[v2,00/14] fscrypt: add extent encryption

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Sweet Tea Dorminy July 9, 2023, 6:53 p.m. UTC

This changeset adds extent-based data encryption to fscrypt.
Some filesystems need to encrypt data based on extents, rather than on
inodes, due to features incompatible with inode-based encryption. For
instance, btrfs can have multiple inodes referencing a single block of
data, and moves logical data blocks to different physical locations on
disk in the background. 

As per discussion last year in [1] and later in [2], we would like to
allow the use of fscrypt with btrfs, with authenticated encryption. This
is the first step of that work, adding extent-based encryption to
fscrypt; authenticated encryption is the next step. Extent-based
encryption should be usable by other filesystems which wish to support
snapshotting or background data rearrangement also, but btrfs is the
first user. 

This changeset requires extent encryption to use inlinecrypt, as
discussed previously. There are two questionable parts: the
forget_extent_info hook is not yet in use by btrfs, as I haven't yet
written a test exercising a race where it would be relevant; and saving
the session key credentials just to enable v1 session-based policies is
perhaps less good than 

This applies atop [3], which itself is based on kdave/misc-next. It
passes encryption fstests with suitable changes to btrfs-progs and tests.

[1] https://docs.google.com/document/d/1janjxewlewtVPqctkWOjSa7OhCgB8Gdx7iDaCDQQNZA/edit?usp=sharing
[2] https://lore.kernel.org/linux-fscrypt/[e-mail]/T/#t
[3]
https://lore.kernel.org/linux-fscrypt/[e-mail]/

Changelog:
v2:
- Change to soft-delete keys in use by inodes using extent encryption at
  key removal time (new changes 9 and 10), as per feedback.
- Add a missing error check in fscrypt_mergeable_bio (change 3)
v1:
- https://lore.kernel.org/linux-fscrypt/[e-mail]/T/#t

Sweet Tea Dorminy (14):
  fscrypt: factor helper for locking master key
  fscrypt: factor getting info for a specific block
  fscrypt: adjust effective lblks based on extents
  fscrypt: add a super_block pointer to fscrypt_info
  fscrypt: setup leaf inodes for extent encryption
  fscrypt: allow infos to be owned by extents
  fscrypt: notify per-extent infos if master key vanishes
  fscrypt: use an optional ino equivalent for per-extent infos
  fscrypt: move function call warning of busy inodes
  fscrypt: revamp key removal for extent encryption
  fscrypt: add creation/usage/freeing of per-extent infos
  fscrypt: allow load/save of extent contexts
  fscrypt: save session key credentials for extent infos
  fscrypt: update documentation for per-extent keys

 Documentation/filesystems/fscrypt.rst |  43 +++-
 fs/crypto/crypto.c                    |   6 +-
 fs/crypto/fscrypt_private.h           | 128 +++++++++++-
 fs/crypto/inline_crypt.c              |  28 ++-
 fs/crypto/keyring.c                   |  79 +++++---
 fs/crypto/keysetup.c                  | 274 ++++++++++++++++++++++----
 fs/crypto/keysetup_v1.c               |   7 +-
 fs/crypto/policy.c                    |  20 ++
 include/linux/fscrypt.h               |  65 ++++++
 9 files changed, 562 insertions(+), 88 deletions(-)


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prerequisite-patch-id: d4f1a64c994c2fa0d2d4cab83f9ddff52f0622e9
prerequisite-patch-id: 1af0fc98277159b31c26bc5751663efc0d322d75
prerequisite-patch-id: 3b21b62208587486cf9b31618f7c3bc875362f1a
prerequisite-patch-id: c43d693f5b7c498a876d9ffcfc49c11a8ca93d80
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prerequisite-patch-id: c6a1f087d4a67b928b9c6af04e00310bfa74ace1