/* SPDX-License-Identifier: BSD-2-Clause */ /* * dhcpcd: BPF arp and bootp filtering * Copyright (c) 2006-2023 Roy Marples <roy@marples.name> * All rights reserved * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef BPF_HEADER #define BPF_HEADER #define BPF_EOF 0x01U #define BPF_PARTIALCSUM 0x02U #define BPF_BCAST 0x04U /* * Even though we program the BPF filter should we trust it? * On Linux at least there is a window between opening the socket, * binding the interface and setting the filter where we receive data. * This data is NOT checked OR flushed and IS returned when reading. * We have no way of flushing it other than reading these packets! * But we don't know if they passed the filter or not ..... so we need * to validate each and every packet that comes through ourselves as well. * Even if Linux does fix this sorry state, who is to say other kernels * don't have bugs causing a similar effect? * * As such, let's strive to keep the filters just for pattern matching * to avoid waking dhcpcd up. * * If you want to be notified of any packet failing the BPF filter, * define BPF_DEBUG below. */ //#define BPF_DEBUG #include "dhcpcd.h" struct bpf { const struct interface *bpf_ifp; int bpf_fd; unsigned int bpf_flags; void *bpf_buffer; size_t bpf_size; size_t bpf_len; size_t bpf_pos; }; extern const char *bpf_name; size_t bpf_frame_header_len(const struct interface *); void *bpf_frame_header_src(const struct interface *, void *, size_t *); void *bpf_frame_header_dst(const struct interface *, void *, size_t *); int bpf_frame_bcast(const struct interface *, const void *); struct bpf * bpf_open(const struct interface *, int (*)(const struct bpf *, const struct in_addr *), const struct in_addr *); void bpf_close(struct bpf *); int bpf_attach(int, void *, unsigned int); ssize_t bpf_send(const struct bpf *, uint16_t, const void *, size_t); ssize_t bpf_read(struct bpf *, void *, size_t); int bpf_arp(const struct bpf *, const struct in_addr *); int bpf_bootp(const struct bpf *, const struct in_addr *); #endif |