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Commit d4144ea6 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Linus Torvalds
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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: default avatarDavidlohr Bueso <dbueso@suse.de>
Acked-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent fd89a65f

security/tomoyo/util.c

+8 −5
Original line number Diff line number Diff line
@@ -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;

}