samples/bpf/xdp_sample_pkts_user.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5 #include <linux/perf_event.h>
   6 #include <linux/bpf.h>
   7 #include <net/if.h>
   8 #include <errno.h>
   9 #include <assert.h>
  10 #include <sys/sysinfo.h>
  11 #include <sys/ioctl.h>
  12 #include <signal.h>
  13 #include <bpf/libbpf.h>
  14 #include <bpf/bpf.h>
  15 #include <sys/resource.h>
  16 #include <libgen.h>
  17 #include <linux/if_link.h>
  18
  19 #include "perf-sys.h"
  20
  21 static int if_idx;
  22 static char *if_name;
  23 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
  24 static __u32 prog_id;
  25 static struct perf_buffer *pb = NULL;
  26
  27 static int do_attach(int idx, int fd, const char *name)
  28 {
  29         struct bpf_prog_info info = {};
  30         __u32 info_len = sizeof(info);
  31         int err;
  32
  33         err = bpf_set_link_xdp_fd(idx, fd, xdp_flags);
  34         if (err < 0) {
  35                 printf("ERROR: failed to attach program to %s\n", name);
  36                 return err;
  37         }
  38
  39         err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
  40         if (err) {
  41                 printf("can't get prog info - %s\n", strerror(errno));
  42                 return err;
  43         }
  44         prog_id = info.id;
  45
  46         return err;
  47 }
  48
  49 static int do_detach(int idx, const char *name)
  50 {
  51         __u32 curr_prog_id = 0;
  52         int err = 0;
  53
  54         err = bpf_get_link_xdp_id(idx, &curr_prog_id, xdp_flags);
  55         if (err) {
  56                 printf("bpf_get_link_xdp_id failed\n");
  57                 return err;
  58         }
  59         if (prog_id == curr_prog_id) {
  60                 err = bpf_set_link_xdp_fd(idx, -1, xdp_flags);
  61                 if (err < 0)
  62                         printf("ERROR: failed to detach prog from %s\n", name);
  63         } else if (!curr_prog_id) {
  64                 printf("couldn't find a prog id on a %s\n", name);
  65         } else {
  66                 printf("program on interface changed, not removing\n");
  67         }
  68
  69         return err;
  70 }
  71
  72 #define SAMPLE_SIZE 64
  73
  74 static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size)
  75 {
  76         struct {
  77                 __u16 cookie;
  78                 __u16 pkt_len;
  79                 __u8  pkt_data[SAMPLE_SIZE];
  80         } __packed *e = data;
  81         int i;
  82
  83         if (e->cookie != 0xdead) {
  84                 printf("BUG cookie %x sized %d\n", e->cookie, size);
  85                 return;
  86         }
  87
  88         printf("Pkt len: %-5d bytes. Ethernet hdr: ", e->pkt_len);
  89         for (i = 0; i < 14 && i < e->pkt_len; i++)
  90                 printf("%02x ", e->pkt_data[i]);
  91         printf("\n");
  92 }
  93
  94 static void sig_handler(int signo)
  95 {
  96         do_detach(if_idx, if_name);
  97         perf_buffer__free(pb);
  98         exit(0);
  99 }
 100
 101 static void usage(const char *prog)
 102 {
 103         fprintf(stderr,
 104                 "%s: %s [OPTS] <ifname|ifindex>\n\n"
 105                 "OPTS:\n"
 106                 "    -F    force loading prog\n",
 107                 __func__, prog);
 108 }
 109
 110 int main(int argc, char **argv)
 111 {
 112         struct bpf_prog_load_attr prog_load_attr = {
 113                 .prog_type      = BPF_PROG_TYPE_XDP,
 114         };
 115         struct perf_buffer_opts pb_opts = {};
 116         const char *optstr = "FS";
 117         int prog_fd, map_fd, opt;
 118         struct bpf_object *obj;
 119         struct bpf_map *map;
 120         char filename[256];
 121         int ret, err;
 122
 123         while ((opt = getopt(argc, argv, optstr)) != -1) {
 124                 switch (opt) {
 125                 case 'F':
 126                         xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
 127                         break;
 128                 case 'S':
 129                         xdp_flags |= XDP_FLAGS_SKB_MODE;
 130                         break;
 131                 default:
 132                         usage(basename(argv[0]));
 133                         return 1;
 134                 }
 135         }
 136
 137         if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
 138                 xdp_flags |= XDP_FLAGS_DRV_MODE;
 139
 140         if (optind == argc) {
 141                 usage(basename(argv[0]));
 142                 return 1;
 143         }
 144
 145         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 146         prog_load_attr.file = filename;
 147
 148         if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
 149                 return 1;
 150
 151         if (!prog_fd) {
 152                 printf("bpf_prog_load_xattr: %s\n", strerror(errno));
 153                 return 1;
 154         }
 155
 156         map = bpf_map__next(NULL, obj);
 157         if (!map) {
 158                 printf("finding a map in obj file failed\n");
 159                 return 1;
 160         }
 161         map_fd = bpf_map__fd(map);
 162
 163         if_idx = if_nametoindex(argv[optind]);
 164         if (!if_idx)
 165                 if_idx = strtoul(argv[optind], NULL, 0);
 166
 167         if (!if_idx) {
 168                 fprintf(stderr, "Invalid ifname\n");
 169                 return 1;
 170         }
 171         if_name = argv[optind];
 172         err = do_attach(if_idx, prog_fd, if_name);
 173         if (err)
 174                 return err;
 175
 176         if (signal(SIGINT, sig_handler) ||
 177             signal(SIGHUP, sig_handler) ||
 178             signal(SIGTERM, sig_handler)) {
 179                 perror("signal");
 180                 return 1;
 181         }
 182
 183         pb_opts.sample_cb = print_bpf_output;
 184         pb = perf_buffer__new(map_fd, 8, &pb_opts);
 185         err = libbpf_get_error(pb);
 186         if (err) {
 187                 perror("perf_buffer setup failed");
 188                 return 1;
 189         }
 190
 191         while ((ret = perf_buffer__poll(pb, 1000)) >= 0) {
 192         }
 193
 194         kill(0, SIGINT);
 195         return ret;
 196 }