net/batman-adv/network-coding.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (C) 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/errno.h>
  15 #include <linux/etherdevice.h>
  16 #include <linux/gfp.h>
  17 #include <linux/if_ether.h>
  18 #include <linux/if_packet.h>
  19 #include <linux/init.h>
  20 #include <linux/jhash.h>
  21 #include <linux/jiffies.h>
  22 #include <linux/kernel.h>
  23 #include <linux/kref.h>
  24 #include <linux/list.h>
  25 #include <linux/lockdep.h>
  26 #include <linux/net.h>
  27 #include <linux/netdevice.h>
  28 #include <linux/prandom.h>
  29 #include <linux/printk.h>
  30 #include <linux/rculist.h>
  31 #include <linux/rcupdate.h>
  32 #include <linux/skbuff.h>
  33 #include <linux/slab.h>
  34 #include <linux/spinlock.h>
  35 #include <linux/stddef.h>
  36 #include <linux/string.h>
  37 #include <linux/workqueue.h>
  38 #include <uapi/linux/batadv_packet.h>
  39
  40 #include "hash.h"
  41 #include "log.h"
  42 #include "originator.h"
  43 #include "routing.h"
  44 #include "send.h"
  45 #include "tvlv.h"
  46
  47 static struct lock_class_key batadv_nc_coding_hash_lock_class_key;
  48 static struct lock_class_key batadv_nc_decoding_hash_lock_class_key;
  49
  50 static void batadv_nc_worker(struct work_struct *work);
  51 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
  52                                        struct batadv_hard_iface *recv_if);
  53
  54 /**
  55  * batadv_nc_init() - one-time initialization for network coding
  56  *
  57  * Return: 0 on success or negative error number in case of failure
  58  */
  59 int __init batadv_nc_init(void)
  60 {
  61         int ret;
  62
  63         /* Register our packet type */
  64         ret = batadv_recv_handler_register(BATADV_CODED,
  65                                            batadv_nc_recv_coded_packet);
  66
  67         return ret;
  68 }
  69
  70 /**
  71  * batadv_nc_start_timer() - initialise the nc periodic worker
  72  * @bat_priv: the bat priv with all the soft interface information
  73  */
  74 static void batadv_nc_start_timer(struct batadv_priv *bat_priv)
  75 {
  76         queue_delayed_work(batadv_event_workqueue, &bat_priv->nc.work,
  77                            msecs_to_jiffies(10));
  78 }
  79
  80 /**
  81  * batadv_nc_tvlv_container_update() - update the network coding tvlv container
  82  *  after network coding setting change
  83  * @bat_priv: the bat priv with all the soft interface information
  84  */
  85 static void batadv_nc_tvlv_container_update(struct batadv_priv *bat_priv)
  86 {
  87         char nc_mode;
  88
  89         nc_mode = atomic_read(&bat_priv->network_coding);
  90
  91         switch (nc_mode) {
  92         case 0:
  93                 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
  94                 break;
  95         case 1:
  96                 batadv_tvlv_container_register(bat_priv, BATADV_TVLV_NC, 1,
  97                                                NULL, 0);
  98                 break;
  99         }
 100 }
 101
 102 /**
 103  * batadv_nc_status_update() - update the network coding tvlv container after
 104  *  network coding setting change
 105  * @net_dev: the soft interface net device
 106  */
 107 void batadv_nc_status_update(struct net_device *net_dev)
 108 {
 109         struct batadv_priv *bat_priv = netdev_priv(net_dev);
 110
 111         batadv_nc_tvlv_container_update(bat_priv);
 112 }
 113
 114 /**
 115  * batadv_nc_tvlv_ogm_handler_v1() - process incoming nc tvlv container
 116  * @bat_priv: the bat priv with all the soft interface information
 117  * @orig: the orig_node of the ogm
 118  * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
 119  * @tvlv_value: tvlv buffer containing the gateway data
 120  * @tvlv_value_len: tvlv buffer length
 121  */
 122 static void batadv_nc_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
 123                                           struct batadv_orig_node *orig,
 124                                           u8 flags,
 125                                           void *tvlv_value, u16 tvlv_value_len)
 126 {
 127         if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
 128                 clear_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
 129         else
 130                 set_bit(BATADV_ORIG_CAPA_HAS_NC, &orig->capabilities);
 131 }
 132
 133 /**
 134  * batadv_nc_mesh_init() - initialise coding hash table and start housekeeping
 135  * @bat_priv: the bat priv with all the soft interface information
 136  *
 137  * Return: 0 on success or negative error number in case of failure
 138  */
 139 int batadv_nc_mesh_init(struct batadv_priv *bat_priv)
 140 {
 141         bat_priv->nc.timestamp_fwd_flush = jiffies;
 142         bat_priv->nc.timestamp_sniffed_purge = jiffies;
 143
 144         if (bat_priv->nc.coding_hash || bat_priv->nc.decoding_hash)
 145                 return 0;
 146
 147         bat_priv->nc.coding_hash = batadv_hash_new(128);
 148         if (!bat_priv->nc.coding_hash)
 149                 goto err;
 150
 151         batadv_hash_set_lock_class(bat_priv->nc.coding_hash,
 152                                    &batadv_nc_coding_hash_lock_class_key);
 153
 154         bat_priv->nc.decoding_hash = batadv_hash_new(128);
 155         if (!bat_priv->nc.decoding_hash)
 156                 goto err;
 157
 158         batadv_hash_set_lock_class(bat_priv->nc.decoding_hash,
 159                                    &batadv_nc_decoding_hash_lock_class_key);
 160
 161         INIT_DELAYED_WORK(&bat_priv->nc.work, batadv_nc_worker);
 162         batadv_nc_start_timer(bat_priv);
 163
 164         batadv_tvlv_handler_register(bat_priv, batadv_nc_tvlv_ogm_handler_v1,
 165                                      NULL, BATADV_TVLV_NC, 1,
 166                                      BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
 167         batadv_nc_tvlv_container_update(bat_priv);
 168         return 0;
 169
 170 err:
 171         return -ENOMEM;
 172 }
 173
 174 /**
 175  * batadv_nc_init_bat_priv() - initialise the nc specific bat_priv variables
 176  * @bat_priv: the bat priv with all the soft interface information
 177  */
 178 void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv)
 179 {
 180         atomic_set(&bat_priv->network_coding, 0);
 181         bat_priv->nc.min_tq = 200;
 182         bat_priv->nc.max_fwd_delay = 10;
 183         bat_priv->nc.max_buffer_time = 200;
 184 }
 185
 186 /**
 187  * batadv_nc_init_orig() - initialise the nc fields of an orig_node
 188  * @orig_node: the orig_node which is going to be initialised
 189  */
 190 void batadv_nc_init_orig(struct batadv_orig_node *orig_node)
 191 {
 192         INIT_LIST_HEAD(&orig_node->in_coding_list);
 193         INIT_LIST_HEAD(&orig_node->out_coding_list);
 194         spin_lock_init(&orig_node->in_coding_list_lock);
 195         spin_lock_init(&orig_node->out_coding_list_lock);
 196 }
 197
 198 /**
 199  * batadv_nc_node_release() - release nc_node from lists and queue for free
 200  *  after rcu grace period
 201  * @ref: kref pointer of the nc_node
 202  */
 203 static void batadv_nc_node_release(struct kref *ref)
 204 {
 205         struct batadv_nc_node *nc_node;
 206
 207         nc_node = container_of(ref, struct batadv_nc_node, refcount);
 208
 209         batadv_orig_node_put(nc_node->orig_node);
 210         kfree_rcu(nc_node, rcu);
 211 }
 212
 213 /**
 214  * batadv_nc_node_put() - decrement the nc_node refcounter and possibly
 215  *  release it
 216  * @nc_node: nc_node to be free'd
 217  */
 218 static void batadv_nc_node_put(struct batadv_nc_node *nc_node)
 219 {
 220         if (!nc_node)
 221                 return;
 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         if (!nc_path)
 248                 return;
 249
 250         kref_put(&nc_path->refcount, batadv_nc_path_release);
 251 }
 252
 253 /**
 254  * batadv_nc_packet_free() - frees nc packet
 255  * @nc_packet: the nc packet to free
 256  * @dropped: whether the packet is freed because is dropped
 257  */
 258 static void batadv_nc_packet_free(struct batadv_nc_packet *nc_packet,
 259                                   bool dropped)
 260 {
 261         if (dropped)
 262                 kfree_skb(nc_packet->skb);
 263         else
 264                 consume_skb(nc_packet->skb);
 265
 266         batadv_nc_path_put(nc_packet->nc_path);
 267         kfree(nc_packet);
 268 }
 269
 270 /**
 271  * batadv_nc_to_purge_nc_node() - checks whether an nc node has to be purged
 272  * @bat_priv: the bat priv with all the soft interface information
 273  * @nc_node: the nc node to check
 274  *
 275  * Return: true if the entry has to be purged now, false otherwise
 276  */
 277 static bool batadv_nc_to_purge_nc_node(struct batadv_priv *bat_priv,
 278                                        struct batadv_nc_node *nc_node)
 279 {
 280         if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
 281                 return true;
 282
 283         return batadv_has_timed_out(nc_node->last_seen, BATADV_NC_NODE_TIMEOUT);
 284 }
 285
 286 /**
 287  * batadv_nc_to_purge_nc_path_coding() - checks whether an nc path has timed out
 288  * @bat_priv: the bat priv with all the soft interface information
 289  * @nc_path: the nc path to check
 290  *
 291  * Return: true if the entry has to be purged now, false otherwise
 292  */
 293 static bool batadv_nc_to_purge_nc_path_coding(struct batadv_priv *bat_priv,
 294                                               struct batadv_nc_path *nc_path)
 295 {
 296         if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
 297                 return true;
 298
 299         /* purge the path when no packets has been added for 10 times the
 300          * max_fwd_delay time
 301          */
 302         return batadv_has_timed_out(nc_path->last_valid,
 303                                     bat_priv->nc.max_fwd_delay * 10);
 304 }
 305
 306 /**
 307  * batadv_nc_to_purge_nc_path_decoding() - checks whether an nc path has timed
 308  *  out
 309  * @bat_priv: the bat priv with all the soft interface information
 310  * @nc_path: the nc path to check
 311  *
 312  * Return: true if the entry has to be purged now, false otherwise
 313  */
 314 static bool batadv_nc_to_purge_nc_path_decoding(struct batadv_priv *bat_priv,
 315                                                 struct batadv_nc_path *nc_path)
 316 {
 317         if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
 318                 return true;
 319
 320         /* purge the path when no packets has been added for 10 times the
 321          * max_buffer time
 322          */
 323         return batadv_has_timed_out(nc_path->last_valid,
 324                                     bat_priv->nc.max_buffer_time * 10);
 325 }
 326
 327 /**
 328  * batadv_nc_purge_orig_nc_nodes() - go through list of nc nodes and purge stale
 329  *  entries
 330  * @bat_priv: the bat priv with all the soft interface information
 331  * @list: list of nc nodes
 332  * @lock: nc node list lock
 333  * @to_purge: function in charge to decide whether an entry has to be purged or
 334  *            not. This function takes the nc node as argument and has to return
 335  *            a boolean value: true if the entry has to be deleted, false
 336  *            otherwise
 337  */
 338 static void
 339 batadv_nc_purge_orig_nc_nodes(struct batadv_priv *bat_priv,
 340                               struct list_head *list,
 341                               spinlock_t *lock,
 342                               bool (*to_purge)(struct batadv_priv *,
 343                                                struct batadv_nc_node *))
 344 {
 345         struct batadv_nc_node *nc_node, *nc_node_tmp;
 346
 347         /* For each nc_node in list */
 348         spin_lock_bh(lock);
 349         list_for_each_entry_safe(nc_node, nc_node_tmp, list, list) {
 350                 /* if an helper function has been passed as parameter,
 351                  * ask it if the entry has to be purged or not
 352                  */
 353                 if (to_purge && !to_purge(bat_priv, nc_node))
 354                         continue;
 355
 356                 batadv_dbg(BATADV_DBG_NC, bat_priv,
 357                            "Removing nc_node %pM -> %pM\n",
 358                            nc_node->addr, nc_node->orig_node->orig);
 359                 list_del_rcu(&nc_node->list);
 360                 batadv_nc_node_put(nc_node);
 361         }
 362         spin_unlock_bh(lock);
 363 }
 364
 365 /**
 366  * batadv_nc_purge_orig() - purges all nc node data attached of the given
 367  *  originator
 368  * @bat_priv: the bat priv with all the soft interface information
 369  * @orig_node: orig_node with the nc node entries to be purged
 370  * @to_purge: function in charge to decide whether an entry has to be purged or
 371  *            not. This function takes the nc node as argument and has to return
 372  *            a boolean value: true is the entry has to be deleted, false
 373  *            otherwise
 374  */
 375 void batadv_nc_purge_orig(struct batadv_priv *bat_priv,
 376                           struct batadv_orig_node *orig_node,
 377                           bool (*to_purge)(struct batadv_priv *,
 378                                            struct batadv_nc_node *))
 379 {
 380         /* Check ingoing nc_node's of this orig_node */
 381         batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->in_coding_list,
 382                                       &orig_node->in_coding_list_lock,
 383                                       to_purge);
 384
 385         /* Check outgoing nc_node's of this orig_node */
 386         batadv_nc_purge_orig_nc_nodes(bat_priv, &orig_node->out_coding_list,
 387                                       &orig_node->out_coding_list_lock,
 388                                       to_purge);
 389 }
 390
 391 /**
 392  * batadv_nc_purge_orig_hash() - traverse entire originator hash to check if
 393  *  they have timed out nc nodes
 394  * @bat_priv: the bat priv with all the soft interface information
 395  */
 396 static void batadv_nc_purge_orig_hash(struct batadv_priv *bat_priv)
 397 {
 398         struct batadv_hashtable *hash = bat_priv->orig_hash;
 399         struct hlist_head *head;
 400         struct batadv_orig_node *orig_node;
 401         u32 i;
 402
 403         if (!hash)
 404                 return;
 405
 406         /* For each orig_node */
 407         for (i = 0; i < hash->size; i++) {
 408                 head = &hash->table[i];
 409
 410                 rcu_read_lock();
 411                 hlist_for_each_entry_rcu(orig_node, head, hash_entry)
 412                         batadv_nc_purge_orig(bat_priv, orig_node,
 413                                              batadv_nc_to_purge_nc_node);
 414                 rcu_read_unlock();
 415         }
 416 }
 417
 418 /**
 419  * batadv_nc_purge_paths() - traverse all nc paths part of the hash and remove
 420  *  unused ones
 421  * @bat_priv: the bat priv with all the soft interface information
 422  * @hash: hash table containing the nc paths to check
 423  * @to_purge: function in charge to decide whether an entry has to be purged or
 424  *            not. This function takes the nc node as argument and has to return
 425  *            a boolean value: true is the entry has to be deleted, false
 426  *            otherwise
 427  */
 428 static void batadv_nc_purge_paths(struct batadv_priv *bat_priv,
 429                                   struct batadv_hashtable *hash,
 430                                   bool (*to_purge)(struct batadv_priv *,
 431                                                    struct batadv_nc_path *))
 432 {
 433         struct hlist_head *head;
 434         struct hlist_node *node_tmp;
 435         struct batadv_nc_path *nc_path;
 436         spinlock_t *lock; /* Protects lists in hash */
 437         u32 i;
 438
 439         for (i = 0; i < hash->size; i++) {
 440                 head = &hash->table[i];
 441                 lock = &hash->list_locks[i];
 442
 443                 /* For each nc_path in this bin */
 444                 spin_lock_bh(lock);
 445                 hlist_for_each_entry_safe(nc_path, node_tmp, head, hash_entry) {
 446                         /* if an helper function has been passed as parameter,
 447                          * ask it if the entry has to be purged or not
 448                          */
 449                         if (to_purge && !to_purge(bat_priv, nc_path))
 450                                 continue;
 451
 452                         /* purging an non-empty nc_path should never happen, but
 453                          * is observed under high CPU load. Delay the purging
 454                          * until next iteration to allow the packet_list to be
 455                          * emptied first.
 456                          */
 457                         if (!unlikely(list_empty(&nc_path->packet_list))) {
 458                                 net_ratelimited_function(printk,
 459                                                          KERN_WARNING
 460                                                          "Skipping free of non-empty nc_path (%pM -> %pM)!\n",
 461                                                          nc_path->prev_hop,
 462                                                          nc_path->next_hop);
 463                                 continue;
 464                         }
 465
 466                         /* nc_path is unused, so remove it */
 467                         batadv_dbg(BATADV_DBG_NC, bat_priv,
 468                                    "Remove nc_path %pM -> %pM\n",
 469                                    nc_path->prev_hop, nc_path->next_hop);
 470                         hlist_del_rcu(&nc_path->hash_entry);
 471                         batadv_nc_path_put(nc_path);
 472                 }
 473                 spin_unlock_bh(lock);
 474         }
 475 }
 476
 477 /**
 478  * batadv_nc_hash_key_gen() - computes the nc_path hash key
 479  * @key: buffer to hold the final hash key
 480  * @src: source ethernet mac address going into the hash key
 481  * @dst: destination ethernet mac address going into the hash key
 482  */
 483 static void batadv_nc_hash_key_gen(struct batadv_nc_path *key, const char *src,
 484                                    const char *dst)
 485 {
 486         memcpy(key->prev_hop, src, sizeof(key->prev_hop));
 487         memcpy(key->next_hop, dst, sizeof(key->next_hop));
 488 }
 489
 490 /**
 491  * batadv_nc_hash_choose() - compute the hash value for an nc path
 492  * @data: data to hash
 493  * @size: size of the hash table
 494  *
 495  * Return: the selected index in the hash table for the given data.
 496  */
 497 static u32 batadv_nc_hash_choose(const void *data, u32 size)
 498 {
 499         const struct batadv_nc_path *nc_path = data;
 500         u32 hash = 0;
 501
 502         hash = jhash(&nc_path->prev_hop, sizeof(nc_path->prev_hop), hash);
 503         hash = jhash(&nc_path->next_hop, sizeof(nc_path->next_hop), hash);
 504
 505         return hash % size;
 506 }
 507
 508 /**
 509  * batadv_nc_hash_compare() - comparing function used in the network coding hash
 510  *  tables
 511  * @node: node in the local table
 512  * @data2: second object to compare the node to
 513  *
 514  * Return: true if the two entry are the same, false otherwise
 515  */
 516 static bool batadv_nc_hash_compare(const struct hlist_node *node,
 517                                    const void *data2)
 518 {
 519         const struct batadv_nc_path *nc_path1, *nc_path2;
 520
 521         nc_path1 = container_of(node, struct batadv_nc_path, hash_entry);
 522         nc_path2 = data2;
 523
 524         /* Return 1 if the two keys are identical */
 525         if (!batadv_compare_eth(nc_path1->prev_hop, nc_path2->prev_hop))
 526                 return false;
 527
 528         if (!batadv_compare_eth(nc_path1->next_hop, nc_path2->next_hop))
 529                 return false;
 530
 531         return true;
 532 }
 533
 534 /**
 535  * batadv_nc_hash_find() - search for an existing nc path and return it
 536  * @hash: hash table containing the nc path
 537  * @data: search key
 538  *
 539  * Return: the nc_path if found, NULL otherwise.
 540  */
 541 static struct batadv_nc_path *
 542 batadv_nc_hash_find(struct batadv_hashtable *hash,
 543                     void *data)
 544 {
 545         struct hlist_head *head;
 546         struct batadv_nc_path *nc_path, *nc_path_tmp = NULL;
 547         int index;
 548
 549         if (!hash)
 550                 return NULL;
 551
 552         index = batadv_nc_hash_choose(data, hash->size);
 553         head = &hash->table[index];
 554
 555         rcu_read_lock();
 556         hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
 557                 if (!batadv_nc_hash_compare(&nc_path->hash_entry, data))
 558                         continue;
 559
 560                 if (!kref_get_unless_zero(&nc_path->refcount))
 561                         continue;
 562
 563                 nc_path_tmp = nc_path;
 564                 break;
 565         }
 566         rcu_read_unlock();
 567
 568         return nc_path_tmp;
 569 }
 570
 571 /**
 572  * batadv_nc_send_packet() - send non-coded packet and free nc_packet struct
 573  * @nc_packet: the nc packet to send
 574  */
 575 static void batadv_nc_send_packet(struct batadv_nc_packet *nc_packet)
 576 {
 577         batadv_send_unicast_skb(nc_packet->skb, nc_packet->neigh_node);
 578         nc_packet->skb = NULL;
 579         batadv_nc_packet_free(nc_packet, false);
 580 }
 581
 582 /**
 583  * batadv_nc_sniffed_purge() - Checks timestamp of given sniffed nc_packet.
 584  * @bat_priv: the bat priv with all the soft interface information
 585  * @nc_path: the nc path the packet belongs to
 586  * @nc_packet: the nc packet to be checked
 587  *
 588  * Checks whether the given sniffed (overheard) nc_packet has hit its buffering
 589  * timeout. If so, the packet is no longer kept and the entry deleted from the
 590  * queue. Has to be called with the appropriate locks.
 591  *
 592  * Return: false as soon as the entry in the fifo queue has not been timed out
 593  * yet and true otherwise.
 594  */
 595 static bool batadv_nc_sniffed_purge(struct batadv_priv *bat_priv,
 596                                     struct batadv_nc_path *nc_path,
 597                                     struct batadv_nc_packet *nc_packet)
 598 {
 599         unsigned long timeout = bat_priv->nc.max_buffer_time;
 600         bool res = false;
 601
 602         lockdep_assert_held(&nc_path->packet_list_lock);
 603
 604         /* Packets are added to tail, so the remaining packets did not time
 605          * out and we can stop processing the current queue
 606          */
 607         if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
 608             !batadv_has_timed_out(nc_packet->timestamp, timeout))
 609                 goto out;
 610
 611         /* purge nc packet */
 612         list_del(&nc_packet->list);
 613         batadv_nc_packet_free(nc_packet, true);
 614
 615         res = true;
 616
 617 out:
 618         return res;
 619 }
 620
 621 /**
 622  * batadv_nc_fwd_flush() - Checks the timestamp of the given nc packet.
 623  * @bat_priv: the bat priv with all the soft interface information
 624  * @nc_path: the nc path the packet belongs to
 625  * @nc_packet: the nc packet to be checked
 626  *
 627  * Checks whether the given nc packet has hit its forward timeout. If so, the
 628  * packet is no longer delayed, immediately sent and the entry deleted from the
 629  * queue. Has to be called with the appropriate locks.
 630  *
 631  * Return: false as soon as the entry in the fifo queue has not been timed out
 632  * yet and true otherwise.
 633  */
 634 static bool batadv_nc_fwd_flush(struct batadv_priv *bat_priv,
 635                                 struct batadv_nc_path *nc_path,
 636                                 struct batadv_nc_packet *nc_packet)
 637 {
 638         unsigned long timeout = bat_priv->nc.max_fwd_delay;
 639
 640         lockdep_assert_held(&nc_path->packet_list_lock);
 641
 642         /* Packets are added to tail, so the remaining packets did not time
 643          * out and we can stop processing the current queue
 644          */
 645         if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_ACTIVE &&
 646             !batadv_has_timed_out(nc_packet->timestamp, timeout))
 647                 return false;
 648
 649         /* Send packet */
 650         batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
 651         batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
 652                            nc_packet->skb->len + ETH_HLEN);
 653         list_del(&nc_packet->list);
 654         batadv_nc_send_packet(nc_packet);
 655
 656         return true;
 657 }
 658
 659 /**
 660  * batadv_nc_process_nc_paths() - traverse given nc packet pool and free timed
 661  *  out nc packets
 662  * @bat_priv: the bat priv with all the soft interface information
 663  * @hash: to be processed hash table
 664  * @process_fn: Function called to process given nc packet. Should return true
 665  *              to encourage this function to proceed with the next packet.
 666  *              Otherwise the rest of the current queue is skipped.
 667  */
 668 static void
 669 batadv_nc_process_nc_paths(struct batadv_priv *bat_priv,
 670                            struct batadv_hashtable *hash,
 671                            bool (*process_fn)(struct batadv_priv *,
 672                                               struct batadv_nc_path *,
 673                                               struct batadv_nc_packet *))
 674 {
 675         struct hlist_head *head;
 676         struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
 677         struct batadv_nc_path *nc_path;
 678         bool ret;
 679         int i;
 680
 681         if (!hash)
 682                 return;
 683
 684         /* Loop hash table bins */
 685         for (i = 0; i < hash->size; i++) {
 686                 head = &hash->table[i];
 687
 688                 /* Loop coding paths */
 689                 rcu_read_lock();
 690                 hlist_for_each_entry_rcu(nc_path, head, hash_entry) {
 691                         /* Loop packets */
 692                         spin_lock_bh(&nc_path->packet_list_lock);
 693                         list_for_each_entry_safe(nc_packet, nc_packet_tmp,
 694                                                  &nc_path->packet_list, list) {
 695                                 ret = process_fn(bat_priv, nc_path, nc_packet);
 696                                 if (!ret)
 697                                         break;
 698                         }
 699                         spin_unlock_bh(&nc_path->packet_list_lock);
 700                 }
 701                 rcu_read_unlock();
 702         }
 703 }
 704
 705 /**
 706  * batadv_nc_worker() - periodic task for housekeeping related to network
 707  *  coding
 708  * @work: kernel work struct
 709  */
 710 static void batadv_nc_worker(struct work_struct *work)
 711 {
 712         struct delayed_work *delayed_work;
 713         struct batadv_priv_nc *priv_nc;
 714         struct batadv_priv *bat_priv;
 715         unsigned long timeout;
 716
 717         delayed_work = to_delayed_work(work);
 718         priv_nc = container_of(delayed_work, struct batadv_priv_nc, work);
 719         bat_priv = container_of(priv_nc, struct batadv_priv, nc);
 720
 721         batadv_nc_purge_orig_hash(bat_priv);
 722         batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash,
 723                               batadv_nc_to_purge_nc_path_coding);
 724         batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash,
 725                               batadv_nc_to_purge_nc_path_decoding);
 726
 727         timeout = bat_priv->nc.max_fwd_delay;
 728
 729         if (batadv_has_timed_out(bat_priv->nc.timestamp_fwd_flush, timeout)) {
 730                 batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.coding_hash,
 731                                            batadv_nc_fwd_flush);
 732                 bat_priv->nc.timestamp_fwd_flush = jiffies;
 733         }
 734
 735         if (batadv_has_timed_out(bat_priv->nc.timestamp_sniffed_purge,
 736                                  bat_priv->nc.max_buffer_time)) {
 737                 batadv_nc_process_nc_paths(bat_priv, bat_priv->nc.decoding_hash,
 738                                            batadv_nc_sniffed_purge);
 739                 bat_priv->nc.timestamp_sniffed_purge = jiffies;
 740         }
 741
 742         /* Schedule a new check */
 743         batadv_nc_start_timer(bat_priv);
 744 }
 745
 746 /**
 747  * batadv_can_nc_with_orig() - checks whether the given orig node is suitable
 748  *  for coding or not
 749  * @bat_priv: the bat priv with all the soft interface information
 750  * @orig_node: neighboring orig node which may be used as nc candidate
 751  * @ogm_packet: incoming ogm packet also used for the checks
 752  *
 753  * Return: true if:
 754  *  1) The OGM must have the most recent sequence number.
 755  *  2) The TTL must be decremented by one and only one.
 756  *  3) The OGM must be received from the first hop from orig_node.
 757  *  4) The TQ value of the OGM must be above bat_priv->nc.min_tq.
 758  */
 759 static bool batadv_can_nc_with_orig(struct batadv_priv *bat_priv,
 760                                     struct batadv_orig_node *orig_node,
 761                                     struct batadv_ogm_packet *ogm_packet)
 762 {
 763         struct batadv_orig_ifinfo *orig_ifinfo;
 764         u32 last_real_seqno;
 765         u8 last_ttl;
 766
 767         orig_ifinfo = batadv_orig_ifinfo_get(orig_node, BATADV_IF_DEFAULT);
 768         if (!orig_ifinfo)
 769                 return false;
 770
 771         last_ttl = orig_ifinfo->last_ttl;
 772         last_real_seqno = orig_ifinfo->last_real_seqno;
 773         batadv_orig_ifinfo_put(orig_ifinfo);
 774
 775         if (last_real_seqno != ntohl(ogm_packet->seqno))
 776                 return false;
 777         if (last_ttl != ogm_packet->ttl + 1)
 778                 return false;
 779         if (!batadv_compare_eth(ogm_packet->orig, ogm_packet->prev_sender))
 780                 return false;
 781         if (ogm_packet->tq < bat_priv->nc.min_tq)
 782                 return false;
 783
 784         return true;
 785 }
 786
 787 /**
 788  * batadv_nc_find_nc_node() - search for an existing nc node and return it
 789  * @orig_node: orig node originating the ogm packet
 790  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
 791  *  (can be equal to orig_node)
 792  * @in_coding: traverse incoming or outgoing network coding list
 793  *
 794  * Return: the nc_node if found, NULL otherwise.
 795  */
 796 static struct batadv_nc_node *
 797 batadv_nc_find_nc_node(struct batadv_orig_node *orig_node,
 798                        struct batadv_orig_node *orig_neigh_node,
 799                        bool in_coding)
 800 {
 801         struct batadv_nc_node *nc_node, *nc_node_out = NULL;
 802         struct list_head *list;
 803
 804         if (in_coding)
 805                 list = &orig_neigh_node->in_coding_list;
 806         else
 807                 list = &orig_neigh_node->out_coding_list;
 808
 809         /* Traverse list of nc_nodes to orig_node */
 810         rcu_read_lock();
 811         list_for_each_entry_rcu(nc_node, list, list) {
 812                 if (!batadv_compare_eth(nc_node->addr, orig_node->orig))
 813                         continue;
 814
 815                 if (!kref_get_unless_zero(&nc_node->refcount))
 816                         continue;
 817
 818                 /* Found a match */
 819                 nc_node_out = nc_node;
 820                 break;
 821         }
 822         rcu_read_unlock();
 823
 824         return nc_node_out;
 825 }
 826
 827 /**
 828  * batadv_nc_get_nc_node() - retrieves an nc node or creates the entry if it was
 829  *  not found
 830  * @bat_priv: the bat priv with all the soft interface information
 831  * @orig_node: orig node originating the ogm packet
 832  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
 833  *  (can be equal to orig_node)
 834  * @in_coding: traverse incoming or outgoing network coding list
 835  *
 836  * Return: the nc_node if found or created, NULL in case of an error.
 837  */
 838 static struct batadv_nc_node *
 839 batadv_nc_get_nc_node(struct batadv_priv *bat_priv,
 840                       struct batadv_orig_node *orig_node,
 841                       struct batadv_orig_node *orig_neigh_node,
 842                       bool in_coding)
 843 {
 844         struct batadv_nc_node *nc_node;
 845         spinlock_t *lock; /* Used to lock list selected by "int in_coding" */
 846         struct list_head *list;
 847
 848         /* Select ingoing or outgoing coding node */
 849         if (in_coding) {
 850                 lock = &orig_neigh_node->in_coding_list_lock;
 851                 list = &orig_neigh_node->in_coding_list;
 852         } else {
 853                 lock = &orig_neigh_node->out_coding_list_lock;
 854                 list = &orig_neigh_node->out_coding_list;
 855         }
 856
 857         spin_lock_bh(lock);
 858
 859         /* Check if nc_node is already added */
 860         nc_node = batadv_nc_find_nc_node(orig_node, orig_neigh_node, in_coding);
 861
 862         /* Node found */
 863         if (nc_node)
 864                 goto unlock;
 865
 866         nc_node = kzalloc(sizeof(*nc_node), GFP_ATOMIC);
 867         if (!nc_node)
 868                 goto unlock;
 869
 870         /* Initialize nc_node */
 871         INIT_LIST_HEAD(&nc_node->list);
 872         kref_init(&nc_node->refcount);
 873         ether_addr_copy(nc_node->addr, orig_node->orig);
 874         kref_get(&orig_neigh_node->refcount);
 875         nc_node->orig_node = orig_neigh_node;
 876
 877         batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_node %pM -> %pM\n",
 878                    nc_node->addr, nc_node->orig_node->orig);
 879
 880         /* Add nc_node to orig_node */
 881         kref_get(&nc_node->refcount);
 882         list_add_tail_rcu(&nc_node->list, list);
 883
 884 unlock:
 885         spin_unlock_bh(lock);
 886
 887         return nc_node;
 888 }
 889
 890 /**
 891  * batadv_nc_update_nc_node() - updates stored incoming and outgoing nc node
 892  *  structs (best called on incoming OGMs)
 893  * @bat_priv: the bat priv with all the soft interface information
 894  * @orig_node: orig node originating the ogm packet
 895  * @orig_neigh_node: neighboring orig node from which we received the ogm packet
 896  *  (can be equal to orig_node)
 897  * @ogm_packet: incoming ogm packet
 898  * @is_single_hop_neigh: orig_node is a single hop neighbor
 899  */
 900 void batadv_nc_update_nc_node(struct batadv_priv *bat_priv,
 901                               struct batadv_orig_node *orig_node,
 902                               struct batadv_orig_node *orig_neigh_node,
 903                               struct batadv_ogm_packet *ogm_packet,
 904                               int is_single_hop_neigh)
 905 {
 906         struct batadv_nc_node *in_nc_node = NULL;
 907         struct batadv_nc_node *out_nc_node = NULL;
 908
 909         /* Check if network coding is enabled */
 910         if (!atomic_read(&bat_priv->network_coding))
 911                 goto out;
 912
 913         /* check if orig node is network coding enabled */
 914         if (!test_bit(BATADV_ORIG_CAPA_HAS_NC, &orig_node->capabilities))
 915                 goto out;
 916
 917         /* accept ogms from 'good' neighbors and single hop neighbors */
 918         if (!batadv_can_nc_with_orig(bat_priv, orig_node, ogm_packet) &&
 919             !is_single_hop_neigh)
 920                 goto out;
 921
 922         /* Add orig_node as in_nc_node on hop */
 923         in_nc_node = batadv_nc_get_nc_node(bat_priv, orig_node,
 924                                            orig_neigh_node, true);
 925         if (!in_nc_node)
 926                 goto out;
 927
 928         in_nc_node->last_seen = jiffies;
 929
 930         /* Add hop as out_nc_node on orig_node */
 931         out_nc_node = batadv_nc_get_nc_node(bat_priv, orig_neigh_node,
 932                                             orig_node, false);
 933         if (!out_nc_node)
 934                 goto out;
 935
 936         out_nc_node->last_seen = jiffies;
 937
 938 out:
 939         batadv_nc_node_put(in_nc_node);
 940         batadv_nc_node_put(out_nc_node);
 941 }
 942
 943 /**
 944  * batadv_nc_get_path() - get existing nc_path or allocate a new one
 945  * @bat_priv: the bat priv with all the soft interface information
 946  * @hash: hash table containing the nc path
 947  * @src: ethernet source address - first half of the nc path search key
 948  * @dst: ethernet destination address - second half of the nc path search key
 949  *
 950  * Return: pointer to nc_path if the path was found or created, returns NULL
 951  * on error.
 952  */
 953 static struct batadv_nc_path *batadv_nc_get_path(struct batadv_priv *bat_priv,
 954                                                  struct batadv_hashtable *hash,
 955                                                  u8 *src,
 956                                                  u8 *dst)
 957 {
 958         int hash_added;
 959         struct batadv_nc_path *nc_path, nc_path_key;
 960
 961         batadv_nc_hash_key_gen(&nc_path_key, src, dst);
 962
 963         /* Search for existing nc_path */
 964         nc_path = batadv_nc_hash_find(hash, (void *)&nc_path_key);
 965
 966         if (nc_path) {
 967                 /* Set timestamp to delay removal of nc_path */
 968                 nc_path->last_valid = jiffies;
 969                 return nc_path;
 970         }
 971
 972         /* No existing nc_path was found; create a new */
 973         nc_path = kzalloc(sizeof(*nc_path), GFP_ATOMIC);
 974
 975         if (!nc_path)
 976                 return NULL;
 977
 978         /* Initialize nc_path */
 979         INIT_LIST_HEAD(&nc_path->packet_list);
 980         spin_lock_init(&nc_path->packet_list_lock);
 981         kref_init(&nc_path->refcount);
 982         nc_path->last_valid = jiffies;
 983         ether_addr_copy(nc_path->next_hop, dst);
 984         ether_addr_copy(nc_path->prev_hop, src);
 985
 986         batadv_dbg(BATADV_DBG_NC, bat_priv, "Adding nc_path %pM -> %pM\n",
 987                    nc_path->prev_hop,
 988                    nc_path->next_hop);
 989
 990         /* Add nc_path to hash table */
 991         kref_get(&nc_path->refcount);
 992         hash_added = batadv_hash_add(hash, batadv_nc_hash_compare,
 993                                      batadv_nc_hash_choose, &nc_path_key,
 994                                      &nc_path->hash_entry);
 995
 996         if (hash_added < 0) {
 997                 kfree(nc_path);
 998                 return NULL;
 999         }
1000
1001         return nc_path;
1002 }
1003
1004 /**
1005  * batadv_nc_random_weight_tq() - scale the receivers TQ-value to avoid unfair
1006  *  selection of a receiver with slightly lower TQ than the other
1007  * @tq: to be weighted tq value
1008  *
1009  * Return: scaled tq value
1010  */
1011 static u8 batadv_nc_random_weight_tq(u8 tq)
1012 {
1013         /* randomize the estimated packet loss (max TQ - estimated TQ) */
1014         u8 rand_tq = prandom_u32_max(BATADV_TQ_MAX_VALUE + 1 - tq);
1015
1016         /* convert to (randomized) estimated tq again */
1017         return BATADV_TQ_MAX_VALUE - rand_tq;
1018 }
1019
1020 /**
1021  * batadv_nc_memxor() - XOR destination with source
1022  * @dst: byte array to XOR into
1023  * @src: byte array to XOR from
1024  * @len: length of destination array
1025  */
1026 static void batadv_nc_memxor(char *dst, const char *src, unsigned int len)
1027 {
1028         unsigned int i;
1029
1030         for (i = 0; i < len; ++i)
1031                 dst[i] ^= src[i];
1032 }
1033
1034 /**
1035  * batadv_nc_code_packets() - code a received unicast_packet with an nc packet
1036  *  into a coded_packet and send it
1037  * @bat_priv: the bat priv with all the soft interface information
1038  * @skb: data skb to forward
1039  * @ethhdr: pointer to the ethernet header inside the skb
1040  * @nc_packet: structure containing the packet to the skb can be coded with
1041  * @neigh_node: next hop to forward packet to
1042  *
1043  * Return: true if both packets are consumed, false otherwise.
1044  */
1045 static bool batadv_nc_code_packets(struct batadv_priv *bat_priv,
1046                                    struct sk_buff *skb,
1047                                    struct ethhdr *ethhdr,
1048                                    struct batadv_nc_packet *nc_packet,
1049                                    struct batadv_neigh_node *neigh_node)
1050 {
1051         u8 tq_weighted_neigh, tq_weighted_coding, tq_tmp;
1052         struct sk_buff *skb_dest, *skb_src;
1053         struct batadv_unicast_packet *packet1;
1054         struct batadv_unicast_packet *packet2;
1055         struct batadv_coded_packet *coded_packet;
1056         struct batadv_neigh_node *neigh_tmp, *router_neigh, *first_dest;
1057         struct batadv_neigh_node *router_coding = NULL, *second_dest;
1058         struct batadv_neigh_ifinfo *router_neigh_ifinfo = NULL;
1059         struct batadv_neigh_ifinfo *router_coding_ifinfo = NULL;
1060         u8 *first_source, *second_source;
1061         __be32 packet_id1, packet_id2;
1062         size_t count;
1063         bool res = false;
1064         int coding_len;
1065         int unicast_size = sizeof(*packet1);
1066         int coded_size = sizeof(*coded_packet);
1067         int header_add = coded_size - unicast_size;
1068
1069         /* TODO: do we need to consider the outgoing interface for
1070          * coded packets?
1071          */
1072         router_neigh = batadv_orig_router_get(neigh_node->orig_node,
1073                                               BATADV_IF_DEFAULT);
1074         if (!router_neigh)
1075                 goto out;
1076
1077         router_neigh_ifinfo = batadv_neigh_ifinfo_get(router_neigh,
1078                                                       BATADV_IF_DEFAULT);
1079         if (!router_neigh_ifinfo)
1080                 goto out;
1081
1082         neigh_tmp = nc_packet->neigh_node;
1083         router_coding = batadv_orig_router_get(neigh_tmp->orig_node,
1084                                                BATADV_IF_DEFAULT);
1085         if (!router_coding)
1086                 goto out;
1087
1088         router_coding_ifinfo = batadv_neigh_ifinfo_get(router_coding,
1089                                                        BATADV_IF_DEFAULT);
1090         if (!router_coding_ifinfo)
1091                 goto out;
1092
1093         tq_tmp = router_neigh_ifinfo->bat_iv.tq_avg;
1094         tq_weighted_neigh = batadv_nc_random_weight_tq(tq_tmp);
1095         tq_tmp = router_coding_ifinfo->bat_iv.tq_avg;
1096         tq_weighted_coding = batadv_nc_random_weight_tq(tq_tmp);
1097
1098         /* Select one destination for the MAC-header dst-field based on
1099          * weighted TQ-values.
1100          */
1101         if (tq_weighted_neigh >= tq_weighted_coding) {
1102                 /* Destination from nc_packet is selected for MAC-header */
1103                 first_dest = nc_packet->neigh_node;
1104                 first_source = nc_packet->nc_path->prev_hop;
1105                 second_dest = neigh_node;
1106                 second_source = ethhdr->h_source;
1107                 packet1 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1108                 packet2 = (struct batadv_unicast_packet *)skb->data;
1109                 packet_id1 = nc_packet->packet_id;
1110                 packet_id2 = batadv_skb_crc32(skb,
1111                                               skb->data + sizeof(*packet2));
1112         } else {
1113                 /* Destination for skb is selected for MAC-header */
1114                 first_dest = neigh_node;
1115                 first_source = ethhdr->h_source;
1116                 second_dest = nc_packet->neigh_node;
1117                 second_source = nc_packet->nc_path->prev_hop;
1118                 packet1 = (struct batadv_unicast_packet *)skb->data;
1119                 packet2 = (struct batadv_unicast_packet *)nc_packet->skb->data;
1120                 packet_id1 = batadv_skb_crc32(skb,
1121                                               skb->data + sizeof(*packet1));
1122                 packet_id2 = nc_packet->packet_id;
1123         }
1124
1125         /* Instead of zero padding the smallest data buffer, we
1126          * code into the largest.
1127          */
1128         if (skb->len <= nc_packet->skb->len) {
1129                 skb_dest = nc_packet->skb;
1130                 skb_src = skb;
1131         } else {
1132                 skb_dest = skb;
1133                 skb_src = nc_packet->skb;
1134         }
1135
1136         /* coding_len is used when decoding the packet shorter packet */
1137         coding_len = skb_src->len - unicast_size;
1138
1139         if (skb_linearize(skb_dest) < 0 || skb_linearize(skb_src) < 0)
1140                 goto out;
1141
1142         skb_push(skb_dest, header_add);
1143
1144         coded_packet = (struct batadv_coded_packet *)skb_dest->data;
1145         skb_reset_mac_header(skb_dest);
1146
1147         coded_packet->packet_type = BATADV_CODED;
1148         coded_packet->version = BATADV_COMPAT_VERSION;
1149         coded_packet->ttl = packet1->ttl;
1150
1151         /* Info about first unicast packet */
1152         ether_addr_copy(coded_packet->first_source, first_source);
1153         ether_addr_copy(coded_packet->first_orig_dest, packet1->dest);
1154         coded_packet->first_crc = packet_id1;
1155         coded_packet->first_ttvn = packet1->ttvn;
1156
1157         /* Info about second unicast packet */
1158         ether_addr_copy(coded_packet->second_dest, second_dest->addr);
1159         ether_addr_copy(coded_packet->second_source, second_source);
1160         ether_addr_copy(coded_packet->second_orig_dest, packet2->dest);
1161         coded_packet->second_crc = packet_id2;
1162         coded_packet->second_ttl = packet2->ttl;
1163         coded_packet->second_ttvn = packet2->ttvn;
1164         coded_packet->coded_len = htons(coding_len);
1165
1166         /* This is where the magic happens: Code skb_src into skb_dest */
1167         batadv_nc_memxor(skb_dest->data + coded_size,
1168                          skb_src->data + unicast_size, coding_len);
1169
1170         /* Update counters accordingly */
1171         if (BATADV_SKB_CB(skb_src)->decoded &&
1172             BATADV_SKB_CB(skb_dest)->decoded) {
1173                 /* Both packets are recoded */
1174                 count = skb_src->len + ETH_HLEN;
1175                 count += skb_dest->len + ETH_HLEN;
1176                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE, 2);
1177                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES, count);
1178         } else if (!BATADV_SKB_CB(skb_src)->decoded &&
1179                    !BATADV_SKB_CB(skb_dest)->decoded) {
1180                 /* Both packets are newly coded */
1181                 count = skb_src->len + ETH_HLEN;
1182                 count += skb_dest->len + ETH_HLEN;
1183                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE, 2);
1184                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES, count);
1185         } else if (BATADV_SKB_CB(skb_src)->decoded &&
1186                    !BATADV_SKB_CB(skb_dest)->decoded) {
1187                 /* skb_src recoded and skb_dest is newly coded */
1188                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1189                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1190                                    skb_src->len + ETH_HLEN);
1191                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1192                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1193                                    skb_dest->len + ETH_HLEN);
1194         } else if (!BATADV_SKB_CB(skb_src)->decoded &&
1195                    BATADV_SKB_CB(skb_dest)->decoded) {
1196                 /* skb_src is newly coded and skb_dest is recoded */
1197                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_CODE);
1198                 batadv_add_counter(bat_priv, BATADV_CNT_NC_CODE_BYTES,
1199                                    skb_src->len + ETH_HLEN);
1200                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_RECODE);
1201                 batadv_add_counter(bat_priv, BATADV_CNT_NC_RECODE_BYTES,
1202                                    skb_dest->len + ETH_HLEN);
1203         }
1204
1205         /* skb_src is now coded into skb_dest, so free it */
1206         consume_skb(skb_src);
1207
1208         /* avoid duplicate free of skb from nc_packet */
1209         nc_packet->skb = NULL;
1210         batadv_nc_packet_free(nc_packet, false);
1211
1212         /* Send the coded packet and return true */
1213         batadv_send_unicast_skb(skb_dest, first_dest);
1214         res = true;
1215 out:
1216         batadv_neigh_node_put(router_neigh);
1217         batadv_neigh_node_put(router_coding);
1218         batadv_neigh_ifinfo_put(router_neigh_ifinfo);
1219         batadv_neigh_ifinfo_put(router_coding_ifinfo);
1220         return res;
1221 }
1222
1223 /**
1224  * batadv_nc_skb_coding_possible() - true if a decoded skb is available at dst.
1225  * @skb: data skb to forward
1226  * @dst: destination mac address of the other skb to code with
1227  * @src: source mac address of skb
1228  *
1229  * Whenever we network code a packet we have to check whether we received it in
1230  * a network coded form. If so, we may not be able to use it for coding because
1231  * some neighbors may also have received (overheard) the packet in the network
1232  * coded form without being able to decode it. It is hard to know which of the
1233  * neighboring nodes was able to decode the packet, therefore we can only
1234  * re-code the packet if the source of the previous encoded packet is involved.
1235  * Since the source encoded the packet we can be certain it has all necessary
1236  * decode information.
1237  *
1238  * Return: true if coding of a decoded packet is allowed.
1239  */
1240 static bool batadv_nc_skb_coding_possible(struct sk_buff *skb, u8 *dst, u8 *src)
1241 {
1242         if (BATADV_SKB_CB(skb)->decoded && !batadv_compare_eth(dst, src))
1243                 return false;
1244         return true;
1245 }
1246
1247 /**
1248  * batadv_nc_path_search() - Find the coding path matching in_nc_node and
1249  *  out_nc_node to retrieve a buffered packet that can be used for coding.
1250  * @bat_priv: the bat priv with all the soft interface information
1251  * @in_nc_node: pointer to skb next hop's neighbor nc node
1252  * @out_nc_node: pointer to skb source's neighbor nc node
1253  * @skb: data skb to forward
1254  * @eth_dst: next hop mac address of skb
1255  *
1256  * Return: true if coding of a decoded skb is allowed.
1257  */
1258 static struct batadv_nc_packet *
1259 batadv_nc_path_search(struct batadv_priv *bat_priv,
1260                       struct batadv_nc_node *in_nc_node,
1261                       struct batadv_nc_node *out_nc_node,
1262                       struct sk_buff *skb,
1263                       u8 *eth_dst)
1264 {
1265         struct batadv_nc_path *nc_path, nc_path_key;
1266         struct batadv_nc_packet *nc_packet_out = NULL;
1267         struct batadv_nc_packet *nc_packet, *nc_packet_tmp;
1268         struct batadv_hashtable *hash = bat_priv->nc.coding_hash;
1269         int idx;
1270
1271         if (!hash)
1272                 return NULL;
1273
1274         /* Create almost path key */
1275         batadv_nc_hash_key_gen(&nc_path_key, in_nc_node->addr,
1276                                out_nc_node->addr);
1277         idx = batadv_nc_hash_choose(&nc_path_key, hash->size);
1278
1279         /* Check for coding opportunities in this nc_path */
1280         rcu_read_lock();
1281         hlist_for_each_entry_rcu(nc_path, &hash->table[idx], hash_entry) {
1282                 if (!batadv_compare_eth(nc_path->prev_hop, in_nc_node->addr))
1283                         continue;
1284
1285                 if (!batadv_compare_eth(nc_path->next_hop, out_nc_node->addr))
1286                         continue;
1287
1288                 spin_lock_bh(&nc_path->packet_list_lock);
1289                 if (list_empty(&nc_path->packet_list)) {
1290                         spin_unlock_bh(&nc_path->packet_list_lock);
1291                         continue;
1292                 }
1293
1294                 list_for_each_entry_safe(nc_packet, nc_packet_tmp,
1295                                          &nc_path->packet_list, list) {
1296                         if (!batadv_nc_skb_coding_possible(nc_packet->skb,
1297                                                            eth_dst,
1298                                                            in_nc_node->addr))
1299                                 continue;
1300
1301                         /* Coding opportunity is found! */
1302                         list_del(&nc_packet->list);
1303                         nc_packet_out = nc_packet;
1304                         break;
1305                 }
1306
1307                 spin_unlock_bh(&nc_path->packet_list_lock);
1308                 break;
1309         }
1310         rcu_read_unlock();
1311
1312         return nc_packet_out;
1313 }
1314
1315 /**
1316  * batadv_nc_skb_src_search() - Loops through the list of neighboring nodes of
1317  *  the skb's sender (may be equal to the originator).
1318  * @bat_priv: the bat priv with all the soft interface information
1319  * @skb: data skb to forward
1320  * @eth_dst: next hop mac address of skb
1321  * @eth_src: source mac address of skb
1322  * @in_nc_node: pointer to skb next hop's neighbor nc node
1323  *
1324  * Return: an nc packet if a suitable coding packet was found, NULL otherwise.
1325  */
1326 static struct batadv_nc_packet *
1327 batadv_nc_skb_src_search(struct batadv_priv *bat_priv,
1328                          struct sk_buff *skb,
1329                          u8 *eth_dst,
1330                          u8 *eth_src,
1331                          struct batadv_nc_node *in_nc_node)
1332 {
1333         struct batadv_orig_node *orig_node;
1334         struct batadv_nc_node *out_nc_node;
1335         struct batadv_nc_packet *nc_packet = NULL;
1336
1337         orig_node = batadv_orig_hash_find(bat_priv, eth_src);
1338         if (!orig_node)
1339                 return NULL;
1340
1341         rcu_read_lock();
1342         list_for_each_entry_rcu(out_nc_node,
1343                                 &orig_node->out_coding_list, list) {
1344                 /* Check if the skb is decoded and if recoding is possible */
1345                 if (!batadv_nc_skb_coding_possible(skb,
1346                                                    out_nc_node->addr, eth_src))
1347                         continue;
1348
1349                 /* Search for an opportunity in this nc_path */
1350                 nc_packet = batadv_nc_path_search(bat_priv, in_nc_node,
1351                                                   out_nc_node, skb, eth_dst);
1352                 if (nc_packet)
1353                         break;
1354         }
1355         rcu_read_unlock();
1356
1357         batadv_orig_node_put(orig_node);
1358         return nc_packet;
1359 }
1360
1361 /**
1362  * batadv_nc_skb_store_before_coding() - set the ethernet src and dst of the
1363  *  unicast skb before it is stored for use in later decoding
1364  * @bat_priv: the bat priv with all the soft interface information
1365  * @skb: data skb to store
1366  * @eth_dst_new: new destination mac address of skb
1367  */
1368 static void batadv_nc_skb_store_before_coding(struct batadv_priv *bat_priv,
1369                                               struct sk_buff *skb,
1370                                               u8 *eth_dst_new)
1371 {
1372         struct ethhdr *ethhdr;
1373
1374         /* Copy skb header to change the mac header */
1375         skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
1376         if (!skb)
1377                 return;
1378
1379         /* Set the mac header as if we actually sent the packet uncoded */
1380         ethhdr = eth_hdr(skb);
1381         ether_addr_copy(ethhdr->h_source, ethhdr->h_dest);
1382         ether_addr_copy(ethhdr->h_dest, eth_dst_new);
1383
1384         /* Set data pointer to MAC header to mimic packets from our tx path */
1385         skb_push(skb, ETH_HLEN);
1386
1387         /* Add the packet to the decoding packet pool */
1388         batadv_nc_skb_store_for_decoding(bat_priv, skb);
1389
1390         /* batadv_nc_skb_store_for_decoding() clones the skb, so we must free
1391          * our ref
1392          */
1393         consume_skb(skb);
1394 }
1395
1396 /**
1397  * batadv_nc_skb_dst_search() - Loops through list of neighboring nodes to dst.
1398  * @skb: data skb to forward
1399  * @neigh_node: next hop to forward packet to
1400  * @ethhdr: pointer to the ethernet header inside the skb
1401  *
1402  * Loops through the list of neighboring nodes the next hop has a good
1403  * connection to (receives OGMs with a sufficient quality). We need to find a
1404  * neighbor of our next hop that potentially sent a packet which our next hop
1405  * also received (overheard) and has stored for later decoding.
1406  *
1407  * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1408  */
1409 static bool batadv_nc_skb_dst_search(struct sk_buff *skb,
1410                                      struct batadv_neigh_node *neigh_node,
1411                                      struct ethhdr *ethhdr)
1412 {
1413         struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1414         struct batadv_priv *bat_priv = netdev_priv(netdev);
1415         struct batadv_orig_node *orig_node = neigh_node->orig_node;
1416         struct batadv_nc_node *nc_node;
1417         struct batadv_nc_packet *nc_packet = NULL;
1418
1419         rcu_read_lock();
1420         list_for_each_entry_rcu(nc_node, &orig_node->in_coding_list, list) {
1421                 /* Search for coding opportunity with this in_nc_node */
1422                 nc_packet = batadv_nc_skb_src_search(bat_priv, skb,
1423                                                      neigh_node->addr,
1424                                                      ethhdr->h_source, nc_node);
1425
1426                 /* Opportunity was found, so stop searching */
1427                 if (nc_packet)
1428                         break;
1429         }
1430         rcu_read_unlock();
1431
1432         if (!nc_packet)
1433                 return false;
1434
1435         /* Save packets for later decoding */
1436         batadv_nc_skb_store_before_coding(bat_priv, skb,
1437                                           neigh_node->addr);
1438         batadv_nc_skb_store_before_coding(bat_priv, nc_packet->skb,
1439                                           nc_packet->neigh_node->addr);
1440
1441         /* Code and send packets */
1442         if (batadv_nc_code_packets(bat_priv, skb, ethhdr, nc_packet,
1443                                    neigh_node))
1444                 return true;
1445
1446         /* out of mem ? Coding failed - we have to free the buffered packet
1447          * to avoid memleaks. The skb passed as argument will be dealt with
1448          * by the calling function.
1449          */
1450         batadv_nc_send_packet(nc_packet);
1451         return false;
1452 }
1453
1454 /**
1455  * batadv_nc_skb_add_to_path() - buffer skb for later encoding / decoding
1456  * @skb: skb to add to path
1457  * @nc_path: path to add skb to
1458  * @neigh_node: next hop to forward packet to
1459  * @packet_id: checksum to identify packet
1460  *
1461  * Return: true if the packet was buffered or false in case of an error.
1462  */
1463 static bool batadv_nc_skb_add_to_path(struct sk_buff *skb,
1464                                       struct batadv_nc_path *nc_path,
1465                                       struct batadv_neigh_node *neigh_node,
1466                                       __be32 packet_id)
1467 {
1468         struct batadv_nc_packet *nc_packet;
1469
1470         nc_packet = kzalloc(sizeof(*nc_packet), GFP_ATOMIC);
1471         if (!nc_packet)
1472                 return false;
1473
1474         /* Initialize nc_packet */
1475         nc_packet->timestamp = jiffies;
1476         nc_packet->packet_id = packet_id;
1477         nc_packet->skb = skb;
1478         nc_packet->neigh_node = neigh_node;
1479         nc_packet->nc_path = nc_path;
1480
1481         /* Add coding packet to list */
1482         spin_lock_bh(&nc_path->packet_list_lock);
1483         list_add_tail(&nc_packet->list, &nc_path->packet_list);
1484         spin_unlock_bh(&nc_path->packet_list_lock);
1485
1486         return true;
1487 }
1488
1489 /**
1490  * batadv_nc_skb_forward() - try to code a packet or add it to the coding packet
1491  *  buffer
1492  * @skb: data skb to forward
1493  * @neigh_node: next hop to forward packet to
1494  *
1495  * Return: true if the skb was consumed (encoded packet sent) or false otherwise
1496  */
1497 bool batadv_nc_skb_forward(struct sk_buff *skb,
1498                            struct batadv_neigh_node *neigh_node)
1499 {
1500         const struct net_device *netdev = neigh_node->if_incoming->soft_iface;
1501         struct batadv_priv *bat_priv = netdev_priv(netdev);
1502         struct batadv_unicast_packet *packet;
1503         struct batadv_nc_path *nc_path;
1504         struct ethhdr *ethhdr = eth_hdr(skb);
1505         __be32 packet_id;
1506         u8 *payload;
1507
1508         /* Check if network coding is enabled */
1509         if (!atomic_read(&bat_priv->network_coding))
1510                 goto out;
1511
1512         /* We only handle unicast packets */
1513         payload = skb_network_header(skb);
1514         packet = (struct batadv_unicast_packet *)payload;
1515         if (packet->packet_type != BATADV_UNICAST)
1516                 goto out;
1517
1518         /* Try to find a coding opportunity and send the skb if one is found */
1519         if (batadv_nc_skb_dst_search(skb, neigh_node, ethhdr))
1520                 return true;
1521
1522         /* Find or create a nc_path for this src-dst pair */
1523         nc_path = batadv_nc_get_path(bat_priv,
1524                                      bat_priv->nc.coding_hash,
1525                                      ethhdr->h_source,
1526                                      neigh_node->addr);
1527
1528         if (!nc_path)
1529                 goto out;
1530
1531         /* Add skb to nc_path */
1532         packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1533         if (!batadv_nc_skb_add_to_path(skb, nc_path, neigh_node, packet_id))
1534                 goto free_nc_path;
1535
1536         /* Packet is consumed */
1537         return true;
1538
1539 free_nc_path:
1540         batadv_nc_path_put(nc_path);
1541 out:
1542         /* Packet is not consumed */
1543         return false;
1544 }
1545
1546 /**
1547  * batadv_nc_skb_store_for_decoding() - save a clone of the skb which can be
1548  *  used when decoding coded packets
1549  * @bat_priv: the bat priv with all the soft interface information
1550  * @skb: data skb to store
1551  */
1552 void batadv_nc_skb_store_for_decoding(struct batadv_priv *bat_priv,
1553                                       struct sk_buff *skb)
1554 {
1555         struct batadv_unicast_packet *packet;
1556         struct batadv_nc_path *nc_path;
1557         struct ethhdr *ethhdr = eth_hdr(skb);
1558         __be32 packet_id;
1559         u8 *payload;
1560
1561         /* Check if network coding is enabled */
1562         if (!atomic_read(&bat_priv->network_coding))
1563                 goto out;
1564
1565         /* Check for supported packet type */
1566         payload = skb_network_header(skb);
1567         packet = (struct batadv_unicast_packet *)payload;
1568         if (packet->packet_type != BATADV_UNICAST)
1569                 goto out;
1570
1571         /* Find existing nc_path or create a new */
1572         nc_path = batadv_nc_get_path(bat_priv,
1573                                      bat_priv->nc.decoding_hash,
1574                                      ethhdr->h_source,
1575                                      ethhdr->h_dest);
1576
1577         if (!nc_path)
1578                 goto out;
1579
1580         /* Clone skb and adjust skb->data to point at batman header */
1581         skb = skb_clone(skb, GFP_ATOMIC);
1582         if (unlikely(!skb))
1583                 goto free_nc_path;
1584
1585         if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
1586                 goto free_skb;
1587
1588         if (unlikely(!skb_pull_rcsum(skb, ETH_HLEN)))
1589                 goto free_skb;
1590
1591         /* Add skb to nc_path */
1592         packet_id = batadv_skb_crc32(skb, payload + sizeof(*packet));
1593         if (!batadv_nc_skb_add_to_path(skb, nc_path, NULL, packet_id))
1594                 goto free_skb;
1595
1596         batadv_inc_counter(bat_priv, BATADV_CNT_NC_BUFFER);
1597         return;
1598
1599 free_skb:
1600         kfree_skb(skb);
1601 free_nc_path:
1602         batadv_nc_path_put(nc_path);
1603 out:
1604         return;
1605 }
1606
1607 /**
1608  * batadv_nc_skb_store_sniffed_unicast() - check if a received unicast packet
1609  *  should be saved in the decoding buffer and, if so, store it there
1610  * @bat_priv: the bat priv with all the soft interface information
1611  * @skb: unicast skb to store
1612  */
1613 void batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv,
1614                                          struct sk_buff *skb)
1615 {
1616         struct ethhdr *ethhdr = eth_hdr(skb);
1617
1618         if (batadv_is_my_mac(bat_priv, ethhdr->h_dest))
1619                 return;
1620
1621         /* Set data pointer to MAC header to mimic packets from our tx path */
1622         skb_push(skb, ETH_HLEN);
1623
1624         batadv_nc_skb_store_for_decoding(bat_priv, skb);
1625 }
1626
1627 /**
1628  * batadv_nc_skb_decode_packet() - decode given skb using the decode data stored
1629  *  in nc_packet
1630  * @bat_priv: the bat priv with all the soft interface information
1631  * @skb: unicast skb to decode
1632  * @nc_packet: decode data needed to decode the skb
1633  *
1634  * Return: pointer to decoded unicast packet if the packet was decoded or NULL
1635  * in case of an error.
1636  */
1637 static struct batadv_unicast_packet *
1638 batadv_nc_skb_decode_packet(struct batadv_priv *bat_priv, struct sk_buff *skb,
1639                             struct batadv_nc_packet *nc_packet)
1640 {
1641         const int h_size = sizeof(struct batadv_unicast_packet);
1642         const int h_diff = sizeof(struct batadv_coded_packet) - h_size;
1643         struct batadv_unicast_packet *unicast_packet;
1644         struct batadv_coded_packet coded_packet_tmp;
1645         struct ethhdr *ethhdr, ethhdr_tmp;
1646         u8 *orig_dest, ttl, ttvn;
1647         unsigned int coding_len;
1648         int err;
1649
1650         /* Save headers temporarily */
1651         memcpy(&coded_packet_tmp, skb->data, sizeof(coded_packet_tmp));
1652         memcpy(&ethhdr_tmp, skb_mac_header(skb), sizeof(ethhdr_tmp));
1653
1654         if (skb_cow(skb, 0) < 0)
1655                 return NULL;
1656
1657         if (unlikely(!skb_pull_rcsum(skb, h_diff)))
1658                 return NULL;
1659
1660         /* Data points to batman header, so set mac header 14 bytes before
1661          * and network to data
1662          */
1663         skb_set_mac_header(skb, -ETH_HLEN);
1664         skb_reset_network_header(skb);
1665
1666         /* Reconstruct original mac header */
1667         ethhdr = eth_hdr(skb);
1668         *ethhdr = ethhdr_tmp;
1669
1670         /* Select the correct unicast header information based on the location
1671          * of our mac address in the coded_packet header
1672          */
1673         if (batadv_is_my_mac(bat_priv, coded_packet_tmp.second_dest)) {
1674                 /* If we are the second destination the packet was overheard,
1675                  * so the Ethernet address must be copied to h_dest and
1676                  * pkt_type changed from PACKET_OTHERHOST to PACKET_HOST
1677                  */
1678                 ether_addr_copy(ethhdr->h_dest, coded_packet_tmp.second_dest);
1679                 skb->pkt_type = PACKET_HOST;
1680
1681                 orig_dest = coded_packet_tmp.second_orig_dest;
1682                 ttl = coded_packet_tmp.second_ttl;
1683                 ttvn = coded_packet_tmp.second_ttvn;
1684         } else {
1685                 orig_dest = coded_packet_tmp.first_orig_dest;
1686                 ttl = coded_packet_tmp.ttl;
1687                 ttvn = coded_packet_tmp.first_ttvn;
1688         }
1689
1690         coding_len = ntohs(coded_packet_tmp.coded_len);
1691
1692         if (coding_len > skb->len)
1693                 return NULL;
1694
1695         /* Here the magic is reversed:
1696          *   extract the missing packet from the received coded packet
1697          */
1698         batadv_nc_memxor(skb->data + h_size,
1699                          nc_packet->skb->data + h_size,
1700                          coding_len);
1701
1702         /* Resize decoded skb if decoded with larger packet */
1703         if (nc_packet->skb->len > coding_len + h_size) {
1704                 err = pskb_trim_rcsum(skb, coding_len + h_size);
1705                 if (err)
1706                         return NULL;
1707         }
1708
1709         /* Create decoded unicast packet */
1710         unicast_packet = (struct batadv_unicast_packet *)skb->data;
1711         unicast_packet->packet_type = BATADV_UNICAST;
1712         unicast_packet->version = BATADV_COMPAT_VERSION;
1713         unicast_packet->ttl = ttl;
1714         ether_addr_copy(unicast_packet->dest, orig_dest);
1715         unicast_packet->ttvn = ttvn;
1716
1717         batadv_nc_packet_free(nc_packet, false);
1718         return unicast_packet;
1719 }
1720
1721 /**
1722  * batadv_nc_find_decoding_packet() - search through buffered decoding data to
1723  *  find the data needed to decode the coded packet
1724  * @bat_priv: the bat priv with all the soft interface information
1725  * @ethhdr: pointer to the ethernet header inside the coded packet
1726  * @coded: coded packet we try to find decode data for
1727  *
1728  * Return: pointer to nc packet if the needed data was found or NULL otherwise.
1729  */
1730 static struct batadv_nc_packet *
1731 batadv_nc_find_decoding_packet(struct batadv_priv *bat_priv,
1732                                struct ethhdr *ethhdr,
1733                                struct batadv_coded_packet *coded)
1734 {
1735         struct batadv_hashtable *hash = bat_priv->nc.decoding_hash;
1736         struct batadv_nc_packet *tmp_nc_packet, *nc_packet = NULL;
1737         struct batadv_nc_path *nc_path, nc_path_key;
1738         u8 *dest, *source;
1739         __be32 packet_id;
1740         int index;
1741
1742         if (!hash)
1743                 return NULL;
1744
1745         /* Select the correct packet id based on the location of our mac-addr */
1746         dest = ethhdr->h_source;
1747         if (!batadv_is_my_mac(bat_priv, coded->second_dest)) {
1748                 source = coded->second_source;
1749                 packet_id = coded->second_crc;
1750         } else {
1751                 source = coded->first_source;
1752                 packet_id = coded->first_crc;
1753         }
1754
1755         batadv_nc_hash_key_gen(&nc_path_key, source, dest);
1756         index = batadv_nc_hash_choose(&nc_path_key, hash->size);
1757
1758         /* Search for matching coding path */
1759         rcu_read_lock();
1760         hlist_for_each_entry_rcu(nc_path, &hash->table[index], hash_entry) {
1761                 /* Find matching nc_packet */
1762                 spin_lock_bh(&nc_path->packet_list_lock);
1763                 list_for_each_entry(tmp_nc_packet,
1764                                     &nc_path->packet_list, list) {
1765                         if (packet_id == tmp_nc_packet->packet_id) {
1766                                 list_del(&tmp_nc_packet->list);
1767
1768                                 nc_packet = tmp_nc_packet;
1769                                 break;
1770                         }
1771                 }
1772                 spin_unlock_bh(&nc_path->packet_list_lock);
1773
1774                 if (nc_packet)
1775                         break;
1776         }
1777         rcu_read_unlock();
1778
1779         if (!nc_packet)
1780                 batadv_dbg(BATADV_DBG_NC, bat_priv,
1781                            "No decoding packet found for %u\n", packet_id);
1782
1783         return nc_packet;
1784 }
1785
1786 /**
1787  * batadv_nc_recv_coded_packet() - try to decode coded packet and enqueue the
1788  *  resulting unicast packet
1789  * @skb: incoming coded packet
1790  * @recv_if: pointer to interface this packet was received on
1791  *
1792  * Return: NET_RX_SUCCESS if the packet has been consumed or NET_RX_DROP
1793  * otherwise.
1794  */
1795 static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
1796                                        struct batadv_hard_iface *recv_if)
1797 {
1798         struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
1799         struct batadv_unicast_packet *unicast_packet;
1800         struct batadv_coded_packet *coded_packet;
1801         struct batadv_nc_packet *nc_packet;
1802         struct ethhdr *ethhdr;
1803         int hdr_size = sizeof(*coded_packet);
1804
1805         /* Check if network coding is enabled */
1806         if (!atomic_read(&bat_priv->network_coding))
1807                 goto free_skb;
1808
1809         /* Make sure we can access (and remove) header */
1810         if (unlikely(!pskb_may_pull(skb, hdr_size)))
1811                 goto free_skb;
1812
1813         coded_packet = (struct batadv_coded_packet *)skb->data;
1814         ethhdr = eth_hdr(skb);
1815
1816         /* Verify frame is destined for us */
1817         if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest) &&
1818             !batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1819                 goto free_skb;
1820
1821         /* Update stat counter */
1822         if (batadv_is_my_mac(bat_priv, coded_packet->second_dest))
1823                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_SNIFFED);
1824
1825         nc_packet = batadv_nc_find_decoding_packet(bat_priv, ethhdr,
1826                                                    coded_packet);
1827         if (!nc_packet) {
1828                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1829                 goto free_skb;
1830         }
1831
1832         /* Make skb's linear, because decoding accesses the entire buffer */
1833         if (skb_linearize(skb) < 0)
1834                 goto free_nc_packet;
1835
1836         if (skb_linearize(nc_packet->skb) < 0)
1837                 goto free_nc_packet;
1838
1839         /* Decode the packet */
1840         unicast_packet = batadv_nc_skb_decode_packet(bat_priv, skb, nc_packet);
1841         if (!unicast_packet) {
1842                 batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
1843                 goto free_nc_packet;
1844         }
1845
1846         /* Mark packet as decoded to do correct recoding when forwarding */
1847         BATADV_SKB_CB(skb)->decoded = true;
1848         batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE);
1849         batadv_add_counter(bat_priv, BATADV_CNT_NC_DECODE_BYTES,
1850                            skb->len + ETH_HLEN);
1851         return batadv_recv_unicast_packet(skb, recv_if);
1852
1853 free_nc_packet:
1854         batadv_nc_packet_free(nc_packet, true);
1855 free_skb:
1856         kfree_skb(skb);
1857
1858         return NET_RX_DROP;
1859 }
1860
1861 /**
1862  * batadv_nc_mesh_free() - clean up network coding memory
1863  * @bat_priv: the bat priv with all the soft interface information
1864  */
1865 void batadv_nc_mesh_free(struct batadv_priv *bat_priv)
1866 {
1867         batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_NC, 1);
1868         batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_NC, 1);
1869         cancel_delayed_work_sync(&bat_priv->nc.work);
1870
1871         batadv_nc_purge_paths(bat_priv, bat_priv->nc.coding_hash, NULL);
1872         batadv_hash_destroy(bat_priv->nc.coding_hash);
1873         batadv_nc_purge_paths(bat_priv, bat_priv->nc.decoding_hash, NULL);
1874         batadv_hash_destroy(bat_priv->nc.decoding_hash);
1875 }