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/libbpf.h>
  18 #include "bpf_insn.h"
  19 #include "sock_example.h"
  20 #include "bpf_util.h"
  21
  22 #define BPF_F_PIN       (1 << 0)
  23 #define BPF_F_GET       (1 << 1)
  24 #define BPF_F_PIN_GET   (BPF_F_PIN | BPF_F_GET)
  25
  26 #define BPF_F_KEY       (1 << 2)
  27 #define BPF_F_VAL       (1 << 3)
  28 #define BPF_F_KEY_VAL   (BPF_F_KEY | BPF_F_VAL)
  29
  30 #define BPF_M_UNSPEC    0
  31 #define BPF_M_MAP       1
  32 #define BPF_M_PROG      2
  33
  34 char bpf_log_buf[BPF_LOG_BUF_SIZE];
  35
  36 static void usage(void)
  37 {
  38         printf("Usage: fds_example [...]\n");
  39         printf("       -F <file>   File to pin/get object\n");
  40         printf("       -P          |- pin object\n");
  41         printf("       -G          `- get object\n");
  42         printf("       -m          eBPF map mode\n");
  43         printf("       -k <key>    |- map key\n");
  44         printf("       -v <value>  `- map value\n");
  45         printf("       -p          eBPF prog mode\n");
  46         printf("       -o <object> `- object file\n");
  47         printf("       -h          Display this help.\n");
  48 }
  49
  50 static int bpf_prog_create(const char *object)
  51 {
  52         static struct bpf_insn insns[] = {
  53                 BPF_MOV64_IMM(BPF_REG_0, 1),
  54                 BPF_EXIT_INSN(),
  55         };
  56         size_t insns_cnt = ARRAY_SIZE(insns);
  57         struct bpf_object *obj;
  58         int err;
  59
  60         if (object) {
  61                 obj = bpf_object__open_file(object, NULL);
  62                 assert(!libbpf_get_error(obj));
  63                 err = bpf_object__load(obj);
  64                 assert(!err);
  65                 return bpf_program__fd(bpf_object__next_program(obj, NULL));
  66         } else {
  67                 LIBBPF_OPTS(bpf_prog_load_opts, opts,
  68                         .log_buf = bpf_log_buf,
  69                         .log_size = BPF_LOG_BUF_SIZE,
  70                 );
  71
  72                 return bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
  73                                      insns, insns_cnt, &opts);
  74         }
  75 }
  76
  77 static int bpf_do_map(const char *file, uint32_t flags, uint32_t key,
  78                       uint32_t value)
  79 {
  80         int fd, ret;
  81
  82         if (flags & BPF_F_PIN) {
  83                 fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, NULL, sizeof(uint32_t),
  84                                     sizeof(uint32_t), 1024, NULL);
  85                 printf("bpf: map fd:%d (%s)\n", fd, strerror(errno));
  86                 assert(fd > 0);
  87
  88                 ret = bpf_obj_pin(fd, file);
  89                 printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
  90                 assert(ret == 0);
  91         } else {
  92                 fd = bpf_obj_get(file);
  93                 printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
  94                 assert(fd > 0);
  95         }
  96
  97         if ((flags & BPF_F_KEY_VAL) == BPF_F_KEY_VAL) {
  98                 ret = bpf_map_update_elem(fd, &key, &value, 0);
  99                 printf("bpf: fd:%d u->(%u:%u) ret:(%d,%s)\n", fd, key, value,
 100                        ret, strerror(errno));
 101                 assert(ret == 0);
 102         } else if (flags & BPF_F_KEY) {
 103                 ret = bpf_map_lookup_elem(fd, &key, &value);
 104                 printf("bpf: fd:%d l->(%u):%u ret:(%d,%s)\n", fd, key, value,
 105                        ret, strerror(errno));
 106                 assert(ret == 0);
 107         }
 108
 109         return 0;
 110 }
 111
 112 static int bpf_do_prog(const char *file, uint32_t flags, const char *object)
 113 {
 114         int fd, sock, ret;
 115
 116         if (flags & BPF_F_PIN) {
 117                 fd = bpf_prog_create(object);
 118                 printf("bpf: prog fd:%d (%s)\n", fd, strerror(errno));
 119                 assert(fd > 0);
 120
 121                 ret = bpf_obj_pin(fd, file);
 122                 printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
 123                 assert(ret == 0);
 124         } else {
 125                 fd = bpf_obj_get(file);
 126                 printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
 127                 assert(fd > 0);
 128         }
 129
 130         sock = open_raw_sock("lo");
 131         assert(sock > 0);
 132
 133         ret = setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &fd, sizeof(fd));
 134         printf("bpf: sock:%d <- fd:%d attached ret:(%d,%s)\n", sock, fd,
 135                ret, strerror(errno));
 136         assert(ret == 0);
 137
 138         return 0;
 139 }
 140
 141 int main(int argc, char **argv)
 142 {
 143         const char *file = NULL, *object = NULL;
 144         uint32_t key = 0, value = 0, flags = 0;
 145         int opt, mode = BPF_M_UNSPEC;
 146
 147         while ((opt = getopt(argc, argv, "F:PGmk:v:po:")) != -1) {
 148                 switch (opt) {
 149                 /* General args */
 150                 case 'F':
 151                         file = optarg;
 152                         break;
 153                 case 'P':
 154                         flags |= BPF_F_PIN;
 155                         break;
 156                 case 'G':
 157                         flags |= BPF_F_GET;
 158                         break;
 159                 /* Map-related args */
 160                 case 'm':
 161                         mode = BPF_M_MAP;
 162                         break;
 163                 case 'k':
 164                         key = strtoul(optarg, NULL, 0);
 165                         flags |= BPF_F_KEY;
 166                         break;
 167                 case 'v':
 168                         value = strtoul(optarg, NULL, 0);
 169                         flags |= BPF_F_VAL;
 170                         break;
 171                 /* Prog-related args */
 172                 case 'p':
 173                         mode = BPF_M_PROG;
 174                         break;
 175                 case 'o':
 176                         object = optarg;
 177                         break;
 178                 default:
 179                         goto out;
 180                 }
 181         }
 182
 183         if (!(flags & BPF_F_PIN_GET) || !file)
 184                 goto out;
 185
 186         switch (mode) {
 187         case BPF_M_MAP:
 188                 return bpf_do_map(file, flags, key, value);
 189         case BPF_M_PROG:
 190                 return bpf_do_prog(file, flags, object);
 191         }
 192 out:
 193         usage();
 194         return -1;
 195 }