1 /* $OpenBSD: mac.c,v 1.32 2015/01/15 18:32:54 naddy Exp $ */ 2 /* 3 * Copyright (c) 2001 Markus Friedl. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 #include "includes.h" 27 28 #include <sys/types.h> 29 30 #include <string.h> 31 #include <stdio.h> 32 33 #include "digest.h" 34 #include "hmac.h" 35 #include "umac.h" 36 #include "mac.h" 37 #include "misc.h" 38 #include "ssherr.h" 39 #include "sshbuf.h" 40 41 #include "openbsd-compat/openssl-compat.h" 42 43 #define SSH_DIGEST 1 /* SSH_DIGEST_XXX */ 44 #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */ 45 #define SSH_UMAC128 3 46 47 struct macalg { 48 char *name; 49 int type; 50 int alg; 51 int truncatebits; /* truncate digest if != 0 */ 52 int key_len; /* just for UMAC */ 53 int len; /* just for UMAC */ 54 int etm; /* Encrypt-then-MAC */ 55 }; 56 57 static const struct macalg macs[] = { 58 /* Encrypt-and-MAC (encrypt-and-authenticate) variants */ 59 { "hmac-sha1", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 0 }, 60 { "hmac-sha1-96", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 0 }, 61 #ifdef HAVE_EVP_SHA256 62 { "hmac-sha2-256", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 0 }, 63 { "hmac-sha2-512", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 0 }, 64 #endif 65 { "hmac-md5", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 0 }, 66 { "hmac-md5-96", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 0 }, 67 #if defined(HAVE_EVP_RIPEMD) 68 { "hmac-ripemd160", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 }, 69 { "hmac-ripemd160 (at) openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 }, 70 #endif 71 { "umac-64 (at) openssh.com", SSH_UMAC, 0, 0, 128, 64, 0 }, 72 { "umac-128 (at) openssh.com", SSH_UMAC128, 0, 0, 128, 128, 0 }, 73 74 /* Encrypt-then-MAC variants */ 75 { "hmac-sha1-etm (at) openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 }, 76 { "hmac-sha1-96-etm (at) openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 }, 77 #ifdef HAVE_EVP_SHA256 78 { "hmac-sha2-256-etm (at) openssh.com", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 }, 79 { "hmac-sha2-512-etm (at) openssh.com", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 }, 80 #endif 81 { "hmac-md5-etm (at) openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 }, 82 { "hmac-md5-96-etm (at) openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 }, 83 { "hmac-ripemd160-etm (at) openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 1 }, 84 { "umac-64-etm (at) openssh.com", SSH_UMAC, 0, 0, 128, 64, 1 }, 85 { "umac-128-etm (at) openssh.com", SSH_UMAC128, 0, 0, 128, 128, 1 }, 86 87 { NULL, 0, 0, 0, 0, 0, 0 } 88 }; 89 90 /* Returns a list of supported MACs separated by the specified char. */ 91 char * 92 mac_alg_list(char sep) 93 { 94 char *ret = NULL, *tmp; 95 size_t nlen, rlen = 0; 96 const struct macalg *m; 97 98 for (m = macs; m->name != NULL; m++) { 99 if (ret != NULL) 100 ret[rlen++] = sep; 101 nlen = strlen(m->name); 102 if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) { 103 free(ret); 104 return NULL; 105 } 106 ret = tmp; 107 memcpy(ret + rlen, m->name, nlen + 1); 108 rlen += nlen; 109 } 110 return ret; 111 } 112 113 static int 114 mac_setup_by_alg(struct sshmac *mac, const struct macalg *macalg) 115 { 116 mac->type = macalg->type; 117 if (mac->type == SSH_DIGEST) { 118 if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL) 119 return SSH_ERR_ALLOC_FAIL; 120 mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg); 121 } else { 122 mac->mac_len = macalg->len / 8; 123 mac->key_len = macalg->key_len / 8; 124 mac->umac_ctx = NULL; 125 } 126 if (macalg->truncatebits != 0) 127 mac->mac_len = macalg->truncatebits / 8; 128 mac->etm = macalg->etm; 129 return 0; 130 } 131 132 int 133 mac_setup(struct sshmac *mac, char *name) 134 { 135 const struct macalg *m; 136 137 for (m = macs; m->name != NULL; m++) { 138 if (strcmp(name, m->name) != 0) 139 continue; 140 if (mac != NULL) 141 return mac_setup_by_alg(mac, m); 142 return 0; 143 } 144 return SSH_ERR_INVALID_ARGUMENT; 145 } 146 147 int 148 mac_init(struct sshmac *mac) 149 { 150 if (mac->key == NULL) 151 return SSH_ERR_INVALID_ARGUMENT; 152 switch (mac->type) { 153 case SSH_DIGEST: 154 if (mac->hmac_ctx == NULL || 155 ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0) 156 return SSH_ERR_INVALID_ARGUMENT; 157 return 0; 158 case SSH_UMAC: 159 if ((mac->umac_ctx = umac_new(mac->key)) == NULL) 160 return SSH_ERR_ALLOC_FAIL; 161 return 0; 162 case SSH_UMAC128: 163 if ((mac->umac_ctx = umac128_new(mac->key)) == NULL) 164 return SSH_ERR_ALLOC_FAIL; 165 return 0; 166 default: 167 return SSH_ERR_INVALID_ARGUMENT; 168 } 169 } 170 171 int 172 mac_compute(struct sshmac *mac, u_int32_t seqno, const u_char *data, int datalen, 173 u_char *digest, size_t dlen) 174 { 175 static union { 176 u_char m[SSH_DIGEST_MAX_LENGTH]; 177 u_int64_t for_align; 178 } u; 179 u_char b[4]; 180 u_char nonce[8]; 181 182 if (mac->mac_len > sizeof(u)) 183 return SSH_ERR_INTERNAL_ERROR; 184 185 switch (mac->type) { 186 case SSH_DIGEST: 187 put_u32(b, seqno); 188 /* reset HMAC context */ 189 if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 || 190 ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 || 191 ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 || 192 ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0) 193 return SSH_ERR_LIBCRYPTO_ERROR; 194 break; 195 case SSH_UMAC: 196 POKE_U64(nonce, seqno); 197 umac_update(mac->umac_ctx, data, datalen); 198 umac_final(mac->umac_ctx, u.m, nonce); 199 break; 200 case SSH_UMAC128: 201 put_u64(nonce, seqno); 202 umac128_update(mac->umac_ctx, data, datalen); 203 umac128_final(mac->umac_ctx, u.m, nonce); 204 break; 205 default: 206 return SSH_ERR_INVALID_ARGUMENT; 207 } 208 if (digest != NULL) { 209 if (dlen > mac->mac_len) 210 dlen = mac->mac_len; 211 memcpy(digest, u.m, dlen); 212 } 213 return 0; 214 } 215 216 void 217 mac_clear(struct sshmac *mac) 218 { 219 if (mac->type == SSH_UMAC) { 220 if (mac->umac_ctx != NULL) 221 umac_delete(mac->umac_ctx); 222 } else if (mac->type == SSH_UMAC128) { 223 if (mac->umac_ctx != NULL) 224 umac128_delete(mac->umac_ctx); 225 } else if (mac->hmac_ctx != NULL) 226 ssh_hmac_free(mac->hmac_ctx); 227 mac->hmac_ctx = NULL; 228 mac->umac_ctx = NULL; 229 } 230 231 /* XXX copied from ciphers_valid */ 232 #define MAC_SEP "," 233 int 234 mac_valid(const char *names) 235 { 236 char *maclist, *cp, *p; 237 238 if (names == NULL || strcmp(names, "") == 0) 239 return 0; 240 if ((maclist = cp = strdup(names)) == NULL) 241 return 0; 242 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 243 (p = strsep(&cp, MAC_SEP))) { 244 if (mac_setup(NULL, p) < 0) { 245 free(maclist); 246 return 0; 247 } 248 } 249 free(maclist); 250 return 1; 251 } 252
