Re: [PATCH v2 01/20] fanotify: fix logic of events on child

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On Thu 05-04-18 16:18:02, Amir Goldstein wrote:
> When event on child inodes are sent to the parent inode mark and
> parent inode mark was not marked with FAN_EVENT_ON_CHILD, the event
> will not be delivered to the listener process. However, if the same
> process also has a mount mark, the event to the parent inode will be
> delivered regadless of the mount mark mask.
> 
> This behavior is incorrect in the case where the mount mark mask does
> not contain the specific event type. For example, the process adds
> a mark on a directory with mask FAN_MODIFY (without FAN_EVENT_ON_CHILD)
> and a mount mark with mask FAN_CLOSE_NOWRITE (without FAN_ONDIR).
> 
> A modify event on a file inside that directory (and inside that mount)
> should not create a FAN_MODIFY event, because neither of the marks
> requested to get that event on the file.
> 
> Fixes: 1968f5eed54c ("fanotify: use both marks when possible")
> Cc: stable <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>

This is already in my tree and I'll push it to Linus next week. JFYI.

								Honza

> ---
>  fs/notify/fanotify/fanotify.c | 34 +++++++++++++++-------------------
>  1 file changed, 15 insertions(+), 19 deletions(-)
> 
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 6702a6a0bbb5..e0e6a9d627df 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -92,7 +92,7 @@ static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
>  				       u32 event_mask,
>  				       const void *data, int data_type)
>  {
> -	__u32 marks_mask, marks_ignored_mask;
> +	__u32 marks_mask = 0, marks_ignored_mask = 0;
>  	const struct path *path = data;
>  
>  	pr_debug("%s: inode_mark=%p vfsmnt_mark=%p mask=%x data=%p"
> @@ -108,24 +108,20 @@ static bool fanotify_should_send_event(struct fsnotify_mark *inode_mark,
>  	    !d_can_lookup(path->dentry))
>  		return false;
>  
> -	if (inode_mark && vfsmnt_mark) {
> -		marks_mask = (vfsmnt_mark->mask | inode_mark->mask);
> -		marks_ignored_mask = (vfsmnt_mark->ignored_mask | inode_mark->ignored_mask);
> -	} else if (inode_mark) {
> -		/*
> -		 * if the event is for a child and this inode doesn't care about
> -		 * events on the child, don't send it!
> -		 */
> -		if ((event_mask & FS_EVENT_ON_CHILD) &&
> -		    !(inode_mark->mask & FS_EVENT_ON_CHILD))
> -			return false;
> -		marks_mask = inode_mark->mask;
> -		marks_ignored_mask = inode_mark->ignored_mask;
> -	} else if (vfsmnt_mark) {
> -		marks_mask = vfsmnt_mark->mask;
> -		marks_ignored_mask = vfsmnt_mark->ignored_mask;
> -	} else {
> -		BUG();
> +	/*
> +	 * if the event is for a child and this inode doesn't care about
> +	 * events on the child, don't send it!
> +	 */
> +	if (inode_mark &&
> +	    (!(event_mask & FS_EVENT_ON_CHILD) ||
> +	     (inode_mark->mask & FS_EVENT_ON_CHILD))) {
> +		marks_mask |= inode_mark->mask;
> +		marks_ignored_mask |= inode_mark->ignored_mask;
> +	}
> +
> +	if (vfsmnt_mark) {
> +		marks_mask |= vfsmnt_mark->mask;
> +		marks_ignored_mask |= vfsmnt_mark->ignored_mask;
>  	}
>  
>  	if (d_is_dir(path->dentry) &&
> -- 
> 2.7.4
> 
-- 
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR



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