linux.git/fs/overlayfs, branch v5.8

ovl: fix lookup of indexed hardlinks with metacopy

2020-07-16T05:24:47+00:00

We recently moved setting inode flag OVL_UPPERDATA to ovl_lookup().

When looking up an overlay dentry, upperdentry may be found by index
and not by name.  In that case, we fail to read the metacopy xattr
and falsly set the OVL_UPPERDATA on the overlay inode.

This caused a regression in xfstest overlay/033 when run with
OVERLAY_MOUNT_OPTIONS="-o metacopy=on".

Fixes: 28166ab3c875 ("ovl: initialize OVL_UPPERDATA in ovl_lookup()")
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: fix unneeded call to ovl_change_flags()

2020-07-16T05:24:47+00:00

The check if user has changed the overlay file was wrong, causing unneeded
call to ovl_change_flags() including taking f_lock on every file access.

Fixes: d989903058a8 ("ovl: do not generate duplicate fsnotify events for "fake" path")
Cc:  # v4.19+
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: fix mount option checks for nfs_export with no upperdir

2020-07-15T22:11:15+00:00

Without upperdir mount option, there is no index dir and the dependency
checks nfs_export => index for mount options parsing are incorrect.

Allow the combination nfs_export=on,index=off with no upperdir and move
the check for dependency redirect_dir=nofollow for non-upper mount case
to mount options parsing.

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: force read-only sb on failure to create index dir

2020-07-15T22:11:15+00:00

With index feature enabled, on failure to create index dir, overlay is
being mounted read-only.  However, we do not forbid user to remount overlay
read-write.  Fix that by setting ofs->workdir to NULL, which prevents
remount read-write.

Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: fix regression with re-formatted lower squashfs

2020-07-15T22:10:31+00:00

Commit 9df085f3c9a2 ("ovl: relax requirement for non null uuid of lower
fs") relaxed the requirement for non null uuid with single lower layer to
allow enabling index and nfs_export features with single lower squashfs.

Fabian reported a regression in a setup when overlay re-uses an existing
upper layer and re-formats the lower squashfs image.  Because squashfs
has no uuid, the origin xattr in upper layer are decoded from the new
lower layer where they may resolve to a wrong origin file and user may
get an ESTALE or EIO error on lookup.

To avoid the reported regression while still allowing the new features
with single lower squashfs, do not allow decoding origin with lower null
uuid unless user opted-in to one of the new features that require
following the lower inode of non-dir upper (index, xino, metacopy).

Reported-by: Fabian 
Link: https://lore.kernel.org/linux-unionfs/32532923.JtPX5UtSzP@fgdesktop/
Fixes: 9df085f3c9a2 ("ovl: relax requirement for non null uuid of lower fs")
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: fix oops in ovl_indexdir_cleanup() with nfs_export=on

2020-07-15T22:09:59+00:00

Mounting with nfs_export=on, xfstests overlay/031 triggers a kernel panic
since v5.8-rc1 overlayfs updates.

 overlayfs: orphan index entry (index/00fb1..., ftype=4000, nlink=2)
 BUG: kernel NULL pointer dereference, address: 0000000000000030
 RIP: 0010:ovl_cleanup_and_whiteout+0x28/0x220 [overlay]

Bisect point at commit c21c839b8448 ("ovl: whiteout inode sharing")

Minimal reproducer:
--------------------------------------------------
rm -rf l u w m
mkdir -p l u w m
mkdir -p l/testdir
touch l/testdir/testfile
mount -t overlay -o lowerdir=l,upperdir=u,workdir=w,nfs_export=on overlay m
echo 1 > m/testdir/testfile
umount m
rm -rf u/testdir
mount -t overlay -o lowerdir=l,upperdir=u,workdir=w,nfs_export=on overlay m
umount m
--------------------------------------------------

When mount with nfs_export=on, and fail to verify an orphan index, we're
cleaning this index from indexdir by calling ovl_cleanup_and_whiteout().
This dereferences ofs->workdir, that was earlier set to NULL.

The design was that ovl->workdir will point at ovl->indexdir, but we are
assigning ofs->indexdir to ofs->workdir only after ovl_indexdir_cleanup().
There is no reason not to do it sooner, because once we get success from
ofs->indexdir = ovl_workdir_create(... there is no turning back.

Reported-and-tested-by: Murphy Zhou 
Fixes: c21c839b8448 ("ovl: whiteout inode sharing")
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: relax WARN_ON() when decoding lower directory file handle

2020-07-15T22:09:17+00:00

Decoding a lower directory file handle to overlay path with cold
inode/dentry cache may go as follows:

1. Decode real lower file handle to lower dir path
2. Check if lower dir is indexed (was copied up)
3. If indexed, get the upper dir path from index
4. Lookup upper dir path in overlay
5. If overlay path found, verify that overlay lower is the lower dir
   from step 1

On failure to verify step 5 above, user will get an ESTALE error and a
WARN_ON will be printed.

A mismatch in step 5 could be a result of lower directory that was renamed
while overlay was offline, after that lower directory has been copied up
and indexed.

This is a scripted reproducer based on xfstest overlay/052:

  # Create lower subdir
  create_dirs
  create_test_files $lower/lowertestdir/subdir
  mount_dirs
  # Copy up lower dir and encode lower subdir file handle
  touch $SCRATCH_MNT/lowertestdir
  test_file_handles $SCRATCH_MNT/lowertestdir/subdir -p -o $tmp.fhandle
  # Rename lower dir offline
  unmount_dirs
  mv $lower/lowertestdir $lower/lowertestdir.new/
  mount_dirs
  # Attempt to decode lower subdir file handle
  test_file_handles $SCRATCH_MNT -p -i $tmp.fhandle

Since this WARN_ON() can be triggered by user we need to relax it.

Fixes: 4b91c30a5a19 ("ovl: lookup connected ancestor of dir in inode cache")
Cc:  # v4.16+
Signed-off-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: remove not used argument in ovl_check_origin

2020-07-15T22:06:16+00:00

ovl_check_origin outparam 'ctrp' argument not used by caller.  So remove
this argument.

Signed-off-by: youngjun 
Reviewed-by: Amir Goldstein 
Signed-off-by: Miklos Szeredi

ovl: change ovl_copy_up_flags static

2020-07-15T22:06:16+00:00

"ovl_copy_up_flags" is used in copy_up.c.
so, change it static.

Signed-off-by: youngjun 
Signed-off-by: Miklos Szeredi

ovl: inode reference leak in ovl_is_inuse true case.

2020-07-15T22:05:40+00:00

When "ovl_is_inuse" true case, trap inode reference not put.  plus adding
the comment explaining sequence of ovl_is_inuse after ovl_setup_trap.

Fixes: 0be0bfd2de9d ("ovl: fix regression caused by overlapping layers detection")
Cc:  # v4.19+
Reviewed-by: Amir Goldstein 
Signed-off-by: youngjun 
Signed-off-by: Miklos Szeredi