Pull overlayfs fixes from Miklos Szeredi:
 "Fix a regression introduced in v5.15, affecting copy up of files with
  'noatime' or 'sync' attributes to a tmpfs upper layer"

* tag 'ovl-fixes-5.17-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: don't fail copy up if no fileattr support on upper
  ovl: fix NULL pointer dereference in copy up warning

Christoph Fritz is reporting that failure to copy up fileattr when upper
doesn't support fileattr or xattr results in a regression.

Return success in these failure cases; this reverts overlayfs to the old
behavior.

Add a pr_warn_once() in these cases to still let the user know about the
copy up failures.

Reported-by: Christoph Fritz <chf.fritz@googlemail.com>
Fixes: 72db82115d2b ("ovl: copy up sync/noatime fileattr flags")
Cc: <stable@vger.kernel.org> # v5.15
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

This patch is fixing a NULL pointer dereference to get a recently
introduced warning message working.

Fixes: 5b0a414d06c3 ("ovl: fix filattr copy-up failure")
Signed-off-by: Christoph Fritz <chf.fritz@googlemail.com>
Cc: <stable@vger.kernel.org> # v5.15
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Multiple places open-code the same check to determine whether a given
mount is idmapped. Introduce a simple helper function that can be used
instead. This allows us to get rid of the fragile open-coding. We will
later change the check that is used to determine whether a given mount
is idmapped. Introducing a helper allows us to do this in a single
place instead of doing it for multiple places.

Link: https://lore.kernel.org/r/20211123114227.3124056-2-brauner@kernel.org (v1)
Link: https://lore.kernel.org/r/20211130121032.3753852-2-brauner@kernel.org (v2)
Link: https://lore.kernel.org/r/20211203111707.3901969-2-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Pull overlayfs updates from Miklos Szeredi:

 - Fix a regression introduced in the last cycle

 - Fix a use-after-free in the AIO path

 - Fix a bogus warning reported by syzbot

* tag 'ovl-update-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: fix filattr copy-up failure
  ovl: fix warning in ovl_create_real()
  ovl: fix use after free in struct ovl_aio_req

This regression can be reproduced with ntfs-3g and overlayfs:

  mkdir lower upper work overlay
  dd if=/dev/zero of=ntfs.raw bs=1M count=2
  mkntfs -F ntfs.raw
  mount ntfs.raw lower
  touch lower/file.txt
  mount -t overlay -o lowerdir=lower,upperdir=upper,workdir=work - overlay
  mv overlay/file.txt overlay/file2.txt

mv fails and (misleadingly) prints

  mv: cannot move 'overlay/file.txt' to a subdirectory of itself, 'overlay/file2.txt'

The reason is that ovl_copy_fileattr() is triggered due to S_NOATIME being
set on all inodes (by fuse) regardless of fileattr.

ovl_copy_fileattr() tries to retrieve file attributes from lower file, but
that fails because filesystem does not support this ioctl (this should fail
with ENOTTY, but ntfs-3g return EINVAL instead).  This failure is
propagated to origial operation (in this case rename) that triggered the
copy-up.

The fix is to ignore ENOTTY and EINVAL errors from fileattr_get() in copy
up.  This also requires turning the internal ENOIOCTLCMD into ENOTTY.

As a further measure to prevent unnecessary failures, only try the
fileattr_get/set on upper if there are any flags to copy up.

Side note: a number of filesystems set S_NOATIME (and sometimes other inode
flags) irrespective of fileattr flags.  This causes unnecessary calls
during copy up, which might lead to a performance issue, especially if
latency is high.  To fix this, the kernel would need to differentiate
between the two cases.  E.g. introduce SB_NOATIME_UPDATE, a per-sb variant
of S_NOATIME.  SB_NOATIME doesn't work, because that's interpreted as
"filesystem doesn't store an atime attribute"

Reported-and-tested-by: Kevin Locke <kevin@kevinlocke.name>
Fixes: 72db82115d2b ("ovl: copy up sync/noatime fileattr flags")
Cc: <stable@vger.kernel.org> # v5.15
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Syzbot triggered the following warning in ovl_workdir_create() ->
ovl_create_real():

	if (!err && WARN_ON(!newdentry->d_inode)) {

The reason is that the cgroup2 filesystem returns from mkdir without
instantiating the new dentry.

Weird filesystems such as this will be rejected by overlayfs at a later
stage during setup, but to prevent such a warning, call ovl_mkdir_real()
directly from ovl_workdir_create() and reject this case early.

Reported-and-tested-by: syzbot+75eab84fd0af9e8bf66b@syzkaller.appspotmail.com
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Example for triggering use after free in a overlay on ext4 setup:

aio_read
  ovl_read_iter
    vfs_iter_read
      ext4_file_read_iter
        ext4_dio_read_iter
          iomap_dio_rw -> -EIOCBQUEUED
          /*
	   * Here IO is completed in a separate thread,
	   * ovl_aio_cleanup_handler() frees aio_req which has iocb embedded
	   */
          file_accessed(iocb->ki_filp); /**BOOM**/

Fix by introducing a refcount in ovl_aio_req similarly to aio_kiocb.  This
guarantees that iocb is only freed after vfs_read/write_iter() returns on
underlying fs.

Fixes: 2406a307ac7d ("ovl: implement async IO routines")
Signed-off-by: yangerkun <yangerkun@huawei.com>
Link: https://lore.kernel.org/r/20210930032228.3199690-3-yangerkun@huawei.com/
Cc: <stable@vger.kernel.org> # v5.6
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

The second argument was only used by the USB gadget code, yet everyone
pays the overhead of passing a zero to be passed into aio, where it
ends up being part of the aio res2 value.

Now that everybody is passing in zero, kill off the extra argument.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Normally the check at open time suffices, but e.g loop device does set
IOCB_DIRECT after doing its own checks (which are not sufficent for
overlayfs).

Make sure we don't call the underlying filesystem read/write method with
the IOCB_DIRECT if it's not supported.

Reported-by: Huang Jianan <huangjianan@oppo.com>
Fixes: 16914e6fc7e1 ("ovl: add ovl_read_iter()")
Cc: <stable@vger.kernel.org> # v4.19
Tested-by: Huang Jianan <huangjianan@oppo.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>