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 most encryption fstests with suitable changes to btrfs-progs, but not generic/580 or generic/595 due to different timing involved in extent encryption. Tests and btrfs progs updates to follow. [1] https://docs.google.com/document/d/1janjxewlewtVPqctkWOjSa7OhCgB8Gdx7iDaCDQQNZA/edit?usp=sharing [2] https://lore.kernel.org/linux-fscrypt/80496cfe-161d-fb0d-8230-93818b966b1b@xxxxxxxxxx/T/#t [3] https://lore.kernel.org/linux-fscrypt/cover.1687988119.git.sweettea-kernel@xxxxxxxxxx/ Sweet Tea Dorminy (12): 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: 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 | 38 +++- fs/crypto/crypto.c | 6 +- fs/crypto/fscrypt_private.h | 91 ++++++++++ fs/crypto/inline_crypt.c | 28 ++- fs/crypto/keyring.c | 32 +++- fs/crypto/keysetup.c | 244 ++++++++++++++++++++++---- fs/crypto/keysetup_v1.c | 7 +- fs/crypto/policy.c | 20 +++ include/linux/fscrypt.h | 74 ++++++++ 9 files changed, 480 insertions(+), 60 deletions(-) base-commit: accadeb67609a5a5d088ebde8409c3f6db0b84b4 -- 2.40.1
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