blob: fc1835c6bb4099e50e75f964826b0aacdd7200f0 [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
26
27/**
28 * batadv_frag_clear_chain - delete entries in the fragment buffer chain
29 * @head: head of chain with entries.
30 *
31 * Free fragments in the passed hlist. Should be called with appropriate lock.
32 */
33static void batadv_frag_clear_chain(struct hlist_head *head)
34{
35 struct batadv_frag_list_entry *entry;
36 struct hlist_node *node;
37
38 hlist_for_each_entry_safe(entry, node, head, list) {
39 hlist_del(&entry->list);
40 kfree_skb(entry->skb);
41 kfree(entry);
42 }
43}
44
45/**
46 * batadv_frag_purge_orig - free fragments associated to an orig
47 * @orig_node: originator to free fragments from
48 * @check_cb: optional function to tell if an entry should be purged
49 */
50void batadv_frag_purge_orig(struct batadv_orig_node *orig_node,
51 bool (*check_cb)(struct batadv_frag_table_entry *))
52{
53 struct batadv_frag_table_entry *chain;
54 uint8_t i;
55
56 for (i = 0; i < BATADV_FRAG_BUFFER_COUNT; i++) {
57 chain = &orig_node->fragments[i];
58 spin_lock_bh(&orig_node->fragments[i].lock);
59
60 if (!check_cb || check_cb(chain)) {
61 batadv_frag_clear_chain(&orig_node->fragments[i].head);
62 orig_node->fragments[i].size = 0;
63 }
64
65 spin_unlock_bh(&orig_node->fragments[i].lock);
66 }
67}
68
69/**
70 * batadv_frag_size_limit - maximum possible size of packet to be fragmented
71 *
72 * Returns the maximum size of payload that can be fragmented.
73 */
74static int batadv_frag_size_limit(void)
75{
76 int limit = BATADV_FRAG_MAX_FRAG_SIZE;
77
78 limit -= sizeof(struct batadv_frag_packet);
79 limit *= BATADV_FRAG_MAX_FRAGMENTS;
80
81 return limit;
82}
83
84/**
85 * batadv_frag_init_chain - check and prepare fragment chain for new fragment
86 * @chain: chain in fragments table to init
87 * @seqno: sequence number of the received fragment
88 *
89 * Make chain ready for a fragment with sequence number "seqno". Delete existing
90 * entries if they have an "old" sequence number.
91 *
92 * Caller must hold chain->lock.
93 *
94 * Returns true if chain is empty and caller can just insert the new fragment
95 * without searching for the right position.
96 */
97static bool batadv_frag_init_chain(struct batadv_frag_table_entry *chain,
98 uint16_t seqno)
99{
100 if (chain->seqno == seqno)
101 return false;
102
103 if (!hlist_empty(&chain->head))
104 batadv_frag_clear_chain(&chain->head);
105
106 chain->size = 0;
107 chain->seqno = seqno;
108
109 return true;
110}
111
112/**
113 * batadv_frag_insert_packet - insert a fragment into a fragment chain
114 * @orig_node: originator that the fragment was received from
115 * @skb: skb to insert
116 * @chain_out: list head to attach complete chains of fragments to
117 *
118 * Insert a new fragment into the reverse ordered chain in the right table
119 * entry. The hash table entry is cleared if "old" fragments exist in it.
120 *
121 * Returns true if skb is buffered, false on error. If the chain has all the
122 * fragments needed to merge the packet, the chain is moved to the passed head
123 * to avoid locking the chain in the table.
124 */
125static bool batadv_frag_insert_packet(struct batadv_orig_node *orig_node,
126 struct sk_buff *skb,
127 struct hlist_head *chain_out)
128{
129 struct batadv_frag_table_entry *chain;
130 struct batadv_frag_list_entry *frag_entry_new = NULL, *frag_entry_curr;
Sven Eckelmannd9124262014-05-26 17:21:39 +0200131 struct batadv_frag_list_entry *frag_entry_last = NULL;
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +0200132 struct batadv_frag_packet *frag_packet;
133 uint8_t bucket;
134 uint16_t seqno, hdr_size = sizeof(struct batadv_frag_packet);
135 bool ret = false;
136
137 /* Linearize packet to avoid linearizing 16 packets in a row when doing
138 * the later merge. Non-linear merge should be added to remove this
139 * linearization.
140 */
141 if (skb_linearize(skb) < 0)
142 goto err;
143
144 frag_packet = (struct batadv_frag_packet *)skb->data;
145 seqno = ntohs(frag_packet->seqno);
146 bucket = seqno % BATADV_FRAG_BUFFER_COUNT;
147
148 frag_entry_new = kmalloc(sizeof(*frag_entry_new), GFP_ATOMIC);
149 if (!frag_entry_new)
150 goto err;
151
152 frag_entry_new->skb = skb;
153 frag_entry_new->no = frag_packet->no;
154
155 /* Select entry in the "chain table" and delete any prior fragments
156 * with another sequence number. batadv_frag_init_chain() returns true,
157 * if the list is empty at return.
158 */
159 chain = &orig_node->fragments[bucket];
160 spin_lock_bh(&chain->lock);
161 if (batadv_frag_init_chain(chain, seqno)) {
162 hlist_add_head(&frag_entry_new->list, &chain->head);
163 chain->size = skb->len - hdr_size;
164 chain->timestamp = jiffies;
165 ret = true;
166 goto out;
167 }
168
169 /* Find the position for the new fragment. */
170 hlist_for_each_entry(frag_entry_curr, &chain->head, list) {
171 /* Drop packet if fragment already exists. */
172 if (frag_entry_curr->no == frag_entry_new->no)
173 goto err_unlock;
174
175 /* Order fragments from highest to lowest. */
176 if (frag_entry_curr->no < frag_entry_new->no) {
177 hlist_add_before(&frag_entry_new->list,
178 &frag_entry_curr->list);
179 chain->size += skb->len - hdr_size;
180 chain->timestamp = jiffies;
181 ret = true;
182 goto out;
183 }
Sven Eckelmannd9124262014-05-26 17:21:39 +0200184
185 /* store current entry because it could be the last in list */
186 frag_entry_last = frag_entry_curr;
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +0200187 }
188
Sven Eckelmannd9124262014-05-26 17:21:39 +0200189 /* Reached the end of the list, so insert after 'frag_entry_last'. */
190 if (likely(frag_entry_last)) {
Sven Eckelmanne050dbe2014-08-15 10:19:39 +0200191 hlist_add_behind(&frag_entry_new->list, &frag_entry_last->list);
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +0200192 chain->size += skb->len - hdr_size;
193 chain->timestamp = jiffies;
194 ret = true;
195 }
196
197out:
198 if (chain->size > batadv_frag_size_limit() ||
199 ntohs(frag_packet->total_size) > batadv_frag_size_limit()) {
200 /* Clear chain if total size of either the list or the packet
201 * exceeds the maximum size of one merged packet.
202 */
203 batadv_frag_clear_chain(&chain->head);
204 chain->size = 0;
205 } else if (ntohs(frag_packet->total_size) == chain->size) {
206 /* All fragments received. Hand over chain to caller. */
207 hlist_move_list(&chain->head, chain_out);
208 chain->size = 0;
209 }
210
211err_unlock:
212 spin_unlock_bh(&chain->lock);
213
214err:
215 if (!ret)
216 kfree(frag_entry_new);
217
218 return ret;
219}
220
221/**
222 * batadv_frag_merge_packets - merge a chain of fragments
223 * @chain: head of chain with fragments
224 * @skb: packet with total size of skb after merging
225 *
226 * Expand the first skb in the chain and copy the content of the remaining
227 * skb's into the expanded one. After doing so, clear the chain.
228 *
229 * Returns the merged skb or NULL on error.
230 */
231static struct sk_buff *
232batadv_frag_merge_packets(struct hlist_head *chain, struct sk_buff *skb)
233{
234 struct batadv_frag_packet *packet;
235 struct batadv_frag_list_entry *entry;
236 struct sk_buff *skb_out = NULL;
237 int size, hdr_size = sizeof(struct batadv_frag_packet);
238
239 /* Make sure incoming skb has non-bogus data. */
240 packet = (struct batadv_frag_packet *)skb->data;
241 size = ntohs(packet->total_size);
242 if (size > batadv_frag_size_limit())
243 goto free;
244
245 /* Remove first entry, as this is the destination for the rest of the
246 * fragments.
247 */
248 entry = hlist_entry(chain->first, struct batadv_frag_list_entry, list);
249 hlist_del(&entry->list);
250 skb_out = entry->skb;
251 kfree(entry);
252
253 /* Make room for the rest of the fragments. */
254 if (pskb_expand_head(skb_out, 0, size - skb->len, GFP_ATOMIC) < 0) {
255 kfree_skb(skb_out);
256 skb_out = NULL;
257 goto free;
258 }
259
260 /* Move the existing MAC header to just before the payload. (Override
261 * the fragment header.)
262 */
263 skb_pull_rcsum(skb_out, hdr_size);
264 memmove(skb_out->data - ETH_HLEN, skb_mac_header(skb_out), ETH_HLEN);
265 skb_set_mac_header(skb_out, -ETH_HLEN);
266 skb_reset_network_header(skb_out);
267 skb_reset_transport_header(skb_out);
268
269 /* Copy the payload of the each fragment into the last skb */
270 hlist_for_each_entry(entry, chain, list) {
271 size = entry->skb->len - hdr_size;
272 memcpy(skb_put(skb_out, size), entry->skb->data + hdr_size,
273 size);
274 }
275
276free:
277 /* Locking is not needed, because 'chain' is not part of any orig. */
278 batadv_frag_clear_chain(chain);
279 return skb_out;
280}
281
282/**
283 * batadv_frag_skb_buffer - buffer fragment for later merge
284 * @skb: skb to buffer
285 * @orig_node_src: originator that the skb is received from
286 *
287 * Add fragment to buffer and merge fragments if possible.
288 *
289 * There are three possible outcomes: 1) Packet is merged: Return true and
290 * set *skb to merged packet; 2) Packet is buffered: Return true and set *skb
291 * to NULL; 3) Error: Return false and leave skb as is.
292 */
293bool batadv_frag_skb_buffer(struct sk_buff **skb,
294 struct batadv_orig_node *orig_node_src)
295{
296 struct sk_buff *skb_out = NULL;
297 struct hlist_head head = HLIST_HEAD_INIT;
298 bool ret = false;
299
300 /* Add packet to buffer and table entry if merge is possible. */
301 if (!batadv_frag_insert_packet(orig_node_src, *skb, &head))
302 goto out_err;
303
304 /* Leave if more fragments are needed to merge. */
305 if (hlist_empty(&head))
306 goto out;
307
308 skb_out = batadv_frag_merge_packets(&head, *skb);
309 if (!skb_out)
310 goto out_err;
311
312out:
313 *skb = skb_out;
314 ret = true;
315out_err:
316 return ret;
317}
318
319/**
320 * batadv_frag_skb_fwd - forward fragments that would exceed MTU when merged
321 * @skb: skb to forward
322 * @recv_if: interface that the skb is received on
323 * @orig_node_src: originator that the skb is received from
324 *
325 * Look up the next-hop of the fragments payload and check if the merged packet
326 * will exceed the MTU towards the next-hop. If so, the fragment is forwarded
327 * without merging it.
328 *
329 * Returns true if the fragment is consumed/forwarded, false otherwise.
330 */
331bool batadv_frag_skb_fwd(struct sk_buff *skb,
332 struct batadv_hard_iface *recv_if,
333 struct batadv_orig_node *orig_node_src)
334{
335 struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
336 struct batadv_orig_node *orig_node_dst = NULL;
337 struct batadv_neigh_node *neigh_node = NULL;
338 struct batadv_frag_packet *packet;
339 uint16_t total_size;
340 bool ret = false;
341
342 packet = (struct batadv_frag_packet *)skb->data;
343 orig_node_dst = batadv_orig_hash_find(bat_priv, packet->dest);
344 if (!orig_node_dst)
345 goto out;
346
347 neigh_node = batadv_find_router(bat_priv, orig_node_dst, recv_if);
348 if (!neigh_node)
349 goto out;
350
351 /* Forward the fragment, if the merged packet would be too big to
352 * be assembled.
353 */
354 total_size = ntohs(packet->total_size);
355 if (total_size > neigh_node->if_incoming->net_dev->mtu) {
356 batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_FWD);
357 batadv_add_counter(bat_priv, BATADV_CNT_FRAG_FWD_BYTES,
358 skb->len + ETH_HLEN);
359
Simon Wunderlicha40d9b02013-12-02 20:38:31 +0100360 packet->ttl--;
Martin Hundebøll610bfc6bc2013-05-23 16:53:02 +0200361 batadv_send_skb_packet(skb, neigh_node->if_incoming,
362 neigh_node->addr);
363 ret = true;
364 }
365
366out:
367 if (orig_node_dst)
368 batadv_orig_node_free_ref(orig_node_dst);
369 if (neigh_node)
370 batadv_neigh_node_free_ref(neigh_node);
371 return ret;
372}
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200373
374/**
375 * batadv_frag_create - create a fragment from skb
376 * @skb: skb to create fragment from
377 * @frag_head: header to use in new fragment
378 * @mtu: size of new fragment
379 *
380 * Split the passed skb into two fragments: A new one with size matching the
381 * passed mtu and the old one with the rest. The new skb contains data from the
382 * tail of the old skb.
383 *
384 * Returns the new fragment, NULL on error.
385 */
386static struct sk_buff *batadv_frag_create(struct sk_buff *skb,
387 struct batadv_frag_packet *frag_head,
388 unsigned int mtu)
389{
390 struct sk_buff *skb_fragment;
391 unsigned header_size = sizeof(*frag_head);
392 unsigned fragment_size = mtu - header_size;
393
394 skb_fragment = netdev_alloc_skb(NULL, mtu + ETH_HLEN);
395 if (!skb_fragment)
396 goto err;
397
398 skb->priority = TC_PRIO_CONTROL;
399
400 /* Eat the last mtu-bytes of the skb */
401 skb_reserve(skb_fragment, header_size + ETH_HLEN);
402 skb_split(skb, skb_fragment, skb->len - fragment_size);
403
404 /* Add the header */
405 skb_push(skb_fragment, header_size);
406 memcpy(skb_fragment->data, frag_head, header_size);
407
408err:
409 return skb_fragment;
410}
411
412/**
413 * batadv_frag_send_packet - create up to 16 fragments from the passed skb
414 * @skb: skb to create fragments from
415 * @orig_node: final destination of the created fragments
416 * @neigh_node: next-hop of the created fragments
417 *
418 * Returns true on success, false otherwise.
419 */
420bool batadv_frag_send_packet(struct sk_buff *skb,
421 struct batadv_orig_node *orig_node,
422 struct batadv_neigh_node *neigh_node)
423{
424 struct batadv_priv *bat_priv;
Antonio Quartullibe181012014-04-23 14:05:16 +0200425 struct batadv_hard_iface *primary_if = NULL;
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200426 struct batadv_frag_packet frag_header;
427 struct sk_buff *skb_fragment;
428 unsigned mtu = neigh_node->if_incoming->net_dev->mtu;
429 unsigned header_size = sizeof(frag_header);
430 unsigned max_fragment_size, max_packet_size;
Antonio Quartullibe181012014-04-23 14:05:16 +0200431 bool ret = false;
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200432
433 /* To avoid merge and refragmentation at next-hops we never send
434 * fragments larger than BATADV_FRAG_MAX_FRAG_SIZE
435 */
436 mtu = min_t(unsigned, mtu, BATADV_FRAG_MAX_FRAG_SIZE);
437 max_fragment_size = (mtu - header_size - ETH_HLEN);
438 max_packet_size = max_fragment_size * BATADV_FRAG_MAX_FRAGMENTS;
439
440 /* Don't even try to fragment, if we need more than 16 fragments */
441 if (skb->len > max_packet_size)
442 goto out_err;
443
444 bat_priv = orig_node->bat_priv;
445 primary_if = batadv_primary_if_get_selected(bat_priv);
446 if (!primary_if)
447 goto out_err;
448
449 /* Create one header to be copied to all fragments */
Simon Wunderlicha40d9b02013-12-02 20:38:31 +0100450 frag_header.packet_type = BATADV_UNICAST_FRAG;
451 frag_header.version = BATADV_COMPAT_VERSION;
452 frag_header.ttl = BATADV_TTL;
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200453 frag_header.seqno = htons(atomic_inc_return(&bat_priv->frag_seqno));
454 frag_header.reserved = 0;
455 frag_header.no = 0;
456 frag_header.total_size = htons(skb->len);
Antonio Quartulli8fdd0152014-01-22 00:42:11 +0100457 ether_addr_copy(frag_header.orig, primary_if->net_dev->dev_addr);
458 ether_addr_copy(frag_header.dest, orig_node->orig);
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200459
460 /* Eat and send fragments from the tail of skb */
461 while (skb->len > max_fragment_size) {
462 skb_fragment = batadv_frag_create(skb, &frag_header, mtu);
463 if (!skb_fragment)
464 goto out_err;
465
466 batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX);
467 batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES,
468 skb_fragment->len + ETH_HLEN);
469 batadv_send_skb_packet(skb_fragment, neigh_node->if_incoming,
470 neigh_node->addr);
471 frag_header.no++;
472
473 /* The initial check in this function should cover this case */
474 if (frag_header.no == BATADV_FRAG_MAX_FRAGMENTS - 1)
475 goto out_err;
476 }
477
478 /* Make room for the fragment header. */
479 if (batadv_skb_head_push(skb, header_size) < 0 ||
480 pskb_expand_head(skb, header_size + ETH_HLEN, 0, GFP_ATOMIC) < 0)
481 goto out_err;
482
483 memcpy(skb->data, &frag_header, header_size);
484
485 /* Send the last fragment */
486 batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX);
487 batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES,
488 skb->len + ETH_HLEN);
489 batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
490
Antonio Quartullibe181012014-04-23 14:05:16 +0200491 ret = true;
492
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200493out_err:
Antonio Quartullibe181012014-04-23 14:05:16 +0200494 if (primary_if)
495 batadv_hardif_free_ref(primary_if);
496
497 return ret;
Martin Hundebøllee75ed82013-05-23 16:53:03 +0200498}