Hi Al,
Here are a set of patches that adds a syscall, fsinfo(), that allows
attributes of a filesystem/superblock to be queried. Attribute values are
of four basic types:
(1) Version dependent-length structure (size defined by type).
(2) Variable-length string (up to PAGE_SIZE).
(3) Array of fixed-length structures (up to INT_MAX size).
(4) Opaque blob (up to INT_MAX size).
Attributes can have multiple values in up to two dimensions and all the
values of a particular attribute must have the same type.
Note that the attribute values *are* allowed to vary between dentries
within a single superblock, depending on the specific dentry that you're
looking at.
I've tried to make the interface as light as possible, so integer/enum
attribute selector rather than string and the core does all the allocation
and extensibility support work rather than leaving that to the filesystems.
That means that for the first two attribute types, sb->s_op->fsinfo() may
assume that the provided buffer is always present and always big enough.
Further, this removes the possibility of the filesystem gaining access to the
userspace buffer.
fsinfo() allows a variety of information to be retrieved about a filesystem
and the mount topology:
(1) General superblock attributes:
- The amount of space/free space in a filesystem (as statfs()).
- Filesystem identifiers (UUID, volume label, device numbers, ...)
- The limits on a filesystem's capabilities
- Information on supported statx fields and attributes and IOC flags.
- A variety single-bit flags indicating supported capabilities.
- Timestamp resolution and range.
- Sources (as per mount(2), but fsconfig() allows multiple sources).
- In-filesystem filename format information.
- Filesystem parameters ("mount -o xxx"-type things).
- LSM parameters (again "mount -o xxx"-type things).
(2) Filesystem-specific superblock attributes:
- Server names and addresses.
- Cell name.
(3) Filesystem configuration metadata attributes:
- Filesystem parameter type descriptions.
- Name -> parameter mappings.
- Simple enumeration name -> value mappings.
(4) Mount topology:
- General information about a mount object.
- Mount device name(s).
- Children of a mount object and their relative paths.
(5) Information about what the fsinfo() syscall itself supports, including
the number of attibutes supported and the number of capability bits
supported.
The system is extensible:
(1) New attributes can be added. There is no requirement that a
filesystem implement every attribute. Note that the core VFS keeps a
table of types and sizes so it can handle future extensibility rather
than delegating this to the filesystems.
(2) Version length-dependent structure attributes can be made larger and
have additional information tacked on the end, provided it keeps the
layout of the existing fields. If an older process asks for a shorter
structure, it will only be given the bits it asks for. If a newer
process asks for a longer structure on an older kernel, the extra
space will be set to 0. In all cases, the size of the data actually
available is returned.
In essence, the size of a structure is that structure's version: a
smaller size is an earlier version and a later version includes
everything that the earlier version did.
(3) New single-bit capability flags can be added. This is a structure-typed
attribute and, as such, (2) applies. Any bits you wanted but the kernel
doesn't support are automatically set to 0.
If a filesystem-specific attribute is added, it should just take up the next
number in the enumeration. Currently, I do not intend that the number space
should be subdivided between interested parties.
fsinfo() may be called like the following, for example:
struct fsinfo_params params = {
.at_flags = AT_SYMLINK_NOFOLLOW,
.request = FSINFO_ATTR_SERVER_ADDRESS;
.Nth = 2;
.Mth = 1;
};
struct fsinfo_server_address address;
len = fsinfo(AT_FDCWD, "/afs/grand.central.org/doc", ¶ms,
&address, sizeof(address));
The above example would query a network filesystem, such as AFS or NFS, and
ask what the 2nd address (Mth) of the 3rd server (Nth) that the superblock is
using is. Whereas:
struct fsinfo_params params = {
.at_flags = AT_SYMLINK_NOFOLLOW,
.request = FSINFO_ATTR_CELL_NAME;
};
char cell_name[256];
len = fsinfo(AT_FDCWD, "/afs/grand.central.org/doc", ¶ms,
&cell_name, sizeof(cell_name));
would retrieve the name of an AFS cell as a string.
fsinfo() can also be used to query a context from fsopen() or fspick():
fd = fsopen("ext4", 0);
struct fsinfo_params params = {
.request = FSINFO_ATTR_PARAM_DESCRIPTION;
};
struct fsinfo_param_description desc;
fsinfo(fd, NULL, ¶ms, &desc, sizeof(desc));
even if that context doesn't currently have a superblock attached (though if
there's no superblock attached, only filesystem-specific things like parameter
descriptions can be accessed).
The patches can be found here also:
https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git
on branch:
fsinfo
===================
SIGNIFICANT CHANGES
===================
ver #14:
(*) Increase to 128-bit the fields for number of blocks and files in the
filesystem and also the max file size and max inode number fields.
(*) Increase to 64-bit the fields for max hard links and max xattr body
length.
(*) Provide struct fsinfo_timestamp_one to represent the characteristics
of a single timestamp and move the range into it. FAT, for example,
has different ranges for different timestamps. Each timestamp is then
represented by one of these structs.
(*) Don't expose MS_* flags (such as MS_RDONLY) through this interface as
they ought to be considered deprecated; instead anyone who wants them
should parse FSINFO_ATTR_PARAMETERS for the string equivalents.
(*) Add a flag, AT_FSINFO_FROM_FSOPEN, to indicate that the fd being
accessed is from fsopen()/fspick() and that fsinfo() should look
inside and access the filesystem referred to by the fs_context.
(*) If the filesystem implements FSINFO_ATTR_PARAMETERS for itself, don't
automatically include flags for the SB_* bits that are normally
rendered by, say, /proc/mounts (such as SB_RDONLY). Rather, a helper
is provided that the filesystem must call with an appropriately
wangled s_flags.
(*) Drop the NFS fsinfo patch for now as NFS fs_context support is
unlikely to get upstream in the upcoming merge window.
ver #13:
(*) Provided a "fixed-struct array" type so that the list of children of a
mount and all their change counters can be read atomically.
(*) Additional filesystem examples.
(*) Documented the API.
ver #12:
(*) Rename ->get_fsinfo() to ->fsinfo().
(*) Pass the path through to to ->fsinfo() as it's needed for NFS to
retrocalculate the source name.
(*) Indicated which is the source parameter in the param-description
attribute.
(*) Dropped the realm attribute.
David
---
David Howells (17):
vfs: syscall: Add fsinfo() to query filesystem information
fsinfo: Add syscalls to other arches
vfs: Allow fsinfo() to query what's in an fs_context
vfs: Allow fsinfo() to be used to query an fs parameter description
vfs: Implement parameter value retrieval with fsinfo()
fsinfo: Implement retrieval of LSM parameters with fsinfo()
vfs: Introduce a non-repeating system-unique superblock ID
vfs: Allow fsinfo() to look up a mount object by ID
vfs: Add mount notification count
vfs: Allow mount information to be queried by fsinfo()
vfs: fsinfo sample: Mount listing program
fsinfo: Add API documentation
hugetlbfs: Add support for fsinfo()
kernfs, cgroup: Add fsinfo support
fsinfo: Support SELinux superblock parameter retrieval
fsinfo: Support Smack superblock parameter retrieval
afs: Support fsinfo()
Ian Kent (8):
fsinfo: proc - add sb operation fsinfo()
fsinfo: autofs - add sb operation fsinfo()
fsinfo: shmem - add tmpfs sb operation fsinfo()
fsinfo: devpts - add sb operation fsinfo()
fsinfo: pstore - add sb operation fsinfo()
fsinfo: debugfs - add sb operation fsinfo()
fsinfo: bpf - add sb operation fsinfo()
fsinfo: ufs - add sb operation fsinfo()
Documentation/filesystems/fsinfo.rst | 596 ++++++++++++++++++
arch/alpha/kernel/syscalls/syscall.tbl | 1
arch/arm/tools/syscall.tbl | 1
arch/arm64/include/asm/unistd.h | 2
arch/ia64/kernel/syscalls/syscall.tbl | 1
arch/m68k/kernel/syscalls/syscall.tbl | 1
arch/microblaze/kernel/syscalls/syscall.tbl | 1
arch/mips/kernel/syscalls/syscall_n32.tbl | 1
arch/mips/kernel/syscalls/syscall_n64.tbl | 1
arch/mips/kernel/syscalls/syscall_o32.tbl | 1
arch/parisc/kernel/syscalls/syscall.tbl | 1
arch/powerpc/kernel/syscalls/syscall.tbl | 1
arch/s390/kernel/syscalls/syscall.tbl | 1
arch/sh/kernel/syscalls/syscall.tbl | 1
arch/sparc/kernel/syscalls/syscall.tbl | 1
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
arch/xtensa/kernel/syscalls/syscall.tbl | 1
fs/Kconfig | 7
fs/Makefile | 1
fs/afs/internal.h | 1
fs/afs/super.c | 180 +++++-
fs/autofs/inode.c | 64 ++
fs/d_path.c | 2
fs/debugfs/inode.c | 38 +
fs/devpts/inode.c | 43 +
fs/fsinfo.c | 877 +++++++++++++++++++++++++++
fs/hugetlbfs/inode.c | 57 ++
fs/internal.h | 11
fs/kernfs/mount.c | 20 +
fs/mount.h | 22 +
fs/namespace.c | 307 +++++++++
fs/proc/inode.c | 37 +
fs/pstore/inode.c | 32 +
fs/statfs.c | 2
fs/super.c | 24 +
fs/ufs/super.c | 58 ++
include/linux/fs.h | 8
include/linux/fsinfo.h | 70 ++
include/linux/kernfs.h | 4
include/linux/lsm_hooks.h | 13
include/linux/security.h | 11
include/linux/syscalls.h | 4
include/uapi/asm-generic/unistd.h | 4
include/uapi/linux/fcntl.h | 3
include/uapi/linux/fsinfo.h | 319 ++++++++++
kernel/bpf/inode.c | 25 +
kernel/cgroup/cgroup-v1.c | 44 +
kernel/cgroup/cgroup.c | 19 +
kernel/sys_ni.c | 1
mm/shmem.c | 72 ++
samples/vfs/Makefile | 9
samples/vfs/test-fs-query.c | 138 ++++
samples/vfs/test-fsinfo.c | 682 +++++++++++++++++++++
samples/vfs/test-mntinfo.c | 241 +++++++
security/security.c | 12
security/selinux/hooks.c | 41 +
security/selinux/include/security.h | 2
security/selinux/ss/services.c | 49 ++
security/smack/smack_lsm.c | 43 +
60 files changed, 4202 insertions(+), 9 deletions(-)
create mode 100644 Documentation/filesystems/fsinfo.rst
create mode 100644 fs/fsinfo.c
create mode 100644 include/linux/fsinfo.h
create mode 100644 include/uapi/linux/fsinfo.h
create mode 100644 samples/vfs/test-fs-query.c
create mode 100644 samples/vfs/test-fsinfo.c
create mode 100644 samples/vfs/test-mntinfo.c
Add the fsinfo syscall to the other arches.
Signed-off-by: David Howells <[email protected]>
---
arch/alpha/kernel/syscalls/syscall.tbl | 1 +
arch/arm/tools/syscall.tbl | 1 +
arch/arm64/include/asm/unistd.h | 2 +-
arch/ia64/kernel/syscalls/syscall.tbl | 1 +
arch/m68k/kernel/syscalls/syscall.tbl | 1 +
arch/microblaze/kernel/syscalls/syscall.tbl | 1 +
arch/mips/kernel/syscalls/syscall_n32.tbl | 1 +
arch/mips/kernel/syscalls/syscall_n64.tbl | 1 +
arch/mips/kernel/syscalls/syscall_o32.tbl | 1 +
arch/parisc/kernel/syscalls/syscall.tbl | 1 +
arch/powerpc/kernel/syscalls/syscall.tbl | 1 +
arch/s390/kernel/syscalls/syscall.tbl | 1 +
arch/sh/kernel/syscalls/syscall.tbl | 1 +
arch/sparc/kernel/syscalls/syscall.tbl | 1 +
arch/xtensa/kernel/syscalls/syscall.tbl | 1 +
15 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl
index 9e7704e44f6d..624d01c3c8eb 100644
--- a/arch/alpha/kernel/syscalls/syscall.tbl
+++ b/arch/alpha/kernel/syscalls/syscall.tbl
@@ -473,3 +473,4 @@
541 common fsconfig sys_fsconfig
542 common fsmount sys_fsmount
543 common fspick sys_fspick
+544 common fsinfo sys_fsinfo
diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
index aaf479a9e92d..ad608b49808c 100644
--- a/arch/arm/tools/syscall.tbl
+++ b/arch/arm/tools/syscall.tbl
@@ -447,3 +447,4 @@
431 common fsconfig sys_fsconfig
432 common fsmount sys_fsmount
433 common fspick sys_fspick
+434 common fsinfo sys_fsinfo
diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
index 70e6882853c0..e8f7d95a1481 100644
--- a/arch/arm64/include/asm/unistd.h
+++ b/arch/arm64/include/asm/unistd.h
@@ -44,7 +44,7 @@
#define __ARM_NR_compat_set_tls (__ARM_NR_COMPAT_BASE + 5)
#define __ARM_NR_COMPAT_END (__ARM_NR_COMPAT_BASE + 0x800)
-#define __NR_compat_syscalls 434
+#define __NR_compat_syscalls 435
#endif
#define __ARCH_WANT_SYS_CLONE
diff --git a/arch/ia64/kernel/syscalls/syscall.tbl b/arch/ia64/kernel/syscalls/syscall.tbl
index e01df3f2f80d..68314763ad16 100644
--- a/arch/ia64/kernel/syscalls/syscall.tbl
+++ b/arch/ia64/kernel/syscalls/syscall.tbl
@@ -354,3 +354,4 @@
431 common fsconfig sys_fsconfig
432 common fsmount sys_fsmount
433 common fspick sys_fspick
+434 common fsinfo sys_fsinfo
diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl
index 7e3d0734b2f3..ee73a7534b1b 100644
--- a/arch/m68k/kernel/syscalls/syscall.tbl
+++ b/arch/m68k/kernel/syscalls/syscall.tbl
@@ -433,3 +433,4 @@
431 common fsconfig sys_fsconfig
432 common fsmount sys_fsmount
433 common fspick sys_fspick
+434 common fsinfo sys_fsinfo
diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl
index 26339e417695..7bc067f4b713 100644
--- a/arch/microblaze/kernel/syscalls/syscall.tbl
+++ b/arch/microblaze/kernel/syscalls/syscall.tbl
@@ -439,3 +439,4 @@
431 common fsconfig sys_fsconfig
432 common fsmount sys_fsmount
433 common fspick sys_fspick
+434 common fsinfo sys_fsinfo
diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl
index 0e2dd68ade57..29b76bd67cc0 100644
--- a/arch/mips/kernel/syscalls/syscall_n32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n32.tbl
@@ -372,3 +372,4 @@
431 n32 fsconfig sys_fsconfig
432 n32 fsmount sys_fsmount
433 n32 fspick sys_fspick
+434 n32 fsinfo sys_fsinfo
diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl
index 5eebfa0d155c..349fb30bb8b5 100644
--- a/arch/mips/kernel/syscalls/syscall_n64.tbl
+++ b/arch/mips/kernel/syscalls/syscall_n64.tbl
@@ -348,3 +348,4 @@
431 n64 fsconfig sys_fsconfig
432 n64 fsmount sys_fsmount
433 n64 fspick sys_fspick
+434 n64 fsinfo sys_fsinfo
diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
index 3cc1374e02d0..71057426b503 100644
--- a/arch/mips/kernel/syscalls/syscall_o32.tbl
+++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
@@ -421,3 +421,4 @@
431 o32 fsconfig sys_fsconfig
432 o32 fsmount sys_fsmount
433 o32 fspick sys_fspick
+434 o32 fsinfo sys_fsinfo
diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
index c9e377d59232..32cff48a1ebd 100644
--- a/arch/parisc/kernel/syscalls/syscall.tbl
+++ b/arch/parisc/kernel/syscalls/syscall.tbl
@@ -430,3 +430,4 @@
431 common fsconfig sys_fsconfig
432 common fsmount sys_fsmount
433 common fspick sys_fspick
+434 common fsinfo sys_fsinfo
diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
index 103655d84b4b..e5755eb6fb84 100644
--- a/arch/powerpc/kernel/syscalls/syscall.tbl
+++ b/arch/powerpc/kernel/syscalls/syscall.tbl
@@ -515,3 +515,4 @@
431 common fsconfig sys_fsconfig
432 common fsmount sys_fsmount
433 common fspick sys_fspick
+434 common fsinfo sys_fsinfo
diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
index e822b2964a83..bcd54116e107 100644
--- a/arch/s390/kernel/syscalls/syscall.tbl
+++ b/arch/s390/kernel/syscalls/syscall.tbl
@@ -436,3 +436,4 @@
431 common fsconfig sys_fsconfig sys_fsconfig
432 common fsmount sys_fsmount sys_fsmount
433 common fspick sys_fspick sys_fspick
+434 common fsinfo sys_fsinfo sys_fsinfo
diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl
index 016a727d4357..0320a5c63cbd 100644
--- a/arch/sh/kernel/syscalls/syscall.tbl
+++ b/arch/sh/kernel/syscalls/syscall.tbl
@@ -436,3 +436,4 @@
431 common fsconfig sys_fsconfig
432 common fsmount sys_fsmount
433 common fspick sys_fspick
+434 common fsinfo sys_fsinfo
diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl
index e047480b1605..f81b1f9402bd 100644
--- a/arch/sparc/kernel/syscalls/syscall.tbl
+++ b/arch/sparc/kernel/syscalls/syscall.tbl
@@ -479,3 +479,4 @@
431 common fsconfig sys_fsconfig
432 common fsmount sys_fsmount
433 common fspick sys_fspick
+434 common fsinfo sys_fsinfo
diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl
index 5fa0ee1c8e00..729795148850 100644
--- a/arch/xtensa/kernel/syscalls/syscall.tbl
+++ b/arch/xtensa/kernel/syscalls/syscall.tbl
@@ -404,3 +404,4 @@
431 common fsconfig sys_fsconfig
432 common fsmount sys_fsmount
433 common fspick sys_fspick
+434 common fsinfo sys_fsinfo
Allow fsinfo() to be used to query the filesystem attached to an fs_context
once a superblock has been created or if it comes from fspick().
The caller must specify AT_FSINFO_FROM_FSOPEN in the parameters and must
supply the fd from fsopen() as dfd and must set filename to NULL.
This is done with something like:
fd = fsopen("ext4", 0);
...
struct fsinfo_params params = {
.at_flags = AT_FSINFO_FROM_FSOPEN;
...
};
fsinfo(fd, NULL, ¶ms, ...);
Signed-off-by: David Howells <[email protected]>
---
fs/fsinfo.c | 46 +++++++++++++++++++++++++++++++++++++++++++-
fs/statfs.c | 2 +-
include/uapi/linux/fcntl.h | 2 ++
3 files changed, 48 insertions(+), 2 deletions(-)
diff --git a/fs/fsinfo.c b/fs/fsinfo.c
index 49b46f96dda3..c24701f994d1 100644
--- a/fs/fsinfo.c
+++ b/fs/fsinfo.c
@@ -8,6 +8,7 @@
#include <linux/security.h>
#include <linux/uaccess.h>
#include <linux/fsinfo.h>
+#include <linux/fs_context.h>
#include <uapi/linux/mount.h>
#include "internal.h"
@@ -340,6 +341,42 @@ static int vfs_fsinfo_fd(unsigned int fd, struct fsinfo_kparams *params)
return ret;
}
+/*
+ * Allow access to an fs_context object as created by fsopen() or fspick().
+ */
+static int vfs_fsinfo_fscontext(int fd, struct fsinfo_kparams *params)
+{
+ struct fs_context *fc;
+ struct fd f = fdget(fd);
+ int ret;
+
+ if (!f.file)
+ return -EBADF;
+
+ ret = -EINVAL;
+ if (f.file->f_op == &fscontext_fops)
+ goto out_f;
+ ret = -EOPNOTSUPP;
+ if (fc->ops == &legacy_fs_context_ops)
+ goto out_f;
+
+ ret = mutex_lock_interruptible(&fc->uapi_mutex);
+ if (ret == 0) {
+ ret = -EIO;
+ if (fc->root) {
+ struct path path = { .dentry = fc->root };
+
+ ret = vfs_fsinfo(&path, params);
+ }
+
+ mutex_unlock(&fc->uapi_mutex);
+ }
+
+out_f:
+ fdput(f);
+ return ret;
+}
+
/*
* Return buffer information by requestable attribute.
*
@@ -445,6 +482,9 @@ SYSCALL_DEFINE5(fsinfo,
params.request = user_params.request;
params.Nth = user_params.Nth;
params.Mth = user_params.Mth;
+
+ if ((params.at_flags & AT_FSINFO_FROM_FSOPEN) && filename)
+ return -EINVAL;
} else {
params.request = FSINFO_ATTR_STATFS;
}
@@ -453,6 +493,8 @@ SYSCALL_DEFINE5(fsinfo,
user_buf_size = 0;
user_buffer = NULL;
}
+ if ((params.at_flags & AT_FSINFO_FROM_FSOPEN) && filename)
+ return -EINVAL;
/* Allocate an appropriately-sized buffer. We will truncate the
* contents when we write the contents back to userspace.
@@ -500,7 +542,9 @@ SYSCALL_DEFINE5(fsinfo,
if (!params.buffer)
goto error_scratch;
- if (filename)
+ if (params.at_flags & AT_FSINFO_FROM_FSOPEN)
+ ret = vfs_fsinfo_fscontext(dfd, ¶ms);
+ else if (filename)
ret = vfs_fsinfo_path(dfd, filename, ¶ms);
else
ret = vfs_fsinfo_fd(dfd, ¶ms);
diff --git a/fs/statfs.c b/fs/statfs.c
index eea7af6f2f22..b9b63d9f4f24 100644
--- a/fs/statfs.c
+++ b/fs/statfs.c
@@ -86,7 +86,7 @@ int vfs_statfs(const struct path *path, struct kstatfs *buf)
int error;
error = statfs_by_dentry(path->dentry, buf);
- if (!error)
+ if (!error && path->mnt)
buf->f_flags = calculate_f_flags(path->mnt);
return error;
}
diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index 1d338357df8a..6a2402a8fa30 100644
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -91,6 +91,8 @@
#define AT_STATX_FORCE_SYNC 0x2000 /* - Force the attributes to be sync'd with the server */
#define AT_STATX_DONT_SYNC 0x4000 /* - Don't sync attributes with the server */
+#define AT_FSINFO_FROM_FSOPEN 0x2000 /* Examine the fs_context attached to dfd by fsopen() */
+
#define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */
Provide fsinfo() attributes that can be used to query a filesystem
parameter description. To do this, fsinfo() can be called on an
fs_context that doesn't yet have a superblock created and attached.
It can be obtained by doing, for example:
fd = fsopen("ext4", 0);
struct fsinfo_param_name name;
struct fsinfo_params params = {
.at_flags = AT_FSINFO_FROM_FSOPEN,
.request = fsinfo_attr_param_name,
.Nth = 3,
};
fsinfo(fd, NULL, ¶ms, &name, sizeof(name));
to query the 4th parameter name in the name to parameter ID mapping table.
Signed-off-by: David Howells <[email protected]>
---
fs/fsinfo.c | 101 +++++++++++++++++++++++++++++++
include/uapi/linux/fsinfo.h | 58 ++++++++++++++++++
samples/vfs/Makefile | 2 +
samples/vfs/test-fs-query.c | 138 +++++++++++++++++++++++++++++++++++++++++++
samples/vfs/test-fsinfo.c | 14 ++++
5 files changed, 311 insertions(+), 2 deletions(-)
create mode 100644 samples/vfs/test-fs-query.c
diff --git a/fs/fsinfo.c b/fs/fsinfo.c
index c24701f994d1..9e2a25510b88 100644
--- a/fs/fsinfo.c
+++ b/fs/fsinfo.c
@@ -9,6 +9,7 @@
#include <linux/uaccess.h>
#include <linux/fsinfo.h>
#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
#include <uapi/linux/mount.h>
#include "internal.h"
@@ -223,12 +224,87 @@ static int fsinfo_generic_name_encoding(struct path *path, char *buf)
return sizeof(encoding) - 1;
}
+static int fsinfo_generic_param_description(struct file_system_type *f,
+ struct fsinfo_kparams *params)
+{
+ const struct fs_parameter_description *desc = f->parameters;
+ const struct fs_parameter_spec *s;
+ const struct fs_parameter_enum *e;
+ struct fsinfo_param_description *p = params->buffer;
+
+ if (desc && desc->specs) {
+ for (s = desc->specs; s->name; s++) {}
+ p->nr_params = s - desc->specs;
+ if (desc->enums) {
+ for (e = desc->enums; e->name[0]; e++) {}
+ p->nr_enum_names = e - desc->enums;
+ }
+ }
+
+ return sizeof(*p);
+}
+
+static int fsinfo_generic_param_specification(struct file_system_type *f,
+ struct fsinfo_kparams *params)
+{
+ const struct fs_parameter_description *desc = f->parameters;
+ const struct fs_parameter_spec *s;
+ struct fsinfo_param_specification *p = params->buffer;
+ unsigned int nth = params->Nth;
+
+ if (!desc || !desc->specs)
+ return -ENODATA;
+
+ for (s = desc->specs; s->name; s++) {
+ if (nth == 0)
+ goto found;
+ nth--;
+ }
+
+ return -ENODATA;
+
+found:
+ p->type = s->type;
+ p->flags = s->flags;
+ p->opt = s->opt;
+ strlcpy(p->name, s->name, sizeof(p->name));
+ return sizeof(*p);
+}
+
+static int fsinfo_generic_param_enum(struct file_system_type *f,
+ struct fsinfo_kparams *params)
+{
+ const struct fs_parameter_description *desc = f->parameters;
+ const struct fs_parameter_enum *e;
+ struct fsinfo_param_enum *p = params->buffer;
+ unsigned int nth = params->Nth;
+
+ if (!desc || !desc->enums)
+ return -ENODATA;
+
+ for (e = desc->enums; e->name; e++) {
+ if (nth == 0)
+ goto found;
+ nth--;
+ }
+
+ return -ENODATA;
+
+found:
+ p->opt = e->opt;
+ strlcpy(p->name, e->name, sizeof(p->name));
+ return sizeof(*p);
+}
+
/*
* Implement some queries generically from stuff in the superblock.
*/
int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
{
+ struct file_system_type *fs = path->dentry->d_sb->s_type;
+
#define _gen(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(path, params->buffer)
+#define _genf(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(fs, params)
switch (params->request) {
case _gen(STATFS, statfs);
@@ -240,6 +316,9 @@ int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
case _gen(VOLUME_UUID, volume_uuid);
case _gen(VOLUME_ID, volume_id);
case _gen(NAME_ENCODING, name_encoding);
+ case _genf(PARAM_DESCRIPTION, param_description);
+ case _genf(PARAM_SPECIFICATION, param_specification);
+ case _genf(PARAM_ENUM, param_enum);
default:
return -EOPNOTSUPP;
}
@@ -342,10 +421,11 @@ static int vfs_fsinfo_fd(unsigned int fd, struct fsinfo_kparams *params)
}
/*
- * Allow access to an fs_context object as created by fsopen() or fspick().
+ * Allow an fs_context object as created by fsopen() or fspick() to be queried.
*/
static int vfs_fsinfo_fscontext(int fd, struct fsinfo_kparams *params)
{
+ struct file_system_type *fs;
struct fs_context *fc;
struct fd f = fdget(fd);
int ret;
@@ -354,12 +434,26 @@ static int vfs_fsinfo_fscontext(int fd, struct fsinfo_kparams *params)
return -EBADF;
ret = -EINVAL;
- if (f.file->f_op == &fscontext_fops)
+ if (f.file->f_op != &fscontext_fops)
goto out_f;
+ fc = f.file->private_data;
+ fs = fc->fs_type;
+
ret = -EOPNOTSUPP;
if (fc->ops == &legacy_fs_context_ops)
goto out_f;
+ /* Filesystem parameter query is static information and doesn't need a
+ * lock to read it, nor even a dentry or superblock.
+ */
+ switch (params->request) {
+ case _genf(PARAM_DESCRIPTION, param_description);
+ case _genf(PARAM_SPECIFICATION, param_specification);
+ case _genf(PARAM_ENUM, param_enum);
+ default:
+ break;
+ }
+
ret = mutex_lock_interruptible(&fc->uapi_mutex);
if (ret == 0) {
ret = -EIO;
@@ -432,6 +526,9 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
FSINFO_STRING (VOLUME_NAME, -),
FSINFO_STRING (NAME_ENCODING, -),
FSINFO_STRING (NAME_CODEPAGE, -),
+ FSINFO_STRUCT (PARAM_DESCRIPTION, param_description),
+ FSINFO_STRUCT_N (PARAM_SPECIFICATION, param_specification),
+ FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
};
/**
diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
index a7a7c731d992..9d929d2f7eee 100644
--- a/include/uapi/linux/fsinfo.h
+++ b/include/uapi/linux/fsinfo.h
@@ -27,6 +27,9 @@ enum fsinfo_attribute {
FSINFO_ATTR_VOLUME_NAME = 9, /* Volume name (string) */
FSINFO_ATTR_NAME_ENCODING = 10, /* Filename encoding (string) */
FSINFO_ATTR_NAME_CODEPAGE = 11, /* Filename codepage (string) */
+ FSINFO_ATTR_PARAM_DESCRIPTION = 12, /* General fs parameter description */
+ FSINFO_ATTR_PARAM_SPECIFICATION = 13, /* Nth parameter specification */
+ FSINFO_ATTR_PARAM_ENUM = 14, /* Nth enum-to-val */
FSINFO_ATTR__NR
};
@@ -216,4 +219,59 @@ struct fsinfo_fsinfo {
__u32 max_cap; /* Number of supported capabilities (fsinfo_cap__nr) */
};
+/*
+ * Information struct for fsinfo(fsinfo_attr_param_description).
+ *
+ * Query the parameter set for a filesystem.
+ */
+struct fsinfo_param_description {
+ __u32 nr_params; /* Number of individual parameters */
+ __u32 nr_enum_names; /* Number of enum names */
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_param_specification).
+ *
+ * Query the specification of the Nth filesystem parameter.
+ */
+struct fsinfo_param_specification {
+ __u32 type; /* enum fsinfo_param_specification_type */
+ __u32 flags; /* Qualifiers */
+ __u32 opt; /* Corresponding params have same ID here */
+ char name[240];
+};
+
+enum fsinfo_param_specification_type {
+ FSINFO_PARAM_SPEC_NOT_DEFINED = 0,
+ FSINFO_PARAM_SPEC_IS_FLAG = 1,
+ FSINFO_PARAM_SPEC_IS_BOOL = 2,
+ FSINFO_PARAM_SPEC_IS_U32 = 3,
+ FSINFO_PARAM_SPEC_IS_U32_OCTAL = 4,
+ FSINFO_PARAM_SPEC_IS_U32_HEX = 5,
+ FSINFO_PARAM_SPEC_IS_S32 = 6,
+ FSINFO_PARAM_SPEC_IS_U64 = 7,
+ FSINFO_PARAM_SPEC_IS_ENUM = 8,
+ FSINFO_PARAM_SPEC_IS_STRING = 9,
+ FSINFO_PARAM_SPEC_IS_BLOB = 10,
+ FSINFO_PARAM_SPEC_IS_BLOCKDEV = 11,
+ FSINFO_PARAM_SPEC_IS_PATH = 12,
+ FSINFO_PARAM_SPEC_IS_FD = 13,
+ NR__FSINFO_PARAM_SPEC
+};
+
+#define FSINFO_PARAM_SPEC_VALUE_IS_OPTIONAL 0X00000001
+#define FSINFO_PARAM_SPEC_PREFIX_NO_IS_NEG 0X00000002
+#define FSINFO_PARAM_SPEC_EMPTY_STRING_IS_NEG 0X00000004
+#define FSINFO_PARAM_SPEC_DEPRECATED 0X00000008
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_param_enum).
+ *
+ * Query the Nth filesystem enum parameter value name.
+ */
+struct fsinfo_param_enum {
+ __u32 opt; /* ->opt of the relevant parameter specification */
+ char name[252]; /* Name of the enum value */
+};
+
#endif /* _UAPI_LINUX_FSINFO_H */
diff --git a/samples/vfs/Makefile b/samples/vfs/Makefile
index d3cc8e9a4fd8..3c542d3b9479 100644
--- a/samples/vfs/Makefile
+++ b/samples/vfs/Makefile
@@ -1,6 +1,7 @@
# List of programs to build
hostprogs-y := \
test-fsinfo \
+ test-fs-query \
test-fsmount \
test-statx
@@ -10,5 +11,6 @@ always := $(hostprogs-y)
HOSTCFLAGS_test-fsinfo.o += -I$(objtree)/usr/include
HOSTLDLIBS_test-fsinfo += -lm
+HOSTCFLAGS_test-fs-query.o += -I$(objtree)/usr/include
HOSTCFLAGS_test-fsmount.o += -I$(objtree)/usr/include
HOSTCFLAGS_test-statx.o += -I$(objtree)/usr/include
diff --git a/samples/vfs/test-fs-query.c b/samples/vfs/test-fs-query.c
new file mode 100644
index 000000000000..7572411ddb7e
--- /dev/null
+++ b/samples/vfs/test-fs-query.c
@@ -0,0 +1,138 @@
+/* Test using the fsinfo() system call to query mount parameters.
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells ([email protected])
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define _GNU_SOURCE
+#define _ATFILE_SOURCE
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <errno.h>
+#include <time.h>
+#include <math.h>
+#include <sys/syscall.h>
+#include <linux/fsinfo.h>
+#include <linux/fcntl.h>
+#include <sys/stat.h>
+
+#ifndef __NR_fsopen
+#define __NR_fsopen -1
+#endif
+#ifndef __NR_fsinfo
+#define __NR_fsinfo -1
+#endif
+
+static int fsopen(const char *fs_name, unsigned int flags)
+{
+ return syscall(__NR_fsopen, fs_name, flags);
+}
+
+static ssize_t fsinfo(int dfd, const char *filename, struct fsinfo_params *params,
+ void *buffer, size_t buf_size)
+{
+ return syscall(__NR_fsinfo, dfd, filename, params, buffer, buf_size);
+}
+
+static const char *param_types[NR__FSINFO_PARAM_SPEC] = {
+ [FSINFO_PARAM_SPEC_NOT_DEFINED] = "?undef",
+ [FSINFO_PARAM_SPEC_IS_FLAG] = "flag",
+ [FSINFO_PARAM_SPEC_IS_BOOL] = "bool",
+ [FSINFO_PARAM_SPEC_IS_U32] = "u32",
+ [FSINFO_PARAM_SPEC_IS_U32_OCTAL] = "octal",
+ [FSINFO_PARAM_SPEC_IS_U32_HEX] = "hex",
+ [FSINFO_PARAM_SPEC_IS_S32] = "s32",
+ [FSINFO_PARAM_SPEC_IS_U64] = "u64",
+ [FSINFO_PARAM_SPEC_IS_ENUM] = "enum",
+ [FSINFO_PARAM_SPEC_IS_STRING] = "string",
+ [FSINFO_PARAM_SPEC_IS_BLOB] = "binary",
+ [FSINFO_PARAM_SPEC_IS_BLOCKDEV] = "blockdev",
+ [FSINFO_PARAM_SPEC_IS_PATH] = "path",
+ [FSINFO_PARAM_SPEC_IS_FD] = "fd",
+};
+
+/*
+ *
+ */
+int main(int argc, char **argv)
+{
+ struct fsinfo_param_description desc;
+ struct fsinfo_param_specification spec;
+ struct fsinfo_param_enum enum_name;
+
+ struct fsinfo_params params = {
+ .at_flags = AT_FSINFO_FROM_FSOPEN,
+ };
+ int fd;
+
+ if (argc != 2) {
+ printf("Format: test-fs-query <fs_name>\n");
+ exit(2);
+ }
+
+ fd = fsopen(argv[1], 0);
+ if (fd == -1) {
+ perror(argv[1]);
+ exit(1);
+ }
+
+ params.request = FSINFO_ATTR_PARAM_DESCRIPTION;
+ if (fsinfo(fd, NULL, ¶ms, &desc, sizeof(desc)) == -1) {
+ perror("fsinfo/desc");
+ exit(1);
+ }
+
+ printf("Filesystem %s has %u parameters\n", argv[1], desc.nr_params);
+
+ params.request = FSINFO_ATTR_PARAM_SPECIFICATION;
+ for (params.Nth = 0; params.Nth < desc.nr_params; params.Nth++) {
+ char type[32];
+
+ if (fsinfo(fd, NULL, ¶ms, &spec, sizeof(spec)) == -1) {
+ if (errno == ENODATA)
+ break;
+ perror("fsinfo/spec");
+ exit(1);
+ }
+
+ if (spec.type < NR__FSINFO_PARAM_SPEC)
+ strcpy(type, param_types[spec.type]);
+ else
+ sprintf(type, "?%u", spec.type);
+
+ printf("- PARAM[%3u] %-20s %3u %s%s%s%s%s\n",
+ params.Nth,
+ spec.name,
+ spec.opt,
+ type,
+ spec.flags & FSINFO_PARAM_SPEC_VALUE_IS_OPTIONAL ? ",opt" : "",
+ spec.flags & FSINFO_PARAM_SPEC_PREFIX_NO_IS_NEG ? ",neg-no" : "",
+ spec.flags & FSINFO_PARAM_SPEC_EMPTY_STRING_IS_NEG ? ",neg-empty" : "",
+ spec.flags & FSINFO_PARAM_SPEC_DEPRECATED ? ",dep" : "");
+ }
+
+ printf("Filesystem has %u enumeration values\n", desc.nr_enum_names);
+
+ params.request = FSINFO_ATTR_PARAM_ENUM;
+ for (params.Nth = 0; params.Nth < desc.nr_enum_names; params.Nth++) {
+ if (fsinfo(fd, NULL, ¶ms, &enum_name, sizeof(enum_name)) == -1) {
+ if (errno == ENODATA)
+ break;
+ perror("fsinfo/enum");
+ exit(1);
+ }
+ printf("- ENUM[%3u] %3u: %s\n",
+ params.Nth, enum_name.opt, enum_name.name);
+ }
+ return 0;
+}
diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
index 8cce1986df7e..3c6ea3a5c157 100644
--- a/samples/vfs/test-fsinfo.c
+++ b/samples/vfs/test-fsinfo.c
@@ -78,6 +78,9 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
FSINFO_STRING (VOLUME_NAME, volume_name),
FSINFO_STRING (NAME_ENCODING, name_encoding),
FSINFO_STRING (NAME_CODEPAGE, name_codepage),
+ FSINFO_STRUCT (PARAM_DESCRIPTION, param_description),
+ FSINFO_STRUCT_N (PARAM_SPECIFICATION, param_specification),
+ FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
};
#define FSINFO_NAME(X,Y) [FSINFO_ATTR_##X] = #Y
@@ -94,6 +97,9 @@ static const char *fsinfo_attr_names[FSINFO_ATTR__NR] = {
FSINFO_NAME (VOLUME_NAME, volume_name),
FSINFO_NAME (NAME_ENCODING, name_encoding),
FSINFO_NAME (NAME_CODEPAGE, name_codepage),
+ FSINFO_NAME (PARAM_DESCRIPTION, param_description),
+ FSINFO_NAME (PARAM_SPECIFICATION, param_specification),
+ FSINFO_NAME (PARAM_ENUM, param_enum),
};
union reply {
@@ -514,6 +520,14 @@ int main(int argc, char **argv)
}
for (attr = 0; attr <= FSINFO_ATTR__NR; attr++) {
+ switch (attr) {
+ case FSINFO_ATTR_PARAM_DESCRIPTION:
+ case FSINFO_ATTR_PARAM_SPECIFICATION:
+ case FSINFO_ATTR_PARAM_ENUM:
+ /* See test-fs-query.c instead */
+ continue;
+ }
+
Nth = 0;
do {
Mth = 0;
Implement parameter value retrieval with fsinfo() - akin to parsing
/proc/mounts.
This allows all the parameters to be retrieved in one go with:
struct fsinfo_params params = {
.request = FSINFO_ATTR_PARAMETER,
};
Each parameter comes as a pair of blobs with a length tacked on the front
rather than using separators, since any printable character that could be
used as a separator can be found in some value somewhere (including comma).
In fact, cifs allows the separator to be set using the "sep=" option in
parameter parsing.
The length on the front of each blob is 1-3 bytes long. Each byte has a
flag in bit 7 that's set if there are more bytes and clear on the last
byte; bits 0-6 should be shifted and OR'd into the length count. The bytes
are most-significant first.
For example, 0x83 0xf5 0x06 is the length (0x03<<14 | 0x75<<7 | 0x06).
As mentioned, each parameter comes as a pair of blobs in key, value order.
The value has length zero if not present. So, for example:
\x08compress\x04zlib
from btrfs would be equivalent to "compress=zlib" and:
\x02ro\x00\x06noexec\x00
would be equivalent to "ro,noexec".
The test-fsinfo sample program is modified to dump the parameters.
Signed-off-by: David Howells <[email protected]>
---
fs/fsinfo.c | 122 +++++++++++++++++++++++++++++++++++++++++++
include/linux/fsinfo.h | 4 +
include/uapi/linux/fsinfo.h | 1
samples/vfs/test-fsinfo.c | 38 +++++++++++++
4 files changed, 165 insertions(+)
diff --git a/fs/fsinfo.c b/fs/fsinfo.c
index 9e2a25510b88..3b35cedab0df 100644
--- a/fs/fsinfo.c
+++ b/fs/fsinfo.c
@@ -296,6 +296,32 @@ static int fsinfo_generic_param_enum(struct file_system_type *f,
return sizeof(*p);
}
+void fsinfo_note_sb_params(struct fsinfo_kparams *params, unsigned int s_flags)
+{
+ if (s_flags & SB_DIRSYNC)
+ fsinfo_note_param(params, "dirsync", NULL);
+ if (s_flags & SB_LAZYTIME)
+ fsinfo_note_param(params, "lazytime", NULL);
+ if (s_flags & SB_MANDLOCK)
+ fsinfo_note_param(params, "mand", NULL);
+ if (s_flags & SB_POSIXACL)
+ fsinfo_note_param(params, "posixacl", NULL);
+ if (s_flags & SB_RDONLY)
+ fsinfo_note_param(params, "ro", NULL);
+ else
+ fsinfo_note_param(params, "rw", NULL);
+ if (s_flags & SB_SYNCHRONOUS)
+ fsinfo_note_param(params, "sync", NULL);
+}
+EXPORT_SYMBOL(fsinfo_note_sb_params);
+
+static int fsinfo_generic_parameters(struct path *path,
+ struct fsinfo_kparams *params)
+{
+ fsinfo_note_sb_params(params, READ_ONCE(path->dentry->d_sb->s_flags));
+ return params->usage;
+}
+
/*
* Implement some queries generically from stuff in the superblock.
*/
@@ -304,6 +330,7 @@ int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
struct file_system_type *fs = path->dentry->d_sb->s_type;
#define _gen(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(path, params->buffer)
+#define _genp(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(path, params)
#define _genf(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(fs, params)
switch (params->request) {
@@ -319,6 +346,7 @@ int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
case _genf(PARAM_DESCRIPTION, param_description);
case _genf(PARAM_SPECIFICATION, param_specification);
case _genf(PARAM_ENUM, param_enum);
+ case _genp(PARAMETERS, parameters);
default:
return -EOPNOTSUPP;
}
@@ -358,8 +386,16 @@ static int vfs_fsinfo(struct path *path, struct fsinfo_kparams *params)
return fsinfo(path, params);
while (!signal_pending(current)) {
+ if (params->request == FSINFO_ATTR_PARAMETERS) {
+ if (down_read_killable(&dentry->d_sb->s_umount) < 0)
+ return -ERESTARTSYS;
+ }
+
params->usage = 0;
ret = fsinfo(path, params);
+ if (params->request == FSINFO_ATTR_PARAMETERS)
+ up_read(&dentry->d_sb->s_umount);
+
if (ret <= (int)params->buf_size)
return ret; /* Error or it fitted */
kvfree(params->buffer);
@@ -529,6 +565,7 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
FSINFO_STRUCT (PARAM_DESCRIPTION, param_description),
FSINFO_STRUCT_N (PARAM_SPECIFICATION, param_specification),
FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
+ FSINFO_OPAQUE (PARAMETERS, -),
};
/**
@@ -676,3 +713,88 @@ SYSCALL_DEFINE5(fsinfo,
error:
return ret;
}
+
+/*
+ * Store a parameter into the user's parameter buffer. The key is prefixed by
+ * a single byte length (1-127) and the value by one (0-0x7f) or two bytes
+ * (0x80-0x3fff) or three bytes (0x4000-0x1fffff).
+ *
+ * Note that we must always make the size determination, even if the buffer is
+ * already full, so that we can tell the caller how much buffer we actually
+ * need.
+ */
+static void __fsinfo_note_param(struct fsinfo_kparams *params, const char *key,
+ const char *val, unsigned int vlen)
+{
+ char *p;
+ unsigned int usage;
+ int klen, total, vmeta;
+ u8 x;
+
+ klen = strlen(key);
+ BUG_ON(klen < 1 || klen > 127);
+ BUG_ON(vlen > (1 << 21) - 1);
+ BUG_ON(vlen > 0 && !val);
+
+ vmeta = (vlen <= 127) ? 1 : (vlen <= 127 * 127) ? 2 : 3;
+
+ total = 1 + klen + vmeta + vlen;
+
+ usage = params->usage;
+ params->usage = usage + total;
+ if (!params->buffer || params->usage > params->buf_size)
+ return;
+
+ p = params->buffer + usage;
+ *p++ = klen;
+ p = memcpy(p, key, klen);
+ p += klen;
+
+ /* The more significant groups of 7 bits in the size are included in
+ * most->least order with 0x80 OR'd in. The least significant 7 bits
+ * are last with the top bit clear.
+ */
+ x = vlen >> 14;
+ if (x & 0x7f)
+ *p++ = 0x80 | x;
+
+ x = vlen >> 7;
+ if (x & 0x7f)
+ *p++ = 0x80 | x;
+
+ *p++ = vlen & 0x7f;
+ memcpy(p, val, vlen);
+}
+
+/**
+ * fsinfo_note_param - Store a parameter for FSINFO_ATTR_PARAMETERS
+ * @params: The parameter buffer
+ * @key: The parameter's key
+ * @val: The parameter's value (or NULL)
+ */
+void fsinfo_note_param(struct fsinfo_kparams *params, const char *key,
+ const char *val)
+{
+ __fsinfo_note_param(params, key, val, val ? strlen(val) : 0);
+}
+EXPORT_SYMBOL(fsinfo_note_param);
+
+/**
+ * fsinfo_note_paramf - Store a formatted parameter for FSINFO_ATTR_PARAMETERS
+ * @params: The parameter buffer
+ * @key: The parameter's key
+ * @val_fmt: Format string for the parameter's value
+ */
+void fsinfo_note_paramf(struct fsinfo_kparams *params, const char *key,
+ const char *val_fmt, ...)
+{
+ va_list va;
+ int n;
+
+ va_start(va, val_fmt);
+ n = vsnprintf(params->scratch_buffer, 4096, val_fmt, va);
+ va_end(va);
+
+ __fsinfo_note_param(params, key, params->scratch_buffer, n);
+}
+EXPORT_SYMBOL(fsinfo_note_paramf);
diff --git a/include/linux/fsinfo.h b/include/linux/fsinfo.h
index e17e4f0bae18..731931afbf1c 100644
--- a/include/linux/fsinfo.h
+++ b/include/linux/fsinfo.h
@@ -29,6 +29,10 @@ struct fsinfo_kparams {
};
extern int generic_fsinfo(struct path *, struct fsinfo_kparams *);
+extern void fsinfo_note_sb_params(struct fsinfo_kparams *, unsigned int);
+extern void fsinfo_note_param(struct fsinfo_kparams *, const char *, const char *);
+extern void fsinfo_note_paramf(struct fsinfo_kparams *, const char *, const char *, ...)
+ __printf(3, 4);
static inline void fsinfo_set_cap(struct fsinfo_capabilities *c,
enum fsinfo_capability cap)
diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
index 9d929d2f7eee..475cd1c97b12 100644
--- a/include/uapi/linux/fsinfo.h
+++ b/include/uapi/linux/fsinfo.h
@@ -30,6 +30,7 @@ enum fsinfo_attribute {
FSINFO_ATTR_PARAM_DESCRIPTION = 12, /* General fs parameter description */
FSINFO_ATTR_PARAM_SPECIFICATION = 13, /* Nth parameter specification */
FSINFO_ATTR_PARAM_ENUM = 14, /* Nth enum-to-val */
+ FSINFO_ATTR_PARAMETERS = 15, /* Mount parameters (large string) */
FSINFO_ATTR__NR
};
diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
index 3c6ea3a5c157..8cf5b02e333a 100644
--- a/samples/vfs/test-fsinfo.c
+++ b/samples/vfs/test-fsinfo.c
@@ -81,6 +81,7 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
FSINFO_STRUCT (PARAM_DESCRIPTION, param_description),
FSINFO_STRUCT_N (PARAM_SPECIFICATION, param_specification),
FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
+ FSINFO_OVERLARGE (PARAMETERS, -),
};
#define FSINFO_NAME(X,Y) [FSINFO_ATTR_##X] = #Y
@@ -100,6 +101,7 @@ static const char *fsinfo_attr_names[FSINFO_ATTR__NR] = {
FSINFO_NAME (PARAM_DESCRIPTION, param_description),
FSINFO_NAME (PARAM_SPECIFICATION, param_specification),
FSINFO_NAME (PARAM_ENUM, param_enum),
+ FSINFO_NAME (PARAMETERS, parameters),
};
union reply {
@@ -352,6 +354,34 @@ static void dump_fsinfo(enum fsinfo_attribute attr,
dumper(r, size);
}
+static void dump_params(struct fsinfo_attr_info about, union reply *r, int size)
+{
+ int len;
+ char *p = r->buffer, *e = p + size;
+ bool is_key = true;
+
+ while (p < e) {
+ len = 0;
+ while (p[0] & 0x80) {
+ len <<= 7;
+ len |= *p++ & 0x7f;
+ }
+
+ len <<= 7;
+ len |= *p++;
+ if (len > e - p)
+ break;
+ if (is_key || len)
+ printf("%s%*.*s", is_key ? "[PARM] " : "= ", len, len, p);
+ if (is_key)
+ putchar(' ');
+ else
+ putchar('\n');
+ p += len;
+ is_key = !is_key;
+ }
+}
+
/*
* Try one subinstance of an attribute.
*/
@@ -427,6 +457,12 @@ static int try_one(const char *file, struct fsinfo_params *params, bool raw)
return 0;
}
+ switch (params->request) {
+ case FSINFO_ATTR_PARAMETERS:
+ if (ret == 0)
+ return 0;
+ }
+
switch (about.flags & (__FSINFO_N | __FSINFO_NM)) {
case 0:
printf("\e[33m%s\e[m: ",
@@ -469,6 +505,8 @@ static int try_one(const char *file, struct fsinfo_params *params, bool raw)
return 0;
case __FSINFO_OVER:
+ if (params->request == FSINFO_ATTR_PARAMETERS)
+ dump_params(about, r, ret);
return 0;
case __FSINFO_STRUCT_ARRAY:
Add a system call to allow filesystem information to be queried. A request
value can be given to indicate the desired attribute. Support is provided
for enumerating multi-value attributes.
===============
NEW SYSTEM CALL
===============
The new system call looks like:
int ret = fsinfo(int dfd,
const char *filename,
const struct fsinfo_params *params,
void *buffer,
size_t buf_size);
The params parameter optionally points to a block of parameters:
struct fsinfo_params {
__u32 at_flags;
__u32 request;
__u32 Nth;
__u32 Mth;
__u32 __reserved[6];
};
If params is NULL, it is assumed params->request should be
fsinfo_attr_statfs, params->Nth should be 0, params->Mth should be 0 and
params->at_flags should be 0.
If params is given, all of params->__reserved[] must be 0.
dfd, filename and params->at_flags indicate the file to query. There is no
equivalent of lstat() as that can be emulated with fsinfo() by setting
AT_SYMLINK_NOFOLLOW in params->at_flags. There is also no equivalent of
fstat() as that can be emulated by passing a NULL filename to fsinfo() with
the fd of interest in dfd. AT_NO_AUTOMOUNT can also be used to an allow
automount point to be queried without triggering it.
params->request indicates the attribute/attributes to be queried. This can
be one of:
FSINFO_ATTR_STATFS - statfs-style info
FSINFO_ATTR_FSINFO - Information about fsinfo()
FSINFO_ATTR_IDS - Filesystem IDs
FSINFO_ATTR_LIMITS - Filesystem limits
FSINFO_ATTR_SUPPORTS - What's supported in statx(), IOC flags
FSINFO_ATTR_CAPABILITIES - Filesystem capabilities
FSINFO_ATTR_TIMESTAMP_INFO - Inode timestamp info
FSINFO_ATTR_VOLUME_ID - Volume ID (string)
FSINFO_ATTR_VOLUME_UUID - Volume UUID
FSINFO_ATTR_VOLUME_NAME - Volume name (string)
FSINFO_ATTR_NAME_ENCODING - Filename encoding (string)
FSINFO_ATTR_NAME_CODEPAGE - Filename codepage (string)
Some attributes (such as the servers backing a network filesystem) can have
multiple values. These can be enumerated by setting params->Nth and
params->Mth to 0, 1, ... until ENODATA is returned.
buffer and buf_size point to the reply buffer. The buffer is filled up to
the specified size, even if this means truncating the reply. The full size
of the reply is returned. In future versions, this will allow extra fields
to be tacked on to the end of the reply, but anyone not expecting them will
only get the subset they're expecting. If either buffer of buf_size are 0,
no copy will take place and the data size will be returned.
At the moment, this will only work on x86_64 and i386 as it requires the
system call to be wired up.
Signed-off-by: David Howells <[email protected]>
cc: [email protected]
---
arch/x86/entry/syscalls/syscall_32.tbl | 1
arch/x86/entry/syscalls/syscall_64.tbl | 1
fs/Kconfig | 7
fs/Makefile | 1
fs/fsinfo.c | 537 +++++++++++++++++++++++++++++++
include/linux/fs.h | 5
include/linux/fsinfo.h | 66 ++++
include/linux/syscalls.h | 4
include/uapi/asm-generic/unistd.h | 4
include/uapi/linux/fsinfo.h | 219 +++++++++++++
kernel/sys_ni.c | 1
samples/vfs/Makefile | 4
samples/vfs/test-fsinfo.c | 551 ++++++++++++++++++++++++++++++++
13 files changed, 1400 insertions(+), 1 deletion(-)
create mode 100644 fs/fsinfo.c
create mode 100644 include/linux/fsinfo.h
create mode 100644 include/uapi/linux/fsinfo.h
create mode 100644 samples/vfs/test-fsinfo.c
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index ad968b7bac72..03decae51513 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -438,3 +438,4 @@
431 i386 fsconfig sys_fsconfig __ia32_sys_fsconfig
432 i386 fsmount sys_fsmount __ia32_sys_fsmount
433 i386 fspick sys_fspick __ia32_sys_fspick
+434 i386 fsinfo sys_fsinfo __ia32_sys_fsinfo
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index b4e6f9e6204a..ea63df9a1020 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -355,6 +355,7 @@
431 common fsconfig __x64_sys_fsconfig
432 common fsmount __x64_sys_fsmount
433 common fspick __x64_sys_fspick
+434 common fsinfo __x64_sys_fsinfo
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/Kconfig b/fs/Kconfig
index cbbffc8b9ef5..9e7d2f2c0111 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -15,6 +15,13 @@ config VALIDATE_FS_PARSER
Enable this to perform validation of the parameter description for a
filesystem when it is registered.
+config FSINFO
+ bool "Enable the fsinfo() system call"
+ help
+ Enable the file system information querying system call to allow
+ comprehensive information to be retrieved about a filesystem,
+ superblock or mount object.
+
if BLOCK
config FS_IOMAP
diff --git a/fs/Makefile b/fs/Makefile
index c9aea23aba56..26eaeae4b9a1 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -53,6 +53,7 @@ obj-$(CONFIG_SYSCTL) += drop_caches.o
obj-$(CONFIG_FHANDLE) += fhandle.o
obj-$(CONFIG_FS_IOMAP) += iomap.o
+obj-$(CONFIG_FSINFO) += fsinfo.o
obj-y += quota/
diff --git a/fs/fsinfo.c b/fs/fsinfo.c
new file mode 100644
index 000000000000..49b46f96dda3
--- /dev/null
+++ b/fs/fsinfo.c
@@ -0,0 +1,537 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/syscalls.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/statfs.h>
+#include <linux/security.h>
+#include <linux/uaccess.h>
+#include <linux/fsinfo.h>
+#include <uapi/linux/mount.h>
+#include "internal.h"
+
+static u32 calc_mount_attrs(u32 mnt_flags)
+{
+ u32 attrs = 0;
+
+ if (mnt_flags & MNT_READONLY)
+ attrs |= MOUNT_ATTR_RDONLY;
+ if (mnt_flags & MNT_NOSUID)
+ attrs |= MOUNT_ATTR_NOSUID;
+ if (mnt_flags & MNT_NODEV)
+ attrs |= MOUNT_ATTR_NODEV;
+ if (mnt_flags & MNT_NOEXEC)
+ attrs |= MOUNT_ATTR_NOEXEC;
+ if (mnt_flags & MNT_NODIRATIME)
+ attrs |= MOUNT_ATTR_NODIRATIME;
+
+ if (mnt_flags & MNT_NOATIME)
+ attrs |= MOUNT_ATTR_NOATIME;
+ else if (mnt_flags & MNT_RELATIME)
+ attrs |= MOUNT_ATTR_RELATIME;
+ else
+ attrs |= MOUNT_ATTR_STRICTATIME;
+ return attrs;
+}
+
+/*
+ * Get basic filesystem stats from statfs.
+ */
+static int fsinfo_generic_statfs(struct path *path, struct fsinfo_statfs *p)
+{
+ struct kstatfs buf;
+ int ret;
+
+ ret = vfs_statfs(path, &buf);
+ if (ret < 0)
+ return ret;
+
+ p->f_blocks.hi = 0;
+ p->f_blocks.lo = buf.f_blocks;
+ p->f_bfree.hi = 0;
+ p->f_bfree.lo = buf.f_bfree;
+ p->f_bavail.hi = 0;
+ p->f_bavail.lo = buf.f_bavail;
+ p->f_files.hi = 0;
+ p->f_files.lo = buf.f_files;
+ p->f_ffree.hi = 0;
+ p->f_ffree.lo = buf.f_ffree;
+ p->f_favail.hi = 0;
+ p->f_favail.lo = buf.f_ffree;
+ p->f_bsize = buf.f_bsize;
+ p->f_frsize = buf.f_frsize;
+
+ p->mnt_attrs = calc_mount_attrs(path->mnt->mnt_flags);
+ return sizeof(*p);
+}
+
+static int fsinfo_generic_ids(struct path *path, struct fsinfo_ids *p)
+{
+ struct super_block *sb;
+ struct kstatfs buf;
+ int ret;
+
+ ret = vfs_statfs(path, &buf);
+ if (ret < 0 && ret != -ENOSYS)
+ return ret;
+
+ sb = path->dentry->d_sb;
+ p->f_fstype = sb->s_magic;
+ p->f_dev_major = MAJOR(sb->s_dev);
+ p->f_dev_minor = MINOR(sb->s_dev);
+
+ memcpy(&p->f_fsid, &buf.f_fsid, sizeof(p->f_fsid));
+ strlcpy(p->f_fs_name, path->dentry->d_sb->s_type->name,
+ sizeof(p->f_fs_name));
+ return sizeof(*p);
+}
+
+static int fsinfo_generic_limits(struct path *path, struct fsinfo_limits *lim)
+{
+ struct super_block *sb = path->dentry->d_sb;
+
+ lim->max_file_size.hi = 0;
+ lim->max_file_size.lo = sb->s_maxbytes;
+ lim->max_hard_links = sb->s_max_links;
+ lim->max_uid = UINT_MAX;
+ lim->max_gid = UINT_MAX;
+ lim->max_projid = UINT_MAX;
+ lim->max_filename_len = NAME_MAX;
+ lim->max_symlink_len = PAGE_SIZE;
+ lim->max_xattr_name_len = XATTR_NAME_MAX;
+ lim->max_xattr_body_len = XATTR_SIZE_MAX;
+ lim->max_dev_major = 0xffffff;
+ lim->max_dev_minor = 0xff;
+ return sizeof(*lim);
+}
+
+static int fsinfo_generic_supports(struct path *path, struct fsinfo_supports *c)
+{
+ struct super_block *sb = path->dentry->d_sb;
+
+ c->stx_mask = STATX_BASIC_STATS;
+ if (sb->s_d_op && sb->s_d_op->d_automount)
+ c->stx_attributes |= STATX_ATTR_AUTOMOUNT;
+ return sizeof(*c);
+}
+
+static int fsinfo_generic_capabilities(struct path *path,
+ struct fsinfo_capabilities *c)
+{
+ struct super_block *sb = path->dentry->d_sb;
+
+ if (sb->s_mtd)
+ fsinfo_set_cap(c, FSINFO_CAP_IS_FLASH_FS);
+ else if (sb->s_bdev)
+ fsinfo_set_cap(c, FSINFO_CAP_IS_BLOCK_FS);
+
+ if (sb->s_quota_types & QTYPE_MASK_USR)
+ fsinfo_set_cap(c, FSINFO_CAP_USER_QUOTAS);
+ if (sb->s_quota_types & QTYPE_MASK_GRP)
+ fsinfo_set_cap(c, FSINFO_CAP_GROUP_QUOTAS);
+ if (sb->s_quota_types & QTYPE_MASK_PRJ)
+ fsinfo_set_cap(c, FSINFO_CAP_PROJECT_QUOTAS);
+ if (sb->s_d_op && sb->s_d_op->d_automount)
+ fsinfo_set_cap(c, FSINFO_CAP_AUTOMOUNTS);
+ if (sb->s_id[0])
+ fsinfo_set_cap(c, FSINFO_CAP_VOLUME_ID);
+
+ fsinfo_set_cap(c, FSINFO_CAP_HAS_ATIME);
+ fsinfo_set_cap(c, FSINFO_CAP_HAS_CTIME);
+ fsinfo_set_cap(c, FSINFO_CAP_HAS_MTIME);
+ return sizeof(*c);
+}
+
+static const struct fsinfo_timestamp_info fsinfo_default_timestamp_info = {
+ .atime = {
+ .minimum = S64_MIN,
+ .maximum = S64_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+ .mtime = {
+ .minimum = S64_MIN,
+ .maximum = S64_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+ .ctime = {
+ .minimum = S64_MIN,
+ .maximum = S64_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+ .btime = {
+ .minimum = S64_MIN,
+ .maximum = S64_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+};
+
+static int fsinfo_generic_timestamp_info(struct path *path,
+ struct fsinfo_timestamp_info *ts)
+{
+ struct super_block *sb = path->dentry->d_sb;
+ s8 exponent;
+
+ *ts = fsinfo_default_timestamp_info;
+
+
+ if (sb->s_time_gran < 1000000000) {
+ if (sb->s_time_gran < 1000)
+ exponent = -9;
+ else if (sb->s_time_gran < 1000000)
+ exponent = -6;
+ else
+ exponent = -3;
+
+ ts->atime.gran_exponent = exponent;
+ ts->mtime.gran_exponent = exponent;
+ ts->ctime.gran_exponent = exponent;
+ ts->btime.gran_exponent = exponent;
+ }
+
+ return sizeof(*ts);
+}
+
+static int fsinfo_generic_volume_uuid(struct path *path,
+ struct fsinfo_volume_uuid *vu)
+{
+ struct super_block *sb = path->dentry->d_sb;
+
+ memcpy(vu, &sb->s_uuid, sizeof(*vu));
+ return sizeof(*vu);
+}
+
+static int fsinfo_generic_volume_id(struct path *path, char *buf)
+{
+ struct super_block *sb = path->dentry->d_sb;
+ size_t len = strlen(sb->s_id);
+
+ memcpy(buf, sb->s_id, len + 1);
+ return len;
+}
+
+static int fsinfo_generic_name_encoding(struct path *path, char *buf)
+{
+ static const char encoding[] = "utf8";
+
+ memcpy(buf, encoding, sizeof(encoding) - 1);
+ return sizeof(encoding) - 1;
+}
+
+/*
+ * Implement some queries generically from stuff in the superblock.
+ */
+int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+#define _gen(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(path, params->buffer)
+
+ switch (params->request) {
+ case _gen(STATFS, statfs);
+ case _gen(IDS, ids);
+ case _gen(LIMITS, limits);
+ case _gen(SUPPORTS, supports);
+ case _gen(CAPABILITIES, capabilities);
+ case _gen(TIMESTAMP_INFO, timestamp_info);
+ case _gen(VOLUME_UUID, volume_uuid);
+ case _gen(VOLUME_ID, volume_id);
+ case _gen(NAME_ENCODING, name_encoding);
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+EXPORT_SYMBOL(generic_fsinfo);
+
+/*
+ * Retrieve the filesystem info. We make some stuff up if the operation is not
+ * supported.
+ */
+static int vfs_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct dentry *dentry = path->dentry;
+ int (*fsinfo)(struct path *, struct fsinfo_kparams *);
+ int ret;
+
+ if (params->request == FSINFO_ATTR_FSINFO) {
+ struct fsinfo_fsinfo *info = params->buffer;
+
+ info->max_attr = FSINFO_ATTR__NR;
+ info->max_cap = FSINFO_CAP__NR;
+ return sizeof(*info);
+ }
+
+ fsinfo = dentry->d_sb->s_op->fsinfo;
+ if (!fsinfo) {
+ if (!dentry->d_sb->s_op->statfs)
+ return -EOPNOTSUPP;
+ fsinfo = generic_fsinfo;
+ }
+
+ ret = security_sb_statfs(dentry);
+ if (ret)
+ return ret;
+
+ if (!params->overlarge)
+ return fsinfo(path, params);
+
+ while (!signal_pending(current)) {
+ params->usage = 0;
+ ret = fsinfo(path, params);
+ if (ret <= (int)params->buf_size)
+ return ret; /* Error or it fitted */
+ kvfree(params->buffer);
+ params->buffer = NULL;
+ params->buf_size = roundup(ret, PAGE_SIZE);
+ if (params->buf_size > INT_MAX)
+ return -ETOOSMALL;
+ params->buffer = kvmalloc(params->buf_size, GFP_KERNEL);
+ if (!params->buffer)
+ return -ENOMEM;
+ }
+
+ return -ERESTARTSYS;
+}
+
+static int vfs_fsinfo_path(int dfd, const char __user *filename,
+ struct fsinfo_kparams *params)
+{
+ struct path path;
+ unsigned lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
+ int ret = -EINVAL;
+
+ if ((params->at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
+ AT_EMPTY_PATH)) != 0)
+ return -EINVAL;
+
+ if (params->at_flags & AT_SYMLINK_NOFOLLOW)
+ lookup_flags &= ~LOOKUP_FOLLOW;
+ if (params->at_flags & AT_NO_AUTOMOUNT)
+ lookup_flags &= ~LOOKUP_AUTOMOUNT;
+ if (params->at_flags & AT_EMPTY_PATH)
+ lookup_flags |= LOOKUP_EMPTY;
+
+retry:
+ ret = user_path_at(dfd, filename, lookup_flags, &path);
+ if (ret)
+ goto out;
+
+ ret = vfs_fsinfo(&path, params);
+ path_put(&path);
+ if (retry_estale(ret, lookup_flags)) {
+ lookup_flags |= LOOKUP_REVAL;
+ goto retry;
+ }
+out:
+ return ret;
+}
+
+static int vfs_fsinfo_fd(unsigned int fd, struct fsinfo_kparams *params)
+{
+ struct fd f = fdget_raw(fd);
+ int ret = -EBADF;
+
+ if (f.file) {
+ ret = vfs_fsinfo(&f.file->f_path, params);
+ fdput(f);
+ }
+ return ret;
+}
+
+/*
+ * Return buffer information by requestable attribute.
+ *
+ * STRUCT indicates a fixed-size structure with only one instance.
+ * STRUCT_N indicates a 1D array of STRUCT, indexed by Nth
+ * STRUCT_NM indicates a 2D-array of STRUCT, indexed by Nth, Mth
+ * STRING indicates a string with only one instance.
+ * STRING_N indicates a 1D array of STRING, indexed by Nth
+ * STRING_NM indicates a 2D-array of STRING, indexed by Nth, Mth
+ * OPAQUE indicates a blob that can be larger than 4K.
+ * STRUCT_ARRAY indicates an array of structs that can be larger than 4K
+ *
+ * If an entry is marked STRUCT, STRUCT_N or STRUCT_NM then if no buffer is
+ * supplied to sys_fsinfo(), sys_fsinfo() will handle returning the buffer size
+ * without calling vfs_fsinfo() and the filesystem.
+ *
+ * No struct may have more than 4K bytes.
+ */
+struct fsinfo_attr_info {
+ u8 type;
+ u8 flags;
+ u16 size;
+};
+
+#define __FSINFO_STRUCT 0
+#define __FSINFO_STRING 1
+#define __FSINFO_OPAQUE 2
+#define __FSINFO_STRUCT_ARRAY 3
+#define __FSINFO_0 0
+#define __FSINFO_N 0x0001
+#define __FSINFO_NM 0x0002
+
+#define _Z(T, F, S) { .type = __FSINFO_##T, .flags = __FSINFO_##F, .size = S }
+#define FSINFO_STRING(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, 0, 0)
+#define FSINFO_STRUCT(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, 0, sizeof(struct fsinfo_##Y))
+#define FSINFO_STRING_N(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, N, 0)
+#define FSINFO_STRUCT_N(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, N, sizeof(struct fsinfo_##Y))
+#define FSINFO_STRING_NM(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, NM, 0)
+#define FSINFO_STRUCT_NM(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, NM, sizeof(struct fsinfo_##Y))
+#define FSINFO_OPAQUE(X,Y) [FSINFO_ATTR_##X] = _Z(OPAQUE, 0, 0)
+#define FSINFO_STRUCT_ARRAY(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT_ARRAY, 0, sizeof(struct fsinfo_##Y))
+
+static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
+ FSINFO_STRUCT (STATFS, statfs),
+ FSINFO_STRUCT (FSINFO, fsinfo),
+ FSINFO_STRUCT (IDS, ids),
+ FSINFO_STRUCT (LIMITS, limits),
+ FSINFO_STRUCT (CAPABILITIES, capabilities),
+ FSINFO_STRUCT (SUPPORTS, supports),
+ FSINFO_STRUCT (TIMESTAMP_INFO, timestamp_info),
+ FSINFO_STRING (VOLUME_ID, volume_id),
+ FSINFO_STRUCT (VOLUME_UUID, volume_uuid),
+ FSINFO_STRING (VOLUME_NAME, -),
+ FSINFO_STRING (NAME_ENCODING, -),
+ FSINFO_STRING (NAME_CODEPAGE, -),
+};
+
+/**
+ * sys_fsinfo - System call to get filesystem information
+ * @dfd: Base directory to pathwalk from or fd referring to filesystem.
+ * @filename: Filesystem to query or NULL.
+ * @_params: Parameters to define request (or NULL for enhanced statfs).
+ * @user_buffer: Result buffer.
+ * @user_buf_size: Size of result buffer.
+ *
+ * Get information on a filesystem. The filesystem attribute to be queried is
+ * indicated by @_params->request, and some of the attributes can have multiple
+ * values, indexed by @_params->Nth and @_params->Mth. If @_params is NULL,
+ * then the 0th fsinfo_attr_statfs attribute is queried. If an attribute does
+ * not exist, EOPNOTSUPP is returned; if the Nth,Mth value does not exist,
+ * ENODATA is returned.
+ *
+ * On success, the size of the attribute's value is returned. If
+ * @user_buf_size is 0 or @user_buffer is NULL, only the size is returned. If
+ * the size of the value is larger than @user_buf_size, it will be truncated by
+ * the copy. If the size of the value is smaller than @user_buf_size then the
+ * excess buffer space will be cleared. The full size of the value will be
+ * returned, irrespective of how much data is actually placed in the buffer.
+ */
+SYSCALL_DEFINE5(fsinfo,
+ int, dfd, const char __user *, filename,
+ struct fsinfo_params __user *, _params,
+ void __user *, user_buffer, size_t, user_buf_size)
+{
+ struct fsinfo_attr_info info;
+ struct fsinfo_params user_params;
+ struct fsinfo_kparams params;
+ unsigned int result_size;
+ int ret;
+
+ memset(¶ms, 0, sizeof(params));
+
+ if (_params) {
+ if (copy_from_user(&user_params, _params, sizeof(user_params)))
+ return -EFAULT;
+ if (user_params.__reserved[0] ||
+ user_params.__reserved[1] ||
+ user_params.__reserved[2])
+ return -EINVAL;
+ if (user_params.request >= FSINFO_ATTR__NR)
+ return -EOPNOTSUPP;
+ params.at_flags = user_params.at_flags;
+ params.request = user_params.request;
+ params.Nth = user_params.Nth;
+ params.Mth = user_params.Mth;
+ } else {
+ params.request = FSINFO_ATTR_STATFS;
+ }
+
+ if (!user_buffer || !user_buf_size) {
+ user_buf_size = 0;
+ user_buffer = NULL;
+ }
+
+ /* Allocate an appropriately-sized buffer. We will truncate the
+ * contents when we write the contents back to userspace.
+ */
+ info = fsinfo_buffer_info[params.request];
+ if (params.Nth != 0 && !(info.flags & (__FSINFO_N | __FSINFO_NM)))
+ return -ENODATA;
+ if (params.Mth != 0 && !(info.flags & __FSINFO_NM))
+ return -ENODATA;
+
+ switch (info.type) {
+ case __FSINFO_STRUCT:
+ params.buf_size = info.size;
+ if (user_buf_size == 0)
+ return info.size; /* We know how big the buffer should be */
+ break;
+
+ case __FSINFO_STRING:
+ params.buf_size = 4096;
+ break;
+
+ case __FSINFO_OPAQUE:
+ case __FSINFO_STRUCT_ARRAY:
+ /* Opaque blob or array of struct elements. We also create a
+ * buffer that can be used for scratch space.
+ */
+ ret = -ENOMEM;
+ params.scratch_buffer = kmalloc(4096, GFP_KERNEL);
+ if (!params.scratch_buffer)
+ goto error;
+ params.overlarge = true;
+ params.buf_size = 4096;
+ break;
+
+ default:
+ return -ENOBUFS;
+ }
+
+ /* We always allocate a buffer for a string, even if buf_size == 0 and
+ * we're not going to return any data. This means that the filesystem
+ * code needn't care about whether the buffer actually exists or not.
+ */
+ ret = -ENOMEM;
+ params.buffer = kvzalloc(params.buf_size, GFP_KERNEL);
+ if (!params.buffer)
+ goto error_scratch;
+
+ if (filename)
+ ret = vfs_fsinfo_path(dfd, filename, ¶ms);
+ else
+ ret = vfs_fsinfo_fd(dfd, ¶ms);
+ if (ret < 0)
+ goto error_buffer;
+
+ result_size = ret;
+ if (result_size > user_buf_size)
+ result_size = user_buf_size;
+
+ if (result_size > 0 &&
+ copy_to_user(user_buffer, params.buffer, result_size)) {
+ ret = -EFAULT;
+ goto error_buffer;
+ }
+
+ /* Clear any part of the buffer that we won't fill if we're putting a
+ * struct in there. Strings, opaque objects and arrays are expected to
+ * be variable length.
+ */
+ if (info.type == __FSINFO_STRUCT &&
+ user_buf_size > result_size &&
+ clear_user(user_buffer + result_size, user_buf_size - result_size) != 0) {
+ ret = -EFAULT;
+ goto error_buffer;
+ }
+
+error_buffer:
+ kvfree(params.buffer);
+error_scratch:
+ kfree(params.scratch_buffer);
+error:
+ return ret;
+}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6a38b7124143..71ce3b054c42 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -66,6 +66,8 @@ struct fscrypt_info;
struct fscrypt_operations;
struct fs_context;
struct fs_parameter_description;
+struct fsinfo_kparams;
+enum fsinfo_attribute;
extern void __init inode_init(void);
extern void __init inode_init_early(void);
@@ -1922,6 +1924,9 @@ struct super_operations {
int (*thaw_super) (struct super_block *);
int (*unfreeze_fs) (struct super_block *);
int (*statfs) (struct dentry *, struct kstatfs *);
+#ifdef CONFIG_FSINFO
+ int (*fsinfo) (struct path *, struct fsinfo_kparams *);
+#endif
int (*remount_fs) (struct super_block *, int *, char *);
void (*umount_begin) (struct super_block *);
diff --git a/include/linux/fsinfo.h b/include/linux/fsinfo.h
new file mode 100644
index 000000000000..e17e4f0bae18
--- /dev/null
+++ b/include/linux/fsinfo.h
@@ -0,0 +1,66 @@
+/* Filesystem information query
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells ([email protected])
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#ifndef _LINUX_FSINFO_H
+#define _LINUX_FSINFO_H
+
+#ifdef CONFIG_FSINFO
+
+#include <uapi/linux/fsinfo.h>
+
+struct fsinfo_kparams {
+ __u32 at_flags; /* AT_SYMLINK_NOFOLLOW and similar */
+ enum fsinfo_attribute request; /* What is being asking for */
+ __u32 Nth; /* Instance of it (some may have multiple) */
+ __u32 Mth; /* Subinstance */
+ bool overlarge; /* T if the buffer may be resized */
+ unsigned int usage; /* Amount of buffer used (overlarge=T) */
+ unsigned int buf_size; /* Size of ->buffer[] */
+ void *buffer; /* Where to place the reply */
+ char *scratch_buffer; /* 4K scratch buffer (overlarge=T) */
+};
+
+extern int generic_fsinfo(struct path *, struct fsinfo_kparams *);
+
+static inline void fsinfo_set_cap(struct fsinfo_capabilities *c,
+ enum fsinfo_capability cap)
+{
+ c->capabilities[cap / 8] |= 1 << (cap % 8);
+}
+
+static inline void fsinfo_clear_cap(struct fsinfo_capabilities *c,
+ enum fsinfo_capability cap)
+{
+ c->capabilities[cap / 8] &= ~(1 << (cap % 8));
+}
+
+/**
+ * fsinfo_set_unix_caps - Set standard UNIX capabilities.
+ * @c: The capabilities mask to alter
+ */
+static inline void fsinfo_set_unix_caps(struct fsinfo_capabilities *caps)
+{
+ fsinfo_set_cap(caps, FSINFO_CAP_UIDS);
+ fsinfo_set_cap(caps, FSINFO_CAP_GIDS);
+ fsinfo_set_cap(caps, FSINFO_CAP_DIRECTORIES);
+ fsinfo_set_cap(caps, FSINFO_CAP_SYMLINKS);
+ fsinfo_set_cap(caps, FSINFO_CAP_HARD_LINKS);
+ fsinfo_set_cap(caps, FSINFO_CAP_DEVICE_FILES);
+ fsinfo_set_cap(caps, FSINFO_CAP_UNIX_SPECIALS);
+ fsinfo_set_cap(caps, FSINFO_CAP_SPARSE);
+ fsinfo_set_cap(caps, FSINFO_CAP_HAS_ATIME);
+ fsinfo_set_cap(caps, FSINFO_CAP_HAS_CTIME);
+ fsinfo_set_cap(caps, FSINFO_CAP_HAS_MTIME);
+}
+
+#endif /* CONFIG_FSINFO */
+
+#endif /* _LINUX_FSINFO_H */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index e2870fe1be5b..217d25b62b4f 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -50,6 +50,7 @@ struct stat64;
struct statfs;
struct statfs64;
struct statx;
+struct fsinfo_params;
struct __sysctl_args;
struct sysinfo;
struct timespec;
@@ -997,6 +998,9 @@ asmlinkage long sys_fspick(int dfd, const char __user *path, unsigned int flags)
asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
siginfo_t __user *info,
unsigned int flags);
+asmlinkage long sys_fsinfo(int dfd, const char __user *path,
+ struct fsinfo_params __user *params,
+ void __user *buffer, size_t buf_size);
/*
* Architecture-specific system calls
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index a87904daf103..50ddf5f25122 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -844,9 +844,11 @@ __SYSCALL(__NR_fsconfig, sys_fsconfig)
__SYSCALL(__NR_fsmount, sys_fsmount)
#define __NR_fspick 433
__SYSCALL(__NR_fspick, sys_fspick)
+#define __NR_fsinfo 434
+__SYSCALL(__NR_fsinfo, sys_fsinfo)
#undef __NR_syscalls
-#define __NR_syscalls 434
+#define __NR_syscalls 435
/*
* 32 bit systems traditionally used different
diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
new file mode 100644
index 000000000000..a7a7c731d992
--- /dev/null
+++ b/include/uapi/linux/fsinfo.h
@@ -0,0 +1,219 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* fsinfo() definitions.
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells ([email protected])
+ */
+#ifndef _UAPI_LINUX_FSINFO_H
+#define _UAPI_LINUX_FSINFO_H
+
+#include <linux/types.h>
+#include <linux/socket.h>
+
+/*
+ * The filesystem attributes that can be requested. Note that some attributes
+ * may have multiple instances which can be switched in the parameter block.
+ */
+enum fsinfo_attribute {
+ FSINFO_ATTR_STATFS = 0, /* statfs()-style state */
+ FSINFO_ATTR_FSINFO = 1, /* Information about fsinfo() */
+ FSINFO_ATTR_IDS = 2, /* Filesystem IDs */
+ FSINFO_ATTR_LIMITS = 3, /* Filesystem limits */
+ FSINFO_ATTR_SUPPORTS = 4, /* What's supported in statx, iocflags, ... */
+ FSINFO_ATTR_CAPABILITIES = 5, /* Filesystem capabilities (bits) */
+ FSINFO_ATTR_TIMESTAMP_INFO = 6, /* Inode timestamp info */
+ FSINFO_ATTR_VOLUME_ID = 7, /* Volume ID (string) */
+ FSINFO_ATTR_VOLUME_UUID = 8, /* Volume UUID (LE uuid) */
+ FSINFO_ATTR_VOLUME_NAME = 9, /* Volume name (string) */
+ FSINFO_ATTR_NAME_ENCODING = 10, /* Filename encoding (string) */
+ FSINFO_ATTR_NAME_CODEPAGE = 11, /* Filename codepage (string) */
+ FSINFO_ATTR__NR
+};
+
+/*
+ * Optional fsinfo() parameter structure.
+ *
+ * If this is not given, it is assumed that fsinfo_attr_statfs instance 0,0 is
+ * desired.
+ */
+struct fsinfo_params {
+ __u32 at_flags; /* AT_SYMLINK_NOFOLLOW and similar flags */
+ __u32 request; /* What is being asking for (enum fsinfo_attribute) */
+ __u32 Nth; /* Instance of it (some may have multiple) */
+ __u32 Mth; /* Subinstance of Nth instance */
+ __u64 __reserved[3]; /* Reserved params; all must be 0 */
+};
+
+struct fsinfo_u128 {
+#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN)
+ __u64 hi;
+ __u64 lo;
+#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN)
+ __u64 lo;
+ __u64 hi;
+#endif
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_statfs).
+ * - This gives extended filesystem information.
+ */
+struct fsinfo_statfs {
+ struct fsinfo_u128 f_blocks; /* Total number of blocks in fs */
+ struct fsinfo_u128 f_bfree; /* Total number of free blocks */
+ struct fsinfo_u128 f_bavail; /* Number of free blocks available to ordinary user */
+ struct fsinfo_u128 f_files; /* Total number of file nodes in fs */
+ struct fsinfo_u128 f_ffree; /* Number of free file nodes */
+ struct fsinfo_u128 f_favail; /* Number of file nodes available to ordinary user */
+ __u64 f_bsize; /* Optimal block size */
+ __u64 f_frsize; /* Fragment size */
+ __u64 mnt_attrs; /* Mount attributes (MOUNT_ATTR_*) */
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_ids).
+ *
+ * List of basic identifiers as is normally found in statfs().
+ */
+struct fsinfo_ids {
+ char f_fs_name[15 + 1]; /* Filesystem name */
+ __u64 f_fsid; /* Short 64-bit Filesystem ID (as statfs) */
+ __u64 f_sb_id; /* Internal superblock ID for sbnotify()/mntnotify() */
+ __u32 f_fstype; /* Filesystem type from linux/magic.h [uncond] */
+ __u32 f_dev_major; /* As st_dev_* from struct statx [uncond] */
+ __u32 f_dev_minor;
+ __u32 __reserved[1];
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_limits).
+ *
+ * List of supported filesystem limits.
+ */
+struct fsinfo_limits {
+ struct fsinfo_u128 max_file_size; /* Maximum file size */
+ struct fsinfo_u128 max_ino; /* Maximum inode number */
+ __u64 max_uid; /* Maximum UID supported */
+ __u64 max_gid; /* Maximum GID supported */
+ __u64 max_projid; /* Maximum project ID supported */
+ __u64 max_hard_links; /* Maximum number of hard links on a file */
+ __u64 max_xattr_body_len; /* Maximum xattr content length */
+ __u32 max_xattr_name_len; /* Maximum xattr name length */
+ __u32 max_filename_len; /* Maximum filename length */
+ __u32 max_symlink_len; /* Maximum symlink content length */
+ __u32 max_dev_major; /* Maximum device major representable */
+ __u32 max_dev_minor; /* Maximum device minor representable */
+ __u32 __reserved[1];
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_supports).
+ *
+ * What's supported in various masks, such as statx() attribute and mask bits
+ * and IOC flags.
+ */
+struct fsinfo_supports {
+ __u64 stx_attributes; /* What statx::stx_attributes are supported */
+ __u32 stx_mask; /* What statx::stx_mask bits are supported */
+ __u32 ioc_flags; /* What FS_IOC_* flags are supported */
+ __u32 win_file_attrs; /* What DOS/Windows FILE_* attributes are supported */
+ __u32 __reserved[1];
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_capabilities).
+ *
+ * Bitmask indicating filesystem capabilities where renderable as single bits.
+ */
+enum fsinfo_capability {
+ FSINFO_CAP_IS_KERNEL_FS = 0, /* fs is kernel-special filesystem */
+ FSINFO_CAP_IS_BLOCK_FS = 1, /* fs is block-based filesystem */
+ FSINFO_CAP_IS_FLASH_FS = 2, /* fs is flash filesystem */
+ FSINFO_CAP_IS_NETWORK_FS = 3, /* fs is network filesystem */
+ FSINFO_CAP_IS_AUTOMOUNTER_FS = 4, /* fs is automounter special filesystem */
+ FSINFO_CAP_IS_MEMORY_FS = 5, /* fs is memory-based filesystem */
+ FSINFO_CAP_AUTOMOUNTS = 6, /* fs supports automounts */
+ FSINFO_CAP_ADV_LOCKS = 7, /* fs supports advisory file locking */
+ FSINFO_CAP_MAND_LOCKS = 8, /* fs supports mandatory file locking */
+ FSINFO_CAP_LEASES = 9, /* fs supports file leases */
+ FSINFO_CAP_UIDS = 10, /* fs supports numeric uids */
+ FSINFO_CAP_GIDS = 11, /* fs supports numeric gids */
+ FSINFO_CAP_PROJIDS = 12, /* fs supports numeric project ids */
+ FSINFO_CAP_STRING_USER_IDS = 13, /* fs supports string user identifiers */
+ FSINFO_CAP_GUID_USER_IDS = 14, /* fs supports GUID user identifiers */
+ FSINFO_CAP_WINDOWS_ATTRS = 15, /* fs has windows attributes */
+ FSINFO_CAP_USER_QUOTAS = 16, /* fs has per-user quotas */
+ FSINFO_CAP_GROUP_QUOTAS = 17, /* fs has per-group quotas */
+ FSINFO_CAP_PROJECT_QUOTAS = 18, /* fs has per-project quotas */
+ FSINFO_CAP_XATTRS = 19, /* fs has xattrs */
+ FSINFO_CAP_JOURNAL = 20, /* fs has a journal */
+ FSINFO_CAP_DATA_IS_JOURNALLED = 21, /* fs is using data journalling */
+ FSINFO_CAP_O_SYNC = 22, /* fs supports O_SYNC */
+ FSINFO_CAP_O_DIRECT = 23, /* fs supports O_DIRECT */
+ FSINFO_CAP_VOLUME_ID = 24, /* fs has a volume ID */
+ FSINFO_CAP_VOLUME_UUID = 25, /* fs has a volume UUID */
+ FSINFO_CAP_VOLUME_NAME = 26, /* fs has a volume name */
+ FSINFO_CAP_VOLUME_FSID = 27, /* fs has a volume FSID */
+ FSINFO_CAP_IVER_ALL_CHANGE = 28, /* i_version represents data + meta changes */
+ FSINFO_CAP_IVER_DATA_CHANGE = 29, /* i_version represents data changes only */
+ FSINFO_CAP_IVER_MONO_INCR = 30, /* i_version incremented monotonically */
+ FSINFO_CAP_DIRECTORIES = 31, /* fs supports (sub)directories */
+ FSINFO_CAP_SYMLINKS = 32, /* fs supports symlinks */
+ FSINFO_CAP_HARD_LINKS = 33, /* fs supports hard links */
+ FSINFO_CAP_HARD_LINKS_1DIR = 34, /* fs supports hard links in same dir only */
+ FSINFO_CAP_DEVICE_FILES = 35, /* fs supports bdev, cdev */
+ FSINFO_CAP_UNIX_SPECIALS = 36, /* fs supports pipe, fifo, socket */
+ FSINFO_CAP_RESOURCE_FORKS = 37, /* fs supports resource forks/streams */
+ FSINFO_CAP_NAME_CASE_INDEP = 38, /* Filename case independence is mandatory */
+ FSINFO_CAP_NAME_NON_UTF8 = 39, /* fs has non-utf8 names */
+ FSINFO_CAP_NAME_HAS_CODEPAGE = 40, /* fs has a filename codepage */
+ FSINFO_CAP_SPARSE = 41, /* fs supports sparse files */
+ FSINFO_CAP_NOT_PERSISTENT = 42, /* fs is not persistent */
+ FSINFO_CAP_NO_UNIX_MODE = 43, /* fs does not support unix mode bits */
+ FSINFO_CAP_HAS_ATIME = 44, /* fs supports access time */
+ FSINFO_CAP_HAS_BTIME = 45, /* fs supports birth/creation time */
+ FSINFO_CAP_HAS_CTIME = 46, /* fs supports change time */
+ FSINFO_CAP_HAS_MTIME = 47, /* fs supports modification time */
+ FSINFO_CAP__NR
+};
+
+struct fsinfo_capabilities {
+ __u8 capabilities[(FSINFO_CAP__NR + 7) / 8];
+};
+
+struct fsinfo_timestamp_one {
+ __s64 minimum; /* Minimum timestamp value in seconds */
+ __u64 maximum; /* Maximum timestamp value in seconds */
+ __u16 gran_mantissa; /* Granularity(secs) = mant * 10^exp */
+ __s8 gran_exponent;
+ __u8 reserved[5];
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_timestamp_info).
+ */
+struct fsinfo_timestamp_info {
+ struct fsinfo_timestamp_one atime; /* Access time */
+ struct fsinfo_timestamp_one mtime; /* Modification time */
+ struct fsinfo_timestamp_one ctime; /* Change time */
+ struct fsinfo_timestamp_one btime; /* Birth/creation time */
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_volume_uuid).
+ */
+struct fsinfo_volume_uuid {
+ __u8 uuid[16];
+};
+
+/*
+ * Information struct for fsinfo(fsinfo_attr_fsinfo).
+ *
+ * This gives information about fsinfo() itself.
+ */
+struct fsinfo_fsinfo {
+ __u32 max_attr; /* Number of supported attributes (fsinfo_attr__nr) */
+ __u32 max_cap; /* Number of supported capabilities (fsinfo_cap__nr) */
+};
+
+#endif /* _UAPI_LINUX_FSINFO_H */
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 4d9ae5ea6caf..93927072396c 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -51,6 +51,7 @@ COND_SYSCALL_COMPAT(io_pgetevents);
COND_SYSCALL(io_uring_setup);
COND_SYSCALL(io_uring_enter);
COND_SYSCALL(io_uring_register);
+COND_SYSCALL(fsinfo);
/* fs/xattr.c */
diff --git a/samples/vfs/Makefile b/samples/vfs/Makefile
index a3e4ffd4c773..d3cc8e9a4fd8 100644
--- a/samples/vfs/Makefile
+++ b/samples/vfs/Makefile
@@ -1,10 +1,14 @@
# List of programs to build
hostprogs-y := \
+ test-fsinfo \
test-fsmount \
test-statx
# Tell kbuild to always build the programs
always := $(hostprogs-y)
+HOSTCFLAGS_test-fsinfo.o += -I$(objtree)/usr/include
+HOSTLDLIBS_test-fsinfo += -lm
+
HOSTCFLAGS_test-fsmount.o += -I$(objtree)/usr/include
HOSTCFLAGS_test-statx.o += -I$(objtree)/usr/include
diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
new file mode 100644
index 000000000000..8cce1986df7e
--- /dev/null
+++ b/samples/vfs/test-fsinfo.c
@@ -0,0 +1,551 @@
+/* Test the fsinfo() system call
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells ([email protected])
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define _GNU_SOURCE
+#define _ATFILE_SOURCE
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <errno.h>
+#include <time.h>
+#include <math.h>
+#include <fcntl.h>
+#include <sys/syscall.h>
+#include <linux/fsinfo.h>
+#include <linux/socket.h>
+#include <sys/stat.h>
+#include <arpa/inet.h>
+
+#ifndef __NR_fsinfo
+#define __NR_fsinfo -1
+#endif
+
+static bool debug = 0;
+
+static __attribute__((unused))
+ssize_t fsinfo(int dfd, const char *filename, struct fsinfo_params *params,
+ void *buffer, size_t buf_size)
+{
+ return syscall(__NR_fsinfo, dfd, filename, params, buffer, buf_size);
+}
+
+struct fsinfo_attr_info {
+ unsigned char type;
+ unsigned char flags;
+ unsigned short size;
+};
+
+#define __FSINFO_STRUCT 0
+#define __FSINFO_STRING 1
+#define __FSINFO_OVER 2
+#define __FSINFO_STRUCT_ARRAY 3
+#define __FSINFO_0 0
+#define __FSINFO_N 0x0001
+#define __FSINFO_NM 0x0002
+
+#define _Z(T, F, S) { .type = __FSINFO_##T, .flags = __FSINFO_##F, .size = S }
+#define FSINFO_STRING(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, 0, 0)
+#define FSINFO_STRUCT(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, 0, sizeof(struct fsinfo_##Y))
+#define FSINFO_STRING_N(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, N, 0)
+#define FSINFO_STRUCT_N(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, N, sizeof(struct fsinfo_##Y))
+#define FSINFO_STRING_NM(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, NM, 0)
+#define FSINFO_STRUCT_NM(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, NM, sizeof(struct fsinfo_##Y))
+#define FSINFO_OVERLARGE(X,Y) [FSINFO_ATTR_##X] = _Z(OVER, 0, 0)
+#define FSINFO_STRUCT_ARRAY(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT_ARRAY, 0, sizeof(struct fsinfo_##Y))
+
+static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
+ FSINFO_STRUCT (STATFS, statfs),
+ FSINFO_STRUCT (FSINFO, fsinfo),
+ FSINFO_STRUCT (IDS, ids),
+ FSINFO_STRUCT (LIMITS, limits),
+ FSINFO_STRUCT (CAPABILITIES, capabilities),
+ FSINFO_STRUCT (SUPPORTS, supports),
+ FSINFO_STRUCT (TIMESTAMP_INFO, timestamp_info),
+ FSINFO_STRING (VOLUME_ID, volume_id),
+ FSINFO_STRUCT (VOLUME_UUID, volume_uuid),
+ FSINFO_STRING (VOLUME_NAME, volume_name),
+ FSINFO_STRING (NAME_ENCODING, name_encoding),
+ FSINFO_STRING (NAME_CODEPAGE, name_codepage),
+};
+
+#define FSINFO_NAME(X,Y) [FSINFO_ATTR_##X] = #Y
+static const char *fsinfo_attr_names[FSINFO_ATTR__NR] = {
+ FSINFO_NAME (STATFS, statfs),
+ FSINFO_NAME (FSINFO, fsinfo),
+ FSINFO_NAME (IDS, ids),
+ FSINFO_NAME (LIMITS, limits),
+ FSINFO_NAME (CAPABILITIES, capabilities),
+ FSINFO_NAME (SUPPORTS, supports),
+ FSINFO_NAME (TIMESTAMP_INFO, timestamp_info),
+ FSINFO_NAME (VOLUME_ID, volume_id),
+ FSINFO_NAME (VOLUME_UUID, volume_uuid),
+ FSINFO_NAME (VOLUME_NAME, volume_name),
+ FSINFO_NAME (NAME_ENCODING, name_encoding),
+ FSINFO_NAME (NAME_CODEPAGE, name_codepage),
+};
+
+union reply {
+ char buffer[4096];
+ struct fsinfo_statfs statfs;
+ struct fsinfo_fsinfo fsinfo;
+ struct fsinfo_ids ids;
+ struct fsinfo_limits limits;
+ struct fsinfo_supports supports;
+ struct fsinfo_capabilities caps;
+ struct fsinfo_timestamp_info timestamps;
+ struct fsinfo_volume_uuid uuid;
+};
+
+static void dump_hex(unsigned int *data, int from, int to)
+{
+ unsigned offset, print_offset = 1, col = 0;
+
+ from /= 4;
+ to = (to + 3) / 4;
+
+ for (offset = from; offset < to; offset++) {
+ if (print_offset) {
+ printf("%04x: ", offset * 8);
+ print_offset = 0;
+ }
+ printf("%08x", data[offset]);
+ col++;
+ if ((col & 3) == 0) {
+ printf("\n");
+ print_offset = 1;
+ } else {
+ printf(" ");
+ }
+ }
+
+ if (!print_offset)
+ printf("\n");
+}
+
+static void dump_attr_STATFS(union reply *r, int size)
+{
+ struct fsinfo_statfs *f = &r->statfs;
+
+ printf("\n");
+ printf("\tblocks: n=%llu fr=%llu av=%llu\n",
+ (unsigned long long)f->f_blocks.lo,
+ (unsigned long long)f->f_bfree.lo,
+ (unsigned long long)f->f_bavail.lo);
+
+ printf("\tfiles : n=%llu fr=%llu av=%llu\n",
+ (unsigned long long)f->f_files.lo,
+ (unsigned long long)f->f_ffree.lo,
+ (unsigned long long)f->f_favail.lo);
+ printf("\tbsize : %llu\n", f->f_bsize);
+ printf("\tfrsize: %llu\n", f->f_frsize);
+ printf("\tmntfl : %llx\n", (unsigned long long)f->mnt_attrs);
+}
+
+static void dump_attr_FSINFO(union reply *r, int size)
+{
+ struct fsinfo_fsinfo *f = &r->fsinfo;
+
+ printf("max_attr=%u max_cap=%u\n", f->max_attr, f->max_cap);
+}
+
+static void dump_attr_IDS(union reply *r, int size)
+{
+ struct fsinfo_ids *f = &r->ids;
+
+ printf("\n");
+ printf("\tdev : %02x:%02x\n", f->f_dev_major, f->f_dev_minor);
+ printf("\tfs : type=%x name=%s\n", f->f_fstype, f->f_fs_name);
+ printf("\tfsid : %llx\n", (unsigned long long)f->f_fsid);
+}
+
+static void dump_attr_LIMITS(union reply *r, int size)
+{
+ struct fsinfo_limits *f = &r->limits;
+
+ printf("\n");
+ printf("\tmax file size: %llx%016llx\n",
+ (unsigned long long)f->max_file_size.hi,
+ (unsigned long long)f->max_file_size.lo);
+ printf("\tmax ino: %llx%016llx\n",
+ (unsigned long long)f->max_ino.hi,
+ (unsigned long long)f->max_ino.lo);
+ printf("\tmax ids : u=%llx g=%llx p=%llx\n",
+ (unsigned long long)f->max_uid,
+ (unsigned long long)f->max_gid,
+ (unsigned long long)f->max_projid);
+ printf("\tmax dev : maj=%x min=%x\n",
+ f->max_dev_major, f->max_dev_minor);
+ printf("\tmax links : %llx\n",
+ (unsigned long long)f->max_hard_links);
+ printf("\tmax xattr : n=%x b=%llx\n",
+ f->max_xattr_name_len,
+ (unsigned long long)f->max_xattr_body_len);
+ printf("\tmax len : file=%x sym=%x\n",
+ f->max_filename_len, f->max_symlink_len);
+}
+
+static void dump_attr_SUPPORTS(union reply *r, int size)
+{
+ struct fsinfo_supports *f = &r->supports;
+
+ printf("\n");
+ printf("\tstx_attr=%llx\n", (unsigned long long)f->stx_attributes);
+ printf("\tstx_mask=%x\n", f->stx_mask);
+ printf("\tioc_flags=%x\n", f->ioc_flags);
+ printf("\twin_fattrs=%x\n", f->win_file_attrs);
+}
+
+#define FSINFO_CAP_NAME(C) [FSINFO_CAP_##C] = #C
+static const char *fsinfo_cap_names[FSINFO_CAP__NR] = {
+ FSINFO_CAP_NAME(IS_KERNEL_FS),
+ FSINFO_CAP_NAME(IS_BLOCK_FS),
+ FSINFO_CAP_NAME(IS_FLASH_FS),
+ FSINFO_CAP_NAME(IS_NETWORK_FS),
+ FSINFO_CAP_NAME(IS_AUTOMOUNTER_FS),
+ FSINFO_CAP_NAME(IS_MEMORY_FS),
+ FSINFO_CAP_NAME(AUTOMOUNTS),
+ FSINFO_CAP_NAME(ADV_LOCKS),
+ FSINFO_CAP_NAME(MAND_LOCKS),
+ FSINFO_CAP_NAME(LEASES),
+ FSINFO_CAP_NAME(UIDS),
+ FSINFO_CAP_NAME(GIDS),
+ FSINFO_CAP_NAME(PROJIDS),
+ FSINFO_CAP_NAME(STRING_USER_IDS),
+ FSINFO_CAP_NAME(GUID_USER_IDS),
+ FSINFO_CAP_NAME(WINDOWS_ATTRS),
+ FSINFO_CAP_NAME(USER_QUOTAS),
+ FSINFO_CAP_NAME(GROUP_QUOTAS),
+ FSINFO_CAP_NAME(PROJECT_QUOTAS),
+ FSINFO_CAP_NAME(XATTRS),
+ FSINFO_CAP_NAME(JOURNAL),
+ FSINFO_CAP_NAME(DATA_IS_JOURNALLED),
+ FSINFO_CAP_NAME(O_SYNC),
+ FSINFO_CAP_NAME(O_DIRECT),
+ FSINFO_CAP_NAME(VOLUME_ID),
+ FSINFO_CAP_NAME(VOLUME_UUID),
+ FSINFO_CAP_NAME(VOLUME_NAME),
+ FSINFO_CAP_NAME(VOLUME_FSID),
+ FSINFO_CAP_NAME(IVER_ALL_CHANGE),
+ FSINFO_CAP_NAME(IVER_DATA_CHANGE),
+ FSINFO_CAP_NAME(IVER_MONO_INCR),
+ FSINFO_CAP_NAME(DIRECTORIES),
+ FSINFO_CAP_NAME(SYMLINKS),
+ FSINFO_CAP_NAME(HARD_LINKS),
+ FSINFO_CAP_NAME(HARD_LINKS_1DIR),
+ FSINFO_CAP_NAME(DEVICE_FILES),
+ FSINFO_CAP_NAME(UNIX_SPECIALS),
+ FSINFO_CAP_NAME(RESOURCE_FORKS),
+ FSINFO_CAP_NAME(NAME_CASE_INDEP),
+ FSINFO_CAP_NAME(NAME_NON_UTF8),
+ FSINFO_CAP_NAME(NAME_HAS_CODEPAGE),
+ FSINFO_CAP_NAME(SPARSE),
+ FSINFO_CAP_NAME(NOT_PERSISTENT),
+ FSINFO_CAP_NAME(NO_UNIX_MODE),
+ FSINFO_CAP_NAME(HAS_ATIME),
+ FSINFO_CAP_NAME(HAS_BTIME),
+ FSINFO_CAP_NAME(HAS_CTIME),
+ FSINFO_CAP_NAME(HAS_MTIME),
+};
+
+static void dump_attr_CAPABILITIES(union reply *r, int size)
+{
+ struct fsinfo_capabilities *f = &r->caps;
+ int i;
+
+ for (i = 0; i < sizeof(f->capabilities); i++)
+ printf("%02x", f->capabilities[i]);
+ printf("\n");
+ for (i = 0; i < FSINFO_CAP__NR; i++)
+ if (f->capabilities[i / 8] & (1 << (i % 8)))
+ printf("\t- %s\n", fsinfo_cap_names[i]);
+}
+
+static void print_time(struct fsinfo_timestamp_one *t, char stamp)
+{
+ printf("\t%ctime : gran=%gs range=%llx-%llx\n",
+ stamp,
+ t->gran_mantissa * pow(10., t->gran_exponent),
+ (long long)t->minimum,
+ (long long)t->maximum);
+}
+
+static void dump_attr_TIMESTAMP_INFO(union reply *r, int size)
+{
+ struct fsinfo_timestamp_info *f = &r->timestamps;
+
+ printf("\n");
+ print_time(&f->atime, 'a');
+ print_time(&f->mtime, 'm');
+ print_time(&f->ctime, 'c');
+ print_time(&f->btime, 'b');
+}
+
+static void dump_attr_VOLUME_UUID(union reply *r, int size)
+{
+ struct fsinfo_volume_uuid *f = &r->uuid;
+
+ printf("%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x"
+ "-%02x%02x%02x%02x%02x%02x\n",
+ f->uuid[ 0], f->uuid[ 1],
+ f->uuid[ 2], f->uuid[ 3],
+ f->uuid[ 4], f->uuid[ 5],
+ f->uuid[ 6], f->uuid[ 7],
+ f->uuid[ 8], f->uuid[ 9],
+ f->uuid[10], f->uuid[11],
+ f->uuid[12], f->uuid[13],
+ f->uuid[14], f->uuid[15]);
+}
+
+/*
+ *
+ */
+typedef void (*dumper_t)(union reply *r, int size);
+
+#define FSINFO_DUMPER(N) [FSINFO_ATTR_##N] = dump_attr_##N
+static const dumper_t fsinfo_attr_dumper[FSINFO_ATTR__NR] = {
+ FSINFO_DUMPER(STATFS),
+ FSINFO_DUMPER(FSINFO),
+ FSINFO_DUMPER(IDS),
+ FSINFO_DUMPER(LIMITS),
+ FSINFO_DUMPER(SUPPORTS),
+ FSINFO_DUMPER(CAPABILITIES),
+ FSINFO_DUMPER(TIMESTAMP_INFO),
+ FSINFO_DUMPER(VOLUME_UUID),
+};
+
+static void dump_fsinfo(enum fsinfo_attribute attr,
+ struct fsinfo_attr_info about,
+ union reply *r, int size)
+{
+ dumper_t dumper = fsinfo_attr_dumper[attr];
+ unsigned int len;
+
+ if (!dumper) {
+ printf("<no dumper>\n");
+ return;
+ }
+
+ len = about.size;
+ if (about.type == __FSINFO_STRUCT && size < len) {
+ printf("<short data %u/%u>\n", size, len);
+ return;
+ }
+
+ dumper(r, size);
+}
+
+/*
+ * Try one subinstance of an attribute.
+ */
+static int try_one(const char *file, struct fsinfo_params *params, bool raw)
+{
+ struct fsinfo_attr_info about;
+ union reply *r;
+ size_t buf_size = 4096;
+ char *p;
+ int ret;
+
+ for (;;) {
+ r = malloc(buf_size);
+ if (!r) {
+ perror("malloc");
+ exit(1);
+ }
+ memset(r->buffer, 0xbd, buf_size);
+
+ errno = 0;
+ ret = fsinfo(AT_FDCWD, file, params, r->buffer, buf_size);
+ if (params->request >= FSINFO_ATTR__NR) {
+ if (ret == -1 && errno == EOPNOTSUPP)
+ exit(0);
+ fprintf(stderr, "Unexpected error for too-large command %u: %m\n",
+ params->request);
+ exit(1);
+ }
+ if (ret == -1)
+ break;
+
+ if (ret <= buf_size)
+ break;
+ buf_size = (ret + 4096 - 1) & ~(4096 - 1);
+ }
+
+ if (debug)
+ printf("fsinfo(%s,%s,%u,%u) = %d: %m\n",
+ file, fsinfo_attr_names[params->request],
+ params->Nth, params->Mth, ret);
+
+ about = fsinfo_buffer_info[params->request];
+ if (ret == -1) {
+ if (errno == ENODATA) {
+ if (!(about.flags & (__FSINFO_N | __FSINFO_NM)) &&
+ params->Nth == 0 && params->Mth == 0) {
+ fprintf(stderr,
+ "Unexpected ENODATA (%u[%u][%u])\n",
+ params->request, params->Nth, params->Mth);
+ exit(1);
+ }
+ return (params->Mth == 0) ? 2 : 1;
+ }
+ if (errno == EOPNOTSUPP) {
+ if (params->Nth > 0 || params->Mth > 0) {
+ fprintf(stderr,
+ "Should return -ENODATA (%u[%u][%u])\n",
+ params->request, params->Nth, params->Mth);
+ exit(1);
+ }
+ //printf("\e[33m%s\e[m: <not supported>\n",
+ // fsinfo_attr_names[attr]);
+ return 2;
+ }
+ perror(file);
+ exit(1);
+ }
+
+ if (raw) {
+ if (ret > 4096)
+ ret = 4096;
+ dump_hex((unsigned int *)r->buffer, 0, ret);
+ return 0;
+ }
+
+ switch (about.flags & (__FSINFO_N | __FSINFO_NM)) {
+ case 0:
+ printf("\e[33m%s\e[m: ",
+ fsinfo_attr_names[params->request]);
+ break;
+ case __FSINFO_N:
+ printf("\e[33m%s[%u]\e[m: ",
+ fsinfo_attr_names[params->request],
+ params->Nth);
+ break;
+ case __FSINFO_NM:
+ printf("\e[33m%s[%u][%u]\e[m: ",
+ fsinfo_attr_names[params->request],
+ params->Nth, params->Mth);
+ break;
+ }
+
+ switch (about.type) {
+ case __FSINFO_STRUCT:
+ dump_fsinfo(params->request, about, r, ret);
+ return 0;
+
+ case __FSINFO_STRING:
+ if (ret >= 4096) {
+ ret = 4096;
+ r->buffer[4092] = '.';
+ r->buffer[4093] = '.';
+ r->buffer[4094] = '.';
+ r->buffer[4095] = 0;
+ } else {
+ r->buffer[ret] = 0;
+ }
+ for (p = r->buffer; *p; p++) {
+ if (!isprint(*p)) {
+ printf("<non-printable>\n");
+ continue;
+ }
+ }
+ printf("%s\n", r->buffer);
+ return 0;
+
+ case __FSINFO_OVER:
+ return 0;
+
+ case __FSINFO_STRUCT_ARRAY:
+ dump_fsinfo(params->request, about, r, ret);
+ return 0;
+
+ default:
+ fprintf(stderr, "Fishy about %u %u,%u,%u\n",
+ params->request, about.type, about.flags, about.size);
+ exit(1);
+ }
+}
+
+/*
+ *
+ */
+int main(int argc, char **argv)
+{
+ struct fsinfo_params params = {
+ .at_flags = AT_SYMLINK_NOFOLLOW,
+ };
+ unsigned int attr;
+ int raw = 0, opt, Nth, Mth;
+
+ while ((opt = getopt(argc, argv, "adlr"))) {
+ switch (opt) {
+ case 'a':
+ params.at_flags |= AT_NO_AUTOMOUNT;
+ continue;
+ case 'd':
+ debug = true;
+ continue;
+ case 'l':
+ params.at_flags &= ~AT_SYMLINK_NOFOLLOW;
+ continue;
+ case 'r':
+ raw = 1;
+ continue;
+ }
+ break;
+ }
+
+ argc -= optind;
+ argv += optind;
+
+ if (argc != 1) {
+ printf("Format: test-fsinfo [-alr] <file>\n");
+ exit(2);
+ }
+
+ for (attr = 0; attr <= FSINFO_ATTR__NR; attr++) {
+ Nth = 0;
+ do {
+ Mth = 0;
+ do {
+ params.request = attr;
+ params.Nth = Nth;
+ params.Mth = Mth;
+
+ switch (try_one(argv[0], ¶ms, raw)) {
+ case 0:
+ continue;
+ case 1:
+ goto done_M;
+ case 2:
+ goto done_N;
+ }
+ } while (++Mth < 100);
+
+ done_M:
+ if (Mth >= 100) {
+ fprintf(stderr, "Fishy: Mth == %u\n", Mth);
+ break;
+ }
+
+ } while (++Nth < 100);
+
+ done_N:
+ if (Nth >= 100) {
+ fprintf(stderr, "Fishy: Nth == %u\n", Nth);
+ break;
+ }
+ }
+
+ return 0;
+}
Implement LSM parameter value retrieval with fsinfo() - akin to parsing
/proc/mounts. This allows all the LSM parameters to be retrieved in one go
with:
struct fsinfo_params params = {
.request = FSINFO_ATTR_LSM_PARAMETER,
};
The format is a blob containing pairs of length-prefixed strings to avoid
the need to escape commas and suchlike in the values. This is the same as
for FSINFO_ATTR_PARAMETER.
Signed-off-by: David Howells <[email protected]>
---
fs/fsinfo.c | 21 +++++++++++++++------
include/linux/lsm_hooks.h | 13 +++++++++++++
include/linux/security.h | 11 +++++++++++
include/uapi/linux/fsinfo.h | 1 +
samples/vfs/test-fsinfo.c | 6 +++++-
security/security.c | 12 ++++++++++++
6 files changed, 57 insertions(+), 7 deletions(-)
diff --git a/fs/fsinfo.c b/fs/fsinfo.c
index 3b35cedab0df..b3d517654c98 100644
--- a/fs/fsinfo.c
+++ b/fs/fsinfo.c
@@ -363,7 +363,8 @@ static int vfs_fsinfo(struct path *path, struct fsinfo_kparams *params)
int (*fsinfo)(struct path *, struct fsinfo_kparams *);
int ret;
- if (params->request == FSINFO_ATTR_FSINFO) {
+ switch (params->request) {
+ case FSINFO_ATTR_FSINFO: {
struct fsinfo_fsinfo *info = params->buffer;
info->max_attr = FSINFO_ATTR__NR;
@@ -371,11 +372,18 @@ static int vfs_fsinfo(struct path *path, struct fsinfo_kparams *params)
return sizeof(*info);
}
- fsinfo = dentry->d_sb->s_op->fsinfo;
- if (!fsinfo) {
- if (!dentry->d_sb->s_op->statfs)
- return -EOPNOTSUPP;
- fsinfo = generic_fsinfo;
+ case FSINFO_ATTR_LSM_PARAMETERS:
+ fsinfo = security_sb_fsinfo;
+ break;
+
+ default:
+ fsinfo = dentry->d_sb->s_op->fsinfo;
+ if (!fsinfo) {
+ if (!dentry->d_sb->s_op->statfs)
+ return -EOPNOTSUPP;
+ fsinfo = generic_fsinfo;
+ }
+ break;
}
ret = security_sb_statfs(dentry);
@@ -566,6 +574,7 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
FSINFO_STRUCT_N (PARAM_SPECIFICATION, param_specification),
FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
FSINFO_OPAQUE (PARAMETERS, -),
+ FSINFO_OPAQUE (LSM_PARAMETERS, -),
};
/**
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 47f58cfb6a19..2474c3f785ca 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -108,6 +108,13 @@
* mountpoint.
* @dentry is a handle on the superblock for the filesystem.
* Return 0 if permission is granted.
+ * @sb_fsinfo:
+ * Query LSM information for a filesystem.
+ * @path is a handle on the superblock for the filesystem.
+ * @params is the fsinfo parameter and buffer block.
+ * - Currently, params->request can only be FSINFO_ATTR_LSM_PARAMETERS.
+ * Return the length of the data in the buffer (and can return -ENODATA to
+ * indicate no value under certain circumstances).
* @sb_mount:
* Check permission before an object specified by @dev_name is mounted on
* the mount point named by @nd. For an ordinary mount, @dev_name
@@ -1492,6 +1499,9 @@ union security_list_options {
int (*sb_kern_mount)(struct super_block *sb);
int (*sb_show_options)(struct seq_file *m, struct super_block *sb);
int (*sb_statfs)(struct dentry *dentry);
+#ifdef CONFIG_FSINFO
+ int (*sb_fsinfo)(struct path *path, struct fsinfo_kparams *params);
+#endif
int (*sb_mount)(const char *dev_name, const struct path *path,
const char *type, unsigned long flags, void *data);
int (*sb_umount)(struct vfsmount *mnt, int flags);
@@ -1838,6 +1848,9 @@ struct security_hook_heads {
struct hlist_head sb_kern_mount;
struct hlist_head sb_show_options;
struct hlist_head sb_statfs;
+#ifdef CONFIG_FSINFO
+ struct hlist_head sb_fsinfo;
+#endif
struct hlist_head sb_mount;
struct hlist_head sb_umount;
struct hlist_head sb_pivotroot;
diff --git a/include/linux/security.h b/include/linux/security.h
index 659071c2e57c..23c8b602c0ab 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -57,6 +57,7 @@ struct mm_struct;
struct fs_context;
struct fs_parameter;
enum fs_value_type;
+struct fsinfo_kparams;
/* Default (no) options for the capable function */
#define CAP_OPT_NONE 0x0
@@ -237,6 +238,9 @@ int security_sb_remount(struct super_block *sb, void *mnt_opts);
int security_sb_kern_mount(struct super_block *sb);
int security_sb_show_options(struct seq_file *m, struct super_block *sb);
int security_sb_statfs(struct dentry *dentry);
+#ifdef CONFIG_FSINFO
+int security_sb_fsinfo(struct path *path, struct fsinfo_kparams *params);
+#endif
int security_sb_mount(const char *dev_name, const struct path *path,
const char *type, unsigned long flags, void *data);
int security_sb_umount(struct vfsmount *mnt, int flags);
@@ -575,6 +579,13 @@ static inline int security_sb_statfs(struct dentry *dentry)
return 0;
}
+#ifdef CONFIG_FSINFO
+static inline int security_sb_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ return 0;
+}
+#endif
+
static inline int security_sb_mount(const char *dev_name, const struct path *path,
const char *type, unsigned long flags,
void *data)
diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
index 475cd1c97b12..bae0bdc9ace9 100644
--- a/include/uapi/linux/fsinfo.h
+++ b/include/uapi/linux/fsinfo.h
@@ -31,6 +31,7 @@ enum fsinfo_attribute {
FSINFO_ATTR_PARAM_SPECIFICATION = 13, /* Nth parameter specification */
FSINFO_ATTR_PARAM_ENUM = 14, /* Nth enum-to-val */
FSINFO_ATTR_PARAMETERS = 15, /* Mount parameters (large string) */
+ FSINFO_ATTR_LSM_PARAMETERS = 16, /* LSM Mount parameters (large string) */
FSINFO_ATTR__NR
};
diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
index 8cf5b02e333a..f865bc1af16f 100644
--- a/samples/vfs/test-fsinfo.c
+++ b/samples/vfs/test-fsinfo.c
@@ -82,6 +82,7 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
FSINFO_STRUCT_N (PARAM_SPECIFICATION, param_specification),
FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
FSINFO_OVERLARGE (PARAMETERS, -),
+ FSINFO_OVERLARGE (LSM_PARAMETERS, -),
};
#define FSINFO_NAME(X,Y) [FSINFO_ATTR_##X] = #Y
@@ -102,6 +103,7 @@ static const char *fsinfo_attr_names[FSINFO_ATTR__NR] = {
FSINFO_NAME (PARAM_SPECIFICATION, param_specification),
FSINFO_NAME (PARAM_ENUM, param_enum),
FSINFO_NAME (PARAMETERS, parameters),
+ FSINFO_NAME (LSM_PARAMETERS, lsm_parameters),
};
union reply {
@@ -459,6 +461,7 @@ static int try_one(const char *file, struct fsinfo_params *params, bool raw)
switch (params->request) {
case FSINFO_ATTR_PARAMETERS:
+ case FSINFO_ATTR_LSM_PARAMETERS:
if (ret == 0)
return 0;
}
@@ -505,7 +508,8 @@ static int try_one(const char *file, struct fsinfo_params *params, bool raw)
return 0;
case __FSINFO_OVER:
- if (params->request == FSINFO_ATTR_PARAMETERS)
+ if (params->request == FSINFO_ATTR_PARAMETERS ||
+ params->request == FSINFO_ATTR_LSM_PARAMETERS)
dump_params(about, r, ret);
return 0;
diff --git a/security/security.c b/security/security.c
index 613a5c00e602..3af886e8fced 100644
--- a/security/security.c
+++ b/security/security.c
@@ -25,6 +25,7 @@
#include <linux/ima.h>
#include <linux/evm.h>
#include <linux/fsnotify.h>
+#include <linux/fsinfo.h>
#include <linux/mman.h>
#include <linux/mount.h>
#include <linux/personality.h>
@@ -821,6 +822,17 @@ int security_sb_statfs(struct dentry *dentry)
return call_int_hook(sb_statfs, 0, dentry);
}
+#ifdef CONFIG_FSINFO
+int security_sb_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ int ret = -ENODATA;
+
+ if (params->request == FSINFO_ATTR_LSM_PARAMETERS)
+ ret = 0; /* This is cumulative amongst all LSMs */
+ return call_int_hook(sb_fsinfo, ret, path, params);
+}
+#endif
+
int security_sb_mount(const char *dev_name, const struct path *path,
const char *type, unsigned long flags, void *data)
{
Allow the fsinfo() syscall to look up a mount object by ID rather than by
pathname. This is necessary as there can be multiple mounts stacked up at
the same pathname and there's no way to look through them otherwise.
This is done by passing AT_FSINFO_MOUNTID_PATH to fsinfo() in the
parameters and then passing the mount ID as a string to fsinfo() in place
of the filename:
struct fsinfo_params params = {
.at_flags = AT_FSINFO_MOUNTID_PATH,
.request = FSINFO_ATTR_IDS,
};
ret = fsinfo(AT_FDCWD, "21", ¶ms, buffer, sizeof(buffer));
The caller is only permitted to query a mount object if the root directory
of that mount connects directly to the current chroot if dfd == AT_FDCWD[*]
or the directory specified by dfd otherwise. Note that this is not
available to the pathwalk of any other syscall.
[*] This needs to be something other than AT_FDCWD, perhaps AT_FDROOT.
[!] This probably needs an LSM hook.
[!] This might want to check the permissions on all the intervening dirs -
but it would have to do that under RCU conditions.
[!] This might want to check a CAP_* flag.
Signed-off-by: David Howells <[email protected]>
---
fs/fsinfo.c | 56 +++++++++++++++++++++
fs/internal.h | 2 +
fs/namespace.c | 117 +++++++++++++++++++++++++++++++++++++++++++-
include/uapi/linux/fcntl.h | 1
4 files changed, 173 insertions(+), 3 deletions(-)
diff --git a/fs/fsinfo.c b/fs/fsinfo.c
index 127538193b77..3b218f9fedb7 100644
--- a/fs/fsinfo.c
+++ b/fs/fsinfo.c
@@ -516,6 +516,57 @@ static int vfs_fsinfo_fscontext(int fd, struct fsinfo_kparams *params)
return ret;
}
+/*
+ * Look up the root of a mount object. This allows access to mount objects
+ * (and their attached superblocks) that can't be retrieved by path because
+ * they're entirely covered.
+ *
+ * We only permit access to a mount that has a direct path between either the
+ * dentry pointed to by dfd or to our chroot (if dfd is AT_FDCWD).
+ */
+static int vfs_fsinfo_mount(int dfd, const char __user *filename,
+ struct fsinfo_kparams *params)
+{
+ struct path path;
+ struct fd f = {};
+ char *name;
+ long mnt_id;
+ int ret;
+
+ if ((params->at_flags & ~AT_FSINFO_MOUNTID_PATH) ||
+ !filename)
+ return -EINVAL;
+
+ name = strndup_user(filename, 32);
+ if (IS_ERR(name))
+ return PTR_ERR(name);
+ ret = kstrtoul(name, 0, &mnt_id);
+ if (ret < 0)
+ goto out_name;
+ if (mnt_id > INT_MAX)
+ goto out_name;
+
+ if (dfd != AT_FDCWD) {
+ ret = -EBADF;
+ f = fdget_raw(dfd);
+ if (!f.file)
+ goto out_name;
+ }
+
+ ret = lookup_mount_object(f.file ? &f.file->f_path : NULL,
+ mnt_id, &path);
+ if (ret < 0)
+ goto out_fd;
+
+ ret = vfs_fsinfo(&path, params);
+ path_put(&path);
+out_fd:
+ fdput(f);
+out_name:
+ kfree(name);
+ return ret;
+}
+
/*
* Return buffer information by requestable attribute.
*
@@ -629,6 +680,9 @@ SYSCALL_DEFINE5(fsinfo,
if ((params.at_flags & AT_FSINFO_FROM_FSOPEN) && filename)
return -EINVAL;
+ if ((params.at_flags & (AT_FSINFO_FROM_FSOPEN | AT_FSINFO_MOUNTID_PATH)) ==
+ (AT_FSINFO_FROM_FSOPEN | AT_FSINFO_MOUNTID_PATH))
+ return -EINVAL;
} else {
params.request = FSINFO_ATTR_STATFS;
}
@@ -688,6 +742,8 @@ SYSCALL_DEFINE5(fsinfo,
if (params.at_flags & AT_FSINFO_FROM_FSOPEN)
ret = vfs_fsinfo_fscontext(dfd, ¶ms);
+ else if (params.at_flags & AT_FSINFO_MOUNTID_PATH)
+ ret = vfs_fsinfo_mount(dfd, filename, ¶ms);
else if (filename)
ret = vfs_fsinfo_path(dfd, filename, ¶ms);
else
diff --git a/fs/internal.h b/fs/internal.h
index b089a489da1f..074b1c65e3bd 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -97,6 +97,8 @@ extern int __mnt_want_write_file(struct file *);
extern void __mnt_drop_write_file(struct file *);
extern void dissolve_on_fput(struct vfsmount *);
+extern int lookup_mount_object(struct path *, int, struct path *);
+
/*
* fs_struct.c
*/
diff --git a/fs/namespace.c b/fs/namespace.c
index 1141641dff96..a49a7d9ed482 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -62,7 +62,7 @@ static int __init set_mphash_entries(char *str)
__setup("mphash_entries=", set_mphash_entries);
static u64 event;
-static DEFINE_IDA(mnt_id_ida);
+static DEFINE_IDR(mnt_id_ida);
static DEFINE_IDA(mnt_group_ida);
static struct hlist_head *mount_hashtable __read_mostly;
@@ -101,17 +101,27 @@ static inline struct hlist_head *mp_hash(struct dentry *dentry)
static int mnt_alloc_id(struct mount *mnt)
{
- int res = ida_alloc(&mnt_id_ida, GFP_KERNEL);
+ int res;
+ /* Allocate an ID, but don't set the pointer back to the mount until
+ * later, as once we do that, we have to follow RCU protocols to get
+ * rid of the mount struct.
+ */
+ res = idr_alloc(&mnt_id_ida, NULL, 0, INT_MAX, GFP_KERNEL);
if (res < 0)
return res;
mnt->mnt_id = res;
return 0;
}
+static void mnt_publish_id(struct mount *mnt)
+{
+ idr_replace(&mnt_id_ida, mnt, mnt->mnt_id);
+}
+
static void mnt_free_id(struct mount *mnt)
{
- ida_free(&mnt_id_ida, mnt->mnt_id);
+ idr_remove(&mnt_id_ida, mnt->mnt_id);
}
/*
@@ -974,6 +984,7 @@ struct vfsmount *vfs_create_mount(struct fs_context *fc)
lock_mount_hash();
list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts);
unlock_mount_hash();
+ mnt_publish_id(mnt);
return &mnt->mnt;
}
EXPORT_SYMBOL(vfs_create_mount);
@@ -1067,6 +1078,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
lock_mount_hash();
list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
unlock_mount_hash();
+ mnt_publish_id(mnt);
if ((flag & CL_SLAVE) ||
((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) {
@@ -3988,3 +4000,102 @@ const struct proc_ns_operations mntns_operations = {
.install = mntns_install,
.owner = mntns_owner,
};
+
+/*
+ * See if one path point connects directly to another by ancestral relationship
+ * across mountpoints. Must call with the RCU read lock held.
+ */
+static bool are_paths_connected(struct path *ancestor, struct path *to_check)
+{
+ struct mount *mnt, *parent;
+ struct path cursor;
+ unsigned seq;
+ bool connected;
+
+ seq = 0;
+restart:
+ cursor = *to_check;
+
+ read_seqbegin_or_lock(&rename_lock, &seq);
+ while (cursor.mnt != ancestor->mnt) {
+ mnt = real_mount(cursor.mnt);
+ parent = READ_ONCE(mnt->mnt_parent);
+ if (mnt == parent)
+ goto failed;
+ cursor.dentry = READ_ONCE(mnt->mnt_mountpoint);
+ cursor.mnt = &parent->mnt;
+ }
+
+ while (cursor.dentry != ancestor->dentry) {
+ if (cursor.dentry == cursor.mnt->mnt_root ||
+ IS_ROOT(cursor.dentry))
+ goto failed;
+ cursor.dentry = READ_ONCE(cursor.dentry->d_parent);
+ }
+
+ connected = true;
+out:
+ done_seqretry(&rename_lock, seq);
+ return connected;
+
+failed:
+ if (need_seqretry(&rename_lock, seq)) {
+ seq = 1;
+ goto restart;
+ }
+ connected = false;
+ goto out;
+}
+
+/**
+ * lookup_mount_object - Look up a vfsmount object by ID
+ * @root: The mount root must connect backwards to this point (or chroot if NULL).
+ * @id: The ID of the mountpoint.
+ * @_mntpt: Where to return the resulting mountpoint path.
+ *
+ * Look up the root of the mount with the corresponding ID. This is only
+ * permitted if that mount connects directly to the specified root/chroot.
+ */
+int lookup_mount_object(struct path *root, int mnt_id, struct path *_mntpt)
+{
+ struct mount *mnt;
+ struct path stop, mntpt = {};
+ int ret = -EPERM;
+
+ if (!root)
+ get_fs_root(current->fs, &stop);
+ else
+ stop = *root;
+
+ rcu_read_lock();
+ lock_mount_hash();
+ mnt = idr_find(&mnt_id_ida, mnt_id);
+ if (!mnt)
+ goto out_unlock_mh;
+ if (mnt->mnt.mnt_flags & (MNT_SYNC_UMOUNT | MNT_UMOUNT | MNT_DOOMED))
+ goto out_unlock_mh;
+ if (mnt_get_count(mnt) == 0)
+ goto out_unlock_mh;
+ mnt_add_count(mnt, 1);
+ mntpt.mnt = &mnt->mnt;
+ mntpt.dentry = dget(mnt->mnt.mnt_root);
+ unlock_mount_hash();
+
+ if (are_paths_connected(&stop, &mntpt)) {
+ *_mntpt = mntpt;
+ mntpt.mnt = NULL;
+ mntpt.dentry = NULL;
+ ret = 0;
+ }
+
+out_unlock:
+ rcu_read_unlock();
+ if (!root)
+ path_put(&stop);
+ path_put(&mntpt);
+ return ret;
+
+out_unlock_mh:
+ unlock_mount_hash();
+ goto out_unlock;
+}
diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
index 6a2402a8fa30..5fda91cfca8a 100644
--- a/include/uapi/linux/fcntl.h
+++ b/include/uapi/linux/fcntl.h
@@ -92,6 +92,7 @@
#define AT_STATX_DONT_SYNC 0x4000 /* - Don't sync attributes with the server */
#define AT_FSINFO_FROM_FSOPEN 0x2000 /* Examine the fs_context attached to dfd by fsopen() */
+#define AT_FSINFO_MOUNTID_PATH 0x4000 /* The path is a mount object ID, not an actual path */
#define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */
Add a notification count on mount objects so that the user can easily check
to see if a mount has changed its attributes or its children.
Future patches will:
(1) Provide this value through fsinfo() attributes.
(2) Hook into the notify_mount() function to provide a notification
interface for userspace to monitor.
Signed-off-by: David Howells <[email protected]>
---
fs/mount.h | 22 ++++++++++++++++++++++
fs/namespace.c | 13 +++++++++++++
2 files changed, 35 insertions(+)
diff --git a/fs/mount.h b/fs/mount.h
index 6250de544760..47795802f78e 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -70,6 +70,7 @@ struct mount {
struct hlist_head mnt_pins;
struct fs_pin mnt_umount;
struct dentry *mnt_ex_mountpoint;
+ atomic_t mnt_notify_counter; /* Number of notifications generated */
} __randomize_layout;
#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
@@ -151,3 +152,24 @@ static inline bool is_anon_ns(struct mnt_namespace *ns)
{
return ns->seq == 0;
}
+
+/*
+ * Type of mount topology change notification.
+ */
+enum mount_notification_subtype {
+ NOTIFY_MOUNT_NEW_MOUNT = 0, /* New mount added */
+ NOTIFY_MOUNT_UNMOUNT = 1, /* Mount removed manually */
+ NOTIFY_MOUNT_EXPIRY = 2, /* Automount expired */
+ NOTIFY_MOUNT_READONLY = 3, /* Mount R/O state changed */
+ NOTIFY_MOUNT_SETATTR = 4, /* Mount attributes changed */
+ NOTIFY_MOUNT_MOVE_FROM = 5, /* Mount moved from here */
+ NOTIFY_MOUNT_MOVE_TO = 6, /* Mount moved to here (compare op_id) */
+};
+
+static inline void notify_mount(struct mount *changed,
+ struct mount *aux,
+ enum mount_notification_subtype subtype,
+ u32 info_flags)
+{
+ atomic_inc(&changed->mnt_notify_counter);
+}
diff --git a/fs/namespace.c b/fs/namespace.c
index a49a7d9ed482..1450faab96b9 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -513,6 +513,8 @@ static int mnt_make_readonly(struct mount *mnt)
smp_wmb();
mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
unlock_mount_hash();
+ if (ret == 0)
+ notify_mount(mnt, NULL, NOTIFY_MOUNT_READONLY, 0x10000);
return ret;
}
@@ -521,6 +523,7 @@ static int __mnt_unmake_readonly(struct mount *mnt)
lock_mount_hash();
mnt->mnt.mnt_flags &= ~MNT_READONLY;
unlock_mount_hash();
+ notify_mount(mnt, NULL, NOTIFY_MOUNT_READONLY, 0);
return 0;
}
@@ -833,6 +836,7 @@ static void umount_mnt(struct mount *mnt)
{
/* old mountpoint will be dropped when we can do that */
mnt->mnt_ex_mountpoint = mnt->mnt_mountpoint;
+ notify_mount(mnt->mnt_parent, mnt, NOTIFY_MOUNT_UNMOUNT, 0);
unhash_mnt(mnt);
}
@@ -1472,6 +1476,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
p = list_first_entry(&tmp_list, struct mount, mnt_list);
list_del_init(&p->mnt_expire);
list_del_init(&p->mnt_list);
+
ns = p->mnt_ns;
if (ns) {
ns->mounts--;
@@ -2095,7 +2100,10 @@ static int attach_recursive_mnt(struct mount *source_mnt,
lock_mount_hash();
}
if (parent_path) {
+ notify_mount(source_mnt->mnt_parent, source_mnt,
+ NOTIFY_MOUNT_MOVE_FROM, 0);
detach_mnt(source_mnt, parent_path);
+ notify_mount(dest_mnt, source_mnt, NOTIFY_MOUNT_MOVE_TO, 0);
attach_mnt(source_mnt, dest_mnt, dest_mp);
touch_mnt_namespace(source_mnt->mnt_ns);
} else {
@@ -2104,6 +2112,9 @@ static int attach_recursive_mnt(struct mount *source_mnt,
list_del_init(&source_mnt->mnt_ns->list);
}
mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt);
+ notify_mount(dest_mnt, source_mnt, NOTIFY_MOUNT_NEW_MOUNT,
+ source_mnt->mnt.mnt_sb->s_flags & SB_SUBMOUNT ?
+ 0x10000 : 0);
commit_tree(source_mnt);
}
@@ -2480,6 +2491,7 @@ static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags)
mnt->mnt.mnt_flags = mnt_flags;
touch_mnt_namespace(mnt->mnt_ns);
unlock_mount_hash();
+ notify_mount(mnt, NULL, NOTIFY_MOUNT_SETATTR, 0);
}
/*
@@ -2880,6 +2892,7 @@ void mark_mounts_for_expiry(struct list_head *mounts)
if (!xchg(&mnt->mnt_expiry_mark, 1) ||
propagate_mount_busy(mnt, 1))
continue;
+ notify_mount(mnt, NULL, NOTIFY_MOUNT_EXPIRY, 0);
list_move(&mnt->mnt_expire, &graveyard);
}
while (!list_empty(&graveyard)) {
Implement a program to demonstrate mount listing using the new fsinfo()
syscall, for example:
# ./test-mntinfo
-M 21
MOUNT MOUNT ID NOTIFY# TYPE & DEVICE
------------------------------------- ---------- ---------- ---------------
21 21 8 sysfs 0:15
\_ kernel/security 24 0 securityfs 0:8
\_ fs/cgroup 28 16 tmpfs 0:19
| \_ unified 29 0 cgroup2 0:1a
| \_ systemd 30 0 cgroup 0:1b
| \_ freezer 34 0 cgroup 0:1f
| \_ cpu,cpuacct 35 0 cgroup 0:20
| \_ devices 36 0 cgroup 0:21
| \_ memory 37 0 cgroup 0:22
| \_ cpuset 38 0 cgroup 0:23
| \_ net_cls,net_prio 39 0 cgroup 0:24
| \_ hugetlb 40 0 cgroup 0:25
| \_ rdma 41 0 cgroup 0:26
| \_ blkio 42 0 cgroup 0:27
| \_ perf_event 43 0 cgroup 0:28
\_ fs/pstore 31 0 pstore 0:1c
\_ firmware/efi/efivars 32 0 efivarfs 0:1d
\_ fs/bpf 33 0 bpf 0:1e
\_ kernel/config 92 0 configfs 0:10
\_ fs/selinux 44 0 selinuxfs 0:12
\_ kernel/debug 48 0 debugfs 0:7
Signed-off-by: David Howells <[email protected]>
---
samples/vfs/Makefile | 3 +
samples/vfs/test-mntinfo.c | 241 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 244 insertions(+)
create mode 100644 samples/vfs/test-mntinfo.c
diff --git a/samples/vfs/Makefile b/samples/vfs/Makefile
index 3c542d3b9479..d377b1f7de79 100644
--- a/samples/vfs/Makefile
+++ b/samples/vfs/Makefile
@@ -3,6 +3,7 @@ hostprogs-y := \
test-fsinfo \
test-fs-query \
test-fsmount \
+ test-mntinfo \
test-statx
# Tell kbuild to always build the programs
@@ -10,6 +11,8 @@ always := $(hostprogs-y)
HOSTCFLAGS_test-fsinfo.o += -I$(objtree)/usr/include
HOSTLDLIBS_test-fsinfo += -lm
+HOSTCFLAGS_test-mntinfo.o += -I$(objtree)/usr/include
+HOSTLDLIBS_test-mntinfo += -lm
HOSTCFLAGS_test-fs-query.o += -I$(objtree)/usr/include
HOSTCFLAGS_test-fsmount.o += -I$(objtree)/usr/include
diff --git a/samples/vfs/test-mntinfo.c b/samples/vfs/test-mntinfo.c
new file mode 100644
index 000000000000..e62ee870bc1e
--- /dev/null
+++ b/samples/vfs/test-mntinfo.c
@@ -0,0 +1,241 @@
+/* Test the fsinfo() system call
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells ([email protected])
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#define _GNU_SOURCE
+#define _ATFILE_SOURCE
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <errno.h>
+#include <time.h>
+#include <math.h>
+#include <sys/syscall.h>
+#include <linux/fsinfo.h>
+#include <linux/socket.h>
+#include <linux/fcntl.h>
+#include <sys/stat.h>
+#include <arpa/inet.h>
+
+#ifndef __NR_fsinfo
+#define __NR_fsinfo -1
+#endif
+
+static __attribute__((unused))
+ssize_t fsinfo(int dfd, const char *filename, struct fsinfo_params *params,
+ void *buffer, size_t buf_size)
+{
+ return syscall(__NR_fsinfo, dfd, filename, params, buffer, buf_size);
+}
+
+static char tree_buf[4096];
+static char bar_buf[4096];
+
+/*
+ * Get an fsinfo attribute in a statically allocated buffer.
+ */
+static void get_attr(unsigned int mnt_id, enum fsinfo_attribute attr,
+ void *buf, size_t buf_size)
+{
+ struct fsinfo_params params = {
+ .at_flags = AT_FSINFO_MOUNTID_PATH,
+ .request = attr,
+ };
+ char file[32];
+ long ret;
+
+ sprintf(file, "%u", mnt_id);
+
+ memset(buf, 0xbd, buf_size);
+
+ ret = fsinfo(AT_FDCWD, file, ¶ms, buf, buf_size);
+ if (ret == -1) {
+ fprintf(stderr, "mount-%s: %m\n", file);
+ exit(1);
+ }
+}
+
+/*
+ * Get an fsinfo attribute in a dynamically allocated buffer.
+ */
+static void *get_attr_alloc(unsigned int mnt_id, enum fsinfo_attribute attr,
+ unsigned int Nth, size_t *_size)
+{
+ struct fsinfo_params params = {
+ .at_flags = AT_FSINFO_MOUNTID_PATH,
+ .request = attr,
+ .Nth = Nth,
+ };
+ size_t buf_size = 4096;
+ char file[32];
+ void *r;
+ long ret;
+
+ sprintf(file, "%u", mnt_id);
+
+ for (;;) {
+ r = malloc(buf_size);
+ if (!r) {
+ perror("malloc");
+ exit(1);
+ }
+ memset(r, 0xbd, buf_size);
+
+ ret = fsinfo(AT_FDCWD, file, ¶ms, r, buf_size);
+ if (ret == -1) {
+ fprintf(stderr, "mount-%s: %m\n", file);
+ exit(1);
+ }
+
+ if (ret <= buf_size) {
+ *_size = ret;
+ break;
+ }
+ buf_size = (ret + 4096 - 1) & ~(4096 - 1);
+ }
+
+ return r;
+}
+
+/*
+ * Display a mount and then recurse through its children.
+ */
+static void display_mount(unsigned int mnt_id, unsigned int depth, char *path)
+{
+ struct fsinfo_mount_child *children;
+ struct fsinfo_mount_info info;
+ struct fsinfo_ids ids;
+ unsigned int d;
+ size_t ch_size, p_size;
+ int i, n, s;
+
+ get_attr(mnt_id, FSINFO_ATTR_MOUNT_INFO, &info, sizeof(info));
+ get_attr(mnt_id, FSINFO_ATTR_IDS, &ids, sizeof(ids));
+ if (depth > 0)
+ printf("%s", tree_buf);
+
+ s = strlen(path);
+ printf("%s", !s ? "\"\"" : path);
+ if (!s)
+ s += 2;
+ s += depth;
+ if (s < 38)
+ s = 38 - s;
+ else
+ s = 1;
+ printf("%*.*s", s, s, "");
+
+ printf("%10u %10u %s %x:%x",
+ info.mnt_id, info.notify_counter,
+ ids.f_fs_name, ids.f_dev_major, ids.f_dev_minor);
+ putchar('\n');
+
+ children = get_attr_alloc(mnt_id, FSINFO_ATTR_MOUNT_CHILDREN, 0, &ch_size);
+ n = ch_size / sizeof(children[0]) - 1;
+
+ bar_buf[depth + 1] = '|';
+ if (depth > 0) {
+ tree_buf[depth - 4 + 1] = bar_buf[depth - 4 + 1];
+ tree_buf[depth - 4 + 2] = ' ';
+ }
+
+ tree_buf[depth + 0] = ' ';
+ tree_buf[depth + 1] = '\\';
+ tree_buf[depth + 2] = '_';
+ tree_buf[depth + 3] = ' ';
+ tree_buf[depth + 4] = 0;
+ d = depth + 4;
+
+ for (i = 0; i < n; i++) {
+ if (i == n - 1)
+ bar_buf[depth + 1] = ' ';
+ path = get_attr_alloc(mnt_id, FSINFO_ATTR_MOUNT_SUBMOUNT, i, &p_size);
+ display_mount(children[i].mnt_id, d, path + 1);
+ free(path);
+ }
+
+ free(children);
+ if (depth > 0) {
+ tree_buf[depth - 4 + 1] = '\\';
+ tree_buf[depth - 4 + 2] = '_';
+ }
+ tree_buf[depth] = 0;
+}
+
+/*
+ * Find the ID of whatever is at the nominated path.
+ */
+static unsigned int lookup_mnt_by_path(const char *path)
+{
+ struct fsinfo_mount_info mnt;
+ struct fsinfo_params params = {
+ .request = FSINFO_ATTR_MOUNT_INFO,
+ };
+
+ if (fsinfo(AT_FDCWD, path, ¶ms, &mnt, sizeof(mnt)) == -1) {
+ perror(path);
+ exit(1);
+ }
+
+ return mnt.mnt_id;
+}
+
+/*
+ *
+ */
+int main(int argc, char **argv)
+{
+ unsigned int mnt_id;
+ char *path;
+ bool use_mnt_id = false;
+ int opt;
+
+ while ((opt = getopt(argc, argv, "M"))) {
+ switch (opt) {
+ case 'M':
+ use_mnt_id = true;
+ continue;
+ }
+ break;
+ }
+
+ argc -= optind;
+ argv += optind;
+
+ switch (argc) {
+ case 0:
+ mnt_id = lookup_mnt_by_path("/");
+ path = "ROOT";
+ break;
+ case 1:
+ path = argv[0];
+ if (use_mnt_id) {
+ mnt_id = strtoul(argv[0], NULL, 0);
+ break;
+ }
+
+ mnt_id = lookup_mnt_by_path(argv[0]);
+ break;
+ default:
+ printf("Format: test-mntinfo\n");
+ printf("Format: test-mntinfo <path>\n");
+ printf("Format: test-mntinfo -M <mnt_id>\n");
+ exit(2);
+ }
+
+ printf("MOUNT MOUNT ID NOTIFY# TYPE & DEVICE\n");
+ printf("------------------------------------- ---------- ---------- ---------------\n");
+ display_mount(mnt_id, 0, path);
+ return 0;
+}
Introduce a non-repeating system-unique superblock ID that can be used to
tag superblock notification messages. The ID is time-based to make it
harder to use it as a covert communications channel.
Make it so that this ID can be fetched by the fsinfo() system call.
Signed-off-by: David Howells <[email protected]>
---
fs/fsinfo.c | 1 +
fs/super.c | 24 ++++++++++++++++++++++++
include/linux/fs.h | 3 +++
samples/vfs/test-fsinfo.c | 1 +
4 files changed, 29 insertions(+)
diff --git a/fs/fsinfo.c b/fs/fsinfo.c
index b3d517654c98..127538193b77 100644
--- a/fs/fsinfo.c
+++ b/fs/fsinfo.c
@@ -82,6 +82,7 @@ static int fsinfo_generic_ids(struct path *path, struct fsinfo_ids *p)
p->f_fstype = sb->s_magic;
p->f_dev_major = MAJOR(sb->s_dev);
p->f_dev_minor = MINOR(sb->s_dev);
+ p->f_sb_id = sb->s_unique_id;
memcpy(&p->f_fsid, &buf.f_fsid, sizeof(p->f_fsid));
strlcpy(p->f_fs_name, path->dentry->d_sb->s_type->name,
diff --git a/fs/super.c b/fs/super.c
index 27b3e41394c8..61819e8e5469 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -43,6 +43,8 @@ static int thaw_super_locked(struct super_block *sb);
static LIST_HEAD(super_blocks);
static DEFINE_SPINLOCK(sb_lock);
+static u64 sb_last_identifier;
+static u64 sb_identifier_offset;
static char *sb_writers_name[SB_FREEZE_LEVELS] = {
"sb_writers",
@@ -187,6 +189,27 @@ static void destroy_unused_super(struct super_block *s)
destroy_super_work(&s->destroy_work);
}
+/*
+ * Generate a unique identifier for a superblock.
+ */
+static void generate_super_id(struct super_block *s)
+{
+ u64 id = ktime_to_ns(ktime_get());
+
+ spin_lock(&sb_lock);
+
+ id += sb_identifier_offset;
+ if (id <= sb_last_identifier) {
+ id = sb_last_identifier + 1;
+ sb_identifier_offset = sb_last_identifier - id;
+ }
+
+ sb_last_identifier = id;
+ spin_unlock(&sb_lock);
+
+ s->s_unique_id = id;
+}
+
/**
* alloc_super - create new superblock
* @type: filesystem type superblock should belong to
@@ -270,6 +293,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags,
goto fail;
if (list_lru_init_memcg(&s->s_inode_lru, &s->s_shrink))
goto fail;
+ generate_super_id(s);
return s;
fail:
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 71ce3b054c42..f1c74596cd77 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1527,6 +1527,9 @@ struct super_block {
spinlock_t s_inode_wblist_lock;
struct list_head s_inodes_wb; /* writeback inodes */
+
+ /* Superblock event notifications */
+ u64 s_unique_id;
} __randomize_layout;
/* Helper functions so that in most cases filesystems will
diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
index f865bc1af16f..fadc5e1384fc 100644
--- a/samples/vfs/test-fsinfo.c
+++ b/samples/vfs/test-fsinfo.c
@@ -178,6 +178,7 @@ static void dump_attr_IDS(union reply *r, int size)
printf("\tdev : %02x:%02x\n", f->f_dev_major, f->f_dev_minor);
printf("\tfs : type=%x name=%s\n", f->f_fstype, f->f_fs_name);
printf("\tfsid : %llx\n", (unsigned long long)f->f_fsid);
+ printf("\tsbid : %llx\n", (unsigned long long)f->f_sb_id);
}
static void dump_attr_LIMITS(union reply *r, int size)
Add support for fsinfo().
Signed-off-by: David Howells <[email protected]>
---
fs/hugetlbfs/inode.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 1dcc57189382..62d5d5dec447 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -28,6 +28,7 @@
#include <linux/hugetlb.h>
#include <linux/pagevec.h>
#include <linux/fs_parser.h>
+#include <linux/fsinfo.h>
#include <linux/mman.h>
#include <linux/slab.h>
#include <linux/dnotify.h>
@@ -958,6 +959,59 @@ static int hugetlbfs_show_options(struct seq_file *m, struct dentry *root)
return 0;
}
+#ifdef CONFIG_FSINFO
+static int hugetlbfs_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct dentry *dentry = path->dentry;
+ struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);
+ struct hugepage_subpool *spool = sbinfo->spool;
+ unsigned long hpage_size = huge_page_size(sbinfo->hstate);
+ unsigned hpage_shift = huge_page_shift(sbinfo->hstate);
+ char mod;
+
+ switch (params->request) {
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, dentry->d_sb->s_flags);
+ if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
+ fsinfo_note_paramf(params, "uid", "%u",
+ from_kuid_munged(&init_user_ns,
+ sbinfo->uid));
+
+ if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
+ fsinfo_note_paramf(params, "gid", "%u",
+ from_kgid_munged(&init_user_ns,
+ sbinfo->gid));
+
+ if (spool && spool->max_hpages != -1)
+ fsinfo_note_paramf(params, "size", "%llu",
+ (unsigned long long)spool->max_hpages << hpage_shift);
+
+ if (spool && spool->min_hpages != -1)
+ fsinfo_note_paramf(params, "min_size", "%llu",
+ (unsigned long long)spool->min_hpages << hpage_shift);
+
+ hpage_size /= 1024;
+ mod = 'K';
+ if (hpage_size >= 1024) {
+ hpage_size /= 1024;
+ mod = 'M';
+ }
+ fsinfo_note_paramf(params, "pagesize", "%lu%c", hpage_size, mod);
+
+ if (sbinfo->mode != 0755)
+ fsinfo_note_paramf(params, "mode", "%o", sbinfo->mode);
+
+ if (sbinfo->max_inodes != -1)
+ fsinfo_note_paramf(params, "nr_inodes", "%lu",
+ sbinfo->max_inodes);
+ return params->usage;
+
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
+
static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);
@@ -1116,6 +1170,9 @@ static const struct super_operations hugetlbfs_ops = {
.statfs = hugetlbfs_statfs,
.put_super = hugetlbfs_put_super,
.show_options = hugetlbfs_show_options,
+#ifdef CONFIG_FSINFO
+ .fsinfo = hugetlbfs_fsinfo,
+#endif
};
/*
Add support for fsinfo() to kernfs and cgroup.
Signed-off-by: David Howells <[email protected]>
---
fs/kernfs/mount.c | 20 ++++++++++++++++++++
include/linux/kernfs.h | 4 ++++
kernel/cgroup/cgroup-v1.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
kernel/cgroup/cgroup.c | 19 +++++++++++++++++++
4 files changed, 87 insertions(+)
diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 9a4646eecb71..f40d467d274b 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -17,6 +17,7 @@
#include <linux/namei.h>
#include <linux/seq_file.h>
#include <linux/exportfs.h>
+#include <linux/fsinfo.h>
#include "kernfs-internal.h"
@@ -45,6 +46,22 @@ static int kernfs_sop_show_path(struct seq_file *sf, struct dentry *dentry)
return 0;
}
+#ifdef CONFIG_FSINFO
+static int kernfs_sop_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct kernfs_root *root = kernfs_root(kernfs_dentry_node(path->dentry));
+ struct kernfs_syscall_ops *scops = root->syscall_ops;
+ int ret;
+
+ if (scops && scops->fsinfo) {
+ ret = scops->fsinfo(root, params);
+ if (ret != -EAGAIN)
+ return ret;
+ }
+ return generic_fsinfo(path, params);
+}
+#endif
+
const struct super_operations kernfs_sops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
@@ -52,6 +69,9 @@ const struct super_operations kernfs_sops = {
.show_options = kernfs_sop_show_options,
.show_path = kernfs_sop_show_path,
+#ifdef CONFIG_FSINFO
+ .fsinfo = kernfs_sop_fsinfo,
+#endif
};
/*
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 2bf477f86eb1..d01ec4dc2db1 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -27,6 +27,7 @@ struct super_block;
struct file_system_type;
struct poll_table_struct;
struct fs_context;
+struct fsinfo_kparams;
struct kernfs_fs_context;
struct kernfs_open_node;
@@ -171,6 +172,9 @@ struct kernfs_node {
*/
struct kernfs_syscall_ops {
int (*show_options)(struct seq_file *sf, struct kernfs_root *root);
+#ifdef CONFIG_FSINFO
+ int (*fsinfo)(struct kernfs_root *root, struct fsinfo_kparams *params);
+#endif
int (*mkdir)(struct kernfs_node *parent, const char *name,
umode_t mode);
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 68ca5de7ec27..c8a85dfcac87 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -14,6 +14,7 @@
#include <linux/pid_namespace.h>
#include <linux/cgroupstats.h>
#include <linux/fs_parser.h>
+#include <linux/fsinfo.h>
#include <trace/events/cgroup.h>
@@ -921,6 +922,46 @@ const struct fs_parameter_description cgroup1_fs_parameters = {
.specs = cgroup1_param_specs,
};
+#ifdef CONFIG_FSINFO
+static int cgroup1_fsinfo(struct kernfs_root *kf_root, struct fsinfo_kparams *params)
+{
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ switch (params->request) {
+ case FSINFO_ATTR_PARAMETERS:
+ if (root->name[0])
+ fsinfo_note_param(params, "name", root->name);
+
+ if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
+ fsinfo_note_param(params, "clone_children", NULL);
+ if (root->flags & CGRP_ROOT_CPUSET_V2_MODE)
+ fsinfo_note_param(params, "noprefix", NULL);
+ if (root->flags & CGRP_ROOT_NOPREFIX)
+ fsinfo_note_param(params, "noprefix", NULL);
+ if (root->flags & CGRP_ROOT_XATTR)
+ fsinfo_note_param(params, "xattr", NULL);
+
+ spin_lock(&release_agent_path_lock);
+ if (root->release_agent_path[0])
+ fsinfo_note_param(params, "release_agent",
+ root->release_agent_path);
+ spin_unlock(&release_agent_path_lock);
+
+
+ for_each_subsys(ss, ssid) {
+ if (root->subsys_mask & (1 << ssid))
+ fsinfo_note_param(params, ss->legacy_name, NULL);
+ }
+ return params->usage;
+
+ default:
+ return -EAGAIN; /* Tell kernfs to call generic_fsinfo() */
+ }
+}
+#endif /* CONFIG_FSINFO */
+
int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
@@ -1114,6 +1155,9 @@ int cgroup1_reconfigure(struct fs_context *fc)
struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
.rename = cgroup1_rename,
.show_options = cgroup1_show_options,
+#ifdef CONFIG_FSINFO
+ .fsinfo = cgroup1_fsinfo,
+#endif
.mkdir = cgroup_mkdir,
.rmdir = cgroup_rmdir,
.show_path = cgroup_show_path,
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 4a0eb465d17e..7e32570905e9 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -55,6 +55,7 @@
#include <linux/nsproxy.h>
#include <linux/file.h>
#include <linux/fs_parser.h>
+#include <linux/fsinfo.h>
#include <linux/sched/cputime.h>
#include <linux/psi.h>
#include <net/sock.h>
@@ -1858,6 +1859,21 @@ static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root
return 0;
}
+#ifdef CONFIG_FSINFO
+static int cgroup_fsinfo(struct kernfs_root *kf_root, struct fsinfo_kparams *params)
+{
+ switch (params->request) {
+ case FSINFO_ATTR_PARAMETERS:
+ if (cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE)
+ fsinfo_note_param(params, "nsdelegate", NULL);
+ return params->usage;
+
+ default:
+ return -EAGAIN; /* Tell kernfs to call generic_fsinfo() */
+ }
+}
+#endif /* CONFIG_FSINFO */
+
static int cgroup_reconfigure(struct fs_context *fc)
{
struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
@@ -5550,6 +5566,9 @@ int cgroup_rmdir(struct kernfs_node *kn)
static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
.show_options = cgroup_show_options,
+#ifdef CONFIG_FSINFO
+ .fsinfo = cgroup_fsinfo,
+#endif
.mkdir = cgroup_mkdir,
.rmdir = cgroup_rmdir,
.show_path = cgroup_show_path,
Add support to SELinux for retrieval of the superblock parameters by
fsinfo(FSINFO_ATTR_LSM_PARAMETERS).
Signed-off-by: David Howells <[email protected]>
---
security/selinux/hooks.c | 41 +++++++++++++++++++++++++++++
security/selinux/include/security.h | 2 +
security/selinux/ss/services.c | 49 +++++++++++++++++++++++++++++++++++
3 files changed, 92 insertions(+)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index c61787b15f27..9b5dbdcde9e6 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -91,6 +91,7 @@
#include <linux/bpf.h>
#include <linux/kernfs.h>
#include <linux/stringhash.h> /* for hashlen_string() */
+#include <linux/fsinfo.h>
#include <uapi/linux/mount.h>
#include "avc.h"
@@ -2735,6 +2736,43 @@ static int selinux_sb_statfs(struct dentry *dentry)
return superblock_has_perm(cred, dentry->d_sb, FILESYSTEM__GETATTR, &ad);
}
+#ifdef CONFIG_FSINFO
+/*
+ * Retrieve the SELinux filesystem information, including mount parameters.
+ */
+static int selinux_sb_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct superblock_security_struct *sbsec = path->dentry->d_sb->s_security;
+
+ switch (params->request) {
+ case FSINFO_ATTR_LSM_PARAMETERS:
+ if (!(sbsec->flags & SE_SBINITIALIZED) ||
+ !selinux_state.initialized)
+ return params->usage;
+
+ if (sbsec->flags & FSCONTEXT_MNT)
+ fsinfo_note_sid(params, FSCONTEXT_STR, sbsec->sid);
+ if (sbsec->flags & CONTEXT_MNT)
+ fsinfo_note_sid(params, CONTEXT_STR, sbsec->mntpoint_sid);
+ if (sbsec->flags & DEFCONTEXT_MNT)
+ fsinfo_note_sid(params, DEFCONTEXT_STR, sbsec->def_sid);
+ if (sbsec->flags & ROOTCONTEXT_MNT) {
+ struct dentry *root = sbsec->sb->s_root;
+ struct inode_security_struct *isec = backing_inode_security(root);
+ fsinfo_note_sid(params, ROOTCONTEXT_STR, isec->sid);
+ }
+ if (sbsec->flags & SBLABEL_MNT)
+ fsinfo_note_param(params, SECLABEL_STR, NULL);
+
+ return params->usage;
+
+ default:
+ return -ENODATA;
+ }
+ return 0;
+}
+#endif
+
static int selinux_mount(const char *dev_name,
const struct path *path,
const char *type,
@@ -6761,6 +6799,9 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(sb_kern_mount, selinux_sb_kern_mount),
LSM_HOOK_INIT(sb_show_options, selinux_sb_show_options),
LSM_HOOK_INIT(sb_statfs, selinux_sb_statfs),
+#ifdef CONFIG_FSINFO
+ LSM_HOOK_INIT(sb_fsinfo, selinux_sb_fsinfo),
+#endif
LSM_HOOK_INIT(sb_mount, selinux_mount),
LSM_HOOK_INIT(sb_umount, selinux_umount),
LSM_HOOK_INIT(sb_set_mnt_opts, selinux_set_mnt_opts),
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index 111121281c47..e9617bfcc6ee 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -67,6 +67,7 @@
#define SECLABEL_STR "seclabel"
struct netlbl_lsm_secattr;
+struct fsinfo_kparams;
extern int selinux_enabled;
@@ -258,6 +259,7 @@ int security_sid_to_context_force(struct selinux_state *state,
int security_sid_to_context_inval(struct selinux_state *state,
u32 sid, char **scontext, u32 *scontext_len);
+void fsinfo_note_sid(struct fsinfo_kparams *params, const char *key, u32 sid);
int security_context_to_sid(struct selinux_state *state,
const char *scontext, u32 scontext_len,
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index cc043bc8fd4c..1111b02a999b 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -50,6 +50,7 @@
#include <linux/audit.h>
#include <linux/mutex.h>
#include <linux/vmalloc.h>
+#include <linux/fsinfo.h>
#include <net/netlabel.h>
#include "flask.h"
@@ -1374,6 +1375,54 @@ int security_sid_to_context_inval(struct selinux_state *state, u32 sid,
scontext_len, 1, 1);
}
+#ifdef CONFIG_FSINFO
+void fsinfo_note_sid(struct fsinfo_kparams *params, const char *key, u32 sid)
+{
+ struct selinux_state *state = &selinux_state;
+ struct policydb *policydb;
+ struct context *context;
+ const char *val = "<<<INVALID>>>";
+ char *p;
+ int n;
+
+ if (!state->initialized) {
+ if (sid <= SECINITSID_NUM) {
+ val = initial_sid_to_string[sid];
+ goto out;
+ }
+
+ pr_err("SELinux: %s: called before initial "
+ "load_policy on unknown SID %d\n", __func__, sid);
+ goto out;
+ }
+
+ read_lock(&state->ss->policy_rwlock);
+
+ policydb = &state->ss->policydb;
+ context = sidtab_search(state->ss->sidtab, sid);
+ if (!context) {
+ pr_err("SELinux: %s: unrecognized SID %d\n", __func__, sid);
+ } else {
+ /* Copy the user name, role name and type name into the scratch
+ * buffer and then tack on the MLS.
+ */
+ val = p = params->scratch_buffer;
+ n = sprintf(p, "%s:%s:%s",
+ sym_name(policydb, SYM_USERS, context->user - 1),
+ sym_name(policydb, SYM_ROLES, context->role - 1),
+ sym_name(policydb, SYM_TYPES, context->type - 1));
+
+ p += n;
+ mls_sid_to_context(policydb, context, &p);
+ *p = 0;
+ }
+
+ read_unlock(&state->ss->policy_rwlock);
+out:
+ fsinfo_note_param(params, key, val);
+}
+#endif
+
/*
* Caveat: Mutates scontext.
*/
Allow mount information, including information about the topology tree to
be queried with the fsinfo() system call. Usage of AT_FSINFO_MOUNTID_PATH
allows overlapping mounts to be queried.
To this end, four fsinfo() attributes are provided:
(1) FSINFO_ATTR_MOUNT_INFO.
This is a structure providing information about a mount, including:
- Mounted superblock ID.
- Mount ID (as AT_FSINFO_MOUNTID_PATH).
- Parent mount ID.
- Mount attributes (eg. R/O, NOEXEC).
- Number of change notifications generated.
Note that the parent mount ID is overridden to the ID of the queried
mount if the parent lies outside of the chroot or dfd tree.
(2) FSINFO_ATTR_MOUNT_DEVNAME.
This a string providing the device name associated with the mount.
Note that the device name may be a path that lies outside of the root.
(3) FSINFO_ATTR_MOUNT_CHILDREN.
This produces an array of structures, one for each child and capped
with one for the argument mount (checked after listing all the
children). Each element contains the mount ID and the notification
counter of the respective mount object.
(4) FSINFO_ATTR_MOUNT_SUBMOUNT.
This is a 1D array of strings, indexed with struct fsinfo_params::Nth.
Each string is the relative pathname of the corresponding child
returned by FSINFO_ATTR_MOUNT_CHILDREN.
Note that paths in the mount at the base of the tree (whether that be
dfd or chroot) are relative to the base of the tree, not the root
directory of that mount.
Signed-off-by: David Howells <[email protected]>
---
fs/d_path.c | 2
fs/fsinfo.c | 8 ++
fs/internal.h | 9 ++
fs/namespace.c | 177 +++++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/fsinfo.h | 28 +++++++
samples/vfs/test-fsinfo.c | 47 +++++++++++
6 files changed, 267 insertions(+), 4 deletions(-)
diff --git a/fs/d_path.c b/fs/d_path.c
index a7d0a96b35ce..89d77c264c5f 100644
--- a/fs/d_path.c
+++ b/fs/d_path.c
@@ -227,7 +227,7 @@ static int prepend_unreachable(char **buffer, int *buflen)
return prepend(buffer, buflen, "(unreachable)", 13);
}
-static void get_fs_root_rcu(struct fs_struct *fs, struct path *root)
+void get_fs_root_rcu(struct fs_struct *fs, struct path *root)
{
unsigned seq;
diff --git a/fs/fsinfo.c b/fs/fsinfo.c
index 3b218f9fedb7..61f00f375fd2 100644
--- a/fs/fsinfo.c
+++ b/fs/fsinfo.c
@@ -348,6 +348,10 @@ int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
case _genf(PARAM_SPECIFICATION, param_specification);
case _genf(PARAM_ENUM, param_enum);
case _genp(PARAMETERS, parameters);
+ case _genp(MOUNT_INFO, mount_info);
+ case _genp(MOUNT_DEVNAME, mount_devname);
+ case _genp(MOUNT_CHILDREN, mount_children);
+ case _genp(MOUNT_SUBMOUNT, mount_submount);
default:
return -EOPNOTSUPP;
}
@@ -627,6 +631,10 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
FSINFO_OPAQUE (PARAMETERS, -),
FSINFO_OPAQUE (LSM_PARAMETERS, -),
+ FSINFO_STRUCT (MOUNT_INFO, mount_info),
+ FSINFO_STRING (MOUNT_DEVNAME, mount_devname),
+ FSINFO_STRUCT_ARRAY (MOUNT_CHILDREN, mount_child),
+ FSINFO_STRING_N (MOUNT_SUBMOUNT, mount_submount),
};
/**
diff --git a/fs/internal.h b/fs/internal.h
index 074b1c65e3bd..bb3d8efa7f49 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -53,6 +53,11 @@ void __generic_write_end(struct inode *inode, loff_t pos, unsigned copied,
*/
extern void __init chrdev_init(void);
+/*
+ * d_path.c
+ */
+extern void get_fs_root_rcu(struct fs_struct *fs, struct path *root);
+
/*
* fs_context.c
*/
@@ -98,6 +103,10 @@ extern void __mnt_drop_write_file(struct file *);
extern void dissolve_on_fput(struct vfsmount *);
extern int lookup_mount_object(struct path *, int, struct path *);
+extern int fsinfo_generic_mount_info(struct path *, struct fsinfo_kparams *);
+extern int fsinfo_generic_mount_devname(struct path *, struct fsinfo_kparams *);
+extern int fsinfo_generic_mount_children(struct path *, struct fsinfo_kparams *);
+extern int fsinfo_generic_mount_submount(struct path *, struct fsinfo_kparams *);
/*
* fs_struct.c
diff --git a/fs/namespace.c b/fs/namespace.c
index 1450faab96b9..2ec7d9d1905a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -29,6 +29,7 @@
#include <linux/sched/task.h>
#include <uapi/linux/mount.h>
#include <linux/fs_context.h>
+#include <linux/fsinfo.h>
#include "pnode.h"
#include "internal.h"
@@ -4112,3 +4113,179 @@ int lookup_mount_object(struct path *root, int mnt_id, struct path *_mntpt)
unlock_mount_hash();
goto out_unlock;
}
+
+#ifdef CONFIG_FSINFO
+int fsinfo_generic_mount_info(struct path *path, struct fsinfo_kparams *params)
+{
+ struct fsinfo_mount_info *p = params->buffer;
+ struct super_block *sb;
+ struct mount *m;
+ struct path root;
+ unsigned int flags;
+
+ if (!path->mnt)
+ return -ENODATA;
+
+ m = real_mount(path->mnt);
+ sb = m->mnt.mnt_sb;
+
+ p->f_sb_id = sb->s_unique_id;
+ p->mnt_id = m->mnt_id;
+ p->parent_id = m->mnt_parent->mnt_id;
+ p->notify_counter = atomic_read(&m->mnt_notify_counter);
+
+ get_fs_root(current->fs, &root);
+ if (path->mnt == root.mnt) {
+ p->parent_id = p->mnt_id;
+ } else {
+ rcu_read_lock();
+ if (!are_paths_connected(&root, path))
+ p->parent_id = p->mnt_id;
+ rcu_read_unlock();
+ }
+ if (IS_MNT_SHARED(m))
+ p->group_id = m->mnt_group_id;
+ if (IS_MNT_SLAVE(m)) {
+ int master = m->mnt_master->mnt_group_id;
+ int dom = get_dominating_id(m, &root);
+ p->master_id = master;
+ if (dom && dom != master)
+ p->from_id = dom;
+ }
+ path_put(&root);
+
+ flags = READ_ONCE(m->mnt.mnt_flags);
+ if (flags & MNT_READONLY)
+ p->attr |= MOUNT_ATTR_RDONLY;
+ if (flags & MNT_NOSUID)
+ p->attr |= MOUNT_ATTR_NOSUID;
+ if (flags & MNT_NODEV)
+ p->attr |= MOUNT_ATTR_NODEV;
+ if (flags & MNT_NOEXEC)
+ p->attr |= MOUNT_ATTR_NOEXEC;
+ if (flags & MNT_NODIRATIME)
+ p->attr |= MOUNT_ATTR_NODIRATIME;
+
+ if (flags & MNT_NOATIME)
+ p->attr |= MOUNT_ATTR_NOATIME;
+ else if (flags & MNT_RELATIME)
+ p->attr |= MOUNT_ATTR_RELATIME;
+ else
+ p->attr |= MOUNT_ATTR_STRICTATIME;
+ return sizeof(*p);
+}
+
+int fsinfo_generic_mount_devname(struct path *path, struct fsinfo_kparams *params)
+{
+ struct mount *m;
+ size_t len;
+
+ if (!path->mnt)
+ return -ENODATA;
+
+ m = real_mount(path->mnt);
+ len = strlen(m->mnt_devname);
+ memcpy(params->buffer, m->mnt_devname, len);
+ return len;
+}
+
+/*
+ * Store a mount record into the fsinfo buffer.
+ */
+static void store_mount_fsinfo(struct fsinfo_kparams *params,
+ struct fsinfo_mount_child *child)
+{
+ unsigned int usage = params->usage;
+ unsigned int total = sizeof(*child);
+
+ if (params->usage >= INT_MAX)
+ return;
+ params->usage = usage + total;
+ if (params->buffer && params->usage <= params->buf_size)
+ memcpy(params->buffer + usage, child, total);
+}
+
+/*
+ * Return information about the submounts relative to path.
+ */
+int fsinfo_generic_mount_children(struct path *path, struct fsinfo_kparams *params)
+{
+ struct fsinfo_mount_child record;
+ struct mount *m, *child;
+
+ if (!path->mnt)
+ return -ENODATA;
+
+ m = real_mount(path->mnt);
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(child, &m->mnt_mounts, mnt_child) {
+ if (child->mnt_parent != m)
+ continue;
+ record.mnt_id = child->mnt_id;
+ record.notify_counter = atomic_read(&child->mnt_notify_counter);
+ store_mount_fsinfo(params, &record);
+ }
+ rcu_read_unlock();
+
+ /* End the list with a copy of the parameter mount's details so that
+ * userspace can quickly check for changes.
+ */
+ record.mnt_id = m->mnt_id;
+ record.notify_counter = atomic_read(&m->mnt_notify_counter);
+ store_mount_fsinfo(params, &record);
+ return params->usage;
+}
+
+/*
+ * Return the path of the Nth submount relative to path. This is derived from
+ * d_path(), but the root determination is more complicated.
+ */
+int fsinfo_generic_mount_submount(struct path *path, struct fsinfo_kparams *params)
+{
+ struct mountpoint *mp;
+ struct mount *m, *child;
+ struct path mountpoint, root;
+ unsigned int n = params->Nth;
+ size_t len;
+ void *p;
+
+ if (!path->mnt)
+ return -ENODATA;
+
+ rcu_read_lock();
+
+ m = real_mount(path->mnt);
+ list_for_each_entry_rcu(child, &m->mnt_mounts, mnt_child) {
+ mp = READ_ONCE(child->mnt_mp);
+ if (child->mnt_parent != m || !mp)
+ continue;
+ if (n-- == 0)
+ goto found;
+ }
+ rcu_read_unlock();
+ return -ENODATA;
+
+found:
+ mountpoint.mnt = path->mnt;
+ mountpoint.dentry = READ_ONCE(mp->m_dentry);
+
+ get_fs_root_rcu(current->fs, &root);
+ if (root.mnt != path->mnt) {
+ root.mnt = path->mnt;
+ root.dentry = path->mnt->mnt_root;
+ }
+
+ p = __d_path(&mountpoint, &root, params->buffer, params->buf_size);
+ rcu_read_unlock();
+
+ if (IS_ERR(p))
+ return PTR_ERR(p);
+ if (!p)
+ return -EPERM;
+
+ len = (params->buffer + params->buf_size) - p;
+ memmove(params->buffer, p, len);
+ return len;
+}
+#endif /* CONFIG_FSINFO */
diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
index bae0bdc9ace9..88e1d004ac6c 100644
--- a/include/uapi/linux/fsinfo.h
+++ b/include/uapi/linux/fsinfo.h
@@ -32,6 +32,10 @@ enum fsinfo_attribute {
FSINFO_ATTR_PARAM_ENUM = 14, /* Nth enum-to-val */
FSINFO_ATTR_PARAMETERS = 15, /* Mount parameters (large string) */
FSINFO_ATTR_LSM_PARAMETERS = 16, /* LSM Mount parameters (large string) */
+ FSINFO_ATTR_MOUNT_INFO = 17, /* Mount object information */
+ FSINFO_ATTR_MOUNT_DEVNAME = 18, /* Mount object device name (string) */
+ FSINFO_ATTR_MOUNT_CHILDREN = 19, /* Submount list (array) */
+ FSINFO_ATTR_MOUNT_SUBMOUNT = 20, /* Relative path of Nth submount (string) */
FSINFO_ATTR__NR
};
@@ -276,4 +280,28 @@ struct fsinfo_param_enum {
char name[252]; /* Name of the enum value */
};
+/*
+ * Information struct for fsinfo(FSINFO_ATTR_MOUNT_INFO).
+ */
+struct fsinfo_mount_info {
+ __u64 f_sb_id; /* Superblock ID */
+ __u32 mnt_id; /* Mount identifier (use with AT_FSINFO_MOUNTID_PATH) */
+ __u32 parent_id; /* Parent mount identifier */
+ __u32 group_id; /* Mount group ID */
+ __u32 master_id; /* Slave master group ID */
+ __u32 from_id; /* Slave propagated from ID */
+ __u32 attr; /* MOUNT_ATTR_* flags */
+ __u32 notify_counter; /* Number of notifications generated. */
+ __u32 __reserved[1];
+};
+
+/*
+ * Information struct element for fsinfo(FSINFO_ATTR_MOUNT_CHILDREN).
+ * - An extra element is placed on the end representing the parent mount.
+ */
+struct fsinfo_mount_child {
+ __u32 mnt_id; /* Mount identifier (use with AT_FSINFO_MOUNTID_PATH) */
+ __u32 notify_counter; /* Number of notifications generated on mount. */
+};
+
#endif /* _UAPI_LINUX_FSINFO_H */
diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
index fadc5e1384fc..ab32a15d4c5b 100644
--- a/samples/vfs/test-fsinfo.c
+++ b/samples/vfs/test-fsinfo.c
@@ -21,10 +21,10 @@
#include <errno.h>
#include <time.h>
#include <math.h>
-#include <fcntl.h>
#include <sys/syscall.h>
#include <linux/fsinfo.h>
#include <linux/socket.h>
+#include <linux/fcntl.h>
#include <sys/stat.h>
#include <arpa/inet.h>
@@ -83,6 +83,10 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
FSINFO_OVERLARGE (PARAMETERS, -),
FSINFO_OVERLARGE (LSM_PARAMETERS, -),
+ FSINFO_STRUCT (MOUNT_INFO, mount_info),
+ FSINFO_STRING (MOUNT_DEVNAME, mount_devname),
+ FSINFO_STRUCT_ARRAY (MOUNT_CHILDREN, mount_child),
+ FSINFO_STRING_N (MOUNT_SUBMOUNT, mount_submount),
};
#define FSINFO_NAME(X,Y) [FSINFO_ATTR_##X] = #Y
@@ -104,6 +108,10 @@ static const char *fsinfo_attr_names[FSINFO_ATTR__NR] = {
FSINFO_NAME (PARAM_ENUM, param_enum),
FSINFO_NAME (PARAMETERS, parameters),
FSINFO_NAME (LSM_PARAMETERS, lsm_parameters),
+ FSINFO_NAME (MOUNT_INFO, mount_info),
+ FSINFO_NAME (MOUNT_DEVNAME, mount_devname),
+ FSINFO_NAME (MOUNT_CHILDREN, mount_children),
+ FSINFO_NAME (MOUNT_SUBMOUNT, mount_submount),
};
union reply {
@@ -116,6 +124,8 @@ union reply {
struct fsinfo_capabilities caps;
struct fsinfo_timestamp_info timestamps;
struct fsinfo_volume_uuid uuid;
+ struct fsinfo_mount_info mount_info;
+ struct fsinfo_mount_child mount_children[1];
};
static void dump_hex(unsigned int *data, int from, int to)
@@ -319,6 +329,29 @@ static void dump_attr_VOLUME_UUID(union reply *r, int size)
f->uuid[14], f->uuid[15]);
}
+static void dump_attr_MOUNT_INFO(union reply *r, int size)
+{
+ struct fsinfo_mount_info *f = &r->mount_info;
+
+ printf("\n");
+ printf("\tsb_id : %llx\n", (unsigned long long)f->f_sb_id);
+ printf("\tmnt_id : %x\n", f->mnt_id);
+ printf("\tparent : %x\n", f->parent_id);
+ printf("\tgroup : %x\n", f->group_id);
+ printf("\tattr : %x\n", f->attr);
+ printf("\tnotifs : %x\n", f->notify_counter);
+}
+
+static void dump_attr_MOUNT_CHILDREN(union reply *r, int size)
+{
+ struct fsinfo_mount_child *f = r->mount_children;
+ int i = 0;
+
+ printf("\n");
+ for (; size >= sizeof(*f); size -= sizeof(*f), f++)
+ printf("\t[%u] %8x %8x\n", i++, f->mnt_id, f->notify_counter);
+}
+
/*
*
*/
@@ -334,6 +367,8 @@ static const dumper_t fsinfo_attr_dumper[FSINFO_ATTR__NR] = {
FSINFO_DUMPER(CAPABILITIES),
FSINFO_DUMPER(TIMESTAMP_INFO),
FSINFO_DUMPER(VOLUME_UUID),
+ FSINFO_DUMPER(MOUNT_INFO),
+ FSINFO_DUMPER(MOUNT_CHILDREN),
};
static void dump_fsinfo(enum fsinfo_attribute attr,
@@ -536,16 +571,21 @@ int main(int argc, char **argv)
unsigned int attr;
int raw = 0, opt, Nth, Mth;
- while ((opt = getopt(argc, argv, "adlr"))) {
+ while ((opt = getopt(argc, argv, "Madlr"))) {
switch (opt) {
+ case 'M':
+ params.at_flags = AT_FSINFO_MOUNTID_PATH;
+ continue;
case 'a':
params.at_flags |= AT_NO_AUTOMOUNT;
+ params.at_flags &= ~AT_FSINFO_MOUNTID_PATH;
continue;
case 'd':
debug = true;
continue;
case 'l':
params.at_flags &= ~AT_SYMLINK_NOFOLLOW;
+ params.at_flags &= ~AT_FSINFO_MOUNTID_PATH;
continue;
case 'r':
raw = 1;
@@ -558,7 +598,8 @@ int main(int argc, char **argv)
argv += optind;
if (argc != 1) {
- printf("Format: test-fsinfo [-alr] <file>\n");
+ printf("Format: test-fsinfo [-adlr] <file>\n");
+ printf("Format: test-fsinfo [-dr] -M <mnt_id>\n");
exit(2);
}
Add support to Smack for retrieval of the superblock parameters.
Signed-off-by: David Howells <[email protected]>
---
security/smack/smack_lsm.c | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 0de725f88bed..0a1e88d50ad3 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -45,6 +45,7 @@
#include <linux/parser.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
+#include <linux/fsinfo.h>
#include "smack.h"
#define TRANS_TRUE "TRUE"
@@ -893,6 +894,45 @@ static int smack_sb_statfs(struct dentry *dentry)
return rc;
}
+#ifdef CONFIG_FSINFO
+/*
+ * Retrieve the Smack filesystem information, including mount parameters.
+ */
+static int smack_sb_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct superblock_smack *sp = path->dentry->d_sb->s_security;
+
+ switch (params->request) {
+ case FSINFO_ATTR_LSM_PARAMETERS: {
+ struct dentry *root = path->dentry->d_sb->s_root;
+ struct inode *inode = d_backing_inode(root);
+ struct inode_smack *isp = inode->i_security;
+
+ if (sp->smk_flags & SMK_SB_INITIALIZED)
+ return 0;
+ if (sp->smk_floor)
+ fsinfo_note_param(params, "fsfloor", sp->smk_floor->smk_known);
+ if (sp->smk_hat)
+ fsinfo_note_param(params, "fshat", sp->smk_hat->smk_known);
+ if (sp->smk_default)
+ fsinfo_note_param(params, "fsdefault", sp->smk_default->smk_known);
+
+ if (sp->smk_root) {
+ if (isp && isp->smk_flags & SMK_INODE_TRANSMUTE)
+ fsinfo_note_param(params, "fstransmute", sp->smk_root->smk_known);
+ else
+ fsinfo_note_param(params, "fsroot", sp->smk_root->smk_known);
+ }
+ return params->usage;
+ }
+
+ default:
+ return -ENODATA;
+ }
+ return 0;
+}
+#endif
+
/*
* BPRM hooks
*/
@@ -4606,6 +4646,9 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(sb_free_mnt_opts, smack_free_mnt_opts),
LSM_HOOK_INIT(sb_eat_lsm_opts, smack_sb_eat_lsm_opts),
LSM_HOOK_INIT(sb_statfs, smack_sb_statfs),
+#ifdef CONFIG_FSINFO
+ LSM_HOOK_INIT(sb_fsinfo, smack_sb_fsinfo),
+#endif
LSM_HOOK_INIT(sb_set_mnt_opts, smack_set_mnt_opts),
LSM_HOOK_INIT(bprm_set_creds, smack_bprm_set_creds),
Add API documentation for fsinfo.
Signed-off-by: David Howells <[email protected]>
---
Documentation/filesystems/fsinfo.rst | 596 ++++++++++++++++++++++++++++++++++
1 file changed, 596 insertions(+)
create mode 100644 Documentation/filesystems/fsinfo.rst
diff --git a/Documentation/filesystems/fsinfo.rst b/Documentation/filesystems/fsinfo.rst
new file mode 100644
index 000000000000..497a90f61b3b
--- /dev/null
+++ b/Documentation/filesystems/fsinfo.rst
@@ -0,0 +1,596 @@
+================================
+Filesystem Information Retrieval
+================================
+
+The fsinfo() system call allows the retrieval of filesystem and filesystem
+security information beyond what stat(), statx() and statfs() can query. It
+does not require a file to be opened as does ioctl().
+
+fsinfo() may be called on a path, an open file descriptor, a filesystem-context
+file descriptor as allocated by fsopen() or fspick() or a mount ID (allowing
+for mounts concealed by overmounts to be accessed).
+
+The fsinfo() system call needs to be configured on by enabling:
+
+ "File systems"/"Enable the fsinfo() system call" (CONFIG_FSINFO)
+
+This document has the following sections:
+
+.. contents:: :local:
+
+
+Overview
+========
+
+The fsinfo() system call retrieves one of a number of attributes, specified by
+the "fsinfo_attribute" enumeration::
+
+ FSINFO_ATTR_STATFS - statfs()-style state
+ FSINFO_ATTR_FSINFO - Information about fsinfo() itself
+ FSINFO_ATTR_IDS - Filesystem IDs
+ FSINFO_ATTR_LIMITS - Filesystem limits
+ ...
+
+Each attribute has one of a number of types and, moreover, may have multiple
+values, accessible as a 1D-array or a 2D array-of-arrays. The attribute types
+are:
+
+ * ``Struct``. This is a structure with a version-dependent length. New
+ versions of the kernel may append more fields, though they are not
+ permitted to remove or replace old ones.
+
+ Older applications, expecting an older version of the field, can ask for a
+ shorter struct and will only get the fields they requested; newer
+ applications running on an older kernel will get the extra fields they
+ requested filled with zeros. Either way, the kernel returns the actual size
+ of the internal struct, regardless of how much data it returned.
+
+ This allows for struct-type fields to be extended in future.
+
+ * ``String``. This is a variable-length string of up to 4096 characters (no
+ NUL character is included). The returned string will be truncated if the
+ output buffer is too small. The total size of the string is returned,
+ regardless of any truncation.
+
+ * ``Array``. This is a variable-length array of fixed-size structures. The
+ element size may not vary over time, so the element format must be designed
+ with care. The maximum length is INT_MAX bytes, though this depends on the
+ kernel being able to allocate an internal buffer large enough.
+
+ * ``Opaque``. This is a variable-length blob of indeterminate structure. It
+ may be up to INT_MAX bytes in size.
+
+
+Filesystem API
+==============
+
+The filesystem is called through a superblock_operations method::
+
+ int (*fsinfo) (struct path *path, struct fsinfo_kparams *params);
+
+where "path" indicates the object to be queried and params indicates the
+parameters and the output buffer description. The function should return the
+total size of the data it would like to produce or an error.
+
+The parameter struct looks like::
+
+ struct fsinfo_kparams {
+ enum fsinfo_attribute request;
+ __u32 Nth;
+ __u32 Mth;
+ unsigned int buf_size;
+ unsigned int usage;
+ void *buffer;
+ char *scratch_buffer;
+ ...
+ };
+
+The fields relevant to the filesystem are as follows:
+
+ * ``request``
+
+ Which attribute is being requested. EOPNOTSUPP should be returned if the
+ attribute is not supported by the filesystem or the LSM.
+
+ * ``Nth`` and ``Mth``
+
+ Which value of an attribute is being requested.
+
+ For a single-value attribute Nth and Mth will both be 0.
+
+ For a "1D" attribute, Nth will indicate which value and Mth will always
+ be 0. Take, for example, FSINFO_ATTR_SERVER_NAME - for a network
+ filesystem, the superblock will be backed by a number of servers. This will
+ return the name of the Nth server. ENODATA will be returned if Nth goes
+ beyond the end of the array.
+
+ For a "2D" attribute, Mth will indicate the index in the Nth set of values.
+ Take, for example, Take, for example, FSINFO_ATTR_SERVER_ADDRESS - each
+ server listed by FSINFO_ATTR_SERVER_NAME may have one or more addresses.
+ This will return the Mth address of the Nth server. ENODATA will be
+ returned if the Nth set doesn't exist or the Mth element of the Nth set
+ doesn't exist.
+
+ * ``buf_size``
+
+ This indicates the current size of the buffer. For the array type and the
+ opaque type this will be increased if the current buffer won't hold the
+ value and the filesystem will be called again.
+
+ * ``usage``
+
+ This indicates how much of the buffer has been used so far for an array or
+ opaque type attribute. This is updated by the fsinfo_note_param*()
+ functions.
+
+ * ``buffer``
+
+ This points to the output buffer. For struct-type and string-type
+ attributes it will always be big enough; for array- and opaque-type, it will
+ be buf_size in size and will be resized if the returned size is larger than
+ this.
+
+ * ``scratch_buffer``
+
+ For array- and opaque-type attributes, this will point to a 4096-byte
+ scratch buffer. Sometimes the value needs to be generated by sprintf(),
+ say, to find out how big is going to be, but that might not be possible in
+ the main buffer without risking an overrun.
+
+To simplify filesystem code, there will always be at least a minimal buffer
+available if the ->fsinfo() method gets called - and the filesystem should
+always write what it can into the buffer. It's possible that the fsinfo()
+system call will then throw the contents away and just return the length.
+
+
+Helper Functions
+================
+
+The API includes a number of helper functions:
+
+ * ``int generic_fsinfo(struct path *path, struct fsinfo_kparams *params);``
+
+ This is the function that does default actions for filling out attribute
+ values from standard data, such as may be found in the file_system_type
+ struct and the super_block struct. It also generates -EOPNOTSUPP for
+ unsupported attributes.
+
+ This should be called by a filesystem if it doesn't want to handle an
+ attribute. The filesystem may also call this function and then adjust the
+ information returned, such as changing the listed capability flags.
+
+ * ``void fsinfo_set_cap(struct fsinfo_capabilities *c,
+ enum fsinfo_capability cap);``
+
+ This function sets a capability flag.
+
+ * ``void fsinfo_clear_cap(struct fsinfo_capabilities *c,
+ enum fsinfo_capability cap);``
+
+ This function clears a capability flag.
+
+ * ``void fsinfo_set_unix_caps(struct fsinfo_capabilities *caps);``
+
+ Set capability flags appropriate to the features of a standard UNIX
+ filesystem, such as having numeric UIDS and GIDS; allowing the creation of
+ directories, symbolic links, hard links, device files, FIFO and socket
+ files; permitting sparse files; and having access, change and modification
+ times.
+
+ * ``void fsinfo_note_sb_params(struct fsinfo_kparams *params,
+ unsigned int s_flags);``
+
+ This function notes the standard parameters corresponding to certain
+ ``SB_*`` flags in ``sb->s_flags`` into the parameter buffer. The filesystem
+ is at liberty to adjust the s_flags mask as it sees fit.
+
+ This is intended for use with FSINFO_ATTR_PARAMETERS.
+
+ * ``void fsinfo_note_param(struct fsinfo_kparams *params, const char *key,
+ const char *val);``
+
+ This function writes a pair of strings with prepended lengths into
+ params->buffer, if there's space, and always updates params->usage. The
+ assumption is that the caller of s->s_op->fsinfo() will resize the buffer if
+ the usage grew too large and call again.
+
+ This is intended for use with FSINFO_ATTR_{,LSM_}PARAMETERS, but is not
+ limited to those. The format allows binary data, though this API function
+ does not support anything with NUL characters in it.
+
+ Note that this function will not sleep, so is safe to take with locks held.
+
+ * ``void fsinfo_note_paramf(struct fsinfo_kparams *params, const char *key,
+ const char *val_fmt, ...);``
+
+ This function is a simple wrapper around fsinfo_note_param(), writing the
+ value using vsnprintf() into params->scratch_buffer and then jumping to
+ fsinfo_note_param().
+
+
+Attribute Summary
+=================
+
+To summarise the attributes that are defined::
+
+ Symbolic name Type
+ ===================================== ===============
+ FSINFO_ATTR_STATFS struct
+ FSINFO_ATTR_FSINFO struct
+ FSINFO_ATTR_IDS struct
+ FSINFO_ATTR_LIMITS struct
+ FSINFO_ATTR_SUPPORTS struct
+ FSINFO_ATTR_CAPABILITIES struct
+ FSINFO_ATTR_TIMESTAMP_INFO struct
+ FSINFO_ATTR_VOLUME_ID string
+ FSINFO_ATTR_VOLUME_UUID struct
+ FSINFO_ATTR_VOLUME_NAME string
+ FSINFO_ATTR_NAME_ENCODING string
+ FSINFO_ATTR_NAME_CODEPAGE string
+ FSINFO_ATTR_PARAM_DESCRIPTION struct
+ FSINFO_ATTR_PARAM_SPECIFICATION N × struct
+ FSINFO_ATTR_PARAM_ENUM N × struct
+ FSINFO_ATTR_PARAMETERS opaque
+ FSINFO_ATTR_LSM_PARAMETERS opaque
+ FSINFO_ATTR_MOUNT_INFO struct
+ FSINFO_ATTR_MOUNT_DEVNAME string
+ FSINFO_ATTR_MOUNT_CHILDREN array
+ FSINFO_ATTR_MOUNT_SUBMOUNT N × string
+ FSINFO_ATTR_SERVER_NAME N × string
+ FSINFO_ATTR_SERVER_ADDRESS N × M × struct
+ FSINFO_ATTR_CELL_NAME string
+
+
+Attribute Catalogue
+===================
+
+A number of the attributes convey information about a filesystem superblock:
+
+ * ``FSINFO_ATTR_STATFS``
+
+ This struct-type attribute gives most of the equivalent data to statfs(),
+ but with all the fields as unconditional 64-bit or 128-bit integers. Note
+ that static data like IDs that don't change are retrieved with
+ FSINFO_ATTR_IDS instead.
+
+ Further, superblock flags (such as MS_RDONLY) are not exposed by this
+ attribute; rather the parameters must be listed and the attributes picked
+ out from that.
+
+ * ``FSINFO_ATTR_IDS``
+
+ This struct-type attribute conveys various identifiers used by the target
+ filesystem. This includes the filesystem name, the NFS filesystem ID, the
+ superblock ID used in notifications, the filesystem magic type number and
+ the primary device ID.
+
+ * ``FSINFO_ATTR_LIMITS``
+
+ This struct-type attribute conveys the limits on various aspects of a
+ filesystem, such as maximum file, symlink and xattr sizes, maxiumm filename
+ and xattr name length, maximum number of symlinks, maximum device major and
+ minor numbers and maximum UID, GID and project ID numbers.
+
+ * ``FSINFO_ATTR_SUPPORTS``
+
+ This struct-type attribute conveys information about the support the
+ filesystem has for various UAPI features of a filesystem. This includes
+ information about which bits are supported in various masks employed by the
+ statx system call, what FS_IOC_* flags are supported by ioctls and what
+ DOS/Windows file attribute flags are supported.
+
+ * ``FSINFO_ATTR_CAPABILITIES``
+
+ This is a special attribute, being a set of single-bit capability flags,
+ formatted as struct-type attribute. The meanings of the capability bits
+ are listed below - see the "Capability Bit Catalogue" section. The
+ capability bits are grouped numerically into bytes, such that capilities
+ 0-7 are in byte 0, 8-15 are in byte 1, 16-23 in byte 2 and so on.
+
+ Any capability bit that's not supported by the kernel will be set to false
+ if asked for. The highest supported capability can be obtained from
+ attribute "FSINFO_ATTR_FSINFO".
+
+ * ``FSINFO_ATTR_TIMESTAMP_INFO``
+
+ This struct-type attribute conveys information about the resolution and
+ range of the timestamps available in a filesystem. The resolutions are
+ given as a mantissa and exponent (resolution = mantissa * 10^exponent
+ seconds), where the exponent can be negative to indicate a sub-second
+ resolution (-9 being nanoseconds, for example).
+
+ * ``FSINFO_ATTR_VOLUME_ID``
+
+ This is a string-type attribute that conveys the superblock identifier for
+ the volume. By default it will be filled in from the contents of s_id from
+ the superblock. For a block-based filesystem, for example, this might be
+ the name of the primary block device.
+
+ * ``FSINFO_ATTR_VOLUME_UUID``
+
+ This is a struct-type attribute that conveys the UUID identifier for the
+ volume. By default it will be filled in from the contents of s_uuid from
+ the superblock. If this doesn't exist, it will be an entirely zeros.
+
+ * ``FSINFO_ATTR_VOLUME_NAME``
+
+ This is a string-type attribute that conveys the name of the volume. By
+ default it will return EOPNOTSUPP. For a disk-based filesystem, it might
+ convey the partition label; for a network-based filesystem, it might convey
+ the name of the remote volume.
+
+ * ``FSINFO_ATTR_NAME_ENCODING``
+
+ This is a string-type attribute that returns the type of encoding used for
+ filenames in the medium. By default this will be filled in with "utf8".
+ Not all filesystems can support that, however, so this may indicate a
+ restriction on what characters can be used.
+
+ * ``FSINFO_ATTR_NAME_CODEPAGE``
+
+ This is a string-type attribute that returns the name of the codepage used
+ to transliterate a Linux utf8 filename into whatever the medium supports.
+ By default it returns EOPNOTSUPP.
+
+
+The next attributes give information about the mount parameter parsers and the
+mount parameters values stored in a superblock and its security data. The
+first few of these can be queried on the file descriptor returned by fsopen()
+before any superblock is attached:
+
+ * ``FSINFO_ATTR_PARAM_DESCRIPTION``
+
+ This is a struct-type attribute that returns summary information about what
+ mount options are available on a filesystem, including the number of
+ parameters and the number of enum symbols.
+
+ * ``FSINFO_ATTR_PARAM_SPECIFICATION``
+
+ This is a 1D array of struct-type attributes, indicating the type,
+ qualifiers, name and an option ID for the Nth mount parameter. Parameters
+ that have the same option ID are presumed to be synonyms.
+
+ * ``FSINFO_ATTR_PARAM_ENUM``
+
+ This is a 1D array of struct-type attributes, indicating the Nth value
+ symbol for the set of enumeration-type parameters. All the values are in
+ the same table, so they can be matched to the parameter by option ID, and
+ each option ID may have several entries, each with a different name.
+
+ * ``FSINFO_ATTR_PARAMETERS``
+ * ``FSINFO_ATTR_LSM_PARAMETERS``
+
+ These are a pair of opaque blobs that list all the mount parameter values
+ currently set on a superblock. The first set come from the filesystem and
+ the second is from the LSMs - and, as such, convey security information,
+ such as labelling.
+
+ Inside the filesystem or LSM, the parameter values should be read in one go
+ under lock to avoid races with remount if necessary.
+
+ Each opaque blob is encoded as a series of pairs of elements, where each
+ element begins with a length. The first element of each pair is the key
+ name and the second is the value (which may contain commas, binary data,
+ NUL chars).
+
+ An element length is encoded as a series of bytes in most->least signifcant
+ order. Each byte contributes 7 bits to the length. The MSB in each byte
+ is set if there's another byte of length information following on (ie. all
+ but the last byte in the length have the MSB set).
+
+ A number of helper functions are provided to help record the parameters::
+
+ fsinfo_note_sb_params()
+ fsinfo_note_param()
+ fsinfo_note_paramf()
+
+ Note that the first is not applicable to LSM parameters. It is called
+ automatically if the filesystem doesn't implement the attribute, but must,
+ and should, be called manually otherwise. It should also be called first,
+ before noting any other parameters.
+
+
+Then there are attributes that convey information about the mount topology:
+
+ * ``FSINFO_ATTR_MOUNT_INFO``
+
+ This struct-type attribute conveys information about a mount topology node
+ rather than a superblock. This includes the ID of the superblock mounted
+ there and the ID of the mount node, its parent, group, master and
+ propagation source. It also contains the attribute flags for the mount and
+ a change notification counter so that it can be quickly determined if that
+ node changed.
+
+ * ``FSINFO_ATTR_MOUNT_DEVNAME``
+
+ This string-type attribute returns the "device name" that was supplied when
+ the mount object was created.
+
+ * ``FSINFO_ATTR_MOUNT_CHILDREN``
+
+ This is an array-type attribute that conveys a set of structs, each of
+ which indicates the mount ID of a child and the change counter for that
+ child. The kernel also tags an extra element on the end that indicates the
+ ID and change counter of the queried object. This allows a conflicting
+ change to be quickly detected by comparing the before and after counters.
+
+ * ``FSINFO_ATTR_MOUNT_SUBMOUNT``
+
+ This is a string-type attribute that conveys the pathname of the Nth
+ mountpoint under the target mount, relative to the mount root or the
+ chroot, whichever is closer. These correspond on a 1:1 basis with the
+ elements in the FSINFO_ATTR_MOUNT_CHILDREN list.
+
+Then there are filesystem-specific attributes.
+
+ * ``FSINFO_ATTR_SERVER_NAME``
+
+ This is a string-type attribute that conveys the name of the Nth server
+ backing a network-filesystem superblock.
+
+ * ``FSINFO_ATTR_SERVER_ADDRESS``
+
+ This is a struct-type attribute that conveys the Mth address of the Nth
+ server, as returned by FSINFO_ATTR_SERVER_NAME.
+
+ * ``FSINFO_ATTR_CELL_NAME``
+
+ This is a string-type attribute that retrieves the AFS cell name of the
+ target object.
+
+
+Lastly, one attribute gives information about fsinfo() itself:
+
+ * ``FSINFO_ATTR_FSINFO``
+
+ This struct-type attribute gives information about the fsinfo() system call
+ itself, including the maximum number of attributes supported and the
+ maximum number of capability bits supported.
+
+
+Capability Bit Catalogue
+========================
+
+The capability bits convey single true/false assertions about a specific
+instance of a filesystem (ie. a specific superblock). They are accessed using
+the "FSINFO_ATTR_CAPABILITY" attribute:
+
+ * ``FSINFO_CAP_IS_KERNEL_FS``
+ * ``FSINFO_CAP_IS_BLOCK_FS``
+ * ``FSINFO_CAP_IS_FLASH_FS``
+ * ``FSINFO_CAP_IS_NETWORK_FS``
+ * ``FSINFO_CAP_IS_AUTOMOUNTER_FS``
+ * ``FSINFO_CAP_IS_MEMORY_FS``
+
+ These indicate what kind of filesystem the target is: kernel API (proc),
+ block-based (ext4), flash/nvm-based (jffs2), remote over the network (NFS),
+ local quasi-filesystem that acts as a tray of mountpoints (autofs), plain
+ in-memory filesystem (shmem).
+
+ * ``FSINFO_CAP_AUTOMOUNTS``
+
+ This indicate if a filesystem may have objects that are automount points.
+
+ * ``FSINFO_CAP_ADV_LOCKS``
+ * ``FSINFO_CAP_MAND_LOCKS``
+ * ``FSINFO_CAP_LEASES``
+
+ These indicate if a filesystem supports advisory locks, mandatory locks or
+ leases.
+
+ * ``FSINFO_CAP_UIDS``
+ * ``FSINFO_CAP_GIDS``
+ * ``FSINFO_CAP_PROJIDS``
+
+ These indicate if a filesystem supports/stores/transports numeric user IDs,
+ group IDs or project IDs. The "FSINFO_ATTR_LIMITS" attribute can be used
+ to find out the upper limits on the IDs values.
+
+ * ``FSINFO_CAP_STRING_USER_IDS``
+
+ This indicates if a filesystem supports/stores/transports string user
+ identifiers.
+
+ * ``FSINFO_CAP_GUID_USER_IDS``
+
+ This indicates if a filesystem supports/stores/transports Windows GUIDs as
+ user identifiers (eg. ntfs).
+
+ * ``FSINFO_CAP_WINDOWS_ATTRS``
+
+ This indicates if a filesystem supports Windows FILE_* attribute bits
+ (eg. cifs, jfs). The "FSINFO_ATTR_SUPPORTS" attribute can be used to find
+ out which windows file attributes are supported by the filesystem.
+
+ * ``FSINFO_CAP_USER_QUOTAS``
+ * ``FSINFO_CAP_GROUP_QUOTAS``
+ * ``FSINFO_CAP_PROJECT_QUOTAS``
+
+ These indicate if a filesystem supports quotas for users, groups or
+ projects.
+
+ * ``FSINFO_CAP_XATTRS``
+
+ These indicate if a filesystem supports extended attributes. The
+ "FSINFO_ATTR_LIMITS" attribute can be used to find out the upper limits on
+ the supported name and body lengths.
+
+ * ``FSINFO_CAP_JOURNAL``
+ * ``FSINFO_CAP_DATA_IS_JOURNALLED``
+
+ These indicate whether the filesystem has a journal and whether data
+ changes are logged to it.
+
+ * ``FSINFO_CAP_O_SYNC``
+ * ``FSINFO_CAP_O_DIRECT``
+
+ These indicate whether the filesystem supports the O_SYNC and O_DIRECT
+ flags.
+
+ * ``FSINFO_CAP_VOLUME_ID``
+ * ``FSINFO_CAP_VOLUME_UUID``
+ * ``FSINFO_CAP_VOLUME_NAME``
+ * ``FSINFO_CAP_VOLUME_FSID``
+
+ These indicate whether ID, UUID, name and FSID identifiers actually exist
+ in the filesystem and thus might be considered persistent.
+
+ * ``FSINFO_CAP_IVER_ALL_CHANGE``
+ * ``FSINFO_CAP_IVER_DATA_CHANGE``
+ * ``FSINFO_CAP_IVER_MONO_INCR``
+
+ These indicate whether i_version in the inode is supported and, if so, what
+ mode it operates in. The first two indicate if it's changed for any data
+ or metadata change, or whether it's only changed for any data changes; the
+ last indicates whether or not it's monotonically increasing for each such
+ change.
+
+ * ``FSINFO_CAP_HARD_LINKS``
+ * ``FSINFO_CAP_HARD_LINKS_1DIR``
+
+ These indicate whether the filesystem can have hard links made in it, and
+ whether they can be made between directory or only within the same
+ directory.
+
+ * ``FSINFO_CAP_DIRECTORIES``
+ * ``FSINFO_CAP_SYMLINKS``
+ * ``FSINFO_CAP_DEVICE_FILES``
+ * ``FSINFO_CAP_UNIX_SPECIALS``
+
+ These indicate whether directories; symbolic links; device files; or pipes
+ and sockets can be made within the filesystem.
+
+ * ``FSINFO_CAP_RESOURCE_FORKS``
+
+ This indicates if the filesystem supports resource forks.
+
+ * ``FSINFO_CAP_NAME_CASE_INDEP``
+ * ``FSINFO_CAP_NAME_NON_UTF8``
+ * ``FSINFO_CAP_NAME_HAS_CODEPAGE``
+
+ These indicate if the filesystem supports case-independent file names,
+ whether the filenames are non-utf8 (see the "FSINFO_ATTR_NAME_ENCODING"
+ attribute) and whether a codepage is in use to transliterate them (see
+ the "FSINFO_ATTR_NAME_CODEPAGE" attribute).
+
+ * ``FSINFO_CAP_SPARSE``
+
+ This indicates if a filesystem supports sparse files.
+
+ * ``FSINFO_CAP_NOT_PERSISTENT``
+
+ This indicates if a filesystem is not persistent.
+
+ * ``FSINFO_CAP_NO_UNIX_MODE``
+
+ This indicates if a filesystem doesn't support UNIX mode bits (though they
+ may be manufactured from other bits, such as Windows file attribute flags).
+
+ * ``FSINFO_CAP_HAS_ATIME``
+ * ``FSINFO_CAP_HAS_BTIME``
+ * ``FSINFO_CAP_HAS_CTIME``
+ * ``FSINFO_CAP_HAS_MTIME``
+
+ These indicate which timestamps a filesystem supports (access, birth,
+ change, modify). The range and resolutions can be queried with the
+ "FSINFO_ATTR_TIMESTAMPS" attribute).
Add fsinfo support to the AFS filesystem.
Signed-off-by: David Howells <[email protected]>
---
fs/afs/internal.h | 1
fs/afs/super.c | 180 +++++++++++++++++++++++++++++++++++++++++++
fs/fsinfo.c | 3 +
include/uapi/linux/fsinfo.h | 12 +++
samples/vfs/test-fsinfo.c | 33 ++++++++
5 files changed, 227 insertions(+), 2 deletions(-)
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 2073c1a3ab4b..da40ea036c6a 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -254,6 +254,7 @@ struct afs_super_info {
struct afs_volume *volume; /* volume record */
enum afs_flock_mode flock_mode:8; /* File locking emulation mode */
bool dyn_root; /* True if dynamic root */
+ bool autocell; /* True if autocell */
};
static inline struct afs_super_info *AFS_FS_S(struct super_block *sb)
diff --git a/fs/afs/super.c b/fs/afs/super.c
index f18911e8d770..47bc49be9bd3 100644
--- a/fs/afs/super.c
+++ b/fs/afs/super.c
@@ -26,6 +26,7 @@
#include <linux/sched.h>
#include <linux/nsproxy.h>
#include <linux/magic.h>
+#include <linux/fsinfo.h>
#include <net/net_namespace.h>
#include "internal.h"
@@ -35,6 +36,9 @@ static struct inode *afs_alloc_inode(struct super_block *sb);
static void afs_destroy_inode(struct inode *inode);
static void afs_free_inode(struct inode *inode);
static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
+#ifdef CONFIG_FSINFO
+static int afs_fsinfo(struct path *path, struct fsinfo_kparams *params);
+#endif
static int afs_show_devname(struct seq_file *m, struct dentry *root);
static int afs_show_options(struct seq_file *m, struct dentry *root);
static int afs_init_fs_context(struct fs_context *fc);
@@ -54,6 +58,9 @@ int afs_net_id;
static const struct super_operations afs_super_ops = {
.statfs = afs_statfs,
+#ifdef CONFIG_FSINFO
+ .fsinfo = afs_fsinfo,
+#endif
.alloc_inode = afs_alloc_inode,
.drop_inode = afs_drop_inode,
.destroy_inode = afs_destroy_inode,
@@ -199,7 +206,7 @@ static int afs_show_options(struct seq_file *m, struct dentry *root)
if (as->dyn_root)
seq_puts(m, ",dyn");
- if (test_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(d_inode(root))->flags))
+ if (as->autocell)
seq_puts(m, ",autocell");
switch (as->flock_mode) {
case afs_flock_mode_unset: break;
@@ -463,7 +470,7 @@ static int afs_fill_super(struct super_block *sb, struct afs_fs_context *ctx)
if (IS_ERR(inode))
return PTR_ERR(inode);
- if (ctx->autocell || as->dyn_root)
+ if (as->autocell || as->dyn_root)
set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);
ret = -ENOMEM;
@@ -503,6 +510,8 @@ static struct afs_super_info *afs_alloc_sbi(struct fs_context *fc)
as->cell = afs_get_cell(ctx->cell);
as->volume = __afs_get_volume(ctx->volume);
}
+ if (ctx->autocell)
+ as->autocell = true;
}
return as;
}
@@ -765,3 +774,170 @@ static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
return ret;
}
+
+#ifdef CONFIG_FSINFO
+static const struct fsinfo_timestamp_info afs_timestamp_info = {
+ .atime = {
+ .minimum = 0,
+ .maximum = UINT_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+ .mtime = {
+ .minimum = 0,
+ .maximum = UINT_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+ .ctime = {
+ .minimum = 0,
+ .maximum = UINT_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+ .btime = {
+ .minimum = 0,
+ .maximum = UINT_MAX,
+ .gran_mantissa = 1,
+ .gran_exponent = 0,
+ },
+};
+
+/*
+ * Get filesystem information.
+ */
+static int afs_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct fsinfo_timestamp_info *tsinfo;
+ struct fsinfo_server_address *addr;
+ struct fsinfo_capabilities *caps;
+ struct fsinfo_supports *sup;
+ struct dentry *dentry = path->dentry;
+ struct afs_server_list *slist;
+ struct afs_super_info *as = AFS_FS_S(dentry->d_sb);
+ struct afs_addr_list *alist;
+ struct afs_server *server;
+ struct afs_volume *volume = as->volume;
+ struct afs_cell *cell = as->cell;
+ struct afs_net *net = afs_d2net(dentry);
+ bool dyn_root = as->dyn_root;
+ int ret;
+
+ switch (params->request) {
+ case FSINFO_ATTR_TIMESTAMP_INFO:
+ tsinfo = params->buffer;
+ *tsinfo = afs_timestamp_info;
+ return sizeof(*tsinfo);
+
+ case FSINFO_ATTR_SUPPORTS:
+ sup = params->buffer;
+ sup->stx_mask = (STATX_TYPE | STATX_MODE |
+ STATX_NLINK |
+ STATX_UID | STATX_GID |
+ STATX_MTIME | STATX_INO |
+ STATX_SIZE);
+ sup->stx_attributes = STATX_ATTR_AUTOMOUNT;
+ return sizeof(*sup);
+
+ case FSINFO_ATTR_CAPABILITIES:
+ caps = params->buffer;
+ if (dyn_root) {
+ fsinfo_set_cap(caps, FSINFO_CAP_IS_AUTOMOUNTER_FS);
+ fsinfo_set_cap(caps, FSINFO_CAP_AUTOMOUNTS);
+ } else {
+ fsinfo_set_cap(caps, FSINFO_CAP_IS_NETWORK_FS);
+ fsinfo_set_cap(caps, FSINFO_CAP_AUTOMOUNTS);
+ fsinfo_set_cap(caps, FSINFO_CAP_ADV_LOCKS);
+ fsinfo_set_cap(caps, FSINFO_CAP_UIDS);
+ fsinfo_set_cap(caps, FSINFO_CAP_GIDS);
+ fsinfo_set_cap(caps, FSINFO_CAP_VOLUME_ID);
+ fsinfo_set_cap(caps, FSINFO_CAP_VOLUME_NAME);
+ fsinfo_set_cap(caps, FSINFO_CAP_IVER_MONO_INCR);
+ fsinfo_set_cap(caps, FSINFO_CAP_SYMLINKS);
+ fsinfo_set_cap(caps, FSINFO_CAP_HARD_LINKS_1DIR);
+ fsinfo_set_cap(caps, FSINFO_CAP_HAS_MTIME);
+ }
+ return sizeof(*caps);
+
+ case FSINFO_ATTR_VOLUME_NAME:
+ if (dyn_root)
+ return -EOPNOTSUPP;
+ memcpy(params->buffer, volume->name, volume->name_len);
+ return volume->name_len;
+
+ case FSINFO_ATTR_CELL_NAME:
+ if (dyn_root)
+ return -EOPNOTSUPP;
+ memcpy(params->buffer, cell->name, cell->name_len);
+ return cell->name_len;
+
+ case FSINFO_ATTR_SERVER_NAME:
+ if (dyn_root)
+ return -EOPNOTSUPP;
+ read_lock(&volume->servers_lock);
+ slist = afs_get_serverlist(volume->servers);
+ read_unlock(&volume->servers_lock);
+
+ if (params->Nth < slist->nr_servers) {
+ server = slist->servers[params->Nth].server;
+ ret = sprintf(params->buffer, "%pU", &server->uuid);
+ } else {
+ ret = -ENODATA;
+ }
+
+ afs_put_serverlist(net, slist);
+ return ret;
+
+ case FSINFO_ATTR_SERVER_ADDRESS:
+ addr = params->buffer;
+ if (dyn_root)
+ return -EOPNOTSUPP;
+ read_lock(&volume->servers_lock);
+ slist = afs_get_serverlist(volume->servers);
+ read_unlock(&volume->servers_lock);
+
+ ret = -ENODATA;
+ if (params->Nth >= slist->nr_servers)
+ goto put_slist;
+ server = slist->servers[params->Nth].server;
+
+ read_lock(&server->fs_lock);
+ alist = afs_get_addrlist(rcu_access_pointer(server->addresses));
+ read_unlock(&server->fs_lock);
+ if (!alist)
+ goto put_slist;
+
+ if (params->Mth >= alist->nr_addrs)
+ goto put_alist;
+
+ memcpy(addr, &alist->addrs[params->Mth],
+ sizeof(struct sockaddr_rxrpc));
+ ret = sizeof(*addr);
+
+ put_alist:
+ afs_put_addrlist(alist);
+ put_slist:
+ afs_put_serverlist(net, slist);
+ return ret;
+
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, dentry->d_sb->s_flags);
+ if (!dyn_root)
+ fsinfo_note_paramf(params, "source", "%c%s:%s%s",
+ volume->type == AFSVL_RWVOL ? '%' : '#',
+ cell->name,
+ volume->name,
+ volume->type == AFSVL_RWVOL ? "" :
+ volume->type == AFSVL_ROVOL ? ".readonly" :
+ ".backup");
+ if (as->autocell)
+ fsinfo_note_param(params, "autocell", NULL);
+ if (dyn_root)
+ fsinfo_note_param(params, "dyn", NULL);
+ return params->usage;
+
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
diff --git a/fs/fsinfo.c b/fs/fsinfo.c
index 61f00f375fd2..c48df3028d60 100644
--- a/fs/fsinfo.c
+++ b/fs/fsinfo.c
@@ -635,6 +635,9 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
FSINFO_STRING (MOUNT_DEVNAME, mount_devname),
FSINFO_STRUCT_ARRAY (MOUNT_CHILDREN, mount_child),
FSINFO_STRING_N (MOUNT_SUBMOUNT, mount_submount),
+ FSINFO_STRING_N (SERVER_NAME, server_name),
+ FSINFO_STRUCT_NM (SERVER_ADDRESS, server_address),
+ FSINFO_STRING (CELL_NAME, cell_name),
};
/**
diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
index 88e1d004ac6c..12e94201a5d1 100644
--- a/include/uapi/linux/fsinfo.h
+++ b/include/uapi/linux/fsinfo.h
@@ -36,6 +36,9 @@ enum fsinfo_attribute {
FSINFO_ATTR_MOUNT_DEVNAME = 18, /* Mount object device name (string) */
FSINFO_ATTR_MOUNT_CHILDREN = 19, /* Submount list (array) */
FSINFO_ATTR_MOUNT_SUBMOUNT = 20, /* Relative path of Nth submount (string) */
+ FSINFO_ATTR_SERVER_NAME = 21, /* Name of the Nth server (string) */
+ FSINFO_ATTR_SERVER_ADDRESS = 22, /* Mth address of the Nth server */
+ FSINFO_ATTR_CELL_NAME = 23, /* Cell name (string) */
FSINFO_ATTR__NR
};
@@ -304,4 +307,13 @@ struct fsinfo_mount_child {
__u32 notify_counter; /* Number of notifications generated on mount. */
};
+/*
+ * Information struct for fsinfo(fsinfo_attr_server_addresses).
+ *
+ * Find the Mth address of the Nth server for a network mount.
+ */
+struct fsinfo_server_address {
+ struct __kernel_sockaddr_storage address;
+};
+
#endif /* _UAPI_LINUX_FSINFO_H */
diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
index ab32a15d4c5b..6d856c1c8bad 100644
--- a/samples/vfs/test-fsinfo.c
+++ b/samples/vfs/test-fsinfo.c
@@ -87,6 +87,9 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
FSINFO_STRING (MOUNT_DEVNAME, mount_devname),
FSINFO_STRUCT_ARRAY (MOUNT_CHILDREN, mount_child),
FSINFO_STRING_N (MOUNT_SUBMOUNT, mount_submount),
+ FSINFO_STRING_N (SERVER_NAME, server_name),
+ FSINFO_STRUCT_NM (SERVER_ADDRESS, server_address),
+ FSINFO_STRING (CELL_NAME, cell_name),
};
#define FSINFO_NAME(X,Y) [FSINFO_ATTR_##X] = #Y
@@ -112,6 +115,9 @@ static const char *fsinfo_attr_names[FSINFO_ATTR__NR] = {
FSINFO_NAME (MOUNT_DEVNAME, mount_devname),
FSINFO_NAME (MOUNT_CHILDREN, mount_children),
FSINFO_NAME (MOUNT_SUBMOUNT, mount_submount),
+ FSINFO_NAME (SERVER_NAME, server_name),
+ FSINFO_NAME (SERVER_ADDRESS, server_address),
+ FSINFO_NAME (CELL_NAME, cell_name),
};
union reply {
@@ -126,6 +132,7 @@ union reply {
struct fsinfo_volume_uuid uuid;
struct fsinfo_mount_info mount_info;
struct fsinfo_mount_child mount_children[1];
+ struct fsinfo_server_address srv_addr;
};
static void dump_hex(unsigned int *data, int from, int to)
@@ -329,6 +336,31 @@ static void dump_attr_VOLUME_UUID(union reply *r, int size)
f->uuid[14], f->uuid[15]);
}
+static void dump_attr_SERVER_ADDRESS(union reply *r, int size)
+{
+ struct fsinfo_server_address *f = &r->srv_addr;
+ struct sockaddr_in6 *sin6;
+ struct sockaddr_in *sin;
+ char buf[1024];
+
+ switch (f->address.ss_family) {
+ case AF_INET:
+ sin = (struct sockaddr_in *)&f->address;
+ if (!inet_ntop(AF_INET, &sin->sin_addr, buf, sizeof(buf)))
+ break;
+ printf("IPv4: %s\n", buf);
+ return;
+ case AF_INET6:
+ sin6 = (struct sockaddr_in6 *)&f->address;
+ if (!inet_ntop(AF_INET6, &sin6->sin6_addr, buf, sizeof(buf)))
+ break;
+ printf("IPv6: %s\n", buf);
+ return;
+ }
+
+ printf("family=%u\n", f->address.ss_family);
+}
+
static void dump_attr_MOUNT_INFO(union reply *r, int size)
{
struct fsinfo_mount_info *f = &r->mount_info;
@@ -369,6 +401,7 @@ static const dumper_t fsinfo_attr_dumper[FSINFO_ATTR__NR] = {
FSINFO_DUMPER(VOLUME_UUID),
FSINFO_DUMPER(MOUNT_INFO),
FSINFO_DUMPER(MOUNT_CHILDREN),
+ FSINFO_DUMPER(SERVER_ADDRESS),
};
static void dump_fsinfo(enum fsinfo_attribute attr,
From: Ian Kent <[email protected]>
The new fsinfo() system call adds a new super block operation
->fsinfo() which is used by file systems to provide file
system specific information for fsinfo() requests.
The fsinfo() request FSINFO_ATTR_PARAMETERS provides the same
function as sb operation ->show_options() so it needs to be
implemented by any file system that provides ->show_options()
as a minimum.
Also add a simple FSINFO_ATTR_CAPABILITIES implementation.
Signed-off-by: Ian Kent <[email protected]>
Signed-off-by: David Howells <[email protected]>
---
fs/proc/inode.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 5f8d215b3fd0..28c287aff6aa 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -24,6 +24,7 @@
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/mount.h>
+#include <linux/fsinfo.h>
#include <linux/uaccess.h>
@@ -115,6 +116,39 @@ static int proc_show_options(struct seq_file *seq, struct dentry *root)
return 0;
}
+#ifdef CONFIG_FSINFO
+/*
+ * Get filesystem information.
+ */
+static int proc_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct super_block *sb = path->dentry->d_sb;
+ struct pid_namespace *pid = sb->s_fs_info;
+ struct fsinfo_capabilities *caps;
+
+ switch (params->request) {
+ case FSINFO_ATTR_CAPABILITIES:
+ caps = params->buffer;
+ fsinfo_set_cap(caps, FSINFO_CAP_IS_KERNEL_FS);
+ fsinfo_set_cap(caps, FSINFO_CAP_NOT_PERSISTENT);
+ return sizeof(*caps);
+
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, sb->s_flags);
+ if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID))
+ fsinfo_note_paramf(params, "gid", "%u",
+ from_kgid_munged(&init_user_ns, pid->pid_gid));
+ if (pid->hide_pid != HIDEPID_OFF)
+ fsinfo_note_paramf(params, "hidepid",
+ "%u", pid->hide_pid);
+ return params->usage;
+
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
+
const struct super_operations proc_sops = {
.alloc_inode = proc_alloc_inode,
.free_inode = proc_free_inode,
@@ -122,6 +156,9 @@ const struct super_operations proc_sops = {
.evict_inode = proc_evict_inode,
.statfs = simple_statfs,
.show_options = proc_show_options,
+#ifdef CONFIG_FSINFO
+ .fsinfo = proc_fsinfo,
+#endif
};
enum {BIAS = -1U<<31};
From: Ian Kent <[email protected]>
The new fsinfo() system call adds a new super block operation
->fsinfo() which is used by file systems to provide file
system specific information for fsinfo() requests.
The fsinfo() request FSINFO_ATTR_PARAMETERS provides the same
function as sb operation ->show_options() so it needs to be
implemented by any file system that provides ->show_options()
as a minimum.
Also add a simple FSINFO_ATTR_CAPABILITIES implementation.
Signed-off-by: Ian Kent <[email protected]>
Signed-off-by: David Howells <[email protected]>
---
fs/autofs/inode.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 64 insertions(+)
diff --git a/fs/autofs/inode.c b/fs/autofs/inode.c
index 58457ec0ab27..53e794ee2aec 100644
--- a/fs/autofs/inode.c
+++ b/fs/autofs/inode.c
@@ -11,6 +11,7 @@
#include <linux/pagemap.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
+#include <linux/fsinfo.h>
#include "autofs_i.h"
@@ -101,6 +102,66 @@ static int autofs_show_options(struct seq_file *m, struct dentry *root)
return 0;
}
+#ifdef CONFIG_FSINFO
+/*
+ * Get filesystem information.
+ */
+static int autofs_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct autofs_sb_info *sbi = autofs_sbi(path->dentry->d_sb);
+ struct inode *inode = d_inode(path->dentry->d_sb->s_root);
+ struct fsinfo_capabilities *caps;
+
+ switch (params->request) {
+ case FSINFO_ATTR_CAPABILITIES:
+ caps = params->buffer;
+ fsinfo_set_cap(caps, FSINFO_CAP_IS_AUTOMOUNTER_FS);
+ fsinfo_set_cap(caps, FSINFO_CAP_AUTOMOUNTS);
+ fsinfo_set_cap(caps, FSINFO_CAP_NOT_PERSISTENT);
+ return sizeof(*caps);
+
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, inode->i_sb->s_flags);
+ fsinfo_note_paramf(params, "fd", "%d", sbi->pipefd);
+ if (!uid_eq(inode->i_uid, GLOBAL_ROOT_UID))
+ fsinfo_note_paramf(params, "uid", "%u",
+ from_kuid_munged(&init_user_ns, inode->i_uid));
+ if (!gid_eq(inode->i_gid, GLOBAL_ROOT_GID))
+ fsinfo_note_paramf(params, "gid", "%u",
+ from_kgid_munged(&init_user_ns, inode->i_gid));
+ fsinfo_note_paramf(params, "pgrp", "%d",
+ pid_vnr(sbi->oz_pgrp));
+ fsinfo_note_paramf(params, "timeout", "%lu",
+ sbi->exp_timeout/HZ);
+ fsinfo_note_paramf(params, "minproto", "%d",
+ sbi->min_proto);
+ fsinfo_note_paramf(params, "maxproto", "%d",
+ sbi->max_proto);
+ if (autofs_type_offset(sbi->type))
+ fsinfo_note_param(params, "offset", NULL);
+ else if (autofs_type_direct(sbi->type))
+ fsinfo_note_param(params, "direct", NULL);
+ else
+ fsinfo_note_param(params, "indirect", NULL);
+ if (sbi->flags & AUTOFS_SBI_STRICTEXPIRE)
+ fsinfo_note_param(params, "strictexpire", NULL);
+ if (sbi->flags & AUTOFS_SBI_IGNORE)
+ fsinfo_note_param(params, "ignore", NULL);
+#ifdef CONFIG_CHECKPOINT_RESTORE
+ if (sbi->pipe)
+ fsinfo_note_paramf(params, "pipe_ino",
+ "%ld", file_inode(sbi->pipe)->i_ino);
+ else
+ fsinfo_note_param(params, "pipe_ino", "-1");
+#endif
+ return params->usage;
+
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
+
static void autofs_evict_inode(struct inode *inode)
{
clear_inode(inode);
@@ -111,6 +172,9 @@ static const struct super_operations autofs_sops = {
.statfs = simple_statfs,
.show_options = autofs_show_options,
.evict_inode = autofs_evict_inode,
+#ifdef CONFIG_FSINFO
+ .fsinfo = autofs_fsinfo,
+#endif
};
struct autofs_fs_context {
From: Ian Kent <[email protected]>
The new fsinfo() system call adds a new super block operation
->fsinfo() which is used by file systems to provide file
system specific information for fsinfo() requests.
The fsinfo() request FSINFO_ATTR_PARAMETERS provides the same
function as sb operation ->show_options() so it needs to be
implemented by any file system that provides ->show_options()
as a minimum.
Also add a simple FSINFO_ATTR_CAPABILITIES implementation.
Signed-off-by: Ian Kent <[email protected]>
Signed-off-by: David Howells <[email protected]>
---
fs/devpts/inode.c | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index 3aa73a2ec2f1..6f0eb69f7cbb 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -28,6 +28,7 @@
#include <linux/devpts_fs.h>
#include <linux/fsnotify.h>
#include <linux/seq_file.h>
+#include <linux/fsinfo.h>
#define DEVPTS_DEFAULT_MODE 0600
/*
@@ -401,9 +402,51 @@ static int devpts_show_options(struct seq_file *seq, struct dentry *root)
return 0;
}
+#ifdef CONFIG_FSINFO
+/*
+ * Get filesystem information.
+ */
+static int devpts_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct pts_fs_info *fsi = DEVPTS_SB(path->dentry->d_sb);
+ struct pts_mount_opts *opts = &fsi->mount_opts;
+ struct fsinfo_capabilities *caps;
+
+ switch (params->request) {
+ case FSINFO_ATTR_CAPABILITIES:
+ caps = params->buffer;
+ fsinfo_set_cap(caps, FSINFO_CAP_IS_KERNEL_FS);
+ fsinfo_set_cap(caps, FSINFO_CAP_NOT_PERSISTENT);
+ fsinfo_set_cap(caps, FSINFO_CAP_UIDS);
+ fsinfo_set_cap(caps, FSINFO_CAP_GIDS);
+ return sizeof(*caps);
+
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, path->dentry->d_sb->s_flags);
+ if (opts->setuid)
+ fsinfo_note_paramf(params, "uid", "%u",
+ from_kuid_munged(&init_user_ns, opts->uid));
+ if (opts->setgid)
+ fsinfo_note_paramf(params, "gid", "%u",
+ from_kgid_munged(&init_user_ns, opts->gid));
+ fsinfo_note_paramf(params, "mode", "%03o", opts->mode);
+ fsinfo_note_paramf(params, "ptmxmode", "%03o", opts->ptmxmode);
+ if (opts->max < NR_UNIX98_PTY_MAX)
+ fsinfo_note_paramf(params, "max", "%d", opts->max);
+ return params->usage;
+
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
+
static const struct super_operations devpts_sops = {
.statfs = simple_statfs,
.show_options = devpts_show_options,
+#ifdef CONFIG_FSINFO
+ .fsinfo = devpts_fsinfo,
+#endif
};
static int devpts_fill_super(struct super_block *s, struct fs_context *fc)
From: Ian Kent <[email protected]>
The new fsinfo() system call adds a new super block operation
->fsinfo() which is used by file systems to provide file
system specific information for fsinfo() requests.
The fsinfo() request FSINFO_ATTR_PARAMETERS provides the same
function as sb operation ->show_options() so it needs to be
implemented by any file system that provides ->show_options()
as a minimum.
Signed-off-by: Ian Kent <[email protected]>
Signed-off-by: David Howells <[email protected]>
---
fs/pstore/inode.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 4640debf8755..b2c1751a1c48 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -36,6 +36,7 @@
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
+#include <linux/fsinfo.h>
#include "internal.h"
@@ -281,6 +282,34 @@ static int pstore_show_options(struct seq_file *m, struct dentry *root)
return 0;
}
+#ifdef CONFIG_FSINFO
+/*
+ * Get filesystem information.
+ */
+static int pstore_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct fsinfo_capabilities *caps;
+
+ switch (params->request) {
+ case FSINFO_ATTR_CAPABILITIES:
+ caps = params->buffer;
+ fsinfo_set_cap(caps, FSINFO_CAP_IS_FLASH_FS);
+ fsinfo_set_cap(caps, FSINFO_CAP_HAS_CTIME);
+ fsinfo_set_cap(caps, FSINFO_CAP_HAS_MTIME);
+ return sizeof(*caps);
+
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, path->dentry->d_sb->s_flags);
+ if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
+ fsinfo_note_paramf(params, "kmsg_bytes", "%lu", kmsg_bytes);
+ return params->usage;
+
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
+
static int pstore_reconfigure(struct fs_context *fc)
{
sync_filesystem(fc->root->d_sb);
@@ -293,6 +322,9 @@ static const struct super_operations pstore_ops = {
.drop_inode = generic_delete_inode,
.evict_inode = pstore_evict_inode,
.show_options = pstore_show_options,
+#ifdef CONFIG_FSINFO
+ .fsinfo = pstore_fsinfo,
+#endif
};
static struct super_block *pstore_sb;
From: Ian Kent <[email protected]>
The new fsinfo() system call adds a new super block operation
->fsinfo() which is used by file systems to provide file
system specific information for fsinfo() requests.
The fsinfo() request FSINFO_ATTR_PARAMETERS provides the same
function as sb operation ->show_options() so it needs to be
implemented by any file system that provides ->show_options()
as a minimum.
Also add a simple FSINFO_ATTR_CAPABILITIES implementation.
Signed-off-by: Ian Kent <[email protected]>
Signed-off-by: David Howells <[email protected]>
---
mm/shmem.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 72 insertions(+)
diff --git a/mm/shmem.c b/mm/shmem.c
index 38a77ee13db1..1a660ca7042f 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -39,6 +39,7 @@
#include <linux/frontswap.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
+#include <linux/fsinfo.h>
#include <asm/tlbflush.h> /* for arch/microblaze update_mmu_cache() */
@@ -1403,6 +1404,20 @@ static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
seq_printf(seq, ",mpol=%s", buffer);
}
+#ifdef CONFIG_FSINFO
+static void shmem_fsinfo_mpol(struct fsinfo_kparams *params, struct mempolicy *mpol)
+{
+ char buffer[64];
+
+ if (!mpol || mpol->mode == MPOL_DEFAULT)
+ return; /* show nothing */
+
+ mpol_to_str(buffer, sizeof(buffer), mpol);
+
+ fsinfo_note_paramf(params, "mpol", "%s", buffer);
+}
+#endif
+
static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
{
struct mempolicy *mpol = NULL;
@@ -1418,6 +1433,11 @@ static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
{
}
+#ifdef CONFIG_FSINFO
+static void shmem_fsinfo_mpol(struct fsinfo_kparams *params, struct mempolicy *mpol)
+{
+}
+#endif
static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
{
return NULL;
@@ -3478,7 +3498,9 @@ static int shmem_parse_param(struct fs_context *fc, struct fs_parameter *param)
struct shmem_fs_context *ctx = fc->fs_private;
struct fs_parse_result result;
unsigned long long size;
+#ifdef CONFIG_NUMA
struct mempolicy *mpol;
+#endif
char *rest;
int opt;
@@ -3623,6 +3645,53 @@ static int shmem_show_options(struct seq_file *seq, struct dentry *root)
return 0;
}
+#ifdef CONFIG_FSINFO
+static int shmem_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct shmem_sb_info *sbinfo = SHMEM_SB(path->dentry->d_sb);
+ struct fsinfo_capabilities *caps;
+
+ switch (params->request) {
+ case FSINFO_ATTR_CAPABILITIES:
+ caps = params->buffer;
+ fsinfo_set_unix_caps(caps);
+ fsinfo_set_cap(caps, FSINFO_CAP_IS_MEMORY_FS);
+ fsinfo_set_cap(caps, FSINFO_CAP_NOT_PERSISTENT);
+#ifdef CONFIG_TMPFS_XATTR
+ fsinfo_set_cap(caps, FSINFO_CAP_XATTRS);
+#endif
+ return sizeof(*caps);
+
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, path->dentry->d_sb->s_flags);
+ if (sbinfo->max_blocks != shmem_default_max_blocks())
+ fsinfo_note_paramf(params, "size", "%luk",
+ sbinfo->max_blocks << (PAGE_SHIFT - 10));
+ if (sbinfo->max_inodes != shmem_default_max_inodes())
+ fsinfo_note_paramf(params, "nr_inodes",
+ "%lu", sbinfo->max_inodes);
+ if (sbinfo->mode != (0777 | S_ISVTX))
+ fsinfo_note_paramf(params, "mode",
+ "%03ho", sbinfo->mode);
+ if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
+ fsinfo_note_paramf(params, "uid", "%u",
+ from_kuid_munged(&init_user_ns, sbinfo->uid));
+ if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
+ fsinfo_note_paramf(params, "gid", "%u",
+ from_kgid_munged(&init_user_ns, sbinfo->gid));
+#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
+ /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
+ if (sbinfo->huge)
+ fsinfo_note_paramf(params, "huge", "%s",
+ shmem_format_huge(sbinfo->huge));
+#endif
+ shmem_fsinfo_mpol(params, sbinfo->mpol);
+ return params->usage;
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
#endif /* CONFIG_TMPFS */
static void shmem_put_super(struct super_block *sb)
@@ -3854,6 +3923,9 @@ static const struct super_operations shmem_ops = {
#ifdef CONFIG_TMPFS
.statfs = shmem_statfs,
.show_options = shmem_show_options,
+#ifdef CONFIG_FSINFO
+ .fsinfo = shmem_fsinfo,
+#endif
#endif
.evict_inode = shmem_evict_inode,
.drop_inode = generic_delete_inode,
From: Ian Kent <[email protected]>
The new fsinfo() system call adds a new super block operation
->fsinfo() which is used by file systems to provide file
system specific information for fsinfo() requests.
The fsinfo() request FSINFO_ATTR_PARAMETERS provides the same
function as sb operation ->show_options() so it needs to be
implemented by any file system that provides ->show_options()
as a minimum.
Signed-off-by: Ian Kent <[email protected]>
Signed-off-by: David Howells <[email protected]>
---
kernel/bpf/inode.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 6e22363054b1..8c3575eca976 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -23,6 +23,7 @@
#include <linux/filter.h>
#include <linux/bpf.h>
#include <linux/bpf_trace.h>
+#include <linux/fsinfo.h>
enum bpf_type {
BPF_TYPE_UNSPEC = 0,
@@ -567,6 +568,27 @@ static int bpf_show_options(struct seq_file *m, struct dentry *root)
return 0;
}
+#ifdef CONFIG_FSINFO
+/*
+ * Get filesystem information.
+ */
+static int bpf_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ umode_t mode = d_inode(path->dentry)->i_mode & S_IALLUGO & ~S_ISVTX;
+
+ switch (params->request) {
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, path->dentry->d_sb->s_flags);
+ if (mode != S_IRWXUGO)
+ fsinfo_note_paramf(params, "mode", "%o", mode);
+ return params->usage;
+
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
+
static void bpf_free_inode(struct inode *inode)
{
enum bpf_type type;
@@ -583,6 +605,9 @@ static const struct super_operations bpf_super_ops = {
.drop_inode = generic_delete_inode,
.show_options = bpf_show_options,
.free_inode = bpf_free_inode,
+#ifdef CONFIG_FSINFO
+ .fsinfo = bpf_fsinfo,
+#endif
};
enum {
From: Ian Kent <[email protected]>
The new fsinfo() system call adds a new super block operation
->fsinfo() which is used by file systems to provide file
system specific information for fsinfo() requests.
The fsinfo() request FSINFO_ATTR_PARAMETERS provides the same
function as sb operation ->show_options() so it needs to be
implemented by any file system that provides ->show_options()
as a minimum.
Signed-off-by: Ian Kent <[email protected]>
Signed-off-by: David Howells <[email protected]>
---
fs/ufs/super.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 58 insertions(+)
diff --git a/fs/ufs/super.c b/fs/ufs/super.c
index 84c0c5178cd2..40a3e9db8ac7 100644
--- a/fs/ufs/super.c
+++ b/fs/ufs/super.c
@@ -89,6 +89,7 @@
#include <linux/mount.h>
#include <linux/seq_file.h>
#include <linux/iversion.h>
+#include <linux/fsinfo.h>
#include "ufs_fs.h"
#include "ufs.h"
@@ -1401,6 +1402,60 @@ static int ufs_show_options(struct seq_file *seq, struct dentry *root)
return 0;
}
+#ifdef CONFIG_FSINFO
+static int ufs_fsinfo_print_token(struct fsinfo_kparams *params, const char *token)
+{
+ char *new, *key, *value;
+
+ new = kstrdup(token, GFP_KERNEL);
+ if (!new)
+ return -ENOMEM;
+
+ key = new;
+ value = strchr(new, '=');
+ if (value)
+ *value++ = '\0';
+
+ fsinfo_note_param(params, key, value);
+
+ kfree(new);
+ return 0;
+}
+
+/*
+ * Get filesystem information.
+ */
+static int ufs_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct ufs_sb_info *sbi = UFS_SB(path->dentry->d_sb);
+ unsigned mval = sbi->s_mount_opt & UFS_MOUNT_UFSTYPE;
+ const struct match_token *tp = tokens;
+ int ret;
+
+ switch (params->request) {
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, path->dentry->d_sb->s_flags);
+ while (tp->token != Opt_onerror_panic && tp->token != mval)
+ ++tp;
+ BUG_ON(tp->token == Opt_onerror_panic);
+ ret = ufs_fsinfo_print_token(params, tp->pattern);
+ if (ret)
+ return ret;
+ mval = sbi->s_mount_opt & UFS_MOUNT_ONERROR;
+ while (tp->token != Opt_err && tp->token != mval)
+ ++tp;
+ BUG_ON(tp->token == Opt_err);
+ ret = ufs_fsinfo_print_token(params, tp->pattern);
+ if (ret)
+ return ret;
+ return params->usage;
+
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
+
static int ufs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct super_block *sb = dentry->d_sb;
@@ -1496,6 +1551,9 @@ static const struct super_operations ufs_super_ops = {
.statfs = ufs_statfs,
.remount_fs = ufs_remount,
.show_options = ufs_show_options,
+#ifdef CONFIG_FSINFO
+ .fsinfo = ufs_fsinfo,
+#endif
};
static struct dentry *ufs_mount(struct file_system_type *fs_type,
From: Ian Kent <[email protected]>
The new fsinfo() system call adds a new super block operation
->fsinfo() which is used by file systems to provide file
system specific information for fsinfo() requests.
The fsinfo() request FSINFO_ATTR_PARAMETERS provides the same
function as sb operation ->show_options() so it needs to be
implemented by any file system that provides ->show_options()
as a minimum.
Also add a simple FSINFO_ATTR_CAPABILITIES implementation.
Signed-off-by: Ian Kent <[email protected]>
Signed-off-by: David Howells <[email protected]>
---
fs/debugfs/inode.c | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 24354ccdc968..a5ef136addbb 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -24,6 +24,7 @@
#include <linux/seq_file.h>
#include <linux/magic.h>
#include <linux/slab.h>
+#include <linux/fsinfo.h>
#include "internal.h"
@@ -143,6 +144,40 @@ static int debugfs_show_options(struct seq_file *m, struct dentry *root)
return 0;
}
+#ifdef CONFIG_FSINFO
+/*
+ * Get filesystem information.
+ */
+static int debugfs_fsinfo(struct path *path, struct fsinfo_kparams *params)
+{
+ struct debugfs_fs_info *fsi = path->dentry->d_sb->s_fs_info;
+ struct fsinfo_capabilities *caps;
+
+ switch (params->request) {
+ case FSINFO_ATTR_CAPABILITIES:
+ caps = params->buffer;
+ fsinfo_set_cap(caps, FSINFO_CAP_IS_KERNEL_FS);
+ fsinfo_set_cap(caps, FSINFO_CAP_NOT_PERSISTENT);
+ return sizeof(*caps);
+
+ case FSINFO_ATTR_PARAMETERS:
+ fsinfo_note_sb_params(params, path->dentry->d_sb->s_flags);
+ if (!uid_eq(fsi->uid, GLOBAL_ROOT_UID))
+ fsinfo_note_paramf(params, "uid", "%u",
+ from_kuid_munged(&init_user_ns, fsi->uid));
+ if (!gid_eq(fsi->gid, GLOBAL_ROOT_GID))
+ fsinfo_note_paramf(params, "gid", "%u",
+ from_kgid_munged(&init_user_ns, fsi->gid));
+ if (fsi->mode != DEBUGFS_DEFAULT_MODE)
+ fsinfo_note_paramf(params, "mode", "%o", fsi->mode);
+ return params->usage;
+
+ default:
+ return generic_fsinfo(path, params);
+ }
+}
+#endif /* CONFIG_FSINFO */
+
static void debugfs_free_inode(struct inode *inode)
{
if (S_ISLNK(inode->i_mode))
@@ -154,6 +189,9 @@ static const struct super_operations debugfs_super_operations = {
.statfs = simple_statfs,
.show_options = debugfs_show_options,
.free_inode = debugfs_free_inode,
+#ifdef CONFIG_FSINFO
+ .fsinfo = debugfs_fsinfo,
+#endif
};
static void debugfs_release_dentry(struct dentry *dentry)
On Mon, Jun 24, 2019 at 03:08:54PM +0100, David Howells wrote:
> Add a system call to allow filesystem information to be queried. A request
> value can be given to indicate the desired attribute. Support is provided
> for enumerating multi-value attributes.
>
> ===============
> NEW SYSTEM CALL
> ===============
>
> The new system call looks like:
>
> int ret = fsinfo(int dfd,
> const char *filename,
> const struct fsinfo_params *params,
> void *buffer,
> size_t buf_size);
>
> The params parameter optionally points to a block of parameters:
>
> struct fsinfo_params {
> __u32 at_flags;
> __u32 request;
> __u32 Nth;
> __u32 Mth;
> __u32 __reserved[6];
> };
>
> If params is NULL, it is assumed params->request should be
> fsinfo_attr_statfs, params->Nth should be 0, params->Mth should be 0 and
> params->at_flags should be 0.
>
> If params is given, all of params->__reserved[] must be 0.
>
> dfd, filename and params->at_flags indicate the file to query. There is no
> equivalent of lstat() as that can be emulated with fsinfo() by setting
> AT_SYMLINK_NOFOLLOW in params->at_flags. There is also no equivalent of
> fstat() as that can be emulated by passing a NULL filename to fsinfo() with
> the fd of interest in dfd. AT_NO_AUTOMOUNT can also be used to an allow
> automount point to be queried without triggering it.
>
> params->request indicates the attribute/attributes to be queried. This can
> be one of:
>
> FSINFO_ATTR_STATFS - statfs-style info
> FSINFO_ATTR_FSINFO - Information about fsinfo()
> FSINFO_ATTR_IDS - Filesystem IDs
> FSINFO_ATTR_LIMITS - Filesystem limits
> FSINFO_ATTR_SUPPORTS - What's supported in statx(), IOC flags
> FSINFO_ATTR_CAPABILITIES - Filesystem capabilities
> FSINFO_ATTR_TIMESTAMP_INFO - Inode timestamp info
> FSINFO_ATTR_VOLUME_ID - Volume ID (string)
> FSINFO_ATTR_VOLUME_UUID - Volume UUID
> FSINFO_ATTR_VOLUME_NAME - Volume name (string)
> FSINFO_ATTR_NAME_ENCODING - Filename encoding (string)
> FSINFO_ATTR_NAME_CODEPAGE - Filename codepage (string)
>
> Some attributes (such as the servers backing a network filesystem) can have
> multiple values. These can be enumerated by setting params->Nth and
> params->Mth to 0, 1, ... until ENODATA is returned.
>
> buffer and buf_size point to the reply buffer. The buffer is filled up to
> the specified size, even if this means truncating the reply. The full size
> of the reply is returned. In future versions, this will allow extra fields
> to be tacked on to the end of the reply, but anyone not expecting them will
> only get the subset they're expecting. If either buffer of buf_size are 0,
> no copy will take place and the data size will be returned.
>
> At the moment, this will only work on x86_64 and i386 as it requires the
> system call to be wired up.
>
> Signed-off-by: David Howells <[email protected]>
> cc: [email protected]
> ---
>
> arch/x86/entry/syscalls/syscall_32.tbl | 1
> arch/x86/entry/syscalls/syscall_64.tbl | 1
> fs/Kconfig | 7
> fs/Makefile | 1
> fs/fsinfo.c | 537 +++++++++++++++++++++++++++++++
> include/linux/fs.h | 5
> include/linux/fsinfo.h | 66 ++++
> include/linux/syscalls.h | 4
> include/uapi/asm-generic/unistd.h | 4
> include/uapi/linux/fsinfo.h | 219 +++++++++++++
> kernel/sys_ni.c | 1
> samples/vfs/Makefile | 4
> samples/vfs/test-fsinfo.c | 551 ++++++++++++++++++++++++++++++++
> 13 files changed, 1400 insertions(+), 1 deletion(-)
> create mode 100644 fs/fsinfo.c
> create mode 100644 include/linux/fsinfo.h
> create mode 100644 include/uapi/linux/fsinfo.h
> create mode 100644 samples/vfs/test-fsinfo.c
>
> diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
> index ad968b7bac72..03decae51513 100644
> --- a/arch/x86/entry/syscalls/syscall_32.tbl
> +++ b/arch/x86/entry/syscalls/syscall_32.tbl
> @@ -438,3 +438,4 @@
> 431 i386 fsconfig sys_fsconfig __ia32_sys_fsconfig
> 432 i386 fsmount sys_fsmount __ia32_sys_fsmount
> 433 i386 fspick sys_fspick __ia32_sys_fspick
> +434 i386 fsinfo sys_fsinfo __ia32_sys_fsinfo
> diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
> index b4e6f9e6204a..ea63df9a1020 100644
> --- a/arch/x86/entry/syscalls/syscall_64.tbl
> +++ b/arch/x86/entry/syscalls/syscall_64.tbl
> @@ -355,6 +355,7 @@
> 431 common fsconfig __x64_sys_fsconfig
> 432 common fsmount __x64_sys_fsmount
> 433 common fspick __x64_sys_fspick
> +434 common fsinfo __x64_sys_fsinfo
>
> #
> # x32-specific system call numbers start at 512 to avoid cache impact
> diff --git a/fs/Kconfig b/fs/Kconfig
> index cbbffc8b9ef5..9e7d2f2c0111 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -15,6 +15,13 @@ config VALIDATE_FS_PARSER
> Enable this to perform validation of the parameter description for a
> filesystem when it is registered.
>
> +config FSINFO
> + bool "Enable the fsinfo() system call"
> + help
> + Enable the file system information querying system call to allow
> + comprehensive information to be retrieved about a filesystem,
> + superblock or mount object.
> +
> if BLOCK
>
> config FS_IOMAP
> diff --git a/fs/Makefile b/fs/Makefile
> index c9aea23aba56..26eaeae4b9a1 100644
> --- a/fs/Makefile
> +++ b/fs/Makefile
> @@ -53,6 +53,7 @@ obj-$(CONFIG_SYSCTL) += drop_caches.o
>
> obj-$(CONFIG_FHANDLE) += fhandle.o
> obj-$(CONFIG_FS_IOMAP) += iomap.o
> +obj-$(CONFIG_FSINFO) += fsinfo.o
>
> obj-y += quota/
>
> diff --git a/fs/fsinfo.c b/fs/fsinfo.c
> new file mode 100644
> index 000000000000..49b46f96dda3
> --- /dev/null
> +++ b/fs/fsinfo.c
> @@ -0,0 +1,537 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <linux/syscalls.h>
> +#include <linux/fs.h>
> +#include <linux/file.h>
> +#include <linux/mount.h>
> +#include <linux/namei.h>
> +#include <linux/statfs.h>
> +#include <linux/security.h>
> +#include <linux/uaccess.h>
> +#include <linux/fsinfo.h>
> +#include <uapi/linux/mount.h>
> +#include "internal.h"
> +
> +static u32 calc_mount_attrs(u32 mnt_flags)
> +{
> + u32 attrs = 0;
> +
> + if (mnt_flags & MNT_READONLY)
> + attrs |= MOUNT_ATTR_RDONLY;
> + if (mnt_flags & MNT_NOSUID)
> + attrs |= MOUNT_ATTR_NOSUID;
> + if (mnt_flags & MNT_NODEV)
> + attrs |= MOUNT_ATTR_NODEV;
> + if (mnt_flags & MNT_NOEXEC)
> + attrs |= MOUNT_ATTR_NOEXEC;
> + if (mnt_flags & MNT_NODIRATIME)
> + attrs |= MOUNT_ATTR_NODIRATIME;
> +
> + if (mnt_flags & MNT_NOATIME)
> + attrs |= MOUNT_ATTR_NOATIME;
> + else if (mnt_flags & MNT_RELATIME)
> + attrs |= MOUNT_ATTR_RELATIME;
> + else
> + attrs |= MOUNT_ATTR_STRICTATIME;
> + return attrs;
> +}
> +
> +/*
> + * Get basic filesystem stats from statfs.
> + */
> +static int fsinfo_generic_statfs(struct path *path, struct fsinfo_statfs *p)
> +{
> + struct kstatfs buf;
> + int ret;
> +
> + ret = vfs_statfs(path, &buf);
> + if (ret < 0)
> + return ret;
> +
> + p->f_blocks.hi = 0;
> + p->f_blocks.lo = buf.f_blocks;
> + p->f_bfree.hi = 0;
> + p->f_bfree.lo = buf.f_bfree;
> + p->f_bavail.hi = 0;
> + p->f_bavail.lo = buf.f_bavail;
> + p->f_files.hi = 0;
> + p->f_files.lo = buf.f_files;
> + p->f_ffree.hi = 0;
> + p->f_ffree.lo = buf.f_ffree;
> + p->f_favail.hi = 0;
> + p->f_favail.lo = buf.f_ffree;
> + p->f_bsize = buf.f_bsize;
> + p->f_frsize = buf.f_frsize;
> +
> + p->mnt_attrs = calc_mount_attrs(path->mnt->mnt_flags);
> + return sizeof(*p);
Hm, the discrepancy between the function signature returning int and
the sizeof operator most likely being size_t is bothering me. It
probably doesn't matter but maybe we can avoid that.
> +}
> +
> +static int fsinfo_generic_ids(struct path *path, struct fsinfo_ids *p)
> +{
> + struct super_block *sb;
> + struct kstatfs buf;
> + int ret;
> +
> + ret = vfs_statfs(path, &buf);
> + if (ret < 0 && ret != -ENOSYS)
> + return ret;
> +
> + sb = path->dentry->d_sb;
> + p->f_fstype = sb->s_magic;
> + p->f_dev_major = MAJOR(sb->s_dev);
> + p->f_dev_minor = MINOR(sb->s_dev);
> +
> + memcpy(&p->f_fsid, &buf.f_fsid, sizeof(p->f_fsid));
> + strlcpy(p->f_fs_name, path->dentry->d_sb->s_type->name,
> + sizeof(p->f_fs_name));
Truncation is acceptable or impossible I assume?
> + return sizeof(*p);
> +}
> +
> +static int fsinfo_generic_limits(struct path *path, struct fsinfo_limits *lim)
> +{
> + struct super_block *sb = path->dentry->d_sb;
> +
> + lim->max_file_size.hi = 0;
> + lim->max_file_size.lo = sb->s_maxbytes;
> + lim->max_hard_links = sb->s_max_links;
> + lim->max_uid = UINT_MAX;
> + lim->max_gid = UINT_MAX;
> + lim->max_projid = UINT_MAX;
> + lim->max_filename_len = NAME_MAX;
> + lim->max_symlink_len = PAGE_SIZE;
> + lim->max_xattr_name_len = XATTR_NAME_MAX;
> + lim->max_xattr_body_len = XATTR_SIZE_MAX;
> + lim->max_dev_major = 0xffffff;
> + lim->max_dev_minor = 0xff;
> + return sizeof(*lim);
> +}
> +
> +static int fsinfo_generic_supports(struct path *path, struct fsinfo_supports *c)
> +{
> + struct super_block *sb = path->dentry->d_sb;
> +
> + c->stx_mask = STATX_BASIC_STATS;
> + if (sb->s_d_op && sb->s_d_op->d_automount)
> + c->stx_attributes |= STATX_ATTR_AUTOMOUNT;
> + return sizeof(*c);
> +}
> +
> +static int fsinfo_generic_capabilities(struct path *path,
> + struct fsinfo_capabilities *c)
> +{
> + struct super_block *sb = path->dentry->d_sb;
> +
> + if (sb->s_mtd)
> + fsinfo_set_cap(c, FSINFO_CAP_IS_FLASH_FS);
> + else if (sb->s_bdev)
> + fsinfo_set_cap(c, FSINFO_CAP_IS_BLOCK_FS);
> +
> + if (sb->s_quota_types & QTYPE_MASK_USR)
> + fsinfo_set_cap(c, FSINFO_CAP_USER_QUOTAS);
> + if (sb->s_quota_types & QTYPE_MASK_GRP)
> + fsinfo_set_cap(c, FSINFO_CAP_GROUP_QUOTAS);
> + if (sb->s_quota_types & QTYPE_MASK_PRJ)
> + fsinfo_set_cap(c, FSINFO_CAP_PROJECT_QUOTAS);
> + if (sb->s_d_op && sb->s_d_op->d_automount)
> + fsinfo_set_cap(c, FSINFO_CAP_AUTOMOUNTS);
> + if (sb->s_id[0])
> + fsinfo_set_cap(c, FSINFO_CAP_VOLUME_ID);
> +
> + fsinfo_set_cap(c, FSINFO_CAP_HAS_ATIME);
> + fsinfo_set_cap(c, FSINFO_CAP_HAS_CTIME);
> + fsinfo_set_cap(c, FSINFO_CAP_HAS_MTIME);
> + return sizeof(*c);
> +}
> +
> +static const struct fsinfo_timestamp_info fsinfo_default_timestamp_info = {
> + .atime = {
> + .minimum = S64_MIN,
> + .maximum = S64_MAX,
> + .gran_mantissa = 1,
> + .gran_exponent = 0,
> + },
> + .mtime = {
> + .minimum = S64_MIN,
> + .maximum = S64_MAX,
> + .gran_mantissa = 1,
> + .gran_exponent = 0,
> + },
> + .ctime = {
> + .minimum = S64_MIN,
> + .maximum = S64_MAX,
> + .gran_mantissa = 1,
> + .gran_exponent = 0,
> + },
> + .btime = {
> + .minimum = S64_MIN,
> + .maximum = S64_MAX,
> + .gran_mantissa = 1,
> + .gran_exponent = 0,
> + },
> +};
> +
> +static int fsinfo_generic_timestamp_info(struct path *path,
> + struct fsinfo_timestamp_info *ts)
> +{
> + struct super_block *sb = path->dentry->d_sb;
> + s8 exponent;
> +
> + *ts = fsinfo_default_timestamp_info;
> +
> +
> + if (sb->s_time_gran < 1000000000) {
> + if (sb->s_time_gran < 1000)
> + exponent = -9;
> + else if (sb->s_time_gran < 1000000)
> + exponent = -6;
> + else
> + exponent = -3;
> +
> + ts->atime.gran_exponent = exponent;
> + ts->mtime.gran_exponent = exponent;
> + ts->ctime.gran_exponent = exponent;
> + ts->btime.gran_exponent = exponent;
> + }
> +
> + return sizeof(*ts);
> +}
> +
> +static int fsinfo_generic_volume_uuid(struct path *path,
> + struct fsinfo_volume_uuid *vu)
> +{
> + struct super_block *sb = path->dentry->d_sb;
> +
> + memcpy(vu, &sb->s_uuid, sizeof(*vu));
> + return sizeof(*vu);
> +}
> +
> +static int fsinfo_generic_volume_id(struct path *path, char *buf)
> +{
> + struct super_block *sb = path->dentry->d_sb;
> + size_t len = strlen(sb->s_id);
> +
> + memcpy(buf, sb->s_id, len + 1);
> + return len;
> +}
> +
> +static int fsinfo_generic_name_encoding(struct path *path, char *buf)
> +{
> + static const char encoding[] = "utf8";
> +
> + memcpy(buf, encoding, sizeof(encoding) - 1);
> + return sizeof(encoding) - 1;
> +}
> +
> +/*
> + * Implement some queries generically from stuff in the superblock.
> + */
> +int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
> +{
> +#define _gen(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(path, params->buffer)
I'm really not sure that this helps readability in the switch below... :)
> +
> + switch (params->request) {
> + case _gen(STATFS, statfs);
> + case _gen(IDS, ids);
> + case _gen(LIMITS, limits);
> + case _gen(SUPPORTS, supports);
> + case _gen(CAPABILITIES, capabilities);
> + case _gen(TIMESTAMP_INFO, timestamp_info);
> + case _gen(VOLUME_UUID, volume_uuid);
> + case _gen(VOLUME_ID, volume_id);
> + case _gen(NAME_ENCODING, name_encoding);
> + default:
> + return -EOPNOTSUPP;
> + }
> +}
> +EXPORT_SYMBOL(generic_fsinfo);
> +
> +/*
> + * Retrieve the filesystem info. We make some stuff up if the operation is not
> + * supported.
> + */
> +static int vfs_fsinfo(struct path *path, struct fsinfo_kparams *params)
> +{
> + struct dentry *dentry = path->dentry;
> + int (*fsinfo)(struct path *, struct fsinfo_kparams *);
> + int ret;
> +
> + if (params->request == FSINFO_ATTR_FSINFO) {
> + struct fsinfo_fsinfo *info = params->buffer;
> +
> + info->max_attr = FSINFO_ATTR__NR;
> + info->max_cap = FSINFO_CAP__NR;
> + return sizeof(*info);
> + }
> +
> + fsinfo = dentry->d_sb->s_op->fsinfo;
> + if (!fsinfo) {
> + if (!dentry->d_sb->s_op->statfs)
> + return -EOPNOTSUPP;
> + fsinfo = generic_fsinfo;
> + }
> +
> + ret = security_sb_statfs(dentry);
> + if (ret)
> + return ret;
> +
> + if (!params->overlarge)
> + return fsinfo(path, params);
> +
> + while (!signal_pending(current)) {
> + params->usage = 0;
> + ret = fsinfo(path, params);
> + if (ret <= (int)params->buf_size)
He, and this is where the return value discrepancy hits again. Just
doesn't look nice tbh. :)
> + return ret; /* Error or it fitted */
> + kvfree(params->buffer);
That means callers should always memset fsinfo_kparams or this is an
invalid free...
> + params->buffer = NULL;
> + params->buf_size = roundup(ret, PAGE_SIZE);
> + if (params->buf_size > INT_MAX)
> + return -ETOOSMALL;
> + params->buffer = kvmalloc(params->buf_size, GFP_KERNEL);
> + if (!params->buffer)
> + return -ENOMEM;
> + }
> +
> + return -ERESTARTSYS;
> +}
> +
> +static int vfs_fsinfo_path(int dfd, const char __user *filename,
> + struct fsinfo_kparams *params)
> +{
> + struct path path;
> + unsigned lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
> + int ret = -EINVAL;
> +
> + if ((params->at_flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
> + AT_EMPTY_PATH)) != 0)
> + return -EINVAL;
> +
> + if (params->at_flags & AT_SYMLINK_NOFOLLOW)
> + lookup_flags &= ~LOOKUP_FOLLOW;
> + if (params->at_flags & AT_NO_AUTOMOUNT)
> + lookup_flags &= ~LOOKUP_AUTOMOUNT;
> + if (params->at_flags & AT_EMPTY_PATH)
> + lookup_flags |= LOOKUP_EMPTY;
> +
> +retry:
> + ret = user_path_at(dfd, filename, lookup_flags, &path);
> + if (ret)
> + goto out;
> +
> + ret = vfs_fsinfo(&path, params);
> + path_put(&path);
> + if (retry_estale(ret, lookup_flags)) {
> + lookup_flags |= LOOKUP_REVAL;
> + goto retry;
> + }
> +out:
> + return ret;
> +}
> +
> +static int vfs_fsinfo_fd(unsigned int fd, struct fsinfo_kparams *params)
> +{
> + struct fd f = fdget_raw(fd);
> + int ret = -EBADF;
> +
> + if (f.file) {
> + ret = vfs_fsinfo(&f.file->f_path, params);
> + fdput(f);
> + }
> + return ret;
> +}
> +
> +/*
> + * Return buffer information by requestable attribute.
> + *
> + * STRUCT indicates a fixed-size structure with only one instance.
> + * STRUCT_N indicates a 1D array of STRUCT, indexed by Nth
> + * STRUCT_NM indicates a 2D-array of STRUCT, indexed by Nth, Mth
> + * STRING indicates a string with only one instance.
> + * STRING_N indicates a 1D array of STRING, indexed by Nth
> + * STRING_NM indicates a 2D-array of STRING, indexed by Nth, Mth
> + * OPAQUE indicates a blob that can be larger than 4K.
> + * STRUCT_ARRAY indicates an array of structs that can be larger than 4K
I honestly have a hard time following the documentation here and that
monster table/macro thing below. For example, STRUCT_NM corresponds to
__FSINFO_NM or what? And is this uapi as you're using this in your
samples/test below?
> + *
> + * If an entry is marked STRUCT, STRUCT_N or STRUCT_NM then if no buffer is
> + * supplied to sys_fsinfo(), sys_fsinfo() will handle returning the buffer size
> + * without calling vfs_fsinfo() and the filesystem.
> + *
> + * No struct may have more than 4K bytes.
> + */
> +struct fsinfo_attr_info {
> + u8 type;
> + u8 flags;
> + u16 size;
> +};
> +
> +#define __FSINFO_STRUCT 0
> +#define __FSINFO_STRING 1
> +#define __FSINFO_OPAQUE 2
> +#define __FSINFO_STRUCT_ARRAY 3
> +#define __FSINFO_0 0
> +#define __FSINFO_N 0x0001
> +#define __FSINFO_NM 0x0002
> +
> +#define _Z(T, F, S) { .type = __FSINFO_##T, .flags = __FSINFO_##F, .size = S }
> +#define FSINFO_STRING(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, 0, 0)
> +#define FSINFO_STRUCT(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, 0, sizeof(struct fsinfo_##Y))
> +#define FSINFO_STRING_N(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, N, 0)
> +#define FSINFO_STRUCT_N(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, N, sizeof(struct fsinfo_##Y))
> +#define FSINFO_STRING_NM(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, NM, 0)
> +#define FSINFO_STRUCT_NM(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, NM, sizeof(struct fsinfo_##Y))
> +#define FSINFO_OPAQUE(X,Y) [FSINFO_ATTR_##X] = _Z(OPAQUE, 0, 0)
> +#define FSINFO_STRUCT_ARRAY(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT_ARRAY, 0, sizeof(struct fsinfo_##Y))
> +
> +static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
> + FSINFO_STRUCT (STATFS, statfs),
> + FSINFO_STRUCT (FSINFO, fsinfo),
> + FSINFO_STRUCT (IDS, ids),
> + FSINFO_STRUCT (LIMITS, limits),
> + FSINFO_STRUCT (CAPABILITIES, capabilities),
> + FSINFO_STRUCT (SUPPORTS, supports),
> + FSINFO_STRUCT (TIMESTAMP_INFO, timestamp_info),
> + FSINFO_STRING (VOLUME_ID, volume_id),
> + FSINFO_STRUCT (VOLUME_UUID, volume_uuid),
> + FSINFO_STRING (VOLUME_NAME, -),
> + FSINFO_STRING (NAME_ENCODING, -),
> + FSINFO_STRING (NAME_CODEPAGE, -),
> +};
Can I complain again that this is really annoying to parse.
> +
> +/**
> + * sys_fsinfo - System call to get filesystem information
> + * @dfd: Base directory to pathwalk from or fd referring to filesystem.
> + * @filename: Filesystem to query or NULL.
> + * @_params: Parameters to define request (or NULL for enhanced statfs).
> + * @user_buffer: Result buffer.
> + * @user_buf_size: Size of result buffer.
> + *
> + * Get information on a filesystem. The filesystem attribute to be queried is
> + * indicated by @_params->request, and some of the attributes can have multiple
> + * values, indexed by @_params->Nth and @_params->Mth. If @_params is NULL,
> + * then the 0th fsinfo_attr_statfs attribute is queried. If an attribute does
> + * not exist, EOPNOTSUPP is returned; if the Nth,Mth value does not exist,
> + * ENODATA is returned.
> + *
> + * On success, the size of the attribute's value is returned. If
> + * @user_buf_size is 0 or @user_buffer is NULL, only the size is returned. If
> + * the size of the value is larger than @user_buf_size, it will be truncated by
> + * the copy. If the size of the value is smaller than @user_buf_size then the
> + * excess buffer space will be cleared. The full size of the value will be
> + * returned, irrespective of how much data is actually placed in the buffer.
> + */
> +SYSCALL_DEFINE5(fsinfo,
> + int, dfd, const char __user *, filename,
> + struct fsinfo_params __user *, _params,
> + void __user *, user_buffer, size_t, user_buf_size)
> +{
> + struct fsinfo_attr_info info;
> + struct fsinfo_params user_params;
> + struct fsinfo_kparams params;
> + unsigned int result_size;
> + int ret;
> +
> + memset(¶ms, 0, sizeof(params));
> +
> + if (_params) {
> + if (copy_from_user(&user_params, _params, sizeof(user_params)))
> + return -EFAULT;
> + if (user_params.__reserved[0] ||
> + user_params.__reserved[1] ||
> + user_params.__reserved[2])
> + return -EINVAL;
Hm, aren't there 6 reserved fields?
> + if (user_params.request >= FSINFO_ATTR__NR)
> + return -EOPNOTSUPP;
> + params.at_flags = user_params.at_flags;
> + params.request = user_params.request;
> + params.Nth = user_params.Nth;
> + params.Mth = user_params.Mth;
> + } else {
> + params.request = FSINFO_ATTR_STATFS;
> + }
> +
> + if (!user_buffer || !user_buf_size) {
> + user_buf_size = 0;
> + user_buffer = NULL;
> + }
> +
> + /* Allocate an appropriately-sized buffer. We will truncate the
> + * contents when we write the contents back to userspace.
> + */
> + info = fsinfo_buffer_info[params.request];
> + if (params.Nth != 0 && !(info.flags & (__FSINFO_N | __FSINFO_NM)))
> + return -ENODATA;
> + if (params.Mth != 0 && !(info.flags & __FSINFO_NM))
> + return -ENODATA;
> +
> + switch (info.type) {
> + case __FSINFO_STRUCT:
> + params.buf_size = info.size;
> + if (user_buf_size == 0)
> + return info.size; /* We know how big the buffer should be */
> + break;
> +
> + case __FSINFO_STRING:
> + params.buf_size = 4096;
> + break;
> +
> + case __FSINFO_OPAQUE:
> + case __FSINFO_STRUCT_ARRAY:
> + /* Opaque blob or array of struct elements. We also create a
> + * buffer that can be used for scratch space.
> + */
> + ret = -ENOMEM;
> + params.scratch_buffer = kmalloc(4096, GFP_KERNEL);
> + if (!params.scratch_buffer)
> + goto error;
> + params.overlarge = true;
> + params.buf_size = 4096;
All the 4096 could probably be macros, FSATTR_GOOD_SIZE or whatever name
you might like.
> + break;
> +
> + default:
> + return -ENOBUFS;
> + }
> +
> + /* We always allocate a buffer for a string, even if buf_size == 0 and
> + * we're not going to return any data. This means that the filesystem
> + * code needn't care about whether the buffer actually exists or not.
> + */
> + ret = -ENOMEM;
> + params.buffer = kvzalloc(params.buf_size, GFP_KERNEL);
> + if (!params.buffer)
> + goto error_scratch;
> +
> + if (filename)
> + ret = vfs_fsinfo_path(dfd, filename, ¶ms);
> + else
> + ret = vfs_fsinfo_fd(dfd, ¶ms);
> + if (ret < 0)
> + goto error_buffer;
> +
> + result_size = ret;
> + if (result_size > user_buf_size)
> + result_size = user_buf_size;
> +
> + if (result_size > 0 &&
> + copy_to_user(user_buffer, params.buffer, result_size)) {
> + ret = -EFAULT;
> + goto error_buffer;
> + }
> +
> + /* Clear any part of the buffer that we won't fill if we're putting a
> + * struct in there. Strings, opaque objects and arrays are expected to
> + * be variable length.
> + */
> + if (info.type == __FSINFO_STRUCT &&
> + user_buf_size > result_size &&
> + clear_user(user_buffer + result_size, user_buf_size - result_size) != 0) {
For consistency you could error check the clear_user() the same way as
copy_to_user(), i.e.
if (copy_to_user()) and if (clear_user()) and not if (clear_user() != 0)
> + ret = -EFAULT;
> + goto error_buffer;
> + }
> +
> +error_buffer:
> + kvfree(params.buffer);
> +error_scratch:
> + kfree(params.scratch_buffer);
> +error:
> + return ret;
> +}
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 6a38b7124143..71ce3b054c42 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -66,6 +66,8 @@ struct fscrypt_info;
> struct fscrypt_operations;
> struct fs_context;
> struct fs_parameter_description;
> +struct fsinfo_kparams;
> +enum fsinfo_attribute;
>
> extern void __init inode_init(void);
> extern void __init inode_init_early(void);
> @@ -1922,6 +1924,9 @@ struct super_operations {
> int (*thaw_super) (struct super_block *);
> int (*unfreeze_fs) (struct super_block *);
> int (*statfs) (struct dentry *, struct kstatfs *);
> +#ifdef CONFIG_FSINFO
> + int (*fsinfo) (struct path *, struct fsinfo_kparams *);
> +#endif
> int (*remount_fs) (struct super_block *, int *, char *);
> void (*umount_begin) (struct super_block *);
>
> diff --git a/include/linux/fsinfo.h b/include/linux/fsinfo.h
> new file mode 100644
> index 000000000000..e17e4f0bae18
> --- /dev/null
> +++ b/include/linux/fsinfo.h
> @@ -0,0 +1,66 @@
> +/* Filesystem information query
> + *
> + * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells ([email protected])
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public Licence
> + * as published by the Free Software Foundation; either version
> + * 2 of the Licence, or (at your option) any later version.
> + */
That should be an SPDX line I would expect. Otherwise Thomas and Greg
can do another round of conversions right after this patchset. :)
> +
> +#ifndef _LINUX_FSINFO_H
> +#define _LINUX_FSINFO_H
> +
> +#ifdef CONFIG_FSINFO
> +
> +#include <uapi/linux/fsinfo.h>
> +
> +struct fsinfo_kparams {
> + __u32 at_flags; /* AT_SYMLINK_NOFOLLOW and similar */
> + enum fsinfo_attribute request; /* What is being asking for */
> + __u32 Nth; /* Instance of it (some may have multiple) */
> + __u32 Mth; /* Subinstance */
> + bool overlarge; /* T if the buffer may be resized */
> + unsigned int usage; /* Amount of buffer used (overlarge=T) */
> + unsigned int buf_size; /* Size of ->buffer[] */
> + void *buffer; /* Where to place the reply */
> + char *scratch_buffer; /* 4K scratch buffer (overlarge=T) */
> +};
> +
> +extern int generic_fsinfo(struct path *, struct fsinfo_kparams *);
> +
> +static inline void fsinfo_set_cap(struct fsinfo_capabilities *c,
> + enum fsinfo_capability cap)
> +{
> + c->capabilities[cap / 8] |= 1 << (cap % 8);
> +}
> +
> +static inline void fsinfo_clear_cap(struct fsinfo_capabilities *c,
> + enum fsinfo_capability cap)
> +{
> + c->capabilities[cap / 8] &= ~(1 << (cap % 8));
> +}
> +
> +/**
> + * fsinfo_set_unix_caps - Set standard UNIX capabilities.
> + * @c: The capabilities mask to alter
> + */
> +static inline void fsinfo_set_unix_caps(struct fsinfo_capabilities *caps)
> +{
> + fsinfo_set_cap(caps, FSINFO_CAP_UIDS);
> + fsinfo_set_cap(caps, FSINFO_CAP_GIDS);
> + fsinfo_set_cap(caps, FSINFO_CAP_DIRECTORIES);
> + fsinfo_set_cap(caps, FSINFO_CAP_SYMLINKS);
> + fsinfo_set_cap(caps, FSINFO_CAP_HARD_LINKS);
> + fsinfo_set_cap(caps, FSINFO_CAP_DEVICE_FILES);
> + fsinfo_set_cap(caps, FSINFO_CAP_UNIX_SPECIALS);
> + fsinfo_set_cap(caps, FSINFO_CAP_SPARSE);
> + fsinfo_set_cap(caps, FSINFO_CAP_HAS_ATIME);
> + fsinfo_set_cap(caps, FSINFO_CAP_HAS_CTIME);
> + fsinfo_set_cap(caps, FSINFO_CAP_HAS_MTIME);
> +}
> +
> +#endif /* CONFIG_FSINFO */
> +
> +#endif /* _LINUX_FSINFO_H */
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index e2870fe1be5b..217d25b62b4f 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -50,6 +50,7 @@ struct stat64;
> struct statfs;
> struct statfs64;
> struct statx;
> +struct fsinfo_params;
> struct __sysctl_args;
> struct sysinfo;
> struct timespec;
> @@ -997,6 +998,9 @@ asmlinkage long sys_fspick(int dfd, const char __user *path, unsigned int flags)
> asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
> siginfo_t __user *info,
> unsigned int flags);
> +asmlinkage long sys_fsinfo(int dfd, const char __user *path,
> + struct fsinfo_params __user *params,
> + void __user *buffer, size_t buf_size);
Nit: There's a bunch of name inconsistency for the arguments between the
stub and the definition:
SYSCALL_DEFINE5(fsinfo,
int, dfd, const char __user *, filename,
struct fsinfo_params __user *, _params,
void __user *, user_buffer, size_t, user_buf_size)
>
> /*
> * Architecture-specific system calls
> diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
> index a87904daf103..50ddf5f25122 100644
> --- a/include/uapi/asm-generic/unistd.h
> +++ b/include/uapi/asm-generic/unistd.h
> @@ -844,9 +844,11 @@ __SYSCALL(__NR_fsconfig, sys_fsconfig)
> __SYSCALL(__NR_fsmount, sys_fsmount)
> #define __NR_fspick 433
> __SYSCALL(__NR_fspick, sys_fspick)
> +#define __NR_fsinfo 434
> +__SYSCALL(__NR_fsinfo, sys_fsinfo)
>
> #undef __NR_syscalls
> -#define __NR_syscalls 434
> +#define __NR_syscalls 435
>
> /*
> * 32 bit systems traditionally used different
> diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
> new file mode 100644
> index 000000000000..a7a7c731d992
> --- /dev/null
> +++ b/include/uapi/linux/fsinfo.h
> @@ -0,0 +1,219 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +/* fsinfo() definitions.
> + *
> + * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells ([email protected])
> + */
Do we do SPDX that way? Or isn't this just supposed to be:
// <spdxy stuff>
> +#ifndef _UAPI_LINUX_FSINFO_H
> +#define _UAPI_LINUX_FSINFO_H
> +
> +#include <linux/types.h>
> +#include <linux/socket.h>
> +
> +/*
> + * The filesystem attributes that can be requested. Note that some attributes
> + * may have multiple instances which can be switched in the parameter block.
> + */
> +enum fsinfo_attribute {
> + FSINFO_ATTR_STATFS = 0, /* statfs()-style state */
> + FSINFO_ATTR_FSINFO = 1, /* Information about fsinfo() */
> + FSINFO_ATTR_IDS = 2, /* Filesystem IDs */
> + FSINFO_ATTR_LIMITS = 3, /* Filesystem limits */
> + FSINFO_ATTR_SUPPORTS = 4, /* What's supported in statx, iocflags, ... */
> + FSINFO_ATTR_CAPABILITIES = 5, /* Filesystem capabilities (bits) */
> + FSINFO_ATTR_TIMESTAMP_INFO = 6, /* Inode timestamp info */
> + FSINFO_ATTR_VOLUME_ID = 7, /* Volume ID (string) */
> + FSINFO_ATTR_VOLUME_UUID = 8, /* Volume UUID (LE uuid) */
> + FSINFO_ATTR_VOLUME_NAME = 9, /* Volume name (string) */
> + FSINFO_ATTR_NAME_ENCODING = 10, /* Filename encoding (string) */
> + FSINFO_ATTR_NAME_CODEPAGE = 11, /* Filename codepage (string) */
> + FSINFO_ATTR__NR
Nit/Bikeshed: FSINFO_ATTR_MAX? Seems more intuitive.
> +};
> +
> +/*
> + * Optional fsinfo() parameter structure.
> + *
> + * If this is not given, it is assumed that fsinfo_attr_statfs instance 0,0 is
> + * desired.
> + */
> +struct fsinfo_params {
> + __u32 at_flags; /* AT_SYMLINK_NOFOLLOW and similar flags */
> + __u32 request; /* What is being asking for (enum fsinfo_attribute) */
> + __u32 Nth; /* Instance of it (some may have multiple) */
> + __u32 Mth; /* Subinstance of Nth instance */
> + __u64 __reserved[3]; /* Reserved params; all must be 0 */
Oh, so your commit message uses __reserved[6] and here it's
__reserved[3] and your error check above also only validates
__reserved[3]. Should probably make this consistent. :)
> +};
> +
> +struct fsinfo_u128 {
> +#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN)
> + __u64 hi;
> + __u64 lo;
> +#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN)
> + __u64 lo;
> + __u64 hi;
> +#endif
> +};
Hm, I know why you do this custom fsinfo_u128 thingy but for userspace
that is going to be annoying to operate with, e.g. comparing the
size/space of two filesystems etc.
> +
> +/*
> + * Information struct for fsinfo(fsinfo_attr_statfs).
> + * - This gives extended filesystem information.
> + */
> +struct fsinfo_statfs {
> + struct fsinfo_u128 f_blocks; /* Total number of blocks in fs */
> + struct fsinfo_u128 f_bfree; /* Total number of free blocks */
> + struct fsinfo_u128 f_bavail; /* Number of free blocks available to ordinary user */
> + struct fsinfo_u128 f_files; /* Total number of file nodes in fs */
> + struct fsinfo_u128 f_ffree; /* Number of free file nodes */
> + struct fsinfo_u128 f_favail; /* Number of file nodes available to ordinary user */
> + __u64 f_bsize; /* Optimal block size */
> + __u64 f_frsize; /* Fragment size */
> + __u64 mnt_attrs; /* Mount attributes (MOUNT_ATTR_*) */
> +};
> +
> +/*
> + * Information struct for fsinfo(fsinfo_attr_ids).
> + *
> + * List of basic identifiers as is normally found in statfs().
> + */
> +struct fsinfo_ids {
> + char f_fs_name[15 + 1]; /* Filesystem name */
You should probably make this a macro so userspace can use it in fs-name
length checks too.
> + __u64 f_fsid; /* Short 64-bit Filesystem ID (as statfs) */
> + __u64 f_sb_id; /* Internal superblock ID for sbnotify()/mntnotify() */
> + __u32 f_fstype; /* Filesystem type from linux/magic.h [uncond] */
> + __u32 f_dev_major; /* As st_dev_* from struct statx [uncond] */
> + __u32 f_dev_minor;
> + __u32 __reserved[1];
> +};
> +
> +/*
> + * Information struct for fsinfo(fsinfo_attr_limits).
> + *
> + * List of supported filesystem limits.
> + */
> +struct fsinfo_limits {
> + struct fsinfo_u128 max_file_size; /* Maximum file size */
> + struct fsinfo_u128 max_ino; /* Maximum inode number */
> + __u64 max_uid; /* Maximum UID supported */
> + __u64 max_gid; /* Maximum GID supported */
> + __u64 max_projid; /* Maximum project ID supported */
> + __u64 max_hard_links; /* Maximum number of hard links on a file */
> + __u64 max_xattr_body_len; /* Maximum xattr content length */
> + __u32 max_xattr_name_len; /* Maximum xattr name length */
> + __u32 max_filename_len; /* Maximum filename length */
> + __u32 max_symlink_len; /* Maximum symlink content length */
> + __u32 max_dev_major; /* Maximum device major representable */
> + __u32 max_dev_minor; /* Maximum device minor representable */
> + __u32 __reserved[1];
> +};
> +
> +/*
> + * Information struct for fsinfo(fsinfo_attr_supports).
> + *
> + * What's supported in various masks, such as statx() attribute and mask bits
> + * and IOC flags.
> + */
> +struct fsinfo_supports {
> + __u64 stx_attributes; /* What statx::stx_attributes are supported */
> + __u32 stx_mask; /* What statx::stx_mask bits are supported */
> + __u32 ioc_flags; /* What FS_IOC_* flags are supported */
> + __u32 win_file_attrs; /* What DOS/Windows FILE_* attributes are supported */
> + __u32 __reserved[1];
> +};
> +
> +/*
> + * Information struct for fsinfo(fsinfo_attr_capabilities).
> + *
> + * Bitmask indicating filesystem capabilities where renderable as single bits.
> + */
> +enum fsinfo_capability {
> + FSINFO_CAP_IS_KERNEL_FS = 0, /* fs is kernel-special filesystem */
> + FSINFO_CAP_IS_BLOCK_FS = 1, /* fs is block-based filesystem */
> + FSINFO_CAP_IS_FLASH_FS = 2, /* fs is flash filesystem */
> + FSINFO_CAP_IS_NETWORK_FS = 3, /* fs is network filesystem */
> + FSINFO_CAP_IS_AUTOMOUNTER_FS = 4, /* fs is automounter special filesystem */
> + FSINFO_CAP_IS_MEMORY_FS = 5, /* fs is memory-based filesystem */
> + FSINFO_CAP_AUTOMOUNTS = 6, /* fs supports automounts */
> + FSINFO_CAP_ADV_LOCKS = 7, /* fs supports advisory file locking */
> + FSINFO_CAP_MAND_LOCKS = 8, /* fs supports mandatory file locking */
> + FSINFO_CAP_LEASES = 9, /* fs supports file leases */
> + FSINFO_CAP_UIDS = 10, /* fs supports numeric uids */
> + FSINFO_CAP_GIDS = 11, /* fs supports numeric gids */
> + FSINFO_CAP_PROJIDS = 12, /* fs supports numeric project ids */
> + FSINFO_CAP_STRING_USER_IDS = 13, /* fs supports string user identifiers */
> + FSINFO_CAP_GUID_USER_IDS = 14, /* fs supports GUID user identifiers */
> + FSINFO_CAP_WINDOWS_ATTRS = 15, /* fs has windows attributes */
> + FSINFO_CAP_USER_QUOTAS = 16, /* fs has per-user quotas */
> + FSINFO_CAP_GROUP_QUOTAS = 17, /* fs has per-group quotas */
> + FSINFO_CAP_PROJECT_QUOTAS = 18, /* fs has per-project quotas */
> + FSINFO_CAP_XATTRS = 19, /* fs has xattrs */
> + FSINFO_CAP_JOURNAL = 20, /* fs has a journal */
> + FSINFO_CAP_DATA_IS_JOURNALLED = 21, /* fs is using data journalling */
> + FSINFO_CAP_O_SYNC = 22, /* fs supports O_SYNC */
> + FSINFO_CAP_O_DIRECT = 23, /* fs supports O_DIRECT */
> + FSINFO_CAP_VOLUME_ID = 24, /* fs has a volume ID */
> + FSINFO_CAP_VOLUME_UUID = 25, /* fs has a volume UUID */
> + FSINFO_CAP_VOLUME_NAME = 26, /* fs has a volume name */
> + FSINFO_CAP_VOLUME_FSID = 27, /* fs has a volume FSID */
> + FSINFO_CAP_IVER_ALL_CHANGE = 28, /* i_version represents data + meta changes */
> + FSINFO_CAP_IVER_DATA_CHANGE = 29, /* i_version represents data changes only */
> + FSINFO_CAP_IVER_MONO_INCR = 30, /* i_version incremented monotonically */
> + FSINFO_CAP_DIRECTORIES = 31, /* fs supports (sub)directories */
> + FSINFO_CAP_SYMLINKS = 32, /* fs supports symlinks */
> + FSINFO_CAP_HARD_LINKS = 33, /* fs supports hard links */
> + FSINFO_CAP_HARD_LINKS_1DIR = 34, /* fs supports hard links in same dir only */
> + FSINFO_CAP_DEVICE_FILES = 35, /* fs supports bdev, cdev */
> + FSINFO_CAP_UNIX_SPECIALS = 36, /* fs supports pipe, fifo, socket */
> + FSINFO_CAP_RESOURCE_FORKS = 37, /* fs supports resource forks/streams */
> + FSINFO_CAP_NAME_CASE_INDEP = 38, /* Filename case independence is mandatory */
> + FSINFO_CAP_NAME_NON_UTF8 = 39, /* fs has non-utf8 names */
> + FSINFO_CAP_NAME_HAS_CODEPAGE = 40, /* fs has a filename codepage */
> + FSINFO_CAP_SPARSE = 41, /* fs supports sparse files */
> + FSINFO_CAP_NOT_PERSISTENT = 42, /* fs is not persistent */
> + FSINFO_CAP_NO_UNIX_MODE = 43, /* fs does not support unix mode bits */
> + FSINFO_CAP_HAS_ATIME = 44, /* fs supports access time */
> + FSINFO_CAP_HAS_BTIME = 45, /* fs supports birth/creation time */
> + FSINFO_CAP_HAS_CTIME = 46, /* fs supports change time */
> + FSINFO_CAP_HAS_MTIME = 47, /* fs supports modification time */
> + FSINFO_CAP__NR
Hm, again, maybe better to use FSINFO_CAP_MAX?
> +};
> +
> +struct fsinfo_capabilities {
> + __u8 capabilities[(FSINFO_CAP__NR + 7) / 8];
> +};
> +
> +struct fsinfo_timestamp_one {
> + __s64 minimum; /* Minimum timestamp value in seconds */
> + __u64 maximum; /* Maximum timestamp value in seconds */
> + __u16 gran_mantissa; /* Granularity(secs) = mant * 10^exp */
> + __s8 gran_exponent;
> + __u8 reserved[5];
> +};
> +
> +/*
> + * Information struct for fsinfo(fsinfo_attr_timestamp_info).
> + */
> +struct fsinfo_timestamp_info {
> + struct fsinfo_timestamp_one atime; /* Access time */
> + struct fsinfo_timestamp_one mtime; /* Modification time */
> + struct fsinfo_timestamp_one ctime; /* Change time */
> + struct fsinfo_timestamp_one btime; /* Birth/creation time */
> +};
> +
> +/*
> + * Information struct for fsinfo(fsinfo_attr_volume_uuid).
> + */
> +struct fsinfo_volume_uuid {
> + __u8 uuid[16];
> +};
> +
> +/*
> + * Information struct for fsinfo(fsinfo_attr_fsinfo).
> + *
> + * This gives information about fsinfo() itself.
> + */
> +struct fsinfo_fsinfo {
> + __u32 max_attr; /* Number of supported attributes (fsinfo_attr__nr) */
> + __u32 max_cap; /* Number of supported capabilities (fsinfo_cap__nr) */
> +};
> +
> +#endif /* _UAPI_LINUX_FSINFO_H */
> diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
> index 4d9ae5ea6caf..93927072396c 100644
> --- a/kernel/sys_ni.c
> +++ b/kernel/sys_ni.c
> @@ -51,6 +51,7 @@ COND_SYSCALL_COMPAT(io_pgetevents);
> COND_SYSCALL(io_uring_setup);
> COND_SYSCALL(io_uring_enter);
> COND_SYSCALL(io_uring_register);
> +COND_SYSCALL(fsinfo);
>
> /* fs/xattr.c */
>
> diff --git a/samples/vfs/Makefile b/samples/vfs/Makefile
> index a3e4ffd4c773..d3cc8e9a4fd8 100644
> --- a/samples/vfs/Makefile
> +++ b/samples/vfs/Makefile
> @@ -1,10 +1,14 @@
> # List of programs to build
> hostprogs-y := \
> + test-fsinfo \
> test-fsmount \
> test-statx
>
> # Tell kbuild to always build the programs
> always := $(hostprogs-y)
>
> +HOSTCFLAGS_test-fsinfo.o += -I$(objtree)/usr/include
> +HOSTLDLIBS_test-fsinfo += -lm
> +
> HOSTCFLAGS_test-fsmount.o += -I$(objtree)/usr/include
> HOSTCFLAGS_test-statx.o += -I$(objtree)/usr/include
> diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
> new file mode 100644
> index 000000000000..8cce1986df7e
> --- /dev/null
> +++ b/samples/vfs/test-fsinfo.c
> @@ -0,0 +1,551 @@
> +/* Test the fsinfo() system call
> + *
> + * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells ([email protected])
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public Licence
> + * as published by the Free Software Foundation; either version
> + * 2 of the Licence, or (at your option) any later version.
> + */
> +
> +#define _GNU_SOURCE
> +#define _ATFILE_SOURCE
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdint.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <ctype.h>
> +#include <errno.h>
> +#include <time.h>
> +#include <math.h>
> +#include <fcntl.h>
> +#include <sys/syscall.h>
> +#include <linux/fsinfo.h>
> +#include <linux/socket.h>
> +#include <sys/stat.h>
> +#include <arpa/inet.h>
> +
> +#ifndef __NR_fsinfo
> +#define __NR_fsinfo -1
> +#endif
> +
> +static bool debug = 0;
> +
> +static __attribute__((unused))
> +ssize_t fsinfo(int dfd, const char *filename, struct fsinfo_params *params,
> + void *buffer, size_t buf_size)
> +{
> + return syscall(__NR_fsinfo, dfd, filename, params, buffer, buf_size);
> +}
> +
> +struct fsinfo_attr_info {
> + unsigned char type;
> + unsigned char flags;
> + unsigned short size;
> +};
> +
> +#define __FSINFO_STRUCT 0
> +#define __FSINFO_STRING 1
> +#define __FSINFO_OVER 2
> +#define __FSINFO_STRUCT_ARRAY 3
> +#define __FSINFO_0 0
> +#define __FSINFO_N 0x0001
> +#define __FSINFO_NM 0x0002
> +
> +#define _Z(T, F, S) { .type = __FSINFO_##T, .flags = __FSINFO_##F, .size = S }
> +#define FSINFO_STRING(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, 0, 0)
> +#define FSINFO_STRUCT(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, 0, sizeof(struct fsinfo_##Y))
> +#define FSINFO_STRING_N(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, N, 0)
> +#define FSINFO_STRUCT_N(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, N, sizeof(struct fsinfo_##Y))
> +#define FSINFO_STRING_NM(X,Y) [FSINFO_ATTR_##X] = _Z(STRING, NM, 0)
> +#define FSINFO_STRUCT_NM(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT, NM, sizeof(struct fsinfo_##Y))
> +#define FSINFO_OVERLARGE(X,Y) [FSINFO_ATTR_##X] = _Z(OVER, 0, 0)
> +#define FSINFO_STRUCT_ARRAY(X,Y) [FSINFO_ATTR_##X] = _Z(STRUCT_ARRAY, 0, sizeof(struct fsinfo_##Y))
> +
> +static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
> + FSINFO_STRUCT (STATFS, statfs),
> + FSINFO_STRUCT (FSINFO, fsinfo),
> + FSINFO_STRUCT (IDS, ids),
> + FSINFO_STRUCT (LIMITS, limits),
> + FSINFO_STRUCT (CAPABILITIES, capabilities),
> + FSINFO_STRUCT (SUPPORTS, supports),
> + FSINFO_STRUCT (TIMESTAMP_INFO, timestamp_info),
> + FSINFO_STRING (VOLUME_ID, volume_id),
> + FSINFO_STRUCT (VOLUME_UUID, volume_uuid),
> + FSINFO_STRING (VOLUME_NAME, volume_name),
> + FSINFO_STRING (NAME_ENCODING, name_encoding),
> + FSINFO_STRING (NAME_CODEPAGE, name_codepage),
> +};
> +
> +#define FSINFO_NAME(X,Y) [FSINFO_ATTR_##X] = #Y
> +static const char *fsinfo_attr_names[FSINFO_ATTR__NR] = {
> + FSINFO_NAME (STATFS, statfs),
> + FSINFO_NAME (FSINFO, fsinfo),
> + FSINFO_NAME (IDS, ids),
> + FSINFO_NAME (LIMITS, limits),
> + FSINFO_NAME (CAPABILITIES, capabilities),
> + FSINFO_NAME (SUPPORTS, supports),
> + FSINFO_NAME (TIMESTAMP_INFO, timestamp_info),
> + FSINFO_NAME (VOLUME_ID, volume_id),
> + FSINFO_NAME (VOLUME_UUID, volume_uuid),
> + FSINFO_NAME (VOLUME_NAME, volume_name),
> + FSINFO_NAME (NAME_ENCODING, name_encoding),
> + FSINFO_NAME (NAME_CODEPAGE, name_codepage),
> +};
> +
> +union reply {
> + char buffer[4096];
> + struct fsinfo_statfs statfs;
> + struct fsinfo_fsinfo fsinfo;
> + struct fsinfo_ids ids;
> + struct fsinfo_limits limits;
> + struct fsinfo_supports supports;
> + struct fsinfo_capabilities caps;
> + struct fsinfo_timestamp_info timestamps;
> + struct fsinfo_volume_uuid uuid;
> +};
> +
> +static void dump_hex(unsigned int *data, int from, int to)
> +{
> + unsigned offset, print_offset = 1, col = 0;
> +
> + from /= 4;
> + to = (to + 3) / 4;
> +
> + for (offset = from; offset < to; offset++) {
> + if (print_offset) {
> + printf("%04x: ", offset * 8);
> + print_offset = 0;
> + }
> + printf("%08x", data[offset]);
> + col++;
> + if ((col & 3) == 0) {
> + printf("\n");
> + print_offset = 1;
> + } else {
> + printf(" ");
> + }
> + }
> +
> + if (!print_offset)
> + printf("\n");
> +}
> +
> +static void dump_attr_STATFS(union reply *r, int size)
> +{
> + struct fsinfo_statfs *f = &r->statfs;
> +
> + printf("\n");
> + printf("\tblocks: n=%llu fr=%llu av=%llu\n",
> + (unsigned long long)f->f_blocks.lo,
> + (unsigned long long)f->f_bfree.lo,
> + (unsigned long long)f->f_bavail.lo);
> +
> + printf("\tfiles : n=%llu fr=%llu av=%llu\n",
> + (unsigned long long)f->f_files.lo,
> + (unsigned long long)f->f_ffree.lo,
> + (unsigned long long)f->f_favail.lo);
> + printf("\tbsize : %llu\n", f->f_bsize);
> + printf("\tfrsize: %llu\n", f->f_frsize);
> + printf("\tmntfl : %llx\n", (unsigned long long)f->mnt_attrs);
> +}
> +
> +static void dump_attr_FSINFO(union reply *r, int size)
> +{
> + struct fsinfo_fsinfo *f = &r->fsinfo;
> +
> + printf("max_attr=%u max_cap=%u\n", f->max_attr, f->max_cap);
> +}
> +
> +static void dump_attr_IDS(union reply *r, int size)
> +{
> + struct fsinfo_ids *f = &r->ids;
> +
> + printf("\n");
> + printf("\tdev : %02x:%02x\n", f->f_dev_major, f->f_dev_minor);
> + printf("\tfs : type=%x name=%s\n", f->f_fstype, f->f_fs_name);
> + printf("\tfsid : %llx\n", (unsigned long long)f->f_fsid);
> +}
> +
> +static void dump_attr_LIMITS(union reply *r, int size)
> +{
> + struct fsinfo_limits *f = &r->limits;
> +
> + printf("\n");
> + printf("\tmax file size: %llx%016llx\n",
> + (unsigned long long)f->max_file_size.hi,
> + (unsigned long long)f->max_file_size.lo);
> + printf("\tmax ino: %llx%016llx\n",
> + (unsigned long long)f->max_ino.hi,
> + (unsigned long long)f->max_ino.lo);
> + printf("\tmax ids : u=%llx g=%llx p=%llx\n",
> + (unsigned long long)f->max_uid,
> + (unsigned long long)f->max_gid,
> + (unsigned long long)f->max_projid);
> + printf("\tmax dev : maj=%x min=%x\n",
> + f->max_dev_major, f->max_dev_minor);
> + printf("\tmax links : %llx\n",
> + (unsigned long long)f->max_hard_links);
> + printf("\tmax xattr : n=%x b=%llx\n",
> + f->max_xattr_name_len,
> + (unsigned long long)f->max_xattr_body_len);
> + printf("\tmax len : file=%x sym=%x\n",
> + f->max_filename_len, f->max_symlink_len);
> +}
> +
> +static void dump_attr_SUPPORTS(union reply *r, int size)
> +{
> + struct fsinfo_supports *f = &r->supports;
> +
> + printf("\n");
> + printf("\tstx_attr=%llx\n", (unsigned long long)f->stx_attributes);
> + printf("\tstx_mask=%x\n", f->stx_mask);
> + printf("\tioc_flags=%x\n", f->ioc_flags);
> + printf("\twin_fattrs=%x\n", f->win_file_attrs);
> +}
> +
> +#define FSINFO_CAP_NAME(C) [FSINFO_CAP_##C] = #C
> +static const char *fsinfo_cap_names[FSINFO_CAP__NR] = {
> + FSINFO_CAP_NAME(IS_KERNEL_FS),
> + FSINFO_CAP_NAME(IS_BLOCK_FS),
> + FSINFO_CAP_NAME(IS_FLASH_FS),
> + FSINFO_CAP_NAME(IS_NETWORK_FS),
> + FSINFO_CAP_NAME(IS_AUTOMOUNTER_FS),
> + FSINFO_CAP_NAME(IS_MEMORY_FS),
> + FSINFO_CAP_NAME(AUTOMOUNTS),
> + FSINFO_CAP_NAME(ADV_LOCKS),
> + FSINFO_CAP_NAME(MAND_LOCKS),
> + FSINFO_CAP_NAME(LEASES),
> + FSINFO_CAP_NAME(UIDS),
> + FSINFO_CAP_NAME(GIDS),
> + FSINFO_CAP_NAME(PROJIDS),
> + FSINFO_CAP_NAME(STRING_USER_IDS),
> + FSINFO_CAP_NAME(GUID_USER_IDS),
> + FSINFO_CAP_NAME(WINDOWS_ATTRS),
> + FSINFO_CAP_NAME(USER_QUOTAS),
> + FSINFO_CAP_NAME(GROUP_QUOTAS),
> + FSINFO_CAP_NAME(PROJECT_QUOTAS),
> + FSINFO_CAP_NAME(XATTRS),
> + FSINFO_CAP_NAME(JOURNAL),
> + FSINFO_CAP_NAME(DATA_IS_JOURNALLED),
> + FSINFO_CAP_NAME(O_SYNC),
> + FSINFO_CAP_NAME(O_DIRECT),
> + FSINFO_CAP_NAME(VOLUME_ID),
> + FSINFO_CAP_NAME(VOLUME_UUID),
> + FSINFO_CAP_NAME(VOLUME_NAME),
> + FSINFO_CAP_NAME(VOLUME_FSID),
> + FSINFO_CAP_NAME(IVER_ALL_CHANGE),
> + FSINFO_CAP_NAME(IVER_DATA_CHANGE),
> + FSINFO_CAP_NAME(IVER_MONO_INCR),
> + FSINFO_CAP_NAME(DIRECTORIES),
> + FSINFO_CAP_NAME(SYMLINKS),
> + FSINFO_CAP_NAME(HARD_LINKS),
> + FSINFO_CAP_NAME(HARD_LINKS_1DIR),
> + FSINFO_CAP_NAME(DEVICE_FILES),
> + FSINFO_CAP_NAME(UNIX_SPECIALS),
> + FSINFO_CAP_NAME(RESOURCE_FORKS),
> + FSINFO_CAP_NAME(NAME_CASE_INDEP),
> + FSINFO_CAP_NAME(NAME_NON_UTF8),
> + FSINFO_CAP_NAME(NAME_HAS_CODEPAGE),
> + FSINFO_CAP_NAME(SPARSE),
> + FSINFO_CAP_NAME(NOT_PERSISTENT),
> + FSINFO_CAP_NAME(NO_UNIX_MODE),
> + FSINFO_CAP_NAME(HAS_ATIME),
> + FSINFO_CAP_NAME(HAS_BTIME),
> + FSINFO_CAP_NAME(HAS_CTIME),
> + FSINFO_CAP_NAME(HAS_MTIME),
> +};
> +
> +static void dump_attr_CAPABILITIES(union reply *r, int size)
> +{
> + struct fsinfo_capabilities *f = &r->caps;
> + int i;
> +
> + for (i = 0; i < sizeof(f->capabilities); i++)
> + printf("%02x", f->capabilities[i]);
> + printf("\n");
> + for (i = 0; i < FSINFO_CAP__NR; i++)
> + if (f->capabilities[i / 8] & (1 << (i % 8)))
> + printf("\t- %s\n", fsinfo_cap_names[i]);
> +}
> +
> +static void print_time(struct fsinfo_timestamp_one *t, char stamp)
> +{
> + printf("\t%ctime : gran=%gs range=%llx-%llx\n",
> + stamp,
> + t->gran_mantissa * pow(10., t->gran_exponent),
> + (long long)t->minimum,
> + (long long)t->maximum);
> +}
> +
> +static void dump_attr_TIMESTAMP_INFO(union reply *r, int size)
> +{
> + struct fsinfo_timestamp_info *f = &r->timestamps;
> +
> + printf("\n");
> + print_time(&f->atime, 'a');
> + print_time(&f->mtime, 'm');
> + print_time(&f->ctime, 'c');
> + print_time(&f->btime, 'b');
> +}
> +
> +static void dump_attr_VOLUME_UUID(union reply *r, int size)
> +{
> + struct fsinfo_volume_uuid *f = &r->uuid;
> +
> + printf("%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x"
> + "-%02x%02x%02x%02x%02x%02x\n",
> + f->uuid[ 0], f->uuid[ 1],
> + f->uuid[ 2], f->uuid[ 3],
> + f->uuid[ 4], f->uuid[ 5],
> + f->uuid[ 6], f->uuid[ 7],
> + f->uuid[ 8], f->uuid[ 9],
> + f->uuid[10], f->uuid[11],
> + f->uuid[12], f->uuid[13],
> + f->uuid[14], f->uuid[15]);
> +}
> +
> +/*
> + *
> + */
> +typedef void (*dumper_t)(union reply *r, int size);
> +
> +#define FSINFO_DUMPER(N) [FSINFO_ATTR_##N] = dump_attr_##N
> +static const dumper_t fsinfo_attr_dumper[FSINFO_ATTR__NR] = {
> + FSINFO_DUMPER(STATFS),
> + FSINFO_DUMPER(FSINFO),
> + FSINFO_DUMPER(IDS),
> + FSINFO_DUMPER(LIMITS),
> + FSINFO_DUMPER(SUPPORTS),
> + FSINFO_DUMPER(CAPABILITIES),
> + FSINFO_DUMPER(TIMESTAMP_INFO),
> + FSINFO_DUMPER(VOLUME_UUID),
> +};
> +
> +static void dump_fsinfo(enum fsinfo_attribute attr,
> + struct fsinfo_attr_info about,
> + union reply *r, int size)
> +{
> + dumper_t dumper = fsinfo_attr_dumper[attr];
> + unsigned int len;
> +
> + if (!dumper) {
> + printf("<no dumper>\n");
> + return;
> + }
> +
> + len = about.size;
> + if (about.type == __FSINFO_STRUCT && size < len) {
> + printf("<short data %u/%u>\n", size, len);
> + return;
> + }
> +
> + dumper(r, size);
> +}
> +
> +/*
> + * Try one subinstance of an attribute.
> + */
> +static int try_one(const char *file, struct fsinfo_params *params, bool raw)
> +{
> + struct fsinfo_attr_info about;
> + union reply *r;
> + size_t buf_size = 4096;
> + char *p;
> + int ret;
> +
> + for (;;) {
> + r = malloc(buf_size);
> + if (!r) {
> + perror("malloc");
> + exit(1);
> + }
> + memset(r->buffer, 0xbd, buf_size);
> +
> + errno = 0;
> + ret = fsinfo(AT_FDCWD, file, params, r->buffer, buf_size);
> + if (params->request >= FSINFO_ATTR__NR) {
> + if (ret == -1 && errno == EOPNOTSUPP)
> + exit(0);
> + fprintf(stderr, "Unexpected error for too-large command %u: %m\n",
> + params->request);
> + exit(1);
> + }
> + if (ret == -1)
> + break;
> +
> + if (ret <= buf_size)
> + break;
> + buf_size = (ret + 4096 - 1) & ~(4096 - 1);
> + }
> +
> + if (debug)
> + printf("fsinfo(%s,%s,%u,%u) = %d: %m\n",
> + file, fsinfo_attr_names[params->request],
> + params->Nth, params->Mth, ret);
> +
> + about = fsinfo_buffer_info[params->request];
> + if (ret == -1) {
> + if (errno == ENODATA) {
> + if (!(about.flags & (__FSINFO_N | __FSINFO_NM)) &&
> + params->Nth == 0 && params->Mth == 0) {
> + fprintf(stderr,
> + "Unexpected ENODATA (%u[%u][%u])\n",
> + params->request, params->Nth, params->Mth);
> + exit(1);
> + }
> + return (params->Mth == 0) ? 2 : 1;
> + }
> + if (errno == EOPNOTSUPP) {
> + if (params->Nth > 0 || params->Mth > 0) {
> + fprintf(stderr,
> + "Should return -ENODATA (%u[%u][%u])\n",
> + params->request, params->Nth, params->Mth);
> + exit(1);
> + }
> + //printf("\e[33m%s\e[m: <not supported>\n",
> + // fsinfo_attr_names[attr]);
> + return 2;
> + }
> + perror(file);
> + exit(1);
> + }
> +
> + if (raw) {
> + if (ret > 4096)
> + ret = 4096;
> + dump_hex((unsigned int *)r->buffer, 0, ret);
> + return 0;
> + }
> +
> + switch (about.flags & (__FSINFO_N | __FSINFO_NM)) {
> + case 0:
> + printf("\e[33m%s\e[m: ",
> + fsinfo_attr_names[params->request]);
> + break;
> + case __FSINFO_N:
> + printf("\e[33m%s[%u]\e[m: ",
> + fsinfo_attr_names[params->request],
> + params->Nth);
> + break;
> + case __FSINFO_NM:
> + printf("\e[33m%s[%u][%u]\e[m: ",
> + fsinfo_attr_names[params->request],
> + params->Nth, params->Mth);
> + break;
> + }
> +
> + switch (about.type) {
> + case __FSINFO_STRUCT:
> + dump_fsinfo(params->request, about, r, ret);
> + return 0;
> +
> + case __FSINFO_STRING:
> + if (ret >= 4096) {
> + ret = 4096;
> + r->buffer[4092] = '.';
> + r->buffer[4093] = '.';
> + r->buffer[4094] = '.';
> + r->buffer[4095] = 0;
> + } else {
> + r->buffer[ret] = 0;
> + }
> + for (p = r->buffer; *p; p++) {
> + if (!isprint(*p)) {
> + printf("<non-printable>\n");
> + continue;
> + }
> + }
> + printf("%s\n", r->buffer);
> + return 0;
> +
> + case __FSINFO_OVER:
> + return 0;
> +
> + case __FSINFO_STRUCT_ARRAY:
> + dump_fsinfo(params->request, about, r, ret);
> + return 0;
> +
> + default:
> + fprintf(stderr, "Fishy about %u %u,%u,%u\n",
> + params->request, about.type, about.flags, about.size);
> + exit(1);
> + }
> +}
> +
> +/*
> + *
> + */
> +int main(int argc, char **argv)
> +{
> + struct fsinfo_params params = {
> + .at_flags = AT_SYMLINK_NOFOLLOW,
> + };
> + unsigned int attr;
> + int raw = 0, opt, Nth, Mth;
> +
> + while ((opt = getopt(argc, argv, "adlr"))) {
> + switch (opt) {
> + case 'a':
> + params.at_flags |= AT_NO_AUTOMOUNT;
> + continue;
> + case 'd':
> + debug = true;
> + continue;
> + case 'l':
> + params.at_flags &= ~AT_SYMLINK_NOFOLLOW;
> + continue;
> + case 'r':
> + raw = 1;
> + continue;
> + }
> + break;
> + }
> +
> + argc -= optind;
> + argv += optind;
> +
> + if (argc != 1) {
> + printf("Format: test-fsinfo [-alr] <file>\n");
> + exit(2);
> + }
> +
> + for (attr = 0; attr <= FSINFO_ATTR__NR; attr++) {
> + Nth = 0;
> + do {
> + Mth = 0;
> + do {
> + params.request = attr;
> + params.Nth = Nth;
> + params.Mth = Mth;
> +
> + switch (try_one(argv[0], ¶ms, raw)) {
> + case 0:
> + continue;
> + case 1:
> + goto done_M;
> + case 2:
> + goto done_N;
> + }
> + } while (++Mth < 100);
> +
> + done_M:
> + if (Mth >= 100) {
> + fprintf(stderr, "Fishy: Mth == %u\n", Mth);
> + break;
> + }
> +
> + } while (++Nth < 100);
> +
> + done_N:
> + if (Nth >= 100) {
> + fprintf(stderr, "Fishy: Nth == %u\n", Nth);
> + break;
> + }
> + }
> +
> + return 0;
> +}
>
On Mon, Jun 24, 2019 at 03:09:14PM +0100, David Howells wrote:
> Allow fsinfo() to be used to query the filesystem attached to an fs_context
> once a superblock has been created or if it comes from fspick().
>
> The caller must specify AT_FSINFO_FROM_FSOPEN in the parameters and must
Yeah, I like that better than how it was before.
> supply the fd from fsopen() as dfd and must set filename to NULL.
>
> This is done with something like:
>
> fd = fsopen("ext4", 0);
> ...
> struct fsinfo_params params = {
> .at_flags = AT_FSINFO_FROM_FSOPEN;
> ...
> };
> fsinfo(fd, NULL, ¶ms, ...);
>
> Signed-off-by: David Howells <[email protected]>
> ---
>
> fs/fsinfo.c | 46 +++++++++++++++++++++++++++++++++++++++++++-
> fs/statfs.c | 2 +-
> include/uapi/linux/fcntl.h | 2 ++
> 3 files changed, 48 insertions(+), 2 deletions(-)
>
> diff --git a/fs/fsinfo.c b/fs/fsinfo.c
> index 49b46f96dda3..c24701f994d1 100644
> --- a/fs/fsinfo.c
> +++ b/fs/fsinfo.c
> @@ -8,6 +8,7 @@
> #include <linux/security.h>
> #include <linux/uaccess.h>
> #include <linux/fsinfo.h>
> +#include <linux/fs_context.h>
> #include <uapi/linux/mount.h>
> #include "internal.h"
>
> @@ -340,6 +341,42 @@ static int vfs_fsinfo_fd(unsigned int fd, struct fsinfo_kparams *params)
> return ret;
> }
>
> +/*
> + * Allow access to an fs_context object as created by fsopen() or fspick().
> + */
> +static int vfs_fsinfo_fscontext(int fd, struct fsinfo_kparams *params)
> +{
> + struct fs_context *fc;
> + struct fd f = fdget(fd);
> + int ret;
> +
> + if (!f.file)
> + return -EBADF;
> +
> + ret = -EINVAL;
> + if (f.file->f_op == &fscontext_fops)
Don't you mean != ?
if (f.file->f_op != &fscontext_fops)
> + goto out_f;
> + ret = -EOPNOTSUPP;
> + if (fc->ops == &legacy_fs_context_ops)
> + goto out_f;
> +
> + ret = mutex_lock_interruptible(&fc->uapi_mutex);
> + if (ret == 0) {
> + ret = -EIO;
Why EIO when there's no root dentry?
> + if (fc->root) {
> + struct path path = { .dentry = fc->root };
> +
> + ret = vfs_fsinfo(&path, params);
> + }
> +
> + mutex_unlock(&fc->uapi_mutex);
> + }
> +
> +out_f:
> + fdput(f);
> + return ret;
> +}
> +
> /*
> * Return buffer information by requestable attribute.
> *
> @@ -445,6 +482,9 @@ SYSCALL_DEFINE5(fsinfo,
> params.request = user_params.request;
> params.Nth = user_params.Nth;
> params.Mth = user_params.Mth;
> +
[1]:
> + if ((params.at_flags & AT_FSINFO_FROM_FSOPEN) && filename)
> + return -EINVAL;
> } else {
> params.request = FSINFO_ATTR_STATFS;
> }
> @@ -453,6 +493,8 @@ SYSCALL_DEFINE5(fsinfo,
> user_buf_size = 0;
> user_buffer = NULL;
> }
> + if ((params.at_flags & AT_FSINFO_FROM_FSOPEN) && filename)
> + return -EINVAL;
Sorry, why is this checked twice (see [1])? Or is the diff just
misleading here?
>
> /* Allocate an appropriately-sized buffer. We will truncate the
> * contents when we write the contents back to userspace.
> @@ -500,7 +542,9 @@ SYSCALL_DEFINE5(fsinfo,
> if (!params.buffer)
> goto error_scratch;
>
> - if (filename)
> + if (params.at_flags & AT_FSINFO_FROM_FSOPEN)
> + ret = vfs_fsinfo_fscontext(dfd, ¶ms);
> + else if (filename)
> ret = vfs_fsinfo_path(dfd, filename, ¶ms);
> else
> ret = vfs_fsinfo_fd(dfd, ¶ms);
> diff --git a/fs/statfs.c b/fs/statfs.c
> index eea7af6f2f22..b9b63d9f4f24 100644
> --- a/fs/statfs.c
> +++ b/fs/statfs.c
> @@ -86,7 +86,7 @@ int vfs_statfs(const struct path *path, struct kstatfs *buf)
> int error;
>
> error = statfs_by_dentry(path->dentry, buf);
> - if (!error)
> + if (!error && path->mnt)
> buf->f_flags = calculate_f_flags(path->mnt);
> return error;
> }
> diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
> index 1d338357df8a..6a2402a8fa30 100644
> --- a/include/uapi/linux/fcntl.h
> +++ b/include/uapi/linux/fcntl.h
> @@ -91,6 +91,8 @@
> #define AT_STATX_FORCE_SYNC 0x2000 /* - Force the attributes to be sync'd with the server */
> #define AT_STATX_DONT_SYNC 0x4000 /* - Don't sync attributes with the server */
>
> +#define AT_FSINFO_FROM_FSOPEN 0x2000 /* Examine the fs_context attached to dfd by fsopen() */
> +
> #define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */
>
>
>
On Mon, Jun 24, 2019 at 03:09:05PM +0100, David Howells wrote:
> Add the fsinfo syscall to the other arches.
>
> Signed-off-by: David Howells <[email protected]>
> ---
>
> arch/alpha/kernel/syscalls/syscall.tbl | 1 +
> arch/arm/tools/syscall.tbl | 1 +
> arch/arm64/include/asm/unistd.h | 2 +-
I think you missed
arch/arm64/include/asm/unistd32.h
?
> arch/ia64/kernel/syscalls/syscall.tbl | 1 +
> arch/m68k/kernel/syscalls/syscall.tbl | 1 +
> arch/microblaze/kernel/syscalls/syscall.tbl | 1 +
> arch/mips/kernel/syscalls/syscall_n32.tbl | 1 +
> arch/mips/kernel/syscalls/syscall_n64.tbl | 1 +
> arch/mips/kernel/syscalls/syscall_o32.tbl | 1 +
> arch/parisc/kernel/syscalls/syscall.tbl | 1 +
> arch/powerpc/kernel/syscalls/syscall.tbl | 1 +
> arch/s390/kernel/syscalls/syscall.tbl | 1 +
> arch/sh/kernel/syscalls/syscall.tbl | 1 +
> arch/sparc/kernel/syscalls/syscall.tbl | 1 +
> arch/xtensa/kernel/syscalls/syscall.tbl | 1 +
> 15 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl
> index 9e7704e44f6d..624d01c3c8eb 100644
> --- a/arch/alpha/kernel/syscalls/syscall.tbl
> +++ b/arch/alpha/kernel/syscalls/syscall.tbl
> @@ -473,3 +473,4 @@
> 541 common fsconfig sys_fsconfig
> 542 common fsmount sys_fsmount
> 543 common fspick sys_fspick
> +544 common fsinfo sys_fsinfo
> diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl
> index aaf479a9e92d..ad608b49808c 100644
> --- a/arch/arm/tools/syscall.tbl
> +++ b/arch/arm/tools/syscall.tbl
> @@ -447,3 +447,4 @@
> 431 common fsconfig sys_fsconfig
> 432 common fsmount sys_fsmount
> 433 common fspick sys_fspick
> +434 common fsinfo sys_fsinfo
> diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
> index 70e6882853c0..e8f7d95a1481 100644
> --- a/arch/arm64/include/asm/unistd.h
> +++ b/arch/arm64/include/asm/unistd.h
> @@ -44,7 +44,7 @@
> #define __ARM_NR_compat_set_tls (__ARM_NR_COMPAT_BASE + 5)
> #define __ARM_NR_COMPAT_END (__ARM_NR_COMPAT_BASE + 0x800)
>
> -#define __NR_compat_syscalls 434
> +#define __NR_compat_syscalls 435
> #endif
>
> #define __ARCH_WANT_SYS_CLONE
> diff --git a/arch/ia64/kernel/syscalls/syscall.tbl b/arch/ia64/kernel/syscalls/syscall.tbl
> index e01df3f2f80d..68314763ad16 100644
> --- a/arch/ia64/kernel/syscalls/syscall.tbl
> +++ b/arch/ia64/kernel/syscalls/syscall.tbl
> @@ -354,3 +354,4 @@
> 431 common fsconfig sys_fsconfig
> 432 common fsmount sys_fsmount
> 433 common fspick sys_fspick
> +434 common fsinfo sys_fsinfo
> diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl
> index 7e3d0734b2f3..ee73a7534b1b 100644
> --- a/arch/m68k/kernel/syscalls/syscall.tbl
> +++ b/arch/m68k/kernel/syscalls/syscall.tbl
> @@ -433,3 +433,4 @@
> 431 common fsconfig sys_fsconfig
> 432 common fsmount sys_fsmount
> 433 common fspick sys_fspick
> +434 common fsinfo sys_fsinfo
> diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl
> index 26339e417695..7bc067f4b713 100644
> --- a/arch/microblaze/kernel/syscalls/syscall.tbl
> +++ b/arch/microblaze/kernel/syscalls/syscall.tbl
> @@ -439,3 +439,4 @@
> 431 common fsconfig sys_fsconfig
> 432 common fsmount sys_fsmount
> 433 common fspick sys_fspick
> +434 common fsinfo sys_fsinfo
> diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl
> index 0e2dd68ade57..29b76bd67cc0 100644
> --- a/arch/mips/kernel/syscalls/syscall_n32.tbl
> +++ b/arch/mips/kernel/syscalls/syscall_n32.tbl
> @@ -372,3 +372,4 @@
> 431 n32 fsconfig sys_fsconfig
> 432 n32 fsmount sys_fsmount
> 433 n32 fspick sys_fspick
> +434 n32 fsinfo sys_fsinfo
> diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl
> index 5eebfa0d155c..349fb30bb8b5 100644
> --- a/arch/mips/kernel/syscalls/syscall_n64.tbl
> +++ b/arch/mips/kernel/syscalls/syscall_n64.tbl
> @@ -348,3 +348,4 @@
> 431 n64 fsconfig sys_fsconfig
> 432 n64 fsmount sys_fsmount
> 433 n64 fspick sys_fspick
> +434 n64 fsinfo sys_fsinfo
> diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl
> index 3cc1374e02d0..71057426b503 100644
> --- a/arch/mips/kernel/syscalls/syscall_o32.tbl
> +++ b/arch/mips/kernel/syscalls/syscall_o32.tbl
> @@ -421,3 +421,4 @@
> 431 o32 fsconfig sys_fsconfig
> 432 o32 fsmount sys_fsmount
> 433 o32 fspick sys_fspick
> +434 o32 fsinfo sys_fsinfo
> diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl
> index c9e377d59232..32cff48a1ebd 100644
> --- a/arch/parisc/kernel/syscalls/syscall.tbl
> +++ b/arch/parisc/kernel/syscalls/syscall.tbl
> @@ -430,3 +430,4 @@
> 431 common fsconfig sys_fsconfig
> 432 common fsmount sys_fsmount
> 433 common fspick sys_fspick
> +434 common fsinfo sys_fsinfo
> diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl
> index 103655d84b4b..e5755eb6fb84 100644
> --- a/arch/powerpc/kernel/syscalls/syscall.tbl
> +++ b/arch/powerpc/kernel/syscalls/syscall.tbl
> @@ -515,3 +515,4 @@
> 431 common fsconfig sys_fsconfig
> 432 common fsmount sys_fsmount
> 433 common fspick sys_fspick
> +434 common fsinfo sys_fsinfo
> diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl
> index e822b2964a83..bcd54116e107 100644
> --- a/arch/s390/kernel/syscalls/syscall.tbl
> +++ b/arch/s390/kernel/syscalls/syscall.tbl
> @@ -436,3 +436,4 @@
> 431 common fsconfig sys_fsconfig sys_fsconfig
> 432 common fsmount sys_fsmount sys_fsmount
> 433 common fspick sys_fspick sys_fspick
> +434 common fsinfo sys_fsinfo sys_fsinfo
> diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl
> index 016a727d4357..0320a5c63cbd 100644
> --- a/arch/sh/kernel/syscalls/syscall.tbl
> +++ b/arch/sh/kernel/syscalls/syscall.tbl
> @@ -436,3 +436,4 @@
> 431 common fsconfig sys_fsconfig
> 432 common fsmount sys_fsmount
> 433 common fspick sys_fspick
> +434 common fsinfo sys_fsinfo
> diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl
> index e047480b1605..f81b1f9402bd 100644
> --- a/arch/sparc/kernel/syscalls/syscall.tbl
> +++ b/arch/sparc/kernel/syscalls/syscall.tbl
> @@ -479,3 +479,4 @@
> 431 common fsconfig sys_fsconfig
> 432 common fsmount sys_fsmount
> 433 common fspick sys_fspick
> +434 common fsinfo sys_fsinfo
> diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl
> index 5fa0ee1c8e00..729795148850 100644
> --- a/arch/xtensa/kernel/syscalls/syscall.tbl
> +++ b/arch/xtensa/kernel/syscalls/syscall.tbl
> @@ -404,3 +404,4 @@
> 431 common fsconfig sys_fsconfig
> 432 common fsmount sys_fsmount
> 433 common fspick sys_fspick
> +434 common fsinfo sys_fsinfo
>
On Mon, Jun 24, 2019 at 03:09:21PM +0100, David Howells wrote:
> Provide fsinfo() attributes that can be used to query a filesystem
> parameter description. To do this, fsinfo() can be called on an
Can you give a usecase for this?
Wouldn't it be more helpful if fsinfo() when used to query a filesystem
without a created or attached superblock could be used to query options
the underlying fs supports so that users know what they can fsconfig()?
(Maybe that's not possible because you'd already need to have a
superblock created or attached in this case.)
> fs_context that doesn't yet have a superblock created and attached.
>
> It can be obtained by doing, for example:
>
> fd = fsopen("ext4", 0);
>
> struct fsinfo_param_name name;
> struct fsinfo_params params = {
> .at_flags = AT_FSINFO_FROM_FSOPEN,
> .request = fsinfo_attr_param_name,
> .Nth = 3,
> };
> fsinfo(fd, NULL, ¶ms, &name, sizeof(name));
>
> to query the 4th parameter name in the name to parameter ID mapping table.
>
> Signed-off-by: David Howells <[email protected]>
> ---
>
> fs/fsinfo.c | 101 +++++++++++++++++++++++++++++++
> include/uapi/linux/fsinfo.h | 58 ++++++++++++++++++
> samples/vfs/Makefile | 2 +
> samples/vfs/test-fs-query.c | 138 +++++++++++++++++++++++++++++++++++++++++++
> samples/vfs/test-fsinfo.c | 14 ++++
> 5 files changed, 311 insertions(+), 2 deletions(-)
> create mode 100644 samples/vfs/test-fs-query.c
>
> diff --git a/fs/fsinfo.c b/fs/fsinfo.c
> index c24701f994d1..9e2a25510b88 100644
> --- a/fs/fsinfo.c
> +++ b/fs/fsinfo.c
> @@ -9,6 +9,7 @@
> #include <linux/uaccess.h>
> #include <linux/fsinfo.h>
> #include <linux/fs_context.h>
> +#include <linux/fs_parser.h>
> #include <uapi/linux/mount.h>
> #include "internal.h"
>
> @@ -223,12 +224,87 @@ static int fsinfo_generic_name_encoding(struct path *path, char *buf)
> return sizeof(encoding) - 1;
> }
>
> +static int fsinfo_generic_param_description(struct file_system_type *f,
> + struct fsinfo_kparams *params)
> +{
> + const struct fs_parameter_description *desc = f->parameters;
> + const struct fs_parameter_spec *s;
> + const struct fs_parameter_enum *e;
nit: *s can probably be moved inside the first if() and *e into the second
if().
> + struct fsinfo_param_description *p = params->buffer;
> +
> + if (desc && desc->specs) {
> + for (s = desc->specs; s->name; s++) {}
> + p->nr_params = s - desc->specs;
> + if (desc->enums) {
> + for (e = desc->enums; e->name[0]; e++) {}
> + p->nr_enum_names = e - desc->enums;
> + }
> + }
> +
> + return sizeof(*p);
> +}
> +
> +static int fsinfo_generic_param_specification(struct file_system_type *f,
> + struct fsinfo_kparams *params)
> +{
> + const struct fs_parameter_description *desc = f->parameters;
> + const struct fs_parameter_spec *s;
> + struct fsinfo_param_specification *p = params->buffer;
> + unsigned int nth = params->Nth;
> +
> + if (!desc || !desc->specs)
> + return -ENODATA;
> +
> + for (s = desc->specs; s->name; s++) {
> + if (nth == 0)
> + goto found;
> + nth--;
> + }
> +
> + return -ENODATA;
> +
> +found:
> + p->type = s->type;
> + p->flags = s->flags;
> + p->opt = s->opt;
> + strlcpy(p->name, s->name, sizeof(p->name));
> + return sizeof(*p);
> +}
> +
> +static int fsinfo_generic_param_enum(struct file_system_type *f,
> + struct fsinfo_kparams *params)
> +{
> + const struct fs_parameter_description *desc = f->parameters;
> + const struct fs_parameter_enum *e;
> + struct fsinfo_param_enum *p = params->buffer;
> + unsigned int nth = params->Nth;
> +
> + if (!desc || !desc->enums)
> + return -ENODATA;
> +
> + for (e = desc->enums; e->name; e++) {
> + if (nth == 0)
> + goto found;
> + nth--;
> + }
> +
> + return -ENODATA;
> +
> +found:
> + p->opt = e->opt;
> + strlcpy(p->name, e->name, sizeof(p->name));
> + return sizeof(*p);
> +}
> +
> /*
> * Implement some queries generically from stuff in the superblock.
> */
> int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
> {
> + struct file_system_type *fs = path->dentry->d_sb->s_type;
> +
> #define _gen(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(path, params->buffer)
> +#define _genf(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(fs, params)
>
> switch (params->request) {
> case _gen(STATFS, statfs);
> @@ -240,6 +316,9 @@ int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
> case _gen(VOLUME_UUID, volume_uuid);
> case _gen(VOLUME_ID, volume_id);
> case _gen(NAME_ENCODING, name_encoding);
> + case _genf(PARAM_DESCRIPTION, param_description);
> + case _genf(PARAM_SPECIFICATION, param_specification);
> + case _genf(PARAM_ENUM, param_enum);
> default:
> return -EOPNOTSUPP;
> }
> @@ -342,10 +421,11 @@ static int vfs_fsinfo_fd(unsigned int fd, struct fsinfo_kparams *params)
> }
>
> /*
> - * Allow access to an fs_context object as created by fsopen() or fspick().
> + * Allow an fs_context object as created by fsopen() or fspick() to be queried.
> */
> static int vfs_fsinfo_fscontext(int fd, struct fsinfo_kparams *params)
> {
> + struct file_system_type *fs;
> struct fs_context *fc;
> struct fd f = fdget(fd);
> int ret;
> @@ -354,12 +434,26 @@ static int vfs_fsinfo_fscontext(int fd, struct fsinfo_kparams *params)
> return -EBADF;
>
> ret = -EINVAL;
> - if (f.file->f_op == &fscontext_fops)
> + if (f.file->f_op != &fscontext_fops)
Here you're fixing the error I pointed out in the other patch (I believe
[03/<max>].). Probably best to fix it in the original patch. ;)
> goto out_f;
> + fc = f.file->private_data;
> + fs = fc->fs_type;
> +
> ret = -EOPNOTSUPP;
> if (fc->ops == &legacy_fs_context_ops)
> goto out_f;
>
> + /* Filesystem parameter query is static information and doesn't need a
> + * lock to read it, nor even a dentry or superblock.
> + */
> + switch (params->request) {
> + case _genf(PARAM_DESCRIPTION, param_description);
> + case _genf(PARAM_SPECIFICATION, param_specification);
> + case _genf(PARAM_ENUM, param_enum);
> + default:
> + break;
> + }
> +
> ret = mutex_lock_interruptible(&fc->uapi_mutex);
> if (ret == 0) {
> ret = -EIO;
> @@ -432,6 +526,9 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
> FSINFO_STRING (VOLUME_NAME, -),
> FSINFO_STRING (NAME_ENCODING, -),
> FSINFO_STRING (NAME_CODEPAGE, -),
> + FSINFO_STRUCT (PARAM_DESCRIPTION, param_description),
> + FSINFO_STRUCT_N (PARAM_SPECIFICATION, param_specification),
> + FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
> };
>
> /**
> diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
> index a7a7c731d992..9d929d2f7eee 100644
> --- a/include/uapi/linux/fsinfo.h
> +++ b/include/uapi/linux/fsinfo.h
> @@ -27,6 +27,9 @@ enum fsinfo_attribute {
> FSINFO_ATTR_VOLUME_NAME = 9, /* Volume name (string) */
> FSINFO_ATTR_NAME_ENCODING = 10, /* Filename encoding (string) */
> FSINFO_ATTR_NAME_CODEPAGE = 11, /* Filename codepage (string) */
> + FSINFO_ATTR_PARAM_DESCRIPTION = 12, /* General fs parameter description */
> + FSINFO_ATTR_PARAM_SPECIFICATION = 13, /* Nth parameter specification */
> + FSINFO_ATTR_PARAM_ENUM = 14, /* Nth enum-to-val */
> FSINFO_ATTR__NR
> };
>
> @@ -216,4 +219,59 @@ struct fsinfo_fsinfo {
> __u32 max_cap; /* Number of supported capabilities (fsinfo_cap__nr) */
> };
>
> +/*
> + * Information struct for fsinfo(fsinfo_attr_param_description).
> + *
> + * Query the parameter set for a filesystem.
> + */
> +struct fsinfo_param_description {
> + __u32 nr_params; /* Number of individual parameters */
> + __u32 nr_enum_names; /* Number of enum names */
> +};
> +
> +/*
> + * Information struct for fsinfo(fsinfo_attr_param_specification).
> + *
> + * Query the specification of the Nth filesystem parameter.
> + */
> +struct fsinfo_param_specification {
> + __u32 type; /* enum fsinfo_param_specification_type */
> + __u32 flags; /* Qualifiers */
> + __u32 opt; /* Corresponding params have same ID here */
> + char name[240];
> +};
> +
> +enum fsinfo_param_specification_type {
> + FSINFO_PARAM_SPEC_NOT_DEFINED = 0,
> + FSINFO_PARAM_SPEC_IS_FLAG = 1,
> + FSINFO_PARAM_SPEC_IS_BOOL = 2,
> + FSINFO_PARAM_SPEC_IS_U32 = 3,
> + FSINFO_PARAM_SPEC_IS_U32_OCTAL = 4,
> + FSINFO_PARAM_SPEC_IS_U32_HEX = 5,
> + FSINFO_PARAM_SPEC_IS_S32 = 6,
> + FSINFO_PARAM_SPEC_IS_U64 = 7,
> + FSINFO_PARAM_SPEC_IS_ENUM = 8,
> + FSINFO_PARAM_SPEC_IS_STRING = 9,
> + FSINFO_PARAM_SPEC_IS_BLOB = 10,
> + FSINFO_PARAM_SPEC_IS_BLOCKDEV = 11,
> + FSINFO_PARAM_SPEC_IS_PATH = 12,
> + FSINFO_PARAM_SPEC_IS_FD = 13,
> + NR__FSINFO_PARAM_SPEC
> +};
> +
> +#define FSINFO_PARAM_SPEC_VALUE_IS_OPTIONAL 0X00000001
> +#define FSINFO_PARAM_SPEC_PREFIX_NO_IS_NEG 0X00000002
> +#define FSINFO_PARAM_SPEC_EMPTY_STRING_IS_NEG 0X00000004
> +#define FSINFO_PARAM_SPEC_DEPRECATED 0X00000008
> +
> +/*
> + * Information struct for fsinfo(fsinfo_attr_param_enum).
> + *
> + * Query the Nth filesystem enum parameter value name.
> + */
> +struct fsinfo_param_enum {
> + __u32 opt; /* ->opt of the relevant parameter specification */
> + char name[252]; /* Name of the enum value */
> +};
> +
> #endif /* _UAPI_LINUX_FSINFO_H */
> diff --git a/samples/vfs/Makefile b/samples/vfs/Makefile
> index d3cc8e9a4fd8..3c542d3b9479 100644
> --- a/samples/vfs/Makefile
> +++ b/samples/vfs/Makefile
> @@ -1,6 +1,7 @@
> # List of programs to build
> hostprogs-y := \
> test-fsinfo \
> + test-fs-query \
> test-fsmount \
> test-statx
>
> @@ -10,5 +11,6 @@ always := $(hostprogs-y)
> HOSTCFLAGS_test-fsinfo.o += -I$(objtree)/usr/include
> HOSTLDLIBS_test-fsinfo += -lm
>
> +HOSTCFLAGS_test-fs-query.o += -I$(objtree)/usr/include
> HOSTCFLAGS_test-fsmount.o += -I$(objtree)/usr/include
> HOSTCFLAGS_test-statx.o += -I$(objtree)/usr/include
> diff --git a/samples/vfs/test-fs-query.c b/samples/vfs/test-fs-query.c
> new file mode 100644
> index 000000000000..7572411ddb7e
> --- /dev/null
> +++ b/samples/vfs/test-fs-query.c
> @@ -0,0 +1,138 @@
> +/* Test using the fsinfo() system call to query mount parameters.
> + *
> + * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells ([email protected])
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public Licence
> + * as published by the Free Software Foundation; either version
> + * 2 of the Licence, or (at your option) any later version.
> + */
> +
> +#define _GNU_SOURCE
> +#define _ATFILE_SOURCE
> +#include <stdbool.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <stdint.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <ctype.h>
> +#include <errno.h>
> +#include <time.h>
> +#include <math.h>
> +#include <sys/syscall.h>
> +#include <linux/fsinfo.h>
> +#include <linux/fcntl.h>
> +#include <sys/stat.h>
> +
> +#ifndef __NR_fsopen
> +#define __NR_fsopen -1
> +#endif
> +#ifndef __NR_fsinfo
> +#define __NR_fsinfo -1
> +#endif
> +
> +static int fsopen(const char *fs_name, unsigned int flags)
> +{
> + return syscall(__NR_fsopen, fs_name, flags);
> +}
> +
> +static ssize_t fsinfo(int dfd, const char *filename, struct fsinfo_params *params,
> + void *buffer, size_t buf_size)
> +{
> + return syscall(__NR_fsinfo, dfd, filename, params, buffer, buf_size);
> +}
> +
> +static const char *param_types[NR__FSINFO_PARAM_SPEC] = {
> + [FSINFO_PARAM_SPEC_NOT_DEFINED] = "?undef",
> + [FSINFO_PARAM_SPEC_IS_FLAG] = "flag",
> + [FSINFO_PARAM_SPEC_IS_BOOL] = "bool",
> + [FSINFO_PARAM_SPEC_IS_U32] = "u32",
> + [FSINFO_PARAM_SPEC_IS_U32_OCTAL] = "octal",
> + [FSINFO_PARAM_SPEC_IS_U32_HEX] = "hex",
> + [FSINFO_PARAM_SPEC_IS_S32] = "s32",
> + [FSINFO_PARAM_SPEC_IS_U64] = "u64",
> + [FSINFO_PARAM_SPEC_IS_ENUM] = "enum",
> + [FSINFO_PARAM_SPEC_IS_STRING] = "string",
> + [FSINFO_PARAM_SPEC_IS_BLOB] = "binary",
> + [FSINFO_PARAM_SPEC_IS_BLOCKDEV] = "blockdev",
> + [FSINFO_PARAM_SPEC_IS_PATH] = "path",
> + [FSINFO_PARAM_SPEC_IS_FD] = "fd",
> +};
> +
> +/*
> + *
> + */
> +int main(int argc, char **argv)
> +{
> + struct fsinfo_param_description desc;
> + struct fsinfo_param_specification spec;
> + struct fsinfo_param_enum enum_name;
> +
> + struct fsinfo_params params = {
> + .at_flags = AT_FSINFO_FROM_FSOPEN,
> + };
> + int fd;
> +
> + if (argc != 2) {
> + printf("Format: test-fs-query <fs_name>\n");
> + exit(2);
> + }
> +
> + fd = fsopen(argv[1], 0);
> + if (fd == -1) {
> + perror(argv[1]);
> + exit(1);
> + }
> +
> + params.request = FSINFO_ATTR_PARAM_DESCRIPTION;
> + if (fsinfo(fd, NULL, ¶ms, &desc, sizeof(desc)) == -1) {
> + perror("fsinfo/desc");
> + exit(1);
> + }
> +
> + printf("Filesystem %s has %u parameters\n", argv[1], desc.nr_params);
> +
> + params.request = FSINFO_ATTR_PARAM_SPECIFICATION;
> + for (params.Nth = 0; params.Nth < desc.nr_params; params.Nth++) {
> + char type[32];
> +
> + if (fsinfo(fd, NULL, ¶ms, &spec, sizeof(spec)) == -1) {
> + if (errno == ENODATA)
> + break;
> + perror("fsinfo/spec");
> + exit(1);
> + }
> +
> + if (spec.type < NR__FSINFO_PARAM_SPEC)
> + strcpy(type, param_types[spec.type]);
> + else
> + sprintf(type, "?%u", spec.type);
> +
> + printf("- PARAM[%3u] %-20s %3u %s%s%s%s%s\n",
> + params.Nth,
> + spec.name,
> + spec.opt,
> + type,
> + spec.flags & FSINFO_PARAM_SPEC_VALUE_IS_OPTIONAL ? ",opt" : "",
> + spec.flags & FSINFO_PARAM_SPEC_PREFIX_NO_IS_NEG ? ",neg-no" : "",
> + spec.flags & FSINFO_PARAM_SPEC_EMPTY_STRING_IS_NEG ? ",neg-empty" : "",
> + spec.flags & FSINFO_PARAM_SPEC_DEPRECATED ? ",dep" : "");
> + }
> +
> + printf("Filesystem has %u enumeration values\n", desc.nr_enum_names);
> +
> + params.request = FSINFO_ATTR_PARAM_ENUM;
> + for (params.Nth = 0; params.Nth < desc.nr_enum_names; params.Nth++) {
> + if (fsinfo(fd, NULL, ¶ms, &enum_name, sizeof(enum_name)) == -1) {
> + if (errno == ENODATA)
> + break;
> + perror("fsinfo/enum");
> + exit(1);
> + }
> + printf("- ENUM[%3u] %3u: %s\n",
> + params.Nth, enum_name.opt, enum_name.name);
> + }
> + return 0;
> +}
> diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
> index 8cce1986df7e..3c6ea3a5c157 100644
> --- a/samples/vfs/test-fsinfo.c
> +++ b/samples/vfs/test-fsinfo.c
> @@ -78,6 +78,9 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
> FSINFO_STRING (VOLUME_NAME, volume_name),
> FSINFO_STRING (NAME_ENCODING, name_encoding),
> FSINFO_STRING (NAME_CODEPAGE, name_codepage),
> + FSINFO_STRUCT (PARAM_DESCRIPTION, param_description),
> + FSINFO_STRUCT_N (PARAM_SPECIFICATION, param_specification),
> + FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
> };
>
> #define FSINFO_NAME(X,Y) [FSINFO_ATTR_##X] = #Y
> @@ -94,6 +97,9 @@ static const char *fsinfo_attr_names[FSINFO_ATTR__NR] = {
> FSINFO_NAME (VOLUME_NAME, volume_name),
> FSINFO_NAME (NAME_ENCODING, name_encoding),
> FSINFO_NAME (NAME_CODEPAGE, name_codepage),
> + FSINFO_NAME (PARAM_DESCRIPTION, param_description),
> + FSINFO_NAME (PARAM_SPECIFICATION, param_specification),
> + FSINFO_NAME (PARAM_ENUM, param_enum),
> };
>
> union reply {
> @@ -514,6 +520,14 @@ int main(int argc, char **argv)
> }
>
> for (attr = 0; attr <= FSINFO_ATTR__NR; attr++) {
> + switch (attr) {
> + case FSINFO_ATTR_PARAM_DESCRIPTION:
> + case FSINFO_ATTR_PARAM_SPECIFICATION:
> + case FSINFO_ATTR_PARAM_ENUM:
> + /* See test-fs-query.c instead */
> + continue;
> + }
> +
> Nth = 0;
> do {
> Mth = 0;
>
On Mon, Jun 24, 2019 at 03:09:33PM +0100, David Howells wrote:
> Implement parameter value retrieval with fsinfo() - akin to parsing
> /proc/mounts.
>
> This allows all the parameters to be retrieved in one go with:
>
> struct fsinfo_params params = {
> .request = FSINFO_ATTR_PARAMETER,
> };
>
> Each parameter comes as a pair of blobs with a length tacked on the front
> rather than using separators, since any printable character that could be
> used as a separator can be found in some value somewhere (including comma).
> In fact, cifs allows the separator to be set using the "sep=" option in
> parameter parsing.
>
> The length on the front of each blob is 1-3 bytes long. Each byte has a
> flag in bit 7 that's set if there are more bytes and clear on the last
> byte; bits 0-6 should be shifted and OR'd into the length count. The bytes
> are most-significant first.
>
> For example, 0x83 0xf5 0x06 is the length (0x03<<14 | 0x75<<7 | 0x06).
Ok, but that is such a royal pain for userspace. Shouldn't we export a
uapi helper that they can use to parse out the length or even iterate
the string or something?
>
> As mentioned, each parameter comes as a pair of blobs in key, value order.
> The value has length zero if not present. So, for example:
>
> \x08compress\x04zlib
>
> from btrfs would be equivalent to "compress=zlib" and:
>
> \x02ro\x00\x06noexec\x00
>
> would be equivalent to "ro,noexec".
>
> The test-fsinfo sample program is modified to dump the parameters.
>
> Signed-off-by: David Howells <[email protected]>
> ---
>
> fs/fsinfo.c | 122 +++++++++++++++++++++++++++++++++++++++++++
> include/linux/fsinfo.h | 4 +
> include/uapi/linux/fsinfo.h | 1
> samples/vfs/test-fsinfo.c | 38 +++++++++++++
> 4 files changed, 165 insertions(+)
>
> diff --git a/fs/fsinfo.c b/fs/fsinfo.c
> index 9e2a25510b88..3b35cedab0df 100644
> --- a/fs/fsinfo.c
> +++ b/fs/fsinfo.c
> @@ -296,6 +296,32 @@ static int fsinfo_generic_param_enum(struct file_system_type *f,
> return sizeof(*p);
> }
>
> +void fsinfo_note_sb_params(struct fsinfo_kparams *params, unsigned int s_flags)
> +{
> + if (s_flags & SB_DIRSYNC)
> + fsinfo_note_param(params, "dirsync", NULL);
> + if (s_flags & SB_LAZYTIME)
> + fsinfo_note_param(params, "lazytime", NULL);
> + if (s_flags & SB_MANDLOCK)
> + fsinfo_note_param(params, "mand", NULL);
> + if (s_flags & SB_POSIXACL)
> + fsinfo_note_param(params, "posixacl", NULL);
> + if (s_flags & SB_RDONLY)
> + fsinfo_note_param(params, "ro", NULL);
> + else
> + fsinfo_note_param(params, "rw", NULL);
> + if (s_flags & SB_SYNCHRONOUS)
> + fsinfo_note_param(params, "sync", NULL);
> +}
> +EXPORT_SYMBOL(fsinfo_note_sb_params);
> +
> +static int fsinfo_generic_parameters(struct path *path,
> + struct fsinfo_kparams *params)
> +{
> + fsinfo_note_sb_params(params, READ_ONCE(path->dentry->d_sb->s_flags));
> + return params->usage;
> +}
> +
> /*
> * Implement some queries generically from stuff in the superblock.
> */
> @@ -304,6 +330,7 @@ int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
> struct file_system_type *fs = path->dentry->d_sb->s_type;
>
> #define _gen(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(path, params->buffer)
> +#define _genp(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(path, params)
> #define _genf(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(fs, params)
>
> switch (params->request) {
> @@ -319,6 +346,7 @@ int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
> case _genf(PARAM_DESCRIPTION, param_description);
> case _genf(PARAM_SPECIFICATION, param_specification);
> case _genf(PARAM_ENUM, param_enum);
> + case _genp(PARAMETERS, parameters);
> default:
> return -EOPNOTSUPP;
> }
> @@ -358,8 +386,16 @@ static int vfs_fsinfo(struct path *path, struct fsinfo_kparams *params)
> return fsinfo(path, params);
>
> while (!signal_pending(current)) {
> + if (params->request == FSINFO_ATTR_PARAMETERS) {
> + if (down_read_killable(&dentry->d_sb->s_umount) < 0)
> + return -ERESTARTSYS;
> + }
> +
> params->usage = 0;
> ret = fsinfo(path, params);
> + if (params->request == FSINFO_ATTR_PARAMETERS)
> + up_read(&dentry->d_sb->s_umount);
> +
> if (ret <= (int)params->buf_size)
> return ret; /* Error or it fitted */
> kvfree(params->buffer);
> @@ -529,6 +565,7 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
> FSINFO_STRUCT (PARAM_DESCRIPTION, param_description),
> FSINFO_STRUCT_N (PARAM_SPECIFICATION, param_specification),
> FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
> + FSINFO_OPAQUE (PARAMETERS, -),
> };
>
> /**
> @@ -676,3 +713,88 @@ SYSCALL_DEFINE5(fsinfo,
> error:
> return ret;
> }
> +
> +/*
> + * Store a parameter into the user's parameter buffer. The key is prefixed by
> + * a single byte length (1-127) and the value by one (0-0x7f) or two bytes
> + * (0x80-0x3fff) or three bytes (0x4000-0x1fffff).
> + *
> + * Note that we must always make the size determination, even if the buffer is
> + * already full, so that we can tell the caller how much buffer we actually
> + * need.
> + */
> +static void __fsinfo_note_param(struct fsinfo_kparams *params, const char *key,
> + const char *val, unsigned int vlen)
> +{
> + char *p;
> + unsigned int usage;
> + int klen, total, vmeta;
> + u8 x;
> +
> + klen = strlen(key);
> + BUG_ON(klen < 1 || klen > 127);
> + BUG_ON(vlen > (1 << 21) - 1);
> + BUG_ON(vlen > 0 && !val);
> +
> + vmeta = (vlen <= 127) ? 1 : (vlen <= 127 * 127) ? 2 : 3;
> +
> + total = 1 + klen + vmeta + vlen;
> +
> + usage = params->usage;
> + params->usage = usage + total;
> + if (!params->buffer || params->usage > params->buf_size)
> + return;
> +
> + p = params->buffer + usage;
> + *p++ = klen;
> + p = memcpy(p, key, klen);
> + p += klen;
> +
> + /* The more significant groups of 7 bits in the size are included in
> + * most->least order with 0x80 OR'd in. The least significant 7 bits
> + * are last with the top bit clear.
> + */
> + x = vlen >> 14;
> + if (x & 0x7f)
> + *p++ = 0x80 | x;
> +
> + x = vlen >> 7;
> + if (x & 0x7f)
> + *p++ = 0x80 | x;
> +
> + *p++ = vlen & 0x7f;
> + memcpy(p, val, vlen);
> +}
> +
> +/**
> + * fsinfo_note_param - Store a parameter for FSINFO_ATTR_PARAMETERS
> + * @params: The parameter buffer
> + * @key: The parameter's key
> + * @val: The parameter's value (or NULL)
> + */
> +void fsinfo_note_param(struct fsinfo_kparams *params, const char *key,
> + const char *val)
> +{
> + __fsinfo_note_param(params, key, val, val ? strlen(val) : 0);
> +}
> +EXPORT_SYMBOL(fsinfo_note_param);
> +
> +/**
> + * fsinfo_note_paramf - Store a formatted parameter for FSINFO_ATTR_PARAMETERS
> + * @params: The parameter buffer
> + * @key: The parameter's key
> + * @val_fmt: Format string for the parameter's value
> + */
> +void fsinfo_note_paramf(struct fsinfo_kparams *params, const char *key,
> + const char *val_fmt, ...)
> +{
> + va_list va;
> + int n;
> +
> + va_start(va, val_fmt);
> + n = vsnprintf(params->scratch_buffer, 4096, val_fmt, va);
> + va_end(va);
> +
> + __fsinfo_note_param(params, key, params->scratch_buffer, n);
> +}
> +EXPORT_SYMBOL(fsinfo_note_paramf);
> diff --git a/include/linux/fsinfo.h b/include/linux/fsinfo.h
> index e17e4f0bae18..731931afbf1c 100644
> --- a/include/linux/fsinfo.h
> +++ b/include/linux/fsinfo.h
> @@ -29,6 +29,10 @@ struct fsinfo_kparams {
> };
>
> extern int generic_fsinfo(struct path *, struct fsinfo_kparams *);
> +extern void fsinfo_note_sb_params(struct fsinfo_kparams *, unsigned int);
> +extern void fsinfo_note_param(struct fsinfo_kparams *, const char *, const char *);
> +extern void fsinfo_note_paramf(struct fsinfo_kparams *, const char *, const char *, ...)
> + __printf(3, 4);
>
> static inline void fsinfo_set_cap(struct fsinfo_capabilities *c,
> enum fsinfo_capability cap)
> diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
> index 9d929d2f7eee..475cd1c97b12 100644
> --- a/include/uapi/linux/fsinfo.h
> +++ b/include/uapi/linux/fsinfo.h
> @@ -30,6 +30,7 @@ enum fsinfo_attribute {
> FSINFO_ATTR_PARAM_DESCRIPTION = 12, /* General fs parameter description */
> FSINFO_ATTR_PARAM_SPECIFICATION = 13, /* Nth parameter specification */
> FSINFO_ATTR_PARAM_ENUM = 14, /* Nth enum-to-val */
> + FSINFO_ATTR_PARAMETERS = 15, /* Mount parameters (large string) */
> FSINFO_ATTR__NR
> };
>
> diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
> index 3c6ea3a5c157..8cf5b02e333a 100644
> --- a/samples/vfs/test-fsinfo.c
> +++ b/samples/vfs/test-fsinfo.c
> @@ -81,6 +81,7 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
> FSINFO_STRUCT (PARAM_DESCRIPTION, param_description),
> FSINFO_STRUCT_N (PARAM_SPECIFICATION, param_specification),
> FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
> + FSINFO_OVERLARGE (PARAMETERS, -),
> };
>
> #define FSINFO_NAME(X,Y) [FSINFO_ATTR_##X] = #Y
> @@ -100,6 +101,7 @@ static const char *fsinfo_attr_names[FSINFO_ATTR__NR] = {
> FSINFO_NAME (PARAM_DESCRIPTION, param_description),
> FSINFO_NAME (PARAM_SPECIFICATION, param_specification),
> FSINFO_NAME (PARAM_ENUM, param_enum),
> + FSINFO_NAME (PARAMETERS, parameters),
> };
>
> union reply {
> @@ -352,6 +354,34 @@ static void dump_fsinfo(enum fsinfo_attribute attr,
> dumper(r, size);
> }
>
> +static void dump_params(struct fsinfo_attr_info about, union reply *r, int size)
> +{
> + int len;
> + char *p = r->buffer, *e = p + size;
> + bool is_key = true;
> +
> + while (p < e) {
> + len = 0;
> + while (p[0] & 0x80) {
> + len <<= 7;
> + len |= *p++ & 0x7f;
> + }
> +
> + len <<= 7;
> + len |= *p++;
> + if (len > e - p)
> + break;
> + if (is_key || len)
> + printf("%s%*.*s", is_key ? "[PARM] " : "= ", len, len, p);
> + if (is_key)
> + putchar(' ');
> + else
> + putchar('\n');
> + p += len;
> + is_key = !is_key;
> + }
> +}
> +
> /*
> * Try one subinstance of an attribute.
> */
> @@ -427,6 +457,12 @@ static int try_one(const char *file, struct fsinfo_params *params, bool raw)
> return 0;
> }
>
> + switch (params->request) {
> + case FSINFO_ATTR_PARAMETERS:
> + if (ret == 0)
> + return 0;
> + }
> +
> switch (about.flags & (__FSINFO_N | __FSINFO_NM)) {
> case 0:
> printf("\e[33m%s\e[m: ",
> @@ -469,6 +505,8 @@ static int try_one(const char *file, struct fsinfo_params *params, bool raw)
> return 0;
>
> case __FSINFO_OVER:
> + if (params->request == FSINFO_ATTR_PARAMETERS)
> + dump_params(about, r, ret);
> return 0;
>
> case __FSINFO_STRUCT_ARRAY:
>
Christian Brauner <[email protected]> wrote:
> > + return sizeof(*p);
>
> Hm, the discrepancy between the function signature returning int and
> the sizeof operator most likely being size_t is bothering me. It
> probably doesn't matter but maybe we can avoid that.
If sizeof(*p) exceeds 4096, the buffer is going to have been overrun by this
point anyway.
The function can't return size_t, though it could return ssize_t. I could
switch it to return long or even store the result in fsinfo_kparams::usage and
return 0.
> > + strlcpy(p->f_fs_name, path->dentry->d_sb->s_type->name,
> > + sizeof(p->f_fs_name));
>
> Truncation is acceptable or impossible I assume?
I'm hoping that file_system_type::name isn't going to exceed 15 chars plus
NUL. If it does, it will be truncated. I don't really want to add an
individual attribute just for the filesystem driver name.
> > +#define _gen(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(path, params->buffer)
>
> I'm really not sure that this helps readability in the switch below... :)
>
> > +
> > + switch (params->request) {
> > + case _gen(STATFS, statfs);
> > + case _gen(IDS, ids);
> > + case _gen(LIMITS, limits);
> > + case _gen(SUPPORTS, supports);
> > + case _gen(CAPABILITIES, capabilities);
> > + case _gen(TIMESTAMP_INFO, timestamp_info);
> > ...
I'm trying to avoid having to spend multiple lines per case and tabulation
makes things easier to read. So
case FSINFO_ATTR_SUPPORTS: return fsinfo_generic_supports(path, params->buffer);
case FSINFO_ATTR_CAPABILITIES: return fsinfo_generic_capabilities(path, params->buffer);
case FSINFO_ATTR_TIMESTAMP_INFO: return fsinfo_generic_timestamp_info(path, params->buffer);
is a bit on the long side per line, whereas:
case FSINFO_ATTR_SUPPORTS:
return fsinfo_generic_supports(path, params->buffer);
case FSINFO_ATTR_CAPABILITIES:
return fsinfo_generic_capabilities(path, params->buffer);
case FSINFO_ATTR_TIMESTAMP_INFO:
return fsinfo_generic_timestamp_info(path, params->buffer);
is less readable by interleaving two of the three columns. (Note that _gen is
a actually third column as I introduce alternatives later).
> > + if (ret <= (int)params->buf_size)
>
> He, and this is where the return value discrepancy hits again. Just
> doesn't look nice tbh. :)
No. That's dealing with signed/unsigned comparison. It might be better if I
change this to:
if (IS_ERR_VALUE(ret))
return ret; /* Error */
if ((unsigned int)ret <= params->buf_size)
return ret; /* It fitted */
In any case, buf_size isn't permitted to be larger than INT_MAX due to a check
later in the loop.
> > + kvfree(params->buffer);
>
> That means callers should always memset fsinfo_kparams or this is an
> invalid free...
vfs_info() isn't a public function. And, in any case, the caller *must*
provide a buffer here.
> > + * Return buffer information by requestable attribute.
> > + *
> > + * STRUCT indicates a fixed-size structure with only one instance.
> > ...
> I honestly have a hard time following the documentation here
How about:
* STRUCT - a fixed-size structure with only one instance.
* STRUCT_N - a sequence of STRUCTs, indexed by Nth
* STRUCT_NM - a sequence of sequences of STRUCTs, indexed by Nth, Mth
* STRING - a string with only one instance.
* STRING_N - a sequence of STRING, indexed by Nth
* STRING_NM - a sequence of sequences of STRING, indexed by Nth, Mth
* OPAQUE - a blob that can be larger than 4K.
* STRUCT_ARRAY - an array of structs that can be larger than 4K
> and that monster table/macro thing below. For example, STRUCT_NM
> corresponds to __FSINFO_NM or what?
STRUCT_NM -> .type = __FSINFO_STRUCT, .flags = __FSINFO_NM, .size = ...
If you think this is bad, you should try looking at the device ID tables used
by the drivers and the attribute tables;-)
I could spell out the flag and type in the macro defs (such as the body of
FSINFO_STRING(X,Y) for instance). It would make it harder to compare macros
as it wouldn't then tabulate, though.
> And is this uapi as you're using this in your samples/test below?
Not exactly. Each attribute is defined as being a certain type in the
documentation in the UAPI header, but this is not coded there. The assumption
being that if you're using a particular attribute, you'll know what the type
of the attribute is and you'll structure your code appropriately.
The reason the sample code has this replicated is that it doesn't really
attempt to interpret the type per se. It has a dumper for an individual
attribute value, but the table tells it whether there should be one of those,
N of those or N of M(0), M(1), M(2), ... of those so that it can report an
error if it doesn't see what it expects.
I could even cheaply provide a meta attribute that dumps the contents of the
table (just the type info, not the names).
> > ...
> > + FSINFO_STRING (NAME_ENCODING, -),
> > + FSINFO_STRING (NAME_CODEPAGE, -),
> > +};
>
> Can I complain again that this is really annoying to parse.
Apparently you can;-) What would you prefer? This:
static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
[FSINFO_STATFS] = {
.type = __FSINFO_STRUCT,
.size = sizeof(struct fsinfo_statfs),
},
[FSINFO_SERVERS] = {
.type = __FSINFO_STRUCT,
.flags = __FSINFO_NM,
.size = sizeof(struct fsinfo_server),
},
...
};
That has 3-5 lines for each 1 in the current code and isn't a great deal more
readable.
> if (copy_to_user()) and if (clear_user()) and not if (clear_user() != 0)
Better "if (copy_to_user() != 0)" since it's not a boolean return value in
either case.
> Nit: There's a bunch of name inconsistency for the arguments between the
> stub and the definition:
>
> SYSCALL_DEFINE5(fsinfo,
> int, dfd, const char __user *, filename,
> struct fsinfo_params __user *, _params,
> void __user *, user_buffer, size_t, user_buf_size)
Yeah. C just doesn't care.
I'll change filename to pathname throughout. That's at least consistent with
various glibc manpages for other vfs syscalls.
_params I can change to params and params as-was to kparams.
But user_buffer and user_buf_size, I'll keep as I've named them such to avoid
confusion with kparams->buffer and kparams->scratch_buffer. However, I
wouldn't want to call them that in the UAPI.
> Do we do SPDX that way? Or isn't this just supposed to be:
> // <spdxy stuff>
Look in, say, include/uapi/linux/stat.h or .../fs.h.
> > + FSINFO_ATTR__NR
>
> Nit/Bikeshed: FSINFO_ATTR_MAX? Seems more intuitive.
No. That would imply a limit that it will never exceed.
> > +struct fsinfo_u128 {
> > +#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN)
> > + __u64 hi;
> > + __u64 lo;
> > +#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN)
> > + __u64 lo;
> > + __u64 hi;
> > +#endif
> > +};
>
> Hm, I know why you do this custom fsinfo_u128 thingy but for userspace
> that is going to be annoying to operate with, e.g. comparing the
> size/space of two filesystems etc.
We don't have a __u128 in the UAPI, and I'm reluctant to use __uint128_t.
Do you have a better suggestion?
> > +struct fsinfo_ids {
> > + char f_fs_name[15 + 1]; /* Filesystem name */
>
> You should probably make this a macro so userspace can use it in fs-name
> length checks too.
The name length, you mean? Well, you can use sizeof...
> > + FSINFO_CAP__NR
>
> Hm, again, maybe better to use FSINFO_CAP_MAX?
It's not a limit.
David
On Mon, Jun 24, 2019 at 03:09:58PM +0100, David Howells wrote:
> Allow the fsinfo() syscall to look up a mount object by ID rather than by
> pathname. This is necessary as there can be multiple mounts stacked up at
> the same pathname and there's no way to look through them otherwise.
>
> This is done by passing AT_FSINFO_MOUNTID_PATH to fsinfo() in the
> parameters and then passing the mount ID as a string to fsinfo() in place
> of the filename:
>
> struct fsinfo_params params = {
> .at_flags = AT_FSINFO_MOUNTID_PATH,
> .request = FSINFO_ATTR_IDS,
> };
>
> ret = fsinfo(AT_FDCWD, "21", ¶ms, buffer, sizeof(buffer));
>
> The caller is only permitted to query a mount object if the root directory
> of that mount connects directly to the current chroot if dfd == AT_FDCWD[*]
> or the directory specified by dfd otherwise. Note that this is not
> available to the pathwalk of any other syscall.
>
> [*] This needs to be something other than AT_FDCWD, perhaps AT_FDROOT.
>
> [!] This probably needs an LSM hook.
>
> [!] This might want to check the permissions on all the intervening dirs -
> but it would have to do that under RCU conditions.
>
> [!] This might want to check a CAP_* flag.
I would recommend you drop that patch for now.
First, because that patchset itself is already so huge that it's hard to
get enough reviewers to look at it in detail.
Second, from your "[!]" comments above it's obvious that the details of
this feature are not clear enough and need more discussion.
Third, (relatest to the first point) this patchset could use a little
shrinking. :)
>
> Signed-off-by: David Howells <[email protected]>
> ---
>
> fs/fsinfo.c | 56 +++++++++++++++++++++
> fs/internal.h | 2 +
> fs/namespace.c | 117 +++++++++++++++++++++++++++++++++++++++++++-
> include/uapi/linux/fcntl.h | 1
> 4 files changed, 173 insertions(+), 3 deletions(-)
>
> diff --git a/fs/fsinfo.c b/fs/fsinfo.c
> index 127538193b77..3b218f9fedb7 100644
> --- a/fs/fsinfo.c
> +++ b/fs/fsinfo.c
> @@ -516,6 +516,57 @@ static int vfs_fsinfo_fscontext(int fd, struct fsinfo_kparams *params)
> return ret;
> }
>
> +/*
> + * Look up the root of a mount object. This allows access to mount objects
> + * (and their attached superblocks) that can't be retrieved by path because
> + * they're entirely covered.
> + *
> + * We only permit access to a mount that has a direct path between either the
> + * dentry pointed to by dfd or to our chroot (if dfd is AT_FDCWD).
> + */
> +static int vfs_fsinfo_mount(int dfd, const char __user *filename,
> + struct fsinfo_kparams *params)
> +{
> + struct path path;
> + struct fd f = {};
> + char *name;
> + long mnt_id;
> + int ret;
> +
> + if ((params->at_flags & ~AT_FSINFO_MOUNTID_PATH) ||
> + !filename)
> + return -EINVAL;
> +
> + name = strndup_user(filename, 32);
> + if (IS_ERR(name))
> + return PTR_ERR(name);
> + ret = kstrtoul(name, 0, &mnt_id);
> + if (ret < 0)
> + goto out_name;
> + if (mnt_id > INT_MAX)
> + goto out_name;
> +
> + if (dfd != AT_FDCWD) {
> + ret = -EBADF;
> + f = fdget_raw(dfd);
> + if (!f.file)
> + goto out_name;
> + }
> +
> + ret = lookup_mount_object(f.file ? &f.file->f_path : NULL,
> + mnt_id, &path);
> + if (ret < 0)
> + goto out_fd;
> +
> + ret = vfs_fsinfo(&path, params);
> + path_put(&path);
> +out_fd:
> + fdput(f);
> +out_name:
> + kfree(name);
> + return ret;
> +}
> +
> /*
> * Return buffer information by requestable attribute.
> *
> @@ -629,6 +680,9 @@ SYSCALL_DEFINE5(fsinfo,
>
> if ((params.at_flags & AT_FSINFO_FROM_FSOPEN) && filename)
> return -EINVAL;
> + if ((params.at_flags & (AT_FSINFO_FROM_FSOPEN | AT_FSINFO_MOUNTID_PATH)) ==
> + (AT_FSINFO_FROM_FSOPEN | AT_FSINFO_MOUNTID_PATH))
> + return -EINVAL;
> } else {
> params.request = FSINFO_ATTR_STATFS;
> }
> @@ -688,6 +742,8 @@ SYSCALL_DEFINE5(fsinfo,
>
> if (params.at_flags & AT_FSINFO_FROM_FSOPEN)
> ret = vfs_fsinfo_fscontext(dfd, ¶ms);
> + else if (params.at_flags & AT_FSINFO_MOUNTID_PATH)
> + ret = vfs_fsinfo_mount(dfd, filename, ¶ms);
> else if (filename)
> ret = vfs_fsinfo_path(dfd, filename, ¶ms);
> else
> diff --git a/fs/internal.h b/fs/internal.h
> index b089a489da1f..074b1c65e3bd 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -97,6 +97,8 @@ extern int __mnt_want_write_file(struct file *);
> extern void __mnt_drop_write_file(struct file *);
>
> extern void dissolve_on_fput(struct vfsmount *);
> +extern int lookup_mount_object(struct path *, int, struct path *);
> +
> /*
> * fs_struct.c
> */
> diff --git a/fs/namespace.c b/fs/namespace.c
> index 1141641dff96..a49a7d9ed482 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -62,7 +62,7 @@ static int __init set_mphash_entries(char *str)
> __setup("mphash_entries=", set_mphash_entries);
>
> static u64 event;
> -static DEFINE_IDA(mnt_id_ida);
> +static DEFINE_IDR(mnt_id_ida);
> static DEFINE_IDA(mnt_group_ida);
>
> static struct hlist_head *mount_hashtable __read_mostly;
> @@ -101,17 +101,27 @@ static inline struct hlist_head *mp_hash(struct dentry *dentry)
>
> static int mnt_alloc_id(struct mount *mnt)
> {
> - int res = ida_alloc(&mnt_id_ida, GFP_KERNEL);
> + int res;
>
> + /* Allocate an ID, but don't set the pointer back to the mount until
> + * later, as once we do that, we have to follow RCU protocols to get
> + * rid of the mount struct.
> + */
> + res = idr_alloc(&mnt_id_ida, NULL, 0, INT_MAX, GFP_KERNEL);
> if (res < 0)
> return res;
> mnt->mnt_id = res;
> return 0;
> }
>
> +static void mnt_publish_id(struct mount *mnt)
> +{
> + idr_replace(&mnt_id_ida, mnt, mnt->mnt_id);
> +}
> +
> static void mnt_free_id(struct mount *mnt)
> {
> - ida_free(&mnt_id_ida, mnt->mnt_id);
> + idr_remove(&mnt_id_ida, mnt->mnt_id);
> }
>
> /*
> @@ -974,6 +984,7 @@ struct vfsmount *vfs_create_mount(struct fs_context *fc)
> lock_mount_hash();
> list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts);
> unlock_mount_hash();
> + mnt_publish_id(mnt);
> return &mnt->mnt;
> }
> EXPORT_SYMBOL(vfs_create_mount);
> @@ -1067,6 +1078,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
> lock_mount_hash();
> list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
> unlock_mount_hash();
> + mnt_publish_id(mnt);
>
> if ((flag & CL_SLAVE) ||
> ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) {
> @@ -3988,3 +4000,102 @@ const struct proc_ns_operations mntns_operations = {
> .install = mntns_install,
> .owner = mntns_owner,
> };
> +
> +/*
> + * See if one path point connects directly to another by ancestral relationship
> + * across mountpoints. Must call with the RCU read lock held.
> + */
> +static bool are_paths_connected(struct path *ancestor, struct path *to_check)
> +{
> + struct mount *mnt, *parent;
> + struct path cursor;
> + unsigned seq;
> + bool connected;
> +
> + seq = 0;
> +restart:
> + cursor = *to_check;
> +
> + read_seqbegin_or_lock(&rename_lock, &seq);
> + while (cursor.mnt != ancestor->mnt) {
> + mnt = real_mount(cursor.mnt);
> + parent = READ_ONCE(mnt->mnt_parent);
> + if (mnt == parent)
> + goto failed;
> + cursor.dentry = READ_ONCE(mnt->mnt_mountpoint);
> + cursor.mnt = &parent->mnt;
> + }
> +
> + while (cursor.dentry != ancestor->dentry) {
> + if (cursor.dentry == cursor.mnt->mnt_root ||
> + IS_ROOT(cursor.dentry))
> + goto failed;
> + cursor.dentry = READ_ONCE(cursor.dentry->d_parent);
> + }
> +
> + connected = true;
> +out:
> + done_seqretry(&rename_lock, seq);
> + return connected;
> +
> +failed:
> + if (need_seqretry(&rename_lock, seq)) {
> + seq = 1;
> + goto restart;
> + }
> + connected = false;
> + goto out;
> +}
> +
> +/**
> + * lookup_mount_object - Look up a vfsmount object by ID
> + * @root: The mount root must connect backwards to this point (or chroot if NULL).
> + * @id: The ID of the mountpoint.
> + * @_mntpt: Where to return the resulting mountpoint path.
> + *
> + * Look up the root of the mount with the corresponding ID. This is only
> + * permitted if that mount connects directly to the specified root/chroot.
> + */
> +int lookup_mount_object(struct path *root, int mnt_id, struct path *_mntpt)
> +{
> + struct mount *mnt;
> + struct path stop, mntpt = {};
> + int ret = -EPERM;
> +
> + if (!root)
> + get_fs_root(current->fs, &stop);
> + else
> + stop = *root;
> +
> + rcu_read_lock();
> + lock_mount_hash();
> + mnt = idr_find(&mnt_id_ida, mnt_id);
> + if (!mnt)
> + goto out_unlock_mh;
> + if (mnt->mnt.mnt_flags & (MNT_SYNC_UMOUNT | MNT_UMOUNT | MNT_DOOMED))
> + goto out_unlock_mh;
> + if (mnt_get_count(mnt) == 0)
> + goto out_unlock_mh;
> + mnt_add_count(mnt, 1);
> + mntpt.mnt = &mnt->mnt;
> + mntpt.dentry = dget(mnt->mnt.mnt_root);
> + unlock_mount_hash();
> +
> + if (are_paths_connected(&stop, &mntpt)) {
> + *_mntpt = mntpt;
> + mntpt.mnt = NULL;
> + mntpt.dentry = NULL;
> + ret = 0;
> + }
> +
> +out_unlock:
> + rcu_read_unlock();
> + if (!root)
> + path_put(&stop);
> + path_put(&mntpt);
> + return ret;
> +
> +out_unlock_mh:
> + unlock_mount_hash();
> + goto out_unlock;
> +}
> diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h
> index 6a2402a8fa30..5fda91cfca8a 100644
> --- a/include/uapi/linux/fcntl.h
> +++ b/include/uapi/linux/fcntl.h
> @@ -92,6 +92,7 @@
> #define AT_STATX_DONT_SYNC 0x4000 /* - Don't sync attributes with the server */
>
> #define AT_FSINFO_FROM_FSOPEN 0x2000 /* Examine the fs_context attached to dfd by fsopen() */
> +#define AT_FSINFO_MOUNTID_PATH 0x4000 /* The path is a mount object ID, not an actual path */
>
> #define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */
>
>
On Mon, Jun 24, 2019 at 03:10:06PM +0100, David Howells wrote:
> Add a notification count on mount objects so that the user can easily check
> to see if a mount has changed its attributes or its children.
>
> Future patches will:
>
> (1) Provide this value through fsinfo() attributes.
>
> (2) Hook into the notify_mount() function to provide a notification
> interface for userspace to monitor.
Sorry, I might have missed this. Is this based on your notification
patchset and thus presupposing that your notification patchset has been
merged?
(One further question below.)
>
> Signed-off-by: David Howells <[email protected]>
> ---
>
> fs/mount.h | 22 ++++++++++++++++++++++
> fs/namespace.c | 13 +++++++++++++
> 2 files changed, 35 insertions(+)
>
> diff --git a/fs/mount.h b/fs/mount.h
> index 6250de544760..47795802f78e 100644
> --- a/fs/mount.h
> +++ b/fs/mount.h
> @@ -70,6 +70,7 @@ struct mount {
> struct hlist_head mnt_pins;
> struct fs_pin mnt_umount;
> struct dentry *mnt_ex_mountpoint;
> + atomic_t mnt_notify_counter; /* Number of notifications generated */
> } __randomize_layout;
>
> #define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
> @@ -151,3 +152,24 @@ static inline bool is_anon_ns(struct mnt_namespace *ns)
> {
> return ns->seq == 0;
> }
> +
> +/*
> + * Type of mount topology change notification.
> + */
> +enum mount_notification_subtype {
> + NOTIFY_MOUNT_NEW_MOUNT = 0, /* New mount added */
> + NOTIFY_MOUNT_UNMOUNT = 1, /* Mount removed manually */
> + NOTIFY_MOUNT_EXPIRY = 2, /* Automount expired */
> + NOTIFY_MOUNT_READONLY = 3, /* Mount R/O state changed */
> + NOTIFY_MOUNT_SETATTR = 4, /* Mount attributes changed */
> + NOTIFY_MOUNT_MOVE_FROM = 5, /* Mount moved from here */
> + NOTIFY_MOUNT_MOVE_TO = 6, /* Mount moved to here (compare op_id) */
> +};
> +
> +static inline void notify_mount(struct mount *changed,
> + struct mount *aux,
> + enum mount_notification_subtype subtype,
> + u32 info_flags)
> +{
> + atomic_inc(&changed->mnt_notify_counter);
> +}
> diff --git a/fs/namespace.c b/fs/namespace.c
> index a49a7d9ed482..1450faab96b9 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -513,6 +513,8 @@ static int mnt_make_readonly(struct mount *mnt)
> smp_wmb();
> mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD;
> unlock_mount_hash();
> + if (ret == 0)
> + notify_mount(mnt, NULL, NOTIFY_MOUNT_READONLY, 0x10000);
> return ret;
> }
>
> @@ -521,6 +523,7 @@ static int __mnt_unmake_readonly(struct mount *mnt)
> lock_mount_hash();
> mnt->mnt.mnt_flags &= ~MNT_READONLY;
> unlock_mount_hash();
> + notify_mount(mnt, NULL, NOTIFY_MOUNT_READONLY, 0);
> return 0;
> }
>
> @@ -833,6 +836,7 @@ static void umount_mnt(struct mount *mnt)
> {
> /* old mountpoint will be dropped when we can do that */
> mnt->mnt_ex_mountpoint = mnt->mnt_mountpoint;
> + notify_mount(mnt->mnt_parent, mnt, NOTIFY_MOUNT_UNMOUNT, 0);
> unhash_mnt(mnt);
> }
>
> @@ -1472,6 +1476,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
> p = list_first_entry(&tmp_list, struct mount, mnt_list);
> list_del_init(&p->mnt_expire);
> list_del_init(&p->mnt_list);
> +
> ns = p->mnt_ns;
> if (ns) {
> ns->mounts--;
> @@ -2095,7 +2100,10 @@ static int attach_recursive_mnt(struct mount *source_mnt,
> lock_mount_hash();
> }
> if (parent_path) {
> + notify_mount(source_mnt->mnt_parent, source_mnt,
> + NOTIFY_MOUNT_MOVE_FROM, 0);
> detach_mnt(source_mnt, parent_path);
> + notify_mount(dest_mnt, source_mnt, NOTIFY_MOUNT_MOVE_TO, 0);
> attach_mnt(source_mnt, dest_mnt, dest_mp);
> touch_mnt_namespace(source_mnt->mnt_ns);
> } else {
> @@ -2104,6 +2112,9 @@ static int attach_recursive_mnt(struct mount *source_mnt,
> list_del_init(&source_mnt->mnt_ns->list);
> }
> mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt);
> + notify_mount(dest_mnt, source_mnt, NOTIFY_MOUNT_NEW_MOUNT,
> + source_mnt->mnt.mnt_sb->s_flags & SB_SUBMOUNT ?
> + 0x10000 : 0);
What's that magic 0x10000 mean?
> commit_tree(source_mnt);
> }
>
> @@ -2480,6 +2491,7 @@ static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags)
> mnt->mnt.mnt_flags = mnt_flags;
> touch_mnt_namespace(mnt->mnt_ns);
> unlock_mount_hash();
> + notify_mount(mnt, NULL, NOTIFY_MOUNT_SETATTR, 0);
> }
>
> /*
> @@ -2880,6 +2892,7 @@ void mark_mounts_for_expiry(struct list_head *mounts)
> if (!xchg(&mnt->mnt_expiry_mark, 1) ||
> propagate_mount_busy(mnt, 1))
> continue;
> + notify_mount(mnt, NULL, NOTIFY_MOUNT_EXPIRY, 0);
> list_move(&mnt->mnt_expire, &graveyard);
> }
> while (!list_empty(&graveyard)) {
>
On Mon, Jun 24, 2019 at 03:10:20PM +0100, David Howells wrote:
> Allow mount information, including information about the topology tree to
> be queried with the fsinfo() system call. Usage of AT_FSINFO_MOUNTID_PATH
> allows overlapping mounts to be queried.
Again, I really think that this doesn't need to land at the same time as
the basic infrastructure for fsinfo()...
>
> To this end, four fsinfo() attributes are provided:
>
> (1) FSINFO_ATTR_MOUNT_INFO.
>
> This is a structure providing information about a mount, including:
>
> - Mounted superblock ID.
> - Mount ID (as AT_FSINFO_MOUNTID_PATH).
> - Parent mount ID.
> - Mount attributes (eg. R/O, NOEXEC).
> - Number of change notifications generated.
>
> Note that the parent mount ID is overridden to the ID of the queried
> mount if the parent lies outside of the chroot or dfd tree.
>
> (2) FSINFO_ATTR_MOUNT_DEVNAME.
>
> This a string providing the device name associated with the mount.
>
> Note that the device name may be a path that lies outside of the root.
>
> (3) FSINFO_ATTR_MOUNT_CHILDREN.
>
> This produces an array of structures, one for each child and capped
> with one for the argument mount (checked after listing all the
> children). Each element contains the mount ID and the notification
> counter of the respective mount object.
>
> (4) FSINFO_ATTR_MOUNT_SUBMOUNT.
>
> This is a 1D array of strings, indexed with struct fsinfo_params::Nth.
> Each string is the relative pathname of the corresponding child
> returned by FSINFO_ATTR_MOUNT_CHILDREN.
>
> Note that paths in the mount at the base of the tree (whether that be
> dfd or chroot) are relative to the base of the tree, not the root
> directory of that mount.
>
> Signed-off-by: David Howells <[email protected]>
> ---
>
> fs/d_path.c | 2
> fs/fsinfo.c | 8 ++
> fs/internal.h | 9 ++
> fs/namespace.c | 177 +++++++++++++++++++++++++++++++++++++++++++
> include/uapi/linux/fsinfo.h | 28 +++++++
> samples/vfs/test-fsinfo.c | 47 +++++++++++
> 6 files changed, 267 insertions(+), 4 deletions(-)
>
> diff --git a/fs/d_path.c b/fs/d_path.c
> index a7d0a96b35ce..89d77c264c5f 100644
> --- a/fs/d_path.c
> +++ b/fs/d_path.c
> @@ -227,7 +227,7 @@ static int prepend_unreachable(char **buffer, int *buflen)
> return prepend(buffer, buflen, "(unreachable)", 13);
> }
>
> -static void get_fs_root_rcu(struct fs_struct *fs, struct path *root)
> +void get_fs_root_rcu(struct fs_struct *fs, struct path *root)
> {
> unsigned seq;
>
> diff --git a/fs/fsinfo.c b/fs/fsinfo.c
> index 3b218f9fedb7..61f00f375fd2 100644
> --- a/fs/fsinfo.c
> +++ b/fs/fsinfo.c
> @@ -348,6 +348,10 @@ int generic_fsinfo(struct path *path, struct fsinfo_kparams *params)
> case _genf(PARAM_SPECIFICATION, param_specification);
> case _genf(PARAM_ENUM, param_enum);
> case _genp(PARAMETERS, parameters);
> + case _genp(MOUNT_INFO, mount_info);
> + case _genp(MOUNT_DEVNAME, mount_devname);
> + case _genp(MOUNT_CHILDREN, mount_children);
> + case _genp(MOUNT_SUBMOUNT, mount_submount);
> default:
> return -EOPNOTSUPP;
> }
> @@ -627,6 +631,10 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
> FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
> FSINFO_OPAQUE (PARAMETERS, -),
> FSINFO_OPAQUE (LSM_PARAMETERS, -),
> + FSINFO_STRUCT (MOUNT_INFO, mount_info),
> + FSINFO_STRING (MOUNT_DEVNAME, mount_devname),
> + FSINFO_STRUCT_ARRAY (MOUNT_CHILDREN, mount_child),
> + FSINFO_STRING_N (MOUNT_SUBMOUNT, mount_submount),
> };
>
> /**
> diff --git a/fs/internal.h b/fs/internal.h
> index 074b1c65e3bd..bb3d8efa7f49 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -53,6 +53,11 @@ void __generic_write_end(struct inode *inode, loff_t pos, unsigned copied,
> */
> extern void __init chrdev_init(void);
>
> +/*
> + * d_path.c
> + */
> +extern void get_fs_root_rcu(struct fs_struct *fs, struct path *root);
> +
> /*
> * fs_context.c
> */
> @@ -98,6 +103,10 @@ extern void __mnt_drop_write_file(struct file *);
>
> extern void dissolve_on_fput(struct vfsmount *);
> extern int lookup_mount_object(struct path *, int, struct path *);
> +extern int fsinfo_generic_mount_info(struct path *, struct fsinfo_kparams *);
> +extern int fsinfo_generic_mount_devname(struct path *, struct fsinfo_kparams *);
> +extern int fsinfo_generic_mount_children(struct path *, struct fsinfo_kparams *);
> +extern int fsinfo_generic_mount_submount(struct path *, struct fsinfo_kparams *);
>
> /*
> * fs_struct.c
> diff --git a/fs/namespace.c b/fs/namespace.c
> index 1450faab96b9..2ec7d9d1905a 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -29,6 +29,7 @@
> #include <linux/sched/task.h>
> #include <uapi/linux/mount.h>
> #include <linux/fs_context.h>
> +#include <linux/fsinfo.h>
>
> #include "pnode.h"
> #include "internal.h"
> @@ -4112,3 +4113,179 @@ int lookup_mount_object(struct path *root, int mnt_id, struct path *_mntpt)
> unlock_mount_hash();
> goto out_unlock;
> }
> +
> +#ifdef CONFIG_FSINFO
> +int fsinfo_generic_mount_info(struct path *path, struct fsinfo_kparams *params)
> +{
> + struct fsinfo_mount_info *p = params->buffer;
> + struct super_block *sb;
> + struct mount *m;
> + struct path root;
> + unsigned int flags;
> +
> + if (!path->mnt)
> + return -ENODATA;
> +
> + m = real_mount(path->mnt);
> + sb = m->mnt.mnt_sb;
> +
> + p->f_sb_id = sb->s_unique_id;
> + p->mnt_id = m->mnt_id;
> + p->parent_id = m->mnt_parent->mnt_id;
> + p->notify_counter = atomic_read(&m->mnt_notify_counter);
> +
> + get_fs_root(current->fs, &root);
> + if (path->mnt == root.mnt) {
> + p->parent_id = p->mnt_id;
> + } else {
> + rcu_read_lock();
> + if (!are_paths_connected(&root, path))
> + p->parent_id = p->mnt_id;
> + rcu_read_unlock();
> + }
> + if (IS_MNT_SHARED(m))
> + p->group_id = m->mnt_group_id;
> + if (IS_MNT_SLAVE(m)) {
> + int master = m->mnt_master->mnt_group_id;
> + int dom = get_dominating_id(m, &root);
> + p->master_id = master;
> + if (dom && dom != master)
> + p->from_id = dom;
> + }
> + path_put(&root);
> +
> + flags = READ_ONCE(m->mnt.mnt_flags);
> + if (flags & MNT_READONLY)
> + p->attr |= MOUNT_ATTR_RDONLY;
> + if (flags & MNT_NOSUID)
> + p->attr |= MOUNT_ATTR_NOSUID;
> + if (flags & MNT_NODEV)
> + p->attr |= MOUNT_ATTR_NODEV;
> + if (flags & MNT_NOEXEC)
> + p->attr |= MOUNT_ATTR_NOEXEC;
> + if (flags & MNT_NODIRATIME)
> + p->attr |= MOUNT_ATTR_NODIRATIME;
> +
> + if (flags & MNT_NOATIME)
> + p->attr |= MOUNT_ATTR_NOATIME;
> + else if (flags & MNT_RELATIME)
> + p->attr |= MOUNT_ATTR_RELATIME;
> + else
> + p->attr |= MOUNT_ATTR_STRICTATIME;
> + return sizeof(*p);
> +}
> +
> +int fsinfo_generic_mount_devname(struct path *path, struct fsinfo_kparams *params)
> +{
> + struct mount *m;
> + size_t len;
> +
> + if (!path->mnt)
> + return -ENODATA;
> +
> + m = real_mount(path->mnt);
> + len = strlen(m->mnt_devname);
> + memcpy(params->buffer, m->mnt_devname, len);
> + return len;
> +}
> +
> +/*
> + * Store a mount record into the fsinfo buffer.
> + */
> +static void store_mount_fsinfo(struct fsinfo_kparams *params,
> + struct fsinfo_mount_child *child)
> +{
> + unsigned int usage = params->usage;
> + unsigned int total = sizeof(*child);
> +
> + if (params->usage >= INT_MAX)
> + return;
> + params->usage = usage + total;
> + if (params->buffer && params->usage <= params->buf_size)
> + memcpy(params->buffer + usage, child, total);
> +}
> +
> +/*
> + * Return information about the submounts relative to path.
> + */
> +int fsinfo_generic_mount_children(struct path *path, struct fsinfo_kparams *params)
> +{
> + struct fsinfo_mount_child record;
> + struct mount *m, *child;
> +
> + if (!path->mnt)
> + return -ENODATA;
> +
> + m = real_mount(path->mnt);
> +
> + rcu_read_lock();
> + list_for_each_entry_rcu(child, &m->mnt_mounts, mnt_child) {
> + if (child->mnt_parent != m)
> + continue;
> + record.mnt_id = child->mnt_id;
> + record.notify_counter = atomic_read(&child->mnt_notify_counter);
> + store_mount_fsinfo(params, &record);
> + }
> + rcu_read_unlock();
> +
> + /* End the list with a copy of the parameter mount's details so that
> + * userspace can quickly check for changes.
> + */
> + record.mnt_id = m->mnt_id;
> + record.notify_counter = atomic_read(&m->mnt_notify_counter);
> + store_mount_fsinfo(params, &record);
> + return params->usage;
> +}
> +
> +/*
> + * Return the path of the Nth submount relative to path. This is derived from
> + * d_path(), but the root determination is more complicated.
> + */
> +int fsinfo_generic_mount_submount(struct path *path, struct fsinfo_kparams *params)
> +{
> + struct mountpoint *mp;
> + struct mount *m, *child;
> + struct path mountpoint, root;
> + unsigned int n = params->Nth;
> + size_t len;
> + void *p;
> +
> + if (!path->mnt)
> + return -ENODATA;
> +
> + rcu_read_lock();
> +
> + m = real_mount(path->mnt);
> + list_for_each_entry_rcu(child, &m->mnt_mounts, mnt_child) {
> + mp = READ_ONCE(child->mnt_mp);
> + if (child->mnt_parent != m || !mp)
> + continue;
> + if (n-- == 0)
> + goto found;
> + }
> + rcu_read_unlock();
> + return -ENODATA;
> +
> +found:
> + mountpoint.mnt = path->mnt;
> + mountpoint.dentry = READ_ONCE(mp->m_dentry);
> +
> + get_fs_root_rcu(current->fs, &root);
> + if (root.mnt != path->mnt) {
> + root.mnt = path->mnt;
> + root.dentry = path->mnt->mnt_root;
> + }
> +
> + p = __d_path(&mountpoint, &root, params->buffer, params->buf_size);
> + rcu_read_unlock();
> +
> + if (IS_ERR(p))
> + return PTR_ERR(p);
> + if (!p)
> + return -EPERM;
> +
> + len = (params->buffer + params->buf_size) - p;
> + memmove(params->buffer, p, len);
> + return len;
> +}
> +#endif /* CONFIG_FSINFO */
> diff --git a/include/uapi/linux/fsinfo.h b/include/uapi/linux/fsinfo.h
> index bae0bdc9ace9..88e1d004ac6c 100644
> --- a/include/uapi/linux/fsinfo.h
> +++ b/include/uapi/linux/fsinfo.h
> @@ -32,6 +32,10 @@ enum fsinfo_attribute {
> FSINFO_ATTR_PARAM_ENUM = 14, /* Nth enum-to-val */
> FSINFO_ATTR_PARAMETERS = 15, /* Mount parameters (large string) */
> FSINFO_ATTR_LSM_PARAMETERS = 16, /* LSM Mount parameters (large string) */
> + FSINFO_ATTR_MOUNT_INFO = 17, /* Mount object information */
> + FSINFO_ATTR_MOUNT_DEVNAME = 18, /* Mount object device name (string) */
> + FSINFO_ATTR_MOUNT_CHILDREN = 19, /* Submount list (array) */
> + FSINFO_ATTR_MOUNT_SUBMOUNT = 20, /* Relative path of Nth submount (string) */
> FSINFO_ATTR__NR
> };
>
> @@ -276,4 +280,28 @@ struct fsinfo_param_enum {
> char name[252]; /* Name of the enum value */
> };
>
> +/*
> + * Information struct for fsinfo(FSINFO_ATTR_MOUNT_INFO).
> + */
> +struct fsinfo_mount_info {
> + __u64 f_sb_id; /* Superblock ID */
> + __u32 mnt_id; /* Mount identifier (use with AT_FSINFO_MOUNTID_PATH) */
> + __u32 parent_id; /* Parent mount identifier */
> + __u32 group_id; /* Mount group ID */
> + __u32 master_id; /* Slave master group ID */
> + __u32 from_id; /* Slave propagated from ID */
> + __u32 attr; /* MOUNT_ATTR_* flags */
> + __u32 notify_counter; /* Number of notifications generated. */
> + __u32 __reserved[1];
> +};
> +
> +/*
> + * Information struct element for fsinfo(FSINFO_ATTR_MOUNT_CHILDREN).
> + * - An extra element is placed on the end representing the parent mount.
> + */
> +struct fsinfo_mount_child {
> + __u32 mnt_id; /* Mount identifier (use with AT_FSINFO_MOUNTID_PATH) */
> + __u32 notify_counter; /* Number of notifications generated on mount. */
> +};
> +
> #endif /* _UAPI_LINUX_FSINFO_H */
> diff --git a/samples/vfs/test-fsinfo.c b/samples/vfs/test-fsinfo.c
> index fadc5e1384fc..ab32a15d4c5b 100644
> --- a/samples/vfs/test-fsinfo.c
> +++ b/samples/vfs/test-fsinfo.c
> @@ -21,10 +21,10 @@
> #include <errno.h>
> #include <time.h>
> #include <math.h>
> -#include <fcntl.h>
> #include <sys/syscall.h>
> #include <linux/fsinfo.h>
> #include <linux/socket.h>
> +#include <linux/fcntl.h>
> #include <sys/stat.h>
> #include <arpa/inet.h>
>
> @@ -83,6 +83,10 @@ static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
> FSINFO_STRUCT_N (PARAM_ENUM, param_enum),
> FSINFO_OVERLARGE (PARAMETERS, -),
> FSINFO_OVERLARGE (LSM_PARAMETERS, -),
> + FSINFO_STRUCT (MOUNT_INFO, mount_info),
> + FSINFO_STRING (MOUNT_DEVNAME, mount_devname),
> + FSINFO_STRUCT_ARRAY (MOUNT_CHILDREN, mount_child),
> + FSINFO_STRING_N (MOUNT_SUBMOUNT, mount_submount),
> };
>
> #define FSINFO_NAME(X,Y) [FSINFO_ATTR_##X] = #Y
> @@ -104,6 +108,10 @@ static const char *fsinfo_attr_names[FSINFO_ATTR__NR] = {
> FSINFO_NAME (PARAM_ENUM, param_enum),
> FSINFO_NAME (PARAMETERS, parameters),
> FSINFO_NAME (LSM_PARAMETERS, lsm_parameters),
> + FSINFO_NAME (MOUNT_INFO, mount_info),
> + FSINFO_NAME (MOUNT_DEVNAME, mount_devname),
> + FSINFO_NAME (MOUNT_CHILDREN, mount_children),
> + FSINFO_NAME (MOUNT_SUBMOUNT, mount_submount),
> };
>
> union reply {
> @@ -116,6 +124,8 @@ union reply {
> struct fsinfo_capabilities caps;
> struct fsinfo_timestamp_info timestamps;
> struct fsinfo_volume_uuid uuid;
> + struct fsinfo_mount_info mount_info;
> + struct fsinfo_mount_child mount_children[1];
> };
>
> static void dump_hex(unsigned int *data, int from, int to)
> @@ -319,6 +329,29 @@ static void dump_attr_VOLUME_UUID(union reply *r, int size)
> f->uuid[14], f->uuid[15]);
> }
>
> +static void dump_attr_MOUNT_INFO(union reply *r, int size)
> +{
> + struct fsinfo_mount_info *f = &r->mount_info;
> +
> + printf("\n");
> + printf("\tsb_id : %llx\n", (unsigned long long)f->f_sb_id);
> + printf("\tmnt_id : %x\n", f->mnt_id);
> + printf("\tparent : %x\n", f->parent_id);
> + printf("\tgroup : %x\n", f->group_id);
> + printf("\tattr : %x\n", f->attr);
> + printf("\tnotifs : %x\n", f->notify_counter);
> +}
> +
> +static void dump_attr_MOUNT_CHILDREN(union reply *r, int size)
> +{
> + struct fsinfo_mount_child *f = r->mount_children;
> + int i = 0;
> +
> + printf("\n");
> + for (; size >= sizeof(*f); size -= sizeof(*f), f++)
> + printf("\t[%u] %8x %8x\n", i++, f->mnt_id, f->notify_counter);
> +}
> +
> /*
> *
> */
> @@ -334,6 +367,8 @@ static const dumper_t fsinfo_attr_dumper[FSINFO_ATTR__NR] = {
> FSINFO_DUMPER(CAPABILITIES),
> FSINFO_DUMPER(TIMESTAMP_INFO),
> FSINFO_DUMPER(VOLUME_UUID),
> + FSINFO_DUMPER(MOUNT_INFO),
> + FSINFO_DUMPER(MOUNT_CHILDREN),
> };
>
> static void dump_fsinfo(enum fsinfo_attribute attr,
> @@ -536,16 +571,21 @@ int main(int argc, char **argv)
> unsigned int attr;
> int raw = 0, opt, Nth, Mth;
>
> - while ((opt = getopt(argc, argv, "adlr"))) {
> + while ((opt = getopt(argc, argv, "Madlr"))) {
> switch (opt) {
> + case 'M':
> + params.at_flags = AT_FSINFO_MOUNTID_PATH;
> + continue;
> case 'a':
> params.at_flags |= AT_NO_AUTOMOUNT;
> + params.at_flags &= ~AT_FSINFO_MOUNTID_PATH;
> continue;
> case 'd':
> debug = true;
> continue;
> case 'l':
> params.at_flags &= ~AT_SYMLINK_NOFOLLOW;
> + params.at_flags &= ~AT_FSINFO_MOUNTID_PATH;
> continue;
> case 'r':
> raw = 1;
> @@ -558,7 +598,8 @@ int main(int argc, char **argv)
> argv += optind;
>
> if (argc != 1) {
> - printf("Format: test-fsinfo [-alr] <file>\n");
> + printf("Format: test-fsinfo [-adlr] <file>\n");
> + printf("Format: test-fsinfo [-dr] -M <mnt_id>\n");
> exit(2);
> }
>
>
On Wed, Jun 26, 2019 at 10:49:12AM +0100, David Howells wrote:
> Christian Brauner <[email protected]> wrote:
>
> > > + return sizeof(*p);
> >
> > Hm, the discrepancy between the function signature returning int and
> > the sizeof operator most likely being size_t is bothering me. It
> > probably doesn't matter but maybe we can avoid that.
>
> If sizeof(*p) exceeds 4096, the buffer is going to have been overrun by this
> point anyway.
Ok.
>
> The function can't return size_t, though it could return ssize_t. I could
> switch it to return long or even store the result in fsinfo_kparams::usage and
> return 0.
>
> > > + strlcpy(p->f_fs_name, path->dentry->d_sb->s_type->name,
> > > + sizeof(p->f_fs_name));
> >
> > Truncation is acceptable or impossible I assume?
>
> I'm hoping that file_system_type::name isn't going to exceed 15 chars plus
> NUL. If it does, it will be truncated. I don't really want to add an
> individual attribute just for the filesystem driver name.
>
> > > +#define _gen(X, Y) FSINFO_ATTR_##X: return fsinfo_generic_##Y(path, params->buffer)
> >
> > I'm really not sure that this helps readability in the switch below... :)
> >
> > > +
> > > + switch (params->request) {
> > > + case _gen(STATFS, statfs);
> > > + case _gen(IDS, ids);
> > > + case _gen(LIMITS, limits);
> > > + case _gen(SUPPORTS, supports);
> > > + case _gen(CAPABILITIES, capabilities);
> > > + case _gen(TIMESTAMP_INFO, timestamp_info);
> > > ...
>
> I'm trying to avoid having to spend multiple lines per case and tabulation
> makes things easier to read. So
>
> case FSINFO_ATTR_SUPPORTS: return fsinfo_generic_supports(path, params->buffer);
> case FSINFO_ATTR_CAPABILITIES: return fsinfo_generic_capabilities(path, params->buffer);
> case FSINFO_ATTR_TIMESTAMP_INFO: return fsinfo_generic_timestamp_info(path, params->buffer);
>
> is a bit on the long side per line, whereas:
>
> case FSINFO_ATTR_SUPPORTS:
> return fsinfo_generic_supports(path, params->buffer);
> case FSINFO_ATTR_CAPABILITIES:
> return fsinfo_generic_capabilities(path, params->buffer);
> case FSINFO_ATTR_TIMESTAMP_INFO:
> return fsinfo_generic_timestamp_info(path, params->buffer);
>
> is less readable by interleaving two of the three columns. (Note that _gen is
> a actually third column as I introduce alternatives later).
>
> > > + if (ret <= (int)params->buf_size)
> >
> > He, and this is where the return value discrepancy hits again. Just
> > doesn't look nice tbh. :)
>
> No. That's dealing with signed/unsigned comparison. It might be better if I
> change this to:
>
> if (IS_ERR_VALUE(ret))
> return ret; /* Error */
> if ((unsigned int)ret <= params->buf_size)
> return ret; /* It fitted */
>
> In any case, buf_size isn't permitted to be larger than INT_MAX due to a check
> later in the loop.
>
> > > + kvfree(params->buffer);
> >
> > That means callers should always memset fsinfo_kparams or this is an
> > invalid free...
>
> vfs_info() isn't a public function. And, in any case, the caller *must*
> provide a buffer here.
>
> > > + * Return buffer information by requestable attribute.
> > > + *
> > > + * STRUCT indicates a fixed-size structure with only one instance.
> > > ...
> > I honestly have a hard time following the documentation here
>
> How about:
>
> * STRUCT - a fixed-size structure with only one instance.
> * STRUCT_N - a sequence of STRUCTs, indexed by Nth
> * STRUCT_NM - a sequence of sequences of STRUCTs, indexed by Nth, Mth
> * STRING - a string with only one instance.
> * STRING_N - a sequence of STRING, indexed by Nth
> * STRING_NM - a sequence of sequences of STRING, indexed by Nth, Mth
> * OPAQUE - a blob that can be larger than 4K.
> * STRUCT_ARRAY - an array of structs that can be larger than 4K
>
> > and that monster table/macro thing below. For example, STRUCT_NM
> > corresponds to __FSINFO_NM or what?
>
> STRUCT_NM -> .type = __FSINFO_STRUCT, .flags = __FSINFO_NM, .size = ...
>
> If you think this is bad, you should try looking at the device ID tables used
> by the drivers and the attribute tables;-)
>
> I could spell out the flag and type in the macro defs (such as the body of
> FSINFO_STRING(X,Y) for instance). It would make it harder to compare macros
> as it wouldn't then tabulate, though.
>
> > And is this uapi as you're using this in your samples/test below?
>
> Not exactly. Each attribute is defined as being a certain type in the
> documentation in the UAPI header, but this is not coded there. The assumption
> being that if you're using a particular attribute, you'll know what the type
> of the attribute is and you'll structure your code appropriately.
>
> The reason the sample code has this replicated is that it doesn't really
> attempt to interpret the type per se. It has a dumper for an individual
> attribute value, but the table tells it whether there should be one of those,
> N of those or N of M(0), M(1), M(2), ... of those so that it can report an
> error if it doesn't see what it expects.
>
> I could even cheaply provide a meta attribute that dumps the contents of the
> table (just the type info, not the names).
>
> > > ...
> > > + FSINFO_STRING (NAME_ENCODING, -),
> > > + FSINFO_STRING (NAME_CODEPAGE, -),
> > > +};
> >
> > Can I complain again that this is really annoying to parse.
>
> Apparently you can;-) What would you prefer? This:
>
> static const struct fsinfo_attr_info fsinfo_buffer_info[FSINFO_ATTR__NR] = {
> [FSINFO_STATFS] = {
> .type = __FSINFO_STRUCT,
> .size = sizeof(struct fsinfo_statfs),
> },
> [FSINFO_SERVERS] = {
> .type = __FSINFO_STRUCT,
> .flags = __FSINFO_NM,
> .size = sizeof(struct fsinfo_server),
> },
> ...
> };
>
> That has 3-5 lines for each 1 in the current code and isn't a great deal more
> readable.
Really, I find this more readable because parsing structs and arrays of
structs is probably still even more common for C programmers then
deciphering nested macros. :) But I won't enforce my own pov. :)
>
> > if (copy_to_user()) and if (clear_user()) and not if (clear_user() != 0)
>
> Better "if (copy_to_user() != 0)" since it's not a boolean return value in
> either case.
>
> > Nit: There's a bunch of name inconsistency for the arguments between the
> > stub and the definition:
> >
> > SYSCALL_DEFINE5(fsinfo,
> > int, dfd, const char __user *, filename,
> > struct fsinfo_params __user *, _params,
> > void __user *, user_buffer, size_t, user_buf_size)
>
> Yeah. C just doesn't care.
>
> I'll change filename to pathname throughout. That's at least consistent with
> various glibc manpages for other vfs syscalls.
>
> _params I can change to params and params as-was to kparams.
>
> But user_buffer and user_buf_size, I'll keep as I've named them such to avoid
> confusion with kparams->buffer and kparams->scratch_buffer. However, I
> wouldn't want to call them that in the UAPI.
Yep, it's really just that I prefer the naming to be consistent. :)
>
> > Do we do SPDX that way? Or isn't this just supposed to be:
> > // <spdxy stuff>
>
> Look in, say, include/uapi/linux/stat.h or .../fs.h.
>
> > > + FSINFO_ATTR__NR
> >
> > Nit/Bikeshed: FSINFO_ATTR_MAX? Seems more intuitive.
>
> No. That would imply a limit that it will never exceed.
>
> > > +struct fsinfo_u128 {
> > > +#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __BIG_ENDIAN : defined(__BIG_ENDIAN)
> > > + __u64 hi;
> > > + __u64 lo;
> > > +#elif defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : defined(__LITTLE_ENDIAN)
> > > + __u64 lo;
> > > + __u64 hi;
> > > +#endif
> > > +};
> >
> > Hm, I know why you do this custom fsinfo_u128 thingy but for userspace
> > that is going to be annoying to operate with, e.g. comparing the
> > size/space of two filesystems etc.
>
> We don't have a __u128 in the UAPI, and I'm reluctant to use __uint128_t.
>
> Do you have a better suggestion?
>
> > > +struct fsinfo_ids {
> > > + char f_fs_name[15 + 1]; /* Filesystem name */
> >
> > You should probably make this a macro so userspace can use it in fs-name
> > length checks too.
>
> The name length, you mean? Well, you can use sizeof...
>
> > > + FSINFO_CAP__NR
> >
> > Hm, again, maybe better to use FSINFO_CAP_MAX?
>
> It's not a limit.
Well, in both cases it's giving the limit of currently supported
attributes. Other places in the kernel do the same (netlink for
example). Anyway, it probably doesn't matter that much.
Christian
Christian Brauner <[email protected]> wrote:
> > + ret = mutex_lock_interruptible(&fc->uapi_mutex);
> > + if (ret == 0) {
> > + ret = -EIO;
>
> Why EIO when there's no root dentry?
Because I don't want to use ENODATA/EBADF and preferably not EINVAL and
because the context you're accessing isn't in the correct state for you to be
able to do that. How about EBADFD ("File descriptor in bad state")?
David
On Mon, Jun 24, 2019 at 03:08:45PM +0100, David Howells wrote:
>
> Hi Al,
>
> Here are a set of patches that adds a syscall, fsinfo(), that allows
> attributes of a filesystem/superblock to be queried. Attribute values are
> of four basic types:
>
> (1) Version dependent-length structure (size defined by type).
>
> (2) Variable-length string (up to PAGE_SIZE).
>
> (3) Array of fixed-length structures (up to INT_MAX size).
>
> (4) Opaque blob (up to INT_MAX size).
>
> Attributes can have multiple values in up to two dimensions and all the
> values of a particular attribute must have the same type.
>
> Note that the attribute values *are* allowed to vary between dentries
> within a single superblock, depending on the specific dentry that you're
> looking at.
>
> I've tried to make the interface as light as possible, so integer/enum
> attribute selector rather than string and the core does all the allocation
> and extensibility support work rather than leaving that to the filesystems.
> That means that for the first two attribute types, sb->s_op->fsinfo() may
> assume that the provided buffer is always present and always big enough.
>
> Further, this removes the possibility of the filesystem gaining access to the
> userspace buffer.
>
>
> fsinfo() allows a variety of information to be retrieved about a filesystem
> and the mount topology:
>
> (1) General superblock attributes:
>
> - The amount of space/free space in a filesystem (as statfs()).
> - Filesystem identifiers (UUID, volume label, device numbers, ...)
> - The limits on a filesystem's capabilities
> - Information on supported statx fields and attributes and IOC flags.
> - A variety single-bit flags indicating supported capabilities.
> - Timestamp resolution and range.
> - Sources (as per mount(2), but fsconfig() allows multiple sources).
> - In-filesystem filename format information.
> - Filesystem parameters ("mount -o xxx"-type things).
> - LSM parameters (again "mount -o xxx"-type things).
>
> (2) Filesystem-specific superblock attributes:
>
> - Server names and addresses.
> - Cell name.
>
> (3) Filesystem configuration metadata attributes:
>
> - Filesystem parameter type descriptions.
> - Name -> parameter mappings.
> - Simple enumeration name -> value mappings.
>
> (4) Mount topology:
>
> - General information about a mount object.
> - Mount device name(s).
> - Children of a mount object and their relative paths.
>
> (5) Information about what the fsinfo() syscall itself supports, including
> the number of attibutes supported and the number of capability bits
> supported.
Phew, this patchset is a lot. It's good of course but can we please cut
some of the more advanced features such as querying by mount id,
submounts etc. pp. for now?
I feel this would help with review and since your interface is
extensible it's really not a big deal if we defer fancy features to
later cycles after people had more time to review and the interface has
seen some exposure.
The mount api changes over the last months have honestly been so huge
that any chance to make the changes smaller and easier to digest we
should take. (I'm really not complaining. Good that the work is done and
it's entirely ok that it's a lot of code.)
It would also be great if after you have dropped some stuff from this
patchset and gotten an Ack we could stuff it into linux-next for some
time because it hasn't been so far...
Christian
On Wed, Jun 26, 2019 at 11:02:59AM +0100, David Howells wrote:
> Christian Brauner <[email protected]> wrote:
>
> > > + ret = mutex_lock_interruptible(&fc->uapi_mutex);
> > > + if (ret == 0) {
> > > + ret = -EIO;
> >
> > Why EIO when there's no root dentry?
>
> Because I don't want to use ENODATA/EBADF and preferably not EINVAL and
> because the context you're accessing isn't in the correct state for you to be
> able to do that. How about EBADFD ("File descriptor in bad state")?
Do we have that? If so that sounds good.
Christian
On Wed, 2019-06-26 at 12:05 +0200, Christian Brauner wrote:
> On Mon, Jun 24, 2019 at 03:08:45PM +0100, David Howells wrote:
> > Hi Al,
> >
> > Here are a set of patches that adds a syscall, fsinfo(), that allows
> > attributes of a filesystem/superblock to be queried. Attribute values are
> > of four basic types:
> >
> > (1) Version dependent-length structure (size defined by type).
> >
> > (2) Variable-length string (up to PAGE_SIZE).
> >
> > (3) Array of fixed-length structures (up to INT_MAX size).
> >
> > (4) Opaque blob (up to INT_MAX size).
> >
> > Attributes can have multiple values in up to two dimensions and all the
> > values of a particular attribute must have the same type.
> >
> > Note that the attribute values *are* allowed to vary between dentries
> > within a single superblock, depending on the specific dentry that you're
> > looking at.
> >
> > I've tried to make the interface as light as possible, so integer/enum
> > attribute selector rather than string and the core does all the allocation
> > and extensibility support work rather than leaving that to the filesystems.
> > That means that for the first two attribute types, sb->s_op->fsinfo() may
> > assume that the provided buffer is always present and always big enough.
> >
> > Further, this removes the possibility of the filesystem gaining access to
> > the
> > userspace buffer.
> >
> >
> > fsinfo() allows a variety of information to be retrieved about a filesystem
> > and the mount topology:
> >
> > (1) General superblock attributes:
> >
> > - The amount of space/free space in a filesystem (as statfs()).
> > - Filesystem identifiers (UUID, volume label, device numbers, ...)
> > - The limits on a filesystem's capabilities
> > - Information on supported statx fields and attributes and IOC flags.
> > - A variety single-bit flags indicating supported capabilities.
> > - Timestamp resolution and range.
> > - Sources (as per mount(2), but fsconfig() allows multiple sources).
> > - In-filesystem filename format information.
> > - Filesystem parameters ("mount -o xxx"-type things).
> > - LSM parameters (again "mount -o xxx"-type things).
> >
> > (2) Filesystem-specific superblock attributes:
> >
> > - Server names and addresses.
> > - Cell name.
> >
> > (3) Filesystem configuration metadata attributes:
> >
> > - Filesystem parameter type descriptions.
> > - Name -> parameter mappings.
> > - Simple enumeration name -> value mappings.
> >
> > (4) Mount topology:
> >
> > - General information about a mount object.
> > - Mount device name(s).
> > - Children of a mount object and their relative paths.
> >
> > (5) Information about what the fsinfo() syscall itself supports, including
> > the number of attibutes supported and the number of capability bits
> > supported.
>
> Phew, this patchset is a lot. It's good of course but can we please cut
> some of the more advanced features such as querying by mount id,
> submounts etc. pp. for now?
Did you mean the "vfs: Allow fsinfo() to look up a mount object by ID"
patch?
We would need to be very careful what was dropped.
For example, I've found that the patch above is pretty much essential
for fsinfo() to be useful from user space.
> I feel this would help with review and since your interface is
> extensible it's really not a big deal if we defer fancy features to
> later cycles after people had more time to review and the interface has
> seen some exposure.
>
> The mount api changes over the last months have honestly been so huge
> that any chance to make the changes smaller and easier to digest we
> should take. (I'm really not complaining. Good that the work is done and
> it's entirely ok that it's a lot of code.)
>
> It would also be great if after you have dropped some stuff from this
> patchset and gotten an Ack we could stuff it into linux-next for some
> time because it hasn't been so far...
>
> Christian
On Wed, Jun 26, 2019 at 06:42:51PM +0800, Ian Kent wrote:
> On Wed, 2019-06-26 at 12:05 +0200, Christian Brauner wrote:
> > On Mon, Jun 24, 2019 at 03:08:45PM +0100, David Howells wrote:
> > > Hi Al,
> > >
> > > Here are a set of patches that adds a syscall, fsinfo(), that allows
> > > attributes of a filesystem/superblock to be queried. Attribute values are
> > > of four basic types:
> > >
> > > (1) Version dependent-length structure (size defined by type).
> > >
> > > (2) Variable-length string (up to PAGE_SIZE).
> > >
> > > (3) Array of fixed-length structures (up to INT_MAX size).
> > >
> > > (4) Opaque blob (up to INT_MAX size).
> > >
> > > Attributes can have multiple values in up to two dimensions and all the
> > > values of a particular attribute must have the same type.
> > >
> > > Note that the attribute values *are* allowed to vary between dentries
> > > within a single superblock, depending on the specific dentry that you're
> > > looking at.
> > >
> > > I've tried to make the interface as light as possible, so integer/enum
> > > attribute selector rather than string and the core does all the allocation
> > > and extensibility support work rather than leaving that to the filesystems.
> > > That means that for the first two attribute types, sb->s_op->fsinfo() may
> > > assume that the provided buffer is always present and always big enough.
> > >
> > > Further, this removes the possibility of the filesystem gaining access to
> > > the
> > > userspace buffer.
> > >
> > >
> > > fsinfo() allows a variety of information to be retrieved about a filesystem
> > > and the mount topology:
> > >
> > > (1) General superblock attributes:
> > >
> > > - The amount of space/free space in a filesystem (as statfs()).
> > > - Filesystem identifiers (UUID, volume label, device numbers, ...)
> > > - The limits on a filesystem's capabilities
> > > - Information on supported statx fields and attributes and IOC flags.
> > > - A variety single-bit flags indicating supported capabilities.
> > > - Timestamp resolution and range.
> > > - Sources (as per mount(2), but fsconfig() allows multiple sources).
> > > - In-filesystem filename format information.
> > > - Filesystem parameters ("mount -o xxx"-type things).
> > > - LSM parameters (again "mount -o xxx"-type things).
> > >
> > > (2) Filesystem-specific superblock attributes:
> > >
> > > - Server names and addresses.
> > > - Cell name.
> > >
> > > (3) Filesystem configuration metadata attributes:
> > >
> > > - Filesystem parameter type descriptions.
> > > - Name -> parameter mappings.
> > > - Simple enumeration name -> value mappings.
> > >
> > > (4) Mount topology:
> > >
> > > - General information about a mount object.
> > > - Mount device name(s).
> > > - Children of a mount object and their relative paths.
> > >
> > > (5) Information about what the fsinfo() syscall itself supports, including
> > > the number of attibutes supported and the number of capability bits
> > > supported.
> >
> > Phew, this patchset is a lot. It's good of course but can we please cut
> > some of the more advanced features such as querying by mount id,
> > submounts etc. pp. for now?
>
> Did you mean the "vfs: Allow fsinfo() to look up a mount object by ID"
> patch?
>
> We would need to be very careful what was dropped.
Not dropped as in never implement but rather defer it by one merge
window to give us a) more time to review and settle the interface while
b) not stalling the overall patch.
>
> For example, I've found that the patch above is pretty much essential
> for fsinfo() to be useful from user space.
Yeah, but that interface is not clearly defined yet as can be seen from
the commit message and that's what's bothering me most.
On Wed, Jun 26, 2019 at 12:05:25PM +0200, Christian Brauner wrote:
> On Mon, Jun 24, 2019 at 03:08:45PM +0100, David Howells wrote:
> >
> > Hi Al,
> >
> > Here are a set of patches that adds a syscall, fsinfo(), that allows
> > attributes of a filesystem/superblock to be queried. Attribute values are
> > of four basic types:
> >
> > (1) Version dependent-length structure (size defined by type).
> >
> > (2) Variable-length string (up to PAGE_SIZE).
> >
> > (3) Array of fixed-length structures (up to INT_MAX size).
> >
> > (4) Opaque blob (up to INT_MAX size).
> >
> > Attributes can have multiple values in up to two dimensions and all the
> > values of a particular attribute must have the same type.
> >
> > Note that the attribute values *are* allowed to vary between dentries
> > within a single superblock, depending on the specific dentry that you're
> > looking at.
> >
> > I've tried to make the interface as light as possible, so integer/enum
> > attribute selector rather than string and the core does all the allocation
> > and extensibility support work rather than leaving that to the filesystems.
> > That means that for the first two attribute types, sb->s_op->fsinfo() may
> > assume that the provided buffer is always present and always big enough.
> >
> > Further, this removes the possibility of the filesystem gaining access to the
> > userspace buffer.
> >
> >
> > fsinfo() allows a variety of information to be retrieved about a filesystem
> > and the mount topology:
> >
> > (1) General superblock attributes:
> >
> > - The amount of space/free space in a filesystem (as statfs()).
> > - Filesystem identifiers (UUID, volume label, device numbers, ...)
> > - The limits on a filesystem's capabilities
> > - Information on supported statx fields and attributes and IOC flags.
> > - A variety single-bit flags indicating supported capabilities.
> > - Timestamp resolution and range.
> > - Sources (as per mount(2), but fsconfig() allows multiple sources).
> > - In-filesystem filename format information.
> > - Filesystem parameters ("mount -o xxx"-type things).
> > - LSM parameters (again "mount -o xxx"-type things).
> >
> > (2) Filesystem-specific superblock attributes:
> >
> > - Server names and addresses.
> > - Cell name.
> >
> > (3) Filesystem configuration metadata attributes:
> >
> > - Filesystem parameter type descriptions.
> > - Name -> parameter mappings.
> > - Simple enumeration name -> value mappings.
> >
> > (4) Mount topology:
> >
> > - General information about a mount object.
> > - Mount device name(s).
> > - Children of a mount object and their relative paths.
> >
> > (5) Information about what the fsinfo() syscall itself supports, including
> > the number of attibutes supported and the number of capability bits
> > supported.
>
> Phew, this patchset is a lot. It's good of course but can we please cut
> some of the more advanced features such as querying by mount id,
> submounts etc. pp. for now?
> I feel this would help with review and since your interface is
> extensible it's really not a big deal if we defer fancy features to
> later cycles after people had more time to review and the interface has
> seen some exposure.
>
> The mount api changes over the last months have honestly been so huge
> that any chance to make the changes smaller and easier to digest we
> should take. (I'm really not complaining. Good that the work is done and
> it's entirely ok that it's a lot of code.)
>
> It would also be great if after you have dropped some stuff from this
> patchset and gotten an Ack we could stuff it into linux-next for some
> time because it hasn't been so far...
And I also very much recommend to remove any potential cross-dependency
between the fsinfo() and the notification patchset.
Ideally, I'd like to see fsinfo() to be completely independent to not
block it on something way more controversial.
Furthermore, I can't possibly keep the context of another huge patchset
not yet merged in the back of my mind while reviewing this patchset. :)
Christian
Christian Brauner <[email protected]> wrote:
> And I also very much recommend to remove any potential cross-dependency
> between the fsinfo() and the notification patchset.
The problem with that is that to make the notification patchset useful for
mount notifications, you need some information that you would obtain through
fsinfo().
David
On Wed, Jun 26, 2019 at 03:31:37PM +0100, David Howells wrote:
> Christian Brauner <[email protected]> wrote:
>
> > And I also very much recommend to remove any potential cross-dependency
> > between the fsinfo() and the notification patchset.
>
> The problem with that is that to make the notification patchset useful for
> mount notifications, you need some information that you would obtain through
> fsinfo().
But would it really be that bad if you'd just land fsinfo() and then
focus on the notification stuff. This very much rather looks like a
timing issue than a conceptual one, i.e. you could very much just push
fsinfo() and leave the notification stuff alone until that is done.
Once fsinfo() has landed you can then go on to put additional bits you
need from or for fsinfo() for the notification patchset in there. Seems
you have at least sketched both APIs sufficiently that you know what you
need to look out for to not cause any regressions later on when you need
to expand them.
Christian
On Wed, 2019-06-26 at 12:47 +0200, Christian Brauner wrote:
> On Wed, Jun 26, 2019 at 06:42:51PM +0800, Ian Kent wrote:
> > On Wed, 2019-06-26 at 12:05 +0200, Christian Brauner wrote:
> > > On Mon, Jun 24, 2019 at 03:08:45PM +0100, David Howells wrote:
> > > > Hi Al,
> > > >
> > > > Here are a set of patches that adds a syscall, fsinfo(), that allows
> > > > attributes of a filesystem/superblock to be queried. Attribute values
> > > > are
> > > > of four basic types:
> > > >
> > > > (1) Version dependent-length structure (size defined by type).
> > > >
> > > > (2) Variable-length string (up to PAGE_SIZE).
> > > >
> > > > (3) Array of fixed-length structures (up to INT_MAX size).
> > > >
> > > > (4) Opaque blob (up to INT_MAX size).
> > > >
> > > > Attributes can have multiple values in up to two dimensions and all the
> > > > values of a particular attribute must have the same type.
> > > >
> > > > Note that the attribute values *are* allowed to vary between dentries
> > > > within a single superblock, depending on the specific dentry that you're
> > > > looking at.
> > > >
> > > > I've tried to make the interface as light as possible, so integer/enum
> > > > attribute selector rather than string and the core does all the
> > > > allocation
> > > > and extensibility support work rather than leaving that to the
> > > > filesystems.
> > > > That means that for the first two attribute types, sb->s_op->fsinfo()
> > > > may
> > > > assume that the provided buffer is always present and always big enough.
> > > >
> > > > Further, this removes the possibility of the filesystem gaining access
> > > > to
> > > > the
> > > > userspace buffer.
> > > >
> > > >
> > > > fsinfo() allows a variety of information to be retrieved about a
> > > > filesystem
> > > > and the mount topology:
> > > >
> > > > (1) General superblock attributes:
> > > >
> > > > - The amount of space/free space in a filesystem (as statfs()).
> > > > - Filesystem identifiers (UUID, volume label, device numbers, ...)
> > > > - The limits on a filesystem's capabilities
> > > > - Information on supported statx fields and attributes and IOC
> > > > flags.
> > > > - A variety single-bit flags indicating supported capabilities.
> > > > - Timestamp resolution and range.
> > > > - Sources (as per mount(2), but fsconfig() allows multiple
> > > > sources).
> > > > - In-filesystem filename format information.
> > > > - Filesystem parameters ("mount -o xxx"-type things).
> > > > - LSM parameters (again "mount -o xxx"-type things).
> > > >
> > > > (2) Filesystem-specific superblock attributes:
> > > >
> > > > - Server names and addresses.
> > > > - Cell name.
> > > >
> > > > (3) Filesystem configuration metadata attributes:
> > > >
> > > > - Filesystem parameter type descriptions.
> > > > - Name -> parameter mappings.
> > > > - Simple enumeration name -> value mappings.
> > > >
> > > > (4) Mount topology:
> > > >
> > > > - General information about a mount object.
> > > > - Mount device name(s).
> > > > - Children of a mount object and their relative paths.
> > > >
> > > > (5) Information about what the fsinfo() syscall itself supports,
> > > > including
> > > > the number of attibutes supported and the number of capability bits
> > > > supported.
> > >
> > > Phew, this patchset is a lot. It's good of course but can we please cut
> > > some of the more advanced features such as querying by mount id,
> > > submounts etc. pp. for now?
> >
> > Did you mean the "vfs: Allow fsinfo() to look up a mount object by ID"
> > patch?
> >
> > We would need to be very careful what was dropped.
>
> Not dropped as in never implement but rather defer it by one merge
> window to give us a) more time to review and settle the interface while
> b) not stalling the overall patch.
Sure, and I'm not saying something like what you recommend shouldn't
be done.
I'm working on user space mount table improvements that I want to
get done ahead of the merge.
Well, I would be but there's still mount-api conversions that need
to be done so that fsinfo() patches don't end up with endless merge
conflicts. The fsinfo() super block method will result in changes
in the same area as the mount-api changes.
The mount-api changes are proving to be a bit of a challenge.
Anyway, the plan is to use the mount table handling improvements to
try and
locate bugs and missing or not quite right functionality.
>
> > For example, I've found that the patch above is pretty much essential
> > for fsinfo() to be useful from user space.
>
> Yeah, but that interface is not clearly defined yet as can be seen from
> the commit message and that's what's bothering me most.
Yeah, but updating my cloned branch hasn't been difficult.
There's a certain amount of functionality that I'd like to see
retained for when I get back to the user space development.
Using the notifications changes are something I'm not likely
to get to for quite some time so breaking those out into a
separate branch (like they were not so long ago) would be
more sensible IMHO.
There may be some other bits that David can identify too.
Ian