blob: 3d1dcaa3e8b5af2040ec1cab987d98be876f35f8 [file] [log] [blame]
Simon Wunderliche19f9752014-01-04 18:04:25 +01001/* Copyright (C) 2013-2014 B.A.T.M.A.N. contributors:
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +02002 *
3 * Martin Hundebøll <martin@hundeboll.net>
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of version 2 of the GNU General Public
7 * License as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
Antonio Quartulliebf38fb2013-11-03 20:40:48 +010015 * along with this program; if not, see <http://www.gnu.org/licenses/>.
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +020016 */
17
18#include "main.h"
19#include "fragmentation.h"
20#include "send.h"
21#include "originator.h"
22#include "routing.h"
23#include "hard-interface.h"
24#include "soft-interface.h"
25
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +020026/**
27 * batadv_frag_clear_chain - delete entries in the fragment buffer chain
28 * @head: head of chain with entries.
29 *
30 * Free fragments in the passed hlist. Should be called with appropriate lock.
31 */
32static void batadv_frag_clear_chain(struct hlist_head *head)
33{
34 struct batadv_frag_list_entry *entry;
35 struct hlist_node *node;
36
37 hlist_for_each_entry_safe(entry, node, head, list) {
38 hlist_del(&entry->list);
39 kfree_skb(entry->skb);
40 kfree(entry);
41 }
42}
43
44/**
45 * batadv_frag_purge_orig - free fragments associated to an orig
46 * @orig_node: originator to free fragments from
47 * @check_cb: optional function to tell if an entry should be purged
48 */
49void batadv_frag_purge_orig(struct batadv_orig_node *orig_node,
50 bool (*check_cb)(struct batadv_frag_table_entry *))
51{
52 struct batadv_frag_table_entry *chain;
53 uint8_t i;
54
55 for (i = 0; i < BATADV_FRAG_BUFFER_COUNT; i++) {
56 chain = &orig_node->fragments[i];
57 spin_lock_bh(&orig_node->fragments[i].lock);
58
59 if (!check_cb || check_cb(chain)) {
60 batadv_frag_clear_chain(&orig_node->fragments[i].head);
61 orig_node->fragments[i].size = 0;
62 }
63
64 spin_unlock_bh(&orig_node->fragments[i].lock);
65 }
66}
67
68/**
69 * batadv_frag_size_limit - maximum possible size of packet to be fragmented
70 *
71 * Returns the maximum size of payload that can be fragmented.
72 */
73static int batadv_frag_size_limit(void)
74{
75 int limit = BATADV_FRAG_MAX_FRAG_SIZE;
76
77 limit -= sizeof(struct batadv_frag_packet);
78 limit *= BATADV_FRAG_MAX_FRAGMENTS;
79
80 return limit;
81}
82
83/**
84 * batadv_frag_init_chain - check and prepare fragment chain for new fragment
85 * @chain: chain in fragments table to init
86 * @seqno: sequence number of the received fragment
87 *
88 * Make chain ready for a fragment with sequence number "seqno". Delete existing
89 * entries if they have an "old" sequence number.
90 *
91 * Caller must hold chain->lock.
92 *
93 * Returns true if chain is empty and caller can just insert the new fragment
94 * without searching for the right position.
95 */
96static bool batadv_frag_init_chain(struct batadv_frag_table_entry *chain,
97 uint16_t seqno)
98{
99 if (chain->seqno == seqno)
100 return false;
101
102 if (!hlist_empty(&chain->head))
103 batadv_frag_clear_chain(&chain->head);
104
105 chain->size = 0;
106 chain->seqno = seqno;
107
108 return true;
109}
110
111/**
112 * batadv_frag_insert_packet - insert a fragment into a fragment chain
113 * @orig_node: originator that the fragment was received from
114 * @skb: skb to insert
115 * @chain_out: list head to attach complete chains of fragments to
116 *
117 * Insert a new fragment into the reverse ordered chain in the right table
118 * entry. The hash table entry is cleared if "old" fragments exist in it.
119 *
120 * Returns true if skb is buffered, false on error. If the chain has all the
121 * fragments needed to merge the packet, the chain is moved to the passed head
122 * to avoid locking the chain in the table.
123 */
124static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node,
125 struct sk_buff *skb,
126 struct hlist_head *chain_out)
127{
128 struct batadv_frag_table_entry *chain;
129 struct batadv_frag_list_entry *frag_entry_new = NULL, *frag_entry_curr;
Sven Eckelmannd9124262014-05-26 17:21:39 +0200130 struct batadv_frag_list_entry *frag_entry_last = NULL;
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +0200131 struct batadv_frag_packet *frag_packet;
132 uint8_t bucket;
133 uint16_t seqno, hdr_size = sizeof(struct batadv_frag_packet);
134 bool ret = false;
135
136 /* Linearize packet to avoid linearizing 16 packets in a row when doing
137 * the later merge. Non-linear merge should be added to remove this
138 * linearization.
139 */
140 if (skb_linearize(skb) < 0)
141 goto err;
142
143 frag_packet = (struct batadv_frag_packet *)skb->data;
144 seqno = ntohs(frag_packet->seqno);
145 bucket = seqno % BATADV_FRAG_BUFFER_COUNT;
146
147 frag_entry_new = kmalloc(sizeof(*frag_entry_new), GFP_ATOMIC);
148 if (!frag_entry_new)
149 goto err;
150
151 frag_entry_new->skb = skb;
152 frag_entry_new->no = frag_packet->no;
153
154 /* Select entry in the "chain table" and delete any prior fragments
155 * with another sequence number. batadv_frag_init_chain() returns true,
156 * if the list is empty at return.
157 */
158 chain = &orig_node->fragments[bucket];
159 spin_lock_bh(&chain->lock);
160 if (batadv_frag_init_chain(chain, seqno)) {
161 hlist_add_head(&frag_entry_new->list, &chain->head);
162 chain->size = skb->len - hdr_size;
163 chain->timestamp = jiffies;
164 ret = true;
165 goto out;
166 }
167
168 /* Find the position for the new fragment. */
169 hlist_for_each_entry(frag_entry_curr, &chain->head, list) {
170 /* Drop packet if fragment already exists. */
171 if (frag_entry_curr->no == frag_entry_new->no)
172 goto err_unlock;
173
174 /* Order fragments from highest to lowest. */
175 if (frag_entry_curr->no < frag_entry_new->no) {
176 hlist_add_before(&frag_entry_new->list,
177 &frag_entry_curr->list);
178 chain->size += skb->len - hdr_size;
179 chain->timestamp = jiffies;
180 ret = true;
181 goto out;
182 }
Sven Eckelmannd9124262014-05-26 17:21:39 +0200183
184 /* store current entry because it could be the last in list */
185 frag_entry_last = frag_entry_curr;
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +0200186 }
187
Sven Eckelmannd9124262014-05-26 17:21:39 +0200188 /* Reached the end of the list, so insert after 'frag_entry_last'. */
189 if (likely(frag_entry_last)) {
Sven Eckelmanne050dbe2014-08-15 10:19:39 +0200190 hlist_add_behind(&frag_entry_new->list, &frag_entry_last->list);
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +0200191 chain->size += skb->len - hdr_size;
192 chain->timestamp = jiffies;
193 ret = true;
194 }
195
196out:
197 if (chain->size > batadv_frag_size_limit() ||
198 ntohs(frag_packet->total_size) > batadv_frag_size_limit()) {
199 /* Clear chain if total size of either the list or the packet
200 * exceeds the maximum size of one merged packet.
201 */
202 batadv_frag_clear_chain(&chain->head);
203 chain->size = 0;
204 } else if (ntohs(frag_packet->total_size) == chain->size) {
205 /* All fragments received. Hand over chain to caller. */
206 hlist_move_list(&chain->head, chain_out);
207 chain->size = 0;
208 }
209
210err_unlock:
211 spin_unlock_bh(&chain->lock);
212
213err:
214 if (!ret)
215 kfree(frag_entry_new);
216
217 return ret;
218}
219
220/**
221 * batadv_frag_merge_packets - merge a chain of fragments
222 * @chain: head of chain with fragments
223 * @skb: packet with total size of skb after merging
224 *
225 * Expand the first skb in the chain and copy the content of the remaining
226 * skb's into the expanded one. After doing so, clear the chain.
227 *
228 * Returns the merged skb or NULL on error.
229 */
230static struct sk_buff *
231batadv_frag_merge_packets(struct hlist_head *chain, struct sk_buff *skb)
232{
233 struct batadv_frag_packet *packet;
234 struct batadv_frag_list_entry *entry;
235 struct sk_buff *skb_out = NULL;
236 int size, hdr_size = sizeof(struct batadv_frag_packet);
237
238 /* Make sure incoming skb has non-bogus data. */
239 packet = (struct batadv_frag_packet *)skb->data;
240 size = ntohs(packet->total_size);
241 if (size > batadv_frag_size_limit())
242 goto free;
243
244 /* Remove first entry, as this is the destination for the rest of the
245 * fragments.
246 */
247 entry = hlist_entry(chain->first, struct batadv_frag_list_entry, list);
248 hlist_del(&entry->list);
249 skb_out = entry->skb;
250 kfree(entry);
251
252 /* Make room for the rest of the fragments. */
Sven Eckelmann5b6698b2014-12-20 13:48:55 +0100253 if (pskb_expand_head(skb_out, 0, size - skb_out->len, GFP_ATOMIC) < 0) {
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +0200254 kfree_skb(skb_out);
255 skb_out = NULL;
256 goto free;
257 }
258
259 /* Move the existing MAC header to just before the payload. (Override
260 * the fragment header.)
261 */
262 skb_pull_rcsum(skb_out, hdr_size);
263 memmove(skb_out->data - ETH_HLEN, skb_mac_header(skb_out), ETH_HLEN);
264 skb_set_mac_header(skb_out, -ETH_HLEN);
265 skb_reset_network_header(skb_out);
266 skb_reset_transport_header(skb_out);
267
268 /* Copy the payload of the each fragment into the last skb */
269 hlist_for_each_entry(entry, chain, list) {
270 size = entry->skb->len - hdr_size;
271 memcpy(skb_put(skb_out, size), entry->skb->data + hdr_size,
272 size);
273 }
274
275free:
276 /* Locking is not needed, because 'chain' is not part of any orig. */
277 batadv_frag_clear_chain(chain);
278 return skb_out;
279}
280
281/**
282 * batadv_frag_skb_buffer - buffer fragment for later merge
283 * @skb: skb to buffer
284 * @orig_node_src: originator that the skb is received from
285 *
286 * Add fragment to buffer and merge fragments if possible.
287 *
288 * There are three possible outcomes: 1) Packet is merged: Return true and
289 * set *skb to merged packet; 2) Packet is buffered: Return true and set *skb
290 * to NULL; 3) Error: Return false and leave skb as is.
291 */
292bool batadv_frag_skb_buffer(struct sk_buff **skb,
293 struct batadv_orig_node *orig_node_src)
294{
295 struct sk_buff *skb_out = NULL;
296 struct hlist_head head = HLIST_HEAD_INIT;
297 bool ret = false;
298
299 /* Add packet to buffer and table entry if merge is possible. */
300 if (!batadv_frag_insert_packet(orig_node_src, *skb, &head))
301 goto out_err;
302
303 /* Leave if more fragments are needed to merge. */
304 if (hlist_empty(&head))
305 goto out;
306
307 skb_out = batadv_frag_merge_packets(&head, *skb);
308 if (!skb_out)
309 goto out_err;
310
311out:
312 *skb = skb_out;
313 ret = true;
314out_err:
315 return ret;
316}
317
318/**
319 * batadv_frag_skb_fwd - forward fragments that would exceed MTU when merged
320 * @skb: skb to forward
321 * @recv_if: interface that the skb is received on
322 * @orig_node_src: originator that the skb is received from
323 *
324 * Look up the next-hop of the fragments payload and check if the merged packet
325 * will exceed the MTU towards the next-hop. If so, the fragment is forwarded
326 * without merging it.
327 *
328 * Returns true if the fragment is consumed/forwarded, false otherwise.
329 */
330bool batadv_frag_skb_fwd(struct sk_buff *skb,
331 struct batadv_hard_iface *recv_if,
332 struct batadv_orig_node *orig_node_src)
333{
334 struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
335 struct batadv_orig_node *orig_node_dst = NULL;
336 struct batadv_neigh_node *neigh_node = NULL;
337 struct batadv_frag_packet *packet;
338 uint16_t total_size;
339 bool ret = false;
340
341 packet = (struct batadv_frag_packet *)skb->data;
342 orig_node_dst = batadv_orig_hash_find(bat_priv, packet->dest);
343 if (!orig_node_dst)
344 goto out;
345
346 neigh_node = batadv_find_router(bat_priv, orig_node_dst, recv_if);
347 if (!neigh_node)
348 goto out;
349
350 /* Forward the fragment, if the merged packet would be too big to
351 * be assembled.
352 */
353 total_size = ntohs(packet->total_size);
354 if (total_size > neigh_node->if_incoming->net_dev->mtu) {
355 batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_FWD);
356 batadv_add_counter(bat_priv, BATADV_CNT_FRAG_FWD_BYTES,
357 skb->len + ETH_HLEN);
358
Simon Wunderlicha40d9b02013-12-02 20:38:31 +0100359 packet->ttl--;
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +0200360 batadv_send_skb_packet(skb, neigh_node->if_incoming,
361 neigh_node->addr);
362 ret = true;
363 }
364
365out:
366 if (orig_node_dst)
367 batadv_orig_node_free_ref(orig_node_dst);
368 if (neigh_node)
369 batadv_neigh_node_free_ref(neigh_node);
370 return ret;
371}
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200372
373/**
374 * batadv_frag_create - create a fragment from skb
375 * @skb: skb to create fragment from
376 * @frag_head: header to use in new fragment
377 * @mtu: size of new fragment
378 *
379 * Split the passed skb into two fragments: A new one with size matching the
380 * passed mtu and the old one with the rest. The new skb contains data from the
381 * tail of the old skb.
382 *
383 * Returns the new fragment, NULL on error.
384 */
385static struct sk_buff *batadv_frag_create(struct sk_buff *skb,
386 struct batadv_frag_packet *frag_head,
387 unsigned int mtu)
388{
389 struct sk_buff *skb_fragment;
390 unsigned header_size = sizeof(*frag_head);
391 unsigned fragment_size = mtu - header_size;
392
393 skb_fragment = netdev_alloc_skb(NULL, mtu + ETH_HLEN);
394 if (!skb_fragment)
395 goto err;
396
397 skb->priority = TC_PRIO_CONTROL;
398
399 /* Eat the last mtu-bytes of the skb */
400 skb_reserve(skb_fragment, header_size + ETH_HLEN);
401 skb_split(skb, skb_fragment, skb->len - fragment_size);
402
403 /* Add the header */
404 skb_push(skb_fragment, header_size);
405 memcpy(skb_fragment->data, frag_head, header_size);
406
407err:
408 return skb_fragment;
409}
410
411/**
412 * batadv_frag_send_packet - create up to 16 fragments from the passed skb
413 * @skb: skb to create fragments from
414 * @orig_node: final destination of the created fragments
415 * @neigh_node: next-hop of the created fragments
416 *
417 * Returns true on success, false otherwise.
418 */
419bool batadv_frag_send_packet(struct sk_buff *skb,
420 struct batadv_orig_node *orig_node,
421 struct batadv_neigh_node *neigh_node)
422{
423 struct batadv_priv *bat_priv;
Antonio Quartullibe181012014-04-23 14:05:16 +0200424 struct batadv_hard_iface *primary_if = NULL;
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200425 struct batadv_frag_packet frag_header;
426 struct sk_buff *skb_fragment;
427 unsigned mtu = neigh_node->if_incoming->net_dev->mtu;
428 unsigned header_size = sizeof(frag_header);
429 unsigned max_fragment_size, max_packet_size;
Antonio Quartullibe181012014-04-23 14:05:16 +0200430 bool ret = false;
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200431
432 /* To avoid merge and refragmentation at next-hops we never send
433 * fragments larger than BATADV_FRAG_MAX_FRAG_SIZE
434 */
435 mtu = min_t(unsigned, mtu, BATADV_FRAG_MAX_FRAG_SIZE);
Sven Eckelmann0402e442014-12-20 13:48:56 +0100436 max_fragment_size = mtu - header_size;
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200437 max_packet_size = max_fragment_size * BATADV_FRAG_MAX_FRAGMENTS;
438
439 /* Don't even try to fragment, if we need more than 16 fragments */
440 if (skb->len > max_packet_size)
441 goto out_err;
442
443 bat_priv = orig_node->bat_priv;
444 primary_if = batadv_primary_if_get_selected(bat_priv);
445 if (!primary_if)
446 goto out_err;
447
448 /* Create one header to be copied to all fragments */
Simon Wunderlicha40d9b02013-12-02 20:38:31 +0100449 frag_header.packet_type = BATADV_UNICAST_FRAG;
450 frag_header.version = BATADV_COMPAT_VERSION;
451 frag_header.ttl = BATADV_TTL;
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200452 frag_header.seqno = htons(atomic_inc_return(&bat_priv->frag_seqno));
453 frag_header.reserved = 0;
454 frag_header.no = 0;
455 frag_header.total_size = htons(skb->len);
Antonio Quartulli8fdd0152014-01-22 00:42:11 +0100456 ether_addr_copy(frag_header.orig, primary_if->net_dev->dev_addr);
457 ether_addr_copy(frag_header.dest, orig_node->orig);
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200458
459 /* Eat and send fragments from the tail of skb */
460 while (skb->len > max_fragment_size) {
461 skb_fragment = batadv_frag_create(skb, &frag_header, mtu);
462 if (!skb_fragment)
463 goto out_err;
464
465 batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX);
466 batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES,
467 skb_fragment->len + ETH_HLEN);
468 batadv_send_skb_packet(skb_fragment, neigh_node->if_incoming,
469 neigh_node->addr);
470 frag_header.no++;
471
472 /* The initial check in this function should cover this case */
473 if (frag_header.no == BATADV_FRAG_MAX_FRAGMENTS - 1)
474 goto out_err;
475 }
476
477 /* Make room for the fragment header. */
478 if (batadv_skb_head_push(skb, header_size) < 0 ||
479 pskb_expand_head(skb, header_size + ETH_HLEN, 0, GFP_ATOMIC) < 0)
480 goto out_err;
481
482 memcpy(skb->data, &frag_header, header_size);
483
484 /* Send the last fragment */
485 batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX);
486 batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES,
487 skb->len + ETH_HLEN);
488 batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
489
Antonio Quartullibe181012014-04-23 14:05:16 +0200490 ret = true;
491
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200492out_err:
Antonio Quartullibe181012014-04-23 14:05:16 +0200493 if (primary_if)
494 batadv_hardif_free_ref(primary_if);
495
496 return ret;
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200497}