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