1 /* $NetBSD: mac.c,v 1.5 2012/05/02 02:41:08 christos Exp $ */ 2 /* $OpenBSD: mac.c,v 1.17 2011/12/02 00:43:57 djm 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 1.5 2012/05/02 02:41:08 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 52 struct { 53 const char *name; 54 int type; 55 const EVP_MD * (*mdfunc)(void); 56 int truncatebits; /* truncate digest if != 0 */ 57 int key_len; /* just for UMAC */ 58 int len; /* just for UMAC */ 59 } macs[] = { 60 { "hmac-sha1", SSH_EVP, EVP_sha1, 0, -1, -1 }, 61 { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, -1, -1 }, 62 { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, -1, -1 }, 63 { "hmac-sha2-256-96", SSH_EVP, EVP_sha256, 96, -1, -1 }, 64 { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, -1, -1 }, 65 { "hmac-sha2-512-96", SSH_EVP, EVP_sha512, 96, -1, -1 }, 66 { "hmac-md5", SSH_EVP, EVP_md5, 0, -1, -1 }, 67 { "hmac-md5-96", SSH_EVP, EVP_md5, 96, -1, -1 }, 68 { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, -1, -1 }, 69 { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, -1, -1 }, 70 #ifdef UMAC_HAS_BEEN_UNBROKEN 71 { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64 }, 72 #endif 73 { NULL, 0, NULL, 0, -1, -1 } 74 }; 75 76 static void 77 mac_setup_by_id(Mac *mac, int which) 78 { 79 int evp_len; 80 mac->type = macs[which].type; 81 if (mac->type == SSH_EVP) { 82 mac->evp_md = (*macs[which].mdfunc)(); 83 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0) 84 fatal("mac %s len %d", mac->name, evp_len); 85 mac->key_len = mac->mac_len = (u_int)evp_len; 86 } else { 87 mac->mac_len = macs[which].len / 8; 88 mac->key_len = macs[which].key_len / 8; 89 mac->umac_ctx = NULL; 90 } 91 if (macs[which].truncatebits != 0) 92 mac->mac_len = macs[which].truncatebits / 8; 93 } 94 95 int 96 mac_setup(Mac *mac, char *name) 97 { 98 int i; 99 100 for (i = 0; macs[i].name; i++) { 101 if (strcmp(name, macs[i].name) == 0) { 102 if (mac != NULL) 103 mac_setup_by_id(mac, i); 104 debug2("mac_setup: found %s", name); 105 return (0); 106 } 107 } 108 debug2("mac_setup: unknown %s", name); 109 return (-1); 110 } 111 112 int 113 mac_init(Mac *mac) 114 { 115 if (mac->key == NULL) 116 fatal("mac_init: no key"); 117 switch (mac->type) { 118 case SSH_EVP: 119 if (mac->evp_md == NULL) 120 return -1; 121 HMAC_CTX_init(&mac->evp_ctx); 122 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md); 123 return 0; 124 #ifdef UMAC_HAS_BEEN_UNBROKEN 125 case SSH_UMAC: 126 mac->umac_ctx = umac_new(mac->key); 127 return 0; 128 #endif 129 default: 130 return -1; 131 } 132 } 133 134 u_char * 135 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) 136 { 137 static u_char m[EVP_MAX_MD_SIZE]; 138 u_char b[4]; 139 #ifdef UMAC_HAS_BEEN_UNBROKEN 140 u_char nonce[8]; 141 #endif 142 143 if (mac->mac_len > sizeof(m)) 144 fatal("mac_compute: mac too long %u %lu", 145 mac->mac_len, (u_long)sizeof(m)); 146 147 switch (mac->type) { 148 case SSH_EVP: 149 put_u32(b, seqno); 150 /* reset HMAC context */ 151 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL); 152 HMAC_Update(&mac->evp_ctx, b, sizeof(b)); 153 HMAC_Update(&mac->evp_ctx, data, datalen); 154 HMAC_Final(&mac->evp_ctx, m, NULL); 155 break; 156 #ifdef UMAC_HAS_BEEN_UNBROKEN 157 case SSH_UMAC: 158 put_u64(nonce, seqno); 159 umac_update(mac->umac_ctx, data, datalen); 160 umac_final(mac->umac_ctx, m, nonce); 161 break; 162 #endif 163 default: 164 fatal("mac_compute: unknown MAC type"); 165 } 166 return (m); 167 } 168 169 void 170 mac_clear(Mac *mac) 171 { 172 #ifdef UMAC_HAS_BEEN_UNBROKEN 173 if (mac->type == SSH_UMAC) { 174 if (mac->umac_ctx != NULL) 175 umac_delete(mac->umac_ctx); 176 } else 177 #endif 178 if (mac->evp_md != NULL) 179 HMAC_cleanup(&mac->evp_ctx); 180 mac->evp_md = NULL; 181 mac->umac_ctx = NULL; 182 } 183 184 /* XXX copied from ciphers_valid */ 185 #define MAC_SEP "," 186 int 187 mac_valid(const char *names) 188 { 189 char *maclist, *cp, *p; 190 191 if (names == NULL || strcmp(names, "") == 0) 192 return (0); 193 maclist = cp = xstrdup(names); 194 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 195 (p = strsep(&cp, MAC_SEP))) { 196 if (mac_setup(NULL, p) < 0) { 197 debug("bad mac %s [%s]", p, names); 198 xfree(maclist); 199 return (0); 200 } else { 201 debug3("mac ok: %s [%s]", p, names); 202 } 203 } 204 debug3("macs ok: [%s]", names); 205 xfree(maclist); 206 return (1); 207 } 208