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 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 #define arp_bpf_filter_len sizeof(arp_bpf_filter) / sizeof(arp_bpf_filter[0]) 51 52 53 /* dhcp_bpf_filter taken from bpf.c in dhcp-3.1.0 54 * 55 * Copyright (c) 2004,2007 by Internet Systems Consortium, Inc. ("ISC") 56 * Copyright (c) 1996-2003 by Internet Software Consortium 57 * 58 * Permission to use, copy, modify, and distribute this software for any 59 * purpose with or without fee is hereby granted, provided that the above 60 * copyright notice and this permission notice appear in all copies. 61 * 62 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 63 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 64 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 65 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 66 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 67 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 68 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 69 * 70 * Internet Systems Consortium, Inc. 71 * 950 Charter Street 72 * Redwood City, CA 94063 73 * <info (at) isc.org> 74 * http://www.isc.org/ 75 */ 76 77 static const struct bpf_insn dhcp_bpf_filter [] = { 78 #ifndef BPF_SKIPTYPE 79 /* Make sure this is an IP packet... */ 80 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12), 81 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 8), 82 #endif 83 /* Make sure it's a UDP packet... */ 84 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 23 + BPF_ETHCOOK), 85 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 6), 86 /* Make sure this isn't a fragment... */ 87 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK), 88 BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 4, 0), 89 /* Get the IP header length... */ 90 BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, 14 + BPF_ETHCOOK), 91 /* Make sure it's to the right port... */ 92 BPF_STMT(BPF_LD + BPF_H + BPF_IND, 16 + BPF_ETHCOOK), 93 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_CLIENT_PORT, 0, 1), 94 /* If we passed all the tests, ask for the whole packet. */ 95 BPF_STMT(BPF_RET + BPF_K, BPF_WHOLEPACKET), 96 /* Otherwise, drop it. */ 97 BPF_STMT(BPF_RET + BPF_K, 0), 98 }; 99 #define dhcp_bpf_filter_len sizeof(dhcp_bpf_filter) / sizeof(dhcp_bpf_filter[0]) 100
