Unsetting FMODE_NONOTIFY in fsnotify_open() is too late, since fsnotify_perm()
is called before. If FMODE_NONOTIFY is set fsnotify_perm() will skip permission
checks, so a user can still disable permission checks by setting this flag
in an open() call.
This patch corrects this by unsetting the flag before fsnotify_perm is called.
Signed-off-by: Lino Sanfilippo <[email protected]>
---
This patch applies against 2.6.37-rc1
It corrects this unsufficient fix
http://lkml.org/lkml/2010/10/29/125
I totally oversaw those fsnotify_perm() calls :(.
Hopefully this one will set things right...
diff -Nurp a/fs/namei.c b/fs/namei.c
--- a/fs/namei.c 2010-11-01 12:54:12.000000000 +0100
+++ b/fs/namei.c 2010-11-05 10:53:57.000000000 +0100
@@ -1748,6 +1748,9 @@ struct file *do_filp_open(int dfd, const
if (!(open_flag & O_CREAT))
mode = 0;
+ /* Must never be set by userspace */
+ open_flag &= ~FMODE_NONOTIFY;
+
/*
* O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
* check for O_DSYNC if the need any syncing at all we enforce it's
diff -Nurp a/include/linux/fsnotify.h b/include/linux/fsnotify.h
--- a/include/linux/fsnotify.h 2010-11-01 12:54:12.000000000 +0100
+++ b/include/linux/fsnotify.h 2010-11-05 10:49:51.000000000 +0100
@@ -235,9 +235,6 @@ static inline void fsnotify_open(struct
if (S_ISDIR(inode->i_mode))
mask |= FS_ISDIR;
- /* FMODE_NONOTIFY must never be set from user */
- file->f_mode &= ~FMODE_NONOTIFY;
-
fsnotify_parent(path, NULL, mask);
fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
}