1 /* $NetBSD: bpf-filter.h,v 1.9 2014/11/07 20:51:02 roy Exp $ */ 2 3 /* 4 * dhcpcd - DHCP client daemon 5 * Copyright (c) 2006-2008 Roy Marples <roy@marples.name> 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 AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #ifndef BPF_ETHCOOK 30 # define BPF_ETHCOOK 0 31 #endif 32 #ifndef BPF_WHOLEPACKET 33 # define BPF_WHOLEPACKET ~0U 34 #endif 35 static const struct bpf_insn arp_bpf_filter [] = { 36 #ifndef BPF_SKIPTYPE 37 /* Make sure this is an ARP packet... */ 38 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12), 39 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_ARP, 0, 3), 40 #endif 41 /* Make sure this is an ARP REQUEST... */ 42 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK), 43 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 2, 0), 44 /* or ARP REPLY... */ 45 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK), 46 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 0, 1), 47 /* If we passed all the tests, ask for the whole packet. */ 48 BPF_STMT(BPF_RET + BPF_K, BPF_WHOLEPACKET), 49 /* Otherwise, drop it. */ 50 BPF_STMT(BPF_RET + BPF_K, 0), 51 }; 52 #define arp_bpf_filter_len sizeof(arp_bpf_filter) / sizeof(arp_bpf_filter[0]) 53 54 55 /* dhcp_bpf_filter taken from bpf.c in dhcp-3.1.0 56 * 57 * Copyright (c) 2004,2007 by Internet Systems Consortium, Inc. ("ISC") 58 * Copyright (c) 1996-2003 by Internet Software Consortium 59 * 60 * Permission to use, copy, modify, and distribute this software for any 61 * purpose with or without fee is hereby granted, provided that the above 62 * copyright notice and this permission notice appear in all copies. 63 * 64 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 65 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 66 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 67 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 68 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 69 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 70 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 71 * 72 * Internet Systems Consortium, Inc. 73 * 950 Charter Street 74 * Redwood City, CA 94063 75 * <info@isc.org> 76 * http://www.isc.org/ 77 */ 78 79 static const struct bpf_insn dhcp_bpf_filter [] = { 80 #ifndef BPF_SKIPTYPE 81 /* Make sure this is an IP packet... */ 82 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12), 83 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 8), 84 #endif 85 /* Make sure it's a UDP packet... */ 86 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 23 + BPF_ETHCOOK), 87 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 6), 88 /* Make sure this isn't a fragment... */ 89 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK), 90 BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 4, 0), 91 /* Get the IP header length... */ 92 BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, 14 + BPF_ETHCOOK), 93 /* Make sure it's to the right port... */ 94 BPF_STMT(BPF_LD + BPF_H + BPF_IND, 16 + BPF_ETHCOOK), 95 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_CLIENT_PORT, 0, 1), 96 /* If we passed all the tests, ask for the whole packet. */ 97 BPF_STMT(BPF_RET + BPF_K, BPF_WHOLEPACKET), 98 /* Otherwise, drop it. */ 99 BPF_STMT(BPF_RET + BPF_K, 0), 100 }; 101 #define dhcp_bpf_filter_len sizeof(dhcp_bpf_filter) / sizeof(dhcp_bpf_filter[0]) 102