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

Version: ~ [ linux-5.6-rc7 ] ~ [ linux-5.5.11 ] ~ [ linux-5.4.27 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.112 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.174 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.217 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.217 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.82 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /* Copyright (C) 2011-2013 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, write to the Free Software
 16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 17  * 02110-1301, USA
 18  */
 19 
 20 #include <linux/if_ether.h>
 21 #include <linux/if_arp.h>
 22 #include <net/arp.h>
 23 
 24 #include "main.h"
 25 #include "hash.h"
 26 #include "distributed-arp-table.h"
 27 #include "hard-interface.h"
 28 #include "originator.h"
 29 #include "send.h"
 30 #include "types.h"
 31 #include "translation-table.h"
 32 #include "unicast.h"
 33 
 34 static void batadv_dat_purge(struct work_struct *work);
 35 
 36 /**
 37  * batadv_dat_start_timer - initialise the DAT periodic worker
 38  * @bat_priv: the bat priv with all the soft interface information
 39  */
 40 static void batadv_dat_start_timer(struct batadv_priv *bat_priv)
 41 {
 42         INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge);
 43         queue_delayed_work(batadv_event_workqueue, &bat_priv->dat.work,
 44                            msecs_to_jiffies(10000));
 45 }
 46 
 47 /**
 48  * batadv_dat_entry_free_ref - decrements the dat_entry refcounter and possibly
 49  * free it
 50  * @dat_entry: the oentry to free
 51  */
 52 static void batadv_dat_entry_free_ref(struct batadv_dat_entry *dat_entry)
 53 {
 54         if (atomic_dec_and_test(&dat_entry->refcount))
 55                 kfree_rcu(dat_entry, rcu);
 56 }
 57 
 58 /**
 59  * batadv_dat_to_purge - checks whether a dat_entry has to be purged or not
 60  * @dat_entry: the entry to check
 61  *
 62  * Returns true if the entry has to be purged now, false otherwise
 63  */
 64 static bool batadv_dat_to_purge(struct batadv_dat_entry *dat_entry)
 65 {
 66         return batadv_has_timed_out(dat_entry->last_update,
 67                                     BATADV_DAT_ENTRY_TIMEOUT);
 68 }
 69 
 70 /**
 71  * __batadv_dat_purge - delete entries from the DAT local storage
 72  * @bat_priv: the bat priv with all the soft interface information
 73  * @to_purge: function in charge to decide whether an entry has to be purged or
 74  *            not. This function takes the dat_entry as argument and has to
 75  *            returns a boolean value: true is the entry has to be deleted,
 76  *            false otherwise
 77  *
 78  * Loops over each entry in the DAT local storage and delete it if and only if
 79  * the to_purge function passed as argument returns true
 80  */
 81 static void __batadv_dat_purge(struct batadv_priv *bat_priv,
 82                                bool (*to_purge)(struct batadv_dat_entry *))
 83 {
 84         spinlock_t *list_lock; /* protects write access to the hash lists */
 85         struct batadv_dat_entry *dat_entry;
 86         struct hlist_node *node_tmp;
 87         struct hlist_head *head;
 88         uint32_t i;
 89 
 90         if (!bat_priv->dat.hash)
 91                 return;
 92 
 93         for (i = 0; i < bat_priv->dat.hash->size; i++) {
 94                 head = &bat_priv->dat.hash->table[i];
 95                 list_lock = &bat_priv->dat.hash->list_locks[i];
 96 
 97                 spin_lock_bh(list_lock);
 98                 hlist_for_each_entry_safe(dat_entry, node_tmp, head,
 99                                           hash_entry) {
100                         /* if an helper function has been passed as parameter,
101                          * ask it if the entry has to be purged or not
102                          */
103                         if (to_purge && !to_purge(dat_entry))
104                                 continue;
105 
106                         hlist_del_rcu(&dat_entry->hash_entry);
107                         batadv_dat_entry_free_ref(dat_entry);
108                 }
109                 spin_unlock_bh(list_lock);
110         }
111 }
112 
113 /**
114  * batadv_dat_purge - periodic task that deletes old entries from the local DAT
115  * hash table
116  * @work: kernel work struct
117  */
118 static void batadv_dat_purge(struct work_struct *work)
119 {
120         struct delayed_work *delayed_work;
121         struct batadv_priv_dat *priv_dat;
122         struct batadv_priv *bat_priv;
123 
124         delayed_work = container_of(work, struct delayed_work, work);
125         priv_dat = container_of(delayed_work, struct batadv_priv_dat, work);
126         bat_priv = container_of(priv_dat, struct batadv_priv, dat);
127 
128         __batadv_dat_purge(bat_priv, batadv_dat_to_purge);
129         batadv_dat_start_timer(bat_priv);
130 }
131 
132 /**
133  * batadv_compare_dat - comparing function used in the local DAT hash table
134  * @node: node in the local table
135  * @data2: second object to compare the node to
136  *
137  * Returns 1 if the two entry are the same, 0 otherwise
138  */
139 static int batadv_compare_dat(const struct hlist_node *node, const void *data2)
140 {
141         const void *data1 = container_of(node, struct batadv_dat_entry,
142                                          hash_entry);
143 
144         return (memcmp(data1, data2, sizeof(__be32)) == 0 ? 1 : 0);
145 }
146 
147 /**
148  * batadv_arp_hw_src - extract the hw_src field from an ARP packet
149  * @skb: ARP packet
150  * @hdr_size: size of the possible header before the ARP packet
151  *
152  * Returns the value of the hw_src field in the ARP packet
153  */
154 static uint8_t *batadv_arp_hw_src(struct sk_buff *skb, int hdr_size)
155 {
156         uint8_t *addr;
157 
158         addr = (uint8_t *)(skb->data + hdr_size);
159         addr += ETH_HLEN + sizeof(struct arphdr);
160 
161         return addr;
162 }
163 
164 /**
165  * batadv_arp_ip_src - extract the ip_src field from an ARP packet
166  * @skb: ARP packet
167  * @hdr_size: size of the possible header before the ARP packet
168  *
169  * Returns the value of the ip_src field in the ARP packet
170  */
171 static __be32 batadv_arp_ip_src(struct sk_buff *skb, int hdr_size)
172 {
173         return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN);
174 }
175 
176 /**
177  * batadv_arp_hw_dst - extract the hw_dst field from an ARP packet
178  * @skb: ARP packet
179  * @hdr_size: size of the possible header before the ARP packet
180  *
181  * Returns the value of the hw_dst field in the ARP packet
182  */
183 static uint8_t *batadv_arp_hw_dst(struct sk_buff *skb, int hdr_size)
184 {
185         return batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN + 4;
186 }
187 
188 /**
189  * batadv_arp_ip_dst - extract the ip_dst field from an ARP packet
190  * @skb: ARP packet
191  * @hdr_size: size of the possible header before the ARP packet
192  *
193  * Returns the value of the ip_dst field in the ARP packet
194  */
195 static __be32 batadv_arp_ip_dst(struct sk_buff *skb, int hdr_size)
196 {
197         return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4);
198 }
199 
200 /**
201  * batadv_hash_dat - compute the hash value for an IP address
202  * @data: data to hash
203  * @size: size of the hash table
204  *
205  * Returns the selected index in the hash table for the given data
206  */
207 static uint32_t batadv_hash_dat(const void *data, uint32_t size)
208 {
209         const unsigned char *key = data;
210         uint32_t hash = 0;
211         size_t i;
212 
213         for (i = 0; i < 4; i++) {
214                 hash += key[i];
215                 hash += (hash << 10);
216                 hash ^= (hash >> 6);
217         }
218 
219         hash += (hash << 3);
220         hash ^= (hash >> 11);
221         hash += (hash << 15);
222 
223         return hash % size;
224 }
225 
226 /**
227  * batadv_dat_entry_hash_find - looks for a given dat_entry in the local hash
228  * table
229  * @bat_priv: the bat priv with all the soft interface information
230  * @ip: search key
231  *
232  * Returns the dat_entry if found, NULL otherwise
233  */
234 static struct batadv_dat_entry *
235 batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip)
236 {
237         struct hlist_head *head;
238         struct batadv_dat_entry *dat_entry, *dat_entry_tmp = NULL;
239         struct batadv_hashtable *hash = bat_priv->dat.hash;
240         uint32_t index;
241 
242         if (!hash)
243                 return NULL;
244 
245         index = batadv_hash_dat(&ip, hash->size);
246         head = &hash->table[index];
247 
248         rcu_read_lock();
249         hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
250                 if (dat_entry->ip != ip)
251                         continue;
252 
253                 if (!atomic_inc_not_zero(&dat_entry->refcount))
254                         continue;
255 
256                 dat_entry_tmp = dat_entry;
257                 break;
258         }
259         rcu_read_unlock();
260 
261         return dat_entry_tmp;
262 }
263 
264 /**
265  * batadv_dat_entry_add - add a new dat entry or update it if already exists
266  * @bat_priv: the bat priv with all the soft interface information
267  * @ip: ipv4 to add/edit
268  * @mac_addr: mac address to assign to the given ipv4
269  */
270 static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
271                                  uint8_t *mac_addr)
272 {
273         struct batadv_dat_entry *dat_entry;
274         int hash_added;
275 
276         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip);
277         /* if this entry is already known, just update it */
278         if (dat_entry) {
279                 if (!batadv_compare_eth(dat_entry->mac_addr, mac_addr))
280                         memcpy(dat_entry->mac_addr, mac_addr, ETH_ALEN);
281                 dat_entry->last_update = jiffies;
282                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
283                            "Entry updated: %pI4 %pM\n", &dat_entry->ip,
284                            dat_entry->mac_addr);
285                 goto out;
286         }
287 
288         dat_entry = kmalloc(sizeof(*dat_entry), GFP_ATOMIC);
289         if (!dat_entry)
290                 goto out;
291 
292         dat_entry->ip = ip;
293         memcpy(dat_entry->mac_addr, mac_addr, ETH_ALEN);
294         dat_entry->last_update = jiffies;
295         atomic_set(&dat_entry->refcount, 2);
296 
297         hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
298                                      batadv_hash_dat, &dat_entry->ip,
299                                      &dat_entry->hash_entry);
300 
301         if (unlikely(hash_added != 0)) {
302                 /* remove the reference for the hash */
303                 batadv_dat_entry_free_ref(dat_entry);
304                 goto out;
305         }
306 
307         batadv_dbg(BATADV_DBG_DAT, bat_priv, "New entry added: %pI4 %pM\n",
308                    &dat_entry->ip, dat_entry->mac_addr);
309 
310 out:
311         if (dat_entry)
312                 batadv_dat_entry_free_ref(dat_entry);
313 }
314 
315 #ifdef CONFIG_BATMAN_ADV_DEBUG
316 
317 /**
318  * batadv_dbg_arp - print a debug message containing all the ARP packet details
319  * @bat_priv: the bat priv with all the soft interface information
320  * @skb: ARP packet
321  * @type: ARP type
322  * @hdr_size: size of the possible header before the ARP packet
323  * @msg: message to print together with the debugging information
324  */
325 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
326                            uint16_t type, int hdr_size, char *msg)
327 {
328         struct batadv_unicast_4addr_packet *unicast_4addr_packet;
329         struct batadv_bcast_packet *bcast_pkt;
330         uint8_t *orig_addr;
331         __be32 ip_src, ip_dst;
332 
333         if (msg)
334                 batadv_dbg(BATADV_DBG_DAT, bat_priv, "%s\n", msg);
335 
336         ip_src = batadv_arp_ip_src(skb, hdr_size);
337         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
338         batadv_dbg(BATADV_DBG_DAT, bat_priv,
339                    "ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]\n",
340                    batadv_arp_hw_src(skb, hdr_size), &ip_src,
341                    batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
342 
343         if (hdr_size == 0)
344                 return;
345 
346         /* if the ARP packet is encapsulated in a batman packet, let's print
347          * some debug messages
348          */
349         unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
350 
351         switch (unicast_4addr_packet->u.header.packet_type) {
352         case BATADV_UNICAST:
353                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
354                            "* encapsulated within a UNICAST packet\n");
355                 break;
356         case BATADV_UNICAST_4ADDR:
357                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
358                            "* encapsulated within a UNICAST_4ADDR packet (src: %pM)\n",
359                            unicast_4addr_packet->src);
360                 switch (unicast_4addr_packet->subtype) {
361                 case BATADV_P_DAT_DHT_PUT:
362                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_PUT\n");
363                         break;
364                 case BATADV_P_DAT_DHT_GET:
365                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_GET\n");
366                         break;
367                 case BATADV_P_DAT_CACHE_REPLY:
368                         batadv_dbg(BATADV_DBG_DAT, bat_priv,
369                                    "* type: DAT_CACHE_REPLY\n");
370                         break;
371                 case BATADV_P_DATA:
372                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DATA\n");
373                         break;
374                 default:
375                         batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: Unknown (%u)!\n",
376                                    unicast_4addr_packet->u.header.packet_type);
377                 }
378                 break;
379         case BATADV_BCAST:
380                 bcast_pkt = (struct batadv_bcast_packet *)unicast_4addr_packet;
381                 orig_addr = bcast_pkt->orig;
382                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
383                            "* encapsulated within a BCAST packet (src: %pM)\n",
384                            orig_addr);
385                 break;
386         default:
387                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
388                            "* encapsulated within an unknown packet type (0x%x)\n",
389                            unicast_4addr_packet->u.header.packet_type);
390         }
391 }
392 
393 #else
394 
395 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
396                            uint16_t type, int hdr_size, char *msg)
397 {
398 }
399 
400 #endif /* CONFIG_BATMAN_ADV_DEBUG */
401 
402 /**
403  * batadv_is_orig_node_eligible - check whether a node can be a DHT candidate
404  * @res: the array with the already selected candidates
405  * @select: number of already selected candidates
406  * @tmp_max: address of the currently evaluated node
407  * @max: current round max address
408  * @last_max: address of the last selected candidate
409  * @candidate: orig_node under evaluation
410  * @max_orig_node: last selected candidate
411  *
412  * Returns true if the node has been elected as next candidate or false othrwise
413  */
414 static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
415                                          int select, batadv_dat_addr_t tmp_max,
416                                          batadv_dat_addr_t max,
417                                          batadv_dat_addr_t last_max,
418                                          struct batadv_orig_node *candidate,
419                                          struct batadv_orig_node *max_orig_node)
420 {
421         bool ret = false;
422         int j;
423 
424         /* Check if this node has already been selected... */
425         for (j = 0; j < select; j++)
426                 if (res[j].orig_node == candidate)
427                         break;
428         /* ..and possibly skip it */
429         if (j < select)
430                 goto out;
431         /* sanity check: has it already been selected? This should not happen */
432         if (tmp_max > last_max)
433                 goto out;
434         /* check if during this iteration an originator with a closer dht
435          * address has already been found
436          */
437         if (tmp_max < max)
438                 goto out;
439         /* this is an hash collision with the temporary selected node. Choose
440          * the one with the lowest address
441          */
442         if ((tmp_max == max) && max_orig_node &&
443             (batadv_compare_eth(candidate->orig, max_orig_node->orig) > 0))
444                 goto out;
445 
446         ret = true;
447 out:
448         return ret;
449 }
450 
451 /**
452  * batadv_choose_next_candidate - select the next DHT candidate
453  * @bat_priv: the bat priv with all the soft interface information
454  * @cands: candidates array
455  * @select: number of candidates already present in the array
456  * @ip_key: key to look up in the DHT
457  * @last_max: pointer where the address of the selected candidate will be saved
458  */
459 static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
460                                          struct batadv_dat_candidate *cands,
461                                          int select, batadv_dat_addr_t ip_key,
462                                          batadv_dat_addr_t *last_max)
463 {
464         batadv_dat_addr_t max = 0, tmp_max = 0;
465         struct batadv_orig_node *orig_node, *max_orig_node = NULL;
466         struct batadv_hashtable *hash = bat_priv->orig_hash;
467         struct hlist_head *head;
468         int i;
469 
470         /* if no node is eligible as candidate, leave the candidate type as
471          * NOT_FOUND
472          */
473         cands[select].type = BATADV_DAT_CANDIDATE_NOT_FOUND;
474 
475         /* iterate over the originator list and find the node with closest
476          * dat_address which has not been selected yet
477          */
478         for (i = 0; i < hash->size; i++) {
479                 head = &hash->table[i];
480 
481                 rcu_read_lock();
482                 hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
483                         /* the dht space is a ring and addresses are unsigned */
484                         tmp_max = BATADV_DAT_ADDR_MAX - orig_node->dat_addr +
485                                   ip_key;
486 
487                         if (!batadv_is_orig_node_eligible(cands, select,
488                                                           tmp_max, max,
489                                                           *last_max, orig_node,
490                                                           max_orig_node))
491                                 continue;
492 
493                         if (!atomic_inc_not_zero(&orig_node->refcount))
494                                 continue;
495 
496                         max = tmp_max;
497                         if (max_orig_node)
498                                 batadv_orig_node_free_ref(max_orig_node);
499                         max_orig_node = orig_node;
500                 }
501                 rcu_read_unlock();
502         }
503         if (max_orig_node) {
504                 cands[select].type = BATADV_DAT_CANDIDATE_ORIG;
505                 cands[select].orig_node = max_orig_node;
506                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
507                            "dat_select_candidates() %d: selected %pM addr=%u dist=%u\n",
508                            select, max_orig_node->orig, max_orig_node->dat_addr,
509                            max);
510         }
511         *last_max = max;
512 }
513 
514 /**
515  * batadv_dat_select_candidates - selects the nodes which the DHT message has to
516  * be sent to
517  * @bat_priv: the bat priv with all the soft interface information
518  * @ip_dst: ipv4 to look up in the DHT
519  *
520  * An originator O is selected if and only if its DHT_ID value is one of three
521  * closest values (from the LEFT, with wrap around if needed) then the hash
522  * value of the key. ip_dst is the key.
523  *
524  * Returns the candidate array of size BATADV_DAT_CANDIDATE_NUM
525  */
526 static struct batadv_dat_candidate *
527 batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst)
528 {
529         int select;
530         batadv_dat_addr_t last_max = BATADV_DAT_ADDR_MAX, ip_key;
531         struct batadv_dat_candidate *res;
532 
533         if (!bat_priv->orig_hash)
534                 return NULL;
535 
536         res = kmalloc(BATADV_DAT_CANDIDATES_NUM * sizeof(*res), GFP_ATOMIC);
537         if (!res)
538                 return NULL;
539 
540         ip_key = (batadv_dat_addr_t)batadv_hash_dat(&ip_dst,
541                                                     BATADV_DAT_ADDR_MAX);
542 
543         batadv_dbg(BATADV_DBG_DAT, bat_priv,
544                    "dat_select_candidates(): IP=%pI4 hash(IP)=%u\n", &ip_dst,
545                    ip_key);
546 
547         for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
548                 batadv_choose_next_candidate(bat_priv, res, select, ip_key,
549                                              &last_max);
550 
551         return res;
552 }
553 
554 /**
555  * batadv_dat_send_data - send a payload to the selected candidates
556  * @bat_priv: the bat priv with all the soft interface information
557  * @skb: payload to send
558  * @ip: the DHT key
559  * @packet_subtype: unicast4addr packet subtype to use
560  *
561  * In this function the skb is copied by means of pskb_copy() and is sent as
562  * unicast packet to each of the selected candidates
563  *
564  * Returns true if the packet is sent to at least one candidate, false otherwise
565  */
566 static bool batadv_dat_send_data(struct batadv_priv *bat_priv,
567                                  struct sk_buff *skb, __be32 ip,
568                                  int packet_subtype)
569 {
570         int i;
571         bool ret = false;
572         int send_status;
573         struct batadv_neigh_node *neigh_node = NULL;
574         struct sk_buff *tmp_skb;
575         struct batadv_dat_candidate *cand;
576 
577         cand = batadv_dat_select_candidates(bat_priv, ip);
578         if (!cand)
579                 goto out;
580 
581         batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
582 
583         for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
584                 if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
585                         continue;
586 
587                 neigh_node = batadv_orig_node_get_router(cand[i].orig_node);
588                 if (!neigh_node)
589                         goto free_orig;
590 
591                 tmp_skb = pskb_copy(skb, GFP_ATOMIC);
592                 if (!batadv_unicast_4addr_prepare_skb(bat_priv, tmp_skb,
593                                                       cand[i].orig_node,
594                                                       packet_subtype)) {
595                         kfree_skb(tmp_skb);
596                         goto free_neigh;
597                 }
598 
599                 send_status = batadv_send_skb_packet(tmp_skb,
600                                                      neigh_node->if_incoming,
601                                                      neigh_node->addr);
602                 if (send_status == NET_XMIT_SUCCESS) {
603                         /* count the sent packet */
604                         switch (packet_subtype) {
605                         case BATADV_P_DAT_DHT_GET:
606                                 batadv_inc_counter(bat_priv,
607                                                    BATADV_CNT_DAT_GET_TX);
608                                 break;
609                         case BATADV_P_DAT_DHT_PUT:
610                                 batadv_inc_counter(bat_priv,
611                                                    BATADV_CNT_DAT_PUT_TX);
612                                 break;
613                         }
614 
615                         /* packet sent to a candidate: return true */
616                         ret = true;
617                 }
618 free_neigh:
619                 batadv_neigh_node_free_ref(neigh_node);
620 free_orig:
621                 batadv_orig_node_free_ref(cand[i].orig_node);
622         }
623 
624 out:
625         kfree(cand);
626         return ret;
627 }
628 
629 /**
630  * batadv_dat_hash_free - free the local DAT hash table
631  * @bat_priv: the bat priv with all the soft interface information
632  */
633 static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
634 {
635         if (!bat_priv->dat.hash)
636                 return;
637 
638         __batadv_dat_purge(bat_priv, NULL);
639 
640         batadv_hash_destroy(bat_priv->dat.hash);
641 
642         bat_priv->dat.hash = NULL;
643 }
644 
645 /**
646  * batadv_dat_init - initialise the DAT internals
647  * @bat_priv: the bat priv with all the soft interface information
648  */
649 int batadv_dat_init(struct batadv_priv *bat_priv)
650 {
651         if (bat_priv->dat.hash)
652                 return 0;
653 
654         bat_priv->dat.hash = batadv_hash_new(1024);
655 
656         if (!bat_priv->dat.hash)
657                 return -ENOMEM;
658 
659         batadv_dat_start_timer(bat_priv);
660 
661         return 0;
662 }
663 
664 /**
665  * batadv_dat_free - free the DAT internals
666  * @bat_priv: the bat priv with all the soft interface information
667  */
668 void batadv_dat_free(struct batadv_priv *bat_priv)
669 {
670         cancel_delayed_work_sync(&bat_priv->dat.work);
671 
672         batadv_dat_hash_free(bat_priv);
673 }
674 
675 /**
676  * batadv_dat_cache_seq_print_text - print the local DAT hash table
677  * @seq: seq file to print on
678  * @offset: not used
679  */
680 int batadv_dat_cache_seq_print_text(struct seq_file *seq, void *offset)
681 {
682         struct net_device *net_dev = (struct net_device *)seq->private;
683         struct batadv_priv *bat_priv = netdev_priv(net_dev);
684         struct batadv_hashtable *hash = bat_priv->dat.hash;
685         struct batadv_dat_entry *dat_entry;
686         struct batadv_hard_iface *primary_if;
687         struct hlist_head *head;
688         unsigned long last_seen_jiffies;
689         int last_seen_msecs, last_seen_secs, last_seen_mins;
690         uint32_t i;
691 
692         primary_if = batadv_seq_print_text_primary_if_get(seq);
693         if (!primary_if)
694                 goto out;
695 
696         seq_printf(seq, "Distributed ARP Table (%s):\n", net_dev->name);
697         seq_printf(seq, "          %-7s          %-13s %5s\n", "IPv4", "MAC",
698                    "last-seen");
699 
700         for (i = 0; i < hash->size; i++) {
701                 head = &hash->table[i];
702 
703                 rcu_read_lock();
704                 hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
705                         last_seen_jiffies = jiffies - dat_entry->last_update;
706                         last_seen_msecs = jiffies_to_msecs(last_seen_jiffies);
707                         last_seen_mins = last_seen_msecs / 60000;
708                         last_seen_msecs = last_seen_msecs % 60000;
709                         last_seen_secs = last_seen_msecs / 1000;
710 
711                         seq_printf(seq, " * %15pI4 %14pM %6i:%02i\n",
712                                    &dat_entry->ip, dat_entry->mac_addr,
713                                    last_seen_mins, last_seen_secs);
714                 }
715                 rcu_read_unlock();
716         }
717 
718 out:
719         if (primary_if)
720                 batadv_hardif_free_ref(primary_if);
721         return 0;
722 }
723 
724 /**
725  * batadv_arp_get_type - parse an ARP packet and gets the type
726  * @bat_priv: the bat priv with all the soft interface information
727  * @skb: packet to analyse
728  * @hdr_size: size of the possible header before the ARP packet in the skb
729  *
730  * Returns the ARP type if the skb contains a valid ARP packet, 0 otherwise
731  */
732 static uint16_t batadv_arp_get_type(struct batadv_priv *bat_priv,
733                                     struct sk_buff *skb, int hdr_size)
734 {
735         struct arphdr *arphdr;
736         struct ethhdr *ethhdr;
737         __be32 ip_src, ip_dst;
738         uint8_t *hw_src, *hw_dst;
739         uint16_t type = 0;
740 
741         /* pull the ethernet header */
742         if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
743                 goto out;
744 
745         ethhdr = (struct ethhdr *)(skb->data + hdr_size);
746 
747         if (ethhdr->h_proto != htons(ETH_P_ARP))
748                 goto out;
749 
750         /* pull the ARP payload */
751         if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
752                                     arp_hdr_len(skb->dev))))
753                 goto out;
754 
755         arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
756 
757         /* Check whether the ARP packet carries a valid
758          * IP information
759          */
760         if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
761                 goto out;
762 
763         if (arphdr->ar_pro != htons(ETH_P_IP))
764                 goto out;
765 
766         if (arphdr->ar_hln != ETH_ALEN)
767                 goto out;
768 
769         if (arphdr->ar_pln != 4)
770                 goto out;
771 
772         /* Check for bad reply/request. If the ARP message is not sane, DAT
773          * will simply ignore it
774          */
775         ip_src = batadv_arp_ip_src(skb, hdr_size);
776         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
777         if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
778             ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst) ||
779             ipv4_is_zeronet(ip_src) || ipv4_is_lbcast(ip_src) ||
780             ipv4_is_zeronet(ip_dst) || ipv4_is_lbcast(ip_dst))
781                 goto out;
782 
783         hw_src = batadv_arp_hw_src(skb, hdr_size);
784         if (is_zero_ether_addr(hw_src) || is_multicast_ether_addr(hw_src))
785                 goto out;
786 
787         /* we don't care about the destination MAC address in ARP requests */
788         if (arphdr->ar_op != htons(ARPOP_REQUEST)) {
789                 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
790                 if (is_zero_ether_addr(hw_dst) ||
791                     is_multicast_ether_addr(hw_dst))
792                         goto out;
793         }
794 
795         type = ntohs(arphdr->ar_op);
796 out:
797         return type;
798 }
799 
800 /**
801  * batadv_dat_snoop_outgoing_arp_request - snoop the ARP request and try to
802  * answer using DAT
803  * @bat_priv: the bat priv with all the soft interface information
804  * @skb: packet to check
805  *
806  * Returns true if the message has been sent to the dht candidates, false
807  * otherwise. In case of true the message has to be enqueued to permit the
808  * fallback
809  */
810 bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
811                                            struct sk_buff *skb)
812 {
813         uint16_t type = 0;
814         __be32 ip_dst, ip_src;
815         uint8_t *hw_src;
816         bool ret = false;
817         struct batadv_dat_entry *dat_entry = NULL;
818         struct sk_buff *skb_new;
819 
820         if (!atomic_read(&bat_priv->distributed_arp_table))
821                 goto out;
822 
823         type = batadv_arp_get_type(bat_priv, skb, 0);
824         /* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast
825          * message to the selected DHT candidates
826          */
827         if (type != ARPOP_REQUEST)
828                 goto out;
829 
830         batadv_dbg_arp(bat_priv, skb, type, 0, "Parsing outgoing ARP REQUEST");
831 
832         ip_src = batadv_arp_ip_src(skb, 0);
833         hw_src = batadv_arp_hw_src(skb, 0);
834         ip_dst = batadv_arp_ip_dst(skb, 0);
835 
836         batadv_dat_entry_add(bat_priv, ip_src, hw_src);
837 
838         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);
839         if (dat_entry) {
840                 /* If the ARP request is destined for a local client the local
841                  * client will answer itself. DAT would only generate a
842                  * duplicate packet.
843                  *
844                  * Moreover, if the soft-interface is enslaved into a bridge, an
845                  * additional DAT answer may trigger kernel warnings about
846                  * a packet coming from the wrong port.
847                  */
848                 if (batadv_is_my_client(bat_priv, dat_entry->mac_addr)) {
849                         ret = true;
850                         goto out;
851                 }
852 
853                 skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,
854                                      bat_priv->soft_iface, ip_dst, hw_src,
855                                      dat_entry->mac_addr, hw_src);
856                 if (!skb_new)
857                         goto out;
858 
859                 skb_reset_mac_header(skb_new);
860                 skb_new->protocol = eth_type_trans(skb_new,
861                                                    bat_priv->soft_iface);
862                 bat_priv->stats.rx_packets++;
863                 bat_priv->stats.rx_bytes += skb->len + ETH_HLEN;
864                 bat_priv->soft_iface->last_rx = jiffies;
865 
866                 netif_rx(skb_new);
867                 batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
868                 ret = true;
869         } else {
870                 /* Send the request on the DHT */
871                 ret = batadv_dat_send_data(bat_priv, skb, ip_dst,
872                                            BATADV_P_DAT_DHT_GET);
873         }
874 out:
875         if (dat_entry)
876                 batadv_dat_entry_free_ref(dat_entry);
877         return ret;
878 }
879 
880 /**
881  * batadv_dat_snoop_incoming_arp_request - snoop the ARP request and try to
882  * answer using the local DAT storage
883  * @bat_priv: the bat priv with all the soft interface information
884  * @skb: packet to check
885  * @hdr_size: size of the encapsulation header
886  *
887  * Returns true if the request has been answered, false otherwise
888  */
889 bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
890                                            struct sk_buff *skb, int hdr_size)
891 {
892         uint16_t type;
893         __be32 ip_src, ip_dst;
894         uint8_t *hw_src;
895         struct sk_buff *skb_new;
896         struct batadv_dat_entry *dat_entry = NULL;
897         bool ret = false;
898         int err;
899 
900         if (!atomic_read(&bat_priv->distributed_arp_table))
901                 goto out;
902 
903         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
904         if (type != ARPOP_REQUEST)
905                 goto out;
906 
907         hw_src = batadv_arp_hw_src(skb, hdr_size);
908         ip_src = batadv_arp_ip_src(skb, hdr_size);
909         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
910 
911         batadv_dbg_arp(bat_priv, skb, type, hdr_size,
912                        "Parsing incoming ARP REQUEST");
913 
914         batadv_dat_entry_add(bat_priv, ip_src, hw_src);
915 
916         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);
917         if (!dat_entry)
918                 goto out;
919 
920         skb_new = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_src,
921                              bat_priv->soft_iface, ip_dst, hw_src,
922                              dat_entry->mac_addr, hw_src);
923 
924         if (!skb_new)
925                 goto out;
926 
927         /* to preserve backwards compatibility, here the node has to answer
928          * using the same packet type it received for the request. This is due
929          * to that if a node is not using the 4addr packet format it may not
930          * support it.
931          */
932         if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))
933                 err = batadv_unicast_4addr_send_skb(bat_priv, skb_new,
934                                                     BATADV_P_DAT_CACHE_REPLY);
935         else
936                 err = batadv_unicast_send_skb(bat_priv, skb_new);
937 
938         if (!err) {
939                 batadv_inc_counter(bat_priv, BATADV_CNT_DAT_CACHED_REPLY_TX);
940                 ret = true;
941         }
942 out:
943         if (dat_entry)
944                 batadv_dat_entry_free_ref(dat_entry);
945         if (ret)
946                 kfree_skb(skb);
947         return ret;
948 }
949 
950 /**
951  * batadv_dat_snoop_outgoing_arp_reply - snoop the ARP reply and fill the DHT
952  * @bat_priv: the bat priv with all the soft interface information
953  * @skb: packet to check
954  */
955 void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
956                                          struct sk_buff *skb)
957 {
958         uint16_t type;
959         __be32 ip_src, ip_dst;
960         uint8_t *hw_src, *hw_dst;
961 
962         if (!atomic_read(&bat_priv->distributed_arp_table))
963                 return;
964 
965         type = batadv_arp_get_type(bat_priv, skb, 0);
966         if (type != ARPOP_REPLY)
967                 return;
968 
969         batadv_dbg_arp(bat_priv, skb, type, 0, "Parsing outgoing ARP REPLY");
970 
971         hw_src = batadv_arp_hw_src(skb, 0);
972         ip_src = batadv_arp_ip_src(skb, 0);
973         hw_dst = batadv_arp_hw_dst(skb, 0);
974         ip_dst = batadv_arp_ip_dst(skb, 0);
975 
976         batadv_dat_entry_add(bat_priv, ip_src, hw_src);
977         batadv_dat_entry_add(bat_priv, ip_dst, hw_dst);
978 
979         /* Send the ARP reply to the candidates for both the IP addresses that
980          * the node got within the ARP reply
981          */
982         batadv_dat_send_data(bat_priv, skb, ip_src, BATADV_P_DAT_DHT_PUT);
983         batadv_dat_send_data(bat_priv, skb, ip_dst, BATADV_P_DAT_DHT_PUT);
984 }
985 /**
986  * batadv_dat_snoop_incoming_arp_reply - snoop the ARP reply and fill the local
987  * DAT storage only
988  * @bat_priv: the bat priv with all the soft interface information
989  * @skb: packet to check
990  * @hdr_size: siaze of the encapsulation header
991  */
992 bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
993                                          struct sk_buff *skb, int hdr_size)
994 {
995         uint16_t type;
996         __be32 ip_src, ip_dst;
997         uint8_t *hw_src, *hw_dst;
998         bool ret = false;
999 
1000         if (!atomic_read(&bat_priv->distributed_arp_table))
1001                 goto out;
1002 
1003         type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1004         if (type != ARPOP_REPLY)
1005                 goto out;
1006 
1007         batadv_dbg_arp(bat_priv, skb, type, hdr_size,
1008                        "Parsing incoming ARP REPLY");
1009 
1010         hw_src = batadv_arp_hw_src(skb, hdr_size);
1011         ip_src = batadv_arp_ip_src(skb, hdr_size);
1012         hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1013         ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1014 
1015         /* Update our internal cache with both the IP addresses the node got
1016          * within the ARP reply
1017          */
1018         batadv_dat_entry_add(bat_priv, ip_src, hw_src);
1019         batadv_dat_entry_add(bat_priv, ip_dst, hw_dst);
1020 
1021         /* if this REPLY is directed to a client of mine, let's deliver the
1022          * packet to the interface
1023          */
1024         ret = !batadv_is_my_client(bat_priv, hw_dst);
1025 out:
1026         if (ret)
1027                 kfree_skb(skb);
1028         /* if ret == false -> packet has to be delivered to the interface */
1029         return ret;
1030 }
1031 
1032 /**
1033  * batadv_dat_drop_broadcast_packet - check if an ARP request has to be dropped
1034  * (because the node has already got the reply via DAT) or not
1035  * @bat_priv: the bat priv with all the soft interface information
1036  * @forw_packet: the broadcast packet
1037  *
1038  * Returns true if the node can drop the packet, false otherwise
1039  */
1040 bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
1041                                       struct batadv_forw_packet *forw_packet)
1042 {
1043         uint16_t type;
1044         __be32 ip_dst;
1045         struct batadv_dat_entry *dat_entry = NULL;
1046         bool ret = false;
1047         const size_t bcast_len = sizeof(struct batadv_bcast_packet);
1048 
1049         if (!atomic_read(&bat_priv->distributed_arp_table))
1050                 goto out;
1051 
1052         /* If this packet is an ARP_REQUEST and the node already has the
1053          * information that it is going to ask, then the packet can be dropped
1054          */
1055         if (forw_packet->num_packets)
1056                 goto out;
1057 
1058         type = batadv_arp_get_type(bat_priv, forw_packet->skb, bcast_len);
1059         if (type != ARPOP_REQUEST)
1060                 goto out;
1061 
1062         ip_dst = batadv_arp_ip_dst(forw_packet->skb, bcast_len);
1063         dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst);
1064         /* check if the node already got this entry */
1065         if (!dat_entry) {
1066                 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1067                            "ARP Request for %pI4: fallback\n", &ip_dst);
1068                 goto out;
1069         }
1070 
1071         batadv_dbg(BATADV_DBG_DAT, bat_priv,
1072                    "ARP Request for %pI4: fallback prevented\n", &ip_dst);
1073         ret = true;
1074 
1075 out:
1076         if (dat_entry)
1077                 batadv_dat_entry_free_ref(dat_entry);
1078         return ret;
1079 }
1080 

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