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  */
crypto_des_verify_key(struct crypto_tfm * tfm,const u8 * key)26 static 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  */
des3_ede_verify_key(const u8 * key,unsigned int key_len,bool check_weak)55 static 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;
72 bad:
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  */
crypto_des3_ede_verify_key(struct crypto_tfm * tfm,const u8 * key)91 static 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 
verify_skcipher_des_key(struct crypto_skcipher * tfm,const u8 * key)99 static 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 
verify_skcipher_des3_key(struct crypto_skcipher * tfm,const u8 * key)105 static 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 
verify_aead_des_key(struct crypto_aead * tfm,const u8 * key,int keylen)111 static 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 
verify_aead_des3_key(struct crypto_aead * tfm,const u8 * key,int keylen)119 static 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