1 /* $OpenBSD: mac.c,v 1.18 2012/06/28 05:07:45 dtucker 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 52 struct { 53 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 #ifdef HAVE_EVP_SHA256 63 { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, -1, -1 }, 64 { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, -1, -1 }, 65 #endif 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 { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64 }, 71 { NULL, 0, NULL, 0, -1, -1 } 72 }; 73 74 static void 75 mac_setup_by_id(Mac *mac, int which) 76 { 77 int evp_len; 78 mac->type = macs[which].type; 79 if (mac->type == SSH_EVP) { 80 mac->evp_md = (*macs[which].mdfunc)(); 81 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0) 82 fatal("mac %s len %d", mac->name, evp_len); 83 mac->key_len = mac->mac_len = (u_int)evp_len; 84 } else { 85 mac->mac_len = macs[which].len / 8; 86 mac->key_len = macs[which].key_len / 8; 87 mac->umac_ctx = NULL; 88 } 89 if (macs[which].truncatebits != 0) 90 mac->mac_len = macs[which].truncatebits / 8; 91 } 92 93 int 94 mac_setup(Mac *mac, char *name) 95 { 96 int i; 97 98 for (i = 0; macs[i].name; i++) { 99 if (strcmp(name, macs[i].name) == 0) { 100 if (mac != NULL) 101 mac_setup_by_id(mac, i); 102 debug2("mac_setup: found %s", name); 103 return (0); 104 } 105 } 106 debug2("mac_setup: unknown %s", name); 107 return (-1); 108 } 109 110 int 111 mac_init(Mac *mac) 112 { 113 if (mac->key == NULL) 114 fatal("mac_init: no key"); 115 switch (mac->type) { 116 case SSH_EVP: 117 if (mac->evp_md == NULL) 118 return -1; 119 HMAC_CTX_init(&mac->evp_ctx); 120 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md); 121 return 0; 122 case SSH_UMAC: 123 mac->umac_ctx = umac_new(mac->key); 124 return 0; 125 default: 126 return -1; 127 } 128 } 129 130 u_char * 131 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) 132 { 133 static u_char m[EVP_MAX_MD_SIZE]; 134 u_char b[4], nonce[8]; 135 136 if (mac->mac_len > sizeof(m)) 137 fatal("mac_compute: mac too long %u %lu", 138 mac->mac_len, (u_long)sizeof(m)); 139 140 switch (mac->type) { 141 case SSH_EVP: 142 put_u32(b, seqno); 143 /* reset HMAC context */ 144 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL); 145 HMAC_Update(&mac->evp_ctx, b, sizeof(b)); 146 HMAC_Update(&mac->evp_ctx, data, datalen); 147 HMAC_Final(&mac->evp_ctx, m, NULL); 148 break; 149 case SSH_UMAC: 150 put_u64(nonce, seqno); 151 umac_update(mac->umac_ctx, data, datalen); 152 umac_final(mac->umac_ctx, m, nonce); 153 break; 154 default: 155 fatal("mac_compute: unknown MAC type"); 156 } 157 return (m); 158 } 159 160 void 161 mac_clear(Mac *mac) 162 { 163 if (mac->type == SSH_UMAC) { 164 if (mac->umac_ctx != NULL) 165 umac_delete(mac->umac_ctx); 166 } else if (mac->evp_md != NULL) 167 HMAC_cleanup(&mac->evp_ctx); 168 mac->evp_md = NULL; 169 mac->umac_ctx = NULL; 170 } 171 172 /* XXX copied from ciphers_valid */ 173 #define MAC_SEP "," 174 int 175 mac_valid(const char *names) 176 { 177 char *maclist, *cp, *p; 178 179 if (names == NULL || strcmp(names, "") == 0) 180 return (0); 181 maclist = cp = xstrdup(names); 182 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 183 (p = strsep(&cp, MAC_SEP))) { 184 if (mac_setup(NULL, p) < 0) { 185 debug("bad mac %s [%s]", p, names); 186 xfree(maclist); 187 return (0); 188 } else { 189 debug3("mac ok: %s [%s]", p, names); 190 } 191 } 192 debug3("macs ok: [%s]", names); 193 xfree(maclist); 194 return (1); 195 } 196