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                "    -S    use skb-mode\n"
  71                "    -F    force loading prog\n"
  72                "    -D    direct table lookups (skip fib rules)\n",
  73                prog);
  74}
  75
  76int main(int argc, char **argv)
  77{
  78        struct bpf_prog_load_attr prog_load_attr = {
  79                .prog_type      = BPF_PROG_TYPE_XDP,
  80        };
  81        const char *prog_name = "xdp_fwd";
  82        struct bpf_program *prog;
  83        int prog_fd, map_fd = -1;
  84        char filename[PATH_MAX];
  85        struct bpf_object *obj;
  86        int opt, i, idx, err;
  87        int attach = 1;
  88        int ret = 0;
  89
  90        while ((opt = getopt(argc, argv, ":dDSF")) != -1) {
  91                switch (opt) {
  92                case 'd':
  93                        attach = 0;
  94                        break;
  95                case 'S':
  96                        xdp_flags |= XDP_FLAGS_SKB_MODE;
  97                        break;
  98                case 'F':
  99                        xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
 100                        break;
 101                case 'D':
 102                        prog_name = "xdp_fwd_direct";
 103                        break;
 104                default:
 105                        usage(basename(argv[0]));
 106                        return 1;
 107                }
 108        }
 109
 110        if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
 111                xdp_flags |= XDP_FLAGS_DRV_MODE;
 112
 113        if (optind == argc) {
 114                usage(basename(argv[0]));
 115                return 1;
 116        }
 117
 118        if (attach) {
 119                snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 120                prog_load_attr.file = filename;
 121
 122                if (access(filename, O_RDONLY) < 0) {
 123                        printf("error accessing file %s: %s\n",
 124                                filename, strerror(errno));
 125                        return 1;
 126                }
 127
 128                err = bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd);
 129                if (err) {
 130                        printf("Does kernel support devmap lookup?\n");
 131                        /* If not, the error message will be:
 132                         *  "cannot pass map_type 14 into func bpf_map_lookup_elem#1"
 133                         */
 134                        return 1;
 135                }
 136
 137                prog = bpf_object__find_program_by_title(obj, prog_name);
 138                prog_fd = bpf_program__fd(prog);
 139                if (prog_fd < 0) {
 140                        printf("program not found: %s\n", strerror(prog_fd));
 141                        return 1;
 142                }
 143                map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
 144                                                        "xdp_tx_ports"));
 145                if (map_fd < 0) {
 146                        printf("map not found: %s\n", strerror(map_fd));
 147                        return 1;
 148                }
 149        }
 150
 151        for (i = optind; i < argc; ++i) {
 152                idx = if_nametoindex(argv[i]);
 153                if (!idx)
 154                        idx = strtoul(argv[i], NULL, 0);
 155
 156                if (!idx) {
 157                        fprintf(stderr, "Invalid arg\n");
 158                        return 1;
 159                }
 160                if (!attach) {
 161                        err = do_detach(idx, argv[i]);
 162                        if (err)
 163                                ret = err;
 164                } else {
 165                        err = do_attach(idx, prog_fd, map_fd, argv[i]);
 166                        if (err)
 167                                ret = err;
 168                }
 169        }
 170
 171        return ret;
 172}
 173