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9f6446c7 | 1 | /* Copyright (C) 2013-2015 B.A.T.M.A.N. contributors: |
610bfc6b MH |
2 | * |
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 | |
ebf38fb7 | 15 | * along with this program; if not, see <http://www.gnu.org/licenses/>. |
610bfc6b MH |
16 | */ |
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 | ||
610bfc6b MH |
26 | /** |
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 | */ | |
32 | static 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 | */ | |
49 | void 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 | */ | |
73 | static 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 | */ | |
96 | static 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 | */ | |
124 | static 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; | |
d9124268 | 130 | struct batadv_frag_list_entry *frag_entry_last = NULL; |
610bfc6b MH |
131 | 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; | |
53e77145 | 164 | chain->total_size = ntohs(frag_packet->total_size); |
610bfc6b MH |
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 | } | |
d9124268 SE |
184 | |
185 | /* store current entry because it could be the last in list */ | |
186 | frag_entry_last = frag_entry_curr; | |
610bfc6b MH |
187 | } |
188 | ||
d9124268 SE |
189 | /* Reached the end of the list, so insert after 'frag_entry_last'. */ |
190 | if (likely(frag_entry_last)) { | |
e050dbeb | 191 | hlist_add_behind(&frag_entry_new->list, &frag_entry_last->list); |
610bfc6b MH |
192 | chain->size += skb->len - hdr_size; |
193 | chain->timestamp = jiffies; | |
194 | ret = true; | |
195 | } | |
196 | ||
197 | out: | |
198 | if (chain->size > batadv_frag_size_limit() || | |
53e77145 SE |
199 | chain->total_size != ntohs(frag_packet->total_size) || |
200 | chain->total_size > batadv_frag_size_limit()) { | |
610bfc6b | 201 | /* Clear chain if total size of either the list or the packet |
53e77145 SE |
202 | * exceeds the maximum size of one merged packet. Don't allow |
203 | * packets to have different total_size. | |
610bfc6b MH |
204 | */ |
205 | batadv_frag_clear_chain(&chain->head); | |
206 | chain->size = 0; | |
207 | } else if (ntohs(frag_packet->total_size) == chain->size) { | |
208 | /* All fragments received. Hand over chain to caller. */ | |
209 | hlist_move_list(&chain->head, chain_out); | |
210 | chain->size = 0; | |
211 | } | |
212 | ||
213 | err_unlock: | |
214 | spin_unlock_bh(&chain->lock); | |
215 | ||
216 | err: | |
217 | if (!ret) | |
218 | kfree(frag_entry_new); | |
219 | ||
220 | return ret; | |
221 | } | |
222 | ||
223 | /** | |
224 | * batadv_frag_merge_packets - merge a chain of fragments | |
225 | * @chain: head of chain with fragments | |
226 | * @skb: packet with total size of skb after merging | |
227 | * | |
228 | * Expand the first skb in the chain and copy the content of the remaining | |
229 | * skb's into the expanded one. After doing so, clear the chain. | |
230 | * | |
231 | * Returns the merged skb or NULL on error. | |
232 | */ | |
233 | static struct sk_buff * | |
234 | batadv_frag_merge_packets(struct hlist_head *chain, struct sk_buff *skb) | |
235 | { | |
236 | struct batadv_frag_packet *packet; | |
237 | struct batadv_frag_list_entry *entry; | |
238 | struct sk_buff *skb_out = NULL; | |
239 | int size, hdr_size = sizeof(struct batadv_frag_packet); | |
240 | ||
241 | /* Make sure incoming skb has non-bogus data. */ | |
242 | packet = (struct batadv_frag_packet *)skb->data; | |
243 | size = ntohs(packet->total_size); | |
244 | if (size > batadv_frag_size_limit()) | |
245 | goto free; | |
246 | ||
247 | /* Remove first entry, as this is the destination for the rest of the | |
248 | * fragments. | |
249 | */ | |
250 | entry = hlist_entry(chain->first, struct batadv_frag_list_entry, list); | |
251 | hlist_del(&entry->list); | |
252 | skb_out = entry->skb; | |
253 | kfree(entry); | |
254 | ||
255 | /* Make room for the rest of the fragments. */ | |
5b6698b0 | 256 | if (pskb_expand_head(skb_out, 0, size - skb_out->len, GFP_ATOMIC) < 0) { |
610bfc6b MH |
257 | kfree_skb(skb_out); |
258 | skb_out = NULL; | |
259 | goto free; | |
260 | } | |
261 | ||
262 | /* Move the existing MAC header to just before the payload. (Override | |
263 | * the fragment header.) | |
264 | */ | |
265 | skb_pull_rcsum(skb_out, hdr_size); | |
266 | memmove(skb_out->data - ETH_HLEN, skb_mac_header(skb_out), ETH_HLEN); | |
267 | skb_set_mac_header(skb_out, -ETH_HLEN); | |
268 | skb_reset_network_header(skb_out); | |
269 | skb_reset_transport_header(skb_out); | |
270 | ||
271 | /* Copy the payload of the each fragment into the last skb */ | |
272 | hlist_for_each_entry(entry, chain, list) { | |
273 | size = entry->skb->len - hdr_size; | |
274 | memcpy(skb_put(skb_out, size), entry->skb->data + hdr_size, | |
275 | size); | |
276 | } | |
277 | ||
278 | free: | |
279 | /* Locking is not needed, because 'chain' is not part of any orig. */ | |
280 | batadv_frag_clear_chain(chain); | |
281 | return skb_out; | |
282 | } | |
283 | ||
284 | /** | |
285 | * batadv_frag_skb_buffer - buffer fragment for later merge | |
286 | * @skb: skb to buffer | |
287 | * @orig_node_src: originator that the skb is received from | |
288 | * | |
289 | * Add fragment to buffer and merge fragments if possible. | |
290 | * | |
291 | * There are three possible outcomes: 1) Packet is merged: Return true and | |
292 | * set *skb to merged packet; 2) Packet is buffered: Return true and set *skb | |
293 | * to NULL; 3) Error: Return false and leave skb as is. | |
294 | */ | |
295 | bool batadv_frag_skb_buffer(struct sk_buff **skb, | |
296 | struct batadv_orig_node *orig_node_src) | |
297 | { | |
298 | struct sk_buff *skb_out = NULL; | |
299 | struct hlist_head head = HLIST_HEAD_INIT; | |
300 | bool ret = false; | |
301 | ||
302 | /* Add packet to buffer and table entry if merge is possible. */ | |
303 | if (!batadv_frag_insert_packet(orig_node_src, *skb, &head)) | |
304 | goto out_err; | |
305 | ||
306 | /* Leave if more fragments are needed to merge. */ | |
307 | if (hlist_empty(&head)) | |
308 | goto out; | |
309 | ||
310 | skb_out = batadv_frag_merge_packets(&head, *skb); | |
311 | if (!skb_out) | |
312 | goto out_err; | |
313 | ||
314 | out: | |
315 | *skb = skb_out; | |
316 | ret = true; | |
317 | out_err: | |
318 | return ret; | |
319 | } | |
320 | ||
321 | /** | |
322 | * batadv_frag_skb_fwd - forward fragments that would exceed MTU when merged | |
323 | * @skb: skb to forward | |
324 | * @recv_if: interface that the skb is received on | |
325 | * @orig_node_src: originator that the skb is received from | |
326 | * | |
327 | * Look up the next-hop of the fragments payload and check if the merged packet | |
328 | * will exceed the MTU towards the next-hop. If so, the fragment is forwarded | |
329 | * without merging it. | |
330 | * | |
331 | * Returns true if the fragment is consumed/forwarded, false otherwise. | |
332 | */ | |
333 | bool batadv_frag_skb_fwd(struct sk_buff *skb, | |
334 | struct batadv_hard_iface *recv_if, | |
335 | struct batadv_orig_node *orig_node_src) | |
336 | { | |
337 | struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface); | |
338 | struct batadv_orig_node *orig_node_dst = NULL; | |
339 | struct batadv_neigh_node *neigh_node = NULL; | |
340 | struct batadv_frag_packet *packet; | |
341 | uint16_t total_size; | |
342 | bool ret = false; | |
343 | ||
344 | packet = (struct batadv_frag_packet *)skb->data; | |
345 | orig_node_dst = batadv_orig_hash_find(bat_priv, packet->dest); | |
346 | if (!orig_node_dst) | |
347 | goto out; | |
348 | ||
349 | neigh_node = batadv_find_router(bat_priv, orig_node_dst, recv_if); | |
350 | if (!neigh_node) | |
351 | goto out; | |
352 | ||
353 | /* Forward the fragment, if the merged packet would be too big to | |
354 | * be assembled. | |
355 | */ | |
356 | total_size = ntohs(packet->total_size); | |
357 | if (total_size > neigh_node->if_incoming->net_dev->mtu) { | |
358 | batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_FWD); | |
359 | batadv_add_counter(bat_priv, BATADV_CNT_FRAG_FWD_BYTES, | |
360 | skb->len + ETH_HLEN); | |
361 | ||
a40d9b07 | 362 | packet->ttl--; |
610bfc6b MH |
363 | batadv_send_skb_packet(skb, neigh_node->if_incoming, |
364 | neigh_node->addr); | |
365 | ret = true; | |
366 | } | |
367 | ||
368 | out: | |
369 | if (orig_node_dst) | |
370 | batadv_orig_node_free_ref(orig_node_dst); | |
371 | if (neigh_node) | |
372 | batadv_neigh_node_free_ref(neigh_node); | |
373 | return ret; | |
374 | } | |
ee75ed88 MH |
375 | |
376 | /** | |
377 | * batadv_frag_create - create a fragment from skb | |
378 | * @skb: skb to create fragment from | |
379 | * @frag_head: header to use in new fragment | |
380 | * @mtu: size of new fragment | |
381 | * | |
382 | * Split the passed skb into two fragments: A new one with size matching the | |
383 | * passed mtu and the old one with the rest. The new skb contains data from the | |
384 | * tail of the old skb. | |
385 | * | |
386 | * Returns the new fragment, NULL on error. | |
387 | */ | |
388 | static struct sk_buff *batadv_frag_create(struct sk_buff *skb, | |
389 | struct batadv_frag_packet *frag_head, | |
390 | unsigned int mtu) | |
391 | { | |
392 | struct sk_buff *skb_fragment; | |
393 | unsigned header_size = sizeof(*frag_head); | |
394 | unsigned fragment_size = mtu - header_size; | |
395 | ||
396 | skb_fragment = netdev_alloc_skb(NULL, mtu + ETH_HLEN); | |
397 | if (!skb_fragment) | |
398 | goto err; | |
399 | ||
400 | skb->priority = TC_PRIO_CONTROL; | |
401 | ||
402 | /* Eat the last mtu-bytes of the skb */ | |
403 | skb_reserve(skb_fragment, header_size + ETH_HLEN); | |
404 | skb_split(skb, skb_fragment, skb->len - fragment_size); | |
405 | ||
406 | /* Add the header */ | |
407 | skb_push(skb_fragment, header_size); | |
408 | memcpy(skb_fragment->data, frag_head, header_size); | |
409 | ||
410 | err: | |
411 | return skb_fragment; | |
412 | } | |
413 | ||
414 | /** | |
415 | * batadv_frag_send_packet - create up to 16 fragments from the passed skb | |
416 | * @skb: skb to create fragments from | |
417 | * @orig_node: final destination of the created fragments | |
418 | * @neigh_node: next-hop of the created fragments | |
419 | * | |
420 | * Returns true on success, false otherwise. | |
421 | */ | |
422 | bool batadv_frag_send_packet(struct sk_buff *skb, | |
423 | struct batadv_orig_node *orig_node, | |
424 | struct batadv_neigh_node *neigh_node) | |
425 | { | |
426 | struct batadv_priv *bat_priv; | |
be181015 | 427 | struct batadv_hard_iface *primary_if = NULL; |
ee75ed88 MH |
428 | struct batadv_frag_packet frag_header; |
429 | struct sk_buff *skb_fragment; | |
430 | unsigned mtu = neigh_node->if_incoming->net_dev->mtu; | |
431 | unsigned header_size = sizeof(frag_header); | |
432 | unsigned max_fragment_size, max_packet_size; | |
be181015 | 433 | bool ret = false; |
ee75ed88 MH |
434 | |
435 | /* To avoid merge and refragmentation at next-hops we never send | |
436 | * fragments larger than BATADV_FRAG_MAX_FRAG_SIZE | |
437 | */ | |
438 | mtu = min_t(unsigned, mtu, BATADV_FRAG_MAX_FRAG_SIZE); | |
0402e444 | 439 | max_fragment_size = mtu - header_size; |
ee75ed88 MH |
440 | max_packet_size = max_fragment_size * BATADV_FRAG_MAX_FRAGMENTS; |
441 | ||
442 | /* Don't even try to fragment, if we need more than 16 fragments */ | |
443 | if (skb->len > max_packet_size) | |
444 | goto out_err; | |
445 | ||
446 | bat_priv = orig_node->bat_priv; | |
447 | primary_if = batadv_primary_if_get_selected(bat_priv); | |
448 | if (!primary_if) | |
449 | goto out_err; | |
450 | ||
451 | /* Create one header to be copied to all fragments */ | |
a40d9b07 SW |
452 | frag_header.packet_type = BATADV_UNICAST_FRAG; |
453 | frag_header.version = BATADV_COMPAT_VERSION; | |
454 | frag_header.ttl = BATADV_TTL; | |
ee75ed88 MH |
455 | frag_header.seqno = htons(atomic_inc_return(&bat_priv->frag_seqno)); |
456 | frag_header.reserved = 0; | |
457 | frag_header.no = 0; | |
458 | frag_header.total_size = htons(skb->len); | |
8fdd0153 AQ |
459 | ether_addr_copy(frag_header.orig, primary_if->net_dev->dev_addr); |
460 | ether_addr_copy(frag_header.dest, orig_node->orig); | |
ee75ed88 MH |
461 | |
462 | /* Eat and send fragments from the tail of skb */ | |
463 | while (skb->len > max_fragment_size) { | |
464 | skb_fragment = batadv_frag_create(skb, &frag_header, mtu); | |
465 | if (!skb_fragment) | |
466 | goto out_err; | |
467 | ||
468 | batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX); | |
469 | batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES, | |
470 | skb_fragment->len + ETH_HLEN); | |
471 | batadv_send_skb_packet(skb_fragment, neigh_node->if_incoming, | |
472 | neigh_node->addr); | |
473 | frag_header.no++; | |
474 | ||
475 | /* The initial check in this function should cover this case */ | |
476 | if (frag_header.no == BATADV_FRAG_MAX_FRAGMENTS - 1) | |
477 | goto out_err; | |
478 | } | |
479 | ||
480 | /* Make room for the fragment header. */ | |
481 | if (batadv_skb_head_push(skb, header_size) < 0 || | |
482 | pskb_expand_head(skb, header_size + ETH_HLEN, 0, GFP_ATOMIC) < 0) | |
483 | goto out_err; | |
484 | ||
485 | memcpy(skb->data, &frag_header, header_size); | |
486 | ||
487 | /* Send the last fragment */ | |
488 | batadv_inc_counter(bat_priv, BATADV_CNT_FRAG_TX); | |
489 | batadv_add_counter(bat_priv, BATADV_CNT_FRAG_TX_BYTES, | |
490 | skb->len + ETH_HLEN); | |
491 | batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr); | |
492 | ||
be181015 AQ |
493 | ret = true; |
494 | ||
ee75ed88 | 495 | out_err: |
be181015 AQ |
496 | if (primary_if) |
497 | batadv_hardif_free_ref(primary_if); | |
498 | ||
499 | return ret; | |
ee75ed88 | 500 | } |