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Commit | Line | Data |
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03f4723e AS |
1 | /* 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 | ||
31 | static 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 | ||
88 | cleanup: | |
89 | /* maps, programs, raw sockets will auto cleanup on process exit */ | |
90 | return 0; | |
91 | } | |
92 | ||
93 | int main(void) | |
94 | { | |
95 | FILE *f; | |
96 | ||
97 | f = popen("ping -c5 localhost", "r"); | |
98 | (void)f; | |
99 | ||
100 | return test_sock(); | |
101 | } |