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
11static inline int xts_verify_key(struct crypto_skcipher *tfm,
12				 const u8 *key, unsigned int keylen)
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 || (crypto_skcipher_get_flags(tfm) &
33			      CRYPTO_TFM_REQ_FORBID_WEAK_KEYS)) &&
34	    !crypto_memneq(key, key + (keylen / 2), keylen / 2))
35		return -EINVAL;
36
37	return 0;
38}
39
40#endif  /* _CRYPTO_XTS_H */