root/samples/bpf/cookie_uid_helper_example.c

DEFINITIONS

1. maps_create
2. prog_load
3. prog_attach_iptables
4. print_table
5. udp_client
6. usage
7. finish
8. main

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