xref: /openbmc/linux/net/sctp/sm_statefuns.c (revision b34e08d5)
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) 2001-2002 Intel Corp.
6  * Copyright (c) 2002      Nokia Corp.
7  *
8  * This is part of the SCTP Linux Kernel Implementation.
9  *
10  * These are the state functions for the state machine.
11  *
12  * This SCTP implementation is free software;
13  * you can redistribute it and/or modify it under the terms of
14  * the GNU General Public License as published by
15  * the Free Software Foundation; either version 2, or (at your option)
16  * any later version.
17  *
18  * This SCTP implementation is distributed in the hope that it
19  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
20  *                 ************************
21  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
22  * See the GNU General Public License for more details.
23  *
24  * You should have received a copy of the GNU General Public License
25  * along with GNU CC; see the file COPYING.  If not, see
26  * <http://www.gnu.org/licenses/>.
27  *
28  * Please send any bug reports or fixes you make to the
29  * email address(es):
30  *    lksctp developers <linux-sctp@vger.kernel.org>
31  *
32  * Written or modified by:
33  *    La Monte H.P. Yarroll <piggy@acm.org>
34  *    Karl Knutson          <karl@athena.chicago.il.us>
35  *    Mathew Kotowsky       <kotowsky@sctp.org>
36  *    Sridhar Samudrala     <samudrala@us.ibm.com>
37  *    Jon Grimm             <jgrimm@us.ibm.com>
38  *    Hui Huang 	    <hui.huang@nokia.com>
39  *    Dajiang Zhang 	    <dajiang.zhang@nokia.com>
40  *    Daisy Chang	    <daisyc@us.ibm.com>
41  *    Ardelle Fan	    <ardelle.fan@intel.com>
42  *    Ryan Layer	    <rmlayer@us.ibm.com>
43  *    Kevin Gao		    <kevin.gao@intel.com>
44  */
45 
46 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
47 
48 #include <linux/types.h>
49 #include <linux/kernel.h>
50 #include <linux/ip.h>
51 #include <linux/ipv6.h>
52 #include <linux/net.h>
53 #include <linux/inet.h>
54 #include <linux/slab.h>
55 #include <net/sock.h>
56 #include <net/inet_ecn.h>
57 #include <linux/skbuff.h>
58 #include <net/sctp/sctp.h>
59 #include <net/sctp/sm.h>
60 #include <net/sctp/structs.h>
61 
62 static struct sctp_packet *sctp_abort_pkt_new(struct net *net,
63 				  const struct sctp_endpoint *ep,
64 				  const struct sctp_association *asoc,
65 				  struct sctp_chunk *chunk,
66 				  const void *payload,
67 				  size_t paylen);
68 static int sctp_eat_data(const struct sctp_association *asoc,
69 			 struct sctp_chunk *chunk,
70 			 sctp_cmd_seq_t *commands);
71 static struct sctp_packet *sctp_ootb_pkt_new(struct net *net,
72 					     const struct sctp_association *asoc,
73 					     const struct sctp_chunk *chunk);
74 static void sctp_send_stale_cookie_err(struct net *net,
75 				       const struct sctp_endpoint *ep,
76 				       const struct sctp_association *asoc,
77 				       const struct sctp_chunk *chunk,
78 				       sctp_cmd_seq_t *commands,
79 				       struct sctp_chunk *err_chunk);
80 static sctp_disposition_t sctp_sf_do_5_2_6_stale(struct net *net,
81 						 const struct sctp_endpoint *ep,
82 						 const struct sctp_association *asoc,
83 						 const sctp_subtype_t type,
84 						 void *arg,
85 						 sctp_cmd_seq_t *commands);
86 static sctp_disposition_t sctp_sf_shut_8_4_5(struct net *net,
87 					     const struct sctp_endpoint *ep,
88 					     const struct sctp_association *asoc,
89 					     const sctp_subtype_t type,
90 					     void *arg,
91 					     sctp_cmd_seq_t *commands);
92 static sctp_disposition_t sctp_sf_tabort_8_4_8(struct net *net,
93 					const struct sctp_endpoint *ep,
94 					const struct sctp_association *asoc,
95 					const sctp_subtype_t type,
96 					void *arg,
97 					sctp_cmd_seq_t *commands);
98 static struct sctp_sackhdr *sctp_sm_pull_sack(struct sctp_chunk *chunk);
99 
100 static sctp_disposition_t sctp_stop_t1_and_abort(struct net *net,
101 					   sctp_cmd_seq_t *commands,
102 					   __be16 error, int sk_err,
103 					   const struct sctp_association *asoc,
104 					   struct sctp_transport *transport);
105 
106 static sctp_disposition_t sctp_sf_abort_violation(
107 				     struct net *net,
108 				     const struct sctp_endpoint *ep,
109 				     const struct sctp_association *asoc,
110 				     void *arg,
111 				     sctp_cmd_seq_t *commands,
112 				     const __u8 *payload,
113 				     const size_t paylen);
114 
115 static sctp_disposition_t sctp_sf_violation_chunklen(
116 				     struct net *net,
117 				     const struct sctp_endpoint *ep,
118 				     const struct sctp_association *asoc,
119 				     const sctp_subtype_t type,
120 				     void *arg,
121 				     sctp_cmd_seq_t *commands);
122 
123 static sctp_disposition_t sctp_sf_violation_paramlen(
124 				     struct net *net,
125 				     const struct sctp_endpoint *ep,
126 				     const struct sctp_association *asoc,
127 				     const sctp_subtype_t type,
128 				     void *arg, void *ext,
129 				     sctp_cmd_seq_t *commands);
130 
131 static sctp_disposition_t sctp_sf_violation_ctsn(
132 				     struct net *net,
133 				     const struct sctp_endpoint *ep,
134 				     const struct sctp_association *asoc,
135 				     const sctp_subtype_t type,
136 				     void *arg,
137 				     sctp_cmd_seq_t *commands);
138 
139 static sctp_disposition_t sctp_sf_violation_chunk(
140 				     struct net *net,
141 				     const struct sctp_endpoint *ep,
142 				     const struct sctp_association *asoc,
143 				     const sctp_subtype_t type,
144 				     void *arg,
145 				     sctp_cmd_seq_t *commands);
146 
147 static sctp_ierror_t sctp_sf_authenticate(struct net *net,
148 				    const struct sctp_endpoint *ep,
149 				    const struct sctp_association *asoc,
150 				    const sctp_subtype_t type,
151 				    struct sctp_chunk *chunk);
152 
153 static sctp_disposition_t __sctp_sf_do_9_1_abort(struct net *net,
154 					const struct sctp_endpoint *ep,
155 					const struct sctp_association *asoc,
156 					const sctp_subtype_t type,
157 					void *arg,
158 					sctp_cmd_seq_t *commands);
159 
160 /* Small helper function that checks if the chunk length
161  * is of the appropriate length.  The 'required_length' argument
162  * is set to be the size of a specific chunk we are testing.
163  * Return Values:  1 = Valid length
164  * 		   0 = Invalid length
165  *
166  */
167 static inline int
168 sctp_chunk_length_valid(struct sctp_chunk *chunk,
169 			   __u16 required_length)
170 {
171 	__u16 chunk_length = ntohs(chunk->chunk_hdr->length);
172 
173 	if (unlikely(chunk_length < required_length))
174 		return 0;
175 
176 	return 1;
177 }
178 
179 /**********************************************************
180  * These are the state functions for handling chunk events.
181  **********************************************************/
182 
183 /*
184  * Process the final SHUTDOWN COMPLETE.
185  *
186  * Section: 4 (C) (diagram), 9.2
187  * Upon reception of the SHUTDOWN COMPLETE chunk the endpoint will verify
188  * that it is in SHUTDOWN-ACK-SENT state, if it is not the chunk should be
189  * discarded. If the endpoint is in the SHUTDOWN-ACK-SENT state the endpoint
190  * should stop the T2-shutdown timer and remove all knowledge of the
191  * association (and thus the association enters the CLOSED state).
192  *
193  * Verification Tag: 8.5.1(C), sctpimpguide 2.41.
194  * C) Rules for packet carrying SHUTDOWN COMPLETE:
195  * ...
196  * - The receiver of a SHUTDOWN COMPLETE shall accept the packet
197  *   if the Verification Tag field of the packet matches its own tag and
198  *   the T bit is not set
199  *   OR
200  *   it is set to its peer's tag and the T bit is set in the Chunk
201  *   Flags.
202  *   Otherwise, the receiver MUST silently discard the packet
203  *   and take no further action.  An endpoint MUST ignore the
204  *   SHUTDOWN COMPLETE if it is not in the SHUTDOWN-ACK-SENT state.
205  *
206  * Inputs
207  * (endpoint, asoc, chunk)
208  *
209  * Outputs
210  * (asoc, reply_msg, msg_up, timers, counters)
211  *
212  * The return value is the disposition of the chunk.
213  */
214 sctp_disposition_t sctp_sf_do_4_C(struct net *net,
215 				  const struct sctp_endpoint *ep,
216 				  const struct sctp_association *asoc,
217 				  const sctp_subtype_t type,
218 				  void *arg,
219 				  sctp_cmd_seq_t *commands)
220 {
221 	struct sctp_chunk *chunk = arg;
222 	struct sctp_ulpevent *ev;
223 
224 	if (!sctp_vtag_verify_either(chunk, asoc))
225 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
226 
227 	/* RFC 2960 6.10 Bundling
228 	 *
229 	 * An endpoint MUST NOT bundle INIT, INIT ACK or
230 	 * SHUTDOWN COMPLETE with any other chunks.
231 	 */
232 	if (!chunk->singleton)
233 		return sctp_sf_violation_chunk(net, ep, asoc, type, arg, commands);
234 
235 	/* Make sure that the SHUTDOWN_COMPLETE chunk has a valid length. */
236 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
237 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
238 						  commands);
239 
240 	/* RFC 2960 10.2 SCTP-to-ULP
241 	 *
242 	 * H) SHUTDOWN COMPLETE notification
243 	 *
244 	 * When SCTP completes the shutdown procedures (section 9.2) this
245 	 * notification is passed to the upper layer.
246 	 */
247 	ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_SHUTDOWN_COMP,
248 					     0, 0, 0, NULL, GFP_ATOMIC);
249 	if (ev)
250 		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
251 				SCTP_ULPEVENT(ev));
252 
253 	/* Upon reception of the SHUTDOWN COMPLETE chunk the endpoint
254 	 * will verify that it is in SHUTDOWN-ACK-SENT state, if it is
255 	 * not the chunk should be discarded. If the endpoint is in
256 	 * the SHUTDOWN-ACK-SENT state the endpoint should stop the
257 	 * T2-shutdown timer and remove all knowledge of the
258 	 * association (and thus the association enters the CLOSED
259 	 * state).
260 	 */
261 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
262 			SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
263 
264 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
265 			SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
266 
267 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
268 			SCTP_STATE(SCTP_STATE_CLOSED));
269 
270 	SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS);
271 	SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
272 
273 	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
274 
275 	return SCTP_DISPOSITION_DELETE_TCB;
276 }
277 
278 /*
279  * Respond to a normal INIT chunk.
280  * We are the side that is being asked for an association.
281  *
282  * Section: 5.1 Normal Establishment of an Association, B
283  * B) "Z" shall respond immediately with an INIT ACK chunk.  The
284  *    destination IP address of the INIT ACK MUST be set to the source
285  *    IP address of the INIT to which this INIT ACK is responding.  In
286  *    the response, besides filling in other parameters, "Z" must set the
287  *    Verification Tag field to Tag_A, and also provide its own
288  *    Verification Tag (Tag_Z) in the Initiate Tag field.
289  *
290  * Verification Tag: Must be 0.
291  *
292  * Inputs
293  * (endpoint, asoc, chunk)
294  *
295  * Outputs
296  * (asoc, reply_msg, msg_up, timers, counters)
297  *
298  * The return value is the disposition of the chunk.
299  */
300 sctp_disposition_t sctp_sf_do_5_1B_init(struct net *net,
301 					const struct sctp_endpoint *ep,
302 					const struct sctp_association *asoc,
303 					const sctp_subtype_t type,
304 					void *arg,
305 					sctp_cmd_seq_t *commands)
306 {
307 	struct sctp_chunk *chunk = arg;
308 	struct sctp_chunk *repl;
309 	struct sctp_association *new_asoc;
310 	struct sctp_chunk *err_chunk;
311 	struct sctp_packet *packet;
312 	sctp_unrecognized_param_t *unk_param;
313 	int len;
314 
315 	/* 6.10 Bundling
316 	 * An endpoint MUST NOT bundle INIT, INIT ACK or
317 	 * SHUTDOWN COMPLETE with any other chunks.
318 	 *
319 	 * IG Section 2.11.2
320 	 * Furthermore, we require that the receiver of an INIT chunk MUST
321 	 * enforce these rules by silently discarding an arriving packet
322 	 * with an INIT chunk that is bundled with other chunks.
323 	 */
324 	if (!chunk->singleton)
325 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
326 
327 	/* If the packet is an OOTB packet which is temporarily on the
328 	 * control endpoint, respond with an ABORT.
329 	 */
330 	if (ep == sctp_sk(net->sctp.ctl_sock)->ep) {
331 		SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
332 		return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
333 	}
334 
335 	/* 3.1 A packet containing an INIT chunk MUST have a zero Verification
336 	 * Tag.
337 	 */
338 	if (chunk->sctp_hdr->vtag != 0)
339 		return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
340 
341 	/* Make sure that the INIT chunk has a valid length.
342 	 * Normally, this would cause an ABORT with a Protocol Violation
343 	 * error, but since we don't have an association, we'll
344 	 * just discard the packet.
345 	 */
346 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_init_chunk_t)))
347 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
348 
349 	/* If the INIT is coming toward a closing socket, we'll send back
350 	 * and ABORT.  Essentially, this catches the race of INIT being
351 	 * backloged to the socket at the same time as the user isses close().
352 	 * Since the socket and all its associations are going away, we
353 	 * can treat this OOTB
354 	 */
355 	if (sctp_sstate(ep->base.sk, CLOSING))
356 		return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
357 
358 	/* Verify the INIT chunk before processing it. */
359 	err_chunk = NULL;
360 	if (!sctp_verify_init(net, asoc, chunk->chunk_hdr->type,
361 			      (sctp_init_chunk_t *)chunk->chunk_hdr, chunk,
362 			      &err_chunk)) {
363 		/* This chunk contains fatal error. It is to be discarded.
364 		 * Send an ABORT, with causes if there is any.
365 		 */
366 		if (err_chunk) {
367 			packet = sctp_abort_pkt_new(net, ep, asoc, arg,
368 					(__u8 *)(err_chunk->chunk_hdr) +
369 					sizeof(sctp_chunkhdr_t),
370 					ntohs(err_chunk->chunk_hdr->length) -
371 					sizeof(sctp_chunkhdr_t));
372 
373 			sctp_chunk_free(err_chunk);
374 
375 			if (packet) {
376 				sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
377 						SCTP_PACKET(packet));
378 				SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
379 				return SCTP_DISPOSITION_CONSUME;
380 			} else {
381 				return SCTP_DISPOSITION_NOMEM;
382 			}
383 		} else {
384 			return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg,
385 						    commands);
386 		}
387 	}
388 
389 	/* Grab the INIT header.  */
390 	chunk->subh.init_hdr = (sctp_inithdr_t *)chunk->skb->data;
391 
392 	/* Tag the variable length parameters.  */
393 	chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(sctp_inithdr_t));
394 
395 	new_asoc = sctp_make_temp_asoc(ep, chunk, GFP_ATOMIC);
396 	if (!new_asoc)
397 		goto nomem;
398 
399 	if (sctp_assoc_set_bind_addr_from_ep(new_asoc,
400 					     sctp_scope(sctp_source(chunk)),
401 					     GFP_ATOMIC) < 0)
402 		goto nomem_init;
403 
404 	/* The call, sctp_process_init(), can fail on memory allocation.  */
405 	if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk),
406 			       (sctp_init_chunk_t *)chunk->chunk_hdr,
407 			       GFP_ATOMIC))
408 		goto nomem_init;
409 
410 	/* B) "Z" shall respond immediately with an INIT ACK chunk.  */
411 
412 	/* If there are errors need to be reported for unknown parameters,
413 	 * make sure to reserve enough room in the INIT ACK for them.
414 	 */
415 	len = 0;
416 	if (err_chunk)
417 		len = ntohs(err_chunk->chunk_hdr->length) -
418 			sizeof(sctp_chunkhdr_t);
419 
420 	repl = sctp_make_init_ack(new_asoc, chunk, GFP_ATOMIC, len);
421 	if (!repl)
422 		goto nomem_init;
423 
424 	/* If there are errors need to be reported for unknown parameters,
425 	 * include them in the outgoing INIT ACK as "Unrecognized parameter"
426 	 * parameter.
427 	 */
428 	if (err_chunk) {
429 		/* Get the "Unrecognized parameter" parameter(s) out of the
430 		 * ERROR chunk generated by sctp_verify_init(). Since the
431 		 * error cause code for "unknown parameter" and the
432 		 * "Unrecognized parameter" type is the same, we can
433 		 * construct the parameters in INIT ACK by copying the
434 		 * ERROR causes over.
435 		 */
436 		unk_param = (sctp_unrecognized_param_t *)
437 			    ((__u8 *)(err_chunk->chunk_hdr) +
438 			    sizeof(sctp_chunkhdr_t));
439 		/* Replace the cause code with the "Unrecognized parameter"
440 		 * parameter type.
441 		 */
442 		sctp_addto_chunk(repl, len, unk_param);
443 		sctp_chunk_free(err_chunk);
444 	}
445 
446 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc));
447 
448 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
449 
450 	/*
451 	 * Note:  After sending out INIT ACK with the State Cookie parameter,
452 	 * "Z" MUST NOT allocate any resources, nor keep any states for the
453 	 * new association.  Otherwise, "Z" will be vulnerable to resource
454 	 * attacks.
455 	 */
456 	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
457 
458 	return SCTP_DISPOSITION_DELETE_TCB;
459 
460 nomem_init:
461 	sctp_association_free(new_asoc);
462 nomem:
463 	if (err_chunk)
464 		sctp_chunk_free(err_chunk);
465 	return SCTP_DISPOSITION_NOMEM;
466 }
467 
468 /*
469  * Respond to a normal INIT ACK chunk.
470  * We are the side that is initiating the association.
471  *
472  * Section: 5.1 Normal Establishment of an Association, C
473  * C) Upon reception of the INIT ACK from "Z", "A" shall stop the T1-init
474  *    timer and leave COOKIE-WAIT state. "A" shall then send the State
475  *    Cookie received in the INIT ACK chunk in a COOKIE ECHO chunk, start
476  *    the T1-cookie timer, and enter the COOKIE-ECHOED state.
477  *
478  *    Note: The COOKIE ECHO chunk can be bundled with any pending outbound
479  *    DATA chunks, but it MUST be the first chunk in the packet and
480  *    until the COOKIE ACK is returned the sender MUST NOT send any
481  *    other packets to the peer.
482  *
483  * Verification Tag: 3.3.3
484  *   If the value of the Initiate Tag in a received INIT ACK chunk is
485  *   found to be 0, the receiver MUST treat it as an error and close the
486  *   association by transmitting an ABORT.
487  *
488  * Inputs
489  * (endpoint, asoc, chunk)
490  *
491  * Outputs
492  * (asoc, reply_msg, msg_up, timers, counters)
493  *
494  * The return value is the disposition of the chunk.
495  */
496 sctp_disposition_t sctp_sf_do_5_1C_ack(struct net *net,
497 				       const struct sctp_endpoint *ep,
498 				       const struct sctp_association *asoc,
499 				       const sctp_subtype_t type,
500 				       void *arg,
501 				       sctp_cmd_seq_t *commands)
502 {
503 	struct sctp_chunk *chunk = arg;
504 	sctp_init_chunk_t *initchunk;
505 	struct sctp_chunk *err_chunk;
506 	struct sctp_packet *packet;
507 
508 	if (!sctp_vtag_verify(chunk, asoc))
509 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
510 
511 	/* 6.10 Bundling
512 	 * An endpoint MUST NOT bundle INIT, INIT ACK or
513 	 * SHUTDOWN COMPLETE with any other chunks.
514 	 */
515 	if (!chunk->singleton)
516 		return sctp_sf_violation_chunk(net, ep, asoc, type, arg, commands);
517 
518 	/* Make sure that the INIT-ACK chunk has a valid length */
519 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_initack_chunk_t)))
520 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
521 						  commands);
522 	/* Grab the INIT header.  */
523 	chunk->subh.init_hdr = (sctp_inithdr_t *) chunk->skb->data;
524 
525 	/* Verify the INIT chunk before processing it. */
526 	err_chunk = NULL;
527 	if (!sctp_verify_init(net, asoc, chunk->chunk_hdr->type,
528 			      (sctp_init_chunk_t *)chunk->chunk_hdr, chunk,
529 			      &err_chunk)) {
530 
531 		sctp_error_t error = SCTP_ERROR_NO_RESOURCE;
532 
533 		/* This chunk contains fatal error. It is to be discarded.
534 		 * Send an ABORT, with causes.  If there are no causes,
535 		 * then there wasn't enough memory.  Just terminate
536 		 * the association.
537 		 */
538 		if (err_chunk) {
539 			packet = sctp_abort_pkt_new(net, ep, asoc, arg,
540 					(__u8 *)(err_chunk->chunk_hdr) +
541 					sizeof(sctp_chunkhdr_t),
542 					ntohs(err_chunk->chunk_hdr->length) -
543 					sizeof(sctp_chunkhdr_t));
544 
545 			sctp_chunk_free(err_chunk);
546 
547 			if (packet) {
548 				sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
549 						SCTP_PACKET(packet));
550 				SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
551 				error = SCTP_ERROR_INV_PARAM;
552 			}
553 		}
554 
555 		/* SCTP-AUTH, Section 6.3:
556 		 *    It should be noted that if the receiver wants to tear
557 		 *    down an association in an authenticated way only, the
558 		 *    handling of malformed packets should not result in
559 		 *    tearing down the association.
560 		 *
561 		 * This means that if we only want to abort associations
562 		 * in an authenticated way (i.e AUTH+ABORT), then we
563 		 * can't destroy this association just because the packet
564 		 * was malformed.
565 		 */
566 		if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc))
567 			return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
568 
569 		SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
570 		return sctp_stop_t1_and_abort(net, commands, error, ECONNREFUSED,
571 						asoc, chunk->transport);
572 	}
573 
574 	/* Tag the variable length parameters.  Note that we never
575 	 * convert the parameters in an INIT chunk.
576 	 */
577 	chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(sctp_inithdr_t));
578 
579 	initchunk = (sctp_init_chunk_t *) chunk->chunk_hdr;
580 
581 	sctp_add_cmd_sf(commands, SCTP_CMD_PEER_INIT,
582 			SCTP_PEER_INIT(initchunk));
583 
584 	/* Reset init error count upon receipt of INIT-ACK.  */
585 	sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_RESET, SCTP_NULL());
586 
587 	/* 5.1 C) "A" shall stop the T1-init timer and leave
588 	 * COOKIE-WAIT state.  "A" shall then ... start the T1-cookie
589 	 * timer, and enter the COOKIE-ECHOED state.
590 	 */
591 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
592 			SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
593 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
594 			SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
595 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
596 			SCTP_STATE(SCTP_STATE_COOKIE_ECHOED));
597 
598 	/* SCTP-AUTH: genereate the assocition shared keys so that
599 	 * we can potentially signe the COOKIE-ECHO.
600 	 */
601 	sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_SHKEY, SCTP_NULL());
602 
603 	/* 5.1 C) "A" shall then send the State Cookie received in the
604 	 * INIT ACK chunk in a COOKIE ECHO chunk, ...
605 	 */
606 	/* If there is any errors to report, send the ERROR chunk generated
607 	 * for unknown parameters as well.
608 	 */
609 	sctp_add_cmd_sf(commands, SCTP_CMD_GEN_COOKIE_ECHO,
610 			SCTP_CHUNK(err_chunk));
611 
612 	return SCTP_DISPOSITION_CONSUME;
613 }
614 
615 /*
616  * Respond to a normal COOKIE ECHO chunk.
617  * We are the side that is being asked for an association.
618  *
619  * Section: 5.1 Normal Establishment of an Association, D
620  * D) Upon reception of the COOKIE ECHO chunk, Endpoint "Z" will reply
621  *    with a COOKIE ACK chunk after building a TCB and moving to
622  *    the ESTABLISHED state. A COOKIE ACK chunk may be bundled with
623  *    any pending DATA chunks (and/or SACK chunks), but the COOKIE ACK
624  *    chunk MUST be the first chunk in the packet.
625  *
626  *   IMPLEMENTATION NOTE: An implementation may choose to send the
627  *   Communication Up notification to the SCTP user upon reception
628  *   of a valid COOKIE ECHO chunk.
629  *
630  * Verification Tag: 8.5.1 Exceptions in Verification Tag Rules
631  * D) Rules for packet carrying a COOKIE ECHO
632  *
633  * - When sending a COOKIE ECHO, the endpoint MUST use the value of the
634  *   Initial Tag received in the INIT ACK.
635  *
636  * - The receiver of a COOKIE ECHO follows the procedures in Section 5.
637  *
638  * Inputs
639  * (endpoint, asoc, chunk)
640  *
641  * Outputs
642  * (asoc, reply_msg, msg_up, timers, counters)
643  *
644  * The return value is the disposition of the chunk.
645  */
646 sctp_disposition_t sctp_sf_do_5_1D_ce(struct net *net,
647 				      const struct sctp_endpoint *ep,
648 				      const struct sctp_association *asoc,
649 				      const sctp_subtype_t type, void *arg,
650 				      sctp_cmd_seq_t *commands)
651 {
652 	struct sctp_chunk *chunk = arg;
653 	struct sctp_association *new_asoc;
654 	sctp_init_chunk_t *peer_init;
655 	struct sctp_chunk *repl;
656 	struct sctp_ulpevent *ev, *ai_ev = NULL;
657 	int error = 0;
658 	struct sctp_chunk *err_chk_p;
659 	struct sock *sk;
660 
661 	/* If the packet is an OOTB packet which is temporarily on the
662 	 * control endpoint, respond with an ABORT.
663 	 */
664 	if (ep == sctp_sk(net->sctp.ctl_sock)->ep) {
665 		SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
666 		return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
667 	}
668 
669 	/* Make sure that the COOKIE_ECHO chunk has a valid length.
670 	 * In this case, we check that we have enough for at least a
671 	 * chunk header.  More detailed verification is done
672 	 * in sctp_unpack_cookie().
673 	 */
674 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
675 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
676 
677 	/* If the endpoint is not listening or if the number of associations
678 	 * on the TCP-style socket exceed the max backlog, respond with an
679 	 * ABORT.
680 	 */
681 	sk = ep->base.sk;
682 	if (!sctp_sstate(sk, LISTENING) ||
683 	    (sctp_style(sk, TCP) && sk_acceptq_is_full(sk)))
684 		return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
685 
686 	/* "Decode" the chunk.  We have no optional parameters so we
687 	 * are in good shape.
688 	 */
689 	chunk->subh.cookie_hdr =
690 		(struct sctp_signed_cookie *)chunk->skb->data;
691 	if (!pskb_pull(chunk->skb, ntohs(chunk->chunk_hdr->length) -
692 					 sizeof(sctp_chunkhdr_t)))
693 		goto nomem;
694 
695 	/* 5.1 D) Upon reception of the COOKIE ECHO chunk, Endpoint
696 	 * "Z" will reply with a COOKIE ACK chunk after building a TCB
697 	 * and moving to the ESTABLISHED state.
698 	 */
699 	new_asoc = sctp_unpack_cookie(ep, asoc, chunk, GFP_ATOMIC, &error,
700 				      &err_chk_p);
701 
702 	/* FIXME:
703 	 * If the re-build failed, what is the proper error path
704 	 * from here?
705 	 *
706 	 * [We should abort the association. --piggy]
707 	 */
708 	if (!new_asoc) {
709 		/* FIXME: Several errors are possible.  A bad cookie should
710 		 * be silently discarded, but think about logging it too.
711 		 */
712 		switch (error) {
713 		case -SCTP_IERROR_NOMEM:
714 			goto nomem;
715 
716 		case -SCTP_IERROR_STALE_COOKIE:
717 			sctp_send_stale_cookie_err(net, ep, asoc, chunk, commands,
718 						   err_chk_p);
719 			return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
720 
721 		case -SCTP_IERROR_BAD_SIG:
722 		default:
723 			return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
724 		}
725 	}
726 
727 
728 	/* Delay state machine commands until later.
729 	 *
730 	 * Re-build the bind address for the association is done in
731 	 * the sctp_unpack_cookie() already.
732 	 */
733 	/* This is a brand-new association, so these are not yet side
734 	 * effects--it is safe to run them here.
735 	 */
736 	peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
737 
738 	if (!sctp_process_init(new_asoc, chunk,
739 			       &chunk->subh.cookie_hdr->c.peer_addr,
740 			       peer_init, GFP_ATOMIC))
741 		goto nomem_init;
742 
743 	/* SCTP-AUTH:  Now that we've populate required fields in
744 	 * sctp_process_init, set up the assocaition shared keys as
745 	 * necessary so that we can potentially authenticate the ACK
746 	 */
747 	error = sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC);
748 	if (error)
749 		goto nomem_init;
750 
751 	/* SCTP-AUTH:  auth_chunk pointer is only set when the cookie-echo
752 	 * is supposed to be authenticated and we have to do delayed
753 	 * authentication.  We've just recreated the association using
754 	 * the information in the cookie and now it's much easier to
755 	 * do the authentication.
756 	 */
757 	if (chunk->auth_chunk) {
758 		struct sctp_chunk auth;
759 		sctp_ierror_t ret;
760 
761 		/* Make sure that we and the peer are AUTH capable */
762 		if (!net->sctp.auth_enable || !new_asoc->peer.auth_capable) {
763 			sctp_association_free(new_asoc);
764 			return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
765 		}
766 
767 		/* set-up our fake chunk so that we can process it */
768 		auth.skb = chunk->auth_chunk;
769 		auth.asoc = chunk->asoc;
770 		auth.sctp_hdr = chunk->sctp_hdr;
771 		auth.chunk_hdr = (sctp_chunkhdr_t *)skb_push(chunk->auth_chunk,
772 					    sizeof(sctp_chunkhdr_t));
773 		skb_pull(chunk->auth_chunk, sizeof(sctp_chunkhdr_t));
774 		auth.transport = chunk->transport;
775 
776 		ret = sctp_sf_authenticate(net, ep, new_asoc, type, &auth);
777 		if (ret != SCTP_IERROR_NO_ERROR) {
778 			sctp_association_free(new_asoc);
779 			return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
780 		}
781 	}
782 
783 	repl = sctp_make_cookie_ack(new_asoc, chunk);
784 	if (!repl)
785 		goto nomem_init;
786 
787 	/* RFC 2960 5.1 Normal Establishment of an Association
788 	 *
789 	 * D) IMPLEMENTATION NOTE: An implementation may choose to
790 	 * send the Communication Up notification to the SCTP user
791 	 * upon reception of a valid COOKIE ECHO chunk.
792 	 */
793 	ev = sctp_ulpevent_make_assoc_change(new_asoc, 0, SCTP_COMM_UP, 0,
794 					     new_asoc->c.sinit_num_ostreams,
795 					     new_asoc->c.sinit_max_instreams,
796 					     NULL, GFP_ATOMIC);
797 	if (!ev)
798 		goto nomem_ev;
799 
800 	/* Sockets API Draft Section 5.3.1.6
801 	 * When a peer sends a Adaptation Layer Indication parameter , SCTP
802 	 * delivers this notification to inform the application that of the
803 	 * peers requested adaptation layer.
804 	 */
805 	if (new_asoc->peer.adaptation_ind) {
806 		ai_ev = sctp_ulpevent_make_adaptation_indication(new_asoc,
807 							    GFP_ATOMIC);
808 		if (!ai_ev)
809 			goto nomem_aiev;
810 	}
811 
812 	/* Add all the state machine commands now since we've created
813 	 * everything.  This way we don't introduce memory corruptions
814 	 * during side-effect processing and correclty count established
815 	 * associations.
816 	 */
817 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc));
818 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
819 			SCTP_STATE(SCTP_STATE_ESTABLISHED));
820 	SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
821 	SCTP_INC_STATS(net, SCTP_MIB_PASSIVEESTABS);
822 	sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL());
823 
824 	if (new_asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
825 		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
826 				SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
827 
828 	/* This will send the COOKIE ACK */
829 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
830 
831 	/* Queue the ASSOC_CHANGE event */
832 	sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
833 
834 	/* Send up the Adaptation Layer Indication event */
835 	if (ai_ev)
836 		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
837 				SCTP_ULPEVENT(ai_ev));
838 
839 	return SCTP_DISPOSITION_CONSUME;
840 
841 nomem_aiev:
842 	sctp_ulpevent_free(ev);
843 nomem_ev:
844 	sctp_chunk_free(repl);
845 nomem_init:
846 	sctp_association_free(new_asoc);
847 nomem:
848 	return SCTP_DISPOSITION_NOMEM;
849 }
850 
851 /*
852  * Respond to a normal COOKIE ACK chunk.
853  * We are the side that is being asked for an association.
854  *
855  * RFC 2960 5.1 Normal Establishment of an Association
856  *
857  * E) Upon reception of the COOKIE ACK, endpoint "A" will move from the
858  *    COOKIE-ECHOED state to the ESTABLISHED state, stopping the T1-cookie
859  *    timer. It may also notify its ULP about the successful
860  *    establishment of the association with a Communication Up
861  *    notification (see Section 10).
862  *
863  * Verification Tag:
864  * Inputs
865  * (endpoint, asoc, chunk)
866  *
867  * Outputs
868  * (asoc, reply_msg, msg_up, timers, counters)
869  *
870  * The return value is the disposition of the chunk.
871  */
872 sctp_disposition_t sctp_sf_do_5_1E_ca(struct net *net,
873 				      const struct sctp_endpoint *ep,
874 				      const struct sctp_association *asoc,
875 				      const sctp_subtype_t type, void *arg,
876 				      sctp_cmd_seq_t *commands)
877 {
878 	struct sctp_chunk *chunk = arg;
879 	struct sctp_ulpevent *ev;
880 
881 	if (!sctp_vtag_verify(chunk, asoc))
882 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
883 
884 	/* Verify that the chunk length for the COOKIE-ACK is OK.
885 	 * If we don't do this, any bundled chunks may be junked.
886 	 */
887 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
888 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
889 						  commands);
890 
891 	/* Reset init error count upon receipt of COOKIE-ACK,
892 	 * to avoid problems with the managemement of this
893 	 * counter in stale cookie situations when a transition back
894 	 * from the COOKIE-ECHOED state to the COOKIE-WAIT
895 	 * state is performed.
896 	 */
897 	sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_RESET, SCTP_NULL());
898 
899 	/* RFC 2960 5.1 Normal Establishment of an Association
900 	 *
901 	 * E) Upon reception of the COOKIE ACK, endpoint "A" will move
902 	 * from the COOKIE-ECHOED state to the ESTABLISHED state,
903 	 * stopping the T1-cookie timer.
904 	 */
905 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
906 			SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
907 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
908 			SCTP_STATE(SCTP_STATE_ESTABLISHED));
909 	SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
910 	SCTP_INC_STATS(net, SCTP_MIB_ACTIVEESTABS);
911 	sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL());
912 	if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
913 		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
914 				SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
915 
916 	/* It may also notify its ULP about the successful
917 	 * establishment of the association with a Communication Up
918 	 * notification (see Section 10).
919 	 */
920 	ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_UP,
921 					     0, asoc->c.sinit_num_ostreams,
922 					     asoc->c.sinit_max_instreams,
923 					     NULL, GFP_ATOMIC);
924 
925 	if (!ev)
926 		goto nomem;
927 
928 	sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
929 
930 	/* Sockets API Draft Section 5.3.1.6
931 	 * When a peer sends a Adaptation Layer Indication parameter , SCTP
932 	 * delivers this notification to inform the application that of the
933 	 * peers requested adaptation layer.
934 	 */
935 	if (asoc->peer.adaptation_ind) {
936 		ev = sctp_ulpevent_make_adaptation_indication(asoc, GFP_ATOMIC);
937 		if (!ev)
938 			goto nomem;
939 
940 		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
941 				SCTP_ULPEVENT(ev));
942 	}
943 
944 	return SCTP_DISPOSITION_CONSUME;
945 nomem:
946 	return SCTP_DISPOSITION_NOMEM;
947 }
948 
949 /* Generate and sendout a heartbeat packet.  */
950 static sctp_disposition_t sctp_sf_heartbeat(const struct sctp_endpoint *ep,
951 					    const struct sctp_association *asoc,
952 					    const sctp_subtype_t type,
953 					    void *arg,
954 					    sctp_cmd_seq_t *commands)
955 {
956 	struct sctp_transport *transport = (struct sctp_transport *) arg;
957 	struct sctp_chunk *reply;
958 
959 	/* Send a heartbeat to our peer.  */
960 	reply = sctp_make_heartbeat(asoc, transport);
961 	if (!reply)
962 		return SCTP_DISPOSITION_NOMEM;
963 
964 	/* Set rto_pending indicating that an RTT measurement
965 	 * is started with this heartbeat chunk.
966 	 */
967 	sctp_add_cmd_sf(commands, SCTP_CMD_RTO_PENDING,
968 			SCTP_TRANSPORT(transport));
969 
970 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
971 	return SCTP_DISPOSITION_CONSUME;
972 }
973 
974 /* Generate a HEARTBEAT packet on the given transport.  */
975 sctp_disposition_t sctp_sf_sendbeat_8_3(struct net *net,
976 					const struct sctp_endpoint *ep,
977 					const struct sctp_association *asoc,
978 					const sctp_subtype_t type,
979 					void *arg,
980 					sctp_cmd_seq_t *commands)
981 {
982 	struct sctp_transport *transport = (struct sctp_transport *) arg;
983 
984 	if (asoc->overall_error_count >= asoc->max_retrans) {
985 		sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
986 				SCTP_ERROR(ETIMEDOUT));
987 		/* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */
988 		sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
989 				SCTP_PERR(SCTP_ERROR_NO_ERROR));
990 		SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
991 		SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
992 		return SCTP_DISPOSITION_DELETE_TCB;
993 	}
994 
995 	/* Section 3.3.5.
996 	 * The Sender-specific Heartbeat Info field should normally include
997 	 * information about the sender's current time when this HEARTBEAT
998 	 * chunk is sent and the destination transport address to which this
999 	 * HEARTBEAT is sent (see Section 8.3).
1000 	 */
1001 
1002 	if (transport->param_flags & SPP_HB_ENABLE) {
1003 		if (SCTP_DISPOSITION_NOMEM ==
1004 				sctp_sf_heartbeat(ep, asoc, type, arg,
1005 						  commands))
1006 			return SCTP_DISPOSITION_NOMEM;
1007 
1008 		/* Set transport error counter and association error counter
1009 		 * when sending heartbeat.
1010 		 */
1011 		sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_HB_SENT,
1012 				SCTP_TRANSPORT(transport));
1013 	}
1014 	sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_IDLE,
1015 			SCTP_TRANSPORT(transport));
1016 	sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMER_UPDATE,
1017 			SCTP_TRANSPORT(transport));
1018 
1019 	return SCTP_DISPOSITION_CONSUME;
1020 }
1021 
1022 /*
1023  * Process an heartbeat request.
1024  *
1025  * Section: 8.3 Path Heartbeat
1026  * The receiver of the HEARTBEAT should immediately respond with a
1027  * HEARTBEAT ACK that contains the Heartbeat Information field copied
1028  * from the received HEARTBEAT chunk.
1029  *
1030  * Verification Tag:  8.5 Verification Tag [Normal verification]
1031  * When receiving an SCTP packet, the endpoint MUST ensure that the
1032  * value in the Verification Tag field of the received SCTP packet
1033  * matches its own Tag. If the received Verification Tag value does not
1034  * match the receiver's own tag value, the receiver shall silently
1035  * discard the packet and shall not process it any further except for
1036  * those cases listed in Section 8.5.1 below.
1037  *
1038  * Inputs
1039  * (endpoint, asoc, chunk)
1040  *
1041  * Outputs
1042  * (asoc, reply_msg, msg_up, timers, counters)
1043  *
1044  * The return value is the disposition of the chunk.
1045  */
1046 sctp_disposition_t sctp_sf_beat_8_3(struct net *net,
1047 				    const struct sctp_endpoint *ep,
1048 				    const struct sctp_association *asoc,
1049 				    const sctp_subtype_t type,
1050 				    void *arg,
1051 				    sctp_cmd_seq_t *commands)
1052 {
1053 	sctp_paramhdr_t *param_hdr;
1054 	struct sctp_chunk *chunk = arg;
1055 	struct sctp_chunk *reply;
1056 	size_t paylen = 0;
1057 
1058 	if (!sctp_vtag_verify(chunk, asoc))
1059 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
1060 
1061 	/* Make sure that the HEARTBEAT chunk has a valid length. */
1062 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_heartbeat_chunk_t)))
1063 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
1064 						  commands);
1065 
1066 	/* 8.3 The receiver of the HEARTBEAT should immediately
1067 	 * respond with a HEARTBEAT ACK that contains the Heartbeat
1068 	 * Information field copied from the received HEARTBEAT chunk.
1069 	 */
1070 	chunk->subh.hb_hdr = (sctp_heartbeathdr_t *) chunk->skb->data;
1071 	param_hdr = (sctp_paramhdr_t *) chunk->subh.hb_hdr;
1072 	paylen = ntohs(chunk->chunk_hdr->length) - sizeof(sctp_chunkhdr_t);
1073 
1074 	if (ntohs(param_hdr->length) > paylen)
1075 		return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
1076 						  param_hdr, commands);
1077 
1078 	if (!pskb_pull(chunk->skb, paylen))
1079 		goto nomem;
1080 
1081 	reply = sctp_make_heartbeat_ack(asoc, chunk, param_hdr, paylen);
1082 	if (!reply)
1083 		goto nomem;
1084 
1085 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
1086 	return SCTP_DISPOSITION_CONSUME;
1087 
1088 nomem:
1089 	return SCTP_DISPOSITION_NOMEM;
1090 }
1091 
1092 /*
1093  * Process the returning HEARTBEAT ACK.
1094  *
1095  * Section: 8.3 Path Heartbeat
1096  * Upon the receipt of the HEARTBEAT ACK, the sender of the HEARTBEAT
1097  * should clear the error counter of the destination transport
1098  * address to which the HEARTBEAT was sent, and mark the destination
1099  * transport address as active if it is not so marked. The endpoint may
1100  * optionally report to the upper layer when an inactive destination
1101  * address is marked as active due to the reception of the latest
1102  * HEARTBEAT ACK. The receiver of the HEARTBEAT ACK must also
1103  * clear the association overall error count as well (as defined
1104  * in section 8.1).
1105  *
1106  * The receiver of the HEARTBEAT ACK should also perform an RTT
1107  * measurement for that destination transport address using the time
1108  * value carried in the HEARTBEAT ACK chunk.
1109  *
1110  * Verification Tag:  8.5 Verification Tag [Normal verification]
1111  *
1112  * Inputs
1113  * (endpoint, asoc, chunk)
1114  *
1115  * Outputs
1116  * (asoc, reply_msg, msg_up, timers, counters)
1117  *
1118  * The return value is the disposition of the chunk.
1119  */
1120 sctp_disposition_t sctp_sf_backbeat_8_3(struct net *net,
1121 					const struct sctp_endpoint *ep,
1122 					const struct sctp_association *asoc,
1123 					const sctp_subtype_t type,
1124 					void *arg,
1125 					sctp_cmd_seq_t *commands)
1126 {
1127 	struct sctp_chunk *chunk = arg;
1128 	union sctp_addr from_addr;
1129 	struct sctp_transport *link;
1130 	sctp_sender_hb_info_t *hbinfo;
1131 	unsigned long max_interval;
1132 
1133 	if (!sctp_vtag_verify(chunk, asoc))
1134 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
1135 
1136 	/* Make sure that the HEARTBEAT-ACK chunk has a valid length.  */
1137 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t) +
1138 					    sizeof(sctp_sender_hb_info_t)))
1139 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
1140 						  commands);
1141 
1142 	hbinfo = (sctp_sender_hb_info_t *) chunk->skb->data;
1143 	/* Make sure that the length of the parameter is what we expect */
1144 	if (ntohs(hbinfo->param_hdr.length) !=
1145 				    sizeof(sctp_sender_hb_info_t)) {
1146 		return SCTP_DISPOSITION_DISCARD;
1147 	}
1148 
1149 	from_addr = hbinfo->daddr;
1150 	link = sctp_assoc_lookup_paddr(asoc, &from_addr);
1151 
1152 	/* This should never happen, but lets log it if so.  */
1153 	if (unlikely(!link)) {
1154 		if (from_addr.sa.sa_family == AF_INET6) {
1155 			net_warn_ratelimited("%s association %p could not find address %pI6\n",
1156 					     __func__,
1157 					     asoc,
1158 					     &from_addr.v6.sin6_addr);
1159 		} else {
1160 			net_warn_ratelimited("%s association %p could not find address %pI4\n",
1161 					     __func__,
1162 					     asoc,
1163 					     &from_addr.v4.sin_addr.s_addr);
1164 		}
1165 		return SCTP_DISPOSITION_DISCARD;
1166 	}
1167 
1168 	/* Validate the 64-bit random nonce. */
1169 	if (hbinfo->hb_nonce != link->hb_nonce)
1170 		return SCTP_DISPOSITION_DISCARD;
1171 
1172 	max_interval = link->hbinterval + link->rto;
1173 
1174 	/* Check if the timestamp looks valid.  */
1175 	if (time_after(hbinfo->sent_at, jiffies) ||
1176 	    time_after(jiffies, hbinfo->sent_at + max_interval)) {
1177 		pr_debug("%s: HEARTBEAT ACK with invalid timestamp received "
1178 			 "for transport:%p\n", __func__, link);
1179 
1180 		return SCTP_DISPOSITION_DISCARD;
1181 	}
1182 
1183 	/* 8.3 Upon the receipt of the HEARTBEAT ACK, the sender of
1184 	 * the HEARTBEAT should clear the error counter of the
1185 	 * destination transport address to which the HEARTBEAT was
1186 	 * sent and mark the destination transport address as active if
1187 	 * it is not so marked.
1188 	 */
1189 	sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_ON, SCTP_TRANSPORT(link));
1190 
1191 	return SCTP_DISPOSITION_CONSUME;
1192 }
1193 
1194 /* Helper function to send out an abort for the restart
1195  * condition.
1196  */
1197 static int sctp_sf_send_restart_abort(struct net *net, union sctp_addr *ssa,
1198 				      struct sctp_chunk *init,
1199 				      sctp_cmd_seq_t *commands)
1200 {
1201 	int len;
1202 	struct sctp_packet *pkt;
1203 	union sctp_addr_param *addrparm;
1204 	struct sctp_errhdr *errhdr;
1205 	struct sctp_endpoint *ep;
1206 	char buffer[sizeof(struct sctp_errhdr)+sizeof(union sctp_addr_param)];
1207 	struct sctp_af *af = sctp_get_af_specific(ssa->v4.sin_family);
1208 
1209 	/* Build the error on the stack.   We are way to malloc crazy
1210 	 * throughout the code today.
1211 	 */
1212 	errhdr = (struct sctp_errhdr *)buffer;
1213 	addrparm = (union sctp_addr_param *)errhdr->variable;
1214 
1215 	/* Copy into a parm format. */
1216 	len = af->to_addr_param(ssa, addrparm);
1217 	len += sizeof(sctp_errhdr_t);
1218 
1219 	errhdr->cause = SCTP_ERROR_RESTART;
1220 	errhdr->length = htons(len);
1221 
1222 	/* Assign to the control socket. */
1223 	ep = sctp_sk(net->sctp.ctl_sock)->ep;
1224 
1225 	/* Association is NULL since this may be a restart attack and we
1226 	 * want to send back the attacker's vtag.
1227 	 */
1228 	pkt = sctp_abort_pkt_new(net, ep, NULL, init, errhdr, len);
1229 
1230 	if (!pkt)
1231 		goto out;
1232 	sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(pkt));
1233 
1234 	SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
1235 
1236 	/* Discard the rest of the inbound packet. */
1237 	sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
1238 
1239 out:
1240 	/* Even if there is no memory, treat as a failure so
1241 	 * the packet will get dropped.
1242 	 */
1243 	return 0;
1244 }
1245 
1246 static bool list_has_sctp_addr(const struct list_head *list,
1247 			       union sctp_addr *ipaddr)
1248 {
1249 	struct sctp_transport *addr;
1250 
1251 	list_for_each_entry(addr, list, transports) {
1252 		if (sctp_cmp_addr_exact(ipaddr, &addr->ipaddr))
1253 			return true;
1254 	}
1255 
1256 	return false;
1257 }
1258 /* A restart is occurring, check to make sure no new addresses
1259  * are being added as we may be under a takeover attack.
1260  */
1261 static int sctp_sf_check_restart_addrs(const struct sctp_association *new_asoc,
1262 				       const struct sctp_association *asoc,
1263 				       struct sctp_chunk *init,
1264 				       sctp_cmd_seq_t *commands)
1265 {
1266 	struct net *net = sock_net(new_asoc->base.sk);
1267 	struct sctp_transport *new_addr;
1268 	int ret = 1;
1269 
1270 	/* Implementor's Guide - Section 5.2.2
1271 	 * ...
1272 	 * Before responding the endpoint MUST check to see if the
1273 	 * unexpected INIT adds new addresses to the association. If new
1274 	 * addresses are added to the association, the endpoint MUST respond
1275 	 * with an ABORT..
1276 	 */
1277 
1278 	/* Search through all current addresses and make sure
1279 	 * we aren't adding any new ones.
1280 	 */
1281 	list_for_each_entry(new_addr, &new_asoc->peer.transport_addr_list,
1282 			    transports) {
1283 		if (!list_has_sctp_addr(&asoc->peer.transport_addr_list,
1284 					&new_addr->ipaddr)) {
1285 			sctp_sf_send_restart_abort(net, &new_addr->ipaddr, init,
1286 						   commands);
1287 			ret = 0;
1288 			break;
1289 		}
1290 	}
1291 
1292 	/* Return success if all addresses were found. */
1293 	return ret;
1294 }
1295 
1296 /* Populate the verification/tie tags based on overlapping INIT
1297  * scenario.
1298  *
1299  * Note: Do not use in CLOSED or SHUTDOWN-ACK-SENT state.
1300  */
1301 static void sctp_tietags_populate(struct sctp_association *new_asoc,
1302 				  const struct sctp_association *asoc)
1303 {
1304 	switch (asoc->state) {
1305 
1306 	/* 5.2.1 INIT received in COOKIE-WAIT or COOKIE-ECHOED State */
1307 
1308 	case SCTP_STATE_COOKIE_WAIT:
1309 		new_asoc->c.my_vtag     = asoc->c.my_vtag;
1310 		new_asoc->c.my_ttag     = asoc->c.my_vtag;
1311 		new_asoc->c.peer_ttag   = 0;
1312 		break;
1313 
1314 	case SCTP_STATE_COOKIE_ECHOED:
1315 		new_asoc->c.my_vtag     = asoc->c.my_vtag;
1316 		new_asoc->c.my_ttag     = asoc->c.my_vtag;
1317 		new_asoc->c.peer_ttag   = asoc->c.peer_vtag;
1318 		break;
1319 
1320 	/* 5.2.2 Unexpected INIT in States Other than CLOSED, COOKIE-ECHOED,
1321 	 * COOKIE-WAIT and SHUTDOWN-ACK-SENT
1322 	 */
1323 	default:
1324 		new_asoc->c.my_ttag   = asoc->c.my_vtag;
1325 		new_asoc->c.peer_ttag = asoc->c.peer_vtag;
1326 		break;
1327 	}
1328 
1329 	/* Other parameters for the endpoint SHOULD be copied from the
1330 	 * existing parameters of the association (e.g. number of
1331 	 * outbound streams) into the INIT ACK and cookie.
1332 	 */
1333 	new_asoc->rwnd                  = asoc->rwnd;
1334 	new_asoc->c.sinit_num_ostreams  = asoc->c.sinit_num_ostreams;
1335 	new_asoc->c.sinit_max_instreams = asoc->c.sinit_max_instreams;
1336 	new_asoc->c.initial_tsn         = asoc->c.initial_tsn;
1337 }
1338 
1339 /*
1340  * Compare vtag/tietag values to determine unexpected COOKIE-ECHO
1341  * handling action.
1342  *
1343  * RFC 2960 5.2.4 Handle a COOKIE ECHO when a TCB exists.
1344  *
1345  * Returns value representing action to be taken.   These action values
1346  * correspond to Action/Description values in RFC 2960, Table 2.
1347  */
1348 static char sctp_tietags_compare(struct sctp_association *new_asoc,
1349 				 const struct sctp_association *asoc)
1350 {
1351 	/* In this case, the peer may have restarted.  */
1352 	if ((asoc->c.my_vtag != new_asoc->c.my_vtag) &&
1353 	    (asoc->c.peer_vtag != new_asoc->c.peer_vtag) &&
1354 	    (asoc->c.my_vtag == new_asoc->c.my_ttag) &&
1355 	    (asoc->c.peer_vtag == new_asoc->c.peer_ttag))
1356 		return 'A';
1357 
1358 	/* Collision case B. */
1359 	if ((asoc->c.my_vtag == new_asoc->c.my_vtag) &&
1360 	    ((asoc->c.peer_vtag != new_asoc->c.peer_vtag) ||
1361 	     (0 == asoc->c.peer_vtag))) {
1362 		return 'B';
1363 	}
1364 
1365 	/* Collision case D. */
1366 	if ((asoc->c.my_vtag == new_asoc->c.my_vtag) &&
1367 	    (asoc->c.peer_vtag == new_asoc->c.peer_vtag))
1368 		return 'D';
1369 
1370 	/* Collision case C. */
1371 	if ((asoc->c.my_vtag != new_asoc->c.my_vtag) &&
1372 	    (asoc->c.peer_vtag == new_asoc->c.peer_vtag) &&
1373 	    (0 == new_asoc->c.my_ttag) &&
1374 	    (0 == new_asoc->c.peer_ttag))
1375 		return 'C';
1376 
1377 	/* No match to any of the special cases; discard this packet. */
1378 	return 'E';
1379 }
1380 
1381 /* Common helper routine for both duplicate and simulataneous INIT
1382  * chunk handling.
1383  */
1384 static sctp_disposition_t sctp_sf_do_unexpected_init(
1385 	struct net *net,
1386 	const struct sctp_endpoint *ep,
1387 	const struct sctp_association *asoc,
1388 	const sctp_subtype_t type,
1389 	void *arg, sctp_cmd_seq_t *commands)
1390 {
1391 	sctp_disposition_t retval;
1392 	struct sctp_chunk *chunk = arg;
1393 	struct sctp_chunk *repl;
1394 	struct sctp_association *new_asoc;
1395 	struct sctp_chunk *err_chunk;
1396 	struct sctp_packet *packet;
1397 	sctp_unrecognized_param_t *unk_param;
1398 	int len;
1399 
1400 	/* 6.10 Bundling
1401 	 * An endpoint MUST NOT bundle INIT, INIT ACK or
1402 	 * SHUTDOWN COMPLETE with any other chunks.
1403 	 *
1404 	 * IG Section 2.11.2
1405 	 * Furthermore, we require that the receiver of an INIT chunk MUST
1406 	 * enforce these rules by silently discarding an arriving packet
1407 	 * with an INIT chunk that is bundled with other chunks.
1408 	 */
1409 	if (!chunk->singleton)
1410 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
1411 
1412 	/* 3.1 A packet containing an INIT chunk MUST have a zero Verification
1413 	 * Tag.
1414 	 */
1415 	if (chunk->sctp_hdr->vtag != 0)
1416 		return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
1417 
1418 	/* Make sure that the INIT chunk has a valid length.
1419 	 * In this case, we generate a protocol violation since we have
1420 	 * an association established.
1421 	 */
1422 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_init_chunk_t)))
1423 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
1424 						  commands);
1425 	/* Grab the INIT header.  */
1426 	chunk->subh.init_hdr = (sctp_inithdr_t *) chunk->skb->data;
1427 
1428 	/* Tag the variable length parameters.  */
1429 	chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(sctp_inithdr_t));
1430 
1431 	/* Verify the INIT chunk before processing it. */
1432 	err_chunk = NULL;
1433 	if (!sctp_verify_init(net, asoc, chunk->chunk_hdr->type,
1434 			      (sctp_init_chunk_t *)chunk->chunk_hdr, chunk,
1435 			      &err_chunk)) {
1436 		/* This chunk contains fatal error. It is to be discarded.
1437 		 * Send an ABORT, with causes if there is any.
1438 		 */
1439 		if (err_chunk) {
1440 			packet = sctp_abort_pkt_new(net, ep, asoc, arg,
1441 					(__u8 *)(err_chunk->chunk_hdr) +
1442 					sizeof(sctp_chunkhdr_t),
1443 					ntohs(err_chunk->chunk_hdr->length) -
1444 					sizeof(sctp_chunkhdr_t));
1445 
1446 			if (packet) {
1447 				sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
1448 						SCTP_PACKET(packet));
1449 				SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
1450 				retval = SCTP_DISPOSITION_CONSUME;
1451 			} else {
1452 				retval = SCTP_DISPOSITION_NOMEM;
1453 			}
1454 			goto cleanup;
1455 		} else {
1456 			return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg,
1457 						    commands);
1458 		}
1459 	}
1460 
1461 	/*
1462 	 * Other parameters for the endpoint SHOULD be copied from the
1463 	 * existing parameters of the association (e.g. number of
1464 	 * outbound streams) into the INIT ACK and cookie.
1465 	 * FIXME:  We are copying parameters from the endpoint not the
1466 	 * association.
1467 	 */
1468 	new_asoc = sctp_make_temp_asoc(ep, chunk, GFP_ATOMIC);
1469 	if (!new_asoc)
1470 		goto nomem;
1471 
1472 	if (sctp_assoc_set_bind_addr_from_ep(new_asoc,
1473 				sctp_scope(sctp_source(chunk)), GFP_ATOMIC) < 0)
1474 		goto nomem;
1475 
1476 	/* In the outbound INIT ACK the endpoint MUST copy its current
1477 	 * Verification Tag and Peers Verification tag into a reserved
1478 	 * place (local tie-tag and per tie-tag) within the state cookie.
1479 	 */
1480 	if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk),
1481 			       (sctp_init_chunk_t *)chunk->chunk_hdr,
1482 			       GFP_ATOMIC))
1483 		goto nomem;
1484 
1485 	/* Make sure no new addresses are being added during the
1486 	 * restart.   Do not do this check for COOKIE-WAIT state,
1487 	 * since there are no peer addresses to check against.
1488 	 * Upon return an ABORT will have been sent if needed.
1489 	 */
1490 	if (!sctp_state(asoc, COOKIE_WAIT)) {
1491 		if (!sctp_sf_check_restart_addrs(new_asoc, asoc, chunk,
1492 						 commands)) {
1493 			retval = SCTP_DISPOSITION_CONSUME;
1494 			goto nomem_retval;
1495 		}
1496 	}
1497 
1498 	sctp_tietags_populate(new_asoc, asoc);
1499 
1500 	/* B) "Z" shall respond immediately with an INIT ACK chunk.  */
1501 
1502 	/* If there are errors need to be reported for unknown parameters,
1503 	 * make sure to reserve enough room in the INIT ACK for them.
1504 	 */
1505 	len = 0;
1506 	if (err_chunk) {
1507 		len = ntohs(err_chunk->chunk_hdr->length) -
1508 			sizeof(sctp_chunkhdr_t);
1509 	}
1510 
1511 	repl = sctp_make_init_ack(new_asoc, chunk, GFP_ATOMIC, len);
1512 	if (!repl)
1513 		goto nomem;
1514 
1515 	/* If there are errors need to be reported for unknown parameters,
1516 	 * include them in the outgoing INIT ACK as "Unrecognized parameter"
1517 	 * parameter.
1518 	 */
1519 	if (err_chunk) {
1520 		/* Get the "Unrecognized parameter" parameter(s) out of the
1521 		 * ERROR chunk generated by sctp_verify_init(). Since the
1522 		 * error cause code for "unknown parameter" and the
1523 		 * "Unrecognized parameter" type is the same, we can
1524 		 * construct the parameters in INIT ACK by copying the
1525 		 * ERROR causes over.
1526 		 */
1527 		unk_param = (sctp_unrecognized_param_t *)
1528 			    ((__u8 *)(err_chunk->chunk_hdr) +
1529 			    sizeof(sctp_chunkhdr_t));
1530 		/* Replace the cause code with the "Unrecognized parameter"
1531 		 * parameter type.
1532 		 */
1533 		sctp_addto_chunk(repl, len, unk_param);
1534 	}
1535 
1536 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc));
1537 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
1538 
1539 	/*
1540 	 * Note: After sending out INIT ACK with the State Cookie parameter,
1541 	 * "Z" MUST NOT allocate any resources for this new association.
1542 	 * Otherwise, "Z" will be vulnerable to resource attacks.
1543 	 */
1544 	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
1545 	retval = SCTP_DISPOSITION_CONSUME;
1546 
1547 	return retval;
1548 
1549 nomem:
1550 	retval = SCTP_DISPOSITION_NOMEM;
1551 nomem_retval:
1552 	if (new_asoc)
1553 		sctp_association_free(new_asoc);
1554 cleanup:
1555 	if (err_chunk)
1556 		sctp_chunk_free(err_chunk);
1557 	return retval;
1558 }
1559 
1560 /*
1561  * Handle simultaneous INIT.
1562  * This means we started an INIT and then we got an INIT request from
1563  * our peer.
1564  *
1565  * Section: 5.2.1 INIT received in COOKIE-WAIT or COOKIE-ECHOED State (Item B)
1566  * This usually indicates an initialization collision, i.e., each
1567  * endpoint is attempting, at about the same time, to establish an
1568  * association with the other endpoint.
1569  *
1570  * Upon receipt of an INIT in the COOKIE-WAIT or COOKIE-ECHOED state, an
1571  * endpoint MUST respond with an INIT ACK using the same parameters it
1572  * sent in its original INIT chunk (including its Verification Tag,
1573  * unchanged). These original parameters are combined with those from the
1574  * newly received INIT chunk. The endpoint shall also generate a State
1575  * Cookie with the INIT ACK. The endpoint uses the parameters sent in its
1576  * INIT to calculate the State Cookie.
1577  *
1578  * After that, the endpoint MUST NOT change its state, the T1-init
1579  * timer shall be left running and the corresponding TCB MUST NOT be
1580  * destroyed. The normal procedures for handling State Cookies when
1581  * a TCB exists will resolve the duplicate INITs to a single association.
1582  *
1583  * For an endpoint that is in the COOKIE-ECHOED state it MUST populate
1584  * its Tie-Tags with the Tag information of itself and its peer (see
1585  * section 5.2.2 for a description of the Tie-Tags).
1586  *
1587  * Verification Tag: Not explicit, but an INIT can not have a valid
1588  * verification tag, so we skip the check.
1589  *
1590  * Inputs
1591  * (endpoint, asoc, chunk)
1592  *
1593  * Outputs
1594  * (asoc, reply_msg, msg_up, timers, counters)
1595  *
1596  * The return value is the disposition of the chunk.
1597  */
1598 sctp_disposition_t sctp_sf_do_5_2_1_siminit(struct net *net,
1599 				    const struct sctp_endpoint *ep,
1600 				    const struct sctp_association *asoc,
1601 				    const sctp_subtype_t type,
1602 				    void *arg,
1603 				    sctp_cmd_seq_t *commands)
1604 {
1605 	/* Call helper to do the real work for both simulataneous and
1606 	 * duplicate INIT chunk handling.
1607 	 */
1608 	return sctp_sf_do_unexpected_init(net, ep, asoc, type, arg, commands);
1609 }
1610 
1611 /*
1612  * Handle duplicated INIT messages.  These are usually delayed
1613  * restransmissions.
1614  *
1615  * Section: 5.2.2 Unexpected INIT in States Other than CLOSED,
1616  * COOKIE-ECHOED and COOKIE-WAIT
1617  *
1618  * Unless otherwise stated, upon reception of an unexpected INIT for
1619  * this association, the endpoint shall generate an INIT ACK with a
1620  * State Cookie.  In the outbound INIT ACK the endpoint MUST copy its
1621  * current Verification Tag and peer's Verification Tag into a reserved
1622  * place within the state cookie.  We shall refer to these locations as
1623  * the Peer's-Tie-Tag and the Local-Tie-Tag.  The outbound SCTP packet
1624  * containing this INIT ACK MUST carry a Verification Tag value equal to
1625  * the Initiation Tag found in the unexpected INIT.  And the INIT ACK
1626  * MUST contain a new Initiation Tag (randomly generated see Section
1627  * 5.3.1).  Other parameters for the endpoint SHOULD be copied from the
1628  * existing parameters of the association (e.g. number of outbound
1629  * streams) into the INIT ACK and cookie.
1630  *
1631  * After sending out the INIT ACK, the endpoint shall take no further
1632  * actions, i.e., the existing association, including its current state,
1633  * and the corresponding TCB MUST NOT be changed.
1634  *
1635  * Note: Only when a TCB exists and the association is not in a COOKIE-
1636  * WAIT state are the Tie-Tags populated.  For a normal association INIT
1637  * (i.e. the endpoint is in a COOKIE-WAIT state), the Tie-Tags MUST be
1638  * set to 0 (indicating that no previous TCB existed).  The INIT ACK and
1639  * State Cookie are populated as specified in section 5.2.1.
1640  *
1641  * Verification Tag: Not specified, but an INIT has no way of knowing
1642  * what the verification tag could be, so we ignore it.
1643  *
1644  * Inputs
1645  * (endpoint, asoc, chunk)
1646  *
1647  * Outputs
1648  * (asoc, reply_msg, msg_up, timers, counters)
1649  *
1650  * The return value is the disposition of the chunk.
1651  */
1652 sctp_disposition_t sctp_sf_do_5_2_2_dupinit(struct net *net,
1653 					const struct sctp_endpoint *ep,
1654 					const struct sctp_association *asoc,
1655 					const sctp_subtype_t type,
1656 					void *arg,
1657 					sctp_cmd_seq_t *commands)
1658 {
1659 	/* Call helper to do the real work for both simulataneous and
1660 	 * duplicate INIT chunk handling.
1661 	 */
1662 	return sctp_sf_do_unexpected_init(net, ep, asoc, type, arg, commands);
1663 }
1664 
1665 
1666 /*
1667  * Unexpected INIT-ACK handler.
1668  *
1669  * Section 5.2.3
1670  * If an INIT ACK received by an endpoint in any state other than the
1671  * COOKIE-WAIT state, the endpoint should discard the INIT ACK chunk.
1672  * An unexpected INIT ACK usually indicates the processing of an old or
1673  * duplicated INIT chunk.
1674 */
1675 sctp_disposition_t sctp_sf_do_5_2_3_initack(struct net *net,
1676 					    const struct sctp_endpoint *ep,
1677 					    const struct sctp_association *asoc,
1678 					    const sctp_subtype_t type,
1679 					    void *arg, sctp_cmd_seq_t *commands)
1680 {
1681 	/* Per the above section, we'll discard the chunk if we have an
1682 	 * endpoint.  If this is an OOTB INIT-ACK, treat it as such.
1683 	 */
1684 	if (ep == sctp_sk(net->sctp.ctl_sock)->ep)
1685 		return sctp_sf_ootb(net, ep, asoc, type, arg, commands);
1686 	else
1687 		return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands);
1688 }
1689 
1690 /* Unexpected COOKIE-ECHO handler for peer restart (Table 2, action 'A')
1691  *
1692  * Section 5.2.4
1693  *  A)  In this case, the peer may have restarted.
1694  */
1695 static sctp_disposition_t sctp_sf_do_dupcook_a(struct net *net,
1696 					const struct sctp_endpoint *ep,
1697 					const struct sctp_association *asoc,
1698 					struct sctp_chunk *chunk,
1699 					sctp_cmd_seq_t *commands,
1700 					struct sctp_association *new_asoc)
1701 {
1702 	sctp_init_chunk_t *peer_init;
1703 	struct sctp_ulpevent *ev;
1704 	struct sctp_chunk *repl;
1705 	struct sctp_chunk *err;
1706 	sctp_disposition_t disposition;
1707 
1708 	/* new_asoc is a brand-new association, so these are not yet
1709 	 * side effects--it is safe to run them here.
1710 	 */
1711 	peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
1712 
1713 	if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), peer_init,
1714 			       GFP_ATOMIC))
1715 		goto nomem;
1716 
1717 	/* Make sure no new addresses are being added during the
1718 	 * restart.  Though this is a pretty complicated attack
1719 	 * since you'd have to get inside the cookie.
1720 	 */
1721 	if (!sctp_sf_check_restart_addrs(new_asoc, asoc, chunk, commands)) {
1722 		return SCTP_DISPOSITION_CONSUME;
1723 	}
1724 
1725 	/* If the endpoint is in the SHUTDOWN-ACK-SENT state and recognizes
1726 	 * the peer has restarted (Action A), it MUST NOT setup a new
1727 	 * association but instead resend the SHUTDOWN ACK and send an ERROR
1728 	 * chunk with a "Cookie Received while Shutting Down" error cause to
1729 	 * its peer.
1730 	*/
1731 	if (sctp_state(asoc, SHUTDOWN_ACK_SENT)) {
1732 		disposition = sctp_sf_do_9_2_reshutack(net, ep, asoc,
1733 				SCTP_ST_CHUNK(chunk->chunk_hdr->type),
1734 				chunk, commands);
1735 		if (SCTP_DISPOSITION_NOMEM == disposition)
1736 			goto nomem;
1737 
1738 		err = sctp_make_op_error(asoc, chunk,
1739 					 SCTP_ERROR_COOKIE_IN_SHUTDOWN,
1740 					 NULL, 0, 0);
1741 		if (err)
1742 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
1743 					SCTP_CHUNK(err));
1744 
1745 		return SCTP_DISPOSITION_CONSUME;
1746 	}
1747 
1748 	/* For now, stop pending T3-rtx and SACK timers, fail any unsent/unacked
1749 	 * data. Consider the optional choice of resending of this data.
1750 	 */
1751 	sctp_add_cmd_sf(commands, SCTP_CMD_T3_RTX_TIMERS_STOP, SCTP_NULL());
1752 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
1753 			SCTP_TO(SCTP_EVENT_TIMEOUT_SACK));
1754 	sctp_add_cmd_sf(commands, SCTP_CMD_PURGE_OUTQUEUE, SCTP_NULL());
1755 
1756 	/* Stop pending T4-rto timer, teardown ASCONF queue, ASCONF-ACK queue
1757 	 * and ASCONF-ACK cache.
1758 	 */
1759 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
1760 			SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
1761 	sctp_add_cmd_sf(commands, SCTP_CMD_PURGE_ASCONF_QUEUE, SCTP_NULL());
1762 
1763 	repl = sctp_make_cookie_ack(new_asoc, chunk);
1764 	if (!repl)
1765 		goto nomem;
1766 
1767 	/* Report association restart to upper layer. */
1768 	ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_RESTART, 0,
1769 					     new_asoc->c.sinit_num_ostreams,
1770 					     new_asoc->c.sinit_max_instreams,
1771 					     NULL, GFP_ATOMIC);
1772 	if (!ev)
1773 		goto nomem_ev;
1774 
1775 	/* Update the content of current association. */
1776 	sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC, SCTP_ASOC(new_asoc));
1777 	sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
1778 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
1779 			SCTP_STATE(SCTP_STATE_ESTABLISHED));
1780 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
1781 	return SCTP_DISPOSITION_CONSUME;
1782 
1783 nomem_ev:
1784 	sctp_chunk_free(repl);
1785 nomem:
1786 	return SCTP_DISPOSITION_NOMEM;
1787 }
1788 
1789 /* Unexpected COOKIE-ECHO handler for setup collision (Table 2, action 'B')
1790  *
1791  * Section 5.2.4
1792  *   B) In this case, both sides may be attempting to start an association
1793  *      at about the same time but the peer endpoint started its INIT
1794  *      after responding to the local endpoint's INIT
1795  */
1796 /* This case represents an initialization collision.  */
1797 static sctp_disposition_t sctp_sf_do_dupcook_b(struct net *net,
1798 					const struct sctp_endpoint *ep,
1799 					const struct sctp_association *asoc,
1800 					struct sctp_chunk *chunk,
1801 					sctp_cmd_seq_t *commands,
1802 					struct sctp_association *new_asoc)
1803 {
1804 	sctp_init_chunk_t *peer_init;
1805 	struct sctp_chunk *repl;
1806 
1807 	/* new_asoc is a brand-new association, so these are not yet
1808 	 * side effects--it is safe to run them here.
1809 	 */
1810 	peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
1811 	if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), peer_init,
1812 			       GFP_ATOMIC))
1813 		goto nomem;
1814 
1815 	/* Update the content of current association.  */
1816 	sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC, SCTP_ASOC(new_asoc));
1817 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
1818 			SCTP_STATE(SCTP_STATE_ESTABLISHED));
1819 	SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
1820 	sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL());
1821 
1822 	repl = sctp_make_cookie_ack(new_asoc, chunk);
1823 	if (!repl)
1824 		goto nomem;
1825 
1826 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
1827 
1828 	/* RFC 2960 5.1 Normal Establishment of an Association
1829 	 *
1830 	 * D) IMPLEMENTATION NOTE: An implementation may choose to
1831 	 * send the Communication Up notification to the SCTP user
1832 	 * upon reception of a valid COOKIE ECHO chunk.
1833 	 *
1834 	 * Sadly, this needs to be implemented as a side-effect, because
1835 	 * we are not guaranteed to have set the association id of the real
1836 	 * association and so these notifications need to be delayed until
1837 	 * the association id is allocated.
1838 	 */
1839 
1840 	sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_CHANGE, SCTP_U8(SCTP_COMM_UP));
1841 
1842 	/* Sockets API Draft Section 5.3.1.6
1843 	 * When a peer sends a Adaptation Layer Indication parameter , SCTP
1844 	 * delivers this notification to inform the application that of the
1845 	 * peers requested adaptation layer.
1846 	 *
1847 	 * This also needs to be done as a side effect for the same reason as
1848 	 * above.
1849 	 */
1850 	if (asoc->peer.adaptation_ind)
1851 		sctp_add_cmd_sf(commands, SCTP_CMD_ADAPTATION_IND, SCTP_NULL());
1852 
1853 	return SCTP_DISPOSITION_CONSUME;
1854 
1855 nomem:
1856 	return SCTP_DISPOSITION_NOMEM;
1857 }
1858 
1859 /* Unexpected COOKIE-ECHO handler for setup collision (Table 2, action 'C')
1860  *
1861  * Section 5.2.4
1862  *  C) In this case, the local endpoint's cookie has arrived late.
1863  *     Before it arrived, the local endpoint sent an INIT and received an
1864  *     INIT-ACK and finally sent a COOKIE ECHO with the peer's same tag
1865  *     but a new tag of its own.
1866  */
1867 /* This case represents an initialization collision.  */
1868 static sctp_disposition_t sctp_sf_do_dupcook_c(struct net *net,
1869 					const struct sctp_endpoint *ep,
1870 					const struct sctp_association *asoc,
1871 					struct sctp_chunk *chunk,
1872 					sctp_cmd_seq_t *commands,
1873 					struct sctp_association *new_asoc)
1874 {
1875 	/* The cookie should be silently discarded.
1876 	 * The endpoint SHOULD NOT change states and should leave
1877 	 * any timers running.
1878 	 */
1879 	return SCTP_DISPOSITION_DISCARD;
1880 }
1881 
1882 /* Unexpected COOKIE-ECHO handler lost chunk (Table 2, action 'D')
1883  *
1884  * Section 5.2.4
1885  *
1886  * D) When both local and remote tags match the endpoint should always
1887  *    enter the ESTABLISHED state, if it has not already done so.
1888  */
1889 /* This case represents an initialization collision.  */
1890 static sctp_disposition_t sctp_sf_do_dupcook_d(struct net *net,
1891 					const struct sctp_endpoint *ep,
1892 					const struct sctp_association *asoc,
1893 					struct sctp_chunk *chunk,
1894 					sctp_cmd_seq_t *commands,
1895 					struct sctp_association *new_asoc)
1896 {
1897 	struct sctp_ulpevent *ev = NULL, *ai_ev = NULL;
1898 	struct sctp_chunk *repl;
1899 
1900 	/* Clarification from Implementor's Guide:
1901 	 * D) When both local and remote tags match the endpoint should
1902 	 * enter the ESTABLISHED state, if it is in the COOKIE-ECHOED state.
1903 	 * It should stop any cookie timer that may be running and send
1904 	 * a COOKIE ACK.
1905 	 */
1906 
1907 	/* Don't accidentally move back into established state. */
1908 	if (asoc->state < SCTP_STATE_ESTABLISHED) {
1909 		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
1910 				SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
1911 		sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
1912 				SCTP_STATE(SCTP_STATE_ESTABLISHED));
1913 		SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
1914 		sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START,
1915 				SCTP_NULL());
1916 
1917 		/* RFC 2960 5.1 Normal Establishment of an Association
1918 		 *
1919 		 * D) IMPLEMENTATION NOTE: An implementation may choose
1920 		 * to send the Communication Up notification to the
1921 		 * SCTP user upon reception of a valid COOKIE
1922 		 * ECHO chunk.
1923 		 */
1924 		ev = sctp_ulpevent_make_assoc_change(asoc, 0,
1925 					     SCTP_COMM_UP, 0,
1926 					     asoc->c.sinit_num_ostreams,
1927 					     asoc->c.sinit_max_instreams,
1928 					     NULL, GFP_ATOMIC);
1929 		if (!ev)
1930 			goto nomem;
1931 
1932 		/* Sockets API Draft Section 5.3.1.6
1933 		 * When a peer sends a Adaptation Layer Indication parameter,
1934 		 * SCTP delivers this notification to inform the application
1935 		 * that of the peers requested adaptation layer.
1936 		 */
1937 		if (asoc->peer.adaptation_ind) {
1938 			ai_ev = sctp_ulpevent_make_adaptation_indication(asoc,
1939 								 GFP_ATOMIC);
1940 			if (!ai_ev)
1941 				goto nomem;
1942 
1943 		}
1944 	}
1945 
1946 	repl = sctp_make_cookie_ack(new_asoc, chunk);
1947 	if (!repl)
1948 		goto nomem;
1949 
1950 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
1951 
1952 	if (ev)
1953 		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
1954 				SCTP_ULPEVENT(ev));
1955 	if (ai_ev)
1956 		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
1957 					SCTP_ULPEVENT(ai_ev));
1958 
1959 	return SCTP_DISPOSITION_CONSUME;
1960 
1961 nomem:
1962 	if (ai_ev)
1963 		sctp_ulpevent_free(ai_ev);
1964 	if (ev)
1965 		sctp_ulpevent_free(ev);
1966 	return SCTP_DISPOSITION_NOMEM;
1967 }
1968 
1969 /*
1970  * Handle a duplicate COOKIE-ECHO.  This usually means a cookie-carrying
1971  * chunk was retransmitted and then delayed in the network.
1972  *
1973  * Section: 5.2.4 Handle a COOKIE ECHO when a TCB exists
1974  *
1975  * Verification Tag: None.  Do cookie validation.
1976  *
1977  * Inputs
1978  * (endpoint, asoc, chunk)
1979  *
1980  * Outputs
1981  * (asoc, reply_msg, msg_up, timers, counters)
1982  *
1983  * The return value is the disposition of the chunk.
1984  */
1985 sctp_disposition_t sctp_sf_do_5_2_4_dupcook(struct net *net,
1986 					const struct sctp_endpoint *ep,
1987 					const struct sctp_association *asoc,
1988 					const sctp_subtype_t type,
1989 					void *arg,
1990 					sctp_cmd_seq_t *commands)
1991 {
1992 	sctp_disposition_t retval;
1993 	struct sctp_chunk *chunk = arg;
1994 	struct sctp_association *new_asoc;
1995 	int error = 0;
1996 	char action;
1997 	struct sctp_chunk *err_chk_p;
1998 
1999 	/* Make sure that the chunk has a valid length from the protocol
2000 	 * perspective.  In this case check to make sure we have at least
2001 	 * enough for the chunk header.  Cookie length verification is
2002 	 * done later.
2003 	 */
2004 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
2005 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2006 						  commands);
2007 
2008 	/* "Decode" the chunk.  We have no optional parameters so we
2009 	 * are in good shape.
2010 	 */
2011 	chunk->subh.cookie_hdr = (struct sctp_signed_cookie *)chunk->skb->data;
2012 	if (!pskb_pull(chunk->skb, ntohs(chunk->chunk_hdr->length) -
2013 					sizeof(sctp_chunkhdr_t)))
2014 		goto nomem;
2015 
2016 	/* In RFC 2960 5.2.4 3, if both Verification Tags in the State Cookie
2017 	 * of a duplicate COOKIE ECHO match the Verification Tags of the
2018 	 * current association, consider the State Cookie valid even if
2019 	 * the lifespan is exceeded.
2020 	 */
2021 	new_asoc = sctp_unpack_cookie(ep, asoc, chunk, GFP_ATOMIC, &error,
2022 				      &err_chk_p);
2023 
2024 	/* FIXME:
2025 	 * If the re-build failed, what is the proper error path
2026 	 * from here?
2027 	 *
2028 	 * [We should abort the association. --piggy]
2029 	 */
2030 	if (!new_asoc) {
2031 		/* FIXME: Several errors are possible.  A bad cookie should
2032 		 * be silently discarded, but think about logging it too.
2033 		 */
2034 		switch (error) {
2035 		case -SCTP_IERROR_NOMEM:
2036 			goto nomem;
2037 
2038 		case -SCTP_IERROR_STALE_COOKIE:
2039 			sctp_send_stale_cookie_err(net, ep, asoc, chunk, commands,
2040 						   err_chk_p);
2041 			return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2042 		case -SCTP_IERROR_BAD_SIG:
2043 		default:
2044 			return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2045 		}
2046 	}
2047 
2048 	/* Compare the tie_tag in cookie with the verification tag of
2049 	 * current association.
2050 	 */
2051 	action = sctp_tietags_compare(new_asoc, asoc);
2052 
2053 	switch (action) {
2054 	case 'A': /* Association restart. */
2055 		retval = sctp_sf_do_dupcook_a(net, ep, asoc, chunk, commands,
2056 					      new_asoc);
2057 		break;
2058 
2059 	case 'B': /* Collision case B. */
2060 		retval = sctp_sf_do_dupcook_b(net, ep, asoc, chunk, commands,
2061 					      new_asoc);
2062 		break;
2063 
2064 	case 'C': /* Collision case C. */
2065 		retval = sctp_sf_do_dupcook_c(net, ep, asoc, chunk, commands,
2066 					      new_asoc);
2067 		break;
2068 
2069 	case 'D': /* Collision case D. */
2070 		retval = sctp_sf_do_dupcook_d(net, ep, asoc, chunk, commands,
2071 					      new_asoc);
2072 		break;
2073 
2074 	default: /* Discard packet for all others. */
2075 		retval = sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2076 		break;
2077 	}
2078 
2079 	/* Delete the tempory new association. */
2080 	sctp_add_cmd_sf(commands, SCTP_CMD_SET_ASOC, SCTP_ASOC(new_asoc));
2081 	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
2082 
2083 	/* Restore association pointer to provide SCTP command interpeter
2084 	 * with a valid context in case it needs to manipulate
2085 	 * the queues */
2086 	sctp_add_cmd_sf(commands, SCTP_CMD_SET_ASOC,
2087 			 SCTP_ASOC((struct sctp_association *)asoc));
2088 
2089 	return retval;
2090 
2091 nomem:
2092 	return SCTP_DISPOSITION_NOMEM;
2093 }
2094 
2095 /*
2096  * Process an ABORT.  (SHUTDOWN-PENDING state)
2097  *
2098  * See sctp_sf_do_9_1_abort().
2099  */
2100 sctp_disposition_t sctp_sf_shutdown_pending_abort(
2101 	struct net *net,
2102 	const struct sctp_endpoint *ep,
2103 	const struct sctp_association *asoc,
2104 	const sctp_subtype_t type,
2105 	void *arg,
2106 	sctp_cmd_seq_t *commands)
2107 {
2108 	struct sctp_chunk *chunk = arg;
2109 
2110 	if (!sctp_vtag_verify_either(chunk, asoc))
2111 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2112 
2113 	/* Make sure that the ABORT chunk has a valid length.
2114 	 * Since this is an ABORT chunk, we have to discard it
2115 	 * because of the following text:
2116 	 * RFC 2960, Section 3.3.7
2117 	 *    If an endpoint receives an ABORT with a format error or for an
2118 	 *    association that doesn't exist, it MUST silently discard it.
2119 	 * Because the length is "invalid", we can't really discard just
2120 	 * as we do not know its true length.  So, to be safe, discard the
2121 	 * packet.
2122 	 */
2123 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_abort_chunk_t)))
2124 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2125 
2126 	/* ADD-IP: Special case for ABORT chunks
2127 	 * F4)  One special consideration is that ABORT Chunks arriving
2128 	 * destined to the IP address being deleted MUST be
2129 	 * ignored (see Section 5.3.1 for further details).
2130 	 */
2131 	if (SCTP_ADDR_DEL ==
2132 		    sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest))
2133 		return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands);
2134 
2135 	return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands);
2136 }
2137 
2138 /*
2139  * Process an ABORT.  (SHUTDOWN-SENT state)
2140  *
2141  * See sctp_sf_do_9_1_abort().
2142  */
2143 sctp_disposition_t sctp_sf_shutdown_sent_abort(struct net *net,
2144 					const struct sctp_endpoint *ep,
2145 					const struct sctp_association *asoc,
2146 					const sctp_subtype_t type,
2147 					void *arg,
2148 					sctp_cmd_seq_t *commands)
2149 {
2150 	struct sctp_chunk *chunk = arg;
2151 
2152 	if (!sctp_vtag_verify_either(chunk, asoc))
2153 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2154 
2155 	/* Make sure that the ABORT chunk has a valid length.
2156 	 * Since this is an ABORT chunk, we have to discard it
2157 	 * because of the following text:
2158 	 * RFC 2960, Section 3.3.7
2159 	 *    If an endpoint receives an ABORT with a format error or for an
2160 	 *    association that doesn't exist, it MUST silently discard it.
2161 	 * Because the length is "invalid", we can't really discard just
2162 	 * as we do not know its true length.  So, to be safe, discard the
2163 	 * packet.
2164 	 */
2165 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_abort_chunk_t)))
2166 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2167 
2168 	/* ADD-IP: Special case for ABORT chunks
2169 	 * F4)  One special consideration is that ABORT Chunks arriving
2170 	 * destined to the IP address being deleted MUST be
2171 	 * ignored (see Section 5.3.1 for further details).
2172 	 */
2173 	if (SCTP_ADDR_DEL ==
2174 		    sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest))
2175 		return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands);
2176 
2177 	/* Stop the T2-shutdown timer. */
2178 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
2179 			SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
2180 
2181 	/* Stop the T5-shutdown guard timer.  */
2182 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
2183 			SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
2184 
2185 	return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands);
2186 }
2187 
2188 /*
2189  * Process an ABORT.  (SHUTDOWN-ACK-SENT state)
2190  *
2191  * See sctp_sf_do_9_1_abort().
2192  */
2193 sctp_disposition_t sctp_sf_shutdown_ack_sent_abort(
2194 	struct net *net,
2195 	const struct sctp_endpoint *ep,
2196 	const struct sctp_association *asoc,
2197 	const sctp_subtype_t type,
2198 	void *arg,
2199 	sctp_cmd_seq_t *commands)
2200 {
2201 	/* The same T2 timer, so we should be able to use
2202 	 * common function with the SHUTDOWN-SENT state.
2203 	 */
2204 	return sctp_sf_shutdown_sent_abort(net, ep, asoc, type, arg, commands);
2205 }
2206 
2207 /*
2208  * Handle an Error received in COOKIE_ECHOED state.
2209  *
2210  * Only handle the error type of stale COOKIE Error, the other errors will
2211  * be ignored.
2212  *
2213  * Inputs
2214  * (endpoint, asoc, chunk)
2215  *
2216  * Outputs
2217  * (asoc, reply_msg, msg_up, timers, counters)
2218  *
2219  * The return value is the disposition of the chunk.
2220  */
2221 sctp_disposition_t sctp_sf_cookie_echoed_err(struct net *net,
2222 					const struct sctp_endpoint *ep,
2223 					const struct sctp_association *asoc,
2224 					const sctp_subtype_t type,
2225 					void *arg,
2226 					sctp_cmd_seq_t *commands)
2227 {
2228 	struct sctp_chunk *chunk = arg;
2229 	sctp_errhdr_t *err;
2230 
2231 	if (!sctp_vtag_verify(chunk, asoc))
2232 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2233 
2234 	/* Make sure that the ERROR chunk has a valid length.
2235 	 * The parameter walking depends on this as well.
2236 	 */
2237 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_operr_chunk_t)))
2238 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2239 						  commands);
2240 
2241 	/* Process the error here */
2242 	/* FUTURE FIXME:  When PR-SCTP related and other optional
2243 	 * parms are emitted, this will have to change to handle multiple
2244 	 * errors.
2245 	 */
2246 	sctp_walk_errors(err, chunk->chunk_hdr) {
2247 		if (SCTP_ERROR_STALE_COOKIE == err->cause)
2248 			return sctp_sf_do_5_2_6_stale(net, ep, asoc, type,
2249 							arg, commands);
2250 	}
2251 
2252 	/* It is possible to have malformed error causes, and that
2253 	 * will cause us to end the walk early.  However, since
2254 	 * we are discarding the packet, there should be no adverse
2255 	 * affects.
2256 	 */
2257 	return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2258 }
2259 
2260 /*
2261  * Handle a Stale COOKIE Error
2262  *
2263  * Section: 5.2.6 Handle Stale COOKIE Error
2264  * If the association is in the COOKIE-ECHOED state, the endpoint may elect
2265  * one of the following three alternatives.
2266  * ...
2267  * 3) Send a new INIT chunk to the endpoint, adding a Cookie
2268  *    Preservative parameter requesting an extension to the lifetime of
2269  *    the State Cookie. When calculating the time extension, an
2270  *    implementation SHOULD use the RTT information measured based on the
2271  *    previous COOKIE ECHO / ERROR exchange, and should add no more
2272  *    than 1 second beyond the measured RTT, due to long State Cookie
2273  *    lifetimes making the endpoint more subject to a replay attack.
2274  *
2275  * Verification Tag:  Not explicit, but safe to ignore.
2276  *
2277  * Inputs
2278  * (endpoint, asoc, chunk)
2279  *
2280  * Outputs
2281  * (asoc, reply_msg, msg_up, timers, counters)
2282  *
2283  * The return value is the disposition of the chunk.
2284  */
2285 static sctp_disposition_t sctp_sf_do_5_2_6_stale(struct net *net,
2286 						 const struct sctp_endpoint *ep,
2287 						 const struct sctp_association *asoc,
2288 						 const sctp_subtype_t type,
2289 						 void *arg,
2290 						 sctp_cmd_seq_t *commands)
2291 {
2292 	struct sctp_chunk *chunk = arg;
2293 	time_t stale;
2294 	sctp_cookie_preserve_param_t bht;
2295 	sctp_errhdr_t *err;
2296 	struct sctp_chunk *reply;
2297 	struct sctp_bind_addr *bp;
2298 	int attempts = asoc->init_err_counter + 1;
2299 
2300 	if (attempts > asoc->max_init_attempts) {
2301 		sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
2302 				SCTP_ERROR(ETIMEDOUT));
2303 		sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
2304 				SCTP_PERR(SCTP_ERROR_STALE_COOKIE));
2305 		return SCTP_DISPOSITION_DELETE_TCB;
2306 	}
2307 
2308 	err = (sctp_errhdr_t *)(chunk->skb->data);
2309 
2310 	/* When calculating the time extension, an implementation
2311 	 * SHOULD use the RTT information measured based on the
2312 	 * previous COOKIE ECHO / ERROR exchange, and should add no
2313 	 * more than 1 second beyond the measured RTT, due to long
2314 	 * State Cookie lifetimes making the endpoint more subject to
2315 	 * a replay attack.
2316 	 * Measure of Staleness's unit is usec. (1/1000000 sec)
2317 	 * Suggested Cookie Life-span Increment's unit is msec.
2318 	 * (1/1000 sec)
2319 	 * In general, if you use the suggested cookie life, the value
2320 	 * found in the field of measure of staleness should be doubled
2321 	 * to give ample time to retransmit the new cookie and thus
2322 	 * yield a higher probability of success on the reattempt.
2323 	 */
2324 	stale = ntohl(*(__be32 *)((u8 *)err + sizeof(sctp_errhdr_t)));
2325 	stale = (stale * 2) / 1000;
2326 
2327 	bht.param_hdr.type = SCTP_PARAM_COOKIE_PRESERVATIVE;
2328 	bht.param_hdr.length = htons(sizeof(bht));
2329 	bht.lifespan_increment = htonl(stale);
2330 
2331 	/* Build that new INIT chunk.  */
2332 	bp = (struct sctp_bind_addr *) &asoc->base.bind_addr;
2333 	reply = sctp_make_init(asoc, bp, GFP_ATOMIC, sizeof(bht));
2334 	if (!reply)
2335 		goto nomem;
2336 
2337 	sctp_addto_chunk(reply, sizeof(bht), &bht);
2338 
2339 	/* Clear peer's init_tag cached in assoc as we are sending a new INIT */
2340 	sctp_add_cmd_sf(commands, SCTP_CMD_CLEAR_INIT_TAG, SCTP_NULL());
2341 
2342 	/* Stop pending T3-rtx and heartbeat timers */
2343 	sctp_add_cmd_sf(commands, SCTP_CMD_T3_RTX_TIMERS_STOP, SCTP_NULL());
2344 	sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL());
2345 
2346 	/* Delete non-primary peer ip addresses since we are transitioning
2347 	 * back to the COOKIE-WAIT state
2348 	 */
2349 	sctp_add_cmd_sf(commands, SCTP_CMD_DEL_NON_PRIMARY, SCTP_NULL());
2350 
2351 	/* If we've sent any data bundled with COOKIE-ECHO we will need to
2352 	 * resend
2353 	 */
2354 	sctp_add_cmd_sf(commands, SCTP_CMD_T1_RETRAN,
2355 			SCTP_TRANSPORT(asoc->peer.primary_path));
2356 
2357 	/* Cast away the const modifier, as we want to just
2358 	 * rerun it through as a sideffect.
2359 	 */
2360 	sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_INC, SCTP_NULL());
2361 
2362 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
2363 			SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
2364 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
2365 			SCTP_STATE(SCTP_STATE_COOKIE_WAIT));
2366 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
2367 			SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
2368 
2369 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
2370 
2371 	return SCTP_DISPOSITION_CONSUME;
2372 
2373 nomem:
2374 	return SCTP_DISPOSITION_NOMEM;
2375 }
2376 
2377 /*
2378  * Process an ABORT.
2379  *
2380  * Section: 9.1
2381  * After checking the Verification Tag, the receiving endpoint shall
2382  * remove the association from its record, and shall report the
2383  * termination to its upper layer.
2384  *
2385  * Verification Tag: 8.5.1 Exceptions in Verification Tag Rules
2386  * B) Rules for packet carrying ABORT:
2387  *
2388  *  - The endpoint shall always fill in the Verification Tag field of the
2389  *    outbound packet with the destination endpoint's tag value if it
2390  *    is known.
2391  *
2392  *  - If the ABORT is sent in response to an OOTB packet, the endpoint
2393  *    MUST follow the procedure described in Section 8.4.
2394  *
2395  *  - The receiver MUST accept the packet if the Verification Tag
2396  *    matches either its own tag, OR the tag of its peer. Otherwise, the
2397  *    receiver MUST silently discard the packet and take no further
2398  *    action.
2399  *
2400  * Inputs
2401  * (endpoint, asoc, chunk)
2402  *
2403  * Outputs
2404  * (asoc, reply_msg, msg_up, timers, counters)
2405  *
2406  * The return value is the disposition of the chunk.
2407  */
2408 sctp_disposition_t sctp_sf_do_9_1_abort(struct net *net,
2409 					const struct sctp_endpoint *ep,
2410 					const struct sctp_association *asoc,
2411 					const sctp_subtype_t type,
2412 					void *arg,
2413 					sctp_cmd_seq_t *commands)
2414 {
2415 	struct sctp_chunk *chunk = arg;
2416 
2417 	if (!sctp_vtag_verify_either(chunk, asoc))
2418 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2419 
2420 	/* Make sure that the ABORT chunk has a valid length.
2421 	 * Since this is an ABORT chunk, we have to discard it
2422 	 * because of the following text:
2423 	 * RFC 2960, Section 3.3.7
2424 	 *    If an endpoint receives an ABORT with a format error or for an
2425 	 *    association that doesn't exist, it MUST silently discard it.
2426 	 * Because the length is "invalid", we can't really discard just
2427 	 * as we do not know its true length.  So, to be safe, discard the
2428 	 * packet.
2429 	 */
2430 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_abort_chunk_t)))
2431 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2432 
2433 	/* ADD-IP: Special case for ABORT chunks
2434 	 * F4)  One special consideration is that ABORT Chunks arriving
2435 	 * destined to the IP address being deleted MUST be
2436 	 * ignored (see Section 5.3.1 for further details).
2437 	 */
2438 	if (SCTP_ADDR_DEL ==
2439 		    sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest))
2440 		return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands);
2441 
2442 	return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands);
2443 }
2444 
2445 static sctp_disposition_t __sctp_sf_do_9_1_abort(struct net *net,
2446 					const struct sctp_endpoint *ep,
2447 					const struct sctp_association *asoc,
2448 					const sctp_subtype_t type,
2449 					void *arg,
2450 					sctp_cmd_seq_t *commands)
2451 {
2452 	struct sctp_chunk *chunk = arg;
2453 	unsigned int len;
2454 	__be16 error = SCTP_ERROR_NO_ERROR;
2455 
2456 	/* See if we have an error cause code in the chunk.  */
2457 	len = ntohs(chunk->chunk_hdr->length);
2458 	if (len >= sizeof(struct sctp_chunkhdr) + sizeof(struct sctp_errhdr)) {
2459 
2460 		sctp_errhdr_t *err;
2461 		sctp_walk_errors(err, chunk->chunk_hdr);
2462 		if ((void *)err != (void *)chunk->chunk_end)
2463 			return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2464 
2465 		error = ((sctp_errhdr_t *)chunk->skb->data)->cause;
2466 	}
2467 
2468 	sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNRESET));
2469 	/* ASSOC_FAILED will DELETE_TCB. */
2470 	sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(error));
2471 	SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
2472 	SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
2473 
2474 	return SCTP_DISPOSITION_ABORT;
2475 }
2476 
2477 /*
2478  * Process an ABORT.  (COOKIE-WAIT state)
2479  *
2480  * See sctp_sf_do_9_1_abort() above.
2481  */
2482 sctp_disposition_t sctp_sf_cookie_wait_abort(struct net *net,
2483 				     const struct sctp_endpoint *ep,
2484 				     const struct sctp_association *asoc,
2485 				     const sctp_subtype_t type,
2486 				     void *arg,
2487 				     sctp_cmd_seq_t *commands)
2488 {
2489 	struct sctp_chunk *chunk = arg;
2490 	unsigned int len;
2491 	__be16 error = SCTP_ERROR_NO_ERROR;
2492 
2493 	if (!sctp_vtag_verify_either(chunk, asoc))
2494 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2495 
2496 	/* Make sure that the ABORT chunk has a valid length.
2497 	 * Since this is an ABORT chunk, we have to discard it
2498 	 * because of the following text:
2499 	 * RFC 2960, Section 3.3.7
2500 	 *    If an endpoint receives an ABORT with a format error or for an
2501 	 *    association that doesn't exist, it MUST silently discard it.
2502 	 * Because the length is "invalid", we can't really discard just
2503 	 * as we do not know its true length.  So, to be safe, discard the
2504 	 * packet.
2505 	 */
2506 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_abort_chunk_t)))
2507 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2508 
2509 	/* See if we have an error cause code in the chunk.  */
2510 	len = ntohs(chunk->chunk_hdr->length);
2511 	if (len >= sizeof(struct sctp_chunkhdr) + sizeof(struct sctp_errhdr))
2512 		error = ((sctp_errhdr_t *)chunk->skb->data)->cause;
2513 
2514 	return sctp_stop_t1_and_abort(net, commands, error, ECONNREFUSED, asoc,
2515 				      chunk->transport);
2516 }
2517 
2518 /*
2519  * Process an incoming ICMP as an ABORT.  (COOKIE-WAIT state)
2520  */
2521 sctp_disposition_t sctp_sf_cookie_wait_icmp_abort(struct net *net,
2522 					const struct sctp_endpoint *ep,
2523 					const struct sctp_association *asoc,
2524 					const sctp_subtype_t type,
2525 					void *arg,
2526 					sctp_cmd_seq_t *commands)
2527 {
2528 	return sctp_stop_t1_and_abort(net, commands, SCTP_ERROR_NO_ERROR,
2529 				      ENOPROTOOPT, asoc,
2530 				      (struct sctp_transport *)arg);
2531 }
2532 
2533 /*
2534  * Process an ABORT.  (COOKIE-ECHOED state)
2535  */
2536 sctp_disposition_t sctp_sf_cookie_echoed_abort(struct net *net,
2537 					       const struct sctp_endpoint *ep,
2538 					       const struct sctp_association *asoc,
2539 					       const sctp_subtype_t type,
2540 					       void *arg,
2541 					       sctp_cmd_seq_t *commands)
2542 {
2543 	/* There is a single T1 timer, so we should be able to use
2544 	 * common function with the COOKIE-WAIT state.
2545 	 */
2546 	return sctp_sf_cookie_wait_abort(net, ep, asoc, type, arg, commands);
2547 }
2548 
2549 /*
2550  * Stop T1 timer and abort association with "INIT failed".
2551  *
2552  * This is common code called by several sctp_sf_*_abort() functions above.
2553  */
2554 static sctp_disposition_t sctp_stop_t1_and_abort(struct net *net,
2555 					   sctp_cmd_seq_t *commands,
2556 					   __be16 error, int sk_err,
2557 					   const struct sctp_association *asoc,
2558 					   struct sctp_transport *transport)
2559 {
2560 	pr_debug("%s: ABORT received (INIT)\n", __func__);
2561 
2562 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
2563 			SCTP_STATE(SCTP_STATE_CLOSED));
2564 	SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
2565 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
2566 			SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
2567 	sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(sk_err));
2568 	/* CMD_INIT_FAILED will DELETE_TCB. */
2569 	sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
2570 			SCTP_PERR(error));
2571 
2572 	return SCTP_DISPOSITION_ABORT;
2573 }
2574 
2575 /*
2576  * sctp_sf_do_9_2_shut
2577  *
2578  * Section: 9.2
2579  * Upon the reception of the SHUTDOWN, the peer endpoint shall
2580  *  - enter the SHUTDOWN-RECEIVED state,
2581  *
2582  *  - stop accepting new data from its SCTP user
2583  *
2584  *  - verify, by checking the Cumulative TSN Ack field of the chunk,
2585  *    that all its outstanding DATA chunks have been received by the
2586  *    SHUTDOWN sender.
2587  *
2588  * Once an endpoint as reached the SHUTDOWN-RECEIVED state it MUST NOT
2589  * send a SHUTDOWN in response to a ULP request. And should discard
2590  * subsequent SHUTDOWN chunks.
2591  *
2592  * If there are still outstanding DATA chunks left, the SHUTDOWN
2593  * receiver shall continue to follow normal data transmission
2594  * procedures defined in Section 6 until all outstanding DATA chunks
2595  * are acknowledged; however, the SHUTDOWN receiver MUST NOT accept
2596  * new data from its SCTP user.
2597  *
2598  * Verification Tag:  8.5 Verification Tag [Normal verification]
2599  *
2600  * Inputs
2601  * (endpoint, asoc, chunk)
2602  *
2603  * Outputs
2604  * (asoc, reply_msg, msg_up, timers, counters)
2605  *
2606  * The return value is the disposition of the chunk.
2607  */
2608 sctp_disposition_t sctp_sf_do_9_2_shutdown(struct net *net,
2609 					   const struct sctp_endpoint *ep,
2610 					   const struct sctp_association *asoc,
2611 					   const sctp_subtype_t type,
2612 					   void *arg,
2613 					   sctp_cmd_seq_t *commands)
2614 {
2615 	struct sctp_chunk *chunk = arg;
2616 	sctp_shutdownhdr_t *sdh;
2617 	sctp_disposition_t disposition;
2618 	struct sctp_ulpevent *ev;
2619 	__u32 ctsn;
2620 
2621 	if (!sctp_vtag_verify(chunk, asoc))
2622 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2623 
2624 	/* Make sure that the SHUTDOWN chunk has a valid length. */
2625 	if (!sctp_chunk_length_valid(chunk,
2626 				      sizeof(struct sctp_shutdown_chunk_t)))
2627 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2628 						  commands);
2629 
2630 	/* Convert the elaborate header.  */
2631 	sdh = (sctp_shutdownhdr_t *)chunk->skb->data;
2632 	skb_pull(chunk->skb, sizeof(sctp_shutdownhdr_t));
2633 	chunk->subh.shutdown_hdr = sdh;
2634 	ctsn = ntohl(sdh->cum_tsn_ack);
2635 
2636 	if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
2637 		pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn,
2638 			 asoc->ctsn_ack_point);
2639 
2640 		return SCTP_DISPOSITION_DISCARD;
2641 	}
2642 
2643 	/* If Cumulative TSN Ack beyond the max tsn currently
2644 	 * send, terminating the association and respond to the
2645 	 * sender with an ABORT.
2646 	 */
2647 	if (!TSN_lt(ctsn, asoc->next_tsn))
2648 		return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands);
2649 
2650 	/* API 5.3.1.5 SCTP_SHUTDOWN_EVENT
2651 	 * When a peer sends a SHUTDOWN, SCTP delivers this notification to
2652 	 * inform the application that it should cease sending data.
2653 	 */
2654 	ev = sctp_ulpevent_make_shutdown_event(asoc, 0, GFP_ATOMIC);
2655 	if (!ev) {
2656 		disposition = SCTP_DISPOSITION_NOMEM;
2657 		goto out;
2658 	}
2659 	sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
2660 
2661 	/* Upon the reception of the SHUTDOWN, the peer endpoint shall
2662 	 *  - enter the SHUTDOWN-RECEIVED state,
2663 	 *  - stop accepting new data from its SCTP user
2664 	 *
2665 	 * [This is implicit in the new state.]
2666 	 */
2667 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
2668 			SCTP_STATE(SCTP_STATE_SHUTDOWN_RECEIVED));
2669 	disposition = SCTP_DISPOSITION_CONSUME;
2670 
2671 	if (sctp_outq_is_empty(&asoc->outqueue)) {
2672 		disposition = sctp_sf_do_9_2_shutdown_ack(net, ep, asoc, type,
2673 							  arg, commands);
2674 	}
2675 
2676 	if (SCTP_DISPOSITION_NOMEM == disposition)
2677 		goto out;
2678 
2679 	/*  - verify, by checking the Cumulative TSN Ack field of the
2680 	 *    chunk, that all its outstanding DATA chunks have been
2681 	 *    received by the SHUTDOWN sender.
2682 	 */
2683 	sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_CTSN,
2684 			SCTP_BE32(chunk->subh.shutdown_hdr->cum_tsn_ack));
2685 
2686 out:
2687 	return disposition;
2688 }
2689 
2690 /*
2691  * sctp_sf_do_9_2_shut_ctsn
2692  *
2693  * Once an endpoint has reached the SHUTDOWN-RECEIVED state,
2694  * it MUST NOT send a SHUTDOWN in response to a ULP request.
2695  * The Cumulative TSN Ack of the received SHUTDOWN chunk
2696  * MUST be processed.
2697  */
2698 sctp_disposition_t sctp_sf_do_9_2_shut_ctsn(struct net *net,
2699 					   const struct sctp_endpoint *ep,
2700 					   const struct sctp_association *asoc,
2701 					   const sctp_subtype_t type,
2702 					   void *arg,
2703 					   sctp_cmd_seq_t *commands)
2704 {
2705 	struct sctp_chunk *chunk = arg;
2706 	sctp_shutdownhdr_t *sdh;
2707 	__u32 ctsn;
2708 
2709 	if (!sctp_vtag_verify(chunk, asoc))
2710 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2711 
2712 	/* Make sure that the SHUTDOWN chunk has a valid length. */
2713 	if (!sctp_chunk_length_valid(chunk,
2714 				      sizeof(struct sctp_shutdown_chunk_t)))
2715 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2716 						  commands);
2717 
2718 	sdh = (sctp_shutdownhdr_t *)chunk->skb->data;
2719 	ctsn = ntohl(sdh->cum_tsn_ack);
2720 
2721 	if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
2722 		pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn,
2723 			 asoc->ctsn_ack_point);
2724 
2725 		return SCTP_DISPOSITION_DISCARD;
2726 	}
2727 
2728 	/* If Cumulative TSN Ack beyond the max tsn currently
2729 	 * send, terminating the association and respond to the
2730 	 * sender with an ABORT.
2731 	 */
2732 	if (!TSN_lt(ctsn, asoc->next_tsn))
2733 		return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands);
2734 
2735 	/* verify, by checking the Cumulative TSN Ack field of the
2736 	 * chunk, that all its outstanding DATA chunks have been
2737 	 * received by the SHUTDOWN sender.
2738 	 */
2739 	sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_CTSN,
2740 			SCTP_BE32(sdh->cum_tsn_ack));
2741 
2742 	return SCTP_DISPOSITION_CONSUME;
2743 }
2744 
2745 /* RFC 2960 9.2
2746  * If an endpoint is in SHUTDOWN-ACK-SENT state and receives an INIT chunk
2747  * (e.g., if the SHUTDOWN COMPLETE was lost) with source and destination
2748  * transport addresses (either in the IP addresses or in the INIT chunk)
2749  * that belong to this association, it should discard the INIT chunk and
2750  * retransmit the SHUTDOWN ACK chunk.
2751  */
2752 sctp_disposition_t sctp_sf_do_9_2_reshutack(struct net *net,
2753 				    const struct sctp_endpoint *ep,
2754 				    const struct sctp_association *asoc,
2755 				    const sctp_subtype_t type,
2756 				    void *arg,
2757 				    sctp_cmd_seq_t *commands)
2758 {
2759 	struct sctp_chunk *chunk = (struct sctp_chunk *) arg;
2760 	struct sctp_chunk *reply;
2761 
2762 	/* Make sure that the chunk has a valid length */
2763 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
2764 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2765 						  commands);
2766 
2767 	/* Since we are not going to really process this INIT, there
2768 	 * is no point in verifying chunk boundries.  Just generate
2769 	 * the SHUTDOWN ACK.
2770 	 */
2771 	reply = sctp_make_shutdown_ack(asoc, chunk);
2772 	if (NULL == reply)
2773 		goto nomem;
2774 
2775 	/* Set the transport for the SHUTDOWN ACK chunk and the timeout for
2776 	 * the T2-SHUTDOWN timer.
2777 	 */
2778 	sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
2779 
2780 	/* and restart the T2-shutdown timer. */
2781 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
2782 			SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
2783 
2784 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
2785 
2786 	return SCTP_DISPOSITION_CONSUME;
2787 nomem:
2788 	return SCTP_DISPOSITION_NOMEM;
2789 }
2790 
2791 /*
2792  * sctp_sf_do_ecn_cwr
2793  *
2794  * Section:  Appendix A: Explicit Congestion Notification
2795  *
2796  * CWR:
2797  *
2798  * RFC 2481 details a specific bit for a sender to send in the header of
2799  * its next outbound TCP segment to indicate to its peer that it has
2800  * reduced its congestion window.  This is termed the CWR bit.  For
2801  * SCTP the same indication is made by including the CWR chunk.
2802  * This chunk contains one data element, i.e. the TSN number that
2803  * was sent in the ECNE chunk.  This element represents the lowest
2804  * TSN number in the datagram that was originally marked with the
2805  * CE bit.
2806  *
2807  * Verification Tag: 8.5 Verification Tag [Normal verification]
2808  * Inputs
2809  * (endpoint, asoc, chunk)
2810  *
2811  * Outputs
2812  * (asoc, reply_msg, msg_up, timers, counters)
2813  *
2814  * The return value is the disposition of the chunk.
2815  */
2816 sctp_disposition_t sctp_sf_do_ecn_cwr(struct net *net,
2817 				      const struct sctp_endpoint *ep,
2818 				      const struct sctp_association *asoc,
2819 				      const sctp_subtype_t type,
2820 				      void *arg,
2821 				      sctp_cmd_seq_t *commands)
2822 {
2823 	sctp_cwrhdr_t *cwr;
2824 	struct sctp_chunk *chunk = arg;
2825 	u32 lowest_tsn;
2826 
2827 	if (!sctp_vtag_verify(chunk, asoc))
2828 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2829 
2830 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_ecne_chunk_t)))
2831 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2832 						  commands);
2833 
2834 	cwr = (sctp_cwrhdr_t *) chunk->skb->data;
2835 	skb_pull(chunk->skb, sizeof(sctp_cwrhdr_t));
2836 
2837 	lowest_tsn = ntohl(cwr->lowest_tsn);
2838 
2839 	/* Does this CWR ack the last sent congestion notification? */
2840 	if (TSN_lte(asoc->last_ecne_tsn, lowest_tsn)) {
2841 		/* Stop sending ECNE. */
2842 		sctp_add_cmd_sf(commands,
2843 				SCTP_CMD_ECN_CWR,
2844 				SCTP_U32(lowest_tsn));
2845 	}
2846 	return SCTP_DISPOSITION_CONSUME;
2847 }
2848 
2849 /*
2850  * sctp_sf_do_ecne
2851  *
2852  * Section:  Appendix A: Explicit Congestion Notification
2853  *
2854  * ECN-Echo
2855  *
2856  * RFC 2481 details a specific bit for a receiver to send back in its
2857  * TCP acknowledgements to notify the sender of the Congestion
2858  * Experienced (CE) bit having arrived from the network.  For SCTP this
2859  * same indication is made by including the ECNE chunk.  This chunk
2860  * contains one data element, i.e. the lowest TSN associated with the IP
2861  * datagram marked with the CE bit.....
2862  *
2863  * Verification Tag: 8.5 Verification Tag [Normal verification]
2864  * Inputs
2865  * (endpoint, asoc, chunk)
2866  *
2867  * Outputs
2868  * (asoc, reply_msg, msg_up, timers, counters)
2869  *
2870  * The return value is the disposition of the chunk.
2871  */
2872 sctp_disposition_t sctp_sf_do_ecne(struct net *net,
2873 				   const struct sctp_endpoint *ep,
2874 				   const struct sctp_association *asoc,
2875 				   const sctp_subtype_t type,
2876 				   void *arg,
2877 				   sctp_cmd_seq_t *commands)
2878 {
2879 	sctp_ecnehdr_t *ecne;
2880 	struct sctp_chunk *chunk = arg;
2881 
2882 	if (!sctp_vtag_verify(chunk, asoc))
2883 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2884 
2885 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_ecne_chunk_t)))
2886 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2887 						  commands);
2888 
2889 	ecne = (sctp_ecnehdr_t *) chunk->skb->data;
2890 	skb_pull(chunk->skb, sizeof(sctp_ecnehdr_t));
2891 
2892 	/* If this is a newer ECNE than the last CWR packet we sent out */
2893 	sctp_add_cmd_sf(commands, SCTP_CMD_ECN_ECNE,
2894 			SCTP_U32(ntohl(ecne->lowest_tsn)));
2895 
2896 	return SCTP_DISPOSITION_CONSUME;
2897 }
2898 
2899 /*
2900  * Section: 6.2  Acknowledgement on Reception of DATA Chunks
2901  *
2902  * The SCTP endpoint MUST always acknowledge the reception of each valid
2903  * DATA chunk.
2904  *
2905  * The guidelines on delayed acknowledgement algorithm specified in
2906  * Section 4.2 of [RFC2581] SHOULD be followed. Specifically, an
2907  * acknowledgement SHOULD be generated for at least every second packet
2908  * (not every second DATA chunk) received, and SHOULD be generated within
2909  * 200 ms of the arrival of any unacknowledged DATA chunk. In some
2910  * situations it may be beneficial for an SCTP transmitter to be more
2911  * conservative than the algorithms detailed in this document allow.
2912  * However, an SCTP transmitter MUST NOT be more aggressive than the
2913  * following algorithms allow.
2914  *
2915  * A SCTP receiver MUST NOT generate more than one SACK for every
2916  * incoming packet, other than to update the offered window as the
2917  * receiving application consumes new data.
2918  *
2919  * Verification Tag:  8.5 Verification Tag [Normal verification]
2920  *
2921  * Inputs
2922  * (endpoint, asoc, chunk)
2923  *
2924  * Outputs
2925  * (asoc, reply_msg, msg_up, timers, counters)
2926  *
2927  * The return value is the disposition of the chunk.
2928  */
2929 sctp_disposition_t sctp_sf_eat_data_6_2(struct net *net,
2930 					const struct sctp_endpoint *ep,
2931 					const struct sctp_association *asoc,
2932 					const sctp_subtype_t type,
2933 					void *arg,
2934 					sctp_cmd_seq_t *commands)
2935 {
2936 	struct sctp_chunk *chunk = arg;
2937 	sctp_arg_t force = SCTP_NOFORCE();
2938 	int error;
2939 
2940 	if (!sctp_vtag_verify(chunk, asoc)) {
2941 		sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
2942 				SCTP_NULL());
2943 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2944 	}
2945 
2946 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_data_chunk_t)))
2947 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2948 						  commands);
2949 
2950 	error = sctp_eat_data(asoc, chunk, commands);
2951 	switch (error) {
2952 	case SCTP_IERROR_NO_ERROR:
2953 		break;
2954 	case SCTP_IERROR_HIGH_TSN:
2955 	case SCTP_IERROR_BAD_STREAM:
2956 		SCTP_INC_STATS(net, SCTP_MIB_IN_DATA_CHUNK_DISCARDS);
2957 		goto discard_noforce;
2958 	case SCTP_IERROR_DUP_TSN:
2959 	case SCTP_IERROR_IGNORE_TSN:
2960 		SCTP_INC_STATS(net, SCTP_MIB_IN_DATA_CHUNK_DISCARDS);
2961 		goto discard_force;
2962 	case SCTP_IERROR_NO_DATA:
2963 		goto consume;
2964 	case SCTP_IERROR_PROTO_VIOLATION:
2965 		return sctp_sf_abort_violation(net, ep, asoc, chunk, commands,
2966 			(u8 *)chunk->subh.data_hdr, sizeof(sctp_datahdr_t));
2967 	default:
2968 		BUG();
2969 	}
2970 
2971 	if (chunk->chunk_hdr->flags & SCTP_DATA_SACK_IMM)
2972 		force = SCTP_FORCE();
2973 
2974 	if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) {
2975 		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
2976 				SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
2977 	}
2978 
2979 	/* If this is the last chunk in a packet, we need to count it
2980 	 * toward sack generation.  Note that we need to SACK every
2981 	 * OTHER packet containing data chunks, EVEN IF WE DISCARD
2982 	 * THEM.  We elect to NOT generate SACK's if the chunk fails
2983 	 * the verification tag test.
2984 	 *
2985 	 * RFC 2960 6.2 Acknowledgement on Reception of DATA Chunks
2986 	 *
2987 	 * The SCTP endpoint MUST always acknowledge the reception of
2988 	 * each valid DATA chunk.
2989 	 *
2990 	 * The guidelines on delayed acknowledgement algorithm
2991 	 * specified in  Section 4.2 of [RFC2581] SHOULD be followed.
2992 	 * Specifically, an acknowledgement SHOULD be generated for at
2993 	 * least every second packet (not every second DATA chunk)
2994 	 * received, and SHOULD be generated within 200 ms of the
2995 	 * arrival of any unacknowledged DATA chunk.  In some
2996 	 * situations it may be beneficial for an SCTP transmitter to
2997 	 * be more conservative than the algorithms detailed in this
2998 	 * document allow. However, an SCTP transmitter MUST NOT be
2999 	 * more aggressive than the following algorithms allow.
3000 	 */
3001 	if (chunk->end_of_packet)
3002 		sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, force);
3003 
3004 	return SCTP_DISPOSITION_CONSUME;
3005 
3006 discard_force:
3007 	/* RFC 2960 6.2 Acknowledgement on Reception of DATA Chunks
3008 	 *
3009 	 * When a packet arrives with duplicate DATA chunk(s) and with
3010 	 * no new DATA chunk(s), the endpoint MUST immediately send a
3011 	 * SACK with no delay.  If a packet arrives with duplicate
3012 	 * DATA chunk(s) bundled with new DATA chunks, the endpoint
3013 	 * MAY immediately send a SACK.  Normally receipt of duplicate
3014 	 * DATA chunks will occur when the original SACK chunk was lost
3015 	 * and the peer's RTO has expired.  The duplicate TSN number(s)
3016 	 * SHOULD be reported in the SACK as duplicate.
3017 	 */
3018 	/* In our case, we split the MAY SACK advice up whether or not
3019 	 * the last chunk is a duplicate.'
3020 	 */
3021 	if (chunk->end_of_packet)
3022 		sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
3023 	return SCTP_DISPOSITION_DISCARD;
3024 
3025 discard_noforce:
3026 	if (chunk->end_of_packet)
3027 		sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, force);
3028 
3029 	return SCTP_DISPOSITION_DISCARD;
3030 consume:
3031 	return SCTP_DISPOSITION_CONSUME;
3032 
3033 }
3034 
3035 /*
3036  * sctp_sf_eat_data_fast_4_4
3037  *
3038  * Section: 4 (4)
3039  * (4) In SHUTDOWN-SENT state the endpoint MUST acknowledge any received
3040  *    DATA chunks without delay.
3041  *
3042  * Verification Tag:  8.5 Verification Tag [Normal verification]
3043  * Inputs
3044  * (endpoint, asoc, chunk)
3045  *
3046  * Outputs
3047  * (asoc, reply_msg, msg_up, timers, counters)
3048  *
3049  * The return value is the disposition of the chunk.
3050  */
3051 sctp_disposition_t sctp_sf_eat_data_fast_4_4(struct net *net,
3052 				     const struct sctp_endpoint *ep,
3053 				     const struct sctp_association *asoc,
3054 				     const sctp_subtype_t type,
3055 				     void *arg,
3056 				     sctp_cmd_seq_t *commands)
3057 {
3058 	struct sctp_chunk *chunk = arg;
3059 	int error;
3060 
3061 	if (!sctp_vtag_verify(chunk, asoc)) {
3062 		sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
3063 				SCTP_NULL());
3064 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3065 	}
3066 
3067 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_data_chunk_t)))
3068 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3069 						  commands);
3070 
3071 	error = sctp_eat_data(asoc, chunk, commands);
3072 	switch (error) {
3073 	case SCTP_IERROR_NO_ERROR:
3074 	case SCTP_IERROR_HIGH_TSN:
3075 	case SCTP_IERROR_DUP_TSN:
3076 	case SCTP_IERROR_IGNORE_TSN:
3077 	case SCTP_IERROR_BAD_STREAM:
3078 		break;
3079 	case SCTP_IERROR_NO_DATA:
3080 		goto consume;
3081 	case SCTP_IERROR_PROTO_VIOLATION:
3082 		return sctp_sf_abort_violation(net, ep, asoc, chunk, commands,
3083 			(u8 *)chunk->subh.data_hdr, sizeof(sctp_datahdr_t));
3084 	default:
3085 		BUG();
3086 	}
3087 
3088 	/* Go a head and force a SACK, since we are shutting down. */
3089 
3090 	/* Implementor's Guide.
3091 	 *
3092 	 * While in SHUTDOWN-SENT state, the SHUTDOWN sender MUST immediately
3093 	 * respond to each received packet containing one or more DATA chunk(s)
3094 	 * with a SACK, a SHUTDOWN chunk, and restart the T2-shutdown timer
3095 	 */
3096 	if (chunk->end_of_packet) {
3097 		/* We must delay the chunk creation since the cumulative
3098 		 * TSN has not been updated yet.
3099 		 */
3100 		sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SHUTDOWN, SCTP_NULL());
3101 		sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
3102 		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
3103 				SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
3104 	}
3105 
3106 consume:
3107 	return SCTP_DISPOSITION_CONSUME;
3108 }
3109 
3110 /*
3111  * Section: 6.2  Processing a Received SACK
3112  * D) Any time a SACK arrives, the endpoint performs the following:
3113  *
3114  *     i) If Cumulative TSN Ack is less than the Cumulative TSN Ack Point,
3115  *     then drop the SACK.   Since Cumulative TSN Ack is monotonically
3116  *     increasing, a SACK whose Cumulative TSN Ack is less than the
3117  *     Cumulative TSN Ack Point indicates an out-of-order SACK.
3118  *
3119  *     ii) Set rwnd equal to the newly received a_rwnd minus the number
3120  *     of bytes still outstanding after processing the Cumulative TSN Ack
3121  *     and the Gap Ack Blocks.
3122  *
3123  *     iii) If the SACK is missing a TSN that was previously
3124  *     acknowledged via a Gap Ack Block (e.g., the data receiver
3125  *     reneged on the data), then mark the corresponding DATA chunk
3126  *     as available for retransmit:  Mark it as missing for fast
3127  *     retransmit as described in Section 7.2.4 and if no retransmit
3128  *     timer is running for the destination address to which the DATA
3129  *     chunk was originally transmitted, then T3-rtx is started for
3130  *     that destination address.
3131  *
3132  * Verification Tag:  8.5 Verification Tag [Normal verification]
3133  *
3134  * Inputs
3135  * (endpoint, asoc, chunk)
3136  *
3137  * Outputs
3138  * (asoc, reply_msg, msg_up, timers, counters)
3139  *
3140  * The return value is the disposition of the chunk.
3141  */
3142 sctp_disposition_t sctp_sf_eat_sack_6_2(struct net *net,
3143 					const struct sctp_endpoint *ep,
3144 					const struct sctp_association *asoc,
3145 					const sctp_subtype_t type,
3146 					void *arg,
3147 					sctp_cmd_seq_t *commands)
3148 {
3149 	struct sctp_chunk *chunk = arg;
3150 	sctp_sackhdr_t *sackh;
3151 	__u32 ctsn;
3152 
3153 	if (!sctp_vtag_verify(chunk, asoc))
3154 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3155 
3156 	/* Make sure that the SACK chunk has a valid length. */
3157 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_sack_chunk_t)))
3158 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3159 						  commands);
3160 
3161 	/* Pull the SACK chunk from the data buffer */
3162 	sackh = sctp_sm_pull_sack(chunk);
3163 	/* Was this a bogus SACK? */
3164 	if (!sackh)
3165 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3166 	chunk->subh.sack_hdr = sackh;
3167 	ctsn = ntohl(sackh->cum_tsn_ack);
3168 
3169 	/* i) If Cumulative TSN Ack is less than the Cumulative TSN
3170 	 *     Ack Point, then drop the SACK.  Since Cumulative TSN
3171 	 *     Ack is monotonically increasing, a SACK whose
3172 	 *     Cumulative TSN Ack is less than the Cumulative TSN Ack
3173 	 *     Point indicates an out-of-order SACK.
3174 	 */
3175 	if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
3176 		pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn,
3177 			 asoc->ctsn_ack_point);
3178 
3179 		return SCTP_DISPOSITION_DISCARD;
3180 	}
3181 
3182 	/* If Cumulative TSN Ack beyond the max tsn currently
3183 	 * send, terminating the association and respond to the
3184 	 * sender with an ABORT.
3185 	 */
3186 	if (!TSN_lt(ctsn, asoc->next_tsn))
3187 		return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands);
3188 
3189 	/* Return this SACK for further processing.  */
3190 	sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_SACK, SCTP_CHUNK(chunk));
3191 
3192 	/* Note: We do the rest of the work on the PROCESS_SACK
3193 	 * sideeffect.
3194 	 */
3195 	return SCTP_DISPOSITION_CONSUME;
3196 }
3197 
3198 /*
3199  * Generate an ABORT in response to a packet.
3200  *
3201  * Section: 8.4 Handle "Out of the blue" Packets, sctpimpguide 2.41
3202  *
3203  * 8) The receiver should respond to the sender of the OOTB packet with
3204  *    an ABORT.  When sending the ABORT, the receiver of the OOTB packet
3205  *    MUST fill in the Verification Tag field of the outbound packet
3206  *    with the value found in the Verification Tag field of the OOTB
3207  *    packet and set the T-bit in the Chunk Flags to indicate that the
3208  *    Verification Tag is reflected.  After sending this ABORT, the
3209  *    receiver of the OOTB packet shall discard the OOTB packet and take
3210  *    no further action.
3211  *
3212  * Verification Tag:
3213  *
3214  * The return value is the disposition of the chunk.
3215 */
3216 static sctp_disposition_t sctp_sf_tabort_8_4_8(struct net *net,
3217 					const struct sctp_endpoint *ep,
3218 					const struct sctp_association *asoc,
3219 					const sctp_subtype_t type,
3220 					void *arg,
3221 					sctp_cmd_seq_t *commands)
3222 {
3223 	struct sctp_packet *packet = NULL;
3224 	struct sctp_chunk *chunk = arg;
3225 	struct sctp_chunk *abort;
3226 
3227 	packet = sctp_ootb_pkt_new(net, asoc, chunk);
3228 
3229 	if (packet) {
3230 		/* Make an ABORT. The T bit will be set if the asoc
3231 		 * is NULL.
3232 		 */
3233 		abort = sctp_make_abort(asoc, chunk, 0);
3234 		if (!abort) {
3235 			sctp_ootb_pkt_free(packet);
3236 			return SCTP_DISPOSITION_NOMEM;
3237 		}
3238 
3239 		/* Reflect vtag if T-Bit is set */
3240 		if (sctp_test_T_bit(abort))
3241 			packet->vtag = ntohl(chunk->sctp_hdr->vtag);
3242 
3243 		/* Set the skb to the belonging sock for accounting.  */
3244 		abort->skb->sk = ep->base.sk;
3245 
3246 		sctp_packet_append_chunk(packet, abort);
3247 
3248 		sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
3249 				SCTP_PACKET(packet));
3250 
3251 		SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
3252 
3253 		sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3254 		return SCTP_DISPOSITION_CONSUME;
3255 	}
3256 
3257 	return SCTP_DISPOSITION_NOMEM;
3258 }
3259 
3260 /*
3261  * Received an ERROR chunk from peer.  Generate SCTP_REMOTE_ERROR
3262  * event as ULP notification for each cause included in the chunk.
3263  *
3264  * API 5.3.1.3 - SCTP_REMOTE_ERROR
3265  *
3266  * The return value is the disposition of the chunk.
3267 */
3268 sctp_disposition_t sctp_sf_operr_notify(struct net *net,
3269 					const struct sctp_endpoint *ep,
3270 					const struct sctp_association *asoc,
3271 					const sctp_subtype_t type,
3272 					void *arg,
3273 					sctp_cmd_seq_t *commands)
3274 {
3275 	struct sctp_chunk *chunk = arg;
3276 	sctp_errhdr_t *err;
3277 
3278 	if (!sctp_vtag_verify(chunk, asoc))
3279 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3280 
3281 	/* Make sure that the ERROR chunk has a valid length. */
3282 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_operr_chunk_t)))
3283 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3284 						  commands);
3285 	sctp_walk_errors(err, chunk->chunk_hdr);
3286 	if ((void *)err != (void *)chunk->chunk_end)
3287 		return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
3288 						  (void *)err, commands);
3289 
3290 	sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_OPERR,
3291 			SCTP_CHUNK(chunk));
3292 
3293 	return SCTP_DISPOSITION_CONSUME;
3294 }
3295 
3296 /*
3297  * Process an inbound SHUTDOWN ACK.
3298  *
3299  * From Section 9.2:
3300  * Upon the receipt of the SHUTDOWN ACK, the SHUTDOWN sender shall
3301  * stop the T2-shutdown timer, send a SHUTDOWN COMPLETE chunk to its
3302  * peer, and remove all record of the association.
3303  *
3304  * The return value is the disposition.
3305  */
3306 sctp_disposition_t sctp_sf_do_9_2_final(struct net *net,
3307 					const struct sctp_endpoint *ep,
3308 					const struct sctp_association *asoc,
3309 					const sctp_subtype_t type,
3310 					void *arg,
3311 					sctp_cmd_seq_t *commands)
3312 {
3313 	struct sctp_chunk *chunk = arg;
3314 	struct sctp_chunk *reply;
3315 	struct sctp_ulpevent *ev;
3316 
3317 	if (!sctp_vtag_verify(chunk, asoc))
3318 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3319 
3320 	/* Make sure that the SHUTDOWN_ACK chunk has a valid length. */
3321 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
3322 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3323 						  commands);
3324 	/* 10.2 H) SHUTDOWN COMPLETE notification
3325 	 *
3326 	 * When SCTP completes the shutdown procedures (section 9.2) this
3327 	 * notification is passed to the upper layer.
3328 	 */
3329 	ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_SHUTDOWN_COMP,
3330 					     0, 0, 0, NULL, GFP_ATOMIC);
3331 	if (!ev)
3332 		goto nomem;
3333 
3334 	/* ...send a SHUTDOWN COMPLETE chunk to its peer, */
3335 	reply = sctp_make_shutdown_complete(asoc, chunk);
3336 	if (!reply)
3337 		goto nomem_chunk;
3338 
3339 	/* Do all the commands now (after allocation), so that we
3340 	 * have consistent state if memory allocation failes
3341 	 */
3342 	sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
3343 
3344 	/* Upon the receipt of the SHUTDOWN ACK, the SHUTDOWN sender shall
3345 	 * stop the T2-shutdown timer,
3346 	 */
3347 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
3348 			SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
3349 
3350 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
3351 			SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
3352 
3353 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
3354 			SCTP_STATE(SCTP_STATE_CLOSED));
3355 	SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS);
3356 	SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
3357 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
3358 
3359 	/* ...and remove all record of the association. */
3360 	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
3361 	return SCTP_DISPOSITION_DELETE_TCB;
3362 
3363 nomem_chunk:
3364 	sctp_ulpevent_free(ev);
3365 nomem:
3366 	return SCTP_DISPOSITION_NOMEM;
3367 }
3368 
3369 /*
3370  * RFC 2960, 8.4 - Handle "Out of the blue" Packets, sctpimpguide 2.41.
3371  *
3372  * 5) If the packet contains a SHUTDOWN ACK chunk, the receiver should
3373  *    respond to the sender of the OOTB packet with a SHUTDOWN COMPLETE.
3374  *    When sending the SHUTDOWN COMPLETE, the receiver of the OOTB
3375  *    packet must fill in the Verification Tag field of the outbound
3376  *    packet with the Verification Tag received in the SHUTDOWN ACK and
3377  *    set the T-bit in the Chunk Flags to indicate that the Verification
3378  *    Tag is reflected.
3379  *
3380  * 8) The receiver should respond to the sender of the OOTB packet with
3381  *    an ABORT.  When sending the ABORT, the receiver of the OOTB packet
3382  *    MUST fill in the Verification Tag field of the outbound packet
3383  *    with the value found in the Verification Tag field of the OOTB
3384  *    packet and set the T-bit in the Chunk Flags to indicate that the
3385  *    Verification Tag is reflected.  After sending this ABORT, the
3386  *    receiver of the OOTB packet shall discard the OOTB packet and take
3387  *    no further action.
3388  */
3389 sctp_disposition_t sctp_sf_ootb(struct net *net,
3390 				const struct sctp_endpoint *ep,
3391 				const struct sctp_association *asoc,
3392 				const sctp_subtype_t type,
3393 				void *arg,
3394 				sctp_cmd_seq_t *commands)
3395 {
3396 	struct sctp_chunk *chunk = arg;
3397 	struct sk_buff *skb = chunk->skb;
3398 	sctp_chunkhdr_t *ch;
3399 	sctp_errhdr_t *err;
3400 	__u8 *ch_end;
3401 	int ootb_shut_ack = 0;
3402 	int ootb_cookie_ack = 0;
3403 
3404 	SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
3405 
3406 	ch = (sctp_chunkhdr_t *) chunk->chunk_hdr;
3407 	do {
3408 		/* Report violation if the chunk is less then minimal */
3409 		if (ntohs(ch->length) < sizeof(sctp_chunkhdr_t))
3410 			return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3411 						  commands);
3412 
3413 		/* Now that we know we at least have a chunk header,
3414 		 * do things that are type appropriate.
3415 		 */
3416 		if (SCTP_CID_SHUTDOWN_ACK == ch->type)
3417 			ootb_shut_ack = 1;
3418 
3419 		/* RFC 2960, Section 3.3.7
3420 		 *   Moreover, under any circumstances, an endpoint that
3421 		 *   receives an ABORT  MUST NOT respond to that ABORT by
3422 		 *   sending an ABORT of its own.
3423 		 */
3424 		if (SCTP_CID_ABORT == ch->type)
3425 			return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3426 
3427 		/* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR
3428 		 * or a COOKIE ACK the SCTP Packet should be silently
3429 		 * discarded.
3430 		 */
3431 
3432 		if (SCTP_CID_COOKIE_ACK == ch->type)
3433 			ootb_cookie_ack = 1;
3434 
3435 		if (SCTP_CID_ERROR == ch->type) {
3436 			sctp_walk_errors(err, ch) {
3437 				if (SCTP_ERROR_STALE_COOKIE == err->cause) {
3438 					ootb_cookie_ack = 1;
3439 					break;
3440 				}
3441 			}
3442 		}
3443 
3444 		/* Report violation if chunk len overflows */
3445 		ch_end = ((__u8 *)ch) + WORD_ROUND(ntohs(ch->length));
3446 		if (ch_end > skb_tail_pointer(skb))
3447 			return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3448 						  commands);
3449 
3450 		ch = (sctp_chunkhdr_t *) ch_end;
3451 	} while (ch_end < skb_tail_pointer(skb));
3452 
3453 	if (ootb_shut_ack)
3454 		return sctp_sf_shut_8_4_5(net, ep, asoc, type, arg, commands);
3455 	else if (ootb_cookie_ack)
3456 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3457 	else
3458 		return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
3459 }
3460 
3461 /*
3462  * Handle an "Out of the blue" SHUTDOWN ACK.
3463  *
3464  * Section: 8.4 5, sctpimpguide 2.41.
3465  *
3466  * 5) If the packet contains a SHUTDOWN ACK chunk, the receiver should
3467  *    respond to the sender of the OOTB packet with a SHUTDOWN COMPLETE.
3468  *    When sending the SHUTDOWN COMPLETE, the receiver of the OOTB
3469  *    packet must fill in the Verification Tag field of the outbound
3470  *    packet with the Verification Tag received in the SHUTDOWN ACK and
3471  *    set the T-bit in the Chunk Flags to indicate that the Verification
3472  *    Tag is reflected.
3473  *
3474  * Inputs
3475  * (endpoint, asoc, type, arg, commands)
3476  *
3477  * Outputs
3478  * (sctp_disposition_t)
3479  *
3480  * The return value is the disposition of the chunk.
3481  */
3482 static sctp_disposition_t sctp_sf_shut_8_4_5(struct net *net,
3483 					     const struct sctp_endpoint *ep,
3484 					     const struct sctp_association *asoc,
3485 					     const sctp_subtype_t type,
3486 					     void *arg,
3487 					     sctp_cmd_seq_t *commands)
3488 {
3489 	struct sctp_packet *packet = NULL;
3490 	struct sctp_chunk *chunk = arg;
3491 	struct sctp_chunk *shut;
3492 
3493 	packet = sctp_ootb_pkt_new(net, asoc, chunk);
3494 
3495 	if (packet) {
3496 		/* Make an SHUTDOWN_COMPLETE.
3497 		 * The T bit will be set if the asoc is NULL.
3498 		 */
3499 		shut = sctp_make_shutdown_complete(asoc, chunk);
3500 		if (!shut) {
3501 			sctp_ootb_pkt_free(packet);
3502 			return SCTP_DISPOSITION_NOMEM;
3503 		}
3504 
3505 		/* Reflect vtag if T-Bit is set */
3506 		if (sctp_test_T_bit(shut))
3507 			packet->vtag = ntohl(chunk->sctp_hdr->vtag);
3508 
3509 		/* Set the skb to the belonging sock for accounting.  */
3510 		shut->skb->sk = ep->base.sk;
3511 
3512 		sctp_packet_append_chunk(packet, shut);
3513 
3514 		sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
3515 				SCTP_PACKET(packet));
3516 
3517 		SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
3518 
3519 		/* If the chunk length is invalid, we don't want to process
3520 		 * the reset of the packet.
3521 		 */
3522 		if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
3523 			return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3524 
3525 		/* We need to discard the rest of the packet to prevent
3526 		 * potential bomming attacks from additional bundled chunks.
3527 		 * This is documented in SCTP Threats ID.
3528 		 */
3529 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3530 	}
3531 
3532 	return SCTP_DISPOSITION_NOMEM;
3533 }
3534 
3535 /*
3536  * Handle SHUTDOWN ACK in COOKIE_ECHOED or COOKIE_WAIT state.
3537  *
3538  * Verification Tag:  8.5.1 E) Rules for packet carrying a SHUTDOWN ACK
3539  *   If the receiver is in COOKIE-ECHOED or COOKIE-WAIT state the
3540  *   procedures in section 8.4 SHOULD be followed, in other words it
3541  *   should be treated as an Out Of The Blue packet.
3542  *   [This means that we do NOT check the Verification Tag on these
3543  *   chunks. --piggy ]
3544  *
3545  */
3546 sctp_disposition_t sctp_sf_do_8_5_1_E_sa(struct net *net,
3547 				      const struct sctp_endpoint *ep,
3548 				      const struct sctp_association *asoc,
3549 				      const sctp_subtype_t type,
3550 				      void *arg,
3551 				      sctp_cmd_seq_t *commands)
3552 {
3553 	struct sctp_chunk *chunk = arg;
3554 
3555 	/* Make sure that the SHUTDOWN_ACK chunk has a valid length. */
3556 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
3557 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3558 						  commands);
3559 
3560 	/* Although we do have an association in this case, it corresponds
3561 	 * to a restarted association. So the packet is treated as an OOTB
3562 	 * packet and the state function that handles OOTB SHUTDOWN_ACK is
3563 	 * called with a NULL association.
3564 	 */
3565 	SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
3566 
3567 	return sctp_sf_shut_8_4_5(net, ep, NULL, type, arg, commands);
3568 }
3569 
3570 /* ADDIP Section 4.2 Upon reception of an ASCONF Chunk.  */
3571 sctp_disposition_t sctp_sf_do_asconf(struct net *net,
3572 				     const struct sctp_endpoint *ep,
3573 				     const struct sctp_association *asoc,
3574 				     const sctp_subtype_t type, void *arg,
3575 				     sctp_cmd_seq_t *commands)
3576 {
3577 	struct sctp_chunk	*chunk = arg;
3578 	struct sctp_chunk	*asconf_ack = NULL;
3579 	struct sctp_paramhdr	*err_param = NULL;
3580 	sctp_addiphdr_t		*hdr;
3581 	union sctp_addr_param	*addr_param;
3582 	__u32			serial;
3583 	int			length;
3584 
3585 	if (!sctp_vtag_verify(chunk, asoc)) {
3586 		sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
3587 				SCTP_NULL());
3588 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3589 	}
3590 
3591 	/* ADD-IP: Section 4.1.1
3592 	 * This chunk MUST be sent in an authenticated way by using
3593 	 * the mechanism defined in [I-D.ietf-tsvwg-sctp-auth]. If this chunk
3594 	 * is received unauthenticated it MUST be silently discarded as
3595 	 * described in [I-D.ietf-tsvwg-sctp-auth].
3596 	 */
3597 	if (!net->sctp.addip_noauth && !chunk->auth)
3598 		return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands);
3599 
3600 	/* Make sure that the ASCONF ADDIP chunk has a valid length.  */
3601 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_addip_chunk_t)))
3602 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3603 						  commands);
3604 
3605 	hdr = (sctp_addiphdr_t *)chunk->skb->data;
3606 	serial = ntohl(hdr->serial);
3607 
3608 	addr_param = (union sctp_addr_param *)hdr->params;
3609 	length = ntohs(addr_param->p.length);
3610 	if (length < sizeof(sctp_paramhdr_t))
3611 		return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
3612 			   (void *)addr_param, commands);
3613 
3614 	/* Verify the ASCONF chunk before processing it. */
3615 	if (!sctp_verify_asconf(asoc,
3616 			    (sctp_paramhdr_t *)((void *)addr_param + length),
3617 			    (void *)chunk->chunk_end,
3618 			    &err_param))
3619 		return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
3620 						  (void *)err_param, commands);
3621 
3622 	/* ADDIP 5.2 E1) Compare the value of the serial number to the value
3623 	 * the endpoint stored in a new association variable
3624 	 * 'Peer-Serial-Number'.
3625 	 */
3626 	if (serial == asoc->peer.addip_serial + 1) {
3627 		/* If this is the first instance of ASCONF in the packet,
3628 		 * we can clean our old ASCONF-ACKs.
3629 		 */
3630 		if (!chunk->has_asconf)
3631 			sctp_assoc_clean_asconf_ack_cache(asoc);
3632 
3633 		/* ADDIP 5.2 E4) When the Sequence Number matches the next one
3634 		 * expected, process the ASCONF as described below and after
3635 		 * processing the ASCONF Chunk, append an ASCONF-ACK Chunk to
3636 		 * the response packet and cache a copy of it (in the event it
3637 		 * later needs to be retransmitted).
3638 		 *
3639 		 * Essentially, do V1-V5.
3640 		 */
3641 		asconf_ack = sctp_process_asconf((struct sctp_association *)
3642 						 asoc, chunk);
3643 		if (!asconf_ack)
3644 			return SCTP_DISPOSITION_NOMEM;
3645 	} else if (serial < asoc->peer.addip_serial + 1) {
3646 		/* ADDIP 5.2 E2)
3647 		 * If the value found in the Sequence Number is less than the
3648 		 * ('Peer- Sequence-Number' + 1), simply skip to the next
3649 		 * ASCONF, and include in the outbound response packet
3650 		 * any previously cached ASCONF-ACK response that was
3651 		 * sent and saved that matches the Sequence Number of the
3652 		 * ASCONF.  Note: It is possible that no cached ASCONF-ACK
3653 		 * Chunk exists.  This will occur when an older ASCONF
3654 		 * arrives out of order.  In such a case, the receiver
3655 		 * should skip the ASCONF Chunk and not include ASCONF-ACK
3656 		 * Chunk for that chunk.
3657 		 */
3658 		asconf_ack = sctp_assoc_lookup_asconf_ack(asoc, hdr->serial);
3659 		if (!asconf_ack)
3660 			return SCTP_DISPOSITION_DISCARD;
3661 
3662 		/* Reset the transport so that we select the correct one
3663 		 * this time around.  This is to make sure that we don't
3664 		 * accidentally use a stale transport that's been removed.
3665 		 */
3666 		asconf_ack->transport = NULL;
3667 	} else {
3668 		/* ADDIP 5.2 E5) Otherwise, the ASCONF Chunk is discarded since
3669 		 * it must be either a stale packet or from an attacker.
3670 		 */
3671 		return SCTP_DISPOSITION_DISCARD;
3672 	}
3673 
3674 	/* ADDIP 5.2 E6)  The destination address of the SCTP packet
3675 	 * containing the ASCONF-ACK Chunks MUST be the source address of
3676 	 * the SCTP packet that held the ASCONF Chunks.
3677 	 *
3678 	 * To do this properly, we'll set the destination address of the chunk
3679 	 * and at the transmit time, will try look up the transport to use.
3680 	 * Since ASCONFs may be bundled, the correct transport may not be
3681 	 * created until we process the entire packet, thus this workaround.
3682 	 */
3683 	asconf_ack->dest = chunk->source;
3684 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(asconf_ack));
3685 	if (asoc->new_transport) {
3686 		sctp_sf_heartbeat(ep, asoc, type, asoc->new_transport, commands);
3687 		((struct sctp_association *)asoc)->new_transport = NULL;
3688 	}
3689 
3690 	return SCTP_DISPOSITION_CONSUME;
3691 }
3692 
3693 /*
3694  * ADDIP Section 4.3 General rules for address manipulation
3695  * When building TLV parameters for the ASCONF Chunk that will add or
3696  * delete IP addresses the D0 to D13 rules should be applied:
3697  */
3698 sctp_disposition_t sctp_sf_do_asconf_ack(struct net *net,
3699 					 const struct sctp_endpoint *ep,
3700 					 const struct sctp_association *asoc,
3701 					 const sctp_subtype_t type, void *arg,
3702 					 sctp_cmd_seq_t *commands)
3703 {
3704 	struct sctp_chunk	*asconf_ack = arg;
3705 	struct sctp_chunk	*last_asconf = asoc->addip_last_asconf;
3706 	struct sctp_chunk	*abort;
3707 	struct sctp_paramhdr	*err_param = NULL;
3708 	sctp_addiphdr_t		*addip_hdr;
3709 	__u32			sent_serial, rcvd_serial;
3710 
3711 	if (!sctp_vtag_verify(asconf_ack, asoc)) {
3712 		sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
3713 				SCTP_NULL());
3714 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3715 	}
3716 
3717 	/* ADD-IP, Section 4.1.2:
3718 	 * This chunk MUST be sent in an authenticated way by using
3719 	 * the mechanism defined in [I-D.ietf-tsvwg-sctp-auth]. If this chunk
3720 	 * is received unauthenticated it MUST be silently discarded as
3721 	 * described in [I-D.ietf-tsvwg-sctp-auth].
3722 	 */
3723 	if (!net->sctp.addip_noauth && !asconf_ack->auth)
3724 		return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands);
3725 
3726 	/* Make sure that the ADDIP chunk has a valid length.  */
3727 	if (!sctp_chunk_length_valid(asconf_ack, sizeof(sctp_addip_chunk_t)))
3728 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3729 						  commands);
3730 
3731 	addip_hdr = (sctp_addiphdr_t *)asconf_ack->skb->data;
3732 	rcvd_serial = ntohl(addip_hdr->serial);
3733 
3734 	/* Verify the ASCONF-ACK chunk before processing it. */
3735 	if (!sctp_verify_asconf(asoc,
3736 	    (sctp_paramhdr_t *)addip_hdr->params,
3737 	    (void *)asconf_ack->chunk_end,
3738 	    &err_param))
3739 		return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
3740 			   (void *)err_param, commands);
3741 
3742 	if (last_asconf) {
3743 		addip_hdr = (sctp_addiphdr_t *)last_asconf->subh.addip_hdr;
3744 		sent_serial = ntohl(addip_hdr->serial);
3745 	} else {
3746 		sent_serial = asoc->addip_serial - 1;
3747 	}
3748 
3749 	/* D0) If an endpoint receives an ASCONF-ACK that is greater than or
3750 	 * equal to the next serial number to be used but no ASCONF chunk is
3751 	 * outstanding the endpoint MUST ABORT the association. Note that a
3752 	 * sequence number is greater than if it is no more than 2^^31-1
3753 	 * larger than the current sequence number (using serial arithmetic).
3754 	 */
3755 	if (ADDIP_SERIAL_gte(rcvd_serial, sent_serial + 1) &&
3756 	    !(asoc->addip_last_asconf)) {
3757 		abort = sctp_make_abort(asoc, asconf_ack,
3758 					sizeof(sctp_errhdr_t));
3759 		if (abort) {
3760 			sctp_init_cause(abort, SCTP_ERROR_ASCONF_ACK, 0);
3761 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
3762 					SCTP_CHUNK(abort));
3763 		}
3764 		/* We are going to ABORT, so we might as well stop
3765 		 * processing the rest of the chunks in the packet.
3766 		 */
3767 		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
3768 				SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
3769 		sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
3770 		sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
3771 				SCTP_ERROR(ECONNABORTED));
3772 		sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
3773 				SCTP_PERR(SCTP_ERROR_ASCONF_ACK));
3774 		SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
3775 		SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
3776 		return SCTP_DISPOSITION_ABORT;
3777 	}
3778 
3779 	if ((rcvd_serial == sent_serial) && asoc->addip_last_asconf) {
3780 		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
3781 				SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
3782 
3783 		if (!sctp_process_asconf_ack((struct sctp_association *)asoc,
3784 					     asconf_ack)) {
3785 			/* Successfully processed ASCONF_ACK.  We can
3786 			 * release the next asconf if we have one.
3787 			 */
3788 			sctp_add_cmd_sf(commands, SCTP_CMD_SEND_NEXT_ASCONF,
3789 					SCTP_NULL());
3790 			return SCTP_DISPOSITION_CONSUME;
3791 		}
3792 
3793 		abort = sctp_make_abort(asoc, asconf_ack,
3794 					sizeof(sctp_errhdr_t));
3795 		if (abort) {
3796 			sctp_init_cause(abort, SCTP_ERROR_RSRC_LOW, 0);
3797 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
3798 					SCTP_CHUNK(abort));
3799 		}
3800 		/* We are going to ABORT, so we might as well stop
3801 		 * processing the rest of the chunks in the packet.
3802 		 */
3803 		sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
3804 		sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
3805 				SCTP_ERROR(ECONNABORTED));
3806 		sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
3807 				SCTP_PERR(SCTP_ERROR_ASCONF_ACK));
3808 		SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
3809 		SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
3810 		return SCTP_DISPOSITION_ABORT;
3811 	}
3812 
3813 	return SCTP_DISPOSITION_DISCARD;
3814 }
3815 
3816 /*
3817  * PR-SCTP Section 3.6 Receiver Side Implementation of PR-SCTP
3818  *
3819  * When a FORWARD TSN chunk arrives, the data receiver MUST first update
3820  * its cumulative TSN point to the value carried in the FORWARD TSN
3821  * chunk, and then MUST further advance its cumulative TSN point locally
3822  * if possible.
3823  * After the above processing, the data receiver MUST stop reporting any
3824  * missing TSNs earlier than or equal to the new cumulative TSN point.
3825  *
3826  * Verification Tag:  8.5 Verification Tag [Normal verification]
3827  *
3828  * The return value is the disposition of the chunk.
3829  */
3830 sctp_disposition_t sctp_sf_eat_fwd_tsn(struct net *net,
3831 				       const struct sctp_endpoint *ep,
3832 				       const struct sctp_association *asoc,
3833 				       const sctp_subtype_t type,
3834 				       void *arg,
3835 				       sctp_cmd_seq_t *commands)
3836 {
3837 	struct sctp_chunk *chunk = arg;
3838 	struct sctp_fwdtsn_hdr *fwdtsn_hdr;
3839 	struct sctp_fwdtsn_skip *skip;
3840 	__u16 len;
3841 	__u32 tsn;
3842 
3843 	if (!sctp_vtag_verify(chunk, asoc)) {
3844 		sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
3845 				SCTP_NULL());
3846 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3847 	}
3848 
3849 	/* Make sure that the FORWARD_TSN chunk has valid length.  */
3850 	if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_fwdtsn_chunk)))
3851 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3852 						  commands);
3853 
3854 	fwdtsn_hdr = (struct sctp_fwdtsn_hdr *)chunk->skb->data;
3855 	chunk->subh.fwdtsn_hdr = fwdtsn_hdr;
3856 	len = ntohs(chunk->chunk_hdr->length);
3857 	len -= sizeof(struct sctp_chunkhdr);
3858 	skb_pull(chunk->skb, len);
3859 
3860 	tsn = ntohl(fwdtsn_hdr->new_cum_tsn);
3861 	pr_debug("%s: TSN 0x%x\n", __func__, tsn);
3862 
3863 	/* The TSN is too high--silently discard the chunk and count on it
3864 	 * getting retransmitted later.
3865 	 */
3866 	if (sctp_tsnmap_check(&asoc->peer.tsn_map, tsn) < 0)
3867 		goto discard_noforce;
3868 
3869 	/* Silently discard the chunk if stream-id is not valid */
3870 	sctp_walk_fwdtsn(skip, chunk) {
3871 		if (ntohs(skip->stream) >= asoc->c.sinit_max_instreams)
3872 			goto discard_noforce;
3873 	}
3874 
3875 	sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_FWDTSN, SCTP_U32(tsn));
3876 	if (len > sizeof(struct sctp_fwdtsn_hdr))
3877 		sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_FWDTSN,
3878 				SCTP_CHUNK(chunk));
3879 
3880 	/* Count this as receiving DATA. */
3881 	if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) {
3882 		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
3883 				SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
3884 	}
3885 
3886 	/* FIXME: For now send a SACK, but DATA processing may
3887 	 * send another.
3888 	 */
3889 	sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_NOFORCE());
3890 
3891 	return SCTP_DISPOSITION_CONSUME;
3892 
3893 discard_noforce:
3894 	return SCTP_DISPOSITION_DISCARD;
3895 }
3896 
3897 sctp_disposition_t sctp_sf_eat_fwd_tsn_fast(
3898 	struct net *net,
3899 	const struct sctp_endpoint *ep,
3900 	const struct sctp_association *asoc,
3901 	const sctp_subtype_t type,
3902 	void *arg,
3903 	sctp_cmd_seq_t *commands)
3904 {
3905 	struct sctp_chunk *chunk = arg;
3906 	struct sctp_fwdtsn_hdr *fwdtsn_hdr;
3907 	struct sctp_fwdtsn_skip *skip;
3908 	__u16 len;
3909 	__u32 tsn;
3910 
3911 	if (!sctp_vtag_verify(chunk, asoc)) {
3912 		sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
3913 				SCTP_NULL());
3914 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3915 	}
3916 
3917 	/* Make sure that the FORWARD_TSN chunk has a valid length.  */
3918 	if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_fwdtsn_chunk)))
3919 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3920 						  commands);
3921 
3922 	fwdtsn_hdr = (struct sctp_fwdtsn_hdr *)chunk->skb->data;
3923 	chunk->subh.fwdtsn_hdr = fwdtsn_hdr;
3924 	len = ntohs(chunk->chunk_hdr->length);
3925 	len -= sizeof(struct sctp_chunkhdr);
3926 	skb_pull(chunk->skb, len);
3927 
3928 	tsn = ntohl(fwdtsn_hdr->new_cum_tsn);
3929 	pr_debug("%s: TSN 0x%x\n", __func__, tsn);
3930 
3931 	/* The TSN is too high--silently discard the chunk and count on it
3932 	 * getting retransmitted later.
3933 	 */
3934 	if (sctp_tsnmap_check(&asoc->peer.tsn_map, tsn) < 0)
3935 		goto gen_shutdown;
3936 
3937 	/* Silently discard the chunk if stream-id is not valid */
3938 	sctp_walk_fwdtsn(skip, chunk) {
3939 		if (ntohs(skip->stream) >= asoc->c.sinit_max_instreams)
3940 			goto gen_shutdown;
3941 	}
3942 
3943 	sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_FWDTSN, SCTP_U32(tsn));
3944 	if (len > sizeof(struct sctp_fwdtsn_hdr))
3945 		sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_FWDTSN,
3946 				SCTP_CHUNK(chunk));
3947 
3948 	/* Go a head and force a SACK, since we are shutting down. */
3949 gen_shutdown:
3950 	/* Implementor's Guide.
3951 	 *
3952 	 * While in SHUTDOWN-SENT state, the SHUTDOWN sender MUST immediately
3953 	 * respond to each received packet containing one or more DATA chunk(s)
3954 	 * with a SACK, a SHUTDOWN chunk, and restart the T2-shutdown timer
3955 	 */
3956 	sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SHUTDOWN, SCTP_NULL());
3957 	sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
3958 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
3959 			SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
3960 
3961 	return SCTP_DISPOSITION_CONSUME;
3962 }
3963 
3964 /*
3965  * SCTP-AUTH Section 6.3 Receiving authenticated chukns
3966  *
3967  *    The receiver MUST use the HMAC algorithm indicated in the HMAC
3968  *    Identifier field.  If this algorithm was not specified by the
3969  *    receiver in the HMAC-ALGO parameter in the INIT or INIT-ACK chunk
3970  *    during association setup, the AUTH chunk and all chunks after it MUST
3971  *    be discarded and an ERROR chunk SHOULD be sent with the error cause
3972  *    defined in Section 4.1.
3973  *
3974  *    If an endpoint with no shared key receives a Shared Key Identifier
3975  *    other than 0, it MUST silently discard all authenticated chunks.  If
3976  *    the endpoint has at least one endpoint pair shared key for the peer,
3977  *    it MUST use the key specified by the Shared Key Identifier if a
3978  *    key has been configured for that Shared Key Identifier.  If no
3979  *    endpoint pair shared key has been configured for that Shared Key
3980  *    Identifier, all authenticated chunks MUST be silently discarded.
3981  *
3982  * Verification Tag:  8.5 Verification Tag [Normal verification]
3983  *
3984  * The return value is the disposition of the chunk.
3985  */
3986 static sctp_ierror_t sctp_sf_authenticate(struct net *net,
3987 				    const struct sctp_endpoint *ep,
3988 				    const struct sctp_association *asoc,
3989 				    const sctp_subtype_t type,
3990 				    struct sctp_chunk *chunk)
3991 {
3992 	struct sctp_authhdr *auth_hdr;
3993 	struct sctp_hmac *hmac;
3994 	unsigned int sig_len;
3995 	__u16 key_id;
3996 	__u8 *save_digest;
3997 	__u8 *digest;
3998 
3999 	/* Pull in the auth header, so we can do some more verification */
4000 	auth_hdr = (struct sctp_authhdr *)chunk->skb->data;
4001 	chunk->subh.auth_hdr = auth_hdr;
4002 	skb_pull(chunk->skb, sizeof(struct sctp_authhdr));
4003 
4004 	/* Make sure that we support the HMAC algorithm from the auth
4005 	 * chunk.
4006 	 */
4007 	if (!sctp_auth_asoc_verify_hmac_id(asoc, auth_hdr->hmac_id))
4008 		return SCTP_IERROR_AUTH_BAD_HMAC;
4009 
4010 	/* Make sure that the provided shared key identifier has been
4011 	 * configured
4012 	 */
4013 	key_id = ntohs(auth_hdr->shkey_id);
4014 	if (key_id != asoc->active_key_id && !sctp_auth_get_shkey(asoc, key_id))
4015 		return SCTP_IERROR_AUTH_BAD_KEYID;
4016 
4017 
4018 	/* Make sure that the length of the signature matches what
4019 	 * we expect.
4020 	 */
4021 	sig_len = ntohs(chunk->chunk_hdr->length) - sizeof(sctp_auth_chunk_t);
4022 	hmac = sctp_auth_get_hmac(ntohs(auth_hdr->hmac_id));
4023 	if (sig_len != hmac->hmac_len)
4024 		return SCTP_IERROR_PROTO_VIOLATION;
4025 
4026 	/* Now that we've done validation checks, we can compute and
4027 	 * verify the hmac.  The steps involved are:
4028 	 *  1. Save the digest from the chunk.
4029 	 *  2. Zero out the digest in the chunk.
4030 	 *  3. Compute the new digest
4031 	 *  4. Compare saved and new digests.
4032 	 */
4033 	digest = auth_hdr->hmac;
4034 	skb_pull(chunk->skb, sig_len);
4035 
4036 	save_digest = kmemdup(digest, sig_len, GFP_ATOMIC);
4037 	if (!save_digest)
4038 		goto nomem;
4039 
4040 	memset(digest, 0, sig_len);
4041 
4042 	sctp_auth_calculate_hmac(asoc, chunk->skb,
4043 				(struct sctp_auth_chunk *)chunk->chunk_hdr,
4044 				GFP_ATOMIC);
4045 
4046 	/* Discard the packet if the digests do not match */
4047 	if (memcmp(save_digest, digest, sig_len)) {
4048 		kfree(save_digest);
4049 		return SCTP_IERROR_BAD_SIG;
4050 	}
4051 
4052 	kfree(save_digest);
4053 	chunk->auth = 1;
4054 
4055 	return SCTP_IERROR_NO_ERROR;
4056 nomem:
4057 	return SCTP_IERROR_NOMEM;
4058 }
4059 
4060 sctp_disposition_t sctp_sf_eat_auth(struct net *net,
4061 				    const struct sctp_endpoint *ep,
4062 				    const struct sctp_association *asoc,
4063 				    const sctp_subtype_t type,
4064 				    void *arg,
4065 				    sctp_cmd_seq_t *commands)
4066 {
4067 	struct sctp_authhdr *auth_hdr;
4068 	struct sctp_chunk *chunk = arg;
4069 	struct sctp_chunk *err_chunk;
4070 	sctp_ierror_t error;
4071 
4072 	/* Make sure that the peer has AUTH capable */
4073 	if (!asoc->peer.auth_capable)
4074 		return sctp_sf_unk_chunk(net, ep, asoc, type, arg, commands);
4075 
4076 	if (!sctp_vtag_verify(chunk, asoc)) {
4077 		sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
4078 				SCTP_NULL());
4079 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4080 	}
4081 
4082 	/* Make sure that the AUTH chunk has valid length.  */
4083 	if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_auth_chunk)))
4084 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4085 						  commands);
4086 
4087 	auth_hdr = (struct sctp_authhdr *)chunk->skb->data;
4088 	error = sctp_sf_authenticate(net, ep, asoc, type, chunk);
4089 	switch (error) {
4090 	case SCTP_IERROR_AUTH_BAD_HMAC:
4091 		/* Generate the ERROR chunk and discard the rest
4092 		 * of the packet
4093 		 */
4094 		err_chunk = sctp_make_op_error(asoc, chunk,
4095 					       SCTP_ERROR_UNSUP_HMAC,
4096 					       &auth_hdr->hmac_id,
4097 					       sizeof(__u16), 0);
4098 		if (err_chunk) {
4099 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
4100 					SCTP_CHUNK(err_chunk));
4101 		}
4102 		/* Fall Through */
4103 	case SCTP_IERROR_AUTH_BAD_KEYID:
4104 	case SCTP_IERROR_BAD_SIG:
4105 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4106 
4107 	case SCTP_IERROR_PROTO_VIOLATION:
4108 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4109 						  commands);
4110 
4111 	case SCTP_IERROR_NOMEM:
4112 		return SCTP_DISPOSITION_NOMEM;
4113 
4114 	default:			/* Prevent gcc warnings */
4115 		break;
4116 	}
4117 
4118 	if (asoc->active_key_id != ntohs(auth_hdr->shkey_id)) {
4119 		struct sctp_ulpevent *ev;
4120 
4121 		ev = sctp_ulpevent_make_authkey(asoc, ntohs(auth_hdr->shkey_id),
4122 				    SCTP_AUTH_NEWKEY, GFP_ATOMIC);
4123 
4124 		if (!ev)
4125 			return -ENOMEM;
4126 
4127 		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
4128 				SCTP_ULPEVENT(ev));
4129 	}
4130 
4131 	return SCTP_DISPOSITION_CONSUME;
4132 }
4133 
4134 /*
4135  * Process an unknown chunk.
4136  *
4137  * Section: 3.2. Also, 2.1 in the implementor's guide.
4138  *
4139  * Chunk Types are encoded such that the highest-order two bits specify
4140  * the action that must be taken if the processing endpoint does not
4141  * recognize the Chunk Type.
4142  *
4143  * 00 - Stop processing this SCTP packet and discard it, do not process
4144  *      any further chunks within it.
4145  *
4146  * 01 - Stop processing this SCTP packet and discard it, do not process
4147  *      any further chunks within it, and report the unrecognized
4148  *      chunk in an 'Unrecognized Chunk Type'.
4149  *
4150  * 10 - Skip this chunk and continue processing.
4151  *
4152  * 11 - Skip this chunk and continue processing, but report in an ERROR
4153  *      Chunk using the 'Unrecognized Chunk Type' cause of error.
4154  *
4155  * The return value is the disposition of the chunk.
4156  */
4157 sctp_disposition_t sctp_sf_unk_chunk(struct net *net,
4158 				     const struct sctp_endpoint *ep,
4159 				     const struct sctp_association *asoc,
4160 				     const sctp_subtype_t type,
4161 				     void *arg,
4162 				     sctp_cmd_seq_t *commands)
4163 {
4164 	struct sctp_chunk *unk_chunk = arg;
4165 	struct sctp_chunk *err_chunk;
4166 	sctp_chunkhdr_t *hdr;
4167 
4168 	pr_debug("%s: processing unknown chunk id:%d\n", __func__, type.chunk);
4169 
4170 	if (!sctp_vtag_verify(unk_chunk, asoc))
4171 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4172 
4173 	/* Make sure that the chunk has a valid length.
4174 	 * Since we don't know the chunk type, we use a general
4175 	 * chunkhdr structure to make a comparison.
4176 	 */
4177 	if (!sctp_chunk_length_valid(unk_chunk, sizeof(sctp_chunkhdr_t)))
4178 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4179 						  commands);
4180 
4181 	switch (type.chunk & SCTP_CID_ACTION_MASK) {
4182 	case SCTP_CID_ACTION_DISCARD:
4183 		/* Discard the packet.  */
4184 		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4185 		break;
4186 	case SCTP_CID_ACTION_DISCARD_ERR:
4187 		/* Generate an ERROR chunk as response. */
4188 		hdr = unk_chunk->chunk_hdr;
4189 		err_chunk = sctp_make_op_error(asoc, unk_chunk,
4190 					       SCTP_ERROR_UNKNOWN_CHUNK, hdr,
4191 					       WORD_ROUND(ntohs(hdr->length)),
4192 					       0);
4193 		if (err_chunk) {
4194 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
4195 					SCTP_CHUNK(err_chunk));
4196 		}
4197 
4198 		/* Discard the packet.  */
4199 		sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4200 		return SCTP_DISPOSITION_CONSUME;
4201 		break;
4202 	case SCTP_CID_ACTION_SKIP:
4203 		/* Skip the chunk.  */
4204 		return SCTP_DISPOSITION_DISCARD;
4205 		break;
4206 	case SCTP_CID_ACTION_SKIP_ERR:
4207 		/* Generate an ERROR chunk as response. */
4208 		hdr = unk_chunk->chunk_hdr;
4209 		err_chunk = sctp_make_op_error(asoc, unk_chunk,
4210 					       SCTP_ERROR_UNKNOWN_CHUNK, hdr,
4211 					       WORD_ROUND(ntohs(hdr->length)),
4212 					       0);
4213 		if (err_chunk) {
4214 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
4215 					SCTP_CHUNK(err_chunk));
4216 		}
4217 		/* Skip the chunk.  */
4218 		return SCTP_DISPOSITION_CONSUME;
4219 		break;
4220 	default:
4221 		break;
4222 	}
4223 
4224 	return SCTP_DISPOSITION_DISCARD;
4225 }
4226 
4227 /*
4228  * Discard the chunk.
4229  *
4230  * Section: 0.2, 5.2.3, 5.2.5, 5.2.6, 6.0, 8.4.6, 8.5.1c, 9.2
4231  * [Too numerous to mention...]
4232  * Verification Tag: No verification needed.
4233  * Inputs
4234  * (endpoint, asoc, chunk)
4235  *
4236  * Outputs
4237  * (asoc, reply_msg, msg_up, timers, counters)
4238  *
4239  * The return value is the disposition of the chunk.
4240  */
4241 sctp_disposition_t sctp_sf_discard_chunk(struct net *net,
4242 					 const struct sctp_endpoint *ep,
4243 					 const struct sctp_association *asoc,
4244 					 const sctp_subtype_t type,
4245 					 void *arg,
4246 					 sctp_cmd_seq_t *commands)
4247 {
4248 	struct sctp_chunk *chunk = arg;
4249 
4250 	/* Make sure that the chunk has a valid length.
4251 	 * Since we don't know the chunk type, we use a general
4252 	 * chunkhdr structure to make a comparison.
4253 	 */
4254 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
4255 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4256 						  commands);
4257 
4258 	pr_debug("%s: chunk:%d is discarded\n", __func__, type.chunk);
4259 
4260 	return SCTP_DISPOSITION_DISCARD;
4261 }
4262 
4263 /*
4264  * Discard the whole packet.
4265  *
4266  * Section: 8.4 2)
4267  *
4268  * 2) If the OOTB packet contains an ABORT chunk, the receiver MUST
4269  *    silently discard the OOTB packet and take no further action.
4270  *
4271  * Verification Tag: No verification necessary
4272  *
4273  * Inputs
4274  * (endpoint, asoc, chunk)
4275  *
4276  * Outputs
4277  * (asoc, reply_msg, msg_up, timers, counters)
4278  *
4279  * The return value is the disposition of the chunk.
4280  */
4281 sctp_disposition_t sctp_sf_pdiscard(struct net *net,
4282 				    const struct sctp_endpoint *ep,
4283 				    const struct sctp_association *asoc,
4284 				    const sctp_subtype_t type,
4285 				    void *arg,
4286 				    sctp_cmd_seq_t *commands)
4287 {
4288 	SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS);
4289 	sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
4290 
4291 	return SCTP_DISPOSITION_CONSUME;
4292 }
4293 
4294 
4295 /*
4296  * The other end is violating protocol.
4297  *
4298  * Section: Not specified
4299  * Verification Tag: Not specified
4300  * Inputs
4301  * (endpoint, asoc, chunk)
4302  *
4303  * Outputs
4304  * (asoc, reply_msg, msg_up, timers, counters)
4305  *
4306  * We simply tag the chunk as a violation.  The state machine will log
4307  * the violation and continue.
4308  */
4309 sctp_disposition_t sctp_sf_violation(struct net *net,
4310 				     const struct sctp_endpoint *ep,
4311 				     const struct sctp_association *asoc,
4312 				     const sctp_subtype_t type,
4313 				     void *arg,
4314 				     sctp_cmd_seq_t *commands)
4315 {
4316 	struct sctp_chunk *chunk = arg;
4317 
4318 	/* Make sure that the chunk has a valid length. */
4319 	if (!sctp_chunk_length_valid(chunk, sizeof(sctp_chunkhdr_t)))
4320 		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4321 						  commands);
4322 
4323 	return SCTP_DISPOSITION_VIOLATION;
4324 }
4325 
4326 /*
4327  * Common function to handle a protocol violation.
4328  */
4329 static sctp_disposition_t sctp_sf_abort_violation(
4330 				     struct net *net,
4331 				     const struct sctp_endpoint *ep,
4332 				     const struct sctp_association *asoc,
4333 				     void *arg,
4334 				     sctp_cmd_seq_t *commands,
4335 				     const __u8 *payload,
4336 				     const size_t paylen)
4337 {
4338 	struct sctp_packet *packet = NULL;
4339 	struct sctp_chunk *chunk =  arg;
4340 	struct sctp_chunk *abort = NULL;
4341 
4342 	/* SCTP-AUTH, Section 6.3:
4343 	 *    It should be noted that if the receiver wants to tear
4344 	 *    down an association in an authenticated way only, the
4345 	 *    handling of malformed packets should not result in
4346 	 *    tearing down the association.
4347 	 *
4348 	 * This means that if we only want to abort associations
4349 	 * in an authenticated way (i.e AUTH+ABORT), then we
4350 	 * can't destroy this association just because the packet
4351 	 * was malformed.
4352 	 */
4353 	if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc))
4354 		goto discard;
4355 
4356 	/* Make the abort chunk. */
4357 	abort = sctp_make_abort_violation(asoc, chunk, payload, paylen);
4358 	if (!abort)
4359 		goto nomem;
4360 
4361 	if (asoc) {
4362 		/* Treat INIT-ACK as a special case during COOKIE-WAIT. */
4363 		if (chunk->chunk_hdr->type == SCTP_CID_INIT_ACK &&
4364 		    !asoc->peer.i.init_tag) {
4365 			sctp_initack_chunk_t *initack;
4366 
4367 			initack = (sctp_initack_chunk_t *)chunk->chunk_hdr;
4368 			if (!sctp_chunk_length_valid(chunk,
4369 						     sizeof(sctp_initack_chunk_t)))
4370 				abort->chunk_hdr->flags |= SCTP_CHUNK_FLAG_T;
4371 			else {
4372 				unsigned int inittag;
4373 
4374 				inittag = ntohl(initack->init_hdr.init_tag);
4375 				sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_INITTAG,
4376 						SCTP_U32(inittag));
4377 			}
4378 		}
4379 
4380 		sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
4381 		SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
4382 
4383 		if (asoc->state <= SCTP_STATE_COOKIE_ECHOED) {
4384 			sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
4385 					SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
4386 			sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
4387 					SCTP_ERROR(ECONNREFUSED));
4388 			sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
4389 					SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
4390 		} else {
4391 			sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
4392 					SCTP_ERROR(ECONNABORTED));
4393 			sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
4394 					SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
4395 			SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
4396 		}
4397 	} else {
4398 		packet = sctp_ootb_pkt_new(net, asoc, chunk);
4399 
4400 		if (!packet)
4401 			goto nomem_pkt;
4402 
4403 		if (sctp_test_T_bit(abort))
4404 			packet->vtag = ntohl(chunk->sctp_hdr->vtag);
4405 
4406 		abort->skb->sk = ep->base.sk;
4407 
4408 		sctp_packet_append_chunk(packet, abort);
4409 
4410 		sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
4411 			SCTP_PACKET(packet));
4412 
4413 		SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
4414 	}
4415 
4416 	SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
4417 
4418 discard:
4419 	sctp_sf_pdiscard(net, ep, asoc, SCTP_ST_CHUNK(0), arg, commands);
4420 	return SCTP_DISPOSITION_ABORT;
4421 
4422 nomem_pkt:
4423 	sctp_chunk_free(abort);
4424 nomem:
4425 	return SCTP_DISPOSITION_NOMEM;
4426 }
4427 
4428 /*
4429  * Handle a protocol violation when the chunk length is invalid.
4430  * "Invalid" length is identified as smaller than the minimal length a
4431  * given chunk can be.  For example, a SACK chunk has invalid length
4432  * if its length is set to be smaller than the size of sctp_sack_chunk_t.
4433  *
4434  * We inform the other end by sending an ABORT with a Protocol Violation
4435  * error code.
4436  *
4437  * Section: Not specified
4438  * Verification Tag:  Nothing to do
4439  * Inputs
4440  * (endpoint, asoc, chunk)
4441  *
4442  * Outputs
4443  * (reply_msg, msg_up, counters)
4444  *
4445  * Generate an  ABORT chunk and terminate the association.
4446  */
4447 static sctp_disposition_t sctp_sf_violation_chunklen(
4448 				     struct net *net,
4449 				     const struct sctp_endpoint *ep,
4450 				     const struct sctp_association *asoc,
4451 				     const sctp_subtype_t type,
4452 				     void *arg,
4453 				     sctp_cmd_seq_t *commands)
4454 {
4455 	static const char err_str[] = "The following chunk had invalid length:";
4456 
4457 	return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str,
4458 					sizeof(err_str));
4459 }
4460 
4461 /*
4462  * Handle a protocol violation when the parameter length is invalid.
4463  * If the length is smaller than the minimum length of a given parameter,
4464  * or accumulated length in multi parameters exceeds the end of the chunk,
4465  * the length is considered as invalid.
4466  */
4467 static sctp_disposition_t sctp_sf_violation_paramlen(
4468 				     struct net *net,
4469 				     const struct sctp_endpoint *ep,
4470 				     const struct sctp_association *asoc,
4471 				     const sctp_subtype_t type,
4472 				     void *arg, void *ext,
4473 				     sctp_cmd_seq_t *commands)
4474 {
4475 	struct sctp_chunk *chunk =  arg;
4476 	struct sctp_paramhdr *param = ext;
4477 	struct sctp_chunk *abort = NULL;
4478 
4479 	if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc))
4480 		goto discard;
4481 
4482 	/* Make the abort chunk. */
4483 	abort = sctp_make_violation_paramlen(asoc, chunk, param);
4484 	if (!abort)
4485 		goto nomem;
4486 
4487 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
4488 	SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
4489 
4490 	sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
4491 			SCTP_ERROR(ECONNABORTED));
4492 	sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
4493 			SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
4494 	SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
4495 	SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
4496 
4497 discard:
4498 	sctp_sf_pdiscard(net, ep, asoc, SCTP_ST_CHUNK(0), arg, commands);
4499 	return SCTP_DISPOSITION_ABORT;
4500 nomem:
4501 	return SCTP_DISPOSITION_NOMEM;
4502 }
4503 
4504 /* Handle a protocol violation when the peer trying to advance the
4505  * cumulative tsn ack to a point beyond the max tsn currently sent.
4506  *
4507  * We inform the other end by sending an ABORT with a Protocol Violation
4508  * error code.
4509  */
4510 static sctp_disposition_t sctp_sf_violation_ctsn(
4511 				     struct net *net,
4512 				     const struct sctp_endpoint *ep,
4513 				     const struct sctp_association *asoc,
4514 				     const sctp_subtype_t type,
4515 				     void *arg,
4516 				     sctp_cmd_seq_t *commands)
4517 {
4518 	static const char err_str[] = "The cumulative tsn ack beyond the max tsn currently sent:";
4519 
4520 	return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str,
4521 					sizeof(err_str));
4522 }
4523 
4524 /* Handle protocol violation of an invalid chunk bundling.  For example,
4525  * when we have an association and we receive bundled INIT-ACK, or
4526  * SHUDOWN-COMPLETE, our peer is clearly violationg the "MUST NOT bundle"
4527  * statement from the specs.  Additionally, there might be an attacker
4528  * on the path and we may not want to continue this communication.
4529  */
4530 static sctp_disposition_t sctp_sf_violation_chunk(
4531 				     struct net *net,
4532 				     const struct sctp_endpoint *ep,
4533 				     const struct sctp_association *asoc,
4534 				     const sctp_subtype_t type,
4535 				     void *arg,
4536 				     sctp_cmd_seq_t *commands)
4537 {
4538 	static const char err_str[] = "The following chunk violates protocol:";
4539 
4540 	if (!asoc)
4541 		return sctp_sf_violation(net, ep, asoc, type, arg, commands);
4542 
4543 	return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str,
4544 					sizeof(err_str));
4545 }
4546 /***************************************************************************
4547  * These are the state functions for handling primitive (Section 10) events.
4548  ***************************************************************************/
4549 /*
4550  * sctp_sf_do_prm_asoc
4551  *
4552  * Section: 10.1 ULP-to-SCTP
4553  * B) Associate
4554  *
4555  * Format: ASSOCIATE(local SCTP instance name, destination transport addr,
4556  * outbound stream count)
4557  * -> association id [,destination transport addr list] [,outbound stream
4558  * count]
4559  *
4560  * This primitive allows the upper layer to initiate an association to a
4561  * specific peer endpoint.
4562  *
4563  * The peer endpoint shall be specified by one of the transport addresses
4564  * which defines the endpoint (see Section 1.4).  If the local SCTP
4565  * instance has not been initialized, the ASSOCIATE is considered an
4566  * error.
4567  * [This is not relevant for the kernel implementation since we do all
4568  * initialization at boot time.  It we hadn't initialized we wouldn't
4569  * get anywhere near this code.]
4570  *
4571  * An association id, which is a local handle to the SCTP association,
4572  * will be returned on successful establishment of the association. If
4573  * SCTP is not able to open an SCTP association with the peer endpoint,
4574  * an error is returned.
4575  * [In the kernel implementation, the struct sctp_association needs to
4576  * be created BEFORE causing this primitive to run.]
4577  *
4578  * Other association parameters may be returned, including the
4579  * complete destination transport addresses of the peer as well as the
4580  * outbound stream count of the local endpoint. One of the transport
4581  * address from the returned destination addresses will be selected by
4582  * the local endpoint as default primary path for sending SCTP packets
4583  * to this peer.  The returned "destination transport addr list" can
4584  * be used by the ULP to change the default primary path or to force
4585  * sending a packet to a specific transport address.  [All of this
4586  * stuff happens when the INIT ACK arrives.  This is a NON-BLOCKING
4587  * function.]
4588  *
4589  * Mandatory attributes:
4590  *
4591  * o local SCTP instance name - obtained from the INITIALIZE operation.
4592  *   [This is the argument asoc.]
4593  * o destination transport addr - specified as one of the transport
4594  * addresses of the peer endpoint with which the association is to be
4595  * established.
4596  *  [This is asoc->peer.active_path.]
4597  * o outbound stream count - the number of outbound streams the ULP
4598  * would like to open towards this peer endpoint.
4599  * [BUG: This is not currently implemented.]
4600  * Optional attributes:
4601  *
4602  * None.
4603  *
4604  * The return value is a disposition.
4605  */
4606 sctp_disposition_t sctp_sf_do_prm_asoc(struct net *net,
4607 				       const struct sctp_endpoint *ep,
4608 				       const struct sctp_association *asoc,
4609 				       const sctp_subtype_t type,
4610 				       void *arg,
4611 				       sctp_cmd_seq_t *commands)
4612 {
4613 	struct sctp_chunk *repl;
4614 	struct sctp_association *my_asoc;
4615 
4616 	/* The comment below says that we enter COOKIE-WAIT AFTER
4617 	 * sending the INIT, but that doesn't actually work in our
4618 	 * implementation...
4619 	 */
4620 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
4621 			SCTP_STATE(SCTP_STATE_COOKIE_WAIT));
4622 
4623 	/* RFC 2960 5.1 Normal Establishment of an Association
4624 	 *
4625 	 * A) "A" first sends an INIT chunk to "Z".  In the INIT, "A"
4626 	 * must provide its Verification Tag (Tag_A) in the Initiate
4627 	 * Tag field.  Tag_A SHOULD be a random number in the range of
4628 	 * 1 to 4294967295 (see 5.3.1 for Tag value selection). ...
4629 	 */
4630 
4631 	repl = sctp_make_init(asoc, &asoc->base.bind_addr, GFP_ATOMIC, 0);
4632 	if (!repl)
4633 		goto nomem;
4634 
4635 	/* Choose transport for INIT. */
4636 	sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT,
4637 			SCTP_CHUNK(repl));
4638 
4639 	/* Cast away the const modifier, as we want to just
4640 	 * rerun it through as a sideffect.
4641 	 */
4642 	my_asoc = (struct sctp_association *)asoc;
4643 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(my_asoc));
4644 
4645 	/* After sending the INIT, "A" starts the T1-init timer and
4646 	 * enters the COOKIE-WAIT state.
4647 	 */
4648 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
4649 			SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
4650 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
4651 	return SCTP_DISPOSITION_CONSUME;
4652 
4653 nomem:
4654 	return SCTP_DISPOSITION_NOMEM;
4655 }
4656 
4657 /*
4658  * Process the SEND primitive.
4659  *
4660  * Section: 10.1 ULP-to-SCTP
4661  * E) Send
4662  *
4663  * Format: SEND(association id, buffer address, byte count [,context]
4664  *         [,stream id] [,life time] [,destination transport address]
4665  *         [,unorder flag] [,no-bundle flag] [,payload protocol-id] )
4666  * -> result
4667  *
4668  * This is the main method to send user data via SCTP.
4669  *
4670  * Mandatory attributes:
4671  *
4672  *  o association id - local handle to the SCTP association
4673  *
4674  *  o buffer address - the location where the user message to be
4675  *    transmitted is stored;
4676  *
4677  *  o byte count - The size of the user data in number of bytes;
4678  *
4679  * Optional attributes:
4680  *
4681  *  o context - an optional 32 bit integer that will be carried in the
4682  *    sending failure notification to the ULP if the transportation of
4683  *    this User Message fails.
4684  *
4685  *  o stream id - to indicate which stream to send the data on. If not
4686  *    specified, stream 0 will be used.
4687  *
4688  *  o life time - specifies the life time of the user data. The user data
4689  *    will not be sent by SCTP after the life time expires. This
4690  *    parameter can be used to avoid efforts to transmit stale
4691  *    user messages. SCTP notifies the ULP if the data cannot be
4692  *    initiated to transport (i.e. sent to the destination via SCTP's
4693  *    send primitive) within the life time variable. However, the
4694  *    user data will be transmitted if SCTP has attempted to transmit a
4695  *    chunk before the life time expired.
4696  *
4697  *  o destination transport address - specified as one of the destination
4698  *    transport addresses of the peer endpoint to which this packet
4699  *    should be sent. Whenever possible, SCTP should use this destination
4700  *    transport address for sending the packets, instead of the current
4701  *    primary path.
4702  *
4703  *  o unorder flag - this flag, if present, indicates that the user
4704  *    would like the data delivered in an unordered fashion to the peer
4705  *    (i.e., the U flag is set to 1 on all DATA chunks carrying this
4706  *    message).
4707  *
4708  *  o no-bundle flag - instructs SCTP not to bundle this user data with
4709  *    other outbound DATA chunks. SCTP MAY still bundle even when
4710  *    this flag is present, when faced with network congestion.
4711  *
4712  *  o payload protocol-id - A 32 bit unsigned integer that is to be
4713  *    passed to the peer indicating the type of payload protocol data
4714  *    being transmitted. This value is passed as opaque data by SCTP.
4715  *
4716  * The return value is the disposition.
4717  */
4718 sctp_disposition_t sctp_sf_do_prm_send(struct net *net,
4719 				       const struct sctp_endpoint *ep,
4720 				       const struct sctp_association *asoc,
4721 				       const sctp_subtype_t type,
4722 				       void *arg,
4723 				       sctp_cmd_seq_t *commands)
4724 {
4725 	struct sctp_datamsg *msg = arg;
4726 
4727 	sctp_add_cmd_sf(commands, SCTP_CMD_SEND_MSG, SCTP_DATAMSG(msg));
4728 	return SCTP_DISPOSITION_CONSUME;
4729 }
4730 
4731 /*
4732  * Process the SHUTDOWN primitive.
4733  *
4734  * Section: 10.1:
4735  * C) Shutdown
4736  *
4737  * Format: SHUTDOWN(association id)
4738  * -> result
4739  *
4740  * Gracefully closes an association. Any locally queued user data
4741  * will be delivered to the peer. The association will be terminated only
4742  * after the peer acknowledges all the SCTP packets sent.  A success code
4743  * will be returned on successful termination of the association. If
4744  * attempting to terminate the association results in a failure, an error
4745  * code shall be returned.
4746  *
4747  * Mandatory attributes:
4748  *
4749  *  o association id - local handle to the SCTP association
4750  *
4751  * Optional attributes:
4752  *
4753  * None.
4754  *
4755  * The return value is the disposition.
4756  */
4757 sctp_disposition_t sctp_sf_do_9_2_prm_shutdown(
4758 	struct net *net,
4759 	const struct sctp_endpoint *ep,
4760 	const struct sctp_association *asoc,
4761 	const sctp_subtype_t type,
4762 	void *arg,
4763 	sctp_cmd_seq_t *commands)
4764 {
4765 	int disposition;
4766 
4767 	/* From 9.2 Shutdown of an Association
4768 	 * Upon receipt of the SHUTDOWN primitive from its upper
4769 	 * layer, the endpoint enters SHUTDOWN-PENDING state and
4770 	 * remains there until all outstanding data has been
4771 	 * acknowledged by its peer. The endpoint accepts no new data
4772 	 * from its upper layer, but retransmits data to the far end
4773 	 * if necessary to fill gaps.
4774 	 */
4775 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
4776 			SCTP_STATE(SCTP_STATE_SHUTDOWN_PENDING));
4777 
4778 	disposition = SCTP_DISPOSITION_CONSUME;
4779 	if (sctp_outq_is_empty(&asoc->outqueue)) {
4780 		disposition = sctp_sf_do_9_2_start_shutdown(net, ep, asoc, type,
4781 							    arg, commands);
4782 	}
4783 	return disposition;
4784 }
4785 
4786 /*
4787  * Process the ABORT primitive.
4788  *
4789  * Section: 10.1:
4790  * C) Abort
4791  *
4792  * Format: Abort(association id [, cause code])
4793  * -> result
4794  *
4795  * Ungracefully closes an association. Any locally queued user data
4796  * will be discarded and an ABORT chunk is sent to the peer.  A success code
4797  * will be returned on successful abortion of the association. If
4798  * attempting to abort the association results in a failure, an error
4799  * code shall be returned.
4800  *
4801  * Mandatory attributes:
4802  *
4803  *  o association id - local handle to the SCTP association
4804  *
4805  * Optional attributes:
4806  *
4807  *  o cause code - reason of the abort to be passed to the peer
4808  *
4809  * None.
4810  *
4811  * The return value is the disposition.
4812  */
4813 sctp_disposition_t sctp_sf_do_9_1_prm_abort(
4814 	struct net *net,
4815 	const struct sctp_endpoint *ep,
4816 	const struct sctp_association *asoc,
4817 	const sctp_subtype_t type,
4818 	void *arg,
4819 	sctp_cmd_seq_t *commands)
4820 {
4821 	/* From 9.1 Abort of an Association
4822 	 * Upon receipt of the ABORT primitive from its upper
4823 	 * layer, the endpoint enters CLOSED state and
4824 	 * discard all outstanding data has been
4825 	 * acknowledged by its peer. The endpoint accepts no new data
4826 	 * from its upper layer, but retransmits data to the far end
4827 	 * if necessary to fill gaps.
4828 	 */
4829 	struct sctp_chunk *abort = arg;
4830 	sctp_disposition_t retval;
4831 
4832 	retval = SCTP_DISPOSITION_CONSUME;
4833 
4834 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
4835 
4836 	/* Even if we can't send the ABORT due to low memory delete the
4837 	 * TCB.  This is a departure from our typical NOMEM handling.
4838 	 */
4839 
4840 	sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
4841 			SCTP_ERROR(ECONNABORTED));
4842 	/* Delete the established association. */
4843 	sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
4844 			SCTP_PERR(SCTP_ERROR_USER_ABORT));
4845 
4846 	SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
4847 	SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
4848 
4849 	return retval;
4850 }
4851 
4852 /* We tried an illegal operation on an association which is closed.  */
4853 sctp_disposition_t sctp_sf_error_closed(struct net *net,
4854 					const struct sctp_endpoint *ep,
4855 					const struct sctp_association *asoc,
4856 					const sctp_subtype_t type,
4857 					void *arg,
4858 					sctp_cmd_seq_t *commands)
4859 {
4860 	sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_ERROR, SCTP_ERROR(-EINVAL));
4861 	return SCTP_DISPOSITION_CONSUME;
4862 }
4863 
4864 /* We tried an illegal operation on an association which is shutting
4865  * down.
4866  */
4867 sctp_disposition_t sctp_sf_error_shutdown(struct net *net,
4868 					  const struct sctp_endpoint *ep,
4869 					  const struct sctp_association *asoc,
4870 					  const sctp_subtype_t type,
4871 					  void *arg,
4872 					  sctp_cmd_seq_t *commands)
4873 {
4874 	sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_ERROR,
4875 			SCTP_ERROR(-ESHUTDOWN));
4876 	return SCTP_DISPOSITION_CONSUME;
4877 }
4878 
4879 /*
4880  * sctp_cookie_wait_prm_shutdown
4881  *
4882  * Section: 4 Note: 2
4883  * Verification Tag:
4884  * Inputs
4885  * (endpoint, asoc)
4886  *
4887  * The RFC does not explicitly address this issue, but is the route through the
4888  * state table when someone issues a shutdown while in COOKIE_WAIT state.
4889  *
4890  * Outputs
4891  * (timers)
4892  */
4893 sctp_disposition_t sctp_sf_cookie_wait_prm_shutdown(
4894 	struct net *net,
4895 	const struct sctp_endpoint *ep,
4896 	const struct sctp_association *asoc,
4897 	const sctp_subtype_t type,
4898 	void *arg,
4899 	sctp_cmd_seq_t *commands)
4900 {
4901 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
4902 			SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
4903 
4904 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
4905 			SCTP_STATE(SCTP_STATE_CLOSED));
4906 
4907 	SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS);
4908 
4909 	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
4910 
4911 	return SCTP_DISPOSITION_DELETE_TCB;
4912 }
4913 
4914 /*
4915  * sctp_cookie_echoed_prm_shutdown
4916  *
4917  * Section: 4 Note: 2
4918  * Verification Tag:
4919  * Inputs
4920  * (endpoint, asoc)
4921  *
4922  * The RFC does not explcitly address this issue, but is the route through the
4923  * state table when someone issues a shutdown while in COOKIE_ECHOED state.
4924  *
4925  * Outputs
4926  * (timers)
4927  */
4928 sctp_disposition_t sctp_sf_cookie_echoed_prm_shutdown(
4929 	struct net *net,
4930 	const struct sctp_endpoint *ep,
4931 	const struct sctp_association *asoc,
4932 	const sctp_subtype_t type,
4933 	void *arg, sctp_cmd_seq_t *commands)
4934 {
4935 	/* There is a single T1 timer, so we should be able to use
4936 	 * common function with the COOKIE-WAIT state.
4937 	 */
4938 	return sctp_sf_cookie_wait_prm_shutdown(net, ep, asoc, type, arg, commands);
4939 }
4940 
4941 /*
4942  * sctp_sf_cookie_wait_prm_abort
4943  *
4944  * Section: 4 Note: 2
4945  * Verification Tag:
4946  * Inputs
4947  * (endpoint, asoc)
4948  *
4949  * The RFC does not explicitly address this issue, but is the route through the
4950  * state table when someone issues an abort while in COOKIE_WAIT state.
4951  *
4952  * Outputs
4953  * (timers)
4954  */
4955 sctp_disposition_t sctp_sf_cookie_wait_prm_abort(
4956 	struct net *net,
4957 	const struct sctp_endpoint *ep,
4958 	const struct sctp_association *asoc,
4959 	const sctp_subtype_t type,
4960 	void *arg,
4961 	sctp_cmd_seq_t *commands)
4962 {
4963 	struct sctp_chunk *abort = arg;
4964 	sctp_disposition_t retval;
4965 
4966 	/* Stop T1-init timer */
4967 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
4968 			SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
4969 	retval = SCTP_DISPOSITION_CONSUME;
4970 
4971 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
4972 
4973 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
4974 			SCTP_STATE(SCTP_STATE_CLOSED));
4975 
4976 	SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
4977 
4978 	/* Even if we can't send the ABORT due to low memory delete the
4979 	 * TCB.  This is a departure from our typical NOMEM handling.
4980 	 */
4981 
4982 	sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
4983 			SCTP_ERROR(ECONNREFUSED));
4984 	/* Delete the established association. */
4985 	sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
4986 			SCTP_PERR(SCTP_ERROR_USER_ABORT));
4987 
4988 	return retval;
4989 }
4990 
4991 /*
4992  * sctp_sf_cookie_echoed_prm_abort
4993  *
4994  * Section: 4 Note: 3
4995  * Verification Tag:
4996  * Inputs
4997  * (endpoint, asoc)
4998  *
4999  * The RFC does not explcitly address this issue, but is the route through the
5000  * state table when someone issues an abort while in COOKIE_ECHOED state.
5001  *
5002  * Outputs
5003  * (timers)
5004  */
5005 sctp_disposition_t sctp_sf_cookie_echoed_prm_abort(
5006 	struct net *net,
5007 	const struct sctp_endpoint *ep,
5008 	const struct sctp_association *asoc,
5009 	const sctp_subtype_t type,
5010 	void *arg,
5011 	sctp_cmd_seq_t *commands)
5012 {
5013 	/* There is a single T1 timer, so we should be able to use
5014 	 * common function with the COOKIE-WAIT state.
5015 	 */
5016 	return sctp_sf_cookie_wait_prm_abort(net, ep, asoc, type, arg, commands);
5017 }
5018 
5019 /*
5020  * sctp_sf_shutdown_pending_prm_abort
5021  *
5022  * Inputs
5023  * (endpoint, asoc)
5024  *
5025  * The RFC does not explicitly address this issue, but is the route through the
5026  * state table when someone issues an abort while in SHUTDOWN-PENDING state.
5027  *
5028  * Outputs
5029  * (timers)
5030  */
5031 sctp_disposition_t sctp_sf_shutdown_pending_prm_abort(
5032 	struct net *net,
5033 	const struct sctp_endpoint *ep,
5034 	const struct sctp_association *asoc,
5035 	const sctp_subtype_t type,
5036 	void *arg,
5037 	sctp_cmd_seq_t *commands)
5038 {
5039 	/* Stop the T5-shutdown guard timer.  */
5040 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5041 			SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
5042 
5043 	return sctp_sf_do_9_1_prm_abort(net, ep, asoc, type, arg, commands);
5044 }
5045 
5046 /*
5047  * sctp_sf_shutdown_sent_prm_abort
5048  *
5049  * Inputs
5050  * (endpoint, asoc)
5051  *
5052  * The RFC does not explicitly address this issue, but is the route through the
5053  * state table when someone issues an abort while in SHUTDOWN-SENT state.
5054  *
5055  * Outputs
5056  * (timers)
5057  */
5058 sctp_disposition_t sctp_sf_shutdown_sent_prm_abort(
5059 	struct net *net,
5060 	const struct sctp_endpoint *ep,
5061 	const struct sctp_association *asoc,
5062 	const sctp_subtype_t type,
5063 	void *arg,
5064 	sctp_cmd_seq_t *commands)
5065 {
5066 	/* Stop the T2-shutdown timer.  */
5067 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5068 			SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
5069 
5070 	/* Stop the T5-shutdown guard timer.  */
5071 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5072 			SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
5073 
5074 	return sctp_sf_do_9_1_prm_abort(net, ep, asoc, type, arg, commands);
5075 }
5076 
5077 /*
5078  * sctp_sf_cookie_echoed_prm_abort
5079  *
5080  * Inputs
5081  * (endpoint, asoc)
5082  *
5083  * The RFC does not explcitly address this issue, but is the route through the
5084  * state table when someone issues an abort while in COOKIE_ECHOED state.
5085  *
5086  * Outputs
5087  * (timers)
5088  */
5089 sctp_disposition_t sctp_sf_shutdown_ack_sent_prm_abort(
5090 	struct net *net,
5091 	const struct sctp_endpoint *ep,
5092 	const struct sctp_association *asoc,
5093 	const sctp_subtype_t type,
5094 	void *arg,
5095 	sctp_cmd_seq_t *commands)
5096 {
5097 	/* The same T2 timer, so we should be able to use
5098 	 * common function with the SHUTDOWN-SENT state.
5099 	 */
5100 	return sctp_sf_shutdown_sent_prm_abort(net, ep, asoc, type, arg, commands);
5101 }
5102 
5103 /*
5104  * Process the REQUESTHEARTBEAT primitive
5105  *
5106  * 10.1 ULP-to-SCTP
5107  * J) Request Heartbeat
5108  *
5109  * Format: REQUESTHEARTBEAT(association id, destination transport address)
5110  *
5111  * -> result
5112  *
5113  * Instructs the local endpoint to perform a HeartBeat on the specified
5114  * destination transport address of the given association. The returned
5115  * result should indicate whether the transmission of the HEARTBEAT
5116  * chunk to the destination address is successful.
5117  *
5118  * Mandatory attributes:
5119  *
5120  * o association id - local handle to the SCTP association
5121  *
5122  * o destination transport address - the transport address of the
5123  *   association on which a heartbeat should be issued.
5124  */
5125 sctp_disposition_t sctp_sf_do_prm_requestheartbeat(
5126 					struct net *net,
5127 					const struct sctp_endpoint *ep,
5128 					const struct sctp_association *asoc,
5129 					const sctp_subtype_t type,
5130 					void *arg,
5131 					sctp_cmd_seq_t *commands)
5132 {
5133 	if (SCTP_DISPOSITION_NOMEM == sctp_sf_heartbeat(ep, asoc, type,
5134 				      (struct sctp_transport *)arg, commands))
5135 		return SCTP_DISPOSITION_NOMEM;
5136 
5137 	/*
5138 	 * RFC 2960 (bis), section 8.3
5139 	 *
5140 	 *    D) Request an on-demand HEARTBEAT on a specific destination
5141 	 *    transport address of a given association.
5142 	 *
5143 	 *    The endpoint should increment the respective error  counter of
5144 	 *    the destination transport address each time a HEARTBEAT is sent
5145 	 *    to that address and not acknowledged within one RTO.
5146 	 *
5147 	 */
5148 	sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_HB_SENT,
5149 			SCTP_TRANSPORT(arg));
5150 	return SCTP_DISPOSITION_CONSUME;
5151 }
5152 
5153 /*
5154  * ADDIP Section 4.1 ASCONF Chunk Procedures
5155  * When an endpoint has an ASCONF signaled change to be sent to the
5156  * remote endpoint it should do A1 to A9
5157  */
5158 sctp_disposition_t sctp_sf_do_prm_asconf(struct net *net,
5159 					const struct sctp_endpoint *ep,
5160 					const struct sctp_association *asoc,
5161 					const sctp_subtype_t type,
5162 					void *arg,
5163 					sctp_cmd_seq_t *commands)
5164 {
5165 	struct sctp_chunk *chunk = arg;
5166 
5167 	sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T4, SCTP_CHUNK(chunk));
5168 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
5169 			SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
5170 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(chunk));
5171 	return SCTP_DISPOSITION_CONSUME;
5172 }
5173 
5174 /*
5175  * Ignore the primitive event
5176  *
5177  * The return value is the disposition of the primitive.
5178  */
5179 sctp_disposition_t sctp_sf_ignore_primitive(
5180 	struct net *net,
5181 	const struct sctp_endpoint *ep,
5182 	const struct sctp_association *asoc,
5183 	const sctp_subtype_t type,
5184 	void *arg,
5185 	sctp_cmd_seq_t *commands)
5186 {
5187 	pr_debug("%s: primitive type:%d is ignored\n", __func__,
5188 		 type.primitive);
5189 
5190 	return SCTP_DISPOSITION_DISCARD;
5191 }
5192 
5193 /***************************************************************************
5194  * These are the state functions for the OTHER events.
5195  ***************************************************************************/
5196 
5197 /*
5198  * When the SCTP stack has no more user data to send or retransmit, this
5199  * notification is given to the user. Also, at the time when a user app
5200  * subscribes to this event, if there is no data to be sent or
5201  * retransmit, the stack will immediately send up this notification.
5202  */
5203 sctp_disposition_t sctp_sf_do_no_pending_tsn(
5204 	struct net *net,
5205 	const struct sctp_endpoint *ep,
5206 	const struct sctp_association *asoc,
5207 	const sctp_subtype_t type,
5208 	void *arg,
5209 	sctp_cmd_seq_t *commands)
5210 {
5211 	struct sctp_ulpevent *event;
5212 
5213 	event = sctp_ulpevent_make_sender_dry_event(asoc, GFP_ATOMIC);
5214 	if (!event)
5215 		return SCTP_DISPOSITION_NOMEM;
5216 
5217 	sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(event));
5218 
5219 	return SCTP_DISPOSITION_CONSUME;
5220 }
5221 
5222 /*
5223  * Start the shutdown negotiation.
5224  *
5225  * From Section 9.2:
5226  * Once all its outstanding data has been acknowledged, the endpoint
5227  * shall send a SHUTDOWN chunk to its peer including in the Cumulative
5228  * TSN Ack field the last sequential TSN it has received from the peer.
5229  * It shall then start the T2-shutdown timer and enter the SHUTDOWN-SENT
5230  * state. If the timer expires, the endpoint must re-send the SHUTDOWN
5231  * with the updated last sequential TSN received from its peer.
5232  *
5233  * The return value is the disposition.
5234  */
5235 sctp_disposition_t sctp_sf_do_9_2_start_shutdown(
5236 	struct net *net,
5237 	const struct sctp_endpoint *ep,
5238 	const struct sctp_association *asoc,
5239 	const sctp_subtype_t type,
5240 	void *arg,
5241 	sctp_cmd_seq_t *commands)
5242 {
5243 	struct sctp_chunk *reply;
5244 
5245 	/* Once all its outstanding data has been acknowledged, the
5246 	 * endpoint shall send a SHUTDOWN chunk to its peer including
5247 	 * in the Cumulative TSN Ack field the last sequential TSN it
5248 	 * has received from the peer.
5249 	 */
5250 	reply = sctp_make_shutdown(asoc, NULL);
5251 	if (!reply)
5252 		goto nomem;
5253 
5254 	/* Set the transport for the SHUTDOWN chunk and the timeout for the
5255 	 * T2-shutdown timer.
5256 	 */
5257 	sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
5258 
5259 	/* It shall then start the T2-shutdown timer */
5260 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
5261 			SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
5262 
5263 	/* RFC 4960 Section 9.2
5264 	 * The sender of the SHUTDOWN MAY also start an overall guard timer
5265 	 * 'T5-shutdown-guard' to bound the overall time for shutdown sequence.
5266 	 */
5267 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
5268 			SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
5269 
5270 	if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
5271 		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5272 				SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
5273 
5274 	/* and enter the SHUTDOWN-SENT state.  */
5275 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
5276 			SCTP_STATE(SCTP_STATE_SHUTDOWN_SENT));
5277 
5278 	/* sctp-implguide 2.10 Issues with Heartbeating and failover
5279 	 *
5280 	 * HEARTBEAT ... is discontinued after sending either SHUTDOWN
5281 	 * or SHUTDOWN-ACK.
5282 	 */
5283 	sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL());
5284 
5285 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
5286 
5287 	return SCTP_DISPOSITION_CONSUME;
5288 
5289 nomem:
5290 	return SCTP_DISPOSITION_NOMEM;
5291 }
5292 
5293 /*
5294  * Generate a SHUTDOWN ACK now that everything is SACK'd.
5295  *
5296  * From Section 9.2:
5297  *
5298  * If it has no more outstanding DATA chunks, the SHUTDOWN receiver
5299  * shall send a SHUTDOWN ACK and start a T2-shutdown timer of its own,
5300  * entering the SHUTDOWN-ACK-SENT state. If the timer expires, the
5301  * endpoint must re-send the SHUTDOWN ACK.
5302  *
5303  * The return value is the disposition.
5304  */
5305 sctp_disposition_t sctp_sf_do_9_2_shutdown_ack(
5306 	struct net *net,
5307 	const struct sctp_endpoint *ep,
5308 	const struct sctp_association *asoc,
5309 	const sctp_subtype_t type,
5310 	void *arg,
5311 	sctp_cmd_seq_t *commands)
5312 {
5313 	struct sctp_chunk *chunk = (struct sctp_chunk *) arg;
5314 	struct sctp_chunk *reply;
5315 
5316 	/* There are 2 ways of getting here:
5317 	 *    1) called in response to a SHUTDOWN chunk
5318 	 *    2) called when SCTP_EVENT_NO_PENDING_TSN event is issued.
5319 	 *
5320 	 * For the case (2), the arg parameter is set to NULL.  We need
5321 	 * to check that we have a chunk before accessing it's fields.
5322 	 */
5323 	if (chunk) {
5324 		if (!sctp_vtag_verify(chunk, asoc))
5325 			return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
5326 
5327 		/* Make sure that the SHUTDOWN chunk has a valid length. */
5328 		if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_shutdown_chunk_t)))
5329 			return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
5330 							  commands);
5331 	}
5332 
5333 	/* If it has no more outstanding DATA chunks, the SHUTDOWN receiver
5334 	 * shall send a SHUTDOWN ACK ...
5335 	 */
5336 	reply = sctp_make_shutdown_ack(asoc, chunk);
5337 	if (!reply)
5338 		goto nomem;
5339 
5340 	/* Set the transport for the SHUTDOWN ACK chunk and the timeout for
5341 	 * the T2-shutdown timer.
5342 	 */
5343 	sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
5344 
5345 	/* and start/restart a T2-shutdown timer of its own, */
5346 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
5347 			SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
5348 
5349 	if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
5350 		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5351 				SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
5352 
5353 	/* Enter the SHUTDOWN-ACK-SENT state.  */
5354 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
5355 			SCTP_STATE(SCTP_STATE_SHUTDOWN_ACK_SENT));
5356 
5357 	/* sctp-implguide 2.10 Issues with Heartbeating and failover
5358 	 *
5359 	 * HEARTBEAT ... is discontinued after sending either SHUTDOWN
5360 	 * or SHUTDOWN-ACK.
5361 	 */
5362 	sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL());
5363 
5364 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
5365 
5366 	return SCTP_DISPOSITION_CONSUME;
5367 
5368 nomem:
5369 	return SCTP_DISPOSITION_NOMEM;
5370 }
5371 
5372 /*
5373  * Ignore the event defined as other
5374  *
5375  * The return value is the disposition of the event.
5376  */
5377 sctp_disposition_t sctp_sf_ignore_other(struct net *net,
5378 					const struct sctp_endpoint *ep,
5379 					const struct sctp_association *asoc,
5380 					const sctp_subtype_t type,
5381 					void *arg,
5382 					sctp_cmd_seq_t *commands)
5383 {
5384 	pr_debug("%s: the event other type:%d is ignored\n",
5385 		 __func__, type.other);
5386 
5387 	return SCTP_DISPOSITION_DISCARD;
5388 }
5389 
5390 /************************************************************
5391  * These are the state functions for handling timeout events.
5392  ************************************************************/
5393 
5394 /*
5395  * RTX Timeout
5396  *
5397  * Section: 6.3.3 Handle T3-rtx Expiration
5398  *
5399  * Whenever the retransmission timer T3-rtx expires for a destination
5400  * address, do the following:
5401  * [See below]
5402  *
5403  * The return value is the disposition of the chunk.
5404  */
5405 sctp_disposition_t sctp_sf_do_6_3_3_rtx(struct net *net,
5406 					const struct sctp_endpoint *ep,
5407 					const struct sctp_association *asoc,
5408 					const sctp_subtype_t type,
5409 					void *arg,
5410 					sctp_cmd_seq_t *commands)
5411 {
5412 	struct sctp_transport *transport = arg;
5413 
5414 	SCTP_INC_STATS(net, SCTP_MIB_T3_RTX_EXPIREDS);
5415 
5416 	if (asoc->overall_error_count >= asoc->max_retrans) {
5417 		if (asoc->state == SCTP_STATE_SHUTDOWN_PENDING) {
5418 			/*
5419 			 * We are here likely because the receiver had its rwnd
5420 			 * closed for a while and we have not been able to
5421 			 * transmit the locally queued data within the maximum
5422 			 * retransmission attempts limit.  Start the T5
5423 			 * shutdown guard timer to give the receiver one last
5424 			 * chance and some additional time to recover before
5425 			 * aborting.
5426 			 */
5427 			sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START_ONCE,
5428 				SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
5429 		} else {
5430 			sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5431 					SCTP_ERROR(ETIMEDOUT));
5432 			/* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */
5433 			sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
5434 					SCTP_PERR(SCTP_ERROR_NO_ERROR));
5435 			SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
5436 			SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
5437 			return SCTP_DISPOSITION_DELETE_TCB;
5438 		}
5439 	}
5440 
5441 	/* E1) For the destination address for which the timer
5442 	 * expires, adjust its ssthresh with rules defined in Section
5443 	 * 7.2.3 and set the cwnd <- MTU.
5444 	 */
5445 
5446 	/* E2) For the destination address for which the timer
5447 	 * expires, set RTO <- RTO * 2 ("back off the timer").  The
5448 	 * maximum value discussed in rule C7 above (RTO.max) may be
5449 	 * used to provide an upper bound to this doubling operation.
5450 	 */
5451 
5452 	/* E3) Determine how many of the earliest (i.e., lowest TSN)
5453 	 * outstanding DATA chunks for the address for which the
5454 	 * T3-rtx has expired will fit into a single packet, subject
5455 	 * to the MTU constraint for the path corresponding to the
5456 	 * destination transport address to which the retransmission
5457 	 * is being sent (this may be different from the address for
5458 	 * which the timer expires [see Section 6.4]).  Call this
5459 	 * value K. Bundle and retransmit those K DATA chunks in a
5460 	 * single packet to the destination endpoint.
5461 	 *
5462 	 * Note: Any DATA chunks that were sent to the address for
5463 	 * which the T3-rtx timer expired but did not fit in one MTU
5464 	 * (rule E3 above), should be marked for retransmission and
5465 	 * sent as soon as cwnd allows (normally when a SACK arrives).
5466 	 */
5467 
5468 	/* Do some failure management (Section 8.2). */
5469 	sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE, SCTP_TRANSPORT(transport));
5470 
5471 	/* NB: Rules E4 and F1 are implicit in R1.  */
5472 	sctp_add_cmd_sf(commands, SCTP_CMD_RETRAN, SCTP_TRANSPORT(transport));
5473 
5474 	return SCTP_DISPOSITION_CONSUME;
5475 }
5476 
5477 /*
5478  * Generate delayed SACK on timeout
5479  *
5480  * Section: 6.2  Acknowledgement on Reception of DATA Chunks
5481  *
5482  * The guidelines on delayed acknowledgement algorithm specified in
5483  * Section 4.2 of [RFC2581] SHOULD be followed.  Specifically, an
5484  * acknowledgement SHOULD be generated for at least every second packet
5485  * (not every second DATA chunk) received, and SHOULD be generated
5486  * within 200 ms of the arrival of any unacknowledged DATA chunk.  In
5487  * some situations it may be beneficial for an SCTP transmitter to be
5488  * more conservative than the algorithms detailed in this document
5489  * allow. However, an SCTP transmitter MUST NOT be more aggressive than
5490  * the following algorithms allow.
5491  */
5492 sctp_disposition_t sctp_sf_do_6_2_sack(struct net *net,
5493 				       const struct sctp_endpoint *ep,
5494 				       const struct sctp_association *asoc,
5495 				       const sctp_subtype_t type,
5496 				       void *arg,
5497 				       sctp_cmd_seq_t *commands)
5498 {
5499 	SCTP_INC_STATS(net, SCTP_MIB_DELAY_SACK_EXPIREDS);
5500 	sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
5501 	return SCTP_DISPOSITION_CONSUME;
5502 }
5503 
5504 /*
5505  * sctp_sf_t1_init_timer_expire
5506  *
5507  * Section: 4 Note: 2
5508  * Verification Tag:
5509  * Inputs
5510  * (endpoint, asoc)
5511  *
5512  *  RFC 2960 Section 4 Notes
5513  *  2) If the T1-init timer expires, the endpoint MUST retransmit INIT
5514  *     and re-start the T1-init timer without changing state.  This MUST
5515  *     be repeated up to 'Max.Init.Retransmits' times.  After that, the
5516  *     endpoint MUST abort the initialization process and report the
5517  *     error to SCTP user.
5518  *
5519  * Outputs
5520  * (timers, events)
5521  *
5522  */
5523 sctp_disposition_t sctp_sf_t1_init_timer_expire(struct net *net,
5524 					   const struct sctp_endpoint *ep,
5525 					   const struct sctp_association *asoc,
5526 					   const sctp_subtype_t type,
5527 					   void *arg,
5528 					   sctp_cmd_seq_t *commands)
5529 {
5530 	struct sctp_chunk *repl = NULL;
5531 	struct sctp_bind_addr *bp;
5532 	int attempts = asoc->init_err_counter + 1;
5533 
5534 	pr_debug("%s: timer T1 expired (INIT)\n", __func__);
5535 
5536 	SCTP_INC_STATS(net, SCTP_MIB_T1_INIT_EXPIREDS);
5537 
5538 	if (attempts <= asoc->max_init_attempts) {
5539 		bp = (struct sctp_bind_addr *) &asoc->base.bind_addr;
5540 		repl = sctp_make_init(asoc, bp, GFP_ATOMIC, 0);
5541 		if (!repl)
5542 			return SCTP_DISPOSITION_NOMEM;
5543 
5544 		/* Choose transport for INIT. */
5545 		sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT,
5546 				SCTP_CHUNK(repl));
5547 
5548 		/* Issue a sideeffect to do the needed accounting. */
5549 		sctp_add_cmd_sf(commands, SCTP_CMD_INIT_RESTART,
5550 				SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
5551 
5552 		sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
5553 	} else {
5554 		pr_debug("%s: giving up on INIT, attempts:%d "
5555 			 "max_init_attempts:%d\n", __func__, attempts,
5556 			 asoc->max_init_attempts);
5557 
5558 		sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5559 				SCTP_ERROR(ETIMEDOUT));
5560 		sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
5561 				SCTP_PERR(SCTP_ERROR_NO_ERROR));
5562 		return SCTP_DISPOSITION_DELETE_TCB;
5563 	}
5564 
5565 	return SCTP_DISPOSITION_CONSUME;
5566 }
5567 
5568 /*
5569  * sctp_sf_t1_cookie_timer_expire
5570  *
5571  * Section: 4 Note: 2
5572  * Verification Tag:
5573  * Inputs
5574  * (endpoint, asoc)
5575  *
5576  *  RFC 2960 Section 4 Notes
5577  *  3) If the T1-cookie timer expires, the endpoint MUST retransmit
5578  *     COOKIE ECHO and re-start the T1-cookie timer without changing
5579  *     state.  This MUST be repeated up to 'Max.Init.Retransmits' times.
5580  *     After that, the endpoint MUST abort the initialization process and
5581  *     report the error to SCTP user.
5582  *
5583  * Outputs
5584  * (timers, events)
5585  *
5586  */
5587 sctp_disposition_t sctp_sf_t1_cookie_timer_expire(struct net *net,
5588 					   const struct sctp_endpoint *ep,
5589 					   const struct sctp_association *asoc,
5590 					   const sctp_subtype_t type,
5591 					   void *arg,
5592 					   sctp_cmd_seq_t *commands)
5593 {
5594 	struct sctp_chunk *repl = NULL;
5595 	int attempts = asoc->init_err_counter + 1;
5596 
5597 	pr_debug("%s: timer T1 expired (COOKIE-ECHO)\n", __func__);
5598 
5599 	SCTP_INC_STATS(net, SCTP_MIB_T1_COOKIE_EXPIREDS);
5600 
5601 	if (attempts <= asoc->max_init_attempts) {
5602 		repl = sctp_make_cookie_echo(asoc, NULL);
5603 		if (!repl)
5604 			return SCTP_DISPOSITION_NOMEM;
5605 
5606 		sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT,
5607 				SCTP_CHUNK(repl));
5608 		/* Issue a sideeffect to do the needed accounting. */
5609 		sctp_add_cmd_sf(commands, SCTP_CMD_COOKIEECHO_RESTART,
5610 				SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
5611 
5612 		sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
5613 	} else {
5614 		sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5615 				SCTP_ERROR(ETIMEDOUT));
5616 		sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
5617 				SCTP_PERR(SCTP_ERROR_NO_ERROR));
5618 		return SCTP_DISPOSITION_DELETE_TCB;
5619 	}
5620 
5621 	return SCTP_DISPOSITION_CONSUME;
5622 }
5623 
5624 /* RFC2960 9.2 If the timer expires, the endpoint must re-send the SHUTDOWN
5625  * with the updated last sequential TSN received from its peer.
5626  *
5627  * An endpoint should limit the number of retransmissions of the
5628  * SHUTDOWN chunk to the protocol parameter 'Association.Max.Retrans'.
5629  * If this threshold is exceeded the endpoint should destroy the TCB and
5630  * MUST report the peer endpoint unreachable to the upper layer (and
5631  * thus the association enters the CLOSED state).  The reception of any
5632  * packet from its peer (i.e. as the peer sends all of its queued DATA
5633  * chunks) should clear the endpoint's retransmission count and restart
5634  * the T2-Shutdown timer,  giving its peer ample opportunity to transmit
5635  * all of its queued DATA chunks that have not yet been sent.
5636  */
5637 sctp_disposition_t sctp_sf_t2_timer_expire(struct net *net,
5638 					   const struct sctp_endpoint *ep,
5639 					   const struct sctp_association *asoc,
5640 					   const sctp_subtype_t type,
5641 					   void *arg,
5642 					   sctp_cmd_seq_t *commands)
5643 {
5644 	struct sctp_chunk *reply = NULL;
5645 
5646 	pr_debug("%s: timer T2 expired\n", __func__);
5647 
5648 	SCTP_INC_STATS(net, SCTP_MIB_T2_SHUTDOWN_EXPIREDS);
5649 
5650 	((struct sctp_association *)asoc)->shutdown_retries++;
5651 
5652 	if (asoc->overall_error_count >= asoc->max_retrans) {
5653 		sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5654 				SCTP_ERROR(ETIMEDOUT));
5655 		/* Note:  CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */
5656 		sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
5657 				SCTP_PERR(SCTP_ERROR_NO_ERROR));
5658 		SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
5659 		SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
5660 		return SCTP_DISPOSITION_DELETE_TCB;
5661 	}
5662 
5663 	switch (asoc->state) {
5664 	case SCTP_STATE_SHUTDOWN_SENT:
5665 		reply = sctp_make_shutdown(asoc, NULL);
5666 		break;
5667 
5668 	case SCTP_STATE_SHUTDOWN_ACK_SENT:
5669 		reply = sctp_make_shutdown_ack(asoc, NULL);
5670 		break;
5671 
5672 	default:
5673 		BUG();
5674 		break;
5675 	}
5676 
5677 	if (!reply)
5678 		goto nomem;
5679 
5680 	/* Do some failure management (Section 8.2).
5681 	 * If we remove the transport an SHUTDOWN was last sent to, don't
5682 	 * do failure management.
5683 	 */
5684 	if (asoc->shutdown_last_sent_to)
5685 		sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE,
5686 				SCTP_TRANSPORT(asoc->shutdown_last_sent_to));
5687 
5688 	/* Set the transport for the SHUTDOWN/ACK chunk and the timeout for
5689 	 * the T2-shutdown timer.
5690 	 */
5691 	sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
5692 
5693 	/* Restart the T2-shutdown timer.  */
5694 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
5695 			SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
5696 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
5697 	return SCTP_DISPOSITION_CONSUME;
5698 
5699 nomem:
5700 	return SCTP_DISPOSITION_NOMEM;
5701 }
5702 
5703 /*
5704  * ADDIP Section 4.1 ASCONF CHunk Procedures
5705  * If the T4 RTO timer expires the endpoint should do B1 to B5
5706  */
5707 sctp_disposition_t sctp_sf_t4_timer_expire(
5708 	struct net *net,
5709 	const struct sctp_endpoint *ep,
5710 	const struct sctp_association *asoc,
5711 	const sctp_subtype_t type,
5712 	void *arg,
5713 	sctp_cmd_seq_t *commands)
5714 {
5715 	struct sctp_chunk *chunk = asoc->addip_last_asconf;
5716 	struct sctp_transport *transport = chunk->transport;
5717 
5718 	SCTP_INC_STATS(net, SCTP_MIB_T4_RTO_EXPIREDS);
5719 
5720 	/* ADDIP 4.1 B1) Increment the error counters and perform path failure
5721 	 * detection on the appropriate destination address as defined in
5722 	 * RFC2960 [5] section 8.1 and 8.2.
5723 	 */
5724 	if (transport)
5725 		sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE,
5726 				SCTP_TRANSPORT(transport));
5727 
5728 	/* Reconfig T4 timer and transport. */
5729 	sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T4, SCTP_CHUNK(chunk));
5730 
5731 	/* ADDIP 4.1 B2) Increment the association error counters and perform
5732 	 * endpoint failure detection on the association as defined in
5733 	 * RFC2960 [5] section 8.1 and 8.2.
5734 	 * association error counter is incremented in SCTP_CMD_STRIKE.
5735 	 */
5736 	if (asoc->overall_error_count >= asoc->max_retrans) {
5737 		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5738 				SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
5739 		sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5740 				SCTP_ERROR(ETIMEDOUT));
5741 		sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
5742 				SCTP_PERR(SCTP_ERROR_NO_ERROR));
5743 		SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
5744 		SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
5745 		return SCTP_DISPOSITION_ABORT;
5746 	}
5747 
5748 	/* ADDIP 4.1 B3) Back-off the destination address RTO value to which
5749 	 * the ASCONF chunk was sent by doubling the RTO timer value.
5750 	 * This is done in SCTP_CMD_STRIKE.
5751 	 */
5752 
5753 	/* ADDIP 4.1 B4) Re-transmit the ASCONF Chunk last sent and if possible
5754 	 * choose an alternate destination address (please refer to RFC2960
5755 	 * [5] section 6.4.1). An endpoint MUST NOT add new parameters to this
5756 	 * chunk, it MUST be the same (including its serial number) as the last
5757 	 * ASCONF sent.
5758 	 */
5759 	sctp_chunk_hold(asoc->addip_last_asconf);
5760 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
5761 			SCTP_CHUNK(asoc->addip_last_asconf));
5762 
5763 	/* ADDIP 4.1 B5) Restart the T-4 RTO timer. Note that if a different
5764 	 * destination is selected, then the RTO used will be that of the new
5765 	 * destination address.
5766 	 */
5767 	sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
5768 			SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
5769 
5770 	return SCTP_DISPOSITION_CONSUME;
5771 }
5772 
5773 /* sctpimpguide-05 Section 2.12.2
5774  * The sender of the SHUTDOWN MAY also start an overall guard timer
5775  * 'T5-shutdown-guard' to bound the overall time for shutdown sequence.
5776  * At the expiration of this timer the sender SHOULD abort the association
5777  * by sending an ABORT chunk.
5778  */
5779 sctp_disposition_t sctp_sf_t5_timer_expire(struct net *net,
5780 					   const struct sctp_endpoint *ep,
5781 					   const struct sctp_association *asoc,
5782 					   const sctp_subtype_t type,
5783 					   void *arg,
5784 					   sctp_cmd_seq_t *commands)
5785 {
5786 	struct sctp_chunk *reply = NULL;
5787 
5788 	pr_debug("%s: timer T5 expired\n", __func__);
5789 
5790 	SCTP_INC_STATS(net, SCTP_MIB_T5_SHUTDOWN_GUARD_EXPIREDS);
5791 
5792 	reply = sctp_make_abort(asoc, NULL, 0);
5793 	if (!reply)
5794 		goto nomem;
5795 
5796 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
5797 	sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5798 			SCTP_ERROR(ETIMEDOUT));
5799 	sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
5800 			SCTP_PERR(SCTP_ERROR_NO_ERROR));
5801 
5802 	SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
5803 	SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
5804 
5805 	return SCTP_DISPOSITION_DELETE_TCB;
5806 nomem:
5807 	return SCTP_DISPOSITION_NOMEM;
5808 }
5809 
5810 /* Handle expiration of AUTOCLOSE timer.  When the autoclose timer expires,
5811  * the association is automatically closed by starting the shutdown process.
5812  * The work that needs to be done is same as when SHUTDOWN is initiated by
5813  * the user.  So this routine looks same as sctp_sf_do_9_2_prm_shutdown().
5814  */
5815 sctp_disposition_t sctp_sf_autoclose_timer_expire(
5816 	struct net *net,
5817 	const struct sctp_endpoint *ep,
5818 	const struct sctp_association *asoc,
5819 	const sctp_subtype_t type,
5820 	void *arg,
5821 	sctp_cmd_seq_t *commands)
5822 {
5823 	int disposition;
5824 
5825 	SCTP_INC_STATS(net, SCTP_MIB_AUTOCLOSE_EXPIREDS);
5826 
5827 	/* From 9.2 Shutdown of an Association
5828 	 * Upon receipt of the SHUTDOWN primitive from its upper
5829 	 * layer, the endpoint enters SHUTDOWN-PENDING state and
5830 	 * remains there until all outstanding data has been
5831 	 * acknowledged by its peer. The endpoint accepts no new data
5832 	 * from its upper layer, but retransmits data to the far end
5833 	 * if necessary to fill gaps.
5834 	 */
5835 	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
5836 			SCTP_STATE(SCTP_STATE_SHUTDOWN_PENDING));
5837 
5838 	disposition = SCTP_DISPOSITION_CONSUME;
5839 	if (sctp_outq_is_empty(&asoc->outqueue)) {
5840 		disposition = sctp_sf_do_9_2_start_shutdown(net, ep, asoc, type,
5841 							    arg, commands);
5842 	}
5843 	return disposition;
5844 }
5845 
5846 /*****************************************************************************
5847  * These are sa state functions which could apply to all types of events.
5848  ****************************************************************************/
5849 
5850 /*
5851  * This table entry is not implemented.
5852  *
5853  * Inputs
5854  * (endpoint, asoc, chunk)
5855  *
5856  * The return value is the disposition of the chunk.
5857  */
5858 sctp_disposition_t sctp_sf_not_impl(struct net *net,
5859 				    const struct sctp_endpoint *ep,
5860 				    const struct sctp_association *asoc,
5861 				    const sctp_subtype_t type,
5862 				    void *arg,
5863 				    sctp_cmd_seq_t *commands)
5864 {
5865 	return SCTP_DISPOSITION_NOT_IMPL;
5866 }
5867 
5868 /*
5869  * This table entry represents a bug.
5870  *
5871  * Inputs
5872  * (endpoint, asoc, chunk)
5873  *
5874  * The return value is the disposition of the chunk.
5875  */
5876 sctp_disposition_t sctp_sf_bug(struct net *net,
5877 			       const struct sctp_endpoint *ep,
5878 			       const struct sctp_association *asoc,
5879 			       const sctp_subtype_t type,
5880 			       void *arg,
5881 			       sctp_cmd_seq_t *commands)
5882 {
5883 	return SCTP_DISPOSITION_BUG;
5884 }
5885 
5886 /*
5887  * This table entry represents the firing of a timer in the wrong state.
5888  * Since timer deletion cannot be guaranteed a timer 'may' end up firing
5889  * when the association is in the wrong state.   This event should
5890  * be ignored, so as to prevent any rearming of the timer.
5891  *
5892  * Inputs
5893  * (endpoint, asoc, chunk)
5894  *
5895  * The return value is the disposition of the chunk.
5896  */
5897 sctp_disposition_t sctp_sf_timer_ignore(struct net *net,
5898 					const struct sctp_endpoint *ep,
5899 					const struct sctp_association *asoc,
5900 					const sctp_subtype_t type,
5901 					void *arg,
5902 					sctp_cmd_seq_t *commands)
5903 {
5904 	pr_debug("%s: timer %d ignored\n", __func__, type.chunk);
5905 
5906 	return SCTP_DISPOSITION_CONSUME;
5907 }
5908 
5909 /********************************************************************
5910  * 2nd Level Abstractions
5911  ********************************************************************/
5912 
5913 /* Pull the SACK chunk based on the SACK header. */
5914 static struct sctp_sackhdr *sctp_sm_pull_sack(struct sctp_chunk *chunk)
5915 {
5916 	struct sctp_sackhdr *sack;
5917 	unsigned int len;
5918 	__u16 num_blocks;
5919 	__u16 num_dup_tsns;
5920 
5921 	/* Protect ourselves from reading too far into
5922 	 * the skb from a bogus sender.
5923 	 */
5924 	sack = (struct sctp_sackhdr *) chunk->skb->data;
5925 
5926 	num_blocks = ntohs(sack->num_gap_ack_blocks);
5927 	num_dup_tsns = ntohs(sack->num_dup_tsns);
5928 	len = sizeof(struct sctp_sackhdr);
5929 	len += (num_blocks + num_dup_tsns) * sizeof(__u32);
5930 	if (len > chunk->skb->len)
5931 		return NULL;
5932 
5933 	skb_pull(chunk->skb, len);
5934 
5935 	return sack;
5936 }
5937 
5938 /* Create an ABORT packet to be sent as a response, with the specified
5939  * error causes.
5940  */
5941 static struct sctp_packet *sctp_abort_pkt_new(struct net *net,
5942 				  const struct sctp_endpoint *ep,
5943 				  const struct sctp_association *asoc,
5944 				  struct sctp_chunk *chunk,
5945 				  const void *payload,
5946 				  size_t paylen)
5947 {
5948 	struct sctp_packet *packet;
5949 	struct sctp_chunk *abort;
5950 
5951 	packet = sctp_ootb_pkt_new(net, asoc, chunk);
5952 
5953 	if (packet) {
5954 		/* Make an ABORT.
5955 		 * The T bit will be set if the asoc is NULL.
5956 		 */
5957 		abort = sctp_make_abort(asoc, chunk, paylen);
5958 		if (!abort) {
5959 			sctp_ootb_pkt_free(packet);
5960 			return NULL;
5961 		}
5962 
5963 		/* Reflect vtag if T-Bit is set */
5964 		if (sctp_test_T_bit(abort))
5965 			packet->vtag = ntohl(chunk->sctp_hdr->vtag);
5966 
5967 		/* Add specified error causes, i.e., payload, to the
5968 		 * end of the chunk.
5969 		 */
5970 		sctp_addto_chunk(abort, paylen, payload);
5971 
5972 		/* Set the skb to the belonging sock for accounting.  */
5973 		abort->skb->sk = ep->base.sk;
5974 
5975 		sctp_packet_append_chunk(packet, abort);
5976 
5977 	}
5978 
5979 	return packet;
5980 }
5981 
5982 /* Allocate a packet for responding in the OOTB conditions.  */
5983 static struct sctp_packet *sctp_ootb_pkt_new(struct net *net,
5984 					     const struct sctp_association *asoc,
5985 					     const struct sctp_chunk *chunk)
5986 {
5987 	struct sctp_packet *packet;
5988 	struct sctp_transport *transport;
5989 	__u16 sport;
5990 	__u16 dport;
5991 	__u32 vtag;
5992 
5993 	/* Get the source and destination port from the inbound packet.  */
5994 	sport = ntohs(chunk->sctp_hdr->dest);
5995 	dport = ntohs(chunk->sctp_hdr->source);
5996 
5997 	/* The V-tag is going to be the same as the inbound packet if no
5998 	 * association exists, otherwise, use the peer's vtag.
5999 	 */
6000 	if (asoc) {
6001 		/* Special case the INIT-ACK as there is no peer's vtag
6002 		 * yet.
6003 		 */
6004 		switch (chunk->chunk_hdr->type) {
6005 		case SCTP_CID_INIT_ACK:
6006 		{
6007 			sctp_initack_chunk_t *initack;
6008 
6009 			initack = (sctp_initack_chunk_t *)chunk->chunk_hdr;
6010 			vtag = ntohl(initack->init_hdr.init_tag);
6011 			break;
6012 		}
6013 		default:
6014 			vtag = asoc->peer.i.init_tag;
6015 			break;
6016 		}
6017 	} else {
6018 		/* Special case the INIT and stale COOKIE_ECHO as there is no
6019 		 * vtag yet.
6020 		 */
6021 		switch (chunk->chunk_hdr->type) {
6022 		case SCTP_CID_INIT:
6023 		{
6024 			sctp_init_chunk_t *init;
6025 
6026 			init = (sctp_init_chunk_t *)chunk->chunk_hdr;
6027 			vtag = ntohl(init->init_hdr.init_tag);
6028 			break;
6029 		}
6030 		default:
6031 			vtag = ntohl(chunk->sctp_hdr->vtag);
6032 			break;
6033 		}
6034 	}
6035 
6036 	/* Make a transport for the bucket, Eliza... */
6037 	transport = sctp_transport_new(net, sctp_source(chunk), GFP_ATOMIC);
6038 	if (!transport)
6039 		goto nomem;
6040 
6041 	/* Cache a route for the transport with the chunk's destination as
6042 	 * the source address.
6043 	 */
6044 	sctp_transport_route(transport, (union sctp_addr *)&chunk->dest,
6045 			     sctp_sk(net->sctp.ctl_sock));
6046 
6047 	packet = sctp_packet_init(&transport->packet, transport, sport, dport);
6048 	packet = sctp_packet_config(packet, vtag, 0);
6049 
6050 	return packet;
6051 
6052 nomem:
6053 	return NULL;
6054 }
6055 
6056 /* Free the packet allocated earlier for responding in the OOTB condition.  */
6057 void sctp_ootb_pkt_free(struct sctp_packet *packet)
6058 {
6059 	sctp_transport_free(packet->transport);
6060 }
6061 
6062 /* Send a stale cookie error when a invalid COOKIE ECHO chunk is found  */
6063 static void sctp_send_stale_cookie_err(struct net *net,
6064 				       const struct sctp_endpoint *ep,
6065 				       const struct sctp_association *asoc,
6066 				       const struct sctp_chunk *chunk,
6067 				       sctp_cmd_seq_t *commands,
6068 				       struct sctp_chunk *err_chunk)
6069 {
6070 	struct sctp_packet *packet;
6071 
6072 	if (err_chunk) {
6073 		packet = sctp_ootb_pkt_new(net, asoc, chunk);
6074 		if (packet) {
6075 			struct sctp_signed_cookie *cookie;
6076 
6077 			/* Override the OOTB vtag from the cookie. */
6078 			cookie = chunk->subh.cookie_hdr;
6079 			packet->vtag = cookie->c.peer_vtag;
6080 
6081 			/* Set the skb to the belonging sock for accounting. */
6082 			err_chunk->skb->sk = ep->base.sk;
6083 			sctp_packet_append_chunk(packet, err_chunk);
6084 			sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
6085 					SCTP_PACKET(packet));
6086 			SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
6087 		} else
6088 			sctp_chunk_free (err_chunk);
6089 	}
6090 }
6091 
6092 
6093 /* Process a data chunk */
6094 static int sctp_eat_data(const struct sctp_association *asoc,
6095 			 struct sctp_chunk *chunk,
6096 			 sctp_cmd_seq_t *commands)
6097 {
6098 	sctp_datahdr_t *data_hdr;
6099 	struct sctp_chunk *err;
6100 	size_t datalen;
6101 	sctp_verb_t deliver;
6102 	int tmp;
6103 	__u32 tsn;
6104 	struct sctp_tsnmap *map = (struct sctp_tsnmap *)&asoc->peer.tsn_map;
6105 	struct sock *sk = asoc->base.sk;
6106 	struct net *net = sock_net(sk);
6107 	u16 ssn;
6108 	u16 sid;
6109 	u8 ordered = 0;
6110 
6111 	data_hdr = chunk->subh.data_hdr = (sctp_datahdr_t *)chunk->skb->data;
6112 	skb_pull(chunk->skb, sizeof(sctp_datahdr_t));
6113 
6114 	tsn = ntohl(data_hdr->tsn);
6115 	pr_debug("%s: TSN 0x%x\n", __func__, tsn);
6116 
6117 	/* ASSERT:  Now skb->data is really the user data.  */
6118 
6119 	/* Process ECN based congestion.
6120 	 *
6121 	 * Since the chunk structure is reused for all chunks within
6122 	 * a packet, we use ecn_ce_done to track if we've already
6123 	 * done CE processing for this packet.
6124 	 *
6125 	 * We need to do ECN processing even if we plan to discard the
6126 	 * chunk later.
6127 	 */
6128 
6129 	if (!chunk->ecn_ce_done) {
6130 		struct sctp_af *af;
6131 		chunk->ecn_ce_done = 1;
6132 
6133 		af = sctp_get_af_specific(
6134 			ipver2af(ip_hdr(chunk->skb)->version));
6135 
6136 		if (af && af->is_ce(chunk->skb) && asoc->peer.ecn_capable) {
6137 			/* Do real work as sideffect. */
6138 			sctp_add_cmd_sf(commands, SCTP_CMD_ECN_CE,
6139 					SCTP_U32(tsn));
6140 		}
6141 	}
6142 
6143 	tmp = sctp_tsnmap_check(&asoc->peer.tsn_map, tsn);
6144 	if (tmp < 0) {
6145 		/* The TSN is too high--silently discard the chunk and
6146 		 * count on it getting retransmitted later.
6147 		 */
6148 		if (chunk->asoc)
6149 			chunk->asoc->stats.outofseqtsns++;
6150 		return SCTP_IERROR_HIGH_TSN;
6151 	} else if (tmp > 0) {
6152 		/* This is a duplicate.  Record it.  */
6153 		sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_DUP, SCTP_U32(tsn));
6154 		return SCTP_IERROR_DUP_TSN;
6155 	}
6156 
6157 	/* This is a new TSN.  */
6158 
6159 	/* Discard if there is no room in the receive window.
6160 	 * Actually, allow a little bit of overflow (up to a MTU).
6161 	 */
6162 	datalen = ntohs(chunk->chunk_hdr->length);
6163 	datalen -= sizeof(sctp_data_chunk_t);
6164 
6165 	deliver = SCTP_CMD_CHUNK_ULP;
6166 
6167 	/* Think about partial delivery. */
6168 	if ((datalen >= asoc->rwnd) && (!asoc->ulpq.pd_mode)) {
6169 
6170 		/* Even if we don't accept this chunk there is
6171 		 * memory pressure.
6172 		 */
6173 		sctp_add_cmd_sf(commands, SCTP_CMD_PART_DELIVER, SCTP_NULL());
6174 	}
6175 
6176 	/* Spill over rwnd a little bit.  Note: While allowed, this spill over
6177 	 * seems a bit troublesome in that frag_point varies based on
6178 	 * PMTU.  In cases, such as loopback, this might be a rather
6179 	 * large spill over.
6180 	 */
6181 	if ((!chunk->data_accepted) && (!asoc->rwnd ||
6182 	    (datalen > asoc->rwnd + asoc->frag_point))) {
6183 
6184 		/* If this is the next TSN, consider reneging to make
6185 		 * room.   Note: Playing nice with a confused sender.  A
6186 		 * malicious sender can still eat up all our buffer
6187 		 * space and in the future we may want to detect and
6188 		 * do more drastic reneging.
6189 		 */
6190 		if (sctp_tsnmap_has_gap(map) &&
6191 		    (sctp_tsnmap_get_ctsn(map) + 1) == tsn) {
6192 			pr_debug("%s: reneging for tsn:%u\n", __func__, tsn);
6193 			deliver = SCTP_CMD_RENEGE;
6194 		} else {
6195 			pr_debug("%s: discard tsn:%u len:%zu, rwnd:%d\n",
6196 				 __func__, tsn, datalen, asoc->rwnd);
6197 
6198 			return SCTP_IERROR_IGNORE_TSN;
6199 		}
6200 	}
6201 
6202 	/*
6203 	 * Also try to renege to limit our memory usage in the event that
6204 	 * we are under memory pressure
6205 	 * If we can't renege, don't worry about it, the sk_rmem_schedule
6206 	 * in sctp_ulpevent_make_rcvmsg will drop the frame if we grow our
6207 	 * memory usage too much
6208 	 */
6209 	if (*sk->sk_prot_creator->memory_pressure) {
6210 		if (sctp_tsnmap_has_gap(map) &&
6211 		    (sctp_tsnmap_get_ctsn(map) + 1) == tsn) {
6212 			pr_debug("%s: under pressure, reneging for tsn:%u\n",
6213 				 __func__, tsn);
6214 			deliver = SCTP_CMD_RENEGE;
6215 		 }
6216 	}
6217 
6218 	/*
6219 	 * Section 3.3.10.9 No User Data (9)
6220 	 *
6221 	 * Cause of error
6222 	 * ---------------
6223 	 * No User Data:  This error cause is returned to the originator of a
6224 	 * DATA chunk if a received DATA chunk has no user data.
6225 	 */
6226 	if (unlikely(0 == datalen)) {
6227 		err = sctp_make_abort_no_data(asoc, chunk, tsn);
6228 		if (err) {
6229 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
6230 					SCTP_CHUNK(err));
6231 		}
6232 		/* We are going to ABORT, so we might as well stop
6233 		 * processing the rest of the chunks in the packet.
6234 		 */
6235 		sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
6236 		sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
6237 				SCTP_ERROR(ECONNABORTED));
6238 		sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
6239 				SCTP_PERR(SCTP_ERROR_NO_DATA));
6240 		SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
6241 		SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
6242 		return SCTP_IERROR_NO_DATA;
6243 	}
6244 
6245 	chunk->data_accepted = 1;
6246 
6247 	/* Note: Some chunks may get overcounted (if we drop) or overcounted
6248 	 * if we renege and the chunk arrives again.
6249 	 */
6250 	if (chunk->chunk_hdr->flags & SCTP_DATA_UNORDERED) {
6251 		SCTP_INC_STATS(net, SCTP_MIB_INUNORDERCHUNKS);
6252 		if (chunk->asoc)
6253 			chunk->asoc->stats.iuodchunks++;
6254 	} else {
6255 		SCTP_INC_STATS(net, SCTP_MIB_INORDERCHUNKS);
6256 		if (chunk->asoc)
6257 			chunk->asoc->stats.iodchunks++;
6258 		ordered = 1;
6259 	}
6260 
6261 	/* RFC 2960 6.5 Stream Identifier and Stream Sequence Number
6262 	 *
6263 	 * If an endpoint receive a DATA chunk with an invalid stream
6264 	 * identifier, it shall acknowledge the reception of the DATA chunk
6265 	 * following the normal procedure, immediately send an ERROR chunk
6266 	 * with cause set to "Invalid Stream Identifier" (See Section 3.3.10)
6267 	 * and discard the DATA chunk.
6268 	 */
6269 	sid = ntohs(data_hdr->stream);
6270 	if (sid >= asoc->c.sinit_max_instreams) {
6271 		/* Mark tsn as received even though we drop it */
6272 		sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_TSN, SCTP_U32(tsn));
6273 
6274 		err = sctp_make_op_error(asoc, chunk, SCTP_ERROR_INV_STRM,
6275 					 &data_hdr->stream,
6276 					 sizeof(data_hdr->stream),
6277 					 sizeof(u16));
6278 		if (err)
6279 			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
6280 					SCTP_CHUNK(err));
6281 		return SCTP_IERROR_BAD_STREAM;
6282 	}
6283 
6284 	/* Check to see if the SSN is possible for this TSN.
6285 	 * The biggest gap we can record is 4K wide.  Since SSNs wrap
6286 	 * at an unsigned short, there is no way that an SSN can
6287 	 * wrap and for a valid TSN.  We can simply check if the current
6288 	 * SSN is smaller then the next expected one.  If it is, it wrapped
6289 	 * and is invalid.
6290 	 */
6291 	ssn = ntohs(data_hdr->ssn);
6292 	if (ordered && SSN_lt(ssn, sctp_ssn_peek(&asoc->ssnmap->in, sid))) {
6293 		return SCTP_IERROR_PROTO_VIOLATION;
6294 	}
6295 
6296 	/* Send the data up to the user.  Note:  Schedule  the
6297 	 * SCTP_CMD_CHUNK_ULP cmd before the SCTP_CMD_GEN_SACK, as the SACK
6298 	 * chunk needs the updated rwnd.
6299 	 */
6300 	sctp_add_cmd_sf(commands, deliver, SCTP_CHUNK(chunk));
6301 
6302 	return SCTP_IERROR_NO_ERROR;
6303 }
6304