[PATCH 3.4 024/172] fsnotify: fix handling of renames in audit

lizf
2015-06-16T09:37:06Z

From: Jan Kara <jack@suse.cz>

3.4.108-rc1 review patch. If anyone has any objections, please let me know.

------------------

commit 6ee8e25fc3e916193bce4ebb43d5439e1e2144ab upstream.

Commit e9fd702a58c4 ("audit: convert audit watches to use fsnotify
instead of inotify") broke handling of renames in audit. Audit code
wants to update inode number of an inode corresponding to watched name
in a directory. When something gets renamed into a directory to a
watched name, inotify previously passed moved inode to audit code
however new fsnotify code passes directory inode where the change
happened. That confuses audit and it starts watching parent directory
instead of a file in a directory.

This can be observed for example by doing:

cd /tmp
touch foo bar
auditctl -w /tmp/foo
touch foo
mv bar foo
touch foo

In audit log we see events like:

type=CONFIG_CHANGE msg=audit(1423563584.155:90): auid=1000 ses=2 op="updated rules" path="/tmp/foo" key=(null) list=4 res=1
...
type=PATH msg=audit(1423563584.155:91): item=2 name="bar" inode=1046884 dev=08:0 2 mode=0100644 ouid=0 ogid=0 rdev=00:00 nametype=DELETE
type=PATH msg=audit(1423563584.155:91): item=3 name="foo" inode=1046842 dev=08:0 2 mode=0100644 ouid=0 ogid=0 rdev=00:00 nametype=DELETE
type=PATH msg=audit(1423563584.155:91): item=4 name="foo" inode=1046884 dev=08:0 2 mode=0100644 ouid=0 ogid=0 rdev=00:00 nametype=CREATE
...

and that's it - we see event for the first touch after creating the
audit rule, we see events for rename but we don't see any event for the
last touch. However we start seeing events for unrelated stuff
happening in /tmp.

Fix the problem by passing moved inode as data in the FS_MOVED_FROM and
FS_MOVED_TO events instead of the directory where the change happens.
This doesn't introduce any new problems because noone besides
audit_watch.c cares about the passed value:

fs/notify/fanotify/fanotify.c cares only about FSNOTIFY_EVENT_PATH events.
fs/notify/dnotify/dnotify.c doesn't care about passed 'data' value at all.
fs/notify/inotify/inotify_fsnotify.c uses 'data' only for FSNOTIFY_EVENT_PATH.
kernel/audit_tree.c doesn't care about passed 'data' at all.
kernel/audit_watch.c expects moved inode as 'data'.

Fixes: e9fd702a58c49db ("audit: convert audit watches to use fsnotify instead of inotify")
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
include/linux/fsnotify.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index a6dfe69..fac26cb 100644
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -101,8 +101,10 @@ static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
new_dir_mask |= FS_ISDIR;
}

- fsnotify(old_dir, old_dir_mask, old_dir, FSNOTIFY_EVENT_INODE, old_name, fs_cookie);
- fsnotify(new_dir, new_dir_mask, new_dir, FSNOTIFY_EVENT_INODE, new_name, fs_cookie);
+ fsnotify(old_dir, old_dir_mask, source, FSNOTIFY_EVENT_INODE, old_name,
+ fs_cookie);
+ fsnotify(new_dir, new_dir_mask, source, FSNOTIFY_EVENT_INODE, new_name,
+ fs_cookie);

if (target)
fsnotify_link_count(target);
--
1.9.1