2015-02-27 11:40:59

by Suzuki K Poulose

Subject: [PATCH] fanotify: Fix event filtering with FAN_ONDIR set

From: "Suzuki K. Poulose" <[email protected]>

With FAN_ONDIR set, the user can end up getting events, which
it hasn't marked. This was revealed with fanotify04 testcase
failure on Linux-4.0-rc1, and is a regression from 3.19, revealed
with commit (66ba93c0d7fe6: fanotify: don't set FAN_ONDIR implicitly
on a marks ignored mask).

# /opt/ltp/testcases/bin/fanotify04
[ ... ]
fanotify04 7 TPASS : event generated properly for type 100000
fanotify04 8 TFAIL : fanotify04.c:147: got unexpected event 30
fanotify04 9 TPASS : No event as expected

The testcase sets the adds the following marks :
FAN_OPEN | FAN_ONDIR for a fanotify on a dir.
Then does an open(), followed by close() of the directory and
expects to see an event FAN_OPEN(0x20). However, the fanotify
returns (FAN_OPEN|FAN_CLOSE_NOWRITE(0x10)). This happens due
to the flaw in the check for event_mask in fanotify_should_send_event()
which does:

if (event_mask & marks_mask & ~marks_ignored_mask)
return true;

where, event_mask = (FAN_ONDIR | FAN_CLOSE_NOWRITE),
marks_mask = (FAN_ONDIR | FAN_OPEN),
marks_ignored_mask = 0

Fix this by masking the outgoing events to the user, as we
already take care of FAN_ONDIR and FAN_EVENT_ON_CHILD.

Cc: Lino Sanfilippo <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Eric Paris <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Suzuki K. Poulose <[email protected]>
---
fs/notify/fanotify/fanotify.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 9a66ff7..d2f97ec 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -143,7 +143,8 @@ static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
!(marks_mask & FS_ISDIR & ~marks_ignored_mask))
return false;

- if (event_mask & marks_mask & ~marks_ignored_mask)
+ if (event_mask & FAN_ALL_OUTGOING_EVENTS & marks_mask &
+ ~marks_ignored_mask)
return true;

return false;
--
1.7.9.5

2015-03-01 02:31:15

by Lino Sanfilippo

Subject: Re: [PATCH] fanotify: Fix event filtering with FAN_ONDIR set

Hi Suzuki,

On 27.02.2015 12:40, Suzuki K. Poulose wrote:
> From: "Suzuki K. Poulose" <[email protected]>
>
> With FAN_ONDIR set, the user can end up getting events, which
> it hasn't marked. This was revealed with fanotify04 testcase
> failure on Linux-4.0-rc1, and is a regression from 3.19, revealed
> with commit (66ba93c0d7fe6: fanotify: don't set FAN_ONDIR implicitly
> on a marks ignored mask).
>

>
> Fix this by masking the outgoing events to the user, as we
> already take care of FAN_ONDIR and FAN_EVENT_ON_CHILD.
>

thank you for fixing this. I tested your solution and it works, so you
can add Tested-by: Lino Sanfilippo <[email protected]>.

Regards,
Lino