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
11#define XTS_TWEAK_CAST(x) ((void (*)(void *, u8*, const u8*))(x))
12
13static inline int xts_check_key(struct crypto_tfm *tfm,
14				const u8 *key, unsigned int keylen)
15{
16	u32 *flags = &tfm->crt_flags;
17
18	/*
19	 * key consists of keys of equal size concatenated, therefore
20	 * the length must be even.
21	 */
22	if (keylen % 2) {
23		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
24		return -EINVAL;
25	}
26
27	/* ensure that the AES and tweak key are not identical */
28	if (fips_enabled &&
29	    !crypto_memneq(key, key + (keylen / 2), keylen / 2)) {
30		*flags |= CRYPTO_TFM_RES_WEAK_KEY;
31		return -EINVAL;
32	}
33
34	return 0;
35}
36
37static inline int xts_verify_key(struct crypto_skcipher *tfm,
38				 const u8 *key, unsigned int keylen)
39{
40	/*
41	 * key consists of keys of equal size concatenated, therefore
42	 * the length must be even.
43	 */
44	if (keylen % 2) {
45		crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
46		return -EINVAL;
47	}
48
49	/* ensure that the AES and tweak key are not identical */
50	if ((fips_enabled || crypto_skcipher_get_flags(tfm) &
51			     CRYPTO_TFM_REQ_WEAK_KEY) &&
52	    !crypto_memneq(key, key + (keylen / 2), keylen / 2)) {
53		crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_WEAK_KEY);
54		return -EINVAL;
55	}
56
57	return 0;
58}
59
60#endif  /* _CRYPTO_XTS_H */