From 20663629f6ae7bc072a8bbc658721bd99626a26d Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Tue, 30 Oct 2018 20:29:53 +0200 Subject: [PATCH] fanotify: fix handling of events on child sub-directory commit b469e7e47c8a075cc08bcd1e85d4365134bdcdd5 upstream. 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: # v4.19 Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara [amir: backport to v4.19] Signed-off-by: Amir Goldstein Signed-off-by: Greg Kroah-Hartman --- 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 94b52157bf8d..29dee9630eec 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -115,12 +115,12 @@ 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 14b4ac5256d1..170a733454f7 100644 --- a/fs/notify/fsnotify.c +++ b/fs/notify/fsnotify.c @@ -161,9 +161,9 @@ 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 & ALL_FSNOTIFY_EVENTS) { struct name_snapshot name; /* we are notifying a parent so come up with the new mask which @@ -331,6 +331,10 @@ 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.