1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _CRYPTO_XTS_H 3 #define _CRYPTO_XTS_H 4 5 #include <crypto/b128ops.h> 6 #include <crypto/internal/skcipher.h> 7 #include <linux/fips.h> 8 9 #define XTS_BLOCK_SIZE 16 10 #define XTS_FORBID_WEAK_KEYS (1 << 0) 11 12 static inline int __xts_verify_key(const u8 *key, size_t keylen, int flags) 13 { 14 /* 15 * key consists of keys of equal size concatenated, therefore 16 * the length must be even. 17 */ 18 if (keylen % 2) 19 return -EINVAL; 20 21 /* 22 * In FIPS mode only a combined key length of either 256 or 23 * 512 bits is allowed, c.f. FIPS 140-3 IG C.I. 24 */ 25 if (fips_enabled && keylen != 32 && keylen != 64) 26 return -EINVAL; 27 28 /* 29 * Ensure that the AES and tweak key are not identical when 30 * in FIPS mode or the FORBID_WEAK_KEYS flag is set. 31 */ 32 if ((fips_enabled || (flags & XTS_FORBID_WEAK_KEYS)) && 33 !crypto_memneq(key, key + (keylen / 2), keylen / 2)) 34 return -EINVAL; 35 36 return 0; 37 } 38 39 static inline int xts_verify_key(struct crypto_skcipher *tfm, const u8 *key, 40 unsigned int keylen) 41 { 42 int flags = (crypto_skcipher_get_flags(tfm) & 43 CRYPTO_TFM_REQ_FORBID_WEAK_KEYS) ? 44 XTS_FORBID_WEAK_KEYS : 45 0; 46 47 return __xts_verify_key(key, keylen, flags); 48 } 49 50 #endif /* _CRYPTO_XTS_H */ 51