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

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

[Amir Goldstein]

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@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 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

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

[Sasha Levin]

Hi,

[This is an automated email]

This commit has been processed because it contains a "Fixes:" tag,
fixing commit: 1968f5eed54c fanotify: use both marks when possible.

The bot has also determined it's probably a bug fixing patch. (score: 70.2871)

The bot has tested the following trees: v4.16, v4.15.15, v4.14.32, v4.9.92, v4.4.126.

v4.16: Build OK!
v4.15.15: Build OK!
v4.14.32: Build OK!
v4.9.92: Failed to apply! Possible dependencies:
    3cd5eca8d7a2 ("fsnotify: constify 'data' passed to ->handle_event()")

v4.4.126: Failed to apply! Possible dependencies:
    3cd5eca8d7a2 ("fsnotify: constify 'data' passed to ->handle_event()")


--
Thanks,
Sasha

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

[Jan Kara]

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@vger.kernel.org>
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>

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@suse.com>
SUSE Labs, CR