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 27 static int ifindex = -1; 28 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST; 29 static __u32 prog_id; 30 31 static 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 */ 52 static 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 68 static 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 81 int 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 } 185