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 <sys/resource.h> 17 #include <arpa/inet.h> 18 #include <netinet/ether.h> 19 #include <unistd.h> 20 #include <time.h> 21 #include "bpf/bpf.h" 22 #include "bpf/libbpf.h" 23 24 #define STATS_INTERVAL_S 2U 25 26 static int ifindex = -1; 27 static __u32 xdp_flags; 28 29 static void int_exit(int sig) 30 { 31 if (ifindex > -1) 32 bpf_set_link_xdp_fd(ifindex, -1, xdp_flags); 33 exit(0); 34 } 35 36 /* simple "icmp packet too big sent" counter 37 */ 38 static void poll_stats(unsigned int map_fd, unsigned int kill_after_s) 39 { 40 time_t started_at = time(NULL); 41 __u64 value = 0; 42 int key = 0; 43 44 45 while (!kill_after_s || time(NULL) - started_at <= kill_after_s) { 46 sleep(STATS_INTERVAL_S); 47 48 assert(bpf_map_lookup_elem(map_fd, &key, &value) == 0); 49 50 printf("icmp \"packet too big\" sent: %10llu pkts\n", value); 51 } 52 } 53 54 static void usage(const char *cmd) 55 { 56 printf("Start a XDP prog which send ICMP \"packet too big\" \n" 57 "messages if ingress packet is bigger then MAX_SIZE bytes\n"); 58 printf("Usage: %s [...]\n", cmd); 59 printf(" -i <ifindex> Interface Index\n"); 60 printf(" -T <stop-after-X-seconds> Default: 0 (forever)\n"); 61 printf(" -S use skb-mode\n"); 62 printf(" -N enforce native mode\n"); 63 printf(" -h Display this help\n"); 64 } 65 66 int main(int argc, char **argv) 67 { 68 struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY}; 69 struct bpf_prog_load_attr prog_load_attr = { 70 .prog_type = BPF_PROG_TYPE_XDP, 71 }; 72 unsigned char opt_flags[256] = {}; 73 unsigned int kill_after_s = 0; 74 const char *optstr = "i:T:SNh"; 75 int i, prog_fd, map_fd, opt; 76 struct bpf_object *obj; 77 struct bpf_map *map; 78 char filename[256]; 79 80 for (i = 0; i < strlen(optstr); i++) 81 if (optstr[i] != 'h' && 'a' <= optstr[i] && optstr[i] <= 'z') 82 opt_flags[(unsigned char)optstr[i]] = 1; 83 84 while ((opt = getopt(argc, argv, optstr)) != -1) { 85 86 switch (opt) { 87 case 'i': 88 ifindex = atoi(optarg); 89 break; 90 case 'T': 91 kill_after_s = atoi(optarg); 92 break; 93 case 'S': 94 xdp_flags |= XDP_FLAGS_SKB_MODE; 95 break; 96 case 'N': 97 xdp_flags |= XDP_FLAGS_DRV_MODE; 98 break; 99 default: 100 usage(argv[0]); 101 return 1; 102 } 103 opt_flags[opt] = 0; 104 } 105 106 for (i = 0; i < strlen(optstr); i++) { 107 if (opt_flags[(unsigned int)optstr[i]]) { 108 fprintf(stderr, "Missing argument -%c\n", optstr[i]); 109 usage(argv[0]); 110 return 1; 111 } 112 } 113 114 if (setrlimit(RLIMIT_MEMLOCK, &r)) { 115 perror("setrlimit(RLIMIT_MEMLOCK, RLIM_INFINITY)"); 116 return 1; 117 } 118 119 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); 120 prog_load_attr.file = filename; 121 122 if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd)) 123 return 1; 124 125 map = bpf_map__next(NULL, obj); 126 if (!map) { 127 printf("finding a map in obj file failed\n"); 128 return 1; 129 } 130 map_fd = bpf_map__fd(map); 131 132 if (!prog_fd) { 133 printf("load_bpf_file: %s\n", strerror(errno)); 134 return 1; 135 } 136 137 signal(SIGINT, int_exit); 138 signal(SIGTERM, int_exit); 139 140 if (bpf_set_link_xdp_fd(ifindex, prog_fd, xdp_flags) < 0) { 141 printf("link set xdp fd failed\n"); 142 return 1; 143 } 144 145 poll_stats(map_fd, kill_after_s); 146 147 bpf_set_link_xdp_fd(ifindex, -1, xdp_flags); 148 149 return 0; 150 } 151