From ff3ab74623dfe6a76fdcf3d2139c3f699e31984a Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Wed, 15 Jul 2026 15:11:41 -0700 Subject: [PATCH] crypto: xts - Split out __xts_verify_key() helper Make the AES-XTS key verification code callable by the crypto library by splitting out a helper function that doesn't use crypto_skcipher. Reviewed-by: Thomas Huth Link: https://patch.msgid.link/20260715221153.246410-2-ebiggers@kernel.org Signed-off-by: Eric Biggers --- include/crypto/xts.h | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/include/crypto/xts.h b/include/crypto/xts.h index 15b16c4853d8..16aef89f021f 100644 --- a/include/crypto/xts.h +++ b/include/crypto/xts.h @@ -7,9 +7,9 @@ #include #define XTS_BLOCK_SIZE 16 +#define XTS_FORBID_WEAK_KEYS (1 << 0) -static inline int xts_verify_key(struct crypto_skcipher *tfm, - const u8 *key, unsigned int keylen) +static inline int __xts_verify_key(const u8 *key, size_t keylen, int flags) { /* * key consists of keys of equal size concatenated, therefore @@ -29,12 +29,22 @@ static inline int xts_verify_key(struct crypto_skcipher *tfm, * Ensure that the AES and tweak key are not identical when * in FIPS mode or the FORBID_WEAK_KEYS flag is set. */ - if ((fips_enabled || (crypto_skcipher_get_flags(tfm) & - CRYPTO_TFM_REQ_FORBID_WEAK_KEYS)) && + if ((fips_enabled || (flags & XTS_FORBID_WEAK_KEYS)) && !crypto_memneq(key, key + (keylen / 2), keylen / 2)) return -EINVAL; return 0; } +static inline int xts_verify_key(struct crypto_skcipher *tfm, const u8 *key, + unsigned int keylen) +{ + int flags = (crypto_skcipher_get_flags(tfm) & + CRYPTO_TFM_REQ_FORBID_WEAK_KEYS) ? + XTS_FORBID_WEAK_KEYS : + 0; + + return __xts_verify_key(key, keylen, flags); +} + #endif /* _CRYPTO_XTS_H */