linux-stable.git/fs/overlayfs/export.c, branch linux-6.2.y

ovl: do not reconnect upper index records in ovl_indexdir_cleanup()

2022-12-08T09:49:46+00:00

ovl_indexdir_cleanup() is called on mount of overayfs with nfs_export
feature to cleanup stale index records for lower and upper files that have
been deleted while overlayfs was offline.

This has the side effect (good or bad) of pre populating inode cache with
all the copied up upper inodes, while verifying the index entries.

For copied up directories, the upper file handles are decoded to conncted
upper dentries.  This has the even bigger side effect of reading the
content of all the parent upper directories which may take significantly
more time and IO than just reading the upper inodes.

Do not request connceted upper dentries for verifying upper directory index
entries, because we have no use for the connected dentry.

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

ovl: fix comment typos

2022-12-08T09:49:46+00:00

Fix two typos.

Reported-by: k2ci 
Signed-off-by: Jiangshan Yi 
Signed-off-by: Miklos Szeredi

ovl: Use "buf" flexible array for memcpy() destination

2022-12-08T09:49:46+00:00

The "buf" flexible array needs to be the memcpy() destination to avoid
false positive run-time warning from the recent FORTIFY_SOURCE
hardening:

  memcpy: detected field-spanning write (size 93) of single field "&fh->fb"
  at fs/overlayfs/export.c:799 (size 21)

Reported-by: syzbot+9d14351a171d0d1c7955@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/000000000000763a6c05e95a5985@google.com/
Signed-off-by: Kees Cook 
Reviewed-by: Gustavo A. R. Silva 
Signed-off-by: Miklos Szeredi

ovl: drop WARN_ON() dentry is NULL in ovl_encode_fh()

2022-07-28T13:00:57+00:00

Some code paths cannot guarantee the inode have any dentry alias. So
WARN_ON() all !dentry may flood the kernel logs.

For example, when an overlayfs inode is watched by inotifywait (1), and
someone is trying to read the /proc/$(pidof inotifywait)/fdinfo/INOTIFY_FD,
at that time if the dentry has been reclaimed by kernel (such as
echo 2 > /proc/sys/vm/drop_caches), there will be a WARN_ON(). The
printed call stack would be like:

    ? show_mark_fhandle+0xf0/0xf0
    show_mark_fhandle+0x4a/0xf0
    ? show_mark_fhandle+0xf0/0xf0
    ? seq_vprintf+0x30/0x50
    ? seq_printf+0x53/0x70
    ? show_mark_fhandle+0xf0/0xf0
    inotify_fdinfo+0x70/0x90
    show_fdinfo.isra.4+0x53/0x70
    seq_show+0x130/0x170
    seq_read+0x153/0x440
    vfs_read+0x94/0x150
    ksys_read+0x5f/0xe0
    do_syscall_64+0x59/0x1e0
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

So let's drop WARN_ON() to avoid kernel log flooding.

Reported-by: Hongbo Yin 
Signed-off-by: Jiachen Zhang 
Signed-off-by: Tianci Zhang 
Fixes: 8ed5eec9d6c4 ("ovl: encode pure upper file handles")
Cc:  # v4.16
Signed-off-by: Miklos Szeredi

ovl: handle idmappings for layer lookup

2022-04-28T14:31:12+00:00

Make the two places where lookup helpers can be called either on lower
or upper layers take the mount's idmapping into account. To this end we
pass down the mount in struct ovl_lookup_data. It can later also be used
to construct struct path for various other helpers. This is needed to
support idmapped base layers with overlay.

Cc: 
Tested-by: Giuseppe Scrivano 
Reviewed-by: Amir Goldstein 
Signed-off-by: Christian Brauner (Microsoft) 
Signed-off-by: Miklos Szeredi

ovl: fix uninitialized pointer read in ovl_lookup_real_one()

2021-08-10T08:21:30+00:00

One error path can result in release_dentry_name_snapshot() being called
before "name" was initialized by take_dentry_name_snapshot().

Fix by moving the release_dentry_name_snapshot() to immediately after the
only use.

Reported-by: Colin Ian King 
Signed-off-by: Miklos Szeredi

ovl: propagate ovl_fs to ovl_decode_real_fh and ovl_encode_real_fh

2020-11-12T10:31:55+00:00

This will be used in next patch to be able to change uuid checks and add
uuid nullification based on ofs->config.index for a new "uuid=off" mode.

Reviewed-by: Amir Goldstein 
Signed-off-by: Pavel Tikhomirov 
Signed-off-by: Miklos Szeredi

ovl: pass ovl_fs down to functions accessing private xattrs

2020-09-02T08:58:49+00:00

This paves the way for optionally using the "user.overlay." xattr
namespace.

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: add accessor for ofs->upper_mnt

2020-06-04T08:48:19+00:00

Next patch will remove ofs->upper_mnt, so add an accessor function for this
field.

Signed-off-by: Miklos Szeredi