samples/bpf/libbpf.c

   1 /* eBPF mini library */
   2 #include <stdlib.h>
   3 #include <stdio.h>
   4 #include <linux/unistd.h>
   5 #include <unistd.h>
   6 #include <string.h>
   7 #include <linux/netlink.h>
   8 #include <linux/bpf.h>
   9 #include <errno.h>
  10 #include <net/ethernet.h>
  11 #include <net/if.h>
  12 #include <linux/if_packet.h>
  13 #include <arpa/inet.h>
  14 #include "libbpf.h"
  15
  16 static __u64 ptr_to_u64(void *ptr)
  17 {
  18         return (__u64) (unsigned long) ptr;
  19 }
  20
  21 int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size,
  22                    int max_entries)
  23 {
  24         union bpf_attr attr = {
  25                 .map_type = map_type,
  26                 .key_size = key_size,
  27                 .value_size = value_size,
  28                 .max_entries = max_entries
  29         };
  30
  31         return syscall(__NR_bpf, BPF_MAP_CREATE, &attr, sizeof(attr));
  32 }
  33
  34 int bpf_update_elem(int fd, void *key, void *value, unsigned long long flags)
  35 {
  36         union bpf_attr attr = {
  37                 .map_fd = fd,
  38                 .key = ptr_to_u64(key),
  39                 .value = ptr_to_u64(value),
  40                 .flags = flags,
  41         };
  42
  43         return syscall(__NR_bpf, BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
  44 }
  45
  46 int bpf_lookup_elem(int fd, void *key, void *value)
  47 {
  48         union bpf_attr attr = {
  49                 .map_fd = fd,
  50                 .key = ptr_to_u64(key),
  51                 .value = ptr_to_u64(value),
  52         };
  53
  54         return syscall(__NR_bpf, BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
  55 }
  56
  57 int bpf_delete_elem(int fd, void *key)
  58 {
  59         union bpf_attr attr = {
  60                 .map_fd = fd,
  61                 .key = ptr_to_u64(key),
  62         };
  63
  64         return syscall(__NR_bpf, BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
  65 }
  66
  67 int bpf_get_next_key(int fd, void *key, void *next_key)
  68 {
  69         union bpf_attr attr = {
  70                 .map_fd = fd,
  71                 .key = ptr_to_u64(key),
  72                 .next_key = ptr_to_u64(next_key),
  73         };
  74
  75         return syscall(__NR_bpf, BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
  76 }
  77
  78 #define ROUND_UP(x, n) (((x) + (n) - 1u) & ~((n) - 1u))
  79
  80 char bpf_log_buf[LOG_BUF_SIZE];
  81
  82 int bpf_prog_load(enum bpf_prog_type prog_type,
  83                   const struct bpf_insn *insns, int prog_len,
  84                   const char *license)
  85 {
  86         union bpf_attr attr = {
  87                 .prog_type = prog_type,
  88                 .insns = ptr_to_u64((void *) insns),
  89                 .insn_cnt = prog_len / sizeof(struct bpf_insn),
  90                 .license = ptr_to_u64((void *) license),
  91                 .log_buf = ptr_to_u64(bpf_log_buf),
  92                 .log_size = LOG_BUF_SIZE,
  93                 .log_level = 1,
  94         };
  95
  96         bpf_log_buf[0] = 0;
  97
  98         return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
  99 }
 100
 101 int open_raw_sock(const char *name)
 102 {
 103         struct sockaddr_ll sll;
 104         int sock;
 105
 106         sock = socket(PF_PACKET, SOCK_RAW | SOCK_NONBLOCK | SOCK_CLOEXEC, htons(ETH_P_ALL));
 107         if (sock < 0) {
 108                 printf("cannot create raw socket\n");
 109                 return -1;
 110         }
 111
 112         memset(&sll, 0, sizeof(sll));
 113         sll.sll_family = AF_PACKET;
 114         sll.sll_ifindex = if_nametoindex(name);
 115         sll.sll_protocol = htons(ETH_P_ALL);
 116         if (bind(sock, (struct sockaddr *)&sll, sizeof(sll)) < 0) {
 117                 printf("bind to %s: %s\n", name, strerror(errno));
 118                 close(sock);
 119                 return -1;
 120         }
 121
 122         return sock;
 123 }