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192 lines
4.5 KiB
192 lines
4.5 KiB
/* 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 <net/if.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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#define MAX_PCKT_SIZE 600 |
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static int ifindex = -1; |
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static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST; |
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static __u32 prog_id; |
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static void int_exit(int sig) |
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{ |
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__u32 curr_prog_id = 0; |
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if (ifindex > -1) { |
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if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) { |
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printf("bpf_get_link_xdp_id failed\n"); |
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exit(1); |
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} |
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if (prog_id == curr_prog_id) |
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bpf_set_link_xdp_fd(ifindex, -1, xdp_flags); |
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else if (!curr_prog_id) |
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printf("couldn't find a prog id on a given iface\n"); |
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else |
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printf("program on interface changed, not removing\n"); |
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} |
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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 <ifname|ifindex> Interface\n"); |
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printf(" -T <stop-after-X-seconds> Default: 0 (forever)\n"); |
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printf(" -P <MAX_PCKT_SIZE> Default: %u\n", MAX_PCKT_SIZE); |
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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(" -F force loading prog\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 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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const char *optstr = "i:T:P:SNFh"; |
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struct bpf_prog_info info = {}; |
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__u32 info_len = sizeof(info); |
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unsigned int kill_after_s = 0; |
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int i, prog_fd, map_fd, opt; |
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struct bpf_object *obj; |
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__u32 max_pckt_size = 0; |
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__u32 key = 0; |
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char filename[256]; |
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int err; |
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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 = if_nametoindex(optarg); |
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if (!ifindex) |
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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 'P': |
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max_pckt_size = 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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/* default, set below */ |
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break; |
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case 'F': |
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xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST; |
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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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if (!(xdp_flags & XDP_FLAGS_SKB_MODE)) |
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xdp_flags |= XDP_FLAGS_DRV_MODE; |
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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 (!ifindex) { |
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fprintf(stderr, "Invalid ifname\n"); |
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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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/* static global var 'max_pcktsz' is accessible from .data section */ |
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if (max_pckt_size) { |
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map_fd = bpf_object__find_map_fd_by_name(obj, "xdp_adju.data"); |
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if (map_fd < 0) { |
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printf("finding a max_pcktsz map in obj file failed\n"); |
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return 1; |
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} |
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bpf_map_update_elem(map_fd, &key, &max_pckt_size, BPF_ANY); |
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} |
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/* fetch icmpcnt map */ |
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map_fd = bpf_object__find_map_fd_by_name(obj, "icmpcnt"); |
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if (map_fd < 0) { |
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printf("finding a icmpcnt map in obj file failed\n"); |
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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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err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len); |
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if (err) { |
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printf("can't get prog info - %s\n", strerror(errno)); |
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return 1; |
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} |
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prog_id = info.id; |
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poll_stats(map_fd, kill_after_s); |
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int_exit(0); |
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return 0; |
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}
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