1 /* $OpenBSD: mac.c,v 1.15 2008/06/13 00:51:47 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 <sys/types.h> 27 28 #include <openssl/hmac.h> 29 30 #include <string.h> 31 #include <signal.h> 32 33 #include "xmalloc.h" 34 #include "log.h" 35 #include "cipher.h" 36 #include "buffer.h" 37 #include "key.h" 38 #include "kex.h" 39 #include "mac.h" 40 #include "misc.h" 41 42 #include "umac.h" 43 44 #define SSH_EVP 1 /* OpenSSL EVP-based MAC */ 45 #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */ 46 47 struct { 48 char *name; 49 int type; 50 const EVP_MD * (*mdfunc)(void); 51 int truncatebits; /* truncate digest if != 0 */ 52 int key_len; /* just for UMAC */ 53 int len; /* just for UMAC */ 54 } macs[] = { 55 { "hmac-sha1", SSH_EVP, EVP_sha1, 0, -1, -1 }, 56 { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, -1, -1 }, 57 { "hmac-md5", SSH_EVP, EVP_md5, 0, -1, -1 }, 58 { "hmac-md5-96", SSH_EVP, EVP_md5, 96, -1, -1 }, 59 { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, -1, -1 }, 60 { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, -1, -1 }, 61 { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64 }, 62 { NULL, 0, NULL, 0, -1, -1 } 63 }; 64 65 static void 66 mac_setup_by_id(Mac *mac, int which) 67 { 68 int evp_len; 69 mac->type = macs[which].type; 70 if (mac->type == SSH_EVP) { 71 mac->evp_md = (*macs[which].mdfunc)(); 72 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0) 73 fatal("mac %s len %d", mac->name, evp_len); 74 mac->key_len = mac->mac_len = (u_int)evp_len; 75 } else { 76 mac->mac_len = macs[which].len / 8; 77 mac->key_len = macs[which].key_len / 8; 78 mac->umac_ctx = NULL; 79 } 80 if (macs[which].truncatebits != 0) 81 mac->mac_len = macs[which].truncatebits / 8; 82 } 83 84 int 85 mac_setup(Mac *mac, char *name) 86 { 87 int i; 88 89 for (i = 0; macs[i].name; i++) { 90 if (strcmp(name, macs[i].name) == 0) { 91 if (mac != NULL) 92 mac_setup_by_id(mac, i); 93 debug2("mac_setup: found %s", name); 94 return (0); 95 } 96 } 97 debug2("mac_setup: unknown %s", name); 98 return (-1); 99 } 100 101 int 102 mac_init(Mac *mac) 103 { 104 if (mac->key == NULL) 105 fatal("mac_init: no key"); 106 switch (mac->type) { 107 case SSH_EVP: 108 if (mac->evp_md == NULL) 109 return -1; 110 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md); 111 return 0; 112 case SSH_UMAC: 113 mac->umac_ctx = umac_new(mac->key); 114 return 0; 115 default: 116 return -1; 117 } 118 } 119 120 u_char * 121 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) 122 { 123 static u_char m[EVP_MAX_MD_SIZE]; 124 u_char b[4], nonce[8]; 125 126 if (mac->mac_len > sizeof(m)) 127 fatal("mac_compute: mac too long %u %lu", 128 mac->mac_len, (u_long)sizeof(m)); 129 130 switch (mac->type) { 131 case SSH_EVP: 132 put_u32(b, seqno); 133 /* reset HMAC context */ 134 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL); 135 HMAC_Update(&mac->evp_ctx, b, sizeof(b)); 136 HMAC_Update(&mac->evp_ctx, data, datalen); 137 HMAC_Final(&mac->evp_ctx, m, NULL); 138 break; 139 case SSH_UMAC: 140 put_u64(nonce, seqno); 141 umac_update(mac->umac_ctx, data, datalen); 142 umac_final(mac->umac_ctx, m, nonce); 143 break; 144 default: 145 fatal("mac_compute: unknown MAC type"); 146 } 147 return (m); 148 } 149 150 void 151 mac_clear(Mac *mac) 152 { 153 if (mac->type == SSH_UMAC) { 154 if (mac->umac_ctx != NULL) 155 umac_delete(mac->umac_ctx); 156 } else if (mac->evp_md != NULL) 157 HMAC_cleanup(&mac->evp_ctx); 158 mac->evp_md = NULL; 159 mac->umac_ctx = NULL; 160 } 161 162 /* XXX copied from ciphers_valid */ 163 #define MAC_SEP "," 164 int 165 mac_valid(const char *names) 166 { 167 char *maclist, *cp, *p; 168 169 if (names == NULL || strcmp(names, "") == 0) 170 return (0); 171 maclist = cp = xstrdup(names); 172 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 173 (p = strsep(&cp, MAC_SEP))) { 174 if (mac_setup(NULL, p) < 0) { 175 debug("bad mac %s [%s]", p, names); 176 xfree(maclist); 177 return (0); 178 } else { 179 debug3("mac ok: %s [%s]", p, names); 180 } 181 } 182 debug3("macs ok: [%s]", names); 183 xfree(maclist); 184 return (1); 185 } 186