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TOMOYO Linux Cross Reference
Linux/net/batman-adv/network-coding.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /* Copyright (C) 2012-2019  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 

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