151 lines
3.4 KiB
C
151 lines
3.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0
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* Copyright (c) 2018 Facebook
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#include <linux/bpf.h>
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#include <linux/if_link.h>
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#include <assert.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/resource.h>
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#include <arpa/inet.h>
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#include <netinet/ether.h>
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#include <unistd.h>
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#include <time.h>
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#include "bpf/bpf.h"
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#include "bpf/libbpf.h"
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#define STATS_INTERVAL_S 2U
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static int ifindex = -1;
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static __u32 xdp_flags;
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static void int_exit(int sig)
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{
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if (ifindex > -1)
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bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
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exit(0);
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}
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/* simple "icmp packet too big sent" counter
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*/
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static void poll_stats(unsigned int map_fd, unsigned int kill_after_s)
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{
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time_t started_at = time(NULL);
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__u64 value = 0;
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int key = 0;
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while (!kill_after_s || time(NULL) - started_at <= kill_after_s) {
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sleep(STATS_INTERVAL_S);
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assert(bpf_map_lookup_elem(map_fd, &key, &value) == 0);
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printf("icmp \"packet too big\" sent: %10llu pkts\n", value);
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}
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}
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static void usage(const char *cmd)
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{
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printf("Start a XDP prog which send ICMP \"packet too big\" \n"
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"messages if ingress packet is bigger then MAX_SIZE bytes\n");
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printf("Usage: %s [...]\n", cmd);
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printf(" -i <ifindex> Interface Index\n");
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printf(" -T <stop-after-X-seconds> Default: 0 (forever)\n");
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printf(" -S use skb-mode\n");
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printf(" -N enforce native mode\n");
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printf(" -h Display this help\n");
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}
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int main(int argc, char **argv)
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{
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struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
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struct bpf_prog_load_attr prog_load_attr = {
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.prog_type = BPF_PROG_TYPE_XDP,
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};
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unsigned char opt_flags[256] = {};
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unsigned int kill_after_s = 0;
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const char *optstr = "i:T:SNh";
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int i, prog_fd, map_fd, opt;
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struct bpf_object *obj;
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struct bpf_map *map;
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char filename[256];
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for (i = 0; i < strlen(optstr); i++)
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if (optstr[i] != 'h' && 'a' <= optstr[i] && optstr[i] <= 'z')
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opt_flags[(unsigned char)optstr[i]] = 1;
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while ((opt = getopt(argc, argv, optstr)) != -1) {
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switch (opt) {
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case 'i':
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ifindex = atoi(optarg);
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break;
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case 'T':
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kill_after_s = atoi(optarg);
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break;
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case 'S':
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xdp_flags |= XDP_FLAGS_SKB_MODE;
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break;
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case 'N':
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xdp_flags |= XDP_FLAGS_DRV_MODE;
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break;
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default:
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usage(argv[0]);
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return 1;
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}
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opt_flags[opt] = 0;
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}
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for (i = 0; i < strlen(optstr); i++) {
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if (opt_flags[(unsigned int)optstr[i]]) {
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fprintf(stderr, "Missing argument -%c\n", optstr[i]);
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usage(argv[0]);
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return 1;
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}
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}
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if (setrlimit(RLIMIT_MEMLOCK, &r)) {
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perror("setrlimit(RLIMIT_MEMLOCK, RLIM_INFINITY)");
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return 1;
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}
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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prog_load_attr.file = filename;
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if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
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return 1;
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map = bpf_map__next(NULL, obj);
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if (!map) {
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printf("finding a map in obj file failed\n");
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return 1;
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}
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map_fd = bpf_map__fd(map);
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if (!prog_fd) {
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printf("load_bpf_file: %s\n", strerror(errno));
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return 1;
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}
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signal(SIGINT, int_exit);
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signal(SIGTERM, int_exit);
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if (bpf_set_link_xdp_fd(ifindex, prog_fd, xdp_flags) < 0) {
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printf("link set xdp fd failed\n");
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return 1;
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}
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poll_stats(map_fd, kill_after_s);
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bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
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return 0;
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}
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