mac.c revision 248619
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#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 { 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} macs[] = { 62 /* Encrypt-and-MAC (encrypt-and-authenticate) variants */ 63 { "hmac-sha1", SSH_EVP, EVP_sha1, 0, 0, 0, 0 }, 64 { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, 0, 0, 0 }, 65#ifdef HAVE_EVP_SHA256 66 { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, 0, 0, 0 }, 67 { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, 0, 0, 0 }, 68#endif 69 { "hmac-md5", SSH_EVP, EVP_md5, 0, 0, 0, 0 }, 70 { "hmac-md5-96", SSH_EVP, EVP_md5, 96, 0, 0, 0 }, 71 { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 }, 72 { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 }, 73 { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 0 }, 74 { "umac-128@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 0 }, 75 76 /* Encrypt-then-MAC variants */ 77 { "hmac-sha1-etm@openssh.com", SSH_EVP, EVP_sha1, 0, 0, 0, 1 }, 78 { "hmac-sha1-96-etm@openssh.com", SSH_EVP, EVP_sha1, 96, 0, 0, 1 }, 79#ifdef HAVE_EVP_SHA256 80 { "hmac-sha2-256-etm@openssh.com", SSH_EVP, EVP_sha256, 0, 0, 0, 1 }, 81 { "hmac-sha2-512-etm@openssh.com", SSH_EVP, EVP_sha512, 0, 0, 0, 1 }, 82#endif 83 { "hmac-md5-etm@openssh.com", SSH_EVP, EVP_md5, 0, 0, 0, 1 }, 84 { "hmac-md5-96-etm@openssh.com", SSH_EVP, EVP_md5, 96, 0, 0, 1 }, 85 { "hmac-ripemd160-etm@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 1 }, 86 { "umac-64-etm@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 1 }, 87 { "umac-128-etm@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 1 }, 88 89 { NULL, 0, NULL, 0, 0, 0, 0 } 90}; 91 92static void 93mac_setup_by_id(Mac *mac, int which) 94{ 95 int evp_len; 96 mac->type = macs[which].type; 97 if (mac->type == SSH_EVP) { 98 mac->evp_md = (*macs[which].mdfunc)(); 99 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0) 100 fatal("mac %s len %d", mac->name, evp_len); 101 mac->key_len = mac->mac_len = (u_int)evp_len; 102 } else { 103 mac->mac_len = macs[which].len / 8; 104 mac->key_len = macs[which].key_len / 8; 105 mac->umac_ctx = NULL; 106 } 107 if (macs[which].truncatebits != 0) 108 mac->mac_len = macs[which].truncatebits / 8; 109 mac->etm = macs[which].etm; 110} 111 112int 113mac_setup(Mac *mac, char *name) 114{ 115 int i; 116 117 for (i = 0; macs[i].name; i++) { 118 if (strcmp(name, macs[i].name) == 0) { 119 if (mac != NULL) 120 mac_setup_by_id(mac, i); 121 debug2("mac_setup: found %s", name); 122 return (0); 123 } 124 } 125 debug2("mac_setup: unknown %s", name); 126 return (-1); 127} 128 129int 130mac_init(Mac *mac) 131{ 132 if (mac->key == NULL) 133 fatal("mac_init: no key"); 134 switch (mac->type) { 135 case SSH_EVP: 136 if (mac->evp_md == NULL) 137 return -1; 138 HMAC_CTX_init(&mac->evp_ctx); 139 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md); 140 return 0; 141 case SSH_UMAC: 142 mac->umac_ctx = umac_new(mac->key); 143 return 0; 144 case SSH_UMAC128: 145 mac->umac_ctx = umac128_new(mac->key); 146 return 0; 147 default: 148 return -1; 149 } 150} 151 152u_char * 153mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) 154{ 155 static u_char m[EVP_MAX_MD_SIZE]; 156 u_char b[4], nonce[8]; 157 158 if (mac->mac_len > sizeof(m)) 159 fatal("mac_compute: mac too long %u %lu", 160 mac->mac_len, (u_long)sizeof(m)); 161 162 switch (mac->type) { 163 case SSH_EVP: 164 put_u32(b, seqno); 165 /* reset HMAC context */ 166 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL); 167 HMAC_Update(&mac->evp_ctx, b, sizeof(b)); 168 HMAC_Update(&mac->evp_ctx, data, datalen); 169 HMAC_Final(&mac->evp_ctx, m, NULL); 170 break; 171 case SSH_UMAC: 172 put_u64(nonce, seqno); 173 umac_update(mac->umac_ctx, data, datalen); 174 umac_final(mac->umac_ctx, m, nonce); 175 break; 176 case SSH_UMAC128: 177 put_u64(nonce, seqno); 178 umac128_update(mac->umac_ctx, data, datalen); 179 umac128_final(mac->umac_ctx, m, nonce); 180 break; 181 default: 182 fatal("mac_compute: unknown MAC type"); 183 } 184 return (m); 185} 186 187void 188mac_clear(Mac *mac) 189{ 190 if (mac->type == SSH_UMAC) { 191 if (mac->umac_ctx != NULL) 192 umac_delete(mac->umac_ctx); 193 } else if (mac->type == SSH_UMAC128) { 194 if (mac->umac_ctx != NULL) 195 umac128_delete(mac->umac_ctx); 196 } else if (mac->evp_md != NULL) 197 HMAC_cleanup(&mac->evp_ctx); 198 mac->evp_md = NULL; 199 mac->umac_ctx = NULL; 200} 201 202/* XXX copied from ciphers_valid */ 203#define MAC_SEP "," 204int 205mac_valid(const char *names) 206{ 207 char *maclist, *cp, *p; 208 209 if (names == NULL || strcmp(names, "") == 0) 210 return (0); 211 maclist = cp = xstrdup(names); 212 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 213 (p = strsep(&cp, MAC_SEP))) { 214 if (mac_setup(NULL, p) < 0) { 215 debug("bad mac %s [%s]", p, names); 216 xfree(maclist); 217 return (0); 218 } else { 219 debug3("mac ok: %s [%s]", p, names); 220 } 221 } 222 debug3("macs ok: [%s]", names); 223 xfree(maclist); 224 return (1); 225} 226