linux-kernel - Re: [PATCH] fanotify: Fix event filtering with FAN

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Date:	Mon, 2 Mar 2015 11:38:01 +0100
From:	Jan Kara <jack@...e.cz>
To:	"Suzuki K. Poulose" <suzuki.poulose@....com>
Cc:	Lino Sanfilippo <LinoSanfilippo@....de>,
	linux-kernel@...r.kernel.org, Jan Kara <jack@...e.cz>,
	Eric Paris <eparis@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Will Deacon <will.deacon@....com>
Subject: Re: [PATCH] fanotify: Fix event filtering with FAN_ONDIR set

On Fri 27-02-15 11:40:39, Suzuki K. Poulose wrote:
> From: "Suzuki K. Poulose" <suzuki.poulose@....com>
> 
> 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 <LinoSanfilippo@....de>
> Cc: Jan Kara <jack@...e.cz>
> Cc: Eric Paris <eparis@...hat.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Will Deacon <will.deacon@....com>
> Signed-off-by: Suzuki K. Poulose <suzuki.poulose@....com>
  Thanks for the fix. I should have run LTP myself. You can add:
Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  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
> 
> 
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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