1 /* $OpenBSD: mac.c,v 1.12 2006/08/03 03:34:42 deraadt 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 struct { 46 char *name; 47 const EVP_MD * (*mdfunc)(void); 48 int truncatebits; /* truncate digest if != 0 */ 49 } macs[] = { 50 { "hmac-sha1", EVP_sha1, 0, }, 51 { "hmac-sha1-96", EVP_sha1, 96 }, 52 { "hmac-md5", EVP_md5, 0 }, 53 { "hmac-md5-96", EVP_md5, 96 }, 54 { "hmac-ripemd160", EVP_ripemd160, 0 }, 55 { "hmac-ripemd160@openssh.com", EVP_ripemd160, 0 }, 56 { NULL, NULL, 0 } 57 }; 58 59 int 60 mac_init(Mac *mac, char *name) 61 { 62 int i, evp_len; 63 64 for (i = 0; macs[i].name; i++) { 65 if (strcmp(name, macs[i].name) == 0) { 66 if (mac != NULL) { 67 mac->md = (*macs[i].mdfunc)(); 68 if ((evp_len = EVP_MD_size(mac->md)) <= 0) 69 fatal("mac %s len %d", name, evp_len); 70 mac->key_len = mac->mac_len = (u_int)evp_len; 71 if (macs[i].truncatebits != 0) 72 mac->mac_len = macs[i].truncatebits/8; 73 } 74 debug2("mac_init: found %s", name); 75 return (0); 76 } 77 } 78 debug2("mac_init: unknown %s", name); 79 return (-1); 80 } 81 82 u_char * 83 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) 84 { 85 HMAC_CTX c; 86 static u_char m[EVP_MAX_MD_SIZE]; 87 u_char b[4]; 88 89 if (mac->key == NULL) 90 fatal("mac_compute: no key"); 91 if (mac->mac_len > sizeof(m)) 92 fatal("mac_compute: mac too long"); 93 HMAC_Init(&c, mac->key, mac->key_len, mac->md); 94 put_u32(b, seqno); 95 HMAC_Update(&c, b, sizeof(b)); 96 HMAC_Update(&c, data, datalen); 97 HMAC_Final(&c, m, NULL); 98 HMAC_cleanup(&c); 99 return (m); 100 } 101 102 /* XXX copied from ciphers_valid */ 103 #define MAC_SEP "," 104 int 105 mac_valid(const char *names) 106 { 107 char *maclist, *cp, *p; 108 109 if (names == NULL || strcmp(names, "") == 0) 110 return (0); 111 maclist = cp = xstrdup(names); 112 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 113 (p = strsep(&cp, MAC_SEP))) { 114 if (mac_init(NULL, p) < 0) { 115 debug("bad mac %s [%s]", p, names); 116 xfree(maclist); 117 return (0); 118 } else { 119 debug3("mac ok: %s [%s]", p, names); 120 } 121 } 122 debug3("macs ok: [%s]", names); 123 xfree(maclist); 124 return (1); 125 } 126