LXR linux/samples/bpf/cookie_uid_helper

   1/* This test is a demo of using get_socket_uid and get_socket_cookie
   2 * helper function to do per socket based network traffic monitoring.
   3 * It requires iptables version higher then 1.6.1. to load pinned eBPF
   4 * program into the xt_bpf match.
   5 *
   6 * TEST:
   7 * ./run_cookie_uid_helper_example.sh -option
   8 * option:
   9 *      -t: do traffic monitoring test, the program will continuously
  10 * print out network traffic happens after program started A sample
  11 * output is shown below:
  12 *
  13 * cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
  14 * cookie: 132, uid: 0x0, Pakcet Count: 2, Bytes Count: 286
  15 * cookie: 812, uid: 0x3e8, Pakcet Count: 3, Bytes Count: 1726
  16 * cookie: 802, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
  17 * cookie: 877, uid: 0x3e8, Pakcet Count: 20, Bytes Count: 11058
  18 * cookie: 831, uid: 0x3e8, Pakcet Count: 2, Bytes Count: 104
  19 * cookie: 0, uid: 0x0, Pakcet Count: 6, Bytes Count: 712
  20 * cookie: 880, uid: 0xfffe, Pakcet Count: 1, Bytes Count: 70
  21 *
  22 *      -s: do getsockopt SO_COOKIE test, the program will set up a pair of
  23 * UDP sockets and send packets between them. And read out the traffic data
  24 * directly from the ebpf map based on the socket cookie.
  25 *
  26 * Clean up: if using shell script, the script file will delete the iptables
  27 * rule and unmount the bpf program when exit. Else the iptables rule need
  28 * to be deleted by hand, see run_cookie_uid_helper_example.sh for detail.
  29 */
  30
  31#define _GNU_SOURCE
  32
  33#define offsetof(type, member)  __builtin_offsetof(type, member)
  34#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
  35
  36#include <arpa/inet.h>
  37#include <errno.h>
  38#include <error.h>
  39#include <limits.h>
  40#include <linux/bpf.h>
  41#include <linux/if_ether.h>
  42#include <net/if.h>
  43#include <signal.h>
  44#include <stdbool.h>
  45#include <stdint.h>
  46#include <stdio.h>
  47#include <stdlib.h>
  48#include <string.h>
  49#include <sys/socket.h>
  50#include <sys/stat.h>
  51#include <sys/types.h>
  52#include <unistd.h>
  53#include <bpf/bpf.h>
  54#include "bpf_insn.h"
  55
  56#define PORT 8888
  57
  58struct stats {
  59        uint32_t uid;
  60        uint64_t packets;
  61        uint64_t bytes;
  62};
  63
  64static int map_fd, prog_fd;
  65
  66static bool test_finish;
  67
  68static void maps_create(void)
  69{
  70        map_fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(uint32_t),
  71                                sizeof(struct stats), 100, 0);
  72        if (map_fd < 0)
  73                error(1, errno, "map create failed!\n");
  74}
  75
  76static void prog_load(void)
  77{
  78        static char log_buf[1 << 16];
  79
  80        struct bpf_insn prog[] = {
  81                /*
  82                 * Save sk_buff for future usage. value stored in R6 to R10 will
  83                 * not be reset after a bpf helper function call.
  84                 */
  85                BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),
  86                /*
  87                 * pc1: BPF_FUNC_get_socket_cookie takes one parameter,
  88                 * R1: sk_buff
  89                 */
  90                BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
  91                                BPF_FUNC_get_socket_cookie),
  92                /* pc2-4: save &socketCookie to r7 for future usage*/
  93                BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0, -8),
  94                BPF_MOV64_REG(BPF_REG_7, BPF_REG_10),
  95                BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, -8),
  96                /*
  97                 * pc5-8: set up the registers for BPF_FUNC_map_lookup_elem,
  98                 * it takes two parameters (R1: map_fd,  R2: &socket_cookie)
  99                 */
 100                BPF_LD_MAP_FD(BPF_REG_1, map_fd),
 101                BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
 102                BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
 103                                BPF_FUNC_map_lookup_elem),
 104                /*
 105                 * pc9. if r0 != 0x0, go to pc+14, since we have the cookie
 106                 * stored already
 107                 * Otherwise do pc10-22 to setup a new data entry.
 108                 */
 109                BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 14),
 110                BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
 111                BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
 112                                BPF_FUNC_get_socket_uid),
 113                /*
 114                 * Place a struct stats in the R10 stack and sequentially
 115                 * place the member value into the memory. Packets value
 116                 * is set by directly place a IMM value 1 into the stack.
 117                 */
 118                BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_0,
 119                            -32 + (__s16)offsetof(struct stats, uid)),
 120                BPF_ST_MEM(BPF_DW, BPF_REG_10,
 121                           -32 + (__s16)offsetof(struct stats, packets), 1),
 122                /*
 123                 * __sk_buff is a special struct used for eBPF program to
 124                 * directly access some sk_buff field.
 125                 */
 126                BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
 127                                offsetof(struct __sk_buff, len)),
 128                BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1,
 129                            -32 + (__s16)offsetof(struct stats, bytes)),
 130                /*
 131                 * add new map entry using BPF_FUNC_map_update_elem, it takes
 132                 * 4 parameters (R1: map_fd, R2: &socket_cookie, R3: &stats,
 133                 * R4: flags)
 134                 */
 135                BPF_LD_MAP_FD(BPF_REG_1, map_fd),
 136                BPF_MOV64_REG(BPF_REG_2, BPF_REG_7),
 137                BPF_MOV64_REG(BPF_REG_3, BPF_REG_10),
 138                BPF_ALU64_IMM(BPF_ADD, BPF_REG_3, -32),
 139                BPF_MOV64_IMM(BPF_REG_4, 0),
 140                BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
 141                                BPF_FUNC_map_update_elem),
 142                BPF_JMP_IMM(BPF_JA, 0, 0, 5),
 143                /*
 144                 * pc24-30 update the packet info to a exist data entry, it can
 145                 * be done by directly write to pointers instead of using
 146                 * BPF_FUNC_map_update_elem helper function
 147                 */
 148                BPF_MOV64_REG(BPF_REG_9, BPF_REG_0),
 149                BPF_MOV64_IMM(BPF_REG_1, 1),
 150                BPF_ATOMIC_OP(BPF_DW, BPF_ADD, BPF_REG_9, BPF_REG_1,
 151                              offsetof(struct stats, packets)),
 152                BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_6,
 153                                offsetof(struct __sk_buff, len)),
 154                BPF_ATOMIC_OP(BPF_DW, BPF_ADD, BPF_REG_9, BPF_REG_1,
 155                              offsetof(struct stats, bytes)),
 156                BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_6,
 157                                offsetof(struct __sk_buff, len)),
 158                BPF_EXIT_INSN(),
 159        };
 160        prog_fd = bpf_load_program(BPF_PROG_TYPE_SOCKET_FILTER, prog,
 161                                        ARRAY_SIZE(prog), "GPL", 0,
 162                                        log_buf, sizeof(log_buf));
 163        if (prog_fd < 0)
 164                error(1, errno, "failed to load prog\n%s\n", log_buf);
 165}
 166
 167static void prog_attach_iptables(char *file)
 168{
 169        int ret;
 170        char rules[256];
 171
 172        if (bpf_obj_pin(prog_fd, file))
 173                error(1, errno, "bpf_obj_pin");
 174        if (strlen(file) > 50) {
 175                printf("file path too long: %s\n", file);
 176                exit(1);
 177        }
 178        ret = snprintf(rules, sizeof(rules),
 179                       "iptables -A OUTPUT -m bpf --object-pinned %s -j ACCEPT",
 180                       file);
 181        if (ret < 0 || ret >= sizeof(rules)) {
 182                printf("error constructing iptables command\n");
 183                exit(1);
 184        }
 185        ret = system(rules);
 186        if (ret < 0) {
 187                printf("iptables rule update failed: %d/n", WEXITSTATUS(ret));
 188                exit(1);
 189        }
 190}
 191
 192static void print_table(void)
 193{
 194        struct stats curEntry;
 195        uint32_t curN = UINT32_MAX;
 196        uint32_t nextN;
 197        int res;
 198
 199        while (bpf_map_get_next_key(map_fd, &curN, &nextN) > -1) {
 200                curN = nextN;
 201                res = bpf_map_lookup_elem(map_fd, &curN, &curEntry);
 202                if (res < 0) {
 203                        error(1, errno, "fail to get entry value of Key: %u\n",
 204                                curN);
 205                } else {
 206                        printf("cookie: %u, uid: 0x%x, Packet Count: %lu,"
 207                                " Bytes Count: %lu\n", curN, curEntry.uid,
 208                                curEntry.packets, curEntry.bytes);
 209                }
 210        }
 211}
 212
 213static void udp_client(void)
 214{
 215        struct sockaddr_in si_other = {0};
 216        struct sockaddr_in si_me = {0};
 217        struct stats dataEntry;
 218        int s_rcv, s_send, i, recv_len;
 219        char message = 'a';
 220        char buf;
 221        uint64_t cookie;
 222        int res;
 223        socklen_t cookie_len = sizeof(cookie);
 224        socklen_t slen = sizeof(si_other);
 225
 226        s_rcv = socket(PF_INET, SOCK_DGRAM, 0);
 227        if (s_rcv < 0)
 228                error(1, errno, "rcv socket creat failed!\n");
 229        si_other.sin_family = AF_INET;
 230        si_other.sin_port = htons(PORT);
 231        if (inet_aton("127.0.0.1", &si_other.sin_addr) == 0)
 232                error(1, errno, "inet_aton\n");
 233        if (bind(s_rcv, (struct sockaddr *)&si_other, sizeof(si_other)) == -1)
 234                error(1, errno, "bind\n");
 235        s_send = socket(PF_INET, SOCK_DGRAM, 0);
 236        if (s_send < 0)
 237                error(1, errno, "send socket creat failed!\n");
 238        res = getsockopt(s_send, SOL_SOCKET, SO_COOKIE, &cookie, &cookie_len);
 239        if (res < 0)
 240                printf("get cookie failed: %s\n", strerror(errno));
 241        res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
 242        if (res != -1)
 243                error(1, errno, "socket stat found while flow not active\n");
 244        for (i = 0; i < 10; i++) {
 245                res = sendto(s_send, &message, sizeof(message), 0,
 246                             (struct sockaddr *)&si_other, slen);
 247                if (res == -1)
 248                        error(1, errno, "send\n");
 249                if (res != sizeof(message))
 250                        error(1, 0, "%uB != %luB\n", res, sizeof(message));
 251                recv_len = recvfrom(s_rcv, &buf, sizeof(buf), 0,
 252                             (struct sockaddr *)&si_me, &slen);
 253                if (recv_len < 0)
 254                        error(1, errno, "receive\n");
 255                res = memcmp(&(si_other.sin_addr), &(si_me.sin_addr),
 256                           sizeof(si_me.sin_addr));
 257                if (res != 0)
 258                        error(1, EFAULT, "sender addr error: %d\n", res);
 259                printf("Message received: %c\n", buf);
 260                res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
 261                if (res < 0)
 262                        error(1, errno, "lookup sk stat failed, cookie: %lu\n",
 263                              cookie);
 264                printf("cookie: %lu, uid: 0x%x, Packet Count: %lu,"
 265                        " Bytes Count: %lu\n\n", cookie, dataEntry.uid,
 266                        dataEntry.packets, dataEntry.bytes);
 267        }
 268        close(s_send);
 269        close(s_rcv);
 270}
 271
 272static int usage(void)
 273{
 274        printf("Usage: ./run_cookie_uid_helper_example.sh"
 275                " bpfObjName -option\n"
 276                "       -t      traffic monitor test\n"
 277                "       -s      getsockopt cookie test\n");
 278        return 1;
 279}
 280
 281static void finish(int ret)
 282{
 283        test_finish = true;
 284}
 285
 286int main(int argc, char *argv[])
 287{
 288        int opt;
 289        bool cfg_test_traffic = false;
 290        bool cfg_test_cookie = false;
 291
 292        if (argc != 3)
 293                return usage();
 294        while ((opt = getopt(argc, argv, "ts")) != -1) {
 295                switch (opt) {
 296                case 't':
 297                        cfg_test_traffic = true;
 298                        break;
 299                case 's':
 300                        cfg_test_cookie = true;
 301                        break;
 302
 303                default:
 304                        printf("unknown option %c\n", opt);
 305                        usage();
 306                        return -1;
 307                }
 308        }
 309        maps_create();
 310        prog_load();
 311        prog_attach_iptables(argv[2]);
 312        if (cfg_test_traffic) {
 313                if (signal(SIGINT, finish) == SIG_ERR)
 314                        error(1, errno, "register SIGINT handler failed");
 315                if (signal(SIGTERM, finish) == SIG_ERR)
 316                        error(1, errno, "register SIGTERM handler failed");
 317                while (!test_finish) {
 318                        print_table();
 319                        printf("\n");
 320                        sleep(1);
 321                }
 322        } else if (cfg_test_cookie) {
 323                udp_client();
 324        }
 325        close(prog_fd);
 326        close(map_fd);
 327        return 0;
 328}
 329