1 /* $OpenBSD: cookie.c,v 1.17 2017/02/03 08:23:46 guenther Exp $ */ 2 /* $EOM: cookie.c,v 1.21 1999/08/05 15:00:04 niklas Exp $ */ 3 4 /* 5 * Copyright (c) 1998, 1999 Niklas Hallqvist. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 /* 29 * This code was written under funding by Ericsson Radio Systems. 30 */ 31 32 #include <sys/types.h> 33 #include <sys/socket.h> 34 #include <netinet/in.h> 35 #include <stdlib.h> 36 #include <string.h> 37 38 #include "cookie.h" 39 #include "exchange.h" 40 #include "hash.h" 41 #include "transport.h" 42 #include "util.h" 43 44 #define COOKIE_SECRET_SIZE 16 45 46 /* 47 * Generate an anti-clogging token (a protection against an attacker forcing 48 * us to keep state for a flood of connection requests) a.k.a. a cookie 49 * at BUF, LEN bytes long. The cookie will be generated by hashing of 50 * information found, among otherplaces, in transport T and exchange 51 * EXCHANGE. 52 */ 53 void 54 cookie_gen(struct transport *t, struct exchange *exchange, u_int8_t *buf, 55 size_t len) 56 { 57 struct hash *hash = hash_get(HASH_SHA1); 58 u_int8_t tmpsecret[COOKIE_SECRET_SIZE]; 59 struct sockaddr *name; 60 61 hash->Init(hash->ctx); 62 (*t->vtbl->get_dst)(t, &name); 63 hash->Update(hash->ctx, (u_int8_t *)name, SA_LEN(name)); 64 (*t->vtbl->get_src)(t, &name); 65 hash->Update(hash->ctx, (u_int8_t *)name, SA_LEN(name)); 66 if (exchange->initiator == 0) 67 hash->Update(hash->ctx, exchange->cookies + 68 ISAKMP_HDR_ICOOKIE_OFF, ISAKMP_HDR_ICOOKIE_LEN); 69 arc4random_buf(tmpsecret, COOKIE_SECRET_SIZE); 70 hash->Update(hash->ctx, tmpsecret, COOKIE_SECRET_SIZE); 71 hash->Final(hash->digest, hash->ctx); 72 memcpy(buf, hash->digest, len); 73 } 74