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1/* eBPF example program:2 * - creates arraymap in kernel with key 4 bytes and value 8 bytes3 *4 * - loads eBPF program:5 * r0 = skb->data[ETH_HLEN + offsetof(struct iphdr, protocol)];6 * *(u32*)(fp - 4) = r0;7 * // assuming packet is IPv4, lookup ip->proto in a map8 * value = bpf_map_lookup_elem(map_fd, fp - 4);9 * if (value)10 * (*(u64*)value) += 1;11 *12 * - attaches this program to loopback interface "lo" raw socket13 *14 * - every second user space reads map[tcp], map[udp], map[icmp] to see15 * how many packets of given protocol were seen on "lo"16 */17#include <stdio.h>18#include <unistd.h>19#include <assert.h>20#include <linux/bpf.h>21#include <string.h>22#include <stdlib.h>23#include <errno.h>24#include <sys/socket.h>25#include <arpa/inet.h>26#include <linux/if_ether.h>27#include <linux/ip.h>28#include <stddef.h>29#include <bpf/bpf.h>30#include "bpf_insn.h"31#include "sock_example.h"32#include "bpf_util.h"33 34char bpf_log_buf[BPF_LOG_BUF_SIZE];35 36static int test_sock(void)37{38 int sock = -1, map_fd, prog_fd, i, key;39 long long value = 0, tcp_cnt, udp_cnt, icmp_cnt;40 41 map_fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, NULL, sizeof(key), sizeof(value),42 256, NULL);43 if (map_fd < 0) {44 printf("failed to create map '%s'\n", strerror(errno));45 goto cleanup;46 }47 48 struct bpf_insn prog[] = {49 BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),50 BPF_LD_ABS(BPF_B, ETH_HLEN + offsetof(struct iphdr, protocol) /* R0 = ip->proto */),51 BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */52 BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),53 BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = fp - 4 */54 BPF_LD_MAP_FD(BPF_REG_1, map_fd),55 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),56 BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),57 BPF_MOV64_IMM(BPF_REG_1, 1), /* r1 = 1 */58 BPF_ATOMIC_OP(BPF_DW, BPF_ADD, BPF_REG_0, BPF_REG_1, 0),59 BPF_MOV64_IMM(BPF_REG_0, 0), /* r0 = 0 */60 BPF_EXIT_INSN(),61 };62 size_t insns_cnt = ARRAY_SIZE(prog);63 LIBBPF_OPTS(bpf_prog_load_opts, opts,64 .log_buf = bpf_log_buf,65 .log_size = BPF_LOG_BUF_SIZE,66 );67 68 prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",69 prog, insns_cnt, &opts);70 if (prog_fd < 0) {71 printf("failed to load prog '%s'\n", strerror(errno));72 goto cleanup;73 }74 75 sock = open_raw_sock("lo");76 77 if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd,78 sizeof(prog_fd)) < 0) {79 printf("setsockopt %s\n", strerror(errno));80 goto cleanup;81 }82 83 for (i = 0; i < 10; i++) {84 key = IPPROTO_TCP;85 assert(bpf_map_lookup_elem(map_fd, &key, &tcp_cnt) == 0);86 87 key = IPPROTO_UDP;88 assert(bpf_map_lookup_elem(map_fd, &key, &udp_cnt) == 0);89 90 key = IPPROTO_ICMP;91 assert(bpf_map_lookup_elem(map_fd, &key, &icmp_cnt) == 0);92 93 printf("TCP %lld UDP %lld ICMP %lld packets\n",94 tcp_cnt, udp_cnt, icmp_cnt);95 sleep(1);96 }97 98cleanup:99 /* maps, programs, raw sockets will auto cleanup on process exit */100 return 0;101}102 103int main(void)104{105 FILE *f;106 107 f = popen("ping -4 -c5 localhost", "r");108 (void)f;109 110 return test_sock();111}112