1// SPDX-License-Identifier: GPL-2.0
  2/* Copyright (c) 2017-18 David Ahern <dsahern@gmail.com>
  3 *
  4 * This program is free software; you can redistribute it and/or
  5 * modify it under the terms of version 2 of the GNU General Public
  6 * License as published by the Free Software Foundation.
  7 *
  8 * This program is distributed in the hope that it will be useful, but
  9 * WITHOUT ANY WARRANTY; without even the implied warranty of
 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 11 * General Public License for more details.
 12 */
 13
 14#include <linux/bpf.h>
 15#include <linux/if_link.h>
 16#include <linux/limits.h>
 17#include <net/if.h>
 18#include <errno.h>
 19#include <stdio.h>
 20#include <stdlib.h>
 21#include <stdbool.h>
 22#include <string.h>
 23#include <unistd.h>
 24#include <fcntl.h>
 25#include <libgen.h>
 26
 27#include "libbpf.h"
 28#include <bpf/bpf.h>
 29
 30static int do_attach(int idx, int prog_fd, int map_fd, const char *name)
 31{
 32	int err;
 33
 34	err = bpf_set_link_xdp_fd(idx, prog_fd, 0);
 35	if (err < 0) {
 36		printf("ERROR: failed to attach program to %s\n", name);
 37		return err;
 38	}
 39
 40	/* Adding ifindex as a possible egress TX port */
 41	err = bpf_map_update_elem(map_fd, &idx, &idx, 0);
 42	if (err)
 43		printf("ERROR: failed using device %s as TX-port\n", name);
 44
 45	return err;
 46}
 47
 48static int do_detach(int idx, const char *name)
 49{
 50	int err;
 51
 52	err = bpf_set_link_xdp_fd(idx, -1, 0);
 53	if (err < 0)
 54		printf("ERROR: failed to detach program from %s\n", name);
 55
 56	/* TODO: Remember to cleanup map, when adding use of shared map
 57	 *  bpf_map_delete_elem((map_fd, &idx);
 58	 */
 59	return err;
 60}
 61
 62static void usage(const char *prog)
 63{
 64	fprintf(stderr,
 65		"usage: %s [OPTS] interface-list\n"
 66		"\nOPTS:\n"
 67		"    -d    detach program\n"
 68		"    -D    direct table lookups (skip fib rules)\n",
 69		prog);
 70}
 71
 72int main(int argc, char **argv)
 73{
 74	struct bpf_prog_load_attr prog_load_attr = {
 75		.prog_type	= BPF_PROG_TYPE_XDP,
 76	};
 77	const char *prog_name = "xdp_fwd";
 78	struct bpf_program *prog;
 79	int prog_fd, map_fd = -1;
 80	char filename[PATH_MAX];
 81	struct bpf_object *obj;
 82	int opt, i, idx, err;
 83	int attach = 1;
 84	int ret = 0;
 85
 86	while ((opt = getopt(argc, argv, ":dD")) != -1) {
 87		switch (opt) {
 88		case 'd':
 89			attach = 0;
 90			break;
 91		case 'D':
 92			prog_name = "xdp_fwd_direct";
 93			break;
 94		default:
 95			usage(basename(argv[0]));
 96			return 1;
 97		}
 98	}
 99
100	if (optind == argc) {
101		usage(basename(argv[0]));
102		return 1;
103	}
104
105	if (attach) {
106		snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
107		prog_load_attr.file = filename;
108
109		if (access(filename, O_RDONLY) < 0) {
110			printf("error accessing file %s: %s\n",
111				filename, strerror(errno));
112			return 1;
113		}
114
115		err = bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd);
116		if (err) {
117			printf("Does kernel support devmap lookup?\n");
118			/* If not, the error message will be:
119			 *  "cannot pass map_type 14 into func bpf_map_lookup_elem#1"
120			 */
121			return 1;
122		}
123
124		prog = bpf_object__find_program_by_title(obj, prog_name);
125		prog_fd = bpf_program__fd(prog);
126		if (prog_fd < 0) {
127			printf("program not found: %s\n", strerror(prog_fd));
128			return 1;
129		}
130		map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
131							"xdp_tx_ports"));
132		if (map_fd < 0) {
133			printf("map not found: %s\n", strerror(map_fd));
134			return 1;
135		}
136	}
137
138	for (i = optind; i < argc; ++i) {
139		idx = if_nametoindex(argv[i]);
140		if (!idx)
141			idx = strtoul(argv[i], NULL, 0);
142
143		if (!idx) {
144			fprintf(stderr, "Invalid arg\n");
145			return 1;
146		}
147		if (!attach) {
148			err = do_detach(idx, argv[i]);
149			if (err)
150				ret = err;
151		} else {
152			err = do_attach(idx, prog_fd, map_fd, argv[i]);
153			if (err)
154				ret = err;
155		}
156	}
157
158	return ret;
159}