1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) 2012-2020  B.A.T.M.A.N. contributors:
3  *
4  * Martin Hundebøll, Jeppe Ledet-Pedersen
5  */
6 
7 #include "network-coding.h"
8 #include "main.h"
9 
10 #include <linux/atomic.h>
11 #include <linux/bitops.h>
12 #include <linux/byteorder/generic.h>
13 #include <linux/compiler.h>
14 #include <linux/debugfs.h>
15 #include <linux/errno.h>
16 #include <linux/etherdevice.h>
17 #include <linux/gfp.h>
18 #include <linux/if_ether.h>
19 #include <linux/if_packet.h>
20 #include <linux/init.h>
21 #include <linux/jhash.h>
22 #include <linux/jiffies.h>
23 #include <linux/kernel.h>
24 #include <linux/kref.h>
25 #include <linux/list.h>
26 #include <linux/lockdep.h>
27 #include <linux/net.h>
28 #include <linux/netdevice.h>
29 #include <linux/printk.h>
30 #include <linux/random.h>
31 #include <linux/rculist.h>
32 #include <linux/rcupdate.h>
33 #include <linux/seq_file.h>
34 #include <linux/skbuff.h>
35 #include <linux/slab.h>
36 #include <linux/spinlock.h>
37 #include <linux/stddef.h>
38 #include <linux/string.h>
39 #include <linux/workqueue.h>
40 #include <uapi/linux/batadv_packet.h>
41 
42 #include "hard-interface.h"
43 #include "hash.h"
44 #include "log.h"
45 #include "originator.h"
46 #include "routing.h"
47 #include "send.h"
48 #include "tvlv.h"
49 
50 static struct lock_class_key batadv_nc_coding_hash_lock_class_key;
51 static struct lock_class_key batadv_nc_decoding_hash_lock_class_key;
52 
53 static void batadv_nc_worker(struct work_struct *work);
54 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
55 				       struct batadv_hard_iface *recv_if);
56 
57 /**
58  * batadv_nc_init() - one-time initialization for network coding
59  *
60  * Return: 0 on success or negative error number in case of failure
61  */
62 int __init batadv_nc_init(void)
63 {
64 	int ret;
65 
66 	/* Register our packet type */
67 	ret = batadv_recv_handler_register(BATADV_CODED,
68 					   batadv_nc_recv_coded_packet);
69 
70 	return ret;
71 }
72 
73 /**
74  * batadv_nc_start_timer() - initialise the nc periodic worker
75  * @bat_priv: the bat priv with all the soft interface information
76  */
77 static void batadv_nc_start_timer(struct batadv_priv *bat_priv)
78 {
79 	queue_delayed_work(batadv_event_workqueue, &bat_priv->nc.work,
80 			   msecs_to_jiffies(10));
81 }
82 
83 /**
84  * batadv_nc_tvlv_container_update() - update the network coding tvlv container
85  *  after network coding setting change
86  * @bat_priv: the bat priv with all the soft interface information
87  */
88 static void batadv_nc_tvlv_container_update(struct batadv_priv *bat_priv)
89 {
90 	char nc_mode;
91 
92 	nc_mode = atomic_read(&bat_priv->network_coding);
93 
94 	switch (nc_mode) {
95 	case 0:
96 		batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
97 		break;
98 	case 1:
99 		batadv_tvlv_container_register(bat_priv, BATADV_TVLV_NC, 1,
100 					       NULL, 0);
101 		break;
102 	}
103 }
104 
105 /**
106  * batadv_nc_status_update() - update the network coding tvlv container after
107  *  network coding setting change
108  * @net_dev: the soft interface net device
109  */
110 void batadv_nc_status_update(struct net_device *net_dev)
111 {
112 	struct batadv_priv *bat_priv = netdev_priv(net_dev);
113 
114 	batadv_nc_tvlv_container_update(bat_priv);
115 }
116 
117 /**
118  * batadv_nc_tvlv_ogm_handler_v1() - process incoming nc tvlv container
119  * @bat_priv: the bat priv with all the soft interface information
120  * @orig: the orig_node of the ogm
121  * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
122  * @tvlv_value: tvlv buffer containing the gateway data
123  * @tvlv_value_len: tvlv buffer length
124  */
125 static void batadv_nc_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
126 					  struct batadv_orig_node *orig,
127 					  u8 flags,
128 					  void *tvlv_value, u16 tvlv_value_len)
129 {
130 	if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
131 		clear_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
132 	else
133 		set_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
134 }
135 
136 /**
137  * batadv_nc_mesh_init() - initialise coding hash table and start house keeping
138  * @bat_priv: the bat priv with all the soft interface information
139  *
140  * Return: 0 on success or negative error number in case of failure
141  */
142 int batadv_nc_mesh_init(struct batadv_priv *bat_priv)
143 {
144 	bat_priv->nc.timestamp_fwd_flush = jiffies;
145 	bat_priv->nc.timestamp_sniffed_purge = jiffies;
146 
147 	if (bat_priv->nc.coding_hash || bat_priv->nc.decoding_hash)
148 		return 0;
149 
150 	bat_priv->nc.coding_hash = batadv_hash_new(128);
151 	if (!bat_priv->nc.coding_hash)
152 		goto err;
153 
154 	batadv_hash_set_lock_class(bat_priv->nc.coding_hash,
155 				   &batadv_nc_coding_hash_lock_class_key);
156 
157 	bat_priv->nc.decoding_hash = batadv_hash_new(128);
158 	if (!bat_priv->nc.decoding_hash)
159 		goto err;
160 
161 	batadv_hash_set_lock_class(bat_priv->nc.decoding_hash,
162 				   &batadv_nc_decoding_hash_lock_class_key);
163 
164 	INIT_DELAYED_WORK(&bat_priv->nc.work, batadv_nc_worker);
165 	batadv_nc_start_timer(bat_priv);
166 
167 	batadv_tvlv_handler_register(bat_priv, batadv_nc_tvlv_ogm_handler_v1,
168 				     NULL, BATADV_TVLV_NC, 1,
169 				     BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
170 	batadv_nc_tvlv_container_update(bat_priv);
171 	return 0;
172 
173 err:
174 	return -ENOMEM;
175 }
176 
177 /**
178  * batadv_nc_init_bat_priv() - initialise the nc specific bat_priv variables
179  * @bat_priv: the bat priv with all the soft interface information
180  */
181 void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv)
182 {
183 	atomic_set(&bat_priv->network_coding, 0);
184 	bat_priv->nc.min_tq = 200;
185 	bat_priv->nc.max_fwd_delay = 10;
186 	bat_priv->nc.max_buffer_time = 200;
187 }
188 
189 /**
190  * batadv_nc_init_orig() - initialise the nc fields of an orig_node
191  * @orig_node: the orig_node which is going to be initialised
192  */
193 void batadv_nc_init_orig(struct batadv_orig_node *orig_node)
194 {
195 	INIT_LIST_HEAD(&orig_node->in_coding_list);
196 	INIT_LIST_HEAD(&orig_node->out_coding_list);
197 	spin_lock_init(&orig_node->in_coding_list_lock);
198 	spin_lock_init(&orig_node->out_coding_list_lock);
199 }
200 
201 /**
202  * batadv_nc_node_release() - release nc_node from lists and queue for free
203  *  after rcu grace period
204  * @ref: kref pointer of the nc_node
205  */
206 static void batadv_nc_node_release(struct kref *ref)
207 {
208 	struct batadv_nc_node *nc_node;
209 
210 	nc_node = container_of(ref, struct batadv_nc_node, refcount);
211 
212 	batadv_orig_node_put(nc_node->orig_node);
213 	kfree_rcu(nc_node, rcu);
214 }
215 
216 /**
217  * batadv_nc_node_put() - decrement the nc_node refcounter and possibly
218  *  release it
219  * @nc_node: nc_node to be free'd
220  */
221 static void batadv_nc_node_put(struct batadv_nc_node *nc_node)
222 {
223 	kref_put(&nc_node->refcount, batadv_nc_node_release);
224 }
225 
226 /**
227  * batadv_nc_path_release() - release nc_path from lists and queue for free
228  *  after rcu grace period
229  * @ref: kref pointer of the nc_path
230  */
231 static void batadv_nc_path_release(struct kref *ref)
232 {
233 	struct batadv_nc_path *nc_path;
234 
235 	nc_path = container_of(ref, struct batadv_nc_path, refcount);
236 
237 	kfree_rcu(nc_path, rcu);
238 }
239 
240 /**
241  * batadv_nc_path_put() - decrement the nc_path refcounter and possibly
242  *  release it
243  * @nc_path: nc_path to be free'd
244  */
245 static void batadv_nc_path_put(struct batadv_nc_path *nc_path)
246 {
247 	kref_put(&nc_path->refcount, batadv_nc_path_release);
248 }
249 
250 /**
251  * batadv_nc_packet_free() - frees nc packet
252  * @nc_packet: the nc packet to free
253  * @dropped: whether the packet is freed because is is dropped
254  */
255 static void batadv_nc_packet_free(struct batadv_nc_packet *nc_packet,
256 				  bool dropped)
257 {
258 	if (dropped)
259 		kfree_skb(nc_packet->skb);
260 	else
261 		consume_skb(nc_packet->skb);
262 
263 	batadv_nc_path_put(nc_packet->nc_path);
264 	kfree(nc_packet);
265 }
266 
267 /**
268  * batadv_nc_to_purge_nc_node() - checks whether an nc node has to be purged
269  * @bat_priv: the bat priv with all the soft interface information
270  * @nc_node: the nc node to check
271  *
272  * Return: true if the entry has to be purged now, false otherwise
273  */
274 static bool batadv_nc_to_purge_nc_node(struct batadv_priv *bat_priv,
275 				       struct batadv_nc_node *nc_node)
276 {
277 	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
278 		return true;
279 
280 	return batadv_has_timed_out(nc_node->last_seen, BATADV_NC_NODE_TIMEOUT);
281 }
282 
283 /**
284  * batadv_nc_to_purge_nc_path_coding() - checks whether an nc path has timed out
285  * @bat_priv: the bat priv with all the soft interface information
286  * @nc_path: the nc path to check
287  *
288  * Return: true if the entry has to be purged now, false otherwise
289  */
290 static bool batadv_nc_to_purge_nc_path_coding(struct batadv_priv *bat_priv,
291 					      struct batadv_nc_path *nc_path)
292 {
293 	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
294 		return true;
295 
296 	/* purge the path when no packets has been added for 10 times the
297 	 * max_fwd_delay time
298 	 */
299 	return batadv_has_timed_out(nc_path->last_valid,
300 				    bat_priv->nc.max_fwd_delay * 10);
301 }
302 
303 /**
304  * batadv_nc_to_purge_nc_path_decoding() - checks whether an nc path has timed
305  *  out
306  * @bat_priv: the bat priv with all the soft interface information
307  * @nc_path: the nc path to check
308  *
309  * Return: true if the entry has to be purged now, false otherwise
310  */
311 static bool batadv_nc_to_purge_nc_path_decoding(struct batadv_priv *bat_priv,
312 						struct batadv_nc_path *nc_path)
313 {
314 	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
315 		return true;
316 
317 	/* purge the path when no packets has been added for 10 times the
318 	 * max_buffer time
319 	 */
320 	return batadv_has_timed_out(nc_path->last_valid,
321 				    bat_priv->nc.max_buffer_time * 10);
322 }
323 
324 /**
325  * batadv_nc_purge_orig_nc_nodes() - go through list of nc nodes and purge stale
326  *  entries
327  * @bat_priv: the bat priv with all the soft interface information
328  * @list: list of nc nodes
329  * @lock: nc node list lock
330  * @to_purge: function in charge to decide whether an entry has to be purged or
331  *	      not. This function takes the nc node as argument and has to return
332  *	      a boolean value: true if the entry has to be deleted, false
333  *	      otherwise
334  */
335 static void
336 batadv_nc_purge_orig_nc_nodes(struct batadv_priv *bat_priv,
337 			      struct list_head *list,
338 			      spinlock_t *lock,
339 			      bool (*to_purge)(struct batadv_priv *,
340 					       struct batadv_nc_node *))
341 {
342 	struct batadv_nc_node *nc_node, *nc_node_tmp;
343 
344 	/* For each nc_node in list */
345 	spin_lock_bh(lock);
346 	list_for_each_entry_safe(nc_node, nc_node_tmp, list, list) {
347 		/* if an helper function has been passed as parameter,
348 		 * ask it if the entry has to be purged or not
349 		 */
350 		if (to_purge && !to_purge(bat_priv, nc_node))
351 			continue;
352 
353 		batadv_dbg(BATADV_DBG_NC, bat_priv,
354 			   "Removing nc_node %pM -> %pM\n",
355 			   nc_node->addr, nc_node->orig_node->orig);
356 		list_del_rcu(&nc_node->list);
357 		batadv_nc_node_put(nc_node);
358 	}
359 	spin_unlock_bh(lock);
360 }
361 
362 /**
363  * batadv_nc_purge_orig() - purges all nc node data attached of the given
364  *  originator
365  * @bat_priv: the bat priv with all the soft interface information
366  * @orig_node: orig_node with the nc node entries to be purged
367  * @to_purge: function in charge to decide whether an entry has to be purged or
368  *	      not. This function takes the nc node as argument and has to return
369  *	      a boolean value: true is the entry has to be deleted, false
370  *	      otherwise
371  */
372 void batadv_nc_purge_orig(struct batadv_priv *bat_priv,
373 			  struct batadv_orig_node *orig_node,
374 			  bool (*to_purge)(struct batadv_priv *,
375 					   struct batadv_nc_node *))
376 {
377 	/* Check ingoing nc_node's of this orig_node */
378 	batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->in_coding_list,
379 				      &orig_node->in_coding_list_lock,
380 				      to_purge);
381 
382 	/* Check outgoing nc_node's of this orig_node */
383 	batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->out_coding_list,
384 				      &orig_node->out_coding_list_lock,
385 				      to_purge);
386 }
387 
388 /**
389  * batadv_nc_purge_orig_hash() - traverse entire originator hash to check if
390  *  they have timed out nc nodes
391  * @bat_priv: the bat priv with all the soft interface information
392  */
393 static void batadv_nc_purge_orig_hash(struct batadv_priv *bat_priv)
394 {
395 	struct batadv_hashtable *hash = bat_priv->orig_hash;
396 	struct hlist_head *head;
397 	struct batadv_orig_node *orig_node;
398 	u32 i;
399 
400 	if (!hash)
401 		return;
402 
403 	/* For each orig_node */
404 	for (i = 0; i < hash->size; i++) {
405 		head = &hash->table[i];
406 
407 		rcu_read_lock();
408 		hlist_for_each_entry_rcu(orig_node, head, hash_entry)
409 			batadv_nc_purge_orig(bat_priv, orig_node,
410 					     batadv_nc_to_purge_nc_node);
411 		rcu_read_unlock();
412 	}
413 }
414 
415 /**
416  * batadv_nc_purge_paths() - traverse all nc paths part of the hash and remove
417  *  unused ones
418  * @bat_priv: the bat priv with all the soft interface information
419  * @hash: hash table containing the nc paths to check
420  * @to_purge: function in charge to decide whether an entry has to be purged or
421  *	      not. This function takes the nc node as argument and has to return
422  *	      a boolean value: true is the entry has to be deleted, false
423  *	      otherwise
424  */
425 static void batadv_nc_purge_paths(struct batadv_priv *bat_priv,
426 				  struct batadv_hashtable *hash,
427 				  bool (*to_purge)(struct batadv_priv *,
428 						   struct batadv_nc_path *))
429 {
430 	struct hlist_head *head;
431 	struct hlist_node *node_tmp;
432 	struct batadv_nc_path *nc_path;
433 	spinlock_t *lock; /* Protects lists in hash */
434 	u32 i;
435 
436 	for (i = 0; i < hash->size; i++) {
437 		head = &hash->table[i];
438 		lock = &hash->list_locks[i];
439 
440 		/* For each nc_path in this bin */
441 		spin_lock_bh(lock);
442 		hlist_for_each_entry_safe(nc_path, node_tmp, head, hash_entry) {
443 			/* if an helper function has been passed as parameter,
444 			 * ask it if the entry has to be purged or not
445 			 */
446 			if (to_purge && !to_purge(bat_priv, nc_path))
447 				continue;
448 
449 			/* purging an non-empty nc_path should never happen, but
450 			 * is observed under high CPU load. Delay the purging
451 			 * until next iteration to allow the packet_list to be
452 			 * emptied first.
453 			 */
454 			if (!unlikely(list_empty(&nc_path->packet_list))) {
455 				net_ratelimited_function(printk,
456 							 KERN_WARNING
457 							 "Skipping free of non-empty nc_path (%pM -> %pM)!\n",
458 							 nc_path->prev_hop,
459 							 nc_path->next_hop);
460 				continue;
461 			}
462 
463 			/* nc_path is unused, so remove it */
464 			batadv_dbg(BATADV_DBG_NC, bat_priv,
465 				   "Remove nc_path %pM -> %pM\n",
466 				   nc_path->prev_hop, nc_path->next_hop);
467 			hlist_del_rcu(&nc_path->hash_entry);
468 			batadv_nc_path_put(nc_path);
469 		}
470 		spin_unlock_bh(lock);
471 	}
472 }
473 
474 /**
475  * batadv_nc_hash_key_gen() - computes the nc_path hash key
476  * @key: buffer to hold the final hash key
477  * @src: source ethernet mac address going into the hash key
478  * @dst: destination ethernet mac address going into the hash key
479  */
480 static void batadv_nc_hash_key_gen(struct batadv_nc_path *key, const char *src,
481 				   const char *dst)
482 {
483 	memcpy(key->prev_hop, src, sizeof(key->prev_hop));
484 	memcpy(key->next_hop, dst, sizeof(key->next_hop));
485 }
486 
487 /**
488  * batadv_nc_hash_choose() - compute the hash value for an nc path
489  * @data: data to hash
490  * @size: size of the hash table
491  *
492  * Return: the selected index in the hash table for the given data.
493  */
494 static u32 batadv_nc_hash_choose(const void *data, u32 size)
495 {
496 	const struct batadv_nc_path *nc_path = data;
497 	u32 hash = 0;
498 
499 	hash = jhash(&nc_path->prev_hop, sizeof(nc_path->prev_hop), hash);
500 	hash = jhash(&nc_path->next_hop, sizeof(nc_path->next_hop), hash);
501 
502 	return hash % size;
503 }
504 
505 /**
506  * batadv_nc_hash_compare() - comparing function used in the network coding hash
507  *  tables
508  * @node: node in the local table
509  * @data2: second object to compare the node to
510  *
511  * Return: true if the two entry are the same, false otherwise
512  */
513 static bool batadv_nc_hash_compare(const struct hlist_node *node,
514 				   const void *data2)
515 {
516 	const struct batadv_nc_path *nc_path1, *nc_path2;
517 
518 	nc_path1 = container_of(node, struct batadv_nc_path, hash_entry);
519 	nc_path2 = data2;
520 
521 	/* Return 1 if the two keys are identical */
522 	if (!batadv_compare_eth(nc_path1->prev_hop, nc_path2->prev_hop))
523 		return false;
524 
525 	if (!batadv_compare_eth(nc_path1->next_hop, nc_path2->next_hop))
526 		return false;
527 
528 	return true;
529 }
530 
531 /**
532  * batadv_nc_hash_find() - search for an existing nc path and return it
533  * @hash: hash table containing the nc path
534  * @data: search key
535  *
536  * Return: the nc_path if found, NULL otherwise.
537  */
538 static struct batadv_nc_path *
539 batadv_nc_hash_find(struct batadv_hashtable *hash,
540 		    void *data)
541 {
542 	struct hlist_head *head;
543 	struct batadv_nc_path *nc_path, *nc_path_tmp = NULL;
544 	int index;
545 
546 	if (!hash)
547 		return NULL;
548 
549 	index = batadv_nc_hash_choose(data, hash->size);
550 	head = &hash->table[index];
551 
552 	rcu_read_lock();
553 	hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
554 		if (!batadv_nc_hash_compare(&nc_path->hash_entry, data))
555 			continue;
556 
557 		if (!kref_get_unless_zero(&nc_path->refcount))
558 			continue;
559 
560 		nc_path_tmp = nc_path;
561 		break;
562 	}
563 	rcu_read_unlock();
564 
565 	return nc_path_tmp;
566 }
567 
568 /**
569  * batadv_nc_send_packet() - send non-coded packet and free nc_packet struct
570  * @nc_packet: the nc packet to send
571  */
572 static void batadv_nc_send_packet(struct batadv_nc_packet *nc_packet)
573 {
574 	batadv_send_unicast_skb(nc_packet->skb, nc_packet->neigh_node);
575 	nc_packet->skb = NULL;
576 	batadv_nc_packet_free(nc_packet, false);
577 }
578 
579 /**
580  * batadv_nc_sniffed_purge() - Checks timestamp of given sniffed nc_packet.
581  * @bat_priv: the bat priv with all the soft interface information
582  * @nc_path: the nc path the packet belongs to
583  * @nc_packet: the nc packet to be checked
584  *
585  * Checks whether the given sniffed (overheard) nc_packet has hit its buffering
586  * timeout. If so, the packet is no longer kept and the entry deleted from the
587  * queue. Has to be called with the appropriate locks.
588  *
589  * Return: false as soon as the entry in the fifo queue has not been timed out
590  * yet and true otherwise.
591  */
592 static bool batadv_nc_sniffed_purge(struct batadv_priv *bat_priv,
593 				    struct batadv_nc_path *nc_path,
594 				    struct batadv_nc_packet *nc_packet)
595 {
596 	unsigned long timeout = bat_priv->nc.max_buffer_time;
597 	bool res = false;
598 
599 	lockdep_assert_held(&nc_path->packet_list_lock);
600 
601 	/* Packets are added to tail, so the remaining packets did not time
602 	 * out and we can stop processing the current queue
603 	 */
604 	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
605 	    !batadv_has_timed_out(nc_packet->timestamp, timeout))
606 		goto out;
607 
608 	/* purge nc packet */
609 	list_del(&nc_packet->list);
610 	batadv_nc_packet_free(nc_packet, true);
611 
612 	res = true;
613 
614 out:
615 	return res;
616 }
617 
618 /**
619  * batadv_nc_fwd_flush() - Checks the timestamp of the given nc packet.
620  * @bat_priv: the bat priv with all the soft interface information
621  * @nc_path: the nc path the packet belongs to
622  * @nc_packet: the nc packet to be checked
623  *
624  * Checks whether the given nc packet has hit its forward timeout. If so, the
625  * packet is no longer delayed, immediately sent and the entry deleted from the
626  * queue. Has to be called with the appropriate locks.
627  *
628  * Return: false as soon as the entry in the fifo queue has not been timed out
629  * yet and true otherwise.
630  */
631 static bool batadv_nc_fwd_flush(struct batadv_priv *bat_priv,
632 				struct batadv_nc_path *nc_path,
633 				struct batadv_nc_packet *nc_packet)
634 {
635 	unsigned long timeout = bat_priv->nc.max_fwd_delay;
636 
637 	lockdep_assert_held(&nc_path->packet_list_lock);
638 
639 	/* Packets are added to tail, so the remaining packets did not time
640 	 * out and we can stop processing the current queue
641 	 */
642 	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
643 	    !batadv_has_timed_out(nc_packet->timestamp, timeout))
644 		return false;
645 
646 	/* Send packet */
647 	batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
648 	batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
649 			   nc_packet->skb->len + ETH_HLEN);
650 	list_del(&nc_packet->list);
651 	batadv_nc_send_packet(nc_packet);
652 
653 	return true;
654 }
655 
656 /**
657  * batadv_nc_process_nc_paths() - traverse given nc packet pool and free timed
658  *  out nc packets
659  * @bat_priv: the bat priv with all the soft interface information
660  * @hash: to be processed hash table
661  * @process_fn: Function called to process given nc packet. Should return true
662  *	        to encourage this function to proceed with the next packet.
663  *	        Otherwise the rest of the current queue is skipped.
664  */
665 static void
666 batadv_nc_process_nc_paths(struct batadv_priv *bat_priv,
667 			   struct batadv_hashtable *hash,
668 			   bool (*process_fn)(struct batadv_priv *,
669 					      struct batadv_nc_path *,
670 					      struct batadv_nc_packet *))
671 {
672 	struct hlist_head *head;
673 	struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
674 	struct batadv_nc_path *nc_path;
675 	bool ret;
676 	int i;
677 
678 	if (!hash)
679 		return;
680 
681 	/* Loop hash table bins */
682 	for (i = 0; i < hash->size; i++) {
683 		head = &hash->table[i];
684 
685 		/* Loop coding paths */
686 		rcu_read_lock();
687 		hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
688 			/* Loop packets */
689 			spin_lock_bh(&nc_path->packet_list_lock);
690 			list_for_each_entry_safe(nc_packet, nc_packet_tmp,
691 						 &nc_path->packet_list, list) {
692 				ret = process_fn(bat_priv, nc_path, nc_packet);
693 				if (!ret)
694 					break;
695 			}
696 			spin_unlock_bh(&nc_path->packet_list_lock);
697 		}
698 		rcu_read_unlock();
699 	}
700 }
701 
702 /**
703  * batadv_nc_worker() - periodic task for house keeping related to network
704  *  coding
705  * @work: kernel work struct
706  */
707 static void batadv_nc_worker(struct work_struct *work)
708 {
709 	struct delayed_work *delayed_work;
710 	struct batadv_priv_nc *priv_nc;
711 	struct batadv_priv *bat_priv;
712 	unsigned long timeout;
713 
714 	delayed_work = to_delayed_work(work);
715 	priv_nc = container_of(delayed_work, struct batadv_priv_nc, work);
716 	bat_priv = container_of(priv_nc, struct batadv_priv, nc);
717 
718 	batadv_nc_purge_orig_hash(bat_priv);
719 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash,
720 			      batadv_nc_to_purge_nc_path_coding);
721 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash,
722 			      batadv_nc_to_purge_nc_path_decoding);
723 
724 	timeout = bat_priv->nc.max_fwd_delay;
725 
726 	if (batadv_has_timed_out(bat_priv->nc.timestamp_fwd_flush, timeout)) {
727 		batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.coding_hash,
728 					   batadv_nc_fwd_flush);
729 		bat_priv->nc.timestamp_fwd_flush = jiffies;
730 	}
731 
732 	if (batadv_has_timed_out(bat_priv->nc.timestamp_sniffed_purge,
733 				 bat_priv->nc.max_buffer_time)) {
734 		batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.decoding_hash,
735 					   batadv_nc_sniffed_purge);
736 		bat_priv->nc.timestamp_sniffed_purge = jiffies;
737 	}
738 
739 	/* Schedule a new check */
740 	batadv_nc_start_timer(bat_priv);
741 }
742 
743 /**
744  * batadv_can_nc_with_orig() - checks whether the given orig node is suitable
745  *  for coding or not
746  * @bat_priv: the bat priv with all the soft interface information
747  * @orig_node: neighboring orig node which may be used as nc candidate
748  * @ogm_packet: incoming ogm packet also used for the checks
749  *
750  * Return: true if:
751  *  1) The OGM must have the most recent sequence number.
752  *  2) The TTL must be decremented by one and only one.
753  *  3) The OGM must be received from the first hop from orig_node.
754  *  4) The TQ value of the OGM must be above bat_priv->nc.min_tq.
755  */
756 static bool batadv_can_nc_with_orig(struct batadv_priv *bat_priv,
757 				    struct batadv_orig_node *orig_node,
758 				    struct batadv_ogm_packet *ogm_packet)
759 {
760 	struct batadv_orig_ifinfo *orig_ifinfo;
761 	u32 last_real_seqno;
762 	u8 last_ttl;
763 
764 	orig_ifinfo = batadv_orig_ifinfo_get(orig_node, BATADV_IF_DEFAULT);
765 	if (!orig_ifinfo)
766 		return false;
767 
768 	last_ttl = orig_ifinfo->last_ttl;
769 	last_real_seqno = orig_ifinfo->last_real_seqno;
770 	batadv_orig_ifinfo_put(orig_ifinfo);
771 
772 	if (last_real_seqno != ntohl(ogm_packet->seqno))
773 		return false;
774 	if (last_ttl != ogm_packet->ttl + 1)
775 		return false;
776 	if (!batadv_compare_eth(ogm_packet->orig, ogm_packet->prev_sender))
777 		return false;
778 	if (ogm_packet->tq < bat_priv->nc.min_tq)
779 		return false;
780 
781 	return true;
782 }
783 
784 /**
785  * batadv_nc_find_nc_node() - search for an existing nc node and return it
786  * @orig_node: orig node originating the ogm packet
787  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
788  *  (can be equal to orig_node)
789  * @in_coding: traverse incoming or outgoing network coding list
790  *
791  * Return: the nc_node if found, NULL otherwise.
792  */
793 static struct batadv_nc_node *
794 batadv_nc_find_nc_node(struct batadv_orig_node *orig_node,
795 		       struct batadv_orig_node *orig_neigh_node,
796 		       bool in_coding)
797 {
798 	struct batadv_nc_node *nc_node, *nc_node_out = NULL;
799 	struct list_head *list;
800 
801 	if (in_coding)
802 		list = &orig_neigh_node->in_coding_list;
803 	else
804 		list = &orig_neigh_node->out_coding_list;
805 
806 	/* Traverse list of nc_nodes to orig_node */
807 	rcu_read_lock();
808 	list_for_each_entry_rcu(nc_node, list, list) {
809 		if (!batadv_compare_eth(nc_node->addr, orig_node->orig))
810 			continue;
811 
812 		if (!kref_get_unless_zero(&nc_node->refcount))
813 			continue;
814 
815 		/* Found a match */
816 		nc_node_out = nc_node;
817 		break;
818 	}
819 	rcu_read_unlock();
820 
821 	return nc_node_out;
822 }
823 
824 /**
825  * batadv_nc_get_nc_node() - retrieves an nc node or creates the entry if it was
826  *  not found
827  * @bat_priv: the bat priv with all the soft interface information
828  * @orig_node: orig node originating the ogm packet
829  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
830  *  (can be equal to orig_node)
831  * @in_coding: traverse incoming or outgoing network coding list
832  *
833  * Return: the nc_node if found or created, NULL in case of an error.
834  */
835 static struct batadv_nc_node *
836 batadv_nc_get_nc_node(struct batadv_priv *bat_priv,
837 		      struct batadv_orig_node *orig_node,
838 		      struct batadv_orig_node *orig_neigh_node,
839 		      bool in_coding)
840 {
841 	struct batadv_nc_node *nc_node;
842 	spinlock_t *lock; /* Used to lock list selected by "int in_coding" */
843 	struct list_head *list;
844 
845 	/* Select ingoing or outgoing coding node */
846 	if (in_coding) {
847 		lock = &orig_neigh_node->in_coding_list_lock;
848 		list = &orig_neigh_node->in_coding_list;
849 	} else {
850 		lock = &orig_neigh_node->out_coding_list_lock;
851 		list = &orig_neigh_node->out_coding_list;
852 	}
853 
854 	spin_lock_bh(lock);
855 
856 	/* Check if nc_node is already added */
857 	nc_node = batadv_nc_find_nc_node(orig_node, orig_neigh_node, in_coding);
858 
859 	/* Node found */
860 	if (nc_node)
861 		goto unlock;
862 
863 	nc_node = kzalloc(sizeof(*nc_node), GFP_ATOMIC);
864 	if (!nc_node)
865 		goto unlock;
866 
867 	/* Initialize nc_node */
868 	INIT_LIST_HEAD(&nc_node->list);
869 	kref_init(&nc_node->refcount);
870 	ether_addr_copy(nc_node->addr, orig_node->orig);
871 	kref_get(&orig_neigh_node->refcount);
872 	nc_node->orig_node = orig_neigh_node;
873 
874 	batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_node %pM -> %pM\n",
875 		   nc_node->addr, nc_node->orig_node->orig);
876 
877 	/* Add nc_node to orig_node */
878 	kref_get(&nc_node->refcount);
879 	list_add_tail_rcu(&nc_node->list, list);
880 
881 unlock:
882 	spin_unlock_bh(lock);
883 
884 	return nc_node;
885 }
886 
887 /**
888  * batadv_nc_update_nc_node() - updates stored incoming and outgoing nc node
889  *  structs (best called on incoming OGMs)
890  * @bat_priv: the bat priv with all the soft interface information
891  * @orig_node: orig node originating the ogm packet
892  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
893  *  (can be equal to orig_node)
894  * @ogm_packet: incoming ogm packet
895  * @is_single_hop_neigh: orig_node is a single hop neighbor
896  */
897 void batadv_nc_update_nc_node(struct batadv_priv *bat_priv,
898 			      struct batadv_orig_node *orig_node,
899 			      struct batadv_orig_node *orig_neigh_node,
900 			      struct batadv_ogm_packet *ogm_packet,
901 			      int is_single_hop_neigh)
902 {
903 	struct batadv_nc_node *in_nc_node = NULL;
904 	struct batadv_nc_node *out_nc_node = NULL;
905 
906 	/* Check if network coding is enabled */
907 	if (!atomic_read(&bat_priv->network_coding))
908 		goto out;
909 
910 	/* check if orig node is network coding enabled */
911 	if (!test_bit(BATADV_ORIG_CAPA_HAS_NC, &orig_node->capabilities))
912 		goto out;
913 
914 	/* accept ogms from 'good' neighbors and single hop neighbors */
915 	if (!batadv_can_nc_with_orig(bat_priv, orig_node, ogm_packet) &&
916 	    !is_single_hop_neigh)
917 		goto out;
918 
919 	/* Add orig_node as in_nc_node on hop */
920 	in_nc_node = batadv_nc_get_nc_node(bat_priv, orig_node,
921 					   orig_neigh_node, true);
922 	if (!in_nc_node)
923 		goto out;
924 
925 	in_nc_node->last_seen = jiffies;
926 
927 	/* Add hop as out_nc_node on orig_node */
928 	out_nc_node = batadv_nc_get_nc_node(bat_priv, orig_neigh_node,
929 					    orig_node, false);
930 	if (!out_nc_node)
931 		goto out;
932 
933 	out_nc_node->last_seen = jiffies;
934 
935 out:
936 	if (in_nc_node)
937 		batadv_nc_node_put(in_nc_node);
938 	if (out_nc_node)
939 		batadv_nc_node_put(out_nc_node);
940 }
941 
942 /**
943  * batadv_nc_get_path() - get existing nc_path or allocate a new one
944  * @bat_priv: the bat priv with all the soft interface information
945  * @hash: hash table containing the nc path
946  * @src: ethernet source address - first half of the nc path search key
947  * @dst: ethernet destination address - second half of the nc path search key
948  *
949  * Return: pointer to nc_path if the path was found or created, returns NULL
950  * on error.
951  */
952 static struct batadv_nc_path *batadv_nc_get_path(struct batadv_priv *bat_priv,
953 						 struct batadv_hashtable *hash,
954 						 u8 *src,
955 						 u8 *dst)
956 {
957 	int hash_added;
958 	struct batadv_nc_path *nc_path, nc_path_key;
959 
960 	batadv_nc_hash_key_gen(&nc_path_key, src, dst);
961 
962 	/* Search for existing nc_path */
963 	nc_path = batadv_nc_hash_find(hash, (void *)&nc_path_key);
964 
965 	if (nc_path) {
966 		/* Set timestamp to delay removal of nc_path */
967 		nc_path->last_valid = jiffies;
968 		return nc_path;
969 	}
970 
971 	/* No existing nc_path was found; create a new */
972 	nc_path = kzalloc(sizeof(*nc_path), GFP_ATOMIC);
973 
974 	if (!nc_path)
975 		return NULL;
976 
977 	/* Initialize nc_path */
978 	INIT_LIST_HEAD(&nc_path->packet_list);
979 	spin_lock_init(&nc_path->packet_list_lock);
980 	kref_init(&nc_path->refcount);
981 	nc_path->last_valid = jiffies;
982 	ether_addr_copy(nc_path->next_hop, dst);
983 	ether_addr_copy(nc_path->prev_hop, src);
984 
985 	batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_path %pM -> %pM\n",
986 		   nc_path->prev_hop,
987 		   nc_path->next_hop);
988 
989 	/* Add nc_path to hash table */
990 	kref_get(&nc_path->refcount);
991 	hash_added = batadv_hash_add(hash, batadv_nc_hash_compare,
992 				     batadv_nc_hash_choose, &nc_path_key,
993 				     &nc_path->hash_entry);
994 
995 	if (hash_added < 0) {
996 		kfree(nc_path);
997 		return NULL;
998 	}
999 
1000 	return nc_path;
1001 }
1002 
1003 /**
1004  * batadv_nc_random_weight_tq() - scale the receivers TQ-value to avoid unfair
1005  *  selection of a receiver with slightly lower TQ than the other
1006  * @tq: to be weighted tq value
1007  *
1008  * Return: scaled tq value
1009  */
1010 static u8 batadv_nc_random_weight_tq(u8 tq)
1011 {
1012 	u8 rand_val, rand_tq;
1013 
1014 	get_random_bytes(&rand_val, sizeof(rand_val));
1015 
1016 	/* randomize the estimated packet loss (max TQ - estimated TQ) */
1017 	rand_tq = rand_val * (BATADV_TQ_MAX_VALUE - tq);
1018 
1019 	/* normalize the randomized packet loss */
1020 	rand_tq /= BATADV_TQ_MAX_VALUE;
1021 
1022 	/* convert to (randomized) estimated tq again */
1023 	return BATADV_TQ_MAX_VALUE - rand_tq;
1024 }
1025 
1026 /**
1027  * batadv_nc_memxor() - XOR destination with source
1028  * @dst: byte array to XOR into
1029  * @src: byte array to XOR from
1030  * @len: length of destination array
1031  */
1032 static void batadv_nc_memxor(char *dst, const char *src, unsigned int len)
1033 {
1034 	unsigned int i;
1035 
1036 	for (i = 0; i < len; ++i)
1037 		dst[i] ^= src[i];
1038 }
1039 
1040 /**
1041  * batadv_nc_code_packets() - code a received unicast_packet with an nc packet
1042  *  into a coded_packet and send it
1043  * @bat_priv: the bat priv with all the soft interface information
1044  * @skb: data skb to forward
1045  * @ethhdr: pointer to the ethernet header inside the skb
1046  * @nc_packet: structure containing the packet to the skb can be coded with
1047  * @neigh_node: next hop to forward packet to
1048  *
1049  * Return: true if both packets are consumed, false otherwise.
1050  */
1051 static bool batadv_nc_code_packets(struct batadv_priv *bat_priv,
1052 				   struct sk_buff *skb,
1053 				   struct ethhdr *ethhdr,
1054 				   struct batadv_nc_packet *nc_packet,
1055 				   struct batadv_neigh_node *neigh_node)
1056 {
1057 	u8 tq_weighted_neigh, tq_weighted_coding, tq_tmp;
1058 	struct sk_buff *skb_dest, *skb_src;
1059 	struct batadv_unicast_packet *packet1;
1060 	struct batadv_unicast_packet *packet2;
1061 	struct batadv_coded_packet *coded_packet;
1062 	struct batadv_neigh_node *neigh_tmp, *router_neigh, *first_dest;
1063 	struct batadv_neigh_node *router_coding = NULL, *second_dest;
1064 	struct batadv_neigh_ifinfo *router_neigh_ifinfo = NULL;
1065 	struct batadv_neigh_ifinfo *router_coding_ifinfo = NULL;
1066 	u8 *first_source, *second_source;
1067 	__be32 packet_id1, packet_id2;
1068 	size_t count;
1069 	bool res = false;
1070 	int coding_len;
1071 	int unicast_size = sizeof(*packet1);
1072 	int coded_size = sizeof(*coded_packet);
1073 	int header_add = coded_size - unicast_size;
1074 
1075 	/* TODO: do we need to consider the outgoing interface for
1076 	 * coded packets?
1077 	 */
1078 	router_neigh = batadv_orig_router_get(neigh_node->orig_node,
1079 					      BATADV_IF_DEFAULT);
1080 	if (!router_neigh)
1081 		goto out;
1082 
1083 	router_neigh_ifinfo = batadv_neigh_ifinfo_get(router_neigh,
1084 						      BATADV_IF_DEFAULT);
1085 	if (!router_neigh_ifinfo)
1086 		goto out;
1087 
1088 	neigh_tmp = nc_packet->neigh_node;
1089 	router_coding = batadv_orig_router_get(neigh_tmp->orig_node,
1090 					       BATADV_IF_DEFAULT);
1091 	if (!router_coding)
1092 		goto out;
1093 
1094 	router_coding_ifinfo = batadv_neigh_ifinfo_get(router_coding,
1095 						       BATADV_IF_DEFAULT);
1096 	if (!router_coding_ifinfo)
1097 		goto out;
1098 
1099 	tq_tmp = router_neigh_ifinfo->bat_iv.tq_avg;
1100 	tq_weighted_neigh = batadv_nc_random_weight_tq(tq_tmp);
1101 	tq_tmp = router_coding_ifinfo->bat_iv.tq_avg;
1102 	tq_weighted_coding = batadv_nc_random_weight_tq(tq_tmp);
1103 
1104 	/* Select one destination for the MAC-header dst-field based on
1105 	 * weighted TQ-values.
1106 	 */
1107 	if (tq_weighted_neigh >= tq_weighted_coding) {
1108 		/* Destination from nc_packet is selected for MAC-header */
1109 		first_dest = nc_packet->neigh_node;
1110 		first_source = nc_packet->nc_path->prev_hop;
1111 		second_dest = neigh_node;
1112 		second_source = ethhdr->h_source;
1113 		packet1 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1114 		packet2 = (struct batadv_unicast_packet *)skb->data;
1115 		packet_id1 = nc_packet->packet_id;
1116 		packet_id2 = batadv_skb_crc32(skb,
1117 					      skb->data + sizeof(*packet2));
1118 	} else {
1119 		/* Destination for skb is selected for MAC-header */
1120 		first_dest = neigh_node;
1121 		first_source = ethhdr->h_source;
1122 		second_dest = nc_packet->neigh_node;
1123 		second_source = nc_packet->nc_path->prev_hop;
1124 		packet1 = (struct batadv_unicast_packet *)skb->data;
1125 		packet2 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1126 		packet_id1 = batadv_skb_crc32(skb,
1127 					      skb->data + sizeof(*packet1));
1128 		packet_id2 = nc_packet->packet_id;
1129 	}
1130 
1131 	/* Instead of zero padding the smallest data buffer, we
1132 	 * code into the largest.
1133 	 */
1134 	if (skb->len <= nc_packet->skb->len) {
1135 		skb_dest = nc_packet->skb;
1136 		skb_src = skb;
1137 	} else {
1138 		skb_dest = skb;
1139 		skb_src = nc_packet->skb;
1140 	}
1141 
1142 	/* coding_len is used when decoding the packet shorter packet */
1143 	coding_len = skb_src->len - unicast_size;
1144 
1145 	if (skb_linearize(skb_dest) < 0 || skb_linearize(skb_src) < 0)
1146 		goto out;
1147 
1148 	skb_push(skb_dest, header_add);
1149 
1150 	coded_packet = (struct batadv_coded_packet *)skb_dest->data;
1151 	skb_reset_mac_header(skb_dest);
1152 
1153 	coded_packet->packet_type = BATADV_CODED;
1154 	coded_packet->version = BATADV_COMPAT_VERSION;
1155 	coded_packet->ttl = packet1->ttl;
1156 
1157 	/* Info about first unicast packet */
1158 	ether_addr_copy(coded_packet->first_source, first_source);
1159 	ether_addr_copy(coded_packet->first_orig_dest, packet1->dest);
1160 	coded_packet->first_crc = packet_id1;
1161 	coded_packet->first_ttvn = packet1->ttvn;
1162 
1163 	/* Info about second unicast packet */
1164 	ether_addr_copy(coded_packet->second_dest, second_dest->addr);
1165 	ether_addr_copy(coded_packet->second_source, second_source);
1166 	ether_addr_copy(coded_packet->second_orig_dest, packet2->dest);
1167 	coded_packet->second_crc = packet_id2;
1168 	coded_packet->second_ttl = packet2->ttl;
1169 	coded_packet->second_ttvn = packet2->ttvn;
1170 	coded_packet->coded_len = htons(coding_len);
1171 
1172 	/* This is where the magic happens: Code skb_src into skb_dest */
1173 	batadv_nc_memxor(skb_dest->data + coded_size,
1174 			 skb_src->data + unicast_size, coding_len);
1175 
1176 	/* Update counters accordingly */
1177 	if (BATADV_SKB_CB(skb_src)->decoded &&
1178 	    BATADV_SKB_CB(skb_dest)->decoded) {
1179 		/* Both packets are recoded */
1180 		count = skb_src->len + ETH_HLEN;
1181 		count += skb_dest->len + ETH_HLEN;
1182 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE, 2);
1183 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, count);
1184 	} else if (!BATADV_SKB_CB(skb_src)->decoded &&
1185 		   !BATADV_SKB_CB(skb_dest)->decoded) {
1186 		/* Both packets are newly coded */
1187 		count = skb_src->len + ETH_HLEN;
1188 		count += skb_dest->len + ETH_HLEN;
1189 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE, 2);
1190 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, count);
1191 	} else if (BATADV_SKB_CB(skb_src)->decoded &&
1192 		   !BATADV_SKB_CB(skb_dest)->decoded) {
1193 		/* skb_src recoded and skb_dest is newly coded */
1194 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1195 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1196 				   skb_src->len + ETH_HLEN);
1197 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1198 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1199 				   skb_dest->len + ETH_HLEN);
1200 	} else if (!BATADV_SKB_CB(skb_src)->decoded &&
1201 		   BATADV_SKB_CB(skb_dest)->decoded) {
1202 		/* skb_src is newly coded and skb_dest is recoded */
1203 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1204 		batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1205 				   skb_src->len + ETH_HLEN);
1206 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1207 		batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1208 				   skb_dest->len + ETH_HLEN);
1209 	}
1210 
1211 	/* skb_src is now coded into skb_dest, so free it */
1212 	consume_skb(skb_src);
1213 
1214 	/* avoid duplicate free of skb from nc_packet */
1215 	nc_packet->skb = NULL;
1216 	batadv_nc_packet_free(nc_packet, false);
1217 
1218 	/* Send the coded packet and return true */
1219 	batadv_send_unicast_skb(skb_dest, first_dest);
1220 	res = true;
1221 out:
1222 	if (router_neigh)
1223 		batadv_neigh_node_put(router_neigh);
1224 	if (router_coding)
1225 		batadv_neigh_node_put(router_coding);
1226 	if (router_neigh_ifinfo)
1227 		batadv_neigh_ifinfo_put(router_neigh_ifinfo);
1228 	if (router_coding_ifinfo)
1229 		batadv_neigh_ifinfo_put(router_coding_ifinfo);
1230 	return res;
1231 }
1232 
1233 /**
1234  * batadv_nc_skb_coding_possible() - true if a decoded skb is available at dst.
1235  * @skb: data skb to forward
1236  * @dst: destination mac address of the other skb to code with
1237  * @src: source mac address of skb
1238  *
1239  * Whenever we network code a packet we have to check whether we received it in
1240  * a network coded form. If so, we may not be able to use it for coding because
1241  * some neighbors may also have received (overheard) the packet in the network
1242  * coded form without being able to decode it. It is hard to know which of the
1243  * neighboring nodes was able to decode the packet, therefore we can only
1244  * re-code the packet if the source of the previous encoded packet is involved.
1245  * Since the source encoded the packet we can be certain it has all necessary
1246  * decode information.
1247  *
1248  * Return: true if coding of a decoded packet is allowed.
1249  */
1250 static bool batadv_nc_skb_coding_possible(struct sk_buff *skb, u8 *dst, u8 *src)
1251 {
1252 	if (BATADV_SKB_CB(skb)->decoded && !batadv_compare_eth(dst, src))
1253 		return false;
1254 	return true;
1255 }
1256 
1257 /**
1258  * batadv_nc_path_search() - Find the coding path matching in_nc_node and
1259  *  out_nc_node to retrieve a buffered packet that can be used for coding.
1260  * @bat_priv: the bat priv with all the soft interface information
1261  * @in_nc_node: pointer to skb next hop's neighbor nc node
1262  * @out_nc_node: pointer to skb source's neighbor nc node
1263  * @skb: data skb to forward
1264  * @eth_dst: next hop mac address of skb
1265  *
1266  * Return: true if coding of a decoded skb is allowed.
1267  */
1268 static struct batadv_nc_packet *
1269 batadv_nc_path_search(struct batadv_priv *bat_priv,
1270 		      struct batadv_nc_node *in_nc_node,
1271 		      struct batadv_nc_node *out_nc_node,
1272 		      struct sk_buff *skb,
1273 		      u8 *eth_dst)
1274 {
1275 	struct batadv_nc_path *nc_path, nc_path_key;
1276 	struct batadv_nc_packet *nc_packet_out = NULL;
1277 	struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
1278 	struct batadv_hashtable *hash = bat_priv->nc.coding_hash;
1279 	int idx;
1280 
1281 	if (!hash)
1282 		return NULL;
1283 
1284 	/* Create almost path key */
1285 	batadv_nc_hash_key_gen(&nc_path_key, in_nc_node->addr,
1286 			       out_nc_node->addr);
1287 	idx = batadv_nc_hash_choose(&nc_path_key, hash->size);
1288 
1289 	/* Check for coding opportunities in this nc_path */
1290 	rcu_read_lock();
1291 	hlist_for_each_entry_rcu(nc_path, &hash->table[idx], hash_entry) {
1292 		if (!batadv_compare_eth(nc_path->prev_hop, in_nc_node->addr))
1293 			continue;
1294 
1295 		if (!batadv_compare_eth(nc_path->next_hop, out_nc_node->addr))
1296 			continue;
1297 
1298 		spin_lock_bh(&nc_path->packet_list_lock);
1299 		if (list_empty(&nc_path->packet_list)) {
1300 			spin_unlock_bh(&nc_path->packet_list_lock);
1301 			continue;
1302 		}
1303 
1304 		list_for_each_entry_safe(nc_packet, nc_packet_tmp,
1305 					 &nc_path->packet_list, list) {
1306 			if (!batadv_nc_skb_coding_possible(nc_packet->skb,
1307 							   eth_dst,
1308 							   in_nc_node->addr))
1309 				continue;
1310 
1311 			/* Coding opportunity is found! */
1312 			list_del(&nc_packet->list);
1313 			nc_packet_out = nc_packet;
1314 			break;
1315 		}
1316 
1317 		spin_unlock_bh(&nc_path->packet_list_lock);
1318 		break;
1319 	}
1320 	rcu_read_unlock();
1321 
1322 	return nc_packet_out;
1323 }
1324 
1325 /**
1326  * batadv_nc_skb_src_search() - Loops through the list of neighoring nodes of
1327  *  the skb's sender (may be equal to the originator).
1328  * @bat_priv: the bat priv with all the soft interface information
1329  * @skb: data skb to forward
1330  * @eth_dst: next hop mac address of skb
1331  * @eth_src: source mac address of skb
1332  * @in_nc_node: pointer to skb next hop's neighbor nc node
1333  *
1334  * Return: an nc packet if a suitable coding packet was found, NULL otherwise.
1335  */
1336 static struct batadv_nc_packet *
1337 batadv_nc_skb_src_search(struct batadv_priv *bat_priv,
1338 			 struct sk_buff *skb,
1339 			 u8 *eth_dst,
1340 			 u8 *eth_src,
1341 			 struct batadv_nc_node *in_nc_node)
1342 {
1343 	struct batadv_orig_node *orig_node;
1344 	struct batadv_nc_node *out_nc_node;
1345 	struct batadv_nc_packet *nc_packet = NULL;
1346 
1347 	orig_node = batadv_orig_hash_find(bat_priv, eth_src);
1348 	if (!orig_node)
1349 		return NULL;
1350 
1351 	rcu_read_lock();
1352 	list_for_each_entry_rcu(out_nc_node,
1353 				&orig_node->out_coding_list, list) {
1354 		/* Check if the skb is decoded and if recoding is possible */
1355 		if (!batadv_nc_skb_coding_possible(skb,
1356 						   out_nc_node->addr, eth_src))
1357 			continue;
1358 
1359 		/* Search for an opportunity in this nc_path */
1360 		nc_packet = batadv_nc_path_search(bat_priv, in_nc_node,
1361 						  out_nc_node, skb, eth_dst);
1362 		if (nc_packet)
1363 			break;
1364 	}
1365 	rcu_read_unlock();
1366 
1367 	batadv_orig_node_put(orig_node);
1368 	return nc_packet;
1369 }
1370 
1371 /**
1372  * batadv_nc_skb_store_before_coding() - set the ethernet src and dst of the
1373  *  unicast skb before it is stored for use in later decoding
1374  * @bat_priv: the bat priv with all the soft interface information
1375  * @skb: data skb to store
1376  * @eth_dst_new: new destination mac address of skb
1377  */
1378 static void batadv_nc_skb_store_before_coding(struct batadv_priv *bat_priv,
1379 					      struct sk_buff *skb,
1380 					      u8 *eth_dst_new)
1381 {
1382 	struct ethhdr *ethhdr;
1383 
1384 	/* Copy skb header to change the mac header */
1385 	skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
1386 	if (!skb)
1387 		return;
1388 
1389 	/* Set the mac header as if we actually sent the packet uncoded */
1390 	ethhdr = eth_hdr(skb);
1391 	ether_addr_copy(ethhdr->h_source, ethhdr->h_dest);
1392 	ether_addr_copy(ethhdr->h_dest, eth_dst_new);
1393 
1394 	/* Set data pointer to MAC header to mimic packets from our tx path */
1395 	skb_push(skb, ETH_HLEN);
1396 
1397 	/* Add the packet to the decoding packet pool */
1398 	batadv_nc_skb_store_for_decoding(bat_priv, skb);
1399 
1400 	/* batadv_nc_skb_store_for_decoding() clones the skb, so we must free
1401 	 * our ref
1402 	 */
1403 	consume_skb(skb);
1404 }
1405 
1406 /**
1407  * batadv_nc_skb_dst_search() - Loops through list of neighboring nodes to dst.
1408  * @skb: data skb to forward
1409  * @neigh_node: next hop to forward packet to
1410  * @ethhdr: pointer to the ethernet header inside the skb
1411  *
1412  * Loops through list of neighboring nodes the next hop has a good connection to
1413  * (receives OGMs with a sufficient quality). We need to find a neighbor of our
1414  * next hop that potentially sent a packet which our next hop also received
1415  * (overheard) and has stored for later decoding.
1416  *
1417  * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1418  */
1419 static bool batadv_nc_skb_dst_search(struct sk_buff *skb,
1420 				     struct batadv_neigh_node *neigh_node,
1421 				     struct ethhdr *ethhdr)
1422 {
1423 	struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1424 	struct batadv_priv *bat_priv = netdev_priv(netdev);
1425 	struct batadv_orig_node *orig_node = neigh_node->orig_node;
1426 	struct batadv_nc_node *nc_node;
1427 	struct batadv_nc_packet *nc_packet = NULL;
1428 
1429 	rcu_read_lock();
1430 	list_for_each_entry_rcu(nc_node, &orig_node->in_coding_list, list) {
1431 		/* Search for coding opportunity with this in_nc_node */
1432 		nc_packet = batadv_nc_skb_src_search(bat_priv, skb,
1433 						     neigh_node->addr,
1434 						     ethhdr->h_source, nc_node);
1435 
1436 		/* Opportunity was found, so stop searching */
1437 		if (nc_packet)
1438 			break;
1439 	}
1440 	rcu_read_unlock();
1441 
1442 	if (!nc_packet)
1443 		return false;
1444 
1445 	/* Save packets for later decoding */
1446 	batadv_nc_skb_store_before_coding(bat_priv, skb,
1447 					  neigh_node->addr);
1448 	batadv_nc_skb_store_before_coding(bat_priv, nc_packet->skb,
1449 					  nc_packet->neigh_node->addr);
1450 
1451 	/* Code and send packets */
1452 	if (batadv_nc_code_packets(bat_priv, skb, ethhdr, nc_packet,
1453 				   neigh_node))
1454 		return true;
1455 
1456 	/* out of mem ? Coding failed - we have to free the buffered packet
1457 	 * to avoid memleaks. The skb passed as argument will be dealt with
1458 	 * by the calling function.
1459 	 */
1460 	batadv_nc_send_packet(nc_packet);
1461 	return false;
1462 }
1463 
1464 /**
1465  * batadv_nc_skb_add_to_path() - buffer skb for later encoding / decoding
1466  * @skb: skb to add to path
1467  * @nc_path: path to add skb to
1468  * @neigh_node: next hop to forward packet to
1469  * @packet_id: checksum to identify packet
1470  *
1471  * Return: true if the packet was buffered or false in case of an error.
1472  */
1473 static bool batadv_nc_skb_add_to_path(struct sk_buff *skb,
1474 				      struct batadv_nc_path *nc_path,
1475 				      struct batadv_neigh_node *neigh_node,
1476 				      __be32 packet_id)
1477 {
1478 	struct batadv_nc_packet *nc_packet;
1479 
1480 	nc_packet = kzalloc(sizeof(*nc_packet), GFP_ATOMIC);
1481 	if (!nc_packet)
1482 		return false;
1483 
1484 	/* Initialize nc_packet */
1485 	nc_packet->timestamp = jiffies;
1486 	nc_packet->packet_id = packet_id;
1487 	nc_packet->skb = skb;
1488 	nc_packet->neigh_node = neigh_node;
1489 	nc_packet->nc_path = nc_path;
1490 
1491 	/* Add coding packet to list */
1492 	spin_lock_bh(&nc_path->packet_list_lock);
1493 	list_add_tail(&nc_packet->list, &nc_path->packet_list);
1494 	spin_unlock_bh(&nc_path->packet_list_lock);
1495 
1496 	return true;
1497 }
1498 
1499 /**
1500  * batadv_nc_skb_forward() - try to code a packet or add it to the coding packet
1501  *  buffer
1502  * @skb: data skb to forward
1503  * @neigh_node: next hop to forward packet to
1504  *
1505  * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1506  */
1507 bool batadv_nc_skb_forward(struct sk_buff *skb,
1508 			   struct batadv_neigh_node *neigh_node)
1509 {
1510 	const struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1511 	struct batadv_priv *bat_priv = netdev_priv(netdev);
1512 	struct batadv_unicast_packet *packet;
1513 	struct batadv_nc_path *nc_path;
1514 	struct ethhdr *ethhdr = eth_hdr(skb);
1515 	__be32 packet_id;
1516 	u8 *payload;
1517 
1518 	/* Check if network coding is enabled */
1519 	if (!atomic_read(&bat_priv->network_coding))
1520 		goto out;
1521 
1522 	/* We only handle unicast packets */
1523 	payload = skb_network_header(skb);
1524 	packet = (struct batadv_unicast_packet *)payload;
1525 	if (packet->packet_type != BATADV_UNICAST)
1526 		goto out;
1527 
1528 	/* Try to find a coding opportunity and send the skb if one is found */
1529 	if (batadv_nc_skb_dst_search(skb, neigh_node, ethhdr))
1530 		return true;
1531 
1532 	/* Find or create a nc_path for this src-dst pair */
1533 	nc_path = batadv_nc_get_path(bat_priv,
1534 				     bat_priv->nc.coding_hash,
1535 				     ethhdr->h_source,
1536 				     neigh_node->addr);
1537 
1538 	if (!nc_path)
1539 		goto out;
1540 
1541 	/* Add skb to nc_path */
1542 	packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1543 	if (!batadv_nc_skb_add_to_path(skb, nc_path, neigh_node, packet_id))
1544 		goto free_nc_path;
1545 
1546 	/* Packet is consumed */
1547 	return true;
1548 
1549 free_nc_path:
1550 	batadv_nc_path_put(nc_path);
1551 out:
1552 	/* Packet is not consumed */
1553 	return false;
1554 }
1555 
1556 /**
1557  * batadv_nc_skb_store_for_decoding() - save a clone of the skb which can be
1558  *  used when decoding coded packets
1559  * @bat_priv: the bat priv with all the soft interface information
1560  * @skb: data skb to store
1561  */
1562 void batadv_nc_skb_store_for_decoding(struct batadv_priv *bat_priv,
1563 				      struct sk_buff *skb)
1564 {
1565 	struct batadv_unicast_packet *packet;
1566 	struct batadv_nc_path *nc_path;
1567 	struct ethhdr *ethhdr = eth_hdr(skb);
1568 	__be32 packet_id;
1569 	u8 *payload;
1570 
1571 	/* Check if network coding is enabled */
1572 	if (!atomic_read(&bat_priv->network_coding))
1573 		goto out;
1574 
1575 	/* Check for supported packet type */
1576 	payload = skb_network_header(skb);
1577 	packet = (struct batadv_unicast_packet *)payload;
1578 	if (packet->packet_type != BATADV_UNICAST)
1579 		goto out;
1580 
1581 	/* Find existing nc_path or create a new */
1582 	nc_path = batadv_nc_get_path(bat_priv,
1583 				     bat_priv->nc.decoding_hash,
1584 				     ethhdr->h_source,
1585 				     ethhdr->h_dest);
1586 
1587 	if (!nc_path)
1588 		goto out;
1589 
1590 	/* Clone skb and adjust skb->data to point at batman header */
1591 	skb = skb_clone(skb, GFP_ATOMIC);
1592 	if (unlikely(!skb))
1593 		goto free_nc_path;
1594 
1595 	if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
1596 		goto free_skb;
1597 
1598 	if (unlikely(!skb_pull_rcsum(skb, ETH_HLEN)))
1599 		goto free_skb;
1600 
1601 	/* Add skb to nc_path */
1602 	packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1603 	if (!batadv_nc_skb_add_to_path(skb, nc_path, NULL, packet_id))
1604 		goto free_skb;
1605 
1606 	batadv_inc_counter(bat_priv, BATADV_CNT_NC_BUFFER);
1607 	return;
1608 
1609 free_skb:
1610 	kfree_skb(skb);
1611 free_nc_path:
1612 	batadv_nc_path_put(nc_path);
1613 out:
1614 	return;
1615 }
1616 
1617 /**
1618  * batadv_nc_skb_store_sniffed_unicast() - check if a received unicast packet
1619  *  should be saved in the decoding buffer and, if so, store it there
1620  * @bat_priv: the bat priv with all the soft interface information
1621  * @skb: unicast skb to store
1622  */
1623 void batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv,
1624 					 struct sk_buff *skb)
1625 {
1626 	struct ethhdr *ethhdr = eth_hdr(skb);
1627 
1628 	if (batadv_is_my_mac(bat_priv, ethhdr->h_dest))
1629 		return;
1630 
1631 	/* Set data pointer to MAC header to mimic packets from our tx path */
1632 	skb_push(skb, ETH_HLEN);
1633 
1634 	batadv_nc_skb_store_for_decoding(bat_priv, skb);
1635 }
1636 
1637 /**
1638  * batadv_nc_skb_decode_packet() - decode given skb using the decode data stored
1639  *  in nc_packet
1640  * @bat_priv: the bat priv with all the soft interface information
1641  * @skb: unicast skb to decode
1642  * @nc_packet: decode data needed to decode the skb
1643  *
1644  * Return: pointer to decoded unicast packet if the packet was decoded or NULL
1645  * in case of an error.
1646  */
1647 static struct batadv_unicast_packet *
1648 batadv_nc_skb_decode_packet(struct batadv_priv *bat_priv, struct sk_buff *skb,
1649 			    struct batadv_nc_packet *nc_packet)
1650 {
1651 	const int h_size = sizeof(struct batadv_unicast_packet);
1652 	const int h_diff = sizeof(struct batadv_coded_packet) - h_size;
1653 	struct batadv_unicast_packet *unicast_packet;
1654 	struct batadv_coded_packet coded_packet_tmp;
1655 	struct ethhdr *ethhdr, ethhdr_tmp;
1656 	u8 *orig_dest, ttl, ttvn;
1657 	unsigned int coding_len;
1658 	int err;
1659 
1660 	/* Save headers temporarily */
1661 	memcpy(&coded_packet_tmp, skb->data, sizeof(coded_packet_tmp));
1662 	memcpy(&ethhdr_tmp, skb_mac_header(skb), sizeof(ethhdr_tmp));
1663 
1664 	if (skb_cow(skb, 0) < 0)
1665 		return NULL;
1666 
1667 	if (unlikely(!skb_pull_rcsum(skb, h_diff)))
1668 		return NULL;
1669 
1670 	/* Data points to batman header, so set mac header 14 bytes before
1671 	 * and network to data
1672 	 */
1673 	skb_set_mac_header(skb, -ETH_HLEN);
1674 	skb_reset_network_header(skb);
1675 
1676 	/* Reconstruct original mac header */
1677 	ethhdr = eth_hdr(skb);
1678 	*ethhdr = ethhdr_tmp;
1679 
1680 	/* Select the correct unicast header information based on the location
1681 	 * of our mac address in the coded_packet header
1682 	 */
1683 	if (batadv_is_my_mac(bat_priv, coded_packet_tmp.second_dest)) {
1684 		/* If we are the second destination the packet was overheard,
1685 		 * so the Ethernet address must be copied to h_dest and
1686 		 * pkt_type changed from PACKET_OTHERHOST to PACKET_HOST
1687 		 */
1688 		ether_addr_copy(ethhdr->h_dest, coded_packet_tmp.second_dest);
1689 		skb->pkt_type = PACKET_HOST;
1690 
1691 		orig_dest = coded_packet_tmp.second_orig_dest;
1692 		ttl = coded_packet_tmp.second_ttl;
1693 		ttvn = coded_packet_tmp.second_ttvn;
1694 	} else {
1695 		orig_dest = coded_packet_tmp.first_orig_dest;
1696 		ttl = coded_packet_tmp.ttl;
1697 		ttvn = coded_packet_tmp.first_ttvn;
1698 	}
1699 
1700 	coding_len = ntohs(coded_packet_tmp.coded_len);
1701 
1702 	if (coding_len > skb->len)
1703 		return NULL;
1704 
1705 	/* Here the magic is reversed:
1706 	 *   extract the missing packet from the received coded packet
1707 	 */
1708 	batadv_nc_memxor(skb->data + h_size,
1709 			 nc_packet->skb->data + h_size,
1710 			 coding_len);
1711 
1712 	/* Resize decoded skb if decoded with larger packet */
1713 	if (nc_packet->skb->len > coding_len + h_size) {
1714 		err = pskb_trim_rcsum(skb, coding_len + h_size);
1715 		if (err)
1716 			return NULL;
1717 	}
1718 
1719 	/* Create decoded unicast packet */
1720 	unicast_packet = (struct batadv_unicast_packet *)skb->data;
1721 	unicast_packet->packet_type = BATADV_UNICAST;
1722 	unicast_packet->version = BATADV_COMPAT_VERSION;
1723 	unicast_packet->ttl = ttl;
1724 	ether_addr_copy(unicast_packet->dest, orig_dest);
1725 	unicast_packet->ttvn = ttvn;
1726 
1727 	batadv_nc_packet_free(nc_packet, false);
1728 	return unicast_packet;
1729 }
1730 
1731 /**
1732  * batadv_nc_find_decoding_packet() - search through buffered decoding data to
1733  *  find the data needed to decode the coded packet
1734  * @bat_priv: the bat priv with all the soft interface information
1735  * @ethhdr: pointer to the ethernet header inside the coded packet
1736  * @coded: coded packet we try to find decode data for
1737  *
1738  * Return: pointer to nc packet if the needed data was found or NULL otherwise.
1739  */
1740 static struct batadv_nc_packet *
1741 batadv_nc_find_decoding_packet(struct batadv_priv *bat_priv,
1742 			       struct ethhdr *ethhdr,
1743 			       struct batadv_coded_packet *coded)
1744 {
1745 	struct batadv_hashtable *hash = bat_priv->nc.decoding_hash;
1746 	struct batadv_nc_packet *tmp_nc_packet, *nc_packet = NULL;
1747 	struct batadv_nc_path *nc_path, nc_path_key;
1748 	u8 *dest, *source;
1749 	__be32 packet_id;
1750 	int index;
1751 
1752 	if (!hash)
1753 		return NULL;
1754 
1755 	/* Select the correct packet id based on the location of our mac-addr */
1756 	dest = ethhdr->h_source;
1757 	if (!batadv_is_my_mac(bat_priv, coded->second_dest)) {
1758 		source = coded->second_source;
1759 		packet_id = coded->second_crc;
1760 	} else {
1761 		source = coded->first_source;
1762 		packet_id = coded->first_crc;
1763 	}
1764 
1765 	batadv_nc_hash_key_gen(&nc_path_key, source, dest);
1766 	index = batadv_nc_hash_choose(&nc_path_key, hash->size);
1767 
1768 	/* Search for matching coding path */
1769 	rcu_read_lock();
1770 	hlist_for_each_entry_rcu(nc_path, &hash->table[index], hash_entry) {
1771 		/* Find matching nc_packet */
1772 		spin_lock_bh(&nc_path->packet_list_lock);
1773 		list_for_each_entry(tmp_nc_packet,
1774 				    &nc_path->packet_list, list) {
1775 			if (packet_id == tmp_nc_packet->packet_id) {
1776 				list_del(&tmp_nc_packet->list);
1777 
1778 				nc_packet = tmp_nc_packet;
1779 				break;
1780 			}
1781 		}
1782 		spin_unlock_bh(&nc_path->packet_list_lock);
1783 
1784 		if (nc_packet)
1785 			break;
1786 	}
1787 	rcu_read_unlock();
1788 
1789 	if (!nc_packet)
1790 		batadv_dbg(BATADV_DBG_NC, bat_priv,
1791 			   "No decoding packet found for %u\n", packet_id);
1792 
1793 	return nc_packet;
1794 }
1795 
1796 /**
1797  * batadv_nc_recv_coded_packet() - try to decode coded packet and enqueue the
1798  *  resulting unicast packet
1799  * @skb: incoming coded packet
1800  * @recv_if: pointer to interface this packet was received on
1801  *
1802  * Return: NET_RX_SUCCESS if the packet has been consumed or NET_RX_DROP
1803  * otherwise.
1804  */
1805 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
1806 				       struct batadv_hard_iface *recv_if)
1807 {
1808 	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
1809 	struct batadv_unicast_packet *unicast_packet;
1810 	struct batadv_coded_packet *coded_packet;
1811 	struct batadv_nc_packet *nc_packet;
1812 	struct ethhdr *ethhdr;
1813 	int hdr_size = sizeof(*coded_packet);
1814 
1815 	/* Check if network coding is enabled */
1816 	if (!atomic_read(&bat_priv->network_coding))
1817 		goto free_skb;
1818 
1819 	/* Make sure we can access (and remove) header */
1820 	if (unlikely(!pskb_may_pull(skb, hdr_size)))
1821 		goto free_skb;
1822 
1823 	coded_packet = (struct batadv_coded_packet *)skb->data;
1824 	ethhdr = eth_hdr(skb);
1825 
1826 	/* Verify frame is destined for us */
1827 	if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest) &&
1828 	    !batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1829 		goto free_skb;
1830 
1831 	/* Update stat counter */
1832 	if (batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1833 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_SNIFFED);
1834 
1835 	nc_packet = batadv_nc_find_decoding_packet(bat_priv, ethhdr,
1836 						   coded_packet);
1837 	if (!nc_packet) {
1838 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1839 		goto free_skb;
1840 	}
1841 
1842 	/* Make skb's linear, because decoding accesses the entire buffer */
1843 	if (skb_linearize(skb) < 0)
1844 		goto free_nc_packet;
1845 
1846 	if (skb_linearize(nc_packet->skb) < 0)
1847 		goto free_nc_packet;
1848 
1849 	/* Decode the packet */
1850 	unicast_packet = batadv_nc_skb_decode_packet(bat_priv, skb, nc_packet);
1851 	if (!unicast_packet) {
1852 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1853 		goto free_nc_packet;
1854 	}
1855 
1856 	/* Mark packet as decoded to do correct recoding when forwarding */
1857 	BATADV_SKB_CB(skb)->decoded = true;
1858 	batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE);
1859 	batadv_add_counter(bat_priv, BATADV_CNT_NC_DECODE_BYTES,
1860 			   skb->len + ETH_HLEN);
1861 	return batadv_recv_unicast_packet(skb, recv_if);
1862 
1863 free_nc_packet:
1864 	batadv_nc_packet_free(nc_packet, true);
1865 free_skb:
1866 	kfree_skb(skb);
1867 
1868 	return NET_RX_DROP;
1869 }
1870 
1871 /**
1872  * batadv_nc_mesh_free() - clean up network coding memory
1873  * @bat_priv: the bat priv with all the soft interface information
1874  */
1875 void batadv_nc_mesh_free(struct batadv_priv *bat_priv)
1876 {
1877 	batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
1878 	batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_NC, 1);
1879 	cancel_delayed_work_sync(&bat_priv->nc.work);
1880 
1881 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash, NULL);
1882 	batadv_hash_destroy(bat_priv->nc.coding_hash);
1883 	batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash, NULL);
1884 	batadv_hash_destroy(bat_priv->nc.decoding_hash);
1885 }
1886 
1887 #ifdef CONFIG_BATMAN_ADV_DEBUGFS
1888 /**
1889  * batadv_nc_nodes_seq_print_text() - print the nc node information
1890  * @seq: seq file to print on
1891  * @offset: not used
1892  *
1893  * Return: always 0
1894  */
1895 int batadv_nc_nodes_seq_print_text(struct seq_file *seq, void *offset)
1896 {
1897 	struct net_device *net_dev = (struct net_device *)seq->private;
1898 	struct batadv_priv *bat_priv = netdev_priv(net_dev);
1899 	struct batadv_hashtable *hash = bat_priv->orig_hash;
1900 	struct batadv_hard_iface *primary_if;
1901 	struct hlist_head *head;
1902 	struct batadv_orig_node *orig_node;
1903 	struct batadv_nc_node *nc_node;
1904 	int i;
1905 
1906 	primary_if = batadv_seq_print_text_primary_if_get(seq);
1907 	if (!primary_if)
1908 		goto out;
1909 
1910 	/* Traverse list of originators */
1911 	for (i = 0; i < hash->size; i++) {
1912 		head = &hash->table[i];
1913 
1914 		/* For each orig_node in this bin */
1915 		rcu_read_lock();
1916 		hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
1917 			/* no need to print the orig node if it does not have
1918 			 * network coding neighbors
1919 			 */
1920 			if (list_empty(&orig_node->in_coding_list) &&
1921 			    list_empty(&orig_node->out_coding_list))
1922 				continue;
1923 
1924 			seq_printf(seq, "Node:      %pM\n", orig_node->orig);
1925 
1926 			seq_puts(seq, " Ingoing:  ");
1927 			/* For each in_nc_node to this orig_node */
1928 			list_for_each_entry_rcu(nc_node,
1929 						&orig_node->in_coding_list,
1930 						list)
1931 				seq_printf(seq, "%pM ",
1932 					   nc_node->addr);
1933 			seq_puts(seq, "\n Outgoing: ");
1934 			/* For out_nc_node to this orig_node */
1935 			list_for_each_entry_rcu(nc_node,
1936 						&orig_node->out_coding_list,
1937 						list)
1938 				seq_printf(seq, "%pM ",
1939 					   nc_node->addr);
1940 			seq_puts(seq, "\n\n");
1941 		}
1942 		rcu_read_unlock();
1943 	}
1944 
1945 out:
1946 	if (primary_if)
1947 		batadv_hardif_put(primary_if);
1948 	return 0;
1949 }
1950 
1951 /**
1952  * batadv_nc_init_debugfs() - create nc folder and related files in debugfs
1953  * @bat_priv: the bat priv with all the soft interface information
1954  */
1955 void batadv_nc_init_debugfs(struct batadv_priv *bat_priv)
1956 {
1957 	struct dentry *nc_dir;
1958 
1959 	nc_dir = debugfs_create_dir("nc", bat_priv->debug_dir);
1960 
1961 	debugfs_create_u8("min_tq", 0644, nc_dir, &bat_priv->nc.min_tq);
1962 
1963 	debugfs_create_u32("max_fwd_delay", 0644, nc_dir,
1964 			   &bat_priv->nc.max_fwd_delay);
1965 
1966 	debugfs_create_u32("max_buffer_time", 0644, nc_dir,
1967 			   &bat_priv->nc.max_buffer_time);
1968 }
1969 #endif
1970