[v2,0/5] fscrypt: add support for data_unit_size < fs_block_size

Message

Eric Biggers Sept. 14, 2023, 8:12 a.m. UTC

This patchset adds support for configuring the granularity of file
contents encryption (a.k.a. the "crypto data unit size") to be less than
the filesystem block size.  The main use case for this is to support
inline crypto hardware that only supports a data unit size that is less
than the FS block size being used.  Another possible use case is to
support direct I/O on encrypted files without the FS block alignment
restriction.  Note that decreasing the crypto data unit size decreases
efficiency, so this feature should only be used when necessary.

For full details, see patch 5 which adds the actual feature.  Patches
1-4 are preparatory patches.

I've written an xfstest that verifies that when a sub-block data unit
size is selected, the data on-disk is encrypted correctly with that data
unit size.  I'll be sending that out separately.  Other testing of this
patchset with xfstests has gone well, though it turns out a sub-block
data unit size doesn't really work with IV_INO_LBLK_* yet (see patch 5).

This patchset will cause some conflicts in the extent-based encryption
patches that the btrfs folks are working on, as both are touching file
contents encryption, but logically they are orthogonal features.

This patchset is based on v6.6-rc1.

Changed in v2:
  - Rebased onto v6.6-rc1 and took into account CephFS's recent addition
    of support for fscrypt
  - Narrowed the focus somewhat by dropping the attempted support for
    IV_INO_LBLK_32 and clearly documenting what is considered out of
    scope for now
  - Other cleanups

Eric Biggers (5):
  fscrypt: make it extra clear that key_prefix is deprecated
  fscrypt: make the bounce page pool opt-in instead of opt-out
  fscrypt: use s_maxbytes instead of filesystem lblk_bits
  fscrypt: replace get_ino_and_lblk_bits with just has_32bit_inodes
  fscrypt: support crypto data unit size less than filesystem block size

 Documentation/filesystems/fscrypt.rst | 116 ++++++++++++++------
 fs/ceph/crypto.c                      |   1 +
 fs/crypto/bio.c                       |  39 ++++---
 fs/crypto/crypto.c                    | 148 +++++++++++++++-----------
 fs/crypto/fscrypt_private.h           |  55 ++++++++--
 fs/crypto/inline_crypt.c              |  25 +++--
 fs/crypto/keysetup.c                  |   3 +
 fs/crypto/keysetup_v1.c               |   5 +-
 fs/crypto/policy.c                    |  75 ++++++++-----
 fs/ext4/crypto.c                      |  13 +--
 fs/f2fs/super.c                       |  13 +--
 fs/ubifs/crypto.c                     |   3 +-
 include/linux/fscrypt.h               |  71 +++++++-----
 include/uapi/linux/fscrypt.h          |   3 +-
 14 files changed, 364 insertions(+), 206 deletions(-)


base-commit: 0bb80ecc33a8fb5a682236443c1e740d5c917d1d