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