cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

sock_example.c (3019B)

      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 loopback interface "lo" 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 "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
     33char bpf_log_buf[BPF_LOG_BUF_SIZE];
     34
     35static int test_sock(void)
     36{
     37	int sock = -1, map_fd, prog_fd, i, key;
     38	long long value = 0, tcp_cnt, udp_cnt, icmp_cnt;
     39
     40	map_fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, NULL, sizeof(key), sizeof(value),
     41				256, NULL);
     42	if (map_fd < 0) {
     43		printf("failed to create map '%s'\n", strerror(errno));
     44		goto cleanup;
     45	}
     46
     47	struct bpf_insn prog[] = {
     48		BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
     49		BPF_LD_ABS(BPF_B, ETH_HLEN + offsetof(struct iphdr, protocol) /* R0 = ip->proto */),
     50		BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */
     51		BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
     52		BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = fp - 4 */
     53		BPF_LD_MAP_FD(BPF_REG_1, map_fd),
     54		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
     55		BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),
     56		BPF_MOV64_IMM(BPF_REG_1, 1), /* r1 = 1 */
     57		BPF_ATOMIC_OP(BPF_DW, BPF_ADD, BPF_REG_0, BPF_REG_1, 0),
     58		BPF_MOV64_IMM(BPF_REG_0, 0), /* r0 = 0 */
     59		BPF_EXIT_INSN(),
     60	};
     61	size_t insns_cnt = sizeof(prog) / sizeof(struct bpf_insn);
     62	LIBBPF_OPTS(bpf_prog_load_opts, opts,
     63		.log_buf = bpf_log_buf,
     64		.log_size = BPF_LOG_BUF_SIZE,
     65	);
     66
     67	prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
     68				prog, insns_cnt, &opts);
     69	if (prog_fd < 0) {
     70		printf("failed to load prog '%s'\n", strerror(errno));
     71		goto cleanup;
     72	}
     73
     74	sock = open_raw_sock("lo");
     75
     76	if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd,
     77		       sizeof(prog_fd)) < 0) {
     78		printf("setsockopt %s\n", strerror(errno));
     79		goto cleanup;
     80	}
     81
     82	for (i = 0; i < 10; i++) {
     83		key = IPPROTO_TCP;
     84		assert(bpf_map_lookup_elem(map_fd, &key, &tcp_cnt) == 0);
     85
     86		key = IPPROTO_UDP;
     87		assert(bpf_map_lookup_elem(map_fd, &key, &udp_cnt) == 0);
     88
     89		key = IPPROTO_ICMP;
     90		assert(bpf_map_lookup_elem(map_fd, &key, &icmp_cnt) == 0);
     91
     92		printf("TCP %lld UDP %lld ICMP %lld packets\n",
     93		       tcp_cnt, udp_cnt, icmp_cnt);
     94		sleep(1);
     95	}
     96
     97cleanup:
     98	/* maps, programs, raw sockets will auto cleanup on process exit */
     99	return 0;
    100}
    101
    102int main(void)
    103{
    104	FILE *f;
    105
    106	f = popen("ping -4 -c5 localhost", "r");
    107	(void)f;
    108
    109	return test_sock();
    110}