blob: c8ad0404416f5da95e318cf4580255abc5174ee0 [file] [log] [blame]
Alexei Starovoitov03f47232014-12-01 15:06:36 -08001/* eBPF example program:
2 * - creates arraymap in kernel with key 4 bytes and value 8 bytes
3 *
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 map
8 * value = bpf_map_lookup_elem(map_fd, fp - 4);
9 * if (value)
10 * (*(u64*)value) += 1;
11 *
12 * - attaches this program to eth0 raw socket
13 *
14 * - every second user space reads map[tcp], map[udp], map[icmp] to see
15 * how many packets of given protocol were seen on eth0
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 "libbpf.h"
30
31static int test_sock(void)
32{
33 int sock = -1, map_fd, prog_fd, i, key;
34 long long value = 0, tcp_cnt, udp_cnt, icmp_cnt;
35
36 map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(key), sizeof(value),
37 256);
38 if (map_fd < 0) {
39 printf("failed to create map '%s'\n", strerror(errno));
40 goto cleanup;
41 }
42
43 struct bpf_insn prog[] = {
44 BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
45 BPF_LD_ABS(BPF_B, ETH_HLEN + offsetof(struct iphdr, protocol) /* R0 = ip->proto */),
46 BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */
47 BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
48 BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = fp - 4 */
49 BPF_LD_MAP_FD(BPF_REG_1, map_fd),
50 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
51 BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
52 BPF_MOV64_IMM(BPF_REG_1, 1), /* r1 = 1 */
53 BPF_RAW_INSN(BPF_STX | BPF_XADD | BPF_DW, BPF_REG_0, BPF_REG_1, 0, 0), /* xadd r0 += r1 */
54 BPF_MOV64_IMM(BPF_REG_0, 0), /* r0 = 0 */
55 BPF_EXIT_INSN(),
56 };
57
58 prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, prog, sizeof(prog),
59 "GPL");
60 if (prog_fd < 0) {
61 printf("failed to load prog '%s'\n", strerror(errno));
62 goto cleanup;
63 }
64
65 sock = open_raw_sock("lo");
66
67 if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd,
68 sizeof(prog_fd)) < 0) {
69 printf("setsockopt %s\n", strerror(errno));
70 goto cleanup;
71 }
72
73 for (i = 0; i < 10; i++) {
74 key = IPPROTO_TCP;
75 assert(bpf_lookup_elem(map_fd, &key, &tcp_cnt) == 0);
76
77 key = IPPROTO_UDP;
78 assert(bpf_lookup_elem(map_fd, &key, &udp_cnt) == 0);
79
80 key = IPPROTO_ICMP;
81 assert(bpf_lookup_elem(map_fd, &key, &icmp_cnt) == 0);
82
83 printf("TCP %lld UDP %lld ICMP %lld packets\n",
84 tcp_cnt, udp_cnt, icmp_cnt);
85 sleep(1);
86 }
87
88cleanup:
89 /* maps, programs, raw sockets will auto cleanup on process exit */
90 return 0;
91}
92
93int main(void)
94{
95 FILE *f;
96
97 f = popen("ping -c5 localhost", "r");
98 (void)f;
99
100 return test_sock();
101}