On Tue, Nov 27, 2018 at 11:09 AM Miklos Szeredi miklos@szeredi.hu wrote:
Hi Amir,
Here's a backport of this patch to 4.18 and earlier. Tested good with ltp/fanotify09.
AFAICS this backport is identical to my v4.19 backport and yes, it looks fine. I just missed the fact that my v4.19 does apply cleanly on v4.18 or I would have asked Greg to apply it.
OTOH, your backport is good for v4.18 not earlier, nothing before: 837a39343847 fanotify: generalize fanotify_should_send_event()
I didn't quite understand the relevance of masking against ALL_FSNOTIFY_EVENTS in __fsnotify_parent()
Right... that is because stable is missing: 007d1e8395ea fsnotify: generalize handling of extra event flags
The mask in __fsnotify_parent() (on master) the same as (stable) mask in fsnotify(), i.e. test_mask = (mask & ~FS_EVENT_ON_CHILD); so its a very minor but low hanging optimization once ALL_FSNOTIFY_EVENTS is defined. So in the backport the mask in __fsnotify_parent() does nothing but its not critical either.
and the backport in fsnotify() is also not quite trivial.
It means: if __fsnotify_parent() is reporting this event, then the event is not intended for a mount mark. __fsnotify_parent() is always called paired with fsnotify() (not for parent) and the mount mark will be getting the event in that second call.
So this is a double layered fix for the bug:
The check in fsnotify() optimizes away events reported from __fsnotify_parent() if the parent inode does NOT have event in commutative mask of ANY group, but mount mark DOES have event in mask of SOME groups.
The check in fanotify_should_send_event() does the same for a SPECIFIC group.
So, can you please review?
Looks good,
Thanks, Amir.
Date: Tue, 30 Oct 2018 20:29:53 +0200 Subject: [PATCH] fanotify: fix handling of events on child sub-directory
When an event is reported on a sub-directory and the parent inode has a mark mask with FS_EVENT_ON_CHILD|FS_ISDIR, the event will be sent to fsnotify() even if the event type is not in the parent mark mask (e.g. FS_OPEN).
Further more, if that event happened on a mount or a filesystem with a mount/sb mark that does have that event type in their mask, the "on child" event will be reported on the mount/sb mark. That is not desired, because user will get a duplicate event for the same action.
Note that the event reported on the victim inode is never merged with the event reported on the parent inode, because of the check in should_merge(): old_fsn->inode == new_fsn->inode.
Fix this by looking for a match of an actual event type (i.e. not just FS_ISDIR) in parent's inode mark mask and by not reporting an "on child" event to group if event type is only found on mount/sb marks.
[backport hint: The bug seems to have always been in fanotify, but this patch will only apply cleanly to v4.19.y]
Cc: stable@vger.kernel.org # v4.19 Signed-off-by: Amir Goldstein amir73il@gmail.com Signed-off-by: Jan Kara jack@suse.cz (cherry picked from commit b469e7e47c8a075cc08bcd1e85d4365134bdcdd5)
fs/notify/fanotify/fanotify.c | 10 +++++----- fs/notify/fsnotify.c | 8 ++++++-- 2 files changed, 11 insertions(+), 7 deletions(-)
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index f90842efea13..78126bd7c162 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -113,12 +113,12 @@ static bool fanotify_should_send_event(struct fsnotify_iter_info *iter_info, continue; mark = iter_info->marks[type]; /*
* if the event is for a child and this inode doesn't care about* events on the child, don't send it!
* If the event is for a child and this mark doesn't care about* events on a child, don't send it! */
if (type == FSNOTIFY_OBJ_TYPE_INODE &&(event_mask & FS_EVENT_ON_CHILD) &&!(mark->mask & FS_EVENT_ON_CHILD))
if (event_mask & FS_EVENT_ON_CHILD &&(type != FSNOTIFY_OBJ_TYPE_INODE ||!(mark->mask & FS_EVENT_ON_CHILD))) continue; marks_mask |= mark->mask;diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c index ababdbfab537..46d27b357226 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -158,9 +158,9 @@ int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask parent = dget_parent(dentry); p_inode = parent->d_inode;
if (unlikely(!fsnotify_inode_watches_children(p_inode)))
if (unlikely(!fsnotify_inode_watches_children(p_inode))) { __fsnotify_update_child_dentry_flags(p_inode);
else if (p_inode->i_fsnotify_mask & mask) {
} else if (p_inode->i_fsnotify_mask & mask & ~FS_EVENT_ON_CHILD) { struct name_snapshot name; /* we are notifying a parent so come up with the new mask which@@ -329,6 +329,10 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is, else mnt = NULL;
/* An event "on child" is not intended for a mount mark */if (mask & FS_EVENT_ON_CHILD)mnt = NULL;/* * Optimization: srcu_read_lock() has a memory barrier which can * be expensive. It protects walking the *_fsnotify_marks lists.-- 2.14.5