* [PATCH mm RESEND] c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal
@ 2012-04-07 19:08 ` Konstantin Khlebnikov
0 siblings, 0 replies; 4+ messages in thread
From: Konstantin Khlebnikov @ 2012-04-07 19:08 UTC (permalink / raw)
To: linux-mm, Andrew Morton, linux-kernel
Cc: Kees Cook, Pavel Emelyanov, Oleg Nesterov, Tejun Heo,
Matt Helsley, KOSAKI Motohiro, Cyrill Gorcunov
[ fix for "c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-v2" from mm tree ]
After removing mm->num_exe_file_vmas kernel keeps mm->exe_file until final mmput(),
it never becomes NULL while task is alive.
We can check for other mapped files in mm instead of checking mm->num_exe_file_vmas,
and mark mm with flag MMF_EXE_FILE_CHANGED in order to forbid second changing of mm->exe_file.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
---
include/linux/sched.h | 1 +
kernel/sys.c | 31 +++++++++++++++++++------------
2 files changed, 20 insertions(+), 12 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 81a173c..ac61e51 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -437,6 +437,7 @@ extern int get_dumpable(struct mm_struct *mm);
/* leave room for more dump flags */
#define MMF_VM_MERGEABLE 16 /* KSM may merge identical pages */
#define MMF_VM_HUGEPAGE 17 /* set when VM_HUGEPAGE is set on vma */
+#define MMF_EXE_FILE_CHANGED 18 /* see prctl_set_mm_exe_file() */
#define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
diff --git a/kernel/sys.c b/kernel/sys.c
index 089cb11..c6cdef5 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1714,17 +1714,11 @@ static bool vma_flags_mismatch(struct vm_area_struct *vma,
static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
{
+ struct vm_area_struct *vma;
struct file *exe_file;
struct dentry *dentry;
int err;
- /*
- * Setting new mm::exe_file is only allowed when no VM_EXECUTABLE vma's
- * remain. So perform a quick test first.
- */
- if (mm->num_exe_file_vmas)
- return -EBUSY;
-
exe_file = fget(fd);
if (!exe_file)
return -EBADF;
@@ -1745,17 +1739,30 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
if (err)
goto exit;
+ down_write(&mm->mmap_sem);
+
+ /*
+ * Forbid mm->exe_file change if there are mapped other files.
+ */
+ err = -EBUSY;
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (vma->vm_file && !path_equal(&vma->vm_file->f_path,
+ &exe_file->f_path))
+ goto exit_unlock;
+ }
+
/*
* The symlink can be changed only once, just to disallow arbitrary
* transitions malicious software might bring in. This means one
* could make a snapshot over all processes running and monitor
* /proc/pid/exe changes to notice unusual activity if needed.
*/
- down_write(&mm->mmap_sem);
- if (likely(!mm->exe_file))
- set_mm_exe_file(mm, exe_file);
- else
- err = -EBUSY;
+ err = -EPERM;
+ if (test_and_set_bit(MMF_EXE_FILE_CHANGED, &mm->flags))
+ goto exit_unlock;
+
+ set_mm_exe_file(mm, exe_file);
+exit_unlock:
up_write(&mm->mmap_sem);
exit:
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH mm RESEND] c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal
@ 2012-04-07 19:08 ` Konstantin Khlebnikov
0 siblings, 0 replies; 4+ messages in thread
From: Konstantin Khlebnikov @ 2012-04-07 19:08 UTC (permalink / raw)
To: linux-mm, Andrew Morton, linux-kernel
Cc: Kees Cook, Pavel Emelyanov, Oleg Nesterov, Tejun Heo,
Matt Helsley, KOSAKI Motohiro, Cyrill Gorcunov
[ fix for "c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-v2" from mm tree ]
After removing mm->num_exe_file_vmas kernel keeps mm->exe_file until final mmput(),
it never becomes NULL while task is alive.
We can check for other mapped files in mm instead of checking mm->num_exe_file_vmas,
and mark mm with flag MMF_EXE_FILE_CHANGED in order to forbid second changing of mm->exe_file.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
---
include/linux/sched.h | 1 +
kernel/sys.c | 31 +++++++++++++++++++------------
2 files changed, 20 insertions(+), 12 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 81a173c..ac61e51 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -437,6 +437,7 @@ extern int get_dumpable(struct mm_struct *mm);
/* leave room for more dump flags */
#define MMF_VM_MERGEABLE 16 /* KSM may merge identical pages */
#define MMF_VM_HUGEPAGE 17 /* set when VM_HUGEPAGE is set on vma */
+#define MMF_EXE_FILE_CHANGED 18 /* see prctl_set_mm_exe_file() */
#define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)
diff --git a/kernel/sys.c b/kernel/sys.c
index 089cb11..c6cdef5 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1714,17 +1714,11 @@ static bool vma_flags_mismatch(struct vm_area_struct *vma,
static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
{
+ struct vm_area_struct *vma;
struct file *exe_file;
struct dentry *dentry;
int err;
- /*
- * Setting new mm::exe_file is only allowed when no VM_EXECUTABLE vma's
- * remain. So perform a quick test first.
- */
- if (mm->num_exe_file_vmas)
- return -EBUSY;
-
exe_file = fget(fd);
if (!exe_file)
return -EBADF;
@@ -1745,17 +1739,30 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
if (err)
goto exit;
+ down_write(&mm->mmap_sem);
+
+ /*
+ * Forbid mm->exe_file change if there are mapped other files.
+ */
+ err = -EBUSY;
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (vma->vm_file && !path_equal(&vma->vm_file->f_path,
+ &exe_file->f_path))
+ goto exit_unlock;
+ }
+
/*
* The symlink can be changed only once, just to disallow arbitrary
* transitions malicious software might bring in. This means one
* could make a snapshot over all processes running and monitor
* /proc/pid/exe changes to notice unusual activity if needed.
*/
- down_write(&mm->mmap_sem);
- if (likely(!mm->exe_file))
- set_mm_exe_file(mm, exe_file);
- else
- err = -EBUSY;
+ err = -EPERM;
+ if (test_and_set_bit(MMF_EXE_FILE_CHANGED, &mm->flags))
+ goto exit_unlock;
+
+ set_mm_exe_file(mm, exe_file);
+exit_unlock:
up_write(&mm->mmap_sem);
exit:
--
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH mm RESEND] c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal
2012-04-07 19:08 ` Konstantin Khlebnikov
@ 2012-04-10 22:59 ` Cyrill Gorcunov
-1 siblings, 0 replies; 4+ messages in thread
From: Cyrill Gorcunov @ 2012-04-10 22:59 UTC (permalink / raw)
To: Konstantin Khlebnikov
Cc: linux-mm, Andrew Morton, linux-kernel, Kees Cook,
Pavel Emelyanov, Oleg Nesterov, Tejun Heo, Matt Helsley,
KOSAKI Motohiro
On Sat, Apr 07, 2012 at 11:08:02PM +0400, Konstantin Khlebnikov wrote:
> [ fix for "c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-v2" from mm tree ]
>
> After removing mm->num_exe_file_vmas kernel keeps mm->exe_file until final mmput(),
> it never becomes NULL while task is alive.
>
> We can check for other mapped files in mm instead of checking mm->num_exe_file_vmas,
> and mark mm with flag MMF_EXE_FILE_CHANGED in order to forbid second changing of mm->exe_file.
>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Hi Konstantin, really sorry for delay. This should do trick for us.
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH mm RESEND] c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal
@ 2012-04-10 22:59 ` Cyrill Gorcunov
0 siblings, 0 replies; 4+ messages in thread
From: Cyrill Gorcunov @ 2012-04-10 22:59 UTC (permalink / raw)
To: Konstantin Khlebnikov
Cc: linux-mm, Andrew Morton, linux-kernel, Kees Cook,
Pavel Emelyanov, Oleg Nesterov, Tejun Heo, Matt Helsley,
KOSAKI Motohiro
On Sat, Apr 07, 2012 at 11:08:02PM +0400, Konstantin Khlebnikov wrote:
> [ fix for "c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-v2" from mm tree ]
>
> After removing mm->num_exe_file_vmas kernel keeps mm->exe_file until final mmput(),
> it never becomes NULL while task is alive.
>
> We can check for other mapped files in mm instead of checking mm->num_exe_file_vmas,
> and mark mm with flag MMF_EXE_FILE_CHANGED in order to forbid second changing of mm->exe_file.
>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Hi Konstantin, really sorry for delay. This should do trick for us.
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-04-10 23:00 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2012-04-07 19:08 [PATCH mm RESEND] c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal Konstantin Khlebnikov
2012-04-07 19:08 ` Konstantin Khlebnikov
2012-04-10 22:59 ` Cyrill Gorcunov
2012-04-10 22:59 ` Cyrill Gorcunov
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