1/* $OpenBSD: mac.c,v 1.21 2012/12/11 22:51:45 sthen 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#ifdef __APPLE_CRYPTO__ 31#include "ossl-hmac.h" 32#else 33#include <openssl/hmac.h> 34#endif 35 36#include <stdarg.h> 37#include <string.h> 38#include <signal.h> 39 40#include "xmalloc.h" 41#include "log.h" 42#include "cipher.h" 43#include "buffer.h" 44#include "key.h" 45#include "kex.h" 46#include "mac.h" 47#include "misc.h" 48 49#include "umac.h" 50 51#include "openbsd-compat/openssl-compat.h" 52 53#define SSH_EVP 1 /* OpenSSL EVP-based MAC */ 54#define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */ 55#define SSH_UMAC128 3 56 57struct { 58 char *name; 59 int type; 60 const EVP_MD * (*mdfunc)(void); 61 int truncatebits; /* truncate digest if != 0 */ 62 int key_len; /* just for UMAC */ 63 int len; /* just for UMAC */ 64 int etm; /* Encrypt-then-MAC */ 65} macs[] = { 66 /* Encrypt-and-MAC (encrypt-and-authenticate) variants */ 67 { "hmac-sha1", SSH_EVP, EVP_sha1, 0, 0, 0, 0 }, 68 { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, 0, 0, 0 }, 69#ifdef HAVE_EVP_SHA256 70 { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, 0, 0, 0 }, 71 { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, 0, 0, 0 }, 72#endif 73 { "hmac-md5", SSH_EVP, EVP_md5, 0, 0, 0, 0 }, 74 { "hmac-md5-96", SSH_EVP, EVP_md5, 96, 0, 0, 0 }, 75 { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 }, 76 { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 }, 77 { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 0 }, 78 { "umac-128@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 0 }, 79 80 /* Encrypt-then-MAC variants */ 81 { "hmac-sha1-etm@openssh.com", SSH_EVP, EVP_sha1, 0, 0, 0, 1 }, 82 { "hmac-sha1-96-etm@openssh.com", SSH_EVP, EVP_sha1, 96, 0, 0, 1 }, 83#ifdef HAVE_EVP_SHA256 84 { "hmac-sha2-256-etm@openssh.com", SSH_EVP, EVP_sha256, 0, 0, 0, 1 }, 85 { "hmac-sha2-512-etm@openssh.com", SSH_EVP, EVP_sha512, 0, 0, 0, 1 }, 86#endif 87 { "hmac-md5-etm@openssh.com", SSH_EVP, EVP_md5, 0, 0, 0, 1 }, 88 { "hmac-md5-96-etm@openssh.com", SSH_EVP, EVP_md5, 96, 0, 0, 1 }, 89 { "hmac-ripemd160-etm@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 1 }, 90 { "umac-64-etm@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 1 }, 91 { "umac-128-etm@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 1 }, 92 93 { NULL, 0, NULL, 0, 0, 0, 0 } 94}; 95 96static void 97mac_setup_by_id(Mac *mac, int which) 98{ 99 int evp_len; 100 mac->type = macs[which].type; 101 if (mac->type == SSH_EVP) { 102 mac->evp_md = (*macs[which].mdfunc)(); 103 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0) 104 fatal("mac %s len %d", mac->name, evp_len); 105 mac->key_len = mac->mac_len = (u_int)evp_len; 106 } else { 107 mac->mac_len = macs[which].len / 8; 108 mac->key_len = macs[which].key_len / 8; 109 mac->umac_ctx = NULL; 110 } 111 if (macs[which].truncatebits != 0) 112 mac->mac_len = macs[which].truncatebits / 8; 113 mac->etm = macs[which].etm; 114} 115 116int 117mac_setup(Mac *mac, char *name) 118{ 119 int i; 120 121 for (i = 0; macs[i].name; i++) { 122 if (strcmp(name, macs[i].name) == 0) { 123 if (mac != NULL) 124 mac_setup_by_id(mac, i); 125 debug2("mac_setup: found %s", name); 126 return (0); 127 } 128 } 129 debug2("mac_setup: unknown %s", name); 130 return (-1); 131} 132 133int 134mac_init(Mac *mac) 135{ 136 if (mac->key == NULL) 137 fatal("mac_init: no key"); 138 switch (mac->type) { 139 case SSH_EVP: 140 if (mac->evp_md == NULL) 141 return -1; 142 HMAC_CTX_init(&mac->evp_ctx); 143 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md); 144 return 0; 145 case SSH_UMAC: 146 mac->umac_ctx = umac_new(mac->key); 147 return 0; 148 case SSH_UMAC128: 149 mac->umac_ctx = umac128_new(mac->key); 150 return 0; 151 default: 152 return -1; 153 } 154} 155 156u_char * 157mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) 158{ 159 static u_char m[EVP_MAX_MD_SIZE]; 160 u_char b[4], nonce[8]; 161 162 if (mac->mac_len > sizeof(m)) 163 fatal("mac_compute: mac too long %u %lu", 164 mac->mac_len, (u_long)sizeof(m)); 165 166 switch (mac->type) { 167 case SSH_EVP: 168 put_u32(b, seqno); 169 /* reset HMAC context */ 170 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL); 171 HMAC_Update(&mac->evp_ctx, b, sizeof(b)); 172 HMAC_Update(&mac->evp_ctx, data, datalen); 173 HMAC_Final(&mac->evp_ctx, m, NULL); 174 break; 175 case SSH_UMAC: 176 put_u64(nonce, seqno); 177 umac_update(mac->umac_ctx, data, datalen); 178 umac_final(mac->umac_ctx, m, nonce); 179 break; 180 case SSH_UMAC128: 181 put_u64(nonce, seqno); 182 umac128_update(mac->umac_ctx, data, datalen); 183 umac128_final(mac->umac_ctx, m, nonce); 184 break; 185 default: 186 fatal("mac_compute: unknown MAC type"); 187 } 188 return (m); 189} 190 191void 192mac_clear(Mac *mac) 193{ 194 if (mac->type == SSH_UMAC) { 195 if (mac->umac_ctx != NULL) 196 umac_delete(mac->umac_ctx); 197 } else if (mac->type == SSH_UMAC128) { 198 if (mac->umac_ctx != NULL) 199 umac128_delete(mac->umac_ctx); 200 } else if (mac->evp_md != NULL) 201 HMAC_cleanup(&mac->evp_ctx); 202 mac->evp_md = NULL; 203 mac->umac_ctx = NULL; 204} 205 206/* XXX copied from ciphers_valid */ 207#define MAC_SEP "," 208int 209mac_valid(const char *names) 210{ 211 char *maclist, *cp, *p; 212 213 if (names == NULL || strcmp(names, "") == 0) 214 return (0); 215 maclist = cp = xstrdup(names); 216 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 217 (p = strsep(&cp, MAC_SEP))) { 218 if (mac_setup(NULL, p) < 0) { 219 debug("bad mac %s [%s]", p, names); 220 xfree(maclist); 221 return (0); 222 } else { 223 debug3("mac ok: %s [%s]", p, names); 224 } 225 } 226 debug3("macs ok: [%s]", names); 227 xfree(maclist); 228 return (1); 229} 230