1 /* $NetBSD: mac.c,v 1.7 2013/03/29 16:19:45 christos Exp $ */ 2 /* $OpenBSD: mac.c,v 1.21 2012/12/11 22:51:45 sthen Exp $ */ 3 /* 4 * Copyright (c) 2001 Markus Friedl. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 __RCSID("$NetBSD: mac.c,v 1.7 2013/03/29 16:19:45 christos Exp $"); 29 #include <sys/types.h> 30 31 #include <openssl/hmac.h> 32 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 #ifdef UMAC_HAS_BEEN_UNBROKEN 46 #include "umac.h" 47 #endif 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 53 struct { 54 const 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 { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, 0, 0, 0 }, 66 { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, 0, 0, 0 }, 67 { "hmac-md5", SSH_EVP, EVP_md5, 0, 0, 0, 0 }, 68 { "hmac-md5-96", SSH_EVP, EVP_md5, 96, 0, 0, 0 }, 69 { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 }, 70 { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 }, 71 #ifdef UMAC_HAS_BEEN_UNBROKEN 72 { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 0 }, 73 { "umac-128@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 0 }, 74 #endif 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 { "hmac-sha2-256-etm@openssh.com", SSH_EVP, EVP_sha256, 0, 0, 0, 1 }, 80 { "hmac-sha2-512-etm@openssh.com", SSH_EVP, EVP_sha512, 0, 0, 0, 1 }, 81 { "hmac-md5-etm@openssh.com", SSH_EVP, EVP_md5, 0, 0, 0, 1 }, 82 { "hmac-md5-96-etm@openssh.com", SSH_EVP, EVP_md5, 96, 0, 0, 1 }, 83 { "hmac-ripemd160-etm@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 1 }, 84 { "umac-64-etm@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 1 }, 85 { "umac-128-etm@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 1 }, 86 87 { NULL, 0, NULL, 0, 0, 0, 0 } 88 }; 89 90 static void 91 mac_setup_by_id(Mac *mac, int which) 92 { 93 int evp_len; 94 mac->type = macs[which].type; 95 if (mac->type == SSH_EVP) { 96 mac->evp_md = (*macs[which].mdfunc)(); 97 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0) 98 fatal("mac %s len %d", mac->name, evp_len); 99 mac->key_len = mac->mac_len = (u_int)evp_len; 100 } else { 101 mac->mac_len = macs[which].len / 8; 102 mac->key_len = macs[which].key_len / 8; 103 mac->umac_ctx = NULL; 104 } 105 if (macs[which].truncatebits != 0) 106 mac->mac_len = macs[which].truncatebits / 8; 107 mac->etm = macs[which].etm; 108 } 109 110 int 111 mac_setup(Mac *mac, char *name) 112 { 113 int i; 114 115 for (i = 0; macs[i].name; i++) { 116 if (strcmp(name, macs[i].name) == 0) { 117 if (mac != NULL) 118 mac_setup_by_id(mac, i); 119 debug2("mac_setup: found %s", name); 120 return (0); 121 } 122 } 123 debug2("mac_setup: unknown %s", name); 124 return (-1); 125 } 126 127 int 128 mac_init(Mac *mac) 129 { 130 if (mac->key == NULL) 131 fatal("mac_init: no key"); 132 switch (mac->type) { 133 case SSH_EVP: 134 if (mac->evp_md == NULL) 135 return -1; 136 HMAC_CTX_init(&mac->evp_ctx); 137 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md); 138 return 0; 139 #ifdef UMAC_HAS_BEEN_UNBROKEN 140 case SSH_UMAC: 141 mac->umac_ctx = umac_new(mac->key); 142 return 0; 143 case SSH_UMAC128: 144 mac->umac_ctx = umac128_new(mac->key); 145 return 0; 146 #endif 147 default: 148 return -1; 149 } 150 } 151 152 u_char * 153 mac_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]; 157 #ifdef UMAC_HAS_BEEN_UNBROKEN 158 u_char nonce[8]; 159 #endif 160 161 if (mac->mac_len > sizeof(m)) 162 fatal("mac_compute: mac too long %u %lu", 163 mac->mac_len, (u_long)sizeof(m)); 164 165 switch (mac->type) { 166 case SSH_EVP: 167 put_u32(b, seqno); 168 /* reset HMAC context */ 169 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL); 170 HMAC_Update(&mac->evp_ctx, b, sizeof(b)); 171 HMAC_Update(&mac->evp_ctx, data, datalen); 172 HMAC_Final(&mac->evp_ctx, m, NULL); 173 break; 174 #ifdef UMAC_HAS_BEEN_UNBROKEN 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 #endif 186 default: 187 fatal("mac_compute: unknown MAC type"); 188 } 189 return (m); 190 } 191 192 void 193 mac_clear(Mac *mac) 194 { 195 #ifdef UMAC_HAS_BEEN_UNBROKEN 196 if (mac->type == SSH_UMAC) { 197 if (mac->umac_ctx != NULL) 198 umac_delete(mac->umac_ctx); 199 } else if (mac->type == SSH_UMAC128) { 200 if (mac->umac_ctx != NULL) 201 umac128_delete(mac->umac_ctx); 202 } else 203 #endif 204 if (mac->evp_md != NULL) 205 HMAC_cleanup(&mac->evp_ctx); 206 mac->evp_md = NULL; 207 mac->umac_ctx = NULL; 208 } 209 210 /* XXX copied from ciphers_valid */ 211 #define MAC_SEP "," 212 int 213 mac_valid(const char *names) 214 { 215 char *maclist, *cp, *p; 216 217 if (names == NULL || strcmp(names, "") == 0) 218 return (0); 219 maclist = cp = xstrdup(names); 220 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 221 (p = strsep(&cp, MAC_SEP))) { 222 if (mac_setup(NULL, p) < 0) { 223 debug("bad mac %s [%s]", p, names); 224 xfree(maclist); 225 return (0); 226 } else { 227 debug3("mac ok: %s [%s]", p, names); 228 } 229 } 230 debug3("macs ok: [%s]", names); 231 xfree(maclist); 232 return (1); 233 } 234