root/net/batman-adv/gateway_client.c

DEFINITIONS

1. batadv_gw_node_release
2. batadv_gw_node_put
3. batadv_gw_get_selected_gw_node
4. batadv_gw_get_selected_orig
5. batadv_gw_select
6. batadv_gw_reselect
7. batadv_gw_check_client_stop
8. batadv_gw_election
9. batadv_gw_check_election
10. batadv_gw_node_add
11. batadv_gw_node_get
12. batadv_gw_node_update
13. batadv_gw_node_delete
14. batadv_gw_node_free
15. batadv_gw_client_seq_print_text
16. batadv_gw_dump
17. batadv_gw_dhcp_recipient_get
18. batadv_gw_out_of_range

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (C) 2009-2019  B.A.T.M.A.N. contributors:
   3  *
   4  * Marek Lindner
   5  */
   6 
   7 #include "gateway_client.h"
   8 #include "main.h"
   9 
  10 #include <linux/atomic.h>
  11 #include <linux/byteorder/generic.h>
  12 #include <linux/errno.h>
  13 #include <linux/etherdevice.h>
  14 #include <linux/gfp.h>
  15 #include <linux/if_ether.h>
  16 #include <linux/if_vlan.h>
  17 #include <linux/in.h>
  18 #include <linux/ip.h>
  19 #include <linux/ipv6.h>
  20 #include <linux/kernel.h>
  21 #include <linux/kref.h>
  22 #include <linux/list.h>
  23 #include <linux/lockdep.h>
  24 #include <linux/netdevice.h>
  25 #include <linux/netlink.h>
  26 #include <linux/rculist.h>
  27 #include <linux/rcupdate.h>
  28 #include <linux/seq_file.h>
  29 #include <linux/skbuff.h>
  30 #include <linux/slab.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/stddef.h>
  33 #include <linux/udp.h>
  34 #include <net/sock.h>
  35 #include <uapi/linux/batadv_packet.h>
  36 #include <uapi/linux/batman_adv.h>
  37 
  38 #include "hard-interface.h"
  39 #include "log.h"
  40 #include "netlink.h"
  41 #include "originator.h"
  42 #include "routing.h"
  43 #include "soft-interface.h"
  44 #include "translation-table.h"
  45 
  46 /* These are the offsets of the "hw type" and "hw address length" in the dhcp
  47  * packet starting at the beginning of the dhcp header
  48  */
  49 #define BATADV_DHCP_HTYPE_OFFSET        1
  50 #define BATADV_DHCP_HLEN_OFFSET         2
  51 /* Value of htype representing Ethernet */
  52 #define BATADV_DHCP_HTYPE_ETHERNET      0x01
  53 /* This is the offset of the "chaddr" field in the dhcp packet starting at the
  54  * beginning of the dhcp header
  55  */
  56 #define BATADV_DHCP_CHADDR_OFFSET       28
  57 
  58 /**
  59  * batadv_gw_node_release() - release gw_node from lists and queue for free
  60  *  after rcu grace period
  61  * @ref: kref pointer of the gw_node
  62  */
  63 static void batadv_gw_node_release(struct kref *ref)
  64 {
  65         struct batadv_gw_node *gw_node;
  66 
  67         gw_node = container_of(ref, struct batadv_gw_node, refcount);
  68 
  69         batadv_orig_node_put(gw_node->orig_node);
  70         kfree_rcu(gw_node, rcu);
  71 }
  72 
  73 /**
  74  * batadv_gw_node_put() - decrement the gw_node refcounter and possibly release
  75  *  it
  76  * @gw_node: gateway node to free
  77  */
  78 void batadv_gw_node_put(struct batadv_gw_node *gw_node)
  79 {
  80         kref_put(&gw_node->refcount, batadv_gw_node_release);
  81 }
  82 
  83 /**
  84  * batadv_gw_get_selected_gw_node() - Get currently selected gateway
  85  * @bat_priv: the bat priv with all the soft interface information
  86  *
  87  * Return: selected gateway (with increased refcnt), NULL on errors
  88  */
  89 struct batadv_gw_node *
  90 batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
  91 {
  92         struct batadv_gw_node *gw_node;
  93 
  94         rcu_read_lock();
  95         gw_node = rcu_dereference(bat_priv->gw.curr_gw);
  96         if (!gw_node)
  97                 goto out;
  98 
  99         if (!kref_get_unless_zero(&gw_node->refcount))
 100                 gw_node = NULL;
 101 
 102 out:
 103         rcu_read_unlock();
 104         return gw_node;
 105 }
 106 
 107 /**
 108  * batadv_gw_get_selected_orig() - Get originator of currently selected gateway
 109  * @bat_priv: the bat priv with all the soft interface information
 110  *
 111  * Return: orig_node of selected gateway (with increased refcnt), NULL on errors
 112  */
 113 struct batadv_orig_node *
 114 batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
 115 {
 116         struct batadv_gw_node *gw_node;
 117         struct batadv_orig_node *orig_node = NULL;
 118 
 119         gw_node = batadv_gw_get_selected_gw_node(bat_priv);
 120         if (!gw_node)
 121                 goto out;
 122 
 123         rcu_read_lock();
 124         orig_node = gw_node->orig_node;
 125         if (!orig_node)
 126                 goto unlock;
 127 
 128         if (!kref_get_unless_zero(&orig_node->refcount))
 129                 orig_node = NULL;
 130 
 131 unlock:
 132         rcu_read_unlock();
 133 out:
 134         if (gw_node)
 135                 batadv_gw_node_put(gw_node);
 136         return orig_node;
 137 }
 138 
 139 static void batadv_gw_select(struct batadv_priv *bat_priv,
 140                              struct batadv_gw_node *new_gw_node)
 141 {
 142         struct batadv_gw_node *curr_gw_node;
 143 
 144         spin_lock_bh(&bat_priv->gw.list_lock);
 145 
 146         if (new_gw_node)
 147                 kref_get(&new_gw_node->refcount);
 148 
 149         curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
 150         rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);
 151 
 152         if (curr_gw_node)
 153                 batadv_gw_node_put(curr_gw_node);
 154 
 155         spin_unlock_bh(&bat_priv->gw.list_lock);
 156 }
 157 
 158 /**
 159  * batadv_gw_reselect() - force a gateway reselection
 160  * @bat_priv: the bat priv with all the soft interface information
 161  *
 162  * Set a flag to remind the GW component to perform a new gateway reselection.
 163  * However this function does not ensure that the current gateway is going to be
 164  * deselected. The reselection mechanism may elect the same gateway once again.
 165  *
 166  * This means that invoking batadv_gw_reselect() does not guarantee a gateway
 167  * change and therefore a uevent is not necessarily expected.
 168  */
 169 void batadv_gw_reselect(struct batadv_priv *bat_priv)
 170 {
 171         atomic_set(&bat_priv->gw.reselect, 1);
 172 }
 173 
 174 /**
 175  * batadv_gw_check_client_stop() - check if client mode has been switched off
 176  * @bat_priv: the bat priv with all the soft interface information
 177  *
 178  * This function assumes the caller has checked that the gw state *is actually
 179  * changing*. This function is not supposed to be called when there is no state
 180  * change.
 181  */
 182 void batadv_gw_check_client_stop(struct batadv_priv *bat_priv)
 183 {
 184         struct batadv_gw_node *curr_gw;
 185 
 186         if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT)
 187                 return;
 188 
 189         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 190         if (!curr_gw)
 191                 return;
 192 
 193         /* deselect the current gateway so that next time that client mode is
 194          * enabled a proper GW_ADD event can be sent
 195          */
 196         batadv_gw_select(bat_priv, NULL);
 197 
 198         /* if batman-adv is switching the gw client mode off and a gateway was
 199          * already selected, send a DEL uevent
 200          */
 201         batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL);
 202 
 203         batadv_gw_node_put(curr_gw);
 204 }
 205 
 206 /**
 207  * batadv_gw_election() - Elect the best gateway
 208  * @bat_priv: the bat priv with all the soft interface information
 209  */
 210 void batadv_gw_election(struct batadv_priv *bat_priv)
 211 {
 212         struct batadv_gw_node *curr_gw = NULL;
 213         struct batadv_gw_node *next_gw = NULL;
 214         struct batadv_neigh_node *router = NULL;
 215         struct batadv_neigh_ifinfo *router_ifinfo = NULL;
 216         char gw_addr[18] = { '\0' };
 217 
 218         if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT)
 219                 goto out;
 220 
 221         if (!bat_priv->algo_ops->gw.get_best_gw_node)
 222                 goto out;
 223 
 224         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 225 
 226         if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
 227                 goto out;
 228 
 229         /* if gw.reselect is set to 1 it means that a previous call to
 230          * gw.is_eligible() said that we have a new best GW, therefore it can
 231          * now be picked from the list and selected
 232          */
 233         next_gw = bat_priv->algo_ops->gw.get_best_gw_node(bat_priv);
 234 
 235         if (curr_gw == next_gw)
 236                 goto out;
 237 
 238         if (next_gw) {
 239                 sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
 240 
 241                 router = batadv_orig_router_get(next_gw->orig_node,
 242                                                 BATADV_IF_DEFAULT);
 243                 if (!router) {
 244                         batadv_gw_reselect(bat_priv);
 245                         goto out;
 246                 }
 247 
 248                 router_ifinfo = batadv_neigh_ifinfo_get(router,
 249                                                         BATADV_IF_DEFAULT);
 250                 if (!router_ifinfo) {
 251                         batadv_gw_reselect(bat_priv);
 252                         goto out;
 253                 }
 254         }
 255 
 256         if (curr_gw && !next_gw) {
 257                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 258                            "Removing selected gateway - no gateway in range\n");
 259                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
 260                                     NULL);
 261         } else if (!curr_gw && next_gw) {
 262                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 263                            "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
 264                            next_gw->orig_node->orig,
 265                            next_gw->bandwidth_down / 10,
 266                            next_gw->bandwidth_down % 10,
 267                            next_gw->bandwidth_up / 10,
 268                            next_gw->bandwidth_up % 10,
 269                            router_ifinfo->bat_iv.tq_avg);
 270                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
 271                                     gw_addr);
 272         } else {
 273                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 274                            "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
 275                            next_gw->orig_node->orig,
 276                            next_gw->bandwidth_down / 10,
 277                            next_gw->bandwidth_down % 10,
 278                            next_gw->bandwidth_up / 10,
 279                            next_gw->bandwidth_up % 10,
 280                            router_ifinfo->bat_iv.tq_avg);
 281                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
 282                                     gw_addr);
 283         }
 284 
 285         batadv_gw_select(bat_priv, next_gw);
 286 
 287 out:
 288         if (curr_gw)
 289                 batadv_gw_node_put(curr_gw);
 290         if (next_gw)
 291                 batadv_gw_node_put(next_gw);
 292         if (router)
 293                 batadv_neigh_node_put(router);
 294         if (router_ifinfo)
 295                 batadv_neigh_ifinfo_put(router_ifinfo);
 296 }
 297 
 298 /**
 299  * batadv_gw_check_election() - Elect orig node as best gateway when eligible
 300  * @bat_priv: the bat priv with all the soft interface information
 301  * @orig_node: orig node which is to be checked
 302  */
 303 void batadv_gw_check_election(struct batadv_priv *bat_priv,
 304                               struct batadv_orig_node *orig_node)
 305 {
 306         struct batadv_orig_node *curr_gw_orig;
 307 
 308         /* abort immediately if the routing algorithm does not support gateway
 309          * election
 310          */
 311         if (!bat_priv->algo_ops->gw.is_eligible)
 312                 return;
 313 
 314         curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
 315         if (!curr_gw_orig)
 316                 goto reselect;
 317 
 318         /* this node already is the gateway */
 319         if (curr_gw_orig == orig_node)
 320                 goto out;
 321 
 322         if (!bat_priv->algo_ops->gw.is_eligible(bat_priv, curr_gw_orig,
 323                                                 orig_node))
 324                 goto out;
 325 
 326 reselect:
 327         batadv_gw_reselect(bat_priv);
 328 out:
 329         if (curr_gw_orig)
 330                 batadv_orig_node_put(curr_gw_orig);
 331 }
 332 
 333 /**
 334  * batadv_gw_node_add() - add gateway node to list of available gateways
 335  * @bat_priv: the bat priv with all the soft interface information
 336  * @orig_node: originator announcing gateway capabilities
 337  * @gateway: announced bandwidth information
 338  *
 339  * Has to be called with the appropriate locks being acquired
 340  * (gw.list_lock).
 341  */
 342 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
 343                                struct batadv_orig_node *orig_node,
 344                                struct batadv_tvlv_gateway_data *gateway)
 345 {
 346         struct batadv_gw_node *gw_node;
 347 
 348         lockdep_assert_held(&bat_priv->gw.list_lock);
 349 
 350         if (gateway->bandwidth_down == 0)
 351                 return;
 352 
 353         gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
 354         if (!gw_node)
 355                 return;
 356 
 357         kref_init(&gw_node->refcount);
 358         INIT_HLIST_NODE(&gw_node->list);
 359         kref_get(&orig_node->refcount);
 360         gw_node->orig_node = orig_node;
 361         gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
 362         gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
 363 
 364         kref_get(&gw_node->refcount);
 365         hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.gateway_list);
 366         bat_priv->gw.generation++;
 367 
 368         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 369                    "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n",
 370                    orig_node->orig,
 371                    ntohl(gateway->bandwidth_down) / 10,
 372                    ntohl(gateway->bandwidth_down) % 10,
 373                    ntohl(gateway->bandwidth_up) / 10,
 374                    ntohl(gateway->bandwidth_up) % 10);
 375 
 376         /* don't return reference to new gw_node */
 377         batadv_gw_node_put(gw_node);
 378 }
 379 
 380 /**
 381  * batadv_gw_node_get() - retrieve gateway node from list of available gateways
 382  * @bat_priv: the bat priv with all the soft interface information
 383  * @orig_node: originator announcing gateway capabilities
 384  *
 385  * Return: gateway node if found or NULL otherwise.
 386  */
 387 struct batadv_gw_node *batadv_gw_node_get(struct batadv_priv *bat_priv,
 388                                           struct batadv_orig_node *orig_node)
 389 {
 390         struct batadv_gw_node *gw_node_tmp, *gw_node = NULL;
 391 
 392         rcu_read_lock();
 393         hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.gateway_list,
 394                                  list) {
 395                 if (gw_node_tmp->orig_node != orig_node)
 396                         continue;
 397 
 398                 if (!kref_get_unless_zero(&gw_node_tmp->refcount))
 399                         continue;
 400 
 401                 gw_node = gw_node_tmp;
 402                 break;
 403         }
 404         rcu_read_unlock();
 405 
 406         return gw_node;
 407 }
 408 
 409 /**
 410  * batadv_gw_node_update() - update list of available gateways with changed
 411  *  bandwidth information
 412  * @bat_priv: the bat priv with all the soft interface information
 413  * @orig_node: originator announcing gateway capabilities
 414  * @gateway: announced bandwidth information
 415  */
 416 void batadv_gw_node_update(struct batadv_priv *bat_priv,
 417                            struct batadv_orig_node *orig_node,
 418                            struct batadv_tvlv_gateway_data *gateway)
 419 {
 420         struct batadv_gw_node *gw_node, *curr_gw = NULL;
 421 
 422         spin_lock_bh(&bat_priv->gw.list_lock);
 423         gw_node = batadv_gw_node_get(bat_priv, orig_node);
 424         if (!gw_node) {
 425                 batadv_gw_node_add(bat_priv, orig_node, gateway);
 426                 spin_unlock_bh(&bat_priv->gw.list_lock);
 427                 goto out;
 428         }
 429         spin_unlock_bh(&bat_priv->gw.list_lock);
 430 
 431         if (gw_node->bandwidth_down == ntohl(gateway->bandwidth_down) &&
 432             gw_node->bandwidth_up == ntohl(gateway->bandwidth_up))
 433                 goto out;
 434 
 435         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 436                    "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n",
 437                    orig_node->orig,
 438                    gw_node->bandwidth_down / 10,
 439                    gw_node->bandwidth_down % 10,
 440                    gw_node->bandwidth_up / 10,
 441                    gw_node->bandwidth_up % 10,
 442                    ntohl(gateway->bandwidth_down) / 10,
 443                    ntohl(gateway->bandwidth_down) % 10,
 444                    ntohl(gateway->bandwidth_up) / 10,
 445                    ntohl(gateway->bandwidth_up) % 10);
 446 
 447         gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
 448         gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
 449 
 450         if (ntohl(gateway->bandwidth_down) == 0) {
 451                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 452                            "Gateway %pM removed from gateway list\n",
 453                            orig_node->orig);
 454 
 455                 /* Note: We don't need a NULL check here, since curr_gw never
 456                  * gets dereferenced.
 457                  */
 458                 spin_lock_bh(&bat_priv->gw.list_lock);
 459                 if (!hlist_unhashed(&gw_node->list)) {
 460                         hlist_del_init_rcu(&gw_node->list);
 461                         batadv_gw_node_put(gw_node);
 462                         bat_priv->gw.generation++;
 463                 }
 464                 spin_unlock_bh(&bat_priv->gw.list_lock);
 465 
 466                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 467                 if (gw_node == curr_gw)
 468                         batadv_gw_reselect(bat_priv);
 469 
 470                 if (curr_gw)
 471                         batadv_gw_node_put(curr_gw);
 472         }
 473 
 474 out:
 475         if (gw_node)
 476                 batadv_gw_node_put(gw_node);
 477 }
 478 
 479 /**
 480  * batadv_gw_node_delete() - Remove orig_node from gateway list
 481  * @bat_priv: the bat priv with all the soft interface information
 482  * @orig_node: orig node which is currently in process of being removed
 483  */
 484 void batadv_gw_node_delete(struct batadv_priv *bat_priv,
 485                            struct batadv_orig_node *orig_node)
 486 {
 487         struct batadv_tvlv_gateway_data gateway;
 488 
 489         gateway.bandwidth_down = 0;
 490         gateway.bandwidth_up = 0;
 491 
 492         batadv_gw_node_update(bat_priv, orig_node, &gateway);
 493 }
 494 
 495 /**
 496  * batadv_gw_node_free() - Free gateway information from soft interface
 497  * @bat_priv: the bat priv with all the soft interface information
 498  */
 499 void batadv_gw_node_free(struct batadv_priv *bat_priv)
 500 {
 501         struct batadv_gw_node *gw_node;
 502         struct hlist_node *node_tmp;
 503 
 504         spin_lock_bh(&bat_priv->gw.list_lock);
 505         hlist_for_each_entry_safe(gw_node, node_tmp,
 506                                   &bat_priv->gw.gateway_list, list) {
 507                 hlist_del_init_rcu(&gw_node->list);
 508                 batadv_gw_node_put(gw_node);
 509                 bat_priv->gw.generation++;
 510         }
 511         spin_unlock_bh(&bat_priv->gw.list_lock);
 512 }
 513 
 514 #ifdef CONFIG_BATMAN_ADV_DEBUGFS
 515 
 516 /**
 517  * batadv_gw_client_seq_print_text() - Print the gateway table in a seq file
 518  * @seq: seq file to print on
 519  * @offset: not used
 520  *
 521  * Return: always 0
 522  */
 523 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
 524 {
 525         struct net_device *net_dev = (struct net_device *)seq->private;
 526         struct batadv_priv *bat_priv = netdev_priv(net_dev);
 527         struct batadv_hard_iface *primary_if;
 528 
 529         primary_if = batadv_seq_print_text_primary_if_get(seq);
 530         if (!primary_if)
 531                 return 0;
 532 
 533         seq_printf(seq, "[B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s %s)]\n",
 534                    BATADV_SOURCE_VERSION, primary_if->net_dev->name,
 535                    primary_if->net_dev->dev_addr, net_dev->name,
 536                    bat_priv->algo_ops->name);
 537 
 538         batadv_hardif_put(primary_if);
 539 
 540         if (!bat_priv->algo_ops->gw.print) {
 541                 seq_puts(seq,
 542                          "No printing function for this routing protocol\n");
 543                 return 0;
 544         }
 545 
 546         bat_priv->algo_ops->gw.print(bat_priv, seq);
 547 
 548         return 0;
 549 }
 550 #endif
 551 
 552 /**
 553  * batadv_gw_dump() - Dump gateways into a message
 554  * @msg: Netlink message to dump into
 555  * @cb: Control block containing additional options
 556  *
 557  * Return: Error code, or length of message
 558  */
 559 int batadv_gw_dump(struct sk_buff *msg, struct netlink_callback *cb)
 560 {
 561         struct batadv_hard_iface *primary_if = NULL;
 562         struct net *net = sock_net(cb->skb->sk);
 563         struct net_device *soft_iface;
 564         struct batadv_priv *bat_priv;
 565         int ifindex;
 566         int ret;
 567 
 568         ifindex = batadv_netlink_get_ifindex(cb->nlh,
 569                                              BATADV_ATTR_MESH_IFINDEX);
 570         if (!ifindex)
 571                 return -EINVAL;
 572 
 573         soft_iface = dev_get_by_index(net, ifindex);
 574         if (!soft_iface || !batadv_softif_is_valid(soft_iface)) {
 575                 ret = -ENODEV;
 576                 goto out;
 577         }
 578 
 579         bat_priv = netdev_priv(soft_iface);
 580 
 581         primary_if = batadv_primary_if_get_selected(bat_priv);
 582         if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
 583                 ret = -ENOENT;
 584                 goto out;
 585         }
 586 
 587         if (!bat_priv->algo_ops->gw.dump) {
 588                 ret = -EOPNOTSUPP;
 589                 goto out;
 590         }
 591 
 592         bat_priv->algo_ops->gw.dump(msg, cb, bat_priv);
 593 
 594         ret = msg->len;
 595 
 596 out:
 597         if (primary_if)
 598                 batadv_hardif_put(primary_if);
 599         if (soft_iface)
 600                 dev_put(soft_iface);
 601 
 602         return ret;
 603 }
 604 
 605 /**
 606  * batadv_gw_dhcp_recipient_get() - check if a packet is a DHCP message
 607  * @skb: the packet to check
 608  * @header_len: a pointer to the batman-adv header size
 609  * @chaddr: buffer where the client address will be stored. Valid
 610  *  only if the function returns BATADV_DHCP_TO_CLIENT
 611  *
 612  * This function may re-allocate the data buffer of the skb passed as argument.
 613  *
 614  * Return:
 615  * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error
 616  *   while parsing it
 617  * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server
 618  * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client
 619  */
 620 enum batadv_dhcp_recipient
 621 batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
 622                              u8 *chaddr)
 623 {
 624         enum batadv_dhcp_recipient ret = BATADV_DHCP_NO;
 625         struct ethhdr *ethhdr;
 626         struct iphdr *iphdr;
 627         struct ipv6hdr *ipv6hdr;
 628         struct udphdr *udphdr;
 629         struct vlan_ethhdr *vhdr;
 630         int chaddr_offset;
 631         __be16 proto;
 632         u8 *p;
 633 
 634         /* check for ethernet header */
 635         if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
 636                 return BATADV_DHCP_NO;
 637 
 638         ethhdr = eth_hdr(skb);
 639         proto = ethhdr->h_proto;
 640         *header_len += ETH_HLEN;
 641 
 642         /* check for initial vlan header */
 643         if (proto == htons(ETH_P_8021Q)) {
 644                 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
 645                         return BATADV_DHCP_NO;
 646 
 647                 vhdr = vlan_eth_hdr(skb);
 648                 proto = vhdr->h_vlan_encapsulated_proto;
 649                 *header_len += VLAN_HLEN;
 650         }
 651 
 652         /* check for ip header */
 653         switch (proto) {
 654         case htons(ETH_P_IP):
 655                 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
 656                         return BATADV_DHCP_NO;
 657 
 658                 iphdr = (struct iphdr *)(skb->data + *header_len);
 659                 *header_len += iphdr->ihl * 4;
 660 
 661                 /* check for udp header */
 662                 if (iphdr->protocol != IPPROTO_UDP)
 663                         return BATADV_DHCP_NO;
 664 
 665                 break;
 666         case htons(ETH_P_IPV6):
 667                 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
 668                         return BATADV_DHCP_NO;
 669 
 670                 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
 671                 *header_len += sizeof(*ipv6hdr);
 672 
 673                 /* check for udp header */
 674                 if (ipv6hdr->nexthdr != IPPROTO_UDP)
 675                         return BATADV_DHCP_NO;
 676 
 677                 break;
 678         default:
 679                 return BATADV_DHCP_NO;
 680         }
 681 
 682         if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
 683                 return BATADV_DHCP_NO;
 684 
 685         udphdr = (struct udphdr *)(skb->data + *header_len);
 686         *header_len += sizeof(*udphdr);
 687 
 688         /* check for bootp port */
 689         switch (proto) {
 690         case htons(ETH_P_IP):
 691                 if (udphdr->dest == htons(67))
 692                         ret = BATADV_DHCP_TO_SERVER;
 693                 else if (udphdr->source == htons(67))
 694                         ret = BATADV_DHCP_TO_CLIENT;
 695                 break;
 696         case htons(ETH_P_IPV6):
 697                 if (udphdr->dest == htons(547))
 698                         ret = BATADV_DHCP_TO_SERVER;
 699                 else if (udphdr->source == htons(547))
 700                         ret = BATADV_DHCP_TO_CLIENT;
 701                 break;
 702         }
 703 
 704         chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET;
 705         /* store the client address if the message is going to a client */
 706         if (ret == BATADV_DHCP_TO_CLIENT &&
 707             pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) {
 708                 /* check if the DHCP packet carries an Ethernet DHCP */
 709                 p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET;
 710                 if (*p != BATADV_DHCP_HTYPE_ETHERNET)
 711                         return BATADV_DHCP_NO;
 712 
 713                 /* check if the DHCP packet carries a valid Ethernet address */
 714                 p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET;
 715                 if (*p != ETH_ALEN)
 716                         return BATADV_DHCP_NO;
 717 
 718                 ether_addr_copy(chaddr, skb->data + chaddr_offset);
 719         }
 720 
 721         return ret;
 722 }
 723 
 724 /**
 725  * batadv_gw_out_of_range() - check if the dhcp request destination is the best
 726  *  gateway
 727  * @bat_priv: the bat priv with all the soft interface information
 728  * @skb: the outgoing packet
 729  *
 730  * Check if the skb is a DHCP request and if it is sent to the current best GW
 731  * server. Due to topology changes it may be the case that the GW server
 732  * previously selected is not the best one anymore.
 733  *
 734  * This call might reallocate skb data.
 735  * Must be invoked only when the DHCP packet is going TO a DHCP SERVER.
 736  *
 737  * Return: true if the packet destination is unicast and it is not the best gw,
 738  * false otherwise.
 739  */
 740 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
 741                             struct sk_buff *skb)
 742 {
 743         struct batadv_neigh_node *neigh_curr = NULL;
 744         struct batadv_neigh_node *neigh_old = NULL;
 745         struct batadv_orig_node *orig_dst_node = NULL;
 746         struct batadv_gw_node *gw_node = NULL;
 747         struct batadv_gw_node *curr_gw = NULL;
 748         struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo;
 749         struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 750         bool out_of_range = false;
 751         u8 curr_tq_avg;
 752         unsigned short vid;
 753 
 754         vid = batadv_get_vid(skb, 0);
 755 
 756         if (is_multicast_ether_addr(ethhdr->h_dest))
 757                 goto out;
 758 
 759         orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
 760                                                  ethhdr->h_dest, vid);
 761         if (!orig_dst_node)
 762                 goto out;
 763 
 764         gw_node = batadv_gw_node_get(bat_priv, orig_dst_node);
 765         if (!gw_node)
 766                 goto out;
 767 
 768         switch (atomic_read(&bat_priv->gw.mode)) {
 769         case BATADV_GW_MODE_SERVER:
 770                 /* If we are a GW then we are our best GW. We can artificially
 771                  * set the tq towards ourself as the maximum value
 772                  */
 773                 curr_tq_avg = BATADV_TQ_MAX_VALUE;
 774                 break;
 775         case BATADV_GW_MODE_CLIENT:
 776                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
 777                 if (!curr_gw)
 778                         goto out;
 779 
 780                 /* packet is going to our gateway */
 781                 if (curr_gw->orig_node == orig_dst_node)
 782                         goto out;
 783 
 784                 /* If the dhcp packet has been sent to a different gw,
 785                  * we have to evaluate whether the old gw is still
 786                  * reliable enough
 787                  */
 788                 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
 789                                                 NULL);
 790                 if (!neigh_curr)
 791                         goto out;
 792 
 793                 curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr,
 794                                                       BATADV_IF_DEFAULT);
 795                 if (!curr_ifinfo)
 796                         goto out;
 797 
 798                 curr_tq_avg = curr_ifinfo->bat_iv.tq_avg;
 799                 batadv_neigh_ifinfo_put(curr_ifinfo);
 800 
 801                 break;
 802         case BATADV_GW_MODE_OFF:
 803         default:
 804                 goto out;
 805         }
 806 
 807         neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
 808         if (!neigh_old)
 809                 goto out;
 810 
 811         old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT);
 812         if (!old_ifinfo)
 813                 goto out;
 814 
 815         if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD)
 816                 out_of_range = true;
 817         batadv_neigh_ifinfo_put(old_ifinfo);
 818 
 819 out:
 820         if (orig_dst_node)
 821                 batadv_orig_node_put(orig_dst_node);
 822         if (curr_gw)
 823                 batadv_gw_node_put(curr_gw);
 824         if (gw_node)
 825                 batadv_gw_node_put(gw_node);
 826         if (neigh_old)
 827                 batadv_neigh_node_put(neigh_old);
 828         if (neigh_curr)
 829                 batadv_neigh_node_put(neigh_curr);
 830         return out_of_range;
 831 }