Merge tag 'fsnotify_for_v5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

Pull fsnotify updates from Jan Kara:
 "This contains cleanups of the fsnotify name removal hook and also a
  patch to disable fanotify permission events for 'proc' filesystem"

* tag 'fsnotify_for_v5.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fsnotify: get rid of fsnotify_nameremove()
  fsnotify: move fsnotify_nameremove() hook out of d_delete()
  configfs: call fsnotify_rmdir() hook
  debugfs: call fsnotify_{unlink,rmdir}() hooks
  debugfs: simplify __debugfs_remove_file()
  devpts: call fsnotify_unlink() hook
  tracefs: call fsnotify_{unlink,rmdir}() hooks
  rpc_pipefs: call fsnotify_{unlink,rmdir}() hooks
  btrfs: call fsnotify_rmdir() hook
  fsnotify: add empty fsnotify_{unlink,rmdir}() hooks
  fanotify: Disallow permission events for proc filesystem

2 files changed, 22 insertions, 41 deletions

diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index a90bb19dcfa2..91006f47e420 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -920,6 +920,22 @@ static int fanotify_test_fid(struct path *path, __kernel_fsid_t *fsid)
 	return 0;
 }
 
+static int fanotify_events_supported(struct path *path, __u64 mask)
+{
+	/*
+	 * Some filesystems such as 'proc' acquire unusual locks when opening
+	 * files. For them fanotify permission events have high chances of
+	 * deadlocking the system - open done when reporting fanotify event
+	 * blocks on this "unusual" lock while another process holding the lock
+	 * waits for fanotify permission event to be answered. Just disallow
+	 * permission events for such filesystems.
+	 */
+	if (mask & FANOTIFY_PERM_EVENTS &&
+	    path->mnt->mnt_sb->s_type->fs_flags & FS_DISALLOW_NOTIFY_PERM)
+		return -EINVAL;
+	return 0;
+}
+
 static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 			    int dfd, const char  __user *pathname)
 {
@@ -1018,6 +1034,12 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
 	if (ret)
 		goto fput_and_out;
 
+	if (flags & FAN_MARK_ADD) {
+		ret = fanotify_events_supported(&path, mask);
+		if (ret)
+			goto path_put_and_out;
+	}
+
 	if (FAN_GROUP_FLAG(group, FAN_REPORT_FID)) {
 		ret = fanotify_test_fid(&path, &__fsid);
 		if (ret)
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 4eb2ebfac468..2ecef6155fc0 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -95,47 +95,6 @@ void fsnotify_sb_delete(struct super_block *sb)
 }
 
 /*
- * fsnotify_nameremove - a filename was removed from a directory
- *
- * This is mostly called under parent vfs inode lock so name and
- * dentry->d_parent should be stable. However there are some corner cases where
- * inode lock is not held. So to be on the safe side and be reselient to future
- * callers and out of tree users of d_delete(), we do not assume that d_parent
- * and d_name are stable and we use dget_parent() and
- * take_dentry_name_snapshot() to grab stable references.
- */
-void fsnotify_nameremove(struct dentry *dentry, int isdir)
-{
-	struct dentry *parent;
-	struct name_snapshot name;
-	__u32 mask = FS_DELETE;
-
-	/* d_delete() of pseudo inode? (e.g. __ns_get_path() playing tricks) */
-	if (IS_ROOT(dentry))
-		return;
-
-	if (isdir)
-		mask |= FS_ISDIR;
-
-	parent = dget_parent(dentry);
-	/* Avoid unneeded take_dentry_name_snapshot() */
-	if (!(d_inode(parent)->i_fsnotify_mask & FS_DELETE) &&
-	    !(dentry->d_sb->s_fsnotify_mask & FS_DELETE))
-		goto out_dput;
-
-	take_dentry_name_snapshot(&name, dentry);
-
-	fsnotify(d_inode(parent), mask, d_inode(dentry), FSNOTIFY_EVENT_INODE,
-		 &name.name, 0);
-
-	release_dentry_name_snapshot(&name);
-
-out_dput:
-	dput(parent);
-}
-EXPORT_SYMBOL(fsnotify_nameremove);
-
-/*
  * Given an inode, first check if we care what happens to our children.  Inotify
  * and dnotify both tell their parents about events.  If we care about any event
  * on a child we run all of our children and set a dentry flag saying that the