1 /* Copyright (C) 2009-2015 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/etherdevice.h>
24 #include <linux/fs.h>
25 #include <linux/if_ether.h>
26 #include <linux/if_vlan.h>
27 #include <linux/in.h>
28 #include <linux/ip.h>
29 #include <linux/ipv6.h>
30 #include <linux/kernel.h>
31 #include <linux/list.h>
32 #include <linux/netdevice.h>
33 #include <linux/rculist.h>
34 #include <linux/rcupdate.h>
35 #include <linux/seq_file.h>
36 #include <linux/skbuff.h>
37 #include <linux/slab.h>
38 #include <linux/spinlock.h>
39 #include <linux/stddef.h>
40 #include <linux/udp.h>
41 
42 #include "gateway_common.h"
43 #include "hard-interface.h"
44 #include "originator.h"
45 #include "packet.h"
46 #include "routing.h"
47 #include "sysfs.h"
48 #include "translation-table.h"
49 
50 /* These are the offsets of the "hw type" and "hw address length" in the dhcp
51  * packet starting at the beginning of the dhcp header
52  */
53 #define BATADV_DHCP_HTYPE_OFFSET	1
54 #define BATADV_DHCP_HLEN_OFFSET		2
55 /* Value of htype representing Ethernet */
56 #define BATADV_DHCP_HTYPE_ETHERNET	0x01
57 /* This is the offset of the "chaddr" field in the dhcp packet starting at the
58  * beginning of the dhcp header
59  */
60 #define BATADV_DHCP_CHADDR_OFFSET	28
61 
62 static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node)
63 {
64 	if (atomic_dec_and_test(&gw_node->refcount)) {
65 		batadv_orig_node_free_ref(gw_node->orig_node);
66 		kfree_rcu(gw_node, rcu);
67 	}
68 }
69 
70 static struct batadv_gw_node *
71 batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
72 {
73 	struct batadv_gw_node *gw_node;
74 
75 	rcu_read_lock();
76 	gw_node = rcu_dereference(bat_priv->gw.curr_gw);
77 	if (!gw_node)
78 		goto out;
79 
80 	if (!atomic_inc_not_zero(&gw_node->refcount))
81 		gw_node = NULL;
82 
83 out:
84 	rcu_read_unlock();
85 	return gw_node;
86 }
87 
88 struct batadv_orig_node *
89 batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
90 {
91 	struct batadv_gw_node *gw_node;
92 	struct batadv_orig_node *orig_node = NULL;
93 
94 	gw_node = batadv_gw_get_selected_gw_node(bat_priv);
95 	if (!gw_node)
96 		goto out;
97 
98 	rcu_read_lock();
99 	orig_node = gw_node->orig_node;
100 	if (!orig_node)
101 		goto unlock;
102 
103 	if (!atomic_inc_not_zero(&orig_node->refcount))
104 		orig_node = NULL;
105 
106 unlock:
107 	rcu_read_unlock();
108 out:
109 	if (gw_node)
110 		batadv_gw_node_free_ref(gw_node);
111 	return orig_node;
112 }
113 
114 static void batadv_gw_select(struct batadv_priv *bat_priv,
115 			     struct batadv_gw_node *new_gw_node)
116 {
117 	struct batadv_gw_node *curr_gw_node;
118 
119 	spin_lock_bh(&bat_priv->gw.list_lock);
120 
121 	if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount))
122 		new_gw_node = NULL;
123 
124 	curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
125 	rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);
126 
127 	if (curr_gw_node)
128 		batadv_gw_node_free_ref(curr_gw_node);
129 
130 	spin_unlock_bh(&bat_priv->gw.list_lock);
131 }
132 
133 /**
134  * batadv_gw_reselect - force a gateway reselection
135  * @bat_priv: the bat priv with all the soft interface information
136  *
137  * Set a flag to remind the GW component to perform a new gateway reselection.
138  * However this function does not ensure that the current gateway is going to be
139  * deselected. The reselection mechanism may elect the same gateway once again.
140  *
141  * This means that invoking batadv_gw_reselect() does not guarantee a gateway
142  * change and therefore a uevent is not necessarily expected.
143  */
144 void batadv_gw_reselect(struct batadv_priv *bat_priv)
145 {
146 	atomic_set(&bat_priv->gw.reselect, 1);
147 }
148 
149 static struct batadv_gw_node *
150 batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
151 {
152 	struct batadv_neigh_node *router;
153 	struct batadv_neigh_ifinfo *router_ifinfo;
154 	struct batadv_gw_node *gw_node, *curr_gw = NULL;
155 	u64 max_gw_factor = 0;
156 	u64 tmp_gw_factor = 0;
157 	u8 max_tq = 0;
158 	u8 tq_avg;
159 	struct batadv_orig_node *orig_node;
160 
161 	rcu_read_lock();
162 	hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
163 		orig_node = gw_node->orig_node;
164 		router = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT);
165 		if (!router)
166 			continue;
167 
168 		router_ifinfo = batadv_neigh_ifinfo_get(router,
169 							BATADV_IF_DEFAULT);
170 		if (!router_ifinfo)
171 			goto next;
172 
173 		if (!atomic_inc_not_zero(&gw_node->refcount))
174 			goto next;
175 
176 		tq_avg = router_ifinfo->bat_iv.tq_avg;
177 
178 		switch (atomic_read(&bat_priv->gw_sel_class)) {
179 		case 1: /* fast connection */
180 			tmp_gw_factor = tq_avg * tq_avg;
181 			tmp_gw_factor *= gw_node->bandwidth_down;
182 			tmp_gw_factor *= 100 * 100;
183 			tmp_gw_factor >>= 18;
184 
185 			if ((tmp_gw_factor > max_gw_factor) ||
186 			    ((tmp_gw_factor == max_gw_factor) &&
187 			     (tq_avg > max_tq))) {
188 				if (curr_gw)
189 					batadv_gw_node_free_ref(curr_gw);
190 				curr_gw = gw_node;
191 				atomic_inc(&curr_gw->refcount);
192 			}
193 			break;
194 
195 		default: /* 2:  stable connection (use best statistic)
196 			  * 3:  fast-switch (use best statistic but change as
197 			  *     soon as a better gateway appears)
198 			  * XX: late-switch (use best statistic but change as
199 			  *     soon as a better gateway appears which has
200 			  *     $routing_class more tq points)
201 			  */
202 			if (tq_avg > max_tq) {
203 				if (curr_gw)
204 					batadv_gw_node_free_ref(curr_gw);
205 				curr_gw = gw_node;
206 				atomic_inc(&curr_gw->refcount);
207 			}
208 			break;
209 		}
210 
211 		if (tq_avg > max_tq)
212 			max_tq = tq_avg;
213 
214 		if (tmp_gw_factor > max_gw_factor)
215 			max_gw_factor = tmp_gw_factor;
216 
217 		batadv_gw_node_free_ref(gw_node);
218 
219 next:
220 		batadv_neigh_node_free_ref(router);
221 		if (router_ifinfo)
222 			batadv_neigh_ifinfo_free_ref(router_ifinfo);
223 	}
224 	rcu_read_unlock();
225 
226 	return curr_gw;
227 }
228 
229 /**
230  * batadv_gw_check_client_stop - check if client mode has been switched off
231  * @bat_priv: the bat priv with all the soft interface information
232  *
233  * This function assumes the caller has checked that the gw state *is actually
234  * changing*. This function is not supposed to be called when there is no state
235  * change.
236  */
237 void batadv_gw_check_client_stop(struct batadv_priv *bat_priv)
238 {
239 	struct batadv_gw_node *curr_gw;
240 
241 	if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
242 		return;
243 
244 	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
245 	if (!curr_gw)
246 		return;
247 
248 	/* deselect the current gateway so that next time that client mode is
249 	 * enabled a proper GW_ADD event can be sent
250 	 */
251 	batadv_gw_select(bat_priv, NULL);
252 
253 	/* if batman-adv is switching the gw client mode off and a gateway was
254 	 * already selected, send a DEL uevent
255 	 */
256 	batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL, NULL);
257 
258 	batadv_gw_node_free_ref(curr_gw);
259 }
260 
261 void batadv_gw_election(struct batadv_priv *bat_priv)
262 {
263 	struct batadv_gw_node *curr_gw = NULL;
264 	struct batadv_gw_node *next_gw = NULL;
265 	struct batadv_neigh_node *router = NULL;
266 	struct batadv_neigh_ifinfo *router_ifinfo = NULL;
267 	char gw_addr[18] = { '\0' };
268 
269 	if (atomic_read(&bat_priv->gw_mode) != BATADV_GW_MODE_CLIENT)
270 		goto out;
271 
272 	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
273 
274 	if (!batadv_atomic_dec_not_zero(&bat_priv->gw.reselect) && curr_gw)
275 		goto out;
276 
277 	next_gw = batadv_gw_get_best_gw_node(bat_priv);
278 
279 	if (curr_gw == next_gw)
280 		goto out;
281 
282 	if (next_gw) {
283 		sprintf(gw_addr, "%pM", next_gw->orig_node->orig);
284 
285 		router = batadv_orig_router_get(next_gw->orig_node,
286 						BATADV_IF_DEFAULT);
287 		if (!router) {
288 			batadv_gw_reselect(bat_priv);
289 			goto out;
290 		}
291 
292 		router_ifinfo = batadv_neigh_ifinfo_get(router,
293 							BATADV_IF_DEFAULT);
294 		if (!router_ifinfo) {
295 			batadv_gw_reselect(bat_priv);
296 			goto out;
297 		}
298 	}
299 
300 	if ((curr_gw) && (!next_gw)) {
301 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
302 			   "Removing selected gateway - no gateway in range\n");
303 		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_DEL,
304 				    NULL);
305 	} else if ((!curr_gw) && (next_gw)) {
306 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
307 			   "Adding route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
308 			   next_gw->orig_node->orig,
309 			   next_gw->bandwidth_down / 10,
310 			   next_gw->bandwidth_down % 10,
311 			   next_gw->bandwidth_up / 10,
312 			   next_gw->bandwidth_up % 10,
313 			   router_ifinfo->bat_iv.tq_avg);
314 		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_ADD,
315 				    gw_addr);
316 	} else {
317 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
318 			   "Changing route to gateway %pM (bandwidth: %u.%u/%u.%u MBit, tq: %i)\n",
319 			   next_gw->orig_node->orig,
320 			   next_gw->bandwidth_down / 10,
321 			   next_gw->bandwidth_down % 10,
322 			   next_gw->bandwidth_up / 10,
323 			   next_gw->bandwidth_up % 10,
324 			   router_ifinfo->bat_iv.tq_avg);
325 		batadv_throw_uevent(bat_priv, BATADV_UEV_GW, BATADV_UEV_CHANGE,
326 				    gw_addr);
327 	}
328 
329 	batadv_gw_select(bat_priv, next_gw);
330 
331 out:
332 	if (curr_gw)
333 		batadv_gw_node_free_ref(curr_gw);
334 	if (next_gw)
335 		batadv_gw_node_free_ref(next_gw);
336 	if (router)
337 		batadv_neigh_node_free_ref(router);
338 	if (router_ifinfo)
339 		batadv_neigh_ifinfo_free_ref(router_ifinfo);
340 }
341 
342 void batadv_gw_check_election(struct batadv_priv *bat_priv,
343 			      struct batadv_orig_node *orig_node)
344 {
345 	struct batadv_neigh_ifinfo *router_orig_tq = NULL;
346 	struct batadv_neigh_ifinfo *router_gw_tq = NULL;
347 	struct batadv_orig_node *curr_gw_orig;
348 	struct batadv_neigh_node *router_gw = NULL;
349 	struct batadv_neigh_node *router_orig = NULL;
350 	u8 gw_tq_avg, orig_tq_avg;
351 
352 	curr_gw_orig = batadv_gw_get_selected_orig(bat_priv);
353 	if (!curr_gw_orig)
354 		goto reselect;
355 
356 	router_gw = batadv_orig_router_get(curr_gw_orig, BATADV_IF_DEFAULT);
357 	if (!router_gw)
358 		goto reselect;
359 
360 	router_gw_tq = batadv_neigh_ifinfo_get(router_gw,
361 					       BATADV_IF_DEFAULT);
362 	if (!router_gw_tq)
363 		goto reselect;
364 
365 	/* this node already is the gateway */
366 	if (curr_gw_orig == orig_node)
367 		goto out;
368 
369 	router_orig = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT);
370 	if (!router_orig)
371 		goto out;
372 
373 	router_orig_tq = batadv_neigh_ifinfo_get(router_orig,
374 						 BATADV_IF_DEFAULT);
375 	if (!router_orig_tq)
376 		goto out;
377 
378 	gw_tq_avg = router_gw_tq->bat_iv.tq_avg;
379 	orig_tq_avg = router_orig_tq->bat_iv.tq_avg;
380 
381 	/* the TQ value has to be better */
382 	if (orig_tq_avg < gw_tq_avg)
383 		goto out;
384 
385 	/* if the routing class is greater than 3 the value tells us how much
386 	 * greater the TQ value of the new gateway must be
387 	 */
388 	if ((atomic_read(&bat_priv->gw_sel_class) > 3) &&
389 	    (orig_tq_avg - gw_tq_avg < atomic_read(&bat_priv->gw_sel_class)))
390 		goto out;
391 
392 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
393 		   "Restarting gateway selection: better gateway found (tq curr: %i, tq new: %i)\n",
394 		   gw_tq_avg, orig_tq_avg);
395 
396 reselect:
397 	batadv_gw_reselect(bat_priv);
398 out:
399 	if (curr_gw_orig)
400 		batadv_orig_node_free_ref(curr_gw_orig);
401 	if (router_gw)
402 		batadv_neigh_node_free_ref(router_gw);
403 	if (router_orig)
404 		batadv_neigh_node_free_ref(router_orig);
405 	if (router_gw_tq)
406 		batadv_neigh_ifinfo_free_ref(router_gw_tq);
407 	if (router_orig_tq)
408 		batadv_neigh_ifinfo_free_ref(router_orig_tq);
409 }
410 
411 /**
412  * batadv_gw_node_add - add gateway node to list of available gateways
413  * @bat_priv: the bat priv with all the soft interface information
414  * @orig_node: originator announcing gateway capabilities
415  * @gateway: announced bandwidth information
416  */
417 static void batadv_gw_node_add(struct batadv_priv *bat_priv,
418 			       struct batadv_orig_node *orig_node,
419 			       struct batadv_tvlv_gateway_data *gateway)
420 {
421 	struct batadv_gw_node *gw_node;
422 
423 	if (gateway->bandwidth_down == 0)
424 		return;
425 
426 	if (!atomic_inc_not_zero(&orig_node->refcount))
427 		return;
428 
429 	gw_node = kzalloc(sizeof(*gw_node), GFP_ATOMIC);
430 	if (!gw_node) {
431 		batadv_orig_node_free_ref(orig_node);
432 		return;
433 	}
434 
435 	INIT_HLIST_NODE(&gw_node->list);
436 	gw_node->orig_node = orig_node;
437 	gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
438 	gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
439 	atomic_set(&gw_node->refcount, 1);
440 
441 	spin_lock_bh(&bat_priv->gw.list_lock);
442 	hlist_add_head_rcu(&gw_node->list, &bat_priv->gw.list);
443 	spin_unlock_bh(&bat_priv->gw.list_lock);
444 
445 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
446 		   "Found new gateway %pM -> gw bandwidth: %u.%u/%u.%u MBit\n",
447 		   orig_node->orig,
448 		   ntohl(gateway->bandwidth_down) / 10,
449 		   ntohl(gateway->bandwidth_down) % 10,
450 		   ntohl(gateway->bandwidth_up) / 10,
451 		   ntohl(gateway->bandwidth_up) % 10);
452 }
453 
454 /**
455  * batadv_gw_node_get - retrieve gateway node from list of available gateways
456  * @bat_priv: the bat priv with all the soft interface information
457  * @orig_node: originator announcing gateway capabilities
458  *
459  * Returns gateway node if found or NULL otherwise.
460  */
461 static struct batadv_gw_node *
462 batadv_gw_node_get(struct batadv_priv *bat_priv,
463 		   struct batadv_orig_node *orig_node)
464 {
465 	struct batadv_gw_node *gw_node_tmp, *gw_node = NULL;
466 
467 	rcu_read_lock();
468 	hlist_for_each_entry_rcu(gw_node_tmp, &bat_priv->gw.list, list) {
469 		if (gw_node_tmp->orig_node != orig_node)
470 			continue;
471 
472 		if (!atomic_inc_not_zero(&gw_node_tmp->refcount))
473 			continue;
474 
475 		gw_node = gw_node_tmp;
476 		break;
477 	}
478 	rcu_read_unlock();
479 
480 	return gw_node;
481 }
482 
483 /**
484  * batadv_gw_node_update - update list of available gateways with changed
485  *  bandwidth information
486  * @bat_priv: the bat priv with all the soft interface information
487  * @orig_node: originator announcing gateway capabilities
488  * @gateway: announced bandwidth information
489  */
490 void batadv_gw_node_update(struct batadv_priv *bat_priv,
491 			   struct batadv_orig_node *orig_node,
492 			   struct batadv_tvlv_gateway_data *gateway)
493 {
494 	struct batadv_gw_node *gw_node, *curr_gw = NULL;
495 
496 	gw_node = batadv_gw_node_get(bat_priv, orig_node);
497 	if (!gw_node) {
498 		batadv_gw_node_add(bat_priv, orig_node, gateway);
499 		goto out;
500 	}
501 
502 	if ((gw_node->bandwidth_down == ntohl(gateway->bandwidth_down)) &&
503 	    (gw_node->bandwidth_up == ntohl(gateway->bandwidth_up)))
504 		goto out;
505 
506 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
507 		   "Gateway bandwidth of originator %pM changed from %u.%u/%u.%u MBit to %u.%u/%u.%u MBit\n",
508 		   orig_node->orig,
509 		   gw_node->bandwidth_down / 10,
510 		   gw_node->bandwidth_down % 10,
511 		   gw_node->bandwidth_up / 10,
512 		   gw_node->bandwidth_up % 10,
513 		   ntohl(gateway->bandwidth_down) / 10,
514 		   ntohl(gateway->bandwidth_down) % 10,
515 		   ntohl(gateway->bandwidth_up) / 10,
516 		   ntohl(gateway->bandwidth_up) % 10);
517 
518 	gw_node->bandwidth_down = ntohl(gateway->bandwidth_down);
519 	gw_node->bandwidth_up = ntohl(gateway->bandwidth_up);
520 
521 	if (ntohl(gateway->bandwidth_down) == 0) {
522 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
523 			   "Gateway %pM removed from gateway list\n",
524 			   orig_node->orig);
525 
526 		/* Note: We don't need a NULL check here, since curr_gw never
527 		 * gets dereferenced.
528 		 */
529 		spin_lock_bh(&bat_priv->gw.list_lock);
530 		hlist_del_init_rcu(&gw_node->list);
531 		spin_unlock_bh(&bat_priv->gw.list_lock);
532 
533 		batadv_gw_node_free_ref(gw_node);
534 
535 		curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
536 		if (gw_node == curr_gw)
537 			batadv_gw_reselect(bat_priv);
538 
539 		if (curr_gw)
540 			batadv_gw_node_free_ref(curr_gw);
541 	}
542 
543 out:
544 	if (gw_node)
545 		batadv_gw_node_free_ref(gw_node);
546 }
547 
548 void batadv_gw_node_delete(struct batadv_priv *bat_priv,
549 			   struct batadv_orig_node *orig_node)
550 {
551 	struct batadv_tvlv_gateway_data gateway;
552 
553 	gateway.bandwidth_down = 0;
554 	gateway.bandwidth_up = 0;
555 
556 	batadv_gw_node_update(bat_priv, orig_node, &gateway);
557 }
558 
559 void batadv_gw_node_free(struct batadv_priv *bat_priv)
560 {
561 	struct batadv_gw_node *gw_node;
562 	struct hlist_node *node_tmp;
563 
564 	spin_lock_bh(&bat_priv->gw.list_lock);
565 	hlist_for_each_entry_safe(gw_node, node_tmp,
566 				  &bat_priv->gw.list, list) {
567 		hlist_del_init_rcu(&gw_node->list);
568 		batadv_gw_node_free_ref(gw_node);
569 	}
570 	spin_unlock_bh(&bat_priv->gw.list_lock);
571 }
572 
573 /* fails if orig_node has no router */
574 static int batadv_write_buffer_text(struct batadv_priv *bat_priv,
575 				    struct seq_file *seq,
576 				    const struct batadv_gw_node *gw_node)
577 {
578 	struct batadv_gw_node *curr_gw;
579 	struct batadv_neigh_node *router;
580 	struct batadv_neigh_ifinfo *router_ifinfo = NULL;
581 	int ret = -1;
582 
583 	router = batadv_orig_router_get(gw_node->orig_node, BATADV_IF_DEFAULT);
584 	if (!router)
585 		goto out;
586 
587 	router_ifinfo = batadv_neigh_ifinfo_get(router, BATADV_IF_DEFAULT);
588 	if (!router_ifinfo)
589 		goto out;
590 
591 	curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
592 
593 	seq_printf(seq, "%s %pM (%3i) %pM [%10s]: %u.%u/%u.%u MBit\n",
594 		   (curr_gw == gw_node ? "=>" : "  "),
595 		   gw_node->orig_node->orig,
596 		   router_ifinfo->bat_iv.tq_avg, router->addr,
597 		   router->if_incoming->net_dev->name,
598 		   gw_node->bandwidth_down / 10,
599 		   gw_node->bandwidth_down % 10,
600 		   gw_node->bandwidth_up / 10,
601 		   gw_node->bandwidth_up % 10);
602 	ret = seq_has_overflowed(seq) ? -1 : 0;
603 
604 	if (curr_gw)
605 		batadv_gw_node_free_ref(curr_gw);
606 out:
607 	if (router_ifinfo)
608 		batadv_neigh_ifinfo_free_ref(router_ifinfo);
609 	if (router)
610 		batadv_neigh_node_free_ref(router);
611 	return ret;
612 }
613 
614 int batadv_gw_client_seq_print_text(struct seq_file *seq, void *offset)
615 {
616 	struct net_device *net_dev = (struct net_device *)seq->private;
617 	struct batadv_priv *bat_priv = netdev_priv(net_dev);
618 	struct batadv_hard_iface *primary_if;
619 	struct batadv_gw_node *gw_node;
620 	int gw_count = 0;
621 
622 	primary_if = batadv_seq_print_text_primary_if_get(seq);
623 	if (!primary_if)
624 		goto out;
625 
626 	seq_printf(seq,
627 		   "      %-12s (%s/%i) %17s [%10s]: advertised uplink bandwidth ... [B.A.T.M.A.N. adv %s, MainIF/MAC: %s/%pM (%s)]\n",
628 		   "Gateway", "#", BATADV_TQ_MAX_VALUE, "Nexthop", "outgoingIF",
629 		   BATADV_SOURCE_VERSION, primary_if->net_dev->name,
630 		   primary_if->net_dev->dev_addr, net_dev->name);
631 
632 	rcu_read_lock();
633 	hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
634 		/* fails if orig_node has no router */
635 		if (batadv_write_buffer_text(bat_priv, seq, gw_node) < 0)
636 			continue;
637 
638 		gw_count++;
639 	}
640 	rcu_read_unlock();
641 
642 	if (gw_count == 0)
643 		seq_puts(seq, "No gateways in range ...\n");
644 
645 out:
646 	if (primary_if)
647 		batadv_hardif_free_ref(primary_if);
648 	return 0;
649 }
650 
651 /**
652  * batadv_gw_dhcp_recipient_get - check if a packet is a DHCP message
653  * @skb: the packet to check
654  * @header_len: a pointer to the batman-adv header size
655  * @chaddr: buffer where the client address will be stored. Valid
656  *  only if the function returns BATADV_DHCP_TO_CLIENT
657  *
658  * Returns:
659  * - BATADV_DHCP_NO if the packet is not a dhcp message or if there was an error
660  *   while parsing it
661  * - BATADV_DHCP_TO_SERVER if this is a message going to the DHCP server
662  * - BATADV_DHCP_TO_CLIENT if this is a message going to a DHCP client
663  *
664  * This function may re-allocate the data buffer of the skb passed as argument.
665  */
666 enum batadv_dhcp_recipient
667 batadv_gw_dhcp_recipient_get(struct sk_buff *skb, unsigned int *header_len,
668 			     u8 *chaddr)
669 {
670 	enum batadv_dhcp_recipient ret = BATADV_DHCP_NO;
671 	struct ethhdr *ethhdr;
672 	struct iphdr *iphdr;
673 	struct ipv6hdr *ipv6hdr;
674 	struct udphdr *udphdr;
675 	struct vlan_ethhdr *vhdr;
676 	int chaddr_offset;
677 	__be16 proto;
678 	u8 *p;
679 
680 	/* check for ethernet header */
681 	if (!pskb_may_pull(skb, *header_len + ETH_HLEN))
682 		return BATADV_DHCP_NO;
683 
684 	ethhdr = eth_hdr(skb);
685 	proto = ethhdr->h_proto;
686 	*header_len += ETH_HLEN;
687 
688 	/* check for initial vlan header */
689 	if (proto == htons(ETH_P_8021Q)) {
690 		if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))
691 			return BATADV_DHCP_NO;
692 
693 		vhdr = vlan_eth_hdr(skb);
694 		proto = vhdr->h_vlan_encapsulated_proto;
695 		*header_len += VLAN_HLEN;
696 	}
697 
698 	/* check for ip header */
699 	switch (proto) {
700 	case htons(ETH_P_IP):
701 		if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))
702 			return BATADV_DHCP_NO;
703 
704 		iphdr = (struct iphdr *)(skb->data + *header_len);
705 		*header_len += iphdr->ihl * 4;
706 
707 		/* check for udp header */
708 		if (iphdr->protocol != IPPROTO_UDP)
709 			return BATADV_DHCP_NO;
710 
711 		break;
712 	case htons(ETH_P_IPV6):
713 		if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))
714 			return BATADV_DHCP_NO;
715 
716 		ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
717 		*header_len += sizeof(*ipv6hdr);
718 
719 		/* check for udp header */
720 		if (ipv6hdr->nexthdr != IPPROTO_UDP)
721 			return BATADV_DHCP_NO;
722 
723 		break;
724 	default:
725 		return BATADV_DHCP_NO;
726 	}
727 
728 	if (!pskb_may_pull(skb, *header_len + sizeof(*udphdr)))
729 		return BATADV_DHCP_NO;
730 
731 	udphdr = (struct udphdr *)(skb->data + *header_len);
732 	*header_len += sizeof(*udphdr);
733 
734 	/* check for bootp port */
735 	switch (proto) {
736 	case htons(ETH_P_IP):
737 		if (udphdr->dest == htons(67))
738 			ret = BATADV_DHCP_TO_SERVER;
739 		else if (udphdr->source == htons(67))
740 			ret = BATADV_DHCP_TO_CLIENT;
741 		break;
742 	case htons(ETH_P_IPV6):
743 		if (udphdr->dest == htons(547))
744 			ret = BATADV_DHCP_TO_SERVER;
745 		else if (udphdr->source == htons(547))
746 			ret = BATADV_DHCP_TO_CLIENT;
747 		break;
748 	}
749 
750 	chaddr_offset = *header_len + BATADV_DHCP_CHADDR_OFFSET;
751 	/* store the client address if the message is going to a client */
752 	if (ret == BATADV_DHCP_TO_CLIENT &&
753 	    pskb_may_pull(skb, chaddr_offset + ETH_ALEN)) {
754 		/* check if the DHCP packet carries an Ethernet DHCP */
755 		p = skb->data + *header_len + BATADV_DHCP_HTYPE_OFFSET;
756 		if (*p != BATADV_DHCP_HTYPE_ETHERNET)
757 			return BATADV_DHCP_NO;
758 
759 		/* check if the DHCP packet carries a valid Ethernet address */
760 		p = skb->data + *header_len + BATADV_DHCP_HLEN_OFFSET;
761 		if (*p != ETH_ALEN)
762 			return BATADV_DHCP_NO;
763 
764 		ether_addr_copy(chaddr, skb->data + chaddr_offset);
765 	}
766 
767 	return ret;
768 }
769 
770 /**
771  * batadv_gw_out_of_range - check if the dhcp request destination is the best gw
772  * @bat_priv: the bat priv with all the soft interface information
773  * @skb: the outgoing packet
774  *
775  * Check if the skb is a DHCP request and if it is sent to the current best GW
776  * server. Due to topology changes it may be the case that the GW server
777  * previously selected is not the best one anymore.
778  *
779  * Returns true if the packet destination is unicast and it is not the best gw,
780  * false otherwise.
781  *
782  * This call might reallocate skb data.
783  * Must be invoked only when the DHCP packet is going TO a DHCP SERVER.
784  */
785 bool batadv_gw_out_of_range(struct batadv_priv *bat_priv,
786 			    struct sk_buff *skb)
787 {
788 	struct batadv_neigh_node *neigh_curr = NULL;
789 	struct batadv_neigh_node *neigh_old = NULL;
790 	struct batadv_orig_node *orig_dst_node = NULL;
791 	struct batadv_gw_node *gw_node = NULL;
792 	struct batadv_gw_node *curr_gw = NULL;
793 	struct batadv_neigh_ifinfo *curr_ifinfo, *old_ifinfo;
794 	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
795 	bool out_of_range = false;
796 	u8 curr_tq_avg;
797 	unsigned short vid;
798 
799 	vid = batadv_get_vid(skb, 0);
800 
801 	orig_dst_node = batadv_transtable_search(bat_priv, ethhdr->h_source,
802 						 ethhdr->h_dest, vid);
803 	if (!orig_dst_node)
804 		goto out;
805 
806 	gw_node = batadv_gw_node_get(bat_priv, orig_dst_node);
807 	if (!gw_node)
808 		goto out;
809 
810 	switch (atomic_read(&bat_priv->gw_mode)) {
811 	case BATADV_GW_MODE_SERVER:
812 		/* If we are a GW then we are our best GW. We can artificially
813 		 * set the tq towards ourself as the maximum value
814 		 */
815 		curr_tq_avg = BATADV_TQ_MAX_VALUE;
816 		break;
817 	case BATADV_GW_MODE_CLIENT:
818 		curr_gw = batadv_gw_get_selected_gw_node(bat_priv);
819 		if (!curr_gw)
820 			goto out;
821 
822 		/* packet is going to our gateway */
823 		if (curr_gw->orig_node == orig_dst_node)
824 			goto out;
825 
826 		/* If the dhcp packet has been sent to a different gw,
827 		 * we have to evaluate whether the old gw is still
828 		 * reliable enough
829 		 */
830 		neigh_curr = batadv_find_router(bat_priv, curr_gw->orig_node,
831 						NULL);
832 		if (!neigh_curr)
833 			goto out;
834 
835 		curr_ifinfo = batadv_neigh_ifinfo_get(neigh_curr,
836 						      BATADV_IF_DEFAULT);
837 		if (!curr_ifinfo)
838 			goto out;
839 
840 		curr_tq_avg = curr_ifinfo->bat_iv.tq_avg;
841 		batadv_neigh_ifinfo_free_ref(curr_ifinfo);
842 
843 		break;
844 	case BATADV_GW_MODE_OFF:
845 	default:
846 		goto out;
847 	}
848 
849 	neigh_old = batadv_find_router(bat_priv, orig_dst_node, NULL);
850 	if (!neigh_old)
851 		goto out;
852 
853 	old_ifinfo = batadv_neigh_ifinfo_get(neigh_old, BATADV_IF_DEFAULT);
854 	if (!old_ifinfo)
855 		goto out;
856 
857 	if ((curr_tq_avg - old_ifinfo->bat_iv.tq_avg) > BATADV_GW_THRESHOLD)
858 		out_of_range = true;
859 	batadv_neigh_ifinfo_free_ref(old_ifinfo);
860 
861 out:
862 	if (orig_dst_node)
863 		batadv_orig_node_free_ref(orig_dst_node);
864 	if (curr_gw)
865 		batadv_gw_node_free_ref(curr_gw);
866 	if (gw_node)
867 		batadv_gw_node_free_ref(gw_node);
868 	if (neigh_old)
869 		batadv_neigh_node_free_ref(neigh_old);
870 	if (neigh_curr)
871 		batadv_neigh_node_free_ref(neigh_curr);
872 	return out_of_range;
873 }
874