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>
---
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
