1 /* 2 * Copyright (c) 2001 Markus Friedl. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 */ 24 25 #include "includes.h" 26 RCSID("$OpenBSD: mac.c,v 1.7 2005/06/17 02:44:32 djm Exp $"); 27 28 #include <openssl/hmac.h> 29 30 #include "xmalloc.h" 31 #include "getput.h" 32 #include "log.h" 33 #include "cipher.h" 34 #include "kex.h" 35 #include "mac.h" 36 37 struct { 38 char *name; 39 const EVP_MD * (*mdfunc)(void); 40 int truncatebits; /* truncate digest if != 0 */ 41 } macs[] = { 42 { "hmac-sha1", EVP_sha1, 0, }, 43 { "hmac-sha1-96", EVP_sha1, 96 }, 44 { "hmac-md5", EVP_md5, 0 }, 45 { "hmac-md5-96", EVP_md5, 96 }, 46 { "hmac-ripemd160", EVP_ripemd160, 0 }, 47 { "hmac-ripemd160@openssh.com", EVP_ripemd160, 0 }, 48 { NULL, NULL, 0 } 49 }; 50 51 int 52 mac_init(Mac *mac, char *name) 53 { 54 int i, evp_len; 55 56 for (i = 0; macs[i].name; i++) { 57 if (strcmp(name, macs[i].name) == 0) { 58 if (mac != NULL) { 59 mac->md = (*macs[i].mdfunc)(); 60 if ((evp_len = EVP_MD_size(mac->md)) <= 0) 61 fatal("mac %s len %d", name, evp_len); 62 mac->key_len = mac->mac_len = (u_int)evp_len; 63 if (macs[i].truncatebits != 0) 64 mac->mac_len = macs[i].truncatebits/8; 65 } 66 debug2("mac_init: found %s", name); 67 return (0); 68 } 69 } 70 debug2("mac_init: unknown %s", name); 71 return (-1); 72 } 73 74 u_char * 75 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) 76 { 77 HMAC_CTX c; 78 static u_char m[EVP_MAX_MD_SIZE]; 79 u_char b[4]; 80 81 if (mac->key == NULL) 82 fatal("mac_compute: no key"); 83 if (mac->mac_len > sizeof(m)) 84 fatal("mac_compute: mac too long"); 85 HMAC_Init(&c, mac->key, mac->key_len, mac->md); 86 PUT_32BIT(b, seqno); 87 HMAC_Update(&c, b, sizeof(b)); 88 HMAC_Update(&c, data, datalen); 89 HMAC_Final(&c, m, NULL); 90 HMAC_cleanup(&c); 91 return (m); 92 } 93 94 /* XXX copied from ciphers_valid */ 95 #define MAC_SEP "," 96 int 97 mac_valid(const char *names) 98 { 99 char *maclist, *cp, *p; 100 101 if (names == NULL || strcmp(names, "") == 0) 102 return (0); 103 maclist = cp = xstrdup(names); 104 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 105 (p = strsep(&cp, MAC_SEP))) { 106 if (mac_init(NULL, p) < 0) { 107 debug("bad mac %s [%s]", p, names); 108 xfree(maclist); 109 return (0); 110 } else { 111 debug3("mac ok: %s [%s]", p, names); 112 } 113 } 114 debug3("macs ok: [%s]", names); 115 xfree(maclist); 116 return (1); 117 } 118