1/* SPDX-License-Identifier: GPL-2.0
  2 * Copyright (c) 2018 Facebook
  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#include <linux/bpf.h>
  9#include <linux/if_link.h>
 10#include <assert.h>
 11#include <errno.h>
 12#include <signal.h>
 13#include <stdio.h>
 14#include <stdlib.h>
 15#include <string.h>
 16#include <net/if.h>
 17#include <sys/resource.h>
 18#include <arpa/inet.h>
 19#include <netinet/ether.h>
 20#include <unistd.h>
 21#include <time.h>
 22#include "bpf.h"
 23#include "libbpf.h"
 24
 25#define STATS_INTERVAL_S 2U
 26
 27static int ifindex = -1;
 28static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 29static __u32 prog_id;
 30
 31static void int_exit(int sig)
 32{
 33	__u32 curr_prog_id = 0;
 34
 35	if (ifindex > -1) {
 36		if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
 37			printf("bpf_get_link_xdp_id failed\n");
 38			exit(1);
 39		}
 40		if (prog_id == curr_prog_id)
 41			bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
 42		else if (!curr_prog_id)
 43			printf("couldn't find a prog id on a given iface\n");
 44		else
 45			printf("program on interface changed, not removing\n");
 46	}
 47	exit(0);
 48}
 49
 50/* simple "icmp packet too big sent" counter
 51 */
 52static void poll_stats(unsigned int map_fd, unsigned int kill_after_s)
 53{
 54	time_t started_at = time(NULL);
 55	__u64 value = 0;
 56	int key = 0;
 57
 58
 59	while (!kill_after_s || time(NULL) - started_at <= kill_after_s) {
 60		sleep(STATS_INTERVAL_S);
 61
 62		assert(bpf_map_lookup_elem(map_fd, &key, &value) == 0);
 63
 64		printf("icmp \"packet too big\" sent: %10llu pkts\n", value);
 65	}
 66}
 67
 68static void usage(const char *cmd)
 69{
 70	printf("Start a XDP prog which send ICMP \"packet too big\" \n"
 71		"messages if ingress packet is bigger then MAX_SIZE bytes\n");
 72	printf("Usage: %s [...]\n", cmd);
 73	printf("    -i <ifname|ifindex> Interface\n");
 74	printf("    -T <stop-after-X-seconds> Default: 0 (forever)\n");
 75	printf("    -S use skb-mode\n");
 76	printf("    -N enforce native mode\n");
 77	printf("    -F force loading prog\n");
 78	printf("    -h Display this help\n");
 79}
 80
 81int main(int argc, char **argv)
 82{
 83	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
 84	struct bpf_prog_load_attr prog_load_attr = {
 85		.prog_type	= BPF_PROG_TYPE_XDP,
 86	};
 87	unsigned char opt_flags[256] = {};
 88	const char *optstr = "i:T:SNFh";
 89	struct bpf_prog_info info = {};
 90	__u32 info_len = sizeof(info);
 91	unsigned int kill_after_s = 0;
 92	int i, prog_fd, map_fd, opt;
 93	struct bpf_object *obj;
 94	struct bpf_map *map;
 95	char filename[256];
 96	int err;
 97
 98	for (i = 0; i < strlen(optstr); i++)
 99		if (optstr[i] != 'h' && 'a' <= optstr[i] && optstr[i] <= 'z')
100			opt_flags[(unsigned char)optstr[i]] = 1;
101
102	while ((opt = getopt(argc, argv, optstr)) != -1) {
103
104		switch (opt) {
105		case 'i':
106			ifindex = if_nametoindex(optarg);
107			if (!ifindex)
108				ifindex = atoi(optarg);
109			break;
110		case 'T':
111			kill_after_s = atoi(optarg);
112			break;
113		case 'S':
114			xdp_flags |= XDP_FLAGS_SKB_MODE;
115			break;
116		case 'N':
117			xdp_flags |= XDP_FLAGS_DRV_MODE;
118			break;
119		case 'F':
120			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
121			break;
122		default:
123			usage(argv[0]);
124			return 1;
125		}
126		opt_flags[opt] = 0;
127	}
128
129	for (i = 0; i < strlen(optstr); i++) {
130		if (opt_flags[(unsigned int)optstr[i]]) {
131			fprintf(stderr, "Missing argument -%c\n", optstr[i]);
132			usage(argv[0]);
133			return 1;
134		}
135	}
136
137	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
138		perror("setrlimit(RLIMIT_MEMLOCK, RLIM_INFINITY)");
139		return 1;
140	}
141
142	if (!ifindex) {
143		fprintf(stderr, "Invalid ifname\n");
144		return 1;
145	}
146
147	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
148	prog_load_attr.file = filename;
149
150	if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
151		return 1;
152
153	map = bpf_map__next(NULL, obj);
154	if (!map) {
155		printf("finding a map in obj file failed\n");
156		return 1;
157	}
158	map_fd = bpf_map__fd(map);
159
160	if (!prog_fd) {
161		printf("load_bpf_file: %s\n", strerror(errno));
162		return 1;
163	}
164
165	signal(SIGINT, int_exit);
166	signal(SIGTERM, int_exit);
167
168	if (bpf_set_link_xdp_fd(ifindex, prog_fd, xdp_flags) < 0) {
169		printf("link set xdp fd failed\n");
170		return 1;
171	}
172
173	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
174	if (err) {
175		printf("can't get prog info - %s\n", strerror(errno));
176		return 1;
177	}
178	prog_id = info.id;
179
180	poll_stats(map_fd, kill_after_s);
181	int_exit(0);
182
183	return 0;
184}