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_xdp_attach(idx, prog_fd, xdp_flags, NULL);
  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 ifindex, const char *ifname, const char *app_name)
  51 {
  52         LIBBPF_OPTS(bpf_xdp_attach_opts, opts);
  53         struct bpf_prog_info prog_info = {};
  54         char prog_name[BPF_OBJ_NAME_LEN];
  55         __u32 info_len, curr_prog_id;
  56         int prog_fd;
  57         int err = 1;
  58
  59         if (bpf_xdp_query_id(ifindex, xdp_flags, &curr_prog_id)) {
  60                 printf("ERROR: bpf_xdp_query_id failed (%s)\n",
  61                        strerror(errno));
  62                 return err;
  63         }
  64
  65         if (!curr_prog_id) {
  66                 printf("ERROR: flags(0x%x) xdp prog is not attached to %s\n",
  67                        xdp_flags, ifname);
  68                 return err;
  69         }
  70
  71         info_len = sizeof(prog_info);
  72         prog_fd = bpf_prog_get_fd_by_id(curr_prog_id);
  73         if (prog_fd < 0) {
  74                 printf("ERROR: bpf_prog_get_fd_by_id failed (%s)\n",
  75                        strerror(errno));
  76                 return prog_fd;
  77         }
  78
  79         err = bpf_prog_get_info_by_fd(prog_fd, &prog_info, &info_len);
  80         if (err) {
  81                 printf("ERROR: bpf_prog_get_info_by_fd failed (%s)\n",
  82                        strerror(errno));
  83                 goto close_out;
  84         }
  85         snprintf(prog_name, sizeof(prog_name), "%s_prog", app_name);
  86         prog_name[BPF_OBJ_NAME_LEN - 1] = '\0';
  87
  88         if (strcmp(prog_info.name, prog_name)) {
  89                 printf("ERROR: %s isn't attached to %s\n", app_name, ifname);
  90                 err = 1;
  91                 goto close_out;
  92         }
  93
  94         opts.old_prog_fd = prog_fd;
  95         err = bpf_xdp_detach(ifindex, xdp_flags, &opts);
  96         if (err < 0)
  97                 printf("ERROR: failed to detach program from %s (%s)\n",
  98                        ifname, strerror(errno));
  99         /* TODO: Remember to cleanup map, when adding use of shared map
 100          *  bpf_map_delete_elem((map_fd, &idx);
 101          */
 102 close_out:
 103         close(prog_fd);
 104         return err;
 105 }
 106
 107 static void usage(const char *prog)
 108 {
 109         fprintf(stderr,
 110                 "usage: %s [OPTS] interface-list\n"
 111                 "\nOPTS:\n"
 112                 "    -d    detach program\n"
 113                 "    -S    use skb-mode\n"
 114                 "    -F    force loading prog\n"
 115                 "    -D    direct table lookups (skip fib rules)\n",
 116                 prog);
 117 }
 118
 119 int main(int argc, char **argv)
 120 {
 121         const char *prog_name = "xdp_fwd";
 122         struct bpf_program *prog = NULL;
 123         struct bpf_program *pos;
 124         const char *sec_name;
 125         int prog_fd = -1, map_fd = -1;
 126         char filename[PATH_MAX];
 127         struct bpf_object *obj;
 128         int opt, i, idx, err;
 129         int attach = 1;
 130         int ret = 0;
 131
 132         while ((opt = getopt(argc, argv, ":dDSF")) != -1) {
 133                 switch (opt) {
 134                 case 'd':
 135                         attach = 0;
 136                         break;
 137                 case 'S':
 138                         xdp_flags |= XDP_FLAGS_SKB_MODE;
 139                         break;
 140                 case 'F':
 141                         xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
 142                         break;
 143                 case 'D':
 144                         prog_name = "xdp_fwd_direct";
 145                         break;
 146                 default:
 147                         usage(basename(argv[0]));
 148                         return 1;
 149                 }
 150         }
 151
 152         if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
 153                 xdp_flags |= XDP_FLAGS_DRV_MODE;
 154
 155         if (optind == argc) {
 156                 usage(basename(argv[0]));
 157                 return 1;
 158         }
 159
 160         if (attach) {
 161                 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
 162
 163                 if (access(filename, O_RDONLY) < 0) {
 164                         printf("error accessing file %s: %s\n",
 165                                 filename, strerror(errno));
 166                         return 1;
 167                 }
 168
 169                 obj = bpf_object__open_file(filename, NULL);
 170                 if (libbpf_get_error(obj))
 171                         return 1;
 172
 173                 prog = bpf_object__next_program(obj, NULL);
 174                 bpf_program__set_type(prog, BPF_PROG_TYPE_XDP);
 175
 176                 err = bpf_object__load(obj);
 177                 if (err) {
 178                         printf("Does kernel support devmap lookup?\n");
 179                         /* If not, the error message will be:
 180                          *  "cannot pass map_type 14 into func bpf_map_lookup_elem#1"
 181                          */
 182                         return 1;
 183                 }
 184
 185                 bpf_object__for_each_program(pos, obj) {
 186                         sec_name = bpf_program__section_name(pos);
 187                         if (sec_name && !strcmp(sec_name, prog_name)) {
 188                                 prog = pos;
 189                                 break;
 190                         }
 191                 }
 192                 prog_fd = bpf_program__fd(prog);
 193                 if (prog_fd < 0) {
 194                         printf("program not found: %s\n", strerror(prog_fd));
 195                         return 1;
 196                 }
 197                 map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
 198                                                         "xdp_tx_ports"));
 199                 if (map_fd < 0) {
 200                         printf("map not found: %s\n", strerror(map_fd));
 201                         return 1;
 202                 }
 203         }
 204
 205         for (i = optind; i < argc; ++i) {
 206                 idx = if_nametoindex(argv[i]);
 207                 if (!idx)
 208                         idx = strtoul(argv[i], NULL, 0);
 209
 210                 if (!idx) {
 211                         fprintf(stderr, "Invalid arg\n");
 212                         return 1;
 213                 }
 214                 if (!attach) {
 215                         err = do_detach(idx, argv[i], prog_name);
 216                         if (err)
 217                                 ret = err;
 218                 } else {
 219                         err = do_attach(idx, prog_fd, map_fd, argv[i]);
 220                         if (err)
 221                                 ret = err;
 222                 }
 223         }
 224
 225         return ret;
 226 }