On Sun 08-11-20 12:59:06, Amir Goldstein wrote:
> The victim inode's parent and name info is required when an event
> needs to be delivered to a group interested in filename info OR
> when the inode's parent is interested in an event on its children.
>
> Let us call the first condition 'parent_needed' and the second
> condition 'parent_interested'.
>
> In fsnotify_parent(), the condition where the inode's parent is
> interested in some events on its children, but not necessarily
> interested the specific event is called 'parent_watched'.
>
> fsnotify_parent() tests the condition (!parent_watched && !parent_needed)
> for sending the event without parent and name info, which is correct.
>
> It then wrongly assumes that parent_watched implies !parent_needed
> and tests the condition (parent_watched && !parent_interested)
> for sending the event without parent and name info, which is wrong,
> because parent may still be needed by some group.
>
> For example, after initializing a group with FAN_REPORT_DFID_NAME and
> adding a FAN_MARK_MOUNT with FAN_OPEN mask, open events on non-directory
> children of "testdir" are delivered with file name info.
>
> After adding another mark to the same group on the parent "testdir"
> with FAN_CLOSE|FAN_EVENT_ON_CHILD mask, open events on non-directory
> children of "testdir" are no longer delivered with file name info.
>
> Fix the logic and use auxiliary variables to clarify the conditions.
>
> Fixes: 9b93f33105f5 ("fsnotify: send event with parent/name info to sb/mount/non-dir marks")
> Cc: stable@xxxxxxxxxxxxxxx#v5.9
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
Thanks! I've queued the patch to my tree and will send it to Linus later
this week.
Honza
> ---
>
> Jan,
>
> There is an LTP test for this bug at [1].
>
> Thanks,
> Amir.
>
> [1] https://github.com/amir73il/ltp/commits/fsnotify-fixes
>
> fs/notify/fsnotify.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
> index a960ec3a569a..8d3ad5ef2925 100644
> --- a/fs/notify/fsnotify.c
> +++ b/fs/notify/fsnotify.c
> @@ -178,6 +178,7 @@ int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
> struct inode *inode = d_inode(dentry);
> struct dentry *parent;
> bool parent_watched = dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED;
> + bool parent_needed, parent_interested;
> __u32 p_mask;
> struct inode *p_inode = NULL;
> struct name_snapshot name;
> @@ -193,7 +194,8 @@ int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
> return 0;
>
> parent = NULL;
> - if (!parent_watched && !fsnotify_event_needs_parent(inode, mnt, mask))
> + parent_needed = fsnotify_event_needs_parent(inode, mnt, mask);
> + if (!parent_watched && !parent_needed)
> goto notify;
>
> /* Does parent inode care about events on children? */
> @@ -205,17 +207,17 @@ int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
>
> /*
> * Include parent/name in notification either if some notification
> - * groups require parent info (!parent_watched case) or the parent is
> - * interested in this event.
> + * groups require parent info or the parent is interested in this event.
> */
> - if (!parent_watched || (mask & p_mask & ALL_FSNOTIFY_EVENTS)) {
> + parent_interested = mask & p_mask & ALL_FSNOTIFY_EVENTS;
> + if (parent_needed || parent_interested) {
> /* When notifying parent, child should be passed as data */
> WARN_ON_ONCE(inode != fsnotify_data_inode(data, data_type));
>
> /* Notify both parent and child with child name info */
> take_dentry_name_snapshot(&name, dentry);
> file_name = &name.name;
> - if (parent_watched)
> + if (parent_interested)
> mask |= FS_EVENT_ON_CHILD;
> }
>
> --
> 2.17.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
