LinuxLists.cc - [PATCH v2 0/3] Checkpoint Support for Syscall User Dispatch

2023-01-18 20:24:50

Subject: [PATCH v2 0/3] Checkpoint Support for Syscall User Dispatch

v2: Implements the getter/setter interface in ptrace rather than prctl

Syscall user dispatch makes it possible to cleanly intercept system
calls from user-land. However, most transparent checkpoint software
presently leverages some combination of ptrace and system call
injection to place software in a ready-to-checkpoint state.

If Syscall User Dispatch is enabled at the time of being quiesced,
injected system calls will subsequently be interposed upon and
dispatched to the task's signal handler.

This patch set implements 3 features to enable software such as CRIU
to cleanly interpose upon software leveraging syscall user dispatch.

- Implement PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH, akin to a similar
feature for SECCOMP. This allows a ptracer to temporarily disable
syscall user dispatch, making syscall injection possible.

- Implement an fs/proc extension that reports whether Syscall User
Dispatch is being used in proc/status. A similar value is present
for SECCOMP, and is used to determine whether special logic is
needed during checkpoint/resume.

- Implement a getter interface for Syscall User Dispatch config info.
To resume successfully, the checkpoint/resume software has to
save and restore this information. Presently this configuration
is write-only, with no way for C/R software to save it.
This was done in ptrace because syscall user dispatch is not part of
uapi. The syscall_user_dispatch_config structure was added to the
ptrace exports.

Signed-off-by: Gregory Price <[email protected]>

Gregory Price (3):
ptrace,syscall_user_dispatch: Implement Syscall User Dispatch
Suspension
fs/proc/array: Add Syscall User Dispatch to proc status
ptrace,syscall_user_dispatch: add a getter/setter for sud
configuration

.../admin-guide/syscall-user-dispatch.rst | 5 +-
fs/proc/array.c | 8 +++
include/linux/ptrace.h | 2 +
include/linux/syscall_user_dispatch.h | 19 +++++++
include/uapi/linux/ptrace.h | 16 +++++-
kernel/entry/syscall_user_dispatch.c | 54 +++++++++++++++++++
kernel/ptrace.c | 14 +++++
7 files changed, 116 insertions(+), 2 deletions(-)

--
2.39.0

2023-01-18 20:25:09

by Gregory Price

[permalink] [raw]

Subject: [PATCH 1/3] ptrace,syscall_user_dispatch: Implement Syscall User Dispatch Suspension

Adds PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH to ptrace options, and
modify Syscall User Dispatch to suspend interception when enabled.

This is modeled after the SUSPEND_SECCOMP feature, which suspends
SECCOMP interposition. Without doing this, software like CRIU will
inject system calls into a process and be intercepted by Syscall
User Dispatch, either causing a crash (due to blocked signals) or
the delivery of those signals to a ptracer (not the intended behavior).

Since Syscall User Dispatch is not a privileged feature, a check
for permissions is not required, however attempting to set this
option when CONFIG_CHECKPOINT_RESTORE it not supported should be
disallowed, as its intended use is checkpoint/resume.

Signed-off-by: Gregory Price <[email protected]>
---
include/linux/ptrace.h | 2 ++
include/uapi/linux/ptrace.h | 6 +++++-
kernel/entry/syscall_user_dispatch.c | 5 +++++
kernel/ptrace.c | 5 +++++
4 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index eaaef3ffec22..461ae5c99d57 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -45,6 +45,8 @@ extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,

#define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
#define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
+#define PT_SUSPEND_SYSCALL_USER_DISPATCH \
+ (PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH << PT_OPT_FLAG_SHIFT)

extern long arch_ptrace(struct task_struct *child, long request,
unsigned long addr, unsigned long data);
diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
index 195ae64a8c87..ba9e3f19a22c 100644
--- a/include/uapi/linux/ptrace.h
+++ b/include/uapi/linux/ptrace.h
@@ -146,9 +146,13 @@ struct ptrace_rseq_configuration {
/* eventless options */
#define PTRACE_O_EXITKILL (1 << 20)
#define PTRACE_O_SUSPEND_SECCOMP (1 << 21)
+#define PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH (1 << 22)

#define PTRACE_O_MASK (\
- 0x000000ff | PTRACE_O_EXITKILL | PTRACE_O_SUSPEND_SECCOMP)
+ 0x000000ff | \
+ PTRACE_O_EXITKILL | \
+ PTRACE_O_SUSPEND_SECCOMP | \
+ PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH)

#include <asm/ptrace.h>

diff --git a/kernel/entry/syscall_user_dispatch.c b/kernel/entry/syscall_user_dispatch.c
index 0b6379adff6b..7607f4598dd8 100644
--- a/kernel/entry/syscall_user_dispatch.c
+++ b/kernel/entry/syscall_user_dispatch.c
@@ -8,6 +8,7 @@
#include <linux/uaccess.h>
#include <linux/signal.h>
#include <linux/elf.h>
+#include <linux/ptrace.h>

#include <linux/sched/signal.h>
#include <linux/sched/task_stack.h>
@@ -36,6 +37,10 @@ bool syscall_user_dispatch(struct pt_regs *regs)
struct syscall_user_dispatch *sd = &current->syscall_dispatch;
char state;

+ if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
+ unlikely(current->ptrace & PT_SUSPEND_SYSCALL_USER_DISPATCH))
+ return false;
+
if (likely(instruction_pointer(regs) - sd->offset < sd->len))
return false;

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 54482193e1ed..a6ad815bd4be 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -370,6 +370,11 @@ static int check_ptrace_options(unsigned long data)
if (data & ~(unsigned long)PTRACE_O_MASK)
return -EINVAL;

+ if (unlikely(data & PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH)) {
+ if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTART))
+ return -EINVAL;
+ }
+
if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) {
if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) ||
!IS_ENABLED(CONFIG_SECCOMP))
--
2.39.0

2023-01-18 20:25:26

by Gregory Price

[permalink] [raw]

Subject: [PATCH 2/3] fs/proc/array: Add Syscall User Dispatch to proc status

If a dispatch selector has been configured for Syscall User Dispatch,
report Syscall User Dispath as configured in proc/status.

This provides an indicator to userland checkpoint/restart software that
it much manage special signal conditions (similar to SECCOMP)

Signed-off-by: Gregory Price <[email protected]>
---
fs/proc/array.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 49283b8103c7..c85cdb4c137c 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -428,6 +428,13 @@ static inline void task_thp_status(struct seq_file *m, struct mm_struct *mm)
seq_printf(m, "THP_enabled:\t%d\n", thp_enabled);
}

+static inline void task_syscall_user_dispatch(struct seq_file *m,
+ struct task_struct *p)
+{
+ seq_put_decimal_ull(m, "\nSyscall_user_dispatch:\t",
+ (p->syscall_dispatch.selector != NULL));
+}
+
int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
@@ -451,6 +458,7 @@ int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
task_cpus_allowed(m, task);
cpuset_task_status_allowed(m, task);
task_context_switch_counts(m, task);
+ task_syscall_user_dispatch(m, task);
return 0;
}

--
2.39.0

2023-01-18 20:25:34

by Gregory Price

[permalink] [raw]

Subject: [PATCH 3/3] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration

This patch implements ptrace getter and setter interface for syscall
syscall user dispatch configuration info.

Presently, these settings are write-only via prctl, making it impossible
to implement transparent checkpoint.

This is modeled after a similar interface for SECCOMP, which can have
its configuration dumped by ptrace for software like CRIU.

Signed-off-by: Gregory Price <[email protected]>
---
.../admin-guide/syscall-user-dispatch.rst | 5 +-
include/linux/syscall_user_dispatch.h | 19 +++++++
include/uapi/linux/ptrace.h | 10 ++++
kernel/entry/syscall_user_dispatch.c | 49 +++++++++++++++++++
kernel/ptrace.c | 9 ++++
5 files changed, 91 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/syscall-user-dispatch.rst b/Documentation/admin-guide/syscall-user-dispatch.rst
index 60314953c728..a23ae21a1d5b 100644
--- a/Documentation/admin-guide/syscall-user-dispatch.rst
+++ b/Documentation/admin-guide/syscall-user-dispatch.rst
@@ -43,7 +43,10 @@ doesn't rely on any of the syscall ABI to make the filtering. It uses
only the syscall dispatcher address and the userspace key.

As the ABI of these intercepted syscalls is unknown to Linux, these
-syscalls are not instrumentable via ptrace or the syscall tracepoints.
+syscalls are not instrumentable via ptrace or the syscall tracepoints,
+however an interfaces to suspend, checkpoint, and restore syscall user
+dispatch configuration has been added to ptrace to assist userland
+checkpoint/restart software.

Interface
---------
diff --git a/include/linux/syscall_user_dispatch.h b/include/linux/syscall_user_dispatch.h
index a0ae443fb7df..dbf384b7a26e 100644
--- a/include/linux/syscall_user_dispatch.h
+++ b/include/linux/syscall_user_dispatch.h
@@ -22,6 +22,13 @@ int set_syscall_user_dispatch(unsigned long mode, unsigned long offset,
#define clear_syscall_work_syscall_user_dispatch(tsk) \
clear_task_syscall_work(tsk, SYSCALL_USER_DISPATCH)

+int syscall_user_dispatch_get_config(struct task_struct *task, unsigned long size,
+ void __user *data);
+
+int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long size,
+ void __user *data);
+
+
#else
struct syscall_user_dispatch {};

@@ -35,6 +42,18 @@ static inline void clear_syscall_work_syscall_user_dispatch(struct task_struct *
{
}

+int syscall_user_dispatch_get_config(struct task_struct *task, unsigned long size,
+ void __user *data)
+{
+ return -EINVAL;
+}
+
+int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long size,
+ void __user *data)
+{
+ return -EINVAL;
+}
+
#endif /* CONFIG_GENERIC_ENTRY */

#endif /* _SYSCALL_USER_DISPATCH_H */
diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
index ba9e3f19a22c..8b93c78189b5 100644
--- a/include/uapi/linux/ptrace.h
+++ b/include/uapi/linux/ptrace.h
@@ -112,6 +112,16 @@ struct ptrace_rseq_configuration {
__u32 pad;
};

+#define PTRACE_SET_SYSCALL_USER_DISPATCH_CONFIG 0x4210
+#define PTRACE_GET_SYSCALL_USER_DISPATCH_CONFIG 0x4211
+struct syscall_user_dispatch_config {
+ __u64 mode;
+ __s8 *selector;
+ __u64 offset;
+ __u64 len;
+ __u8 on_dispatch;
+};
+
/*
* These values are stored in task->ptrace_message
* by ptrace_stop to describe the current syscall-stop.
diff --git a/kernel/entry/syscall_user_dispatch.c b/kernel/entry/syscall_user_dispatch.c
index 7607f4598dd8..ae4f9a4b96ac 100644
--- a/kernel/entry/syscall_user_dispatch.c
+++ b/kernel/entry/syscall_user_dispatch.c
@@ -111,3 +111,52 @@ int set_syscall_user_dispatch(unsigned long mode, unsigned long offset,

return 0;
}
+
+int syscall_user_dispatch_get_config(struct task_struct *task, unsigned long size,
+ void __user *data)
+{
+ struct syscall_user_dispatch *sd = &task->syscall_dispatch;
+ struct syscall_user_dispatch_config config;
+
+ if (size != sizeof(struct syscall_user_dispatch_config))
+ return -EINVAL;
+
+ if (sd->selector) {
+ config.mode = PR_SYS_DISPATCH_ON;
+ config.offset = sd->offset;
+ config.len = sd->len;
+ config.selector = sd->selector;
+ config.on_dispatch = sd->on_dispatch;
+ } else {
+ config.mode = PR_SYS_DISPATCH_OFF;
+ config.offset = 0;
+ config.len = 0;
+ config.selector = NULL;
+ config.on_dispatch = false;
+ }
+ if (copy_to_user(data, &config, sizeof(config)))
+ return -EFAULT;
+
+ return 0;
+}
+
+int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long size,
+ void __user *data)
+{
+ struct syscall_user_dispatch_config config;
+ int ret;
+
+ if (size != sizeof(struct syscall_user_dispatch_config))
+ return -EINVAL;
+
+ if (copy_from_user(&config, data, sizeof(config)))
+ return -EFAULT;
+
+ ret = set_syscall_user_dispatch(config.mode, config.offset, config.len,
+ config.selector);
+ if (ret)
+ return ret;
+
+ task->syscall_dispatch.on_dispatch = config.on_dispatch;
+ return 0;
+}
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index a6ad815bd4be..0b210a1450e7 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -32,6 +32,7 @@
#include <linux/compat.h>
#include <linux/sched/signal.h>
#include <linux/minmax.h>
+#include <linux/syscall_user_dispatch.h>

#include <asm/syscall.h> /* for syscall_get_* */

@@ -1264,6 +1265,14 @@ int ptrace_request(struct task_struct *child, long request,
break;
#endif

+ case PTRACE_SET_SYSCALL_USER_DISPATCH_CONFIG:
+ ret = syscall_user_dispatch_set_config(child, addr, datavp);
+ break;
+
+ case PTRACE_GET_SYSCALL_USER_DISPATCH_CONFIG:
+ ret = syscall_user_dispatch_get_config(child, addr, datavp);
+ break;
+
default:
break;
}
--
2.39.0

2023-01-18 23:53:18

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH 3/3] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration

Hi Gregory,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.2-rc4 next-20230118]
[cannot apply to tip/core/entry]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Gregory-Price/ptrace-syscall_user_dispatch-Implement-Syscall-User-Dispatch-Suspension/20230119-041259
patch link: https://lore.kernel.org/r/20230118201055.147228-4-gregory.price%40memverge.com
patch subject: [PATCH 3/3] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration
config: m68k-allyesconfig (https://download.01.org/0day-ci/archive/20230119/[email protected]/config)
compiler: m68k-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/intel-lab-lkp/linux/commit/bd6833b41ed48c444c09346f695efe229deec2e9
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Gregory-Price/ptrace-syscall_user_dispatch-Implement-Syscall-User-Dispatch-Suspension/20230119-041259
git checkout bd6833b41ed48c444c09346f695efe229deec2e9
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k olddefconfig
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k prepare

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>

All warnings (new ones prefixed by >>):

In file included from include/linux/sched.h:31,
from arch/m68k/kernel/asm-offsets.c:15:
>> include/linux/syscall_user_dispatch.h:45:5: warning: no previous prototype for 'syscall_user_dispatch_get_config' [-Wmissing-prototypes]
45 | int syscall_user_dispatch_get_config(struct task_struct *task, unsigned long size,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> include/linux/syscall_user_dispatch.h:51:5: warning: no previous prototype for 'syscall_user_dispatch_set_config' [-Wmissing-prototypes]
51 | int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long size,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
scripts/genksyms/parse.y: warning: 9 shift/reduce conflicts [-Wconflicts-sr]
scripts/genksyms/parse.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
scripts/genksyms/parse.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
In file included from include/linux/sched.h:31,
from arch/m68k/kernel/asm-offsets.c:15:
>> include/linux/syscall_user_dispatch.h:45:5: warning: no previous prototype for 'syscall_user_dispatch_get_config' [-Wmissing-prototypes]
45 | int syscall_user_dispatch_get_config(struct task_struct *task, unsigned long size,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> include/linux/syscall_user_dispatch.h:51:5: warning: no previous prototype for 'syscall_user_dispatch_set_config' [-Wmissing-prototypes]
51 | int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long size,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

vim +/syscall_user_dispatch_get_config +45 include/linux/syscall_user_dispatch.h

44
> 45 int syscall_user_dispatch_get_config(struct task_struct *task, unsigned long size,
46 void __user *data)
47 {
48 return -EINVAL;
49 }
50
> 51 int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long size,
52 void __user *data)
53 {
54 return -EINVAL;
55 }
56

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

2023-01-19 01:29:22

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH 3/3] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration

2023-01-19 01:49:23

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH 3/3] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration

Hi Gregory,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.2-rc4 next-20230118]
[cannot apply to tip/core/entry]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Gregory-Price/ptrace-syscall_user_dispatch-Implement-Syscall-User-Dispatch-Suspension/20230119-041259
patch link: https://lore.kernel.org/r/20230118201055.147228-4-gregory.price%40memverge.com
patch subject: [PATCH 3/3] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration
config: um-i386_defconfig (https://download.01.org/0day-ci/archive/20230119/[email protected]/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce (this is a W=1 build):
# https://github.com/intel-lab-lkp/linux/commit/bd6833b41ed48c444c09346f695efe229deec2e9
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Gregory-Price/ptrace-syscall_user_dispatch-Implement-Syscall-User-Dispatch-Suspension/20230119-041259
git checkout bd6833b41ed48c444c09346f695efe229deec2e9
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 O=build_dir ARCH=um SUBARCH=i386 olddefconfig
make W=1 O=build_dir ARCH=um SUBARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>

All errors (new ones prefixed by >>):

ld: fs/isofs/inode.o: in function `syscall_user_dispatch_get_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_get_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/isofs/inode.o: in function `syscall_user_dispatch_set_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_set_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/isofs/dir.o: in function `syscall_user_dispatch_get_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_get_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/isofs/dir.o: in function `syscall_user_dispatch_set_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_set_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/isofs/util.o: in function `syscall_user_dispatch_get_config':
fs/isofs/util.c:49: multiple definition of `syscall_user_dispatch_get_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/isofs/util.o: in function `syscall_user_dispatch_set_config':
fs/isofs/util.c:49: multiple definition of `syscall_user_dispatch_set_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/isofs/rock.o: in function `syscall_user_dispatch_get_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_get_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/isofs/rock.o: in function `syscall_user_dispatch_set_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_set_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/isofs/export.o: in function `syscall_user_dispatch_get_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_get_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/isofs/export.o: in function `syscall_user_dispatch_set_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_set_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/isofs/joliet.o: in function `syscall_user_dispatch_get_config':
fs/isofs/joliet.c:49: multiple definition of `syscall_user_dispatch_get_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/isofs/joliet.o: in function `syscall_user_dispatch_set_config':
fs/isofs/joliet.c:49: multiple definition of `syscall_user_dispatch_set_config'; fs/isofs/namei.o:include/linux/syscall_user_dispatch.h:49: first defined here
--
ld: fs/autofs/inode.o: in function `syscall_user_dispatch_get_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_get_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/autofs/inode.o: in function `syscall_user_dispatch_set_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_set_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/autofs/root.o: in function `syscall_user_dispatch_get_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_get_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/autofs/root.o: in function `syscall_user_dispatch_set_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_set_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/autofs/symlink.o: in function `syscall_user_dispatch_get_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_get_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/autofs/symlink.o: in function `syscall_user_dispatch_set_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_set_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/autofs/waitq.o: in function `syscall_user_dispatch_get_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_get_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/autofs/waitq.o: in function `syscall_user_dispatch_set_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_set_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/autofs/expire.o: in function `syscall_user_dispatch_get_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_get_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/autofs/expire.o: in function `syscall_user_dispatch_set_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_set_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/autofs/dev-ioctl.o: in function `syscall_user_dispatch_get_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_get_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here
ld: fs/autofs/dev-ioctl.o: in function `syscall_user_dispatch_set_config':
>> include/linux/syscall_user_dispatch.h:49: multiple definition of `syscall_user_dispatch_set_config'; fs/autofs/init.o:include/linux/syscall_user_dispatch.h:49: first defined here

vim +49 include/linux/syscall_user_dispatch.h

44
45 int syscall_user_dispatch_get_config(struct task_struct *task, unsigned long size,
46 void __user *data)
47 {
48 return -EINVAL;
> 49 }
50

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

2023-01-19 02:45:01

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH 3/3] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration

Hi Gregory,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.2-rc4 next-20230118]
[cannot apply to tip/core/entry]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Gregory-Price/ptrace-syscall_user_dispatch-Implement-Syscall-User-Dispatch-Suspension/20230119-041259
patch link: https://lore.kernel.org/r/20230118201055.147228-4-gregory.price%40memverge.com
patch subject: [PATCH 3/3] ptrace,syscall_user_dispatch: add a getter/setter for sud configuration
config: x86_64-randconfig-s022 (https://download.01.org/0day-ci/archive/20230119/[email protected]/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce:
# apt-get install sparse
# sparse version: v0.6.4-39-gce1a6720-dirty
# https://github.com/intel-lab-lkp/linux/commit/bd6833b41ed48c444c09346f695efe229deec2e9
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Gregory-Price/ptrace-syscall_user_dispatch-Implement-Syscall-User-Dispatch-Suspension/20230119-041259
git checkout bd6833b41ed48c444c09346f695efe229deec2e9
# save the config file
mkdir build_dir && cp config build_dir/.config
make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=x86_64 olddefconfig
make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=x86_64 SHELL=/bin/bash kernel/entry/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <[email protected]>

sparse warnings: (new ones prefixed by >>)
>> kernel/entry/syscall_user_dispatch.c:128:33: sparse: sparse: incorrect type in assignment (different address spaces) @@ expected signed char [usertype] *[assigned] selector @@ got char [noderef] __user *selector @@
kernel/entry/syscall_user_dispatch.c:128:33: sparse: expected signed char [usertype] *[assigned] selector
kernel/entry/syscall_user_dispatch.c:128:33: sparse: got char [noderef] __user *selector
>> kernel/entry/syscall_user_dispatch.c:156:31: sparse: sparse: incorrect type in argument 4 (different address spaces) @@ expected char [noderef] __user *selector @@ got signed char [usertype] *[addressable] selector @@
kernel/entry/syscall_user_dispatch.c:156:31: sparse: expected char [noderef] __user *selector
kernel/entry/syscall_user_dispatch.c:156:31: sparse: got signed char [usertype] *[addressable] selector

vim +128 kernel/entry/syscall_user_dispatch.c

114
115 int syscall_user_dispatch_get_config(struct task_struct *task, unsigned long size,
116 void __user *data)
117 {
118 struct syscall_user_dispatch *sd = &task->syscall_dispatch;
119 struct syscall_user_dispatch_config config;
120
121 if (size != sizeof(struct syscall_user_dispatch_config))
122 return -EINVAL;
123
124 if (sd->selector) {
125 config.mode = PR_SYS_DISPATCH_ON;
126 config.offset = sd->offset;
127 config.len = sd->len;
> 128 config.selector = sd->selector;
129 config.on_dispatch = sd->on_dispatch;
130 } else {
131 config.mode = PR_SYS_DISPATCH_OFF;
132 config.offset = 0;
133 config.len = 0;
134 config.selector = NULL;
135 config.on_dispatch = false;
136 }
137 if (copy_to_user(data, &config, sizeof(config)))
138 return -EFAULT;
139
140 return 0;
141 }
142
143 int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long size,
144 void __user *data)
145 {
146 struct syscall_user_dispatch_config config;
147 int ret;
148
149 if (size != sizeof(struct syscall_user_dispatch_config))
150 return -EINVAL;
151
152 if (copy_from_user(&config, data, sizeof(config)))
153 return -EFAULT;
154
155 ret = set_syscall_user_dispatch(config.mode, config.offset, config.len,
> 156 config.selector);

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

2023-01-20 10:36:54

by Peter Zijlstra

[permalink] [raw]

Subject: Re: [PATCH 1/3] ptrace,syscall_user_dispatch: Implement Syscall User Dispatch Suspension

On Wed, Jan 18, 2023 at 03:10:53PM -0500, Gregory Price wrote:
> Adds PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH to ptrace options, and
> modify Syscall User Dispatch to suspend interception when enabled.
>
> This is modeled after the SUSPEND_SECCOMP feature, which suspends
> SECCOMP interposition. Without doing this, software like CRIU will
> inject system calls into a process and be intercepted by Syscall
> User Dispatch, either causing a crash (due to blocked signals) or
> the delivery of those signals to a ptracer (not the intended behavior).
>
> Since Syscall User Dispatch is not a privileged feature, a check
> for permissions is not required, however attempting to set this
> option when CONFIG_CHECKPOINT_RESTORE it not supported should be
> disallowed, as its intended use is checkpoint/resume.
>
> Signed-off-by: Gregory Price <[email protected]>

One small nit -- see below, otherwise:

Acked-by: Peter Zijlstra (Intel) <[email protected]>

> ---
> include/linux/ptrace.h | 2 ++
> include/uapi/linux/ptrace.h | 6 +++++-
> kernel/entry/syscall_user_dispatch.c | 5 +++++
> kernel/ptrace.c | 5 +++++
> 4 files changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
> index eaaef3ffec22..461ae5c99d57 100644
> --- a/include/linux/ptrace.h
> +++ b/include/linux/ptrace.h
> @@ -45,6 +45,8 @@ extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
>
> #define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
> #define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
> +#define PT_SUSPEND_SYSCALL_USER_DISPATCH \
> + (PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH << PT_OPT_FLAG_SHIFT)
>
> extern long arch_ptrace(struct task_struct *child, long request,
> unsigned long addr, unsigned long data);
> diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
> index 195ae64a8c87..ba9e3f19a22c 100644
> --- a/include/uapi/linux/ptrace.h
> +++ b/include/uapi/linux/ptrace.h
> @@ -146,9 +146,13 @@ struct ptrace_rseq_configuration {
> /* eventless options */
> #define PTRACE_O_EXITKILL (1 << 20)
> #define PTRACE_O_SUSPEND_SECCOMP (1 << 21)
> +#define PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH (1 << 22)
>
> #define PTRACE_O_MASK (\
> - 0x000000ff | PTRACE_O_EXITKILL | PTRACE_O_SUSPEND_SECCOMP)
> + 0x000000ff | \
> + PTRACE_O_EXITKILL | \
> + PTRACE_O_SUSPEND_SECCOMP | \
> + PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH)
>
> #include <asm/ptrace.h>
>
> diff --git a/kernel/entry/syscall_user_dispatch.c b/kernel/entry/syscall_user_dispatch.c
> index 0b6379adff6b..7607f4598dd8 100644
> --- a/kernel/entry/syscall_user_dispatch.c
> +++ b/kernel/entry/syscall_user_dispatch.c
> @@ -8,6 +8,7 @@
> #include <linux/uaccess.h>
> #include <linux/signal.h>
> #include <linux/elf.h>
> +#include <linux/ptrace.h>
>
> #include <linux/sched/signal.h>
> #include <linux/sched/task_stack.h>
> @@ -36,6 +37,10 @@ bool syscall_user_dispatch(struct pt_regs *regs)
> struct syscall_user_dispatch *sd = &current->syscall_dispatch;
> char state;
>
> + if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
> + unlikely(current->ptrace & PT_SUSPEND_SYSCALL_USER_DISPATCH))

Align with the '(' pleaase.

> + return false;
> +
> if (likely(instruction_pointer(regs) - sd->offset < sd->len))
> return false;
>
> diff --git a/kernel/ptrace.c b/kernel/ptrace.c
> index 54482193e1ed..a6ad815bd4be 100644
> --- a/kernel/ptrace.c
> +++ b/kernel/ptrace.c
> @@ -370,6 +370,11 @@ static int check_ptrace_options(unsigned long data)
> if (data & ~(unsigned long)PTRACE_O_MASK)
> return -EINVAL;
>
> + if (unlikely(data & PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH)) {
> + if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTART))
> + return -EINVAL;
> + }
> +
> if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) {
> if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) ||
> !IS_ENABLED(CONFIG_SECCOMP))
> --
> 2.39.0
>

2023-01-20 11:15:22

by Damien Le Moal

[permalink] [raw]

Subject: Re: [PATCH 1/3] ptrace,syscall_user_dispatch: Implement Syscall User Dispatch Suspension

On 1/20/23 19:23, Peter Zijlstra wrote:
> On Wed, Jan 18, 2023 at 03:10:53PM -0500, Gregory Price wrote:
>> Adds PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH to ptrace options, and
>> modify Syscall User Dispatch to suspend interception when enabled.
>>
>> This is modeled after the SUSPEND_SECCOMP feature, which suspends
>> SECCOMP interposition. Without doing this, software like CRIU will
>> inject system calls into a process and be intercepted by Syscall
>> User Dispatch, either causing a crash (due to blocked signals) or
>> the delivery of those signals to a ptracer (not the intended behavior).
>>
>> Since Syscall User Dispatch is not a privileged feature, a check
>> for permissions is not required, however attempting to set this
>> option when CONFIG_CHECKPOINT_RESTORE it not supported should be
>> disallowed, as its intended use is checkpoint/resume.
>>
>> Signed-off-by: Gregory Price <[email protected]>
>
> One small nit -- see below, otherwise:
>
> Acked-by: Peter Zijlstra (Intel) <[email protected]>
>
>> ---
>> include/linux/ptrace.h | 2 ++
>> include/uapi/linux/ptrace.h | 6 +++++-
>> kernel/entry/syscall_user_dispatch.c | 5 +++++
>> kernel/ptrace.c | 5 +++++
>> 4 files changed, 17 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
>> index eaaef3ffec22..461ae5c99d57 100644
>> --- a/include/linux/ptrace.h
>> +++ b/include/linux/ptrace.h
>> @@ -45,6 +45,8 @@ extern int ptrace_access_vm(struct task_struct *tsk, unsigned long addr,
>>
>> #define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
>> #define PT_SUSPEND_SECCOMP (PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
>> +#define PT_SUSPEND_SYSCALL_USER_DISPATCH \
>> + (PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH << PT_OPT_FLAG_SHIFT)
>>
>> extern long arch_ptrace(struct task_struct *child, long request,
>> unsigned long addr, unsigned long data);
>> diff --git a/include/uapi/linux/ptrace.h b/include/uapi/linux/ptrace.h
>> index 195ae64a8c87..ba9e3f19a22c 100644
>> --- a/include/uapi/linux/ptrace.h
>> +++ b/include/uapi/linux/ptrace.h
>> @@ -146,9 +146,13 @@ struct ptrace_rseq_configuration {
>> /* eventless options */
>> #define PTRACE_O_EXITKILL (1 << 20)
>> #define PTRACE_O_SUSPEND_SECCOMP (1 << 21)
>> +#define PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH (1 << 22)
>>
>> #define PTRACE_O_MASK (\
>> - 0x000000ff | PTRACE_O_EXITKILL | PTRACE_O_SUSPEND_SECCOMP)
>> + 0x000000ff | \
>> + PTRACE_O_EXITKILL | \
>> + PTRACE_O_SUSPEND_SECCOMP | \
>> + PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH)
>>
>> #include <asm/ptrace.h>
>>
>> diff --git a/kernel/entry/syscall_user_dispatch.c b/kernel/entry/syscall_user_dispatch.c
>> index 0b6379adff6b..7607f4598dd8 100644
>> --- a/kernel/entry/syscall_user_dispatch.c
>> +++ b/kernel/entry/syscall_user_dispatch.c
>> @@ -8,6 +8,7 @@
>> #include <linux/uaccess.h>
>> #include <linux/signal.h>
>> #include <linux/elf.h>
>> +#include <linux/ptrace.h>
>>
>> #include <linux/sched/signal.h>
>> #include <linux/sched/task_stack.h>
>> @@ -36,6 +37,10 @@ bool syscall_user_dispatch(struct pt_regs *regs)
>> struct syscall_user_dispatch *sd = &current->syscall_dispatch;
>> char state;
>>
>> + if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
>> + unlikely(current->ptrace & PT_SUSPEND_SYSCALL_USER_DISPATCH))
>
> Align with the '(' pleaase.
>
>> + return false;
>> +
>> if (likely(instruction_pointer(regs) - sd->offset < sd->len))
>> return false;
>>
>> diff --git a/kernel/ptrace.c b/kernel/ptrace.c
>> index 54482193e1ed..a6ad815bd4be 100644
>> --- a/kernel/ptrace.c
>> +++ b/kernel/ptrace.c
>> @@ -370,6 +370,11 @@ static int check_ptrace_options(unsigned long data)
>> if (data & ~(unsigned long)PTRACE_O_MASK)
>> return -EINVAL;
>>
>> + if (unlikely(data & PTRACE_O_SUSPEND_SYSCALL_USER_DISPATCH)) {
>> + if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTART))

Why not one if with a && ?

>> + return -EINVAL;
>> + }
>> +
>> if (unlikely(data & PTRACE_O_SUSPEND_SECCOMP)) {
>> if (!IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) ||
>> !IS_ENABLED(CONFIG_SECCOMP))
>> --
>> 2.39.0
>>

--
Damien Le Moal
Western Digital Research