The patch titled
Subject: tomoyo: reduce mmap_sem hold for mm->exe_file
has been added to the -mm tree. Its filename is
tomoyo-reduce-mmap_sem-hold-for-mm-exe_file.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/tomoyo-reduce-mmap_sem-hold-for-mm-exe_file.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/tomoyo-reduce-mmap_sem-hold-for-mm-exe_file.patch
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------------------------------------------------------
From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: tomoyo: 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) compute the realpath by calling
tomoyo_realpath_from_path, making it an absolute overkill. 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
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Acked-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: James Morris <jmorris@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
security/tomoyo/util.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)
diff -puN security/tomoyo/util.c~tomoyo-reduce-mmap_sem-hold-for-mm-exe_file security/tomoyo/util.c
--- a/security/tomoyo/util.c~tomoyo-reduce-mmap_sem-hold-for-mm-exe_file
+++ a/security/tomoyo/util.c
@@ -948,16 +948,19 @@ bool tomoyo_path_matches_pattern(const s
*/
const char *tomoyo_get_exe(void)
{
- struct mm_struct *mm = current->mm;
- const char *cp = NULL;
+ struct file *exe_file;
+ const char *cp;
+ struct mm_struct *mm = current->mm;
- if (!mm)
- return NULL;
- down_read(&mm->mmap_sem);
- if (mm->exe_file)
- cp = tomoyo_realpath_from_path(&mm->exe_file->f_path);
- up_read(&mm->mmap_sem);
- return cp;
+ if (!mm)
+ return NULL;
+ exe_file = get_mm_exe_file(mm);
+ if (!exe_file)
+ return NULL;
+
+ cp = tomoyo_realpath_from_path(&exe_file->f_path);
+ fput(exe_file);
+ return cp;
}
/**
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
mm-hugetlb-close-race-when-setting-pagetail-for-gigantic-pages.patch
arc-do-not-export-symbols-in-troubleshootc.patch
linux-next.patch
tile-elf-reorganize-notify_exec.patch
oprofile-reduce-mmap_sem-hold-for-mm-exe_file.patch
powerpc-oprofile-reduce-mmap_sem-hold-for-exe_file.patch
tomoyo-reduce-mmap_sem-hold-for-mm-exe_file.patch
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