[PATCH v5 0/5] ceph: add support for snapshot names encryption

["Luís Henriques" <lhenriques@suse.de>]

Hi!

And here's yet another revision.  The main difference from v4 is the
addition of a patch to prevent the creation of snapshots in directories
that are encrypted but that are not unlocked (i.e. no key available).

As before, the following ceph PRs are required:

  mds: add protection from clients without fscrypt support #45073
  mds: use the whole string as the snapshot long name #45192
  mds: support alternate names for snapshots #45224
  mds: limit the snapshot names to 240 characters #45312

Changes since v4:

- Explicitly added the encoding base for kstrtou64() as we do know that
  the inode numbers are in decimal.

- New patch to prevent the creation of snapshots in encrypted directories
  that do not have the key loaded.

Changes since v3:

- Fixed WARN_ON() in ceph_encode_encrypted_dname()

- Updated documentation and copyright notice for the base64
  encoding/decoding implementaiton which was taken from the fscrypt base.

Changes since v2:

- Use ceph_find_inode() instead of ceph_get_inode() for finding a snapshot
  parent in function parse_longname().  I've also added a fallback to
  ceph_get_inode() in case we fail to find the inode.  This may happen if,
  for example, the mount root doesn't include that inode.  The iput() was
  also complemented by a discard_new_inode() if the inode is in the I_NEW
  state. (patch 0002)

- Move the check for '_' snapshots further up in the ceph_fname_to_usr()
  and ceph_encode_encrypted_dname().  This fixes the case pointed out by
  Xiubo in v2. (patch 0002)

- Use NAME_MAX for tmp arrays (patch 0002)

- Added an extra patch for replacing the base64url encoding by a different
  encoding standard, the one used for IMAP mailboxes (which uses '+' and
  ',' instead of '-' and '_').  This should fix the issue with snapshot
  names starting with '_'. (patch 0003)

Changes since v1:

- Dropped the dentry->d_flags change in ceph_mkdir().  Thanks to Xiubo
  suggestion, patch 0001 now skips calling ceph_fscrypt_prepare_context()
  if we're handling a snapshot.

- Added error handling to ceph_get_snapdir() in patch 0001 (Jeff had
  already pointed that out but I forgot to include that change in previous
  revision).

- Rebased patch 0002 to the latest wip-fscrypt branch.

- Added some documentation regarding snapshots naming restrictions.


Luís Henriques (5):
  ceph: add support for encrypted snapshot names
  ceph: add support for handling encrypted snapshot names
  ceph: update documentation regarding snapshot naming limitations
  ceph: replace base64url by the encoding used for mailbox names
  ceph: prevent snapshots to be created in encrypted locked directories

 Documentation/filesystems/ceph.rst |  10 ++
 fs/ceph/crypto.c                   | 252 +++++++++++++++++++++++++----
 fs/ceph/crypto.h                   |  14 +-
 fs/ceph/dir.c                      |   7 +-
 fs/ceph/inode.c                    |  33 +++-
 5 files changed, 278 insertions(+), 38 deletions(-)