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_xdp_attach(idx, prog_fd, xdp_flags, NULL);
 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 ifindex, const char *ifname, const char *app_name)
 51{
 52	LIBBPF_OPTS(bpf_xdp_attach_opts, opts);
 53	struct bpf_prog_info prog_info = {};
 54	char prog_name[BPF_OBJ_NAME_LEN];
 55	__u32 info_len, curr_prog_id;
 56	int prog_fd;
 57	int err = 1;
 58
 59	if (bpf_xdp_query_id(ifindex, xdp_flags, &curr_prog_id)) {
 60		printf("ERROR: bpf_xdp_query_id failed (%s)\n",
 61		       strerror(errno));
 62		return err;
 63	}
 64
 65	if (!curr_prog_id) {
 66		printf("ERROR: flags(0x%x) xdp prog is not attached to %s\n",
 67		       xdp_flags, ifname);
 68		return err;
 69	}
 70
 71	info_len = sizeof(prog_info);
 72	prog_fd = bpf_prog_get_fd_by_id(curr_prog_id);
 73	if (prog_fd < 0) {
 74		printf("ERROR: bpf_prog_get_fd_by_id failed (%s)\n",
 75		       strerror(errno));
 76		return prog_fd;
 77	}
 78
 79	err = bpf_prog_get_info_by_fd(prog_fd, &prog_info, &info_len);
 80	if (err) {
 81		printf("ERROR: bpf_prog_get_info_by_fd failed (%s)\n",
 82		       strerror(errno));
 83		goto close_out;
 84	}
 85	snprintf(prog_name, sizeof(prog_name), "%s_prog", app_name);
 86	prog_name[BPF_OBJ_NAME_LEN - 1] = '\0';
 87
 88	if (strcmp(prog_info.name, prog_name)) {
 89		printf("ERROR: %s isn't attached to %s\n", app_name, ifname);
 90		err = 1;
 91		goto close_out;
 92	}
 93
 94	opts.old_prog_fd = prog_fd;
 95	err = bpf_xdp_detach(ifindex, xdp_flags, &opts);
 96	if (err < 0)
 97		printf("ERROR: failed to detach program from %s (%s)\n",
 98		       ifname, strerror(errno));
 99	/* TODO: Remember to cleanup map, when adding use of shared map
100	 *  bpf_map_delete_elem((map_fd, &idx);
101	 */
102close_out:
103	close(prog_fd);
104	return err;
105}
106
107static void usage(const char *prog)
108{
109	fprintf(stderr,
110		"usage: %s [OPTS] interface-list\n"
111		"\nOPTS:\n"
112		"    -d    detach program\n"
113		"    -S    use skb-mode\n"
114		"    -F    force loading prog\n"
115		"    -D    direct table lookups (skip fib rules)\n",
116		prog);
117}
118
119int main(int argc, char **argv)
120{
121	const char *prog_name = "xdp_fwd";
122	struct bpf_program *prog = NULL;
123	struct bpf_program *pos;
124	const char *sec_name;
125	int prog_fd = -1, map_fd = -1;
126	char filename[PATH_MAX];
127	struct bpf_object *obj;
128	int opt, i, idx, err;
129	int attach = 1;
130	int ret = 0;
131
132	while ((opt = getopt(argc, argv, ":dDSF")) != -1) {
133		switch (opt) {
134		case 'd':
135			attach = 0;
136			break;
137		case 'S':
138			xdp_flags |= XDP_FLAGS_SKB_MODE;
139			break;
140		case 'F':
141			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
142			break;
143		case 'D':
144			prog_name = "xdp_fwd_direct";
145			break;
146		default:
147			usage(basename(argv[0]));
148			return 1;
149		}
150	}
151
152	if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
153		xdp_flags |= XDP_FLAGS_DRV_MODE;
154
155	if (optind == argc) {
156		usage(basename(argv[0]));
157		return 1;
158	}
159
160	if (attach) {
161		snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
162
163		if (access(filename, O_RDONLY) < 0) {
164			printf("error accessing file %s: %s\n",
165				filename, strerror(errno));
166			return 1;
167		}
168
169		obj = bpf_object__open_file(filename, NULL);
170		if (libbpf_get_error(obj))
171			return 1;
172
173		prog = bpf_object__next_program(obj, NULL);
174		bpf_program__set_type(prog, BPF_PROG_TYPE_XDP);
175
176		err = bpf_object__load(obj);
177		if (err) {
178			printf("Does kernel support devmap lookup?\n");
179			/* If not, the error message will be:
180			 *  "cannot pass map_type 14 into func bpf_map_lookup_elem#1"
181			 */
182			return 1;
183		}
184
185		bpf_object__for_each_program(pos, obj) {
186			sec_name = bpf_program__section_name(pos);
187			if (sec_name && !strcmp(sec_name, prog_name)) {
188				prog = pos;
189				break;
190			}
191		}
192		prog_fd = bpf_program__fd(prog);
193		if (prog_fd < 0) {
194			printf("program not found: %s\n", strerror(prog_fd));
195			return 1;
196		}
197		map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
198							"xdp_tx_ports"));
199		if (map_fd < 0) {
200			printf("map not found: %s\n", strerror(map_fd));
201			return 1;
202		}
203	}
204
205	for (i = optind; i < argc; ++i) {
206		idx = if_nametoindex(argv[i]);
207		if (!idx)
208			idx = strtoul(argv[i], NULL, 0);
209
210		if (!idx) {
211			fprintf(stderr, "Invalid arg\n");
212			return 1;
213		}
214		if (!attach) {
215			err = do_detach(idx, argv[i], prog_name);
216			if (err)
217				ret = err;
218		} else {
219			err = do_attach(idx, prog_fd, map_fd, argv[i]);
220			if (err)
221				ret = err;
222		}
223	}
224
225	return ret;
226}