net/batman-adv/hard-interface.c

   1 /*
   2  * Copyright (C) 2007-2011 B.A.T.M.A.N. contributors:
   3  *
   4  * Marek Lindner, Simon Wunderlich
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of version 2 of the GNU General Public
   8  * License as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301, USA
  19  *
  20  */
  21
  22 #include "main.h"
  23 #include "hard-interface.h"
  24 #include "soft-interface.h"
  25 #include "send.h"
  26 #include "translation-table.h"
  27 #include "routing.h"
  28 #include "bat_sysfs.h"
  29 #include "originator.h"
  30 #include "hash.h"
  31
  32 #include <linux/if_arp.h>
  33
  34
  35 static int batman_skb_recv(struct sk_buff *skb,
  36                            struct net_device *dev,
  37                            struct packet_type *ptype,
  38                            struct net_device *orig_dev);
  39
  40 void hardif_free_rcu(struct rcu_head *rcu)
  41 {
  42         struct hard_iface *hard_iface;
  43
  44         hard_iface = container_of(rcu, struct hard_iface, rcu);
  45         dev_put(hard_iface->net_dev);
  46         kfree(hard_iface);
  47 }
  48
  49 struct hard_iface *hardif_get_by_netdev(const struct net_device *net_dev)
  50 {
  51         struct hard_iface *hard_iface;
  52
  53         rcu_read_lock();
  54         list_for_each_entry_rcu(hard_iface, &hardif_list, list) {
  55                 if (hard_iface->net_dev == net_dev &&
  56                     atomic_inc_not_zero(&hard_iface->refcount))
  57                         goto out;
  58         }
  59
  60         hard_iface = NULL;
  61
  62 out:
  63         rcu_read_unlock();
  64         return hard_iface;
  65 }
  66
  67 static int is_valid_iface(const struct net_device *net_dev)
  68 {
  69         if (net_dev->flags & IFF_LOOPBACK)
  70                 return 0;
  71
  72         if (net_dev->type != ARPHRD_ETHER)
  73                 return 0;
  74
  75         if (net_dev->addr_len != ETH_ALEN)
  76                 return 0;
  77
  78         /* no batman over batman */
  79         if (softif_is_valid(net_dev))
  80                 return 0;
  81
  82         /* Device is being bridged */
  83         /* if (net_dev->priv_flags & IFF_BRIDGE_PORT)
  84                 return 0; */
  85
  86         return 1;
  87 }
  88
  89 static struct hard_iface *hardif_get_active(const struct net_device *soft_iface)
  90 {
  91         struct hard_iface *hard_iface;
  92
  93         rcu_read_lock();
  94         list_for_each_entry_rcu(hard_iface, &hardif_list, list) {
  95                 if (hard_iface->soft_iface != soft_iface)
  96                         continue;
  97
  98                 if (hard_iface->if_status == IF_ACTIVE &&
  99                     atomic_inc_not_zero(&hard_iface->refcount))
 100                         goto out;
 101         }
 102
 103         hard_iface = NULL;
 104
 105 out:
 106         rcu_read_unlock();
 107         return hard_iface;
 108 }
 109
 110 static void primary_if_update_addr(struct bat_priv *bat_priv)
 111 {
 112         struct vis_packet *vis_packet;
 113         struct hard_iface *primary_if;
 114
 115         primary_if = primary_if_get_selected(bat_priv);
 116         if (!primary_if)
 117                 goto out;
 118
 119         vis_packet = (struct vis_packet *)
 120                                 bat_priv->my_vis_info->skb_packet->data;
 121         memcpy(vis_packet->vis_orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 122         memcpy(vis_packet->sender_orig,
 123                primary_if->net_dev->dev_addr, ETH_ALEN);
 124
 125 out:
 126         if (primary_if)
 127                 hardif_free_ref(primary_if);
 128 }
 129
 130 static void primary_if_select(struct bat_priv *bat_priv,
 131                               struct hard_iface *new_hard_iface)
 132 {
 133         struct hard_iface *curr_hard_iface;
 134         struct batman_packet *batman_packet;
 135
 136         ASSERT_RTNL();
 137
 138         if (new_hard_iface && !atomic_inc_not_zero(&new_hard_iface->refcount))
 139                 new_hard_iface = NULL;
 140
 141         curr_hard_iface = rcu_dereference_protected(bat_priv->primary_if, 1);
 142         rcu_assign_pointer(bat_priv->primary_if, new_hard_iface);
 143
 144         if (curr_hard_iface)
 145                 hardif_free_ref(curr_hard_iface);
 146
 147         if (!new_hard_iface)
 148                 return;
 149
 150         batman_packet = (struct batman_packet *)(new_hard_iface->packet_buff);
 151         batman_packet->flags = PRIMARIES_FIRST_HOP;
 152         batman_packet->ttl = TTL;
 153
 154         primary_if_update_addr(bat_priv);
 155
 156         /***
 157          * hacky trick to make sure that we send the TT information via
 158          * our new primary interface
 159          */
 160         atomic_set(&bat_priv->tt_local_changed, 1);
 161 }
 162
 163 static bool hardif_is_iface_up(const struct hard_iface *hard_iface)
 164 {
 165         if (hard_iface->net_dev->flags & IFF_UP)
 166                 return true;
 167
 168         return false;
 169 }
 170
 171 static void update_mac_addresses(struct hard_iface *hard_iface)
 172 {
 173         memcpy(((struct batman_packet *)(hard_iface->packet_buff))->orig,
 174                hard_iface->net_dev->dev_addr, ETH_ALEN);
 175         memcpy(((struct batman_packet *)(hard_iface->packet_buff))->prev_sender,
 176                hard_iface->net_dev->dev_addr, ETH_ALEN);
 177 }
 178
 179 static void check_known_mac_addr(const struct net_device *net_dev)
 180 {
 181         const struct hard_iface *hard_iface;
 182
 183         rcu_read_lock();
 184         list_for_each_entry_rcu(hard_iface, &hardif_list, list) {
 185                 if ((hard_iface->if_status != IF_ACTIVE) &&
 186                     (hard_iface->if_status != IF_TO_BE_ACTIVATED))
 187                         continue;
 188
 189                 if (hard_iface->net_dev == net_dev)
 190                         continue;
 191
 192                 if (!compare_eth(hard_iface->net_dev->dev_addr,
 193                                  net_dev->dev_addr))
 194                         continue;
 195
 196                 pr_warning("The newly added mac address (%pM) already exists "
 197                            "on: %s\n", net_dev->dev_addr,
 198                            hard_iface->net_dev->name);
 199                 pr_warning("It is strongly recommended to keep mac addresses "
 200                            "unique to avoid problems!\n");
 201         }
 202         rcu_read_unlock();
 203 }
 204
 205 int hardif_min_mtu(struct net_device *soft_iface)
 206 {
 207         const struct bat_priv *bat_priv = netdev_priv(soft_iface);
 208         const struct hard_iface *hard_iface;
 209         /* allow big frames if all devices are capable to do so
 210          * (have MTU > 1500 + BAT_HEADER_LEN) */
 211         int min_mtu = ETH_DATA_LEN;
 212
 213         if (atomic_read(&bat_priv->fragmentation))
 214                 goto out;
 215
 216         rcu_read_lock();
 217         list_for_each_entry_rcu(hard_iface, &hardif_list, list) {
 218                 if ((hard_iface->if_status != IF_ACTIVE) &&
 219                     (hard_iface->if_status != IF_TO_BE_ACTIVATED))
 220                         continue;
 221
 222                 if (hard_iface->soft_iface != soft_iface)
 223                         continue;
 224
 225                 min_mtu = min_t(int, hard_iface->net_dev->mtu - BAT_HEADER_LEN,
 226                                 min_mtu);
 227         }
 228         rcu_read_unlock();
 229 out:
 230         return min_mtu;
 231 }
 232
 233 /* adjusts the MTU if a new interface with a smaller MTU appeared. */
 234 void update_min_mtu(struct net_device *soft_iface)
 235 {
 236         int min_mtu;
 237
 238         min_mtu = hardif_min_mtu(soft_iface);
 239         if (soft_iface->mtu != min_mtu)
 240                 soft_iface->mtu = min_mtu;
 241 }
 242
 243 static void hardif_activate_interface(struct hard_iface *hard_iface)
 244 {
 245         struct bat_priv *bat_priv;
 246         struct hard_iface *primary_if = NULL;
 247
 248         if (hard_iface->if_status != IF_INACTIVE)
 249                 goto out;
 250
 251         bat_priv = netdev_priv(hard_iface->soft_iface);
 252
 253         update_mac_addresses(hard_iface);
 254         hard_iface->if_status = IF_TO_BE_ACTIVATED;
 255
 256         /**
 257          * the first active interface becomes our primary interface or
 258          * the next active interface after the old primay interface was removed
 259          */
 260         primary_if = primary_if_get_selected(bat_priv);
 261         if (!primary_if)
 262                 primary_if_select(bat_priv, hard_iface);
 263
 264         bat_info(hard_iface->soft_iface, "Interface activated: %s\n",
 265                  hard_iface->net_dev->name);
 266
 267         update_min_mtu(hard_iface->soft_iface);
 268
 269 out:
 270         if (primary_if)
 271                 hardif_free_ref(primary_if);
 272 }
 273
 274 static void hardif_deactivate_interface(struct hard_iface *hard_iface)
 275 {
 276         if ((hard_iface->if_status != IF_ACTIVE) &&
 277             (hard_iface->if_status != IF_TO_BE_ACTIVATED))
 278                 return;
 279
 280         hard_iface->if_status = IF_INACTIVE;
 281
 282         bat_info(hard_iface->soft_iface, "Interface deactivated: %s\n",
 283                  hard_iface->net_dev->name);
 284
 285         update_min_mtu(hard_iface->soft_iface);
 286 }
 287
 288 int hardif_enable_interface(struct hard_iface *hard_iface,
 289                             const char *iface_name)
 290 {
 291         struct bat_priv *bat_priv;
 292         struct batman_packet *batman_packet;
 293         struct net_device *soft_iface;
 294         int ret;
 295
 296         if (hard_iface->if_status != IF_NOT_IN_USE)
 297                 goto out;
 298
 299         if (!atomic_inc_not_zero(&hard_iface->refcount))
 300                 goto out;
 301
 302         soft_iface = dev_get_by_name(&init_net, iface_name);
 303
 304         if (!soft_iface) {
 305                 soft_iface = softif_create(iface_name);
 306
 307                 if (!soft_iface) {
 308                         ret = -ENOMEM;
 309                         goto err;
 310                 }
 311
 312                 /* dev_get_by_name() increases the reference counter for us */
 313                 dev_hold(soft_iface);
 314         }
 315
 316         if (!softif_is_valid(soft_iface)) {
 317                 pr_err("Can't create batman mesh interface %s: "
 318                        "already exists as regular interface\n",
 319                        soft_iface->name);
 320                 dev_put(soft_iface);
 321                 ret = -EINVAL;
 322                 goto err;
 323         }
 324
 325         hard_iface->soft_iface = soft_iface;
 326         bat_priv = netdev_priv(hard_iface->soft_iface);
 327         hard_iface->packet_len = BAT_PACKET_LEN;
 328         hard_iface->packet_buff = kmalloc(hard_iface->packet_len, GFP_ATOMIC);
 329
 330         if (!hard_iface->packet_buff) {
 331                 bat_err(hard_iface->soft_iface, "Can't add interface packet "
 332                         "(%s): out of memory\n", hard_iface->net_dev->name);
 333                 ret = -ENOMEM;
 334                 goto err;
 335         }
 336
 337         batman_packet = (struct batman_packet *)(hard_iface->packet_buff);
 338         batman_packet->packet_type = BAT_PACKET;
 339         batman_packet->version = COMPAT_VERSION;
 340         batman_packet->flags = NO_FLAGS;
 341         batman_packet->ttl = 2;
 342         batman_packet->tq = TQ_MAX_VALUE;
 343         batman_packet->num_tt = 0;
 344
 345         hard_iface->if_num = bat_priv->num_ifaces;
 346         bat_priv->num_ifaces++;
 347         hard_iface->if_status = IF_INACTIVE;
 348         orig_hash_add_if(hard_iface, bat_priv->num_ifaces);
 349
 350         hard_iface->batman_adv_ptype.type = __constant_htons(ETH_P_BATMAN);
 351         hard_iface->batman_adv_ptype.func = batman_skb_recv;
 352         hard_iface->batman_adv_ptype.dev = hard_iface->net_dev;
 353         dev_add_pack(&hard_iface->batman_adv_ptype);
 354
 355         atomic_set(&hard_iface->seqno, 1);
 356         atomic_set(&hard_iface->frag_seqno, 1);
 357         bat_info(hard_iface->soft_iface, "Adding interface: %s\n",
 358                  hard_iface->net_dev->name);
 359
 360         if (atomic_read(&bat_priv->fragmentation) && hard_iface->net_dev->mtu <
 361                 ETH_DATA_LEN + BAT_HEADER_LEN)
 362                 bat_info(hard_iface->soft_iface,
 363                         "The MTU of interface %s is too small (%i) to handle "
 364                         "the transport of batman-adv packets. Packets going "
 365                         "over this interface will be fragmented on layer2 "
 366                         "which could impact the performance. Setting the MTU "
 367                         "to %zi would solve the problem.\n",
 368                         hard_iface->net_dev->name, hard_iface->net_dev->mtu,
 369                         ETH_DATA_LEN + BAT_HEADER_LEN);
 370
 371         if (!atomic_read(&bat_priv->fragmentation) && hard_iface->net_dev->mtu <
 372                 ETH_DATA_LEN + BAT_HEADER_LEN)
 373                 bat_info(hard_iface->soft_iface,
 374                         "The MTU of interface %s is too small (%i) to handle "
 375                         "the transport of batman-adv packets. If you experience"
 376                         " problems getting traffic through try increasing the "
 377                         "MTU to %zi.\n",
 378                         hard_iface->net_dev->name, hard_iface->net_dev->mtu,
 379                         ETH_DATA_LEN + BAT_HEADER_LEN);
 380
 381         if (hardif_is_iface_up(hard_iface))
 382                 hardif_activate_interface(hard_iface);
 383         else
 384                 bat_err(hard_iface->soft_iface, "Not using interface %s "
 385                         "(retrying later): interface not active\n",
 386                         hard_iface->net_dev->name);
 387
 388         /* begin scheduling originator messages on that interface */
 389         schedule_own_packet(hard_iface);
 390
 391 out:
 392         return 0;
 393
 394 err:
 395         hardif_free_ref(hard_iface);
 396         return ret;
 397 }
 398
 399 void hardif_disable_interface(struct hard_iface *hard_iface)
 400 {
 401         struct bat_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
 402         struct hard_iface *primary_if = NULL;
 403
 404         if (hard_iface->if_status == IF_ACTIVE)
 405                 hardif_deactivate_interface(hard_iface);
 406
 407         if (hard_iface->if_status != IF_INACTIVE)
 408                 goto out;
 409
 410         bat_info(hard_iface->soft_iface, "Removing interface: %s\n",
 411                  hard_iface->net_dev->name);
 412         dev_remove_pack(&hard_iface->batman_adv_ptype);
 413
 414         bat_priv->num_ifaces--;
 415         orig_hash_del_if(hard_iface, bat_priv->num_ifaces);
 416
 417         primary_if = primary_if_get_selected(bat_priv);
 418         if (hard_iface == primary_if) {
 419                 struct hard_iface *new_if;
 420
 421                 new_if = hardif_get_active(hard_iface->soft_iface);
 422                 primary_if_select(bat_priv, new_if);
 423
 424                 if (new_if)
 425                         hardif_free_ref(new_if);
 426         }
 427
 428         kfree(hard_iface->packet_buff);
 429         hard_iface->packet_buff = NULL;
 430         hard_iface->if_status = IF_NOT_IN_USE;
 431
 432         /* delete all references to this hard_iface */
 433         purge_orig_ref(bat_priv);
 434         purge_outstanding_packets(bat_priv, hard_iface);
 435         dev_put(hard_iface->soft_iface);
 436
 437         /* nobody uses this interface anymore */
 438         if (!bat_priv->num_ifaces)
 439                 softif_destroy(hard_iface->soft_iface);
 440
 441         hard_iface->soft_iface = NULL;
 442         hardif_free_ref(hard_iface);
 443
 444 out:
 445         if (primary_if)
 446                 hardif_free_ref(primary_if);
 447 }
 448
 449 static struct hard_iface *hardif_add_interface(struct net_device *net_dev)
 450 {
 451         struct hard_iface *hard_iface;
 452         int ret;
 453
 454         ASSERT_RTNL();
 455
 456         ret = is_valid_iface(net_dev);
 457         if (ret != 1)
 458                 goto out;
 459
 460         dev_hold(net_dev);
 461
 462         hard_iface = kmalloc(sizeof(*hard_iface), GFP_ATOMIC);
 463         if (!hard_iface) {
 464                 pr_err("Can't add interface (%s): out of memory\n",
 465                        net_dev->name);
 466                 goto release_dev;
 467         }
 468
 469         ret = sysfs_add_hardif(&hard_iface->hardif_obj, net_dev);
 470         if (ret)
 471                 goto free_if;
 472
 473         hard_iface->if_num = -1;
 474         hard_iface->net_dev = net_dev;
 475         hard_iface->soft_iface = NULL;
 476         hard_iface->if_status = IF_NOT_IN_USE;
 477         INIT_LIST_HEAD(&hard_iface->list);
 478         /* extra reference for return */
 479         atomic_set(&hard_iface->refcount, 2);
 480
 481         check_known_mac_addr(hard_iface->net_dev);
 482         list_add_tail_rcu(&hard_iface->list, &hardif_list);
 483
 484         return hard_iface;
 485
 486 free_if:
 487         kfree(hard_iface);
 488 release_dev:
 489         dev_put(net_dev);
 490 out:
 491         return NULL;
 492 }
 493
 494 static void hardif_remove_interface(struct hard_iface *hard_iface)
 495 {
 496         ASSERT_RTNL();
 497
 498         /* first deactivate interface */
 499         if (hard_iface->if_status != IF_NOT_IN_USE)
 500                 hardif_disable_interface(hard_iface);
 501
 502         if (hard_iface->if_status != IF_NOT_IN_USE)
 503                 return;
 504
 505         hard_iface->if_status = IF_TO_BE_REMOVED;
 506         sysfs_del_hardif(&hard_iface->hardif_obj);
 507         hardif_free_ref(hard_iface);
 508 }
 509
 510 void hardif_remove_interfaces(void)
 511 {
 512         struct hard_iface *hard_iface, *hard_iface_tmp;
 513
 514         rtnl_lock();
 515         list_for_each_entry_safe(hard_iface, hard_iface_tmp,
 516                                  &hardif_list, list) {
 517                 list_del_rcu(&hard_iface->list);
 518                 hardif_remove_interface(hard_iface);
 519         }
 520         rtnl_unlock();
 521 }
 522
 523 static int hard_if_event(struct notifier_block *this,
 524                          unsigned long event, void *ptr)
 525 {
 526         struct net_device *net_dev = ptr;
 527         struct hard_iface *hard_iface = hardif_get_by_netdev(net_dev);
 528         struct hard_iface *primary_if = NULL;
 529         struct bat_priv *bat_priv;
 530
 531         if (!hard_iface && event == NETDEV_REGISTER)
 532                 hard_iface = hardif_add_interface(net_dev);
 533
 534         if (!hard_iface)
 535                 goto out;
 536
 537         switch (event) {
 538         case NETDEV_UP:
 539                 hardif_activate_interface(hard_iface);
 540                 break;
 541         case NETDEV_GOING_DOWN:
 542         case NETDEV_DOWN:
 543                 hardif_deactivate_interface(hard_iface);
 544                 break;
 545         case NETDEV_UNREGISTER:
 546                 list_del_rcu(&hard_iface->list);
 547
 548                 hardif_remove_interface(hard_iface);
 549                 break;
 550         case NETDEV_CHANGEMTU:
 551                 if (hard_iface->soft_iface)
 552                         update_min_mtu(hard_iface->soft_iface);
 553                 break;
 554         case NETDEV_CHANGEADDR:
 555                 if (hard_iface->if_status == IF_NOT_IN_USE)
 556                         goto hardif_put;
 557
 558                 check_known_mac_addr(hard_iface->net_dev);
 559                 update_mac_addresses(hard_iface);
 560
 561                 bat_priv = netdev_priv(hard_iface->soft_iface);
 562                 primary_if = primary_if_get_selected(bat_priv);
 563                 if (!primary_if)
 564                         goto hardif_put;
 565
 566                 if (hard_iface == primary_if)
 567                         primary_if_update_addr(bat_priv);
 568                 break;
 569         default:
 570                 break;
 571         }
 572
 573 hardif_put:
 574         hardif_free_ref(hard_iface);
 575 out:
 576         if (primary_if)
 577                 hardif_free_ref(primary_if);
 578         return NOTIFY_DONE;
 579 }
 580
 581 /* receive a packet with the batman ethertype coming on a hard
 582  * interface */
 583 static int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
 584                            struct packet_type *ptype,
 585                            struct net_device *orig_dev)
 586 {
 587         struct bat_priv *bat_priv;
 588         struct batman_packet *batman_packet;
 589         struct hard_iface *hard_iface;
 590         int ret;
 591
 592         hard_iface = container_of(ptype, struct hard_iface, batman_adv_ptype);
 593         skb = skb_share_check(skb, GFP_ATOMIC);
 594
 595         /* skb was released by skb_share_check() */
 596         if (!skb)
 597                 goto err_out;
 598
 599         /* packet should hold at least type and version */
 600         if (unlikely(!pskb_may_pull(skb, 2)))
 601                 goto err_free;
 602
 603         /* expect a valid ethernet header here. */
 604         if (unlikely(skb->mac_len != sizeof(struct ethhdr)
 605                                 || !skb_mac_header(skb)))
 606                 goto err_free;
 607
 608         if (!hard_iface->soft_iface)
 609                 goto err_free;
 610
 611         bat_priv = netdev_priv(hard_iface->soft_iface);
 612
 613         if (atomic_read(&bat_priv->mesh_state) != MESH_ACTIVE)
 614                 goto err_free;
 615
 616         /* discard frames on not active interfaces */
 617         if (hard_iface->if_status != IF_ACTIVE)
 618                 goto err_free;
 619
 620         batman_packet = (struct batman_packet *)skb->data;
 621
 622         if (batman_packet->version != COMPAT_VERSION) {
 623                 bat_dbg(DBG_BATMAN, bat_priv,
 624                         "Drop packet: incompatible batman version (%i)\n",
 625                         batman_packet->version);
 626                 goto err_free;
 627         }
 628
 629         /* all receive handlers return whether they received or reused
 630          * the supplied skb. if not, we have to free the skb. */
 631
 632         switch (batman_packet->packet_type) {
 633                 /* batman originator packet */
 634         case BAT_PACKET:
 635                 ret = recv_bat_packet(skb, hard_iface);
 636                 break;
 637
 638                 /* batman icmp packet */
 639         case BAT_ICMP:
 640                 ret = recv_icmp_packet(skb, hard_iface);
 641                 break;
 642
 643                 /* unicast packet */
 644         case BAT_UNICAST:
 645                 ret = recv_unicast_packet(skb, hard_iface);
 646                 break;
 647
 648                 /* fragmented unicast packet */
 649         case BAT_UNICAST_FRAG:
 650                 ret = recv_ucast_frag_packet(skb, hard_iface);
 651                 break;
 652
 653                 /* broadcast packet */
 654         case BAT_BCAST:
 655                 ret = recv_bcast_packet(skb, hard_iface);
 656                 break;
 657
 658                 /* vis packet */
 659         case BAT_VIS:
 660                 ret = recv_vis_packet(skb, hard_iface);
 661                 break;
 662         default:
 663                 ret = NET_RX_DROP;
 664         }
 665
 666         if (ret == NET_RX_DROP)
 667                 kfree_skb(skb);
 668
 669         /* return NET_RX_SUCCESS in any case as we
 670          * most probably dropped the packet for
 671          * routing-logical reasons. */
 672
 673         return NET_RX_SUCCESS;
 674
 675 err_free:
 676         kfree_skb(skb);
 677 err_out:
 678         return NET_RX_DROP;
 679 }
 680
 681 struct notifier_block hard_if_notifier = {
 682         .notifier_call = hard_if_event,
 683 };