1 /* $NetBSD: mac.c,v 1.11 2015/04/03 23:58:19 christos Exp $ */ 2 /* $OpenBSD: mac.c,v 1.32 2015/01/15 18:32:54 naddy Exp $ */ 3 /* 4 * Copyright (c) 2001 Markus Friedl. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 __RCSID("$NetBSD: mac.c,v 1.11 2015/04/03 23:58:19 christos Exp $"); 29 #include <sys/types.h> 30 31 #include <string.h> 32 #include <stdio.h> 33 #include <time.h> 34 35 #include "digest.h" 36 #include "hmac.h" 37 #include "umac.h" 38 #include "mac.h" 39 #include "misc.h" 40 #include "ssherr.h" 41 #include "sshbuf.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 const 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 { "hmac-sha2-256", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 0 }, 62 { "hmac-sha2-512", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 0 }, 63 { "hmac-md5", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 0 }, 64 { "hmac-md5-96", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 0 }, 65 { "hmac-ripemd160", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 }, 66 { "hmac-ripemd160@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 }, 67 { "umac-64@openssh.com", SSH_UMAC, 0, 0, 128, 64, 0 }, 68 { "umac-128@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 0 }, 69 70 /* Encrypt-then-MAC variants */ 71 { "hmac-sha1-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 }, 72 { "hmac-sha1-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 }, 73 { "hmac-sha2-256-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 }, 74 { "hmac-sha2-512-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 }, 75 { "hmac-md5-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 }, 76 { "hmac-md5-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 }, 77 { "hmac-ripemd160-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 1 }, 78 { "umac-64-etm@openssh.com", SSH_UMAC, 0, 0, 128, 64, 1 }, 79 { "umac-128-etm@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 1 }, 80 81 { NULL, 0, 0, 0, 0, 0, 0 } 82 }; 83 84 /* Returns a list of supported MACs separated by the specified char. */ 85 char * 86 mac_alg_list(char sep) 87 { 88 char *ret = NULL, *tmp; 89 size_t nlen, rlen = 0; 90 const struct macalg *m; 91 92 for (m = macs; m->name != NULL; m++) { 93 if (ret != NULL) 94 ret[rlen++] = sep; 95 nlen = strlen(m->name); 96 if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) { 97 free(ret); 98 return NULL; 99 } 100 ret = tmp; 101 memcpy(ret + rlen, m->name, nlen + 1); 102 rlen += nlen; 103 } 104 return ret; 105 } 106 107 static int 108 mac_setup_by_alg(struct sshmac *mac, const struct macalg *macalg) 109 { 110 mac->type = macalg->type; 111 if (mac->type == SSH_DIGEST) { 112 if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL) 113 return SSH_ERR_ALLOC_FAIL; 114 mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg); 115 } else { 116 mac->mac_len = macalg->len / 8; 117 mac->key_len = macalg->key_len / 8; 118 mac->umac_ctx = NULL; 119 } 120 if (macalg->truncatebits != 0) 121 mac->mac_len = macalg->truncatebits / 8; 122 mac->etm = macalg->etm; 123 return 0; 124 } 125 126 int 127 mac_setup(struct sshmac *mac, char *name) 128 { 129 const struct macalg *m; 130 131 for (m = macs; m->name != NULL; m++) { 132 if (strcmp(name, m->name) != 0) 133 continue; 134 if (mac != NULL) 135 return mac_setup_by_alg(mac, m); 136 return 0; 137 } 138 return SSH_ERR_INVALID_ARGUMENT; 139 } 140 141 int 142 mac_init(struct sshmac *mac) 143 { 144 if (mac->key == NULL) 145 return SSH_ERR_INVALID_ARGUMENT; 146 switch (mac->type) { 147 case SSH_DIGEST: 148 if (mac->hmac_ctx == NULL || 149 ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0) 150 return SSH_ERR_INVALID_ARGUMENT; 151 return 0; 152 case SSH_UMAC: 153 if ((mac->umac_ctx = umac_new(mac->key)) == NULL) 154 return SSH_ERR_ALLOC_FAIL; 155 return 0; 156 case SSH_UMAC128: 157 if ((mac->umac_ctx = umac128_new(mac->key)) == NULL) 158 return SSH_ERR_ALLOC_FAIL; 159 return 0; 160 default: 161 return SSH_ERR_INVALID_ARGUMENT; 162 } 163 } 164 165 int 166 mac_compute(struct sshmac *mac, u_int32_t seqno, const u_char *data, int datalen, 167 u_char *digest, size_t dlen) 168 { 169 static union { 170 u_char m[SSH_DIGEST_MAX_LENGTH]; 171 u_int64_t for_align; 172 } u; 173 u_char b[4]; 174 u_char nonce[8]; 175 176 if (mac->mac_len > sizeof(u)) 177 return SSH_ERR_INTERNAL_ERROR; 178 179 switch (mac->type) { 180 case SSH_DIGEST: 181 put_u32(b, seqno); 182 /* reset HMAC context */ 183 if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 || 184 ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 || 185 ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 || 186 ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0) 187 return SSH_ERR_LIBCRYPTO_ERROR; 188 break; 189 case SSH_UMAC: 190 POKE_U64(nonce, seqno); 191 umac_update(mac->umac_ctx, data, datalen); 192 umac_final(mac->umac_ctx, u.m, nonce); 193 break; 194 case SSH_UMAC128: 195 put_u64(nonce, seqno); 196 umac128_update(mac->umac_ctx, data, datalen); 197 umac128_final(mac->umac_ctx, u.m, nonce); 198 break; 199 default: 200 return SSH_ERR_INVALID_ARGUMENT; 201 } 202 if (digest != NULL) { 203 if (dlen > mac->mac_len) 204 dlen = mac->mac_len; 205 memcpy(digest, u.m, dlen); 206 } 207 return 0; 208 } 209 210 void 211 mac_clear(struct sshmac *mac) 212 { 213 if (mac->type == SSH_UMAC) { 214 if (mac->umac_ctx != NULL) 215 umac_delete(mac->umac_ctx); 216 } else if (mac->type == SSH_UMAC128) { 217 if (mac->umac_ctx != NULL) 218 umac128_delete(mac->umac_ctx); 219 } else if (mac->hmac_ctx != NULL) 220 ssh_hmac_free(mac->hmac_ctx); 221 mac->hmac_ctx = NULL; 222 mac->umac_ctx = NULL; 223 } 224 225 /* XXX copied from ciphers_valid */ 226 #define MAC_SEP "," 227 int 228 mac_valid(const char *names) 229 { 230 char *maclist, *cp, *p; 231 232 if (names == NULL || strcmp(names, "") == 0) 233 return 0; 234 if ((maclist = cp = strdup(names)) == NULL) 235 return 0; 236 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 237 (p = strsep(&cp, MAC_SEP))) { 238 if (mac_setup(NULL, p) < 0) { 239 free(maclist); 240 return 0; 241 } 242 } 243 free(maclist); 244 return 1; 245 } 246