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TOMOYO Linux Cross Reference
Linux/net/batman-adv/distributed-arp-table.c

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  1 /* Copyright (C) 2011-2017  B.A.T.M.A.N. contributors:
  2  *
  3  * Antonio Quartulli
  4  *
  5  * This program is free software; you can redistribute it and/or
  6  * modify it under the terms of version 2 of the GNU General Public
  7  * License as published by the Free Software Foundation.
  8  *
  9  * This program is distributed in the hope that it will be useful, but
 10  * WITHOUT ANY WARRANTY; without even the implied warranty of
 11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 12  * General Public License for more details.
 13  *
 14  * You should have received a copy of the GNU General Public License
 15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
 16  */
 17 
 18 #include "distributed-arp-table.h"
 19 #include "main.h"
 20 
 21 #include <linux/atomic.h>
 22 #include <linux/bitops.h>
 23 #include <linux/byteorder/generic.h>
 24 #include <linux/errno.h>
 25 #include <linux/etherdevice.h>
 26 #include <linux/fs.h>
 27 #include <linux/if_arp.h>
 28 #include <linux/if_ether.h>
 29 #include <linux/if_vlan.h>
 30 #include <linux/in.h>
 31 #include <linux/jiffies.h>
 32 #include <linux/kernel.h>
 33 #include <linux/kref.h>
 34 #include <linux/list.h>
 35 #include <linux/rculist.h>
 36 #include <linux/rcupdate.h>
 37 #include <linux/seq_file.h>
 38 #include <linux/skbuff.h>
 39 #include <linux/slab.h>
 40 #include <linux/spinlock.h>
 41 #include <linux/stddef.h>
 42 #include <linux/string.h>
 43 #include <linux/workqueue.h>
 44 #include <net/arp.h>
 45 
 46 #include "bridge_loop_avoidance.h"
 47 #include "hard-interface.h"
 48 #include "hash.h"
 49 #include "log.h"
 50 #include "originator.h"
 51 #include "send.h"
 52 #include "translation-table.h"
 53 #include "tvlv.h"
 54 
 55 static void batadv_dat_purge(struct work_struct *work);
 56 
 57 /**
 58  * batadv_dat_start_timer - initialise the DAT periodic worker
 59  * @bat_priv: the bat priv with all the soft interface information
 60  */
 61 static void batadv_dat_start_timer(struct batadv_priv *bat_priv)
 62 {
 63         INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge);
 64         queue_delayed_work(batadv_event_workqueue, &bat_priv->dat.work,
 65                            msecs_to_jiffies(10000));
 66 }
 67 
 68 /**
 69  * batadv_dat_entry_release - release dat_entry from lists and queue for free
 70  *  after rcu grace period
 71  * @ref: kref pointer of the dat_entry
 72  */
 73 static void batadv_dat_entry_release(struct kref *ref)
 74 {
 75         struct batadv_dat_entry *dat_entry;
 76 
 77         dat_entry = container_of(ref, struct batadv_dat_entry, refcount);
 78 
 79         kfree_rcu(dat_entry, rcu);
 80 }
 81 
 82 /**
 83  * batadv_dat_entry_put - decrement the dat_entry refcounter and possibly
 84  *  release it
 85  * @dat_entry: dat_entry to be free'd
 86  */
 87 static void batadv_dat_entry_put(struct batadv_dat_entry *dat_entry)
 88 {
 89         kref_put(&dat_entry->refcount, batadv_dat_entry_release);
 90 }
 91 
 92 /**
 93  * batadv_dat_to_purge - check whether a dat_entry has to be purged or not
 94  * @dat_entry: the entry to check
 95  *
 96  * Return: true if the entry has to be purged now, false otherwise.
 97  */
 98 static bool batadv_dat_to_purge(struct batadv_dat_entry *dat_entry)
 99 {
100         return batadv_has_timed_out(dat_entry->last_update,
101                                     BATADV_DAT_ENTRY_TIMEOUT);
102 }
103 
104 /**
105  * __batadv_dat_purge - delete entries from the DAT local storage
106  * @bat_priv: the bat priv with all the soft interface information
107  * @to_purge: function in charge to decide whether an entry has to be purged or
108  *            not. This function takes the dat_entry as argument and has to
109  *            returns a boolean value: true is the entry has to be deleted,
110  *            false otherwise
111  *
112  * Loops over each entry in the DAT local storage and deletes it if and only if
113  * the to_purge function passed as argument returns true.
114  */
115 static void __batadv_dat_purge(struct batadv_priv *bat_priv,
116                                bool (*to_purge)(struct batadv_dat_entry *))
117 {
118         spinlock_t *list_lock; /* protects write access to the hash lists */
119         struct batadv_dat_entry *dat_entry;
120         struct hlist_node *node_tmp;
121         struct hlist_head *head;
122         u32 i;
123 
124         if (!bat_priv->dat.hash)
125                 return;
126 
127         for (i = 0; i < bat_priv->dat.hash->size; i++) {
128                 head = &bat_priv->dat.hash->table[i];
129                 list_lock = &bat_priv->dat.hash->list_locks[i];
130 
131                 spin_lock_bh(list_lock);
132                 hlist_for_each_entry_safe(dat_entry, node_tmp, head,
133                                           hash_entry) {
134                         /* if a helper function has been passed as parameter,
135                          * ask it if the entry has to be purged or not
136                          */
137                         if (to_purge && !to_purge(dat_entry))
138                                 continue;
139 
140                         hlist_del_rcu(&dat_entry->hash_entry);
141                         batadv_dat_entry_put(dat_entry);
142                 }
143                 spin_unlock_bh(list_lock);
144         }
145 }
146 
147 /**
148  * batadv_dat_purge - periodic task that deletes old entries from the local DAT
149  * hash table
150  * @work: kernel work struct
151  */
152 static void batadv_dat_purge(struct work_struct *work)
153 {
154         struct delayed_work *delayed_work;
155         struct batadv_priv_dat *priv_dat;
156         struct batadv_priv *bat_priv;
157 
158         delayed_work = to_delayed_work(work);
159         priv_dat = container_of(delayed_work, struct batadv_priv_dat, work);
160         bat_priv = container_of(priv_dat, struct batadv_priv, dat);
161 
162         __batadv_dat_purge(bat_priv, batadv_dat_to_purge);
163         batadv_dat_start_timer(bat_priv);
164 }
165 
166 /**
167  * batadv_compare_dat - comparing function used in the local DAT hash table
168  * @node: node in the local table
169  * @data2: second object to compare the node to
170  *
171  * Return: true if the two entries are the same, false otherwise.
172  */
173 static bool batadv_compare_dat(const struct hlist_node *node, const void *data2)
174 {
175         const void *data1 = container_of(node, struct batadv_dat_entry,
176                                          hash_entry);
177 
178         return memcmp(data1, data2, sizeof(__be32)) == 0;
179 }
180 
181 /**
182  * batadv_arp_hw_src - extract the hw_src field from an ARP packet
183  * @skb: ARP packet
184  * @hdr_size: size of the possible header before the ARP packet
185  *
186  * Return: the value of the hw_src field in the ARP packet.
187  */
188 static u8 *batadv_arp_hw_src(struct sk_buff *skb, int hdr_size)
189 {
190         u8 *addr;
191 
192         addr = (u8 *)(skb->data + hdr_size);
193         addr += ETH_HLEN + sizeof(struct arphdr);
194 
195         return addr;
196 }
197 
198 /**
199  * batadv_arp_ip_src - extract the ip_src field from an ARP packet
200  * @skb: ARP packet
201  * @hdr_size: size of the possible header before the ARP packet
202  *
203  * Return: the value of the ip_src field in the ARP packet.
204  */
205 static __be32 batadv_arp_ip_src(struct sk_buff *skb, int hdr_size)
206 {
207         return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN);
208 }
209 
210 /**
211  * batadv_arp_hw_dst - extract the hw_dst field from an ARP packet
212  * @skb: ARP packet
213  * @hdr_size: size of the possible header before the ARP packet
214  *
215  * Return: the value of the hw_dst field in the ARP packet.
216  */
217 static u8 *batadv_arp_hw_dst(struct sk_buff *skb, int hdr_size)
218 {
219         return batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN + 4;
220 }
221 
222 /**
223  * batadv_arp_ip_dst - extract the ip_dst field from an ARP packet
224  * @skb: ARP packet
225  * @hdr_size: size of the possible header before the ARP packet
226  *
227  * Return: the value of the ip_dst field in the ARP packet.
228  */
229 static __be32 batadv_arp_ip_dst(struct sk_buff *skb, int hdr_size)
230 {
231         return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4);
232 }
233 
234 /**
235  * batadv_hash_dat - compute the hash value for an IP address
236  * @data: data to hash
237  * @size: size of the hash table
238  *
239  * Return: the selected index in the hash table for the given data.
240  */
241 static u32 batadv_hash_dat(const void *data, u32 size)
242 {
243         u32 hash = 0;
244         const struct batadv_dat_entry *dat = data;
245         const unsigned char *key;
246         u32 i;
247 
248         key = (const unsigned char *)&dat->ip;
249         for (i = 0; i < sizeof(dat->ip); i++) {
250                 hash += key[i];
251                 hash += (hash << 10);
252                 hash ^= (hash >> 6);
253         }
254 
255         key = (const unsigned char *)&dat->vid;
256         for (i = 0; i < sizeof(dat->vid); i++) {
257                 hash += key[i];
258                 hash += (hash << 10);
259                 hash ^= (hash >> 6);
260         }
261 
262         hash += (hash << 3);
263         hash ^= (hash >> 11);
264         hash += (hash << 15);
265 
266         return hash % size;
267 }
268 
269 /**
270  * batadv_dat_entry_hash_find - look for a given dat_entry in the local hash
271  * table
272  * @bat_priv: the bat priv with all the soft interface information
273  * @ip: search key
274  * @vid: VLAN identifier
275  *
276  * Return: the dat_entry if found, NULL otherwise.
277  */
278 static struct batadv_dat_entry *
279 batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
280                            unsigned short vid)
281 {
282         struct hlist_head *head;
283         struct batadv_dat_entry to_find, *dat_entry, *dat_entry_tmp = NULL;
284         struct batadv_hashtable *hash = bat_priv->dat.hash;
285         u32 index;
286 
287         if (!hash)
288                 return NULL;
289 
290         to_find.ip = ip;
291         to_find.vid = vid;
292 
293         index = batadv_hash_dat(&to_find, hash->size);
294         head = &hash->table[index];
295 
296         rcu_read_lock();
297         hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
298                 if (dat_entry->ip != ip)
299                         continue;
300 
301                 if (!kref_get_unless_zero(&dat_entry->refcount))
302                         continue;
303 
304                 dat_entry_tmp = dat_entry;
305                 break;
306         }
307         rcu_read_unlock();
308 
309         return dat_entry_tmp;
310 }
311 
312 /**
313  * batadv_dat_entry_add - add a new dat entry or update it if already exists
314  * @bat_priv: the bat priv with all the soft interface information
315  * @ip: ipv4 to add/edit
316  * @mac_addr: mac address to assign to the given ipv4
317  * @vid: VLAN identifier
318  */
319 static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
320                                  u8 *mac_addr, unsigned short vid)
321 {
322         struct batadv_dat_entry *dat_entry;
323         int hash_added;
324 
325         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip, vid);
326         /* if this entry is already known, just update it */
327         if (dat_entry) {
328                 if (!batadv_compare_eth(dat_entry->mac_addr, mac_addr))
329                         ether_addr_copy(dat_entry->mac_addr, mac_addr);
330                 dat_entry->last_update = jiffies;
331                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
332                            "Entry updated: %pI4 %pM (vid: %d)\n",
333                            &dat_entry->ip, dat_entry->mac_addr,
334                            batadv_print_vid(vid));
335                 goto out;
336         }
337 
338         dat_entry = kmalloc(sizeof(*dat_entry), GFP_ATOMIC);
339         if (!dat_entry)
340                 goto out;
341 
342         dat_entry->ip = ip;
343         dat_entry->vid = vid;
344         ether_addr_copy(dat_entry->mac_addr, mac_addr);
345         dat_entry->last_update = jiffies;
346         kref_init(&dat_entry->refcount);
347 
348         kref_get(&dat_entry->refcount);
349         hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
350                                      batadv_hash_dat, dat_entry,
351                                      &dat_entry->hash_entry);
352 
353         if (unlikely(hash_added != 0)) {
354                 /* remove the reference for the hash */
355                 batadv_dat_entry_put(dat_entry);
356                 goto out;
357         }
358 
359         batadv_dbg(BATADV_DBG_DAT, bat_priv, "New entry added: %pI4 %pM (vid: %d)\n",
360                    &dat_entry->ip, dat_entry->mac_addr, batadv_print_vid(vid));
361 
362 out:
363         if (dat_entry)
364                 batadv_dat_entry_put(dat_entry);
365 }
366 
367 #ifdef CONFIG_BATMAN_ADV_DEBUG
368 
369 /**
370  * batadv_dbg_arp - print a debug message containing all the ARP packet details
371  * @bat_priv: the bat priv with all the soft interface information
372  * @skb: ARP packet
373  * @hdr_size: size of the possible header before the ARP packet
374  * @msg: message to print together with the debugging information
375  */
376 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
377                            int hdr_size, char *msg)
378 {
379         struct batadv_unicast_4addr_packet *unicast_4addr_packet;
380         struct batadv_bcast_packet *bcast_pkt;
381         u8 *orig_addr;
382         __be32 ip_src, ip_dst;
383 
384         if (msg)
385                 batadv_dbg(BATADV_DBG_DAT, bat_priv, "%s\n", msg);
386 
387         ip_src = batadv_arp_ip_src(skb, hdr_size);
388         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
389         batadv_dbg(BATADV_DBG_DAT, bat_priv,
390                    "ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]\n",
391                    batadv_arp_hw_src(skb, hdr_size), &ip_src,
392                    batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
393 
394         if (hdr_size == 0)
395                 return;
396 
397         unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
398 
399         switch (unicast_4addr_packet->u.packet_type) {
400         case BATADV_UNICAST:
401                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
402                            "* encapsulated within a UNICAST packet\n");
403                 break;
404         case BATADV_UNICAST_4ADDR:
405                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
406                            "* encapsulated within a UNICAST_4ADDR packet (src: %pM)\n",
407                            unicast_4addr_packet->src);
408                 switch (unicast_4addr_packet->subtype) {
409                 case BATADV_P_DAT_DHT_PUT:
410                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_PUT\n");
411                         break;
412                 case BATADV_P_DAT_DHT_GET:
413                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_GET\n");
414                         break;
415                 case BATADV_P_DAT_CACHE_REPLY:
416                         batadv_dbg(BATADV_DBG_DAT, bat_priv,
417                                    "* type: DAT_CACHE_REPLY\n");
418                         break;
419                 case BATADV_P_DATA:
420                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DATA\n");
421                         break;
422                 default:
423                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: Unknown (%u)!\n",
424                                    unicast_4addr_packet->u.packet_type);
425                 }
426                 break;
427         case BATADV_BCAST:
428                 bcast_pkt = (struct batadv_bcast_packet *)unicast_4addr_packet;
429                 orig_addr = bcast_pkt->orig;
430                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
431                            "* encapsulated within a BCAST packet (src: %pM)\n",
432                            orig_addr);
433                 break;
434         default:
435                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
436                            "* encapsulated within an unknown packet type (0x%x)\n",
437                            unicast_4addr_packet->u.packet_type);
438         }
439 }
440 
441 #else
442 
443 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
444                            int hdr_size, char *msg)
445 {
446 }
447 
448 #endif /* CONFIG_BATMAN_ADV_DEBUG */
449 
450 /**
451  * batadv_is_orig_node_eligible - check whether a node can be a DHT candidate
452  * @res: the array with the already selected candidates
453  * @select: number of already selected candidates
454  * @tmp_max: address of the currently evaluated node
455  * @max: current round max address
456  * @last_max: address of the last selected candidate
457  * @candidate: orig_node under evaluation
458  * @max_orig_node: last selected candidate
459  *
460  * Return: true if the node has been elected as next candidate or false
461  * otherwise.
462  */
463 static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
464                                          int select, batadv_dat_addr_t tmp_max,
465                                          batadv_dat_addr_t max,
466                                          batadv_dat_addr_t last_max,
467                                          struct batadv_orig_node *candidate,
468                                          struct batadv_orig_node *max_orig_node)
469 {
470         bool ret = false;
471         int j;
472 
473         /* check if orig node candidate is running DAT */
474         if (!test_bit(BATADV_ORIG_CAPA_HAS_DAT, &candidate->capabilities))
475                 goto out;
476 
477         /* Check if this node has already been selected... */
478         for (j = 0; j < select; j++)
479                 if (res[j].orig_node == candidate)
480                         break;
481         /* ..and possibly skip it */
482         if (j < select)
483                 goto out;
484         /* sanity check: has it already been selected? This should not happen */
485         if (tmp_max > last_max)
486                 goto out;
487         /* check if during this iteration an originator with a closer dht
488          * address has already been found
489          */
490         if (tmp_max < max)
491                 goto out;
492         /* this is an hash collision with the temporary selected node. Choose
493          * the one with the lowest address
494          */
495         if ((tmp_max == max) && max_orig_node &&
496             (batadv_compare_eth(candidate->orig, max_orig_node->orig) > 0))
497                 goto out;
498 
499         ret = true;
500 out:
501         return ret;
502 }
503 
504 /**
505  * batadv_choose_next_candidate - select the next DHT candidate
506  * @bat_priv: the bat priv with all the soft interface information
507  * @cands: candidates array
508  * @select: number of candidates already present in the array
509  * @ip_key: key to look up in the DHT
510  * @last_max: pointer where the address of the selected candidate will be saved
511  */
512 static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
513                                          struct batadv_dat_candidate *cands,
514                                          int select, batadv_dat_addr_t ip_key,
515                                          batadv_dat_addr_t *last_max)
516 {
517         batadv_dat_addr_t max = 0;
518         batadv_dat_addr_t tmp_max = 0;
519         struct batadv_orig_node *orig_node, *max_orig_node = NULL;
520         struct batadv_hashtable *hash = bat_priv->orig_hash;
521         struct hlist_head *head;
522         int i;
523 
524         /* if no node is eligible as candidate, leave the candidate type as
525          * NOT_FOUND
526          */
527         cands[select].type = BATADV_DAT_CANDIDATE_NOT_FOUND;
528 
529         /* iterate over the originator list and find the node with the closest
530          * dat_address which has not been selected yet
531          */
532         for (i = 0; i < hash->size; i++) {
533                 head = &hash->table[i];
534 
535                 rcu_read_lock();
536                 hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
537                         /* the dht space is a ring using unsigned addresses */
538                         tmp_max = BATADV_DAT_ADDR_MAX - orig_node->dat_addr +
539                                   ip_key;
540 
541                         if (!batadv_is_orig_node_eligible(cands, select,
542                                                           tmp_max, max,
543                                                           *last_max, orig_node,
544                                                           max_orig_node))
545                                 continue;
546 
547                         if (!kref_get_unless_zero(&orig_node->refcount))
548                                 continue;
549 
550                         max = tmp_max;
551                         if (max_orig_node)
552                                 batadv_orig_node_put(max_orig_node);
553                         max_orig_node = orig_node;
554                 }
555                 rcu_read_unlock();
556         }
557         if (max_orig_node) {
558                 cands[select].type = BATADV_DAT_CANDIDATE_ORIG;
559                 cands[select].orig_node = max_orig_node;
560                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
561                            "dat_select_candidates() %d: selected %pM addr=%u dist=%u\n",
562                            select, max_orig_node->orig, max_orig_node->dat_addr,
563                            max);
564         }
565         *last_max = max;
566 }
567 
568 /**
569  * batadv_dat_select_candidates - select the nodes which the DHT message has to
570  * be sent to
571  * @bat_priv: the bat priv with all the soft interface information
572  * @ip_dst: ipv4 to look up in the DHT
573  * @vid: VLAN identifier
574  *
575  * An originator O is selected if and only if its DHT_ID value is one of three
576  * closest values (from the LEFT, with wrap around if needed) then the hash
577  * value of the key. ip_dst is the key.
578  *
579  * Return: the candidate array of size BATADV_DAT_CANDIDATE_NUM.
580  */
581 static struct batadv_dat_candidate *
582 batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst,
583                              unsigned short vid)
584 {
585         int select;
586         batadv_dat_addr_t last_max = BATADV_DAT_ADDR_MAX, ip_key;
587         struct batadv_dat_candidate *res;
588         struct batadv_dat_entry dat;
589 
590         if (!bat_priv->orig_hash)
591                 return NULL;
592 
593         res = kmalloc_array(BATADV_DAT_CANDIDATES_NUM, sizeof(*res),
594                             GFP_ATOMIC);
595         if (!res)
596                 return NULL;
597 
598         dat.ip = ip_dst;
599         dat.vid = vid;
600         ip_key = (batadv_dat_addr_t)batadv_hash_dat(&dat,
601                                                     BATADV_DAT_ADDR_MAX);
602 
603         batadv_dbg(BATADV_DBG_DAT, bat_priv,
604                    "dat_select_candidates(): IP=%pI4 hash(IP)=%u\n", &ip_dst,
605                    ip_key);
606 
607         for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
608                 batadv_choose_next_candidate(bat_priv, res, select, ip_key,
609                                              &last_max);
610 
611         return res;
612 }
613 
614 /**
615  * batadv_dat_send_data - send a payload to the selected candidates
616  * @bat_priv: the bat priv with all the soft interface information
617  * @skb: payload to send
618  * @ip: the DHT key
619  * @vid: VLAN identifier
620  * @packet_subtype: unicast4addr packet subtype to use
621  *
622  * This function copies the skb with pskb_copy() and is sent as unicast packet
623  * to each of the selected candidates.
624  *
625  * Return: true if the packet is sent to at least one candidate, false
626  * otherwise.
627  */
628 static bool batadv_dat_send_data(struct batadv_priv *bat_priv,
629                                  struct sk_buff *skb, __be32 ip,
630                                  unsigned short vid, int packet_subtype)
631 {
632         int i;
633         bool ret = false;
634         int send_status;
635         struct batadv_neigh_node *neigh_node = NULL;
636         struct sk_buff *tmp_skb;
637         struct batadv_dat_candidate *cand;
638 
639         cand = batadv_dat_select_candidates(bat_priv, ip, vid);
640         if (!cand)
641                 goto out;
642 
643         batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
644 
645         for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
646                 if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
647                         continue;
648 
649                 neigh_node = batadv_orig_router_get(cand[i].orig_node,
650                                                     BATADV_IF_DEFAULT);
651                 if (!neigh_node)
652                         goto free_orig;
653 
654                 tmp_skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
655                 if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, tmp_skb,
656                                                            cand[i].orig_node,
657                                                            packet_subtype)) {
658                         kfree_skb(tmp_skb);
659                         goto free_neigh;
660                 }
661 
662                 send_status = batadv_send_unicast_skb(tmp_skb, neigh_node);
663                 if (send_status == NET_XMIT_SUCCESS) {
664                         /* count the sent packet */
665                         switch (packet_subtype) {
666                         case BATADV_P_DAT_DHT_GET:
667                                 batadv_inc_counter(bat_priv,
668                                                    BATADV_CNT_DAT_GET_TX);
669                                 break;
670                         case BATADV_P_DAT_DHT_PUT:
671                                 batadv_inc_counter(bat_priv,
672                                                    BATADV_CNT_DAT_PUT_TX);
673                                 break;
674                         }
675 
676                         /* packet sent to a candidate: return true */
677                         ret = true;
678                 }
679 free_neigh:
680                 batadv_neigh_node_put(neigh_node);
681 free_orig:
682                 batadv_orig_node_put(cand[i].orig_node);
683         }
684 
685 out:
686         kfree(cand);
687         return ret;
688 }
689 
690 /**
691  * batadv_dat_tvlv_container_update - update the dat tvlv container after dat
692  *  setting change
693  * @bat_priv: the bat priv with all the soft interface information
694  */
695 static void batadv_dat_tvlv_container_update(struct batadv_priv *bat_priv)
696 {
697         char dat_mode;
698 
699         dat_mode = atomic_read(&bat_priv->distributed_arp_table);
700 
701         switch (dat_mode) {
702         case 0:
703                 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
704                 break;
705         case 1:
706                 batadv_tvlv_container_register(bat_priv, BATADV_TVLV_DAT, 1,
707                                                NULL, 0);
708                 break;
709         }
710 }
711 
712 /**
713  * batadv_dat_status_update - update the dat tvlv container after dat
714  *  setting change
715  * @net_dev: the soft interface net device
716  */
717 void batadv_dat_status_update(struct net_device *net_dev)
718 {
719         struct batadv_priv *bat_priv = netdev_priv(net_dev);
720 
721         batadv_dat_tvlv_container_update(bat_priv);
722 }
723 
724 /**
725  * batadv_dat_tvlv_ogm_handler_v1 - process incoming dat tvlv container
726  * @bat_priv: the bat priv with all the soft interface information
727  * @orig: the orig_node of the ogm
728  * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
729  * @tvlv_value: tvlv buffer containing the gateway data
730  * @tvlv_value_len: tvlv buffer length
731  */
732 static void batadv_dat_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
733                                            struct batadv_orig_node *orig,
734                                            u8 flags,
735                                            void *tvlv_value, u16 tvlv_value_len)
736 {
737         if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
738                 clear_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
739         else
740                 set_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
741 }
742 
743 /**
744  * batadv_dat_hash_free - free the local DAT hash table
745  * @bat_priv: the bat priv with all the soft interface information
746  */
747 static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
748 {
749         if (!bat_priv->dat.hash)
750                 return;
751 
752         __batadv_dat_purge(bat_priv, NULL);
753 
754         batadv_hash_destroy(bat_priv->dat.hash);
755 
756         bat_priv->dat.hash = NULL;
757 }
758 
759 /**
760  * batadv_dat_init - initialise the DAT internals
761  * @bat_priv: the bat priv with all the soft interface information
762  *
763  * Return: 0 in case of success, a negative error code otherwise
764  */
765 int batadv_dat_init(struct batadv_priv *bat_priv)
766 {
767         if (bat_priv->dat.hash)
768                 return 0;
769 
770         bat_priv->dat.hash = batadv_hash_new(1024);
771 
772         if (!bat_priv->dat.hash)
773                 return -ENOMEM;
774 
775         batadv_dat_start_timer(bat_priv);
776 
777         batadv_tvlv_handler_register(bat_priv, batadv_dat_tvlv_ogm_handler_v1,
778                                      NULL, BATADV_TVLV_DAT, 1,
779                                      BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
780         batadv_dat_tvlv_container_update(bat_priv);
781         return 0;
782 }
783 
784 /**
785  * batadv_dat_free - free the DAT internals
786  * @bat_priv: the bat priv with all the soft interface information
787  */
788 void batadv_dat_free(struct batadv_priv *bat_priv)
789 {
790         batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
791         batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_DAT, 1);
792 
793         cancel_delayed_work_sync(&bat_priv->dat.work);
794 
795         batadv_dat_hash_free(bat_priv);
796 }
797 
798 #ifdef CONFIG_BATMAN_ADV_DEBUGFS
799 /**
800  * batadv_dat_cache_seq_print_text - print the local DAT hash table
801  * @seq: seq file to print on
802  * @offset: not used
803  *
804  * Return: always 0
805  */
806 int batadv_dat_cache_seq_print_text(struct seq_file *seq, void *offset)
807 {
808         struct net_device *net_dev = (struct net_device *)seq->private;
809         struct batadv_priv *bat_priv = netdev_priv(net_dev);
810         struct batadv_hashtable *hash = bat_priv->dat.hash;
811         struct batadv_dat_entry *dat_entry;
812         struct batadv_hard_iface *primary_if;
813         struct hlist_head *head;
814         unsigned long last_seen_jiffies;
815         int last_seen_msecs, last_seen_secs, last_seen_mins;
816         u32 i;
817 
818         primary_if = batadv_seq_print_text_primary_if_get(seq);
819         if (!primary_if)
820                 goto out;
821 
822         seq_printf(seq, "Distributed ARP Table (%s):\n", net_dev->name);
823         seq_puts(seq,
824                  "          IPv4             MAC        VID   last-seen\n");
825 
826         for (i = 0; i < hash->size; i++) {
827                 head = &hash->table[i];
828 
829                 rcu_read_lock();
830                 hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
831                         last_seen_jiffies = jiffies - dat_entry->last_update;
832                         last_seen_msecs = jiffies_to_msecs(last_seen_jiffies);
833                         last_seen_mins = last_seen_msecs / 60000;
834                         last_seen_msecs = last_seen_msecs % 60000;
835                         last_seen_secs = last_seen_msecs / 1000;
836 
837                         seq_printf(seq, " * %15pI4 %14pM %4i %6i:%02i\n",
838                                    &dat_entry->ip, dat_entry->mac_addr,
839                                    batadv_print_vid(dat_entry->vid),
840                                    last_seen_mins, last_seen_secs);
841                 }
842                 rcu_read_unlock();
843         }
844 
845 out:
846         if (primary_if)
847                 batadv_hardif_put(primary_if);
848         return 0;
849 }
850 #endif
851 
852 /**
853  * batadv_arp_get_type - parse an ARP packet and gets the type
854  * @bat_priv: the bat priv with all the soft interface information
855  * @skb: packet to analyse
856  * @hdr_size: size of the possible header before the ARP packet in the skb
857  *
858  * Return: the ARP type if the skb contains a valid ARP packet, 0 otherwise.
859  */
860 static u16 batadv_arp_get_type(struct batadv_priv *bat_priv,
861                                struct sk_buff *skb, int hdr_size)
862 {
863         struct arphdr *arphdr;
864         struct ethhdr *ethhdr;
865         __be32 ip_src, ip_dst;
866         u8 *hw_src, *hw_dst;
867         u16 type = 0;
868 
869         /* pull the ethernet header */
870         if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
871                 goto out;
872 
873         ethhdr = (struct ethhdr *)(skb->data + hdr_size);
874 
875         if (ethhdr->h_proto != htons(ETH_P_ARP))
876                 goto out;
877 
878         /* pull the ARP payload */
879         if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
880                                     arp_hdr_len(skb->dev))))
881                 goto out;
882 
883         arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
884 
885         /* check whether the ARP packet carries a valid IP information */
886         if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
887                 goto out;
888 
889         if (arphdr->ar_pro != htons(ETH_P_IP))
890                 goto out;
891 
892         if (arphdr->ar_hln != ETH_ALEN)
893                 goto out;
894 
895         if (arphdr->ar_pln != 4)
896                 goto out;
897 
898         /* Check for bad reply/request. If the ARP message is not sane, DAT
899          * will simply ignore it
900          */
901         ip_src = batadv_arp_ip_src(skb, hdr_size);
902         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
903         if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
904             ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst) ||
905             ipv4_is_zeronet(ip_src) || ipv4_is_lbcast(ip_src) ||
906             ipv4_is_zeronet(ip_dst) || ipv4_is_lbcast(ip_dst))
907                 goto out;
908 
909         hw_src = batadv_arp_hw_src(skb, hdr_size);
910         if (is_zero_ether_addr(hw_src) || is_multicast_ether_addr(hw_src))
911                 goto out;
912 
913         /* don't care about the destination MAC address in ARP requests */
914         if (arphdr->ar_op != htons(ARPOP_REQUEST)) {
915                 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
916                 if (is_zero_ether_addr(hw_dst) ||
917                     is_multicast_ether_addr(hw_dst))
918                         goto out;
919         }
920 
921         type = ntohs(arphdr->ar_op);
922 out:
923         return type;
924 }
925 
926 /**
927  * batadv_dat_get_vid - extract the VLAN identifier from skb if any
928  * @skb: the buffer containing the packet to extract the VID from
929  * @hdr_size: the size of the batman-adv header encapsulating the packet
930  *
931  * Return: If the packet embedded in the skb is vlan tagged this function
932  * returns the VID with the BATADV_VLAN_HAS_TAG flag. Otherwise BATADV_NO_FLAGS
933  * is returned.
934  */
935 static unsigned short batadv_dat_get_vid(struct sk_buff *skb, int *hdr_size)
936 {
937         unsigned short vid;
938 
939         vid = batadv_get_vid(skb, *hdr_size);
940 
941         /* ARP parsing functions jump forward of hdr_size + ETH_HLEN.
942          * If the header contained in the packet is a VLAN one (which is longer)
943          * hdr_size is updated so that the functions will still skip the
944          * correct amount of bytes.
945          */
946         if (vid & BATADV_VLAN_HAS_TAG)
947                 *hdr_size += VLAN_HLEN;
948 
949         return vid;
950 }
951 
952 /**
953  * batadv_dat_arp_create_reply - create an ARP Reply
954  * @bat_priv: the bat priv with all the soft interface information
955  * @ip_src: ARP sender IP
956  * @ip_dst: ARP target IP
957  * @hw_src: Ethernet source and ARP sender MAC
958  * @hw_dst: Ethernet destination and ARP target MAC
959  * @vid: VLAN identifier (optional, set to zero otherwise)
960  *
961  * Creates an ARP Reply from the given values, optionally encapsulated in a
962  * VLAN header.
963  *
964  * Return: An skb containing an ARP Reply.
965  */
966 static struct sk_buff *
967 batadv_dat_arp_create_reply(struct batadv_priv *bat_priv, __be32 ip_src,
968                             __be32 ip_dst, u8 *hw_src, u8 *hw_dst,
969                             unsigned short vid)
970 {
971         struct sk_buff *skb;
972 
973         skb = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_dst, bat_priv->soft_iface,
974                          ip_src, hw_dst, hw_src, hw_dst);
975         if (!skb)
976                 return NULL;
977 
978         skb_reset_mac_header(skb);
979 
980         if (vid & BATADV_VLAN_HAS_TAG)
981                 skb = vlan_insert_tag(skb, htons(ETH_P_8021Q),
982                                       vid & VLAN_VID_MASK);
983 
984         return skb;
985 }
986 
987 /**
988  * batadv_dat_snoop_outgoing_arp_request - snoop the ARP request and try to
989  * answer using DAT
990  * @bat_priv: the bat priv with all the soft interface information
991  * @skb: packet to check
992  *
993  * Return: true if the message has been sent to the dht candidates, false
994  * otherwise. In case of a positive return value the message has to be enqueued
995  * to permit the fallback.
996  */
997 bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
998                                            struct sk_buff *skb)
999 {
1000         u16 type = 0;
1001         __be32 ip_dst, ip_src;
1002         u8 *hw_src;
1003         bool ret = false;
1004         struct batadv_dat_entry *dat_entry = NULL;
1005         struct sk_buff *skb_new;
1006         struct net_device *soft_iface = bat_priv->soft_iface;
1007         int hdr_size = 0;
1008         unsigned short vid;
1009 
1010         if (!atomic_read(&bat_priv->distributed_arp_table))
1011                 goto out;
1012 
1013         vid = batadv_dat_get_vid(skb, &hdr_size);
1014 
1015         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1016         /* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast
1017          * message to the selected DHT candidates
1018          */
1019         if (type != ARPOP_REQUEST)
1020                 goto out;
1021 
1022         batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REQUEST");
1023 
1024         ip_src = batadv_arp_ip_src(skb, hdr_size);
1025         hw_src = batadv_arp_hw_src(skb, hdr_size);
1026         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1027 
1028         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1029 
1030         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1031         if (dat_entry) {
1032                 /* If the ARP request is destined for a local client the local
1033                  * client will answer itself. DAT would only generate a
1034                  * duplicate packet.
1035                  *
1036                  * Moreover, if the soft-interface is enslaved into a bridge, an
1037                  * additional DAT answer may trigger kernel warnings about
1038                  * a packet coming from the wrong port.
1039                  */
1040                 if (batadv_is_my_client(bat_priv, dat_entry->mac_addr, vid)) {
1041                         ret = true;
1042                         goto out;
1043                 }
1044 
1045                 /* If BLA is enabled, only send ARP replies if we have claimed
1046                  * the destination for the ARP request or if no one else of
1047                  * the backbone gws belonging to our backbone has claimed the
1048                  * destination.
1049                  */
1050                 if (!batadv_bla_check_claim(bat_priv,
1051                                             dat_entry->mac_addr, vid)) {
1052                         batadv_dbg(BATADV_DBG_DAT, bat_priv,
1053                                    "Device %pM claimed by another backbone gw. Don't send ARP reply!",
1054                                    dat_entry->mac_addr);
1055                         ret = true;
1056                         goto out;
1057                 }
1058 
1059                 skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
1060                                                       dat_entry->mac_addr,
1061                                                       hw_src, vid);
1062                 if (!skb_new)
1063                         goto out;
1064 
1065                 skb_new->protocol = eth_type_trans(skb_new, soft_iface);
1066 
1067                 batadv_inc_counter(bat_priv, BATADV_CNT_RX);
1068                 batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES,
1069                                    skb->len + ETH_HLEN + hdr_size);
1070 
1071                 netif_rx(skb_new);
1072                 batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
1073                 ret = true;
1074         } else {
1075                 /* Send the request to the DHT */
1076                 ret = batadv_dat_send_data(bat_priv, skb, ip_dst, vid,
1077                                            BATADV_P_DAT_DHT_GET);
1078         }
1079 out:
1080         if (dat_entry)
1081                 batadv_dat_entry_put(dat_entry);
1082         return ret;
1083 }
1084 
1085 /**
1086  * batadv_dat_snoop_incoming_arp_request - snoop the ARP request and try to
1087  * answer using the local DAT storage
1088  * @bat_priv: the bat priv with all the soft interface information
1089  * @skb: packet to check
1090  * @hdr_size: size of the encapsulation header
1091  *
1092  * Return: true if the request has been answered, false otherwise.
1093  */
1094 bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
1095                                            struct sk_buff *skb, int hdr_size)
1096 {
1097         u16 type;
1098         __be32 ip_src, ip_dst;
1099         u8 *hw_src;
1100         struct sk_buff *skb_new;
1101         struct batadv_dat_entry *dat_entry = NULL;
1102         bool ret = false;
1103         unsigned short vid;
1104         int err;
1105 
1106         if (!atomic_read(&bat_priv->distributed_arp_table))
1107                 goto out;
1108 
1109         vid = batadv_dat_get_vid(skb, &hdr_size);
1110 
1111         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1112         if (type != ARPOP_REQUEST)
1113                 goto out;
1114 
1115         hw_src = batadv_arp_hw_src(skb, hdr_size);
1116         ip_src = batadv_arp_ip_src(skb, hdr_size);
1117         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1118 
1119         batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REQUEST");
1120 
1121         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1122 
1123         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1124         if (!dat_entry)
1125                 goto out;
1126 
1127         skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
1128                                               dat_entry->mac_addr, hw_src, vid);
1129         if (!skb_new)
1130                 goto out;
1131 
1132         /* To preserve backwards compatibility, the node has choose the outgoing
1133          * format based on the incoming request packet type. The assumption is
1134          * that a node not using the 4addr packet format doesn't support it.
1135          */
1136         if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))
1137                 err = batadv_send_skb_via_tt_4addr(bat_priv, skb_new,
1138                                                    BATADV_P_DAT_CACHE_REPLY,
1139                                                    NULL, vid);
1140         else
1141                 err = batadv_send_skb_via_tt(bat_priv, skb_new, NULL, vid);
1142 
1143         if (err != NET_XMIT_DROP) {
1144                 batadv_inc_counter(bat_priv, BATADV_CNT_DAT_CACHED_REPLY_TX);
1145                 ret = true;
1146         }
1147 out:
1148         if (dat_entry)
1149                 batadv_dat_entry_put(dat_entry);
1150         if (ret)
1151                 kfree_skb(skb);
1152         return ret;
1153 }
1154 
1155 /**
1156  * batadv_dat_snoop_outgoing_arp_reply - snoop the ARP reply and fill the DHT
1157  * @bat_priv: the bat priv with all the soft interface information
1158  * @skb: packet to check
1159  */
1160 void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
1161                                          struct sk_buff *skb)
1162 {
1163         u16 type;
1164         __be32 ip_src, ip_dst;
1165         u8 *hw_src, *hw_dst;
1166         int hdr_size = 0;
1167         unsigned short vid;
1168 
1169         if (!atomic_read(&bat_priv->distributed_arp_table))
1170                 return;
1171 
1172         vid = batadv_dat_get_vid(skb, &hdr_size);
1173 
1174         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1175         if (type != ARPOP_REPLY)
1176                 return;
1177 
1178         batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REPLY");
1179 
1180         hw_src = batadv_arp_hw_src(skb, hdr_size);
1181         ip_src = batadv_arp_ip_src(skb, hdr_size);
1182         hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1183         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1184 
1185         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1186         batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1187 
1188         /* Send the ARP reply to the candidates for both the IP addresses that
1189          * the node obtained from the ARP reply
1190          */
1191         batadv_dat_send_data(bat_priv, skb, ip_src, vid, BATADV_P_DAT_DHT_PUT);
1192         batadv_dat_send_data(bat_priv, skb, ip_dst, vid, BATADV_P_DAT_DHT_PUT);
1193 }
1194 
1195 /**
1196  * batadv_dat_snoop_incoming_arp_reply - snoop the ARP reply and fill the local
1197  * DAT storage only
1198  * @bat_priv: the bat priv with all the soft interface information
1199  * @skb: packet to check
1200  * @hdr_size: size of the encapsulation header
1201  *
1202  * Return: true if the packet was snooped and consumed by DAT. False if the
1203  * packet has to be delivered to the interface
1204  */
1205 bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
1206                                          struct sk_buff *skb, int hdr_size)
1207 {
1208         struct batadv_dat_entry *dat_entry = NULL;
1209         u16 type;
1210         __be32 ip_src, ip_dst;
1211         u8 *hw_src, *hw_dst;
1212         bool dropped = false;
1213         unsigned short vid;
1214 
1215         if (!atomic_read(&bat_priv->distributed_arp_table))
1216                 goto out;
1217 
1218         vid = batadv_dat_get_vid(skb, &hdr_size);
1219 
1220         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1221         if (type != ARPOP_REPLY)
1222                 goto out;
1223 
1224         batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REPLY");
1225 
1226         hw_src = batadv_arp_hw_src(skb, hdr_size);
1227         ip_src = batadv_arp_ip_src(skb, hdr_size);
1228         hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1229         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1230 
1231         /* If ip_dst is already in cache and has the right mac address,
1232          * drop this frame if this ARP reply is destined for us because it's
1233          * most probably an ARP reply generated by another node of the DHT.
1234          * We have most probably received already a reply earlier. Delivering
1235          * this frame would lead to doubled receive of an ARP reply.
1236          */
1237         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_src, vid);
1238         if (dat_entry && batadv_compare_eth(hw_src, dat_entry->mac_addr)) {
1239                 batadv_dbg(BATADV_DBG_DAT, bat_priv, "Doubled ARP reply removed: ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]; dat_entry: %pM-%pI4\n",
1240                            hw_src, &ip_src, hw_dst, &ip_dst,
1241                            dat_entry->mac_addr, &dat_entry->ip);
1242                 dropped = true;
1243                 goto out;
1244         }
1245 
1246         /* Update our internal cache with both the IP addresses the node got
1247          * within the ARP reply
1248          */
1249         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1250         batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1251 
1252         /* If BLA is enabled, only forward ARP replies if we have claimed the
1253          * source of the ARP reply or if no one else of the same backbone has
1254          * already claimed that client. This prevents that different gateways
1255          * to the same backbone all forward the ARP reply leading to multiple
1256          * replies in the backbone.
1257          */
1258         if (!batadv_bla_check_claim(bat_priv, hw_src, vid)) {
1259                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1260                            "Device %pM claimed by another backbone gw. Drop ARP reply.\n",
1261                            hw_src);
1262                 dropped = true;
1263                 goto out;
1264         }
1265 
1266         /* if this REPLY is directed to a client of mine, let's deliver the
1267          * packet to the interface
1268          */
1269         dropped = !batadv_is_my_client(bat_priv, hw_dst, vid);
1270 
1271         /* if this REPLY is sent on behalf of a client of mine, let's drop the
1272          * packet because the client will reply by itself
1273          */
1274         dropped |= batadv_is_my_client(bat_priv, hw_src, vid);
1275 out:
1276         if (dropped)
1277                 kfree_skb(skb);
1278         if (dat_entry)
1279                 batadv_dat_entry_put(dat_entry);
1280         /* if dropped == false -> deliver to the interface */
1281         return dropped;
1282 }
1283 
1284 /**
1285  * batadv_dat_drop_broadcast_packet - check if an ARP request has to be dropped
1286  * (because the node has already obtained the reply via DAT) or not
1287  * @bat_priv: the bat priv with all the soft interface information
1288  * @forw_packet: the broadcast packet
1289  *
1290  * Return: true if the node can drop the packet, false otherwise.
1291  */
1292 bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
1293                                       struct batadv_forw_packet *forw_packet)
1294 {
1295         u16 type;
1296         __be32 ip_dst;
1297         struct batadv_dat_entry *dat_entry = NULL;
1298         bool ret = false;
1299         int hdr_size = sizeof(struct batadv_bcast_packet);
1300         unsigned short vid;
1301 
1302         if (!atomic_read(&bat_priv->distributed_arp_table))
1303                 goto out;
1304 
1305         /* If this packet is an ARP_REQUEST and the node already has the
1306          * information that it is going to ask, then the packet can be dropped
1307          */
1308         if (batadv_forw_packet_is_rebroadcast(forw_packet))
1309                 goto out;
1310 
1311         vid = batadv_dat_get_vid(forw_packet->skb, &hdr_size);
1312 
1313         type = batadv_arp_get_type(bat_priv, forw_packet->skb, hdr_size);
1314         if (type != ARPOP_REQUEST)
1315                 goto out;
1316 
1317         ip_dst = batadv_arp_ip_dst(forw_packet->skb, hdr_size);
1318         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1319         /* check if the node already got this entry */
1320         if (!dat_entry) {
1321                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1322                            "ARP Request for %pI4: fallback\n", &ip_dst);
1323                 goto out;
1324         }
1325 
1326         batadv_dbg(BATADV_DBG_DAT, bat_priv,
1327                    "ARP Request for %pI4: fallback prevented\n", &ip_dst);
1328         ret = true;
1329 
1330 out:
1331         if (dat_entry)
1332                 batadv_dat_entry_put(dat_entry);
1333         return ret;
1334 }
1335 

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