samples/bpf/xdp_fwd_user.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (c) 2017-18 David Ahern <dsahern@gmail.com>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of version 2 of the GNU General Public
   6  * License as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11  * General Public License for more details.
  12  */
  13
  14 #include <linux/bpf.h>
  15 #include <linux/if_link.h>
  16 #include <linux/limits.h>
  17 #include <net/if.h>
  18 #include <errno.h>
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <stdbool.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24 #include <fcntl.h>
  25 #include <libgen.h>
  26
  27 #include "libbpf.h"
  28 #include <bpf/bpf.h>
  29
  30
  31 static int do_attach(int idx, int fd, const char *name)
  32 {
  33         int err;
  34
  35         err = bpf_set_link_xdp_fd(idx, fd, 0);
  36         if (err < 0)
  37                 printf("ERROR: failed to attach program to %s\n", name);
  38
  39         return err;
  40 }
  41
  42 static int do_detach(int idx, const char *name)
  43 {
  44         int err;
  45
  46         err = bpf_set_link_xdp_fd(idx, -1, 0);
  47         if (err < 0)
  48                 printf("ERROR: failed to detach program from %s\n", name);
  49
  50         return err;
  51 }
  52
  53 static void usage(const char *prog)
  54 {
  55         fprintf(stderr,
  56                 "usage: %s [OPTS] interface-list\n"
  57                 "\nOPTS:\n"
  58                 "    -d    detach program\n"
  59                 "    -D    direct table lookups (skip fib rules)\n",
  60                 prog);
  61 }
  62
  63 int main(int argc, char **argv)
  64 {
  65         struct bpf_prog_load_attr prog_load_attr = {
  66                 .prog_type      = BPF_PROG_TYPE_XDP,
  67         };
  68         const char *prog_name = "xdp_fwd";
  69         struct bpf_program *prog;
  70         char filename[PATH_MAX];
  71         struct bpf_object *obj;
  72         int opt, i, idx, err;
  73         int prog_fd, map_fd;
  74         int attach = 1;
  75         int ret = 0;
  76
  77         while ((opt = getopt(argc, argv, ":dD")) != -1) {
  78                 switch (opt) {
  79                 case 'd':
  80                         attach = 0;
  81                         break;
  82                 case 'D':
  83                         prog_name = "xdp_fwd_direct";
  84                         break;
  85                 default:
  86                         usage(basename(argv[0]));
  87                         return 1;
  88                 }
  89         }
  90
  91         if (optind == argc) {
  92                 usage(basename(argv[0]));
  93                 return 1;
  94         }
  95
  96         if (attach) {
  97                 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  98                 prog_load_attr.file = filename;
  99
 100                 if (access(filename, O_RDONLY) < 0) {
 101                         printf("error accessing file %s: %s\n",
 102                                 filename, strerror(errno));
 103                         return 1;
 104                 }
 105
 106                 if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
 107                         return 1;
 108
 109                 prog = bpf_object__find_program_by_title(obj, prog_name);
 110                 prog_fd = bpf_program__fd(prog);
 111                 if (prog_fd < 0) {
 112                         printf("program not found: %s\n", strerror(prog_fd));
 113                         return 1;
 114                 }
 115                 map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
 116                                                                   "tx_port"));
 117                 if (map_fd < 0) {
 118                         printf("map not found: %s\n", strerror(map_fd));
 119                         return 1;
 120                 }
 121         }
 122         if (attach) {
 123                 for (i = 1; i < 64; ++i)
 124                         bpf_map_update_elem(map_fd, &i, &i, 0);
 125         }
 126
 127         for (i = optind; i < argc; ++i) {
 128                 idx = if_nametoindex(argv[i]);
 129                 if (!idx)
 130                         idx = strtoul(argv[i], NULL, 0);
 131
 132                 if (!idx) {
 133                         fprintf(stderr, "Invalid arg\n");
 134                         return 1;
 135                 }
 136                 if (!attach) {
 137                         err = do_detach(idx, argv[i]);
 138                         if (err)
 139                                 ret = err;
 140                 } else {
 141                         err = do_attach(idx, prog_fd, argv[i]);
 142                         if (err)
 143                                 ret = err;
 144                 }
 145         }
 146
 147         return ret;
 148 }