1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* SCTP kernel implementation
3  * (C) Copyright IBM Corp. 2001, 2004
4  * Copyright (c) 1999-2000 Cisco, Inc.
5  * Copyright (c) 1999-2001 Motorola, Inc.
6  * Copyright (c) 2001-2003 Intel Corp.
7  *
8  * This file is part of the SCTP kernel implementation
9  *
10  * These functions implement the sctp_outq class.   The outqueue handles
11  * bundling and queueing of outgoing SCTP chunks.
12  *
13  * Please send any bug reports or fixes you make to the
14  * email address(es):
15  *    lksctp developers <linux-sctp@vger.kernel.org>
16  *
17  * Written or modified by:
18  *    La Monte H.P. Yarroll <piggy@acm.org>
19  *    Karl Knutson          <karl@athena.chicago.il.us>
20  *    Perry Melange         <pmelange@null.cc.uic.edu>
21  *    Xingang Guo           <xingang.guo@intel.com>
22  *    Hui Huang 	    <hui.huang@nokia.com>
23  *    Sridhar Samudrala     <sri@us.ibm.com>
24  *    Jon Grimm             <jgrimm@us.ibm.com>
25  */
26 
27 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28 
29 #include <linux/types.h>
30 #include <linux/list.h>   /* For struct list_head */
31 #include <linux/socket.h>
32 #include <linux/ip.h>
33 #include <linux/slab.h>
34 #include <net/sock.h>	  /* For skb_set_owner_w */
35 
36 #include <net/sctp/sctp.h>
37 #include <net/sctp/sm.h>
38 #include <net/sctp/stream_sched.h>
39 #include <trace/events/sctp.h>
40 
41 /* Declare internal functions here.  */
42 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn);
43 static void sctp_check_transmitted(struct sctp_outq *q,
44 				   struct list_head *transmitted_queue,
45 				   struct sctp_transport *transport,
46 				   union sctp_addr *saddr,
47 				   struct sctp_sackhdr *sack,
48 				   __u32 *highest_new_tsn);
49 
50 static void sctp_mark_missing(struct sctp_outq *q,
51 			      struct list_head *transmitted_queue,
52 			      struct sctp_transport *transport,
53 			      __u32 highest_new_tsn,
54 			      int count_of_newacks);
55 
56 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp);
57 
58 /* Add data to the front of the queue. */
sctp_outq_head_data(struct sctp_outq * q,struct sctp_chunk * ch)59 static inline void sctp_outq_head_data(struct sctp_outq *q,
60 				       struct sctp_chunk *ch)
61 {
62 	struct sctp_stream_out_ext *oute;
63 	__u16 stream;
64 
65 	list_add(&ch->list, &q->out_chunk_list);
66 	q->out_qlen += ch->skb->len;
67 
68 	stream = sctp_chunk_stream_no(ch);
69 	oute = SCTP_SO(&q->asoc->stream, stream)->ext;
70 	list_add(&ch->stream_list, &oute->outq);
71 }
72 
73 /* Take data from the front of the queue. */
sctp_outq_dequeue_data(struct sctp_outq * q)74 static inline struct sctp_chunk *sctp_outq_dequeue_data(struct sctp_outq *q)
75 {
76 	return q->sched->dequeue(q);
77 }
78 
79 /* Add data chunk to the end of the queue. */
sctp_outq_tail_data(struct sctp_outq * q,struct sctp_chunk * ch)80 static inline void sctp_outq_tail_data(struct sctp_outq *q,
81 				       struct sctp_chunk *ch)
82 {
83 	struct sctp_stream_out_ext *oute;
84 	__u16 stream;
85 
86 	list_add_tail(&ch->list, &q->out_chunk_list);
87 	q->out_qlen += ch->skb->len;
88 
89 	stream = sctp_chunk_stream_no(ch);
90 	oute = SCTP_SO(&q->asoc->stream, stream)->ext;
91 	list_add_tail(&ch->stream_list, &oute->outq);
92 }
93 
94 /*
95  * SFR-CACC algorithm:
96  * D) If count_of_newacks is greater than or equal to 2
97  * and t was not sent to the current primary then the
98  * sender MUST NOT increment missing report count for t.
99  */
sctp_cacc_skip_3_1_d(struct sctp_transport * primary,struct sctp_transport * transport,int count_of_newacks)100 static inline int sctp_cacc_skip_3_1_d(struct sctp_transport *primary,
101 				       struct sctp_transport *transport,
102 				       int count_of_newacks)
103 {
104 	if (count_of_newacks >= 2 && transport != primary)
105 		return 1;
106 	return 0;
107 }
108 
109 /*
110  * SFR-CACC algorithm:
111  * F) If count_of_newacks is less than 2, let d be the
112  * destination to which t was sent. If cacc_saw_newack
113  * is 0 for destination d, then the sender MUST NOT
114  * increment missing report count for t.
115  */
sctp_cacc_skip_3_1_f(struct sctp_transport * transport,int count_of_newacks)116 static inline int sctp_cacc_skip_3_1_f(struct sctp_transport *transport,
117 				       int count_of_newacks)
118 {
119 	if (count_of_newacks < 2 &&
120 			(transport && !transport->cacc.cacc_saw_newack))
121 		return 1;
122 	return 0;
123 }
124 
125 /*
126  * SFR-CACC algorithm:
127  * 3.1) If CYCLING_CHANGEOVER is 0, the sender SHOULD
128  * execute steps C, D, F.
129  *
130  * C has been implemented in sctp_outq_sack
131  */
sctp_cacc_skip_3_1(struct sctp_transport * primary,struct sctp_transport * transport,int count_of_newacks)132 static inline int sctp_cacc_skip_3_1(struct sctp_transport *primary,
133 				     struct sctp_transport *transport,
134 				     int count_of_newacks)
135 {
136 	if (!primary->cacc.cycling_changeover) {
137 		if (sctp_cacc_skip_3_1_d(primary, transport, count_of_newacks))
138 			return 1;
139 		if (sctp_cacc_skip_3_1_f(transport, count_of_newacks))
140 			return 1;
141 		return 0;
142 	}
143 	return 0;
144 }
145 
146 /*
147  * SFR-CACC algorithm:
148  * 3.2) Else if CYCLING_CHANGEOVER is 1, and t is less
149  * than next_tsn_at_change of the current primary, then
150  * the sender MUST NOT increment missing report count
151  * for t.
152  */
sctp_cacc_skip_3_2(struct sctp_transport * primary,__u32 tsn)153 static inline int sctp_cacc_skip_3_2(struct sctp_transport *primary, __u32 tsn)
154 {
155 	if (primary->cacc.cycling_changeover &&
156 	    TSN_lt(tsn, primary->cacc.next_tsn_at_change))
157 		return 1;
158 	return 0;
159 }
160 
161 /*
162  * SFR-CACC algorithm:
163  * 3) If the missing report count for TSN t is to be
164  * incremented according to [RFC2960] and
165  * [SCTP_STEWART-2002], and CHANGEOVER_ACTIVE is set,
166  * then the sender MUST further execute steps 3.1 and
167  * 3.2 to determine if the missing report count for
168  * TSN t SHOULD NOT be incremented.
169  *
170  * 3.3) If 3.1 and 3.2 do not dictate that the missing
171  * report count for t should not be incremented, then
172  * the sender SHOULD increment missing report count for
173  * t (according to [RFC2960] and [SCTP_STEWART_2002]).
174  */
sctp_cacc_skip(struct sctp_transport * primary,struct sctp_transport * transport,int count_of_newacks,__u32 tsn)175 static inline int sctp_cacc_skip(struct sctp_transport *primary,
176 				 struct sctp_transport *transport,
177 				 int count_of_newacks,
178 				 __u32 tsn)
179 {
180 	if (primary->cacc.changeover_active &&
181 	    (sctp_cacc_skip_3_1(primary, transport, count_of_newacks) ||
182 	     sctp_cacc_skip_3_2(primary, tsn)))
183 		return 1;
184 	return 0;
185 }
186 
187 /* Initialize an existing sctp_outq.  This does the boring stuff.
188  * You still need to define handlers if you really want to DO
189  * something with this structure...
190  */
sctp_outq_init(struct sctp_association * asoc,struct sctp_outq * q)191 void sctp_outq_init(struct sctp_association *asoc, struct sctp_outq *q)
192 {
193 	memset(q, 0, sizeof(struct sctp_outq));
194 
195 	q->asoc = asoc;
196 	INIT_LIST_HEAD(&q->out_chunk_list);
197 	INIT_LIST_HEAD(&q->control_chunk_list);
198 	INIT_LIST_HEAD(&q->retransmit);
199 	INIT_LIST_HEAD(&q->sacked);
200 	INIT_LIST_HEAD(&q->abandoned);
201 	sctp_sched_set_sched(asoc, sctp_sk(asoc->base.sk)->default_ss);
202 }
203 
204 /* Free the outqueue structure and any related pending chunks.
205  */
__sctp_outq_teardown(struct sctp_outq * q)206 static void __sctp_outq_teardown(struct sctp_outq *q)
207 {
208 	struct sctp_transport *transport;
209 	struct list_head *lchunk, *temp;
210 	struct sctp_chunk *chunk, *tmp;
211 
212 	/* Throw away unacknowledged chunks. */
213 	list_for_each_entry(transport, &q->asoc->peer.transport_addr_list,
214 			transports) {
215 		while ((lchunk = sctp_list_dequeue(&transport->transmitted)) != NULL) {
216 			chunk = list_entry(lchunk, struct sctp_chunk,
217 					   transmitted_list);
218 			/* Mark as part of a failed message. */
219 			sctp_chunk_fail(chunk, q->error);
220 			sctp_chunk_free(chunk);
221 		}
222 	}
223 
224 	/* Throw away chunks that have been gap ACKed.  */
225 	list_for_each_safe(lchunk, temp, &q->sacked) {
226 		list_del_init(lchunk);
227 		chunk = list_entry(lchunk, struct sctp_chunk,
228 				   transmitted_list);
229 		sctp_chunk_fail(chunk, q->error);
230 		sctp_chunk_free(chunk);
231 	}
232 
233 	/* Throw away any chunks in the retransmit queue. */
234 	list_for_each_safe(lchunk, temp, &q->retransmit) {
235 		list_del_init(lchunk);
236 		chunk = list_entry(lchunk, struct sctp_chunk,
237 				   transmitted_list);
238 		sctp_chunk_fail(chunk, q->error);
239 		sctp_chunk_free(chunk);
240 	}
241 
242 	/* Throw away any chunks that are in the abandoned queue. */
243 	list_for_each_safe(lchunk, temp, &q->abandoned) {
244 		list_del_init(lchunk);
245 		chunk = list_entry(lchunk, struct sctp_chunk,
246 				   transmitted_list);
247 		sctp_chunk_fail(chunk, q->error);
248 		sctp_chunk_free(chunk);
249 	}
250 
251 	/* Throw away any leftover data chunks. */
252 	while ((chunk = sctp_outq_dequeue_data(q)) != NULL) {
253 		sctp_sched_dequeue_done(q, chunk);
254 
255 		/* Mark as send failure. */
256 		sctp_chunk_fail(chunk, q->error);
257 		sctp_chunk_free(chunk);
258 	}
259 
260 	/* Throw away any leftover control chunks. */
261 	list_for_each_entry_safe(chunk, tmp, &q->control_chunk_list, list) {
262 		list_del_init(&chunk->list);
263 		sctp_chunk_free(chunk);
264 	}
265 }
266 
sctp_outq_teardown(struct sctp_outq * q)267 void sctp_outq_teardown(struct sctp_outq *q)
268 {
269 	__sctp_outq_teardown(q);
270 	sctp_outq_init(q->asoc, q);
271 }
272 
273 /* Free the outqueue structure and any related pending chunks.  */
sctp_outq_free(struct sctp_outq * q)274 void sctp_outq_free(struct sctp_outq *q)
275 {
276 	/* Throw away leftover chunks. */
277 	__sctp_outq_teardown(q);
278 }
279 
280 /* Put a new chunk in an sctp_outq.  */
sctp_outq_tail(struct sctp_outq * q,struct sctp_chunk * chunk,gfp_t gfp)281 void sctp_outq_tail(struct sctp_outq *q, struct sctp_chunk *chunk, gfp_t gfp)
282 {
283 	struct net *net = q->asoc->base.net;
284 
285 	pr_debug("%s: outq:%p, chunk:%p[%s]\n", __func__, q, chunk,
286 		 chunk && chunk->chunk_hdr ?
287 		 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
288 		 "illegal chunk");
289 
290 	/* If it is data, queue it up, otherwise, send it
291 	 * immediately.
292 	 */
293 	if (sctp_chunk_is_data(chunk)) {
294 		pr_debug("%s: outqueueing: outq:%p, chunk:%p[%s])\n",
295 			 __func__, q, chunk, chunk && chunk->chunk_hdr ?
296 			 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
297 			 "illegal chunk");
298 
299 		sctp_outq_tail_data(q, chunk);
300 		if (chunk->asoc->peer.prsctp_capable &&
301 		    SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
302 			chunk->asoc->sent_cnt_removable++;
303 		if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
304 			SCTP_INC_STATS(net, SCTP_MIB_OUTUNORDERCHUNKS);
305 		else
306 			SCTP_INC_STATS(net, SCTP_MIB_OUTORDERCHUNKS);
307 	} else {
308 		list_add_tail(&chunk->list, &q->control_chunk_list);
309 		SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
310 	}
311 
312 	if (!q->cork)
313 		sctp_outq_flush(q, 0, gfp);
314 }
315 
316 /* Insert a chunk into the sorted list based on the TSNs.  The retransmit list
317  * and the abandoned list are in ascending order.
318  */
sctp_insert_list(struct list_head * head,struct list_head * new)319 static void sctp_insert_list(struct list_head *head, struct list_head *new)
320 {
321 	struct list_head *pos;
322 	struct sctp_chunk *nchunk, *lchunk;
323 	__u32 ntsn, ltsn;
324 	int done = 0;
325 
326 	nchunk = list_entry(new, struct sctp_chunk, transmitted_list);
327 	ntsn = ntohl(nchunk->subh.data_hdr->tsn);
328 
329 	list_for_each(pos, head) {
330 		lchunk = list_entry(pos, struct sctp_chunk, transmitted_list);
331 		ltsn = ntohl(lchunk->subh.data_hdr->tsn);
332 		if (TSN_lt(ntsn, ltsn)) {
333 			list_add(new, pos->prev);
334 			done = 1;
335 			break;
336 		}
337 	}
338 	if (!done)
339 		list_add_tail(new, head);
340 }
341 
sctp_prsctp_prune_sent(struct sctp_association * asoc,struct sctp_sndrcvinfo * sinfo,struct list_head * queue,int msg_len)342 static int sctp_prsctp_prune_sent(struct sctp_association *asoc,
343 				  struct sctp_sndrcvinfo *sinfo,
344 				  struct list_head *queue, int msg_len)
345 {
346 	struct sctp_chunk *chk, *temp;
347 
348 	list_for_each_entry_safe(chk, temp, queue, transmitted_list) {
349 		struct sctp_stream_out *streamout;
350 
351 		if (!chk->msg->abandoned &&
352 		    (!SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
353 		     chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
354 			continue;
355 
356 		chk->msg->abandoned = 1;
357 		list_del_init(&chk->transmitted_list);
358 		sctp_insert_list(&asoc->outqueue.abandoned,
359 				 &chk->transmitted_list);
360 
361 		streamout = SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
362 		asoc->sent_cnt_removable--;
363 		asoc->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
364 		streamout->ext->abandoned_sent[SCTP_PR_INDEX(PRIO)]++;
365 
366 		if (queue != &asoc->outqueue.retransmit &&
367 		    !chk->tsn_gap_acked) {
368 			if (chk->transport)
369 				chk->transport->flight_size -=
370 						sctp_data_size(chk);
371 			asoc->outqueue.outstanding_bytes -= sctp_data_size(chk);
372 		}
373 
374 		msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
375 		if (msg_len <= 0)
376 			break;
377 	}
378 
379 	return msg_len;
380 }
381 
sctp_prsctp_prune_unsent(struct sctp_association * asoc,struct sctp_sndrcvinfo * sinfo,int msg_len)382 static int sctp_prsctp_prune_unsent(struct sctp_association *asoc,
383 				    struct sctp_sndrcvinfo *sinfo, int msg_len)
384 {
385 	struct sctp_outq *q = &asoc->outqueue;
386 	struct sctp_chunk *chk, *temp;
387 	struct sctp_stream_out *sout;
388 
389 	q->sched->unsched_all(&asoc->stream);
390 
391 	list_for_each_entry_safe(chk, temp, &q->out_chunk_list, list) {
392 		if (!chk->msg->abandoned &&
393 		    (!(chk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG) ||
394 		     !SCTP_PR_PRIO_ENABLED(chk->sinfo.sinfo_flags) ||
395 		     chk->sinfo.sinfo_timetolive <= sinfo->sinfo_timetolive))
396 			continue;
397 
398 		chk->msg->abandoned = 1;
399 		sctp_sched_dequeue_common(q, chk);
400 		asoc->sent_cnt_removable--;
401 		asoc->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
402 
403 		sout = SCTP_SO(&asoc->stream, chk->sinfo.sinfo_stream);
404 		sout->ext->abandoned_unsent[SCTP_PR_INDEX(PRIO)]++;
405 
406 		/* clear out_curr if all frag chunks are pruned */
407 		if (asoc->stream.out_curr == sout &&
408 		    list_is_last(&chk->frag_list, &chk->msg->chunks))
409 			asoc->stream.out_curr = NULL;
410 
411 		msg_len -= chk->skb->truesize + sizeof(struct sctp_chunk);
412 		sctp_chunk_free(chk);
413 		if (msg_len <= 0)
414 			break;
415 	}
416 
417 	q->sched->sched_all(&asoc->stream);
418 
419 	return msg_len;
420 }
421 
422 /* Abandon the chunks according their priorities */
sctp_prsctp_prune(struct sctp_association * asoc,struct sctp_sndrcvinfo * sinfo,int msg_len)423 void sctp_prsctp_prune(struct sctp_association *asoc,
424 		       struct sctp_sndrcvinfo *sinfo, int msg_len)
425 {
426 	struct sctp_transport *transport;
427 
428 	if (!asoc->peer.prsctp_capable || !asoc->sent_cnt_removable)
429 		return;
430 
431 	msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
432 					 &asoc->outqueue.retransmit,
433 					 msg_len);
434 	if (msg_len <= 0)
435 		return;
436 
437 	list_for_each_entry(transport, &asoc->peer.transport_addr_list,
438 			    transports) {
439 		msg_len = sctp_prsctp_prune_sent(asoc, sinfo,
440 						 &transport->transmitted,
441 						 msg_len);
442 		if (msg_len <= 0)
443 			return;
444 	}
445 
446 	sctp_prsctp_prune_unsent(asoc, sinfo, msg_len);
447 }
448 
449 /* Mark all the eligible packets on a transport for retransmission.  */
sctp_retransmit_mark(struct sctp_outq * q,struct sctp_transport * transport,__u8 reason)450 void sctp_retransmit_mark(struct sctp_outq *q,
451 			  struct sctp_transport *transport,
452 			  __u8 reason)
453 {
454 	struct list_head *lchunk, *ltemp;
455 	struct sctp_chunk *chunk;
456 
457 	/* Walk through the specified transmitted queue.  */
458 	list_for_each_safe(lchunk, ltemp, &transport->transmitted) {
459 		chunk = list_entry(lchunk, struct sctp_chunk,
460 				   transmitted_list);
461 
462 		/* If the chunk is abandoned, move it to abandoned list. */
463 		if (sctp_chunk_abandoned(chunk)) {
464 			list_del_init(lchunk);
465 			sctp_insert_list(&q->abandoned, lchunk);
466 
467 			/* If this chunk has not been previousely acked,
468 			 * stop considering it 'outstanding'.  Our peer
469 			 * will most likely never see it since it will
470 			 * not be retransmitted
471 			 */
472 			if (!chunk->tsn_gap_acked) {
473 				if (chunk->transport)
474 					chunk->transport->flight_size -=
475 							sctp_data_size(chunk);
476 				q->outstanding_bytes -= sctp_data_size(chunk);
477 				q->asoc->peer.rwnd += sctp_data_size(chunk);
478 			}
479 			continue;
480 		}
481 
482 		/* If we are doing  retransmission due to a timeout or pmtu
483 		 * discovery, only the  chunks that are not yet acked should
484 		 * be added to the retransmit queue.
485 		 */
486 		if ((reason == SCTP_RTXR_FAST_RTX  &&
487 			    (chunk->fast_retransmit == SCTP_NEED_FRTX)) ||
488 		    (reason != SCTP_RTXR_FAST_RTX  && !chunk->tsn_gap_acked)) {
489 			/* RFC 2960 6.2.1 Processing a Received SACK
490 			 *
491 			 * C) Any time a DATA chunk is marked for
492 			 * retransmission (via either T3-rtx timer expiration
493 			 * (Section 6.3.3) or via fast retransmit
494 			 * (Section 7.2.4)), add the data size of those
495 			 * chunks to the rwnd.
496 			 */
497 			q->asoc->peer.rwnd += sctp_data_size(chunk);
498 			q->outstanding_bytes -= sctp_data_size(chunk);
499 			if (chunk->transport)
500 				transport->flight_size -= sctp_data_size(chunk);
501 
502 			/* sctpimpguide-05 Section 2.8.2
503 			 * M5) If a T3-rtx timer expires, the
504 			 * 'TSN.Missing.Report' of all affected TSNs is set
505 			 * to 0.
506 			 */
507 			chunk->tsn_missing_report = 0;
508 
509 			/* If a chunk that is being used for RTT measurement
510 			 * has to be retransmitted, we cannot use this chunk
511 			 * anymore for RTT measurements. Reset rto_pending so
512 			 * that a new RTT measurement is started when a new
513 			 * data chunk is sent.
514 			 */
515 			if (chunk->rtt_in_progress) {
516 				chunk->rtt_in_progress = 0;
517 				transport->rto_pending = 0;
518 			}
519 
520 			/* Move the chunk to the retransmit queue. The chunks
521 			 * on the retransmit queue are always kept in order.
522 			 */
523 			list_del_init(lchunk);
524 			sctp_insert_list(&q->retransmit, lchunk);
525 		}
526 	}
527 
528 	pr_debug("%s: transport:%p, reason:%d, cwnd:%d, ssthresh:%d, "
529 		 "flight_size:%d, pba:%d\n", __func__, transport, reason,
530 		 transport->cwnd, transport->ssthresh, transport->flight_size,
531 		 transport->partial_bytes_acked);
532 }
533 
534 /* Mark all the eligible packets on a transport for retransmission and force
535  * one packet out.
536  */
sctp_retransmit(struct sctp_outq * q,struct sctp_transport * transport,enum sctp_retransmit_reason reason)537 void sctp_retransmit(struct sctp_outq *q, struct sctp_transport *transport,
538 		     enum sctp_retransmit_reason reason)
539 {
540 	struct net *net = q->asoc->base.net;
541 
542 	switch (reason) {
543 	case SCTP_RTXR_T3_RTX:
544 		SCTP_INC_STATS(net, SCTP_MIB_T3_RETRANSMITS);
545 		sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_T3_RTX);
546 		/* Update the retran path if the T3-rtx timer has expired for
547 		 * the current retran path.
548 		 */
549 		if (transport == transport->asoc->peer.retran_path)
550 			sctp_assoc_update_retran_path(transport->asoc);
551 		transport->asoc->rtx_data_chunks +=
552 			transport->asoc->unack_data;
553 		if (transport->pl.state == SCTP_PL_COMPLETE &&
554 		    transport->asoc->unack_data)
555 			sctp_transport_reset_probe_timer(transport);
556 		break;
557 	case SCTP_RTXR_FAST_RTX:
558 		SCTP_INC_STATS(net, SCTP_MIB_FAST_RETRANSMITS);
559 		sctp_transport_lower_cwnd(transport, SCTP_LOWER_CWND_FAST_RTX);
560 		q->fast_rtx = 1;
561 		break;
562 	case SCTP_RTXR_PMTUD:
563 		SCTP_INC_STATS(net, SCTP_MIB_PMTUD_RETRANSMITS);
564 		break;
565 	case SCTP_RTXR_T1_RTX:
566 		SCTP_INC_STATS(net, SCTP_MIB_T1_RETRANSMITS);
567 		transport->asoc->init_retries++;
568 		break;
569 	default:
570 		BUG();
571 	}
572 
573 	sctp_retransmit_mark(q, transport, reason);
574 
575 	/* PR-SCTP A5) Any time the T3-rtx timer expires, on any destination,
576 	 * the sender SHOULD try to advance the "Advanced.Peer.Ack.Point" by
577 	 * following the procedures outlined in C1 - C5.
578 	 */
579 	if (reason == SCTP_RTXR_T3_RTX)
580 		q->asoc->stream.si->generate_ftsn(q, q->asoc->ctsn_ack_point);
581 
582 	/* Flush the queues only on timeout, since fast_rtx is only
583 	 * triggered during sack processing and the queue
584 	 * will be flushed at the end.
585 	 */
586 	if (reason != SCTP_RTXR_FAST_RTX)
587 		sctp_outq_flush(q, /* rtx_timeout */ 1, GFP_ATOMIC);
588 }
589 
590 /*
591  * Transmit DATA chunks on the retransmit queue.  Upon return from
592  * __sctp_outq_flush_rtx() the packet 'pkt' may contain chunks which
593  * need to be transmitted by the caller.
594  * We assume that pkt->transport has already been set.
595  *
596  * The return value is a normal kernel error return value.
597  */
__sctp_outq_flush_rtx(struct sctp_outq * q,struct sctp_packet * pkt,int rtx_timeout,int * start_timer,gfp_t gfp)598 static int __sctp_outq_flush_rtx(struct sctp_outq *q, struct sctp_packet *pkt,
599 				 int rtx_timeout, int *start_timer, gfp_t gfp)
600 {
601 	struct sctp_transport *transport = pkt->transport;
602 	struct sctp_chunk *chunk, *chunk1;
603 	struct list_head *lqueue;
604 	enum sctp_xmit status;
605 	int error = 0;
606 	int timer = 0;
607 	int done = 0;
608 	int fast_rtx;
609 
610 	lqueue = &q->retransmit;
611 	fast_rtx = q->fast_rtx;
612 
613 	/* This loop handles time-out retransmissions, fast retransmissions,
614 	 * and retransmissions due to opening of whindow.
615 	 *
616 	 * RFC 2960 6.3.3 Handle T3-rtx Expiration
617 	 *
618 	 * E3) Determine how many of the earliest (i.e., lowest TSN)
619 	 * outstanding DATA chunks for the address for which the
620 	 * T3-rtx has expired will fit into a single packet, subject
621 	 * to the MTU constraint for the path corresponding to the
622 	 * destination transport address to which the retransmission
623 	 * is being sent (this may be different from the address for
624 	 * which the timer expires [see Section 6.4]). Call this value
625 	 * K. Bundle and retransmit those K DATA chunks in a single
626 	 * packet to the destination endpoint.
627 	 *
628 	 * [Just to be painfully clear, if we are retransmitting
629 	 * because a timeout just happened, we should send only ONE
630 	 * packet of retransmitted data.]
631 	 *
632 	 * For fast retransmissions we also send only ONE packet.  However,
633 	 * if we are just flushing the queue due to open window, we'll
634 	 * try to send as much as possible.
635 	 */
636 	list_for_each_entry_safe(chunk, chunk1, lqueue, transmitted_list) {
637 		/* If the chunk is abandoned, move it to abandoned list. */
638 		if (sctp_chunk_abandoned(chunk)) {
639 			list_del_init(&chunk->transmitted_list);
640 			sctp_insert_list(&q->abandoned,
641 					 &chunk->transmitted_list);
642 			continue;
643 		}
644 
645 		/* Make sure that Gap Acked TSNs are not retransmitted.  A
646 		 * simple approach is just to move such TSNs out of the
647 		 * way and into a 'transmitted' queue and skip to the
648 		 * next chunk.
649 		 */
650 		if (chunk->tsn_gap_acked) {
651 			list_move_tail(&chunk->transmitted_list,
652 				       &transport->transmitted);
653 			continue;
654 		}
655 
656 		/* If we are doing fast retransmit, ignore non-fast_rtransmit
657 		 * chunks
658 		 */
659 		if (fast_rtx && !chunk->fast_retransmit)
660 			continue;
661 
662 redo:
663 		/* Attempt to append this chunk to the packet. */
664 		status = sctp_packet_append_chunk(pkt, chunk);
665 
666 		switch (status) {
667 		case SCTP_XMIT_PMTU_FULL:
668 			if (!pkt->has_data && !pkt->has_cookie_echo) {
669 				/* If this packet did not contain DATA then
670 				 * retransmission did not happen, so do it
671 				 * again.  We'll ignore the error here since
672 				 * control chunks are already freed so there
673 				 * is nothing we can do.
674 				 */
675 				sctp_packet_transmit(pkt, gfp);
676 				goto redo;
677 			}
678 
679 			/* Send this packet.  */
680 			error = sctp_packet_transmit(pkt, gfp);
681 
682 			/* If we are retransmitting, we should only
683 			 * send a single packet.
684 			 * Otherwise, try appending this chunk again.
685 			 */
686 			if (rtx_timeout || fast_rtx)
687 				done = 1;
688 			else
689 				goto redo;
690 
691 			/* Bundle next chunk in the next round.  */
692 			break;
693 
694 		case SCTP_XMIT_RWND_FULL:
695 			/* Send this packet. */
696 			error = sctp_packet_transmit(pkt, gfp);
697 
698 			/* Stop sending DATA as there is no more room
699 			 * at the receiver.
700 			 */
701 			done = 1;
702 			break;
703 
704 		case SCTP_XMIT_DELAY:
705 			/* Send this packet. */
706 			error = sctp_packet_transmit(pkt, gfp);
707 
708 			/* Stop sending DATA because of nagle delay. */
709 			done = 1;
710 			break;
711 
712 		default:
713 			/* The append was successful, so add this chunk to
714 			 * the transmitted list.
715 			 */
716 			list_move_tail(&chunk->transmitted_list,
717 				       &transport->transmitted);
718 
719 			/* Mark the chunk as ineligible for fast retransmit
720 			 * after it is retransmitted.
721 			 */
722 			if (chunk->fast_retransmit == SCTP_NEED_FRTX)
723 				chunk->fast_retransmit = SCTP_DONT_FRTX;
724 
725 			q->asoc->stats.rtxchunks++;
726 			break;
727 		}
728 
729 		/* Set the timer if there were no errors */
730 		if (!error && !timer)
731 			timer = 1;
732 
733 		if (done)
734 			break;
735 	}
736 
737 	/* If we are here due to a retransmit timeout or a fast
738 	 * retransmit and if there are any chunks left in the retransmit
739 	 * queue that could not fit in the PMTU sized packet, they need
740 	 * to be marked as ineligible for a subsequent fast retransmit.
741 	 */
742 	if (rtx_timeout || fast_rtx) {
743 		list_for_each_entry(chunk1, lqueue, transmitted_list) {
744 			if (chunk1->fast_retransmit == SCTP_NEED_FRTX)
745 				chunk1->fast_retransmit = SCTP_DONT_FRTX;
746 		}
747 	}
748 
749 	*start_timer = timer;
750 
751 	/* Clear fast retransmit hint */
752 	if (fast_rtx)
753 		q->fast_rtx = 0;
754 
755 	return error;
756 }
757 
758 /* Cork the outqueue so queued chunks are really queued. */
sctp_outq_uncork(struct sctp_outq * q,gfp_t gfp)759 void sctp_outq_uncork(struct sctp_outq *q, gfp_t gfp)
760 {
761 	if (q->cork)
762 		q->cork = 0;
763 
764 	sctp_outq_flush(q, 0, gfp);
765 }
766 
sctp_packet_singleton(struct sctp_transport * transport,struct sctp_chunk * chunk,gfp_t gfp)767 static int sctp_packet_singleton(struct sctp_transport *transport,
768 				 struct sctp_chunk *chunk, gfp_t gfp)
769 {
770 	const struct sctp_association *asoc = transport->asoc;
771 	const __u16 sport = asoc->base.bind_addr.port;
772 	const __u16 dport = asoc->peer.port;
773 	const __u32 vtag = asoc->peer.i.init_tag;
774 	struct sctp_packet singleton;
775 
776 	sctp_packet_init(&singleton, transport, sport, dport);
777 	sctp_packet_config(&singleton, vtag, 0);
778 	if (sctp_packet_append_chunk(&singleton, chunk) != SCTP_XMIT_OK) {
779 		list_del_init(&chunk->list);
780 		sctp_chunk_free(chunk);
781 		return -ENOMEM;
782 	}
783 	return sctp_packet_transmit(&singleton, gfp);
784 }
785 
786 /* Struct to hold the context during sctp outq flush */
787 struct sctp_flush_ctx {
788 	struct sctp_outq *q;
789 	/* Current transport being used. It's NOT the same as curr active one */
790 	struct sctp_transport *transport;
791 	/* These transports have chunks to send. */
792 	struct list_head transport_list;
793 	struct sctp_association *asoc;
794 	/* Packet on the current transport above */
795 	struct sctp_packet *packet;
796 	gfp_t gfp;
797 };
798 
799 /* transport: current transport */
sctp_outq_select_transport(struct sctp_flush_ctx * ctx,struct sctp_chunk * chunk)800 static void sctp_outq_select_transport(struct sctp_flush_ctx *ctx,
801 				       struct sctp_chunk *chunk)
802 {
803 	struct sctp_transport *new_transport = chunk->transport;
804 
805 	if (!new_transport) {
806 		if (!sctp_chunk_is_data(chunk)) {
807 			/* If we have a prior transport pointer, see if
808 			 * the destination address of the chunk
809 			 * matches the destination address of the
810 			 * current transport.  If not a match, then
811 			 * try to look up the transport with a given
812 			 * destination address.  We do this because
813 			 * after processing ASCONFs, we may have new
814 			 * transports created.
815 			 */
816 			if (ctx->transport && sctp_cmp_addr_exact(&chunk->dest,
817 							&ctx->transport->ipaddr))
818 				new_transport = ctx->transport;
819 			else
820 				new_transport = sctp_assoc_lookup_paddr(ctx->asoc,
821 								  &chunk->dest);
822 		}
823 
824 		/* if we still don't have a new transport, then
825 		 * use the current active path.
826 		 */
827 		if (!new_transport)
828 			new_transport = ctx->asoc->peer.active_path;
829 	} else {
830 		__u8 type;
831 
832 		switch (new_transport->state) {
833 		case SCTP_INACTIVE:
834 		case SCTP_UNCONFIRMED:
835 		case SCTP_PF:
836 			/* If the chunk is Heartbeat or Heartbeat Ack,
837 			 * send it to chunk->transport, even if it's
838 			 * inactive.
839 			 *
840 			 * 3.3.6 Heartbeat Acknowledgement:
841 			 * ...
842 			 * A HEARTBEAT ACK is always sent to the source IP
843 			 * address of the IP datagram containing the
844 			 * HEARTBEAT chunk to which this ack is responding.
845 			 * ...
846 			 *
847 			 * ASCONF_ACKs also must be sent to the source.
848 			 */
849 			type = chunk->chunk_hdr->type;
850 			if (type != SCTP_CID_HEARTBEAT &&
851 			    type != SCTP_CID_HEARTBEAT_ACK &&
852 			    type != SCTP_CID_ASCONF_ACK)
853 				new_transport = ctx->asoc->peer.active_path;
854 			break;
855 		default:
856 			break;
857 		}
858 	}
859 
860 	/* Are we switching transports? Take care of transport locks. */
861 	if (new_transport != ctx->transport) {
862 		ctx->transport = new_transport;
863 		ctx->packet = &ctx->transport->packet;
864 
865 		if (list_empty(&ctx->transport->send_ready))
866 			list_add_tail(&ctx->transport->send_ready,
867 				      &ctx->transport_list);
868 
869 		sctp_packet_config(ctx->packet,
870 				   ctx->asoc->peer.i.init_tag,
871 				   ctx->asoc->peer.ecn_capable);
872 		/* We've switched transports, so apply the
873 		 * Burst limit to the new transport.
874 		 */
875 		sctp_transport_burst_limited(ctx->transport);
876 	}
877 }
878 
sctp_outq_flush_ctrl(struct sctp_flush_ctx * ctx)879 static void sctp_outq_flush_ctrl(struct sctp_flush_ctx *ctx)
880 {
881 	struct sctp_chunk *chunk, *tmp;
882 	enum sctp_xmit status;
883 	int one_packet, error;
884 
885 	list_for_each_entry_safe(chunk, tmp, &ctx->q->control_chunk_list, list) {
886 		one_packet = 0;
887 
888 		/* RFC 5061, 5.3
889 		 * F1) This means that until such time as the ASCONF
890 		 * containing the add is acknowledged, the sender MUST
891 		 * NOT use the new IP address as a source for ANY SCTP
892 		 * packet except on carrying an ASCONF Chunk.
893 		 */
894 		if (ctx->asoc->src_out_of_asoc_ok &&
895 		    chunk->chunk_hdr->type != SCTP_CID_ASCONF)
896 			continue;
897 
898 		list_del_init(&chunk->list);
899 
900 		/* Pick the right transport to use. Should always be true for
901 		 * the first chunk as we don't have a transport by then.
902 		 */
903 		sctp_outq_select_transport(ctx, chunk);
904 
905 		switch (chunk->chunk_hdr->type) {
906 		/* 6.10 Bundling
907 		 *   ...
908 		 *   An endpoint MUST NOT bundle INIT, INIT ACK or SHUTDOWN
909 		 *   COMPLETE with any other chunks.  [Send them immediately.]
910 		 */
911 		case SCTP_CID_INIT:
912 		case SCTP_CID_INIT_ACK:
913 		case SCTP_CID_SHUTDOWN_COMPLETE:
914 			error = sctp_packet_singleton(ctx->transport, chunk,
915 						      ctx->gfp);
916 			if (error < 0) {
917 				ctx->asoc->base.sk->sk_err = -error;
918 				return;
919 			}
920 			ctx->asoc->stats.octrlchunks++;
921 			break;
922 
923 		case SCTP_CID_ABORT:
924 			if (sctp_test_T_bit(chunk))
925 				ctx->packet->vtag = ctx->asoc->c.my_vtag;
926 			fallthrough;
927 
928 		/* The following chunks are "response" chunks, i.e.
929 		 * they are generated in response to something we
930 		 * received.  If we are sending these, then we can
931 		 * send only 1 packet containing these chunks.
932 		 */
933 		case SCTP_CID_HEARTBEAT_ACK:
934 		case SCTP_CID_SHUTDOWN_ACK:
935 		case SCTP_CID_COOKIE_ACK:
936 		case SCTP_CID_COOKIE_ECHO:
937 		case SCTP_CID_ERROR:
938 		case SCTP_CID_ECN_CWR:
939 		case SCTP_CID_ASCONF_ACK:
940 			one_packet = 1;
941 			fallthrough;
942 
943 		case SCTP_CID_HEARTBEAT:
944 			if (chunk->pmtu_probe) {
945 				error = sctp_packet_singleton(ctx->transport,
946 							      chunk, ctx->gfp);
947 				if (!error)
948 					ctx->asoc->stats.octrlchunks++;
949 				break;
950 			}
951 			fallthrough;
952 		case SCTP_CID_SACK:
953 		case SCTP_CID_SHUTDOWN:
954 		case SCTP_CID_ECN_ECNE:
955 		case SCTP_CID_ASCONF:
956 		case SCTP_CID_FWD_TSN:
957 		case SCTP_CID_I_FWD_TSN:
958 		case SCTP_CID_RECONF:
959 			status = sctp_packet_transmit_chunk(ctx->packet, chunk,
960 							    one_packet, ctx->gfp);
961 			if (status != SCTP_XMIT_OK) {
962 				/* put the chunk back */
963 				list_add(&chunk->list, &ctx->q->control_chunk_list);
964 				break;
965 			}
966 
967 			ctx->asoc->stats.octrlchunks++;
968 			/* PR-SCTP C5) If a FORWARD TSN is sent, the
969 			 * sender MUST assure that at least one T3-rtx
970 			 * timer is running.
971 			 */
972 			if (chunk->chunk_hdr->type == SCTP_CID_FWD_TSN ||
973 			    chunk->chunk_hdr->type == SCTP_CID_I_FWD_TSN) {
974 				sctp_transport_reset_t3_rtx(ctx->transport);
975 				ctx->transport->last_time_sent = jiffies;
976 			}
977 
978 			if (chunk == ctx->asoc->strreset_chunk)
979 				sctp_transport_reset_reconf_timer(ctx->transport);
980 
981 			break;
982 
983 		default:
984 			/* We built a chunk with an illegal type! */
985 			BUG();
986 		}
987 	}
988 }
989 
990 /* Returns false if new data shouldn't be sent */
sctp_outq_flush_rtx(struct sctp_flush_ctx * ctx,int rtx_timeout)991 static bool sctp_outq_flush_rtx(struct sctp_flush_ctx *ctx,
992 				int rtx_timeout)
993 {
994 	int error, start_timer = 0;
995 
996 	if (ctx->asoc->peer.retran_path->state == SCTP_UNCONFIRMED)
997 		return false;
998 
999 	if (ctx->transport != ctx->asoc->peer.retran_path) {
1000 		/* Switch transports & prepare the packet.  */
1001 		ctx->transport = ctx->asoc->peer.retran_path;
1002 		ctx->packet = &ctx->transport->packet;
1003 
1004 		if (list_empty(&ctx->transport->send_ready))
1005 			list_add_tail(&ctx->transport->send_ready,
1006 				      &ctx->transport_list);
1007 
1008 		sctp_packet_config(ctx->packet, ctx->asoc->peer.i.init_tag,
1009 				   ctx->asoc->peer.ecn_capable);
1010 	}
1011 
1012 	error = __sctp_outq_flush_rtx(ctx->q, ctx->packet, rtx_timeout,
1013 				      &start_timer, ctx->gfp);
1014 	if (error < 0)
1015 		ctx->asoc->base.sk->sk_err = -error;
1016 
1017 	if (start_timer) {
1018 		sctp_transport_reset_t3_rtx(ctx->transport);
1019 		ctx->transport->last_time_sent = jiffies;
1020 	}
1021 
1022 	/* This can happen on COOKIE-ECHO resend.  Only
1023 	 * one chunk can get bundled with a COOKIE-ECHO.
1024 	 */
1025 	if (ctx->packet->has_cookie_echo)
1026 		return false;
1027 
1028 	/* Don't send new data if there is still data
1029 	 * waiting to retransmit.
1030 	 */
1031 	if (!list_empty(&ctx->q->retransmit))
1032 		return false;
1033 
1034 	return true;
1035 }
1036 
sctp_outq_flush_data(struct sctp_flush_ctx * ctx,int rtx_timeout)1037 static void sctp_outq_flush_data(struct sctp_flush_ctx *ctx,
1038 				 int rtx_timeout)
1039 {
1040 	struct sctp_chunk *chunk;
1041 	enum sctp_xmit status;
1042 
1043 	/* Is it OK to send data chunks?  */
1044 	switch (ctx->asoc->state) {
1045 	case SCTP_STATE_COOKIE_ECHOED:
1046 		/* Only allow bundling when this packet has a COOKIE-ECHO
1047 		 * chunk.
1048 		 */
1049 		if (!ctx->packet || !ctx->packet->has_cookie_echo)
1050 			return;
1051 
1052 		fallthrough;
1053 	case SCTP_STATE_ESTABLISHED:
1054 	case SCTP_STATE_SHUTDOWN_PENDING:
1055 	case SCTP_STATE_SHUTDOWN_RECEIVED:
1056 		break;
1057 
1058 	default:
1059 		/* Do nothing. */
1060 		return;
1061 	}
1062 
1063 	/* RFC 2960 6.1  Transmission of DATA Chunks
1064 	 *
1065 	 * C) When the time comes for the sender to transmit,
1066 	 * before sending new DATA chunks, the sender MUST
1067 	 * first transmit any outstanding DATA chunks which
1068 	 * are marked for retransmission (limited by the
1069 	 * current cwnd).
1070 	 */
1071 	if (!list_empty(&ctx->q->retransmit) &&
1072 	    !sctp_outq_flush_rtx(ctx, rtx_timeout))
1073 		return;
1074 
1075 	/* Apply Max.Burst limitation to the current transport in
1076 	 * case it will be used for new data.  We are going to
1077 	 * rest it before we return, but we want to apply the limit
1078 	 * to the currently queued data.
1079 	 */
1080 	if (ctx->transport)
1081 		sctp_transport_burst_limited(ctx->transport);
1082 
1083 	/* Finally, transmit new packets.  */
1084 	while ((chunk = sctp_outq_dequeue_data(ctx->q)) != NULL) {
1085 		__u32 sid = ntohs(chunk->subh.data_hdr->stream);
1086 		__u8 stream_state = SCTP_SO(&ctx->asoc->stream, sid)->state;
1087 
1088 		/* Has this chunk expired? */
1089 		if (sctp_chunk_abandoned(chunk)) {
1090 			sctp_sched_dequeue_done(ctx->q, chunk);
1091 			sctp_chunk_fail(chunk, 0);
1092 			sctp_chunk_free(chunk);
1093 			continue;
1094 		}
1095 
1096 		if (stream_state == SCTP_STREAM_CLOSED) {
1097 			sctp_outq_head_data(ctx->q, chunk);
1098 			break;
1099 		}
1100 
1101 		sctp_outq_select_transport(ctx, chunk);
1102 
1103 		pr_debug("%s: outq:%p, chunk:%p[%s], tx-tsn:0x%x skb->head:%p skb->users:%d\n",
1104 			 __func__, ctx->q, chunk, chunk && chunk->chunk_hdr ?
1105 			 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)) :
1106 			 "illegal chunk", ntohl(chunk->subh.data_hdr->tsn),
1107 			 chunk->skb ? chunk->skb->head : NULL, chunk->skb ?
1108 			 refcount_read(&chunk->skb->users) : -1);
1109 
1110 		/* Add the chunk to the packet.  */
1111 		status = sctp_packet_transmit_chunk(ctx->packet, chunk, 0,
1112 						    ctx->gfp);
1113 		if (status != SCTP_XMIT_OK) {
1114 			/* We could not append this chunk, so put
1115 			 * the chunk back on the output queue.
1116 			 */
1117 			pr_debug("%s: could not transmit tsn:0x%x, status:%d\n",
1118 				 __func__, ntohl(chunk->subh.data_hdr->tsn),
1119 				 status);
1120 
1121 			sctp_outq_head_data(ctx->q, chunk);
1122 			break;
1123 		}
1124 
1125 		/* The sender is in the SHUTDOWN-PENDING state,
1126 		 * The sender MAY set the I-bit in the DATA
1127 		 * chunk header.
1128 		 */
1129 		if (ctx->asoc->state == SCTP_STATE_SHUTDOWN_PENDING)
1130 			chunk->chunk_hdr->flags |= SCTP_DATA_SACK_IMM;
1131 		if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED)
1132 			ctx->asoc->stats.ouodchunks++;
1133 		else
1134 			ctx->asoc->stats.oodchunks++;
1135 
1136 		/* Only now it's safe to consider this
1137 		 * chunk as sent, sched-wise.
1138 		 */
1139 		sctp_sched_dequeue_done(ctx->q, chunk);
1140 
1141 		list_add_tail(&chunk->transmitted_list,
1142 			      &ctx->transport->transmitted);
1143 
1144 		sctp_transport_reset_t3_rtx(ctx->transport);
1145 		ctx->transport->last_time_sent = jiffies;
1146 
1147 		/* Only let one DATA chunk get bundled with a
1148 		 * COOKIE-ECHO chunk.
1149 		 */
1150 		if (ctx->packet->has_cookie_echo)
1151 			break;
1152 	}
1153 }
1154 
sctp_outq_flush_transports(struct sctp_flush_ctx * ctx)1155 static void sctp_outq_flush_transports(struct sctp_flush_ctx *ctx)
1156 {
1157 	struct sock *sk = ctx->asoc->base.sk;
1158 	struct list_head *ltransport;
1159 	struct sctp_packet *packet;
1160 	struct sctp_transport *t;
1161 	int error = 0;
1162 
1163 	while ((ltransport = sctp_list_dequeue(&ctx->transport_list)) != NULL) {
1164 		t = list_entry(ltransport, struct sctp_transport, send_ready);
1165 		packet = &t->packet;
1166 		if (!sctp_packet_empty(packet)) {
1167 			rcu_read_lock();
1168 			if (t->dst && __sk_dst_get(sk) != t->dst) {
1169 				dst_hold(t->dst);
1170 				sk_setup_caps(sk, t->dst);
1171 			}
1172 			rcu_read_unlock();
1173 			error = sctp_packet_transmit(packet, ctx->gfp);
1174 			if (error < 0)
1175 				ctx->q->asoc->base.sk->sk_err = -error;
1176 		}
1177 
1178 		/* Clear the burst limited state, if any */
1179 		sctp_transport_burst_reset(t);
1180 	}
1181 }
1182 
1183 /* Try to flush an outqueue.
1184  *
1185  * Description: Send everything in q which we legally can, subject to
1186  * congestion limitations.
1187  * * Note: This function can be called from multiple contexts so appropriate
1188  * locking concerns must be made.  Today we use the sock lock to protect
1189  * this function.
1190  */
1191 
sctp_outq_flush(struct sctp_outq * q,int rtx_timeout,gfp_t gfp)1192 static void sctp_outq_flush(struct sctp_outq *q, int rtx_timeout, gfp_t gfp)
1193 {
1194 	struct sctp_flush_ctx ctx = {
1195 		.q = q,
1196 		.transport = NULL,
1197 		.transport_list = LIST_HEAD_INIT(ctx.transport_list),
1198 		.asoc = q->asoc,
1199 		.packet = NULL,
1200 		.gfp = gfp,
1201 	};
1202 
1203 	/* 6.10 Bundling
1204 	 *   ...
1205 	 *   When bundling control chunks with DATA chunks, an
1206 	 *   endpoint MUST place control chunks first in the outbound
1207 	 *   SCTP packet.  The transmitter MUST transmit DATA chunks
1208 	 *   within a SCTP packet in increasing order of TSN.
1209 	 *   ...
1210 	 */
1211 
1212 	sctp_outq_flush_ctrl(&ctx);
1213 
1214 	if (q->asoc->src_out_of_asoc_ok)
1215 		goto sctp_flush_out;
1216 
1217 	sctp_outq_flush_data(&ctx, rtx_timeout);
1218 
1219 sctp_flush_out:
1220 
1221 	sctp_outq_flush_transports(&ctx);
1222 }
1223 
1224 /* Update unack_data based on the incoming SACK chunk */
sctp_sack_update_unack_data(struct sctp_association * assoc,struct sctp_sackhdr * sack)1225 static void sctp_sack_update_unack_data(struct sctp_association *assoc,
1226 					struct sctp_sackhdr *sack)
1227 {
1228 	union sctp_sack_variable *frags;
1229 	__u16 unack_data;
1230 	int i;
1231 
1232 	unack_data = assoc->next_tsn - assoc->ctsn_ack_point - 1;
1233 
1234 	frags = (union sctp_sack_variable *)(sack + 1);
1235 	for (i = 0; i < ntohs(sack->num_gap_ack_blocks); i++) {
1236 		unack_data -= ((ntohs(frags[i].gab.end) -
1237 				ntohs(frags[i].gab.start) + 1));
1238 	}
1239 
1240 	assoc->unack_data = unack_data;
1241 }
1242 
1243 /* This is where we REALLY process a SACK.
1244  *
1245  * Process the SACK against the outqueue.  Mostly, this just frees
1246  * things off the transmitted queue.
1247  */
sctp_outq_sack(struct sctp_outq * q,struct sctp_chunk * chunk)1248 int sctp_outq_sack(struct sctp_outq *q, struct sctp_chunk *chunk)
1249 {
1250 	struct sctp_association *asoc = q->asoc;
1251 	struct sctp_sackhdr *sack = chunk->subh.sack_hdr;
1252 	struct sctp_transport *transport;
1253 	struct sctp_chunk *tchunk = NULL;
1254 	struct list_head *lchunk, *transport_list, *temp;
1255 	__u32 sack_ctsn, ctsn, tsn;
1256 	__u32 highest_tsn, highest_new_tsn;
1257 	__u32 sack_a_rwnd;
1258 	unsigned int outstanding;
1259 	struct sctp_transport *primary = asoc->peer.primary_path;
1260 	int count_of_newacks = 0;
1261 	int gap_ack_blocks;
1262 	u8 accum_moved = 0;
1263 
1264 	/* Grab the association's destination address list. */
1265 	transport_list = &asoc->peer.transport_addr_list;
1266 
1267 	/* SCTP path tracepoint for congestion control debugging. */
1268 	if (trace_sctp_probe_path_enabled()) {
1269 		list_for_each_entry(transport, transport_list, transports)
1270 			trace_sctp_probe_path(transport, asoc);
1271 	}
1272 
1273 	sack_ctsn = ntohl(sack->cum_tsn_ack);
1274 	gap_ack_blocks = ntohs(sack->num_gap_ack_blocks);
1275 	asoc->stats.gapcnt += gap_ack_blocks;
1276 	/*
1277 	 * SFR-CACC algorithm:
1278 	 * On receipt of a SACK the sender SHOULD execute the
1279 	 * following statements.
1280 	 *
1281 	 * 1) If the cumulative ack in the SACK passes next tsn_at_change
1282 	 * on the current primary, the CHANGEOVER_ACTIVE flag SHOULD be
1283 	 * cleared. The CYCLING_CHANGEOVER flag SHOULD also be cleared for
1284 	 * all destinations.
1285 	 * 2) If the SACK contains gap acks and the flag CHANGEOVER_ACTIVE
1286 	 * is set the receiver of the SACK MUST take the following actions:
1287 	 *
1288 	 * A) Initialize the cacc_saw_newack to 0 for all destination
1289 	 * addresses.
1290 	 *
1291 	 * Only bother if changeover_active is set. Otherwise, this is
1292 	 * totally suboptimal to do on every SACK.
1293 	 */
1294 	if (primary->cacc.changeover_active) {
1295 		u8 clear_cycling = 0;
1296 
1297 		if (TSN_lte(primary->cacc.next_tsn_at_change, sack_ctsn)) {
1298 			primary->cacc.changeover_active = 0;
1299 			clear_cycling = 1;
1300 		}
1301 
1302 		if (clear_cycling || gap_ack_blocks) {
1303 			list_for_each_entry(transport, transport_list,
1304 					transports) {
1305 				if (clear_cycling)
1306 					transport->cacc.cycling_changeover = 0;
1307 				if (gap_ack_blocks)
1308 					transport->cacc.cacc_saw_newack = 0;
1309 			}
1310 		}
1311 	}
1312 
1313 	/* Get the highest TSN in the sack. */
1314 	highest_tsn = sack_ctsn;
1315 	if (gap_ack_blocks) {
1316 		union sctp_sack_variable *frags =
1317 			(union sctp_sack_variable *)(sack + 1);
1318 
1319 		highest_tsn += ntohs(frags[gap_ack_blocks - 1].gab.end);
1320 	}
1321 
1322 	if (TSN_lt(asoc->highest_sacked, highest_tsn))
1323 		asoc->highest_sacked = highest_tsn;
1324 
1325 	highest_new_tsn = sack_ctsn;
1326 
1327 	/* Run through the retransmit queue.  Credit bytes received
1328 	 * and free those chunks that we can.
1329 	 */
1330 	sctp_check_transmitted(q, &q->retransmit, NULL, NULL, sack, &highest_new_tsn);
1331 
1332 	/* Run through the transmitted queue.
1333 	 * Credit bytes received and free those chunks which we can.
1334 	 *
1335 	 * This is a MASSIVE candidate for optimization.
1336 	 */
1337 	list_for_each_entry(transport, transport_list, transports) {
1338 		sctp_check_transmitted(q, &transport->transmitted,
1339 				       transport, &chunk->source, sack,
1340 				       &highest_new_tsn);
1341 		/*
1342 		 * SFR-CACC algorithm:
1343 		 * C) Let count_of_newacks be the number of
1344 		 * destinations for which cacc_saw_newack is set.
1345 		 */
1346 		if (transport->cacc.cacc_saw_newack)
1347 			count_of_newacks++;
1348 	}
1349 
1350 	/* Move the Cumulative TSN Ack Point if appropriate.  */
1351 	if (TSN_lt(asoc->ctsn_ack_point, sack_ctsn)) {
1352 		asoc->ctsn_ack_point = sack_ctsn;
1353 		accum_moved = 1;
1354 	}
1355 
1356 	if (gap_ack_blocks) {
1357 
1358 		if (asoc->fast_recovery && accum_moved)
1359 			highest_new_tsn = highest_tsn;
1360 
1361 		list_for_each_entry(transport, transport_list, transports)
1362 			sctp_mark_missing(q, &transport->transmitted, transport,
1363 					  highest_new_tsn, count_of_newacks);
1364 	}
1365 
1366 	/* Update unack_data field in the assoc. */
1367 	sctp_sack_update_unack_data(asoc, sack);
1368 
1369 	ctsn = asoc->ctsn_ack_point;
1370 
1371 	/* Throw away stuff rotting on the sack queue.  */
1372 	list_for_each_safe(lchunk, temp, &q->sacked) {
1373 		tchunk = list_entry(lchunk, struct sctp_chunk,
1374 				    transmitted_list);
1375 		tsn = ntohl(tchunk->subh.data_hdr->tsn);
1376 		if (TSN_lte(tsn, ctsn)) {
1377 			list_del_init(&tchunk->transmitted_list);
1378 			if (asoc->peer.prsctp_capable &&
1379 			    SCTP_PR_PRIO_ENABLED(chunk->sinfo.sinfo_flags))
1380 				asoc->sent_cnt_removable--;
1381 			sctp_chunk_free(tchunk);
1382 		}
1383 	}
1384 
1385 	/* ii) Set rwnd equal to the newly received a_rwnd minus the
1386 	 *     number of bytes still outstanding after processing the
1387 	 *     Cumulative TSN Ack and the Gap Ack Blocks.
1388 	 */
1389 
1390 	sack_a_rwnd = ntohl(sack->a_rwnd);
1391 	asoc->peer.zero_window_announced = !sack_a_rwnd;
1392 	outstanding = q->outstanding_bytes;
1393 
1394 	if (outstanding < sack_a_rwnd)
1395 		sack_a_rwnd -= outstanding;
1396 	else
1397 		sack_a_rwnd = 0;
1398 
1399 	asoc->peer.rwnd = sack_a_rwnd;
1400 
1401 	asoc->stream.si->generate_ftsn(q, sack_ctsn);
1402 
1403 	pr_debug("%s: sack cumulative tsn ack:0x%x\n", __func__, sack_ctsn);
1404 	pr_debug("%s: cumulative tsn ack of assoc:%p is 0x%x, "
1405 		 "advertised peer ack point:0x%x\n", __func__, asoc, ctsn,
1406 		 asoc->adv_peer_ack_point);
1407 
1408 	return sctp_outq_is_empty(q);
1409 }
1410 
1411 /* Is the outqueue empty?
1412  * The queue is empty when we have not pending data, no in-flight data
1413  * and nothing pending retransmissions.
1414  */
sctp_outq_is_empty(const struct sctp_outq * q)1415 int sctp_outq_is_empty(const struct sctp_outq *q)
1416 {
1417 	return q->out_qlen == 0 && q->outstanding_bytes == 0 &&
1418 	       list_empty(&q->retransmit);
1419 }
1420 
1421 /********************************************************************
1422  * 2nd Level Abstractions
1423  ********************************************************************/
1424 
1425 /* Go through a transport's transmitted list or the association's retransmit
1426  * list and move chunks that are acked by the Cumulative TSN Ack to q->sacked.
1427  * The retransmit list will not have an associated transport.
1428  *
1429  * I added coherent debug information output.	--xguo
1430  *
1431  * Instead of printing 'sacked' or 'kept' for each TSN on the
1432  * transmitted_queue, we print a range: SACKED: TSN1-TSN2, TSN3, TSN4-TSN5.
1433  * KEPT TSN6-TSN7, etc.
1434  */
sctp_check_transmitted(struct sctp_outq * q,struct list_head * transmitted_queue,struct sctp_transport * transport,union sctp_addr * saddr,struct sctp_sackhdr * sack,__u32 * highest_new_tsn_in_sack)1435 static void sctp_check_transmitted(struct sctp_outq *q,
1436 				   struct list_head *transmitted_queue,
1437 				   struct sctp_transport *transport,
1438 				   union sctp_addr *saddr,
1439 				   struct sctp_sackhdr *sack,
1440 				   __u32 *highest_new_tsn_in_sack)
1441 {
1442 	struct list_head *lchunk;
1443 	struct sctp_chunk *tchunk;
1444 	struct list_head tlist;
1445 	__u32 tsn;
1446 	__u32 sack_ctsn;
1447 	__u32 rtt;
1448 	__u8 restart_timer = 0;
1449 	int bytes_acked = 0;
1450 	int migrate_bytes = 0;
1451 	bool forward_progress = false;
1452 
1453 	sack_ctsn = ntohl(sack->cum_tsn_ack);
1454 
1455 	INIT_LIST_HEAD(&tlist);
1456 
1457 	/* The while loop will skip empty transmitted queues. */
1458 	while (NULL != (lchunk = sctp_list_dequeue(transmitted_queue))) {
1459 		tchunk = list_entry(lchunk, struct sctp_chunk,
1460 				    transmitted_list);
1461 
1462 		if (sctp_chunk_abandoned(tchunk)) {
1463 			/* Move the chunk to abandoned list. */
1464 			sctp_insert_list(&q->abandoned, lchunk);
1465 
1466 			/* If this chunk has not been acked, stop
1467 			 * considering it as 'outstanding'.
1468 			 */
1469 			if (transmitted_queue != &q->retransmit &&
1470 			    !tchunk->tsn_gap_acked) {
1471 				if (tchunk->transport)
1472 					tchunk->transport->flight_size -=
1473 							sctp_data_size(tchunk);
1474 				q->outstanding_bytes -= sctp_data_size(tchunk);
1475 			}
1476 			continue;
1477 		}
1478 
1479 		tsn = ntohl(tchunk->subh.data_hdr->tsn);
1480 		if (sctp_acked(sack, tsn)) {
1481 			/* If this queue is the retransmit queue, the
1482 			 * retransmit timer has already reclaimed
1483 			 * the outstanding bytes for this chunk, so only
1484 			 * count bytes associated with a transport.
1485 			 */
1486 			if (transport && !tchunk->tsn_gap_acked) {
1487 				/* If this chunk is being used for RTT
1488 				 * measurement, calculate the RTT and update
1489 				 * the RTO using this value.
1490 				 *
1491 				 * 6.3.1 C5) Karn's algorithm: RTT measurements
1492 				 * MUST NOT be made using packets that were
1493 				 * retransmitted (and thus for which it is
1494 				 * ambiguous whether the reply was for the
1495 				 * first instance of the packet or a later
1496 				 * instance).
1497 				 */
1498 				if (!sctp_chunk_retransmitted(tchunk) &&
1499 				    tchunk->rtt_in_progress) {
1500 					tchunk->rtt_in_progress = 0;
1501 					rtt = jiffies - tchunk->sent_at;
1502 					sctp_transport_update_rto(transport,
1503 								  rtt);
1504 				}
1505 
1506 				if (TSN_lte(tsn, sack_ctsn)) {
1507 					/*
1508 					 * SFR-CACC algorithm:
1509 					 * 2) If the SACK contains gap acks
1510 					 * and the flag CHANGEOVER_ACTIVE is
1511 					 * set the receiver of the SACK MUST
1512 					 * take the following action:
1513 					 *
1514 					 * B) For each TSN t being acked that
1515 					 * has not been acked in any SACK so
1516 					 * far, set cacc_saw_newack to 1 for
1517 					 * the destination that the TSN was
1518 					 * sent to.
1519 					 */
1520 					if (sack->num_gap_ack_blocks &&
1521 					    q->asoc->peer.primary_path->cacc.
1522 					    changeover_active)
1523 						transport->cacc.cacc_saw_newack
1524 							= 1;
1525 				}
1526 			}
1527 
1528 			/* If the chunk hasn't been marked as ACKED,
1529 			 * mark it and account bytes_acked if the
1530 			 * chunk had a valid transport (it will not
1531 			 * have a transport if ASCONF had deleted it
1532 			 * while DATA was outstanding).
1533 			 */
1534 			if (!tchunk->tsn_gap_acked) {
1535 				tchunk->tsn_gap_acked = 1;
1536 				if (TSN_lt(*highest_new_tsn_in_sack, tsn))
1537 					*highest_new_tsn_in_sack = tsn;
1538 				bytes_acked += sctp_data_size(tchunk);
1539 				if (!tchunk->transport)
1540 					migrate_bytes += sctp_data_size(tchunk);
1541 				forward_progress = true;
1542 			}
1543 
1544 			if (TSN_lte(tsn, sack_ctsn)) {
1545 				/* RFC 2960  6.3.2 Retransmission Timer Rules
1546 				 *
1547 				 * R3) Whenever a SACK is received
1548 				 * that acknowledges the DATA chunk
1549 				 * with the earliest outstanding TSN
1550 				 * for that address, restart T3-rtx
1551 				 * timer for that address with its
1552 				 * current RTO.
1553 				 */
1554 				restart_timer = 1;
1555 				forward_progress = true;
1556 
1557 				list_add_tail(&tchunk->transmitted_list,
1558 					      &q->sacked);
1559 			} else {
1560 				/* RFC2960 7.2.4, sctpimpguide-05 2.8.2
1561 				 * M2) Each time a SACK arrives reporting
1562 				 * 'Stray DATA chunk(s)' record the highest TSN
1563 				 * reported as newly acknowledged, call this
1564 				 * value 'HighestTSNinSack'. A newly
1565 				 * acknowledged DATA chunk is one not
1566 				 * previously acknowledged in a SACK.
1567 				 *
1568 				 * When the SCTP sender of data receives a SACK
1569 				 * chunk that acknowledges, for the first time,
1570 				 * the receipt of a DATA chunk, all the still
1571 				 * unacknowledged DATA chunks whose TSN is
1572 				 * older than that newly acknowledged DATA
1573 				 * chunk, are qualified as 'Stray DATA chunks'.
1574 				 */
1575 				list_add_tail(lchunk, &tlist);
1576 			}
1577 		} else {
1578 			if (tchunk->tsn_gap_acked) {
1579 				pr_debug("%s: receiver reneged on data TSN:0x%x\n",
1580 					 __func__, tsn);
1581 
1582 				tchunk->tsn_gap_acked = 0;
1583 
1584 				if (tchunk->transport)
1585 					bytes_acked -= sctp_data_size(tchunk);
1586 
1587 				/* RFC 2960 6.3.2 Retransmission Timer Rules
1588 				 *
1589 				 * R4) Whenever a SACK is received missing a
1590 				 * TSN that was previously acknowledged via a
1591 				 * Gap Ack Block, start T3-rtx for the
1592 				 * destination address to which the DATA
1593 				 * chunk was originally
1594 				 * transmitted if it is not already running.
1595 				 */
1596 				restart_timer = 1;
1597 			}
1598 
1599 			list_add_tail(lchunk, &tlist);
1600 		}
1601 	}
1602 
1603 	if (transport) {
1604 		if (bytes_acked) {
1605 			struct sctp_association *asoc = transport->asoc;
1606 
1607 			/* We may have counted DATA that was migrated
1608 			 * to this transport due to DEL-IP operation.
1609 			 * Subtract those bytes, since the were never
1610 			 * send on this transport and shouldn't be
1611 			 * credited to this transport.
1612 			 */
1613 			bytes_acked -= migrate_bytes;
1614 
1615 			/* 8.2. When an outstanding TSN is acknowledged,
1616 			 * the endpoint shall clear the error counter of
1617 			 * the destination transport address to which the
1618 			 * DATA chunk was last sent.
1619 			 * The association's overall error counter is
1620 			 * also cleared.
1621 			 */
1622 			transport->error_count = 0;
1623 			transport->asoc->overall_error_count = 0;
1624 			forward_progress = true;
1625 
1626 			/*
1627 			 * While in SHUTDOWN PENDING, we may have started
1628 			 * the T5 shutdown guard timer after reaching the
1629 			 * retransmission limit. Stop that timer as soon
1630 			 * as the receiver acknowledged any data.
1631 			 */
1632 			if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING &&
1633 			    del_timer(&asoc->timers
1634 				[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]))
1635 					sctp_association_put(asoc);
1636 
1637 			/* Mark the destination transport address as
1638 			 * active if it is not so marked.
1639 			 */
1640 			if ((transport->state == SCTP_INACTIVE ||
1641 			     transport->state == SCTP_UNCONFIRMED) &&
1642 			    sctp_cmp_addr_exact(&transport->ipaddr, saddr)) {
1643 				sctp_assoc_control_transport(
1644 					transport->asoc,
1645 					transport,
1646 					SCTP_TRANSPORT_UP,
1647 					SCTP_RECEIVED_SACK);
1648 			}
1649 
1650 			sctp_transport_raise_cwnd(transport, sack_ctsn,
1651 						  bytes_acked);
1652 
1653 			transport->flight_size -= bytes_acked;
1654 			if (transport->flight_size == 0)
1655 				transport->partial_bytes_acked = 0;
1656 			q->outstanding_bytes -= bytes_acked + migrate_bytes;
1657 		} else {
1658 			/* RFC 2960 6.1, sctpimpguide-06 2.15.2
1659 			 * When a sender is doing zero window probing, it
1660 			 * should not timeout the association if it continues
1661 			 * to receive new packets from the receiver. The
1662 			 * reason is that the receiver MAY keep its window
1663 			 * closed for an indefinite time.
1664 			 * A sender is doing zero window probing when the
1665 			 * receiver's advertised window is zero, and there is
1666 			 * only one data chunk in flight to the receiver.
1667 			 *
1668 			 * Allow the association to timeout while in SHUTDOWN
1669 			 * PENDING or SHUTDOWN RECEIVED in case the receiver
1670 			 * stays in zero window mode forever.
1671 			 */
1672 			if (!q->asoc->peer.rwnd &&
1673 			    !list_empty(&tlist) &&
1674 			    (sack_ctsn+2 == q->asoc->next_tsn) &&
1675 			    q->asoc->state < SCTP_STATE_SHUTDOWN_PENDING) {
1676 				pr_debug("%s: sack received for zero window "
1677 					 "probe:%u\n", __func__, sack_ctsn);
1678 
1679 				q->asoc->overall_error_count = 0;
1680 				transport->error_count = 0;
1681 			}
1682 		}
1683 
1684 		/* RFC 2960 6.3.2 Retransmission Timer Rules
1685 		 *
1686 		 * R2) Whenever all outstanding data sent to an address have
1687 		 * been acknowledged, turn off the T3-rtx timer of that
1688 		 * address.
1689 		 */
1690 		if (!transport->flight_size) {
1691 			if (del_timer(&transport->T3_rtx_timer))
1692 				sctp_transport_put(transport);
1693 		} else if (restart_timer) {
1694 			if (!mod_timer(&transport->T3_rtx_timer,
1695 				       jiffies + transport->rto))
1696 				sctp_transport_hold(transport);
1697 		}
1698 
1699 		if (forward_progress) {
1700 			if (transport->dst)
1701 				sctp_transport_dst_confirm(transport);
1702 		}
1703 	}
1704 
1705 	list_splice(&tlist, transmitted_queue);
1706 }
1707 
1708 /* Mark chunks as missing and consequently may get retransmitted. */
sctp_mark_missing(struct sctp_outq * q,struct list_head * transmitted_queue,struct sctp_transport * transport,__u32 highest_new_tsn_in_sack,int count_of_newacks)1709 static void sctp_mark_missing(struct sctp_outq *q,
1710 			      struct list_head *transmitted_queue,
1711 			      struct sctp_transport *transport,
1712 			      __u32 highest_new_tsn_in_sack,
1713 			      int count_of_newacks)
1714 {
1715 	struct sctp_chunk *chunk;
1716 	__u32 tsn;
1717 	char do_fast_retransmit = 0;
1718 	struct sctp_association *asoc = q->asoc;
1719 	struct sctp_transport *primary = asoc->peer.primary_path;
1720 
1721 	list_for_each_entry(chunk, transmitted_queue, transmitted_list) {
1722 
1723 		tsn = ntohl(chunk->subh.data_hdr->tsn);
1724 
1725 		/* RFC 2960 7.2.4, sctpimpguide-05 2.8.2 M3) Examine all
1726 		 * 'Unacknowledged TSN's', if the TSN number of an
1727 		 * 'Unacknowledged TSN' is smaller than the 'HighestTSNinSack'
1728 		 * value, increment the 'TSN.Missing.Report' count on that
1729 		 * chunk if it has NOT been fast retransmitted or marked for
1730 		 * fast retransmit already.
1731 		 */
1732 		if (chunk->fast_retransmit == SCTP_CAN_FRTX &&
1733 		    !chunk->tsn_gap_acked &&
1734 		    TSN_lt(tsn, highest_new_tsn_in_sack)) {
1735 
1736 			/* SFR-CACC may require us to skip marking
1737 			 * this chunk as missing.
1738 			 */
1739 			if (!transport || !sctp_cacc_skip(primary,
1740 						chunk->transport,
1741 						count_of_newacks, tsn)) {
1742 				chunk->tsn_missing_report++;
1743 
1744 				pr_debug("%s: tsn:0x%x missing counter:%d\n",
1745 					 __func__, tsn, chunk->tsn_missing_report);
1746 			}
1747 		}
1748 		/*
1749 		 * M4) If any DATA chunk is found to have a
1750 		 * 'TSN.Missing.Report'
1751 		 * value larger than or equal to 3, mark that chunk for
1752 		 * retransmission and start the fast retransmit procedure.
1753 		 */
1754 
1755 		if (chunk->tsn_missing_report >= 3) {
1756 			chunk->fast_retransmit = SCTP_NEED_FRTX;
1757 			do_fast_retransmit = 1;
1758 		}
1759 	}
1760 
1761 	if (transport) {
1762 		if (do_fast_retransmit)
1763 			sctp_retransmit(q, transport, SCTP_RTXR_FAST_RTX);
1764 
1765 		pr_debug("%s: transport:%p, cwnd:%d, ssthresh:%d, "
1766 			 "flight_size:%d, pba:%d\n",  __func__, transport,
1767 			 transport->cwnd, transport->ssthresh,
1768 			 transport->flight_size, transport->partial_bytes_acked);
1769 	}
1770 }
1771 
1772 /* Is the given TSN acked by this packet?  */
sctp_acked(struct sctp_sackhdr * sack,__u32 tsn)1773 static int sctp_acked(struct sctp_sackhdr *sack, __u32 tsn)
1774 {
1775 	__u32 ctsn = ntohl(sack->cum_tsn_ack);
1776 	union sctp_sack_variable *frags;
1777 	__u16 tsn_offset, blocks;
1778 	int i;
1779 
1780 	if (TSN_lte(tsn, ctsn))
1781 		goto pass;
1782 
1783 	/* 3.3.4 Selective Acknowledgment (SACK) (3):
1784 	 *
1785 	 * Gap Ack Blocks:
1786 	 *  These fields contain the Gap Ack Blocks. They are repeated
1787 	 *  for each Gap Ack Block up to the number of Gap Ack Blocks
1788 	 *  defined in the Number of Gap Ack Blocks field. All DATA
1789 	 *  chunks with TSNs greater than or equal to (Cumulative TSN
1790 	 *  Ack + Gap Ack Block Start) and less than or equal to
1791 	 *  (Cumulative TSN Ack + Gap Ack Block End) of each Gap Ack
1792 	 *  Block are assumed to have been received correctly.
1793 	 */
1794 
1795 	frags = (union sctp_sack_variable *)(sack + 1);
1796 	blocks = ntohs(sack->num_gap_ack_blocks);
1797 	tsn_offset = tsn - ctsn;
1798 	for (i = 0; i < blocks; ++i) {
1799 		if (tsn_offset >= ntohs(frags[i].gab.start) &&
1800 		    tsn_offset <= ntohs(frags[i].gab.end))
1801 			goto pass;
1802 	}
1803 
1804 	return 0;
1805 pass:
1806 	return 1;
1807 }
1808 
sctp_get_skip_pos(struct sctp_fwdtsn_skip * skiplist,int nskips,__be16 stream)1809 static inline int sctp_get_skip_pos(struct sctp_fwdtsn_skip *skiplist,
1810 				    int nskips, __be16 stream)
1811 {
1812 	int i;
1813 
1814 	for (i = 0; i < nskips; i++) {
1815 		if (skiplist[i].stream == stream)
1816 			return i;
1817 	}
1818 	return i;
1819 }
1820 
1821 /* Create and add a fwdtsn chunk to the outq's control queue if needed. */
sctp_generate_fwdtsn(struct sctp_outq * q,__u32 ctsn)1822 void sctp_generate_fwdtsn(struct sctp_outq *q, __u32 ctsn)
1823 {
1824 	struct sctp_association *asoc = q->asoc;
1825 	struct sctp_chunk *ftsn_chunk = NULL;
1826 	struct sctp_fwdtsn_skip ftsn_skip_arr[10];
1827 	int nskips = 0;
1828 	int skip_pos = 0;
1829 	__u32 tsn;
1830 	struct sctp_chunk *chunk;
1831 	struct list_head *lchunk, *temp;
1832 
1833 	if (!asoc->peer.prsctp_capable)
1834 		return;
1835 
1836 	/* PR-SCTP C1) Let SackCumAck be the Cumulative TSN ACK carried in the
1837 	 * received SACK.
1838 	 *
1839 	 * If (Advanced.Peer.Ack.Point < SackCumAck), then update
1840 	 * Advanced.Peer.Ack.Point to be equal to SackCumAck.
1841 	 */
1842 	if (TSN_lt(asoc->adv_peer_ack_point, ctsn))
1843 		asoc->adv_peer_ack_point = ctsn;
1844 
1845 	/* PR-SCTP C2) Try to further advance the "Advanced.Peer.Ack.Point"
1846 	 * locally, that is, to move "Advanced.Peer.Ack.Point" up as long as
1847 	 * the chunk next in the out-queue space is marked as "abandoned" as
1848 	 * shown in the following example:
1849 	 *
1850 	 * Assuming that a SACK arrived with the Cumulative TSN ACK 102
1851 	 * and the Advanced.Peer.Ack.Point is updated to this value:
1852 	 *
1853 	 *   out-queue at the end of  ==>   out-queue after Adv.Ack.Point
1854 	 *   normal SACK processing           local advancement
1855 	 *                ...                           ...
1856 	 *   Adv.Ack.Pt-> 102 acked                     102 acked
1857 	 *                103 abandoned                 103 abandoned
1858 	 *                104 abandoned     Adv.Ack.P-> 104 abandoned
1859 	 *                105                           105
1860 	 *                106 acked                     106 acked
1861 	 *                ...                           ...
1862 	 *
1863 	 * In this example, the data sender successfully advanced the
1864 	 * "Advanced.Peer.Ack.Point" from 102 to 104 locally.
1865 	 */
1866 	list_for_each_safe(lchunk, temp, &q->abandoned) {
1867 		chunk = list_entry(lchunk, struct sctp_chunk,
1868 					transmitted_list);
1869 		tsn = ntohl(chunk->subh.data_hdr->tsn);
1870 
1871 		/* Remove any chunks in the abandoned queue that are acked by
1872 		 * the ctsn.
1873 		 */
1874 		if (TSN_lte(tsn, ctsn)) {
1875 			list_del_init(lchunk);
1876 			sctp_chunk_free(chunk);
1877 		} else {
1878 			if (TSN_lte(tsn, asoc->adv_peer_ack_point+1)) {
1879 				asoc->adv_peer_ack_point = tsn;
1880 				if (chunk->chunk_hdr->flags &
1881 					 SCTP_DATA_UNORDERED)
1882 					continue;
1883 				skip_pos = sctp_get_skip_pos(&ftsn_skip_arr[0],
1884 						nskips,
1885 						chunk->subh.data_hdr->stream);
1886 				ftsn_skip_arr[skip_pos].stream =
1887 					chunk->subh.data_hdr->stream;
1888 				ftsn_skip_arr[skip_pos].ssn =
1889 					 chunk->subh.data_hdr->ssn;
1890 				if (skip_pos == nskips)
1891 					nskips++;
1892 				if (nskips == 10)
1893 					break;
1894 			} else
1895 				break;
1896 		}
1897 	}
1898 
1899 	/* PR-SCTP C3) If, after step C1 and C2, the "Advanced.Peer.Ack.Point"
1900 	 * is greater than the Cumulative TSN ACK carried in the received
1901 	 * SACK, the data sender MUST send the data receiver a FORWARD TSN
1902 	 * chunk containing the latest value of the
1903 	 * "Advanced.Peer.Ack.Point".
1904 	 *
1905 	 * C4) For each "abandoned" TSN the sender of the FORWARD TSN SHOULD
1906 	 * list each stream and sequence number in the forwarded TSN. This
1907 	 * information will enable the receiver to easily find any
1908 	 * stranded TSN's waiting on stream reorder queues. Each stream
1909 	 * SHOULD only be reported once; this means that if multiple
1910 	 * abandoned messages occur in the same stream then only the
1911 	 * highest abandoned stream sequence number is reported. If the
1912 	 * total size of the FORWARD TSN does NOT fit in a single MTU then
1913 	 * the sender of the FORWARD TSN SHOULD lower the
1914 	 * Advanced.Peer.Ack.Point to the last TSN that will fit in a
1915 	 * single MTU.
1916 	 */
1917 	if (asoc->adv_peer_ack_point > ctsn)
1918 		ftsn_chunk = sctp_make_fwdtsn(asoc, asoc->adv_peer_ack_point,
1919 					      nskips, &ftsn_skip_arr[0]);
1920 
1921 	if (ftsn_chunk) {
1922 		list_add_tail(&ftsn_chunk->list, &q->control_chunk_list);
1923 		SCTP_INC_STATS(asoc->base.net, SCTP_MIB_OUTCTRLCHUNKS);
1924 	}
1925 }
1926