kernel/linux.git/lib/crypto/sha256.c, branch v6.19.11

lib/crypto: Add FIPS self-tests for SHA-1 and SHA-2

2025-10-30T05:04:24+00:00

Add FIPS cryptographic algorithm self-tests for all SHA-1 and SHA-2 algorithms. Following the "Implementation Guidance for FIPS 140-3" document, to achieve this it's sufficient to just test a single test vector for each of HMAC-SHA1, HMAC-SHA256, and HMAC-SHA512. Just run these tests in the initcalls, following the example of e.g. crypto/kdf_sp800108.c. Note that this should meet the FIPS self-test requirement even in the built-in case, given that the initcalls run before userspace, storage, network, etc. are accessible. This does not fix a regression, seeing as lib/ has had SHA-1 support since 2005 and SHA-256 support since 2018. Neither ever had FIPS self-tests. Moreover, fips=1 support has always been an unfinished feature upstream. However, with lib/ now being used more widely, it's now seeing more scrutiny and people seem to want these now [1][2]. [1] https://lore.kernel.org/r/3226361.1758126043@warthog.procyon.org.uk/ [2] https://lore.kernel.org/r/f31dbb22-0add-481c-aee0-e337a7731f8e@oracle.com/ Reviewed-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20251011001047.51886-1-ebiggers@kernel.org Signed-off-by: Eric Biggers

lib/crypto: sha256: Add support for 2-way interleaved hashing

2025-09-17T18:09:39+00:00

Many arm64 and x86_64 CPUs can compute two SHA-256 hashes in nearly the same speed as one, if the instructions are interleaved. This is because SHA-256 is serialized block-by-block, and two interleaved hashes take much better advantage of the CPU's instruction-level parallelism. Meanwhile, a very common use case for SHA-256 hashing in the Linux kernel is dm-verity and fs-verity. Both use a Merkle tree that has a fixed block size, usually 4096 bytes with an empty or 32-byte salt prepended. Usually, many blocks need to be hashed at a time. This is an ideal scenario for 2-way interleaved hashing. To enable this optimization, add a new function sha256_finup_2x() to the SHA-256 library API. It computes the hash of two equal-length messages, starting from a common initial context. For now it always falls back to sequential processing. Later patches will wire up arm64 and x86_64 optimized implementations. Note that the interleaving factor could in principle be higher than 2x. However, that runs into many practical difficulties and CPU throughput limitations. Thus, both the implementations I'm adding are 2x. In the interest of using the simplest solution, the API matches that. Reviewed-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250915160819.140019-2-ebiggers@kernel.org Signed-off-by: Eric Biggers

lib/crypto: sha2: Add hmac_sha*_init_usingrawkey()

2025-07-14T15:20:37+00:00

While the HMAC library functions support both incremental and one-shot computation and both prepared and raw keys, the combination of raw key + incremental was missing. It turns out that several potential users of the HMAC library functions (tpm2-sessions.c, smb2transport.c, trusted_tpm1.c) want exactly that. Therefore, add the missing functions hmac_sha*_init_usingrawkey(). Implement them in an optimized way that directly initializes the HMAC context without a separate key preparation step. Reimplement the one-shot raw key functions hmac_sha*_usingrawkey() on top of the new functions, which makes them a bit more efficient. Reviewed-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250711215844.41715-1-ebiggers@kernel.org Signed-off-by: Eric Biggers

lib/crypto: sha256: Sync sha256_update() with sha512_update()

2025-07-04T17:23:11+00:00

The BLOCK_HASH_UPDATE_BLOCKS macro is difficult to read. For now, let's just write the update explicitly in the straightforward way, mirroring sha512_update(). It's possible that we'll bring back a macro for this later, but it needs to be properly justified and hopefully a bit more readable. Acked-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250630160645.3198-14-ebiggers@kernel.org Signed-off-by: Eric Biggers

lib/crypto: sha256: Consolidate into single module

2025-07-04T17:23:11+00:00

Consolidate the CPU-based SHA-256 code into a single module, following what I did with SHA-512: - Each arch now provides a header file lib/crypto/$(SRCARCH)/sha256.h, replacing lib/crypto/$(SRCARCH)/sha256.c. The header defines sha256_blocks() and optionally sha256_mod_init_arch(). It is included by lib/crypto/sha256.c, and thus the code gets built into the single libsha256 module, with proper inlining and dead code elimination. - sha256_blocks_generic() is moved from lib/crypto/sha256-generic.c into lib/crypto/sha256.c. It's now a static function marked with __maybe_unused, so the compiler automatically eliminates it in any cases where it's not used. - Whether arch-optimized SHA-256 is buildable is now controlled centrally by lib/crypto/Kconfig instead of by lib/crypto/$(SRCARCH)/Kconfig. The conditions for enabling it remain the same as before, and it remains enabled by default. - Any additional arch-specific translation units for the optimized SHA-256 code (such as assembly files) are now compiled by lib/crypto/Makefile instead of lib/crypto/$(SRCARCH)/Makefile. Acked-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250630160645.3198-13-ebiggers@kernel.org Signed-off-by: Eric Biggers

lib/crypto: sha256: Add HMAC-SHA224 and HMAC-SHA256 support

2025-07-04T17:23:11+00:00

Since HMAC support is commonly needed and is fairly simple, include it as a first-class citizen of the SHA-256 library. The API supports both incremental and one-shot computation, and either preparing the key ahead of time or just using a raw key. The implementation is much more streamlined than crypto/hmac.c. I've kept it consistent with the HMAC-SHA384 and HMAC-SHA512 code as much as possible. Testing of these functions will be via sha224_kunit and sha256_kunit, added by a later commit. Acked-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250630160645.3198-9-ebiggers@kernel.org Signed-off-by: Eric Biggers

lib/crypto: sha256: Make library API use strongly-typed contexts

2025-07-04T17:18:53+00:00

Currently the SHA-224 and SHA-256 library functions can be mixed arbitrarily, even in ways that are incorrect, for example using sha224_init() and sha256_final(). This is because they operate on the same structure, sha256_state. Introduce stronger typing, as I did for SHA-384 and SHA-512. Also as I did for SHA-384 and SHA-512, use the names *_ctx instead of *_state. The *_ctx names have the following small benefits: - They're shorter. - They avoid an ambiguity with the compression function state. - They're consistent with the well-known OpenSSL API. - Users usually name the variable 'sctx' anyway, which suggests that *_ctx would be the more natural name for the actual struct. Therefore: update the SHA-224 and SHA-256 APIs, implementation, and calling code accordingly. In the new structs, also strongly-type the compression function state. Acked-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250630160645.3198-7-ebiggers@kernel.org Signed-off-by: Eric Biggers

lib/crypto: sha256: Add sha224() and sha224_update()

2025-07-04T17:18:53+00:00

Add a one-shot SHA-224 computation function sha224(), for consistency with sha256(), sha384(), and sha512() which all already exist. Similarly, add sha224_update(). While for now it's identical to sha256_update(), omitting it makes the API harder to use since users have to "know" which functions are the same between SHA-224 and SHA-256. Also, this is a prerequisite for using different context types for each. Acked-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250630160645.3198-6-ebiggers@kernel.org Signed-off-by: Eric Biggers

lib/crypto: sha256: Reorder some code

2025-07-04T17:18:52+00:00

First, move the declarations of sha224_init/update/final to be just above the corresponding SHA-256 code, matching the order that I used for SHA-384 and SHA-512. In sha2.h, the end result is that SHA-224, SHA-256, SHA-384, and SHA-512 are all in the logical order. Second, move sha224_block_init() and sha256_block_init() to be just below crypto_sha256_state. In later changes, these functions as well as struct crypto_sha256_state will no longer be used by the library functions. They'll remain just for some legacy offload drivers. This gets them into a logical place in the file for that. No code changes other than reordering. Acked-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250630160645.3198-4-ebiggers@kernel.org Signed-off-by: Eric Biggers

lib/crypto: Explicitly include

2025-06-30T16:26:19+00:00

Fix build warnings with W=1 that started appearing after commit a934a57a42f6 ("scripts/misc-check: check missing #include when W=1"). While at it, also sort the include lists alphabetically. (Keep asm/irqflags.h last, as otherwise it doesn't build on alpha.) This handles all of lib/crypto/, but not arch/*/lib/crypto/. The exports in arch/*/lib/crypto/ will go away when the code is properly integrated into lib/crypto/ as planned. Link: https://lore.kernel.org/r/20250613184814.50173-1-ebiggers@kernel.org Signed-off-by: Eric Biggers