diff options
| author | Eric Biggers <ebiggers@kernel.org> | 2025-09-05 20:59:13 -0700 |
|---|---|---|
| committer | Eric Biggers <ebiggers@kernel.org> | 2025-09-05 21:01:51 -0700 |
| commit | 19591f7e781fd1e68228f5b3bee60be6425af886 (patch) | |
| tree | bfb8b2d50c1e2d0eb3006f582fae72d00259974f /fs/crypto/fname.c | |
| parent | 0e6608d4938eb209616e8673c95364bb2a7d55bd (diff) | |
fscrypt: use HMAC-SHA512 library for HKDF
For the HKDF-SHA512 key derivation needed by fscrypt, just use the
HMAC-SHA512 library functions directly. These functions were introduced
in v6.17, and they provide simple and efficient direct support for
HMAC-SHA512. This ends up being quite a bit simpler and more efficient
than using crypto/hkdf.c, as it avoids the generic crypto layer:
- The HMAC library can't fail, so callers don't need to handle errors
- No inefficient indirect calls
- No inefficient and error-prone dynamic allocations
- No inefficient and error-prone loading of algorithm by name
- Less stack usage
Benchmarks on x86_64 show that deriving a per-file key gets about 30%
faster, and FS_IOC_ADD_ENCRYPTION_KEY gets nearly twice as fast.
The only small downside is the HKDF-Expand logic gets duplicated again.
Then again, even considering that, the new fscrypt_hkdf_expand() is only
7 lines longer than the version that called hkdf_expand(). Later we
could add HKDF support to lib/crypto/, but for now let's just do this.
Link: https://lore.kernel.org/r/20250906035913.1141532-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Diffstat (limited to 'fs/crypto/fname.c')
| -rw-r--r-- | fs/crypto/fname.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/fs/crypto/fname.c b/fs/crypto/fname.c index f9f6713e144f..5fa1eb58bb1d 100644 --- a/fs/crypto/fname.c +++ b/fs/crypto/fname.c @@ -11,7 +11,6 @@ * This has not yet undergone a rigorous security audit. */ -#include <crypto/hash.h> #include <crypto/sha2.h> #include <crypto/skcipher.h> #include <linux/export.h> |