1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) 2009-2018 B.A.T.M.A.N. contributors:
3 *
4 * Marek Lindner
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, see <http://www.gnu.org/licenses/>.
17 */
18
19 #include "gateway_client.h"
20 #include "main.h"
21
22 #include <linux/atomic.h>
23 #include <linux/byteorder/generic.h>
24 #include <linux/errno.h>
25 #include <linux/etherdevice.h>
26 #include <linux/gfp.h>
27 #include <linux/if_ether.h>
28 #include <linux/if_vlan.h>
29 #include <linux/in.h>
30 #include <linux/ip.h>
31 #include <linux/ipv6.h>
32 #include <linux/kernel.h>
33 #include <linux/kref.h>
34 #include <linux/list.h>
35 #include <linux/lockdep.h>
36 #include <linux/netdevice.h>
37 #include <linux/netlink.h>
38 #include <linux/rculist.h>
39 #include <linux/rcupdate.h>
40 #include <linux/seq_file.h>
41 #include <linux/skbuff.h>
42 #include <linux/slab.h>
43 #include <linux/spinlock.h>
44 #include <linux/stddef.h>
45 #include <linux/udp.h>
46 #include <net/sock.h>
47 #include <uapi/linux/batadv_packet.h>
48 #include <uapi/linux/batman_adv.h>
49
50 #include "gateway_common.h"
51 #include "hard-interface.h"
52 #include "log.h"
53 #include "netlink.h"
54 #include "originator.h"
55 #include "routing.h"
56 #include "soft-interface.h"
57 #include "sysfs.h"
58 #include "translation-table.h"
59
60 /* These are the offsets of the "hw type" and "hw address length" in the dhcp
61 * packet starting at the beginning of the dhcp header
62 */
63 #define BATADV_DHCP_HTYPE_OFFSET 1
64 #define BATADV_DHCP_HLEN_OFFSET 2
65 /* Value of htype representing Ethernet */
66 #define BATADV_DHCP_HTYPE_ETHERNET 0x01
67 /* This is the offset of the "chaddr" field in the dhcp packet starting at the
68 * beginning of the dhcp header
69 */
70 #define BATADV_DHCP_CHADDR_OFFSET 28
71
72 /**
73 * batadv_gw_node_release() - release gw_node from lists and queue for free
74 * after rcu grace period
75 * @ref: kref pointer of the gw_node
76 */
batadv_gw_node_release(struct kref * ref)77 static void batadv_gw_node_release(struct kref *ref)
78 {
79 struct batadv_gw_node *gw_node;
80
81 gw_node = container_of(ref, struct batadv_gw_node, refcount);
82
83 batadv_orig_node_put(gw_node->orig_node);
84 kfree_rcu(gw_node, rcu);
85 }
86
87 /**
88 * batadv_gw_node_put() - decrement the gw_node refcounter and possibly release
89 * it
90 * @gw_node: gateway node to free
91 */
batadv_gw_node_put(struct batadv_gw_node * gw_node)92 void batadv_gw_node_put(struct batadv_gw_node *gw_node)
93 {
94 kref_put(&gw_node->refcount, batadv_gw_node_release);
95 }
96
97 /**
98 * batadv_gw_get_selected_gw_node() - Get currently selected gateway
99 * @bat_priv: the bat priv with all the soft interface information
100 *
101 * Return: selected gateway (with increased refcnt), NULL on errors
102 */
103 struct batadv_gw_node *
batadv_gw_get_selected_gw_node(struct batadv_priv * bat_priv)104 batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
105 {
106 struct batadv_gw_node *gw_node;
107
108 rcu_read_lock();
109 gw_node = rcu_dereference(bat_priv->gw.curr_gw);
110 if (!gw_node)
111 goto out;
112
113 if (!kref_get_unless_zero(&gw_node->refcount))
114 gw_node = NULL;
115
116 out:
117 rcu_read_unlock();
118 return gw_node;
119 }
120
121 /**
122 * batadv_gw_get_selected_orig() - Get originator of currently selected gateway
123 * @bat_priv: the bat priv with all the soft interface information
124 *
125 * Return: orig_node of selected gateway (with increased refcnt), NULL on errors
126 */
127 struct batadv_orig_node *
batadv_gw_get_selected_orig(struct batadv_priv * bat_priv)128 batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
129 {
130 struct batadv_gw_node *gw_node;
131 struct batadv_orig_node *orig_node = NULL;
132
133 gw_node = batadv_gw_get_selected_gw_node(bat_priv);
134 if (!gw_node)
135 goto out;
136
137 rcu_read_lock();
138 orig_node = gw_node->orig_node;
139 if (!orig_node)
140 goto unlock;
141
142 if (!kref_get_unless_zero(&orig_node->refcount))
143 orig_node = NULL;
144
145 unlock:
146 rcu_read_unlock();
147 out:
148 if (gw_node)
149 batadv_gw_node_put(gw_node);
150 return orig_node;
151 }
152
batadv_gw_select(struct batadv_priv * bat_priv,struct batadv_gw_node * new_gw_node)153 static void batadv_gw_select(struct batadv_priv *bat_priv,
154 struct batadv_gw_node *new_gw_node)
155 {
156 struct batadv_gw_node *curr_gw_node;
157
158 spin_lock_bh(&bat_priv->gw.list_lock);
159
160 if (new_gw_node)
161 kref_get(&new_gw_node->refcount);
162
163 curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
164 rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);
165
166 if (curr_gw_node)
167 batadv_gw_node_put(curr_gw_node);
168
169 spin_unlock_bh(&bat_priv->gw.list_lock);
170 }
171
172 /**
173 * batadv_gw_reselect() - force a gateway reselection
174 * @bat_priv: the bat priv with all the soft interface information
175 *
176 * Set a flag to remind the GW component to perform a new gateway reselection.
177 * However this function does not ensure that the current gateway is going to be
178 * deselected. The reselection mechanism may elect the same gateway once again.
179 *
180 * This means that invoking batadv_gw_reselect() does not guarantee a gateway
181 * change and therefore a uevent is not necessarily expected.
182 */
batadv_gw_reselect(struct batadv_priv * bat_priv)183 void batadv_gw_reselect(struct batadv_priv *bat_priv)
184 {
185 atomic_set(&bat_priv->gw.reselect, 1);
186 }
187
188 /**
189 * batadv_gw_check_client_stop() - check if client mode has been switched off
190 * @bat_priv: the bat priv with all the soft interface information
191 *
192 * This function assumes the caller has checked that the gw state *is actually
193 * changing*. This function is not supposed to be called when there is no state
194 * change.
195 */
batadv_gw_check_client_stop(struct batadv_priv * bat_priv)196 void batadv_gw_check_client_stop(struct batadv_priv *bat_priv)
197 {
198 struct batadv_gw_node *curr_gw;
199
200 if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT)
201 return;
202
203 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
204 if (!curr_gw)
205 return;
206
207 /* deselect the current gateway so that next time that client mode is
208 * enabled a proper GW_ADD event can be sent
209 */
210 batadv_gw_select(bat_priv, NULL);
211
212 /* if batman-adv is switching the gw client mode off and a gateway was
213 * already selected, send a DEL uevent
214 */
215 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL);
216
217 batadv_gw_node_put(curr_gw);
218 }
219
220 /**
221 * batadv_gw_election() - Elect the best gateway
222 * @bat_priv: the bat priv with all the soft interface information
223 */
batadv_gw_election(struct batadv_priv * bat_priv)224 void batadv_gw_election(struct batadv_priv *bat_priv)
225 {
226 struct batadv_gw_node *curr_gw = NULL;
227 struct batadv_gw_node *next_gw = NULL;
228 struct batadv_neigh_node *router = NULL;
229 struct batadv_neigh_ifinfo *router_ifinfo = NULL;
230 char gw_addr[18] = { '\0' };
231
232 if (atomic_read(&bat_priv->gw.mode) != BATADV_GW_MODE_CLIENT)
233 goto out;
234
235 if (!bat_priv->algo_ops->gw.get_best_gw_node)
236 goto out;
237
238 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
239
240 if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
241 goto out;
242
243 /* if gw.reselect is set to 1 it means that a previous call to
244 * gw.is_eligible() said that we have a new best GW, therefore it can
245 * now be picked from the list and selected
246 */
247 next_gw = bat_priv->algo_ops->gw.get_best_gw_node(bat_priv);
248
249 if (curr_gw == next_gw)
250 goto out;
251
252 if (next_gw) {
253 sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
254
255 router = batadv_orig_router_get(next_gw->orig_node,
256 BATADV_IF_DEFAULT);
257 if (!router) {
258 batadv_gw_reselect(bat_priv);
259 goto out;
260 }
261
262 router_ifinfo = batadv_neigh_ifinfo_get(router,
263 BATADV_IF_DEFAULT);
264 if (!router_ifinfo) {
265 batadv_gw_reselect(bat_priv);
266 goto out;
267 }
268 }
269
270 if (curr_gw && !next_gw) {
271 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
272 "Removing selected gateway - no gateway in range\n");
273 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
274 NULL);
275 } else if (!curr_gw && next_gw) {
276 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
277 "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
278 next_gw->orig_node->orig,
279 next_gw->bandwidth_down / 10,
280 next_gw->bandwidth_down % 10,
281 next_gw->bandwidth_up / 10,
282 next_gw->bandwidth_up % 10,
283 router_ifinfo->bat_iv.tq_avg);
284 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
285 gw_addr);
286 } else {
287 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
288 "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
289 next_gw->orig_node->orig,
290 next_gw->bandwidth_down / 10,
291 next_gw->bandwidth_down % 10,
292 next_gw->bandwidth_up / 10,
293 next_gw->bandwidth_up % 10,
294 router_ifinfo->bat_iv.tq_avg);
295 batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
296 gw_addr);
297 }
298
299 batadv_gw_select(bat_priv, next_gw);
300
301 out:
302 if (curr_gw)
303 batadv_gw_node_put(curr_gw);
304 if (next_gw)
305 batadv_gw_node_put(next_gw);
306 if (router)
307 batadv_neigh_node_put(router);
308 if (router_ifinfo)
309 batadv_neigh_ifinfo_put(router_ifinfo);
310 }
311
312 /**
313 * batadv_gw_check_election() - Elect orig node as best gateway when eligible
314 * @bat_priv: the bat priv with all the soft interface information
315 * @orig_node: orig node which is to be checked
316 */
batadv_gw_check_election(struct batadv_priv * bat_priv,struct batadv_orig_node * orig_node)317 void batadv_gw_check_election(struct batadv_priv *bat_priv,
318 struct batadv_orig_node *orig_node)
319 {
320 struct batadv_orig_node *curr_gw_orig;
321
322 /* abort immediately if the routing algorithm does not support gateway
323 * election
324 */
325 if (!bat_priv->algo_ops->gw.is_eligible)
326 return;
327
328 curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
329 if (!curr_gw_orig)
330 goto reselect;
331
332 /* this node already is the gateway */
333 if (curr_gw_orig == orig_node)
334 goto out;
335
336 if (!bat_priv->algo_ops->gw.is_eligible(bat_priv, curr_gw_orig,
337 orig_node))
338 goto out;
339
340 reselect:
341 batadv_gw_reselect(bat_priv);
342 out:
343 if (curr_gw_orig)
344 batadv_orig_node_put(curr_gw_orig);
345 }
346
347 /**
348 * batadv_gw_node_add() - add gateway node to list of available gateways
349 * @bat_priv: the bat priv with all the soft interface information
350 * @orig_node: originator announcing gateway capabilities
351 * @gateway: announced bandwidth information
352 *
353 * Has to be called with the appropriate locks being acquired
354 * (gw.list_lock).
355 */
batadv_gw_node_add(struct batadv_priv * bat_priv,struct batadv_orig_node * orig_node,struct batadv_tvlv_gateway_data * gateway)356 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
357 struct batadv_orig_node *orig_node,
358 struct batadv_tvlv_gateway_data *gateway)
359 {
360 struct batadv_gw_node *gw_node;
361
362 lockdep_assert_held(&bat_priv->gw.list_lock);
363
364 if (gateway->bandwidth_down == 0)
365 return;
366
367 gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
368 if (!gw_node)
369 return;
370
371 kref_init(&gw_node->refcount);
372 INIT_HLIST_NODE(&gw_node->list);
373 kref_get(&orig_node->refcount);
374 gw_node->orig_node = orig_node;
375 gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
376 gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
377
378 kref_get(&gw_node->refcount);
379 hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.gateway_list);
380
381 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
382 "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n",
383 orig_node->orig,
384 ntohl(gateway->bandwidth_down) / 10,
385 ntohl(gateway->bandwidth_down) % 10,
386 ntohl(gateway->bandwidth_up) / 10,
387 ntohl(gateway->bandwidth_up) % 10);
388
389 /* don't return reference to new gw_node */
390 batadv_gw_node_put(gw_node);
391 }
392
393 /**
394 * batadv_gw_node_get() - retrieve gateway node from list of available gateways
395 * @bat_priv: the bat priv with all the soft interface information
396 * @orig_node: originator announcing gateway capabilities
397 *
398 * Return: gateway node if found or NULL otherwise.
399 */
batadv_gw_node_get(struct batadv_priv * bat_priv,struct batadv_orig_node * orig_node)400 struct batadv_gw_node *batadv_gw_node_get(struct batadv_priv *bat_priv,
401 struct batadv_orig_node *orig_node)
402 {
403 struct batadv_gw_node *gw_node_tmp, *gw_node = NULL;
404
405 rcu_read_lock();
406 hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.gateway_list,
407 list) {
408 if (gw_node_tmp->orig_node != orig_node)
409 continue;
410
411 if (!kref_get_unless_zero(&gw_node_tmp->refcount))
412 continue;
413
414 gw_node = gw_node_tmp;
415 break;
416 }
417 rcu_read_unlock();
418
419 return gw_node;
420 }
421
422 /**
423 * batadv_gw_node_update() - update list of available gateways with changed
424 * bandwidth information
425 * @bat_priv: the bat priv with all the soft interface information
426 * @orig_node: originator announcing gateway capabilities
427 * @gateway: announced bandwidth information
428 */
batadv_gw_node_update(struct batadv_priv * bat_priv,struct batadv_orig_node * orig_node,struct batadv_tvlv_gateway_data * gateway)429 void batadv_gw_node_update(struct batadv_priv *bat_priv,
430 struct batadv_orig_node *orig_node,
431 struct batadv_tvlv_gateway_data *gateway)
432 {
433 struct batadv_gw_node *gw_node, *curr_gw = NULL;
434
435 spin_lock_bh(&bat_priv->gw.list_lock);
436 gw_node = batadv_gw_node_get(bat_priv, orig_node);
437 if (!gw_node) {
438 batadv_gw_node_add(bat_priv, orig_node, gateway);
439 spin_unlock_bh(&bat_priv->gw.list_lock);
440 goto out;
441 }
442 spin_unlock_bh(&bat_priv->gw.list_lock);
443
444 if (gw_node->bandwidth_down == ntohl(gateway->bandwidth_down) &&
445 gw_node->bandwidth_up == ntohl(gateway->bandwidth_up))
446 goto out;
447
448 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
449 "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n",
450 orig_node->orig,
451 gw_node->bandwidth_down / 10,
452 gw_node->bandwidth_down % 10,
453 gw_node->bandwidth_up / 10,
454 gw_node->bandwidth_up % 10,
455 ntohl(gateway->bandwidth_down) / 10,
456 ntohl(gateway->bandwidth_down) % 10,
457 ntohl(gateway->bandwidth_up) / 10,
458 ntohl(gateway->bandwidth_up) % 10);
459
460 gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
461 gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
462
463 if (ntohl(gateway->bandwidth_down) == 0) {
464 batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
465 "Gateway %pM removed from gateway list\n",
466 orig_node->orig);
467
468 /* Note: We don't need a NULL check here, since curr_gw never
469 * gets dereferenced.
470 */
471 spin_lock_bh(&bat_priv->gw.list_lock);
472 if (!hlist_unhashed(&gw_node->list)) {
473 hlist_del_init_rcu(&gw_node->list);
474 batadv_gw_node_put(gw_node);
475 }
476 spin_unlock_bh(&bat_priv->gw.list_lock);
477
478 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
479 if (gw_node == curr_gw)
480 batadv_gw_reselect(bat_priv);
481
482 if (curr_gw)
483 batadv_gw_node_put(curr_gw);
484 }
485
486 out:
487 if (gw_node)
488 batadv_gw_node_put(gw_node);
489 }
490
491 /**
492 * batadv_gw_node_delete() - Remove orig_node from gateway list
493 * @bat_priv: the bat priv with all the soft interface information
494 * @orig_node: orig node which is currently in process of being removed
495 */
batadv_gw_node_delete(struct batadv_priv * bat_priv,struct batadv_orig_node * orig_node)496 void batadv_gw_node_delete(struct batadv_priv *bat_priv,
497 struct batadv_orig_node *orig_node)
498 {
499 struct batadv_tvlv_gateway_data gateway;
500
501 gateway.bandwidth_down = 0;
502 gateway.bandwidth_up = 0;
503
504 batadv_gw_node_update(bat_priv, orig_node, &gateway);
505 }
506
507 /**
508 * batadv_gw_node_free() - Free gateway information from soft interface
509 * @bat_priv: the bat priv with all the soft interface information
510 */
batadv_gw_node_free(struct batadv_priv * bat_priv)511 void batadv_gw_node_free(struct batadv_priv *bat_priv)
512 {
513 struct batadv_gw_node *gw_node;
514 struct hlist_node *node_tmp;
515
516 spin_lock_bh(&bat_priv->gw.list_lock);
517 hlist_for_each_entry_safe(gw_node, node_tmp,
518 &bat_priv->gw.gateway_list, list) {
519 hlist_del_init_rcu(&gw_node->list);
520 batadv_gw_node_put(gw_node);
521 }
522 spin_unlock_bh(&bat_priv->gw.list_lock);
523 }
524
525 #ifdef CONFIG_BATMAN_ADV_DEBUGFS
526
527 /**
528 * batadv_gw_client_seq_print_text() - Print the gateway table in a seq file
529 * @seq: seq file to print on
530 * @offset: not used
531 *
532 * Return: always 0
533 */
batadv_gw_client_seq_print_text(struct seq_file * seq,void * offset)534 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
535 {
536 struct net_device *net_dev = (struct net_device *)seq->private;
537 struct batadv_priv *bat_priv = netdev_priv(net_dev);
538 struct batadv_hard_iface *primary_if;
539
540 primary_if = batadv_seq_print_text_primary_if_get(seq);
541 if (!primary_if)
542 return 0;
543
544 seq_printf(seq, "[B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s %s)]\n",
545 BATADV_SOURCE_VERSION, primary_if->net_dev->name,
546 primary_if->net_dev->dev_addr, net_dev->name,
547 bat_priv->algo_ops->name);
548
549 batadv_hardif_put(primary_if);
550
551 if (!bat_priv->algo_ops->gw.print) {
552 seq_puts(seq,
553 "No printing function for this routing protocol\n");
554 return 0;
555 }
556
557 bat_priv->algo_ops->gw.print(bat_priv, seq);
558
559 return 0;
560 }
561 #endif
562
563 /**
564 * batadv_gw_dump() - Dump gateways into a message
565 * @msg: Netlink message to dump into
566 * @cb: Control block containing additional options
567 *
568 * Return: Error code, or length of message
569 */
batadv_gw_dump(struct sk_buff * msg,struct netlink_callback * cb)570 int batadv_gw_dump(struct sk_buff *msg, struct netlink_callback *cb)
571 {
572 struct batadv_hard_iface *primary_if = NULL;
573 struct net *net = sock_net(cb->skb->sk);
574 struct net_device *soft_iface;
575 struct batadv_priv *bat_priv;
576 int ifindex;
577 int ret;
578
579 ifindex = batadv_netlink_get_ifindex(cb->nlh,
580 BATADV_ATTR_MESH_IFINDEX);
581 if (!ifindex)
582 return -EINVAL;
583
584 soft_iface = dev_get_by_index(net, ifindex);
585 if (!soft_iface || !batadv_softif_is_valid(soft_iface)) {
586 ret = -ENODEV;
587 goto out;
588 }
589
590 bat_priv = netdev_priv(soft_iface);
591
592 primary_if = batadv_primary_if_get_selected(bat_priv);
593 if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
594 ret = -ENOENT;
595 goto out;
596 }
597
598 if (!bat_priv->algo_ops->gw.dump) {
599 ret = -EOPNOTSUPP;
600 goto out;
601 }
602
603 bat_priv->algo_ops->gw.dump(msg, cb, bat_priv);
604
605 ret = msg->len;
606
607 out:
608 if (primary_if)
609 batadv_hardif_put(primary_if);
610 if (soft_iface)
611 dev_put(soft_iface);
612
613 return ret;
614 }
615
616 /**
617 * batadv_gw_dhcp_recipient_get() - check if a packet is a DHCP message
618 * @skb: the packet to check
619 * @header_len: a pointer to the batman-adv header size
620 * @chaddr: buffer where the client address will be stored. Valid
621 * only if the function returns BATADV_DHCP_TO_CLIENT
622 *
623 * This function may re-allocate the data buffer of the skb passed as argument.
624 *
625 * Return:
626 * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error
627 * while parsing it
628 * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server
629 * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client
630 */
631 enum batadv_dhcp_recipient
batadv_gw_dhcp_recipient_get(struct sk_buff * skb,unsigned int * header_len,u8 * chaddr)632 batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
633 u8 *chaddr)
634 {
635 enum batadv_dhcp_recipient ret = BATADV_DHCP_NO;
636 struct ethhdr *ethhdr;
637 struct iphdr *iphdr;
638 struct ipv6hdr *ipv6hdr;
639 struct udphdr *udphdr;
640 struct vlan_ethhdr *vhdr;
641 int chaddr_offset;
642 __be16 proto;
643 u8 *p;
644
645 /* check for ethernet header */
646 if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
647 return BATADV_DHCP_NO;
648
649 ethhdr = eth_hdr(skb);
650 proto = ethhdr->h_proto;
651 *header_len += ETH_HLEN;
652
653 /* check for initial vlan header */
654 if (proto == htons(ETH_P_8021Q)) {
655 if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
656 return BATADV_DHCP_NO;
657
658 vhdr = vlan_eth_hdr(skb);
659 proto = vhdr->h_vlan_encapsulated_proto;
660 *header_len += VLAN_HLEN;
661 }
662
663 /* check for ip header */
664 switch (proto) {
665 case htons(ETH_P_IP):
666 if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
667 return BATADV_DHCP_NO;
668
669 iphdr = (struct iphdr *)(skb->data + *header_len);
670 *header_len += iphdr->ihl * 4;
671
672 /* check for udp header */
673 if (iphdr->protocol != IPPROTO_UDP)
674 return BATADV_DHCP_NO;
675
676 break;
677 case htons(ETH_P_IPV6):
678 if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
679 return BATADV_DHCP_NO;
680
681 ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
682 *header_len += sizeof(*ipv6hdr);
683
684 /* check for udp header */
685 if (ipv6hdr->nexthdr != IPPROTO_UDP)
686 return BATADV_DHCP_NO;
687
688 break;
689 default:
690 return BATADV_DHCP_NO;
691 }
692
693 if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
694 return BATADV_DHCP_NO;
695
696 udphdr = (struct udphdr *)(skb->data + *header_len);
697 *header_len += sizeof(*udphdr);
698
699 /* check for bootp port */
700 switch (proto) {
701 case htons(ETH_P_IP):
702 if (udphdr->dest == htons(67))
703 ret = BATADV_DHCP_TO_SERVER;
704 else if (udphdr->source == htons(67))
705 ret = BATADV_DHCP_TO_CLIENT;
706 break;
707 case htons(ETH_P_IPV6):
708 if (udphdr->dest == htons(547))
709 ret = BATADV_DHCP_TO_SERVER;
710 else if (udphdr->source == htons(547))
711 ret = BATADV_DHCP_TO_CLIENT;
712 break;
713 }
714
715 chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET;
716 /* store the client address if the message is going to a client */
717 if (ret == BATADV_DHCP_TO_CLIENT &&
718 pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) {
719 /* check if the DHCP packet carries an Ethernet DHCP */
720 p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET;
721 if (*p != BATADV_DHCP_HTYPE_ETHERNET)
722 return BATADV_DHCP_NO;
723
724 /* check if the DHCP packet carries a valid Ethernet address */
725 p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET;
726 if (*p != ETH_ALEN)
727 return BATADV_DHCP_NO;
728
729 ether_addr_copy(chaddr, skb->data + chaddr_offset);
730 }
731
732 return ret;
733 }
734
735 /**
736 * batadv_gw_out_of_range() - check if the dhcp request destination is the best
737 * gateway
738 * @bat_priv: the bat priv with all the soft interface information
739 * @skb: the outgoing packet
740 *
741 * Check if the skb is a DHCP request and if it is sent to the current best GW
742 * server. Due to topology changes it may be the case that the GW server
743 * previously selected is not the best one anymore.
744 *
745 * This call might reallocate skb data.
746 * Must be invoked only when the DHCP packet is going TO a DHCP SERVER.
747 *
748 * Return: true if the packet destination is unicast and it is not the best gw,
749 * false otherwise.
750 */
batadv_gw_out_of_range(struct batadv_priv * bat_priv,struct sk_buff * skb)751 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
752 struct sk_buff *skb)
753 {
754 struct batadv_neigh_node *neigh_curr = NULL;
755 struct batadv_neigh_node *neigh_old = NULL;
756 struct batadv_orig_node *orig_dst_node = NULL;
757 struct batadv_gw_node *gw_node = NULL;
758 struct batadv_gw_node *curr_gw = NULL;
759 struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo;
760 struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
761 bool out_of_range = false;
762 u8 curr_tq_avg;
763 unsigned short vid;
764
765 vid = batadv_get_vid(skb, 0);
766
767 if (is_multicast_ether_addr(ethhdr->h_dest))
768 goto out;
769
770 orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
771 ethhdr->h_dest, vid);
772 if (!orig_dst_node)
773 goto out;
774
775 gw_node = batadv_gw_node_get(bat_priv, orig_dst_node);
776 if (!gw_node)
777 goto out;
778
779 switch (atomic_read(&bat_priv->gw.mode)) {
780 case BATADV_GW_MODE_SERVER:
781 /* If we are a GW then we are our best GW. We can artificially
782 * set the tq towards ourself as the maximum value
783 */
784 curr_tq_avg = BATADV_TQ_MAX_VALUE;
785 break;
786 case BATADV_GW_MODE_CLIENT:
787 curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
788 if (!curr_gw)
789 goto out;
790
791 /* packet is going to our gateway */
792 if (curr_gw->orig_node == orig_dst_node)
793 goto out;
794
795 /* If the dhcp packet has been sent to a different gw,
796 * we have to evaluate whether the old gw is still
797 * reliable enough
798 */
799 neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
800 NULL);
801 if (!neigh_curr)
802 goto out;
803
804 curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr,
805 BATADV_IF_DEFAULT);
806 if (!curr_ifinfo)
807 goto out;
808
809 curr_tq_avg = curr_ifinfo->bat_iv.tq_avg;
810 batadv_neigh_ifinfo_put(curr_ifinfo);
811
812 break;
813 case BATADV_GW_MODE_OFF:
814 default:
815 goto out;
816 }
817
818 neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
819 if (!neigh_old)
820 goto out;
821
822 old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT);
823 if (!old_ifinfo)
824 goto out;
825
826 if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD)
827 out_of_range = true;
828 batadv_neigh_ifinfo_put(old_ifinfo);
829
830 out:
831 if (orig_dst_node)
832 batadv_orig_node_put(orig_dst_node);
833 if (curr_gw)
834 batadv_gw_node_put(curr_gw);
835 if (gw_node)
836 batadv_gw_node_put(gw_node);
837 if (neigh_old)
838 batadv_neigh_node_put(neigh_old);
839 if (neigh_curr)
840 batadv_neigh_node_put(neigh_curr);
841 return out_of_range;
842 }
843
