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 "libbpf.h"
  18 #include "bpf_insn.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         char bpf_log_buf[BPF_LOG_BUF_SIZE];
  61         struct bpf_object *obj;
  62         int prog_fd;
  63
  64         if (object) {
  65                 assert(!bpf_prog_load(object, BPF_PROG_TYPE_UNSPEC,
  66                                       &obj, &prog_fd));
  67                 return prog_fd;
  68         } else {
  69                 return bpf_load_program(BPF_PROG_TYPE_SOCKET_FILTER,
  70                                         insns, insns_cnt, "GPL", 0,
  71                                         bpf_log_buf, BPF_LOG_BUF_SIZE);
  72         }
  73 }
  74
  75 static int bpf_do_map(const char *file, uint32_t flags, uint32_t key,
  76                       uint32_t value)
  77 {
  78         int fd, ret;
  79
  80         if (flags & BPF_F_PIN) {
  81                 fd = bpf_map_create();
  82                 printf("bpf: map fd:%d (%s)\n", fd, strerror(errno));
  83                 assert(fd > 0);
  84
  85                 ret = bpf_obj_pin(fd, file);
  86                 printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
  87                 assert(ret == 0);
  88         } else {
  89                 fd = bpf_obj_get(file);
  90                 printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
  91                 assert(fd > 0);
  92         }
  93
  94         if ((flags & BPF_F_KEY_VAL) == BPF_F_KEY_VAL) {
  95                 ret = bpf_map_update_elem(fd, &key, &value, 0);
  96                 printf("bpf: fd:%d u->(%u:%u) ret:(%d,%s)\n", fd, key, value,
  97                        ret, strerror(errno));
  98                 assert(ret == 0);
  99         } else if (flags & BPF_F_KEY) {
 100                 ret = bpf_map_lookup_elem(fd, &key, &value);
 101                 printf("bpf: fd:%d l->(%u):%u ret:(%d,%s)\n", fd, key, value,
 102                        ret, strerror(errno));
 103                 assert(ret == 0);
 104         }
 105
 106         return 0;
 107 }
 108
 109 static int bpf_do_prog(const char *file, uint32_t flags, const char *object)
 110 {
 111         int fd, sock, ret;
 112
 113         if (flags & BPF_F_PIN) {
 114                 fd = bpf_prog_create(object);
 115                 printf("bpf: prog fd:%d (%s)\n", fd, strerror(errno));
 116                 assert(fd > 0);
 117
 118                 ret = bpf_obj_pin(fd, file);
 119                 printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
 120                 assert(ret == 0);
 121         } else {
 122                 fd = bpf_obj_get(file);
 123                 printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
 124                 assert(fd > 0);
 125         }
 126
 127         sock = open_raw_sock("lo");
 128         assert(sock > 0);
 129
 130         ret = setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &fd, sizeof(fd));
 131         printf("bpf: sock:%d <- fd:%d attached ret:(%d,%s)\n", sock, fd,
 132                ret, strerror(errno));
 133         assert(ret == 0);
 134
 135         return 0;
 136 }
 137
 138 int main(int argc, char **argv)
 139 {
 140         const char *file = NULL, *object = NULL;
 141         uint32_t key = 0, value = 0, flags = 0;
 142         int opt, mode = BPF_M_UNSPEC;
 143
 144         while ((opt = getopt(argc, argv, "F:PGmk:v:po:")) != -1) {
 145                 switch (opt) {
 146                 /* General args */
 147                 case 'F':
 148                         file = optarg;
 149                         break;
 150                 case 'P':
 151                         flags |= BPF_F_PIN;
 152                         break;
 153                 case 'G':
 154                         flags |= BPF_F_GET;
 155                         break;
 156                 /* Map-related args */
 157                 case 'm':
 158                         mode = BPF_M_MAP;
 159                         break;
 160                 case 'k':
 161                         key = strtoul(optarg, NULL, 0);
 162                         flags |= BPF_F_KEY;
 163                         break;
 164                 case 'v':
 165                         value = strtoul(optarg, NULL, 0);
 166                         flags |= BPF_F_VAL;
 167                         break;
 168                 /* Prog-related args */
 169                 case 'p':
 170                         mode = BPF_M_PROG;
 171                         break;
 172                 case 'o':
 173                         object = optarg;
 174                         break;
 175                 default:
 176                         goto out;
 177                 }
 178         }
 179
 180         if (!(flags & BPF_F_PIN_GET) || !file)
 181                 goto out;
 182
 183         switch (mode) {
 184         case BPF_M_MAP:
 185                 return bpf_do_map(file, flags, key, value);
 186         case BPF_M_PROG:
 187                 return bpf_do_prog(file, flags, object);
 188         }
 189 out:
 190         usage();
 191         return -1;
 192 }