linux.git/fs/overlayfs, branch v6.6

ovl: temporarily disable appending lowedirs

2023-10-14T19:42:45+00:00

Kernel v6.5 converted overlayfs to new mount api.
As an added bonus, it also added a feature to allow appending lowerdirs
using lowerdir=:/lower2,lowerdir=::/data3 syntax.

This new syntax has raised some concerns regarding escaping of colons.
We decided to try and disable this syntax, which hasn't been in the wild
for so long and introduce it again in 6.7 using explicit mount options
lowerdir+=/lower2,datadir+=/data3.

Suggested-by: Miklos Szeredi 
Link: https://lore.kernel.org/r/CAJfpegsr3A4YgF2YBevWa6n3=AcP7hNndG6EPMu3ncvV-AM71A@mail.gmail.com/
Fixes: b36a5780cb44 ("ovl: modify layer parameter parsing")
Signed-off-by: Amir Goldstein

ovl: fix regression in showing lowerdir mount option

2023-10-14T06:24:11+00:00

Before commit b36a5780cb44 ("ovl: modify layer parameter parsing"),
spaces and commas in lowerdir mount option value used to be escaped using
seq_show_option().

In current upstream, when lowerdir value has a space, it is not escaped
in /proc/mounts, e.g.:

  none /mnt overlay rw,relatime,lowerdir=l l,upperdir=u,workdir=w 0 0

which results in broken output of the mount utility:

  none on /mnt type overlay (rw,relatime,lowerdir=l)

Store the original lowerdir mount options before unescaping and show
them using the same escaping used for seq_show_option() in addition to
escaping the colon separator character.

Fixes: b36a5780cb44 ("ovl: modify layer parameter parsing")
Signed-off-by: Amir Goldstein

ovl: fix regression in parsing of mount options with escaped comma

2023-10-12T15:53:37+00:00

Ever since commit 91c77947133f ("ovl: allow filenames with comma"), the
following example was legit overlayfs mount options:

  mount -t overlay overlay -o 'lowerdir=/tmp/a\,b/lower' /mnt

The conversion to new mount api moved to using the common helper
generic_parse_monolithic() and discarded the specialized ovl_next_opt()
option separator.

Bring back ovl_next_opt() and use vfs_parse_monolithic_sep() to fix the
regression.

Reported-by: Ryan Hendrickson 
Closes: https://lore.kernel.org/r/8da307fb-9318-cf78-8a27-ba5c5a0aef6d@alum.mit.edu/
Fixes: 1784fbc2ed9c ("ovl: port to new mount api")
Signed-off-by: Amir Goldstein

ovl: fix NULL pointer defer when encoding non-decodable lower fid

2023-10-03T06:24:11+00:00

A wrong return value from ovl_check_encode_origin() would cause
ovl_dentry_to_fid() to try to encode fid from NULL upper dentry.

Reported-by: syzbot+2208f82282740c1c8915@syzkaller.appspotmail.com
Fixes: 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles")
Signed-off-by: Amir Goldstein

ovl: make use of ->layers safe in rcu pathwalk

2023-10-02T14:45:02+00:00

ovl_permission() accesses ->layers[...].mnt; we can't have ->layers
freed without an RCU delay on fs shutdown.

Fortunately, kern_unmount_array() that is used to drop those mounts
does include an RCU delay, so freeing is delayed; unfortunately, the
array passed to kern_unmount_array() is formed by mangling ->layers
contents and that happens without any delays.

The ->layers[...].name string entries are used to store the strings to
display in "lowerdir=..." by ovl_show_options().  Those entries are not
accessed in RCU walk.

Move the name strings into a separate array ofs->config.lowerdirs and
reuse the ofs->config.lowerdirs array as the temporary mount array to
pass to kern_unmount_array().

Reported-by: Al Viro 
Link: https://lore.kernel.org/r/20231002023711.GP3389589@ZenIV/
Acked-by: Miklos Szeredi 
Signed-off-by: Amir Goldstein

ovl: fetch inode once in ovl_dentry_revalidate_common()

2023-10-02T14:44:19+00:00

d_inode_rcu() is right - we might be in rcu pathwalk;
however, OVL_E() hides plain d_inode() on the same dentry...

Fixes: a6ff2bc0be17 ("ovl: use OVL_E() and OVL_E_FLAGS() accessors")
Signed-off-by: Al Viro 
Signed-off-by: Amir Goldstein

ovl: move freeing ovl_entry past rcu delay

2023-10-02T14:44:06+00:00

... into ->free_inode(), that is.

Fixes: 0af950f57fef "ovl: move ovl_entry into ovl_inode"
Signed-off-by: Al Viro 
Signed-off-by: Amir Goldstein

ovl: fix file reference leak when submitting aio

2023-10-02T10:08:31+00:00

Commit 724768a39374 ("ovl: fix incorrect fdput() on aio completion")
took a refcount on real file before submitting aio, but forgot to
avoid clearing FDPUT_FPUT from real.flags stack variable.
This can result in a file reference leak.

Fixes: 724768a39374 ("ovl: fix incorrect fdput() on aio completion")
Reported-by: Gil Lev 
Signed-off-by: Amir Goldstein

Merge tag 'v6.6-rc4.vfs.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs

2023-09-26T15:50:30+00:00

Pull vfs fixes from Christian Brauner:
 "This contains the usual miscellaneous fixes and cleanups for vfs and
  individual fses:

  Fixes:
   - Revert ki_pos on error from buffered writes for direct io fallback
   - Add missing documentation for block device and superblock handling
     for changes merged this cycle
   - Fix reiserfs flexible array usage
   - Ensure that overlayfs sets ctime when setting mtime and atime
   - Disable deferred caller completions with overlayfs writes until
     proper support exists

  Cleanups:
   - Remove duplicate initialization in pipe code
   - Annotate aio kioctx_table with __counted_by"

* tag 'v6.6-rc4.vfs.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
  overlayfs: set ctime when setting mtime and atime
  ntfs3: put resources during ntfs_fill_super()
  ovl: disable IOCB_DIO_CALLER_COMP
  porting: document superblock as block device holder
  porting: document new block device opening order
  fs/pipe: remove duplicate "offset" initializer
  fs-writeback: do not requeue a clean inode having skipped pages
  aio: Annotate struct kioctx_table with __counted_by
  direct_write_fallback(): on error revert the ->ki_pos update from buffered write
  reiserfs: Replace 1-element array with C99 style flex-array

overlayfs: set ctime when setting mtime and atime

2023-09-25T12:53:54+00:00

Nathan reported that he was seeing the new warning in
setattr_copy_mgtime pop when starting podman containers. Overlayfs is
trying to set the atime and mtime via notify_change without also
setting the ctime.

POSIX states that when the atime and mtime are updated via utimes() that
we must also update the ctime to the current time. The situation with
overlayfs copy-up is analogies, so add ATTR_CTIME to the bitmask.
notify_change will fill in the value.

Reported-by: Nathan Chancellor 
Signed-off-by: Jeff Layton 
Tested-by: Nathan Chancellor 
Acked-by: Christian Brauner 
Acked-by: Amir Goldstein 
Message-Id: <20230913-ctime-v1-1-c6bc509cbc27@kernel.org>
Signed-off-by: Christian Brauner