linux-stable.git/fs/notify, branch v3.16.67

fanotify: fix logic of events on child

2018-10-21T07:45:19+00:00

commit 54a307ba8d3cd00a3902337ffaae28f436eeb1a4 upstream.

When event on child inodes are sent to the parent inode mark and
parent inode mark was not marked with FAN_EVENT_ON_CHILD, the event
will not be delivered to the listener process. However, if the same
process also has a mount mark, the event to the parent inode will be
delivered regadless of the mount mark mask.

This behavior is incorrect in the case where the mount mark mask does
not contain the specific event type. For example, the process adds
a mark on a directory with mask FAN_MODIFY (without FAN_EVENT_ON_CHILD)
and a mount mark with mask FAN_CLOSE_NOWRITE (without FAN_ONDIR).

A modify event on a file inside that directory (and inside that mount)
should not create a FAN_MODIFY event, because neither of the marks
requested to get that event on the file.

Fixes: 1968f5eed54c ("fanotify: use both marks when possible")
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

dentry name snapshots

2017-08-26T01:14:48+00:00

commit 49d31c2f389acfe83417083e1208422b4091cd9e upstream.

take_dentry_name_snapshot() takes a safe snapshot of dentry name;
if the name is a short one, it gets copied into caller-supplied
structure, otherwise an extra reference to external name is grabbed
(those are never modified).  In either case the pointer to stable
string is stored into the same structure.

dentry must be held by the caller of take_dentry_name_snapshot(),
but may be freely dropped afterwards - the snapshot will stay
until destroyed by release_dentry_name_snapshot().

Intended use:
	struct name_snapshot s;

	take_dentry_name_snapshot(&s, dentry);
	...
	access s.name
	...
	release_dentry_name_snapshot(&s);

Replaces fsnotify_oldname_...(), gets used in fsnotify to obtain the name
to pass down with event.

Signed-off-by: Al Viro 
[carnil: backport 4.9: adjust context]
[bwh: Backported to 3.16:
 - External names are not ref-counted, so copy them
 - Adjust context]
Signed-off-by: Ben Hutchings

fanotify: don't expose EOPENSTALE to userspace

2017-08-26T01:14:39+00:00

commit 4ff33aafd32e084f5ee7faa54ba06e95f8b1b8af upstream.

When delivering an event to userspace for a file on an NFS share,
if the file is deleted on server side before user reads the event,
user will not get the event.

If the event queue contained several events, the stale event is
quietly dropped and read() returns to user with events read so far
in the buffer.

If the event queue contains a single stale event or if the stale
event is a permission event, read() returns to user with the kernel
internal error code 518 (EOPENSTALE), which is not a POSIX error code.

Check the internal return value -EOPENSTALE in fanotify_read(), just
the same as it is checked in path_openat() and drop the event in the
cases that it is not already dropped.

This is a reproducer from Marko Rauhamaa:

Just take the example program listed under "man fanotify" ("fantest")
and follow these steps:

    ==============================================================
    NFS Server    NFS Client(1)     NFS Client(2)
    ==============================================================
    # echo foo >/nfsshare/bar.txt
                  # cat /nfsshare/bar.txt
                  foo
                                    # ./fantest /nfsshare
                                    Press enter key to terminate.
                                    Listening for events.
    # rm -f /nfsshare/bar.txt
                  # cat /nfsshare/bar.txt
                                    read: Unknown error 518
                  cat: /nfsshare/bar.txt: Operation not permitted
    ==============================================================

where NFS Client (1) and (2) are two terminal sessions on a single NFS
Client machine.

Reported-by: Marko Rauhamaa 
Tested-by: Marko Rauhamaa 
Cc: 
Signed-off-by: Amir Goldstein 
Signed-off-by: Jan Kara 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

fsnotify: Fix possible use-after-free in inode iteration on umount

2017-03-16T02:26:35+00:00

commit 5716863e0f8251d3360d4cbfc0e44e08007075df upstream.

fsnotify_unmount_inodes() plays complex tricks to pin next inode in the
sb->s_inodes list when iterating over all inodes. Furthermore the code has a
bug that if the current inode is the last on i_sb_list that does not have e.g.
I_FREEING set, then we leave next_i pointing to inode which may get removed
from the i_sb_list once we drop s_inode_list_lock thus resulting in
use-after-free issues (usually manifesting as infinite looping in
fsnotify_unmount_inodes()).

Fix the problem by keeping current inode pinned somewhat longer. Then we can
make the code much simpler and standard.

Signed-off-by: Jan Kara 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

fs/notify/inode_mark.c: use list_next_entry in fsnotify_unmount_inodes

2017-03-16T02:26:34+00:00

commit 1deaf9d19776916cd1c83191503bf327319a301a upstream.

To make the intention clearer, use list_next_entry instead of
list_entry.

Signed-off-by: Geliang Tang 
Reviewed-by: Jan Kara 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings

fanotify: fix list corruption in fanotify_get_response()

2016-11-20T01:17:33+00:00

commit 96d41019e3ac55f6f0115b0ce97e4f24a3d636d2 upstream.

fanotify_get_response() calls fsnotify_remove_event() when it finds that
group is being released from fanotify_release() (bypass_perm is set).

However the event it removes need not be only in the group's notification
queue but it can have already moved to access_list (userspace read the
event before closing the fanotify instance fd) which is protected by a
different lock.  Thus when fsnotify_remove_event() races with
fanotify_release() operating on access_list, the list can get corrupted.

Fix the problem by moving all the logic removing permission events from
the lists to one place - fanotify_release().

Fixes: 5838d4442bd5 ("fanotify: fix double free of pending permission events")
Link: http://lkml.kernel.org/r/1473797711-14111-3-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara 
Reported-by: Miklos Szeredi 
Tested-by: Miklos Szeredi 
Reviewed-by: Miklos Szeredi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
[bwh: Backported to 3.16:
 - s/fsnotify_remove_first_event/fsnotify_remove_notify_event/
 - Adjust context]
Signed-off-by: Ben Hutchings

fsnotify: add a way to stop queueing events on group shutdown

2016-11-20T01:17:33+00:00

commit 12703dbfeb15402260e7554d32a34ac40c233990 upstream.

Implement a function that can be called when a group is being shutdown
to stop queueing new events to the group.  Fanotify will use this.

Fixes: 5838d4442bd5 ("fanotify: fix double free of pending permission events")
Link: http://lkml.kernel.org/r/1473797711-14111-2-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara 
Reviewed-by: Miklos Szeredi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings

fsnotify: fix oops in fsnotify_clear_marks_by_group_flags()

2015-08-27T11:08:16+00:00

commit 8f2f3eb59dff4ec538de55f2e0592fec85966aab upstream.

fsnotify_clear_marks_by_group_flags() can race with
fsnotify_destroy_marks() so that when fsnotify_destroy_mark_locked()
drops mark_mutex, a mark from the list iterated by
fsnotify_clear_marks_by_group_flags() can be freed and thus the next
entry pointer we have cached may become stale and we dereference free
memory.

Fix the problem by first moving marks to free to a special private list
and then always free the first entry in the special list.  This method
is safe even when entries from the list can disappear once we drop the
lock.

Signed-off-by: Jan Kara 
Reported-by: Ashish Sangwan 
Reviewed-by: Ashish Sangwan 
Cc: Lino Sanfilippo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Luis Henriques

fsnotify: next_i is freed during fsnotify_unmount_inodes.

2015-01-16T14:34:38+00:00

commit 6424babfd68dd8a83d9c60a5242d27038856599f upstream.

During file system stress testing on 3.10 and 3.12 based kernels, the
umount command occasionally hung in fsnotify_unmount_inodes in the
section of code:

                spin_lock(&inode->i_lock);
                if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) {
                        spin_unlock(&inode->i_lock);
                        continue;
                }

As this section of code holds the global inode_sb_list_lock, eventually
the system hangs trying to acquire the lock.

Multiple crash dumps showed:

The inode->i_state == 0x60 and i_count == 0 and i_sb_list would point
back at itself.  As this is not the value of list upon entry to the
function, the kernel never exits the loop.

To help narrow down problem, the call to list_del_init in
inode_sb_list_del was changed to list_del.  This poisons the pointers in
the i_sb_list and causes a kernel to panic if it transverse a freed
inode.

Subsequent stress testing paniced in fsnotify_unmount_inodes at the
bottom of the list_for_each_entry_safe loop showing next_i had become
free.

We believe the root cause of the problem is that next_i is being freed
during the window of time that the list_for_each_entry_safe loop
temporarily releases inode_sb_list_lock to call fsnotify and
fsnotify_inode_delete.

The code in fsnotify_unmount_inodes attempts to prevent the freeing of
inode and next_i by calling __iget.  However, the code doesn't do the
__iget call on next_i

	if i_count == 0 or
	if i_state & (I_FREEING | I_WILL_FREE)

The patch addresses this issue by advancing next_i in the above two cases
until we either find a next_i which we can __iget or we reach the end of
the list.  This makes the handling of next_i more closely match the
handling of the variable "inode."

The time to reproduce the hang is highly variable (from hours to days.) We
ran the stress test on a 3.10 kernel with the proposed patch for a week
without failure.

During list_for_each_entry_safe, next_i is becoming free causing
the loop to never terminate.  Advance next_i in those cases where
__iget is not done.

Signed-off-by: Jerry Hoemann 
Cc: Jeff Kirsher 
Cc: Ken Helias 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Cc: Jan Kara 
Signed-off-by: Luis Henriques

move d_rcu from overlapping d_child to overlapping d_alias

2015-01-15T10:44:58+00:00

commit 946e51f2bf37f1656916eb75bd0742ba33983c28 upstream.

Signed-off-by: Al Viro 
[bwh: Backported to 3.16:
 - Apply name changes in all the different places we use d_alias and d_child
 - Adjust context]
Signed-off-by: Ben Hutchings 
Cc: Moritz Muehlenhoff 
Signed-off-by: Luis Henriques