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 <bpf/libbpf.h>
  28 #include <bpf/bpf.h>
  29
  30 static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
  31
  32 static int do_attach(int idx, int prog_fd, int map_fd, const char *name)
  33 {
  34         int err;
  35
  36         err = bpf_set_link_xdp_fd(idx, prog_fd, xdp_flags);
  37         if (err < 0) {
  38                 printf("ERROR: failed to attach program to %s\n", name);
  39                 return err;
  40         }
  41
  42         /* Adding ifindex as a possible egress TX port */
  43         err = bpf_map_update_elem(map_fd, &idx, &idx, 0);
  44         if (err)
  45                 printf("ERROR: failed using device %s as TX-port\n", name);
  46
  47         return err;
  48 }
  49
  50 static int do_detach(int idx, const char *name)
  51 {
  52         int err;
  53
  54         err = bpf_set_link_xdp_fd(idx, -1, xdp_flags);
  55         if (err < 0)
  56                 printf("ERROR: failed to detach program from %s\n", name);
  57
  58         /* TODO: Remember to cleanup map, when adding use of shared map
  59          *  bpf_map_delete_elem((map_fd, &idx);
  60          */
  61         return err;
  62 }
  63
  64 static void usage(const char *prog)
  65 {
  66         fprintf(stderr,
  67                 "usage: %s [OPTS] interface-list\n"
  68                 "\nOPTS:\n"
  69                 "    -d    detach program\n"
  70                 "    -D    direct table lookups (skip fib rules)\n",
  71                 prog);
  72 }
  73
  74 int main(int argc, char **argv)
  75 {
  76         struct bpf_prog_load_attr prog_load_attr = {
  77                 .prog_type      = BPF_PROG_TYPE_XDP,
  78         };
  79         const char *prog_name = "xdp_fwd";
  80         struct bpf_program *prog;
  81         int prog_fd, map_fd = -1;
  82         char filename[PATH_MAX];
  83         struct bpf_object *obj;
  84         int opt, i, idx, err;
  85         int attach = 1;
  86         int ret = 0;
  87
  88         while ((opt = getopt(argc, argv, ":dDSF")) != -1) {
  89                 switch (opt) {
  90                 case 'd':
  91                         attach = 0;
  92                         break;
  93                 case 'S':
  94                         xdp_flags |= XDP_FLAGS_SKB_MODE;
  95                         break;
  96                 case 'F':
  97                         xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
  98                         break;
  99                 case 'D':
 100                         prog_name = "xdp_fwd_direct";
 101                         break;
 102                 default:
 103                         usage(basename(argv[0]));
 104                         return 1;
 105                 }
 106         }
 107
 108         if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
 109                 xdp_flags |= XDP_FLAGS_DRV_MODE;
 110
 111         if (optind == argc) {
 112                 usage(basename(argv[0]));
 113                 return 1;
 114         }
 115
 116         if (attach) {
 117                 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 118                 prog_load_attr.file = filename;
 119
 120                 if (access(filename, O_RDONLY) < 0) {
 121                         printf("error accessing file %s: %s\n",
 122                                 filename, strerror(errno));
 123                         return 1;
 124                 }
 125
 126                 err = bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd);
 127                 if (err) {
 128                         printf("Does kernel support devmap lookup?\n");
 129                         /* If not, the error message will be:
 130                          *  "cannot pass map_type 14 into func bpf_map_lookup_elem#1"
 131                          */
 132                         return 1;
 133                 }
 134
 135                 prog = bpf_object__find_program_by_title(obj, prog_name);
 136                 prog_fd = bpf_program__fd(prog);
 137                 if (prog_fd < 0) {
 138                         printf("program not found: %s\n", strerror(prog_fd));
 139                         return 1;
 140                 }
 141                 map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
 142                                                         "xdp_tx_ports"));
 143                 if (map_fd < 0) {
 144                         printf("map not found: %s\n", strerror(map_fd));
 145                         return 1;
 146                 }
 147         }
 148
 149         for (i = optind; i < argc; ++i) {
 150                 idx = if_nametoindex(argv[i]);
 151                 if (!idx)
 152                         idx = strtoul(argv[i], NULL, 0);
 153
 154                 if (!idx) {
 155                         fprintf(stderr, "Invalid arg\n");
 156                         return 1;
 157                 }
 158                 if (!attach) {
 159                         err = do_detach(idx, argv[i]);
 160                         if (err)
 161                                 ret = err;
 162                 } else {
 163                         err = do_attach(idx, prog_fd, map_fd, argv[i]);
 164                         if (err)
 165                                 ret = err;
 166                 }
 167         }
 168
 169         return ret;
 170 }