mac.c revision 295367
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 47struct 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 57static 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 { "hmac-ripemd160", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 }, 68 { "hmac-ripemd160@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 0 }, 69 { "umac-64@openssh.com", SSH_UMAC, 0, 0, 128, 64, 0 }, 70 { "umac-128@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 0 }, 71 72 /* Encrypt-then-MAC variants */ 73 { "hmac-sha1-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 0, 0, 0, 1 }, 74 { "hmac-sha1-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA1, 96, 0, 0, 1 }, 75#ifdef HAVE_EVP_SHA256 76 { "hmac-sha2-256-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA256, 0, 0, 0, 1 }, 77 { "hmac-sha2-512-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_SHA512, 0, 0, 0, 1 }, 78#endif 79 { "hmac-md5-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 0, 0, 0, 1 }, 80 { "hmac-md5-96-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_MD5, 96, 0, 0, 1 }, 81 { "hmac-ripemd160-etm@openssh.com", SSH_DIGEST, SSH_DIGEST_RIPEMD160, 0, 0, 0, 1 }, 82 { "umac-64-etm@openssh.com", SSH_UMAC, 0, 0, 128, 64, 1 }, 83 { "umac-128-etm@openssh.com", SSH_UMAC128, 0, 0, 128, 128, 1 }, 84 85 { NULL, 0, 0, 0, 0, 0, 0 } 86}; 87 88/* Returns a list of supported MACs separated by the specified char. */ 89char * 90mac_alg_list(char sep) 91{ 92 char *ret = NULL, *tmp; 93 size_t nlen, rlen = 0; 94 const struct macalg *m; 95 96 for (m = macs; m->name != NULL; m++) { 97 if (ret != NULL) 98 ret[rlen++] = sep; 99 nlen = strlen(m->name); 100 if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) { 101 free(ret); 102 return NULL; 103 } 104 ret = tmp; 105 memcpy(ret + rlen, m->name, nlen + 1); 106 rlen += nlen; 107 } 108 return ret; 109} 110 111static int 112mac_setup_by_alg(struct sshmac *mac, const struct macalg *macalg) 113{ 114 mac->type = macalg->type; 115 if (mac->type == SSH_DIGEST) { 116 if ((mac->hmac_ctx = ssh_hmac_start(macalg->alg)) == NULL) 117 return SSH_ERR_ALLOC_FAIL; 118 mac->key_len = mac->mac_len = ssh_hmac_bytes(macalg->alg); 119 } else { 120 mac->mac_len = macalg->len / 8; 121 mac->key_len = macalg->key_len / 8; 122 mac->umac_ctx = NULL; 123 } 124 if (macalg->truncatebits != 0) 125 mac->mac_len = macalg->truncatebits / 8; 126 mac->etm = macalg->etm; 127 return 0; 128} 129 130int 131mac_setup(struct sshmac *mac, char *name) 132{ 133 const struct macalg *m; 134 135 for (m = macs; m->name != NULL; m++) { 136 if (strcmp(name, m->name) != 0) 137 continue; 138 if (mac != NULL) 139 return mac_setup_by_alg(mac, m); 140 return 0; 141 } 142 return SSH_ERR_INVALID_ARGUMENT; 143} 144 145int 146mac_init(struct sshmac *mac) 147{ 148 if (mac->key == NULL) 149 return SSH_ERR_INVALID_ARGUMENT; 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 SSH_ERR_INVALID_ARGUMENT; 155 return 0; 156 case SSH_UMAC: 157 if ((mac->umac_ctx = umac_new(mac->key)) == NULL) 158 return SSH_ERR_ALLOC_FAIL; 159 return 0; 160 case SSH_UMAC128: 161 if ((mac->umac_ctx = umac128_new(mac->key)) == NULL) 162 return SSH_ERR_ALLOC_FAIL; 163 return 0; 164 default: 165 return SSH_ERR_INVALID_ARGUMENT; 166 } 167} 168 169int 170mac_compute(struct sshmac *mac, u_int32_t seqno, const u_char *data, int datalen, 171 u_char *digest, size_t dlen) 172{ 173 static union { 174 u_char m[SSH_DIGEST_MAX_LENGTH]; 175 u_int64_t for_align; 176 } u; 177 u_char b[4]; 178 u_char nonce[8]; 179 180 if (mac->mac_len > sizeof(u)) 181 return SSH_ERR_INTERNAL_ERROR; 182 183 switch (mac->type) { 184 case SSH_DIGEST: 185 put_u32(b, seqno); 186 /* reset HMAC context */ 187 if (ssh_hmac_init(mac->hmac_ctx, NULL, 0) < 0 || 188 ssh_hmac_update(mac->hmac_ctx, b, sizeof(b)) < 0 || 189 ssh_hmac_update(mac->hmac_ctx, data, datalen) < 0 || 190 ssh_hmac_final(mac->hmac_ctx, u.m, sizeof(u.m)) < 0) 191 return SSH_ERR_LIBCRYPTO_ERROR; 192 break; 193 case SSH_UMAC: 194 POKE_U64(nonce, seqno); 195 umac_update(mac->umac_ctx, data, datalen); 196 umac_final(mac->umac_ctx, u.m, nonce); 197 break; 198 case SSH_UMAC128: 199 put_u64(nonce, seqno); 200 umac128_update(mac->umac_ctx, data, datalen); 201 umac128_final(mac->umac_ctx, u.m, nonce); 202 break; 203 default: 204 return SSH_ERR_INVALID_ARGUMENT; 205 } 206 if (digest != NULL) { 207 if (dlen > mac->mac_len) 208 dlen = mac->mac_len; 209 memcpy(digest, u.m, dlen); 210 } 211 return 0; 212} 213 214void 215mac_clear(struct sshmac *mac) 216{ 217 if (mac->type == SSH_UMAC) { 218 if (mac->umac_ctx != NULL) 219 umac_delete(mac->umac_ctx); 220 } else if (mac->type == SSH_UMAC128) { 221 if (mac->umac_ctx != NULL) 222 umac128_delete(mac->umac_ctx); 223 } else if (mac->hmac_ctx != NULL) 224 ssh_hmac_free(mac->hmac_ctx); 225 mac->hmac_ctx = NULL; 226 mac->umac_ctx = NULL; 227} 228 229/* XXX copied from ciphers_valid */ 230#define MAC_SEP "," 231int 232mac_valid(const char *names) 233{ 234 char *maclist, *cp, *p; 235 236 if (names == NULL || strcmp(names, "") == 0) 237 return 0; 238 if ((maclist = cp = strdup(names)) == NULL) 239 return 0; 240 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 241 (p = strsep(&cp, MAC_SEP))) { 242 if (mac_setup(NULL, p) < 0) { 243 free(maclist); 244 return 0; 245 } 246 } 247 free(maclist); 248 return 1; 249} 250