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TOMOYO Linux Cross Reference
Linux/net/batman-adv/gateway_client.c

Version: ~ [ linux-5.15-rc7 ] ~ [ linux-5.14.14 ] ~ [ linux-5.13.19 ] ~ [ linux-5.12.19 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.75 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.155 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.213 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.252 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.287 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.289 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /* Copyright (C) 2009-2017  B.A.T.M.A.N. contributors:
  2  *
  3  * Marek Lindner
  4  *
  5  * This program is free software; you can redistribute it and/or
  6  * modify it under the terms of version 2 of the GNU General Public
  7  * License as published by the Free Software Foundation.
  8  *
  9  * This program is distributed in the hope that it will be useful, but
 10  * WITHOUT ANY WARRANTY; without even the implied warranty of
 11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 12  * General Public License for more details.
 13  *
 14  * You should have received a copy of the GNU General Public License
 15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
 16  */
 17 
 18 #include "gateway_client.h"
 19 #include "main.h"
 20 
 21 #include <linux/atomic.h>
 22 #include <linux/byteorder/generic.h>
 23 #include <linux/errno.h>
 24 #include <linux/etherdevice.h>
 25 #include <linux/fs.h>
 26 #include <linux/if_ether.h>
 27 #include <linux/if_vlan.h>
 28 #include <linux/in.h>
 29 #include <linux/ip.h>
 30 #include <linux/ipv6.h>
 31 #include <linux/kernel.h>
 32 #include <linux/kref.h>
 33 #include <linux/list.h>
 34 #include <linux/netdevice.h>
 35 #include <linux/netlink.h>
 36 #include <linux/rculist.h>
 37 #include <linux/rcupdate.h>
 38 #include <linux/seq_file.h>
 39 #include <linux/skbuff.h>
 40 #include <linux/slab.h>
 41 #include <linux/spinlock.h>
 42 #include <linux/stddef.h>
 43 #include <linux/udp.h>
 44 #include <net/sock.h>
 45 #include <uapi/linux/batman_adv.h>
 46 
 47 #include "gateway_common.h"
 48 #include "hard-interface.h"
 49 #include "log.h"
 50 #include "netlink.h"
 51 #include "originator.h"
 52 #include "packet.h"
 53 #include "routing.h"
 54 #include "soft-interface.h"
 55 #include "sysfs.h"
 56 #include "translation-table.h"
 57 
 58 /* These are the offsets of the "hw type" and "hw address length" in the dhcp
 59  * packet starting at the beginning of the dhcp header
 60  */
 61 #define BATADV_DHCP_HTYPE_OFFSET        1
 62 #define BATADV_DHCP_HLEN_OFFSET         2
 63 /* Value of htype representing Ethernet */
 64 #define BATADV_DHCP_HTYPE_ETHERNET      0x01
 65 /* This is the offset of the "chaddr" field in the dhcp packet starting at the
 66  * beginning of the dhcp header
 67  */
 68 #define BATADV_DHCP_CHADDR_OFFSET       28
 69 
 70 /**
 71  * batadv_gw_node_release - release gw_node from lists and queue for free after
 72  *  rcu grace period
 73  * @ref: kref pointer of the gw_node
 74  */
 75 static void batadv_gw_node_release(struct kref *ref)
 76 {
 77         struct batadv_gw_node *gw_node;
 78 
 79         gw_node = container_of(ref, struct batadv_gw_node, refcount);
 80 
 81         batadv_orig_node_put(gw_node->orig_node);
 82         kfree_rcu(gw_node, rcu);
 83 }
 84 
 85 /**
 86  * batadv_gw_node_put - decrement the gw_node refcounter and possibly release it
 87  * @gw_node: gateway node to free
 88  */
 89 void batadv_gw_node_put(struct batadv_gw_node *gw_node)
 90 {
 91         kref_put(&gw_node->refcount, batadv_gw_node_release);
 92 }
 93 
 94 struct batadv_gw_node *
 95 batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
 96 {
 97         struct batadv_gw_node *gw_node;
 98 
 99         rcu_read_lock();
100         gw_node = rcu_dereference(bat_priv->gw.curr_gw);
101         if (!gw_node)
102                 goto out;
103 
104         if (!kref_get_unless_zero(&gw_node->refcount))
105                 gw_node = NULL;
106 
107 out:
108         rcu_read_unlock();
109         return gw_node;
110 }
111 
112 struct batadv_orig_node *
113 batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
114 {
115         struct batadv_gw_node *gw_node;
116         struct batadv_orig_node *orig_node = NULL;
117 
118         gw_node = batadv_gw_get_selected_gw_node(bat_priv);
119         if (!gw_node)
120                 goto out;
121 
122         rcu_read_lock();
123         orig_node = gw_node->orig_node;
124         if (!orig_node)
125                 goto unlock;
126 
127         if (!kref_get_unless_zero(&orig_node->refcount))
128                 orig_node = NULL;
129 
130 unlock:
131         rcu_read_unlock();
132 out:
133         if (gw_node)
134                 batadv_gw_node_put(gw_node);
135         return orig_node;
136 }
137 
138 static void batadv_gw_select(struct batadv_priv *bat_priv,
139                              struct batadv_gw_node *new_gw_node)
140 {
141         struct batadv_gw_node *curr_gw_node;
142 
143         spin_lock_bh(&bat_priv->gw.list_lock);
144 
145         if (new_gw_node)
146                 kref_get(&new_gw_node->refcount);
147 
148         curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
149         rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);
150 
151         if (curr_gw_node)
152                 batadv_gw_node_put(curr_gw_node);
153 
154         spin_unlock_bh(&bat_priv->gw.list_lock);
155 }
156 
157 /**
158  * batadv_gw_reselect - force a gateway reselection
159  * @bat_priv: the bat priv with all the soft interface information
160  *
161  * Set a flag to remind the GW component to perform a new gateway reselection.
162  * However this function does not ensure that the current gateway is going to be
163  * deselected. The reselection mechanism may elect the same gateway once again.
164  *
165  * This means that invoking batadv_gw_reselect() does not guarantee a gateway
166  * change and therefore a uevent is not necessarily expected.
167  */
168 void batadv_gw_reselect(struct batadv_priv *bat_priv)
169 {
170         atomic_set(&bat_priv->gw.reselect, 1);
171 }
172 
173 /**
174  * batadv_gw_check_client_stop - check if client mode has been switched off
175  * @bat_priv: the bat priv with all the soft interface information
176  *
177  * This function assumes the caller has checked that the gw state *is actually
178  * changing*. This function is not supposed to be called when there is no state
179  * change.
180  */
181 void batadv_gw_check_client_stop(struct batadv_priv *bat_priv)
182 {
183         struct batadv_gw_node *curr_gw;
184 
185         if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT)
186                 return;
187 
188         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
189         if (!curr_gw)
190                 return;
191 
192         /* deselect the current gateway so that next time that client mode is
193          * enabled a proper GW_ADD event can be sent
194          */
195         batadv_gw_select(bat_priv, NULL);
196 
197         /* if batman-adv is switching the gw client mode off and a gateway was
198          * already selected, send a DEL uevent
199          */
200         batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL);
201 
202         batadv_gw_node_put(curr_gw);
203 }
204 
205 void batadv_gw_election(struct batadv_priv *bat_priv)
206 {
207         struct batadv_gw_node *curr_gw = NULL;
208         struct batadv_gw_node *next_gw = NULL;
209         struct batadv_neigh_node *router = NULL;
210         struct batadv_neigh_ifinfo *router_ifinfo = NULL;
211         char gw_addr[18] = { '\0' };
212 
213         if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT)
214                 goto out;
215 
216         if (!bat_priv->algo_ops->gw.get_best_gw_node)
217                 goto out;
218 
219         curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
220 
221         if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
222                 goto out;
223 
224         /* if gw.reselect is set to 1 it means that a previous call to
225          * gw.is_eligible() said that we have a new best GW, therefore it can
226          * now be picked from the list and selected
227          */
228         next_gw = bat_priv->algo_ops->gw.get_best_gw_node(bat_priv);
229 
230         if (curr_gw == next_gw)
231                 goto out;
232 
233         if (next_gw) {
234                 sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
235 
236                 router = batadv_orig_router_get(next_gw->orig_node,
237                                                 BATADV_IF_DEFAULT);
238                 if (!router) {
239                         batadv_gw_reselect(bat_priv);
240                         goto out;
241                 }
242 
243                 router_ifinfo = batadv_neigh_ifinfo_get(router,
244                                                         BATADV_IF_DEFAULT);
245                 if (!router_ifinfo) {
246                         batadv_gw_reselect(bat_priv);
247                         goto out;
248                 }
249         }
250 
251         if ((curr_gw) && (!next_gw)) {
252                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
253                            "Removing selected gateway - no gateway in range\n");
254                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
255                                     NULL);
256         } else if ((!curr_gw) && (next_gw)) {
257                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
258                            "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
259                            next_gw->orig_node->orig,
260                            next_gw->bandwidth_down / 10,
261                            next_gw->bandwidth_down % 10,
262                            next_gw->bandwidth_up / 10,
263                            next_gw->bandwidth_up % 10,
264                            router_ifinfo->bat_iv.tq_avg);
265                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
266                                     gw_addr);
267         } else {
268                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
269                            "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
270                            next_gw->orig_node->orig,
271                            next_gw->bandwidth_down / 10,
272                            next_gw->bandwidth_down % 10,
273                            next_gw->bandwidth_up / 10,
274                            next_gw->bandwidth_up % 10,
275                            router_ifinfo->bat_iv.tq_avg);
276                 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
277                                     gw_addr);
278         }
279 
280         batadv_gw_select(bat_priv, next_gw);
281 
282 out:
283         if (curr_gw)
284                 batadv_gw_node_put(curr_gw);
285         if (next_gw)
286                 batadv_gw_node_put(next_gw);
287         if (router)
288                 batadv_neigh_node_put(router);
289         if (router_ifinfo)
290                 batadv_neigh_ifinfo_put(router_ifinfo);
291 }
292 
293 void batadv_gw_check_election(struct batadv_priv *bat_priv,
294                               struct batadv_orig_node *orig_node)
295 {
296         struct batadv_orig_node *curr_gw_orig;
297 
298         /* abort immediately if the routing algorithm does not support gateway
299          * election
300          */
301         if (!bat_priv->algo_ops->gw.is_eligible)
302                 return;
303 
304         curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
305         if (!curr_gw_orig)
306                 goto reselect;
307 
308         /* this node already is the gateway */
309         if (curr_gw_orig == orig_node)
310                 goto out;
311 
312         if (!bat_priv->algo_ops->gw.is_eligible(bat_priv, curr_gw_orig,
313                                                 orig_node))
314                 goto out;
315 
316 reselect:
317         batadv_gw_reselect(bat_priv);
318 out:
319         if (curr_gw_orig)
320                 batadv_orig_node_put(curr_gw_orig);
321 }
322 
323 /**
324  * batadv_gw_node_add - add gateway node to list of available gateways
325  * @bat_priv: the bat priv with all the soft interface information
326  * @orig_node: originator announcing gateway capabilities
327  * @gateway: announced bandwidth information
328  */
329 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
330                                struct batadv_orig_node *orig_node,
331                                struct batadv_tvlv_gateway_data *gateway)
332 {
333         struct batadv_gw_node *gw_node;
334 
335         if (gateway->bandwidth_down == 0)
336                 return;
337 
338         gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
339         if (!gw_node)
340                 return;
341 
342         kref_init(&gw_node->refcount);
343         INIT_HLIST_NODE(&gw_node->list);
344         kref_get(&orig_node->refcount);
345         gw_node->orig_node = orig_node;
346         gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
347         gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
348 
349         spin_lock_bh(&bat_priv->gw.list_lock);
350         kref_get(&gw_node->refcount);
351         hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.gateway_list);
352         spin_unlock_bh(&bat_priv->gw.list_lock);
353 
354         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
355                    "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n",
356                    orig_node->orig,
357                    ntohl(gateway->bandwidth_down) / 10,
358                    ntohl(gateway->bandwidth_down) % 10,
359                    ntohl(gateway->bandwidth_up) / 10,
360                    ntohl(gateway->bandwidth_up) % 10);
361 
362         /* don't return reference to new gw_node */
363         batadv_gw_node_put(gw_node);
364 }
365 
366 /**
367  * batadv_gw_node_get - retrieve gateway node from list of available gateways
368  * @bat_priv: the bat priv with all the soft interface information
369  * @orig_node: originator announcing gateway capabilities
370  *
371  * Return: gateway node if found or NULL otherwise.
372  */
373 struct batadv_gw_node *batadv_gw_node_get(struct batadv_priv *bat_priv,
374                                           struct batadv_orig_node *orig_node)
375 {
376         struct batadv_gw_node *gw_node_tmp, *gw_node = NULL;
377 
378         rcu_read_lock();
379         hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.gateway_list,
380                                  list) {
381                 if (gw_node_tmp->orig_node != orig_node)
382                         continue;
383 
384                 if (!kref_get_unless_zero(&gw_node_tmp->refcount))
385                         continue;
386 
387                 gw_node = gw_node_tmp;
388                 break;
389         }
390         rcu_read_unlock();
391 
392         return gw_node;
393 }
394 
395 /**
396  * batadv_gw_node_update - update list of available gateways with changed
397  *  bandwidth information
398  * @bat_priv: the bat priv with all the soft interface information
399  * @orig_node: originator announcing gateway capabilities
400  * @gateway: announced bandwidth information
401  */
402 void batadv_gw_node_update(struct batadv_priv *bat_priv,
403                            struct batadv_orig_node *orig_node,
404                            struct batadv_tvlv_gateway_data *gateway)
405 {
406         struct batadv_gw_node *gw_node, *curr_gw = NULL;
407 
408         gw_node = batadv_gw_node_get(bat_priv, orig_node);
409         if (!gw_node) {
410                 batadv_gw_node_add(bat_priv, orig_node, gateway);
411                 goto out;
412         }
413 
414         if ((gw_node->bandwidth_down == ntohl(gateway->bandwidth_down)) &&
415             (gw_node->bandwidth_up == ntohl(gateway->bandwidth_up)))
416                 goto out;
417 
418         batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
419                    "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n",
420                    orig_node->orig,
421                    gw_node->bandwidth_down / 10,
422                    gw_node->bandwidth_down % 10,
423                    gw_node->bandwidth_up / 10,
424                    gw_node->bandwidth_up % 10,
425                    ntohl(gateway->bandwidth_down) / 10,
426                    ntohl(gateway->bandwidth_down) % 10,
427                    ntohl(gateway->bandwidth_up) / 10,
428                    ntohl(gateway->bandwidth_up) % 10);
429 
430         gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
431         gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
432 
433         if (ntohl(gateway->bandwidth_down) == 0) {
434                 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
435                            "Gateway %pM removed from gateway list\n",
436                            orig_node->orig);
437 
438                 /* Note: We don't need a NULL check here, since curr_gw never
439                  * gets dereferenced.
440                  */
441                 spin_lock_bh(&bat_priv->gw.list_lock);
442                 if (!hlist_unhashed(&gw_node->list)) {
443                         hlist_del_init_rcu(&gw_node->list);
444                         batadv_gw_node_put(gw_node);
445                 }
446                 spin_unlock_bh(&bat_priv->gw.list_lock);
447 
448                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
449                 if (gw_node == curr_gw)
450                         batadv_gw_reselect(bat_priv);
451 
452                 if (curr_gw)
453                         batadv_gw_node_put(curr_gw);
454         }
455 
456 out:
457         if (gw_node)
458                 batadv_gw_node_put(gw_node);
459 }
460 
461 void batadv_gw_node_delete(struct batadv_priv *bat_priv,
462                            struct batadv_orig_node *orig_node)
463 {
464         struct batadv_tvlv_gateway_data gateway;
465 
466         gateway.bandwidth_down = 0;
467         gateway.bandwidth_up = 0;
468 
469         batadv_gw_node_update(bat_priv, orig_node, &gateway);
470 }
471 
472 void batadv_gw_node_free(struct batadv_priv *bat_priv)
473 {
474         struct batadv_gw_node *gw_node;
475         struct hlist_node *node_tmp;
476 
477         spin_lock_bh(&bat_priv->gw.list_lock);
478         hlist_for_each_entry_safe(gw_node, node_tmp,
479                                   &bat_priv->gw.gateway_list, list) {
480                 hlist_del_init_rcu(&gw_node->list);
481                 batadv_gw_node_put(gw_node);
482         }
483         spin_unlock_bh(&bat_priv->gw.list_lock);
484 }
485 
486 #ifdef CONFIG_BATMAN_ADV_DEBUGFS
487 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
488 {
489         struct net_device *net_dev = (struct net_device *)seq->private;
490         struct batadv_priv *bat_priv = netdev_priv(net_dev);
491         struct batadv_hard_iface *primary_if;
492 
493         primary_if = batadv_seq_print_text_primary_if_get(seq);
494         if (!primary_if)
495                 return 0;
496 
497         seq_printf(seq, "[B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s %s)]\n",
498                    BATADV_SOURCE_VERSION, primary_if->net_dev->name,
499                    primary_if->net_dev->dev_addr, net_dev->name,
500                    bat_priv->algo_ops->name);
501 
502         batadv_hardif_put(primary_if);
503 
504         if (!bat_priv->algo_ops->gw.print) {
505                 seq_puts(seq,
506                          "No printing function for this routing protocol\n");
507                 return 0;
508         }
509 
510         bat_priv->algo_ops->gw.print(bat_priv, seq);
511 
512         return 0;
513 }
514 #endif
515 
516 /**
517  * batadv_gw_dump - Dump gateways into a message
518  * @msg: Netlink message to dump into
519  * @cb: Control block containing additional options
520  *
521  * Return: Error code, or length of message
522  */
523 int batadv_gw_dump(struct sk_buff *msg, struct netlink_callback *cb)
524 {
525         struct batadv_hard_iface *primary_if = NULL;
526         struct net *net = sock_net(cb->skb->sk);
527         struct net_device *soft_iface;
528         struct batadv_priv *bat_priv;
529         int ifindex;
530         int ret;
531 
532         ifindex = batadv_netlink_get_ifindex(cb->nlh,
533                                              BATADV_ATTR_MESH_IFINDEX);
534         if (!ifindex)
535                 return -EINVAL;
536 
537         soft_iface = dev_get_by_index(net, ifindex);
538         if (!soft_iface || !batadv_softif_is_valid(soft_iface)) {
539                 ret = -ENODEV;
540                 goto out;
541         }
542 
543         bat_priv = netdev_priv(soft_iface);
544 
545         primary_if = batadv_primary_if_get_selected(bat_priv);
546         if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
547                 ret = -ENOENT;
548                 goto out;
549         }
550 
551         if (!bat_priv->algo_ops->gw.dump) {
552                 ret = -EOPNOTSUPP;
553                 goto out;
554         }
555 
556         bat_priv->algo_ops->gw.dump(msg, cb, bat_priv);
557 
558         ret = msg->len;
559 
560 out:
561         if (primary_if)
562                 batadv_hardif_put(primary_if);
563         if (soft_iface)
564                 dev_put(soft_iface);
565 
566         return ret;
567 }
568 
569 /**
570  * batadv_gw_dhcp_recipient_get - check if a packet is a DHCP message
571  * @skb: the packet to check
572  * @header_len: a pointer to the batman-adv header size
573  * @chaddr: buffer where the client address will be stored. Valid
574  *  only if the function returns BATADV_DHCP_TO_CLIENT
575  *
576  * This function may re-allocate the data buffer of the skb passed as argument.
577  *
578  * Return:
579  * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error
580  *   while parsing it
581  * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server
582  * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client
583  */
584 enum batadv_dhcp_recipient
585 batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
586                              u8 *chaddr)
587 {
588         enum batadv_dhcp_recipient ret = BATADV_DHCP_NO;
589         struct ethhdr *ethhdr;
590         struct iphdr *iphdr;
591         struct ipv6hdr *ipv6hdr;
592         struct udphdr *udphdr;
593         struct vlan_ethhdr *vhdr;
594         int chaddr_offset;
595         __be16 proto;
596         u8 *p;
597 
598         /* check for ethernet header */
599         if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
600                 return BATADV_DHCP_NO;
601 
602         ethhdr = eth_hdr(skb);
603         proto = ethhdr->h_proto;
604         *header_len += ETH_HLEN;
605 
606         /* check for initial vlan header */
607         if (proto == htons(ETH_P_8021Q)) {
608                 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
609                         return BATADV_DHCP_NO;
610 
611                 vhdr = vlan_eth_hdr(skb);
612                 proto = vhdr->h_vlan_encapsulated_proto;
613                 *header_len += VLAN_HLEN;
614         }
615 
616         /* check for ip header */
617         switch (proto) {
618         case htons(ETH_P_IP):
619                 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
620                         return BATADV_DHCP_NO;
621 
622                 iphdr = (struct iphdr *)(skb->data + *header_len);
623                 *header_len += iphdr->ihl * 4;
624 
625                 /* check for udp header */
626                 if (iphdr->protocol != IPPROTO_UDP)
627                         return BATADV_DHCP_NO;
628 
629                 break;
630         case htons(ETH_P_IPV6):
631                 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
632                         return BATADV_DHCP_NO;
633 
634                 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
635                 *header_len += sizeof(*ipv6hdr);
636 
637                 /* check for udp header */
638                 if (ipv6hdr->nexthdr != IPPROTO_UDP)
639                         return BATADV_DHCP_NO;
640 
641                 break;
642         default:
643                 return BATADV_DHCP_NO;
644         }
645 
646         if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
647                 return BATADV_DHCP_NO;
648 
649         udphdr = (struct udphdr *)(skb->data + *header_len);
650         *header_len += sizeof(*udphdr);
651 
652         /* check for bootp port */
653         switch (proto) {
654         case htons(ETH_P_IP):
655                 if (udphdr->dest == htons(67))
656                         ret = BATADV_DHCP_TO_SERVER;
657                 else if (udphdr->source == htons(67))
658                         ret = BATADV_DHCP_TO_CLIENT;
659                 break;
660         case htons(ETH_P_IPV6):
661                 if (udphdr->dest == htons(547))
662                         ret = BATADV_DHCP_TO_SERVER;
663                 else if (udphdr->source == htons(547))
664                         ret = BATADV_DHCP_TO_CLIENT;
665                 break;
666         }
667 
668         chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET;
669         /* store the client address if the message is going to a client */
670         if (ret == BATADV_DHCP_TO_CLIENT &&
671             pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) {
672                 /* check if the DHCP packet carries an Ethernet DHCP */
673                 p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET;
674                 if (*p != BATADV_DHCP_HTYPE_ETHERNET)
675                         return BATADV_DHCP_NO;
676 
677                 /* check if the DHCP packet carries a valid Ethernet address */
678                 p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET;
679                 if (*p != ETH_ALEN)
680                         return BATADV_DHCP_NO;
681 
682                 ether_addr_copy(chaddr, skb->data + chaddr_offset);
683         }
684 
685         return ret;
686 }
687 
688 /**
689  * batadv_gw_out_of_range - check if the dhcp request destination is the best gw
690  * @bat_priv: the bat priv with all the soft interface information
691  * @skb: the outgoing packet
692  *
693  * Check if the skb is a DHCP request and if it is sent to the current best GW
694  * server. Due to topology changes it may be the case that the GW server
695  * previously selected is not the best one anymore.
696  *
697  * This call might reallocate skb data.
698  * Must be invoked only when the DHCP packet is going TO a DHCP SERVER.
699  *
700  * Return: true if the packet destination is unicast and it is not the best gw,
701  * false otherwise.
702  */
703 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
704                             struct sk_buff *skb)
705 {
706         struct batadv_neigh_node *neigh_curr = NULL;
707         struct batadv_neigh_node *neigh_old = NULL;
708         struct batadv_orig_node *orig_dst_node;
709         struct batadv_gw_node *gw_node = NULL;
710         struct batadv_gw_node *curr_gw = NULL;
711         struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo;
712         struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
713         bool out_of_range = false;
714         u8 curr_tq_avg;
715         unsigned short vid;
716 
717         vid = batadv_get_vid(skb, 0);
718 
719         orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
720                                                  ethhdr->h_dest, vid);
721         if (!orig_dst_node)
722                 goto out;
723 
724         gw_node = batadv_gw_node_get(bat_priv, orig_dst_node);
725         if (!gw_node)
726                 goto out;
727 
728         switch (atomic_read(&bat_priv->gw.mode)) {
729         case BATADV_GW_MODE_SERVER:
730                 /* If we are a GW then we are our best GW. We can artificially
731                  * set the tq towards ourself as the maximum value
732                  */
733                 curr_tq_avg = BATADV_TQ_MAX_VALUE;
734                 break;
735         case BATADV_GW_MODE_CLIENT:
736                 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
737                 if (!curr_gw)
738                         goto out;
739 
740                 /* packet is going to our gateway */
741                 if (curr_gw->orig_node == orig_dst_node)
742                         goto out;
743 
744                 /* If the dhcp packet has been sent to a different gw,
745                  * we have to evaluate whether the old gw is still
746                  * reliable enough
747                  */
748                 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
749                                                 NULL);
750                 if (!neigh_curr)
751                         goto out;
752 
753                 curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr,
754                                                       BATADV_IF_DEFAULT);
755                 if (!curr_ifinfo)
756                         goto out;
757 
758                 curr_tq_avg = curr_ifinfo->bat_iv.tq_avg;
759                 batadv_neigh_ifinfo_put(curr_ifinfo);
760 
761                 break;
762         case BATADV_GW_MODE_OFF:
763         default:
764                 goto out;
765         }
766 
767         neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
768         if (!neigh_old)
769                 goto out;
770 
771         old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT);
772         if (!old_ifinfo)
773                 goto out;
774 
775         if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD)
776                 out_of_range = true;
777         batadv_neigh_ifinfo_put(old_ifinfo);
778 
779 out:
780         if (orig_dst_node)
781                 batadv_orig_node_put(orig_dst_node);
782         if (curr_gw)
783                 batadv_gw_node_put(curr_gw);
784         if (gw_node)
785                 batadv_gw_node_put(gw_node);
786         if (neigh_old)
787                 batadv_neigh_node_put(neigh_old);
788         if (neigh_curr)
789                 batadv_neigh_node_put(neigh_curr);
790         return out_of_range;
791 }
792 

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