1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * DES & Triple DES EDE key verification helpers
4 */
5
6#ifndef __CRYPTO_INTERNAL_DES_H
7#define __CRYPTO_INTERNAL_DES_H
8
9#include <linux/crypto.h>
10#include <linux/fips.h>
11#include <crypto/des.h>
12#include <crypto/aead.h>
13#include <crypto/skcipher.h>
14
15/**
16 * crypto_des_verify_key - Check whether a DES key is weak
17 * @tfm: the crypto algo
18 * @key: the key buffer
19 *
20 * Returns -EINVAL if the key is weak and the crypto TFM does not permit weak
21 * keys. Otherwise, 0 is returned.
22 *
23 * It is the job of the caller to ensure that the size of the key equals
24 * DES_KEY_SIZE.
25 */
26static inline int crypto_des_verify_key(struct crypto_tfm *tfm, const u8 *key)
27{
28	struct des_ctx tmp;
29	int err;
30
31	err = des_expand_key(&tmp, key, DES_KEY_SIZE);
32	if (err == -ENOKEY) {
33		if (crypto_tfm_get_flags(tfm) & CRYPTO_TFM_REQ_FORBID_WEAK_KEYS)
34			err = -EINVAL;
35		else
36			err = 0;
37	}
38	memzero_explicit(&tmp, sizeof(tmp));
39	return err;
40}
41
42/*
43 * RFC2451:
44 *
45 *   For DES-EDE3, there is no known need to reject weak or
46 *   complementation keys.  Any weakness is obviated by the use of
47 *   multiple keys.
48 *
49 *   However, if the first two or last two independent 64-bit keys are
50 *   equal (k1 == k2 or k2 == k3), then the DES3 operation is simply the
51 *   same as DES.  Implementers MUST reject keys that exhibit this
52 *   property.
53 *
54 */
55static inline int des3_ede_verify_key(const u8 *key, unsigned int key_len,
56				      bool check_weak)
57{
58	int ret = fips_enabled ? -EINVAL : -ENOKEY;
59	u32 K[6];
60
61	memcpy(K, key, DES3_EDE_KEY_SIZE);
62
63	if ((!((K[0] ^ K[2]) | (K[1] ^ K[3])) ||
64	     !((K[2] ^ K[4]) | (K[3] ^ K[5]))) &&
65	    (fips_enabled || check_weak))
66		goto bad;
67
68	if ((!((K[0] ^ K[4]) | (K[1] ^ K[5]))) && fips_enabled)
69		goto bad;
70
71	ret = 0;
72bad:
73	memzero_explicit(K, DES3_EDE_KEY_SIZE);
74
75	return ret;
76}
77
78/**
79 * crypto_des3_ede_verify_key - Check whether a DES3-EDE key is weak
80 * @tfm: the crypto algo
81 * @key: the key buffer
82 *
83 * Returns -EINVAL if the key is weak and the crypto TFM does not permit weak
84 * keys or when running in FIPS mode. Otherwise, 0 is returned. Note that some
85 * keys are rejected in FIPS mode even if weak keys are permitted by the TFM
86 * flags.
87 *
88 * It is the job of the caller to ensure that the size of the key equals
89 * DES3_EDE_KEY_SIZE.
90 */
91static inline int crypto_des3_ede_verify_key(struct crypto_tfm *tfm,
92					     const u8 *key)
93{
94	return des3_ede_verify_key(key, DES3_EDE_KEY_SIZE,
95				   crypto_tfm_get_flags(tfm) &
96				   CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
97}
98
99static inline int verify_skcipher_des_key(struct crypto_skcipher *tfm,
100					  const u8 *key)
101{
102	return crypto_des_verify_key(crypto_skcipher_tfm(tfm), key);
103}
104
105static inline int verify_skcipher_des3_key(struct crypto_skcipher *tfm,
106					   const u8 *key)
107{
108	return crypto_des3_ede_verify_key(crypto_skcipher_tfm(tfm), key);
109}
110
111static inline int verify_aead_des_key(struct crypto_aead *tfm, const u8 *key,
112				      int keylen)
113{
114	if (keylen != DES_KEY_SIZE)
115		return -EINVAL;
116	return crypto_des_verify_key(crypto_aead_tfm(tfm), key);
117}
118
119static inline int verify_aead_des3_key(struct crypto_aead *tfm, const u8 *key,
120				       int keylen)
121{
122	if (keylen != DES3_EDE_KEY_SIZE)
123		return -EINVAL;
124	return crypto_des3_ede_verify_key(crypto_aead_tfm(tfm), key);
125}
126
127#endif /* __CRYPTO_INTERNAL_DES_H */
128