1 /* SPDX-License-Identifier: BSD-2-Clause */ 2 /* 3 * dhcpcd: BPF arp and bootp filtering 4 * Copyright (c) 2006-2019 Roy Marples <roy@marples.name> 5 * 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 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_HEADER 30 #define BPF_HEADER 31 32 #define BPF_READING (1U << 0) 33 #define BPF_EOF (1U << 1) 34 #define BPF_PARTIALCSUM (1U << 2) 35 #define BPF_BCAST (1U << 3) 36 37 /* 38 * Even though we program the BPF filter should we trust it? 39 * On Linux at least there is a window between opening the socket, 40 * binding the interface and setting the filter where we receive data. 41 * This data is NOT checked OR flushed and IS returned when reading. 42 * We have no way of flushing it other than reading these packets! 43 * But we don't know if they passed the filter or not ..... so we need 44 * to validate each and every packet that comes through ourselves as well. 45 * Even if Linux does fix this sorry state, who is to say other kernels 46 * don't have bugs causing a similar effect? 47 * 48 * As such, let's strive to keep the filters just for pattern matching 49 * to avoid waking dhcpcd up. 50 * 51 * If you want to be notified of any packet failing the BPF filter, 52 * define BPF_DEBUG below. 53 */ 54 //#define BPF_DEBUG 55 56 #include "dhcpcd.h" 57 58 extern const char *bpf_name; 59 size_t bpf_frame_header_len(const struct interface *); 60 int bpf_frame_bcast(const struct interface *, const char *frame); 61 int bpf_open(struct interface *, int (*)(struct interface *, int)); 62 int bpf_close(struct interface *, int); 63 int bpf_attach(int, void *, unsigned int); 64 ssize_t bpf_send(const struct interface *, int, uint16_t, const void *, size_t); 65 ssize_t bpf_read(struct interface *, int, void *, size_t, unsigned int *); 66 int bpf_arp(struct interface *, int); 67 int bpf_bootp(struct interface *, int); 68 #endif 69