1 /* $NetBSD: mac.c,v 1.10 2014/10/20 03:05:13 christos Exp $ */ 2 /* $OpenBSD: mac.c,v 1.30 2014/04/30 19:07:48 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 1.10 2014/10/20 03:05:13 christos Exp $"); 29 #include <sys/types.h> 30 31 #include <openssl/hmac.h> 32 33 #include <string.h> 34 #include <signal.h> 35 36 #include "xmalloc.h" 37 #include "log.h" 38 #include "cipher.h" 39 #include "buffer.h" 40 #include "key.h" 41 #include "kex.h" 42 #include "mac.h" 43 #include "misc.h" 44 45 #include "digest.h" 46 #include "hmac.h" 47 #include "umac.h" 48 49 #define SSH_DIGEST 1 /* SSH_DIGEST_XXX */ 50 #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */ 51 #define SSH_UMAC128 3 52 53 struct macalg { 54 const char *name; 55 int type; 56 int alg; 57 int truncatebits; /* truncate digest if != 0 */ 58 int key_len; /* just for UMAC */ 59 int len; /* just for UMAC */ 60 int etm; /* Encrypt-then-MAC */ 61 }; 62 63 static const struct macalg macs[] = { 64 /* Encrypt-and-MAC (encrypt-and-authenticate) variants */ 65 { "hmac-sha1", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 0 }, 66 { "hmac-sha1-96", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 0 }, 67 { "hmac-sha2-256", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 0 }, 68 { "hmac-sha2-512", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 0 }, 69 { "hmac-md5", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 0 }, 70 { "hmac-md5-96", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 0 }, 71 { "hmac-ripemd160", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 }, 72 { "hmac-ripemd160@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 }, 73 { "umac-64@openssh.com", SSH_UMAC, 0, 0, 128, 64, 0 }, 74 { "umac-128@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 0 }, 75 76 /* Encrypt-then-MAC variants */ 77 { "hmac-sha1-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 }, 78 { "hmac-sha1-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 }, 79 { "hmac-sha2-256-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 }, 80 { "hmac-sha2-512-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 }, 81 { "hmac-md5-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 }, 82 { "hmac-md5-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 }, 83 { "hmac-ripemd160-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 1 }, 84 { "umac-64-etm@openssh.com", SSH_UMAC, 0, 0, 128, 64, 1 }, 85 { "umac-128-etm@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; 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 ret = xrealloc(ret, 1, rlen + nlen + 2); 103 memcpy(ret + rlen, m->name, nlen + 1); 104 rlen += nlen; 105 } 106 return ret; 107 } 108 109 static void 110 mac_setup_by_alg(Mac *mac, const struct macalg *macalg) 111 { 112 mac->type = macalg->type; 113 if (mac->type == SSH_DIGEST) { 114 if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL) 115 fatal("ssh_hmac_start(alg=%d) failed", macalg->alg); 116 mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg); 117 } else { 118 mac->mac_len = macalg->len / 8; 119 mac->key_len = macalg->key_len / 8; 120 mac->umac_ctx = NULL; 121 } 122 if (macalg->truncatebits != 0) 123 mac->mac_len = macalg->truncatebits / 8; 124 mac->etm = macalg->etm; 125 } 126 127 int 128 mac_setup(Mac *mac, char *name) 129 { 130 const struct macalg *m; 131 132 for (m = macs; m->name != NULL; m++) { 133 if (strcmp(name, m->name) != 0) 134 continue; 135 if (mac != NULL) { 136 mac_setup_by_alg(mac, m); 137 debug2("mac_setup: setup %s", name); 138 } 139 return (0); 140 } 141 debug2("mac_setup: unknown %s", name); 142 return (-1); 143 } 144 145 int 146 mac_init(Mac *mac) 147 { 148 if (mac->key == NULL) 149 fatal("%s: no key", __func__); 150 switch (mac->type) { 151 case SSH_DIGEST: 152 if (mac->hmac_ctx == NULL || 153 ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0) 154 return -1; 155 return 0; 156 case SSH_UMAC: 157 mac->umac_ctx = umac_new(mac->key); 158 return 0; 159 case SSH_UMAC128: 160 mac->umac_ctx = umac128_new(mac->key); 161 return 0; 162 default: 163 return -1; 164 } 165 } 166 167 u_char * 168 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) 169 { 170 static union { 171 u_char m[EVP_MAX_MD_SIZE]; 172 u_int64_t for_align; 173 } u; 174 u_char b[4]; 175 u_char nonce[8]; 176 177 if (mac->mac_len > sizeof(u)) 178 fatal("mac_compute: mac too long %u %zu", 179 mac->mac_len, sizeof(u)); 180 181 switch (mac->type) { 182 case SSH_DIGEST: 183 put_u32(b, seqno); 184 /* reset HMAC context */ 185 if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 || 186 ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 || 187 ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 || 188 ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0) 189 fatal("ssh_hmac failed"); 190 break; 191 case SSH_UMAC: 192 put_u64(nonce, seqno); 193 umac_update(mac->umac_ctx, data, datalen); 194 umac_final(mac->umac_ctx, u.m, nonce); 195 break; 196 case SSH_UMAC128: 197 put_u64(nonce, seqno); 198 umac128_update(mac->umac_ctx, data, datalen); 199 umac128_final(mac->umac_ctx, u.m, nonce); 200 break; 201 default: 202 fatal("mac_compute: unknown MAC type"); 203 } 204 return (u.m); 205 } 206 207 void 208 mac_clear(Mac *mac) 209 { 210 if (mac->type == SSH_UMAC) { 211 if (mac->umac_ctx != NULL) 212 umac_delete(mac->umac_ctx); 213 } else if (mac->type == SSH_UMAC128) { 214 if (mac->umac_ctx != NULL) 215 umac128_delete(mac->umac_ctx); 216 } else if (mac->hmac_ctx != NULL) 217 ssh_hmac_free(mac->hmac_ctx); 218 mac->hmac_ctx = NULL; 219 mac->umac_ctx = NULL; 220 } 221 222 /* XXX copied from ciphers_valid */ 223 #define MAC_SEP "," 224 int 225 mac_valid(const char *names) 226 { 227 char *maclist, *cp, *p; 228 229 if (names == NULL || strcmp(names, "") == 0) 230 return (0); 231 maclist = cp = xstrdup(names); 232 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 233 (p = strsep(&cp, MAC_SEP))) { 234 if (mac_setup(NULL, p) < 0) { 235 debug("bad mac %s [%s]", p, names); 236 free(maclist); 237 return (0); 238 } 239 } 240 debug3("macs ok: [%s]", names); 241 free(maclist); 242 return (1); 243 } 244