1 // SPDX-License-Identifier: GPL-2.0
2
3 /*
4 * SP800-108 Key-derivation function
5 *
6 * Copyright (C) 2021, Stephan Mueller <smueller@chronox.de>
7 */
8
9 #include <linux/fips.h>
10 #include <linux/module.h>
11 #include <crypto/kdf_sp800108.h>
12 #include <crypto/internal/kdf_selftest.h>
13
14 /*
15 * SP800-108 CTR KDF implementation
16 */
17 int crypto_kdf108_ctr_generate(struct crypto_shash *kmd,
18 const struct kvec *info, unsigned int info_nvec,
19 u8 *dst, unsigned int dlen)
20 {
21 SHASH_DESC_ON_STACK(desc, kmd);
22 __be32 counter = cpu_to_be32(1);
23 const unsigned int h = crypto_shash_digestsize(kmd), dlen_orig = dlen;
24 unsigned int i;
25 int err = 0;
26 u8 *dst_orig = dst;
27
28 desc->tfm = kmd;
29
30 while (dlen) {
31 err = crypto_shash_init(desc);
32 if (err)
33 goto out;
34
35 err = crypto_shash_update(desc, (u8 *)&counter, sizeof(__be32));
36 if (err)
37 goto out;
38
39 for (i = 0; i < info_nvec; i++) {
40 err = crypto_shash_update(desc, info[i].iov_base,
41 info[i].iov_len);
42 if (err)
43 goto out;
44 }
45
46 if (dlen < h) {
47 u8 tmpbuffer[HASH_MAX_DIGESTSIZE];
48
49 err = crypto_shash_final(desc, tmpbuffer);
50 if (err)
51 goto out;
52 memcpy(dst, tmpbuffer, dlen);
53 memzero_explicit(tmpbuffer, h);
54 goto out;
55 }
56
57 err = crypto_shash_final(desc, dst);
58 if (err)
59 goto out;
60
61 dlen -= h;
62 dst += h;
63 counter = cpu_to_be32(be32_to_cpu(counter) + 1);
64 }
65
66 out:
67 if (err)
68 memzero_explicit(dst_orig, dlen_orig);
69 shash_desc_zero(desc);
70 return err;
71 }
72 EXPORT_SYMBOL(crypto_kdf108_ctr_generate);
73
74 /*
75 * The seeding of the KDF
76 */
77 int crypto_kdf108_setkey(struct crypto_shash *kmd,
78 const u8 *key, size_t keylen,
79 const u8 *ikm, size_t ikmlen)
80 {
81 unsigned int ds = crypto_shash_digestsize(kmd);
82
83 /* SP800-108 does not support IKM */
84 if (ikm || ikmlen)
85 return -EINVAL;
86
87 /* Check according to SP800-108 section 7.2 */
88 if (ds > keylen)
89 return -EINVAL;
90
91 /* Set the key for the MAC used for the KDF. */
92 return crypto_shash_setkey(kmd, key, keylen);
93 }
94 EXPORT_SYMBOL(crypto_kdf108_setkey);
95
96 /*
97 * Test vector obtained from
98 * http://csrc.nist.gov/groups/STM/cavp/documents/KBKDF800-108/CounterMode.zip
99 */
100 static const struct kdf_testvec kdf_ctr_hmac_sha256_tv_template[] = {
101 {
102 .key = "\xdd\x1d\x91\xb7\xd9\x0b\x2b\xd3"
103 "\x13\x85\x33\xce\x92\xb2\x72\xfb"
104 "\xf8\xa3\x69\x31\x6a\xef\xe2\x42"
105 "\xe6\x59\xcc\x0a\xe2\x38\xaf\xe0",
106 .keylen = 32,
107 .ikm = NULL,
108 .ikmlen = 0,
109 .info = {
110 .iov_base = "\x01\x32\x2b\x96\xb3\x0a\xcd\x19"
111 "\x79\x79\x44\x4e\x46\x8e\x1c\x5c"
112 "\x68\x59\xbf\x1b\x1c\xf9\x51\xb7"
113 "\xe7\x25\x30\x3e\x23\x7e\x46\xb8"
114 "\x64\xa1\x45\xfa\xb2\x5e\x51\x7b"
115 "\x08\xf8\x68\x3d\x03\x15\xbb\x29"
116 "\x11\xd8\x0a\x0e\x8a\xba\x17\xf3"
117 "\xb4\x13\xfa\xac",
118 .iov_len = 60
119 },
120 .expected = "\x10\x62\x13\x42\xbf\xb0\xfd\x40"
121 "\x04\x6c\x0e\x29\xf2\xcf\xdb\xf0",
122 .expectedlen = 16
123 }
124 };
125
126 static int __init crypto_kdf108_init(void)
127 {
128 int ret;
129
130 if (IS_ENABLED(CONFIG_CRYPTO_MANAGER_DISABLE_TESTS))
131 return 0;
132
133 ret = kdf_test(&kdf_ctr_hmac_sha256_tv_template[0], "hmac(sha256)",
134 crypto_kdf108_setkey, crypto_kdf108_ctr_generate);
135 if (ret) {
136 if (fips_enabled)
137 panic("alg: self-tests for CTR-KDF (hmac(sha256)) failed (rc=%d)\n",
138 ret);
139
140 WARN(1,
141 "alg: self-tests for CTR-KDF (hmac(sha256)) failed (rc=%d)\n",
142 ret);
143 } else if (fips_enabled) {
144 pr_info("alg: self-tests for CTR-KDF (hmac(sha256)) passed\n");
145 }
146
147 return ret;
148 }
149
150 static void __exit crypto_kdf108_exit(void) { }
151
152 module_init(crypto_kdf108_init);
153 module_exit(crypto_kdf108_exit);
154
155 MODULE_LICENSE("GPL v2");
156 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
157 MODULE_DESCRIPTION("Key Derivation Function conformant to SP800-108");
158
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