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Linux/net/batman-adv/distributed-arp-table.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /* Copyright (C) 2011-2018  B.A.T.M.A.N. contributors:
  3  *
  4  * Antonio Quartulli
  5  *
  6  * This program is free software; you can redistribute it and/or
  7  * modify it under the terms of version 2 of the GNU General Public
  8  * License as published by the Free Software Foundation.
  9  *
 10  * This program is distributed in the hope that it will be useful, but
 11  * WITHOUT ANY WARRANTY; without even the implied warranty of
 12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 13  * General Public License for more details.
 14  *
 15  * You should have received a copy of the GNU General Public License
 16  * along with this program; if not, see <http://www.gnu.org/licenses/>.
 17  */
 18 
 19 #include "distributed-arp-table.h"
 20 #include "main.h"
 21 
 22 #include <linux/atomic.h>
 23 #include <linux/bitops.h>
 24 #include <linux/byteorder/generic.h>
 25 #include <linux/errno.h>
 26 #include <linux/etherdevice.h>
 27 #include <linux/gfp.h>
 28 #include <linux/if_arp.h>
 29 #include <linux/if_ether.h>
 30 #include <linux/if_vlan.h>
 31 #include <linux/in.h>
 32 #include <linux/jiffies.h>
 33 #include <linux/kernel.h>
 34 #include <linux/kref.h>
 35 #include <linux/list.h>
 36 #include <linux/netlink.h>
 37 #include <linux/rculist.h>
 38 #include <linux/rcupdate.h>
 39 #include <linux/seq_file.h>
 40 #include <linux/skbuff.h>
 41 #include <linux/slab.h>
 42 #include <linux/spinlock.h>
 43 #include <linux/stddef.h>
 44 #include <linux/string.h>
 45 #include <linux/workqueue.h>
 46 #include <net/arp.h>
 47 #include <net/genetlink.h>
 48 #include <net/netlink.h>
 49 #include <net/sock.h>
 50 #include <uapi/linux/batman_adv.h>
 51 
 52 #include "bridge_loop_avoidance.h"
 53 #include "hard-interface.h"
 54 #include "hash.h"
 55 #include "log.h"
 56 #include "netlink.h"
 57 #include "originator.h"
 58 #include "send.h"
 59 #include "soft-interface.h"
 60 #include "translation-table.h"
 61 #include "tvlv.h"
 62 
 63 static void batadv_dat_purge(struct work_struct *work);
 64 
 65 /**
 66  * batadv_dat_start_timer() - initialise the DAT periodic worker
 67  * @bat_priv: the bat priv with all the soft interface information
 68  */
 69 static void batadv_dat_start_timer(struct batadv_priv *bat_priv)
 70 {
 71         INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge);
 72         queue_delayed_work(batadv_event_workqueue, &bat_priv->dat.work,
 73                            msecs_to_jiffies(10000));
 74 }
 75 
 76 /**
 77  * batadv_dat_entry_release() - release dat_entry from lists and queue for free
 78  *  after rcu grace period
 79  * @ref: kref pointer of the dat_entry
 80  */
 81 static void batadv_dat_entry_release(struct kref *ref)
 82 {
 83         struct batadv_dat_entry *dat_entry;
 84 
 85         dat_entry = container_of(ref, struct batadv_dat_entry, refcount);
 86 
 87         kfree_rcu(dat_entry, rcu);
 88 }
 89 
 90 /**
 91  * batadv_dat_entry_put() - decrement the dat_entry refcounter and possibly
 92  *  release it
 93  * @dat_entry: dat_entry to be free'd
 94  */
 95 static void batadv_dat_entry_put(struct batadv_dat_entry *dat_entry)
 96 {
 97         kref_put(&dat_entry->refcount, batadv_dat_entry_release);
 98 }
 99 
100 /**
101  * batadv_dat_to_purge() - check whether a dat_entry has to be purged or not
102  * @dat_entry: the entry to check
103  *
104  * Return: true if the entry has to be purged now, false otherwise.
105  */
106 static bool batadv_dat_to_purge(struct batadv_dat_entry *dat_entry)
107 {
108         return batadv_has_timed_out(dat_entry->last_update,
109                                     BATADV_DAT_ENTRY_TIMEOUT);
110 }
111 
112 /**
113  * __batadv_dat_purge() - delete entries from the DAT local storage
114  * @bat_priv: the bat priv with all the soft interface information
115  * @to_purge: function in charge to decide whether an entry has to be purged or
116  *            not. This function takes the dat_entry as argument and has to
117  *            returns a boolean value: true is the entry has to be deleted,
118  *            false otherwise
119  *
120  * Loops over each entry in the DAT local storage and deletes it if and only if
121  * the to_purge function passed as argument returns true.
122  */
123 static void __batadv_dat_purge(struct batadv_priv *bat_priv,
124                                bool (*to_purge)(struct batadv_dat_entry *))
125 {
126         spinlock_t *list_lock; /* protects write access to the hash lists */
127         struct batadv_dat_entry *dat_entry;
128         struct hlist_node *node_tmp;
129         struct hlist_head *head;
130         u32 i;
131 
132         if (!bat_priv->dat.hash)
133                 return;
134 
135         for (i = 0; i < bat_priv->dat.hash->size; i++) {
136                 head = &bat_priv->dat.hash->table[i];
137                 list_lock = &bat_priv->dat.hash->list_locks[i];
138 
139                 spin_lock_bh(list_lock);
140                 hlist_for_each_entry_safe(dat_entry, node_tmp, head,
141                                           hash_entry) {
142                         /* if a helper function has been passed as parameter,
143                          * ask it if the entry has to be purged or not
144                          */
145                         if (to_purge && !to_purge(dat_entry))
146                                 continue;
147 
148                         hlist_del_rcu(&dat_entry->hash_entry);
149                         batadv_dat_entry_put(dat_entry);
150                 }
151                 spin_unlock_bh(list_lock);
152         }
153 }
154 
155 /**
156  * batadv_dat_purge() - periodic task that deletes old entries from the local
157  *  DAT hash table
158  * @work: kernel work struct
159  */
160 static void batadv_dat_purge(struct work_struct *work)
161 {
162         struct delayed_work *delayed_work;
163         struct batadv_priv_dat *priv_dat;
164         struct batadv_priv *bat_priv;
165 
166         delayed_work = to_delayed_work(work);
167         priv_dat = container_of(delayed_work, struct batadv_priv_dat, work);
168         bat_priv = container_of(priv_dat, struct batadv_priv, dat);
169 
170         __batadv_dat_purge(bat_priv, batadv_dat_to_purge);
171         batadv_dat_start_timer(bat_priv);
172 }
173 
174 /**
175  * batadv_compare_dat() - comparing function used in the local DAT hash table
176  * @node: node in the local table
177  * @data2: second object to compare the node to
178  *
179  * Return: true if the two entries are the same, false otherwise.
180  */
181 static bool batadv_compare_dat(const struct hlist_node *node, const void *data2)
182 {
183         const void *data1 = container_of(node, struct batadv_dat_entry,
184                                          hash_entry);
185 
186         return memcmp(data1, data2, sizeof(__be32)) == 0;
187 }
188 
189 /**
190  * batadv_arp_hw_src() - extract the hw_src field from an ARP packet
191  * @skb: ARP packet
192  * @hdr_size: size of the possible header before the ARP packet
193  *
194  * Return: the value of the hw_src field in the ARP packet.
195  */
196 static u8 *batadv_arp_hw_src(struct sk_buff *skb, int hdr_size)
197 {
198         u8 *addr;
199 
200         addr = (u8 *)(skb->data + hdr_size);
201         addr += ETH_HLEN + sizeof(struct arphdr);
202 
203         return addr;
204 }
205 
206 /**
207  * batadv_arp_ip_src() - extract the ip_src field from an ARP packet
208  * @skb: ARP packet
209  * @hdr_size: size of the possible header before the ARP packet
210  *
211  * Return: the value of the ip_src field in the ARP packet.
212  */
213 static __be32 batadv_arp_ip_src(struct sk_buff *skb, int hdr_size)
214 {
215         return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN);
216 }
217 
218 /**
219  * batadv_arp_hw_dst() - extract the hw_dst field from an ARP packet
220  * @skb: ARP packet
221  * @hdr_size: size of the possible header before the ARP packet
222  *
223  * Return: the value of the hw_dst field in the ARP packet.
224  */
225 static u8 *batadv_arp_hw_dst(struct sk_buff *skb, int hdr_size)
226 {
227         return batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN + 4;
228 }
229 
230 /**
231  * batadv_arp_ip_dst() - extract the ip_dst field from an ARP packet
232  * @skb: ARP packet
233  * @hdr_size: size of the possible header before the ARP packet
234  *
235  * Return: the value of the ip_dst field in the ARP packet.
236  */
237 static __be32 batadv_arp_ip_dst(struct sk_buff *skb, int hdr_size)
238 {
239         return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4);
240 }
241 
242 /**
243  * batadv_hash_dat() - compute the hash value for an IP address
244  * @data: data to hash
245  * @size: size of the hash table
246  *
247  * Return: the selected index in the hash table for the given data.
248  */
249 static u32 batadv_hash_dat(const void *data, u32 size)
250 {
251         u32 hash = 0;
252         const struct batadv_dat_entry *dat = data;
253         const unsigned char *key;
254         u32 i;
255 
256         key = (const unsigned char *)&dat->ip;
257         for (i = 0; i < sizeof(dat->ip); i++) {
258                 hash += key[i];
259                 hash += (hash << 10);
260                 hash ^= (hash >> 6);
261         }
262 
263         key = (const unsigned char *)&dat->vid;
264         for (i = 0; i < sizeof(dat->vid); i++) {
265                 hash += key[i];
266                 hash += (hash << 10);
267                 hash ^= (hash >> 6);
268         }
269 
270         hash += (hash << 3);
271         hash ^= (hash >> 11);
272         hash += (hash << 15);
273 
274         return hash % size;
275 }
276 
277 /**
278  * batadv_dat_entry_hash_find() - look for a given dat_entry in the local hash
279  * table
280  * @bat_priv: the bat priv with all the soft interface information
281  * @ip: search key
282  * @vid: VLAN identifier
283  *
284  * Return: the dat_entry if found, NULL otherwise.
285  */
286 static struct batadv_dat_entry *
287 batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
288                            unsigned short vid)
289 {
290         struct hlist_head *head;
291         struct batadv_dat_entry to_find, *dat_entry, *dat_entry_tmp = NULL;
292         struct batadv_hashtable *hash = bat_priv->dat.hash;
293         u32 index;
294 
295         if (!hash)
296                 return NULL;
297 
298         to_find.ip = ip;
299         to_find.vid = vid;
300 
301         index = batadv_hash_dat(&to_find, hash->size);
302         head = &hash->table[index];
303 
304         rcu_read_lock();
305         hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
306                 if (dat_entry->ip != ip)
307                         continue;
308 
309                 if (!kref_get_unless_zero(&dat_entry->refcount))
310                         continue;
311 
312                 dat_entry_tmp = dat_entry;
313                 break;
314         }
315         rcu_read_unlock();
316 
317         return dat_entry_tmp;
318 }
319 
320 /**
321  * batadv_dat_entry_add() - add a new dat entry or update it if already exists
322  * @bat_priv: the bat priv with all the soft interface information
323  * @ip: ipv4 to add/edit
324  * @mac_addr: mac address to assign to the given ipv4
325  * @vid: VLAN identifier
326  */
327 static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
328                                  u8 *mac_addr, unsigned short vid)
329 {
330         struct batadv_dat_entry *dat_entry;
331         int hash_added;
332 
333         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip, vid);
334         /* if this entry is already known, just update it */
335         if (dat_entry) {
336                 if (!batadv_compare_eth(dat_entry->mac_addr, mac_addr))
337                         ether_addr_copy(dat_entry->mac_addr, mac_addr);
338                 dat_entry->last_update = jiffies;
339                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
340                            "Entry updated: %pI4 %pM (vid: %d)\n",
341                            &dat_entry->ip, dat_entry->mac_addr,
342                            batadv_print_vid(vid));
343                 goto out;
344         }
345 
346         dat_entry = kmalloc(sizeof(*dat_entry), GFP_ATOMIC);
347         if (!dat_entry)
348                 goto out;
349 
350         dat_entry->ip = ip;
351         dat_entry->vid = vid;
352         ether_addr_copy(dat_entry->mac_addr, mac_addr);
353         dat_entry->last_update = jiffies;
354         kref_init(&dat_entry->refcount);
355 
356         kref_get(&dat_entry->refcount);
357         hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
358                                      batadv_hash_dat, dat_entry,
359                                      &dat_entry->hash_entry);
360 
361         if (unlikely(hash_added != 0)) {
362                 /* remove the reference for the hash */
363                 batadv_dat_entry_put(dat_entry);
364                 goto out;
365         }
366 
367         batadv_dbg(BATADV_DBG_DAT, bat_priv, "New entry added: %pI4 %pM (vid: %d)\n",
368                    &dat_entry->ip, dat_entry->mac_addr, batadv_print_vid(vid));
369 
370 out:
371         if (dat_entry)
372                 batadv_dat_entry_put(dat_entry);
373 }
374 
375 #ifdef CONFIG_BATMAN_ADV_DEBUG
376 
377 /**
378  * batadv_dbg_arp() - print a debug message containing all the ARP packet
379  *  details
380  * @bat_priv: the bat priv with all the soft interface information
381  * @skb: ARP packet
382  * @hdr_size: size of the possible header before the ARP packet
383  * @msg: message to print together with the debugging information
384  */
385 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
386                            int hdr_size, char *msg)
387 {
388         struct batadv_unicast_4addr_packet *unicast_4addr_packet;
389         struct batadv_bcast_packet *bcast_pkt;
390         u8 *orig_addr;
391         __be32 ip_src, ip_dst;
392 
393         if (msg)
394                 batadv_dbg(BATADV_DBG_DAT, bat_priv, "%s\n", msg);
395 
396         ip_src = batadv_arp_ip_src(skb, hdr_size);
397         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
398         batadv_dbg(BATADV_DBG_DAT, bat_priv,
399                    "ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]\n",
400                    batadv_arp_hw_src(skb, hdr_size), &ip_src,
401                    batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
402 
403         if (hdr_size < sizeof(struct batadv_unicast_packet))
404                 return;
405 
406         unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
407 
408         switch (unicast_4addr_packet->u.packet_type) {
409         case BATADV_UNICAST:
410                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
411                            "* encapsulated within a UNICAST packet\n");
412                 break;
413         case BATADV_UNICAST_4ADDR:
414                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
415                            "* encapsulated within a UNICAST_4ADDR packet (src: %pM)\n",
416                            unicast_4addr_packet->src);
417                 switch (unicast_4addr_packet->subtype) {
418                 case BATADV_P_DAT_DHT_PUT:
419                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_PUT\n");
420                         break;
421                 case BATADV_P_DAT_DHT_GET:
422                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_GET\n");
423                         break;
424                 case BATADV_P_DAT_CACHE_REPLY:
425                         batadv_dbg(BATADV_DBG_DAT, bat_priv,
426                                    "* type: DAT_CACHE_REPLY\n");
427                         break;
428                 case BATADV_P_DATA:
429                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DATA\n");
430                         break;
431                 default:
432                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: Unknown (%u)!\n",
433                                    unicast_4addr_packet->u.packet_type);
434                 }
435                 break;
436         case BATADV_BCAST:
437                 bcast_pkt = (struct batadv_bcast_packet *)unicast_4addr_packet;
438                 orig_addr = bcast_pkt->orig;
439                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
440                            "* encapsulated within a BCAST packet (src: %pM)\n",
441                            orig_addr);
442                 break;
443         default:
444                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
445                            "* encapsulated within an unknown packet type (0x%x)\n",
446                            unicast_4addr_packet->u.packet_type);
447         }
448 }
449 
450 #else
451 
452 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
453                            int hdr_size, char *msg)
454 {
455 }
456 
457 #endif /* CONFIG_BATMAN_ADV_DEBUG */
458 
459 /**
460  * batadv_is_orig_node_eligible() - check whether a node can be a DHT candidate
461  * @res: the array with the already selected candidates
462  * @select: number of already selected candidates
463  * @tmp_max: address of the currently evaluated node
464  * @max: current round max address
465  * @last_max: address of the last selected candidate
466  * @candidate: orig_node under evaluation
467  * @max_orig_node: last selected candidate
468  *
469  * Return: true if the node has been elected as next candidate or false
470  * otherwise.
471  */
472 static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
473                                          int select, batadv_dat_addr_t tmp_max,
474                                          batadv_dat_addr_t max,
475                                          batadv_dat_addr_t last_max,
476                                          struct batadv_orig_node *candidate,
477                                          struct batadv_orig_node *max_orig_node)
478 {
479         bool ret = false;
480         int j;
481 
482         /* check if orig node candidate is running DAT */
483         if (!test_bit(BATADV_ORIG_CAPA_HAS_DAT, &candidate->capabilities))
484                 goto out;
485 
486         /* Check if this node has already been selected... */
487         for (j = 0; j < select; j++)
488                 if (res[j].orig_node == candidate)
489                         break;
490         /* ..and possibly skip it */
491         if (j < select)
492                 goto out;
493         /* sanity check: has it already been selected? This should not happen */
494         if (tmp_max > last_max)
495                 goto out;
496         /* check if during this iteration an originator with a closer dht
497          * address has already been found
498          */
499         if (tmp_max < max)
500                 goto out;
501         /* this is an hash collision with the temporary selected node. Choose
502          * the one with the lowest address
503          */
504         if (tmp_max == max && max_orig_node &&
505             batadv_compare_eth(candidate->orig, max_orig_node->orig))
506                 goto out;
507 
508         ret = true;
509 out:
510         return ret;
511 }
512 
513 /**
514  * batadv_choose_next_candidate() - select the next DHT candidate
515  * @bat_priv: the bat priv with all the soft interface information
516  * @cands: candidates array
517  * @select: number of candidates already present in the array
518  * @ip_key: key to look up in the DHT
519  * @last_max: pointer where the address of the selected candidate will be saved
520  */
521 static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
522                                          struct batadv_dat_candidate *cands,
523                                          int select, batadv_dat_addr_t ip_key,
524                                          batadv_dat_addr_t *last_max)
525 {
526         batadv_dat_addr_t max = 0;
527         batadv_dat_addr_t tmp_max = 0;
528         struct batadv_orig_node *orig_node, *max_orig_node = NULL;
529         struct batadv_hashtable *hash = bat_priv->orig_hash;
530         struct hlist_head *head;
531         int i;
532 
533         /* if no node is eligible as candidate, leave the candidate type as
534          * NOT_FOUND
535          */
536         cands[select].type = BATADV_DAT_CANDIDATE_NOT_FOUND;
537 
538         /* iterate over the originator list and find the node with the closest
539          * dat_address which has not been selected yet
540          */
541         for (i = 0; i < hash->size; i++) {
542                 head = &hash->table[i];
543 
544                 rcu_read_lock();
545                 hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
546                         /* the dht space is a ring using unsigned addresses */
547                         tmp_max = BATADV_DAT_ADDR_MAX - orig_node->dat_addr +
548                                   ip_key;
549 
550                         if (!batadv_is_orig_node_eligible(cands, select,
551                                                           tmp_max, max,
552                                                           *last_max, orig_node,
553                                                           max_orig_node))
554                                 continue;
555 
556                         if (!kref_get_unless_zero(&orig_node->refcount))
557                                 continue;
558 
559                         max = tmp_max;
560                         if (max_orig_node)
561                                 batadv_orig_node_put(max_orig_node);
562                         max_orig_node = orig_node;
563                 }
564                 rcu_read_unlock();
565         }
566         if (max_orig_node) {
567                 cands[select].type = BATADV_DAT_CANDIDATE_ORIG;
568                 cands[select].orig_node = max_orig_node;
569                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
570                            "dat_select_candidates() %d: selected %pM addr=%u dist=%u\n",
571                            select, max_orig_node->orig, max_orig_node->dat_addr,
572                            max);
573         }
574         *last_max = max;
575 }
576 
577 /**
578  * batadv_dat_select_candidates() - select the nodes which the DHT message has
579  *  to be sent to
580  * @bat_priv: the bat priv with all the soft interface information
581  * @ip_dst: ipv4 to look up in the DHT
582  * @vid: VLAN identifier
583  *
584  * An originator O is selected if and only if its DHT_ID value is one of three
585  * closest values (from the LEFT, with wrap around if needed) then the hash
586  * value of the key. ip_dst is the key.
587  *
588  * Return: the candidate array of size BATADV_DAT_CANDIDATE_NUM.
589  */
590 static struct batadv_dat_candidate *
591 batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst,
592                              unsigned short vid)
593 {
594         int select;
595         batadv_dat_addr_t last_max = BATADV_DAT_ADDR_MAX, ip_key;
596         struct batadv_dat_candidate *res;
597         struct batadv_dat_entry dat;
598 
599         if (!bat_priv->orig_hash)
600                 return NULL;
601 
602         res = kmalloc_array(BATADV_DAT_CANDIDATES_NUM, sizeof(*res),
603                             GFP_ATOMIC);
604         if (!res)
605                 return NULL;
606 
607         dat.ip = ip_dst;
608         dat.vid = vid;
609         ip_key = (batadv_dat_addr_t)batadv_hash_dat(&dat,
610                                                     BATADV_DAT_ADDR_MAX);
611 
612         batadv_dbg(BATADV_DBG_DAT, bat_priv,
613                    "%s(): IP=%pI4 hash(IP)=%u\n", __func__, &ip_dst,
614                    ip_key);
615 
616         for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
617                 batadv_choose_next_candidate(bat_priv, res, select, ip_key,
618                                              &last_max);
619 
620         return res;
621 }
622 
623 /**
624  * batadv_dat_send_data() - send a payload to the selected candidates
625  * @bat_priv: the bat priv with all the soft interface information
626  * @skb: payload to send
627  * @ip: the DHT key
628  * @vid: VLAN identifier
629  * @packet_subtype: unicast4addr packet subtype to use
630  *
631  * This function copies the skb with pskb_copy() and is sent as unicast packet
632  * to each of the selected candidates.
633  *
634  * Return: true if the packet is sent to at least one candidate, false
635  * otherwise.
636  */
637 static bool batadv_dat_send_data(struct batadv_priv *bat_priv,
638                                  struct sk_buff *skb, __be32 ip,
639                                  unsigned short vid, int packet_subtype)
640 {
641         int i;
642         bool ret = false;
643         int send_status;
644         struct batadv_neigh_node *neigh_node = NULL;
645         struct sk_buff *tmp_skb;
646         struct batadv_dat_candidate *cand;
647 
648         cand = batadv_dat_select_candidates(bat_priv, ip, vid);
649         if (!cand)
650                 goto out;
651 
652         batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
653 
654         for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
655                 if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
656                         continue;
657 
658                 neigh_node = batadv_orig_router_get(cand[i].orig_node,
659                                                     BATADV_IF_DEFAULT);
660                 if (!neigh_node)
661                         goto free_orig;
662 
663                 tmp_skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
664                 if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, tmp_skb,
665                                                            cand[i].orig_node,
666                                                            packet_subtype)) {
667                         kfree_skb(tmp_skb);
668                         goto free_neigh;
669                 }
670 
671                 send_status = batadv_send_unicast_skb(tmp_skb, neigh_node);
672                 if (send_status == NET_XMIT_SUCCESS) {
673                         /* count the sent packet */
674                         switch (packet_subtype) {
675                         case BATADV_P_DAT_DHT_GET:
676                                 batadv_inc_counter(bat_priv,
677                                                    BATADV_CNT_DAT_GET_TX);
678                                 break;
679                         case BATADV_P_DAT_DHT_PUT:
680                                 batadv_inc_counter(bat_priv,
681                                                    BATADV_CNT_DAT_PUT_TX);
682                                 break;
683                         }
684 
685                         /* packet sent to a candidate: return true */
686                         ret = true;
687                 }
688 free_neigh:
689                 batadv_neigh_node_put(neigh_node);
690 free_orig:
691                 batadv_orig_node_put(cand[i].orig_node);
692         }
693 
694 out:
695         kfree(cand);
696         return ret;
697 }
698 
699 /**
700  * batadv_dat_tvlv_container_update() - update the dat tvlv container after dat
701  *  setting change
702  * @bat_priv: the bat priv with all the soft interface information
703  */
704 static void batadv_dat_tvlv_container_update(struct batadv_priv *bat_priv)
705 {
706         char dat_mode;
707 
708         dat_mode = atomic_read(&bat_priv->distributed_arp_table);
709 
710         switch (dat_mode) {
711         case 0:
712                 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
713                 break;
714         case 1:
715                 batadv_tvlv_container_register(bat_priv, BATADV_TVLV_DAT, 1,
716                                                NULL, 0);
717                 break;
718         }
719 }
720 
721 /**
722  * batadv_dat_status_update() - update the dat tvlv container after dat
723  *  setting change
724  * @net_dev: the soft interface net device
725  */
726 void batadv_dat_status_update(struct net_device *net_dev)
727 {
728         struct batadv_priv *bat_priv = netdev_priv(net_dev);
729 
730         batadv_dat_tvlv_container_update(bat_priv);
731 }
732 
733 /**
734  * batadv_dat_tvlv_ogm_handler_v1() - process incoming dat tvlv container
735  * @bat_priv: the bat priv with all the soft interface information
736  * @orig: the orig_node of the ogm
737  * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
738  * @tvlv_value: tvlv buffer containing the gateway data
739  * @tvlv_value_len: tvlv buffer length
740  */
741 static void batadv_dat_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
742                                            struct batadv_orig_node *orig,
743                                            u8 flags,
744                                            void *tvlv_value, u16 tvlv_value_len)
745 {
746         if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
747                 clear_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
748         else
749                 set_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
750 }
751 
752 /**
753  * batadv_dat_hash_free() - free the local DAT hash table
754  * @bat_priv: the bat priv with all the soft interface information
755  */
756 static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
757 {
758         if (!bat_priv->dat.hash)
759                 return;
760 
761         __batadv_dat_purge(bat_priv, NULL);
762 
763         batadv_hash_destroy(bat_priv->dat.hash);
764 
765         bat_priv->dat.hash = NULL;
766 }
767 
768 /**
769  * batadv_dat_init() - initialise the DAT internals
770  * @bat_priv: the bat priv with all the soft interface information
771  *
772  * Return: 0 in case of success, a negative error code otherwise
773  */
774 int batadv_dat_init(struct batadv_priv *bat_priv)
775 {
776         if (bat_priv->dat.hash)
777                 return 0;
778 
779         bat_priv->dat.hash = batadv_hash_new(1024);
780 
781         if (!bat_priv->dat.hash)
782                 return -ENOMEM;
783 
784         batadv_dat_start_timer(bat_priv);
785 
786         batadv_tvlv_handler_register(bat_priv, batadv_dat_tvlv_ogm_handler_v1,
787                                      NULL, BATADV_TVLV_DAT, 1,
788                                      BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
789         batadv_dat_tvlv_container_update(bat_priv);
790         return 0;
791 }
792 
793 /**
794  * batadv_dat_free() - free the DAT internals
795  * @bat_priv: the bat priv with all the soft interface information
796  */
797 void batadv_dat_free(struct batadv_priv *bat_priv)
798 {
799         batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
800         batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_DAT, 1);
801 
802         cancel_delayed_work_sync(&bat_priv->dat.work);
803 
804         batadv_dat_hash_free(bat_priv);
805 }
806 
807 #ifdef CONFIG_BATMAN_ADV_DEBUGFS
808 /**
809  * batadv_dat_cache_seq_print_text() - print the local DAT hash table
810  * @seq: seq file to print on
811  * @offset: not used
812  *
813  * Return: always 0
814  */
815 int batadv_dat_cache_seq_print_text(struct seq_file *seq, void *offset)
816 {
817         struct net_device *net_dev = (struct net_device *)seq->private;
818         struct batadv_priv *bat_priv = netdev_priv(net_dev);
819         struct batadv_hashtable *hash = bat_priv->dat.hash;
820         struct batadv_dat_entry *dat_entry;
821         struct batadv_hard_iface *primary_if;
822         struct hlist_head *head;
823         unsigned long last_seen_jiffies;
824         int last_seen_msecs, last_seen_secs, last_seen_mins;
825         u32 i;
826 
827         primary_if = batadv_seq_print_text_primary_if_get(seq);
828         if (!primary_if)
829                 goto out;
830 
831         seq_printf(seq, "Distributed ARP Table (%s):\n", net_dev->name);
832         seq_puts(seq,
833                  "          IPv4             MAC        VID   last-seen\n");
834 
835         for (i = 0; i < hash->size; i++) {
836                 head = &hash->table[i];
837 
838                 rcu_read_lock();
839                 hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
840                         last_seen_jiffies = jiffies - dat_entry->last_update;
841                         last_seen_msecs = jiffies_to_msecs(last_seen_jiffies);
842                         last_seen_mins = last_seen_msecs / 60000;
843                         last_seen_msecs = last_seen_msecs % 60000;
844                         last_seen_secs = last_seen_msecs / 1000;
845 
846                         seq_printf(seq, " * %15pI4 %pM %4i %6i:%02i\n",
847                                    &dat_entry->ip, dat_entry->mac_addr,
848                                    batadv_print_vid(dat_entry->vid),
849                                    last_seen_mins, last_seen_secs);
850                 }
851                 rcu_read_unlock();
852         }
853 
854 out:
855         if (primary_if)
856                 batadv_hardif_put(primary_if);
857         return 0;
858 }
859 #endif
860 
861 /**
862  * batadv_dat_cache_dump_entry() - dump one entry of the DAT cache table to a
863  *  netlink socket
864  * @msg: buffer for the message
865  * @portid: netlink port
866  * @seq: Sequence number of netlink message
867  * @dat_entry: entry to dump
868  *
869  * Return: 0 or error code.
870  */
871 static int
872 batadv_dat_cache_dump_entry(struct sk_buff *msg, u32 portid, u32 seq,
873                             struct batadv_dat_entry *dat_entry)
874 {
875         int msecs;
876         void *hdr;
877 
878         hdr = genlmsg_put(msg, portid, seq, &batadv_netlink_family,
879                           NLM_F_MULTI, BATADV_CMD_GET_DAT_CACHE);
880         if (!hdr)
881                 return -ENOBUFS;
882 
883         msecs = jiffies_to_msecs(jiffies - dat_entry->last_update);
884 
885         if (nla_put_in_addr(msg, BATADV_ATTR_DAT_CACHE_IP4ADDRESS,
886                             dat_entry->ip) ||
887             nla_put(msg, BATADV_ATTR_DAT_CACHE_HWADDRESS, ETH_ALEN,
888                     dat_entry->mac_addr) ||
889             nla_put_u16(msg, BATADV_ATTR_DAT_CACHE_VID, dat_entry->vid) ||
890             nla_put_u32(msg, BATADV_ATTR_LAST_SEEN_MSECS, msecs)) {
891                 genlmsg_cancel(msg, hdr);
892                 return -EMSGSIZE;
893         }
894 
895         genlmsg_end(msg, hdr);
896         return 0;
897 }
898 
899 /**
900  * batadv_dat_cache_dump_bucket() - dump one bucket of the DAT cache table to
901  *  a netlink socket
902  * @msg: buffer for the message
903  * @portid: netlink port
904  * @seq: Sequence number of netlink message
905  * @head: bucket to dump
906  * @idx_skip: How many entries to skip
907  *
908  * Return: 0 or error code.
909  */
910 static int
911 batadv_dat_cache_dump_bucket(struct sk_buff *msg, u32 portid, u32 seq,
912                              struct hlist_head *head, int *idx_skip)
913 {
914         struct batadv_dat_entry *dat_entry;
915         int idx = 0;
916 
917         rcu_read_lock();
918         hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
919                 if (idx < *idx_skip)
920                         goto skip;
921 
922                 if (batadv_dat_cache_dump_entry(msg, portid, seq,
923                                                 dat_entry)) {
924                         rcu_read_unlock();
925                         *idx_skip = idx;
926 
927                         return -EMSGSIZE;
928                 }
929 
930 skip:
931                 idx++;
932         }
933         rcu_read_unlock();
934 
935         return 0;
936 }
937 
938 /**
939  * batadv_dat_cache_dump() - dump DAT cache table to a netlink socket
940  * @msg: buffer for the message
941  * @cb: callback structure containing arguments
942  *
943  * Return: message length.
944  */
945 int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
946 {
947         struct batadv_hard_iface *primary_if = NULL;
948         int portid = NETLINK_CB(cb->skb).portid;
949         struct net *net = sock_net(cb->skb->sk);
950         struct net_device *soft_iface;
951         struct batadv_hashtable *hash;
952         struct batadv_priv *bat_priv;
953         int bucket = cb->args[0];
954         struct hlist_head *head;
955         int idx = cb->args[1];
956         int ifindex;
957         int ret = 0;
958 
959         ifindex = batadv_netlink_get_ifindex(cb->nlh,
960                                              BATADV_ATTR_MESH_IFINDEX);
961         if (!ifindex)
962                 return -EINVAL;
963 
964         soft_iface = dev_get_by_index(net, ifindex);
965         if (!soft_iface || !batadv_softif_is_valid(soft_iface)) {
966                 ret = -ENODEV;
967                 goto out;
968         }
969 
970         bat_priv = netdev_priv(soft_iface);
971         hash = bat_priv->dat.hash;
972 
973         primary_if = batadv_primary_if_get_selected(bat_priv);
974         if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
975                 ret = -ENOENT;
976                 goto out;
977         }
978 
979         while (bucket < hash->size) {
980                 head = &hash->table[bucket];
981 
982                 if (batadv_dat_cache_dump_bucket(msg, portid,
983                                                  cb->nlh->nlmsg_seq, head,
984                                                  &idx))
985                         break;
986 
987                 bucket++;
988                 idx = 0;
989         }
990 
991         cb->args[0] = bucket;
992         cb->args[1] = idx;
993 
994         ret = msg->len;
995 
996 out:
997         if (primary_if)
998                 batadv_hardif_put(primary_if);
999 
1000         if (soft_iface)
1001                 dev_put(soft_iface);
1002 
1003         return ret;
1004 }
1005 
1006 /**
1007  * batadv_arp_get_type() - parse an ARP packet and gets the type
1008  * @bat_priv: the bat priv with all the soft interface information
1009  * @skb: packet to analyse
1010  * @hdr_size: size of the possible header before the ARP packet in the skb
1011  *
1012  * Return: the ARP type if the skb contains a valid ARP packet, 0 otherwise.
1013  */
1014 static u16 batadv_arp_get_type(struct batadv_priv *bat_priv,
1015                                struct sk_buff *skb, int hdr_size)
1016 {
1017         struct arphdr *arphdr;
1018         struct ethhdr *ethhdr;
1019         __be32 ip_src, ip_dst;
1020         u8 *hw_src, *hw_dst;
1021         u16 type = 0;
1022 
1023         /* pull the ethernet header */
1024         if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
1025                 goto out;
1026 
1027         ethhdr = (struct ethhdr *)(skb->data + hdr_size);
1028 
1029         if (ethhdr->h_proto != htons(ETH_P_ARP))
1030                 goto out;
1031 
1032         /* pull the ARP payload */
1033         if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
1034                                     arp_hdr_len(skb->dev))))
1035                 goto out;
1036 
1037         arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
1038 
1039         /* check whether the ARP packet carries a valid IP information */
1040         if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
1041                 goto out;
1042 
1043         if (arphdr->ar_pro != htons(ETH_P_IP))
1044                 goto out;
1045 
1046         if (arphdr->ar_hln != ETH_ALEN)
1047                 goto out;
1048 
1049         if (arphdr->ar_pln != 4)
1050                 goto out;
1051 
1052         /* Check for bad reply/request. If the ARP message is not sane, DAT
1053          * will simply ignore it
1054          */
1055         ip_src = batadv_arp_ip_src(skb, hdr_size);
1056         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1057         if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
1058             ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst) ||
1059             ipv4_is_zeronet(ip_src) || ipv4_is_lbcast(ip_src) ||
1060             ipv4_is_zeronet(ip_dst) || ipv4_is_lbcast(ip_dst))
1061                 goto out;
1062 
1063         hw_src = batadv_arp_hw_src(skb, hdr_size);
1064         if (is_zero_ether_addr(hw_src) || is_multicast_ether_addr(hw_src))
1065                 goto out;
1066 
1067         /* don't care about the destination MAC address in ARP requests */
1068         if (arphdr->ar_op != htons(ARPOP_REQUEST)) {
1069                 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1070                 if (is_zero_ether_addr(hw_dst) ||
1071                     is_multicast_ether_addr(hw_dst))
1072                         goto out;
1073         }
1074 
1075         type = ntohs(arphdr->ar_op);
1076 out:
1077         return type;
1078 }
1079 
1080 /**
1081  * batadv_dat_get_vid() - extract the VLAN identifier from skb if any
1082  * @skb: the buffer containing the packet to extract the VID from
1083  * @hdr_size: the size of the batman-adv header encapsulating the packet
1084  *
1085  * Return: If the packet embedded in the skb is vlan tagged this function
1086  * returns the VID with the BATADV_VLAN_HAS_TAG flag. Otherwise BATADV_NO_FLAGS
1087  * is returned.
1088  */
1089 static unsigned short batadv_dat_get_vid(struct sk_buff *skb, int *hdr_size)
1090 {
1091         unsigned short vid;
1092 
1093         vid = batadv_get_vid(skb, *hdr_size);
1094 
1095         /* ARP parsing functions jump forward of hdr_size + ETH_HLEN.
1096          * If the header contained in the packet is a VLAN one (which is longer)
1097          * hdr_size is updated so that the functions will still skip the
1098          * correct amount of bytes.
1099          */
1100         if (vid & BATADV_VLAN_HAS_TAG)
1101                 *hdr_size += VLAN_HLEN;
1102 
1103         return vid;
1104 }
1105 
1106 /**
1107  * batadv_dat_arp_create_reply() - create an ARP Reply
1108  * @bat_priv: the bat priv with all the soft interface information
1109  * @ip_src: ARP sender IP
1110  * @ip_dst: ARP target IP
1111  * @hw_src: Ethernet source and ARP sender MAC
1112  * @hw_dst: Ethernet destination and ARP target MAC
1113  * @vid: VLAN identifier (optional, set to zero otherwise)
1114  *
1115  * Creates an ARP Reply from the given values, optionally encapsulated in a
1116  * VLAN header.
1117  *
1118  * Return: An skb containing an ARP Reply.
1119  */
1120 static struct sk_buff *
1121 batadv_dat_arp_create_reply(struct batadv_priv *bat_priv, __be32 ip_src,
1122                             __be32 ip_dst, u8 *hw_src, u8 *hw_dst,
1123                             unsigned short vid)
1124 {
1125         struct sk_buff *skb;
1126 
1127         skb = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_dst, bat_priv->soft_iface,
1128                          ip_src, hw_dst, hw_src, hw_dst);
1129         if (!skb)
1130                 return NULL;
1131 
1132         skb_reset_mac_header(skb);
1133 
1134         if (vid & BATADV_VLAN_HAS_TAG)
1135                 skb = vlan_insert_tag(skb, htons(ETH_P_8021Q),
1136                                       vid & VLAN_VID_MASK);
1137 
1138         return skb;
1139 }
1140 
1141 /**
1142  * batadv_dat_snoop_outgoing_arp_request() - snoop the ARP request and try to
1143  * answer using DAT
1144  * @bat_priv: the bat priv with all the soft interface information
1145  * @skb: packet to check
1146  *
1147  * Return: true if the message has been sent to the dht candidates, false
1148  * otherwise. In case of a positive return value the message has to be enqueued
1149  * to permit the fallback.
1150  */
1151 bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
1152                                            struct sk_buff *skb)
1153 {
1154         u16 type = 0;
1155         __be32 ip_dst, ip_src;
1156         u8 *hw_src;
1157         bool ret = false;
1158         struct batadv_dat_entry *dat_entry = NULL;
1159         struct sk_buff *skb_new;
1160         struct net_device *soft_iface = bat_priv->soft_iface;
1161         int hdr_size = 0;
1162         unsigned short vid;
1163 
1164         if (!atomic_read(&bat_priv->distributed_arp_table))
1165                 goto out;
1166 
1167         vid = batadv_dat_get_vid(skb, &hdr_size);
1168 
1169         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1170         /* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast
1171          * message to the selected DHT candidates
1172          */
1173         if (type != ARPOP_REQUEST)
1174                 goto out;
1175 
1176         batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REQUEST");
1177 
1178         ip_src = batadv_arp_ip_src(skb, hdr_size);
1179         hw_src = batadv_arp_hw_src(skb, hdr_size);
1180         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1181 
1182         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1183 
1184         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1185         if (dat_entry) {
1186                 /* If the ARP request is destined for a local client the local
1187                  * client will answer itself. DAT would only generate a
1188                  * duplicate packet.
1189                  *
1190                  * Moreover, if the soft-interface is enslaved into a bridge, an
1191                  * additional DAT answer may trigger kernel warnings about
1192                  * a packet coming from the wrong port.
1193                  */
1194                 if (batadv_is_my_client(bat_priv, dat_entry->mac_addr, vid)) {
1195                         ret = true;
1196                         goto out;
1197                 }
1198 
1199                 /* If BLA is enabled, only send ARP replies if we have claimed
1200                  * the destination for the ARP request or if no one else of
1201                  * the backbone gws belonging to our backbone has claimed the
1202                  * destination.
1203                  */
1204                 if (!batadv_bla_check_claim(bat_priv,
1205                                             dat_entry->mac_addr, vid)) {
1206                         batadv_dbg(BATADV_DBG_DAT, bat_priv,
1207                                    "Device %pM claimed by another backbone gw. Don't send ARP reply!",
1208                                    dat_entry->mac_addr);
1209                         ret = true;
1210                         goto out;
1211                 }
1212 
1213                 skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
1214                                                       dat_entry->mac_addr,
1215                                                       hw_src, vid);
1216                 if (!skb_new)
1217                         goto out;
1218 
1219                 skb_new->protocol = eth_type_trans(skb_new, soft_iface);
1220 
1221                 batadv_inc_counter(bat_priv, BATADV_CNT_RX);
1222                 batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES,
1223                                    skb->len + ETH_HLEN + hdr_size);
1224 
1225                 netif_rx(skb_new);
1226                 batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
1227                 ret = true;
1228         } else {
1229                 /* Send the request to the DHT */
1230                 ret = batadv_dat_send_data(bat_priv, skb, ip_dst, vid,
1231                                            BATADV_P_DAT_DHT_GET);
1232         }
1233 out:
1234         if (dat_entry)
1235                 batadv_dat_entry_put(dat_entry);
1236         return ret;
1237 }
1238 
1239 /**
1240  * batadv_dat_snoop_incoming_arp_request() - snoop the ARP request and try to
1241  * answer using the local DAT storage
1242  * @bat_priv: the bat priv with all the soft interface information
1243  * @skb: packet to check
1244  * @hdr_size: size of the encapsulation header
1245  *
1246  * Return: true if the request has been answered, false otherwise.
1247  */
1248 bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
1249                                            struct sk_buff *skb, int hdr_size)
1250 {
1251         u16 type;
1252         __be32 ip_src, ip_dst;
1253         u8 *hw_src;
1254         struct sk_buff *skb_new;
1255         struct batadv_dat_entry *dat_entry = NULL;
1256         bool ret = false;
1257         unsigned short vid;
1258         int err;
1259 
1260         if (!atomic_read(&bat_priv->distributed_arp_table))
1261                 goto out;
1262 
1263         vid = batadv_dat_get_vid(skb, &hdr_size);
1264 
1265         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1266         if (type != ARPOP_REQUEST)
1267                 goto out;
1268 
1269         hw_src = batadv_arp_hw_src(skb, hdr_size);
1270         ip_src = batadv_arp_ip_src(skb, hdr_size);
1271         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1272 
1273         batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REQUEST");
1274 
1275         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1276 
1277         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1278         if (!dat_entry)
1279                 goto out;
1280 
1281         skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
1282                                               dat_entry->mac_addr, hw_src, vid);
1283         if (!skb_new)
1284                 goto out;
1285 
1286         /* To preserve backwards compatibility, the node has choose the outgoing
1287          * format based on the incoming request packet type. The assumption is
1288          * that a node not using the 4addr packet format doesn't support it.
1289          */
1290         if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))
1291                 err = batadv_send_skb_via_tt_4addr(bat_priv, skb_new,
1292                                                    BATADV_P_DAT_CACHE_REPLY,
1293                                                    NULL, vid);
1294         else
1295                 err = batadv_send_skb_via_tt(bat_priv, skb_new, NULL, vid);
1296 
1297         if (err != NET_XMIT_DROP) {
1298                 batadv_inc_counter(bat_priv, BATADV_CNT_DAT_CACHED_REPLY_TX);
1299                 ret = true;
1300         }
1301 out:
1302         if (dat_entry)
1303                 batadv_dat_entry_put(dat_entry);
1304         if (ret)
1305                 kfree_skb(skb);
1306         return ret;
1307 }
1308 
1309 /**
1310  * batadv_dat_snoop_outgoing_arp_reply() - snoop the ARP reply and fill the DHT
1311  * @bat_priv: the bat priv with all the soft interface information
1312  * @skb: packet to check
1313  */
1314 void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
1315                                          struct sk_buff *skb)
1316 {
1317         u16 type;
1318         __be32 ip_src, ip_dst;
1319         u8 *hw_src, *hw_dst;
1320         int hdr_size = 0;
1321         unsigned short vid;
1322 
1323         if (!atomic_read(&bat_priv->distributed_arp_table))
1324                 return;
1325 
1326         vid = batadv_dat_get_vid(skb, &hdr_size);
1327 
1328         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1329         if (type != ARPOP_REPLY)
1330                 return;
1331 
1332         batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REPLY");
1333 
1334         hw_src = batadv_arp_hw_src(skb, hdr_size);
1335         ip_src = batadv_arp_ip_src(skb, hdr_size);
1336         hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1337         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1338 
1339         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1340         batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1341 
1342         /* Send the ARP reply to the candidates for both the IP addresses that
1343          * the node obtained from the ARP reply
1344          */
1345         batadv_dat_send_data(bat_priv, skb, ip_src, vid, BATADV_P_DAT_DHT_PUT);
1346         batadv_dat_send_data(bat_priv, skb, ip_dst, vid, BATADV_P_DAT_DHT_PUT);
1347 }
1348 
1349 /**
1350  * batadv_dat_snoop_incoming_arp_reply() - snoop the ARP reply and fill the
1351  *  local DAT storage only
1352  * @bat_priv: the bat priv with all the soft interface information
1353  * @skb: packet to check
1354  * @hdr_size: size of the encapsulation header
1355  *
1356  * Return: true if the packet was snooped and consumed by DAT. False if the
1357  * packet has to be delivered to the interface
1358  */
1359 bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
1360                                          struct sk_buff *skb, int hdr_size)
1361 {
1362         struct batadv_dat_entry *dat_entry = NULL;
1363         u16 type;
1364         __be32 ip_src, ip_dst;
1365         u8 *hw_src, *hw_dst;
1366         bool dropped = false;
1367         unsigned short vid;
1368 
1369         if (!atomic_read(&bat_priv->distributed_arp_table))
1370                 goto out;
1371 
1372         vid = batadv_dat_get_vid(skb, &hdr_size);
1373 
1374         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1375         if (type != ARPOP_REPLY)
1376                 goto out;
1377 
1378         batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REPLY");
1379 
1380         hw_src = batadv_arp_hw_src(skb, hdr_size);
1381         ip_src = batadv_arp_ip_src(skb, hdr_size);
1382         hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1383         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1384 
1385         /* If ip_dst is already in cache and has the right mac address,
1386          * drop this frame if this ARP reply is destined for us because it's
1387          * most probably an ARP reply generated by another node of the DHT.
1388          * We have most probably received already a reply earlier. Delivering
1389          * this frame would lead to doubled receive of an ARP reply.
1390          */
1391         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_src, vid);
1392         if (dat_entry && batadv_compare_eth(hw_src, dat_entry->mac_addr)) {
1393                 batadv_dbg(BATADV_DBG_DAT, bat_priv, "Doubled ARP reply removed: ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]; dat_entry: %pM-%pI4\n",
1394                            hw_src, &ip_src, hw_dst, &ip_dst,
1395                            dat_entry->mac_addr, &dat_entry->ip);
1396                 dropped = true;
1397                 goto out;
1398         }
1399 
1400         /* Update our internal cache with both the IP addresses the node got
1401          * within the ARP reply
1402          */
1403         batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1404         batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1405 
1406         /* If BLA is enabled, only forward ARP replies if we have claimed the
1407          * source of the ARP reply or if no one else of the same backbone has
1408          * already claimed that client. This prevents that different gateways
1409          * to the same backbone all forward the ARP reply leading to multiple
1410          * replies in the backbone.
1411          */
1412         if (!batadv_bla_check_claim(bat_priv, hw_src, vid)) {
1413                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1414                            "Device %pM claimed by another backbone gw. Drop ARP reply.\n",
1415                            hw_src);
1416                 dropped = true;
1417                 goto out;
1418         }
1419 
1420         /* if this REPLY is directed to a client of mine, let's deliver the
1421          * packet to the interface
1422          */
1423         dropped = !batadv_is_my_client(bat_priv, hw_dst, vid);
1424 
1425         /* if this REPLY is sent on behalf of a client of mine, let's drop the
1426          * packet because the client will reply by itself
1427          */
1428         dropped |= batadv_is_my_client(bat_priv, hw_src, vid);
1429 out:
1430         if (dropped)
1431                 kfree_skb(skb);
1432         if (dat_entry)
1433                 batadv_dat_entry_put(dat_entry);
1434         /* if dropped == false -> deliver to the interface */
1435         return dropped;
1436 }
1437 
1438 /**
1439  * batadv_dat_drop_broadcast_packet() - check if an ARP request has to be
1440  *  dropped (because the node has already obtained the reply via DAT) or not
1441  * @bat_priv: the bat priv with all the soft interface information
1442  * @forw_packet: the broadcast packet
1443  *
1444  * Return: true if the node can drop the packet, false otherwise.
1445  */
1446 bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
1447                                       struct batadv_forw_packet *forw_packet)
1448 {
1449         u16 type;
1450         __be32 ip_dst;
1451         struct batadv_dat_entry *dat_entry = NULL;
1452         bool ret = false;
1453         int hdr_size = sizeof(struct batadv_bcast_packet);
1454         unsigned short vid;
1455 
1456         if (!atomic_read(&bat_priv->distributed_arp_table))
1457                 goto out;
1458 
1459         /* If this packet is an ARP_REQUEST and the node already has the
1460          * information that it is going to ask, then the packet can be dropped
1461          */
1462         if (batadv_forw_packet_is_rebroadcast(forw_packet))
1463                 goto out;
1464 
1465         vid = batadv_dat_get_vid(forw_packet->skb, &hdr_size);
1466 
1467         type = batadv_arp_get_type(bat_priv, forw_packet->skb, hdr_size);
1468         if (type != ARPOP_REQUEST)
1469                 goto out;
1470 
1471         ip_dst = batadv_arp_ip_dst(forw_packet->skb, hdr_size);
1472         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1473         /* check if the node already got this entry */
1474         if (!dat_entry) {
1475                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1476                            "ARP Request for %pI4: fallback\n", &ip_dst);
1477                 goto out;
1478         }
1479 
1480         batadv_dbg(BATADV_DBG_DAT, bat_priv,
1481                    "ARP Request for %pI4: fallback prevented\n", &ip_dst);
1482         ret = true;
1483 
1484 out:
1485         if (dat_entry)
1486                 batadv_dat_entry_put(dat_entry);
1487         return ret;
1488 }
1489 

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