[PATCH v3 00/13] fscrypt: improve file creation flow

[Eric Biggers]

Hello,

This series reworks the implementation of creating new encrypted files
by introducing new helper functions that allow filesystems to set up the
inodes' keys earlier, prior to taking too many filesystem locks.

This fixes deadlocks that are possible during memory reclaim because
fscrypt_get_encryption_info() isn't GFP_NOFS-safe, yet it's called
during an ext4 transaction or under f2fs_lock_op().  It also fixes a
similar deadlock where f2fs can try to recursively lock a page when the
test_dummy_encryption mount option is in use.

It also solves an ordering problem that the ceph support for fscrypt
will have.  For more details about this ordering problem, see the
discussion on Jeff Layton's RFC patchsets for ceph fscrypt support
(v1: https://lkml.kernel.org/linux-fscrypt/20200821182813.52570-1-jlayton@kernel.org/T/#u
 v2: https://lkml.kernel.org/linux-fscrypt/20200904160537.76663-1-jlayton@kernel.org/T/#u
 v3: https://lkml.kernel.org/linux-fscrypt/20200914191707.380444-1-jlayton@kernel.org/T/#u)
Note that v3 of the ceph patchset is based on v2 of this patchset.

Patch 1 adds the above-mentioned new helper functions.  Patches 2-5
convert ext4, f2fs, and ubifs to use them, and patches 6-9 clean up a
few things afterwards.

Finally, patches 10-13 change the implementation of
test_dummy_encryption to no longer set up an encryption key for
unencrypted directories, which was confusing and was causing problems.

This patchset applies to the master branch of
https://git.kernel.org/pub/scm/fs/fscrypt/fscrypt.git.
It can also be retrieved from tag "fscrypt-file-creation-v3" of
https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git.

I'm looking to apply this for 5.10; reviews are greatly appreciated!

Changed v2 => v3:
  - Added patch that changes fscrypt_set_test_dummy_encryption() to take
    a 'const char *'.  (Needed by ceph.)
  - Fixed bug where fscrypt_prepare_new_inode() succeeded even if the
    new inode's key couldn't be set up.
  - Fixed bug where fscrypt_prepare_new_inode() wouldn't derive the
    dirhash key for new casefolded directories.
  - Made warning messages account for i_ino possibly being 0 now.

Changed v1 => v2:
  - Added mention of another deadlock this fixes.
  - Added patches to improve the test_dummy_encryption implementation.
  - Dropped an ext4 cleanup patch that can be done separately later.
  - Lots of small cleanups, and a couple small fixes.

Eric Biggers (13):
  fscrypt: add fscrypt_prepare_new_inode() and fscrypt_set_context()
  ext4: factor out ext4_xattr_credits_for_new_inode()
  ext4: use fscrypt_prepare_new_inode() and fscrypt_set_context()
  f2fs: use fscrypt_prepare_new_inode() and fscrypt_set_context()
  ubifs: use fscrypt_prepare_new_inode() and fscrypt_set_context()
  fscrypt: adjust logging for in-creation inodes
  fscrypt: remove fscrypt_inherit_context()
  fscrypt: require that fscrypt_encrypt_symlink() already has key
  fscrypt: stop pretending that key setup is nofs-safe
  fscrypt: make "#define fscrypt_policy" user-only
  fscrypt: move fscrypt_prepare_symlink() out-of-line
  fscrypt: handle test_dummy_encryption in more logical way
  fscrypt: make fscrypt_set_test_dummy_encryption() take a 'const char
    *'

 fs/crypto/crypto.c           |   4 +-
 fs/crypto/fname.c            |  11 +-
 fs/crypto/fscrypt_private.h  |  10 +-
 fs/crypto/hooks.c            |  65 ++++++++----
 fs/crypto/inline_crypt.c     |   7 +-
 fs/crypto/keyring.c          |   9 +-
 fs/crypto/keysetup.c         | 182 +++++++++++++++++++++++--------
 fs/crypto/keysetup_v1.c      |   8 +-
 fs/crypto/policy.c           | 200 ++++++++++++++++++++---------------
 fs/ext4/ext4.h               |   6 +-
 fs/ext4/ialloc.c             | 119 +++++++++++----------
 fs/ext4/super.c              |  17 +--
 fs/f2fs/dir.c                |   2 +-
 fs/f2fs/f2fs.h               |  25 +----
 fs/f2fs/namei.c              |   7 +-
 fs/f2fs/super.c              |  16 +--
 fs/ubifs/dir.c               |  38 +++----
 include/linux/fscrypt.h      | 120 +++++++--------------
 include/uapi/linux/fscrypt.h |   6 +-
 19 files changed, 474 insertions(+), 378 deletions(-)


base-commit: 5e895bd4d5233cb054447d0491d4e63c8496d419
-- 
2.28.0