diff options
| author | Davidlohr Bueso <dave@stgolabs.net> | 2015-04-16 12:49:18 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-17 09:04:11 -0400 |
| commit | d4144ea6e7cc307e84cd9ca227df7b04a54a2365 (patch) | |
| tree | a12d8c0df4e50b5b307cc2d77d5f870ed7042dba | |
| parent | fd89a65f155fa890c0130139dfb91684d6da4cfb (diff) | |
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
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | security/tomoyo/util.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/security/tomoyo/util.c b/security/tomoyo/util.c index 2952ba576fb9..b974a6997d7f 100644 --- a/security/tomoyo/util.c +++ b/security/tomoyo/util.c @@ -948,15 +948,18 @@ bool tomoyo_path_matches_pattern(const struct tomoyo_path_info *filename, */ const char *tomoyo_get_exe(void) { + struct file *exe_file; + const char *cp; struct mm_struct *mm = current->mm; - const char *cp = NULL; 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); + 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; } |