1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) 2012-2018  B.A.T.M.A.N. contributors:
3  *
4  * Martin Hundebøll, Jeppe Ledet-Pedersen
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 "network-coding.h"
20 #include "main.h"
21 
22 #include <linux/atomic.h>
23 #include <linux/bitops.h>
24 #include <linux/byteorder/generic.h>
25 #include <linux/compiler.h>
26 #include <linux/debugfs.h>
27 #include <linux/errno.h>
28 #include <linux/etherdevice.h>
29 #include <linux/gfp.h>
30 #include <linux/if_ether.h>
31 #include <linux/if_packet.h>
32 #include <linux/init.h>
33 #include <linux/jhash.h>
34 #include <linux/jiffies.h>
35 #include <linux/kernel.h>
36 #include <linux/kref.h>
37 #include <linux/list.h>
38 #include <linux/lockdep.h>
39 #include <linux/net.h>
40 #include <linux/netdevice.h>
41 #include <linux/printk.h>
42 #include <linux/random.h>
43 #include <linux/rculist.h>
44 #include <linux/rcupdate.h>
45 #include <linux/seq_file.h>
46 #include <linux/skbuff.h>
47 #include <linux/slab.h>
48 #include <linux/spinlock.h>
49 #include <linux/stddef.h>
50 #include <linux/string.h>
51 #include <linux/workqueue.h>
52 #include <uapi/linux/batadv_packet.h>
53 
54 #include "hard-interface.h"
55 #include "hash.h"
56 #include "log.h"
57 #include "originator.h"
58 #include "routing.h"
59 #include "send.h"
60 #include "tvlv.h"
61 
62 static struct lock_class_key batadv_nc_coding_hash_lock_class_key;
63 static struct lock_class_key batadv_nc_decoding_hash_lock_class_key;
64 
65 static void batadv_nc_worker(struct work_struct *work);
66 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
67 				       struct batadv_hard_iface *recv_if);
68 
69 /**
70  * batadv_nc_init() - one-time initialization for network coding
71  *
72  * Return: 0 on success or negative error number in case of failure
73  */
74 int __init batadv_nc_init(void)
75 {
76 	int ret;
77 
78 	/* Register our packet type */
79 	ret = batadv_recv_handler_register(BATADV_CODED,
80 					   batadv_nc_recv_coded_packet);
81 
82 	return ret;
83 }
84 
85 /**
86  * batadv_nc_start_timer() - initialise the nc periodic worker
87  * @bat_priv: the bat priv with all the soft interface information
88  */
89 static void batadv_nc_start_timer(struct batadv_priv *bat_priv)
90 {
91 	queue_delayed_work(batadv_event_workqueue, &bat_priv->nc.work,
92 			   msecs_to_jiffies(10));
93 }
94 
95 /**
96  * batadv_nc_tvlv_container_update() - update the network coding tvlv container
97  *  after network coding setting change
98  * @bat_priv: the bat priv with all the soft interface information
99  */
100 static void batadv_nc_tvlv_container_update(struct batadv_priv *bat_priv)
101 {
102 	char nc_mode;
103 
104 	nc_mode = atomic_read(&bat_priv->network_coding);
105 
106 	switch (nc_mode) {
107 	case 0:
108 		batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
109 		break;
110 	case 1:
111 		batadv_tvlv_container_register(bat_priv, BATADV_TVLV_NC, 1,
112 					       NULL, 0);
113 		break;
114 	}
115 }
116 
117 /**
118  * batadv_nc_status_update() - update the network coding tvlv container after
119  *  network coding setting change
120  * @net_dev: the soft interface net device
121  */
122 void batadv_nc_status_update(struct net_device *net_dev)
123 {
124 	struct batadv_priv *bat_priv = netdev_priv(net_dev);
125 
126 	batadv_nc_tvlv_container_update(bat_priv);
127 }
128 
129 /**
130  * batadv_nc_tvlv_ogm_handler_v1() - process incoming nc tvlv container
131  * @bat_priv: the bat priv with all the soft interface information
132  * @orig: the orig_node of the ogm
133  * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
134  * @tvlv_value: tvlv buffer containing the gateway data
135  * @tvlv_value_len: tvlv buffer length
136  */
137 static void batadv_nc_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
138 					  struct batadv_orig_node *orig,
139 					  u8 flags,
140 					  void *tvlv_value, u16 tvlv_value_len)
141 {
142 	if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
143 		clear_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
144 	else
145 		set_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
146 }
147 
148 /**
149  * batadv_nc_mesh_init() - initialise coding hash table and start house keeping
150  * @bat_priv: the bat priv with all the soft interface information
151  *
152  * Return: 0 on success or negative error number in case of failure
153  */
154 int batadv_nc_mesh_init(struct batadv_priv *bat_priv)
155 {
156 	bat_priv->nc.timestamp_fwd_flush = jiffies;
157 	bat_priv->nc.timestamp_sniffed_purge = jiffies;
158 
159 	if (bat_priv->nc.coding_hash || bat_priv->nc.decoding_hash)
160 		return 0;
161 
162 	bat_priv->nc.coding_hash = batadv_hash_new(128);
163 	if (!bat_priv->nc.coding_hash)
164 		goto err;
165 
166 	batadv_hash_set_lock_class(bat_priv->nc.coding_hash,
167 				   &batadv_nc_coding_hash_lock_class_key);
168 
169 	bat_priv->nc.decoding_hash = batadv_hash_new(128);
170 	if (!bat_priv->nc.decoding_hash)
171 		goto err;
172 
173 	batadv_hash_set_lock_class(bat_priv->nc.decoding_hash,
174 				   &batadv_nc_decoding_hash_lock_class_key);
175 
176 	INIT_DELAYED_WORK(&bat_priv->nc.work, batadv_nc_worker);
177 	batadv_nc_start_timer(bat_priv);
178 
179 	batadv_tvlv_handler_register(bat_priv, batadv_nc_tvlv_ogm_handler_v1,
180 				     NULL, BATADV_TVLV_NC, 1,
181 				     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
182 	batadv_nc_tvlv_container_update(bat_priv);
183 	return 0;
184 
185 err:
186 	return -ENOMEM;
187 }
188 
189 /**
190  * batadv_nc_init_bat_priv() - initialise the nc specific bat_priv variables
191  * @bat_priv: the bat priv with all the soft interface information
192  */
193 void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv)
194 {
195 	atomic_set(&bat_priv->network_coding, 0);
196 	bat_priv->nc.min_tq = 200;
197 	bat_priv->nc.max_fwd_delay = 10;
198 	bat_priv->nc.max_buffer_time = 200;
199 }
200 
201 /**
202  * batadv_nc_init_orig() - initialise the nc fields of an orig_node
203  * @orig_node: the orig_node which is going to be initialised
204  */
205 void batadv_nc_init_orig(struct batadv_orig_node *orig_node)
206 {
207 	INIT_LIST_HEAD(&orig_node->in_coding_list);
208 	INIT_LIST_HEAD(&orig_node->out_coding_list);
209 	spin_lock_init(&orig_node->in_coding_list_lock);
210 	spin_lock_init(&orig_node->out_coding_list_lock);
211 }
212 
213 /**
214  * batadv_nc_node_release() - release nc_node from lists and queue for free
215  *  after rcu grace period
216  * @ref: kref pointer of the nc_node
217  */
218 static void batadv_nc_node_release(struct kref *ref)
219 {
220 	struct batadv_nc_node *nc_node;
221 
222 	nc_node = container_of(ref, struct batadv_nc_node, refcount);
223 
224 	batadv_orig_node_put(nc_node->orig_node);
225 	kfree_rcu(nc_node, rcu);
226 }
227 
228 /**
229  * batadv_nc_node_put() - decrement the nc_node refcounter and possibly
230  *  release it
231  * @nc_node: nc_node to be free'd
232  */
233 static void batadv_nc_node_put(struct batadv_nc_node *nc_node)
234 {
235 	kref_put(&nc_node->refcount, batadv_nc_node_release);
236 }
237 
238 /**
239  * batadv_nc_path_release() - release nc_path from lists and queue for free
240  *  after rcu grace period
241  * @ref: kref pointer of the nc_path
242  */
243 static void batadv_nc_path_release(struct kref *ref)
244 {
245 	struct batadv_nc_path *nc_path;
246 
247 	nc_path = container_of(ref, struct batadv_nc_path, refcount);
248 
249 	kfree_rcu(nc_path, rcu);
250 }
251 
252 /**
253  * batadv_nc_path_put() - decrement the nc_path refcounter and possibly
254  *  release it
255  * @nc_path: nc_path to be free'd
256  */
257 static void batadv_nc_path_put(struct batadv_nc_path *nc_path)
258 {
259 	kref_put(&nc_path->refcount, batadv_nc_path_release);
260 }
261 
262 /**
263  * batadv_nc_packet_free() - frees nc packet
264  * @nc_packet: the nc packet to free
265  * @dropped: whether the packet is freed because is is dropped
266  */
267 static void batadv_nc_packet_free(struct batadv_nc_packet *nc_packet,
268 				  bool dropped)
269 {
270 	if (dropped)
271 		kfree_skb(nc_packet->skb);
272 	else
273 		consume_skb(nc_packet->skb);
274 
275 	batadv_nc_path_put(nc_packet->nc_path);
276 	kfree(nc_packet);
277 }
278 
279 /**
280  * batadv_nc_to_purge_nc_node() - checks whether an nc node has to be purged
281  * @bat_priv: the bat priv with all the soft interface information
282  * @nc_node: the nc node to check
283  *
284  * Return: true if the entry has to be purged now, false otherwise
285  */
286 static bool batadv_nc_to_purge_nc_node(struct batadv_priv *bat_priv,
287 				       struct batadv_nc_node *nc_node)
288 {
289 	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
290 		return true;
291 
292 	return batadv_has_timed_out(nc_node->last_seen, BATADV_NC_NODE_TIMEOUT);
293 }
294 
295 /**
296  * batadv_nc_to_purge_nc_path_coding() - checks whether an nc path has timed out
297  * @bat_priv: the bat priv with all the soft interface information
298  * @nc_path: the nc path to check
299  *
300  * Return: true if the entry has to be purged now, false otherwise
301  */
302 static bool batadv_nc_to_purge_nc_path_coding(struct batadv_priv *bat_priv,
303 					      struct batadv_nc_path *nc_path)
304 {
305 	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
306 		return true;
307 
308 	/* purge the path when no packets has been added for 10 times the
309 	 * max_fwd_delay time
310 	 */
311 	return batadv_has_timed_out(nc_path->last_valid,
312 				    bat_priv->nc.max_fwd_delay * 10);
313 }
314 
315 /**
316  * batadv_nc_to_purge_nc_path_decoding() - checks whether an nc path has timed
317  *  out
318  * @bat_priv: the bat priv with all the soft interface information
319  * @nc_path: the nc path to check
320  *
321  * Return: true if the entry has to be purged now, false otherwise
322  */
323 static bool batadv_nc_to_purge_nc_path_decoding(struct batadv_priv *bat_priv,
324 						struct batadv_nc_path *nc_path)
325 {
326 	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
327 		return true;
328 
329 	/* purge the path when no packets has been added for 10 times the
330 	 * max_buffer time
331 	 */
332 	return batadv_has_timed_out(nc_path->last_valid,
333 				    bat_priv->nc.max_buffer_time * 10);
334 }
335 
336 /**
337  * batadv_nc_purge_orig_nc_nodes() - go through list of nc nodes and purge stale
338  *  entries
339  * @bat_priv: the bat priv with all the soft interface information
340  * @list: list of nc nodes
341  * @lock: nc node list lock
342  * @to_purge: function in charge to decide whether an entry has to be purged or
343  *	      not. This function takes the nc node as argument and has to return
344  *	      a boolean value: true if the entry has to be deleted, false
345  *	      otherwise
346  */
347 static void
348 batadv_nc_purge_orig_nc_nodes(struct batadv_priv *bat_priv,
349 			      struct list_head *list,
350 			      spinlock_t *lock,
351 			      bool (*to_purge)(struct batadv_priv *,
352 					       struct batadv_nc_node *))
353 {
354 	struct batadv_nc_node *nc_node, *nc_node_tmp;
355 
356 	/* For each nc_node in list */
357 	spin_lock_bh(lock);
358 	list_for_each_entry_safe(nc_node, nc_node_tmp, list, list) {
359 		/* if an helper function has been passed as parameter,
360 		 * ask it if the entry has to be purged or not
361 		 */
362 		if (to_purge && !to_purge(bat_priv, nc_node))
363 			continue;
364 
365 		batadv_dbg(BATADV_DBG_NC, bat_priv,
366 			   "Removing nc_node %pM -> %pM\n",
367 			   nc_node->addr, nc_node->orig_node->orig);
368 		list_del_rcu(&nc_node->list);
369 		batadv_nc_node_put(nc_node);
370 	}
371 	spin_unlock_bh(lock);
372 }
373 
374 /**
375  * batadv_nc_purge_orig() - purges all nc node data attached of the given
376  *  originator
377  * @bat_priv: the bat priv with all the soft interface information
378  * @orig_node: orig_node with the nc node entries to be purged
379  * @to_purge: function in charge to decide whether an entry has to be purged or
380  *	      not. This function takes the nc node as argument and has to return
381  *	      a boolean value: true is the entry has to be deleted, false
382  *	      otherwise
383  */
384 void batadv_nc_purge_orig(struct batadv_priv *bat_priv,
385 			  struct batadv_orig_node *orig_node,
386 			  bool (*to_purge)(struct batadv_priv *,
387 					   struct batadv_nc_node *))
388 {
389 	/* Check ingoing nc_node's of this orig_node */
390 	batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->in_coding_list,
391 				      &orig_node->in_coding_list_lock,
392 				      to_purge);
393 
394 	/* Check outgoing nc_node's of this orig_node */
395 	batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->out_coding_list,
396 				      &orig_node->out_coding_list_lock,
397 				      to_purge);
398 }
399 
400 /**
401  * batadv_nc_purge_orig_hash() - traverse entire originator hash to check if
402  *  they have timed out nc nodes
403  * @bat_priv: the bat priv with all the soft interface information
404  */
405 static void batadv_nc_purge_orig_hash(struct batadv_priv *bat_priv)
406 {
407 	struct batadv_hashtable *hash = bat_priv->orig_hash;
408 	struct hlist_head *head;
409 	struct batadv_orig_node *orig_node;
410 	u32 i;
411 
412 	if (!hash)
413 		return;
414 
415 	/* For each orig_node */
416 	for (i = 0; i < hash->size; i++) {
417 		head = &hash->table[i];
418 
419 		rcu_read_lock();
420 		hlist_for_each_entry_rcu(orig_node, head, hash_entry)
421 			batadv_nc_purge_orig(bat_priv, orig_node,
422 					     batadv_nc_to_purge_nc_node);
423 		rcu_read_unlock();
424 	}
425 }
426 
427 /**
428  * batadv_nc_purge_paths() - traverse all nc paths part of the hash and remove
429  *  unused ones
430  * @bat_priv: the bat priv with all the soft interface information
431  * @hash: hash table containing the nc paths to check
432  * @to_purge: function in charge to decide whether an entry has to be purged or
433  *	      not. This function takes the nc node as argument and has to return
434  *	      a boolean value: true is the entry has to be deleted, false
435  *	      otherwise
436  */
437 static void batadv_nc_purge_paths(struct batadv_priv *bat_priv,
438 				  struct batadv_hashtable *hash,
439 				  bool (*to_purge)(struct batadv_priv *,
440 						   struct batadv_nc_path *))
441 {
442 	struct hlist_head *head;
443 	struct hlist_node *node_tmp;
444 	struct batadv_nc_path *nc_path;
445 	spinlock_t *lock; /* Protects lists in hash */
446 	u32 i;
447 
448 	for (i = 0; i < hash->size; i++) {
449 		head = &hash->table[i];
450 		lock = &hash->list_locks[i];
451 
452 		/* For each nc_path in this bin */
453 		spin_lock_bh(lock);
454 		hlist_for_each_entry_safe(nc_path, node_tmp, head, hash_entry) {
455 			/* if an helper function has been passed as parameter,
456 			 * ask it if the entry has to be purged or not
457 			 */
458 			if (to_purge && !to_purge(bat_priv, nc_path))
459 				continue;
460 
461 			/* purging an non-empty nc_path should never happen, but
462 			 * is observed under high CPU load. Delay the purging
463 			 * until next iteration to allow the packet_list to be
464 			 * emptied first.
465 			 */
466 			if (!unlikely(list_empty(&nc_path->packet_list))) {
467 				net_ratelimited_function(printk,
468 							 KERN_WARNING
469 							 "Skipping free of non-empty nc_path (%pM -> %pM)!\n",
470 							 nc_path->prev_hop,
471 							 nc_path->next_hop);
472 				continue;
473 			}
474 
475 			/* nc_path is unused, so remove it */
476 			batadv_dbg(BATADV_DBG_NC, bat_priv,
477 				   "Remove nc_path %pM -> %pM\n",
478 				   nc_path->prev_hop, nc_path->next_hop);
479 			hlist_del_rcu(&nc_path->hash_entry);
480 			batadv_nc_path_put(nc_path);
481 		}
482 		spin_unlock_bh(lock);
483 	}
484 }
485 
486 /**
487  * batadv_nc_hash_key_gen() - computes the nc_path hash key
488  * @key: buffer to hold the final hash key
489  * @src: source ethernet mac address going into the hash key
490  * @dst: destination ethernet mac address going into the hash key
491  */
492 static void batadv_nc_hash_key_gen(struct batadv_nc_path *key, const char *src,
493 				   const char *dst)
494 {
495 	memcpy(key->prev_hop, src, sizeof(key->prev_hop));
496 	memcpy(key->next_hop, dst, sizeof(key->next_hop));
497 }
498 
499 /**
500  * batadv_nc_hash_choose() - compute the hash value for an nc path
501  * @data: data to hash
502  * @size: size of the hash table
503  *
504  * Return: the selected index in the hash table for the given data.
505  */
506 static u32 batadv_nc_hash_choose(const void *data, u32 size)
507 {
508 	const struct batadv_nc_path *nc_path = data;
509 	u32 hash = 0;
510 
511 	hash = jhash(&nc_path->prev_hop, sizeof(nc_path->prev_hop), hash);
512 	hash = jhash(&nc_path->next_hop, sizeof(nc_path->next_hop), hash);
513 
514 	return hash % size;
515 }
516 
517 /**
518  * batadv_nc_hash_compare() - comparing function used in the network coding hash
519  *  tables
520  * @node: node in the local table
521  * @data2: second object to compare the node to
522  *
523  * Return: true if the two entry are the same, false otherwise
524  */
525 static bool batadv_nc_hash_compare(const struct hlist_node *node,
526 				   const void *data2)
527 {
528 	const struct batadv_nc_path *nc_path1, *nc_path2;
529 
530 	nc_path1 = container_of(node, struct batadv_nc_path, hash_entry);
531 	nc_path2 = data2;
532 
533 	/* Return 1 if the two keys are identical */
534 	if (!batadv_compare_eth(nc_path1->prev_hop, nc_path2->prev_hop))
535 		return false;
536 
537 	if (!batadv_compare_eth(nc_path1->next_hop, nc_path2->next_hop))
538 		return false;
539 
540 	return true;
541 }
542 
543 /**
544  * batadv_nc_hash_find() - search for an existing nc path and return it
545  * @hash: hash table containing the nc path
546  * @data: search key
547  *
548  * Return: the nc_path if found, NULL otherwise.
549  */
550 static struct batadv_nc_path *
551 batadv_nc_hash_find(struct batadv_hashtable *hash,
552 		    void *data)
553 {
554 	struct hlist_head *head;
555 	struct batadv_nc_path *nc_path, *nc_path_tmp = NULL;
556 	int index;
557 
558 	if (!hash)
559 		return NULL;
560 
561 	index = batadv_nc_hash_choose(data, hash->size);
562 	head = &hash->table[index];
563 
564 	rcu_read_lock();
565 	hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
566 		if (!batadv_nc_hash_compare(&nc_path->hash_entry, data))
567 			continue;
568 
569 		if (!kref_get_unless_zero(&nc_path->refcount))
570 			continue;
571 
572 		nc_path_tmp = nc_path;
573 		break;
574 	}
575 	rcu_read_unlock();
576 
577 	return nc_path_tmp;
578 }
579 
580 /**
581  * batadv_nc_send_packet() - send non-coded packet and free nc_packet struct
582  * @nc_packet: the nc packet to send
583  */
584 static void batadv_nc_send_packet(struct batadv_nc_packet *nc_packet)
585 {
586 	batadv_send_unicast_skb(nc_packet->skb, nc_packet->neigh_node);
587 	nc_packet->skb = NULL;
588 	batadv_nc_packet_free(nc_packet, false);
589 }
590 
591 /**
592  * batadv_nc_sniffed_purge() - Checks timestamp of given sniffed nc_packet.
593  * @bat_priv: the bat priv with all the soft interface information
594  * @nc_path: the nc path the packet belongs to
595  * @nc_packet: the nc packet to be checked
596  *
597  * Checks whether the given sniffed (overheard) nc_packet has hit its buffering
598  * timeout. If so, the packet is no longer kept and the entry deleted from the
599  * queue. Has to be called with the appropriate locks.
600  *
601  * Return: false as soon as the entry in the fifo queue has not been timed out
602  * yet and true otherwise.
603  */
604 static bool batadv_nc_sniffed_purge(struct batadv_priv *bat_priv,
605 				    struct batadv_nc_path *nc_path,
606 				    struct batadv_nc_packet *nc_packet)
607 {
608 	unsigned long timeout = bat_priv->nc.max_buffer_time;
609 	bool res = false;
610 
611 	lockdep_assert_held(&nc_path->packet_list_lock);
612 
613 	/* Packets are added to tail, so the remaining packets did not time
614 	 * out and we can stop processing the current queue
615 	 */
616 	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
617 	    !batadv_has_timed_out(nc_packet->timestamp, timeout))
618 		goto out;
619 
620 	/* purge nc packet */
621 	list_del(&nc_packet->list);
622 	batadv_nc_packet_free(nc_packet, true);
623 
624 	res = true;
625 
626 out:
627 	return res;
628 }
629 
630 /**
631  * batadv_nc_fwd_flush() - Checks the timestamp of the given nc packet.
632  * @bat_priv: the bat priv with all the soft interface information
633  * @nc_path: the nc path the packet belongs to
634  * @nc_packet: the nc packet to be checked
635  *
636  * Checks whether the given nc packet has hit its forward timeout. If so, the
637  * packet is no longer delayed, immediately sent and the entry deleted from the
638  * queue. Has to be called with the appropriate locks.
639  *
640  * Return: false as soon as the entry in the fifo queue has not been timed out
641  * yet and true otherwise.
642  */
643 static bool batadv_nc_fwd_flush(struct batadv_priv *bat_priv,
644 				struct batadv_nc_path *nc_path,
645 				struct batadv_nc_packet *nc_packet)
646 {
647 	unsigned long timeout = bat_priv->nc.max_fwd_delay;
648 
649 	lockdep_assert_held(&nc_path->packet_list_lock);
650 
651 	/* Packets are added to tail, so the remaining packets did not time
652 	 * out and we can stop processing the current queue
653 	 */
654 	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
655 	    !batadv_has_timed_out(nc_packet->timestamp, timeout))
656 		return false;
657 
658 	/* Send packet */
659 	batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
660 	batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
661 			   nc_packet->skb->len + ETH_HLEN);
662 	list_del(&nc_packet->list);
663 	batadv_nc_send_packet(nc_packet);
664 
665 	return true;
666 }
667 
668 /**
669  * batadv_nc_process_nc_paths() - traverse given nc packet pool and free timed
670  *  out nc packets
671  * @bat_priv: the bat priv with all the soft interface information
672  * @hash: to be processed hash table
673  * @process_fn: Function called to process given nc packet. Should return true
674  *	        to encourage this function to proceed with the next packet.
675  *	        Otherwise the rest of the current queue is skipped.
676  */
677 static void
678 batadv_nc_process_nc_paths(struct batadv_priv *bat_priv,
679 			   struct batadv_hashtable *hash,
680 			   bool (*process_fn)(struct batadv_priv *,
681 					      struct batadv_nc_path *,
682 					      struct batadv_nc_packet *))
683 {
684 	struct hlist_head *head;
685 	struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
686 	struct batadv_nc_path *nc_path;
687 	bool ret;
688 	int i;
689 
690 	if (!hash)
691 		return;
692 
693 	/* Loop hash table bins */
694 	for (i = 0; i < hash->size; i++) {
695 		head = &hash->table[i];
696 
697 		/* Loop coding paths */
698 		rcu_read_lock();
699 		hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
700 			/* Loop packets */
701 			spin_lock_bh(&nc_path->packet_list_lock);
702 			list_for_each_entry_safe(nc_packet, nc_packet_tmp,
703 						 &nc_path->packet_list, list) {
704 				ret = process_fn(bat_priv, nc_path, nc_packet);
705 				if (!ret)
706 					break;
707 			}
708 			spin_unlock_bh(&nc_path->packet_list_lock);
709 		}
710 		rcu_read_unlock();
711 	}
712 }
713 
714 /**
715  * batadv_nc_worker() - periodic task for house keeping related to network
716  *  coding
717  * @work: kernel work struct
718  */
719 static void batadv_nc_worker(struct work_struct *work)
720 {
721 	struct delayed_work *delayed_work;
722 	struct batadv_priv_nc *priv_nc;
723 	struct batadv_priv *bat_priv;
724 	unsigned long timeout;
725 
726 	delayed_work = to_delayed_work(work);
727 	priv_nc = container_of(delayed_work, struct batadv_priv_nc, work);
728 	bat_priv = container_of(priv_nc, struct batadv_priv, nc);
729 
730 	batadv_nc_purge_orig_hash(bat_priv);
731 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash,
732 			      batadv_nc_to_purge_nc_path_coding);
733 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash,
734 			      batadv_nc_to_purge_nc_path_decoding);
735 
736 	timeout = bat_priv->nc.max_fwd_delay;
737 
738 	if (batadv_has_timed_out(bat_priv->nc.timestamp_fwd_flush, timeout)) {
739 		batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.coding_hash,
740 					   batadv_nc_fwd_flush);
741 		bat_priv->nc.timestamp_fwd_flush = jiffies;
742 	}
743 
744 	if (batadv_has_timed_out(bat_priv->nc.timestamp_sniffed_purge,
745 				 bat_priv->nc.max_buffer_time)) {
746 		batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.decoding_hash,
747 					   batadv_nc_sniffed_purge);
748 		bat_priv->nc.timestamp_sniffed_purge = jiffies;
749 	}
750 
751 	/* Schedule a new check */
752 	batadv_nc_start_timer(bat_priv);
753 }
754 
755 /**
756  * batadv_can_nc_with_orig() - checks whether the given orig node is suitable
757  *  for coding or not
758  * @bat_priv: the bat priv with all the soft interface information
759  * @orig_node: neighboring orig node which may be used as nc candidate
760  * @ogm_packet: incoming ogm packet also used for the checks
761  *
762  * Return: true if:
763  *  1) The OGM must have the most recent sequence number.
764  *  2) The TTL must be decremented by one and only one.
765  *  3) The OGM must be received from the first hop from orig_node.
766  *  4) The TQ value of the OGM must be above bat_priv->nc.min_tq.
767  */
768 static bool batadv_can_nc_with_orig(struct batadv_priv *bat_priv,
769 				    struct batadv_orig_node *orig_node,
770 				    struct batadv_ogm_packet *ogm_packet)
771 {
772 	struct batadv_orig_ifinfo *orig_ifinfo;
773 	u32 last_real_seqno;
774 	u8 last_ttl;
775 
776 	orig_ifinfo = batadv_orig_ifinfo_get(orig_node, BATADV_IF_DEFAULT);
777 	if (!orig_ifinfo)
778 		return false;
779 
780 	last_ttl = orig_ifinfo->last_ttl;
781 	last_real_seqno = orig_ifinfo->last_real_seqno;
782 	batadv_orig_ifinfo_put(orig_ifinfo);
783 
784 	if (last_real_seqno != ntohl(ogm_packet->seqno))
785 		return false;
786 	if (last_ttl != ogm_packet->ttl + 1)
787 		return false;
788 	if (!batadv_compare_eth(ogm_packet->orig, ogm_packet->prev_sender))
789 		return false;
790 	if (ogm_packet->tq < bat_priv->nc.min_tq)
791 		return false;
792 
793 	return true;
794 }
795 
796 /**
797  * batadv_nc_find_nc_node() - search for an existing nc node and return it
798  * @orig_node: orig node originating the ogm packet
799  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
800  *  (can be equal to orig_node)
801  * @in_coding: traverse incoming or outgoing network coding list
802  *
803  * Return: the nc_node if found, NULL otherwise.
804  */
805 static struct batadv_nc_node *
806 batadv_nc_find_nc_node(struct batadv_orig_node *orig_node,
807 		       struct batadv_orig_node *orig_neigh_node,
808 		       bool in_coding)
809 {
810 	struct batadv_nc_node *nc_node, *nc_node_out = NULL;
811 	struct list_head *list;
812 
813 	if (in_coding)
814 		list = &orig_neigh_node->in_coding_list;
815 	else
816 		list = &orig_neigh_node->out_coding_list;
817 
818 	/* Traverse list of nc_nodes to orig_node */
819 	rcu_read_lock();
820 	list_for_each_entry_rcu(nc_node, list, list) {
821 		if (!batadv_compare_eth(nc_node->addr, orig_node->orig))
822 			continue;
823 
824 		if (!kref_get_unless_zero(&nc_node->refcount))
825 			continue;
826 
827 		/* Found a match */
828 		nc_node_out = nc_node;
829 		break;
830 	}
831 	rcu_read_unlock();
832 
833 	return nc_node_out;
834 }
835 
836 /**
837  * batadv_nc_get_nc_node() - retrieves an nc node or creates the entry if it was
838  *  not found
839  * @bat_priv: the bat priv with all the soft interface information
840  * @orig_node: orig node originating the ogm packet
841  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
842  *  (can be equal to orig_node)
843  * @in_coding: traverse incoming or outgoing network coding list
844  *
845  * Return: the nc_node if found or created, NULL in case of an error.
846  */
847 static struct batadv_nc_node *
848 batadv_nc_get_nc_node(struct batadv_priv *bat_priv,
849 		      struct batadv_orig_node *orig_node,
850 		      struct batadv_orig_node *orig_neigh_node,
851 		      bool in_coding)
852 {
853 	struct batadv_nc_node *nc_node;
854 	spinlock_t *lock; /* Used to lock list selected by "int in_coding" */
855 	struct list_head *list;
856 
857 	/* Check if nc_node is already added */
858 	nc_node = batadv_nc_find_nc_node(orig_node, orig_neigh_node, in_coding);
859 
860 	/* Node found */
861 	if (nc_node)
862 		return nc_node;
863 
864 	nc_node = kzalloc(sizeof(*nc_node), GFP_ATOMIC);
865 	if (!nc_node)
866 		return NULL;
867 
868 	/* Initialize nc_node */
869 	INIT_LIST_HEAD(&nc_node->list);
870 	kref_init(&nc_node->refcount);
871 	ether_addr_copy(nc_node->addr, orig_node->orig);
872 	kref_get(&orig_neigh_node->refcount);
873 	nc_node->orig_node = orig_neigh_node;
874 
875 	/* Select ingoing or outgoing coding node */
876 	if (in_coding) {
877 		lock = &orig_neigh_node->in_coding_list_lock;
878 		list = &orig_neigh_node->in_coding_list;
879 	} else {
880 		lock = &orig_neigh_node->out_coding_list_lock;
881 		list = &orig_neigh_node->out_coding_list;
882 	}
883 
884 	batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_node %pM -> %pM\n",
885 		   nc_node->addr, nc_node->orig_node->orig);
886 
887 	/* Add nc_node to orig_node */
888 	spin_lock_bh(lock);
889 	kref_get(&nc_node->refcount);
890 	list_add_tail_rcu(&nc_node->list, list);
891 	spin_unlock_bh(lock);
892 
893 	return nc_node;
894 }
895 
896 /**
897  * batadv_nc_update_nc_node() - updates stored incoming and outgoing nc node
898  *  structs (best called on incoming OGMs)
899  * @bat_priv: the bat priv with all the soft interface information
900  * @orig_node: orig node originating the ogm packet
901  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
902  *  (can be equal to orig_node)
903  * @ogm_packet: incoming ogm packet
904  * @is_single_hop_neigh: orig_node is a single hop neighbor
905  */
906 void batadv_nc_update_nc_node(struct batadv_priv *bat_priv,
907 			      struct batadv_orig_node *orig_node,
908 			      struct batadv_orig_node *orig_neigh_node,
909 			      struct batadv_ogm_packet *ogm_packet,
910 			      int is_single_hop_neigh)
911 {
912 	struct batadv_nc_node *in_nc_node = NULL;
913 	struct batadv_nc_node *out_nc_node = NULL;
914 
915 	/* Check if network coding is enabled */
916 	if (!atomic_read(&bat_priv->network_coding))
917 		goto out;
918 
919 	/* check if orig node is network coding enabled */
920 	if (!test_bit(BATADV_ORIG_CAPA_HAS_NC, &orig_node->capabilities))
921 		goto out;
922 
923 	/* accept ogms from 'good' neighbors and single hop neighbors */
924 	if (!batadv_can_nc_with_orig(bat_priv, orig_node, ogm_packet) &&
925 	    !is_single_hop_neigh)
926 		goto out;
927 
928 	/* Add orig_node as in_nc_node on hop */
929 	in_nc_node = batadv_nc_get_nc_node(bat_priv, orig_node,
930 					   orig_neigh_node, true);
931 	if (!in_nc_node)
932 		goto out;
933 
934 	in_nc_node->last_seen = jiffies;
935 
936 	/* Add hop as out_nc_node on orig_node */
937 	out_nc_node = batadv_nc_get_nc_node(bat_priv, orig_neigh_node,
938 					    orig_node, false);
939 	if (!out_nc_node)
940 		goto out;
941 
942 	out_nc_node->last_seen = jiffies;
943 
944 out:
945 	if (in_nc_node)
946 		batadv_nc_node_put(in_nc_node);
947 	if (out_nc_node)
948 		batadv_nc_node_put(out_nc_node);
949 }
950 
951 /**
952  * batadv_nc_get_path() - get existing nc_path or allocate a new one
953  * @bat_priv: the bat priv with all the soft interface information
954  * @hash: hash table containing the nc path
955  * @src: ethernet source address - first half of the nc path search key
956  * @dst: ethernet destination address - second half of the nc path search key
957  *
958  * Return: pointer to nc_path if the path was found or created, returns NULL
959  * on error.
960  */
961 static struct batadv_nc_path *batadv_nc_get_path(struct batadv_priv *bat_priv,
962 						 struct batadv_hashtable *hash,
963 						 u8 *src,
964 						 u8 *dst)
965 {
966 	int hash_added;
967 	struct batadv_nc_path *nc_path, nc_path_key;
968 
969 	batadv_nc_hash_key_gen(&nc_path_key, src, dst);
970 
971 	/* Search for existing nc_path */
972 	nc_path = batadv_nc_hash_find(hash, (void *)&nc_path_key);
973 
974 	if (nc_path) {
975 		/* Set timestamp to delay removal of nc_path */
976 		nc_path->last_valid = jiffies;
977 		return nc_path;
978 	}
979 
980 	/* No existing nc_path was found; create a new */
981 	nc_path = kzalloc(sizeof(*nc_path), GFP_ATOMIC);
982 
983 	if (!nc_path)
984 		return NULL;
985 
986 	/* Initialize nc_path */
987 	INIT_LIST_HEAD(&nc_path->packet_list);
988 	spin_lock_init(&nc_path->packet_list_lock);
989 	kref_init(&nc_path->refcount);
990 	nc_path->last_valid = jiffies;
991 	ether_addr_copy(nc_path->next_hop, dst);
992 	ether_addr_copy(nc_path->prev_hop, src);
993 
994 	batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_path %pM -> %pM\n",
995 		   nc_path->prev_hop,
996 		   nc_path->next_hop);
997 
998 	/* Add nc_path to hash table */
999 	kref_get(&nc_path->refcount);
1000 	hash_added = batadv_hash_add(hash, batadv_nc_hash_compare,
1001 				     batadv_nc_hash_choose, &nc_path_key,
1002 				     &nc_path->hash_entry);
1003 
1004 	if (hash_added < 0) {
1005 		kfree(nc_path);
1006 		return NULL;
1007 	}
1008 
1009 	return nc_path;
1010 }
1011 
1012 /**
1013  * batadv_nc_random_weight_tq() - scale the receivers TQ-value to avoid unfair
1014  *  selection of a receiver with slightly lower TQ than the other
1015  * @tq: to be weighted tq value
1016  *
1017  * Return: scaled tq value
1018  */
1019 static u8 batadv_nc_random_weight_tq(u8 tq)
1020 {
1021 	u8 rand_val, rand_tq;
1022 
1023 	get_random_bytes(&rand_val, sizeof(rand_val));
1024 
1025 	/* randomize the estimated packet loss (max TQ - estimated TQ) */
1026 	rand_tq = rand_val * (BATADV_TQ_MAX_VALUE - tq);
1027 
1028 	/* normalize the randomized packet loss */
1029 	rand_tq /= BATADV_TQ_MAX_VALUE;
1030 
1031 	/* convert to (randomized) estimated tq again */
1032 	return BATADV_TQ_MAX_VALUE - rand_tq;
1033 }
1034 
1035 /**
1036  * batadv_nc_memxor() - XOR destination with source
1037  * @dst: byte array to XOR into
1038  * @src: byte array to XOR from
1039  * @len: length of destination array
1040  */
1041 static void batadv_nc_memxor(char *dst, const char *src, unsigned int len)
1042 {
1043 	unsigned int i;
1044 
1045 	for (i = 0; i < len; ++i)
1046 		dst[i] ^= src[i];
1047 }
1048 
1049 /**
1050  * batadv_nc_code_packets() - code a received unicast_packet with an nc packet
1051  *  into a coded_packet and send it
1052  * @bat_priv: the bat priv with all the soft interface information
1053  * @skb: data skb to forward
1054  * @ethhdr: pointer to the ethernet header inside the skb
1055  * @nc_packet: structure containing the packet to the skb can be coded with
1056  * @neigh_node: next hop to forward packet to
1057  *
1058  * Return: true if both packets are consumed, false otherwise.
1059  */
1060 static bool batadv_nc_code_packets(struct batadv_priv *bat_priv,
1061 				   struct sk_buff *skb,
1062 				   struct ethhdr *ethhdr,
1063 				   struct batadv_nc_packet *nc_packet,
1064 				   struct batadv_neigh_node *neigh_node)
1065 {
1066 	u8 tq_weighted_neigh, tq_weighted_coding, tq_tmp;
1067 	struct sk_buff *skb_dest, *skb_src;
1068 	struct batadv_unicast_packet *packet1;
1069 	struct batadv_unicast_packet *packet2;
1070 	struct batadv_coded_packet *coded_packet;
1071 	struct batadv_neigh_node *neigh_tmp, *router_neigh, *first_dest;
1072 	struct batadv_neigh_node *router_coding = NULL, *second_dest;
1073 	struct batadv_neigh_ifinfo *router_neigh_ifinfo = NULL;
1074 	struct batadv_neigh_ifinfo *router_coding_ifinfo = NULL;
1075 	u8 *first_source, *second_source;
1076 	__be32 packet_id1, packet_id2;
1077 	size_t count;
1078 	bool res = false;
1079 	int coding_len;
1080 	int unicast_size = sizeof(*packet1);
1081 	int coded_size = sizeof(*coded_packet);
1082 	int header_add = coded_size - unicast_size;
1083 
1084 	/* TODO: do we need to consider the outgoing interface for
1085 	 * coded packets?
1086 	 */
1087 	router_neigh = batadv_orig_router_get(neigh_node->orig_node,
1088 					      BATADV_IF_DEFAULT);
1089 	if (!router_neigh)
1090 		goto out;
1091 
1092 	router_neigh_ifinfo = batadv_neigh_ifinfo_get(router_neigh,
1093 						      BATADV_IF_DEFAULT);
1094 	if (!router_neigh_ifinfo)
1095 		goto out;
1096 
1097 	neigh_tmp = nc_packet->neigh_node;
1098 	router_coding = batadv_orig_router_get(neigh_tmp->orig_node,
1099 					       BATADV_IF_DEFAULT);
1100 	if (!router_coding)
1101 		goto out;
1102 
1103 	router_coding_ifinfo = batadv_neigh_ifinfo_get(router_coding,
1104 						       BATADV_IF_DEFAULT);
1105 	if (!router_coding_ifinfo)
1106 		goto out;
1107 
1108 	tq_tmp = router_neigh_ifinfo->bat_iv.tq_avg;
1109 	tq_weighted_neigh = batadv_nc_random_weight_tq(tq_tmp);
1110 	tq_tmp = router_coding_ifinfo->bat_iv.tq_avg;
1111 	tq_weighted_coding = batadv_nc_random_weight_tq(tq_tmp);
1112 
1113 	/* Select one destination for the MAC-header dst-field based on
1114 	 * weighted TQ-values.
1115 	 */
1116 	if (tq_weighted_neigh >= tq_weighted_coding) {
1117 		/* Destination from nc_packet is selected for MAC-header */
1118 		first_dest = nc_packet->neigh_node;
1119 		first_source = nc_packet->nc_path->prev_hop;
1120 		second_dest = neigh_node;
1121 		second_source = ethhdr->h_source;
1122 		packet1 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1123 		packet2 = (struct batadv_unicast_packet *)skb->data;
1124 		packet_id1 = nc_packet->packet_id;
1125 		packet_id2 = batadv_skb_crc32(skb,
1126 					      skb->data + sizeof(*packet2));
1127 	} else {
1128 		/* Destination for skb is selected for MAC-header */
1129 		first_dest = neigh_node;
1130 		first_source = ethhdr->h_source;
1131 		second_dest = nc_packet->neigh_node;
1132 		second_source = nc_packet->nc_path->prev_hop;
1133 		packet1 = (struct batadv_unicast_packet *)skb->data;
1134 		packet2 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1135 		packet_id1 = batadv_skb_crc32(skb,
1136 					      skb->data + sizeof(*packet1));
1137 		packet_id2 = nc_packet->packet_id;
1138 	}
1139 
1140 	/* Instead of zero padding the smallest data buffer, we
1141 	 * code into the largest.
1142 	 */
1143 	if (skb->len <= nc_packet->skb->len) {
1144 		skb_dest = nc_packet->skb;
1145 		skb_src = skb;
1146 	} else {
1147 		skb_dest = skb;
1148 		skb_src = nc_packet->skb;
1149 	}
1150 
1151 	/* coding_len is used when decoding the packet shorter packet */
1152 	coding_len = skb_src->len - unicast_size;
1153 
1154 	if (skb_linearize(skb_dest) < 0 || skb_linearize(skb_src) < 0)
1155 		goto out;
1156 
1157 	skb_push(skb_dest, header_add);
1158 
1159 	coded_packet = (struct batadv_coded_packet *)skb_dest->data;
1160 	skb_reset_mac_header(skb_dest);
1161 
1162 	coded_packet->packet_type = BATADV_CODED;
1163 	coded_packet->version = BATADV_COMPAT_VERSION;
1164 	coded_packet->ttl = packet1->ttl;
1165 
1166 	/* Info about first unicast packet */
1167 	ether_addr_copy(coded_packet->first_source, first_source);
1168 	ether_addr_copy(coded_packet->first_orig_dest, packet1->dest);
1169 	coded_packet->first_crc = packet_id1;
1170 	coded_packet->first_ttvn = packet1->ttvn;
1171 
1172 	/* Info about second unicast packet */
1173 	ether_addr_copy(coded_packet->second_dest, second_dest->addr);
1174 	ether_addr_copy(coded_packet->second_source, second_source);
1175 	ether_addr_copy(coded_packet->second_orig_dest, packet2->dest);
1176 	coded_packet->second_crc = packet_id2;
1177 	coded_packet->second_ttl = packet2->ttl;
1178 	coded_packet->second_ttvn = packet2->ttvn;
1179 	coded_packet->coded_len = htons(coding_len);
1180 
1181 	/* This is where the magic happens: Code skb_src into skb_dest */
1182 	batadv_nc_memxor(skb_dest->data + coded_size,
1183 			 skb_src->data + unicast_size, coding_len);
1184 
1185 	/* Update counters accordingly */
1186 	if (BATADV_SKB_CB(skb_src)->decoded &&
1187 	    BATADV_SKB_CB(skb_dest)->decoded) {
1188 		/* Both packets are recoded */
1189 		count = skb_src->len + ETH_HLEN;
1190 		count += skb_dest->len + ETH_HLEN;
1191 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE, 2);
1192 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, count);
1193 	} else if (!BATADV_SKB_CB(skb_src)->decoded &&
1194 		   !BATADV_SKB_CB(skb_dest)->decoded) {
1195 		/* Both packets are newly coded */
1196 		count = skb_src->len + ETH_HLEN;
1197 		count += skb_dest->len + ETH_HLEN;
1198 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE, 2);
1199 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, count);
1200 	} else if (BATADV_SKB_CB(skb_src)->decoded &&
1201 		   !BATADV_SKB_CB(skb_dest)->decoded) {
1202 		/* skb_src recoded and skb_dest is newly coded */
1203 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1204 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1205 				   skb_src->len + ETH_HLEN);
1206 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1207 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1208 				   skb_dest->len + ETH_HLEN);
1209 	} else if (!BATADV_SKB_CB(skb_src)->decoded &&
1210 		   BATADV_SKB_CB(skb_dest)->decoded) {
1211 		/* skb_src is newly coded and skb_dest is recoded */
1212 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1213 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1214 				   skb_src->len + ETH_HLEN);
1215 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1216 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1217 				   skb_dest->len + ETH_HLEN);
1218 	}
1219 
1220 	/* skb_src is now coded into skb_dest, so free it */
1221 	consume_skb(skb_src);
1222 
1223 	/* avoid duplicate free of skb from nc_packet */
1224 	nc_packet->skb = NULL;
1225 	batadv_nc_packet_free(nc_packet, false);
1226 
1227 	/* Send the coded packet and return true */
1228 	batadv_send_unicast_skb(skb_dest, first_dest);
1229 	res = true;
1230 out:
1231 	if (router_neigh)
1232 		batadv_neigh_node_put(router_neigh);
1233 	if (router_coding)
1234 		batadv_neigh_node_put(router_coding);
1235 	if (router_neigh_ifinfo)
1236 		batadv_neigh_ifinfo_put(router_neigh_ifinfo);
1237 	if (router_coding_ifinfo)
1238 		batadv_neigh_ifinfo_put(router_coding_ifinfo);
1239 	return res;
1240 }
1241 
1242 /**
1243  * batadv_nc_skb_coding_possible() - true if a decoded skb is available at dst.
1244  * @skb: data skb to forward
1245  * @dst: destination mac address of the other skb to code with
1246  * @src: source mac address of skb
1247  *
1248  * Whenever we network code a packet we have to check whether we received it in
1249  * a network coded form. If so, we may not be able to use it for coding because
1250  * some neighbors may also have received (overheard) the packet in the network
1251  * coded form without being able to decode it. It is hard to know which of the
1252  * neighboring nodes was able to decode the packet, therefore we can only
1253  * re-code the packet if the source of the previous encoded packet is involved.
1254  * Since the source encoded the packet we can be certain it has all necessary
1255  * decode information.
1256  *
1257  * Return: true if coding of a decoded packet is allowed.
1258  */
1259 static bool batadv_nc_skb_coding_possible(struct sk_buff *skb, u8 *dst, u8 *src)
1260 {
1261 	if (BATADV_SKB_CB(skb)->decoded && !batadv_compare_eth(dst, src))
1262 		return false;
1263 	return true;
1264 }
1265 
1266 /**
1267  * batadv_nc_path_search() - Find the coding path matching in_nc_node and
1268  *  out_nc_node to retrieve a buffered packet that can be used for coding.
1269  * @bat_priv: the bat priv with all the soft interface information
1270  * @in_nc_node: pointer to skb next hop's neighbor nc node
1271  * @out_nc_node: pointer to skb source's neighbor nc node
1272  * @skb: data skb to forward
1273  * @eth_dst: next hop mac address of skb
1274  *
1275  * Return: true if coding of a decoded skb is allowed.
1276  */
1277 static struct batadv_nc_packet *
1278 batadv_nc_path_search(struct batadv_priv *bat_priv,
1279 		      struct batadv_nc_node *in_nc_node,
1280 		      struct batadv_nc_node *out_nc_node,
1281 		      struct sk_buff *skb,
1282 		      u8 *eth_dst)
1283 {
1284 	struct batadv_nc_path *nc_path, nc_path_key;
1285 	struct batadv_nc_packet *nc_packet_out = NULL;
1286 	struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
1287 	struct batadv_hashtable *hash = bat_priv->nc.coding_hash;
1288 	int idx;
1289 
1290 	if (!hash)
1291 		return NULL;
1292 
1293 	/* Create almost path key */
1294 	batadv_nc_hash_key_gen(&nc_path_key, in_nc_node->addr,
1295 			       out_nc_node->addr);
1296 	idx = batadv_nc_hash_choose(&nc_path_key, hash->size);
1297 
1298 	/* Check for coding opportunities in this nc_path */
1299 	rcu_read_lock();
1300 	hlist_for_each_entry_rcu(nc_path, &hash->table[idx], hash_entry) {
1301 		if (!batadv_compare_eth(nc_path->prev_hop, in_nc_node->addr))
1302 			continue;
1303 
1304 		if (!batadv_compare_eth(nc_path->next_hop, out_nc_node->addr))
1305 			continue;
1306 
1307 		spin_lock_bh(&nc_path->packet_list_lock);
1308 		if (list_empty(&nc_path->packet_list)) {
1309 			spin_unlock_bh(&nc_path->packet_list_lock);
1310 			continue;
1311 		}
1312 
1313 		list_for_each_entry_safe(nc_packet, nc_packet_tmp,
1314 					 &nc_path->packet_list, list) {
1315 			if (!batadv_nc_skb_coding_possible(nc_packet->skb,
1316 							   eth_dst,
1317 							   in_nc_node->addr))
1318 				continue;
1319 
1320 			/* Coding opportunity is found! */
1321 			list_del(&nc_packet->list);
1322 			nc_packet_out = nc_packet;
1323 			break;
1324 		}
1325 
1326 		spin_unlock_bh(&nc_path->packet_list_lock);
1327 		break;
1328 	}
1329 	rcu_read_unlock();
1330 
1331 	return nc_packet_out;
1332 }
1333 
1334 /**
1335  * batadv_nc_skb_src_search() - Loops through the list of neighoring nodes of
1336  *  the skb's sender (may be equal to the originator).
1337  * @bat_priv: the bat priv with all the soft interface information
1338  * @skb: data skb to forward
1339  * @eth_dst: next hop mac address of skb
1340  * @eth_src: source mac address of skb
1341  * @in_nc_node: pointer to skb next hop's neighbor nc node
1342  *
1343  * Return: an nc packet if a suitable coding packet was found, NULL otherwise.
1344  */
1345 static struct batadv_nc_packet *
1346 batadv_nc_skb_src_search(struct batadv_priv *bat_priv,
1347 			 struct sk_buff *skb,
1348 			 u8 *eth_dst,
1349 			 u8 *eth_src,
1350 			 struct batadv_nc_node *in_nc_node)
1351 {
1352 	struct batadv_orig_node *orig_node;
1353 	struct batadv_nc_node *out_nc_node;
1354 	struct batadv_nc_packet *nc_packet = NULL;
1355 
1356 	orig_node = batadv_orig_hash_find(bat_priv, eth_src);
1357 	if (!orig_node)
1358 		return NULL;
1359 
1360 	rcu_read_lock();
1361 	list_for_each_entry_rcu(out_nc_node,
1362 				&orig_node->out_coding_list, list) {
1363 		/* Check if the skb is decoded and if recoding is possible */
1364 		if (!batadv_nc_skb_coding_possible(skb,
1365 						   out_nc_node->addr, eth_src))
1366 			continue;
1367 
1368 		/* Search for an opportunity in this nc_path */
1369 		nc_packet = batadv_nc_path_search(bat_priv, in_nc_node,
1370 						  out_nc_node, skb, eth_dst);
1371 		if (nc_packet)
1372 			break;
1373 	}
1374 	rcu_read_unlock();
1375 
1376 	batadv_orig_node_put(orig_node);
1377 	return nc_packet;
1378 }
1379 
1380 /**
1381  * batadv_nc_skb_store_before_coding() - set the ethernet src and dst of the
1382  *  unicast skb before it is stored for use in later decoding
1383  * @bat_priv: the bat priv with all the soft interface information
1384  * @skb: data skb to store
1385  * @eth_dst_new: new destination mac address of skb
1386  */
1387 static void batadv_nc_skb_store_before_coding(struct batadv_priv *bat_priv,
1388 					      struct sk_buff *skb,
1389 					      u8 *eth_dst_new)
1390 {
1391 	struct ethhdr *ethhdr;
1392 
1393 	/* Copy skb header to change the mac header */
1394 	skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
1395 	if (!skb)
1396 		return;
1397 
1398 	/* Set the mac header as if we actually sent the packet uncoded */
1399 	ethhdr = eth_hdr(skb);
1400 	ether_addr_copy(ethhdr->h_source, ethhdr->h_dest);
1401 	ether_addr_copy(ethhdr->h_dest, eth_dst_new);
1402 
1403 	/* Set data pointer to MAC header to mimic packets from our tx path */
1404 	skb_push(skb, ETH_HLEN);
1405 
1406 	/* Add the packet to the decoding packet pool */
1407 	batadv_nc_skb_store_for_decoding(bat_priv, skb);
1408 
1409 	/* batadv_nc_skb_store_for_decoding() clones the skb, so we must free
1410 	 * our ref
1411 	 */
1412 	consume_skb(skb);
1413 }
1414 
1415 /**
1416  * batadv_nc_skb_dst_search() - Loops through list of neighboring nodes to dst.
1417  * @skb: data skb to forward
1418  * @neigh_node: next hop to forward packet to
1419  * @ethhdr: pointer to the ethernet header inside the skb
1420  *
1421  * Loops through list of neighboring nodes the next hop has a good connection to
1422  * (receives OGMs with a sufficient quality). We need to find a neighbor of our
1423  * next hop that potentially sent a packet which our next hop also received
1424  * (overheard) and has stored for later decoding.
1425  *
1426  * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1427  */
1428 static bool batadv_nc_skb_dst_search(struct sk_buff *skb,
1429 				     struct batadv_neigh_node *neigh_node,
1430 				     struct ethhdr *ethhdr)
1431 {
1432 	struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1433 	struct batadv_priv *bat_priv = netdev_priv(netdev);
1434 	struct batadv_orig_node *orig_node = neigh_node->orig_node;
1435 	struct batadv_nc_node *nc_node;
1436 	struct batadv_nc_packet *nc_packet = NULL;
1437 
1438 	rcu_read_lock();
1439 	list_for_each_entry_rcu(nc_node, &orig_node->in_coding_list, list) {
1440 		/* Search for coding opportunity with this in_nc_node */
1441 		nc_packet = batadv_nc_skb_src_search(bat_priv, skb,
1442 						     neigh_node->addr,
1443 						     ethhdr->h_source, nc_node);
1444 
1445 		/* Opportunity was found, so stop searching */
1446 		if (nc_packet)
1447 			break;
1448 	}
1449 	rcu_read_unlock();
1450 
1451 	if (!nc_packet)
1452 		return false;
1453 
1454 	/* Save packets for later decoding */
1455 	batadv_nc_skb_store_before_coding(bat_priv, skb,
1456 					  neigh_node->addr);
1457 	batadv_nc_skb_store_before_coding(bat_priv, nc_packet->skb,
1458 					  nc_packet->neigh_node->addr);
1459 
1460 	/* Code and send packets */
1461 	if (batadv_nc_code_packets(bat_priv, skb, ethhdr, nc_packet,
1462 				   neigh_node))
1463 		return true;
1464 
1465 	/* out of mem ? Coding failed - we have to free the buffered packet
1466 	 * to avoid memleaks. The skb passed as argument will be dealt with
1467 	 * by the calling function.
1468 	 */
1469 	batadv_nc_send_packet(nc_packet);
1470 	return false;
1471 }
1472 
1473 /**
1474  * batadv_nc_skb_add_to_path() - buffer skb for later encoding / decoding
1475  * @skb: skb to add to path
1476  * @nc_path: path to add skb to
1477  * @neigh_node: next hop to forward packet to
1478  * @packet_id: checksum to identify packet
1479  *
1480  * Return: true if the packet was buffered or false in case of an error.
1481  */
1482 static bool batadv_nc_skb_add_to_path(struct sk_buff *skb,
1483 				      struct batadv_nc_path *nc_path,
1484 				      struct batadv_neigh_node *neigh_node,
1485 				      __be32 packet_id)
1486 {
1487 	struct batadv_nc_packet *nc_packet;
1488 
1489 	nc_packet = kzalloc(sizeof(*nc_packet), GFP_ATOMIC);
1490 	if (!nc_packet)
1491 		return false;
1492 
1493 	/* Initialize nc_packet */
1494 	nc_packet->timestamp = jiffies;
1495 	nc_packet->packet_id = packet_id;
1496 	nc_packet->skb = skb;
1497 	nc_packet->neigh_node = neigh_node;
1498 	nc_packet->nc_path = nc_path;
1499 
1500 	/* Add coding packet to list */
1501 	spin_lock_bh(&nc_path->packet_list_lock);
1502 	list_add_tail(&nc_packet->list, &nc_path->packet_list);
1503 	spin_unlock_bh(&nc_path->packet_list_lock);
1504 
1505 	return true;
1506 }
1507 
1508 /**
1509  * batadv_nc_skb_forward() - try to code a packet or add it to the coding packet
1510  *  buffer
1511  * @skb: data skb to forward
1512  * @neigh_node: next hop to forward packet to
1513  *
1514  * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1515  */
1516 bool batadv_nc_skb_forward(struct sk_buff *skb,
1517 			   struct batadv_neigh_node *neigh_node)
1518 {
1519 	const struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1520 	struct batadv_priv *bat_priv = netdev_priv(netdev);
1521 	struct batadv_unicast_packet *packet;
1522 	struct batadv_nc_path *nc_path;
1523 	struct ethhdr *ethhdr = eth_hdr(skb);
1524 	__be32 packet_id;
1525 	u8 *payload;
1526 
1527 	/* Check if network coding is enabled */
1528 	if (!atomic_read(&bat_priv->network_coding))
1529 		goto out;
1530 
1531 	/* We only handle unicast packets */
1532 	payload = skb_network_header(skb);
1533 	packet = (struct batadv_unicast_packet *)payload;
1534 	if (packet->packet_type != BATADV_UNICAST)
1535 		goto out;
1536 
1537 	/* Try to find a coding opportunity and send the skb if one is found */
1538 	if (batadv_nc_skb_dst_search(skb, neigh_node, ethhdr))
1539 		return true;
1540 
1541 	/* Find or create a nc_path for this src-dst pair */
1542 	nc_path = batadv_nc_get_path(bat_priv,
1543 				     bat_priv->nc.coding_hash,
1544 				     ethhdr->h_source,
1545 				     neigh_node->addr);
1546 
1547 	if (!nc_path)
1548 		goto out;
1549 
1550 	/* Add skb to nc_path */
1551 	packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1552 	if (!batadv_nc_skb_add_to_path(skb, nc_path, neigh_node, packet_id))
1553 		goto free_nc_path;
1554 
1555 	/* Packet is consumed */
1556 	return true;
1557 
1558 free_nc_path:
1559 	batadv_nc_path_put(nc_path);
1560 out:
1561 	/* Packet is not consumed */
1562 	return false;
1563 }
1564 
1565 /**
1566  * batadv_nc_skb_store_for_decoding() - save a clone of the skb which can be
1567  *  used when decoding coded packets
1568  * @bat_priv: the bat priv with all the soft interface information
1569  * @skb: data skb to store
1570  */
1571 void batadv_nc_skb_store_for_decoding(struct batadv_priv *bat_priv,
1572 				      struct sk_buff *skb)
1573 {
1574 	struct batadv_unicast_packet *packet;
1575 	struct batadv_nc_path *nc_path;
1576 	struct ethhdr *ethhdr = eth_hdr(skb);
1577 	__be32 packet_id;
1578 	u8 *payload;
1579 
1580 	/* Check if network coding is enabled */
1581 	if (!atomic_read(&bat_priv->network_coding))
1582 		goto out;
1583 
1584 	/* Check for supported packet type */
1585 	payload = skb_network_header(skb);
1586 	packet = (struct batadv_unicast_packet *)payload;
1587 	if (packet->packet_type != BATADV_UNICAST)
1588 		goto out;
1589 
1590 	/* Find existing nc_path or create a new */
1591 	nc_path = batadv_nc_get_path(bat_priv,
1592 				     bat_priv->nc.decoding_hash,
1593 				     ethhdr->h_source,
1594 				     ethhdr->h_dest);
1595 
1596 	if (!nc_path)
1597 		goto out;
1598 
1599 	/* Clone skb and adjust skb->data to point at batman header */
1600 	skb = skb_clone(skb, GFP_ATOMIC);
1601 	if (unlikely(!skb))
1602 		goto free_nc_path;
1603 
1604 	if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
1605 		goto free_skb;
1606 
1607 	if (unlikely(!skb_pull_rcsum(skb, ETH_HLEN)))
1608 		goto free_skb;
1609 
1610 	/* Add skb to nc_path */
1611 	packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1612 	if (!batadv_nc_skb_add_to_path(skb, nc_path, NULL, packet_id))
1613 		goto free_skb;
1614 
1615 	batadv_inc_counter(bat_priv, BATADV_CNT_NC_BUFFER);
1616 	return;
1617 
1618 free_skb:
1619 	kfree_skb(skb);
1620 free_nc_path:
1621 	batadv_nc_path_put(nc_path);
1622 out:
1623 	return;
1624 }
1625 
1626 /**
1627  * batadv_nc_skb_store_sniffed_unicast() - check if a received unicast packet
1628  *  should be saved in the decoding buffer and, if so, store it there
1629  * @bat_priv: the bat priv with all the soft interface information
1630  * @skb: unicast skb to store
1631  */
1632 void batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv,
1633 					 struct sk_buff *skb)
1634 {
1635 	struct ethhdr *ethhdr = eth_hdr(skb);
1636 
1637 	if (batadv_is_my_mac(bat_priv, ethhdr->h_dest))
1638 		return;
1639 
1640 	/* Set data pointer to MAC header to mimic packets from our tx path */
1641 	skb_push(skb, ETH_HLEN);
1642 
1643 	batadv_nc_skb_store_for_decoding(bat_priv, skb);
1644 }
1645 
1646 /**
1647  * batadv_nc_skb_decode_packet() - decode given skb using the decode data stored
1648  *  in nc_packet
1649  * @bat_priv: the bat priv with all the soft interface information
1650  * @skb: unicast skb to decode
1651  * @nc_packet: decode data needed to decode the skb
1652  *
1653  * Return: pointer to decoded unicast packet if the packet was decoded or NULL
1654  * in case of an error.
1655  */
1656 static struct batadv_unicast_packet *
1657 batadv_nc_skb_decode_packet(struct batadv_priv *bat_priv, struct sk_buff *skb,
1658 			    struct batadv_nc_packet *nc_packet)
1659 {
1660 	const int h_size = sizeof(struct batadv_unicast_packet);
1661 	const int h_diff = sizeof(struct batadv_coded_packet) - h_size;
1662 	struct batadv_unicast_packet *unicast_packet;
1663 	struct batadv_coded_packet coded_packet_tmp;
1664 	struct ethhdr *ethhdr, ethhdr_tmp;
1665 	u8 *orig_dest, ttl, ttvn;
1666 	unsigned int coding_len;
1667 	int err;
1668 
1669 	/* Save headers temporarily */
1670 	memcpy(&coded_packet_tmp, skb->data, sizeof(coded_packet_tmp));
1671 	memcpy(&ethhdr_tmp, skb_mac_header(skb), sizeof(ethhdr_tmp));
1672 
1673 	if (skb_cow(skb, 0) < 0)
1674 		return NULL;
1675 
1676 	if (unlikely(!skb_pull_rcsum(skb, h_diff)))
1677 		return NULL;
1678 
1679 	/* Data points to batman header, so set mac header 14 bytes before
1680 	 * and network to data
1681 	 */
1682 	skb_set_mac_header(skb, -ETH_HLEN);
1683 	skb_reset_network_header(skb);
1684 
1685 	/* Reconstruct original mac header */
1686 	ethhdr = eth_hdr(skb);
1687 	*ethhdr = ethhdr_tmp;
1688 
1689 	/* Select the correct unicast header information based on the location
1690 	 * of our mac address in the coded_packet header
1691 	 */
1692 	if (batadv_is_my_mac(bat_priv, coded_packet_tmp.second_dest)) {
1693 		/* If we are the second destination the packet was overheard,
1694 		 * so the Ethernet address must be copied to h_dest and
1695 		 * pkt_type changed from PACKET_OTHERHOST to PACKET_HOST
1696 		 */
1697 		ether_addr_copy(ethhdr->h_dest, coded_packet_tmp.second_dest);
1698 		skb->pkt_type = PACKET_HOST;
1699 
1700 		orig_dest = coded_packet_tmp.second_orig_dest;
1701 		ttl = coded_packet_tmp.second_ttl;
1702 		ttvn = coded_packet_tmp.second_ttvn;
1703 	} else {
1704 		orig_dest = coded_packet_tmp.first_orig_dest;
1705 		ttl = coded_packet_tmp.ttl;
1706 		ttvn = coded_packet_tmp.first_ttvn;
1707 	}
1708 
1709 	coding_len = ntohs(coded_packet_tmp.coded_len);
1710 
1711 	if (coding_len > skb->len)
1712 		return NULL;
1713 
1714 	/* Here the magic is reversed:
1715 	 *   extract the missing packet from the received coded packet
1716 	 */
1717 	batadv_nc_memxor(skb->data + h_size,
1718 			 nc_packet->skb->data + h_size,
1719 			 coding_len);
1720 
1721 	/* Resize decoded skb if decoded with larger packet */
1722 	if (nc_packet->skb->len > coding_len + h_size) {
1723 		err = pskb_trim_rcsum(skb, coding_len + h_size);
1724 		if (err)
1725 			return NULL;
1726 	}
1727 
1728 	/* Create decoded unicast packet */
1729 	unicast_packet = (struct batadv_unicast_packet *)skb->data;
1730 	unicast_packet->packet_type = BATADV_UNICAST;
1731 	unicast_packet->version = BATADV_COMPAT_VERSION;
1732 	unicast_packet->ttl = ttl;
1733 	ether_addr_copy(unicast_packet->dest, orig_dest);
1734 	unicast_packet->ttvn = ttvn;
1735 
1736 	batadv_nc_packet_free(nc_packet, false);
1737 	return unicast_packet;
1738 }
1739 
1740 /**
1741  * batadv_nc_find_decoding_packet() - search through buffered decoding data to
1742  *  find the data needed to decode the coded packet
1743  * @bat_priv: the bat priv with all the soft interface information
1744  * @ethhdr: pointer to the ethernet header inside the coded packet
1745  * @coded: coded packet we try to find decode data for
1746  *
1747  * Return: pointer to nc packet if the needed data was found or NULL otherwise.
1748  */
1749 static struct batadv_nc_packet *
1750 batadv_nc_find_decoding_packet(struct batadv_priv *bat_priv,
1751 			       struct ethhdr *ethhdr,
1752 			       struct batadv_coded_packet *coded)
1753 {
1754 	struct batadv_hashtable *hash = bat_priv->nc.decoding_hash;
1755 	struct batadv_nc_packet *tmp_nc_packet, *nc_packet = NULL;
1756 	struct batadv_nc_path *nc_path, nc_path_key;
1757 	u8 *dest, *source;
1758 	__be32 packet_id;
1759 	int index;
1760 
1761 	if (!hash)
1762 		return NULL;
1763 
1764 	/* Select the correct packet id based on the location of our mac-addr */
1765 	dest = ethhdr->h_source;
1766 	if (!batadv_is_my_mac(bat_priv, coded->second_dest)) {
1767 		source = coded->second_source;
1768 		packet_id = coded->second_crc;
1769 	} else {
1770 		source = coded->first_source;
1771 		packet_id = coded->first_crc;
1772 	}
1773 
1774 	batadv_nc_hash_key_gen(&nc_path_key, source, dest);
1775 	index = batadv_nc_hash_choose(&nc_path_key, hash->size);
1776 
1777 	/* Search for matching coding path */
1778 	rcu_read_lock();
1779 	hlist_for_each_entry_rcu(nc_path, &hash->table[index], hash_entry) {
1780 		/* Find matching nc_packet */
1781 		spin_lock_bh(&nc_path->packet_list_lock);
1782 		list_for_each_entry(tmp_nc_packet,
1783 				    &nc_path->packet_list, list) {
1784 			if (packet_id == tmp_nc_packet->packet_id) {
1785 				list_del(&tmp_nc_packet->list);
1786 
1787 				nc_packet = tmp_nc_packet;
1788 				break;
1789 			}
1790 		}
1791 		spin_unlock_bh(&nc_path->packet_list_lock);
1792 
1793 		if (nc_packet)
1794 			break;
1795 	}
1796 	rcu_read_unlock();
1797 
1798 	if (!nc_packet)
1799 		batadv_dbg(BATADV_DBG_NC, bat_priv,
1800 			   "No decoding packet found for %u\n", packet_id);
1801 
1802 	return nc_packet;
1803 }
1804 
1805 /**
1806  * batadv_nc_recv_coded_packet() - try to decode coded packet and enqueue the
1807  *  resulting unicast packet
1808  * @skb: incoming coded packet
1809  * @recv_if: pointer to interface this packet was received on
1810  *
1811  * Return: NET_RX_SUCCESS if the packet has been consumed or NET_RX_DROP
1812  * otherwise.
1813  */
1814 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
1815 				       struct batadv_hard_iface *recv_if)
1816 {
1817 	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
1818 	struct batadv_unicast_packet *unicast_packet;
1819 	struct batadv_coded_packet *coded_packet;
1820 	struct batadv_nc_packet *nc_packet;
1821 	struct ethhdr *ethhdr;
1822 	int hdr_size = sizeof(*coded_packet);
1823 
1824 	/* Check if network coding is enabled */
1825 	if (!atomic_read(&bat_priv->network_coding))
1826 		goto free_skb;
1827 
1828 	/* Make sure we can access (and remove) header */
1829 	if (unlikely(!pskb_may_pull(skb, hdr_size)))
1830 		goto free_skb;
1831 
1832 	coded_packet = (struct batadv_coded_packet *)skb->data;
1833 	ethhdr = eth_hdr(skb);
1834 
1835 	/* Verify frame is destined for us */
1836 	if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest) &&
1837 	    !batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1838 		goto free_skb;
1839 
1840 	/* Update stat counter */
1841 	if (batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1842 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_SNIFFED);
1843 
1844 	nc_packet = batadv_nc_find_decoding_packet(bat_priv, ethhdr,
1845 						   coded_packet);
1846 	if (!nc_packet) {
1847 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1848 		goto free_skb;
1849 	}
1850 
1851 	/* Make skb's linear, because decoding accesses the entire buffer */
1852 	if (skb_linearize(skb) < 0)
1853 		goto free_nc_packet;
1854 
1855 	if (skb_linearize(nc_packet->skb) < 0)
1856 		goto free_nc_packet;
1857 
1858 	/* Decode the packet */
1859 	unicast_packet = batadv_nc_skb_decode_packet(bat_priv, skb, nc_packet);
1860 	if (!unicast_packet) {
1861 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1862 		goto free_nc_packet;
1863 	}
1864 
1865 	/* Mark packet as decoded to do correct recoding when forwarding */
1866 	BATADV_SKB_CB(skb)->decoded = true;
1867 	batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE);
1868 	batadv_add_counter(bat_priv, BATADV_CNT_NC_DECODE_BYTES,
1869 			   skb->len + ETH_HLEN);
1870 	return batadv_recv_unicast_packet(skb, recv_if);
1871 
1872 free_nc_packet:
1873 	batadv_nc_packet_free(nc_packet, true);
1874 free_skb:
1875 	kfree_skb(skb);
1876 
1877 	return NET_RX_DROP;
1878 }
1879 
1880 /**
1881  * batadv_nc_mesh_free() - clean up network coding memory
1882  * @bat_priv: the bat priv with all the soft interface information
1883  */
1884 void batadv_nc_mesh_free(struct batadv_priv *bat_priv)
1885 {
1886 	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
1887 	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_NC, 1);
1888 	cancel_delayed_work_sync(&bat_priv->nc.work);
1889 
1890 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash, NULL);
1891 	batadv_hash_destroy(bat_priv->nc.coding_hash);
1892 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash, NULL);
1893 	batadv_hash_destroy(bat_priv->nc.decoding_hash);
1894 }
1895 
1896 #ifdef CONFIG_BATMAN_ADV_DEBUGFS
1897 /**
1898  * batadv_nc_nodes_seq_print_text() - print the nc node information
1899  * @seq: seq file to print on
1900  * @offset: not used
1901  *
1902  * Return: always 0
1903  */
1904 int batadv_nc_nodes_seq_print_text(struct seq_file *seq, void *offset)
1905 {
1906 	struct net_device *net_dev = (struct net_device *)seq->private;
1907 	struct batadv_priv *bat_priv = netdev_priv(net_dev);
1908 	struct batadv_hashtable *hash = bat_priv->orig_hash;
1909 	struct batadv_hard_iface *primary_if;
1910 	struct hlist_head *head;
1911 	struct batadv_orig_node *orig_node;
1912 	struct batadv_nc_node *nc_node;
1913 	int i;
1914 
1915 	primary_if = batadv_seq_print_text_primary_if_get(seq);
1916 	if (!primary_if)
1917 		goto out;
1918 
1919 	/* Traverse list of originators */
1920 	for (i = 0; i < hash->size; i++) {
1921 		head = &hash->table[i];
1922 
1923 		/* For each orig_node in this bin */
1924 		rcu_read_lock();
1925 		hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
1926 			/* no need to print the orig node if it does not have
1927 			 * network coding neighbors
1928 			 */
1929 			if (list_empty(&orig_node->in_coding_list) &&
1930 			    list_empty(&orig_node->out_coding_list))
1931 				continue;
1932 
1933 			seq_printf(seq, "Node:      %pM\n", orig_node->orig);
1934 
1935 			seq_puts(seq, " Ingoing:  ");
1936 			/* For each in_nc_node to this orig_node */
1937 			list_for_each_entry_rcu(nc_node,
1938 						&orig_node->in_coding_list,
1939 						list)
1940 				seq_printf(seq, "%pM ",
1941 					   nc_node->addr);
1942 			seq_puts(seq, "\n Outgoing: ");
1943 			/* For out_nc_node to this orig_node */
1944 			list_for_each_entry_rcu(nc_node,
1945 						&orig_node->out_coding_list,
1946 						list)
1947 				seq_printf(seq, "%pM ",
1948 					   nc_node->addr);
1949 			seq_puts(seq, "\n\n");
1950 		}
1951 		rcu_read_unlock();
1952 	}
1953 
1954 out:
1955 	if (primary_if)
1956 		batadv_hardif_put(primary_if);
1957 	return 0;
1958 }
1959 
1960 /**
1961  * batadv_nc_init_debugfs() - create nc folder and related files in debugfs
1962  * @bat_priv: the bat priv with all the soft interface information
1963  *
1964  * Return: 0 on success or negative error number in case of failure
1965  */
1966 int batadv_nc_init_debugfs(struct batadv_priv *bat_priv)
1967 {
1968 	struct dentry *nc_dir, *file;
1969 
1970 	nc_dir = debugfs_create_dir("nc", bat_priv->debug_dir);
1971 	if (!nc_dir)
1972 		goto out;
1973 
1974 	file = debugfs_create_u8("min_tq", 0644, nc_dir, &bat_priv->nc.min_tq);
1975 	if (!file)
1976 		goto out;
1977 
1978 	file = debugfs_create_u32("max_fwd_delay", 0644, nc_dir,
1979 				  &bat_priv->nc.max_fwd_delay);
1980 	if (!file)
1981 		goto out;
1982 
1983 	file = debugfs_create_u32("max_buffer_time", 0644, nc_dir,
1984 				  &bat_priv->nc.max_buffer_time);
1985 	if (!file)
1986 		goto out;
1987 
1988 	return 0;
1989 
1990 out:
1991 	return -ENOMEM;
1992 }
1993 #endif
1994