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

Version: ~ [ linux-5.2-rc4 ] ~ [ linux-5.1.9 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.50 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.125 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.181 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.181 ] ~ [ 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         struct sctp_ulpevent *event;
109 
110         /* Create an event from the incoming chunk. */
111         event = sctp_ulpevent_make_rcvmsg(chunk->asoc, chunk, gfp);
112         if (!event)
113                 return -ENOMEM;
114 
115         /* Do reassembly if needed.  */
116         event = sctp_ulpq_reasm(ulpq, event);
117 
118         /* Do ordering if needed.  */
119         if ((event) && (event->msg_flags & MSG_EOR)){
120                 /* Create a temporary list to collect chunks on.  */
121                 skb_queue_head_init(&temp);
122                 __skb_queue_tail(&temp, sctp_event2skb(event));
123 
124                 event = sctp_ulpq_order(ulpq, event);
125         }
126 
127         /* Send event to the ULP.  'event' is the sctp_ulpevent for
128          * very first SKB on the 'temp' list.
129          */
130         if (event)
131                 sctp_ulpq_tail_event(ulpq, event);
132 
133         return 0;
134 }
135 
136 /* Add a new event for propagation to the ULP.  */
137 /* Clear the partial delivery mode for this socket.   Note: This
138  * assumes that no association is currently in partial delivery mode.
139  */
140 int sctp_clear_pd(struct sock *sk, struct sctp_association *asoc)
141 {
142         struct sctp_sock *sp = sctp_sk(sk);
143 
144         if (atomic_dec_and_test(&sp->pd_mode)) {
145                 /* This means there are no other associations in PD, so
146                  * we can go ahead and clear out the lobby in one shot
147                  */
148                 if (!skb_queue_empty(&sp->pd_lobby)) {
149                         struct list_head *list;
150                         sctp_skb_list_tail(&sp->pd_lobby, &sk->sk_receive_queue);
151                         list = (struct list_head *)&sctp_sk(sk)->pd_lobby;
152                         INIT_LIST_HEAD(list);
153                         return 1;
154                 }
155         } else {
156                 /* There are other associations in PD, so we only need to
157                  * pull stuff out of the lobby that belongs to the
158                  * associations that is exiting PD (all of its notifications
159                  * are posted here).
160                  */
161                 if (!skb_queue_empty(&sp->pd_lobby) && asoc) {
162                         struct sk_buff *skb, *tmp;
163                         struct sctp_ulpevent *event;
164 
165                         sctp_skb_for_each(skb, &sp->pd_lobby, tmp) {
166                                 event = sctp_skb2event(skb);
167                                 if (event->asoc == asoc) {
168                                         __skb_unlink(skb, &sp->pd_lobby);
169                                         __skb_queue_tail(&sk->sk_receive_queue,
170                                                          skb);
171                                 }
172                         }
173                 }
174         }
175 
176         return 0;
177 }
178 
179 /* Set the pd_mode on the socket and ulpq */
180 static void sctp_ulpq_set_pd(struct sctp_ulpq *ulpq)
181 {
182         struct sctp_sock *sp = sctp_sk(ulpq->asoc->base.sk);
183 
184         atomic_inc(&sp->pd_mode);
185         ulpq->pd_mode = 1;
186 }
187 
188 /* Clear the pd_mode and restart any pending messages waiting for delivery. */
189 static int sctp_ulpq_clear_pd(struct sctp_ulpq *ulpq)
190 {
191         ulpq->pd_mode = 0;
192         sctp_ulpq_reasm_drain(ulpq);
193         return sctp_clear_pd(ulpq->asoc->base.sk, ulpq->asoc);
194 }
195 
196 /* If the SKB of 'event' is on a list, it is the first such member
197  * of that list.
198  */
199 int sctp_ulpq_tail_event(struct sctp_ulpq *ulpq, struct sctp_ulpevent *event)
200 {
201         struct sock *sk = ulpq->asoc->base.sk;
202         struct sk_buff_head *queue, *skb_list;
203         struct sk_buff *skb = sctp_event2skb(event);
204         int clear_pd = 0;
205 
206         skb_list = (struct sk_buff_head *) skb->prev;
207 
208         /* If the socket is just going to throw this away, do not
209          * even try to deliver it.
210          */
211         if (sock_flag(sk, SOCK_DEAD) || (sk->sk_shutdown & RCV_SHUTDOWN))
212                 goto out_free;
213 
214         /* Check if the user wishes to receive this event.  */
215         if (!sctp_ulpevent_is_enabled(event, &sctp_sk(sk)->subscribe))
216                 goto out_free;
217 
218         /* If we are in partial delivery mode, post to the lobby until
219          * partial delivery is cleared, unless, of course _this_ is
220          * the association the cause of the partial delivery.
221          */
222 
223         if (atomic_read(&sctp_sk(sk)->pd_mode) == 0) {
224                 queue = &sk->sk_receive_queue;
225         } else {
226                 if (ulpq->pd_mode) {
227                         /* If the association is in partial delivery, we
228                          * need to finish delivering the partially processed
229                          * packet before passing any other data.  This is
230                          * because we don't truly support stream interleaving.
231                          */
232                         if ((event->msg_flags & MSG_NOTIFICATION) ||
233                             (SCTP_DATA_NOT_FRAG ==
234                                     (event->msg_flags & SCTP_DATA_FRAG_MASK)))
235                                 queue = &sctp_sk(sk)->pd_lobby;
236                         else {
237                                 clear_pd = event->msg_flags & MSG_EOR;
238                                 queue = &sk->sk_receive_queue;
239                         }
240                 } else {
241                         /*
242                          * If fragment interleave is enabled, we
243                          * can queue this to the receive queue instead
244                          * of the lobby.
245                          */
246                         if (sctp_sk(sk)->frag_interleave)
247                                 queue = &sk->sk_receive_queue;
248                         else
249                                 queue = &sctp_sk(sk)->pd_lobby;
250                 }
251         }
252 
253         /* If we are harvesting multiple skbs they will be
254          * collected on a list.
255          */
256         if (skb_list)
257                 sctp_skb_list_tail(skb_list, queue);
258         else
259                 __skb_queue_tail(queue, skb);
260 
261         /* Did we just complete partial delivery and need to get
262          * rolling again?  Move pending data to the receive
263          * queue.
264          */
265         if (clear_pd)
266                 sctp_ulpq_clear_pd(ulpq);
267 
268         if (queue == &sk->sk_receive_queue)
269                 sk->sk_data_ready(sk, 0);
270         return 1;
271 
272 out_free:
273         if (skb_list)
274                 sctp_queue_purge_ulpevents(skb_list);
275         else
276                 sctp_ulpevent_free(event);
277 
278         return 0;
279 }
280 
281 /* 2nd Level Abstractions */
282 
283 /* Helper function to store chunks that need to be reassembled.  */
284 static void sctp_ulpq_store_reasm(struct sctp_ulpq *ulpq,
285                                          struct sctp_ulpevent *event)
286 {
287         struct sk_buff *pos;
288         struct sctp_ulpevent *cevent;
289         __u32 tsn, ctsn;
290 
291         tsn = event->tsn;
292 
293         /* See if it belongs at the end. */
294         pos = skb_peek_tail(&ulpq->reasm);
295         if (!pos) {
296                 __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
297                 return;
298         }
299 
300         /* Short circuit just dropping it at the end. */
301         cevent = sctp_skb2event(pos);
302         ctsn = cevent->tsn;
303         if (TSN_lt(ctsn, tsn)) {
304                 __skb_queue_tail(&ulpq->reasm, sctp_event2skb(event));
305                 return;
306         }
307 
308         /* Find the right place in this list. We store them by TSN.  */
309         skb_queue_walk(&ulpq->reasm, pos) {
310                 cevent = sctp_skb2event(pos);
311                 ctsn = cevent->tsn;
312 
313                 if (TSN_lt(tsn, ctsn))
314                         break;
315         }
316 
317         /* Insert before pos. */
318         __skb_queue_before(&ulpq->reasm, pos, sctp_event2skb(event));
319 
320 }
321 
322 /* Helper function to return an event corresponding to the reassembled
323  * datagram.
324  * This routine creates a re-assembled skb given the first and last skb's
325  * as stored in the reassembly queue. The skb's may be non-linear if the sctp
326  * payload was fragmented on the way and ip had to reassemble them.
327  * We add the rest of skb's to the first skb's fraglist.
328  */
329 static struct sctp_ulpevent *sctp_make_reassembled_event(struct net *net,
330         struct sk_buff_head *queue, struct sk_buff *f_frag,
331         struct sk_buff *l_frag)
332 {
333         struct sk_buff *pos;
334         struct sk_buff *new = NULL;
335         struct sctp_ulpevent *event;
336         struct sk_buff *pnext, *last;
337         struct sk_buff *list = skb_shinfo(f_frag)->frag_list;
338 
339         /* Store the pointer to the 2nd skb */
340         if (f_frag == l_frag)
341                 pos = NULL;
342         else
343                 pos = f_frag->next;
344 
345         /* Get the last skb in the f_frag's frag_list if present. */
346         for (last = list; list; last = list, list = list->next);
347 
348         /* Add the list of remaining fragments to the first fragments
349          * frag_list.
350          */
351         if (last)
352                 last->next = pos;
353         else {
354                 if (skb_cloned(f_frag)) {
355                         /* This is a cloned skb, we can't just modify
356                          * the frag_list.  We need a new skb to do that.
357                          * Instead of calling skb_unshare(), we'll do it
358                          * ourselves since we need to delay the free.
359                          */
360                         new = skb_copy(f_frag, GFP_ATOMIC);
361                         if (!new)
362                                 return NULL;    /* try again later */
363 
364                         sctp_skb_set_owner_r(new, f_frag->sk);
365 
366                         skb_shinfo(new)->frag_list = pos;
367                 } else
368                         skb_shinfo(f_frag)->frag_list = pos;
369         }
370 
371         /* Remove the first fragment from the reassembly queue.  */
372         __skb_unlink(f_frag, queue);
373 
374         /* if we did unshare, then free the old skb and re-assign */
375         if (new) {
376                 kfree_skb(f_frag);
377                 f_frag = new;
378         }
379 
380         while (pos) {
381 
382                 pnext = pos->next;
383 
384                 /* Update the len and data_len fields of the first fragment. */
385                 f_frag->len += pos->len;
386                 f_frag->data_len += pos->len;
387 
388                 /* Remove the fragment from the reassembly queue.  */
389                 __skb_unlink(pos, queue);
390 
391                 /* Break if we have reached the last fragment.  */
392                 if (pos == l_frag)
393                         break;
394                 pos->next = pnext;
395                 pos = pnext;
396         }
397 
398         event = sctp_skb2event(f_frag);
399         SCTP_INC_STATS(net, SCTP_MIB_REASMUSRMSGS);
400 
401         return event;
402 }
403 
404 
405 /* Helper function to check if an incoming chunk has filled up the last
406  * missing fragment in a SCTP datagram and return the corresponding event.
407  */
408 static struct sctp_ulpevent *sctp_ulpq_retrieve_reassembled(struct sctp_ulpq *ulpq)
409 {
410         struct sk_buff *pos;
411         struct sctp_ulpevent *cevent;
412         struct sk_buff *first_frag = NULL;
413         __u32 ctsn, next_tsn;
414         struct sctp_ulpevent *retval = NULL;
415         struct sk_buff *pd_first = NULL;
416         struct sk_buff *pd_last = NULL;
417         size_t pd_len = 0;
418         struct sctp_association *asoc;
419         u32 pd_point;
420 
421         /* Initialized to 0 just to avoid compiler warning message.  Will
422          * never be used with this value. It is referenced only after it
423          * is set when we find the first fragment of a message.
424          */
425         next_tsn = 0;
426 
427         /* The chunks are held in the reasm queue sorted by TSN.
428          * Walk through the queue sequentially and look for a sequence of
429          * fragmented chunks that complete a datagram.
430          * 'first_frag' and next_tsn are reset when we find a chunk which
431          * is the first fragment of a datagram. Once these 2 fields are set
432          * we expect to find the remaining middle fragments and the last
433          * fragment in order. If not, first_frag is reset to NULL and we
434          * start the next pass when we find another first fragment.
435          *
436          * There is a potential to do partial delivery if user sets
437          * SCTP_PARTIAL_DELIVERY_POINT option. Lets count some things here
438          * to see if can do PD.
439          */
440         skb_queue_walk(&ulpq->reasm, pos) {
441                 cevent = sctp_skb2event(pos);
442                 ctsn = cevent->tsn;
443 
444                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
445                 case SCTP_DATA_FIRST_FRAG:
446                         /* If this "FIRST_FRAG" is the first
447                          * element in the queue, then count it towards
448                          * possible PD.
449                          */
450                         if (pos == ulpq->reasm.next) {
451                             pd_first = pos;
452                             pd_last = pos;
453                             pd_len = pos->len;
454                         } else {
455                             pd_first = NULL;
456                             pd_last = NULL;
457                             pd_len = 0;
458                         }
459 
460                         first_frag = pos;
461                         next_tsn = ctsn + 1;
462                         break;
463 
464                 case SCTP_DATA_MIDDLE_FRAG:
465                         if ((first_frag) && (ctsn == next_tsn)) {
466                                 next_tsn++;
467                                 if (pd_first) {
468                                     pd_last = pos;
469                                     pd_len += pos->len;
470                                 }
471                         } else
472                                 first_frag = NULL;
473                         break;
474 
475                 case SCTP_DATA_LAST_FRAG:
476                         if (first_frag && (ctsn == next_tsn))
477                                 goto found;
478                         else
479                                 first_frag = NULL;
480                         break;
481                 }
482         }
483 
484         asoc = ulpq->asoc;
485         if (pd_first) {
486                 /* Make sure we can enter partial deliver.
487                  * We can trigger partial delivery only if framgent
488                  * interleave is set, or the socket is not already
489                  * in  partial delivery.
490                  */
491                 if (!sctp_sk(asoc->base.sk)->frag_interleave &&
492                     atomic_read(&sctp_sk(asoc->base.sk)->pd_mode))
493                         goto done;
494 
495                 cevent = sctp_skb2event(pd_first);
496                 pd_point = sctp_sk(asoc->base.sk)->pd_point;
497                 if (pd_point && pd_point <= pd_len) {
498                         retval = sctp_make_reassembled_event(sock_net(asoc->base.sk),
499                                                              &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(sock_net(ulpq->asoc->base.sk),
510                                              &ulpq->reasm, first_frag, pos);
511         if (retval)
512                 retval->msg_flags |= MSG_EOR;
513         goto done;
514 }
515 
516 /* Retrieve the next set of fragments of a partial message. */
517 static struct sctp_ulpevent *sctp_ulpq_retrieve_partial(struct sctp_ulpq *ulpq)
518 {
519         struct sk_buff *pos, *last_frag, *first_frag;
520         struct sctp_ulpevent *cevent;
521         __u32 ctsn, next_tsn;
522         int is_last;
523         struct sctp_ulpevent *retval;
524 
525         /* The chunks are held in the reasm queue sorted by TSN.
526          * Walk through the queue sequentially and look for the first
527          * sequence of fragmented chunks.
528          */
529 
530         if (skb_queue_empty(&ulpq->reasm))
531                 return NULL;
532 
533         last_frag = first_frag = NULL;
534         retval = NULL;
535         next_tsn = 0;
536         is_last = 0;
537 
538         skb_queue_walk(&ulpq->reasm, pos) {
539                 cevent = sctp_skb2event(pos);
540                 ctsn = cevent->tsn;
541 
542                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
543                 case SCTP_DATA_MIDDLE_FRAG:
544                         if (!first_frag) {
545                                 first_frag = pos;
546                                 next_tsn = ctsn + 1;
547                                 last_frag = pos;
548                         } else if (next_tsn == ctsn)
549                                 next_tsn++;
550                         else
551                                 goto done;
552                         break;
553                 case SCTP_DATA_LAST_FRAG:
554                         if (!first_frag)
555                                 first_frag = pos;
556                         else if (ctsn != next_tsn)
557                                 goto done;
558                         last_frag = pos;
559                         is_last = 1;
560                         goto done;
561                 default:
562                         return NULL;
563                 }
564         }
565 
566         /* We have the reassembled event. There is no need to look
567          * further.
568          */
569 done:
570         retval = sctp_make_reassembled_event(sock_net(ulpq->asoc->base.sk),
571                                         &ulpq->reasm, first_frag, last_frag);
572         if (retval && is_last)
573                 retval->msg_flags |= MSG_EOR;
574 
575         return retval;
576 }
577 
578 
579 /* Helper function to reassemble chunks.  Hold chunks on the reasm queue that
580  * need reassembling.
581  */
582 static struct sctp_ulpevent *sctp_ulpq_reasm(struct sctp_ulpq *ulpq,
583                                                 struct sctp_ulpevent *event)
584 {
585         struct sctp_ulpevent *retval = NULL;
586 
587         /* Check if this is part of a fragmented message.  */
588         if (SCTP_DATA_NOT_FRAG == (event->msg_flags & SCTP_DATA_FRAG_MASK)) {
589                 event->msg_flags |= MSG_EOR;
590                 return event;
591         }
592 
593         sctp_ulpq_store_reasm(ulpq, event);
594         if (!ulpq->pd_mode)
595                 retval = sctp_ulpq_retrieve_reassembled(ulpq);
596         else {
597                 __u32 ctsn, ctsnap;
598 
599                 /* Do not even bother unless this is the next tsn to
600                  * be delivered.
601                  */
602                 ctsn = event->tsn;
603                 ctsnap = sctp_tsnmap_get_ctsn(&ulpq->asoc->peer.tsn_map);
604                 if (TSN_lte(ctsn, ctsnap))
605                         retval = sctp_ulpq_retrieve_partial(ulpq);
606         }
607 
608         return retval;
609 }
610 
611 /* Retrieve the first part (sequential fragments) for partial delivery.  */
612 static struct sctp_ulpevent *sctp_ulpq_retrieve_first(struct sctp_ulpq *ulpq)
613 {
614         struct sk_buff *pos, *last_frag, *first_frag;
615         struct sctp_ulpevent *cevent;
616         __u32 ctsn, next_tsn;
617         struct sctp_ulpevent *retval;
618 
619         /* The chunks are held in the reasm queue sorted by TSN.
620          * Walk through the queue sequentially and look for a sequence of
621          * fragmented chunks that start a datagram.
622          */
623 
624         if (skb_queue_empty(&ulpq->reasm))
625                 return NULL;
626 
627         last_frag = first_frag = NULL;
628         retval = NULL;
629         next_tsn = 0;
630 
631         skb_queue_walk(&ulpq->reasm, pos) {
632                 cevent = sctp_skb2event(pos);
633                 ctsn = cevent->tsn;
634 
635                 switch (cevent->msg_flags & SCTP_DATA_FRAG_MASK) {
636                 case SCTP_DATA_FIRST_FRAG:
637                         if (!first_frag) {
638                                 first_frag = pos;
639                                 next_tsn = ctsn + 1;
640                                 last_frag = pos;
641                         } else
642                                 goto done;
643                         break;
644 
645                 case SCTP_DATA_MIDDLE_FRAG:
646                         if (!first_frag)
647                                 return NULL;
648                         if (ctsn == next_tsn) {
649                                 next_tsn++;
650                                 last_frag = pos;
651                         } else
652                                 goto done;
653                         break;
654                 default:
655                         return NULL;
656                 }
657         }
658 
659         /* We have the reassembled event. There is no need to look
660          * further.
661          */
662 done:
663         retval = sctp_make_reassembled_event(sock_net(ulpq->asoc->base.sk),
664                                         &ulpq->reasm, first_frag, last_frag);
665         return retval;
666 }
667 
668 /*
669  * Flush out stale fragments from the reassembly queue when processing
670  * a Forward TSN.
671  *
672  * RFC 3758, Section 3.6
673  *
674  * After receiving and processing a FORWARD TSN, the data receiver MUST
675  * take cautions in updating its re-assembly queue.  The receiver MUST
676  * remove any partially reassembled message, which is still missing one
677  * or more TSNs earlier than or equal to the new cumulative TSN point.
678  * In the event that the receiver has invoked the partial delivery API,
679  * a notification SHOULD also be generated to inform the upper layer API
680  * that the message being partially delivered will NOT be completed.
681  */
682 void sctp_ulpq_reasm_flushtsn(struct sctp_ulpq *ulpq, __u32 fwd_tsn)
683 {
684         struct sk_buff *pos, *tmp;
685         struct sctp_ulpevent *event;
686         __u32 tsn;
687 
688         if (skb_queue_empty(&ulpq->reasm))
689                 return;
690 
691         skb_queue_walk_safe(&ulpq->reasm, pos, tmp) {
692                 event = sctp_skb2event(pos);
693                 tsn = event->tsn;
694 
695                 /* Since the entire message must be abandoned by the
696                  * sender (item A3 in Section 3.5, RFC 3758), we can
697                  * free all fragments on the list that are less then
698                  * or equal to ctsn_point
699                  */
700                 if (TSN_lte(tsn, fwd_tsn)) {
701                         __skb_unlink(pos, &ulpq->reasm);
702                         sctp_ulpevent_free(event);
703                 } else
704                         break;
705         }
706 }
707 
708 /*
709  * Drain the reassembly queue.  If we just cleared parted delivery, it
710  * is possible that the reassembly queue will contain already reassembled
711  * messages.  Retrieve any such messages and give them to the user.
712  */
713 static void sctp_ulpq_reasm_drain(struct sctp_ulpq *ulpq)
714 {
715         struct sctp_ulpevent *event = NULL;
716         struct sk_buff_head temp;
717 
718         if (skb_queue_empty(&ulpq->reasm))
719                 return;
720 
721         while ((event = sctp_ulpq_retrieve_reassembled(ulpq)) != NULL) {
722                 /* Do ordering if needed.  */
723                 if ((event) && (event->msg_flags & MSG_EOR)){
724                         skb_queue_head_init(&temp);
725                         __skb_queue_tail(&temp, sctp_event2skb(event));
726 
727                         event = sctp_ulpq_order(ulpq, event);
728                 }
729 
730                 /* Send event to the ULP.  'event' is the
731                  * sctp_ulpevent for  very first SKB on the  temp' list.
732                  */
733                 if (event)
734                         sctp_ulpq_tail_event(ulpq, event);
735         }
736 }
737 
738 
739 /* Helper function to gather skbs that have possibly become
740  * ordered by an an incoming chunk.
741  */
742 static void sctp_ulpq_retrieve_ordered(struct sctp_ulpq *ulpq,
743                                               struct sctp_ulpevent *event)
744 {
745         struct sk_buff_head *event_list;
746         struct sk_buff *pos, *tmp;
747         struct sctp_ulpevent *cevent;
748         struct sctp_stream *in;
749         __u16 sid, csid, cssn;
750 
751         sid = event->stream;
752         in  = &ulpq->asoc->ssnmap->in;
753 
754         event_list = (struct sk_buff_head *) sctp_event2skb(event)->prev;
755 
756         /* We are holding the chunks by stream, by SSN.  */
757         sctp_skb_for_each(pos, &ulpq->lobby, tmp) {
758                 cevent = (struct sctp_ulpevent *) pos->cb;
759                 csid = cevent->stream;
760                 cssn = cevent->ssn;
761 
762                 /* Have we gone too far?  */
763                 if (csid > sid)
764                         break;
765 
766                 /* Have we not gone far enough?  */
767                 if (csid < sid)
768                         continue;
769 
770                 if (cssn != sctp_ssn_peek(in, sid))
771                         break;
772 
773                 /* Found it, so mark in the ssnmap. */
774                 sctp_ssn_next(in, sid);
775 
776                 __skb_unlink(pos, &ulpq->lobby);
777 
778                 /* Attach all gathered skbs to the event.  */
779                 __skb_queue_tail(event_list, pos);
780         }
781 }
782 
783 /* Helper function to store chunks needing ordering.  */
784 static void sctp_ulpq_store_ordered(struct sctp_ulpq *ulpq,
785                                            struct sctp_ulpevent *event)
786 {
787         struct sk_buff *pos;
788         struct sctp_ulpevent *cevent;
789         __u16 sid, csid;
790         __u16 ssn, cssn;
791 
792         pos = skb_peek_tail(&ulpq->lobby);
793         if (!pos) {
794                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
795                 return;
796         }
797 
798         sid = event->stream;
799         ssn = event->ssn;
800 
801         cevent = (struct sctp_ulpevent *) pos->cb;
802         csid = cevent->stream;
803         cssn = cevent->ssn;
804         if (sid > csid) {
805                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
806                 return;
807         }
808 
809         if ((sid == csid) && SSN_lt(cssn, ssn)) {
810                 __skb_queue_tail(&ulpq->lobby, sctp_event2skb(event));
811                 return;
812         }
813 
814         /* Find the right place in this list.  We store them by
815          * stream ID and then by SSN.
816          */
817         skb_queue_walk(&ulpq->lobby, pos) {
818                 cevent = (struct sctp_ulpevent *) pos->cb;
819                 csid = cevent->stream;
820                 cssn = cevent->ssn;
821 
822                 if (csid > sid)
823                         break;
824                 if (csid == sid && SSN_lt(ssn, cssn))
825                         break;
826         }
827 
828 
829         /* Insert before pos. */
830         __skb_queue_before(&ulpq->lobby, pos, sctp_event2skb(event));
831 }
832 
833 static struct sctp_ulpevent *sctp_ulpq_order(struct sctp_ulpq *ulpq,
834                                              struct sctp_ulpevent *event)
835 {
836         __u16 sid, ssn;
837         struct sctp_stream *in;
838 
839         /* Check if this message needs ordering.  */
840         if (SCTP_DATA_UNORDERED & event->msg_flags)
841                 return event;
842 
843         /* Note: The stream ID must be verified before this routine.  */
844         sid = event->stream;
845         ssn = event->ssn;
846         in  = &ulpq->asoc->ssnmap->in;
847 
848         /* Is this the expected SSN for this stream ID?  */
849         if (ssn != sctp_ssn_peek(in, sid)) {
850                 /* We've received something out of order, so find where it
851                  * needs to be placed.  We order by stream and then by SSN.
852                  */
853                 sctp_ulpq_store_ordered(ulpq, event);
854                 return NULL;
855         }
856 
857         /* Mark that the next chunk has been found.  */
858         sctp_ssn_next(in, sid);
859 
860         /* Go find any other chunks that were waiting for
861          * ordering.
862          */
863         sctp_ulpq_retrieve_ordered(ulpq, event);
864 
865         return event;
866 }
867 
868 /* Helper function to gather skbs that have possibly become
869  * ordered by forward tsn skipping their dependencies.
870  */
871 static void sctp_ulpq_reap_ordered(struct sctp_ulpq *ulpq, __u16 sid)
872 {
873         struct sk_buff *pos, *tmp;
874         struct sctp_ulpevent *cevent;
875         struct sctp_ulpevent *event;
876         struct sctp_stream *in;
877         struct sk_buff_head temp;
878         struct sk_buff_head *lobby = &ulpq->lobby;
879         __u16 csid, cssn;
880 
881         in  = &ulpq->asoc->ssnmap->in;
882 
883         /* We are holding the chunks by stream, by SSN.  */
884         skb_queue_head_init(&temp);
885         event = NULL;
886         sctp_skb_for_each(pos, lobby, tmp) {
887                 cevent = (struct sctp_ulpevent *) pos->cb;
888                 csid = cevent->stream;
889                 cssn = cevent->ssn;
890 
891                 /* Have we gone too far?  */
892                 if (csid > sid)
893                         break;
894 
895                 /* Have we not gone far enough?  */
896                 if (csid < sid)
897                         continue;
898 
899                 /* see if this ssn has been marked by skipping */
900                 if (!SSN_lt(cssn, sctp_ssn_peek(in, csid)))
901                         break;
902 
903                 __skb_unlink(pos, lobby);
904                 if (!event)
905                         /* Create a temporary list to collect chunks on.  */
906                         event = sctp_skb2event(pos);
907 
908                 /* Attach all gathered skbs to the event.  */
909                 __skb_queue_tail(&temp, pos);
910         }
911 
912         /* If we didn't reap any data, see if the next expected SSN
913          * is next on the queue and if so, use that.
914          */
915         if (event == NULL && pos != (struct sk_buff *)lobby) {
916                 cevent = (struct sctp_ulpevent *) pos->cb;
917                 csid = cevent->stream;
918                 cssn = cevent->ssn;
919 
920                 if (csid == sid && cssn == sctp_ssn_peek(in, csid)) {
921                         sctp_ssn_next(in, csid);
922                         __skb_unlink(pos, lobby);
923                         __skb_queue_tail(&temp, pos);
924                         event = sctp_skb2event(pos);
925                 }
926         }
927 
928         /* Send event to the ULP.  'event' is the sctp_ulpevent for
929          * very first SKB on the 'temp' list.
930          */
931         if (event) {
932                 /* see if we have more ordered that we can deliver */
933                 sctp_ulpq_retrieve_ordered(ulpq, event);
934                 sctp_ulpq_tail_event(ulpq, event);
935         }
936 }
937 
938 /* Skip over an SSN. This is used during the processing of
939  * Forwared TSN chunk to skip over the abandoned ordered data
940  */
941 void sctp_ulpq_skip(struct sctp_ulpq *ulpq, __u16 sid, __u16 ssn)
942 {
943         struct sctp_stream *in;
944 
945         /* Note: The stream ID must be verified before this routine.  */
946         in  = &ulpq->asoc->ssnmap->in;
947 
948         /* Is this an old SSN?  If so ignore. */
949         if (SSN_lt(ssn, sctp_ssn_peek(in, sid)))
950                 return;
951 
952         /* Mark that we are no longer expecting this SSN or lower. */
953         sctp_ssn_skip(in, sid, ssn);
954 
955         /* Go find any other chunks that were waiting for
956          * ordering and deliver them if needed.
957          */
958         sctp_ulpq_reap_ordered(ulpq, sid);
959 }
960 
961 static __u16 sctp_ulpq_renege_list(struct sctp_ulpq *ulpq,
962                 struct sk_buff_head *list, __u16 needed)
963 {
964         __u16 freed = 0;
965         __u32 tsn;
966         struct sk_buff *skb;
967         struct sctp_ulpevent *event;
968         struct sctp_tsnmap *tsnmap;
969 
970         tsnmap = &ulpq->asoc->peer.tsn_map;
971 
972         while ((skb = __skb_dequeue_tail(list)) != NULL) {
973                 freed += skb_headlen(skb);
974                 event = sctp_skb2event(skb);
975                 tsn = event->tsn;
976 
977                 sctp_ulpevent_free(event);
978                 sctp_tsnmap_renege(tsnmap, tsn);
979                 if (freed >= needed)
980                         return freed;
981         }
982 
983         return freed;
984 }
985 
986 /* Renege 'needed' bytes from the ordering queue. */
987 static __u16 sctp_ulpq_renege_order(struct sctp_ulpq *ulpq, __u16 needed)
988 {
989         return sctp_ulpq_renege_list(ulpq, &ulpq->lobby, needed);
990 }
991 
992 /* Renege 'needed' bytes from the reassembly queue. */
993 static __u16 sctp_ulpq_renege_frags(struct sctp_ulpq *ulpq, __u16 needed)
994 {
995         return sctp_ulpq_renege_list(ulpq, &ulpq->reasm, needed);
996 }
997 
998 /* Partial deliver the first message as there is pressure on rwnd. */
999 void sctp_ulpq_partial_delivery(struct sctp_ulpq *ulpq,
1000                                 struct sctp_chunk *chunk,
1001                                 gfp_t gfp)
1002 {
1003         struct sctp_ulpevent *event;
1004         struct sctp_association *asoc;
1005         struct sctp_sock *sp;
1006 
1007         asoc = ulpq->asoc;
1008         sp = sctp_sk(asoc->base.sk);
1009 
1010         /* If the association is already in Partial Delivery mode
1011          * we have noting to do.
1012          */
1013         if (ulpq->pd_mode)
1014                 return;
1015 
1016         /* If the user enabled fragment interleave socket option,
1017          * multiple associations can enter partial delivery.
1018          * Otherwise, we can only enter partial delivery if the
1019          * socket is not in partial deliver mode.
1020          */
1021         if (sp->frag_interleave || atomic_read(&sp->pd_mode) == 0) {
1022                 /* Is partial delivery possible?  */
1023                 event = sctp_ulpq_retrieve_first(ulpq);
1024                 /* Send event to the ULP.   */
1025                 if (event) {
1026                         sctp_ulpq_tail_event(ulpq, event);
1027                         sctp_ulpq_set_pd(ulpq);
1028                         return;
1029                 }
1030         }
1031 }
1032 
1033 /* Renege some packets to make room for an incoming chunk.  */
1034 void sctp_ulpq_renege(struct sctp_ulpq *ulpq, struct sctp_chunk *chunk,
1035                       gfp_t gfp)
1036 {
1037         struct sctp_association *asoc;
1038         __u16 needed, freed;
1039 
1040         asoc = ulpq->asoc;
1041 
1042         if (chunk) {
1043                 needed = ntohs(chunk->chunk_hdr->length);
1044                 needed -= sizeof(sctp_data_chunk_t);
1045         } else
1046                 needed = SCTP_DEFAULT_MAXWINDOW;
1047 
1048         freed = 0;
1049 
1050         if (skb_queue_empty(&asoc->base.sk->sk_receive_queue)) {
1051                 freed = sctp_ulpq_renege_order(ulpq, needed);
1052                 if (freed < needed) {
1053                         freed += sctp_ulpq_renege_frags(ulpq, needed - freed);
1054                 }
1055         }
1056         /* If able to free enough room, accept this chunk. */
1057         if (chunk && (freed >= needed)) {
1058                 __u32 tsn;
1059                 tsn = ntohl(chunk->subh.data_hdr->tsn);
1060                 sctp_tsnmap_mark(&asoc->peer.tsn_map, tsn, chunk->transport);
1061                 sctp_ulpq_tail_data(ulpq, chunk, gfp);
1062 
1063                 sctp_ulpq_partial_delivery(ulpq, chunk, gfp);
1064         }
1065 
1066         sk_mem_reclaim(asoc->base.sk);
1067 }
1068 
1069 
1070 
1071 /* Notify the application if an association is aborted and in
1072  * partial delivery mode.  Send up any pending received messages.
1073  */
1074 void sctp_ulpq_abort_pd(struct sctp_ulpq *ulpq, gfp_t gfp)
1075 {
1076         struct sctp_ulpevent *ev = NULL;
1077         struct sock *sk;
1078 
1079         if (!ulpq->pd_mode)
1080                 return;
1081 
1082         sk = ulpq->asoc->base.sk;
1083         if (sctp_ulpevent_type_enabled(SCTP_PARTIAL_DELIVERY_EVENT,
1084                                        &sctp_sk(sk)->subscribe))
1085                 ev = sctp_ulpevent_make_pdapi(ulpq->asoc,
1086                                               SCTP_PARTIAL_DELIVERY_ABORTED,
1087                                               gfp);
1088         if (ev)
1089                 __skb_queue_tail(&sk->sk_receive_queue, sctp_event2skb(ev));
1090 
1091         /* If there is data waiting, send it up the socket now. */
1092         if (sctp_ulpq_clear_pd(ulpq) || ev)
1093                 sk->sk_data_ready(sk, 0);
1094 }
1095 

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