1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) B.A.T.M.A.N. contributors:
3 *
4 * Antonio Quartulli
5 */
6
7 #include "distributed-arp-table.h"
8 #include "main.h"
9
10 #include <linux/atomic.h>
11 #include <linux/bitops.h>
12 #include <linux/byteorder/generic.h>
13 #include <linux/container_of.h>
14 #include <linux/err.h>
15 #include <linux/errno.h>
16 #include <linux/etherdevice.h>
17 #include <linux/gfp.h>
18 #include <linux/if_arp.h>
19 #include <linux/if_ether.h>
20 #include <linux/if_vlan.h>
21 #include <linux/in.h>
22 #include <linux/ip.h>
23 #include <linux/jiffies.h>
24 #include <linux/kref.h>
25 #include <linux/list.h>
26 #include <linux/netlink.h>
27 #include <linux/rculist.h>
28 #include <linux/rcupdate.h>
29 #include <linux/skbuff.h>
30 #include <linux/slab.h>
31 #include <linux/spinlock.h>
32 #include <linux/stddef.h>
33 #include <linux/string.h>
34 #include <linux/udp.h>
35 #include <linux/unaligned.h>
36 #include <linux/workqueue.h>
37 #include <net/arp.h>
38 #include <net/genetlink.h>
39 #include <net/netlink.h>
40 #include <uapi/linux/batman_adv.h>
41
42 #include "bridge_loop_avoidance.h"
43 #include "hard-interface.h"
44 #include "hash.h"
45 #include "log.h"
46 #include "netlink.h"
47 #include "originator.h"
48 #include "send.h"
49 #include "translation-table.h"
50 #include "tvlv.h"
51
52 enum batadv_bootpop {
53 BATADV_BOOTREPLY = 2,
54 };
55
56 enum batadv_boothtype {
57 BATADV_HTYPE_ETHERNET = 1,
58 };
59
60 enum batadv_dhcpoptioncode {
61 BATADV_DHCP_OPT_PAD = 0,
62 BATADV_DHCP_OPT_MSG_TYPE = 53,
63 BATADV_DHCP_OPT_END = 255,
64 };
65
66 enum batadv_dhcptype {
67 BATADV_DHCPACK = 5,
68 };
69
70 /* { 99, 130, 83, 99 } */
71 #define BATADV_DHCP_MAGIC 1669485411
72
73 struct batadv_dhcp_packet {
74 __u8 op;
75 __u8 htype;
76 __u8 hlen;
77 __u8 hops;
78 __be32 xid;
79 __be16 secs;
80 __be16 flags;
81 __be32 ciaddr;
82 __be32 yiaddr;
83 __be32 siaddr;
84 __be32 giaddr;
85 __u8 chaddr[16];
86 __u8 sname[64];
87 __u8 file[128];
88 __be32 magic;
89 /* __u8 options[]; */
90 };
91
92 #define BATADV_DHCP_YIADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->yiaddr)
93 #define BATADV_DHCP_CHADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->chaddr)
94
95 static void batadv_dat_purge(struct work_struct *work);
96
97 /**
98 * batadv_dat_start_timer() - initialise the DAT periodic worker
99 * @bat_priv: the bat priv with all the mesh interface information
100 */
batadv_dat_start_timer(struct batadv_priv * bat_priv)101 static void batadv_dat_start_timer(struct batadv_priv *bat_priv)
102 {
103 queue_delayed_work(batadv_event_workqueue, &bat_priv->dat.work,
104 msecs_to_jiffies(10000));
105 }
106
107 /**
108 * batadv_dat_entry_release() - release dat_entry from lists and queue for free
109 * after rcu grace period
110 * @ref: kref pointer of the dat_entry
111 */
batadv_dat_entry_release(struct kref * ref)112 static void batadv_dat_entry_release(struct kref *ref)
113 {
114 struct batadv_dat_entry *dat_entry;
115
116 dat_entry = container_of(ref, struct batadv_dat_entry, refcount);
117
118 kfree_rcu(dat_entry, rcu);
119 }
120
121 /**
122 * batadv_dat_entry_put() - decrement the dat_entry refcounter and possibly
123 * release it
124 * @dat_entry: dat_entry to be free'd
125 */
batadv_dat_entry_put(struct batadv_dat_entry * dat_entry)126 static void batadv_dat_entry_put(struct batadv_dat_entry *dat_entry)
127 {
128 if (!dat_entry)
129 return;
130
131 kref_put(&dat_entry->refcount, batadv_dat_entry_release);
132 }
133
134 /**
135 * batadv_dat_to_purge() - check whether a dat_entry has to be purged or not
136 * @dat_entry: the entry to check
137 *
138 * Return: true if the entry has to be purged now, false otherwise.
139 */
batadv_dat_to_purge(struct batadv_dat_entry * dat_entry)140 static bool batadv_dat_to_purge(struct batadv_dat_entry *dat_entry)
141 {
142 return batadv_has_timed_out(dat_entry->last_update,
143 BATADV_DAT_ENTRY_TIMEOUT);
144 }
145
146 /**
147 * __batadv_dat_purge() - delete entries from the DAT local storage
148 * @bat_priv: the bat priv with all the mesh interface information
149 * @to_purge: function in charge to decide whether an entry has to be purged or
150 * not. This function takes the dat_entry as argument and has to
151 * returns a boolean value: true is the entry has to be deleted,
152 * false otherwise
153 *
154 * Loops over each entry in the DAT local storage and deletes it if and only if
155 * the to_purge function passed as argument returns true.
156 */
__batadv_dat_purge(struct batadv_priv * bat_priv,bool (* to_purge)(struct batadv_dat_entry *))157 static void __batadv_dat_purge(struct batadv_priv *bat_priv,
158 bool (*to_purge)(struct batadv_dat_entry *))
159 {
160 spinlock_t *list_lock; /* protects write access to the hash lists */
161 struct batadv_dat_entry *dat_entry;
162 struct hlist_node *node_tmp;
163 struct hlist_head *head;
164 u32 i;
165
166 if (!bat_priv->dat.hash)
167 return;
168
169 for (i = 0; i < bat_priv->dat.hash->size; i++) {
170 head = &bat_priv->dat.hash->table[i];
171 list_lock = &bat_priv->dat.hash->list_locks[i];
172
173 spin_lock_bh(list_lock);
174 hlist_for_each_entry_safe(dat_entry, node_tmp, head,
175 hash_entry) {
176 /* if a helper function has been passed as parameter,
177 * ask it if the entry has to be purged or not
178 */
179 if (to_purge && !to_purge(dat_entry))
180 continue;
181
182 hlist_del_rcu(&dat_entry->hash_entry);
183 batadv_dat_entry_put(dat_entry);
184 }
185 spin_unlock_bh(list_lock);
186 }
187 }
188
189 /**
190 * batadv_dat_purge() - periodic task that deletes old entries from the local
191 * DAT hash table
192 * @work: kernel work struct
193 */
batadv_dat_purge(struct work_struct * work)194 static void batadv_dat_purge(struct work_struct *work)
195 {
196 struct delayed_work *delayed_work;
197 struct batadv_priv_dat *priv_dat;
198 struct batadv_priv *bat_priv;
199
200 delayed_work = to_delayed_work(work);
201 priv_dat = container_of(delayed_work, struct batadv_priv_dat, work);
202 bat_priv = container_of(priv_dat, struct batadv_priv, dat);
203
204 __batadv_dat_purge(bat_priv, batadv_dat_to_purge);
205 batadv_dat_start_timer(bat_priv);
206 }
207
208 /**
209 * batadv_compare_dat() - comparing function used in the local DAT hash table
210 * @node: node in the local table
211 * @data2: second object to compare the node to
212 *
213 * Return: true if the two entries are the same, false otherwise.
214 */
batadv_compare_dat(const struct hlist_node * node,const void * data2)215 static bool batadv_compare_dat(const struct hlist_node *node, const void *data2)
216 {
217 const void *data1 = container_of(node, struct batadv_dat_entry,
218 hash_entry);
219
220 return memcmp(data1, data2, sizeof(__be32)) == 0;
221 }
222
223 /**
224 * batadv_arp_hw_src() - extract the hw_src field from an ARP packet
225 * @skb: ARP packet
226 * @hdr_size: size of the possible header before the ARP packet
227 *
228 * Return: the value of the hw_src field in the ARP packet.
229 */
batadv_arp_hw_src(struct sk_buff * skb,int hdr_size)230 static u8 *batadv_arp_hw_src(struct sk_buff *skb, int hdr_size)
231 {
232 u8 *addr;
233
234 addr = (u8 *)(skb->data + hdr_size);
235 addr += ETH_HLEN + sizeof(struct arphdr);
236
237 return addr;
238 }
239
240 /**
241 * batadv_arp_ip_src() - extract the ip_src field from an ARP packet
242 * @skb: ARP packet
243 * @hdr_size: size of the possible header before the ARP packet
244 *
245 * Return: the value of the ip_src field in the ARP packet.
246 */
batadv_arp_ip_src(struct sk_buff * skb,int hdr_size)247 static __be32 batadv_arp_ip_src(struct sk_buff *skb, int hdr_size)
248 {
249 return *(__force __be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN);
250 }
251
252 /**
253 * batadv_arp_hw_dst() - extract the hw_dst field from an ARP packet
254 * @skb: ARP packet
255 * @hdr_size: size of the possible header before the ARP packet
256 *
257 * Return: the value of the hw_dst field in the ARP packet.
258 */
batadv_arp_hw_dst(struct sk_buff * skb,int hdr_size)259 static u8 *batadv_arp_hw_dst(struct sk_buff *skb, int hdr_size)
260 {
261 return batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN + 4;
262 }
263
264 /**
265 * batadv_arp_ip_dst() - extract the ip_dst field from an ARP packet
266 * @skb: ARP packet
267 * @hdr_size: size of the possible header before the ARP packet
268 *
269 * Return: the value of the ip_dst field in the ARP packet.
270 */
batadv_arp_ip_dst(struct sk_buff * skb,int hdr_size)271 static __be32 batadv_arp_ip_dst(struct sk_buff *skb, int hdr_size)
272 {
273 u8 *dst = batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4;
274
275 return *(__force __be32 *)dst;
276 }
277
278 /**
279 * batadv_hash_dat() - compute the hash value for an IP address
280 * @data: data to hash
281 * @size: size of the hash table
282 *
283 * Return: the selected index in the hash table for the given data.
284 */
batadv_hash_dat(const void * data,u32 size)285 static u32 batadv_hash_dat(const void *data, u32 size)
286 {
287 u32 hash = 0;
288 const struct batadv_dat_entry *dat = data;
289 const unsigned char *key;
290 __be16 vid;
291 u32 i;
292
293 key = (__force const unsigned char *)&dat->ip;
294 for (i = 0; i < sizeof(dat->ip); i++) {
295 hash += key[i];
296 hash += (hash << 10);
297 hash ^= (hash >> 6);
298 }
299
300 vid = htons(dat->vid);
301 key = (__force const unsigned char *)&vid;
302 for (i = 0; i < sizeof(dat->vid); i++) {
303 hash += key[i];
304 hash += (hash << 10);
305 hash ^= (hash >> 6);
306 }
307
308 hash += (hash << 3);
309 hash ^= (hash >> 11);
310 hash += (hash << 15);
311
312 return hash % size;
313 }
314
315 /**
316 * batadv_dat_entry_hash_find() - look for a given dat_entry in the local hash
317 * table
318 * @bat_priv: the bat priv with all the mesh interface information
319 * @ip: search key
320 * @vid: VLAN identifier
321 *
322 * Return: the dat_entry if found, NULL otherwise.
323 */
324 static struct batadv_dat_entry *
batadv_dat_entry_hash_find(struct batadv_priv * bat_priv,__be32 ip,unsigned short vid)325 batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
326 unsigned short vid)
327 {
328 struct hlist_head *head;
329 struct batadv_dat_entry to_find, *dat_entry, *dat_entry_tmp = NULL;
330 struct batadv_hashtable *hash = bat_priv->dat.hash;
331 u32 index;
332
333 if (!hash)
334 return NULL;
335
336 to_find.ip = ip;
337 to_find.vid = vid;
338
339 index = batadv_hash_dat(&to_find, hash->size);
340 head = &hash->table[index];
341
342 rcu_read_lock();
343 hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
344 if (dat_entry->ip != ip)
345 continue;
346
347 if (!kref_get_unless_zero(&dat_entry->refcount))
348 continue;
349
350 dat_entry_tmp = dat_entry;
351 break;
352 }
353 rcu_read_unlock();
354
355 return dat_entry_tmp;
356 }
357
358 /**
359 * batadv_dat_entry_add() - add a new dat entry or update it if already exists
360 * @bat_priv: the bat priv with all the mesh interface information
361 * @ip: ipv4 to add/edit
362 * @mac_addr: mac address to assign to the given ipv4
363 * @vid: VLAN identifier
364 */
batadv_dat_entry_add(struct batadv_priv * bat_priv,__be32 ip,u8 * mac_addr,unsigned short vid)365 static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
366 u8 *mac_addr, unsigned short vid)
367 {
368 struct batadv_dat_entry *dat_entry;
369 int hash_added;
370
371 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip, vid);
372 /* if this entry is already known, just update it */
373 if (dat_entry) {
374 if (!batadv_compare_eth(dat_entry->mac_addr, mac_addr))
375 ether_addr_copy(dat_entry->mac_addr, mac_addr);
376 dat_entry->last_update = jiffies;
377 batadv_dbg(BATADV_DBG_DAT, bat_priv,
378 "Entry updated: %pI4 %pM (vid: %d)\n",
379 &dat_entry->ip, dat_entry->mac_addr,
380 batadv_print_vid(vid));
381 goto out;
382 }
383
384 dat_entry = kmalloc_obj(*dat_entry, GFP_ATOMIC);
385 if (!dat_entry)
386 goto out;
387
388 dat_entry->ip = ip;
389 dat_entry->vid = vid;
390 ether_addr_copy(dat_entry->mac_addr, mac_addr);
391 dat_entry->last_update = jiffies;
392 kref_init(&dat_entry->refcount);
393
394 kref_get(&dat_entry->refcount);
395 hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
396 batadv_hash_dat, dat_entry,
397 &dat_entry->hash_entry);
398
399 if (unlikely(hash_added != 0)) {
400 /* remove the reference for the hash */
401 batadv_dat_entry_put(dat_entry);
402 goto out;
403 }
404
405 batadv_dbg(BATADV_DBG_DAT, bat_priv, "New entry added: %pI4 %pM (vid: %d)\n",
406 &dat_entry->ip, dat_entry->mac_addr, batadv_print_vid(vid));
407
408 out:
409 batadv_dat_entry_put(dat_entry);
410 }
411
412 #ifdef CONFIG_BATMAN_ADV_DEBUG
413
414 /**
415 * batadv_dbg_arp() - print a debug message containing all the ARP packet
416 * details
417 * @bat_priv: the bat priv with all the mesh interface information
418 * @skb: ARP packet
419 * @hdr_size: size of the possible header before the ARP packet
420 * @msg: message to print together with the debugging information
421 */
batadv_dbg_arp(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size,char * msg)422 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
423 int hdr_size, char *msg)
424 {
425 struct batadv_unicast_4addr_packet *unicast_4addr_packet;
426 struct batadv_bcast_packet *bcast_pkt;
427 u8 *orig_addr;
428 __be32 ip_src, ip_dst;
429
430 if (msg)
431 batadv_dbg(BATADV_DBG_DAT, bat_priv, "%s\n", msg);
432
433 ip_src = batadv_arp_ip_src(skb, hdr_size);
434 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
435 batadv_dbg(BATADV_DBG_DAT, bat_priv,
436 "ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]\n",
437 batadv_arp_hw_src(skb, hdr_size), &ip_src,
438 batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
439
440 if (hdr_size < sizeof(struct batadv_unicast_packet))
441 return;
442
443 unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
444
445 switch (unicast_4addr_packet->u.packet_type) {
446 case BATADV_UNICAST:
447 batadv_dbg(BATADV_DBG_DAT, bat_priv,
448 "* encapsulated within a UNICAST packet\n");
449 break;
450 case BATADV_UNICAST_4ADDR:
451 batadv_dbg(BATADV_DBG_DAT, bat_priv,
452 "* encapsulated within a UNICAST_4ADDR packet (src: %pM)\n",
453 unicast_4addr_packet->src);
454 switch (unicast_4addr_packet->subtype) {
455 case BATADV_P_DAT_DHT_PUT:
456 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_PUT\n");
457 break;
458 case BATADV_P_DAT_DHT_GET:
459 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_GET\n");
460 break;
461 case BATADV_P_DAT_CACHE_REPLY:
462 batadv_dbg(BATADV_DBG_DAT, bat_priv,
463 "* type: DAT_CACHE_REPLY\n");
464 break;
465 case BATADV_P_DATA:
466 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DATA\n");
467 break;
468 default:
469 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: Unknown (%u)!\n",
470 unicast_4addr_packet->u.packet_type);
471 }
472 break;
473 case BATADV_BCAST:
474 bcast_pkt = (struct batadv_bcast_packet *)unicast_4addr_packet;
475 orig_addr = bcast_pkt->orig;
476 batadv_dbg(BATADV_DBG_DAT, bat_priv,
477 "* encapsulated within a BCAST packet (src: %pM)\n",
478 orig_addr);
479 break;
480 default:
481 batadv_dbg(BATADV_DBG_DAT, bat_priv,
482 "* encapsulated within an unknown packet type (0x%x)\n",
483 unicast_4addr_packet->u.packet_type);
484 }
485 }
486
487 #else
488
batadv_dbg_arp(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size,char * msg)489 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
490 int hdr_size, char *msg)
491 {
492 }
493
494 #endif /* CONFIG_BATMAN_ADV_DEBUG */
495
496 /**
497 * batadv_is_orig_node_eligible() - check whether a node can be a DHT candidate
498 * @res: the array with the already selected candidates
499 * @select: number of already selected candidates
500 * @tmp_max: address of the currently evaluated node
501 * @max: current round max address
502 * @last_max: address of the last selected candidate
503 * @candidate: orig_node under evaluation
504 * @max_orig_node: last selected candidate
505 *
506 * Return: true if the node has been elected as next candidate or false
507 * otherwise.
508 */
batadv_is_orig_node_eligible(struct batadv_dat_candidate * res,int select,batadv_dat_addr_t tmp_max,batadv_dat_addr_t max,batadv_dat_addr_t last_max,struct batadv_orig_node * candidate,struct batadv_orig_node * max_orig_node)509 static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
510 int select, batadv_dat_addr_t tmp_max,
511 batadv_dat_addr_t max,
512 batadv_dat_addr_t last_max,
513 struct batadv_orig_node *candidate,
514 struct batadv_orig_node *max_orig_node)
515 {
516 bool ret = false;
517 int j;
518
519 /* check if orig node candidate is running DAT */
520 if (!test_bit(BATADV_ORIG_CAPA_HAS_DAT, &candidate->capabilities))
521 goto out;
522
523 /* Check if this node has already been selected... */
524 for (j = 0; j < select; j++)
525 if (res[j].orig_node == candidate)
526 break;
527 /* ..and possibly skip it */
528 if (j < select)
529 goto out;
530 /* sanity check: has it already been selected? This should not happen */
531 if (tmp_max > last_max)
532 goto out;
533 /* check if during this iteration an originator with a closer dht
534 * address has already been found
535 */
536 if (tmp_max < max)
537 goto out;
538 /* this is an hash collision with the temporary selected node. Choose
539 * the one with the lowest address
540 */
541 if (tmp_max == max && max_orig_node &&
542 batadv_compare_eth(candidate->orig, max_orig_node->orig))
543 goto out;
544
545 ret = true;
546 out:
547 return ret;
548 }
549
550 /**
551 * batadv_choose_next_candidate() - select the next DHT candidate
552 * @bat_priv: the bat priv with all the mesh interface information
553 * @cands: candidates array
554 * @select: number of candidates already present in the array
555 * @ip_key: key to look up in the DHT
556 * @last_max: pointer where the address of the selected candidate will be saved
557 */
batadv_choose_next_candidate(struct batadv_priv * bat_priv,struct batadv_dat_candidate * cands,int select,batadv_dat_addr_t ip_key,batadv_dat_addr_t * last_max)558 static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
559 struct batadv_dat_candidate *cands,
560 int select, batadv_dat_addr_t ip_key,
561 batadv_dat_addr_t *last_max)
562 {
563 batadv_dat_addr_t max = 0;
564 batadv_dat_addr_t tmp_max = 0;
565 struct batadv_orig_node *orig_node, *max_orig_node = NULL;
566 struct batadv_hashtable *hash = bat_priv->orig_hash;
567 struct hlist_head *head;
568 int i;
569
570 /* if no node is eligible as candidate, leave the candidate type as
571 * NOT_FOUND
572 */
573 cands[select].type = BATADV_DAT_CANDIDATE_NOT_FOUND;
574
575 /* iterate over the originator list and find the node with the closest
576 * dat_address which has not been selected yet
577 */
578 for (i = 0; i < hash->size; i++) {
579 head = &hash->table[i];
580
581 rcu_read_lock();
582 hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
583 /* the dht space is a ring using unsigned addresses */
584 tmp_max = BATADV_DAT_ADDR_MAX - orig_node->dat_addr +
585 ip_key;
586
587 if (!batadv_is_orig_node_eligible(cands, select,
588 tmp_max, max,
589 *last_max, orig_node,
590 max_orig_node))
591 continue;
592
593 if (!kref_get_unless_zero(&orig_node->refcount))
594 continue;
595
596 max = tmp_max;
597 batadv_orig_node_put(max_orig_node);
598 max_orig_node = orig_node;
599 }
600 rcu_read_unlock();
601 }
602 if (max_orig_node) {
603 cands[select].type = BATADV_DAT_CANDIDATE_ORIG;
604 cands[select].orig_node = max_orig_node;
605 batadv_dbg(BATADV_DBG_DAT, bat_priv,
606 "dat_select_candidates() %d: selected %pM addr=%u dist=%u\n",
607 select, max_orig_node->orig, max_orig_node->dat_addr,
608 max);
609 }
610 *last_max = max;
611 }
612
613 /**
614 * batadv_dat_select_candidates() - select the nodes which the DHT message has
615 * to be sent to
616 * @bat_priv: the bat priv with all the mesh interface information
617 * @ip_dst: ipv4 to look up in the DHT
618 * @vid: VLAN identifier
619 *
620 * An originator O is selected if and only if its DHT_ID value is one of three
621 * closest values (from the LEFT, with wrap around if needed) then the hash
622 * value of the key. ip_dst is the key.
623 *
624 * Return: the candidate array of size BATADV_DAT_CANDIDATE_NUM.
625 */
626 static struct batadv_dat_candidate *
batadv_dat_select_candidates(struct batadv_priv * bat_priv,__be32 ip_dst,unsigned short vid)627 batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst,
628 unsigned short vid)
629 {
630 int select;
631 batadv_dat_addr_t last_max = BATADV_DAT_ADDR_MAX, ip_key;
632 struct batadv_dat_candidate *res;
633 struct batadv_dat_entry dat;
634
635 if (!bat_priv->orig_hash)
636 return NULL;
637
638 res = kmalloc_objs(*res, BATADV_DAT_CANDIDATES_NUM, GFP_ATOMIC);
639 if (!res)
640 return NULL;
641
642 dat.ip = ip_dst;
643 dat.vid = vid;
644 ip_key = (batadv_dat_addr_t)batadv_hash_dat(&dat,
645 BATADV_DAT_ADDR_MAX);
646
647 batadv_dbg(BATADV_DBG_DAT, bat_priv,
648 "%s(): IP=%pI4 hash(IP)=%u\n", __func__, &ip_dst,
649 ip_key);
650
651 for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
652 batadv_choose_next_candidate(bat_priv, res, select, ip_key,
653 &last_max);
654
655 return res;
656 }
657
658 /**
659 * batadv_dat_forward_data() - copy and send payload to the selected candidates
660 * @bat_priv: the bat priv with all the mesh interface information
661 * @skb: payload to send
662 * @ip: the DHT key
663 * @vid: VLAN identifier
664 * @packet_subtype: unicast4addr packet subtype to use
665 *
666 * This function copies the skb with pskb_copy() and is sent as a unicast packet
667 * to each of the selected candidates.
668 *
669 * Return: true if the packet is sent to at least one candidate, false
670 * otherwise.
671 */
batadv_dat_forward_data(struct batadv_priv * bat_priv,struct sk_buff * skb,__be32 ip,unsigned short vid,int packet_subtype)672 static bool batadv_dat_forward_data(struct batadv_priv *bat_priv,
673 struct sk_buff *skb, __be32 ip,
674 unsigned short vid, int packet_subtype)
675 {
676 int i;
677 bool ret = false;
678 int send_status;
679 struct batadv_neigh_node *neigh_node = NULL;
680 struct sk_buff *tmp_skb;
681 struct batadv_dat_candidate *cand;
682
683 cand = batadv_dat_select_candidates(bat_priv, ip, vid);
684 if (!cand)
685 return ret;
686
687 batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
688
689 for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
690 if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
691 continue;
692
693 neigh_node = batadv_orig_router_get(cand[i].orig_node,
694 BATADV_IF_DEFAULT);
695 if (!neigh_node)
696 goto free_orig;
697
698 tmp_skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
699 if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, tmp_skb,
700 cand[i].orig_node,
701 packet_subtype)) {
702 kfree_skb(tmp_skb);
703 goto free_neigh;
704 }
705
706 send_status = batadv_send_unicast_skb(tmp_skb, neigh_node);
707 if (send_status == NET_XMIT_SUCCESS) {
708 /* count the sent packet */
709 switch (packet_subtype) {
710 case BATADV_P_DAT_DHT_GET:
711 batadv_inc_counter(bat_priv,
712 BATADV_CNT_DAT_GET_TX);
713 break;
714 case BATADV_P_DAT_DHT_PUT:
715 batadv_inc_counter(bat_priv,
716 BATADV_CNT_DAT_PUT_TX);
717 break;
718 }
719
720 /* packet sent to a candidate: return true */
721 ret = true;
722 }
723 free_neigh:
724 batadv_neigh_node_put(neigh_node);
725 free_orig:
726 batadv_orig_node_put(cand[i].orig_node);
727 }
728
729 kfree(cand);
730 return ret;
731 }
732
733 /**
734 * batadv_dat_tvlv_container_update() - update the dat tvlv container after dat
735 * setting change
736 * @bat_priv: the bat priv with all the mesh interface information
737 */
batadv_dat_tvlv_container_update(struct batadv_priv * bat_priv)738 static void batadv_dat_tvlv_container_update(struct batadv_priv *bat_priv)
739 {
740 char dat_mode;
741
742 dat_mode = atomic_read(&bat_priv->distributed_arp_table);
743
744 switch (dat_mode) {
745 case 0:
746 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
747 break;
748 case 1:
749 batadv_tvlv_container_register(bat_priv, BATADV_TVLV_DAT, 1,
750 NULL, 0);
751 break;
752 }
753 }
754
755 /**
756 * batadv_dat_status_update() - update the dat tvlv container after dat
757 * setting change
758 * @net_dev: the mesh interface net device
759 */
batadv_dat_status_update(struct net_device * net_dev)760 void batadv_dat_status_update(struct net_device *net_dev)
761 {
762 struct batadv_priv *bat_priv = netdev_priv(net_dev);
763
764 batadv_dat_tvlv_container_update(bat_priv);
765 }
766
767 /**
768 * batadv_dat_tvlv_ogm_handler_v1() - process incoming dat tvlv container
769 * @bat_priv: the bat priv with all the mesh interface information
770 * @orig: the orig_node of the ogm
771 * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
772 * @tvlv_value: tvlv buffer containing the gateway data
773 * @tvlv_value_len: tvlv buffer length
774 */
batadv_dat_tvlv_ogm_handler_v1(struct batadv_priv * bat_priv,struct batadv_orig_node * orig,u8 flags,void * tvlv_value,u16 tvlv_value_len)775 static void batadv_dat_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
776 struct batadv_orig_node *orig,
777 u8 flags,
778 void *tvlv_value, u16 tvlv_value_len)
779 {
780 if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
781 clear_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
782 else
783 set_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
784 }
785
786 /**
787 * batadv_dat_hash_free() - free the local DAT hash table
788 * @bat_priv: the bat priv with all the mesh interface information
789 */
batadv_dat_hash_free(struct batadv_priv * bat_priv)790 static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
791 {
792 if (!bat_priv->dat.hash)
793 return;
794
795 __batadv_dat_purge(bat_priv, NULL);
796
797 batadv_hash_destroy(bat_priv->dat.hash);
798
799 bat_priv->dat.hash = NULL;
800 }
801
802 /**
803 * batadv_dat_init() - initialise the DAT internals
804 * @bat_priv: the bat priv with all the mesh interface information
805 *
806 * Return: 0 in case of success, a negative error code otherwise
807 */
batadv_dat_init(struct batadv_priv * bat_priv)808 int batadv_dat_init(struct batadv_priv *bat_priv)
809 {
810 if (bat_priv->dat.hash)
811 return 0;
812
813 bat_priv->dat.hash = batadv_hash_new(1024);
814
815 if (!bat_priv->dat.hash)
816 return -ENOMEM;
817
818 INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge);
819 batadv_dat_start_timer(bat_priv);
820
821 batadv_tvlv_handler_register(bat_priv, batadv_dat_tvlv_ogm_handler_v1,
822 NULL, NULL, BATADV_TVLV_DAT, 1,
823 BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
824 batadv_dat_tvlv_container_update(bat_priv);
825 return 0;
826 }
827
828 /**
829 * batadv_dat_free() - free the DAT internals
830 * @bat_priv: the bat priv with all the mesh interface information
831 */
batadv_dat_free(struct batadv_priv * bat_priv)832 void batadv_dat_free(struct batadv_priv *bat_priv)
833 {
834 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
835 batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_DAT, 1);
836
837 cancel_delayed_work_sync(&bat_priv->dat.work);
838
839 batadv_dat_hash_free(bat_priv);
840 }
841
842 /**
843 * batadv_dat_cache_dump_entry() - dump one entry of the DAT cache table to a
844 * netlink socket
845 * @msg: buffer for the message
846 * @portid: netlink port
847 * @cb: Control block containing additional options
848 * @dat_entry: entry to dump
849 *
850 * Return: 0 or error code.
851 */
852 static int
batadv_dat_cache_dump_entry(struct sk_buff * msg,u32 portid,struct netlink_callback * cb,struct batadv_dat_entry * dat_entry)853 batadv_dat_cache_dump_entry(struct sk_buff *msg, u32 portid,
854 struct netlink_callback *cb,
855 struct batadv_dat_entry *dat_entry)
856 {
857 int msecs;
858 void *hdr;
859
860 hdr = genlmsg_put(msg, portid, cb->nlh->nlmsg_seq,
861 &batadv_netlink_family, NLM_F_MULTI,
862 BATADV_CMD_GET_DAT_CACHE);
863 if (!hdr)
864 return -ENOBUFS;
865
866 genl_dump_check_consistent(cb, hdr);
867
868 msecs = jiffies_to_msecs(jiffies - dat_entry->last_update);
869
870 if (nla_put_in_addr(msg, BATADV_ATTR_DAT_CACHE_IP4ADDRESS,
871 dat_entry->ip) ||
872 nla_put(msg, BATADV_ATTR_DAT_CACHE_HWADDRESS, ETH_ALEN,
873 dat_entry->mac_addr) ||
874 nla_put_u16(msg, BATADV_ATTR_DAT_CACHE_VID, dat_entry->vid) ||
875 nla_put_u32(msg, BATADV_ATTR_LAST_SEEN_MSECS, msecs)) {
876 genlmsg_cancel(msg, hdr);
877 return -EMSGSIZE;
878 }
879
880 genlmsg_end(msg, hdr);
881 return 0;
882 }
883
884 /**
885 * batadv_dat_cache_dump_bucket() - dump one bucket of the DAT cache table to
886 * a netlink socket
887 * @msg: buffer for the message
888 * @portid: netlink port
889 * @cb: Control block containing additional options
890 * @hash: hash to dump
891 * @bucket: bucket index to dump
892 * @idx_skip: How many entries to skip
893 *
894 * Return: 0 or error code.
895 */
896 static int
batadv_dat_cache_dump_bucket(struct sk_buff * msg,u32 portid,struct netlink_callback * cb,struct batadv_hashtable * hash,unsigned int bucket,int * idx_skip)897 batadv_dat_cache_dump_bucket(struct sk_buff *msg, u32 portid,
898 struct netlink_callback *cb,
899 struct batadv_hashtable *hash, unsigned int bucket,
900 int *idx_skip)
901 {
902 struct batadv_dat_entry *dat_entry;
903 int idx = 0;
904
905 spin_lock_bh(&hash->list_locks[bucket]);
906 cb->seq = atomic_read(&hash->generation) << 1 | 1;
907
908 hlist_for_each_entry(dat_entry, &hash->table[bucket], hash_entry) {
909 if (idx < *idx_skip)
910 goto skip;
911
912 if (batadv_dat_cache_dump_entry(msg, portid, cb, dat_entry)) {
913 spin_unlock_bh(&hash->list_locks[bucket]);
914 *idx_skip = idx;
915
916 return -EMSGSIZE;
917 }
918
919 skip:
920 idx++;
921 }
922 spin_unlock_bh(&hash->list_locks[bucket]);
923
924 return 0;
925 }
926
927 /**
928 * batadv_dat_cache_dump() - dump DAT cache table to a netlink socket
929 * @msg: buffer for the message
930 * @cb: callback structure containing arguments
931 *
932 * Return: message length.
933 */
batadv_dat_cache_dump(struct sk_buff * msg,struct netlink_callback * cb)934 int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
935 {
936 struct batadv_hard_iface *primary_if = NULL;
937 int portid = NETLINK_CB(cb->skb).portid;
938 struct net_device *mesh_iface;
939 struct batadv_hashtable *hash;
940 struct batadv_priv *bat_priv;
941 int bucket = cb->args[0];
942 int idx = cb->args[1];
943 int ret = 0;
944
945 mesh_iface = batadv_netlink_get_meshif(cb);
946 if (IS_ERR(mesh_iface))
947 return PTR_ERR(mesh_iface);
948
949 bat_priv = netdev_priv(mesh_iface);
950 hash = bat_priv->dat.hash;
951
952 primary_if = batadv_primary_if_get_selected(bat_priv);
953 if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
954 ret = -ENOENT;
955 goto out;
956 }
957
958 while (bucket < hash->size) {
959 if (batadv_dat_cache_dump_bucket(msg, portid, cb, hash, bucket,
960 &idx))
961 break;
962
963 bucket++;
964 idx = 0;
965 }
966
967 cb->args[0] = bucket;
968 cb->args[1] = idx;
969
970 ret = msg->len;
971
972 out:
973 batadv_hardif_put(primary_if);
974
975 dev_put(mesh_iface);
976
977 return ret;
978 }
979
980 /**
981 * batadv_arp_get_type() - parse an ARP packet and gets the type
982 * @bat_priv: the bat priv with all the mesh interface information
983 * @skb: packet to analyse
984 * @hdr_size: size of the possible header before the ARP packet in the skb
985 *
986 * Return: the ARP type if the skb contains a valid ARP packet, 0 otherwise.
987 */
batadv_arp_get_type(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size)988 static u16 batadv_arp_get_type(struct batadv_priv *bat_priv,
989 struct sk_buff *skb, int hdr_size)
990 {
991 struct arphdr *arphdr;
992 struct ethhdr *ethhdr;
993 __be32 ip_src, ip_dst;
994 u8 *hw_src, *hw_dst;
995 u16 type = 0;
996
997 /* pull the ethernet header */
998 if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
999 goto out;
1000
1001 ethhdr = (struct ethhdr *)(skb->data + hdr_size);
1002
1003 if (ethhdr->h_proto != htons(ETH_P_ARP))
1004 goto out;
1005
1006 /* pull the ARP payload */
1007 if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
1008 arp_hdr_len(skb->dev))))
1009 goto out;
1010
1011 arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
1012
1013 /* check whether the ARP packet carries a valid IP information */
1014 if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
1015 goto out;
1016
1017 if (arphdr->ar_pro != htons(ETH_P_IP))
1018 goto out;
1019
1020 if (arphdr->ar_hln != ETH_ALEN)
1021 goto out;
1022
1023 if (arphdr->ar_pln != 4)
1024 goto out;
1025
1026 /* Check for bad reply/request. If the ARP message is not sane, DAT
1027 * will simply ignore it
1028 */
1029 ip_src = batadv_arp_ip_src(skb, hdr_size);
1030 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1031 if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
1032 ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst) ||
1033 ipv4_is_zeronet(ip_src) || ipv4_is_lbcast(ip_src) ||
1034 ipv4_is_zeronet(ip_dst) || ipv4_is_lbcast(ip_dst))
1035 goto out;
1036
1037 hw_src = batadv_arp_hw_src(skb, hdr_size);
1038 if (is_zero_ether_addr(hw_src) || is_multicast_ether_addr(hw_src))
1039 goto out;
1040
1041 /* don't care about the destination MAC address in ARP requests */
1042 if (arphdr->ar_op != htons(ARPOP_REQUEST)) {
1043 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1044 if (is_zero_ether_addr(hw_dst) ||
1045 is_multicast_ether_addr(hw_dst))
1046 goto out;
1047 }
1048
1049 type = ntohs(arphdr->ar_op);
1050 out:
1051 return type;
1052 }
1053
1054 /**
1055 * batadv_dat_get_vid() - extract the VLAN identifier from skb if any
1056 * @skb: the buffer containing the packet to extract the VID from
1057 * @hdr_size: the size of the batman-adv header encapsulating the packet
1058 *
1059 * Return: If the packet embedded in the skb is vlan tagged this function
1060 * returns the VID with the BATADV_VLAN_HAS_TAG flag. Otherwise BATADV_NO_FLAGS
1061 * is returned.
1062 */
batadv_dat_get_vid(struct sk_buff * skb,int * hdr_size)1063 static unsigned short batadv_dat_get_vid(struct sk_buff *skb, int *hdr_size)
1064 {
1065 unsigned short vid;
1066
1067 vid = batadv_get_vid(skb, *hdr_size);
1068
1069 /* ARP parsing functions jump forward of hdr_size + ETH_HLEN.
1070 * If the header contained in the packet is a VLAN one (which is longer)
1071 * hdr_size is updated so that the functions will still skip the
1072 * correct amount of bytes.
1073 */
1074 if (vid & BATADV_VLAN_HAS_TAG)
1075 *hdr_size += VLAN_HLEN;
1076
1077 return vid;
1078 }
1079
1080 /**
1081 * batadv_dat_arp_create_reply() - create an ARP Reply
1082 * @bat_priv: the bat priv with all the mesh interface information
1083 * @ip_src: ARP sender IP
1084 * @ip_dst: ARP target IP
1085 * @hw_src: Ethernet source and ARP sender MAC
1086 * @hw_dst: Ethernet destination and ARP target MAC
1087 * @vid: VLAN identifier (optional, set to zero otherwise)
1088 *
1089 * Creates an ARP Reply from the given values, optionally encapsulated in a
1090 * VLAN header.
1091 *
1092 * Return: An skb containing an ARP Reply.
1093 */
1094 static struct sk_buff *
batadv_dat_arp_create_reply(struct batadv_priv * bat_priv,__be32 ip_src,__be32 ip_dst,u8 * hw_src,u8 * hw_dst,unsigned short vid)1095 batadv_dat_arp_create_reply(struct batadv_priv *bat_priv, __be32 ip_src,
1096 __be32 ip_dst, u8 *hw_src, u8 *hw_dst,
1097 unsigned short vid)
1098 {
1099 struct sk_buff *skb;
1100
1101 skb = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_dst, bat_priv->mesh_iface,
1102 ip_src, hw_dst, hw_src, hw_dst);
1103 if (!skb)
1104 return NULL;
1105
1106 skb_reset_mac_header(skb);
1107
1108 if (vid & BATADV_VLAN_HAS_TAG)
1109 skb = vlan_insert_tag(skb, htons(ETH_P_8021Q),
1110 vid & VLAN_VID_MASK);
1111
1112 return skb;
1113 }
1114
1115 /**
1116 * batadv_dat_snoop_outgoing_arp_request() - snoop the ARP request and try to
1117 * answer using DAT
1118 * @bat_priv: the bat priv with all the mesh interface information
1119 * @skb: packet to check
1120 *
1121 * Return: true if the message has been sent to the dht candidates, false
1122 * otherwise. In case of a positive return value the message has to be enqueued
1123 * to permit the fallback.
1124 */
batadv_dat_snoop_outgoing_arp_request(struct batadv_priv * bat_priv,struct sk_buff * skb)1125 bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
1126 struct sk_buff *skb)
1127 {
1128 u16 type = 0;
1129 __be32 ip_dst, ip_src;
1130 u8 *hw_src;
1131 bool ret = false;
1132 struct batadv_dat_entry *dat_entry = NULL;
1133 struct sk_buff *skb_new;
1134 struct net_device *mesh_iface = bat_priv->mesh_iface;
1135 int hdr_size = 0;
1136 unsigned short vid;
1137
1138 if (!atomic_read(&bat_priv->distributed_arp_table))
1139 goto out;
1140
1141 vid = batadv_dat_get_vid(skb, &hdr_size);
1142
1143 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1144 /* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast
1145 * message to the selected DHT candidates
1146 */
1147 if (type != ARPOP_REQUEST)
1148 goto out;
1149
1150 batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REQUEST");
1151
1152 ip_src = batadv_arp_ip_src(skb, hdr_size);
1153 hw_src = batadv_arp_hw_src(skb, hdr_size);
1154 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1155
1156 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1157
1158 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1159 if (dat_entry) {
1160 /* If the ARP request is destined for a local client the local
1161 * client will answer itself. DAT would only generate a
1162 * duplicate packet.
1163 *
1164 * Moreover, if the mesh-interface is enslaved into a bridge, an
1165 * additional DAT answer may trigger kernel warnings about
1166 * a packet coming from the wrong port.
1167 */
1168 if (batadv_is_my_client(bat_priv, dat_entry->mac_addr, vid)) {
1169 ret = true;
1170 goto out;
1171 }
1172
1173 /* If BLA is enabled, only send ARP replies if we have claimed
1174 * the destination for the ARP request or if no one else of
1175 * the backbone gws belonging to our backbone has claimed the
1176 * destination.
1177 */
1178 if (!batadv_bla_check_claim(bat_priv,
1179 dat_entry->mac_addr, vid)) {
1180 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1181 "Device %pM claimed by another backbone gw. Don't send ARP reply!",
1182 dat_entry->mac_addr);
1183 ret = true;
1184 goto out;
1185 }
1186
1187 skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
1188 dat_entry->mac_addr,
1189 hw_src, vid);
1190 if (!skb_new)
1191 goto out;
1192
1193 skb_new->protocol = eth_type_trans(skb_new, mesh_iface);
1194
1195 batadv_inc_counter(bat_priv, BATADV_CNT_RX);
1196 batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES,
1197 skb->len + ETH_HLEN + hdr_size);
1198
1199 netif_rx(skb_new);
1200 batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
1201 ret = true;
1202 } else {
1203 /* Send the request to the DHT */
1204 ret = batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
1205 BATADV_P_DAT_DHT_GET);
1206 }
1207 out:
1208 batadv_dat_entry_put(dat_entry);
1209 return ret;
1210 }
1211
1212 /**
1213 * batadv_dat_snoop_incoming_arp_request() - snoop the ARP request and try to
1214 * answer using the local DAT storage
1215 * @bat_priv: the bat priv with all the mesh interface information
1216 * @skb: packet to check
1217 * @hdr_size: size of the encapsulation header
1218 *
1219 * Return: true if the request has been answered, false otherwise.
1220 */
batadv_dat_snoop_incoming_arp_request(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size)1221 bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
1222 struct sk_buff *skb, int hdr_size)
1223 {
1224 u16 type;
1225 __be32 ip_src, ip_dst;
1226 u8 *hw_src;
1227 struct sk_buff *skb_new;
1228 struct batadv_dat_entry *dat_entry = NULL;
1229 bool ret = false;
1230 unsigned short vid;
1231 int err;
1232
1233 if (!atomic_read(&bat_priv->distributed_arp_table))
1234 goto out;
1235
1236 vid = batadv_dat_get_vid(skb, &hdr_size);
1237
1238 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1239 if (type != ARPOP_REQUEST)
1240 goto out;
1241
1242 hw_src = batadv_arp_hw_src(skb, hdr_size);
1243 ip_src = batadv_arp_ip_src(skb, hdr_size);
1244 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1245
1246 batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REQUEST");
1247
1248 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1249
1250 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1251 if (!dat_entry)
1252 goto out;
1253
1254 skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
1255 dat_entry->mac_addr, hw_src, vid);
1256 if (!skb_new)
1257 goto out;
1258
1259 /* To preserve backwards compatibility, the node has choose the outgoing
1260 * format based on the incoming request packet type. The assumption is
1261 * that a node not using the 4addr packet format doesn't support it.
1262 */
1263 if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))
1264 err = batadv_send_skb_via_tt_4addr(bat_priv, skb_new,
1265 BATADV_P_DAT_CACHE_REPLY,
1266 NULL, vid);
1267 else
1268 err = batadv_send_skb_via_tt(bat_priv, skb_new, NULL, vid);
1269
1270 if (err != NET_XMIT_DROP) {
1271 batadv_inc_counter(bat_priv, BATADV_CNT_DAT_CACHED_REPLY_TX);
1272 ret = true;
1273 }
1274 out:
1275 batadv_dat_entry_put(dat_entry);
1276 if (ret)
1277 kfree_skb(skb);
1278 return ret;
1279 }
1280
1281 /**
1282 * batadv_dat_snoop_outgoing_arp_reply() - snoop the ARP reply and fill the DHT
1283 * @bat_priv: the bat priv with all the mesh interface information
1284 * @skb: packet to check
1285 */
batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv * bat_priv,struct sk_buff * skb)1286 void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
1287 struct sk_buff *skb)
1288 {
1289 u16 type;
1290 __be32 ip_src, ip_dst;
1291 u8 *hw_src, *hw_dst;
1292 int hdr_size = 0;
1293 unsigned short vid;
1294
1295 if (!atomic_read(&bat_priv->distributed_arp_table))
1296 return;
1297
1298 vid = batadv_dat_get_vid(skb, &hdr_size);
1299
1300 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1301 if (type != ARPOP_REPLY)
1302 return;
1303
1304 batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REPLY");
1305
1306 hw_src = batadv_arp_hw_src(skb, hdr_size);
1307 ip_src = batadv_arp_ip_src(skb, hdr_size);
1308 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1309 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1310
1311 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1312 batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1313
1314 /* Send the ARP reply to the candidates for both the IP addresses that
1315 * the node obtained from the ARP reply
1316 */
1317 batadv_dat_forward_data(bat_priv, skb, ip_src, vid,
1318 BATADV_P_DAT_DHT_PUT);
1319 batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
1320 BATADV_P_DAT_DHT_PUT);
1321 }
1322
1323 /**
1324 * batadv_dat_snoop_incoming_arp_reply() - snoop the ARP reply and fill the
1325 * local DAT storage only
1326 * @bat_priv: the bat priv with all the mesh interface information
1327 * @skb: packet to check
1328 * @hdr_size: size of the encapsulation header
1329 *
1330 * Return: true if the packet was snooped and consumed by DAT. False if the
1331 * packet has to be delivered to the interface
1332 */
batadv_dat_snoop_incoming_arp_reply(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size)1333 bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
1334 struct sk_buff *skb, int hdr_size)
1335 {
1336 struct batadv_dat_entry *dat_entry = NULL;
1337 u16 type;
1338 __be32 ip_src, ip_dst;
1339 u8 *hw_src, *hw_dst;
1340 bool dropped = false;
1341 unsigned short vid;
1342
1343 if (!atomic_read(&bat_priv->distributed_arp_table))
1344 goto out;
1345
1346 vid = batadv_dat_get_vid(skb, &hdr_size);
1347
1348 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1349 if (type != ARPOP_REPLY)
1350 goto out;
1351
1352 batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REPLY");
1353
1354 hw_src = batadv_arp_hw_src(skb, hdr_size);
1355 ip_src = batadv_arp_ip_src(skb, hdr_size);
1356 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1357 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1358
1359 /* If ip_dst is already in cache and has the right mac address,
1360 * drop this frame if this ARP reply is destined for us because it's
1361 * most probably an ARP reply generated by another node of the DHT.
1362 * We have most probably received already a reply earlier. Delivering
1363 * this frame would lead to doubled receive of an ARP reply.
1364 */
1365 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_src, vid);
1366 if (dat_entry && batadv_compare_eth(hw_src, dat_entry->mac_addr)) {
1367 batadv_dbg(BATADV_DBG_DAT, bat_priv, "Doubled ARP reply removed: ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]; dat_entry: %pM-%pI4\n",
1368 hw_src, &ip_src, hw_dst, &ip_dst,
1369 dat_entry->mac_addr, &dat_entry->ip);
1370 dropped = true;
1371 }
1372
1373 /* Update our internal cache with both the IP addresses the node got
1374 * within the ARP reply
1375 */
1376 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1377 batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1378
1379 if (dropped)
1380 goto out;
1381
1382 /* If BLA is enabled, only forward ARP replies if we have claimed the
1383 * source of the ARP reply or if no one else of the same backbone has
1384 * already claimed that client. This prevents that different gateways
1385 * to the same backbone all forward the ARP reply leading to multiple
1386 * replies in the backbone.
1387 */
1388 if (!batadv_bla_check_claim(bat_priv, hw_src, vid)) {
1389 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1390 "Device %pM claimed by another backbone gw. Drop ARP reply.\n",
1391 hw_src);
1392 dropped = true;
1393 goto out;
1394 }
1395
1396 /* if this REPLY is directed to a client of mine, let's deliver the
1397 * packet to the interface
1398 */
1399 dropped = !batadv_is_my_client(bat_priv, hw_dst, vid);
1400
1401 /* if this REPLY is sent on behalf of a client of mine, let's drop the
1402 * packet because the client will reply by itself
1403 */
1404 dropped |= batadv_is_my_client(bat_priv, hw_src, vid);
1405 out:
1406 if (dropped)
1407 kfree_skb(skb);
1408 batadv_dat_entry_put(dat_entry);
1409 /* if dropped == false -> deliver to the interface */
1410 return dropped;
1411 }
1412
1413 /**
1414 * batadv_dat_check_dhcp_ipudp() - check skb for IP+UDP headers valid for DHCP
1415 * @skb: the packet to check
1416 * @ip_src: a buffer to store the IPv4 source address in
1417 *
1418 * Checks whether the given skb has an IP and UDP header valid for a DHCP
1419 * message from a DHCP server. And if so, stores the IPv4 source address in
1420 * the provided buffer.
1421 *
1422 * Return: True if valid, false otherwise.
1423 */
1424 static bool
batadv_dat_check_dhcp_ipudp(struct sk_buff * skb,__be32 * ip_src)1425 batadv_dat_check_dhcp_ipudp(struct sk_buff *skb, __be32 *ip_src)
1426 {
1427 unsigned int offset = skb_network_offset(skb);
1428 struct udphdr *udphdr, _udphdr;
1429 struct iphdr *iphdr, _iphdr;
1430
1431 iphdr = skb_header_pointer(skb, offset, sizeof(_iphdr), &_iphdr);
1432 if (!iphdr || iphdr->version != 4 || iphdr->ihl * 4 < sizeof(_iphdr))
1433 return false;
1434
1435 if (iphdr->protocol != IPPROTO_UDP)
1436 return false;
1437
1438 offset += iphdr->ihl * 4;
1439 skb_set_transport_header(skb, offset);
1440
1441 udphdr = skb_header_pointer(skb, offset, sizeof(_udphdr), &_udphdr);
1442 if (!udphdr || udphdr->source != htons(67))
1443 return false;
1444
1445 *ip_src = get_unaligned(&iphdr->saddr);
1446
1447 return true;
1448 }
1449
1450 /**
1451 * batadv_dat_check_dhcp() - examine packet for valid DHCP message
1452 * @skb: the packet to check
1453 * @proto: ethernet protocol hint (behind a potential vlan)
1454 * @ip_src: a buffer to store the IPv4 source address in
1455 *
1456 * Checks whether the given skb is a valid DHCP packet. And if so, stores the
1457 * IPv4 source address in the provided buffer.
1458 *
1459 * Caller needs to ensure that the skb network header is set correctly.
1460 *
1461 * Return: If skb is a valid DHCP packet, then returns its op code
1462 * (e.g. BOOTREPLY vs. BOOTREQUEST). Otherwise returns -EINVAL.
1463 */
1464 static int
batadv_dat_check_dhcp(struct sk_buff * skb,__be16 proto,__be32 * ip_src)1465 batadv_dat_check_dhcp(struct sk_buff *skb, __be16 proto, __be32 *ip_src)
1466 {
1467 __be32 *magic, _magic;
1468 unsigned int offset;
1469 struct {
1470 __u8 op;
1471 __u8 htype;
1472 __u8 hlen;
1473 __u8 hops;
1474 } *dhcp_h, _dhcp_h;
1475
1476 if (proto != htons(ETH_P_IP))
1477 return -EINVAL;
1478
1479 if (!batadv_dat_check_dhcp_ipudp(skb, ip_src))
1480 return -EINVAL;
1481
1482 offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1483 if (skb->len < offset + sizeof(struct batadv_dhcp_packet))
1484 return -EINVAL;
1485
1486 dhcp_h = skb_header_pointer(skb, offset, sizeof(_dhcp_h), &_dhcp_h);
1487 if (!dhcp_h || dhcp_h->htype != BATADV_HTYPE_ETHERNET ||
1488 dhcp_h->hlen != ETH_ALEN)
1489 return -EINVAL;
1490
1491 offset += offsetof(struct batadv_dhcp_packet, magic);
1492
1493 magic = skb_header_pointer(skb, offset, sizeof(_magic), &_magic);
1494 if (!magic || get_unaligned(magic) != htonl(BATADV_DHCP_MAGIC))
1495 return -EINVAL;
1496
1497 return dhcp_h->op;
1498 }
1499
1500 /**
1501 * batadv_dat_get_dhcp_message_type() - get message type of a DHCP packet
1502 * @skb: the DHCP packet to parse
1503 *
1504 * Iterates over the DHCP options of the given DHCP packet to find a
1505 * DHCP Message Type option and parse it.
1506 *
1507 * Caller needs to ensure that the given skb is a valid DHCP packet and
1508 * that the skb transport header is set correctly.
1509 *
1510 * Return: The found DHCP message type value, if found. -EINVAL otherwise.
1511 */
batadv_dat_get_dhcp_message_type(struct sk_buff * skb)1512 static int batadv_dat_get_dhcp_message_type(struct sk_buff *skb)
1513 {
1514 unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1515 u8 *type, _type;
1516 struct {
1517 u8 type;
1518 u8 len;
1519 } *tl, _tl;
1520
1521 offset += sizeof(struct batadv_dhcp_packet);
1522
1523 while ((tl = skb_header_pointer(skb, offset, sizeof(_tl), &_tl))) {
1524 if (tl->type == BATADV_DHCP_OPT_MSG_TYPE)
1525 break;
1526
1527 if (tl->type == BATADV_DHCP_OPT_END)
1528 break;
1529
1530 if (tl->type == BATADV_DHCP_OPT_PAD)
1531 offset++;
1532 else
1533 offset += tl->len + sizeof(_tl);
1534 }
1535
1536 /* Option Overload Code not supported */
1537 if (!tl || tl->type != BATADV_DHCP_OPT_MSG_TYPE ||
1538 tl->len != sizeof(_type))
1539 return -EINVAL;
1540
1541 offset += sizeof(_tl);
1542
1543 type = skb_header_pointer(skb, offset, sizeof(_type), &_type);
1544 if (!type)
1545 return -EINVAL;
1546
1547 return *type;
1548 }
1549
1550 /**
1551 * batadv_dat_dhcp_get_yiaddr() - get yiaddr from a DHCP packet
1552 * @skb: the DHCP packet to parse
1553 * @buf: a buffer to store the yiaddr in
1554 *
1555 * Caller needs to ensure that the given skb is a valid DHCP packet and
1556 * that the skb transport header is set correctly.
1557 *
1558 * Return: True on success, false otherwise.
1559 */
batadv_dat_dhcp_get_yiaddr(struct sk_buff * skb,__be32 * buf)1560 static bool batadv_dat_dhcp_get_yiaddr(struct sk_buff *skb, __be32 *buf)
1561 {
1562 unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1563 __be32 *yiaddr;
1564
1565 offset += offsetof(struct batadv_dhcp_packet, yiaddr);
1566 yiaddr = skb_header_pointer(skb, offset, BATADV_DHCP_YIADDR_LEN, buf);
1567
1568 if (!yiaddr)
1569 return false;
1570
1571 if (yiaddr != buf)
1572 *buf = get_unaligned(yiaddr);
1573
1574 return true;
1575 }
1576
1577 /**
1578 * batadv_dat_get_dhcp_chaddr() - get chaddr from a DHCP packet
1579 * @skb: the DHCP packet to parse
1580 * @buf: a buffer to store the chaddr in
1581 *
1582 * Caller needs to ensure that the given skb is a valid DHCP packet and
1583 * that the skb transport header is set correctly.
1584 *
1585 * Return: True on success, false otherwise
1586 */
batadv_dat_get_dhcp_chaddr(struct sk_buff * skb,u8 * buf)1587 static bool batadv_dat_get_dhcp_chaddr(struct sk_buff *skb, u8 *buf)
1588 {
1589 unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1590 u8 *chaddr;
1591
1592 offset += offsetof(struct batadv_dhcp_packet, chaddr);
1593 chaddr = skb_header_pointer(skb, offset, BATADV_DHCP_CHADDR_LEN, buf);
1594
1595 if (!chaddr)
1596 return false;
1597
1598 if (chaddr != buf)
1599 memcpy(buf, chaddr, BATADV_DHCP_CHADDR_LEN);
1600
1601 return true;
1602 }
1603
1604 /**
1605 * batadv_dat_put_dhcp() - puts addresses from a DHCP packet into the DHT and
1606 * DAT cache
1607 * @bat_priv: the bat priv with all the mesh interface information
1608 * @chaddr: the DHCP client MAC address
1609 * @yiaddr: the DHCP client IP address
1610 * @hw_dst: the DHCP server MAC address
1611 * @ip_dst: the DHCP server IP address
1612 * @vid: VLAN identifier
1613 *
1614 * Adds given MAC/IP pairs to the local DAT cache and propagates them further
1615 * into the DHT.
1616 *
1617 * For the DHT propagation, client MAC + IP will appear as the ARP Reply
1618 * transmitter (and hw_dst/ip_dst as the target).
1619 */
batadv_dat_put_dhcp(struct batadv_priv * bat_priv,u8 * chaddr,__be32 yiaddr,u8 * hw_dst,__be32 ip_dst,unsigned short vid)1620 static void batadv_dat_put_dhcp(struct batadv_priv *bat_priv, u8 *chaddr,
1621 __be32 yiaddr, u8 *hw_dst, __be32 ip_dst,
1622 unsigned short vid)
1623 {
1624 struct sk_buff *skb;
1625
1626 skb = batadv_dat_arp_create_reply(bat_priv, yiaddr, ip_dst, chaddr,
1627 hw_dst, vid);
1628 if (!skb)
1629 return;
1630
1631 skb_set_network_header(skb, ETH_HLEN);
1632
1633 batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
1634 batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1635
1636 batadv_dat_forward_data(bat_priv, skb, yiaddr, vid,
1637 BATADV_P_DAT_DHT_PUT);
1638 batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
1639 BATADV_P_DAT_DHT_PUT);
1640
1641 consume_skb(skb);
1642
1643 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1644 "Snooped from outgoing DHCPACK (server address): %pI4, %pM (vid: %i)\n",
1645 &ip_dst, hw_dst, batadv_print_vid(vid));
1646 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1647 "Snooped from outgoing DHCPACK (client address): %pI4, %pM (vid: %i)\n",
1648 &yiaddr, chaddr, batadv_print_vid(vid));
1649 }
1650
1651 /**
1652 * batadv_dat_check_dhcp_ack() - examine packet for valid DHCP message
1653 * @skb: the packet to check
1654 * @proto: ethernet protocol hint (behind a potential vlan)
1655 * @ip_src: a buffer to store the IPv4 source address in
1656 * @chaddr: a buffer to store the DHCP Client Hardware Address in
1657 * @yiaddr: a buffer to store the DHCP Your IP Address in
1658 *
1659 * Checks whether the given skb is a valid DHCPACK. And if so, stores the
1660 * IPv4 server source address (ip_src), client MAC address (chaddr) and client
1661 * IPv4 address (yiaddr) in the provided buffers.
1662 *
1663 * Caller needs to ensure that the skb network header is set correctly.
1664 *
1665 * Return: True if the skb is a valid DHCPACK. False otherwise.
1666 */
1667 static bool
batadv_dat_check_dhcp_ack(struct sk_buff * skb,__be16 proto,__be32 * ip_src,u8 * chaddr,__be32 * yiaddr)1668 batadv_dat_check_dhcp_ack(struct sk_buff *skb, __be16 proto, __be32 *ip_src,
1669 u8 *chaddr, __be32 *yiaddr)
1670 {
1671 int type;
1672
1673 type = batadv_dat_check_dhcp(skb, proto, ip_src);
1674 if (type != BATADV_BOOTREPLY)
1675 return false;
1676
1677 type = batadv_dat_get_dhcp_message_type(skb);
1678 if (type != BATADV_DHCPACK)
1679 return false;
1680
1681 if (!batadv_dat_dhcp_get_yiaddr(skb, yiaddr))
1682 return false;
1683
1684 if (!batadv_dat_get_dhcp_chaddr(skb, chaddr))
1685 return false;
1686
1687 return true;
1688 }
1689
1690 /**
1691 * batadv_dat_snoop_outgoing_dhcp_ack() - snoop DHCPACK and fill DAT with it
1692 * @bat_priv: the bat priv with all the mesh interface information
1693 * @skb: the packet to snoop
1694 * @proto: ethernet protocol hint (behind a potential vlan)
1695 * @vid: VLAN identifier
1696 *
1697 * This function first checks whether the given skb is a valid DHCPACK. If
1698 * so then its source MAC and IP as well as its DHCP Client Hardware Address
1699 * field and DHCP Your IP Address field are added to the local DAT cache and
1700 * propagated into the DHT.
1701 *
1702 * Caller needs to ensure that the skb mac and network headers are set
1703 * correctly.
1704 */
batadv_dat_snoop_outgoing_dhcp_ack(struct batadv_priv * bat_priv,struct sk_buff * skb,__be16 proto,unsigned short vid)1705 void batadv_dat_snoop_outgoing_dhcp_ack(struct batadv_priv *bat_priv,
1706 struct sk_buff *skb,
1707 __be16 proto,
1708 unsigned short vid)
1709 {
1710 u8 chaddr[BATADV_DHCP_CHADDR_LEN];
1711 __be32 ip_src, yiaddr;
1712
1713 if (!atomic_read(&bat_priv->distributed_arp_table))
1714 return;
1715
1716 if (!batadv_dat_check_dhcp_ack(skb, proto, &ip_src, chaddr, &yiaddr))
1717 return;
1718
1719 batadv_dat_put_dhcp(bat_priv, chaddr, yiaddr, eth_hdr(skb)->h_source,
1720 ip_src, vid);
1721 }
1722
1723 /**
1724 * batadv_dat_snoop_incoming_dhcp_ack() - snoop DHCPACK and fill DAT cache
1725 * @bat_priv: the bat priv with all the mesh interface information
1726 * @skb: the packet to snoop
1727 * @hdr_size: header size, up to the tail of the batman-adv header
1728 *
1729 * This function first checks whether the given skb is a valid DHCPACK. If
1730 * so then its source MAC and IP as well as its DHCP Client Hardware Address
1731 * field and DHCP Your IP Address field are added to the local DAT cache.
1732 */
batadv_dat_snoop_incoming_dhcp_ack(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size)1733 void batadv_dat_snoop_incoming_dhcp_ack(struct batadv_priv *bat_priv,
1734 struct sk_buff *skb, int hdr_size)
1735 {
1736 u8 chaddr[BATADV_DHCP_CHADDR_LEN];
1737 struct ethhdr *ethhdr;
1738 __be32 ip_src, yiaddr;
1739 unsigned short vid;
1740 __be16 proto;
1741 u8 *hw_src;
1742
1743 if (!atomic_read(&bat_priv->distributed_arp_table))
1744 return;
1745
1746 if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
1747 return;
1748
1749 ethhdr = (struct ethhdr *)(skb->data + hdr_size);
1750 skb_set_network_header(skb, hdr_size + ETH_HLEN);
1751 proto = ethhdr->h_proto;
1752
1753 if (!batadv_dat_check_dhcp_ack(skb, proto, &ip_src, chaddr, &yiaddr))
1754 return;
1755
1756 hw_src = ethhdr->h_source;
1757 vid = batadv_dat_get_vid(skb, &hdr_size);
1758
1759 batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
1760 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1761
1762 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1763 "Snooped from incoming DHCPACK (server address): %pI4, %pM (vid: %i)\n",
1764 &ip_src, hw_src, batadv_print_vid(vid));
1765 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1766 "Snooped from incoming DHCPACK (client address): %pI4, %pM (vid: %i)\n",
1767 &yiaddr, chaddr, batadv_print_vid(vid));
1768 }
1769
1770 /**
1771 * batadv_dat_drop_broadcast_packet() - check if an ARP request has to be
1772 * dropped (because the node has already obtained the reply via DAT) or not
1773 * @bat_priv: the bat priv with all the mesh interface information
1774 * @forw_packet: the broadcast packet
1775 *
1776 * Return: true if the node can drop the packet, false otherwise.
1777 */
batadv_dat_drop_broadcast_packet(struct batadv_priv * bat_priv,struct batadv_forw_packet * forw_packet)1778 bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
1779 struct batadv_forw_packet *forw_packet)
1780 {
1781 u16 type;
1782 __be32 ip_dst;
1783 struct batadv_dat_entry *dat_entry = NULL;
1784 bool ret = false;
1785 int hdr_size = sizeof(struct batadv_bcast_packet);
1786 unsigned short vid;
1787
1788 if (!atomic_read(&bat_priv->distributed_arp_table))
1789 goto out;
1790
1791 /* If this packet is an ARP_REQUEST and the node already has the
1792 * information that it is going to ask, then the packet can be dropped
1793 */
1794 if (batadv_forw_packet_is_rebroadcast(forw_packet))
1795 goto out;
1796
1797 vid = batadv_dat_get_vid(forw_packet->skb, &hdr_size);
1798
1799 type = batadv_arp_get_type(bat_priv, forw_packet->skb, hdr_size);
1800 if (type != ARPOP_REQUEST)
1801 goto out;
1802
1803 ip_dst = batadv_arp_ip_dst(forw_packet->skb, hdr_size);
1804 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1805 /* check if the node already got this entry */
1806 if (!dat_entry) {
1807 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1808 "ARP Request for %pI4: fallback\n", &ip_dst);
1809 goto out;
1810 }
1811
1812 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1813 "ARP Request for %pI4: fallback prevented\n", &ip_dst);
1814 ret = true;
1815
1816 out:
1817 batadv_dat_entry_put(dat_entry);
1818 return ret;
1819 }
1820