LXR linux/samples/bpf/xdp_fwd

   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
  30static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
  31
  32static 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
  50static 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
  64static 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
  74int 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}
 171