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		"    -D    direct table lookups (skip fib rules)\n",
 71		prog);
 72}
 73
 74int main(int argc, char **argv)
 75{
 76	struct bpf_prog_load_attr prog_load_attr = {
 77		.prog_type	= BPF_PROG_TYPE_XDP,
 78	};
 79	const char *prog_name = "xdp_fwd";
 80	struct bpf_program *prog;
 81	int prog_fd, map_fd = -1;
 82	char filename[PATH_MAX];
 83	struct bpf_object *obj;
 84	int opt, i, idx, err;
 85	int attach = 1;
 86	int ret = 0;
 87
 88	while ((opt = getopt(argc, argv, ":dDSF")) != -1) {
 89		switch (opt) {
 90		case 'd':
 91			attach = 0;
 92			break;
 93		case 'S':
 94			xdp_flags |= XDP_FLAGS_SKB_MODE;
 95			break;
 96		case 'F':
 97			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
 98			break;
 99		case 'D':
100			prog_name = "xdp_fwd_direct";
101			break;
102		default:
103			usage(basename(argv[0]));
104			return 1;
105		}
106	}
107
108	if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
109		xdp_flags |= XDP_FLAGS_DRV_MODE;
110
111	if (optind == argc) {
112		usage(basename(argv[0]));
113		return 1;
114	}
115
116	if (attach) {
117		snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
118		prog_load_attr.file = filename;
119
120		if (access(filename, O_RDONLY) < 0) {
121			printf("error accessing file %s: %s\n",
122				filename, strerror(errno));
123			return 1;
124		}
125
126		err = bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd);
127		if (err) {
128			printf("Does kernel support devmap lookup?\n");
129			/* If not, the error message will be:
130			 *  "cannot pass map_type 14 into func bpf_map_lookup_elem#1"
131			 */
132			return 1;
133		}
134
135		prog = bpf_object__find_program_by_title(obj, prog_name);
136		prog_fd = bpf_program__fd(prog);
137		if (prog_fd < 0) {
138			printf("program not found: %s\n", strerror(prog_fd));
139			return 1;
140		}
141		map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
142							"xdp_tx_ports"));
143		if (map_fd < 0) {
144			printf("map not found: %s\n", strerror(map_fd));
145			return 1;
146		}
147	}
148
149	for (i = optind; i < argc; ++i) {
150		idx = if_nametoindex(argv[i]);
151		if (!idx)
152			idx = strtoul(argv[i], NULL, 0);
153
154		if (!idx) {
155			fprintf(stderr, "Invalid arg\n");
156			return 1;
157		}
158		if (!attach) {
159			err = do_detach(idx, argv[i]);
160			if (err)
161				ret = err;
162		} else {
163			err = do_attach(idx, prog_fd, map_fd, argv[i]);
164			if (err)
165				ret = err;
166		}
167	}
168
169	return ret;
170}