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, int map_flags)
  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                 .map_flags = map_flags,
  30         };
  31
  32         return syscall(__NR_bpf, BPF_MAP_CREATE, &attr, sizeof(attr));
  33 }
  34
  35 int bpf_update_elem(int fd, void *key, void *value, unsigned long long flags)
  36 {
  37         union bpf_attr attr = {
  38                 .map_fd = fd,
  39                 .key = ptr_to_u64(key),
  40                 .value = ptr_to_u64(value),
  41                 .flags = flags,
  42         };
  43
  44         return syscall(__NR_bpf, BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
  45 }
  46
  47 int bpf_lookup_elem(int fd, void *key, void *value)
  48 {
  49         union bpf_attr attr = {
  50                 .map_fd = fd,
  51                 .key = ptr_to_u64(key),
  52                 .value = ptr_to_u64(value),
  53         };
  54
  55         return syscall(__NR_bpf, BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
  56 }
  57
  58 int bpf_delete_elem(int fd, void *key)
  59 {
  60         union bpf_attr attr = {
  61                 .map_fd = fd,
  62                 .key = ptr_to_u64(key),
  63         };
  64
  65         return syscall(__NR_bpf, BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
  66 }
  67
  68 int bpf_get_next_key(int fd, void *key, void *next_key)
  69 {
  70         union bpf_attr attr = {
  71                 .map_fd = fd,
  72                 .key = ptr_to_u64(key),
  73                 .next_key = ptr_to_u64(next_key),
  74         };
  75
  76         return syscall(__NR_bpf, BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
  77 }
  78
  79 #define ROUND_UP(x, n) (((x) + (n) - 1u) & ~((n) - 1u))
  80
  81 char bpf_log_buf[LOG_BUF_SIZE];
  82
  83 int bpf_prog_load(enum bpf_prog_type prog_type,
  84                   const struct bpf_insn *insns, int prog_len,
  85                   const char *license, int kern_version)
  86 {
  87         union bpf_attr attr = {
  88                 .prog_type = prog_type,
  89                 .insns = ptr_to_u64((void *) insns),
  90                 .insn_cnt = prog_len / sizeof(struct bpf_insn),
  91                 .license = ptr_to_u64((void *) license),
  92                 .log_buf = ptr_to_u64(bpf_log_buf),
  93                 .log_size = LOG_BUF_SIZE,
  94                 .log_level = 1,
  95         };
  96
  97         /* assign one field outside of struct init to make sure any
  98          * padding is zero initialized
  99          */
 100         attr.kern_version = kern_version;
 101
 102         bpf_log_buf[0] = 0;
 103
 104         return syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr));
 105 }
 106
 107 int bpf_obj_pin(int fd, const char *pathname)
 108 {
 109         union bpf_attr attr = {
 110                 .pathname       = ptr_to_u64((void *)pathname),
 111                 .bpf_fd         = fd,
 112         };
 113
 114         return syscall(__NR_bpf, BPF_OBJ_PIN, &attr, sizeof(attr));
 115 }
 116
 117 int bpf_obj_get(const char *pathname)
 118 {
 119         union bpf_attr attr = {
 120                 .pathname       = ptr_to_u64((void *)pathname),
 121         };
 122
 123         return syscall(__NR_bpf, BPF_OBJ_GET, &attr, sizeof(attr));
 124 }
 125
 126 int open_raw_sock(const char *name)
 127 {
 128         struct sockaddr_ll sll;
 129         int sock;
 130
 131         sock = socket(PF_PACKET, SOCK_RAW | SOCK_NONBLOCK | SOCK_CLOEXEC, htons(ETH_P_ALL));
 132         if (sock < 0) {
 133                 printf("cannot create raw socket\n");
 134                 return -1;
 135         }
 136
 137         memset(&sll, 0, sizeof(sll));
 138         sll.sll_family = AF_PACKET;
 139         sll.sll_ifindex = if_nametoindex(name);
 140         sll.sll_protocol = htons(ETH_P_ALL);
 141         if (bind(sock, (struct sockaddr *)&sll, sizeof(sll)) < 0) {
 142                 printf("bind to %s: %s\n", name, strerror(errno));
 143                 close(sock);
 144                 return -1;
 145         }
 146
 147         return sock;
 148 }
 149
 150 int perf_event_open(struct perf_event_attr *attr, int pid, int cpu,
 151                     int group_fd, unsigned long flags)
 152 {
 153         return syscall(__NR_perf_event_open, attr, pid, cpu,
 154                        group_fd, flags);
 155 }