mac.c revision 264377
1/* $OpenBSD: mac.c,v 1.28 2014/02/07 06:55:54 djm 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 <stdarg.h> 31#include <string.h> 32#include <signal.h> 33 34#include "xmalloc.h" 35#include "log.h" 36#include "cipher.h" 37#include "buffer.h" 38#include "key.h" 39#include "kex.h" 40#include "mac.h" 41#include "misc.h" 42 43#include "digest.h" 44#include "hmac.h" 45#include "umac.h" 46 47#include "openbsd-compat/openssl-compat.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 53struct macalg { 54 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 63static 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#ifdef HAVE_EVP_SHA256 68 { "hmac-sha2-256", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 0 }, 69 { "hmac-sha2-512", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 0 }, 70#endif 71 { "hmac-md5", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 0 }, 72 { "hmac-md5-96", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 0 }, 73 { "hmac-ripemd160", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 }, 74 { "hmac-ripemd160@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 }, 75 { "umac-64@openssh.com", SSH_UMAC, 0, 0, 128, 64, 0 }, 76 { "umac-128@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 0 }, 77 78 /* Encrypt-then-MAC variants */ 79 { "hmac-sha1-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 }, 80 { "hmac-sha1-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 }, 81#ifdef HAVE_EVP_SHA256 82 { "hmac-sha2-256-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 }, 83 { "hmac-sha2-512-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 }, 84#endif 85 { "hmac-md5-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 }, 86 { "hmac-md5-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 }, 87 { "hmac-ripemd160-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 1 }, 88 { "umac-64-etm@openssh.com", SSH_UMAC, 0, 0, 128, 64, 1 }, 89 { "umac-128-etm@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 1 }, 90 91 { NULL, 0, 0, 0, 0, 0, 0 } 92}; 93 94/* Returns a list of supported MACs separated by the specified char. */ 95char * 96mac_alg_list(char sep) 97{ 98 char *ret = NULL; 99 size_t nlen, rlen = 0; 100 const struct macalg *m; 101 102 for (m = macs; m->name != NULL; m++) { 103 if (ret != NULL) 104 ret[rlen++] = sep; 105 nlen = strlen(m->name); 106 ret = xrealloc(ret, 1, rlen + nlen + 2); 107 memcpy(ret + rlen, m->name, nlen + 1); 108 rlen += nlen; 109 } 110 return ret; 111} 112 113static void 114mac_setup_by_alg(Mac *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 fatal("ssh_hmac_start(alg=%d) failed", macalg->alg); 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} 130 131int 132mac_setup(Mac *mac, char *name) 133{ 134 const struct macalg *m; 135 136 for (m = macs; m->name != NULL; m++) { 137 if (strcmp(name, m->name) != 0) 138 continue; 139 if (mac != NULL) { 140 mac_setup_by_alg(mac, m); 141 debug2("mac_setup: setup %s", name); 142 } 143 return (0); 144 } 145 debug2("mac_setup: unknown %s", name); 146 return (-1); 147} 148 149int 150mac_init(Mac *mac) 151{ 152 if (mac->key == NULL) 153 fatal("%s: no key", __func__); 154 switch (mac->type) { 155 case SSH_DIGEST: 156 if (mac->hmac_ctx == NULL || 157 ssh_hmac_init(mac->hmac_ctx, mac->key, mac->key_len) < 0) 158 return -1; 159 return 0; 160 case SSH_UMAC: 161 mac->umac_ctx = umac_new(mac->key); 162 return 0; 163 case SSH_UMAC128: 164 mac->umac_ctx = umac128_new(mac->key); 165 return 0; 166 default: 167 return -1; 168 } 169} 170 171u_char * 172mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) 173{ 174 static union { 175 u_char m[EVP_MAX_MD_SIZE]; 176 u_int64_t for_align; 177 } u; 178 u_char b[4], nonce[8]; 179 180 if (mac->mac_len > sizeof(u)) 181 fatal("mac_compute: mac too long %u %zu", 182 mac->mac_len, sizeof(u)); 183 184 switch (mac->type) { 185 case SSH_DIGEST: 186 put_u32(b, seqno); 187 /* reset HMAC context */ 188 if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 || 189 ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 || 190 ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 || 191 ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0) 192 fatal("ssh_hmac failed"); 193 break; 194 case SSH_UMAC: 195 put_u64(nonce, seqno); 196 umac_update(mac->umac_ctx, data, datalen); 197 umac_final(mac->umac_ctx, u.m, nonce); 198 break; 199 case SSH_UMAC128: 200 put_u64(nonce, seqno); 201 umac128_update(mac->umac_ctx, data, datalen); 202 umac128_final(mac->umac_ctx, u.m, nonce); 203 break; 204 default: 205 fatal("mac_compute: unknown MAC type"); 206 } 207 return (u.m); 208} 209 210void 211mac_clear(Mac *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 "," 227int 228mac_valid(const char *names) 229{ 230 char *maclist, *cp, *p; 231 232 if (names == NULL || strcmp(names, "") == 0) 233 return (0); 234 maclist = cp = xstrdup(names); 235 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 236 (p = strsep(&cp, MAC_SEP))) { 237 if (mac_setup(NULL, p) < 0) { 238 debug("bad mac %s [%s]", p, names); 239 free(maclist); 240 return (0); 241 } 242 } 243 debug3("macs ok: [%s]", names); 244 free(maclist); 245 return (1); 246} 247