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