The patch titled
Subject: kernel/audit: reduce mmap_sem hold for mm->exe_file
has been added to the -mm tree. Its filename is
kernel-audit-reduce-mmap_sem-hold-for-mm-exe_file.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/kernel-audit-reduce-mmap_sem-hold-for-mm-exe_file.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/kernel-audit-reduce-mmap_sem-hold-for-mm-exe_file.patch
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From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: kernel/audit: reduce mmap_sem hold for mm->exe_file
The mm->exe_file is currently serialized with mmap_sem (shared) in order
to both safely (1) read the file and (2) audit it via audit_log_d_path().
Good users will, on the other hand, make use of the more standard
get_mm_exe_file(), requiring only holding the mmap_sem to read the value,
and relying on reference counting to make sure that the exe file won't
dissapear underneath us.
Additionally, upon NULL return of get_mm_exe_file, we also call
audit_log_format(ab, " exe=(null)").
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: Paul Moore <paul@xxxxxxxxxxxxxx>
Cc: Eric Paris <eparis@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/audit.c | 22 ++++++++++++++--------
1 file changed, 14 insertions(+), 8 deletions(-)
diff -puN kernel/audit.c~kernel-audit-reduce-mmap_sem-hold-for-mm-exe_file kernel/audit.c
--- a/kernel/audit.c~kernel-audit-reduce-mmap_sem-hold-for-mm-exe_file
+++ a/kernel/audit.c
@@ -43,6 +43,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/file.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/atomic.h>
@@ -1841,15 +1842,20 @@ EXPORT_SYMBOL(audit_log_task_context);
void audit_log_d_path_exe(struct audit_buffer *ab,
struct mm_struct *mm)
{
- if (!mm) {
- audit_log_format(ab, " exe=(null)");
- return;
- }
+ struct file *exe_file;
+
+ if (!mm)
+ goto out_null;
- down_read(&mm->mmap_sem);
- if (mm->exe_file)
- audit_log_d_path(ab, " exe=", &mm->exe_file->f_path);
- up_read(&mm->mmap_sem);
+ exe_file = get_mm_exe_file(mm);
+ if (!exe_file)
+ goto out_null;
+
+ audit_log_d_path(ab, " exe=", &exe_file->f_path);
+ fput(exe_file);
+ return;
+out_null:
+ audit_log_format(ab, " exe=(null)");
}
void audit_log_task_info(struct audit_buffer *ab, struct task_struct *tsk)
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
kernel-audit-consolidate-handling-of-mm-exe_file.patch
kernel-audit-reduce-mmap_sem-hold-for-mm-exe_file.patch
arc-do-not-export-symbols-in-troubleshootc.patch
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