samples/bpf/cookie_uid_helper_example.c

   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
  58 struct stats {
  59         uint32_t uid;
  60         uint64_t packets;
  61         uint64_t bytes;
  62 };
  63
  64 static int map_fd, prog_fd;
  65
  66 static bool test_finish;
  67
  68 static void maps_create(void)
  69 {
  70         map_fd = bpf_map_create(BPF_MAP_TYPE_HASH, NULL, sizeof(uint32_t),
  71                                 sizeof(struct stats), 100, NULL);
  72         if (map_fd < 0)
  73                 error(1, errno, "map create failed!\n");
  74 }
  75
  76 static 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         LIBBPF_OPTS(bpf_prog_load_opts, opts,
 161                 .log_buf = log_buf,
 162                 .log_size = sizeof(log_buf),
 163         );
 164
 165         prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
 166                                 prog, ARRAY_SIZE(prog), &opts);
 167         if (prog_fd < 0)
 168                 error(1, errno, "failed to load prog\n%s\n", log_buf);
 169 }
 170
 171 static void prog_attach_iptables(char *file)
 172 {
 173         int ret;
 174         char rules[256];
 175
 176         if (bpf_obj_pin(prog_fd, file))
 177                 error(1, errno, "bpf_obj_pin");
 178         if (strlen(file) > 50) {
 179                 printf("file path too long: %s\n", file);
 180                 exit(1);
 181         }
 182         ret = snprintf(rules, sizeof(rules),
 183                        "iptables -A OUTPUT -m bpf --object-pinned %s -j ACCEPT",
 184                        file);
 185         if (ret < 0 || ret >= sizeof(rules)) {
 186                 printf("error constructing iptables command\n");
 187                 exit(1);
 188         }
 189         ret = system(rules);
 190         if (ret < 0) {
 191                 printf("iptables rule update failed: %d/n", WEXITSTATUS(ret));
 192                 exit(1);
 193         }
 194 }
 195
 196 static void print_table(void)
 197 {
 198         struct stats curEntry;
 199         uint32_t curN = UINT32_MAX;
 200         uint32_t nextN;
 201         int res;
 202
 203         while (bpf_map_get_next_key(map_fd, &curN, &nextN) > -1) {
 204                 curN = nextN;
 205                 res = bpf_map_lookup_elem(map_fd, &curN, &curEntry);
 206                 if (res < 0) {
 207                         error(1, errno, "fail to get entry value of Key: %u\n",
 208                                 curN);
 209                 } else {
 210                         printf("cookie: %u, uid: 0x%x, Packet Count: %lu,"
 211                                 " Bytes Count: %lu\n", curN, curEntry.uid,
 212                                 curEntry.packets, curEntry.bytes);
 213                 }
 214         }
 215 }
 216
 217 static void udp_client(void)
 218 {
 219         struct sockaddr_in si_other = {0};
 220         struct sockaddr_in si_me = {0};
 221         struct stats dataEntry;
 222         int s_rcv, s_send, i, recv_len;
 223         char message = 'a';
 224         char buf;
 225         uint64_t cookie;
 226         int res;
 227         socklen_t cookie_len = sizeof(cookie);
 228         socklen_t slen = sizeof(si_other);
 229
 230         s_rcv = socket(PF_INET, SOCK_DGRAM, 0);
 231         if (s_rcv < 0)
 232                 error(1, errno, "rcv socket creat failed!\n");
 233         si_other.sin_family = AF_INET;
 234         si_other.sin_port = htons(PORT);
 235         if (inet_aton("127.0.0.1", &si_other.sin_addr) == 0)
 236                 error(1, errno, "inet_aton\n");
 237         if (bind(s_rcv, (struct sockaddr *)&si_other, sizeof(si_other)) == -1)
 238                 error(1, errno, "bind\n");
 239         s_send = socket(PF_INET, SOCK_DGRAM, 0);
 240         if (s_send < 0)
 241                 error(1, errno, "send socket creat failed!\n");
 242         res = getsockopt(s_send, SOL_SOCKET, SO_COOKIE, &cookie, &cookie_len);
 243         if (res < 0)
 244                 printf("get cookie failed: %s\n", strerror(errno));
 245         res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
 246         if (res != -1)
 247                 error(1, errno, "socket stat found while flow not active\n");
 248         for (i = 0; i < 10; i++) {
 249                 res = sendto(s_send, &message, sizeof(message), 0,
 250                              (struct sockaddr *)&si_other, slen);
 251                 if (res == -1)
 252                         error(1, errno, "send\n");
 253                 if (res != sizeof(message))
 254                         error(1, 0, "%uB != %luB\n", res, sizeof(message));
 255                 recv_len = recvfrom(s_rcv, &buf, sizeof(buf), 0,
 256                              (struct sockaddr *)&si_me, &slen);
 257                 if (recv_len < 0)
 258                         error(1, errno, "receive\n");
 259                 res = memcmp(&(si_other.sin_addr), &(si_me.sin_addr),
 260                            sizeof(si_me.sin_addr));
 261                 if (res != 0)
 262                         error(1, EFAULT, "sender addr error: %d\n", res);
 263                 printf("Message received: %c\n", buf);
 264                 res = bpf_map_lookup_elem(map_fd, &cookie, &dataEntry);
 265                 if (res < 0)
 266                         error(1, errno, "lookup sk stat failed, cookie: %lu\n",
 267                               cookie);
 268                 printf("cookie: %lu, uid: 0x%x, Packet Count: %lu,"
 269                         " Bytes Count: %lu\n\n", cookie, dataEntry.uid,
 270                         dataEntry.packets, dataEntry.bytes);
 271         }
 272         close(s_send);
 273         close(s_rcv);
 274 }
 275
 276 static int usage(void)
 277 {
 278         printf("Usage: ./run_cookie_uid_helper_example.sh"
 279                 " bpfObjName -option\n"
 280                 "       -t      traffic monitor test\n"
 281                 "       -s      getsockopt cookie test\n");
 282         return 1;
 283 }
 284
 285 static void finish(int ret)
 286 {
 287         test_finish = true;
 288 }
 289
 290 int main(int argc, char *argv[])
 291 {
 292         int opt;
 293         bool cfg_test_traffic = false;
 294         bool cfg_test_cookie = false;
 295
 296         if (argc != 3)
 297                 return usage();
 298         while ((opt = getopt(argc, argv, "ts")) != -1) {
 299                 switch (opt) {
 300                 case 't':
 301                         cfg_test_traffic = true;
 302                         break;
 303                 case 's':
 304                         cfg_test_cookie = true;
 305                         break;
 306
 307                 default:
 308                         printf("unknown option %c\n", opt);
 309                         usage();
 310                         return -1;
 311                 }
 312         }
 313         maps_create();
 314         prog_load();
 315         prog_attach_iptables(argv[2]);
 316         if (cfg_test_traffic) {
 317                 if (signal(SIGINT, finish) == SIG_ERR)
 318                         error(1, errno, "register SIGINT handler failed");
 319                 if (signal(SIGTERM, finish) == SIG_ERR)
 320                         error(1, errno, "register SIGTERM handler failed");
 321                 while (!test_finish) {
 322                         print_table();
 323                         printf("\n");
 324                         sleep(1);
 325                 }
 326         } else if (cfg_test_cookie) {
 327                 udp_client();
 328         }
 329         close(prog_fd);
 330         close(map_fd);
 331         return 0;
 332 }