/* This test is a demo of using get_socket_uid and get_socket_cookie
* helper function to do per socket based network traffic monitoring.
* It requires iptables version higher then 1.6.1. to load pinned eBPF
* program into the xt_bpf match.
*
* TEST:
* ./run_cookie_uid_helper_example.sh
* Then generate some traffic in variate ways. ping 0 -c 10 would work
* but the cookie and uid in this case could both be 0. A sample output
* with some traffic generated by web browser is shown below:
*
* cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
* cookie: 132, uid: 0x0, Pakcet Count: 2, Bytes Count: 286
* cookie: 812, uid: 0x3e8, Pakcet Count: 3, Bytes Count: 1726
* cookie: 802, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
* cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
* cookie: 831, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
* cookie: 0, uid: 0x0, Pakcet Count: 6, Bytes Count: 712
* cookie: 880, uid: 0xfffe, Pakcet Count: 1, Bytes Count: 70
*
* Clean up: if using shell script, the script file will delete the iptables
* rule and unmount the bpf program when exit. Else the iptables rule need
* to be deleted by hand, see run_cookie_uid_helper_example.sh for detail.
*/
#define _GNU_SOURCE
#define offsetof(type, member) __builtin_offsetof(type, member)
#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
#include <arpa/inet.h>
#include <errno.h>
#include <error.h>
#include <limits.h>
#include <linux/bpf.h>
#include <linux/if_ether.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <bpf/bpf.h>
#include "libbpf.h"
struct stats {
uint32_t uid;
uint64_t packets;
uint64_t bytes;
};
static int map_fd, prog_fd;
static void maps_create(void)
{
map_fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(uint32_t),
sizeof(struct stats), 100, 0);
if (map_fd < 0)
error(1, errno, "map create failed!\n");
}
static void prog_load(void)
{
static char log_buf[1 << 16];
struct bpf_insn prog[] = {
/*
* Save sk_buff for future usage. value stored in R6 to R10 will
* not be reset after a bpf helper function call.
*/
BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
/*
* pc1: BPF_FUNC_get_socket_cookie takes one parameter,
* R1: sk_buff
*/
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
BPF_FUNC_get_socket_cookie),
/* pc2-4: save &socketCookie to r7 for future usage*/
BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8),
BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
/*
* pc5-8: set up the registers for BPF_FUNC_map_lookup_elem,
* it takes two parameters (R1: map_fd, R2: &socket_cookie)
*/
BPF_LD_MAP_FD(BPF_REG_1, map_fd),
BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
BPF_FUNC_map_lookup_elem),
/*
* pc9. if r0 != 0x0, go to pc+14, since we have the cookie
* stored already
* Otherwise do pc10-22 to setup a new data entry.
*/
BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 14),
BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
BPF_FUNC_get_socket_uid),
/*
* Place a struct stats in the R10 stack and sequentially
* place the member value into the memory. Packets value
* is set by directly place a IMM value 1 into the stack.
*/
BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0,
-32 + offsetof(struct stats, uid)),
BPF_ST_MEM(BPF_DW, BPF_REG_10,
-32 + offsetof(struct stats, packets), 1),
/*
* __sk_buff is a special struct used for eBPF program to
* directly access some sk_buff field.
*/
BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
offsetof(struct __sk_buff, len)),
BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1,
-32 + offsetof(struct stats, bytes)),
/*
* add new map entry using BPF_FUNC_map_update_elem, it takes
* 4 parameters (R1: map_fd, R2: &socket_cookie, R3: &stats,
* R4: flags)
*/
BPF_LD_MAP_FD(BPF_REG_1, map_fd),
BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
BPF_MOV64_REG(BPF_REG_3, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -32),
BPF_MOV64_IMM(BPF_REG_4, 0),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
BPF_FUNC_map_update_elem),
BPF_JMP_IMM(BPF_JA, 0, 0, 5),
/*
* pc24-30 update the packet info to a exist data entry, it can
* be done by directly write to pointers instead of using
* BPF_FUNC_map_update_elem helper function
*/
BPF_MOV64_REG(BPF_REG_9, BPF_REG_0),
BPF_MOV64_IMM(BPF_REG_1, 1),
BPF_STX_XADD(BPF_DW, BPF_REG_9, BPF_REG_1,
offsetof(struct stats, packets)),
BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
offsetof(struct __sk_buff, len)),
BPF_STX_XADD(BPF_DW, BPF_REG_9, BPF_REG_1,
offsetof(struct stats, bytes)),
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6,
offsetof(struct __sk_buff, len)),
BPF_EXIT_INSN(),
};
prog_fd = bpf_load_program(BPF_PROG_TYPE_SOCKET_FILTER, prog,
ARRAY_SIZE(prog), "GPL", 0,
log_buf, sizeof(log_buf));
if (prog_fd < 0)
error(1, errno, "failed to load prog\n%s\n", log_buf);
}
static void prog_attach_iptables(char *file)
{
int ret;
char rules[100];
if (bpf_obj_pin(prog_fd, file))
error(1, errno, "bpf_obj_pin");
if (strlen(file) > 50) {
printf("file path too long: %s\n", file);
exit(1);
}
sprintf(rules, "iptables -A INPUT -m bpf --object-pinned %s -j ACCEPT",
file);
ret = system(rules);
if (ret < 0) {
printf("iptables rule update failed: %d/n", WEXITSTATUS(ret));
exit(1);
}
}
static void print_table(void)
{
struct stats curEntry;
uint32_t curN = UINT32_MAX;
uint32_t nextN, res;
while (bpf_map_get_next_key(map_fd, &curN, &nextN) > -1) {
curN = nextN;
res = bpf_map_lookup_elem(map_fd, &curN, &curEntry);
if (res < 0) {
error(1, errno, "fail to get entry value of Key: %u\n",
curN);
} else {
printf("cookie: %u, uid: 0x%x, Packet Count: %lu,"
" Bytes Count: %lu\n", curN, curEntry.uid,
curEntry.packets, curEntry.bytes);
}
}
}
int main(int argc, char *argv[])
{
if (argc > 2) {
printf("Too many argument provided\n");
return 1;
} else if (argc < 2) {
printf("Usage: %s bpfObjName\n", argv[0]);
return 1;
}
maps_create();
prog_load();
prog_attach_iptables(argv[1]);
while (true) {
print_table();
printf("\n");
sleep(1);
};
return 0;
}
