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
57struct 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
67extern const char *bpf_name;
68size_t bpf_frame_header_len(const struct interface *);
69void *bpf_frame_header_src(const struct interface *, void *, size_t *);
70void *bpf_frame_header_dst(const struct interface *, void *, size_t *);
71int bpf_frame_bcast(const struct interface *, const void *);
72struct bpf * bpf_open(const struct interface *,
73    int (*)(const struct bpf *, const struct in_addr *),
74    const struct in_addr *);
75void bpf_close(struct bpf *);
76int bpf_attach(int, void *, unsigned int);
77ssize_t bpf_send(const struct bpf *, uint16_t, const void *, size_t);
78ssize_t bpf_read(struct bpf *, void *, size_t);
79int bpf_arp(const struct bpf *, const struct in_addr *);
80int bpf_bootp(const struct bpf *, const struct in_addr *);
81#endif
82