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