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TOMOYO Linux Cross Reference
Linux/net/sctp/ulpqueue.c

Version: ~ [ linux-5.2-rc5 ] ~ [ linux-5.1.11 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.52 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.127 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.182 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.182 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.68 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 /* SCTP kernel implementation
  2  * (C) Copyright IBM Corp. 2001, 2004
  3  * Copyright (c) 1999-2000 Cisco, Inc.
  4  * Copyright (c) 1999-2001 Motorola, Inc.
  5  * Copyright (c) 2001 Intel Corp.
  6  * Copyright (c) 2001 Nokia, Inc.
  7  * Copyright (c) 2001 La Monte H.P. Yarroll
  8  *
  9  * This abstraction carries sctp events to the ULP (sockets).
 10  *
 11  * This SCTP implementation is free software;
 12  * you can redistribute it and/or modify it under the terms of
 13  * the GNU General Public License as published by
 14  * the Free Software Foundation; either version 2, or (at your option)
 15  * any later version.
 16  *
 17  * This SCTP implementation is distributed in the hope that it
 18  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 19  *                 ************************
 20  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 21  * See the GNU General Public License for more details.
 22  *
 23  * You should have received a copy of the GNU General Public License
 24  * along with GNU CC; see the file COPYING.  If not, write to
 25  * the Free Software Foundation, 59 Temple Place - Suite 330,
 26  * Boston, MA 02111-1307, USA.
 27  *
 28  * Please send any bug reports or fixes you make to the
 29  * email address(es):
 30  *    lksctp developers <lksctp-developers@lists.sourceforge.net>
 31  *
 32  * Or submit a bug report through the following website:
 33  *    http://www.sf.net/projects/lksctp
 34  *
 35  * Written or modified by:
 36  *    Jon Grimm             <jgrimm@us.ibm.com>
 37  *    La Monte H.P. Yarroll <piggy@acm.org>
 38  *    Sridhar Samudrala     <sri@us.ibm.com>
 39  *
 40  * Any bugs reported given to us we will try to fix... any fixes shared will
 41  * be incorporated into the next SCTP release.
 42  */
 43 
 44 #include <linux/slab.h>
 45 #include <linux/types.h>
 46 #include <linux/skbuff.h>
 47 #include <net/sock.h>
 48 #include <net/sctp/structs.h>
 49 #include <net/sctp/sctp.h>
 50 #include <net/sctp/sm.h>
 51 
 52 /* Forward declarations for internal helpers.  */
 53 static struct sctp_ulpevent * sctp_ulpq_reasm(struct sctp_ulpq *ulpq,
 54                                               struct sctp_ulpevent *);
 55 static struct sctp_ulpevent * sctp_ulpq_order(struct sctp_ulpq *,
 56                                               struct sctp_ulpevent *);
 57 static void sctp_ulpq_reasm_drain(struct sctp_ulpq *ulpq);
 58 
 59 /* 1st Level Abstractions */
 60 
 61 /* Initialize a ULP queue from a block of memory.  */
 62 struct sctp_ulpq *sctp_ulpq_init(struct sctp_ulpq *ulpq,
 63                                  struct sctp_association *asoc)
 64 {
 65         memset(ulpq, 0, sizeof(struct sctp_ulpq));
 66 
 67         ulpq->asoc = asoc;
 68         skb_queue_head_init(&ulpq->reasm);
 69         skb_queue_head_init(&ulpq->lobby);
 70         ulpq->pd_mode  = 0;
 71         ulpq->malloced = 0;
 72 
 73         return ulpq;
 74 }
 75 
 76 
 77 /* Flush the reassembly and ordering queues.  */
 78 void sctp_ulpq_flush(struct sctp_ulpq *ulpq)
 79 {
 80         struct sk_buff *skb;
 81         struct sctp_ulpevent *event;
 82 
 83         while ((skb = __skb_dequeue(&ulpq->lobby)) != NULL) {
 84                 event = sctp_skb2event(skb);
 85                 sctp_ulpevent_free(event);
 86         }
 87 
 88         while ((skb = __skb_dequeue(&ulpq->reasm)) != NULL) {
 89                 event = sctp_skb2event(skb);
 90                 sctp_ulpevent_free(event);
 91         }
 92 
 93 }
 94 
 95 /* Dispose of a ulpqueue.  */
 96 void sctp_ulpq_free(struct sctp_ulpq *ulpq)
 97 {
 98         sctp_ulpq_flush(ulpq);
 99         if (ulpq->malloced)
100                 kfree(ulpq);
101 }
102 
103 /* Process an incoming DATA chunk.  */
104 int sctp_ulpq_tail_data(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
105                         gfp_t gfp)
106 {
107         struct sk_buff_head temp;
108         sctp_data_chunk_t *hdr;
109         struct sctp_ulpevent *event;
110 
111         hdr = (sctp_data_chunk_t *) chunk->chunk_hdr;
112 
113         /* Create an event from the incoming chunk. */
114         event = sctp_ulpevent_make_rcvmsg(chunk->asoc, chunk, gfp);
115         if (!event)
116                 return -ENOMEM;
117 
118         /* Do reassembly if needed.  */
119         event = sctp_ulpq_reasm(ulpq, event);
120 
121         /* Do ordering if needed.  */
122         if ((event) && (event->msg_flags & MSG_EOR)){
123                 /* Create a temporary list to collect chunks on.  */
124                 skb_queue_head_init(&temp);
125                 __skb_queue_tail(&temp, sctp_event2skb(event));
126 
127                 event = sctp_ulpq_order(ulpq, event);
128         }
129 
130         /* Send event to the ULP.  'event' is the sctp_ulpevent for
131          * very first SKB on the 'temp' list.
132          */
133         if (event)
134                 sctp_ulpq_tail_event(ulpq, event);
135 
136         return 0;
137 }
138 
139 /* Add a new event for propagation to the ULP.  */
140 /* Clear the partial delivery mode for this socket.   Note: This
141  * assumes that no association is currently in partial delivery mode.
142  */
143 int sctp_clear_pd(struct sock *sk, struct sctp_association *asoc)
144 {
145         struct sctp_sock *sp = sctp_sk(sk);
146 
147         if (atomic_dec_and_test(&sp->pd_mode)) {
148                 /* This means there are no other associations in PD, so
149                  * we can go ahead and clear out the lobby in one shot
150                  */
151                 if (!skb_queue_empty(&sp->pd_lobby)) {
152                         struct list_head *list;
153                         sctp_skb_list_tail(&sp->pd_lobby, &sk->sk_receive_queue);
154                         list = (struct list_head *)&sctp_sk(sk)->pd_lobby;
155                         INIT_LIST_HEAD(list);
156                         return 1;
157                 }
158         } else {
159                 /* There are other associations in PD, so we only need to
160                  * pull stuff out of the lobby that belongs to the
161                  * associations that is exiting PD (all of its notifications
162                  * are posted here).
163                  */
164                 if (!skb_queue_empty(&sp->pd_lobby) && asoc) {
165                         struct sk_buff *skb, *tmp;
166                         struct sctp_ulpevent *event;
167 
168                         sctp_skb_for_each(skb, &sp->pd_lobby, tmp) {
169                                 event = sctp_skb2event(skb);
170                                 if (event->asoc == asoc) {
171                                         __skb_unlink(skb, &sp->pd_lobby);
172                                         __skb_queue_tail(&sk->sk_receive_queue,
173                                                          skb);
174                                 }
175                         }
176                 }
177         }
178 
179         return 0;
180 }
181 
182 /* Set the pd_mode on the socket and ulpq */
183 static void sctp_ulpq_set_pd(struct sctp_ulpq *ulpq)
184 {
185         struct sctp_sock *sp = sctp_sk(ulpq->asoc->base.sk);
186 
187         atomic_inc(&sp->pd_mode);
188         ulpq->pd_mode = 1;
189 }
190 
191 /* Clear the pd_mode and restart any pending messages waiting for delivery. */
192 static int sctp_ulpq_clear_pd(struct sctp_ulpq *ulpq)
193 {
194         ulpq->pd_mode = 0;
195         sctp_ulpq_reasm_drain(ulpq);
196         return sctp_clear_pd(ulpq->asoc->base.sk, ulpq->asoc);
197 }
198 
199 /* If the SKB of 'event' is on a list, it is the first such member
200  * of that list.
201  */
202 int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
203 {
204         struct sock *sk = ulpq->asoc->base.sk;
205         struct sk_buff_head *queue, *skb_list;
206         struct sk_buff *skb = sctp_event2skb(event);
207         int clear_pd = 0;
208 
209         skb_list = (struct sk_buff_head *) skb->prev;
210 
211         /* If the socket is just going to throw this away, do not
212          * even try to deliver it.
213          */
214         if (sock_flag(sk, SOCK_DEAD) || (sk->sk_shutdown & RCV_SHUTDOWN))
215                 goto out_free;
216 
217         /* Check if the user wishes to receive this event.  */
218         if (!sctp_ulpevent_is_enabled(event, &sctp_sk(sk)->subscribe))
219                 goto out_free;
220 
221         /* If we are in partial delivery mode, post to the lobby until
222          * partial delivery is cleared, unless, of course _this_ is
223          * the association the cause of the partial delivery.
224          */
225 
226         if (atomic_read(&sctp_sk(sk)->pd_mode) == 0) {
227                 queue = &sk->sk_receive_queue;
228         } else {
229                 if (ulpq->pd_mode) {
230                         /* If the association is in partial delivery, we
231                          * need to finish delivering the partially processed
232                          * packet before passing any other data.  This is
233                          * because we don't truly support stream interleaving.
234                          */
235                         if ((event->msg_flags & MSG_NOTIFICATION) ||
236                             (SCTP_DATA_NOT_FRAG ==
237                                     (event->msg_flags & SCTP_DATA_FRAG_MASK)))
238                                 queue = &sctp_sk(sk)->pd_lobby;
239                         else {
240                                 clear_pd = event->msg_flags & MSG_EOR;
241                                 queue = &sk->sk_receive_queue;
242                         }
243                 } else {
244                         /*
245                          * If fragment interleave is enabled, we
246                          * can queue this to the recieve queue instead
247                          * of the lobby.
248                          */
249                         if (sctp_sk(sk)->frag_interleave)
250                                 queue = &sk->sk_receive_queue;
251                         else
252                                 queue = &sctp_sk(sk)->pd_lobby;
253                 }
254         }
255 
256         /* If we are harvesting multiple skbs they will be
257          * collected on a list.
258          */
259         if (skb_list)
260                 sctp_skb_list_tail(skb_list, queue);
261         else
262                 __skb_queue_tail(queue, skb);
263 
264         /* Did we just complete partial delivery and need to get
265          * rolling again?  Move pending data to the receive
266          * queue.
267          */
268         if (clear_pd)
269                 sctp_ulpq_clear_pd(ulpq);
270 
271         if (queue == &sk->sk_receive_queue)
272                 sk->sk_data_ready(sk, 0);
273         return 1;
274 
275 out_free:
276         if (skb_list)
277                 sctp_queue_purge_ulpevents(skb_list);
278         else
279                 sctp_ulpevent_free(event);
280 
281         return 0;
282 }
283 
284 /* 2nd Level Abstractions */
285 
286 /* Helper function to store chunks that need to be reassembled.  */
287 static void sctp_ulpq_store_reasm(struct sctp_ulpq *ulpq,
288                                          struct sctp_ulpevent *event)
289 {
290         struct sk_buff *pos;
291         struct sctp_ulpevent *cevent;
292         __u32 tsn, ctsn;
293 
294         tsn = event->tsn;
295 
296         /* See if it belongs at the end. */
297         pos = skb_peek_tail(&ulpq->reasm);
298         if (!pos) {
299                 __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
300                 return;
301         }
302 
303         /* Short circuit just dropping it at the end. */
304         cevent = sctp_skb2event(pos);
305         ctsn = cevent->tsn;
306         if (TSN_lt(ctsn, tsn)) {
307                 __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
308                 return;
309         }
310 
311         /* Find the right place in this list. We store them by TSN.  */
312         skb_queue_walk(&ulpq->reasm, pos) {
313                 cevent = sctp_skb2event(pos);
314                 ctsn = cevent->tsn;
315 
316                 if (TSN_lt(tsn, ctsn))
317                         break;
318         }
319 
320         /* Insert before pos. */
321         __skb_queue_before(&ulpq->reasm, pos, sctp_event2skb(event));
322 
323 }
324 
325 /* Helper function to return an event corresponding to the reassembled
326  * datagram.
327  * This routine creates a re-assembled skb given the first and last skb's
328  * as stored in the reassembly queue. The skb's may be non-linear if the sctp
329  * payload was fragmented on the way and ip had to reassemble them.
330  * We add the rest of skb's to the first skb's fraglist.
331  */
332 static struct sctp_ulpevent *sctp_make_reassembled_event(struct sk_buff_head *queue, struct sk_buff *f_frag, struct sk_buff *l_frag)
333 {
334         struct sk_buff *pos;
335         struct sk_buff *new = NULL;
336         struct sctp_ulpevent *event;
337         struct sk_buff *pnext, *last;
338         struct sk_buff *list = skb_shinfo(f_frag)->frag_list;
339 
340         /* Store the pointer to the 2nd skb */
341         if (f_frag == l_frag)
342                 pos = NULL;
343         else
344                 pos = f_frag->next;
345 
346         /* Get the last skb in the f_frag's frag_list if present. */
347         for (last = list; list; last = list, list = list->next);
348 
349         /* Add the list of remaining fragments to the first fragments
350          * frag_list.
351          */
352         if (last)
353                 last->next = pos;
354         else {
355                 if (skb_cloned(f_frag)) {
356                         /* This is a cloned skb, we can't just modify
357                          * the frag_list.  We need a new skb to do that.
358                          * Instead of calling skb_unshare(), we'll do it
359                          * ourselves since we need to delay the free.
360                          */
361                         new = skb_copy(f_frag, GFP_ATOMIC);
362                         if (!new)
363                                 return NULL;    /* try again later */
364 
365                         sctp_skb_set_owner_r(new, f_frag->sk);
366 
367                         skb_shinfo(new)->frag_list = pos;
368                 } else
369                         skb_shinfo(f_frag)->frag_list = pos;
370         }
371 
372         /* Remove the first fragment from the reassembly queue.  */
373         __skb_unlink(f_frag, queue);
374 
375         /* if we did unshare, then free the old skb and re-assign */
376         if (new) {
377                 kfree_skb(f_frag);
378                 f_frag = new;
379         }
380 
381         while (pos) {
382 
383                 pnext = pos->next;
384 
385                 /* Update the len and data_len fields of the first fragment. */
386                 f_frag->len += pos->len;
387                 f_frag->data_len += pos->len;
388 
389                 /* Remove the fragment from the reassembly queue.  */
390                 __skb_unlink(pos, queue);
391 
392                 /* Break if we have reached the last fragment.  */
393                 if (pos == l_frag)
394                         break;
395                 pos->next = pnext;
396                 pos = pnext;
397         }
398 
399         event = sctp_skb2event(f_frag);
400         SCTP_INC_STATS(SCTP_MIB_REASMUSRMSGS);
401 
402         return event;
403 }
404 
405 
406 /* Helper function to check if an incoming chunk has filled up the last
407  * missing fragment in a SCTP datagram and return the corresponding event.
408  */
409 static struct sctp_ulpevent *sctp_ulpq_retrieve_reassembled(struct sctp_ulpq *ulpq)
410 {
411         struct sk_buff *pos;
412         struct sctp_ulpevent *cevent;
413         struct sk_buff *first_frag = NULL;
414         __u32 ctsn, next_tsn;
415         struct sctp_ulpevent *retval = NULL;
416         struct sk_buff *pd_first = NULL;
417         struct sk_buff *pd_last = NULL;
418         size_t pd_len = 0;
419         struct sctp_association *asoc;
420         u32 pd_point;
421 
422         /* Initialized to 0 just to avoid compiler warning message.  Will
423          * never be used with this value. It is referenced only after it
424          * is set when we find the first fragment of a message.
425          */
426         next_tsn = 0;
427 
428         /* The chunks are held in the reasm queue sorted by TSN.
429          * Walk through the queue sequentially and look for a sequence of
430          * fragmented chunks that complete a datagram.
431          * 'first_frag' and next_tsn are reset when we find a chunk which
432          * is the first fragment of a datagram. Once these 2 fields are set
433          * we expect to find the remaining middle fragments and the last
434          * fragment in order. If not, first_frag is reset to NULL and we
435          * start the next pass when we find another first fragment.
436          *
437          * There is a potential to do partial delivery if user sets
438          * SCTP_PARTIAL_DELIVERY_POINT option. Lets count some things here
439          * to see if can do PD.
440          */
441         skb_queue_walk(&ulpq->reasm, pos) {
442                 cevent = sctp_skb2event(pos);
443                 ctsn = cevent->tsn;
444 
445                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
446                 case SCTP_DATA_FIRST_FRAG:
447                         /* If this "FIRST_FRAG" is the first
448                          * element in the queue, then count it towards
449                          * possible PD.
450                          */
451                         if (pos == ulpq->reasm.next) {
452                             pd_first = pos;
453                             pd_last = pos;
454                             pd_len = pos->len;
455                         } else {
456                             pd_first = NULL;
457                             pd_last = NULL;
458                             pd_len = 0;
459                         }
460 
461                         first_frag = pos;
462                         next_tsn = ctsn + 1;
463                         break;
464 
465                 case SCTP_DATA_MIDDLE_FRAG:
466                         if ((first_frag) && (ctsn == next_tsn)) {
467                                 next_tsn++;
468                                 if (pd_first) {
469                                     pd_last = pos;
470                                     pd_len += pos->len;
471                                 }
472                         } else
473                                 first_frag = NULL;
474                         break;
475 
476                 case SCTP_DATA_LAST_FRAG:
477                         if (first_frag && (ctsn == next_tsn))
478                                 goto found;
479                         else
480                                 first_frag = NULL;
481                         break;
482                 }
483         }
484 
485         asoc = ulpq->asoc;
486         if (pd_first) {
487                 /* Make sure we can enter partial deliver.
488                  * We can trigger partial delivery only if framgent
489                  * interleave is set, or the socket is not already
490                  * in  partial delivery.
491                  */
492                 if (!sctp_sk(asoc->base.sk)->frag_interleave &&
493                     atomic_read(&sctp_sk(asoc->base.sk)->pd_mode))
494                         goto done;
495 
496                 cevent = sctp_skb2event(pd_first);
497                 pd_point = sctp_sk(asoc->base.sk)->pd_point;
498                 if (pd_point && pd_point <= pd_len) {
499                         retval = sctp_make_reassembled_event(&ulpq->reasm,
500                                                              pd_first,
501                                                              pd_last);
502                         if (retval)
503                                 sctp_ulpq_set_pd(ulpq);
504                 }
505         }
506 done:
507         return retval;
508 found:
509         retval = sctp_make_reassembled_event(&ulpq->reasm, first_frag, pos);
510         if (retval)
511                 retval->msg_flags |= MSG_EOR;
512         goto done;
513 }
514 
515 /* Retrieve the next set of fragments of a partial message. */
516 static struct sctp_ulpevent *sctp_ulpq_retrieve_partial(struct sctp_ulpq *ulpq)
517 {
518         struct sk_buff *pos, *last_frag, *first_frag;
519         struct sctp_ulpevent *cevent;
520         __u32 ctsn, next_tsn;
521         int is_last;
522         struct sctp_ulpevent *retval;
523 
524         /* The chunks are held in the reasm queue sorted by TSN.
525          * Walk through the queue sequentially and look for the first
526          * sequence of fragmented chunks.
527          */
528 
529         if (skb_queue_empty(&ulpq->reasm))
530                 return NULL;
531 
532         last_frag = first_frag = NULL;
533         retval = NULL;
534         next_tsn = 0;
535         is_last = 0;
536 
537         skb_queue_walk(&ulpq->reasm, pos) {
538                 cevent = sctp_skb2event(pos);
539                 ctsn = cevent->tsn;
540 
541                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
542                 case SCTP_DATA_MIDDLE_FRAG:
543                         if (!first_frag) {
544                                 first_frag = pos;
545                                 next_tsn = ctsn + 1;
546                                 last_frag = pos;
547                         } else if (next_tsn == ctsn)
548                                 next_tsn++;
549                         else
550                                 goto done;
551                         break;
552                 case SCTP_DATA_LAST_FRAG:
553                         if (!first_frag)
554                                 first_frag = pos;
555                         else if (ctsn != next_tsn)
556                                 goto done;
557                         last_frag = pos;
558                         is_last = 1;
559                         goto done;
560                 default:
561                         return NULL;
562                 }
563         }
564 
565         /* We have the reassembled event. There is no need to look
566          * further.
567          */
568 done:
569         retval = sctp_make_reassembled_event(&ulpq->reasm, first_frag, last_frag);
570         if (retval && is_last)
571                 retval->msg_flags |= MSG_EOR;
572 
573         return retval;
574 }
575 
576 
577 /* Helper function to reassemble chunks.  Hold chunks on the reasm queue that
578  * need reassembling.
579  */
580 static struct sctp_ulpevent *sctp_ulpq_reasm(struct sctp_ulpq *ulpq,
581                                                 struct sctp_ulpevent *event)
582 {
583         struct sctp_ulpevent *retval = NULL;
584 
585         /* Check if this is part of a fragmented message.  */
586         if (SCTP_DATA_NOT_FRAG == (event->msg_flags & SCTP_DATA_FRAG_MASK)) {
587                 event->msg_flags |= MSG_EOR;
588                 return event;
589         }
590 
591         sctp_ulpq_store_reasm(ulpq, event);
592         if (!ulpq->pd_mode)
593                 retval = sctp_ulpq_retrieve_reassembled(ulpq);
594         else {
595                 __u32 ctsn, ctsnap;
596 
597                 /* Do not even bother unless this is the next tsn to
598                  * be delivered.
599                  */
600                 ctsn = event->tsn;
601                 ctsnap = sctp_tsnmap_get_ctsn(&ulpq->asoc->peer.tsn_map);
602                 if (TSN_lte(ctsn, ctsnap))
603                         retval = sctp_ulpq_retrieve_partial(ulpq);
604         }
605 
606         return retval;
607 }
608 
609 /* Retrieve the first part (sequential fragments) for partial delivery.  */
610 static struct sctp_ulpevent *sctp_ulpq_retrieve_first(struct sctp_ulpq *ulpq)
611 {
612         struct sk_buff *pos, *last_frag, *first_frag;
613         struct sctp_ulpevent *cevent;
614         __u32 ctsn, next_tsn;
615         struct sctp_ulpevent *retval;
616 
617         /* The chunks are held in the reasm queue sorted by TSN.
618          * Walk through the queue sequentially and look for a sequence of
619          * fragmented chunks that start a datagram.
620          */
621 
622         if (skb_queue_empty(&ulpq->reasm))
623                 return NULL;
624 
625         last_frag = first_frag = NULL;
626         retval = NULL;
627         next_tsn = 0;
628 
629         skb_queue_walk(&ulpq->reasm, pos) {
630                 cevent = sctp_skb2event(pos);
631                 ctsn = cevent->tsn;
632 
633                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
634                 case SCTP_DATA_FIRST_FRAG:
635                         if (!first_frag) {
636                                 first_frag = pos;
637                                 next_tsn = ctsn + 1;
638                                 last_frag = pos;
639                         } else
640                                 goto done;
641                         break;
642 
643                 case SCTP_DATA_MIDDLE_FRAG:
644                         if (!first_frag)
645                                 return NULL;
646                         if (ctsn == next_tsn) {
647                                 next_tsn++;
648                                 last_frag = pos;
649                         } else
650                                 goto done;
651                         break;
652                 default:
653                         return NULL;
654                 }
655         }
656 
657         /* We have the reassembled event. There is no need to look
658          * further.
659          */
660 done:
661         retval = sctp_make_reassembled_event(&ulpq->reasm, first_frag, last_frag);
662         return retval;
663 }
664 
665 /*
666  * Flush out stale fragments from the reassembly queue when processing
667  * a Forward TSN.
668  *
669  * RFC 3758, Section 3.6
670  *
671  * After receiving and processing a FORWARD TSN, the data receiver MUST
672  * take cautions in updating its re-assembly queue.  The receiver MUST
673  * remove any partially reassembled message, which is still missing one
674  * or more TSNs earlier than or equal to the new cumulative TSN point.
675  * In the event that the receiver has invoked the partial delivery API,
676  * a notification SHOULD also be generated to inform the upper layer API
677  * that the message being partially delivered will NOT be completed.
678  */
679 void sctp_ulpq_reasm_flushtsn(struct sctp_ulpq *ulpq, __u32 fwd_tsn)
680 {
681         struct sk_buff *pos, *tmp;
682         struct sctp_ulpevent *event;
683         __u32 tsn;
684 
685         if (skb_queue_empty(&ulpq->reasm))
686                 return;
687 
688         skb_queue_walk_safe(&ulpq->reasm, pos, tmp) {
689                 event = sctp_skb2event(pos);
690                 tsn = event->tsn;
691 
692                 /* Since the entire message must be abandoned by the
693                  * sender (item A3 in Section 3.5, RFC 3758), we can
694                  * free all fragments on the list that are less then
695                  * or equal to ctsn_point
696                  */
697                 if (TSN_lte(tsn, fwd_tsn)) {
698                         __skb_unlink(pos, &ulpq->reasm);
699                         sctp_ulpevent_free(event);
700                 } else
701                         break;
702         }
703 }
704 
705 /*
706  * Drain the reassembly queue.  If we just cleared parted delivery, it
707  * is possible that the reassembly queue will contain already reassembled
708  * messages.  Retrieve any such messages and give them to the user.
709  */
710 static void sctp_ulpq_reasm_drain(struct sctp_ulpq *ulpq)
711 {
712         struct sctp_ulpevent *event = NULL;
713         struct sk_buff_head temp;
714 
715         if (skb_queue_empty(&ulpq->reasm))
716                 return;
717 
718         while ((event = sctp_ulpq_retrieve_reassembled(ulpq)) != NULL) {
719                 /* Do ordering if needed.  */
720                 if ((event) && (event->msg_flags & MSG_EOR)){
721                         skb_queue_head_init(&temp);
722                         __skb_queue_tail(&temp, sctp_event2skb(event));
723 
724                         event = sctp_ulpq_order(ulpq, event);
725                 }
726 
727                 /* Send event to the ULP.  'event' is the
728                  * sctp_ulpevent for  very first SKB on the  temp' list.
729                  */
730                 if (event)
731                         sctp_ulpq_tail_event(ulpq, event);
732         }
733 }
734 
735 
736 /* Helper function to gather skbs that have possibly become
737  * ordered by an an incoming chunk.
738  */
739 static void sctp_ulpq_retrieve_ordered(struct sctp_ulpq *ulpq,
740                                               struct sctp_ulpevent *event)
741 {
742         struct sk_buff_head *event_list;
743         struct sk_buff *pos, *tmp;
744         struct sctp_ulpevent *cevent;
745         struct sctp_stream *in;
746         __u16 sid, csid;
747         __u16 ssn, cssn;
748 
749         sid = event->stream;
750         ssn = event->ssn;
751         in  = &ulpq->asoc->ssnmap->in;
752 
753         event_list = (struct sk_buff_head *) sctp_event2skb(event)->prev;
754 
755         /* We are holding the chunks by stream, by SSN.  */
756         sctp_skb_for_each(pos, &ulpq->lobby, tmp) {
757                 cevent = (struct sctp_ulpevent *) pos->cb;
758                 csid = cevent->stream;
759                 cssn = cevent->ssn;
760 
761                 /* Have we gone too far?  */
762                 if (csid > sid)
763                         break;
764 
765                 /* Have we not gone far enough?  */
766                 if (csid < sid)
767                         continue;
768 
769                 if (cssn != sctp_ssn_peek(in, sid))
770                         break;
771 
772                 /* Found it, so mark in the ssnmap. */
773                 sctp_ssn_next(in, sid);
774 
775                 __skb_unlink(pos, &ulpq->lobby);
776 
777                 /* Attach all gathered skbs to the event.  */
778                 __skb_queue_tail(event_list, pos);
779         }
780 }
781 
782 /* Helper function to store chunks needing ordering.  */
783 static void sctp_ulpq_store_ordered(struct sctp_ulpq *ulpq,
784                                            struct sctp_ulpevent *event)
785 {
786         struct sk_buff *pos;
787         struct sctp_ulpevent *cevent;
788         __u16 sid, csid;
789         __u16 ssn, cssn;
790 
791         pos = skb_peek_tail(&ulpq->lobby);
792         if (!pos) {
793                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
794                 return;
795         }
796 
797         sid = event->stream;
798         ssn = event->ssn;
799 
800         cevent = (struct sctp_ulpevent *) pos->cb;
801         csid = cevent->stream;
802         cssn = cevent->ssn;
803         if (sid > csid) {
804                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
805                 return;
806         }
807 
808         if ((sid == csid) && SSN_lt(cssn, ssn)) {
809                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
810                 return;
811         }
812 
813         /* Find the right place in this list.  We store them by
814          * stream ID and then by SSN.
815          */
816         skb_queue_walk(&ulpq->lobby, pos) {
817                 cevent = (struct sctp_ulpevent *) pos->cb;
818                 csid = cevent->stream;
819                 cssn = cevent->ssn;
820 
821                 if (csid > sid)
822                         break;
823                 if (csid == sid && SSN_lt(ssn, cssn))
824                         break;
825         }
826 
827 
828         /* Insert before pos. */
829         __skb_queue_before(&ulpq->lobby, pos, sctp_event2skb(event));
830 }
831 
832 static struct sctp_ulpevent *sctp_ulpq_order(struct sctp_ulpq *ulpq,
833                                              struct sctp_ulpevent *event)
834 {
835         __u16 sid, ssn;
836         struct sctp_stream *in;
837 
838         /* Check if this message needs ordering.  */
839         if (SCTP_DATA_UNORDERED & event->msg_flags)
840                 return event;
841 
842         /* Note: The stream ID must be verified before this routine.  */
843         sid = event->stream;
844         ssn = event->ssn;
845         in  = &ulpq->asoc->ssnmap->in;
846 
847         /* Is this the expected SSN for this stream ID?  */
848         if (ssn != sctp_ssn_peek(in, sid)) {
849                 /* We've received something out of order, so find where it
850                  * needs to be placed.  We order by stream and then by SSN.
851                  */
852                 sctp_ulpq_store_ordered(ulpq, event);
853                 return NULL;
854         }
855 
856         /* Mark that the next chunk has been found.  */
857         sctp_ssn_next(in, sid);
858 
859         /* Go find any other chunks that were waiting for
860          * ordering.
861          */
862         sctp_ulpq_retrieve_ordered(ulpq, event);
863 
864         return event;
865 }
866 
867 /* Helper function to gather skbs that have possibly become
868  * ordered by forward tsn skipping their dependencies.
869  */
870 static void sctp_ulpq_reap_ordered(struct sctp_ulpq *ulpq, __u16 sid)
871 {
872         struct sk_buff *pos, *tmp;
873         struct sctp_ulpevent *cevent;
874         struct sctp_ulpevent *event;
875         struct sctp_stream *in;
876         struct sk_buff_head temp;
877         struct sk_buff_head *lobby = &ulpq->lobby;
878         __u16 csid, cssn;
879 
880         in  = &ulpq->asoc->ssnmap->in;
881 
882         /* We are holding the chunks by stream, by SSN.  */
883         skb_queue_head_init(&temp);
884         event = NULL;
885         sctp_skb_for_each(pos, lobby, tmp) {
886                 cevent = (struct sctp_ulpevent *) pos->cb;
887                 csid = cevent->stream;
888                 cssn = cevent->ssn;
889 
890                 /* Have we gone too far?  */
891                 if (csid > sid)
892                         break;
893 
894                 /* Have we not gone far enough?  */
895                 if (csid < sid)
896                         continue;
897 
898                 /* see if this ssn has been marked by skipping */
899                 if (!SSN_lt(cssn, sctp_ssn_peek(in, csid)))
900                         break;
901 
902                 __skb_unlink(pos, lobby);
903                 if (!event)
904                         /* Create a temporary list to collect chunks on.  */
905                         event = sctp_skb2event(pos);
906 
907                 /* Attach all gathered skbs to the event.  */
908                 __skb_queue_tail(&temp, pos);
909         }
910 
911         /* If we didn't reap any data, see if the next expected SSN
912          * is next on the queue and if so, use that.
913          */
914         if (event == NULL && pos != (struct sk_buff *)lobby) {
915                 cevent = (struct sctp_ulpevent *) pos->cb;
916                 csid = cevent->stream;
917                 cssn = cevent->ssn;
918 
919                 if (csid == sid && cssn == sctp_ssn_peek(in, csid)) {
920                         sctp_ssn_next(in, csid);
921                         __skb_unlink(pos, lobby);
922                         __skb_queue_tail(&temp, pos);
923                         event = sctp_skb2event(pos);
924                 }
925         }
926 
927         /* Send event to the ULP.  'event' is the sctp_ulpevent for
928          * very first SKB on the 'temp' list.
929          */
930         if (event) {
931                 /* see if we have more ordered that we can deliver */
932                 sctp_ulpq_retrieve_ordered(ulpq, event);
933                 sctp_ulpq_tail_event(ulpq, event);
934         }
935 }
936 
937 /* Skip over an SSN. This is used during the processing of
938  * Forwared TSN chunk to skip over the abandoned ordered data
939  */
940 void sctp_ulpq_skip(struct sctp_ulpq *ulpq, __u16 sid, __u16 ssn)
941 {
942         struct sctp_stream *in;
943 
944         /* Note: The stream ID must be verified before this routine.  */
945         in  = &ulpq->asoc->ssnmap->in;
946 
947         /* Is this an old SSN?  If so ignore. */
948         if (SSN_lt(ssn, sctp_ssn_peek(in, sid)))
949                 return;
950 
951         /* Mark that we are no longer expecting this SSN or lower. */
952         sctp_ssn_skip(in, sid, ssn);
953 
954         /* Go find any other chunks that were waiting for
955          * ordering and deliver them if needed.
956          */
957         sctp_ulpq_reap_ordered(ulpq, sid);
958 }
959 
960 static __u16 sctp_ulpq_renege_list(struct sctp_ulpq *ulpq,
961                 struct sk_buff_head *list, __u16 needed)
962 {
963         __u16 freed = 0;
964         __u32 tsn;
965         struct sk_buff *skb;
966         struct sctp_ulpevent *event;
967         struct sctp_tsnmap *tsnmap;
968 
969         tsnmap = &ulpq->asoc->peer.tsn_map;
970 
971         while ((skb = __skb_dequeue_tail(list)) != NULL) {
972                 freed += skb_headlen(skb);
973                 event = sctp_skb2event(skb);
974                 tsn = event->tsn;
975 
976                 sctp_ulpevent_free(event);
977                 sctp_tsnmap_renege(tsnmap, tsn);
978                 if (freed >= needed)
979                         return freed;
980         }
981 
982         return freed;
983 }
984 
985 /* Renege 'needed' bytes from the ordering queue. */
986 static __u16 sctp_ulpq_renege_order(struct sctp_ulpq *ulpq, __u16 needed)
987 {
988         return sctp_ulpq_renege_list(ulpq, &ulpq->lobby, needed);
989 }
990 
991 /* Renege 'needed' bytes from the reassembly queue. */
992 static __u16 sctp_ulpq_renege_frags(struct sctp_ulpq *ulpq, __u16 needed)
993 {
994         return sctp_ulpq_renege_list(ulpq, &ulpq->reasm, needed);
995 }
996 
997 /* Partial deliver the first message as there is pressure on rwnd. */
998 void sctp_ulpq_partial_delivery(struct sctp_ulpq *ulpq,
999                                 struct sctp_chunk *chunk,
1000                                 gfp_t gfp)
1001 {
1002         struct sctp_ulpevent *event;
1003         struct sctp_association *asoc;
1004         struct sctp_sock *sp;
1005 
1006         asoc = ulpq->asoc;
1007         sp = sctp_sk(asoc->base.sk);
1008 
1009         /* If the association is already in Partial Delivery mode
1010          * we have noting to do.
1011          */
1012         if (ulpq->pd_mode)
1013                 return;
1014 
1015         /* If the user enabled fragment interleave socket option,
1016          * multiple associations can enter partial delivery.
1017          * Otherwise, we can only enter partial delivery if the
1018          * socket is not in partial deliver mode.
1019          */
1020         if (sp->frag_interleave || atomic_read(&sp->pd_mode) == 0) {
1021                 /* Is partial delivery possible?  */
1022                 event = sctp_ulpq_retrieve_first(ulpq);
1023                 /* Send event to the ULP.   */
1024                 if (event) {
1025                         sctp_ulpq_tail_event(ulpq, event);
1026                         sctp_ulpq_set_pd(ulpq);
1027                         return;
1028                 }
1029         }
1030 }
1031 
1032 /* Renege some packets to make room for an incoming chunk.  */
1033 void sctp_ulpq_renege(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
1034                       gfp_t gfp)
1035 {
1036         struct sctp_association *asoc;
1037         __u16 needed, freed;
1038 
1039         asoc = ulpq->asoc;
1040 
1041         if (chunk) {
1042                 needed = ntohs(chunk->chunk_hdr->length);
1043                 needed -= sizeof(sctp_data_chunk_t);
1044         } else
1045                 needed = SCTP_DEFAULT_MAXWINDOW;
1046 
1047         freed = 0;
1048 
1049         if (skb_queue_empty(&asoc->base.sk->sk_receive_queue)) {
1050                 freed = sctp_ulpq_renege_order(ulpq, needed);
1051                 if (freed < needed) {
1052                         freed += sctp_ulpq_renege_frags(ulpq, needed - freed);
1053                 }
1054         }
1055         /* If able to free enough room, accept this chunk. */
1056         if (chunk && (freed >= needed)) {
1057                 __u32 tsn;
1058                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1059                 sctp_tsnmap_mark(&asoc->peer.tsn_map, tsn);
1060                 sctp_ulpq_tail_data(ulpq, chunk, gfp);
1061 
1062                 sctp_ulpq_partial_delivery(ulpq, chunk, gfp);
1063         }
1064 
1065         sk_mem_reclaim(asoc->base.sk);
1066 }
1067 
1068 
1069 
1070 /* Notify the application if an association is aborted and in
1071  * partial delivery mode.  Send up any pending received messages.
1072  */
1073 void sctp_ulpq_abort_pd(struct sctp_ulpq *ulpq, gfp_t gfp)
1074 {
1075         struct sctp_ulpevent *ev = NULL;
1076         struct sock *sk;
1077 
1078         if (!ulpq->pd_mode)
1079                 return;
1080 
1081         sk = ulpq->asoc->base.sk;
1082         if (sctp_ulpevent_type_enabled(SCTP_PARTIAL_DELIVERY_EVENT,
1083                                        &sctp_sk(sk)->subscribe))
1084                 ev = sctp_ulpevent_make_pdapi(ulpq->asoc,
1085                                               SCTP_PARTIAL_DELIVERY_ABORTED,
1086                                               gfp);
1087         if (ev)
1088                 __skb_queue_tail(&sk->sk_receive_queue, sctp_event2skb(ev));
1089 
1090         /* If there is data waiting, send it up the socket now. */
1091         if (sctp_ulpq_clear_pd(ulpq) || ev)
1092                 sk->sk_data_ready(sk, 0);
1093 }
1094 

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