1 /* 2 * Copyright (c) 2008 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 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 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * $DragonFly: src/usr.sbin/vknetd/filter.c,v 1.2 2008/05/27 22:47:16 dillon Exp $ 35 */ 36 /* 37 * Bridging code (serialized) 38 */ 39 #include "vknetd.h" 40 #include <netinet/ip.h> 41 #include <netinet/udp.h> 42 43 /* 44 * Return on-zero if the packet should be passed through, zero if it should 45 * be discarded. 46 */ 47 int 48 filter_ok(u_int8_t *pkt, int bytes) 49 { 50 struct ip *ip; 51 u_int16_t ether_type; 52 53 if (bytes < 12 + 2 + 20) 54 return(0); 55 56 /* 57 * Allow only ARP and IP packetes 58 */ 59 ether_type = ntohs(*(u_int16_t *)(pkt + 12)); 60 if (ether_type == ETHERTYPE_ARP) 61 return(1); 62 if (ether_type != ETHERTYPE_IP) 63 return(0); 64 65 /* 66 * Allow only ICMP, TCP, and UDP protocols. 67 */ 68 ip = (void *)(pkt + 14); 69 70 switch(ip->ip_p) { 71 case 1: /* ICMP */ 72 /* XXX fix me */ 73 break; 74 case 17: /* UDP */ 75 case 6: /* TCP */ 76 /* 77 * ip_src must represent our network or be 0. 78 * 0 is a special case, mainly so bootp (dhclient) gets 79 * through. 80 */ 81 if (ip->ip_src.s_addr == 0) 82 break; 83 if (SecureOpt && 84 (ip->ip_src.s_addr & NetMask.s_addr) != 85 (NetAddress.s_addr & NetMask.s_addr)) { 86 fprintf(stderr, "Filtered Address: %08x\n", 87 ntohl(ip->ip_src.s_addr)); 88 return(0); 89 } 90 break; 91 default: 92 if (SecureOpt) 93 return(0); 94 break; 95 } 96 return(1); 97 } 98 99