1 /* 2 * dhcpcd - DHCP client daemon 3 * Copyright (c) 2006-2008 Roy Marples <roy (at) marples.name> 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 AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #ifndef BPF_ETHCOOK 28 # define BPF_ETHCOOK 0 29 #endif 30 #ifndef BPF_WHOLEPACKET 31 # define BPF_WHOLEPACKET ~0U 32 #endif 33 static const struct bpf_insn const arp_bpf_filter [] = { 34 #ifndef BPF_SKIPTYPE 35 /* Make sure this is an ARP packet... */ 36 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12), 37 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_ARP, 0, 3), 38 #endif 39 /* Make sure this is an ARP REQUEST... */ 40 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK), 41 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 2, 0), 42 /* or ARP REPLY... */ 43 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK), 44 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 0, 1), 45 /* If we passed all the tests, ask for the whole packet. */ 46 BPF_STMT(BPF_RET + BPF_K, BPF_WHOLEPACKET), 47 /* Otherwise, drop it. */ 48 BPF_STMT(BPF_RET + BPF_K, 0), 49 }; 50 static const size_t arp_bpf_filter_len = 51 sizeof(arp_bpf_filter) / sizeof(arp_bpf_filter[0]); 52 53 54 /* dhcp_bpf_filter taken from bpf.c in dhcp-3.1.0 55 * 56 * Copyright (c) 2004,2007 by Internet Systems Consortium, Inc. ("ISC") 57 * Copyright (c) 1996-2003 by Internet Software Consortium 58 * 59 * Permission to use, copy, modify, and distribute this software for any 60 * purpose with or without fee is hereby granted, provided that the above 61 * copyright notice and this permission notice appear in all copies. 62 * 63 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 64 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 65 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 66 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 67 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 68 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 69 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 70 * 71 * Internet Systems Consortium, Inc. 72 * 950 Charter Street 73 * Redwood City, CA 94063 74 * <info (at) isc.org> 75 * http://www.isc.org/ 76 */ 77 78 static const struct bpf_insn const dhcp_bpf_filter [] = { 79 #ifndef BPF_SKIPTYPE 80 /* Make sure this is an IP packet... */ 81 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12), 82 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 8), 83 #endif 84 /* Make sure it's a UDP packet... */ 85 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 23 + BPF_ETHCOOK), 86 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 6), 87 /* Make sure this isn't a fragment... */ 88 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK), 89 BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 4, 0), 90 /* Get the IP header length... */ 91 BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, 14 + BPF_ETHCOOK), 92 /* Make sure it's to the right port... */ 93 BPF_STMT(BPF_LD + BPF_H + BPF_IND, 16 + BPF_ETHCOOK), 94 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_CLIENT_PORT, 0, 1), 95 /* If we passed all the tests, ask for the whole packet. */ 96 BPF_STMT(BPF_RET + BPF_K, BPF_WHOLEPACKET), 97 /* Otherwise, drop it. */ 98 BPF_STMT(BPF_RET + BPF_K, 0), 99 }; 100 static const size_t dhcp_bpf_filter_len = 101 sizeof(dhcp_bpf_filter) / sizeof(dhcp_bpf_filter[0]); 102
