Gone over this issue once again, with a deeper understanding of what's
actually needed and updated the patches.
And I think these patches clearly fix the requirement of the customer:
autofs4 can be started in a "container" and it will be able to serve
mounts in that container.
If second patch makes sure that triggers from unrelated pid namespaces
are not honoured (because they can't be honoured properly).
Untested, for review only at this point.
Thanks,
Miklos
----
From: Sukadev Bhattiprolu <[email protected]>
This patch enables autofs4 to work in a "container". oz_pgrp is converted from
pid_t to struct pid and this is stored at mount time based on the "pgrp=" option
or if the option is missing then the current pgrp.
The "pgrp=" option is interpreted in the PID namespace of the current process.
This option is flawed in that it doesn't carry the namespace information, so it
should be deprecated. AFAICS the autofs daemon always sends the current pgrp,
which is the default anyway.
The oz_pgrp is also set from the AUTOFS_DEV_IOCTL_SETPIPEFD_CMD ioctl. This
ioctl sets oz_pgrp to the current pgrp. It is not allowed to change the pid
namespace.
oz_pgrp is used mainly to determine whether the process traversing the autofs
mount tree is the autofs daemon itself or not. This function now compares the
pid pointers instead of the pid_t values.
One other use of oz_pgrp is in autofs4_show_options. There is shows the
virtual pid number (i.e. the one that is valid inside the PID namespace of the
calling process)
For debugging printk convert oz_pgrp to the value in the initial pid namespace.
Signed-off-by: Sukadev Bhattiprolu <[email protected]>
Cc: Serge Hallyn <[email protected]>
Cc: Eric Biederman <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>
---
fs/autofs4/autofs_i.h | 4 ++--
fs/autofs4/dev-ioctl.c | 16 ++++++++++++++--
fs/autofs4/inode.c | 33 +++++++++++++++++++++++++--------
3 files changed, 41 insertions(+), 12 deletions(-)
Index: linux-2.6/fs/autofs4/autofs_i.h
===================================================================
--- linux-2.6.orig/fs/autofs4/autofs_i.h 2012-11-12 17:55:28.000000000 +0100
+++ linux-2.6/fs/autofs4/autofs_i.h 2012-11-12 19:09:40.000000000 +0100
@@ -104,7 +104,7 @@ struct autofs_sb_info {
u32 magic;
int pipefd;
struct file *pipe;
- pid_t oz_pgrp;
+ struct pid *oz_pgrp;
int catatonic;
int version;
int sub_version;
@@ -139,7 +139,7 @@ static inline struct autofs_info *autofs
filesystem without "magic".) */
static inline int autofs4_oz_mode(struct autofs_sb_info *sbi) {
- return sbi->catatonic || task_pgrp_nr(current) == sbi->oz_pgrp;
+ return sbi->catatonic || task_pgrp(current) == sbi->oz_pgrp;
}
/* Does a dentry have some pending activity? */
Index: linux-2.6/fs/autofs4/inode.c
===================================================================
--- linux-2.6.orig/fs/autofs4/inode.c 2012-11-12 17:55:28.000000000 +0100
+++ linux-2.6/fs/autofs4/inode.c 2012-11-12 19:09:35.000000000 +0100
@@ -62,6 +62,8 @@ void autofs4_kill_sb(struct super_block
/* Free wait queues, close pipe */
autofs4_catatonic_mode(sbi);
+ put_pid(sbi->oz_pgrp);
+
sb->s_fs_info = NULL;
kfree(sbi);
@@ -83,7 +85,7 @@ static int autofs4_show_options(struct s
seq_printf(m, ",uid=%u", root_inode->i_uid);
if (root_inode->i_gid != 0)
seq_printf(m, ",gid=%u", root_inode->i_gid);
- seq_printf(m, ",pgrp=%d", sbi->oz_pgrp);
+ seq_printf(m, ",pgrp=%d", pid_vnr(sbi->oz_pgrp));
seq_printf(m, ",timeout=%lu", sbi->exp_timeout/HZ);
seq_printf(m, ",minproto=%d", sbi->min_proto);
seq_printf(m, ",maxproto=%d", sbi->max_proto);
@@ -127,7 +129,8 @@ static const match_table_t tokens = {
};
static int parse_options(char *options, int *pipefd, uid_t *uid, gid_t *gid,
- pid_t *pgrp, unsigned int *type, int *minproto, int *maxproto)
+ int *pgrp, bool *pgrp_set, unsigned int *type,
+ int *minproto, int *maxproto)
{
char *p;
substring_t args[MAX_OPT_ARGS];
@@ -135,7 +138,6 @@ static int parse_options(char *options,
*uid = current_uid();
*gid = current_gid();
- *pgrp = task_pgrp_nr(current);
*minproto = AUTOFS_MIN_PROTO_VERSION;
*maxproto = AUTOFS_MAX_PROTO_VERSION;
@@ -170,6 +172,7 @@ static int parse_options(char *options,
if (match_int(args, &option))
return 1;
*pgrp = option;
+ *pgrp_set = true;
break;
case Opt_minproto:
if (match_int(args, &option))
@@ -205,6 +208,8 @@ int autofs4_fill_super(struct super_bloc
int pipefd;
struct autofs_sb_info *sbi;
struct autofs_info *ino;
+ int pgrp;
+ bool pgrp_set = false;
sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
if (!sbi)
@@ -217,7 +222,7 @@ int autofs4_fill_super(struct super_bloc
sbi->pipe = NULL;
sbi->catatonic = 1;
sbi->exp_timeout = 0;
- sbi->oz_pgrp = task_pgrp_nr(current);
+ sbi->oz_pgrp = NULL;
sbi->sb = s;
sbi->version = 0;
sbi->sub_version = 0;
@@ -254,12 +259,23 @@ int autofs4_fill_super(struct super_bloc
/* Can this call block? */
if (parse_options(data, &pipefd, &root_inode->i_uid, &root_inode->i_gid,
- &sbi->oz_pgrp, &sbi->type, &sbi->min_proto,
- &sbi->max_proto)) {
+ &pgrp, &pgrp_set, &sbi->type, &sbi->min_proto,
+ &sbi->max_proto)) {
printk("autofs: called with bogus options\n");
goto fail_dput;
}
+ if (pgrp_set) {
+ sbi->oz_pgrp = find_get_pid(pgrp);
+ if (!sbi->oz_pgrp) {
+ pr_warn("autofs: could not find process group %d\n",
+ pgrp);
+ goto fail_dput;
+ }
+ } else {
+ sbi->oz_pgrp = get_task_pid(current, PIDTYPE_PGID);
+ }
+
if (autofs_type_trigger(sbi->type))
__managed_dentry_set_managed(root);
@@ -283,9 +299,9 @@ int autofs4_fill_super(struct super_bloc
sbi->version = sbi->max_proto;
sbi->sub_version = AUTOFS_PROTO_SUBVERSION;
- DPRINTK("pipe fd = %d, pgrp = %u", pipefd, sbi->oz_pgrp);
+ DPRINTK("pipe fd = %d, pgrp = %u", pipefd, pid_nr(sbi->oz_pgrp));
pipe = fget(pipefd);
-
+
if (!pipe) {
printk("autofs: could not open pipe file descriptor\n");
goto fail_dput;
@@ -315,6 +331,7 @@ int autofs4_fill_super(struct super_bloc
fail_ino:
kfree(ino);
fail_free:
+ put_pid(sbi->oz_pgrp);
kfree(sbi);
s->s_fs_info = NULL;
fail_unlock:
Index: linux-2.6/fs/autofs4/dev-ioctl.c
===================================================================
--- linux-2.6.orig/fs/autofs4/dev-ioctl.c 2012-11-12 17:55:28.000000000 +0100
+++ linux-2.6/fs/autofs4/dev-ioctl.c 2012-11-12 20:41:26.000000000 +0100
@@ -346,6 +346,7 @@ static int autofs_dev_ioctl_setpipefd(st
{
int pipefd;
int err = 0;
+ struct pid *new_pid = NULL;
if (param->setpipefd.pipefd == -1)
return -EINVAL;
@@ -357,7 +358,17 @@ static int autofs_dev_ioctl_setpipefd(st
mutex_unlock(&sbi->wq_mutex);
return -EBUSY;
} else {
- struct file *pipe = fget(pipefd);
+ struct file *pipe;
+
+ new_pid = get_task_pid(current, PIDTYPE_PGID);
+
+ if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
+ AUTOFS_WARN("Not allowed to change PID namespace");
+ err = -EINVAL;
+ goto out;
+ }
+
+ pipe = fget(pipefd);
if (!pipe) {
err = -EBADF;
goto out;
@@ -367,12 +378,13 @@ static int autofs_dev_ioctl_setpipefd(st
fput(pipe);
goto out;
}
- sbi->oz_pgrp = task_pgrp_nr(current);
+ swap(sbi->oz_pgrp, new_pid);
sbi->pipefd = pipefd;
sbi->pipe = pipe;
sbi->catatonic = 0;
}
out:
+ put_pid(new_pid);
mutex_unlock(&sbi->wq_mutex);
return err;
}
From: Miklos Szeredi <[email protected]>
The PID and the TGID of the process tringgering the mount are sent to the
daemon. Currently the global pid values are sent (ones valid in the initial pid
namespace) but this is wrong if the autofs daemon itself is not running in the
initial pid namespace.
So send the pid values that are valid in the namespace of the autofs daemon.
The namespace to use is taken from the oz_pgrp pid pointer, which was set at
mount time to the mounting process' pid namespace.
If the pid translation fails (the triggering process is in an unrelated pid
namespace) then the automount fails with ENOENT.
Cc: Serge E. Hallyn <[email protected]>
Cc: Eric Biederman <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>
---
fs/autofs4/waitq.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
03944aae0b9cb4a36d091f275d2f2217447b27ec
Index: linux-2.6/fs/autofs4/waitq.c
===================================================================
--- linux-2.6.orig/fs/autofs4/waitq.c 2012-11-12 19:07:06.000000000 +0100
+++ linux-2.6/fs/autofs4/waitq.c 2012-11-12 19:57:10.000000000 +0100
@@ -354,11 +354,23 @@ int autofs4_wait(struct autofs_sb_info *
struct qstr qstr;
char *name;
int status, ret, type;
+ pid_t pid;
+ pid_t tgid;
/* In catatonic mode, we don't wait for nobody */
if (sbi->catatonic)
return -ENOENT;
+ /*
+ * Try translating pids to the namespace of the daemon.
+ *
+ * Zero means failure: we are in an unrelated pid namespace.
+ */
+ pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
+ tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
+ if (pid == 0 || tgid == 0)
+ return -ENOENT;
+
if (!dentry->d_inode) {
/*
* A wait for a negative dentry is invalid for certain
@@ -424,8 +436,8 @@ int autofs4_wait(struct autofs_sb_info *
wq->ino = autofs4_get_ino(sbi);
wq->uid = current_uid();
wq->gid = current_gid();
- wq->pid = current->pid;
- wq->tgid = current->tgid;
+ wq->pid = pid;
+ wq->tgid = tgid;
wq->status = -EINTR; /* Status return if interrupted */
wq->wait_ctr = 2;
mutex_unlock(&sbi->wq_mutex);