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 <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 struct { 43 char *name; 44 const EVP_MD * (*mdfunc)(void); 45 int truncatebits; /* truncate digest if != 0 */ 46 } macs[] = { 47 { "hmac-sha1", EVP_sha1, 0, }, 48 { "hmac-sha1-96", EVP_sha1, 96 }, 49 { "hmac-md5", EVP_md5, 0 }, 50 { "hmac-md5-96", EVP_md5, 96 }, 51 { "hmac-ripemd160", EVP_ripemd160, 0 }, 52 { "hmac-ripemd160@openssh.com", EVP_ripemd160, 0 }, 53 { NULL, NULL, 0 } 54 }; 55 56 int 57 mac_init(Mac *mac, char *name) 58 { 59 int i, evp_len; 60 61 for (i = 0; macs[i].name; i++) { 62 if (strcmp(name, macs[i].name) == 0) { 63 if (mac != NULL) { 64 mac->md = (*macs[i].mdfunc)(); 65 if ((evp_len = EVP_MD_size(mac->md)) <= 0) 66 fatal("mac %s len %d", name, evp_len); 67 mac->key_len = mac->mac_len = (u_int)evp_len; 68 if (macs[i].truncatebits != 0) 69 mac->mac_len = macs[i].truncatebits/8; 70 } 71 debug2("mac_init: found %s", name); 72 return (0); 73 } 74 } 75 debug2("mac_init: unknown %s", name); 76 return (-1); 77 } 78 79 u_char * 80 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen) 81 { 82 HMAC_CTX c; 83 static u_char m[EVP_MAX_MD_SIZE]; 84 u_char b[4]; 85 86 if (mac->key == NULL) 87 fatal("mac_compute: no key"); 88 if (mac->mac_len > sizeof(m)) 89 fatal("mac_compute: mac too long"); 90 HMAC_Init(&c, mac->key, mac->key_len, mac->md); 91 put_u32(b, seqno); 92 HMAC_Update(&c, b, sizeof(b)); 93 HMAC_Update(&c, data, datalen); 94 HMAC_Final(&c, m, NULL); 95 HMAC_cleanup(&c); 96 return (m); 97 } 98 99 /* XXX copied from ciphers_valid */ 100 #define MAC_SEP "," 101 int 102 mac_valid(const char *names) 103 { 104 char *maclist, *cp, *p; 105 106 if (names == NULL || strcmp(names, "") == 0) 107 return (0); 108 maclist = cp = xstrdup(names); 109 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0'; 110 (p = strsep(&cp, MAC_SEP))) { 111 if (mac_init(NULL, p) < 0) { 112 debug("bad mac %s [%s]", p, names); 113 xfree(maclist); 114 return (0); 115 } else { 116 debug3("mac ok: %s [%s]", p, names); 117 } 118 } 119 debug3("macs ok: [%s]", names); 120 xfree(maclist); 121 return (1); 122 } 123