Alexei Starovoitov | 03f4723 | 2014-12-01 15:06:36 -0800 | [diff] [blame] | 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), |
Alexei Starovoitov | b73b6a8 | 2016-03-07 21:57:20 -0800 | [diff] [blame] | 37 | 256, 0); |
Alexei Starovoitov | 03f4723 | 2014-12-01 15:06:36 -0800 | [diff] [blame] | 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), |
Alexei Starovoitov | b896c4f | 2015-03-25 12:49:23 -0700 | [diff] [blame] | 59 | "GPL", 0); |
Alexei Starovoitov | 03f4723 | 2014-12-01 15:06:36 -0800 | [diff] [blame] | 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 | } |