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 #define MAX_CPUS 128
  22 static int if_idx;
  23 static char *if_name;
  24 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
  25 static __u32 prog_id;
  26 static struct perf_buffer *pb = NULL;
  27
  28 static int do_attach(int idx, int fd, const char *name)
  29 {
  30         struct bpf_prog_info info = {};
  31         __u32 info_len = sizeof(info);
  32         int err;
  33
  34         err = bpf_set_link_xdp_fd(idx, fd, xdp_flags);
  35         if (err < 0) {
  36                 printf("ERROR: failed to attach program to %s\n", name);
  37                 return err;
  38         }
  39
  40         err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
  41         if (err) {
  42                 printf("can't get prog info - %s\n", strerror(errno));
  43                 return err;
  44         }
  45         prog_id = info.id;
  46
  47         return err;
  48 }
  49
  50 static int do_detach(int idx, const char *name)
  51 {
  52         __u32 curr_prog_id = 0;
  53         int err = 0;
  54
  55         err = bpf_get_link_xdp_id(idx, &curr_prog_id, xdp_flags);
  56         if (err) {
  57                 printf("bpf_get_link_xdp_id failed\n");
  58                 return err;
  59         }
  60         if (prog_id == curr_prog_id) {
  61                 err = bpf_set_link_xdp_fd(idx, -1, xdp_flags);
  62                 if (err < 0)
  63                         printf("ERROR: failed to detach prog from %s\n", name);
  64         } else if (!curr_prog_id) {
  65                 printf("couldn't find a prog id on a %s\n", name);
  66         } else {
  67                 printf("program on interface changed, not removing\n");
  68         }
  69
  70         return err;
  71 }
  72
  73 #define SAMPLE_SIZE 64
  74
  75 static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size)
  76 {
  77         struct {
  78                 __u16 cookie;
  79                 __u16 pkt_len;
  80                 __u8  pkt_data[SAMPLE_SIZE];
  81         } __packed *e = data;
  82         int i;
  83
  84         if (e->cookie != 0xdead) {
  85                 printf("BUG cookie %x sized %d\n", e->cookie, size);
  86                 return;
  87         }
  88
  89         printf("Pkt len: %-5d bytes. Ethernet hdr: ", e->pkt_len);
  90         for (i = 0; i < 14 && i < e->pkt_len; i++)
  91                 printf("%02x ", e->pkt_data[i]);
  92         printf("\n");
  93 }
  94
  95 static void sig_handler(int signo)
  96 {
  97         do_detach(if_idx, if_name);
  98         perf_buffer__free(pb);
  99         exit(0);
 100 }
 101
 102 static void usage(const char *prog)
 103 {
 104         fprintf(stderr,
 105                 "%s: %s [OPTS] <ifname|ifindex>\n\n"
 106                 "OPTS:\n"
 107                 "    -F    force loading prog\n",
 108                 __func__, prog);
 109 }
 110
 111 int main(int argc, char **argv)
 112 {
 113         struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
 114         struct bpf_prog_load_attr prog_load_attr = {
 115                 .prog_type      = BPF_PROG_TYPE_XDP,
 116         };
 117         struct perf_buffer_opts pb_opts = {};
 118         const char *optstr = "FS";
 119         int prog_fd, map_fd, opt;
 120         struct bpf_object *obj;
 121         struct bpf_map *map;
 122         char filename[256];
 123         int ret, err;
 124
 125         while ((opt = getopt(argc, argv, optstr)) != -1) {
 126                 switch (opt) {
 127                 case 'F':
 128                         xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
 129                         break;
 130                 case 'S':
 131                         xdp_flags |= XDP_FLAGS_SKB_MODE;
 132                         break;
 133                 default:
 134                         usage(basename(argv[0]));
 135                         return 1;
 136                 }
 137         }
 138
 139         if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
 140                 xdp_flags |= XDP_FLAGS_DRV_MODE;
 141
 142         if (optind == argc) {
 143                 usage(basename(argv[0]));
 144                 return 1;
 145         }
 146
 147         if (setrlimit(RLIMIT_MEMLOCK, &r)) {
 148                 perror("setrlimit(RLIMIT_MEMLOCK)");
 149                 return 1;
 150         }
 151
 152         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 153         prog_load_attr.file = filename;
 154
 155         if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
 156                 return 1;
 157
 158         if (!prog_fd) {
 159                 printf("bpf_prog_load_xattr: %s\n", strerror(errno));
 160                 return 1;
 161         }
 162
 163         map = bpf_map__next(NULL, obj);
 164         if (!map) {
 165                 printf("finding a map in obj file failed\n");
 166                 return 1;
 167         }
 168         map_fd = bpf_map__fd(map);
 169
 170         if_idx = if_nametoindex(argv[optind]);
 171         if (!if_idx)
 172                 if_idx = strtoul(argv[optind], NULL, 0);
 173
 174         if (!if_idx) {
 175                 fprintf(stderr, "Invalid ifname\n");
 176                 return 1;
 177         }
 178         if_name = argv[optind];
 179         err = do_attach(if_idx, prog_fd, if_name);
 180         if (err)
 181                 return err;
 182
 183         if (signal(SIGINT, sig_handler) ||
 184             signal(SIGHUP, sig_handler) ||
 185             signal(SIGTERM, sig_handler)) {
 186                 perror("signal");
 187                 return 1;
 188         }
 189
 190         pb_opts.sample_cb = print_bpf_output;
 191         pb = perf_buffer__new(map_fd, 8, &pb_opts);
 192         err = libbpf_get_error(pb);
 193         if (err) {
 194                 perror("perf_buffer setup failed");
 195                 return 1;
 196         }
 197
 198         while ((ret = perf_buffer__poll(pb, 1000)) >= 0) {
 199         }
 200
 201         kill(0, SIGINT);
 202         return ret;
 203 }