mac.c revision 262566
1/* $OpenBSD: mac.c,v 1.26 2014/01/04 17:50:55 tedu 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 <openssl/hmac.h> 31 32#include <stdarg.h> 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 "umac.h" 46 47#include "openbsd-compat/openssl-compat.h" 48 49#define SSH_EVP 1 /* OpenSSL EVP-based MAC */ 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 const EVP_MD * (*mdfunc)(void); 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_EVP, EVP_sha1, 0, 0, 0, 0 }, 66 { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, 0, 0, 0 }, 67#ifdef HAVE_EVP_SHA256 68 { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, 0, 0, 0 }, 69 { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, 0, 0, 0 }, 70#endif 71 { "hmac-md5", SSH_EVP, EVP_md5, 0, 0, 0, 0 }, 72 { "hmac-md5-96", SSH_EVP, EVP_md5, 96, 0, 0, 0 }, 73 { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 }, 74 { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 }, 75 { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 0 }, 76 { "umac-128@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 0 }, 77 78 /* Encrypt-then-MAC variants */ 79 { "hmac-sha1-etm@openssh.com", SSH_EVP, EVP_sha1, 0, 0, 0, 1 }, 80 { "hmac-sha1-96-etm@openssh.com", SSH_EVP, EVP_sha1, 96, 0, 0, 1 }, 81#ifdef HAVE_EVP_SHA256 82 { "hmac-sha2-256-etm@openssh.com", SSH_EVP, EVP_sha256, 0, 0, 0, 1 }, 83 { "hmac-sha2-512-etm@openssh.com", SSH_EVP, EVP_sha512, 0, 0, 0, 1 }, 84#endif 85 { "hmac-md5-etm@openssh.com", SSH_EVP, EVP_md5, 0, 0, 0, 1 }, 86 { "hmac-md5-96-etm@openssh.com", SSH_EVP, EVP_md5, 96, 0, 0, 1 }, 87 { "hmac-ripemd160-etm@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 1 }, 88 { "umac-64-etm@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 1 }, 89 { "umac-128-etm@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 1 }, 90 91 { NULL, 0, NULL, 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 int evp_len; 117 118 mac->type = macalg->type; 119 if (mac->type == SSH_EVP) { 120 mac->evp_md = macalg->mdfunc(); 121 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0) 122 fatal("mac %s len %d", mac->name, evp_len); 123 mac->key_len = mac->mac_len = (u_int)evp_len; 124 } else { 125 mac->mac_len = macalg->len / 8; 126 mac->key_len = macalg->key_len / 8; 127 mac->umac_ctx = NULL; 128 } 129 if (macalg->truncatebits != 0) 130 mac->mac_len = macalg->truncatebits / 8; 131 mac->etm = macalg->etm; 132} 133 134int 135mac_setup(Mac *mac, char *name) 136{ 137 const struct macalg *m; 138 139 for (m = macs; m->name != NULL; m++) { 140 if (strcmp(name, m->name) != 0) 141 continue; 142 if (mac != NULL) 143 mac_setup_by_alg(mac, m); 144 debug2("mac_setup: found %s", name); 145 return (0); 146 } 147 debug2("mac_setup: unknown %s", name); 148 return (-1); 149} 150 151int 152mac_init(Mac *mac) 153{ 154 if (mac->key == NULL) 155 fatal("mac_init: no key"); 156 switch (mac->type) { 157 case SSH_EVP: 158 if (mac->evp_md == NULL) 159 return -1; 160 HMAC_CTX_init(&mac->evp_ctx); 161 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md); 162 return 0; 163 case SSH_UMAC: 164 mac->umac_ctx = umac_new(mac->key); 165 return 0; 166 case SSH_UMAC128: 167 mac->umac_ctx = umac128_new(mac->key); 168 return 0; 169 default: 170 return -1; 171 } 172} 173 174u_char * 175mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) 176{ 177 static union { 178 u_char m[EVP_MAX_MD_SIZE]; 179 u_int64_t for_align; 180 } u; 181 u_char b[4], nonce[8]; 182 183 if (mac->mac_len > sizeof(u)) 184 fatal("mac_compute: mac too long %u %zu", 185 mac->mac_len, sizeof(u)); 186 187 switch (mac->type) { 188 case SSH_EVP: 189 put_u32(b, seqno); 190 /* reset HMAC context */ 191 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL); 192 HMAC_Update(&mac->evp_ctx, b, sizeof(b)); 193 HMAC_Update(&mac->evp_ctx, data, datalen); 194 HMAC_Final(&mac->evp_ctx, u.m, NULL); 195 break; 196 case SSH_UMAC: 197 put_u64(nonce, seqno); 198 umac_update(mac->umac_ctx, data, datalen); 199 umac_final(mac->umac_ctx, u.m, nonce); 200 break; 201 case SSH_UMAC128: 202 put_u64(nonce, seqno); 203 umac128_update(mac->umac_ctx, data, datalen); 204 umac128_final(mac->umac_ctx, u.m, nonce); 205 break; 206 default: 207 fatal("mac_compute: unknown MAC type"); 208 } 209 return (u.m); 210} 211 212void 213mac_clear(Mac *mac) 214{ 215 if (mac->type == SSH_UMAC) { 216 if (mac->umac_ctx != NULL) 217 umac_delete(mac->umac_ctx); 218 } else if (mac->type == SSH_UMAC128) { 219 if (mac->umac_ctx != NULL) 220 umac128_delete(mac->umac_ctx); 221 } else if (mac->evp_md != NULL) 222 HMAC_cleanup(&mac->evp_ctx); 223 mac->evp_md = NULL; 224 mac->umac_ctx = NULL; 225} 226 227/* XXX copied from ciphers_valid */ 228#define MAC_SEP "," 229int 230mac_valid(const char *names) 231{ 232 char *maclist, *cp, *p; 233 234 if (names == NULL || strcmp(names, "") == 0) 235 return (0); 236 maclist = cp = xstrdup(names); 237 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 238 (p = strsep(&cp, MAC_SEP))) { 239 if (mac_setup(NULL, p) < 0) { 240 debug("bad mac %s [%s]", p, names); 241 free(maclist); 242 return (0); 243 } else { 244 debug3("mac ok: %s [%s]", p, names); 245 } 246 } 247 debug3("macs ok: [%s]", names); 248 free(maclist); 249 return (1); 250} 251