1 /* SPDX-License-Identifier: BSD-2-Clause */ 2 /* 3 * dhcpcd: BPF arp and bootp filtering 4 * Copyright (c) 2006-2023 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_EOF 0x01U 33 #define BPF_PARTIALCSUM 0x02U 34 #define BPF_BCAST 0x04U 35 36 /* 37 * Even though we program the BPF filter should we trust it? 38 * On Linux at least there is a window between opening the socket, 39 * binding the interface and setting the filter where we receive data. 40 * This data is NOT checked OR flushed and IS returned when reading. 41 * We have no way of flushing it other than reading these packets! 42 * But we don't know if they passed the filter or not ..... so we need 43 * to validate each and every packet that comes through ourselves as well. 44 * Even if Linux does fix this sorry state, who is to say other kernels 45 * don't have bugs causing a similar effect? 46 * 47 * As such, let's strive to keep the filters just for pattern matching 48 * to avoid waking dhcpcd up. 49 * 50 * If you want to be notified of any packet failing the BPF filter, 51 * define BPF_DEBUG below. 52 */ 53 //#define BPF_DEBUG 54 55 #include "dhcpcd.h" 56 57 struct bpf { 58 const struct interface *bpf_ifp; 59 int bpf_fd; 60 unsigned int bpf_flags; 61 void *bpf_buffer; 62 size_t bpf_size; 63 size_t bpf_len; 64 size_t bpf_pos; 65 }; 66 67 extern const char *bpf_name; 68 size_t bpf_frame_header_len(const struct interface *); 69 void *bpf_frame_header_src(const struct interface *, void *, size_t *); 70 void *bpf_frame_header_dst(const struct interface *, void *, size_t *); 71 int bpf_frame_bcast(const struct interface *, const void *); 72 struct bpf * bpf_open(const struct interface *, 73 int (*)(const struct bpf *, const struct in_addr *), 74 const struct in_addr *); 75 void bpf_close(struct bpf *); 76 int bpf_attach(int, void *, unsigned int); 77 ssize_t bpf_send(const struct bpf *, uint16_t, const void *, size_t); 78 ssize_t bpf_read(struct bpf *, void *, size_t); 79 int bpf_arp(const struct bpf *, const struct in_addr *); 80 int bpf_bootp(const struct bpf *, const struct in_addr *); 81 #endif 82