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106 lines
2.9 KiB
106 lines
2.9 KiB
/* eBPF example program: |
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* - creates arraymap in kernel with key 4 bytes and value 8 bytes |
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* |
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* - loads eBPF program: |
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* r0 = skb->data[ETH_HLEN + offsetof(struct iphdr, protocol)]; |
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* *(u32*)(fp - 4) = r0; |
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* // assuming packet is IPv4, lookup ip->proto in a map |
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* value = bpf_map_lookup_elem(map_fd, fp - 4); |
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* if (value) |
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* (*(u64*)value) += 1; |
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* |
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* - attaches this program to loopback interface "lo" raw socket |
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* |
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* - every second user space reads map[tcp], map[udp], map[icmp] to see |
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* how many packets of given protocol were seen on "lo" |
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*/ |
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#include <stdio.h> |
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#include <unistd.h> |
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#include <assert.h> |
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#include <linux/bpf.h> |
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#include <string.h> |
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#include <stdlib.h> |
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#include <errno.h> |
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#include <sys/socket.h> |
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#include <arpa/inet.h> |
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#include <linux/if_ether.h> |
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#include <linux/ip.h> |
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#include <stddef.h> |
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#include <bpf/bpf.h> |
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#include "bpf_insn.h" |
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#include "sock_example.h" |
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char bpf_log_buf[BPF_LOG_BUF_SIZE]; |
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static int test_sock(void) |
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{ |
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int sock = -1, map_fd, prog_fd, i, key; |
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long long value = 0, tcp_cnt, udp_cnt, icmp_cnt; |
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map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(key), sizeof(value), |
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256, 0); |
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if (map_fd < 0) { |
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printf("failed to create map '%s'\n", strerror(errno)); |
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goto cleanup; |
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} |
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struct bpf_insn prog[] = { |
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BPF_MOV64_REG(BPF_REG_6, BPF_REG_1), |
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BPF_LD_ABS(BPF_B, ETH_HLEN + offsetof(struct iphdr, protocol) /* R0 = ip->proto */), |
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BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */ |
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BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), |
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BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = fp - 4 */ |
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BPF_LD_MAP_FD(BPF_REG_1, map_fd), |
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BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), |
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BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), |
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BPF_MOV64_IMM(BPF_REG_1, 1), /* r1 = 1 */ |
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BPF_ATOMIC_OP(BPF_DW, BPF_ADD, BPF_REG_0, BPF_REG_1, 0), |
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BPF_MOV64_IMM(BPF_REG_0, 0), /* r0 = 0 */ |
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BPF_EXIT_INSN(), |
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}; |
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size_t insns_cnt = sizeof(prog) / sizeof(struct bpf_insn); |
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prog_fd = bpf_load_program(BPF_PROG_TYPE_SOCKET_FILTER, prog, insns_cnt, |
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"GPL", 0, bpf_log_buf, BPF_LOG_BUF_SIZE); |
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if (prog_fd < 0) { |
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printf("failed to load prog '%s'\n", strerror(errno)); |
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goto cleanup; |
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} |
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sock = open_raw_sock("lo"); |
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if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd, |
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sizeof(prog_fd)) < 0) { |
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printf("setsockopt %s\n", strerror(errno)); |
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goto cleanup; |
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} |
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for (i = 0; i < 10; i++) { |
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key = IPPROTO_TCP; |
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assert(bpf_map_lookup_elem(map_fd, &key, &tcp_cnt) == 0); |
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key = IPPROTO_UDP; |
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assert(bpf_map_lookup_elem(map_fd, &key, &udp_cnt) == 0); |
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key = IPPROTO_ICMP; |
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assert(bpf_map_lookup_elem(map_fd, &key, &icmp_cnt) == 0); |
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printf("TCP %lld UDP %lld ICMP %lld packets\n", |
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tcp_cnt, udp_cnt, icmp_cnt); |
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sleep(1); |
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} |
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cleanup: |
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/* maps, programs, raw sockets will auto cleanup on process exit */ |
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return 0; |
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} |
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int main(void) |
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{ |
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FILE *f; |
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f = popen("ping -4 -c5 localhost", "r"); |
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(void)f; |
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return test_sock(); |
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}
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