samples/bpf/fds_example.c

   1 #include <linux/unistd.h>
   2 #include <linux/bpf.h>
   3
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <stdint.h>
   7 #include <unistd.h>
   8 #include <string.h>
   9 #include <assert.h>
  10 #include <errno.h>
  11
  12 #include <sys/types.h>
  13 #include <sys/socket.h>
  14
  15 #include <bpf/bpf.h>
  16
  17 #include "bpf_insn.h"
  18 #include "bpf_load.h"
  19 #include "sock_example.h"
  20
  21 #define BPF_F_PIN       (1 << 0)
  22 #define BPF_F_GET       (1 << 1)
  23 #define BPF_F_PIN_GET   (BPF_F_PIN | BPF_F_GET)
  24
  25 #define BPF_F_KEY       (1 << 2)
  26 #define BPF_F_VAL       (1 << 3)
  27 #define BPF_F_KEY_VAL   (BPF_F_KEY | BPF_F_VAL)
  28
  29 #define BPF_M_UNSPEC    0
  30 #define BPF_M_MAP       1
  31 #define BPF_M_PROG      2
  32
  33 static void usage(void)
  34 {
  35         printf("Usage: fds_example [...]\n");
  36         printf("       -F <file>   File to pin/get object\n");
  37         printf("       -P          |- pin object\n");
  38         printf("       -G          `- get object\n");
  39         printf("       -m          eBPF map mode\n");
  40         printf("       -k <key>    |- map key\n");
  41         printf("       -v <value>  `- map value\n");
  42         printf("       -p          eBPF prog mode\n");
  43         printf("       -o <object> `- object file\n");
  44         printf("       -h          Display this help.\n");
  45 }
  46
  47 static int bpf_map_create(void)
  48 {
  49         return bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(uint32_t),
  50                               sizeof(uint32_t), 1024, 0);
  51 }
  52
  53 static int bpf_prog_create(const char *object)
  54 {
  55         static struct bpf_insn insns[] = {
  56                 BPF_MOV64_IMM(BPF_REG_0, 1),
  57                 BPF_EXIT_INSN(),
  58         };
  59         size_t insns_cnt = sizeof(insns) / sizeof(struct bpf_insn);
  60
  61         if (object) {
  62                 assert(!load_bpf_file((char *)object));
  63                 return prog_fd[0];
  64         } else {
  65                 return bpf_load_program(BPF_PROG_TYPE_SOCKET_FILTER,
  66                                         insns, insns_cnt, "GPL", 0,
  67                                         bpf_log_buf, BPF_LOG_BUF_SIZE);
  68         }
  69 }
  70
  71 static int bpf_do_map(const char *file, uint32_t flags, uint32_t key,
  72                       uint32_t value)
  73 {
  74         int fd, ret;
  75
  76         if (flags & BPF_F_PIN) {
  77                 fd = bpf_map_create();
  78                 printf("bpf: map fd:%d (%s)\n", fd, strerror(errno));
  79                 assert(fd > 0);
  80
  81                 ret = bpf_obj_pin(fd, file);
  82                 printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
  83                 assert(ret == 0);
  84         } else {
  85                 fd = bpf_obj_get(file);
  86                 printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
  87                 assert(fd > 0);
  88         }
  89
  90         if ((flags & BPF_F_KEY_VAL) == BPF_F_KEY_VAL) {
  91                 ret = bpf_map_update_elem(fd, &key, &value, 0);
  92                 printf("bpf: fd:%d u->(%u:%u) ret:(%d,%s)\n", fd, key, value,
  93                        ret, strerror(errno));
  94                 assert(ret == 0);
  95         } else if (flags & BPF_F_KEY) {
  96                 ret = bpf_map_lookup_elem(fd, &key, &value);
  97                 printf("bpf: fd:%d l->(%u):%u ret:(%d,%s)\n", fd, key, value,
  98                        ret, strerror(errno));
  99                 assert(ret == 0);
 100         }
 101
 102         return 0;
 103 }
 104
 105 static int bpf_do_prog(const char *file, uint32_t flags, const char *object)
 106 {
 107         int fd, sock, ret;
 108
 109         if (flags & BPF_F_PIN) {
 110                 fd = bpf_prog_create(object);
 111                 printf("bpf: prog fd:%d (%s)\n", fd, strerror(errno));
 112                 assert(fd > 0);
 113
 114                 ret = bpf_obj_pin(fd, file);
 115                 printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
 116                 assert(ret == 0);
 117         } else {
 118                 fd = bpf_obj_get(file);
 119                 printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
 120                 assert(fd > 0);
 121         }
 122
 123         sock = open_raw_sock("lo");
 124         assert(sock > 0);
 125
 126         ret = setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &fd, sizeof(fd));
 127         printf("bpf: sock:%d <- fd:%d attached ret:(%d,%s)\n", sock, fd,
 128                ret, strerror(errno));
 129         assert(ret == 0);
 130
 131         return 0;
 132 }
 133
 134 int main(int argc, char **argv)
 135 {
 136         const char *file = NULL, *object = NULL;
 137         uint32_t key = 0, value = 0, flags = 0;
 138         int opt, mode = BPF_M_UNSPEC;
 139
 140         while ((opt = getopt(argc, argv, "F:PGmk:v:po:")) != -1) {
 141                 switch (opt) {
 142                 /* General args */
 143                 case 'F':
 144                         file = optarg;
 145                         break;
 146                 case 'P':
 147                         flags |= BPF_F_PIN;
 148                         break;
 149                 case 'G':
 150                         flags |= BPF_F_GET;
 151                         break;
 152                 /* Map-related args */
 153                 case 'm':
 154                         mode = BPF_M_MAP;
 155                         break;
 156                 case 'k':
 157                         key = strtoul(optarg, NULL, 0);
 158                         flags |= BPF_F_KEY;
 159                         break;
 160                 case 'v':
 161                         value = strtoul(optarg, NULL, 0);
 162                         flags |= BPF_F_VAL;
 163                         break;
 164                 /* Prog-related args */
 165                 case 'p':
 166                         mode = BPF_M_PROG;
 167                         break;
 168                 case 'o':
 169                         object = optarg;
 170                         break;
 171                 default:
 172                         goto out;
 173                 }
 174         }
 175
 176         if (!(flags & BPF_F_PIN_GET) || !file)
 177                 goto out;
 178
 179         switch (mode) {
 180         case BPF_M_MAP:
 181                 return bpf_do_map(file, flags, key, value);
 182         case BPF_M_PROG:
 183                 return bpf_do_prog(file, flags, object);
 184         }
 185 out:
 186         usage();
 187         return -1;
 188 }