From 04cadb4fe0341304741ef60a297366b553f0ce36 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 10 Oct 2025 17:10:47 -0700 Subject: lib/crypto: Add FIPS self-tests for SHA-1 and SHA-2 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.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) (limited to 'lib/crypto/sha256.c') diff --git a/lib/crypto/sha256.c b/lib/crypto/sha256.c index 881b935418ce..5d6b77e7e141 100644 --- a/lib/crypto/sha256.c +++ b/lib/crypto/sha256.c @@ -17,6 +17,7 @@ #include #include #include +#include "fips.h" static const struct sha256_block_state sha224_iv = { .h = { @@ -269,8 +270,8 @@ void sha256(const u8 *data, size_t len, u8 out[SHA256_DIGEST_SIZE]) EXPORT_SYMBOL(sha256); /* - * Pre-boot environment (as indicated by __DISABLE_EXPORTS being defined) - * doesn't need either HMAC support or interleaved hashing support + * Pre-boot environments (as indicated by __DISABLE_EXPORTS being defined) just + * need the generic SHA-256 code. Omit all other features from them. */ #ifndef __DISABLE_EXPORTS @@ -477,12 +478,27 @@ void hmac_sha256_usingrawkey(const u8 *raw_key, size_t raw_key_len, hmac_sha256_final(&ctx, out); } EXPORT_SYMBOL_GPL(hmac_sha256_usingrawkey); -#endif /* !__DISABLE_EXPORTS */ -#ifdef sha256_mod_init_arch +#if defined(sha256_mod_init_arch) || defined(CONFIG_CRYPTO_FIPS) static int __init sha256_mod_init(void) { +#ifdef sha256_mod_init_arch sha256_mod_init_arch(); +#endif + if (fips_enabled) { + /* + * FIPS cryptographic algorithm self-test. As per the FIPS + * Implementation Guidance, testing HMAC-SHA256 satisfies the + * test requirement for SHA-224, SHA-256, and HMAC-SHA224 too. + */ + u8 mac[SHA256_DIGEST_SIZE]; + + hmac_sha256_usingrawkey(fips_test_key, sizeof(fips_test_key), + fips_test_data, sizeof(fips_test_data), + mac); + if (memcmp(fips_test_hmac_sha256_value, mac, sizeof(mac)) != 0) + panic("sha256: FIPS self-test failed\n"); + } return 0; } subsys_initcall(sha256_mod_init); @@ -493,5 +509,7 @@ static void __exit sha256_mod_exit(void) module_exit(sha256_mod_exit); #endif +#endif /* !__DISABLE_EXPORTS */ + MODULE_DESCRIPTION("SHA-224, SHA-256, HMAC-SHA224, and HMAC-SHA256 library functions"); MODULE_LICENSE("GPL"); -- cgit v1.2.3