1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) 2011-2019 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 <asm/unaligned.h>
11 #include <linux/atomic.h>
12 #include <linux/bitops.h>
13 #include <linux/byteorder/generic.h>
14 #include <linux/errno.h>
15 #include <linux/etherdevice.h>
16 #include <linux/gfp.h>
17 #include <linux/if_arp.h>
18 #include <linux/if_ether.h>
19 #include <linux/if_vlan.h>
20 #include <linux/in.h>
21 #include <linux/ip.h>
22 #include <linux/jiffies.h>
23 #include <linux/kernel.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/seq_file.h>
30 #include <linux/skbuff.h>
31 #include <linux/slab.h>
32 #include <linux/spinlock.h>
33 #include <linux/stddef.h>
34 #include <linux/string.h>
35 #include <linux/udp.h>
36 #include <linux/workqueue.h>
37 #include <net/arp.h>
38 #include <net/genetlink.h>
39 #include <net/netlink.h>
40 #include <net/sock.h>
41 #include <uapi/linux/batman_adv.h>
42
43 #include "bridge_loop_avoidance.h"
44 #include "hard-interface.h"
45 #include "hash.h"
46 #include "log.h"
47 #include "netlink.h"
48 #include "originator.h"
49 #include "send.h"
50 #include "soft-interface.h"
51 #include "translation-table.h"
52 #include "tvlv.h"
53
54 enum batadv_bootpop {
55 BATADV_BOOTREPLY = 2,
56 };
57
58 enum batadv_boothtype {
59 BATADV_HTYPE_ETHERNET = 1,
60 };
61
62 enum batadv_dhcpoptioncode {
63 BATADV_DHCP_OPT_PAD = 0,
64 BATADV_DHCP_OPT_MSG_TYPE = 53,
65 BATADV_DHCP_OPT_END = 255,
66 };
67
68 enum batadv_dhcptype {
69 BATADV_DHCPACK = 5,
70 };
71
72 /* { 99, 130, 83, 99 } */
73 #define BATADV_DHCP_MAGIC 1669485411
74
75 struct batadv_dhcp_packet {
76 __u8 op;
77 __u8 htype;
78 __u8 hlen;
79 __u8 hops;
80 __be32 xid;
81 __be16 secs;
82 __be16 flags;
83 __be32 ciaddr;
84 __be32 yiaddr;
85 __be32 siaddr;
86 __be32 giaddr;
87 __u8 chaddr[16];
88 __u8 sname[64];
89 __u8 file[128];
90 __be32 magic;
91 __u8 options[0];
92 };
93
94 #define BATADV_DHCP_YIADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->yiaddr)
95 #define BATADV_DHCP_CHADDR_LEN sizeof(((struct batadv_dhcp_packet *)0)->chaddr)
96
97 static void batadv_dat_purge(struct work_struct *work);
98
99 /**
100 * batadv_dat_start_timer() - initialise the DAT periodic worker
101 * @bat_priv: the bat priv with all the soft interface information
102 */
batadv_dat_start_timer(struct batadv_priv * bat_priv)103 static void batadv_dat_start_timer(struct batadv_priv *bat_priv)
104 {
105 INIT_DELAYED_WORK(&bat_priv->dat.work, batadv_dat_purge);
106 queue_delayed_work(batadv_event_workqueue, &bat_priv->dat.work,
107 msecs_to_jiffies(10000));
108 }
109
110 /**
111 * batadv_dat_entry_release() - release dat_entry from lists and queue for free
112 * after rcu grace period
113 * @ref: kref pointer of the dat_entry
114 */
batadv_dat_entry_release(struct kref * ref)115 static void batadv_dat_entry_release(struct kref *ref)
116 {
117 struct batadv_dat_entry *dat_entry;
118
119 dat_entry = container_of(ref, struct batadv_dat_entry, refcount);
120
121 kfree_rcu(dat_entry, rcu);
122 }
123
124 /**
125 * batadv_dat_entry_put() - decrement the dat_entry refcounter and possibly
126 * release it
127 * @dat_entry: dat_entry to be free'd
128 */
batadv_dat_entry_put(struct batadv_dat_entry * dat_entry)129 static void batadv_dat_entry_put(struct batadv_dat_entry *dat_entry)
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 soft 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 *(__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 return *(__be32 *)(batadv_arp_hw_src(skb, hdr_size) + ETH_ALEN * 2 + 4);
274 }
275
276 /**
277 * batadv_hash_dat() - compute the hash value for an IP address
278 * @data: data to hash
279 * @size: size of the hash table
280 *
281 * Return: the selected index in the hash table for the given data.
282 */
batadv_hash_dat(const void * data,u32 size)283 static u32 batadv_hash_dat(const void *data, u32 size)
284 {
285 u32 hash = 0;
286 const struct batadv_dat_entry *dat = data;
287 const unsigned char *key;
288 __be16 vid;
289 u32 i;
290
291 key = (const unsigned char *)&dat->ip;
292 for (i = 0; i < sizeof(dat->ip); i++) {
293 hash += key[i];
294 hash += (hash << 10);
295 hash ^= (hash >> 6);
296 }
297
298 vid = htons(dat->vid);
299 key = (__force const unsigned char *)&vid;
300 for (i = 0; i < sizeof(dat->vid); i++) {
301 hash += key[i];
302 hash += (hash << 10);
303 hash ^= (hash >> 6);
304 }
305
306 hash += (hash << 3);
307 hash ^= (hash >> 11);
308 hash += (hash << 15);
309
310 return hash % size;
311 }
312
313 /**
314 * batadv_dat_entry_hash_find() - look for a given dat_entry in the local hash
315 * table
316 * @bat_priv: the bat priv with all the soft interface information
317 * @ip: search key
318 * @vid: VLAN identifier
319 *
320 * Return: the dat_entry if found, NULL otherwise.
321 */
322 static struct batadv_dat_entry *
batadv_dat_entry_hash_find(struct batadv_priv * bat_priv,__be32 ip,unsigned short vid)323 batadv_dat_entry_hash_find(struct batadv_priv *bat_priv, __be32 ip,
324 unsigned short vid)
325 {
326 struct hlist_head *head;
327 struct batadv_dat_entry to_find, *dat_entry, *dat_entry_tmp = NULL;
328 struct batadv_hashtable *hash = bat_priv->dat.hash;
329 u32 index;
330
331 if (!hash)
332 return NULL;
333
334 to_find.ip = ip;
335 to_find.vid = vid;
336
337 index = batadv_hash_dat(&to_find, hash->size);
338 head = &hash->table[index];
339
340 rcu_read_lock();
341 hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
342 if (dat_entry->ip != ip)
343 continue;
344
345 if (!kref_get_unless_zero(&dat_entry->refcount))
346 continue;
347
348 dat_entry_tmp = dat_entry;
349 break;
350 }
351 rcu_read_unlock();
352
353 return dat_entry_tmp;
354 }
355
356 /**
357 * batadv_dat_entry_add() - add a new dat entry or update it if already exists
358 * @bat_priv: the bat priv with all the soft interface information
359 * @ip: ipv4 to add/edit
360 * @mac_addr: mac address to assign to the given ipv4
361 * @vid: VLAN identifier
362 */
batadv_dat_entry_add(struct batadv_priv * bat_priv,__be32 ip,u8 * mac_addr,unsigned short vid)363 static void batadv_dat_entry_add(struct batadv_priv *bat_priv, __be32 ip,
364 u8 *mac_addr, unsigned short vid)
365 {
366 struct batadv_dat_entry *dat_entry;
367 int hash_added;
368
369 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip, vid);
370 /* if this entry is already known, just update it */
371 if (dat_entry) {
372 if (!batadv_compare_eth(dat_entry->mac_addr, mac_addr))
373 ether_addr_copy(dat_entry->mac_addr, mac_addr);
374 dat_entry->last_update = jiffies;
375 batadv_dbg(BATADV_DBG_DAT, bat_priv,
376 "Entry updated: %pI4 %pM (vid: %d)\n",
377 &dat_entry->ip, dat_entry->mac_addr,
378 batadv_print_vid(vid));
379 goto out;
380 }
381
382 dat_entry = kmalloc(sizeof(*dat_entry), GFP_ATOMIC);
383 if (!dat_entry)
384 goto out;
385
386 dat_entry->ip = ip;
387 dat_entry->vid = vid;
388 ether_addr_copy(dat_entry->mac_addr, mac_addr);
389 dat_entry->last_update = jiffies;
390 kref_init(&dat_entry->refcount);
391
392 kref_get(&dat_entry->refcount);
393 hash_added = batadv_hash_add(bat_priv->dat.hash, batadv_compare_dat,
394 batadv_hash_dat, dat_entry,
395 &dat_entry->hash_entry);
396
397 if (unlikely(hash_added != 0)) {
398 /* remove the reference for the hash */
399 batadv_dat_entry_put(dat_entry);
400 goto out;
401 }
402
403 batadv_dbg(BATADV_DBG_DAT, bat_priv, "New entry added: %pI4 %pM (vid: %d)\n",
404 &dat_entry->ip, dat_entry->mac_addr, batadv_print_vid(vid));
405
406 out:
407 if (dat_entry)
408 batadv_dat_entry_put(dat_entry);
409 }
410
411 #ifdef CONFIG_BATMAN_ADV_DEBUG
412
413 /**
414 * batadv_dbg_arp() - print a debug message containing all the ARP packet
415 * details
416 * @bat_priv: the bat priv with all the soft interface information
417 * @skb: ARP packet
418 * @hdr_size: size of the possible header before the ARP packet
419 * @msg: message to print together with the debugging information
420 */
batadv_dbg_arp(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size,char * msg)421 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
422 int hdr_size, char *msg)
423 {
424 struct batadv_unicast_4addr_packet *unicast_4addr_packet;
425 struct batadv_bcast_packet *bcast_pkt;
426 u8 *orig_addr;
427 __be32 ip_src, ip_dst;
428
429 if (msg)
430 batadv_dbg(BATADV_DBG_DAT, bat_priv, "%s\n", msg);
431
432 ip_src = batadv_arp_ip_src(skb, hdr_size);
433 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
434 batadv_dbg(BATADV_DBG_DAT, bat_priv,
435 "ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]\n",
436 batadv_arp_hw_src(skb, hdr_size), &ip_src,
437 batadv_arp_hw_dst(skb, hdr_size), &ip_dst);
438
439 if (hdr_size < sizeof(struct batadv_unicast_packet))
440 return;
441
442 unicast_4addr_packet = (struct batadv_unicast_4addr_packet *)skb->data;
443
444 switch (unicast_4addr_packet->u.packet_type) {
445 case BATADV_UNICAST:
446 batadv_dbg(BATADV_DBG_DAT, bat_priv,
447 "* encapsulated within a UNICAST packet\n");
448 break;
449 case BATADV_UNICAST_4ADDR:
450 batadv_dbg(BATADV_DBG_DAT, bat_priv,
451 "* encapsulated within a UNICAST_4ADDR packet (src: %pM)\n",
452 unicast_4addr_packet->src);
453 switch (unicast_4addr_packet->subtype) {
454 case BATADV_P_DAT_DHT_PUT:
455 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_PUT\n");
456 break;
457 case BATADV_P_DAT_DHT_GET:
458 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DAT_DHT_GET\n");
459 break;
460 case BATADV_P_DAT_CACHE_REPLY:
461 batadv_dbg(BATADV_DBG_DAT, bat_priv,
462 "* type: DAT_CACHE_REPLY\n");
463 break;
464 case BATADV_P_DATA:
465 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: DATA\n");
466 break;
467 default:
468 batadv_dbg(BATADV_DBG_DAT, bat_priv, "* type: Unknown (%u)!\n",
469 unicast_4addr_packet->u.packet_type);
470 }
471 break;
472 case BATADV_BCAST:
473 bcast_pkt = (struct batadv_bcast_packet *)unicast_4addr_packet;
474 orig_addr = bcast_pkt->orig;
475 batadv_dbg(BATADV_DBG_DAT, bat_priv,
476 "* encapsulated within a BCAST packet (src: %pM)\n",
477 orig_addr);
478 break;
479 default:
480 batadv_dbg(BATADV_DBG_DAT, bat_priv,
481 "* encapsulated within an unknown packet type (0x%x)\n",
482 unicast_4addr_packet->u.packet_type);
483 }
484 }
485
486 #else
487
batadv_dbg_arp(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size,char * msg)488 static void batadv_dbg_arp(struct batadv_priv *bat_priv, struct sk_buff *skb,
489 int hdr_size, char *msg)
490 {
491 }
492
493 #endif /* CONFIG_BATMAN_ADV_DEBUG */
494
495 /**
496 * batadv_is_orig_node_eligible() - check whether a node can be a DHT candidate
497 * @res: the array with the already selected candidates
498 * @select: number of already selected candidates
499 * @tmp_max: address of the currently evaluated node
500 * @max: current round max address
501 * @last_max: address of the last selected candidate
502 * @candidate: orig_node under evaluation
503 * @max_orig_node: last selected candidate
504 *
505 * Return: true if the node has been elected as next candidate or false
506 * otherwise.
507 */
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)508 static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
509 int select, batadv_dat_addr_t tmp_max,
510 batadv_dat_addr_t max,
511 batadv_dat_addr_t last_max,
512 struct batadv_orig_node *candidate,
513 struct batadv_orig_node *max_orig_node)
514 {
515 bool ret = false;
516 int j;
517
518 /* check if orig node candidate is running DAT */
519 if (!test_bit(BATADV_ORIG_CAPA_HAS_DAT, &candidate->capabilities))
520 goto out;
521
522 /* Check if this node has already been selected... */
523 for (j = 0; j < select; j++)
524 if (res[j].orig_node == candidate)
525 break;
526 /* ..and possibly skip it */
527 if (j < select)
528 goto out;
529 /* sanity check: has it already been selected? This should not happen */
530 if (tmp_max > last_max)
531 goto out;
532 /* check if during this iteration an originator with a closer dht
533 * address has already been found
534 */
535 if (tmp_max < max)
536 goto out;
537 /* this is an hash collision with the temporary selected node. Choose
538 * the one with the lowest address
539 */
540 if (tmp_max == max && max_orig_node &&
541 batadv_compare_eth(candidate->orig, max_orig_node->orig))
542 goto out;
543
544 ret = true;
545 out:
546 return ret;
547 }
548
549 /**
550 * batadv_choose_next_candidate() - select the next DHT candidate
551 * @bat_priv: the bat priv with all the soft interface information
552 * @cands: candidates array
553 * @select: number of candidates already present in the array
554 * @ip_key: key to look up in the DHT
555 * @last_max: pointer where the address of the selected candidate will be saved
556 */
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)557 static void batadv_choose_next_candidate(struct batadv_priv *bat_priv,
558 struct batadv_dat_candidate *cands,
559 int select, batadv_dat_addr_t ip_key,
560 batadv_dat_addr_t *last_max)
561 {
562 batadv_dat_addr_t max = 0;
563 batadv_dat_addr_t tmp_max = 0;
564 struct batadv_orig_node *orig_node, *max_orig_node = NULL;
565 struct batadv_hashtable *hash = bat_priv->orig_hash;
566 struct hlist_head *head;
567 int i;
568
569 /* if no node is eligible as candidate, leave the candidate type as
570 * NOT_FOUND
571 */
572 cands[select].type = BATADV_DAT_CANDIDATE_NOT_FOUND;
573
574 /* iterate over the originator list and find the node with the closest
575 * dat_address which has not been selected yet
576 */
577 for (i = 0; i < hash->size; i++) {
578 head = &hash->table[i];
579
580 rcu_read_lock();
581 hlist_for_each_entry_rcu(orig_node, head, hash_entry) {
582 /* the dht space is a ring using unsigned addresses */
583 tmp_max = BATADV_DAT_ADDR_MAX - orig_node->dat_addr +
584 ip_key;
585
586 if (!batadv_is_orig_node_eligible(cands, select,
587 tmp_max, max,
588 *last_max, orig_node,
589 max_orig_node))
590 continue;
591
592 if (!kref_get_unless_zero(&orig_node->refcount))
593 continue;
594
595 max = tmp_max;
596 if (max_orig_node)
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 soft 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_array(BATADV_DAT_CANDIDATES_NUM, sizeof(*res),
639 GFP_ATOMIC);
640 if (!res)
641 return NULL;
642
643 dat.ip = ip_dst;
644 dat.vid = vid;
645 ip_key = (batadv_dat_addr_t)batadv_hash_dat(&dat,
646 BATADV_DAT_ADDR_MAX);
647
648 batadv_dbg(BATADV_DBG_DAT, bat_priv,
649 "%s(): IP=%pI4 hash(IP)=%u\n", __func__, &ip_dst,
650 ip_key);
651
652 for (select = 0; select < BATADV_DAT_CANDIDATES_NUM; select++)
653 batadv_choose_next_candidate(bat_priv, res, select, ip_key,
654 &last_max);
655
656 return res;
657 }
658
659 /**
660 * batadv_dat_forward_data() - copy and send payload to the selected candidates
661 * @bat_priv: the bat priv with all the soft interface information
662 * @skb: payload to send
663 * @ip: the DHT key
664 * @vid: VLAN identifier
665 * @packet_subtype: unicast4addr packet subtype to use
666 *
667 * This function copies the skb with pskb_copy() and is sent as unicast packet
668 * to each of the selected candidates.
669 *
670 * Return: true if the packet is sent to at least one candidate, false
671 * otherwise.
672 */
batadv_dat_forward_data(struct batadv_priv * bat_priv,struct sk_buff * skb,__be32 ip,unsigned short vid,int packet_subtype)673 static bool batadv_dat_forward_data(struct batadv_priv *bat_priv,
674 struct sk_buff *skb, __be32 ip,
675 unsigned short vid, int packet_subtype)
676 {
677 int i;
678 bool ret = false;
679 int send_status;
680 struct batadv_neigh_node *neigh_node = NULL;
681 struct sk_buff *tmp_skb;
682 struct batadv_dat_candidate *cand;
683
684 cand = batadv_dat_select_candidates(bat_priv, ip, vid);
685 if (!cand)
686 goto out;
687
688 batadv_dbg(BATADV_DBG_DAT, bat_priv, "DHT_SEND for %pI4\n", &ip);
689
690 for (i = 0; i < BATADV_DAT_CANDIDATES_NUM; i++) {
691 if (cand[i].type == BATADV_DAT_CANDIDATE_NOT_FOUND)
692 continue;
693
694 neigh_node = batadv_orig_router_get(cand[i].orig_node,
695 BATADV_IF_DEFAULT);
696 if (!neigh_node)
697 goto free_orig;
698
699 tmp_skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
700 if (!batadv_send_skb_prepare_unicast_4addr(bat_priv, tmp_skb,
701 cand[i].orig_node,
702 packet_subtype)) {
703 kfree_skb(tmp_skb);
704 goto free_neigh;
705 }
706
707 send_status = batadv_send_unicast_skb(tmp_skb, neigh_node);
708 if (send_status == NET_XMIT_SUCCESS) {
709 /* count the sent packet */
710 switch (packet_subtype) {
711 case BATADV_P_DAT_DHT_GET:
712 batadv_inc_counter(bat_priv,
713 BATADV_CNT_DAT_GET_TX);
714 break;
715 case BATADV_P_DAT_DHT_PUT:
716 batadv_inc_counter(bat_priv,
717 BATADV_CNT_DAT_PUT_TX);
718 break;
719 }
720
721 /* packet sent to a candidate: return true */
722 ret = true;
723 }
724 free_neigh:
725 batadv_neigh_node_put(neigh_node);
726 free_orig:
727 batadv_orig_node_put(cand[i].orig_node);
728 }
729
730 out:
731 kfree(cand);
732 return ret;
733 }
734
735 /**
736 * batadv_dat_tvlv_container_update() - update the dat tvlv container after dat
737 * setting change
738 * @bat_priv: the bat priv with all the soft interface information
739 */
batadv_dat_tvlv_container_update(struct batadv_priv * bat_priv)740 static void batadv_dat_tvlv_container_update(struct batadv_priv *bat_priv)
741 {
742 char dat_mode;
743
744 dat_mode = atomic_read(&bat_priv->distributed_arp_table);
745
746 switch (dat_mode) {
747 case 0:
748 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
749 break;
750 case 1:
751 batadv_tvlv_container_register(bat_priv, BATADV_TVLV_DAT, 1,
752 NULL, 0);
753 break;
754 }
755 }
756
757 /**
758 * batadv_dat_status_update() - update the dat tvlv container after dat
759 * setting change
760 * @net_dev: the soft interface net device
761 */
batadv_dat_status_update(struct net_device * net_dev)762 void batadv_dat_status_update(struct net_device *net_dev)
763 {
764 struct batadv_priv *bat_priv = netdev_priv(net_dev);
765
766 batadv_dat_tvlv_container_update(bat_priv);
767 }
768
769 /**
770 * batadv_dat_tvlv_ogm_handler_v1() - process incoming dat tvlv container
771 * @bat_priv: the bat priv with all the soft interface information
772 * @orig: the orig_node of the ogm
773 * @flags: flags indicating the tvlv state (see batadv_tvlv_handler_flags)
774 * @tvlv_value: tvlv buffer containing the gateway data
775 * @tvlv_value_len: tvlv buffer length
776 */
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)777 static void batadv_dat_tvlv_ogm_handler_v1(struct batadv_priv *bat_priv,
778 struct batadv_orig_node *orig,
779 u8 flags,
780 void *tvlv_value, u16 tvlv_value_len)
781 {
782 if (flags & BATADV_TVLV_HANDLER_OGM_CIFNOTFND)
783 clear_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
784 else
785 set_bit(BATADV_ORIG_CAPA_HAS_DAT, &orig->capabilities);
786 }
787
788 /**
789 * batadv_dat_hash_free() - free the local DAT hash table
790 * @bat_priv: the bat priv with all the soft interface information
791 */
batadv_dat_hash_free(struct batadv_priv * bat_priv)792 static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
793 {
794 if (!bat_priv->dat.hash)
795 return;
796
797 __batadv_dat_purge(bat_priv, NULL);
798
799 batadv_hash_destroy(bat_priv->dat.hash);
800
801 bat_priv->dat.hash = NULL;
802 }
803
804 /**
805 * batadv_dat_init() - initialise the DAT internals
806 * @bat_priv: the bat priv with all the soft interface information
807 *
808 * Return: 0 in case of success, a negative error code otherwise
809 */
batadv_dat_init(struct batadv_priv * bat_priv)810 int batadv_dat_init(struct batadv_priv *bat_priv)
811 {
812 if (bat_priv->dat.hash)
813 return 0;
814
815 bat_priv->dat.hash = batadv_hash_new(1024);
816
817 if (!bat_priv->dat.hash)
818 return -ENOMEM;
819
820 batadv_dat_start_timer(bat_priv);
821
822 batadv_tvlv_handler_register(bat_priv, batadv_dat_tvlv_ogm_handler_v1,
823 NULL, BATADV_TVLV_DAT, 1,
824 BATADV_TVLV_HANDLER_OGM_CIFNOTFND);
825 batadv_dat_tvlv_container_update(bat_priv);
826 return 0;
827 }
828
829 /**
830 * batadv_dat_free() - free the DAT internals
831 * @bat_priv: the bat priv with all the soft interface information
832 */
batadv_dat_free(struct batadv_priv * bat_priv)833 void batadv_dat_free(struct batadv_priv *bat_priv)
834 {
835 batadv_tvlv_container_unregister(bat_priv, BATADV_TVLV_DAT, 1);
836 batadv_tvlv_handler_unregister(bat_priv, BATADV_TVLV_DAT, 1);
837
838 cancel_delayed_work_sync(&bat_priv->dat.work);
839
840 batadv_dat_hash_free(bat_priv);
841 }
842
843 #ifdef CONFIG_BATMAN_ADV_DEBUGFS
844 /**
845 * batadv_dat_cache_seq_print_text() - print the local DAT hash table
846 * @seq: seq file to print on
847 * @offset: not used
848 *
849 * Return: always 0
850 */
batadv_dat_cache_seq_print_text(struct seq_file * seq,void * offset)851 int batadv_dat_cache_seq_print_text(struct seq_file *seq, void *offset)
852 {
853 struct net_device *net_dev = (struct net_device *)seq->private;
854 struct batadv_priv *bat_priv = netdev_priv(net_dev);
855 struct batadv_hashtable *hash = bat_priv->dat.hash;
856 struct batadv_dat_entry *dat_entry;
857 struct batadv_hard_iface *primary_if;
858 struct hlist_head *head;
859 unsigned long last_seen_jiffies;
860 int last_seen_msecs, last_seen_secs, last_seen_mins;
861 u32 i;
862
863 primary_if = batadv_seq_print_text_primary_if_get(seq);
864 if (!primary_if)
865 goto out;
866
867 seq_printf(seq, "Distributed ARP Table (%s):\n", net_dev->name);
868 seq_puts(seq,
869 " IPv4 MAC VID last-seen\n");
870
871 for (i = 0; i < hash->size; i++) {
872 head = &hash->table[i];
873
874 rcu_read_lock();
875 hlist_for_each_entry_rcu(dat_entry, head, hash_entry) {
876 last_seen_jiffies = jiffies - dat_entry->last_update;
877 last_seen_msecs = jiffies_to_msecs(last_seen_jiffies);
878 last_seen_mins = last_seen_msecs / 60000;
879 last_seen_msecs = last_seen_msecs % 60000;
880 last_seen_secs = last_seen_msecs / 1000;
881
882 seq_printf(seq, " * %15pI4 %pM %4i %6i:%02i\n",
883 &dat_entry->ip, dat_entry->mac_addr,
884 batadv_print_vid(dat_entry->vid),
885 last_seen_mins, last_seen_secs);
886 }
887 rcu_read_unlock();
888 }
889
890 out:
891 if (primary_if)
892 batadv_hardif_put(primary_if);
893 return 0;
894 }
895 #endif
896
897 /**
898 * batadv_dat_cache_dump_entry() - dump one entry of the DAT cache table to a
899 * netlink socket
900 * @msg: buffer for the message
901 * @portid: netlink port
902 * @cb: Control block containing additional options
903 * @dat_entry: entry to dump
904 *
905 * Return: 0 or error code.
906 */
907 static int
batadv_dat_cache_dump_entry(struct sk_buff * msg,u32 portid,struct netlink_callback * cb,struct batadv_dat_entry * dat_entry)908 batadv_dat_cache_dump_entry(struct sk_buff *msg, u32 portid,
909 struct netlink_callback *cb,
910 struct batadv_dat_entry *dat_entry)
911 {
912 int msecs;
913 void *hdr;
914
915 hdr = genlmsg_put(msg, portid, cb->nlh->nlmsg_seq,
916 &batadv_netlink_family, NLM_F_MULTI,
917 BATADV_CMD_GET_DAT_CACHE);
918 if (!hdr)
919 return -ENOBUFS;
920
921 genl_dump_check_consistent(cb, hdr);
922
923 msecs = jiffies_to_msecs(jiffies - dat_entry->last_update);
924
925 if (nla_put_in_addr(msg, BATADV_ATTR_DAT_CACHE_IP4ADDRESS,
926 dat_entry->ip) ||
927 nla_put(msg, BATADV_ATTR_DAT_CACHE_HWADDRESS, ETH_ALEN,
928 dat_entry->mac_addr) ||
929 nla_put_u16(msg, BATADV_ATTR_DAT_CACHE_VID, dat_entry->vid) ||
930 nla_put_u32(msg, BATADV_ATTR_LAST_SEEN_MSECS, msecs)) {
931 genlmsg_cancel(msg, hdr);
932 return -EMSGSIZE;
933 }
934
935 genlmsg_end(msg, hdr);
936 return 0;
937 }
938
939 /**
940 * batadv_dat_cache_dump_bucket() - dump one bucket of the DAT cache table to
941 * a netlink socket
942 * @msg: buffer for the message
943 * @portid: netlink port
944 * @cb: Control block containing additional options
945 * @hash: hash to dump
946 * @bucket: bucket index to dump
947 * @idx_skip: How many entries to skip
948 *
949 * Return: 0 or error code.
950 */
951 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)952 batadv_dat_cache_dump_bucket(struct sk_buff *msg, u32 portid,
953 struct netlink_callback *cb,
954 struct batadv_hashtable *hash, unsigned int bucket,
955 int *idx_skip)
956 {
957 struct batadv_dat_entry *dat_entry;
958 int idx = 0;
959
960 spin_lock_bh(&hash->list_locks[bucket]);
961 cb->seq = atomic_read(&hash->generation) << 1 | 1;
962
963 hlist_for_each_entry(dat_entry, &hash->table[bucket], hash_entry) {
964 if (idx < *idx_skip)
965 goto skip;
966
967 if (batadv_dat_cache_dump_entry(msg, portid, cb, dat_entry)) {
968 spin_unlock_bh(&hash->list_locks[bucket]);
969 *idx_skip = idx;
970
971 return -EMSGSIZE;
972 }
973
974 skip:
975 idx++;
976 }
977 spin_unlock_bh(&hash->list_locks[bucket]);
978
979 return 0;
980 }
981
982 /**
983 * batadv_dat_cache_dump() - dump DAT cache table to a netlink socket
984 * @msg: buffer for the message
985 * @cb: callback structure containing arguments
986 *
987 * Return: message length.
988 */
batadv_dat_cache_dump(struct sk_buff * msg,struct netlink_callback * cb)989 int batadv_dat_cache_dump(struct sk_buff *msg, struct netlink_callback *cb)
990 {
991 struct batadv_hard_iface *primary_if = NULL;
992 int portid = NETLINK_CB(cb->skb).portid;
993 struct net *net = sock_net(cb->skb->sk);
994 struct net_device *soft_iface;
995 struct batadv_hashtable *hash;
996 struct batadv_priv *bat_priv;
997 int bucket = cb->args[0];
998 int idx = cb->args[1];
999 int ifindex;
1000 int ret = 0;
1001
1002 ifindex = batadv_netlink_get_ifindex(cb->nlh,
1003 BATADV_ATTR_MESH_IFINDEX);
1004 if (!ifindex)
1005 return -EINVAL;
1006
1007 soft_iface = dev_get_by_index(net, ifindex);
1008 if (!soft_iface || !batadv_softif_is_valid(soft_iface)) {
1009 ret = -ENODEV;
1010 goto out;
1011 }
1012
1013 bat_priv = netdev_priv(soft_iface);
1014 hash = bat_priv->dat.hash;
1015
1016 primary_if = batadv_primary_if_get_selected(bat_priv);
1017 if (!primary_if || primary_if->if_status != BATADV_IF_ACTIVE) {
1018 ret = -ENOENT;
1019 goto out;
1020 }
1021
1022 while (bucket < hash->size) {
1023 if (batadv_dat_cache_dump_bucket(msg, portid, cb, hash, bucket,
1024 &idx))
1025 break;
1026
1027 bucket++;
1028 idx = 0;
1029 }
1030
1031 cb->args[0] = bucket;
1032 cb->args[1] = idx;
1033
1034 ret = msg->len;
1035
1036 out:
1037 if (primary_if)
1038 batadv_hardif_put(primary_if);
1039
1040 if (soft_iface)
1041 dev_put(soft_iface);
1042
1043 return ret;
1044 }
1045
1046 /**
1047 * batadv_arp_get_type() - parse an ARP packet and gets the type
1048 * @bat_priv: the bat priv with all the soft interface information
1049 * @skb: packet to analyse
1050 * @hdr_size: size of the possible header before the ARP packet in the skb
1051 *
1052 * Return: the ARP type if the skb contains a valid ARP packet, 0 otherwise.
1053 */
batadv_arp_get_type(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size)1054 static u16 batadv_arp_get_type(struct batadv_priv *bat_priv,
1055 struct sk_buff *skb, int hdr_size)
1056 {
1057 struct arphdr *arphdr;
1058 struct ethhdr *ethhdr;
1059 __be32 ip_src, ip_dst;
1060 u8 *hw_src, *hw_dst;
1061 u16 type = 0;
1062
1063 /* pull the ethernet header */
1064 if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
1065 goto out;
1066
1067 ethhdr = (struct ethhdr *)(skb->data + hdr_size);
1068
1069 if (ethhdr->h_proto != htons(ETH_P_ARP))
1070 goto out;
1071
1072 /* pull the ARP payload */
1073 if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN +
1074 arp_hdr_len(skb->dev))))
1075 goto out;
1076
1077 arphdr = (struct arphdr *)(skb->data + hdr_size + ETH_HLEN);
1078
1079 /* check whether the ARP packet carries a valid IP information */
1080 if (arphdr->ar_hrd != htons(ARPHRD_ETHER))
1081 goto out;
1082
1083 if (arphdr->ar_pro != htons(ETH_P_IP))
1084 goto out;
1085
1086 if (arphdr->ar_hln != ETH_ALEN)
1087 goto out;
1088
1089 if (arphdr->ar_pln != 4)
1090 goto out;
1091
1092 /* Check for bad reply/request. If the ARP message is not sane, DAT
1093 * will simply ignore it
1094 */
1095 ip_src = batadv_arp_ip_src(skb, hdr_size);
1096 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1097 if (ipv4_is_loopback(ip_src) || ipv4_is_multicast(ip_src) ||
1098 ipv4_is_loopback(ip_dst) || ipv4_is_multicast(ip_dst) ||
1099 ipv4_is_zeronet(ip_src) || ipv4_is_lbcast(ip_src) ||
1100 ipv4_is_zeronet(ip_dst) || ipv4_is_lbcast(ip_dst))
1101 goto out;
1102
1103 hw_src = batadv_arp_hw_src(skb, hdr_size);
1104 if (is_zero_ether_addr(hw_src) || is_multicast_ether_addr(hw_src))
1105 goto out;
1106
1107 /* don't care about the destination MAC address in ARP requests */
1108 if (arphdr->ar_op != htons(ARPOP_REQUEST)) {
1109 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1110 if (is_zero_ether_addr(hw_dst) ||
1111 is_multicast_ether_addr(hw_dst))
1112 goto out;
1113 }
1114
1115 type = ntohs(arphdr->ar_op);
1116 out:
1117 return type;
1118 }
1119
1120 /**
1121 * batadv_dat_get_vid() - extract the VLAN identifier from skb if any
1122 * @skb: the buffer containing the packet to extract the VID from
1123 * @hdr_size: the size of the batman-adv header encapsulating the packet
1124 *
1125 * Return: If the packet embedded in the skb is vlan tagged this function
1126 * returns the VID with the BATADV_VLAN_HAS_TAG flag. Otherwise BATADV_NO_FLAGS
1127 * is returned.
1128 */
batadv_dat_get_vid(struct sk_buff * skb,int * hdr_size)1129 static unsigned short batadv_dat_get_vid(struct sk_buff *skb, int *hdr_size)
1130 {
1131 unsigned short vid;
1132
1133 vid = batadv_get_vid(skb, *hdr_size);
1134
1135 /* ARP parsing functions jump forward of hdr_size + ETH_HLEN.
1136 * If the header contained in the packet is a VLAN one (which is longer)
1137 * hdr_size is updated so that the functions will still skip the
1138 * correct amount of bytes.
1139 */
1140 if (vid & BATADV_VLAN_HAS_TAG)
1141 *hdr_size += VLAN_HLEN;
1142
1143 return vid;
1144 }
1145
1146 /**
1147 * batadv_dat_arp_create_reply() - create an ARP Reply
1148 * @bat_priv: the bat priv with all the soft interface information
1149 * @ip_src: ARP sender IP
1150 * @ip_dst: ARP target IP
1151 * @hw_src: Ethernet source and ARP sender MAC
1152 * @hw_dst: Ethernet destination and ARP target MAC
1153 * @vid: VLAN identifier (optional, set to zero otherwise)
1154 *
1155 * Creates an ARP Reply from the given values, optionally encapsulated in a
1156 * VLAN header.
1157 *
1158 * Return: An skb containing an ARP Reply.
1159 */
1160 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)1161 batadv_dat_arp_create_reply(struct batadv_priv *bat_priv, __be32 ip_src,
1162 __be32 ip_dst, u8 *hw_src, u8 *hw_dst,
1163 unsigned short vid)
1164 {
1165 struct sk_buff *skb;
1166
1167 skb = arp_create(ARPOP_REPLY, ETH_P_ARP, ip_dst, bat_priv->soft_iface,
1168 ip_src, hw_dst, hw_src, hw_dst);
1169 if (!skb)
1170 return NULL;
1171
1172 skb_reset_mac_header(skb);
1173
1174 if (vid & BATADV_VLAN_HAS_TAG)
1175 skb = vlan_insert_tag(skb, htons(ETH_P_8021Q),
1176 vid & VLAN_VID_MASK);
1177
1178 return skb;
1179 }
1180
1181 /**
1182 * batadv_dat_snoop_outgoing_arp_request() - snoop the ARP request and try to
1183 * answer using DAT
1184 * @bat_priv: the bat priv with all the soft interface information
1185 * @skb: packet to check
1186 *
1187 * Return: true if the message has been sent to the dht candidates, false
1188 * otherwise. In case of a positive return value the message has to be enqueued
1189 * to permit the fallback.
1190 */
batadv_dat_snoop_outgoing_arp_request(struct batadv_priv * bat_priv,struct sk_buff * skb)1191 bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
1192 struct sk_buff *skb)
1193 {
1194 u16 type = 0;
1195 __be32 ip_dst, ip_src;
1196 u8 *hw_src;
1197 bool ret = false;
1198 struct batadv_dat_entry *dat_entry = NULL;
1199 struct sk_buff *skb_new;
1200 struct net_device *soft_iface = bat_priv->soft_iface;
1201 int hdr_size = 0;
1202 unsigned short vid;
1203
1204 if (!atomic_read(&bat_priv->distributed_arp_table))
1205 goto out;
1206
1207 vid = batadv_dat_get_vid(skb, &hdr_size);
1208
1209 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1210 /* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast
1211 * message to the selected DHT candidates
1212 */
1213 if (type != ARPOP_REQUEST)
1214 goto out;
1215
1216 batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REQUEST");
1217
1218 ip_src = batadv_arp_ip_src(skb, hdr_size);
1219 hw_src = batadv_arp_hw_src(skb, hdr_size);
1220 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1221
1222 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1223
1224 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1225 if (dat_entry) {
1226 /* If the ARP request is destined for a local client the local
1227 * client will answer itself. DAT would only generate a
1228 * duplicate packet.
1229 *
1230 * Moreover, if the soft-interface is enslaved into a bridge, an
1231 * additional DAT answer may trigger kernel warnings about
1232 * a packet coming from the wrong port.
1233 */
1234 if (batadv_is_my_client(bat_priv, dat_entry->mac_addr, vid)) {
1235 ret = true;
1236 goto out;
1237 }
1238
1239 /* If BLA is enabled, only send ARP replies if we have claimed
1240 * the destination for the ARP request or if no one else of
1241 * the backbone gws belonging to our backbone has claimed the
1242 * destination.
1243 */
1244 if (!batadv_bla_check_claim(bat_priv,
1245 dat_entry->mac_addr, vid)) {
1246 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1247 "Device %pM claimed by another backbone gw. Don't send ARP reply!",
1248 dat_entry->mac_addr);
1249 ret = true;
1250 goto out;
1251 }
1252
1253 skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
1254 dat_entry->mac_addr,
1255 hw_src, vid);
1256 if (!skb_new)
1257 goto out;
1258
1259 skb_new->protocol = eth_type_trans(skb_new, soft_iface);
1260
1261 batadv_inc_counter(bat_priv, BATADV_CNT_RX);
1262 batadv_add_counter(bat_priv, BATADV_CNT_RX_BYTES,
1263 skb->len + ETH_HLEN + hdr_size);
1264
1265 netif_rx(skb_new);
1266 batadv_dbg(BATADV_DBG_DAT, bat_priv, "ARP request replied locally\n");
1267 ret = true;
1268 } else {
1269 /* Send the request to the DHT */
1270 ret = batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
1271 BATADV_P_DAT_DHT_GET);
1272 }
1273 out:
1274 if (dat_entry)
1275 batadv_dat_entry_put(dat_entry);
1276 return ret;
1277 }
1278
1279 /**
1280 * batadv_dat_snoop_incoming_arp_request() - snoop the ARP request and try to
1281 * answer using the local DAT storage
1282 * @bat_priv: the bat priv with all the soft interface information
1283 * @skb: packet to check
1284 * @hdr_size: size of the encapsulation header
1285 *
1286 * Return: true if the request has been answered, false otherwise.
1287 */
batadv_dat_snoop_incoming_arp_request(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size)1288 bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
1289 struct sk_buff *skb, int hdr_size)
1290 {
1291 u16 type;
1292 __be32 ip_src, ip_dst;
1293 u8 *hw_src;
1294 struct sk_buff *skb_new;
1295 struct batadv_dat_entry *dat_entry = NULL;
1296 bool ret = false;
1297 unsigned short vid;
1298 int err;
1299
1300 if (!atomic_read(&bat_priv->distributed_arp_table))
1301 goto out;
1302
1303 vid = batadv_dat_get_vid(skb, &hdr_size);
1304
1305 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1306 if (type != ARPOP_REQUEST)
1307 goto out;
1308
1309 hw_src = batadv_arp_hw_src(skb, hdr_size);
1310 ip_src = batadv_arp_ip_src(skb, hdr_size);
1311 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1312
1313 batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REQUEST");
1314
1315 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1316
1317 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1318 if (!dat_entry)
1319 goto out;
1320
1321 skb_new = batadv_dat_arp_create_reply(bat_priv, ip_dst, ip_src,
1322 dat_entry->mac_addr, hw_src, vid);
1323 if (!skb_new)
1324 goto out;
1325
1326 /* To preserve backwards compatibility, the node has choose the outgoing
1327 * format based on the incoming request packet type. The assumption is
1328 * that a node not using the 4addr packet format doesn't support it.
1329 */
1330 if (hdr_size == sizeof(struct batadv_unicast_4addr_packet))
1331 err = batadv_send_skb_via_tt_4addr(bat_priv, skb_new,
1332 BATADV_P_DAT_CACHE_REPLY,
1333 NULL, vid);
1334 else
1335 err = batadv_send_skb_via_tt(bat_priv, skb_new, NULL, vid);
1336
1337 if (err != NET_XMIT_DROP) {
1338 batadv_inc_counter(bat_priv, BATADV_CNT_DAT_CACHED_REPLY_TX);
1339 ret = true;
1340 }
1341 out:
1342 if (dat_entry)
1343 batadv_dat_entry_put(dat_entry);
1344 if (ret)
1345 kfree_skb(skb);
1346 return ret;
1347 }
1348
1349 /**
1350 * batadv_dat_snoop_outgoing_arp_reply() - snoop the ARP reply and fill the DHT
1351 * @bat_priv: the bat priv with all the soft interface information
1352 * @skb: packet to check
1353 */
batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv * bat_priv,struct sk_buff * skb)1354 void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
1355 struct sk_buff *skb)
1356 {
1357 u16 type;
1358 __be32 ip_src, ip_dst;
1359 u8 *hw_src, *hw_dst;
1360 int hdr_size = 0;
1361 unsigned short vid;
1362
1363 if (!atomic_read(&bat_priv->distributed_arp_table))
1364 return;
1365
1366 vid = batadv_dat_get_vid(skb, &hdr_size);
1367
1368 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1369 if (type != ARPOP_REPLY)
1370 return;
1371
1372 batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing outgoing ARP REPLY");
1373
1374 hw_src = batadv_arp_hw_src(skb, hdr_size);
1375 ip_src = batadv_arp_ip_src(skb, hdr_size);
1376 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1377 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1378
1379 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1380 batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1381
1382 /* Send the ARP reply to the candidates for both the IP addresses that
1383 * the node obtained from the ARP reply
1384 */
1385 batadv_dat_forward_data(bat_priv, skb, ip_src, vid,
1386 BATADV_P_DAT_DHT_PUT);
1387 batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
1388 BATADV_P_DAT_DHT_PUT);
1389 }
1390
1391 /**
1392 * batadv_dat_snoop_incoming_arp_reply() - snoop the ARP reply and fill the
1393 * local DAT storage only
1394 * @bat_priv: the bat priv with all the soft interface information
1395 * @skb: packet to check
1396 * @hdr_size: size of the encapsulation header
1397 *
1398 * Return: true if the packet was snooped and consumed by DAT. False if the
1399 * packet has to be delivered to the interface
1400 */
batadv_dat_snoop_incoming_arp_reply(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size)1401 bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
1402 struct sk_buff *skb, int hdr_size)
1403 {
1404 struct batadv_dat_entry *dat_entry = NULL;
1405 u16 type;
1406 __be32 ip_src, ip_dst;
1407 u8 *hw_src, *hw_dst;
1408 bool dropped = false;
1409 unsigned short vid;
1410
1411 if (!atomic_read(&bat_priv->distributed_arp_table))
1412 goto out;
1413
1414 vid = batadv_dat_get_vid(skb, &hdr_size);
1415
1416 type = batadv_arp_get_type(bat_priv, skb, hdr_size);
1417 if (type != ARPOP_REPLY)
1418 goto out;
1419
1420 batadv_dbg_arp(bat_priv, skb, hdr_size, "Parsing incoming ARP REPLY");
1421
1422 hw_src = batadv_arp_hw_src(skb, hdr_size);
1423 ip_src = batadv_arp_ip_src(skb, hdr_size);
1424 hw_dst = batadv_arp_hw_dst(skb, hdr_size);
1425 ip_dst = batadv_arp_ip_dst(skb, hdr_size);
1426
1427 /* If ip_dst is already in cache and has the right mac address,
1428 * drop this frame if this ARP reply is destined for us because it's
1429 * most probably an ARP reply generated by another node of the DHT.
1430 * We have most probably received already a reply earlier. Delivering
1431 * this frame would lead to doubled receive of an ARP reply.
1432 */
1433 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_src, vid);
1434 if (dat_entry && batadv_compare_eth(hw_src, dat_entry->mac_addr)) {
1435 batadv_dbg(BATADV_DBG_DAT, bat_priv, "Doubled ARP reply removed: ARP MSG = [src: %pM-%pI4 dst: %pM-%pI4]; dat_entry: %pM-%pI4\n",
1436 hw_src, &ip_src, hw_dst, &ip_dst,
1437 dat_entry->mac_addr, &dat_entry->ip);
1438 dropped = true;
1439 }
1440
1441 /* Update our internal cache with both the IP addresses the node got
1442 * within the ARP reply
1443 */
1444 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1445 batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1446
1447 if (dropped)
1448 goto out;
1449
1450 /* If BLA is enabled, only forward ARP replies if we have claimed the
1451 * source of the ARP reply or if no one else of the same backbone has
1452 * already claimed that client. This prevents that different gateways
1453 * to the same backbone all forward the ARP reply leading to multiple
1454 * replies in the backbone.
1455 */
1456 if (!batadv_bla_check_claim(bat_priv, hw_src, vid)) {
1457 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1458 "Device %pM claimed by another backbone gw. Drop ARP reply.\n",
1459 hw_src);
1460 dropped = true;
1461 goto out;
1462 }
1463
1464 /* if this REPLY is directed to a client of mine, let's deliver the
1465 * packet to the interface
1466 */
1467 dropped = !batadv_is_my_client(bat_priv, hw_dst, vid);
1468
1469 /* if this REPLY is sent on behalf of a client of mine, let's drop the
1470 * packet because the client will reply by itself
1471 */
1472 dropped |= batadv_is_my_client(bat_priv, hw_src, vid);
1473 out:
1474 if (dropped)
1475 kfree_skb(skb);
1476 if (dat_entry)
1477 batadv_dat_entry_put(dat_entry);
1478 /* if dropped == false -> deliver to the interface */
1479 return dropped;
1480 }
1481
1482 /**
1483 * batadv_dat_check_dhcp_ipudp() - check skb for IP+UDP headers valid for DHCP
1484 * @skb: the packet to check
1485 * @ip_src: a buffer to store the IPv4 source address in
1486 *
1487 * Checks whether the given skb has an IP and UDP header valid for a DHCP
1488 * message from a DHCP server. And if so, stores the IPv4 source address in
1489 * the provided buffer.
1490 *
1491 * Return: True if valid, false otherwise.
1492 */
1493 static bool
batadv_dat_check_dhcp_ipudp(struct sk_buff * skb,__be32 * ip_src)1494 batadv_dat_check_dhcp_ipudp(struct sk_buff *skb, __be32 *ip_src)
1495 {
1496 unsigned int offset = skb_network_offset(skb);
1497 struct udphdr *udphdr, _udphdr;
1498 struct iphdr *iphdr, _iphdr;
1499
1500 iphdr = skb_header_pointer(skb, offset, sizeof(_iphdr), &_iphdr);
1501 if (!iphdr || iphdr->version != 4 || iphdr->ihl * 4 < sizeof(_iphdr))
1502 return false;
1503
1504 if (iphdr->protocol != IPPROTO_UDP)
1505 return false;
1506
1507 offset += iphdr->ihl * 4;
1508 skb_set_transport_header(skb, offset);
1509
1510 udphdr = skb_header_pointer(skb, offset, sizeof(_udphdr), &_udphdr);
1511 if (!udphdr || udphdr->source != htons(67))
1512 return false;
1513
1514 *ip_src = get_unaligned(&iphdr->saddr);
1515
1516 return true;
1517 }
1518
1519 /**
1520 * batadv_dat_check_dhcp() - examine packet for valid DHCP message
1521 * @skb: the packet to check
1522 * @proto: ethernet protocol hint (behind a potential vlan)
1523 * @ip_src: a buffer to store the IPv4 source address in
1524 *
1525 * Checks whether the given skb is a valid DHCP packet. And if so, stores the
1526 * IPv4 source address in the provided buffer.
1527 *
1528 * Caller needs to ensure that the skb network header is set correctly.
1529 *
1530 * Return: If skb is a valid DHCP packet, then returns its op code
1531 * (e.g. BOOTREPLY vs. BOOTREQUEST). Otherwise returns -EINVAL.
1532 */
1533 static int
batadv_dat_check_dhcp(struct sk_buff * skb,__be16 proto,__be32 * ip_src)1534 batadv_dat_check_dhcp(struct sk_buff *skb, __be16 proto, __be32 *ip_src)
1535 {
1536 __be32 *magic, _magic;
1537 unsigned int offset;
1538 struct {
1539 __u8 op;
1540 __u8 htype;
1541 __u8 hlen;
1542 __u8 hops;
1543 } *dhcp_h, _dhcp_h;
1544
1545 if (proto != htons(ETH_P_IP))
1546 return -EINVAL;
1547
1548 if (!batadv_dat_check_dhcp_ipudp(skb, ip_src))
1549 return -EINVAL;
1550
1551 offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1552 if (skb->len < offset + sizeof(struct batadv_dhcp_packet))
1553 return -EINVAL;
1554
1555 dhcp_h = skb_header_pointer(skb, offset, sizeof(_dhcp_h), &_dhcp_h);
1556 if (!dhcp_h || dhcp_h->htype != BATADV_HTYPE_ETHERNET ||
1557 dhcp_h->hlen != ETH_ALEN)
1558 return -EINVAL;
1559
1560 offset += offsetof(struct batadv_dhcp_packet, magic);
1561
1562 magic = skb_header_pointer(skb, offset, sizeof(_magic), &_magic);
1563 if (!magic || get_unaligned(magic) != htonl(BATADV_DHCP_MAGIC))
1564 return -EINVAL;
1565
1566 return dhcp_h->op;
1567 }
1568
1569 /**
1570 * batadv_dat_get_dhcp_message_type() - get message type of a DHCP packet
1571 * @skb: the DHCP packet to parse
1572 *
1573 * Iterates over the DHCP options of the given DHCP packet to find a
1574 * DHCP Message Type option and parse it.
1575 *
1576 * Caller needs to ensure that the given skb is a valid DHCP packet and
1577 * that the skb transport header is set correctly.
1578 *
1579 * Return: The found DHCP message type value, if found. -EINVAL otherwise.
1580 */
batadv_dat_get_dhcp_message_type(struct sk_buff * skb)1581 static int batadv_dat_get_dhcp_message_type(struct sk_buff *skb)
1582 {
1583 unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1584 u8 *type, _type;
1585 struct {
1586 u8 type;
1587 u8 len;
1588 } *tl, _tl;
1589
1590 offset += sizeof(struct batadv_dhcp_packet);
1591
1592 while ((tl = skb_header_pointer(skb, offset, sizeof(_tl), &_tl))) {
1593 if (tl->type == BATADV_DHCP_OPT_MSG_TYPE)
1594 break;
1595
1596 if (tl->type == BATADV_DHCP_OPT_END)
1597 break;
1598
1599 if (tl->type == BATADV_DHCP_OPT_PAD)
1600 offset++;
1601 else
1602 offset += tl->len + sizeof(_tl);
1603 }
1604
1605 /* Option Overload Code not supported */
1606 if (!tl || tl->type != BATADV_DHCP_OPT_MSG_TYPE ||
1607 tl->len != sizeof(_type))
1608 return -EINVAL;
1609
1610 offset += sizeof(_tl);
1611
1612 type = skb_header_pointer(skb, offset, sizeof(_type), &_type);
1613 if (!type)
1614 return -EINVAL;
1615
1616 return *type;
1617 }
1618
1619 /**
1620 * batadv_dat_get_dhcp_yiaddr() - get yiaddr from a DHCP packet
1621 * @skb: the DHCP packet to parse
1622 * @buf: a buffer to store the yiaddr in
1623 *
1624 * Caller needs to ensure that the given skb is a valid DHCP packet and
1625 * that the skb transport header is set correctly.
1626 *
1627 * Return: True on success, false otherwise.
1628 */
batadv_dat_dhcp_get_yiaddr(struct sk_buff * skb,__be32 * buf)1629 static bool batadv_dat_dhcp_get_yiaddr(struct sk_buff *skb, __be32 *buf)
1630 {
1631 unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1632 __be32 *yiaddr;
1633
1634 offset += offsetof(struct batadv_dhcp_packet, yiaddr);
1635 yiaddr = skb_header_pointer(skb, offset, BATADV_DHCP_YIADDR_LEN, buf);
1636
1637 if (!yiaddr)
1638 return false;
1639
1640 if (yiaddr != buf)
1641 *buf = get_unaligned(yiaddr);
1642
1643 return true;
1644 }
1645
1646 /**
1647 * batadv_dat_get_dhcp_chaddr() - get chaddr from a DHCP packet
1648 * @skb: the DHCP packet to parse
1649 * @buf: a buffer to store the chaddr in
1650 *
1651 * Caller needs to ensure that the given skb is a valid DHCP packet and
1652 * that the skb transport header is set correctly.
1653 *
1654 * Return: True on success, false otherwise
1655 */
batadv_dat_get_dhcp_chaddr(struct sk_buff * skb,u8 * buf)1656 static bool batadv_dat_get_dhcp_chaddr(struct sk_buff *skb, u8 *buf)
1657 {
1658 unsigned int offset = skb_transport_offset(skb) + sizeof(struct udphdr);
1659 u8 *chaddr;
1660
1661 offset += offsetof(struct batadv_dhcp_packet, chaddr);
1662 chaddr = skb_header_pointer(skb, offset, BATADV_DHCP_CHADDR_LEN, buf);
1663
1664 if (!chaddr)
1665 return false;
1666
1667 if (chaddr != buf)
1668 memcpy(buf, chaddr, BATADV_DHCP_CHADDR_LEN);
1669
1670 return true;
1671 }
1672
1673 /**
1674 * batadv_dat_put_dhcp() - puts addresses from a DHCP packet into the DHT and
1675 * DAT cache
1676 * @bat_priv: the bat priv with all the soft interface information
1677 * @chaddr: the DHCP client MAC address
1678 * @yiaddr: the DHCP client IP address
1679 * @hw_dst: the DHCP server MAC address
1680 * @ip_dst: the DHCP server IP address
1681 * @vid: VLAN identifier
1682 *
1683 * Adds given MAC/IP pairs to the local DAT cache and propagates them further
1684 * into the DHT.
1685 *
1686 * For the DHT propagation, client MAC + IP will appear as the ARP Reply
1687 * transmitter (and hw_dst/ip_dst as the target).
1688 */
batadv_dat_put_dhcp(struct batadv_priv * bat_priv,u8 * chaddr,__be32 yiaddr,u8 * hw_dst,__be32 ip_dst,unsigned short vid)1689 static void batadv_dat_put_dhcp(struct batadv_priv *bat_priv, u8 *chaddr,
1690 __be32 yiaddr, u8 *hw_dst, __be32 ip_dst,
1691 unsigned short vid)
1692 {
1693 struct sk_buff *skb;
1694
1695 skb = batadv_dat_arp_create_reply(bat_priv, yiaddr, ip_dst, chaddr,
1696 hw_dst, vid);
1697 if (!skb)
1698 return;
1699
1700 skb_set_network_header(skb, ETH_HLEN);
1701
1702 batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
1703 batadv_dat_entry_add(bat_priv, ip_dst, hw_dst, vid);
1704
1705 batadv_dat_forward_data(bat_priv, skb, yiaddr, vid,
1706 BATADV_P_DAT_DHT_PUT);
1707 batadv_dat_forward_data(bat_priv, skb, ip_dst, vid,
1708 BATADV_P_DAT_DHT_PUT);
1709
1710 consume_skb(skb);
1711
1712 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1713 "Snooped from outgoing DHCPACK (server address): %pI4, %pM (vid: %i)\n",
1714 &ip_dst, hw_dst, batadv_print_vid(vid));
1715 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1716 "Snooped from outgoing DHCPACK (client address): %pI4, %pM (vid: %i)\n",
1717 &yiaddr, chaddr, batadv_print_vid(vid));
1718 }
1719
1720 /**
1721 * batadv_dat_check_dhcp_ack() - examine packet for valid DHCP message
1722 * @skb: the packet to check
1723 * @proto: ethernet protocol hint (behind a potential vlan)
1724 * @ip_src: a buffer to store the IPv4 source address in
1725 * @chaddr: a buffer to store the DHCP Client Hardware Address in
1726 * @yiaddr: a buffer to store the DHCP Your IP Address in
1727 *
1728 * Checks whether the given skb is a valid DHCPACK. And if so, stores the
1729 * IPv4 server source address (ip_src), client MAC address (chaddr) and client
1730 * IPv4 address (yiaddr) in the provided buffers.
1731 *
1732 * Caller needs to ensure that the skb network header is set correctly.
1733 *
1734 * Return: True if the skb is a valid DHCPACK. False otherwise.
1735 */
1736 static bool
batadv_dat_check_dhcp_ack(struct sk_buff * skb,__be16 proto,__be32 * ip_src,u8 * chaddr,__be32 * yiaddr)1737 batadv_dat_check_dhcp_ack(struct sk_buff *skb, __be16 proto, __be32 *ip_src,
1738 u8 *chaddr, __be32 *yiaddr)
1739 {
1740 int type;
1741
1742 type = batadv_dat_check_dhcp(skb, proto, ip_src);
1743 if (type != BATADV_BOOTREPLY)
1744 return false;
1745
1746 type = batadv_dat_get_dhcp_message_type(skb);
1747 if (type != BATADV_DHCPACK)
1748 return false;
1749
1750 if (!batadv_dat_dhcp_get_yiaddr(skb, yiaddr))
1751 return false;
1752
1753 if (!batadv_dat_get_dhcp_chaddr(skb, chaddr))
1754 return false;
1755
1756 return true;
1757 }
1758
1759 /**
1760 * batadv_dat_snoop_outgoing_dhcp_ack() - snoop DHCPACK and fill DAT with it
1761 * @bat_priv: the bat priv with all the soft interface information
1762 * @skb: the packet to snoop
1763 * @proto: ethernet protocol hint (behind a potential vlan)
1764 * @vid: VLAN identifier
1765 *
1766 * This function first checks whether the given skb is a valid DHCPACK. If
1767 * so then its source MAC and IP as well as its DHCP Client Hardware Address
1768 * field and DHCP Your IP Address field are added to the local DAT cache and
1769 * propagated into the DHT.
1770 *
1771 * Caller needs to ensure that the skb mac and network headers are set
1772 * correctly.
1773 */
batadv_dat_snoop_outgoing_dhcp_ack(struct batadv_priv * bat_priv,struct sk_buff * skb,__be16 proto,unsigned short vid)1774 void batadv_dat_snoop_outgoing_dhcp_ack(struct batadv_priv *bat_priv,
1775 struct sk_buff *skb,
1776 __be16 proto,
1777 unsigned short vid)
1778 {
1779 u8 chaddr[BATADV_DHCP_CHADDR_LEN];
1780 __be32 ip_src, yiaddr;
1781
1782 if (!atomic_read(&bat_priv->distributed_arp_table))
1783 return;
1784
1785 if (!batadv_dat_check_dhcp_ack(skb, proto, &ip_src, chaddr, &yiaddr))
1786 return;
1787
1788 batadv_dat_put_dhcp(bat_priv, chaddr, yiaddr, eth_hdr(skb)->h_source,
1789 ip_src, vid);
1790 }
1791
1792 /**
1793 * batadv_dat_snoop_incoming_dhcp_ack() - snoop DHCPACK and fill DAT cache
1794 * @bat_priv: the bat priv with all the soft interface information
1795 * @skb: the packet to snoop
1796 * @hdr_size: header size, up to the tail of the batman-adv header
1797 *
1798 * This function first checks whether the given skb is a valid DHCPACK. If
1799 * so then its source MAC and IP as well as its DHCP Client Hardware Address
1800 * field and DHCP Your IP Address field are added to the local DAT cache.
1801 */
batadv_dat_snoop_incoming_dhcp_ack(struct batadv_priv * bat_priv,struct sk_buff * skb,int hdr_size)1802 void batadv_dat_snoop_incoming_dhcp_ack(struct batadv_priv *bat_priv,
1803 struct sk_buff *skb, int hdr_size)
1804 {
1805 u8 chaddr[BATADV_DHCP_CHADDR_LEN];
1806 struct ethhdr *ethhdr;
1807 __be32 ip_src, yiaddr;
1808 unsigned short vid;
1809 __be16 proto;
1810 u8 *hw_src;
1811
1812 if (!atomic_read(&bat_priv->distributed_arp_table))
1813 return;
1814
1815 if (unlikely(!pskb_may_pull(skb, hdr_size + ETH_HLEN)))
1816 return;
1817
1818 ethhdr = (struct ethhdr *)(skb->data + hdr_size);
1819 skb_set_network_header(skb, hdr_size + ETH_HLEN);
1820 proto = ethhdr->h_proto;
1821
1822 if (!batadv_dat_check_dhcp_ack(skb, proto, &ip_src, chaddr, &yiaddr))
1823 return;
1824
1825 hw_src = ethhdr->h_source;
1826 vid = batadv_dat_get_vid(skb, &hdr_size);
1827
1828 batadv_dat_entry_add(bat_priv, yiaddr, chaddr, vid);
1829 batadv_dat_entry_add(bat_priv, ip_src, hw_src, vid);
1830
1831 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1832 "Snooped from incoming DHCPACK (server address): %pI4, %pM (vid: %i)\n",
1833 &ip_src, hw_src, batadv_print_vid(vid));
1834 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1835 "Snooped from incoming DHCPACK (client address): %pI4, %pM (vid: %i)\n",
1836 &yiaddr, chaddr, batadv_print_vid(vid));
1837 }
1838
1839 /**
1840 * batadv_dat_drop_broadcast_packet() - check if an ARP request has to be
1841 * dropped (because the node has already obtained the reply via DAT) or not
1842 * @bat_priv: the bat priv with all the soft interface information
1843 * @forw_packet: the broadcast packet
1844 *
1845 * Return: true if the node can drop the packet, false otherwise.
1846 */
batadv_dat_drop_broadcast_packet(struct batadv_priv * bat_priv,struct batadv_forw_packet * forw_packet)1847 bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
1848 struct batadv_forw_packet *forw_packet)
1849 {
1850 u16 type;
1851 __be32 ip_dst;
1852 struct batadv_dat_entry *dat_entry = NULL;
1853 bool ret = false;
1854 int hdr_size = sizeof(struct batadv_bcast_packet);
1855 unsigned short vid;
1856
1857 if (!atomic_read(&bat_priv->distributed_arp_table))
1858 goto out;
1859
1860 /* If this packet is an ARP_REQUEST and the node already has the
1861 * information that it is going to ask, then the packet can be dropped
1862 */
1863 if (batadv_forw_packet_is_rebroadcast(forw_packet))
1864 goto out;
1865
1866 vid = batadv_dat_get_vid(forw_packet->skb, &hdr_size);
1867
1868 type = batadv_arp_get_type(bat_priv, forw_packet->skb, hdr_size);
1869 if (type != ARPOP_REQUEST)
1870 goto out;
1871
1872 ip_dst = batadv_arp_ip_dst(forw_packet->skb, hdr_size);
1873 dat_entry = batadv_dat_entry_hash_find(bat_priv, ip_dst, vid);
1874 /* check if the node already got this entry */
1875 if (!dat_entry) {
1876 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1877 "ARP Request for %pI4: fallback\n", &ip_dst);
1878 goto out;
1879 }
1880
1881 batadv_dbg(BATADV_DBG_DAT, bat_priv,
1882 "ARP Request for %pI4: fallback prevented\n", &ip_dst);
1883 ret = true;
1884
1885 out:
1886 if (dat_entry)
1887 batadv_dat_entry_put(dat_entry);
1888 return ret;
1889 }
1890