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 <bpf/libbpf.h>
 28#include <bpf/bpf.h>
 29
 30static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 31
 32static int do_attach(int idx, int prog_fd, int map_fd, const char *name)
 33{
 34	int err;
 35
 36	err = bpf_set_link_xdp_fd(idx, prog_fd, xdp_flags);
 37	if (err < 0) {
 38		printf("ERROR: failed to attach program to %s\n", name);
 39		return err;
 40	}
 41
 42	/* Adding ifindex as a possible egress TX port */
 43	err = bpf_map_update_elem(map_fd, &idx, &idx, 0);
 44	if (err)
 45		printf("ERROR: failed using device %s as TX-port\n", name);
 46
 47	return err;
 48}
 49
 50static int do_detach(int idx, const char *name)
 51{
 52	int err;
 53
 54	err = bpf_set_link_xdp_fd(idx, -1, xdp_flags);
 55	if (err < 0)
 56		printf("ERROR: failed to detach program from %s\n", name);
 57
 58	/* TODO: Remember to cleanup map, when adding use of shared map
 59	 *  bpf_map_delete_elem((map_fd, &idx);
 60	 */
 61	return err;
 62}
 63
 64static void usage(const char *prog)
 65{
 66	fprintf(stderr,
 67		"usage: %s [OPTS] interface-list\n"
 68		"\nOPTS:\n"
 69		"    -d    detach program\n"
 70		"    -S    use skb-mode\n"
 71		"    -F    force loading prog\n"
 72		"    -D    direct table lookups (skip fib rules)\n",
 73		prog);
 74}
 75
 76int main(int argc, char **argv)
 77{
 78	struct bpf_prog_load_attr prog_load_attr = {
 79		.prog_type	= BPF_PROG_TYPE_XDP,
 80	};
 81	const char *prog_name = "xdp_fwd";
 82	struct bpf_program *prog;
 83	int prog_fd, map_fd = -1;
 84	char filename[PATH_MAX];
 85	struct bpf_object *obj;
 86	int opt, i, idx, err;
 87	int attach = 1;
 88	int ret = 0;
 89
 90	while ((opt = getopt(argc, argv, ":dDSF")) != -1) {
 91		switch (opt) {
 92		case 'd':
 93			attach = 0;
 94			break;
 95		case 'S':
 96			xdp_flags |= XDP_FLAGS_SKB_MODE;
 97			break;
 98		case 'F':
 99			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
100			break;
101		case 'D':
102			prog_name = "xdp_fwd_direct";
103			break;
104		default:
105			usage(basename(argv[0]));
106			return 1;
107		}
108	}
109
110	if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
111		xdp_flags |= XDP_FLAGS_DRV_MODE;
112
113	if (optind == argc) {
114		usage(basename(argv[0]));
115		return 1;
116	}
117
118	if (attach) {
119		snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
120		prog_load_attr.file = filename;
121
122		if (access(filename, O_RDONLY) < 0) {
123			printf("error accessing file %s: %s\n",
124				filename, strerror(errno));
125			return 1;
126		}
127
128		err = bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd);
129		if (err) {
130			printf("Does kernel support devmap lookup?\n");
131			/* If not, the error message will be:
132			 *  "cannot pass map_type 14 into func bpf_map_lookup_elem#1"
133			 */
134			return 1;
135		}
136
137		prog = bpf_object__find_program_by_title(obj, prog_name);
138		prog_fd = bpf_program__fd(prog);
139		if (prog_fd < 0) {
140			printf("program not found: %s\n", strerror(prog_fd));
141			return 1;
142		}
143		map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
144							"xdp_tx_ports"));
145		if (map_fd < 0) {
146			printf("map not found: %s\n", strerror(map_fd));
147			return 1;
148		}
149	}
150
151	for (i = optind; i < argc; ++i) {
152		idx = if_nametoindex(argv[i]);
153		if (!idx)
154			idx = strtoul(argv[i], NULL, 0);
155
156		if (!idx) {
157			fprintf(stderr, "Invalid arg\n");
158			return 1;
159		}
160		if (!attach) {
161			err = do_detach(idx, argv[i]);
162			if (err)
163				ret = err;
164		} else {
165			err = do_attach(idx, prog_fd, map_fd, argv[i]);
166			if (err)
167				ret = err;
168		}
169	}
170
171	return ret;
172}