crypto/kdf_sp800108.c

   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 = kdf_test(&kdf_ctr_hmac_sha256_tv_template[0], "hmac(sha256)",
 129                            crypto_kdf108_setkey, crypto_kdf108_ctr_generate);
 130
 131         if (ret) {
 132                 if (fips_enabled)
 133                         panic("alg: self-tests for CTR-KDF (hmac(sha256)) failed (rc=%d)\n",
 134                               ret);
 135
 136                 WARN(1,
 137                      "alg: self-tests for CTR-KDF (hmac(sha256)) failed (rc=%d)\n",
 138                      ret);
 139         } else {
 140                 pr_info("alg: self-tests for CTR-KDF (hmac(sha256)) passed\n");
 141         }
 142
 143         return ret;
 144 }
 145
 146 static void __exit crypto_kdf108_exit(void) { }
 147
 148 module_init(crypto_kdf108_init);
 149 module_exit(crypto_kdf108_exit);
 150
 151 MODULE_LICENSE("GPL v2");
 152 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
 153 MODULE_DESCRIPTION("Key Derivation Function conformant to SP800-108");