linux-stable.git/fs/notify, branch v5.4.263

fanotify: disallow mount/sb marks on kernel internal pseudo fs

2023-07-27T06:37:26+00:00

commit 69562eb0bd3e6bb8e522a7b254334e0fb30dff0c upstream.

Hopefully, nobody is trying to abuse mount/sb marks for watching all
anonymous pipes/inodes.

I cannot think of a good reason to allow this - it looks like an
oversight that dated back to the original fanotify API.

Link: https://lore.kernel.org/linux-fsdevel/20230628101132.kvchg544mczxv2pm@quack3/
Fixes: 0ff21db9fcc3 ("fanotify: hooks the fanotify_mark syscall to the vfsmount code")
Signed-off-by: Amir Goldstein 
Reviewed-by: Christian Brauner 
Signed-off-by: Jan Kara 
Message-Id: <20230629042044.25723-1-amir73il@gmail.com>
[backport to 5.x.y]
Signed-off-by: Amir Goldstein 
Signed-off-by: Greg Kroah-Hartman

inotify: Avoid reporting event with invalid wd

2023-05-17T09:36:01+00:00

commit c915d8f5918bea7c3962b09b8884ca128bfd9b0c upstream.

When inotify_freeing_mark() races with inotify_handle_inode_event() it
can happen that inotify_handle_inode_event() sees that i_mark->wd got
already reset to -1 and reports this value to userspace which can
confuse the inotify listener. Avoid the problem by validating that wd is
sensible (and pretend the mark got removed before the event got
generated otherwise).

CC: stable@vger.kernel.org
Fixes: 7e790dd5fc93 ("inotify: fix error paths in inotify_update_watch")
Message-Id: <20230424163219.9250-1-jack@suse.cz>
Reported-by: syzbot+4a06d4373fd52f0b2f9c@syzkaller.appspotmail.com
Reviewed-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Signed-off-by: Greg Kroah-Hartman

fsnotify: fix wrong lockdep annotations

2022-06-14T16:11:34+00:00

[ Upstream commit 623af4f538b5df9b416e1b82f720af7371b4c771 ]

Commit 6960b0d909cd ("fsnotify: change locking order") changed some
of the mark_mutex locks in direct reclaim path to use:
  mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING);

This change is explained:
 "...It uses nested locking to avoid deadlock in case we do the final
  iput() on an inode which still holds marks and thus would take the
  mutex again when calling fsnotify_inode_delete() in destroy_inode()."

The problem is that the mutex_lock_nested() is not a nested lock at
all. In fact, it has the opposite effect of preventing lockdep from
warning about a very possible deadlock.

Due to these wrong annotations, a deadlock that was introduced with
nfsd filecache in kernel v5.4 went unnoticed in v5.4.y for over two
years until it was reported recently by Khazhismel Kumykov, only to
find out that the deadlock was already fixed in kernel v5.5.

Fix the wrong lockdep annotations.

Cc: Khazhismel Kumykov 
Fixes: 6960b0d909cd ("fsnotify: change locking order")
Link: https://lore.kernel.org/r/20220321112310.vpr7oxro2xkz5llh@quack3.lan/
Link: https://lore.kernel.org/r/20220422120327.3459282-4-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Signed-off-by: Sasha Levin

inotify: show inotify mask flags in proc fdinfo

2022-06-14T16:11:34+00:00

[ Upstream commit a32e697cda27679a0327ae2cafdad8c7170f548f ]

The inotify mask flags IN_ONESHOT and IN_EXCL_UNLINK are not "internal
to kernel" and should be exposed in procfs fdinfo so CRIU can restore
them.

Fixes: 6933599697c9 ("inotify: hide internal kernel bits from fdinfo")
Link: https://lore.kernel.org/r/20220422120327.3459282-2-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Signed-off-by: Sasha Levin

fanotify: fix ignore mask logic for events on child and on dir

2020-06-17T14:40:24+00:00

[ Upstream commit 2f02fd3fa13e51713b630164f8a8e5b42de8283b ]

The comments in fanotify_group_event_mask() say:

  "If the event is on dir/child and this mark doesn't care about
   events on dir/child, don't send it!"

Specifically, mount and filesystem marks do not care about events
on child, but they can still specify an ignore mask for those events.
For example, a group that has:
- A mount mark with mask 0 and ignore_mask FAN_OPEN
- An inode mark on a directory with mask FAN_OPEN | FAN_OPEN_EXEC
  with flag FAN_EVENT_ON_CHILD

A child file open for exec would be reported to group with the FAN_OPEN
event despite the fact that FAN_OPEN is in ignore mask of mount mark,
because the mark iteration loop skips over non-inode marks for events
on child when calculating the ignore mask.

Move ignore mask calculation to the top of the iteration loop block
before excluding marks for events on dir/child.

Link: https://lore.kernel.org/r/20200524072441.18258-1-amir73il@gmail.com
Reported-by: Jan Kara 
Link: https://lore.kernel.org/linux-fsdevel/20200521162443.GA26052@quack2.suse.cz/
Fixes: 55bf882c7f13 "fanotify: fix merging marks masks with FAN_ONDIR"
Fixes: b469e7e47c8a "fanotify: fix handling of events on child..."
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Signed-off-by: Sasha Levin

fanotify: fix merging marks masks with FAN_ONDIR

2020-05-20T06:20:35+00:00

commit 55bf882c7f13dda8bbe624040c6d5b4fbb812d16 upstream.

Change the logic of FAN_ONDIR in two ways that are similar to the logic
of FAN_EVENT_ON_CHILD, that was fixed in commit 54a307ba8d3c ("fanotify:
fix logic of events on child"):

1. The flag is meaningless in ignore mask
2. The flag refers only to events in the mask of the mark where it is set

This is what the fanotify_mark.2 man page says about FAN_ONDIR:
"Without this flag, only events for files are created."  It doesn't
say anything about setting this flag in ignore mask to stop getting
events on directories nor can I think of any setup where this capability
would be useful.

Currently, when marks masks are merged, the FAN_ONDIR flag set in one
mark affects the events that are set in another mark's mask and this
behavior causes unexpected results.  For example, a user adds a mark on a
directory with mask FAN_ATTRIB | FAN_ONDIR and a mount mark with mask
FAN_OPEN (without FAN_ONDIR).  An opendir() of that directory (which is
inside that mount) generates a FAN_OPEN event even though neither of the
marks requested to get open events on directories.

Link: https://lore.kernel.org/r/20200319151022.31456-10-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Cc: Rachel Sibley 
Signed-off-by: Greg Kroah-Hartman

fanotify: merge duplicate events on parent and child

2020-05-14T05:58:30+00:00

[ Upstream commit f367a62a7cad2447d835a9f14fc63997a9137246 ]

With inotify, when a watch is set on a directory and on its child, an
event on the child is reported twice, once with wd of the parent watch
and once with wd of the child watch without the filename.

With fanotify, when a watch is set on a directory and on its child, an
event on the child is reported twice, but it has the exact same
information - either an open file descriptor of the child or an encoded
fid of the child.

The reason that the two identical events are not merged is because the
object id used for merging events in the queue is the child inode in one
event and parent inode in the other.

For events with path or dentry data, use the victim inode instead of the
watched inode as the object id for event merging, so that the event
reported on parent will be merged with the event reported on the child.

Link: https://lore.kernel.org/r/20200319151022.31456-9-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Signed-off-by: Sasha Levin

fsnotify: replace inode pointer with an object id

2020-05-14T05:58:30+00:00

[ Upstream commit dfc2d2594e4a79204a3967585245f00644b8f838 ]

The event inode field is used only for comparison in queue merges and
cannot be dereferenced after handle_event(), because it does not hold a
refcount on the inode.

Replace it with an abstract id to do the same thing.

Link: https://lore.kernel.org/r/20200319151022.31456-8-amir73il@gmail.com
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
Signed-off-by: Sasha Levin

fs: call fsnotify_sb_delete after evict_inodes

2020-01-12T11:21:38+00:00

[ Upstream commit 1edc8eb2e93130e36ac74ac9c80913815a57d413 ]

When a filesystem is unmounted, we currently call fsnotify_sb_delete()
before evict_inodes(), which means that fsnotify_unmount_inodes()
must iterate over all inodes on the superblock looking for any inodes
with watches.  This is inefficient and can lead to livelocks as it
iterates over many unwatched inodes.

At this point, SB_ACTIVE is gone and dropping refcount to zero kicks
the inode out out immediately, so anything processed by
fsnotify_sb_delete / fsnotify_unmount_inodes gets evicted in that loop.

After that, the call to evict_inodes will evict everything else with a
zero refcount.

This should speed things up overall, and avoid livelocks in
fsnotify_unmount_inodes().

Signed-off-by: Eric Sandeen 
Reviewed-by: Jan Kara 
Signed-off-by: Al Viro 
Signed-off-by: Sasha Levin

fs: avoid softlockups in s_inodes iterators

2020-01-12T11:21:37+00:00

[ Upstream commit 04646aebd30b99f2cfa0182435a2ec252fcb16d0 ]

Anything that walks all inodes on sb->s_inodes list without rescheduling
risks softlockups.

Previous efforts were made in 2 functions, see:

c27d82f fs/drop_caches.c: avoid softlockups in drop_pagecache_sb()
ac05fbb inode: don't softlockup when evicting inodes

but there hasn't been an audit of all walkers, so do that now.  This
also consistently moves the cond_resched() calls to the bottom of each
loop in cases where it already exists.

One loop remains: remove_dquot_ref(), because I'm not quite sure how
to deal with that one w/o taking the i_lock.

Signed-off-by: Eric Sandeen 
Reviewed-by: Jan Kara 
Signed-off-by: Al Viro 
Signed-off-by: Sasha Levin