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

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