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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 #define CREATE_TRACE_POINTS
 63 #include <trace/events/sctp.h>
 64 
 65 static struct sctp_packet *sctp_abort_pkt_new(
 66                                         struct net *net,
 67                                         const struct sctp_endpoint *ep,
 68                                         const struct sctp_association *asoc,
 69                                         struct sctp_chunk *chunk,
 70                                         const void *payload, size_t paylen);
 71 static int sctp_eat_data(const struct sctp_association *asoc,
 72                          struct sctp_chunk *chunk,
 73                          struct sctp_cmd_seq *commands);
 74 static struct sctp_packet *sctp_ootb_pkt_new(
 75                                         struct net *net,
 76                                         const struct sctp_association *asoc,
 77                                         const struct sctp_chunk *chunk);
 78 static void sctp_send_stale_cookie_err(struct net *net,
 79                                        const struct sctp_endpoint *ep,
 80                                        const struct sctp_association *asoc,
 81                                        const struct sctp_chunk *chunk,
 82                                        struct sctp_cmd_seq *commands,
 83                                        struct sctp_chunk *err_chunk);
 84 static enum sctp_disposition sctp_sf_do_5_2_6_stale(
 85                                         struct net *net,
 86                                         const struct sctp_endpoint *ep,
 87                                         const struct sctp_association *asoc,
 88                                         const union sctp_subtype type,
 89                                         void *arg,
 90                                         struct sctp_cmd_seq *commands);
 91 static enum sctp_disposition sctp_sf_shut_8_4_5(
 92                                         struct net *net,
 93                                         const struct sctp_endpoint *ep,
 94                                         const struct sctp_association *asoc,
 95                                         const union sctp_subtype type,
 96                                         void *arg,
 97                                         struct sctp_cmd_seq *commands);
 98 static enum sctp_disposition sctp_sf_tabort_8_4_8(
 99                                         struct net *net,
100                                         const struct sctp_endpoint *ep,
101                                         const struct sctp_association *asoc,
102                                         const union sctp_subtype type,
103                                         void *arg,
104                                         struct sctp_cmd_seq *commands);
105 static struct sctp_sackhdr *sctp_sm_pull_sack(struct sctp_chunk *chunk);
106 
107 static enum sctp_disposition sctp_stop_t1_and_abort(
108                                         struct net *net,
109                                         struct sctp_cmd_seq *commands,
110                                         __be16 error, int sk_err,
111                                         const struct sctp_association *asoc,
112                                         struct sctp_transport *transport);
113 
114 static enum sctp_disposition sctp_sf_abort_violation(
115                                         struct net *net,
116                                         const struct sctp_endpoint *ep,
117                                         const struct sctp_association *asoc,
118                                         void *arg,
119                                         struct sctp_cmd_seq *commands,
120                                         const __u8 *payload,
121                                         const size_t paylen);
122 
123 static enum sctp_disposition sctp_sf_violation_chunklen(
124                                         struct net *net,
125                                         const struct sctp_endpoint *ep,
126                                         const struct sctp_association *asoc,
127                                         const union sctp_subtype type,
128                                         void *arg,
129                                         struct sctp_cmd_seq *commands);
130 
131 static enum sctp_disposition sctp_sf_violation_paramlen(
132                                         struct net *net,
133                                         const struct sctp_endpoint *ep,
134                                         const struct sctp_association *asoc,
135                                         const union sctp_subtype type,
136                                         void *arg, void *ext,
137                                         struct sctp_cmd_seq *commands);
138 
139 static enum sctp_disposition sctp_sf_violation_ctsn(
140                                         struct net *net,
141                                         const struct sctp_endpoint *ep,
142                                         const struct sctp_association *asoc,
143                                         const union sctp_subtype type,
144                                         void *arg,
145                                         struct sctp_cmd_seq *commands);
146 
147 static enum sctp_disposition sctp_sf_violation_chunk(
148                                         struct net *net,
149                                         const struct sctp_endpoint *ep,
150                                         const struct sctp_association *asoc,
151                                         const union sctp_subtype type,
152                                         void *arg,
153                                         struct sctp_cmd_seq *commands);
154 
155 static enum sctp_ierror sctp_sf_authenticate(
156                                         const struct sctp_association *asoc,
157                                         struct sctp_chunk *chunk);
158 
159 static enum sctp_disposition __sctp_sf_do_9_1_abort(
160                                         struct net *net,
161                                         const struct sctp_endpoint *ep,
162                                         const struct sctp_association *asoc,
163                                         const union sctp_subtype type,
164                                         void *arg,
165                                         struct sctp_cmd_seq *commands);
166 
167 /* Small helper function that checks if the chunk length
168  * is of the appropriate length.  The 'required_length' argument
169  * is set to be the size of a specific chunk we are testing.
170  * Return Values:  true  = Valid length
171  *                 false = Invalid length
172  *
173  */
174 static inline bool sctp_chunk_length_valid(struct sctp_chunk *chunk,
175                                            __u16 required_length)
176 {
177         __u16 chunk_length = ntohs(chunk->chunk_hdr->length);
178 
179         /* Previously already marked? */
180         if (unlikely(chunk->pdiscard))
181                 return false;
182         if (unlikely(chunk_length < required_length))
183                 return false;
184 
185         return true;
186 }
187 
188 /**********************************************************
189  * These are the state functions for handling chunk events.
190  **********************************************************/
191 
192 /*
193  * Process the final SHUTDOWN COMPLETE.
194  *
195  * Section: 4 (C) (diagram), 9.2
196  * Upon reception of the SHUTDOWN COMPLETE chunk the endpoint will verify
197  * that it is in SHUTDOWN-ACK-SENT state, if it is not the chunk should be
198  * discarded. If the endpoint is in the SHUTDOWN-ACK-SENT state the endpoint
199  * should stop the T2-shutdown timer and remove all knowledge of the
200  * association (and thus the association enters the CLOSED state).
201  *
202  * Verification Tag: 8.5.1(C), sctpimpguide 2.41.
203  * C) Rules for packet carrying SHUTDOWN COMPLETE:
204  * ...
205  * - The receiver of a SHUTDOWN COMPLETE shall accept the packet
206  *   if the Verification Tag field of the packet matches its own tag and
207  *   the T bit is not set
208  *   OR
209  *   it is set to its peer's tag and the T bit is set in the Chunk
210  *   Flags.
211  *   Otherwise, the receiver MUST silently discard the packet
212  *   and take no further action.  An endpoint MUST ignore the
213  *   SHUTDOWN COMPLETE if it is not in the SHUTDOWN-ACK-SENT state.
214  *
215  * Inputs
216  * (endpoint, asoc, chunk)
217  *
218  * Outputs
219  * (asoc, reply_msg, msg_up, timers, counters)
220  *
221  * The return value is the disposition of the chunk.
222  */
223 enum sctp_disposition sctp_sf_do_4_C(struct net *net,
224                                      const struct sctp_endpoint *ep,
225                                      const struct sctp_association *asoc,
226                                      const union sctp_subtype type,
227                                      void *arg, struct sctp_cmd_seq *commands)
228 {
229         struct sctp_chunk *chunk = arg;
230         struct sctp_ulpevent *ev;
231 
232         if (!sctp_vtag_verify_either(chunk, asoc))
233                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
234 
235         /* RFC 2960 6.10 Bundling
236          *
237          * An endpoint MUST NOT bundle INIT, INIT ACK or
238          * SHUTDOWN COMPLETE with any other chunks.
239          */
240         if (!chunk->singleton)
241                 return sctp_sf_violation_chunk(net, ep, asoc, type, arg, commands);
242 
243         /* Make sure that the SHUTDOWN_COMPLETE chunk has a valid length. */
244         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
245                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
246                                                   commands);
247 
248         /* RFC 2960 10.2 SCTP-to-ULP
249          *
250          * H) SHUTDOWN COMPLETE notification
251          *
252          * When SCTP completes the shutdown procedures (section 9.2) this
253          * notification is passed to the upper layer.
254          */
255         ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_SHUTDOWN_COMP,
256                                              0, 0, 0, NULL, GFP_ATOMIC);
257         if (ev)
258                 sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
259                                 SCTP_ULPEVENT(ev));
260 
261         /* Upon reception of the SHUTDOWN COMPLETE chunk the endpoint
262          * will verify that it is in SHUTDOWN-ACK-SENT state, if it is
263          * not the chunk should be discarded. If the endpoint is in
264          * the SHUTDOWN-ACK-SENT state the endpoint should stop the
265          * T2-shutdown timer and remove all knowledge of the
266          * association (and thus the association enters the CLOSED
267          * state).
268          */
269         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
270                         SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
271 
272         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
273                         SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
274 
275         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
276                         SCTP_STATE(SCTP_STATE_CLOSED));
277 
278         SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS);
279         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
280 
281         sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
282 
283         return SCTP_DISPOSITION_DELETE_TCB;
284 }
285 
286 /*
287  * Respond to a normal INIT chunk.
288  * We are the side that is being asked for an association.
289  *
290  * Section: 5.1 Normal Establishment of an Association, B
291  * B) "Z" shall respond immediately with an INIT ACK chunk.  The
292  *    destination IP address of the INIT ACK MUST be set to the source
293  *    IP address of the INIT to which this INIT ACK is responding.  In
294  *    the response, besides filling in other parameters, "Z" must set the
295  *    Verification Tag field to Tag_A, and also provide its own
296  *    Verification Tag (Tag_Z) in the Initiate Tag field.
297  *
298  * Verification Tag: Must be 0.
299  *
300  * Inputs
301  * (endpoint, asoc, chunk)
302  *
303  * Outputs
304  * (asoc, reply_msg, msg_up, timers, counters)
305  *
306  * The return value is the disposition of the chunk.
307  */
308 enum sctp_disposition sctp_sf_do_5_1B_init(struct net *net,
309                                            const struct sctp_endpoint *ep,
310                                            const struct sctp_association *asoc,
311                                            const union sctp_subtype type,
312                                            void *arg,
313                                            struct sctp_cmd_seq *commands)
314 {
315         struct sctp_chunk *chunk = arg, *repl, *err_chunk;
316         struct sctp_unrecognized_param *unk_param;
317         struct sctp_association *new_asoc;
318         struct sctp_packet *packet;
319         int len;
320 
321         /* Update socket peer label if first association. */
322         if (security_sctp_assoc_request((struct sctp_endpoint *)ep,
323                                         chunk->skb))
324                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
325 
326         /* 6.10 Bundling
327          * An endpoint MUST NOT bundle INIT, INIT ACK or
328          * SHUTDOWN COMPLETE with any other chunks.
329          *
330          * IG Section 2.11.2
331          * Furthermore, we require that the receiver of an INIT chunk MUST
332          * enforce these rules by silently discarding an arriving packet
333          * with an INIT chunk that is bundled with other chunks.
334          */
335         if (!chunk->singleton)
336                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
337 
338         /* If the packet is an OOTB packet which is temporarily on the
339          * control endpoint, respond with an ABORT.
340          */
341         if (ep == sctp_sk(net->sctp.ctl_sock)->ep) {
342                 SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
343                 return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
344         }
345 
346         /* 3.1 A packet containing an INIT chunk MUST have a zero Verification
347          * Tag.
348          */
349         if (chunk->sctp_hdr->vtag != 0)
350                 return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
351 
352         /* Make sure that the INIT chunk has a valid length.
353          * Normally, this would cause an ABORT with a Protocol Violation
354          * error, but since we don't have an association, we'll
355          * just discard the packet.
356          */
357         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_init_chunk)))
358                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
359 
360         /* If the INIT is coming toward a closing socket, we'll send back
361          * and ABORT.  Essentially, this catches the race of INIT being
362          * backloged to the socket at the same time as the user isses close().
363          * Since the socket and all its associations are going away, we
364          * can treat this OOTB
365          */
366         if (sctp_sstate(ep->base.sk, CLOSING))
367                 return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
368 
369         /* Verify the INIT chunk before processing it. */
370         err_chunk = NULL;
371         if (!sctp_verify_init(net, ep, asoc, chunk->chunk_hdr->type,
372                               (struct sctp_init_chunk *)chunk->chunk_hdr, chunk,
373                               &err_chunk)) {
374                 /* This chunk contains fatal error. It is to be discarded.
375                  * Send an ABORT, with causes if there is any.
376                  */
377                 if (err_chunk) {
378                         packet = sctp_abort_pkt_new(net, ep, asoc, arg,
379                                         (__u8 *)(err_chunk->chunk_hdr) +
380                                         sizeof(struct sctp_chunkhdr),
381                                         ntohs(err_chunk->chunk_hdr->length) -
382                                         sizeof(struct sctp_chunkhdr));
383 
384                         sctp_chunk_free(err_chunk);
385 
386                         if (packet) {
387                                 sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
388                                                 SCTP_PACKET(packet));
389                                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
390                                 return SCTP_DISPOSITION_CONSUME;
391                         } else {
392                                 return SCTP_DISPOSITION_NOMEM;
393                         }
394                 } else {
395                         return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg,
396                                                     commands);
397                 }
398         }
399 
400         /* Grab the INIT header.  */
401         chunk->subh.init_hdr = (struct sctp_inithdr *)chunk->skb->data;
402 
403         /* Tag the variable length parameters.  */
404         chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(struct sctp_inithdr));
405 
406         new_asoc = sctp_make_temp_asoc(ep, chunk, GFP_ATOMIC);
407         if (!new_asoc)
408                 goto nomem;
409 
410         if (sctp_assoc_set_bind_addr_from_ep(new_asoc,
411                                              sctp_scope(sctp_source(chunk)),
412                                              GFP_ATOMIC) < 0)
413                 goto nomem_init;
414 
415         /* The call, sctp_process_init(), can fail on memory allocation.  */
416         if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk),
417                                (struct sctp_init_chunk *)chunk->chunk_hdr,
418                                GFP_ATOMIC))
419                 goto nomem_init;
420 
421         /* B) "Z" shall respond immediately with an INIT ACK chunk.  */
422 
423         /* If there are errors need to be reported for unknown parameters,
424          * make sure to reserve enough room in the INIT ACK for them.
425          */
426         len = 0;
427         if (err_chunk)
428                 len = ntohs(err_chunk->chunk_hdr->length) -
429                       sizeof(struct sctp_chunkhdr);
430 
431         repl = sctp_make_init_ack(new_asoc, chunk, GFP_ATOMIC, len);
432         if (!repl)
433                 goto nomem_init;
434 
435         /* If there are errors need to be reported for unknown parameters,
436          * include them in the outgoing INIT ACK as "Unrecognized parameter"
437          * parameter.
438          */
439         if (err_chunk) {
440                 /* Get the "Unrecognized parameter" parameter(s) out of the
441                  * ERROR chunk generated by sctp_verify_init(). Since the
442                  * error cause code for "unknown parameter" and the
443                  * "Unrecognized parameter" type is the same, we can
444                  * construct the parameters in INIT ACK by copying the
445                  * ERROR causes over.
446                  */
447                 unk_param = (struct sctp_unrecognized_param *)
448                             ((__u8 *)(err_chunk->chunk_hdr) +
449                             sizeof(struct sctp_chunkhdr));
450                 /* Replace the cause code with the "Unrecognized parameter"
451                  * parameter type.
452                  */
453                 sctp_addto_chunk(repl, len, unk_param);
454                 sctp_chunk_free(err_chunk);
455         }
456 
457         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc));
458 
459         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
460 
461         /*
462          * Note:  After sending out INIT ACK with the State Cookie parameter,
463          * "Z" MUST NOT allocate any resources, nor keep any states for the
464          * new association.  Otherwise, "Z" will be vulnerable to resource
465          * attacks.
466          */
467         sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
468 
469         return SCTP_DISPOSITION_DELETE_TCB;
470 
471 nomem_init:
472         sctp_association_free(new_asoc);
473 nomem:
474         if (err_chunk)
475                 sctp_chunk_free(err_chunk);
476         return SCTP_DISPOSITION_NOMEM;
477 }
478 
479 /*
480  * Respond to a normal INIT ACK chunk.
481  * We are the side that is initiating the association.
482  *
483  * Section: 5.1 Normal Establishment of an Association, C
484  * C) Upon reception of the INIT ACK from "Z", "A" shall stop the T1-init
485  *    timer and leave COOKIE-WAIT state. "A" shall then send the State
486  *    Cookie received in the INIT ACK chunk in a COOKIE ECHO chunk, start
487  *    the T1-cookie timer, and enter the COOKIE-ECHOED state.
488  *
489  *    Note: The COOKIE ECHO chunk can be bundled with any pending outbound
490  *    DATA chunks, but it MUST be the first chunk in the packet and
491  *    until the COOKIE ACK is returned the sender MUST NOT send any
492  *    other packets to the peer.
493  *
494  * Verification Tag: 3.3.3
495  *   If the value of the Initiate Tag in a received INIT ACK chunk is
496  *   found to be 0, the receiver MUST treat it as an error and close the
497  *   association by transmitting an ABORT.
498  *
499  * Inputs
500  * (endpoint, asoc, chunk)
501  *
502  * Outputs
503  * (asoc, reply_msg, msg_up, timers, counters)
504  *
505  * The return value is the disposition of the chunk.
506  */
507 enum sctp_disposition sctp_sf_do_5_1C_ack(struct net *net,
508                                           const struct sctp_endpoint *ep,
509                                           const struct sctp_association *asoc,
510                                           const union sctp_subtype type,
511                                           void *arg,
512                                           struct sctp_cmd_seq *commands)
513 {
514         struct sctp_init_chunk *initchunk;
515         struct sctp_chunk *chunk = arg;
516         struct sctp_chunk *err_chunk;
517         struct sctp_packet *packet;
518 
519         if (!sctp_vtag_verify(chunk, asoc))
520                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
521 
522         /* 6.10 Bundling
523          * An endpoint MUST NOT bundle INIT, INIT ACK or
524          * SHUTDOWN COMPLETE with any other chunks.
525          */
526         if (!chunk->singleton)
527                 return sctp_sf_violation_chunk(net, ep, asoc, type, arg, commands);
528 
529         /* Make sure that the INIT-ACK chunk has a valid length */
530         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_initack_chunk)))
531                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
532                                                   commands);
533         /* Grab the INIT header.  */
534         chunk->subh.init_hdr = (struct sctp_inithdr *)chunk->skb->data;
535 
536         /* Verify the INIT chunk before processing it. */
537         err_chunk = NULL;
538         if (!sctp_verify_init(net, ep, asoc, chunk->chunk_hdr->type,
539                               (struct sctp_init_chunk *)chunk->chunk_hdr, chunk,
540                               &err_chunk)) {
541 
542                 enum sctp_error error = SCTP_ERROR_NO_RESOURCE;
543 
544                 /* This chunk contains fatal error. It is to be discarded.
545                  * Send an ABORT, with causes.  If there are no causes,
546                  * then there wasn't enough memory.  Just terminate
547                  * the association.
548                  */
549                 if (err_chunk) {
550                         packet = sctp_abort_pkt_new(net, ep, asoc, arg,
551                                         (__u8 *)(err_chunk->chunk_hdr) +
552                                         sizeof(struct sctp_chunkhdr),
553                                         ntohs(err_chunk->chunk_hdr->length) -
554                                         sizeof(struct sctp_chunkhdr));
555 
556                         sctp_chunk_free(err_chunk);
557 
558                         if (packet) {
559                                 sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
560                                                 SCTP_PACKET(packet));
561                                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
562                                 error = SCTP_ERROR_INV_PARAM;
563                         }
564                 }
565 
566                 /* SCTP-AUTH, Section 6.3:
567                  *    It should be noted that if the receiver wants to tear
568                  *    down an association in an authenticated way only, the
569                  *    handling of malformed packets should not result in
570                  *    tearing down the association.
571                  *
572                  * This means that if we only want to abort associations
573                  * in an authenticated way (i.e AUTH+ABORT), then we
574                  * can't destroy this association just because the packet
575                  * was malformed.
576                  */
577                 if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc))
578                         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
579 
580                 SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
581                 return sctp_stop_t1_and_abort(net, commands, error, ECONNREFUSED,
582                                                 asoc, chunk->transport);
583         }
584 
585         /* Tag the variable length parameters.  Note that we never
586          * convert the parameters in an INIT chunk.
587          */
588         chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(struct sctp_inithdr));
589 
590         initchunk = (struct sctp_init_chunk *)chunk->chunk_hdr;
591 
592         sctp_add_cmd_sf(commands, SCTP_CMD_PEER_INIT,
593                         SCTP_PEER_INIT(initchunk));
594 
595         /* Reset init error count upon receipt of INIT-ACK.  */
596         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_RESET, SCTP_NULL());
597 
598         /* 5.1 C) "A" shall stop the T1-init timer and leave
599          * COOKIE-WAIT state.  "A" shall then ... start the T1-cookie
600          * timer, and enter the COOKIE-ECHOED state.
601          */
602         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
603                         SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
604         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
605                         SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
606         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
607                         SCTP_STATE(SCTP_STATE_COOKIE_ECHOED));
608 
609         /* SCTP-AUTH: genereate the assocition shared keys so that
610          * we can potentially signe the COOKIE-ECHO.
611          */
612         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_SHKEY, SCTP_NULL());
613 
614         /* 5.1 C) "A" shall then send the State Cookie received in the
615          * INIT ACK chunk in a COOKIE ECHO chunk, ...
616          */
617         /* If there is any errors to report, send the ERROR chunk generated
618          * for unknown parameters as well.
619          */
620         sctp_add_cmd_sf(commands, SCTP_CMD_GEN_COOKIE_ECHO,
621                         SCTP_CHUNK(err_chunk));
622 
623         return SCTP_DISPOSITION_CONSUME;
624 }
625 
626 static bool sctp_auth_chunk_verify(struct net *net, struct sctp_chunk *chunk,
627                                    const struct sctp_association *asoc)
628 {
629         struct sctp_chunk auth;
630 
631         if (!chunk->auth_chunk)
632                 return true;
633 
634         /* SCTP-AUTH:  auth_chunk pointer is only set when the cookie-echo
635          * is supposed to be authenticated and we have to do delayed
636          * authentication.  We've just recreated the association using
637          * the information in the cookie and now it's much easier to
638          * do the authentication.
639          */
640 
641         /* Make sure that we and the peer are AUTH capable */
642         if (!net->sctp.auth_enable || !asoc->peer.auth_capable)
643                 return false;
644 
645         /* set-up our fake chunk so that we can process it */
646         auth.skb = chunk->auth_chunk;
647         auth.asoc = chunk->asoc;
648         auth.sctp_hdr = chunk->sctp_hdr;
649         auth.chunk_hdr = (struct sctp_chunkhdr *)
650                                 skb_push(chunk->auth_chunk,
651                                          sizeof(struct sctp_chunkhdr));
652         skb_pull(chunk->auth_chunk, sizeof(struct sctp_chunkhdr));
653         auth.transport = chunk->transport;
654 
655         return sctp_sf_authenticate(asoc, &auth) == SCTP_IERROR_NO_ERROR;
656 }
657 
658 /*
659  * Respond to a normal COOKIE ECHO chunk.
660  * We are the side that is being asked for an association.
661  *
662  * Section: 5.1 Normal Establishment of an Association, D
663  * D) Upon reception of the COOKIE ECHO chunk, Endpoint "Z" will reply
664  *    with a COOKIE ACK chunk after building a TCB and moving to
665  *    the ESTABLISHED state. A COOKIE ACK chunk may be bundled with
666  *    any pending DATA chunks (and/or SACK chunks), but the COOKIE ACK
667  *    chunk MUST be the first chunk in the packet.
668  *
669  *   IMPLEMENTATION NOTE: An implementation may choose to send the
670  *   Communication Up notification to the SCTP user upon reception
671  *   of a valid COOKIE ECHO chunk.
672  *
673  * Verification Tag: 8.5.1 Exceptions in Verification Tag Rules
674  * D) Rules for packet carrying a COOKIE ECHO
675  *
676  * - When sending a COOKIE ECHO, the endpoint MUST use the value of the
677  *   Initial Tag received in the INIT ACK.
678  *
679  * - The receiver of a COOKIE ECHO follows the procedures in Section 5.
680  *
681  * Inputs
682  * (endpoint, asoc, chunk)
683  *
684  * Outputs
685  * (asoc, reply_msg, msg_up, timers, counters)
686  *
687  * The return value is the disposition of the chunk.
688  */
689 enum sctp_disposition sctp_sf_do_5_1D_ce(struct net *net,
690                                          const struct sctp_endpoint *ep,
691                                          const struct sctp_association *asoc,
692                                          const union sctp_subtype type,
693                                          void *arg,
694                                          struct sctp_cmd_seq *commands)
695 {
696         struct sctp_ulpevent *ev, *ai_ev = NULL, *auth_ev = NULL;
697         struct sctp_association *new_asoc;
698         struct sctp_init_chunk *peer_init;
699         struct sctp_chunk *chunk = arg;
700         struct sctp_chunk *err_chk_p;
701         struct sctp_chunk *repl;
702         struct sock *sk;
703         int error = 0;
704 
705         /* If the packet is an OOTB packet which is temporarily on the
706          * control endpoint, respond with an ABORT.
707          */
708         if (ep == sctp_sk(net->sctp.ctl_sock)->ep) {
709                 SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
710                 return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
711         }
712 
713         /* Make sure that the COOKIE_ECHO chunk has a valid length.
714          * In this case, we check that we have enough for at least a
715          * chunk header.  More detailed verification is done
716          * in sctp_unpack_cookie().
717          */
718         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
719                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
720 
721         /* If the endpoint is not listening or if the number of associations
722          * on the TCP-style socket exceed the max backlog, respond with an
723          * ABORT.
724          */
725         sk = ep->base.sk;
726         if (!sctp_sstate(sk, LISTENING) ||
727             (sctp_style(sk, TCP) && sk_acceptq_is_full(sk)))
728                 return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
729 
730         /* "Decode" the chunk.  We have no optional parameters so we
731          * are in good shape.
732          */
733         chunk->subh.cookie_hdr =
734                 (struct sctp_signed_cookie *)chunk->skb->data;
735         if (!pskb_pull(chunk->skb, ntohs(chunk->chunk_hdr->length) -
736                                          sizeof(struct sctp_chunkhdr)))
737                 goto nomem;
738 
739         /* 5.1 D) Upon reception of the COOKIE ECHO chunk, Endpoint
740          * "Z" will reply with a COOKIE ACK chunk after building a TCB
741          * and moving to the ESTABLISHED state.
742          */
743         new_asoc = sctp_unpack_cookie(ep, asoc, chunk, GFP_ATOMIC, &error,
744                                       &err_chk_p);
745 
746         /* FIXME:
747          * If the re-build failed, what is the proper error path
748          * from here?
749          *
750          * [We should abort the association. --piggy]
751          */
752         if (!new_asoc) {
753                 /* FIXME: Several errors are possible.  A bad cookie should
754                  * be silently discarded, but think about logging it too.
755                  */
756                 switch (error) {
757                 case -SCTP_IERROR_NOMEM:
758                         goto nomem;
759 
760                 case -SCTP_IERROR_STALE_COOKIE:
761                         sctp_send_stale_cookie_err(net, ep, asoc, chunk, commands,
762                                                    err_chk_p);
763                         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
764 
765                 case -SCTP_IERROR_BAD_SIG:
766                 default:
767                         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
768                 }
769         }
770 
771 
772         /* Delay state machine commands until later.
773          *
774          * Re-build the bind address for the association is done in
775          * the sctp_unpack_cookie() already.
776          */
777         /* This is a brand-new association, so these are not yet side
778          * effects--it is safe to run them here.
779          */
780         peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
781 
782         if (!sctp_process_init(new_asoc, chunk,
783                                &chunk->subh.cookie_hdr->c.peer_addr,
784                                peer_init, GFP_ATOMIC))
785                 goto nomem_init;
786 
787         /* SCTP-AUTH:  Now that we've populate required fields in
788          * sctp_process_init, set up the assocaition shared keys as
789          * necessary so that we can potentially authenticate the ACK
790          */
791         error = sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC);
792         if (error)
793                 goto nomem_init;
794 
795         if (!sctp_auth_chunk_verify(net, chunk, new_asoc)) {
796                 sctp_association_free(new_asoc);
797                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
798         }
799 
800         repl = sctp_make_cookie_ack(new_asoc, chunk);
801         if (!repl)
802                 goto nomem_init;
803 
804         /* RFC 2960 5.1 Normal Establishment of an Association
805          *
806          * D) IMPLEMENTATION NOTE: An implementation may choose to
807          * send the Communication Up notification to the SCTP user
808          * upon reception of a valid COOKIE ECHO chunk.
809          */
810         ev = sctp_ulpevent_make_assoc_change(new_asoc, 0, SCTP_COMM_UP, 0,
811                                              new_asoc->c.sinit_num_ostreams,
812                                              new_asoc->c.sinit_max_instreams,
813                                              NULL, GFP_ATOMIC);
814         if (!ev)
815                 goto nomem_ev;
816 
817         /* Sockets API Draft Section 5.3.1.6
818          * When a peer sends a Adaptation Layer Indication parameter , SCTP
819          * delivers this notification to inform the application that of the
820          * peers requested adaptation layer.
821          */
822         if (new_asoc->peer.adaptation_ind) {
823                 ai_ev = sctp_ulpevent_make_adaptation_indication(new_asoc,
824                                                             GFP_ATOMIC);
825                 if (!ai_ev)
826                         goto nomem_aiev;
827         }
828 
829         if (!new_asoc->peer.auth_capable) {
830                 auth_ev = sctp_ulpevent_make_authkey(new_asoc, 0,
831                                                      SCTP_AUTH_NO_AUTH,
832                                                      GFP_ATOMIC);
833                 if (!auth_ev)
834                         goto nomem_authev;
835         }
836 
837         /* Add all the state machine commands now since we've created
838          * everything.  This way we don't introduce memory corruptions
839          * during side-effect processing and correclty count established
840          * associations.
841          */
842         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc));
843         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
844                         SCTP_STATE(SCTP_STATE_ESTABLISHED));
845         SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
846         SCTP_INC_STATS(net, SCTP_MIB_PASSIVEESTABS);
847         sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL());
848 
849         if (new_asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
850                 sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
851                                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
852 
853         /* This will send the COOKIE ACK */
854         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
855 
856         /* Queue the ASSOC_CHANGE event */
857         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
858 
859         /* Send up the Adaptation Layer Indication event */
860         if (ai_ev)
861                 sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
862                                 SCTP_ULPEVENT(ai_ev));
863 
864         if (auth_ev)
865                 sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
866                                 SCTP_ULPEVENT(auth_ev));
867 
868         return SCTP_DISPOSITION_CONSUME;
869 
870 nomem_authev:
871         sctp_ulpevent_free(ai_ev);
872 nomem_aiev:
873         sctp_ulpevent_free(ev);
874 nomem_ev:
875         sctp_chunk_free(repl);
876 nomem_init:
877         sctp_association_free(new_asoc);
878 nomem:
879         return SCTP_DISPOSITION_NOMEM;
880 }
881 
882 /*
883  * Respond to a normal COOKIE ACK chunk.
884  * We are the side that is asking for an association.
885  *
886  * RFC 2960 5.1 Normal Establishment of an Association
887  *
888  * E) Upon reception of the COOKIE ACK, endpoint "A" will move from the
889  *    COOKIE-ECHOED state to the ESTABLISHED state, stopping the T1-cookie
890  *    timer. It may also notify its ULP about the successful
891  *    establishment of the association with a Communication Up
892  *    notification (see Section 10).
893  *
894  * Verification Tag:
895  * Inputs
896  * (endpoint, asoc, chunk)
897  *
898  * Outputs
899  * (asoc, reply_msg, msg_up, timers, counters)
900  *
901  * The return value is the disposition of the chunk.
902  */
903 enum sctp_disposition sctp_sf_do_5_1E_ca(struct net *net,
904                                          const struct sctp_endpoint *ep,
905                                          const struct sctp_association *asoc,
906                                          const union sctp_subtype type,
907                                          void *arg,
908                                          struct sctp_cmd_seq *commands)
909 {
910         struct sctp_chunk *chunk = arg;
911         struct sctp_ulpevent *ev;
912 
913         if (!sctp_vtag_verify(chunk, asoc))
914                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
915 
916         /* Verify that the chunk length for the COOKIE-ACK is OK.
917          * If we don't do this, any bundled chunks may be junked.
918          */
919         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
920                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
921                                                   commands);
922 
923         /* Reset init error count upon receipt of COOKIE-ACK,
924          * to avoid problems with the managemement of this
925          * counter in stale cookie situations when a transition back
926          * from the COOKIE-ECHOED state to the COOKIE-WAIT
927          * state is performed.
928          */
929         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_RESET, SCTP_NULL());
930 
931         /* Set peer label for connection. */
932         security_inet_conn_established(ep->base.sk, chunk->skb);
933 
934         /* RFC 2960 5.1 Normal Establishment of an Association
935          *
936          * E) Upon reception of the COOKIE ACK, endpoint "A" will move
937          * from the COOKIE-ECHOED state to the ESTABLISHED state,
938          * stopping the T1-cookie timer.
939          */
940         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
941                         SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
942         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
943                         SCTP_STATE(SCTP_STATE_ESTABLISHED));
944         SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
945         SCTP_INC_STATS(net, SCTP_MIB_ACTIVEESTABS);
946         sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL());
947         if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
948                 sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
949                                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
950 
951         /* It may also notify its ULP about the successful
952          * establishment of the association with a Communication Up
953          * notification (see Section 10).
954          */
955         ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_UP,
956                                              0, asoc->c.sinit_num_ostreams,
957                                              asoc->c.sinit_max_instreams,
958                                              NULL, GFP_ATOMIC);
959 
960         if (!ev)
961                 goto nomem;
962 
963         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
964 
965         /* Sockets API Draft Section 5.3.1.6
966          * When a peer sends a Adaptation Layer Indication parameter , SCTP
967          * delivers this notification to inform the application that of the
968          * peers requested adaptation layer.
969          */
970         if (asoc->peer.adaptation_ind) {
971                 ev = sctp_ulpevent_make_adaptation_indication(asoc, GFP_ATOMIC);
972                 if (!ev)
973                         goto nomem;
974 
975                 sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
976                                 SCTP_ULPEVENT(ev));
977         }
978 
979         if (!asoc->peer.auth_capable) {
980                 ev = sctp_ulpevent_make_authkey(asoc, 0, SCTP_AUTH_NO_AUTH,
981                                                 GFP_ATOMIC);
982                 if (!ev)
983                         goto nomem;
984                 sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
985                                 SCTP_ULPEVENT(ev));
986         }
987 
988         return SCTP_DISPOSITION_CONSUME;
989 nomem:
990         return SCTP_DISPOSITION_NOMEM;
991 }
992 
993 /* Generate and sendout a heartbeat packet.  */
994 static enum sctp_disposition sctp_sf_heartbeat(
995                                         const struct sctp_endpoint *ep,
996                                         const struct sctp_association *asoc,
997                                         const union sctp_subtype type,
998                                         void *arg,
999                                         struct sctp_cmd_seq *commands)
1000 {
1001         struct sctp_transport *transport = (struct sctp_transport *) arg;
1002         struct sctp_chunk *reply;
1003 
1004         /* Send a heartbeat to our peer.  */
1005         reply = sctp_make_heartbeat(asoc, transport);
1006         if (!reply)
1007                 return SCTP_DISPOSITION_NOMEM;
1008 
1009         /* Set rto_pending indicating that an RTT measurement
1010          * is started with this heartbeat chunk.
1011          */
1012         sctp_add_cmd_sf(commands, SCTP_CMD_RTO_PENDING,
1013                         SCTP_TRANSPORT(transport));
1014 
1015         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
1016         return SCTP_DISPOSITION_CONSUME;
1017 }
1018 
1019 /* Generate a HEARTBEAT packet on the given transport.  */
1020 enum sctp_disposition sctp_sf_sendbeat_8_3(struct net *net,
1021                                            const struct sctp_endpoint *ep,
1022                                            const struct sctp_association *asoc,
1023                                            const union sctp_subtype type,
1024                                            void *arg,
1025                                            struct sctp_cmd_seq *commands)
1026 {
1027         struct sctp_transport *transport = (struct sctp_transport *) arg;
1028 
1029         if (asoc->overall_error_count >= asoc->max_retrans) {
1030                 sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
1031                                 SCTP_ERROR(ETIMEDOUT));
1032                 /* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */
1033                 sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
1034                                 SCTP_PERR(SCTP_ERROR_NO_ERROR));
1035                 SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
1036                 SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
1037                 return SCTP_DISPOSITION_DELETE_TCB;
1038         }
1039 
1040         /* Section 3.3.5.
1041          * The Sender-specific Heartbeat Info field should normally include
1042          * information about the sender's current time when this HEARTBEAT
1043          * chunk is sent and the destination transport address to which this
1044          * HEARTBEAT is sent (see Section 8.3).
1045          */
1046 
1047         if (transport->param_flags & SPP_HB_ENABLE) {
1048                 if (SCTP_DISPOSITION_NOMEM ==
1049                                 sctp_sf_heartbeat(ep, asoc, type, arg,
1050                                                   commands))
1051                         return SCTP_DISPOSITION_NOMEM;
1052 
1053                 /* Set transport error counter and association error counter
1054                  * when sending heartbeat.
1055                  */
1056                 sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_HB_SENT,
1057                                 SCTP_TRANSPORT(transport));
1058         }
1059         sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_IDLE,
1060                         SCTP_TRANSPORT(transport));
1061         sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMER_UPDATE,
1062                         SCTP_TRANSPORT(transport));
1063 
1064         return SCTP_DISPOSITION_CONSUME;
1065 }
1066 
1067 /* resend asoc strreset_chunk.  */
1068 enum sctp_disposition sctp_sf_send_reconf(struct net *net,
1069                                           const struct sctp_endpoint *ep,
1070                                           const struct sctp_association *asoc,
1071                                           const union sctp_subtype type,
1072                                           void *arg,
1073                                           struct sctp_cmd_seq *commands)
1074 {
1075         struct sctp_transport *transport = arg;
1076 
1077         if (asoc->overall_error_count >= asoc->max_retrans) {
1078                 sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
1079                                 SCTP_ERROR(ETIMEDOUT));
1080                 /* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */
1081                 sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
1082                                 SCTP_PERR(SCTP_ERROR_NO_ERROR));
1083                 SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
1084                 SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
1085                 return SCTP_DISPOSITION_DELETE_TCB;
1086         }
1087 
1088         sctp_chunk_hold(asoc->strreset_chunk);
1089         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
1090                         SCTP_CHUNK(asoc->strreset_chunk));
1091         sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE, SCTP_TRANSPORT(transport));
1092 
1093         return SCTP_DISPOSITION_CONSUME;
1094 }
1095 
1096 /*
1097  * Process an heartbeat request.
1098  *
1099  * Section: 8.3 Path Heartbeat
1100  * The receiver of the HEARTBEAT should immediately respond with a
1101  * HEARTBEAT ACK that contains the Heartbeat Information field copied
1102  * from the received HEARTBEAT chunk.
1103  *
1104  * Verification Tag:  8.5 Verification Tag [Normal verification]
1105  * When receiving an SCTP packet, the endpoint MUST ensure that the
1106  * value in the Verification Tag field of the received SCTP packet
1107  * matches its own Tag. If the received Verification Tag value does not
1108  * match the receiver's own tag value, the receiver shall silently
1109  * discard the packet and shall not process it any further except for
1110  * those cases listed in Section 8.5.1 below.
1111  *
1112  * Inputs
1113  * (endpoint, asoc, chunk)
1114  *
1115  * Outputs
1116  * (asoc, reply_msg, msg_up, timers, counters)
1117  *
1118  * The return value is the disposition of the chunk.
1119  */
1120 enum sctp_disposition sctp_sf_beat_8_3(struct net *net,
1121                                        const struct sctp_endpoint *ep,
1122                                        const struct sctp_association *asoc,
1123                                        const union sctp_subtype type,
1124                                        void *arg, struct sctp_cmd_seq *commands)
1125 {
1126         struct sctp_paramhdr *param_hdr;
1127         struct sctp_chunk *chunk = arg;
1128         struct sctp_chunk *reply;
1129         size_t paylen = 0;
1130 
1131         if (!sctp_vtag_verify(chunk, asoc))
1132                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
1133 
1134         /* Make sure that the HEARTBEAT chunk has a valid length. */
1135         if (!sctp_chunk_length_valid(chunk,
1136                                      sizeof(struct sctp_heartbeat_chunk)))
1137                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
1138                                                   commands);
1139 
1140         /* 8.3 The receiver of the HEARTBEAT should immediately
1141          * respond with a HEARTBEAT ACK that contains the Heartbeat
1142          * Information field copied from the received HEARTBEAT chunk.
1143          */
1144         chunk->subh.hb_hdr = (struct sctp_heartbeathdr *)chunk->skb->data;
1145         param_hdr = (struct sctp_paramhdr *)chunk->subh.hb_hdr;
1146         paylen = ntohs(chunk->chunk_hdr->length) - sizeof(struct sctp_chunkhdr);
1147 
1148         if (ntohs(param_hdr->length) > paylen)
1149                 return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
1150                                                   param_hdr, commands);
1151 
1152         if (!pskb_pull(chunk->skb, paylen))
1153                 goto nomem;
1154 
1155         reply = sctp_make_heartbeat_ack(asoc, chunk, param_hdr, paylen);
1156         if (!reply)
1157                 goto nomem;
1158 
1159         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
1160         return SCTP_DISPOSITION_CONSUME;
1161 
1162 nomem:
1163         return SCTP_DISPOSITION_NOMEM;
1164 }
1165 
1166 /*
1167  * Process the returning HEARTBEAT ACK.
1168  *
1169  * Section: 8.3 Path Heartbeat
1170  * Upon the receipt of the HEARTBEAT ACK, the sender of the HEARTBEAT
1171  * should clear the error counter of the destination transport
1172  * address to which the HEARTBEAT was sent, and mark the destination
1173  * transport address as active if it is not so marked. The endpoint may
1174  * optionally report to the upper layer when an inactive destination
1175  * address is marked as active due to the reception of the latest
1176  * HEARTBEAT ACK. The receiver of the HEARTBEAT ACK must also
1177  * clear the association overall error count as well (as defined
1178  * in section 8.1).
1179  *
1180  * The receiver of the HEARTBEAT ACK should also perform an RTT
1181  * measurement for that destination transport address using the time
1182  * value carried in the HEARTBEAT ACK chunk.
1183  *
1184  * Verification Tag:  8.5 Verification Tag [Normal verification]
1185  *
1186  * Inputs
1187  * (endpoint, asoc, chunk)
1188  *
1189  * Outputs
1190  * (asoc, reply_msg, msg_up, timers, counters)
1191  *
1192  * The return value is the disposition of the chunk.
1193  */
1194 enum sctp_disposition sctp_sf_backbeat_8_3(struct net *net,
1195                                            const struct sctp_endpoint *ep,
1196                                            const struct sctp_association *asoc,
1197                                            const union sctp_subtype type,
1198                                            void *arg,
1199                                            struct sctp_cmd_seq *commands)
1200 {
1201         struct sctp_sender_hb_info *hbinfo;
1202         struct sctp_chunk *chunk = arg;
1203         struct sctp_transport *link;
1204         unsigned long max_interval;
1205         union sctp_addr from_addr;
1206 
1207         if (!sctp_vtag_verify(chunk, asoc))
1208                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
1209 
1210         /* Make sure that the HEARTBEAT-ACK chunk has a valid length.  */
1211         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr) +
1212                                             sizeof(*hbinfo)))
1213                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
1214                                                   commands);
1215 
1216         hbinfo = (struct sctp_sender_hb_info *)chunk->skb->data;
1217         /* Make sure that the length of the parameter is what we expect */
1218         if (ntohs(hbinfo->param_hdr.length) != sizeof(*hbinfo))
1219                 return SCTP_DISPOSITION_DISCARD;
1220 
1221         from_addr = hbinfo->daddr;
1222         link = sctp_assoc_lookup_paddr(asoc, &from_addr);
1223 
1224         /* This should never happen, but lets log it if so.  */
1225         if (unlikely(!link)) {
1226                 if (from_addr.sa.sa_family == AF_INET6) {
1227                         net_warn_ratelimited("%s association %p could not find address %pI6\n",
1228                                              __func__,
1229                                              asoc,
1230                                              &from_addr.v6.sin6_addr);
1231                 } else {
1232                         net_warn_ratelimited("%s association %p could not find address %pI4\n",
1233                                              __func__,
1234                                              asoc,
1235                                              &from_addr.v4.sin_addr.s_addr);
1236                 }
1237                 return SCTP_DISPOSITION_DISCARD;
1238         }
1239 
1240         /* Validate the 64-bit random nonce. */
1241         if (hbinfo->hb_nonce != link->hb_nonce)
1242                 return SCTP_DISPOSITION_DISCARD;
1243 
1244         max_interval = link->hbinterval + link->rto;
1245 
1246         /* Check if the timestamp looks valid.  */
1247         if (time_after(hbinfo->sent_at, jiffies) ||
1248             time_after(jiffies, hbinfo->sent_at + max_interval)) {
1249                 pr_debug("%s: HEARTBEAT ACK with invalid timestamp received "
1250                          "for transport:%p\n", __func__, link);
1251 
1252                 return SCTP_DISPOSITION_DISCARD;
1253         }
1254 
1255         /* 8.3 Upon the receipt of the HEARTBEAT ACK, the sender of
1256          * the HEARTBEAT should clear the error counter of the
1257          * destination transport address to which the HEARTBEAT was
1258          * sent and mark the destination transport address as active if
1259          * it is not so marked.
1260          */
1261         sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_ON, SCTP_TRANSPORT(link));
1262 
1263         return SCTP_DISPOSITION_CONSUME;
1264 }
1265 
1266 /* Helper function to send out an abort for the restart
1267  * condition.
1268  */
1269 static int sctp_sf_send_restart_abort(struct net *net, union sctp_addr *ssa,
1270                                       struct sctp_chunk *init,
1271                                       struct sctp_cmd_seq *commands)
1272 {
1273         struct sctp_af *af = sctp_get_af_specific(ssa->v4.sin_family);
1274         union sctp_addr_param *addrparm;
1275         struct sctp_errhdr *errhdr;
1276         char buffer[sizeof(*errhdr) + sizeof(*addrparm)];
1277         struct sctp_endpoint *ep;
1278         struct sctp_packet *pkt;
1279         int len;
1280 
1281         /* Build the error on the stack.   We are way to malloc crazy
1282          * throughout the code today.
1283          */
1284         errhdr = (struct sctp_errhdr *)buffer;
1285         addrparm = (union sctp_addr_param *)errhdr->variable;
1286 
1287         /* Copy into a parm format. */
1288         len = af->to_addr_param(ssa, addrparm);
1289         len += sizeof(*errhdr);
1290 
1291         errhdr->cause = SCTP_ERROR_RESTART;
1292         errhdr->length = htons(len);
1293 
1294         /* Assign to the control socket. */
1295         ep = sctp_sk(net->sctp.ctl_sock)->ep;
1296 
1297         /* Association is NULL since this may be a restart attack and we
1298          * want to send back the attacker's vtag.
1299          */
1300         pkt = sctp_abort_pkt_new(net, ep, NULL, init, errhdr, len);
1301 
1302         if (!pkt)
1303                 goto out;
1304         sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT, SCTP_PACKET(pkt));
1305 
1306         SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
1307 
1308         /* Discard the rest of the inbound packet. */
1309         sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
1310 
1311 out:
1312         /* Even if there is no memory, treat as a failure so
1313          * the packet will get dropped.
1314          */
1315         return 0;
1316 }
1317 
1318 static bool list_has_sctp_addr(const struct list_head *list,
1319                                union sctp_addr *ipaddr)
1320 {
1321         struct sctp_transport *addr;
1322 
1323         list_for_each_entry(addr, list, transports) {
1324                 if (sctp_cmp_addr_exact(ipaddr, &addr->ipaddr))
1325                         return true;
1326         }
1327 
1328         return false;
1329 }
1330 /* A restart is occurring, check to make sure no new addresses
1331  * are being added as we may be under a takeover attack.
1332  */
1333 static int sctp_sf_check_restart_addrs(const struct sctp_association *new_asoc,
1334                                        const struct sctp_association *asoc,
1335                                        struct sctp_chunk *init,
1336                                        struct sctp_cmd_seq *commands)
1337 {
1338         struct net *net = sock_net(new_asoc->base.sk);
1339         struct sctp_transport *new_addr;
1340         int ret = 1;
1341 
1342         /* Implementor's Guide - Section 5.2.2
1343          * ...
1344          * Before responding the endpoint MUST check to see if the
1345          * unexpected INIT adds new addresses to the association. If new
1346          * addresses are added to the association, the endpoint MUST respond
1347          * with an ABORT..
1348          */
1349 
1350         /* Search through all current addresses and make sure
1351          * we aren't adding any new ones.
1352          */
1353         list_for_each_entry(new_addr, &new_asoc->peer.transport_addr_list,
1354                             transports) {
1355                 if (!list_has_sctp_addr(&asoc->peer.transport_addr_list,
1356                                         &new_addr->ipaddr)) {
1357                         sctp_sf_send_restart_abort(net, &new_addr->ipaddr, init,
1358                                                    commands);
1359                         ret = 0;
1360                         break;
1361                 }
1362         }
1363 
1364         /* Return success if all addresses were found. */
1365         return ret;
1366 }
1367 
1368 /* Populate the verification/tie tags based on overlapping INIT
1369  * scenario.
1370  *
1371  * Note: Do not use in CLOSED or SHUTDOWN-ACK-SENT state.
1372  */
1373 static void sctp_tietags_populate(struct sctp_association *new_asoc,
1374                                   const struct sctp_association *asoc)
1375 {
1376         switch (asoc->state) {
1377 
1378         /* 5.2.1 INIT received in COOKIE-WAIT or COOKIE-ECHOED State */
1379 
1380         case SCTP_STATE_COOKIE_WAIT:
1381                 new_asoc->c.my_vtag     = asoc->c.my_vtag;
1382                 new_asoc->c.my_ttag     = asoc->c.my_vtag;
1383                 new_asoc->c.peer_ttag   = 0;
1384                 break;
1385 
1386         case SCTP_STATE_COOKIE_ECHOED:
1387                 new_asoc->c.my_vtag     = asoc->c.my_vtag;
1388                 new_asoc->c.my_ttag     = asoc->c.my_vtag;
1389                 new_asoc->c.peer_ttag   = asoc->c.peer_vtag;
1390                 break;
1391 
1392         /* 5.2.2 Unexpected INIT in States Other than CLOSED, COOKIE-ECHOED,
1393          * COOKIE-WAIT and SHUTDOWN-ACK-SENT
1394          */
1395         default:
1396                 new_asoc->c.my_ttag   = asoc->c.my_vtag;
1397                 new_asoc->c.peer_ttag = asoc->c.peer_vtag;
1398                 break;
1399         }
1400 
1401         /* Other parameters for the endpoint SHOULD be copied from the
1402          * existing parameters of the association (e.g. number of
1403          * outbound streams) into the INIT ACK and cookie.
1404          */
1405         new_asoc->rwnd                  = asoc->rwnd;
1406         new_asoc->c.sinit_num_ostreams  = asoc->c.sinit_num_ostreams;
1407         new_asoc->c.sinit_max_instreams = asoc->c.sinit_max_instreams;
1408         new_asoc->c.initial_tsn         = asoc->c.initial_tsn;
1409 }
1410 
1411 /*
1412  * Compare vtag/tietag values to determine unexpected COOKIE-ECHO
1413  * handling action.
1414  *
1415  * RFC 2960 5.2.4 Handle a COOKIE ECHO when a TCB exists.
1416  *
1417  * Returns value representing action to be taken.   These action values
1418  * correspond to Action/Description values in RFC 2960, Table 2.
1419  */
1420 static char sctp_tietags_compare(struct sctp_association *new_asoc,
1421                                  const struct sctp_association *asoc)
1422 {
1423         /* In this case, the peer may have restarted.  */
1424         if ((asoc->c.my_vtag != new_asoc->c.my_vtag) &&
1425             (asoc->c.peer_vtag != new_asoc->c.peer_vtag) &&
1426             (asoc->c.my_vtag == new_asoc->c.my_ttag) &&
1427             (asoc->c.peer_vtag == new_asoc->c.peer_ttag))
1428                 return 'A';
1429 
1430         /* Collision case B. */
1431         if ((asoc->c.my_vtag == new_asoc->c.my_vtag) &&
1432             ((asoc->c.peer_vtag != new_asoc->c.peer_vtag) ||
1433              (0 == asoc->c.peer_vtag))) {
1434                 return 'B';
1435         }
1436 
1437         /* Collision case D. */
1438         if ((asoc->c.my_vtag == new_asoc->c.my_vtag) &&
1439             (asoc->c.peer_vtag == new_asoc->c.peer_vtag))
1440                 return 'D';
1441 
1442         /* Collision case C. */
1443         if ((asoc->c.my_vtag != new_asoc->c.my_vtag) &&
1444             (asoc->c.peer_vtag == new_asoc->c.peer_vtag) &&
1445             (0 == new_asoc->c.my_ttag) &&
1446             (0 == new_asoc->c.peer_ttag))
1447                 return 'C';
1448 
1449         /* No match to any of the special cases; discard this packet. */
1450         return 'E';
1451 }
1452 
1453 /* Common helper routine for both duplicate and simulataneous INIT
1454  * chunk handling.
1455  */
1456 static enum sctp_disposition sctp_sf_do_unexpected_init(
1457                                         struct net *net,
1458                                         const struct sctp_endpoint *ep,
1459                                         const struct sctp_association *asoc,
1460                                         const union sctp_subtype type,
1461                                         void *arg,
1462                                         struct sctp_cmd_seq *commands)
1463 {
1464         struct sctp_chunk *chunk = arg, *repl, *err_chunk;
1465         struct sctp_unrecognized_param *unk_param;
1466         struct sctp_association *new_asoc;
1467         enum sctp_disposition retval;
1468         struct sctp_packet *packet;
1469         int len;
1470 
1471         /* Update socket peer label if first association. */
1472         if (security_sctp_assoc_request((struct sctp_endpoint *)ep,
1473                                         chunk->skb))
1474                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
1475 
1476         /* 6.10 Bundling
1477          * An endpoint MUST NOT bundle INIT, INIT ACK or
1478          * SHUTDOWN COMPLETE with any other chunks.
1479          *
1480          * IG Section 2.11.2
1481          * Furthermore, we require that the receiver of an INIT chunk MUST
1482          * enforce these rules by silently discarding an arriving packet
1483          * with an INIT chunk that is bundled with other chunks.
1484          */
1485         if (!chunk->singleton)
1486                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
1487 
1488         /* 3.1 A packet containing an INIT chunk MUST have a zero Verification
1489          * Tag.
1490          */
1491         if (chunk->sctp_hdr->vtag != 0)
1492                 return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
1493 
1494         /* Make sure that the INIT chunk has a valid length.
1495          * In this case, we generate a protocol violation since we have
1496          * an association established.
1497          */
1498         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_init_chunk)))
1499                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
1500                                                   commands);
1501         /* Grab the INIT header.  */
1502         chunk->subh.init_hdr = (struct sctp_inithdr *)chunk->skb->data;
1503 
1504         /* Tag the variable length parameters.  */
1505         chunk->param_hdr.v = skb_pull(chunk->skb, sizeof(struct sctp_inithdr));
1506 
1507         /* Verify the INIT chunk before processing it. */
1508         err_chunk = NULL;
1509         if (!sctp_verify_init(net, ep, asoc, chunk->chunk_hdr->type,
1510                               (struct sctp_init_chunk *)chunk->chunk_hdr, chunk,
1511                               &err_chunk)) {
1512                 /* This chunk contains fatal error. It is to be discarded.
1513                  * Send an ABORT, with causes if there is any.
1514                  */
1515                 if (err_chunk) {
1516                         packet = sctp_abort_pkt_new(net, ep, asoc, arg,
1517                                         (__u8 *)(err_chunk->chunk_hdr) +
1518                                         sizeof(struct sctp_chunkhdr),
1519                                         ntohs(err_chunk->chunk_hdr->length) -
1520                                         sizeof(struct sctp_chunkhdr));
1521 
1522                         if (packet) {
1523                                 sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
1524                                                 SCTP_PACKET(packet));
1525                                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
1526                                 retval = SCTP_DISPOSITION_CONSUME;
1527                         } else {
1528                                 retval = SCTP_DISPOSITION_NOMEM;
1529                         }
1530                         goto cleanup;
1531                 } else {
1532                         return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg,
1533                                                     commands);
1534                 }
1535         }
1536 
1537         /*
1538          * Other parameters for the endpoint SHOULD be copied from the
1539          * existing parameters of the association (e.g. number of
1540          * outbound streams) into the INIT ACK and cookie.
1541          * FIXME:  We are copying parameters from the endpoint not the
1542          * association.
1543          */
1544         new_asoc = sctp_make_temp_asoc(ep, chunk, GFP_ATOMIC);
1545         if (!new_asoc)
1546                 goto nomem;
1547 
1548         if (sctp_assoc_set_bind_addr_from_ep(new_asoc,
1549                                 sctp_scope(sctp_source(chunk)), GFP_ATOMIC) < 0)
1550                 goto nomem;
1551 
1552         /* In the outbound INIT ACK the endpoint MUST copy its current
1553          * Verification Tag and Peers Verification tag into a reserved
1554          * place (local tie-tag and per tie-tag) within the state cookie.
1555          */
1556         if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk),
1557                                (struct sctp_init_chunk *)chunk->chunk_hdr,
1558                                GFP_ATOMIC))
1559                 goto nomem;
1560 
1561         /* Make sure no new addresses are being added during the
1562          * restart.   Do not do this check for COOKIE-WAIT state,
1563          * since there are no peer addresses to check against.
1564          * Upon return an ABORT will have been sent if needed.
1565          */
1566         if (!sctp_state(asoc, COOKIE_WAIT)) {
1567                 if (!sctp_sf_check_restart_addrs(new_asoc, asoc, chunk,
1568                                                  commands)) {
1569                         retval = SCTP_DISPOSITION_CONSUME;
1570                         goto nomem_retval;
1571                 }
1572         }
1573 
1574         sctp_tietags_populate(new_asoc, asoc);
1575 
1576         /* B) "Z" shall respond immediately with an INIT ACK chunk.  */
1577 
1578         /* If there are errors need to be reported for unknown parameters,
1579          * make sure to reserve enough room in the INIT ACK for them.
1580          */
1581         len = 0;
1582         if (err_chunk) {
1583                 len = ntohs(err_chunk->chunk_hdr->length) -
1584                       sizeof(struct sctp_chunkhdr);
1585         }
1586 
1587         repl = sctp_make_init_ack(new_asoc, chunk, GFP_ATOMIC, len);
1588         if (!repl)
1589                 goto nomem;
1590 
1591         /* If there are errors need to be reported for unknown parameters,
1592          * include them in the outgoing INIT ACK as "Unrecognized parameter"
1593          * parameter.
1594          */
1595         if (err_chunk) {
1596                 /* Get the "Unrecognized parameter" parameter(s) out of the
1597                  * ERROR chunk generated by sctp_verify_init(). Since the
1598                  * error cause code for "unknown parameter" and the
1599                  * "Unrecognized parameter" type is the same, we can
1600                  * construct the parameters in INIT ACK by copying the
1601                  * ERROR causes over.
1602                  */
1603                 unk_param = (struct sctp_unrecognized_param *)
1604                             ((__u8 *)(err_chunk->chunk_hdr) +
1605                             sizeof(struct sctp_chunkhdr));
1606                 /* Replace the cause code with the "Unrecognized parameter"
1607                  * parameter type.
1608                  */
1609                 sctp_addto_chunk(repl, len, unk_param);
1610         }
1611 
1612         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(new_asoc));
1613         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
1614 
1615         /*
1616          * Note: After sending out INIT ACK with the State Cookie parameter,
1617          * "Z" MUST NOT allocate any resources for this new association.
1618          * Otherwise, "Z" will be vulnerable to resource attacks.
1619          */
1620         sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
1621         retval = SCTP_DISPOSITION_CONSUME;
1622 
1623         return retval;
1624 
1625 nomem:
1626         retval = SCTP_DISPOSITION_NOMEM;
1627 nomem_retval:
1628         if (new_asoc)
1629                 sctp_association_free(new_asoc);
1630 cleanup:
1631         if (err_chunk)
1632                 sctp_chunk_free(err_chunk);
1633         return retval;
1634 }
1635 
1636 /*
1637  * Handle simultaneous INIT.
1638  * This means we started an INIT and then we got an INIT request from
1639  * our peer.
1640  *
1641  * Section: 5.2.1 INIT received in COOKIE-WAIT or COOKIE-ECHOED State (Item B)
1642  * This usually indicates an initialization collision, i.e., each
1643  * endpoint is attempting, at about the same time, to establish an
1644  * association with the other endpoint.
1645  *
1646  * Upon receipt of an INIT in the COOKIE-WAIT or COOKIE-ECHOED state, an
1647  * endpoint MUST respond with an INIT ACK using the same parameters it
1648  * sent in its original INIT chunk (including its Verification Tag,
1649  * unchanged). These original parameters are combined with those from the
1650  * newly received INIT chunk. The endpoint shall also generate a State
1651  * Cookie with the INIT ACK. The endpoint uses the parameters sent in its
1652  * INIT to calculate the State Cookie.
1653  *
1654  * After that, the endpoint MUST NOT change its state, the T1-init
1655  * timer shall be left running and the corresponding TCB MUST NOT be
1656  * destroyed. The normal procedures for handling State Cookies when
1657  * a TCB exists will resolve the duplicate INITs to a single association.
1658  *
1659  * For an endpoint that is in the COOKIE-ECHOED state it MUST populate
1660  * its Tie-Tags with the Tag information of itself and its peer (see
1661  * section 5.2.2 for a description of the Tie-Tags).
1662  *
1663  * Verification Tag: Not explicit, but an INIT can not have a valid
1664  * verification tag, so we skip the check.
1665  *
1666  * Inputs
1667  * (endpoint, asoc, chunk)
1668  *
1669  * Outputs
1670  * (asoc, reply_msg, msg_up, timers, counters)
1671  *
1672  * The return value is the disposition of the chunk.
1673  */
1674 enum sctp_disposition sctp_sf_do_5_2_1_siminit(
1675                                         struct net *net,
1676                                         const struct sctp_endpoint *ep,
1677                                         const struct sctp_association *asoc,
1678                                         const union sctp_subtype type,
1679                                         void *arg,
1680                                         struct sctp_cmd_seq *commands)
1681 {
1682         /* Call helper to do the real work for both simulataneous and
1683          * duplicate INIT chunk handling.
1684          */
1685         return sctp_sf_do_unexpected_init(net, ep, asoc, type, arg, commands);
1686 }
1687 
1688 /*
1689  * Handle duplicated INIT messages.  These are usually delayed
1690  * restransmissions.
1691  *
1692  * Section: 5.2.2 Unexpected INIT in States Other than CLOSED,
1693  * COOKIE-ECHOED and COOKIE-WAIT
1694  *
1695  * Unless otherwise stated, upon reception of an unexpected INIT for
1696  * this association, the endpoint shall generate an INIT ACK with a
1697  * State Cookie.  In the outbound INIT ACK the endpoint MUST copy its
1698  * current Verification Tag and peer's Verification Tag into a reserved
1699  * place within the state cookie.  We shall refer to these locations as
1700  * the Peer's-Tie-Tag and the Local-Tie-Tag.  The outbound SCTP packet
1701  * containing this INIT ACK MUST carry a Verification Tag value equal to
1702  * the Initiation Tag found in the unexpected INIT.  And the INIT ACK
1703  * MUST contain a new Initiation Tag (randomly generated see Section
1704  * 5.3.1).  Other parameters for the endpoint SHOULD be copied from the
1705  * existing parameters of the association (e.g. number of outbound
1706  * streams) into the INIT ACK and cookie.
1707  *
1708  * After sending out the INIT ACK, the endpoint shall take no further
1709  * actions, i.e., the existing association, including its current state,
1710  * and the corresponding TCB MUST NOT be changed.
1711  *
1712  * Note: Only when a TCB exists and the association is not in a COOKIE-
1713  * WAIT state are the Tie-Tags populated.  For a normal association INIT
1714  * (i.e. the endpoint is in a COOKIE-WAIT state), the Tie-Tags MUST be
1715  * set to 0 (indicating that no previous TCB existed).  The INIT ACK and
1716  * State Cookie are populated as specified in section 5.2.1.
1717  *
1718  * Verification Tag: Not specified, but an INIT has no way of knowing
1719  * what the verification tag could be, so we ignore it.
1720  *
1721  * Inputs
1722  * (endpoint, asoc, chunk)
1723  *
1724  * Outputs
1725  * (asoc, reply_msg, msg_up, timers, counters)
1726  *
1727  * The return value is the disposition of the chunk.
1728  */
1729 enum sctp_disposition sctp_sf_do_5_2_2_dupinit(
1730                                         struct net *net,
1731                                         const struct sctp_endpoint *ep,
1732                                         const struct sctp_association *asoc,
1733                                         const union sctp_subtype type,
1734                                         void *arg,
1735                                         struct sctp_cmd_seq *commands)
1736 {
1737         /* Call helper to do the real work for both simulataneous and
1738          * duplicate INIT chunk handling.
1739          */
1740         return sctp_sf_do_unexpected_init(net, ep, asoc, type, arg, commands);
1741 }
1742 
1743 
1744 /*
1745  * Unexpected INIT-ACK handler.
1746  *
1747  * Section 5.2.3
1748  * If an INIT ACK received by an endpoint in any state other than the
1749  * COOKIE-WAIT state, the endpoint should discard the INIT ACK chunk.
1750  * An unexpected INIT ACK usually indicates the processing of an old or
1751  * duplicated INIT chunk.
1752 */
1753 enum sctp_disposition sctp_sf_do_5_2_3_initack(
1754                                         struct net *net,
1755                                         const struct sctp_endpoint *ep,
1756                                         const struct sctp_association *asoc,
1757                                         const union sctp_subtype type,
1758                                         void *arg,
1759                                         struct sctp_cmd_seq *commands)
1760 {
1761         /* Per the above section, we'll discard the chunk if we have an
1762          * endpoint.  If this is an OOTB INIT-ACK, treat it as such.
1763          */
1764         if (ep == sctp_sk(net->sctp.ctl_sock)->ep)
1765                 return sctp_sf_ootb(net, ep, asoc, type, arg, commands);
1766         else
1767                 return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands);
1768 }
1769 
1770 /* Unexpected COOKIE-ECHO handler for peer restart (Table 2, action 'A')
1771  *
1772  * Section 5.2.4
1773  *  A)  In this case, the peer may have restarted.
1774  */
1775 static enum sctp_disposition sctp_sf_do_dupcook_a(
1776                                         struct net *net,
1777                                         const struct sctp_endpoint *ep,
1778                                         const struct sctp_association *asoc,
1779                                         struct sctp_chunk *chunk,
1780                                         struct sctp_cmd_seq *commands,
1781                                         struct sctp_association *new_asoc)
1782 {
1783         struct sctp_init_chunk *peer_init;
1784         enum sctp_disposition disposition;
1785         struct sctp_ulpevent *ev;
1786         struct sctp_chunk *repl;
1787         struct sctp_chunk *err;
1788 
1789         /* new_asoc is a brand-new association, so these are not yet
1790          * side effects--it is safe to run them here.
1791          */
1792         peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
1793 
1794         if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), peer_init,
1795                                GFP_ATOMIC))
1796                 goto nomem;
1797 
1798         if (sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC))
1799                 goto nomem;
1800 
1801         if (!sctp_auth_chunk_verify(net, chunk, new_asoc))
1802                 return SCTP_DISPOSITION_DISCARD;
1803 
1804         /* Make sure no new addresses are being added during the
1805          * restart.  Though this is a pretty complicated attack
1806          * since you'd have to get inside the cookie.
1807          */
1808         if (!sctp_sf_check_restart_addrs(new_asoc, asoc, chunk, commands))
1809                 return SCTP_DISPOSITION_CONSUME;
1810 
1811         /* If the endpoint is in the SHUTDOWN-ACK-SENT state and recognizes
1812          * the peer has restarted (Action A), it MUST NOT setup a new
1813          * association but instead resend the SHUTDOWN ACK and send an ERROR
1814          * chunk with a "Cookie Received while Shutting Down" error cause to
1815          * its peer.
1816         */
1817         if (sctp_state(asoc, SHUTDOWN_ACK_SENT)) {
1818                 disposition = sctp_sf_do_9_2_reshutack(net, ep, asoc,
1819                                 SCTP_ST_CHUNK(chunk->chunk_hdr->type),
1820                                 chunk, commands);
1821                 if (SCTP_DISPOSITION_NOMEM == disposition)
1822                         goto nomem;
1823 
1824                 err = sctp_make_op_error(asoc, chunk,
1825                                          SCTP_ERROR_COOKIE_IN_SHUTDOWN,
1826                                          NULL, 0, 0);
1827                 if (err)
1828                         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
1829                                         SCTP_CHUNK(err));
1830 
1831                 return SCTP_DISPOSITION_CONSUME;
1832         }
1833 
1834         /* For now, stop pending T3-rtx and SACK timers, fail any unsent/unacked
1835          * data. Consider the optional choice of resending of this data.
1836          */
1837         sctp_add_cmd_sf(commands, SCTP_CMD_T3_RTX_TIMERS_STOP, SCTP_NULL());
1838         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
1839                         SCTP_TO(SCTP_EVENT_TIMEOUT_SACK));
1840         sctp_add_cmd_sf(commands, SCTP_CMD_PURGE_OUTQUEUE, SCTP_NULL());
1841 
1842         /* Stop pending T4-rto timer, teardown ASCONF queue, ASCONF-ACK queue
1843          * and ASCONF-ACK cache.
1844          */
1845         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
1846                         SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
1847         sctp_add_cmd_sf(commands, SCTP_CMD_PURGE_ASCONF_QUEUE, SCTP_NULL());
1848 
1849         repl = sctp_make_cookie_ack(new_asoc, chunk);
1850         if (!repl)
1851                 goto nomem;
1852 
1853         /* Report association restart to upper layer. */
1854         ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_RESTART, 0,
1855                                              new_asoc->c.sinit_num_ostreams,
1856                                              new_asoc->c.sinit_max_instreams,
1857                                              NULL, GFP_ATOMIC);
1858         if (!ev)
1859                 goto nomem_ev;
1860 
1861         /* Update the content of current association. */
1862         sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC, SCTP_ASOC(new_asoc));
1863         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
1864         if (sctp_state(asoc, SHUTDOWN_PENDING) &&
1865             (sctp_sstate(asoc->base.sk, CLOSING) ||
1866              sock_flag(asoc->base.sk, SOCK_DEAD))) {
1867                 /* if were currently in SHUTDOWN_PENDING, but the socket
1868                  * has been closed by user, don't transition to ESTABLISHED.
1869                  * Instead trigger SHUTDOWN bundled with COOKIE_ACK.
1870                  */
1871                 sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
1872                 return sctp_sf_do_9_2_start_shutdown(net, ep, asoc,
1873                                                      SCTP_ST_CHUNK(0), NULL,
1874                                                      commands);
1875         } else {
1876                 sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
1877                                 SCTP_STATE(SCTP_STATE_ESTABLISHED));
1878                 sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
1879         }
1880         return SCTP_DISPOSITION_CONSUME;
1881 
1882 nomem_ev:
1883         sctp_chunk_free(repl);
1884 nomem:
1885         return SCTP_DISPOSITION_NOMEM;
1886 }
1887 
1888 /* Unexpected COOKIE-ECHO handler for setup collision (Table 2, action 'B')
1889  *
1890  * Section 5.2.4
1891  *   B) In this case, both sides may be attempting to start an association
1892  *      at about the same time but the peer endpoint started its INIT
1893  *      after responding to the local endpoint's INIT
1894  */
1895 /* This case represents an initialization collision.  */
1896 static enum sctp_disposition sctp_sf_do_dupcook_b(
1897                                         struct net *net,
1898                                         const struct sctp_endpoint *ep,
1899                                         const struct sctp_association *asoc,
1900                                         struct sctp_chunk *chunk,
1901                                         struct sctp_cmd_seq *commands,
1902                                         struct sctp_association *new_asoc)
1903 {
1904         struct sctp_init_chunk *peer_init;
1905         struct sctp_chunk *repl;
1906 
1907         /* new_asoc is a brand-new association, so these are not yet
1908          * side effects--it is safe to run them here.
1909          */
1910         peer_init = &chunk->subh.cookie_hdr->c.peer_init[0];
1911         if (!sctp_process_init(new_asoc, chunk, sctp_source(chunk), peer_init,
1912                                GFP_ATOMIC))
1913                 goto nomem;
1914 
1915         if (sctp_auth_asoc_init_active_key(new_asoc, GFP_ATOMIC))
1916                 goto nomem;
1917 
1918         if (!sctp_auth_chunk_verify(net, chunk, new_asoc))
1919                 return SCTP_DISPOSITION_DISCARD;
1920 
1921         /* Update the content of current association.  */
1922         sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_ASSOC, SCTP_ASOC(new_asoc));
1923         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
1924                         SCTP_STATE(SCTP_STATE_ESTABLISHED));
1925         SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
1926         sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START, SCTP_NULL());
1927 
1928         repl = sctp_make_cookie_ack(new_asoc, chunk);
1929         if (!repl)
1930                 goto nomem;
1931 
1932         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
1933 
1934         /* RFC 2960 5.1 Normal Establishment of an Association
1935          *
1936          * D) IMPLEMENTATION NOTE: An implementation may choose to
1937          * send the Communication Up notification to the SCTP user
1938          * upon reception of a valid COOKIE ECHO chunk.
1939          *
1940          * Sadly, this needs to be implemented as a side-effect, because
1941          * we are not guaranteed to have set the association id of the real
1942          * association and so these notifications need to be delayed until
1943          * the association id is allocated.
1944          */
1945 
1946         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_CHANGE, SCTP_U8(SCTP_COMM_UP));
1947 
1948         /* Sockets API Draft Section 5.3.1.6
1949          * When a peer sends a Adaptation Layer Indication parameter , SCTP
1950          * delivers this notification to inform the application that of the
1951          * peers requested adaptation layer.
1952          *
1953          * This also needs to be done as a side effect for the same reason as
1954          * above.
1955          */
1956         if (asoc->peer.adaptation_ind)
1957                 sctp_add_cmd_sf(commands, SCTP_CMD_ADAPTATION_IND, SCTP_NULL());
1958 
1959         if (!asoc->peer.auth_capable)
1960                 sctp_add_cmd_sf(commands, SCTP_CMD_PEER_NO_AUTH, SCTP_NULL());
1961 
1962         return SCTP_DISPOSITION_CONSUME;
1963 
1964 nomem:
1965         return SCTP_DISPOSITION_NOMEM;
1966 }
1967 
1968 /* Unexpected COOKIE-ECHO handler for setup collision (Table 2, action 'C')
1969  *
1970  * Section 5.2.4
1971  *  C) In this case, the local endpoint's cookie has arrived late.
1972  *     Before it arrived, the local endpoint sent an INIT and received an
1973  *     INIT-ACK and finally sent a COOKIE ECHO with the peer's same tag
1974  *     but a new tag of its own.
1975  */
1976 /* This case represents an initialization collision.  */
1977 static enum sctp_disposition sctp_sf_do_dupcook_c(
1978                                         struct net *net,
1979                                         const struct sctp_endpoint *ep,
1980                                         const struct sctp_association *asoc,
1981                                         struct sctp_chunk *chunk,
1982                                         struct sctp_cmd_seq *commands,
1983                                         struct sctp_association *new_asoc)
1984 {
1985         /* The cookie should be silently discarded.
1986          * The endpoint SHOULD NOT change states and should leave
1987          * any timers running.
1988          */
1989         return SCTP_DISPOSITION_DISCARD;
1990 }
1991 
1992 /* Unexpected COOKIE-ECHO handler lost chunk (Table 2, action 'D')
1993  *
1994  * Section 5.2.4
1995  *
1996  * D) When both local and remote tags match the endpoint should always
1997  *    enter the ESTABLISHED state, if it has not already done so.
1998  */
1999 /* This case represents an initialization collision.  */
2000 static enum sctp_disposition sctp_sf_do_dupcook_d(
2001                                         struct net *net,
2002                                         const struct sctp_endpoint *ep,
2003                                         const struct sctp_association *asoc,
2004                                         struct sctp_chunk *chunk,
2005                                         struct sctp_cmd_seq *commands,
2006                                         struct sctp_association *new_asoc)
2007 {
2008         struct sctp_ulpevent *ev = NULL, *ai_ev = NULL, *auth_ev = NULL;
2009         struct sctp_chunk *repl;
2010 
2011         /* Clarification from Implementor's Guide:
2012          * D) When both local and remote tags match the endpoint should
2013          * enter the ESTABLISHED state, if it is in the COOKIE-ECHOED state.
2014          * It should stop any cookie timer that may be running and send
2015          * a COOKIE ACK.
2016          */
2017 
2018         if (!sctp_auth_chunk_verify(net, chunk, asoc))
2019                 return SCTP_DISPOSITION_DISCARD;
2020 
2021         /* Don't accidentally move back into established state. */
2022         if (asoc->state < SCTP_STATE_ESTABLISHED) {
2023                 sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
2024                                 SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
2025                 sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
2026                                 SCTP_STATE(SCTP_STATE_ESTABLISHED));
2027                 SCTP_INC_STATS(net, SCTP_MIB_CURRESTAB);
2028                 sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_START,
2029                                 SCTP_NULL());
2030 
2031                 /* RFC 2960 5.1 Normal Establishment of an Association
2032                  *
2033                  * D) IMPLEMENTATION NOTE: An implementation may choose
2034                  * to send the Communication Up notification to the
2035                  * SCTP user upon reception of a valid COOKIE
2036                  * ECHO chunk.
2037                  */
2038                 ev = sctp_ulpevent_make_assoc_change(asoc, 0,
2039                                              SCTP_COMM_UP, 0,
2040                                              asoc->c.sinit_num_ostreams,
2041                                              asoc->c.sinit_max_instreams,
2042                                              NULL, GFP_ATOMIC);
2043                 if (!ev)
2044                         goto nomem;
2045 
2046                 /* Sockets API Draft Section 5.3.1.6
2047                  * When a peer sends a Adaptation Layer Indication parameter,
2048                  * SCTP delivers this notification to inform the application
2049                  * that of the peers requested adaptation layer.
2050                  */
2051                 if (asoc->peer.adaptation_ind) {
2052                         ai_ev = sctp_ulpevent_make_adaptation_indication(asoc,
2053                                                                  GFP_ATOMIC);
2054                         if (!ai_ev)
2055                                 goto nomem;
2056 
2057                 }
2058 
2059                 if (!asoc->peer.auth_capable) {
2060                         auth_ev = sctp_ulpevent_make_authkey(asoc, 0,
2061                                                              SCTP_AUTH_NO_AUTH,
2062                                                              GFP_ATOMIC);
2063                         if (!auth_ev)
2064                                 goto nomem;
2065                 }
2066         }
2067 
2068         repl = sctp_make_cookie_ack(asoc, chunk);
2069         if (!repl)
2070                 goto nomem;
2071 
2072         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
2073 
2074         if (ev)
2075                 sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
2076                                 SCTP_ULPEVENT(ev));
2077         if (ai_ev)
2078                 sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
2079                                         SCTP_ULPEVENT(ai_ev));
2080         if (auth_ev)
2081                 sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
2082                                 SCTP_ULPEVENT(auth_ev));
2083 
2084         return SCTP_DISPOSITION_CONSUME;
2085 
2086 nomem:
2087         if (auth_ev)
2088                 sctp_ulpevent_free(auth_ev);
2089         if (ai_ev)
2090                 sctp_ulpevent_free(ai_ev);
2091         if (ev)
2092                 sctp_ulpevent_free(ev);
2093         return SCTP_DISPOSITION_NOMEM;
2094 }
2095 
2096 /*
2097  * Handle a duplicate COOKIE-ECHO.  This usually means a cookie-carrying
2098  * chunk was retransmitted and then delayed in the network.
2099  *
2100  * Section: 5.2.4 Handle a COOKIE ECHO when a TCB exists
2101  *
2102  * Verification Tag: None.  Do cookie validation.
2103  *
2104  * Inputs
2105  * (endpoint, asoc, chunk)
2106  *
2107  * Outputs
2108  * (asoc, reply_msg, msg_up, timers, counters)
2109  *
2110  * The return value is the disposition of the chunk.
2111  */
2112 enum sctp_disposition sctp_sf_do_5_2_4_dupcook(
2113                                         struct net *net,
2114                                         const struct sctp_endpoint *ep,
2115                                         const struct sctp_association *asoc,
2116                                         const union sctp_subtype type,
2117                                         void *arg,
2118                                         struct sctp_cmd_seq *commands)
2119 {
2120         struct sctp_association *new_asoc;
2121         struct sctp_chunk *chunk = arg;
2122         enum sctp_disposition retval;
2123         struct sctp_chunk *err_chk_p;
2124         int error = 0;
2125         char action;
2126 
2127         /* Make sure that the chunk has a valid length from the protocol
2128          * perspective.  In this case check to make sure we have at least
2129          * enough for the chunk header.  Cookie length verification is
2130          * done later.
2131          */
2132         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
2133                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2134                                                   commands);
2135 
2136         /* "Decode" the chunk.  We have no optional parameters so we
2137          * are in good shape.
2138          */
2139         chunk->subh.cookie_hdr = (struct sctp_signed_cookie *)chunk->skb->data;
2140         if (!pskb_pull(chunk->skb, ntohs(chunk->chunk_hdr->length) -
2141                                         sizeof(struct sctp_chunkhdr)))
2142                 goto nomem;
2143 
2144         /* In RFC 2960 5.2.4 3, if both Verification Tags in the State Cookie
2145          * of a duplicate COOKIE ECHO match the Verification Tags of the
2146          * current association, consider the State Cookie valid even if
2147          * the lifespan is exceeded.
2148          */
2149         new_asoc = sctp_unpack_cookie(ep, asoc, chunk, GFP_ATOMIC, &error,
2150                                       &err_chk_p);
2151 
2152         /* FIXME:
2153          * If the re-build failed, what is the proper error path
2154          * from here?
2155          *
2156          * [We should abort the association. --piggy]
2157          */
2158         if (!new_asoc) {
2159                 /* FIXME: Several errors are possible.  A bad cookie should
2160                  * be silently discarded, but think about logging it too.
2161                  */
2162                 switch (error) {
2163                 case -SCTP_IERROR_NOMEM:
2164                         goto nomem;
2165 
2166                 case -SCTP_IERROR_STALE_COOKIE:
2167                         sctp_send_stale_cookie_err(net, ep, asoc, chunk, commands,
2168                                                    err_chk_p);
2169                         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2170                 case -SCTP_IERROR_BAD_SIG:
2171                 default:
2172                         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2173                 }
2174         }
2175 
2176         /* Update socket peer label if first association. */
2177         if (security_sctp_assoc_request((struct sctp_endpoint *)ep,
2178                                         chunk->skb))
2179                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2180 
2181         /* Set temp so that it won't be added into hashtable */
2182         new_asoc->temp = 1;
2183 
2184         /* Compare the tie_tag in cookie with the verification tag of
2185          * current association.
2186          */
2187         action = sctp_tietags_compare(new_asoc, asoc);
2188 
2189         switch (action) {
2190         case 'A': /* Association restart. */
2191                 retval = sctp_sf_do_dupcook_a(net, ep, asoc, chunk, commands,
2192                                               new_asoc);
2193                 break;
2194 
2195         case 'B': /* Collision case B. */
2196                 retval = sctp_sf_do_dupcook_b(net, ep, asoc, chunk, commands,
2197                                               new_asoc);
2198                 break;
2199 
2200         case 'C': /* Collision case C. */
2201                 retval = sctp_sf_do_dupcook_c(net, ep, asoc, chunk, commands,
2202                                               new_asoc);
2203                 break;
2204 
2205         case 'D': /* Collision case D. */
2206                 retval = sctp_sf_do_dupcook_d(net, ep, asoc, chunk, commands,
2207                                               new_asoc);
2208                 break;
2209 
2210         default: /* Discard packet for all others. */
2211                 retval = sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2212                 break;
2213         }
2214 
2215         /* Delete the tempory new association. */
2216         sctp_add_cmd_sf(commands, SCTP_CMD_SET_ASOC, SCTP_ASOC(new_asoc));
2217         sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
2218 
2219         /* Restore association pointer to provide SCTP command interpeter
2220          * with a valid context in case it needs to manipulate
2221          * the queues */
2222         sctp_add_cmd_sf(commands, SCTP_CMD_SET_ASOC,
2223                          SCTP_ASOC((struct sctp_association *)asoc));
2224 
2225         return retval;
2226 
2227 nomem:
2228         return SCTP_DISPOSITION_NOMEM;
2229 }
2230 
2231 /*
2232  * Process an ABORT.  (SHUTDOWN-PENDING state)
2233  *
2234  * See sctp_sf_do_9_1_abort().
2235  */
2236 enum sctp_disposition sctp_sf_shutdown_pending_abort(
2237                                         struct net *net,
2238                                         const struct sctp_endpoint *ep,
2239                                         const struct sctp_association *asoc,
2240                                         const union sctp_subtype type,
2241                                         void *arg,
2242                                         struct sctp_cmd_seq *commands)
2243 {
2244         struct sctp_chunk *chunk = arg;
2245 
2246         if (!sctp_vtag_verify_either(chunk, asoc))
2247                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2248 
2249         /* Make sure that the ABORT chunk has a valid length.
2250          * Since this is an ABORT chunk, we have to discard it
2251          * because of the following text:
2252          * RFC 2960, Section 3.3.7
2253          *    If an endpoint receives an ABORT with a format error or for an
2254          *    association that doesn't exist, it MUST silently discard it.
2255          * Because the length is "invalid", we can't really discard just
2256          * as we do not know its true length.  So, to be safe, discard the
2257          * packet.
2258          */
2259         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_abort_chunk)))
2260                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2261 
2262         /* ADD-IP: Special case for ABORT chunks
2263          * F4)  One special consideration is that ABORT Chunks arriving
2264          * destined to the IP address being deleted MUST be
2265          * ignored (see Section 5.3.1 for further details).
2266          */
2267         if (SCTP_ADDR_DEL ==
2268                     sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest))
2269                 return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands);
2270 
2271         return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands);
2272 }
2273 
2274 /*
2275  * Process an ABORT.  (SHUTDOWN-SENT state)
2276  *
2277  * See sctp_sf_do_9_1_abort().
2278  */
2279 enum sctp_disposition sctp_sf_shutdown_sent_abort(
2280                                         struct net *net,
2281                                         const struct sctp_endpoint *ep,
2282                                         const struct sctp_association *asoc,
2283                                         const union sctp_subtype type,
2284                                         void *arg,
2285                                         struct sctp_cmd_seq *commands)
2286 {
2287         struct sctp_chunk *chunk = arg;
2288 
2289         if (!sctp_vtag_verify_either(chunk, asoc))
2290                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2291 
2292         /* Make sure that the ABORT chunk has a valid length.
2293          * Since this is an ABORT chunk, we have to discard it
2294          * because of the following text:
2295          * RFC 2960, Section 3.3.7
2296          *    If an endpoint receives an ABORT with a format error or for an
2297          *    association that doesn't exist, it MUST silently discard it.
2298          * Because the length is "invalid", we can't really discard just
2299          * as we do not know its true length.  So, to be safe, discard the
2300          * packet.
2301          */
2302         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_abort_chunk)))
2303                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2304 
2305         /* ADD-IP: Special case for ABORT chunks
2306          * F4)  One special consideration is that ABORT Chunks arriving
2307          * destined to the IP address being deleted MUST be
2308          * ignored (see Section 5.3.1 for further details).
2309          */
2310         if (SCTP_ADDR_DEL ==
2311                     sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest))
2312                 return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands);
2313 
2314         /* Stop the T2-shutdown timer. */
2315         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
2316                         SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
2317 
2318         /* Stop the T5-shutdown guard timer.  */
2319         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
2320                         SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
2321 
2322         return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands);
2323 }
2324 
2325 /*
2326  * Process an ABORT.  (SHUTDOWN-ACK-SENT state)
2327  *
2328  * See sctp_sf_do_9_1_abort().
2329  */
2330 enum sctp_disposition sctp_sf_shutdown_ack_sent_abort(
2331                                         struct net *net,
2332                                         const struct sctp_endpoint *ep,
2333                                         const struct sctp_association *asoc,
2334                                         const union sctp_subtype type,
2335                                         void *arg,
2336                                         struct sctp_cmd_seq *commands)
2337 {
2338         /* The same T2 timer, so we should be able to use
2339          * common function with the SHUTDOWN-SENT state.
2340          */
2341         return sctp_sf_shutdown_sent_abort(net, ep, asoc, type, arg, commands);
2342 }
2343 
2344 /*
2345  * Handle an Error received in COOKIE_ECHOED state.
2346  *
2347  * Only handle the error type of stale COOKIE Error, the other errors will
2348  * be ignored.
2349  *
2350  * Inputs
2351  * (endpoint, asoc, chunk)
2352  *
2353  * Outputs
2354  * (asoc, reply_msg, msg_up, timers, counters)
2355  *
2356  * The return value is the disposition of the chunk.
2357  */
2358 enum sctp_disposition sctp_sf_cookie_echoed_err(
2359                                         struct net *net,
2360                                         const struct sctp_endpoint *ep,
2361                                         const struct sctp_association *asoc,
2362                                         const union sctp_subtype type,
2363                                         void *arg,
2364                                         struct sctp_cmd_seq *commands)
2365 {
2366         struct sctp_chunk *chunk = arg;
2367         struct sctp_errhdr *err;
2368 
2369         if (!sctp_vtag_verify(chunk, asoc))
2370                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2371 
2372         /* Make sure that the ERROR chunk has a valid length.
2373          * The parameter walking depends on this as well.
2374          */
2375         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_operr_chunk)))
2376                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2377                                                   commands);
2378 
2379         /* Process the error here */
2380         /* FUTURE FIXME:  When PR-SCTP related and other optional
2381          * parms are emitted, this will have to change to handle multiple
2382          * errors.
2383          */
2384         sctp_walk_errors(err, chunk->chunk_hdr) {
2385                 if (SCTP_ERROR_STALE_COOKIE == err->cause)
2386                         return sctp_sf_do_5_2_6_stale(net, ep, asoc, type,
2387                                                         arg, commands);
2388         }
2389 
2390         /* It is possible to have malformed error causes, and that
2391          * will cause us to end the walk early.  However, since
2392          * we are discarding the packet, there should be no adverse
2393          * affects.
2394          */
2395         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2396 }
2397 
2398 /*
2399  * Handle a Stale COOKIE Error
2400  *
2401  * Section: 5.2.6 Handle Stale COOKIE Error
2402  * If the association is in the COOKIE-ECHOED state, the endpoint may elect
2403  * one of the following three alternatives.
2404  * ...
2405  * 3) Send a new INIT chunk to the endpoint, adding a Cookie
2406  *    Preservative parameter requesting an extension to the lifetime of
2407  *    the State Cookie. When calculating the time extension, an
2408  *    implementation SHOULD use the RTT information measured based on the
2409  *    previous COOKIE ECHO / ERROR exchange, and should add no more
2410  *    than 1 second beyond the measured RTT, due to long State Cookie
2411  *    lifetimes making the endpoint more subject to a replay attack.
2412  *
2413  * Verification Tag:  Not explicit, but safe to ignore.
2414  *
2415  * Inputs
2416  * (endpoint, asoc, chunk)
2417  *
2418  * Outputs
2419  * (asoc, reply_msg, msg_up, timers, counters)
2420  *
2421  * The return value is the disposition of the chunk.
2422  */
2423 static enum sctp_disposition sctp_sf_do_5_2_6_stale(
2424                                         struct net *net,
2425                                         const struct sctp_endpoint *ep,
2426                                         const struct sctp_association *asoc,
2427                                         const union sctp_subtype type,
2428                                         void *arg,
2429                                         struct sctp_cmd_seq *commands)
2430 {
2431         int attempts = asoc->init_err_counter + 1;
2432         struct sctp_chunk *chunk = arg, *reply;
2433         struct sctp_cookie_preserve_param bht;
2434         struct sctp_bind_addr *bp;
2435         struct sctp_errhdr *err;
2436         u32 stale;
2437 
2438         if (attempts > asoc->max_init_attempts) {
2439                 sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
2440                                 SCTP_ERROR(ETIMEDOUT));
2441                 sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
2442                                 SCTP_PERR(SCTP_ERROR_STALE_COOKIE));
2443                 return SCTP_DISPOSITION_DELETE_TCB;
2444         }
2445 
2446         err = (struct sctp_errhdr *)(chunk->skb->data);
2447 
2448         /* When calculating the time extension, an implementation
2449          * SHOULD use the RTT information measured based on the
2450          * previous COOKIE ECHO / ERROR exchange, and should add no
2451          * more than 1 second beyond the measured RTT, due to long
2452          * State Cookie lifetimes making the endpoint more subject to
2453          * a replay attack.
2454          * Measure of Staleness's unit is usec. (1/1000000 sec)
2455          * Suggested Cookie Life-span Increment's unit is msec.
2456          * (1/1000 sec)
2457          * In general, if you use the suggested cookie life, the value
2458          * found in the field of measure of staleness should be doubled
2459          * to give ample time to retransmit the new cookie and thus
2460          * yield a higher probability of success on the reattempt.
2461          */
2462         stale = ntohl(*(__be32 *)((u8 *)err + sizeof(*err)));
2463         stale = (stale * 2) / 1000;
2464 
2465         bht.param_hdr.type = SCTP_PARAM_COOKIE_PRESERVATIVE;
2466         bht.param_hdr.length = htons(sizeof(bht));
2467         bht.lifespan_increment = htonl(stale);
2468 
2469         /* Build that new INIT chunk.  */
2470         bp = (struct sctp_bind_addr *) &asoc->base.bind_addr;
2471         reply = sctp_make_init(asoc, bp, GFP_ATOMIC, sizeof(bht));
2472         if (!reply)
2473                 goto nomem;
2474 
2475         sctp_addto_chunk(reply, sizeof(bht), &bht);
2476 
2477         /* Clear peer's init_tag cached in assoc as we are sending a new INIT */
2478         sctp_add_cmd_sf(commands, SCTP_CMD_CLEAR_INIT_TAG, SCTP_NULL());
2479 
2480         /* Stop pending T3-rtx and heartbeat timers */
2481         sctp_add_cmd_sf(commands, SCTP_CMD_T3_RTX_TIMERS_STOP, SCTP_NULL());
2482         sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL());
2483 
2484         /* Delete non-primary peer ip addresses since we are transitioning
2485          * back to the COOKIE-WAIT state
2486          */
2487         sctp_add_cmd_sf(commands, SCTP_CMD_DEL_NON_PRIMARY, SCTP_NULL());
2488 
2489         /* If we've sent any data bundled with COOKIE-ECHO we will need to
2490          * resend
2491          */
2492         sctp_add_cmd_sf(commands, SCTP_CMD_T1_RETRAN,
2493                         SCTP_TRANSPORT(asoc->peer.primary_path));
2494 
2495         /* Cast away the const modifier, as we want to just
2496          * rerun it through as a sideffect.
2497          */
2498         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_COUNTER_INC, SCTP_NULL());
2499 
2500         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
2501                         SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
2502         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
2503                         SCTP_STATE(SCTP_STATE_COOKIE_WAIT));
2504         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
2505                         SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
2506 
2507         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
2508 
2509         return SCTP_DISPOSITION_CONSUME;
2510 
2511 nomem:
2512         return SCTP_DISPOSITION_NOMEM;
2513 }
2514 
2515 /*
2516  * Process an ABORT.
2517  *
2518  * Section: 9.1
2519  * After checking the Verification Tag, the receiving endpoint shall
2520  * remove the association from its record, and shall report the
2521  * termination to its upper layer.
2522  *
2523  * Verification Tag: 8.5.1 Exceptions in Verification Tag Rules
2524  * B) Rules for packet carrying ABORT:
2525  *
2526  *  - The endpoint shall always fill in the Verification Tag field of the
2527  *    outbound packet with the destination endpoint's tag value if it
2528  *    is known.
2529  *
2530  *  - If the ABORT is sent in response to an OOTB packet, the endpoint
2531  *    MUST follow the procedure described in Section 8.4.
2532  *
2533  *  - The receiver MUST accept the packet if the Verification Tag
2534  *    matches either its own tag, OR the tag of its peer. Otherwise, the
2535  *    receiver MUST silently discard the packet and take no further
2536  *    action.
2537  *
2538  * Inputs
2539  * (endpoint, asoc, chunk)
2540  *
2541  * Outputs
2542  * (asoc, reply_msg, msg_up, timers, counters)
2543  *
2544  * The return value is the disposition of the chunk.
2545  */
2546 enum sctp_disposition sctp_sf_do_9_1_abort(
2547                                         struct net *net,
2548                                         const struct sctp_endpoint *ep,
2549                                         const struct sctp_association *asoc,
2550                                         const union sctp_subtype type,
2551                                         void *arg,
2552                                         struct sctp_cmd_seq *commands)
2553 {
2554         struct sctp_chunk *chunk = arg;
2555 
2556         if (!sctp_vtag_verify_either(chunk, asoc))
2557                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2558 
2559         /* Make sure that the ABORT chunk has a valid length.
2560          * Since this is an ABORT chunk, we have to discard it
2561          * because of the following text:
2562          * RFC 2960, Section 3.3.7
2563          *    If an endpoint receives an ABORT with a format error or for an
2564          *    association that doesn't exist, it MUST silently discard it.
2565          * Because the length is "invalid", we can't really discard just
2566          * as we do not know its true length.  So, to be safe, discard the
2567          * packet.
2568          */
2569         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_abort_chunk)))
2570                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2571 
2572         /* ADD-IP: Special case for ABORT chunks
2573          * F4)  One special consideration is that ABORT Chunks arriving
2574          * destined to the IP address being deleted MUST be
2575          * ignored (see Section 5.3.1 for further details).
2576          */
2577         if (SCTP_ADDR_DEL ==
2578                     sctp_bind_addr_state(&asoc->base.bind_addr, &chunk->dest))
2579                 return sctp_sf_discard_chunk(net, ep, asoc, type, arg, commands);
2580 
2581         return __sctp_sf_do_9_1_abort(net, ep, asoc, type, arg, commands);
2582 }
2583 
2584 static enum sctp_disposition __sctp_sf_do_9_1_abort(
2585                                         struct net *net,
2586                                         const struct sctp_endpoint *ep,
2587                                         const struct sctp_association *asoc,
2588                                         const union sctp_subtype type,
2589                                         void *arg,
2590                                         struct sctp_cmd_seq *commands)
2591 {
2592         __be16 error = SCTP_ERROR_NO_ERROR;
2593         struct sctp_chunk *chunk = arg;
2594         unsigned int len;
2595 
2596         /* See if we have an error cause code in the chunk.  */
2597         len = ntohs(chunk->chunk_hdr->length);
2598         if (len >= sizeof(struct sctp_chunkhdr) + sizeof(struct sctp_errhdr)) {
2599                 struct sctp_errhdr *err;
2600 
2601                 sctp_walk_errors(err, chunk->chunk_hdr);
2602                 if ((void *)err != (void *)chunk->chunk_end)
2603                         return sctp_sf_pdiscard(net, ep, asoc, type, arg,
2604                                                 commands);
2605 
2606                 error = ((struct sctp_errhdr *)chunk->skb->data)->cause;
2607         }
2608 
2609         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(ECONNRESET));
2610         /* ASSOC_FAILED will DELETE_TCB. */
2611         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED, SCTP_PERR(error));
2612         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
2613         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
2614 
2615         return SCTP_DISPOSITION_ABORT;
2616 }
2617 
2618 /*
2619  * Process an ABORT.  (COOKIE-WAIT state)
2620  *
2621  * See sctp_sf_do_9_1_abort() above.
2622  */
2623 enum sctp_disposition sctp_sf_cookie_wait_abort(
2624                                         struct net *net,
2625                                         const struct sctp_endpoint *ep,
2626                                         const struct sctp_association *asoc,
2627                                         const union sctp_subtype type,
2628                                         void *arg,
2629                                         struct sctp_cmd_seq *commands)
2630 {
2631         __be16 error = SCTP_ERROR_NO_ERROR;
2632         struct sctp_chunk *chunk = arg;
2633         unsigned int len;
2634 
2635         if (!sctp_vtag_verify_either(chunk, asoc))
2636                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2637 
2638         /* Make sure that the ABORT chunk has a valid length.
2639          * Since this is an ABORT chunk, we have to discard it
2640          * because of the following text:
2641          * RFC 2960, Section 3.3.7
2642          *    If an endpoint receives an ABORT with a format error or for an
2643          *    association that doesn't exist, it MUST silently discard it.
2644          * Because the length is "invalid", we can't really discard just
2645          * as we do not know its true length.  So, to be safe, discard the
2646          * packet.
2647          */
2648         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_abort_chunk)))
2649                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2650 
2651         /* See if we have an error cause code in the chunk.  */
2652         len = ntohs(chunk->chunk_hdr->length);
2653         if (len >= sizeof(struct sctp_chunkhdr) + sizeof(struct sctp_errhdr))
2654                 error = ((struct sctp_errhdr *)chunk->skb->data)->cause;
2655 
2656         return sctp_stop_t1_and_abort(net, commands, error, ECONNREFUSED, asoc,
2657                                       chunk->transport);
2658 }
2659 
2660 /*
2661  * Process an incoming ICMP as an ABORT.  (COOKIE-WAIT state)
2662  */
2663 enum sctp_disposition sctp_sf_cookie_wait_icmp_abort(
2664                                         struct net *net,
2665                                         const struct sctp_endpoint *ep,
2666                                         const struct sctp_association *asoc,
2667                                         const union sctp_subtype type,
2668                                         void *arg,
2669                                         struct sctp_cmd_seq *commands)
2670 {
2671         return sctp_stop_t1_and_abort(net, commands, SCTP_ERROR_NO_ERROR,
2672                                       ENOPROTOOPT, asoc,
2673                                       (struct sctp_transport *)arg);
2674 }
2675 
2676 /*
2677  * Process an ABORT.  (COOKIE-ECHOED state)
2678  */
2679 enum sctp_disposition sctp_sf_cookie_echoed_abort(
2680                                         struct net *net,
2681                                         const struct sctp_endpoint *ep,
2682                                         const struct sctp_association *asoc,
2683                                         const union sctp_subtype type,
2684                                         void *arg,
2685                                         struct sctp_cmd_seq *commands)
2686 {
2687         /* There is a single T1 timer, so we should be able to use
2688          * common function with the COOKIE-WAIT state.
2689          */
2690         return sctp_sf_cookie_wait_abort(net, ep, asoc, type, arg, commands);
2691 }
2692 
2693 /*
2694  * Stop T1 timer and abort association with "INIT failed".
2695  *
2696  * This is common code called by several sctp_sf_*_abort() functions above.
2697  */
2698 static enum sctp_disposition sctp_stop_t1_and_abort(
2699                                         struct net *net,
2700                                         struct sctp_cmd_seq *commands,
2701                                         __be16 error, int sk_err,
2702                                         const struct sctp_association *asoc,
2703                                         struct sctp_transport *transport)
2704 {
2705         pr_debug("%s: ABORT received (INIT)\n", __func__);
2706 
2707         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
2708                         SCTP_STATE(SCTP_STATE_CLOSED));
2709         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
2710         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
2711                         SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
2712         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR, SCTP_ERROR(sk_err));
2713         /* CMD_INIT_FAILED will DELETE_TCB. */
2714         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
2715                         SCTP_PERR(error));
2716 
2717         return SCTP_DISPOSITION_ABORT;
2718 }
2719 
2720 /*
2721  * sctp_sf_do_9_2_shut
2722  *
2723  * Section: 9.2
2724  * Upon the reception of the SHUTDOWN, the peer endpoint shall
2725  *  - enter the SHUTDOWN-RECEIVED state,
2726  *
2727  *  - stop accepting new data from its SCTP user
2728  *
2729  *  - verify, by checking the Cumulative TSN Ack field of the chunk,
2730  *    that all its outstanding DATA chunks have been received by the
2731  *    SHUTDOWN sender.
2732  *
2733  * Once an endpoint as reached the SHUTDOWN-RECEIVED state it MUST NOT
2734  * send a SHUTDOWN in response to a ULP request. And should discard
2735  * subsequent SHUTDOWN chunks.
2736  *
2737  * If there are still outstanding DATA chunks left, the SHUTDOWN
2738  * receiver shall continue to follow normal data transmission
2739  * procedures defined in Section 6 until all outstanding DATA chunks
2740  * are acknowledged; however, the SHUTDOWN receiver MUST NOT accept
2741  * new data from its SCTP user.
2742  *
2743  * Verification Tag:  8.5 Verification Tag [Normal verification]
2744  *
2745  * Inputs
2746  * (endpoint, asoc, chunk)
2747  *
2748  * Outputs
2749  * (asoc, reply_msg, msg_up, timers, counters)
2750  *
2751  * The return value is the disposition of the chunk.
2752  */
2753 enum sctp_disposition sctp_sf_do_9_2_shutdown(
2754                                         struct net *net,
2755                                         const struct sctp_endpoint *ep,
2756                                         const struct sctp_association *asoc,
2757                                         const union sctp_subtype type,
2758                                         void *arg,
2759                                         struct sctp_cmd_seq *commands)
2760 {
2761         enum sctp_disposition disposition;
2762         struct sctp_chunk *chunk = arg;
2763         struct sctp_shutdownhdr *sdh;
2764         struct sctp_ulpevent *ev;
2765         __u32 ctsn;
2766 
2767         if (!sctp_vtag_verify(chunk, asoc))
2768                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2769 
2770         /* Make sure that the SHUTDOWN chunk has a valid length. */
2771         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_shutdown_chunk)))
2772                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2773                                                   commands);
2774 
2775         /* Convert the elaborate header.  */
2776         sdh = (struct sctp_shutdownhdr *)chunk->skb->data;
2777         skb_pull(chunk->skb, sizeof(*sdh));
2778         chunk->subh.shutdown_hdr = sdh;
2779         ctsn = ntohl(sdh->cum_tsn_ack);
2780 
2781         if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
2782                 pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn,
2783                          asoc->ctsn_ack_point);
2784 
2785                 return SCTP_DISPOSITION_DISCARD;
2786         }
2787 
2788         /* If Cumulative TSN Ack beyond the max tsn currently
2789          * send, terminating the association and respond to the
2790          * sender with an ABORT.
2791          */
2792         if (!TSN_lt(ctsn, asoc->next_tsn))
2793                 return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands);
2794 
2795         /* API 5.3.1.5 SCTP_SHUTDOWN_EVENT
2796          * When a peer sends a SHUTDOWN, SCTP delivers this notification to
2797          * inform the application that it should cease sending data.
2798          */
2799         ev = sctp_ulpevent_make_shutdown_event(asoc, 0, GFP_ATOMIC);
2800         if (!ev) {
2801                 disposition = SCTP_DISPOSITION_NOMEM;
2802                 goto out;
2803         }
2804         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
2805 
2806         /* Upon the reception of the SHUTDOWN, the peer endpoint shall
2807          *  - enter the SHUTDOWN-RECEIVED state,
2808          *  - stop accepting new data from its SCTP user
2809          *
2810          * [This is implicit in the new state.]
2811          */
2812         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
2813                         SCTP_STATE(SCTP_STATE_SHUTDOWN_RECEIVED));
2814         disposition = SCTP_DISPOSITION_CONSUME;
2815 
2816         if (sctp_outq_is_empty(&asoc->outqueue)) {
2817                 disposition = sctp_sf_do_9_2_shutdown_ack(net, ep, asoc, type,
2818                                                           arg, commands);
2819         }
2820 
2821         if (SCTP_DISPOSITION_NOMEM == disposition)
2822                 goto out;
2823 
2824         /*  - verify, by checking the Cumulative TSN Ack field of the
2825          *    chunk, that all its outstanding DATA chunks have been
2826          *    received by the SHUTDOWN sender.
2827          */
2828         sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_CTSN,
2829                         SCTP_BE32(chunk->subh.shutdown_hdr->cum_tsn_ack));
2830 
2831 out:
2832         return disposition;
2833 }
2834 
2835 /*
2836  * sctp_sf_do_9_2_shut_ctsn
2837  *
2838  * Once an endpoint has reached the SHUTDOWN-RECEIVED state,
2839  * it MUST NOT send a SHUTDOWN in response to a ULP request.
2840  * The Cumulative TSN Ack of the received SHUTDOWN chunk
2841  * MUST be processed.
2842  */
2843 enum sctp_disposition sctp_sf_do_9_2_shut_ctsn(
2844                                         struct net *net,
2845                                         const struct sctp_endpoint *ep,
2846                                         const struct sctp_association *asoc,
2847                                         const union sctp_subtype type,
2848                                         void *arg,
2849                                         struct sctp_cmd_seq *commands)
2850 {
2851         struct sctp_chunk *chunk = arg;
2852         struct sctp_shutdownhdr *sdh;
2853         __u32 ctsn;
2854 
2855         if (!sctp_vtag_verify(chunk, asoc))
2856                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2857 
2858         /* Make sure that the SHUTDOWN chunk has a valid length. */
2859         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_shutdown_chunk)))
2860                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2861                                                   commands);
2862 
2863         sdh = (struct sctp_shutdownhdr *)chunk->skb->data;
2864         ctsn = ntohl(sdh->cum_tsn_ack);
2865 
2866         if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
2867                 pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn,
2868                          asoc->ctsn_ack_point);
2869 
2870                 return SCTP_DISPOSITION_DISCARD;
2871         }
2872 
2873         /* If Cumulative TSN Ack beyond the max tsn currently
2874          * send, terminating the association and respond to the
2875          * sender with an ABORT.
2876          */
2877         if (!TSN_lt(ctsn, asoc->next_tsn))
2878                 return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands);
2879 
2880         /* verify, by checking the Cumulative TSN Ack field of the
2881          * chunk, that all its outstanding DATA chunks have been
2882          * received by the SHUTDOWN sender.
2883          */
2884         sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_CTSN,
2885                         SCTP_BE32(sdh->cum_tsn_ack));
2886 
2887         return SCTP_DISPOSITION_CONSUME;
2888 }
2889 
2890 /* RFC 2960 9.2
2891  * If an endpoint is in SHUTDOWN-ACK-SENT state and receives an INIT chunk
2892  * (e.g., if the SHUTDOWN COMPLETE was lost) with source and destination
2893  * transport addresses (either in the IP addresses or in the INIT chunk)
2894  * that belong to this association, it should discard the INIT chunk and
2895  * retransmit the SHUTDOWN ACK chunk.
2896  */
2897 enum sctp_disposition sctp_sf_do_9_2_reshutack(
2898                                         struct net *net,
2899                                         const struct sctp_endpoint *ep,
2900                                         const struct sctp_association *asoc,
2901                                         const union sctp_subtype type,
2902                                         void *arg,
2903                                         struct sctp_cmd_seq *commands)
2904 {
2905         struct sctp_chunk *chunk = arg;
2906         struct sctp_chunk *reply;
2907 
2908         /* Make sure that the chunk has a valid length */
2909         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
2910                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2911                                                   commands);
2912 
2913         /* Since we are not going to really process this INIT, there
2914          * is no point in verifying chunk boundries.  Just generate
2915          * the SHUTDOWN ACK.
2916          */
2917         reply = sctp_make_shutdown_ack(asoc, chunk);
2918         if (NULL == reply)
2919                 goto nomem;
2920 
2921         /* Set the transport for the SHUTDOWN ACK chunk and the timeout for
2922          * the T2-SHUTDOWN timer.
2923          */
2924         sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
2925 
2926         /* and restart the T2-shutdown timer. */
2927         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
2928                         SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
2929 
2930         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
2931 
2932         return SCTP_DISPOSITION_CONSUME;
2933 nomem:
2934         return SCTP_DISPOSITION_NOMEM;
2935 }
2936 
2937 /*
2938  * sctp_sf_do_ecn_cwr
2939  *
2940  * Section:  Appendix A: Explicit Congestion Notification
2941  *
2942  * CWR:
2943  *
2944  * RFC 2481 details a specific bit for a sender to send in the header of
2945  * its next outbound TCP segment to indicate to its peer that it has
2946  * reduced its congestion window.  This is termed the CWR bit.  For
2947  * SCTP the same indication is made by including the CWR chunk.
2948  * This chunk contains one data element, i.e. the TSN number that
2949  * was sent in the ECNE chunk.  This element represents the lowest
2950  * TSN number in the datagram that was originally marked with the
2951  * CE bit.
2952  *
2953  * Verification Tag: 8.5 Verification Tag [Normal verification]
2954  * Inputs
2955  * (endpoint, asoc, chunk)
2956  *
2957  * Outputs
2958  * (asoc, reply_msg, msg_up, timers, counters)
2959  *
2960  * The return value is the disposition of the chunk.
2961  */
2962 enum sctp_disposition sctp_sf_do_ecn_cwr(struct net *net,
2963                                          const struct sctp_endpoint *ep,
2964                                          const struct sctp_association *asoc,
2965                                          const union sctp_subtype type,
2966                                          void *arg,
2967                                          struct sctp_cmd_seq *commands)
2968 {
2969         struct sctp_chunk *chunk = arg;
2970         struct sctp_cwrhdr *cwr;
2971         u32 lowest_tsn;
2972 
2973         if (!sctp_vtag_verify(chunk, asoc))
2974                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
2975 
2976         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_ecne_chunk)))
2977                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
2978                                                   commands);
2979 
2980         cwr = (struct sctp_cwrhdr *)chunk->skb->data;
2981         skb_pull(chunk->skb, sizeof(*cwr));
2982 
2983         lowest_tsn = ntohl(cwr->lowest_tsn);
2984 
2985         /* Does this CWR ack the last sent congestion notification? */
2986         if (TSN_lte(asoc->last_ecne_tsn, lowest_tsn)) {
2987                 /* Stop sending ECNE. */
2988                 sctp_add_cmd_sf(commands,
2989                                 SCTP_CMD_ECN_CWR,
2990                                 SCTP_U32(lowest_tsn));
2991         }
2992         return SCTP_DISPOSITION_CONSUME;
2993 }
2994 
2995 /*
2996  * sctp_sf_do_ecne
2997  *
2998  * Section:  Appendix A: Explicit Congestion Notification
2999  *
3000  * ECN-Echo
3001  *
3002  * RFC 2481 details a specific bit for a receiver to send back in its
3003  * TCP acknowledgements to notify the sender of the Congestion
3004  * Experienced (CE) bit having arrived from the network.  For SCTP this
3005  * same indication is made by including the ECNE chunk.  This chunk
3006  * contains one data element, i.e. the lowest TSN associated with the IP
3007  * datagram marked with the CE bit.....
3008  *
3009  * Verification Tag: 8.5 Verification Tag [Normal verification]
3010  * Inputs
3011  * (endpoint, asoc, chunk)
3012  *
3013  * Outputs
3014  * (asoc, reply_msg, msg_up, timers, counters)
3015  *
3016  * The return value is the disposition of the chunk.
3017  */
3018 enum sctp_disposition sctp_sf_do_ecne(struct net *net,
3019                                       const struct sctp_endpoint *ep,
3020                                       const struct sctp_association *asoc,
3021                                       const union sctp_subtype type,
3022                                       void *arg, struct sctp_cmd_seq *commands)
3023 {
3024         struct sctp_chunk *chunk = arg;
3025         struct sctp_ecnehdr *ecne;
3026 
3027         if (!sctp_vtag_verify(chunk, asoc))
3028                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3029 
3030         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_ecne_chunk)))
3031                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3032                                                   commands);
3033 
3034         ecne = (struct sctp_ecnehdr *)chunk->skb->data;
3035         skb_pull(chunk->skb, sizeof(*ecne));
3036 
3037         /* If this is a newer ECNE than the last CWR packet we sent out */
3038         sctp_add_cmd_sf(commands, SCTP_CMD_ECN_ECNE,
3039                         SCTP_U32(ntohl(ecne->lowest_tsn)));
3040 
3041         return SCTP_DISPOSITION_CONSUME;
3042 }
3043 
3044 /*
3045  * Section: 6.2  Acknowledgement on Reception of DATA Chunks
3046  *
3047  * The SCTP endpoint MUST always acknowledge the reception of each valid
3048  * DATA chunk.
3049  *
3050  * The guidelines on delayed acknowledgement algorithm specified in
3051  * Section 4.2 of [RFC2581] SHOULD be followed. Specifically, an
3052  * acknowledgement SHOULD be generated for at least every second packet
3053  * (not every second DATA chunk) received, and SHOULD be generated within
3054  * 200 ms of the arrival of any unacknowledged DATA chunk. In some
3055  * situations it may be beneficial for an SCTP transmitter to be more
3056  * conservative than the algorithms detailed in this document allow.
3057  * However, an SCTP transmitter MUST NOT be more aggressive than the
3058  * following algorithms allow.
3059  *
3060  * A SCTP receiver MUST NOT generate more than one SACK for every
3061  * incoming packet, other than to update the offered window as the
3062  * receiving application consumes new data.
3063  *
3064  * Verification Tag:  8.5 Verification Tag [Normal verification]
3065  *
3066  * Inputs
3067  * (endpoint, asoc, chunk)
3068  *
3069  * Outputs
3070  * (asoc, reply_msg, msg_up, timers, counters)
3071  *
3072  * The return value is the disposition of the chunk.
3073  */
3074 enum sctp_disposition sctp_sf_eat_data_6_2(struct net *net,
3075                                            const struct sctp_endpoint *ep,
3076                                            const struct sctp_association *asoc,
3077                                            const union sctp_subtype type,
3078                                            void *arg,
3079                                            struct sctp_cmd_seq *commands)
3080 {
3081         union sctp_arg force = SCTP_NOFORCE();
3082         struct sctp_chunk *chunk = arg;
3083         int error;
3084 
3085         if (!sctp_vtag_verify(chunk, asoc)) {
3086                 sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
3087                                 SCTP_NULL());
3088                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3089         }
3090 
3091         if (!sctp_chunk_length_valid(chunk, sctp_datachk_len(&asoc->stream)))
3092                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3093                                                   commands);
3094 
3095         error = sctp_eat_data(asoc, chunk, commands);
3096         switch (error) {
3097         case SCTP_IERROR_NO_ERROR:
3098                 break;
3099         case SCTP_IERROR_HIGH_TSN:
3100         case SCTP_IERROR_BAD_STREAM:
3101                 SCTP_INC_STATS(net, SCTP_MIB_IN_DATA_CHUNK_DISCARDS);
3102                 goto discard_noforce;
3103         case SCTP_IERROR_DUP_TSN:
3104         case SCTP_IERROR_IGNORE_TSN:
3105                 SCTP_INC_STATS(net, SCTP_MIB_IN_DATA_CHUNK_DISCARDS);
3106                 goto discard_force;
3107         case SCTP_IERROR_NO_DATA:
3108                 return SCTP_DISPOSITION_ABORT;
3109         case SCTP_IERROR_PROTO_VIOLATION:
3110                 return sctp_sf_abort_violation(net, ep, asoc, chunk, commands,
3111                                                (u8 *)chunk->subh.data_hdr,
3112                                                sctp_datahdr_len(&asoc->stream));
3113         default:
3114                 BUG();
3115         }
3116 
3117         if (chunk->chunk_hdr->flags & SCTP_DATA_SACK_IMM)
3118                 force = SCTP_FORCE();
3119 
3120         if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) {
3121                 sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
3122                                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
3123         }
3124 
3125         /* If this is the last chunk in a packet, we need to count it
3126          * toward sack generation.  Note that we need to SACK every
3127          * OTHER packet containing data chunks, EVEN IF WE DISCARD
3128          * THEM.  We elect to NOT generate SACK's if the chunk fails
3129          * the verification tag test.
3130          *
3131          * RFC 2960 6.2 Acknowledgement on Reception of DATA Chunks
3132          *
3133          * The SCTP endpoint MUST always acknowledge the reception of
3134          * each valid DATA chunk.
3135          *
3136          * The guidelines on delayed acknowledgement algorithm
3137          * specified in  Section 4.2 of [RFC2581] SHOULD be followed.
3138          * Specifically, an acknowledgement SHOULD be generated for at
3139          * least every second packet (not every second DATA chunk)
3140          * received, and SHOULD be generated within 200 ms of the
3141          * arrival of any unacknowledged DATA chunk.  In some
3142          * situations it may be beneficial for an SCTP transmitter to
3143          * be more conservative than the algorithms detailed in this
3144          * document allow. However, an SCTP transmitter MUST NOT be
3145          * more aggressive than the following algorithms allow.
3146          */
3147         if (chunk->end_of_packet)
3148                 sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, force);
3149 
3150         return SCTP_DISPOSITION_CONSUME;
3151 
3152 discard_force:
3153         /* RFC 2960 6.2 Acknowledgement on Reception of DATA Chunks
3154          *
3155          * When a packet arrives with duplicate DATA chunk(s) and with
3156          * no new DATA chunk(s), the endpoint MUST immediately send a
3157          * SACK with no delay.  If a packet arrives with duplicate
3158          * DATA chunk(s) bundled with new DATA chunks, the endpoint
3159          * MAY immediately send a SACK.  Normally receipt of duplicate
3160          * DATA chunks will occur when the original SACK chunk was lost
3161          * and the peer's RTO has expired.  The duplicate TSN number(s)
3162          * SHOULD be reported in the SACK as duplicate.
3163          */
3164         /* In our case, we split the MAY SACK advice up whether or not
3165          * the last chunk is a duplicate.'
3166          */
3167         if (chunk->end_of_packet)
3168                 sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
3169         return SCTP_DISPOSITION_DISCARD;
3170 
3171 discard_noforce:
3172         if (chunk->end_of_packet)
3173                 sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, force);
3174 
3175         return SCTP_DISPOSITION_DISCARD;
3176 }
3177 
3178 /*
3179  * sctp_sf_eat_data_fast_4_4
3180  *
3181  * Section: 4 (4)
3182  * (4) In SHUTDOWN-SENT state the endpoint MUST acknowledge any received
3183  *    DATA chunks without delay.
3184  *
3185  * Verification Tag:  8.5 Verification Tag [Normal verification]
3186  * Inputs
3187  * (endpoint, asoc, chunk)
3188  *
3189  * Outputs
3190  * (asoc, reply_msg, msg_up, timers, counters)
3191  *
3192  * The return value is the disposition of the chunk.
3193  */
3194 enum sctp_disposition sctp_sf_eat_data_fast_4_4(
3195                                         struct net *net,
3196                                         const struct sctp_endpoint *ep,
3197                                         const struct sctp_association *asoc,
3198                                         const union sctp_subtype type,
3199                                         void *arg,
3200                                         struct sctp_cmd_seq *commands)
3201 {
3202         struct sctp_chunk *chunk = arg;
3203         int error;
3204 
3205         if (!sctp_vtag_verify(chunk, asoc)) {
3206                 sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
3207                                 SCTP_NULL());
3208                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3209         }
3210 
3211         if (!sctp_chunk_length_valid(chunk, sctp_datachk_len(&asoc->stream)))
3212                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3213                                                   commands);
3214 
3215         error = sctp_eat_data(asoc, chunk, commands);
3216         switch (error) {
3217         case SCTP_IERROR_NO_ERROR:
3218         case SCTP_IERROR_HIGH_TSN:
3219         case SCTP_IERROR_DUP_TSN:
3220         case SCTP_IERROR_IGNORE_TSN:
3221         case SCTP_IERROR_BAD_STREAM:
3222                 break;
3223         case SCTP_IERROR_NO_DATA:
3224                 return SCTP_DISPOSITION_ABORT;
3225         case SCTP_IERROR_PROTO_VIOLATION:
3226                 return sctp_sf_abort_violation(net, ep, asoc, chunk, commands,
3227                                                (u8 *)chunk->subh.data_hdr,
3228                                                sctp_datahdr_len(&asoc->stream));
3229         default:
3230                 BUG();
3231         }
3232 
3233         /* Go a head and force a SACK, since we are shutting down. */
3234 
3235         /* Implementor's Guide.
3236          *
3237          * While in SHUTDOWN-SENT state, the SHUTDOWN sender MUST immediately
3238          * respond to each received packet containing one or more DATA chunk(s)
3239          * with a SACK, a SHUTDOWN chunk, and restart the T2-shutdown timer
3240          */
3241         if (chunk->end_of_packet) {
3242                 /* We must delay the chunk creation since the cumulative
3243                  * TSN has not been updated yet.
3244                  */
3245                 sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SHUTDOWN, SCTP_NULL());
3246                 sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
3247                 sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
3248                                 SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
3249         }
3250 
3251         return SCTP_DISPOSITION_CONSUME;
3252 }
3253 
3254 /*
3255  * Section: 6.2  Processing a Received SACK
3256  * D) Any time a SACK arrives, the endpoint performs the following:
3257  *
3258  *     i) If Cumulative TSN Ack is less than the Cumulative TSN Ack Point,
3259  *     then drop the SACK.   Since Cumulative TSN Ack is monotonically
3260  *     increasing, a SACK whose Cumulative TSN Ack is less than the
3261  *     Cumulative TSN Ack Point indicates an out-of-order SACK.
3262  *
3263  *     ii) Set rwnd equal to the newly received a_rwnd minus the number
3264  *     of bytes still outstanding after processing the Cumulative TSN Ack
3265  *     and the Gap Ack Blocks.
3266  *
3267  *     iii) If the SACK is missing a TSN that was previously
3268  *     acknowledged via a Gap Ack Block (e.g., the data receiver
3269  *     reneged on the data), then mark the corresponding DATA chunk
3270  *     as available for retransmit:  Mark it as missing for fast
3271  *     retransmit as described in Section 7.2.4 and if no retransmit
3272  *     timer is running for the destination address to which the DATA
3273  *     chunk was originally transmitted, then T3-rtx is started for
3274  *     that destination address.
3275  *
3276  * Verification Tag:  8.5 Verification Tag [Normal verification]
3277  *
3278  * Inputs
3279  * (endpoint, asoc, chunk)
3280  *
3281  * Outputs
3282  * (asoc, reply_msg, msg_up, timers, counters)
3283  *
3284  * The return value is the disposition of the chunk.
3285  */
3286 enum sctp_disposition sctp_sf_eat_sack_6_2(struct net *net,
3287                                            const struct sctp_endpoint *ep,
3288                                            const struct sctp_association *asoc,
3289                                            const union sctp_subtype type,
3290                                            void *arg,
3291                                            struct sctp_cmd_seq *commands)
3292 {
3293         struct sctp_chunk *chunk = arg;
3294         struct sctp_sackhdr *sackh;
3295         __u32 ctsn;
3296 
3297         trace_sctp_probe(ep, asoc, chunk);
3298 
3299         if (!sctp_vtag_verify(chunk, asoc))
3300                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3301 
3302         /* Make sure that the SACK chunk has a valid length. */
3303         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_sack_chunk)))
3304                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3305                                                   commands);
3306 
3307         /* Pull the SACK chunk from the data buffer */
3308         sackh = sctp_sm_pull_sack(chunk);
3309         /* Was this a bogus SACK? */
3310         if (!sackh)
3311                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3312         chunk->subh.sack_hdr = sackh;
3313         ctsn = ntohl(sackh->cum_tsn_ack);
3314 
3315         /* i) If Cumulative TSN Ack is less than the Cumulative TSN
3316          *     Ack Point, then drop the SACK.  Since Cumulative TSN
3317          *     Ack is monotonically increasing, a SACK whose
3318          *     Cumulative TSN Ack is less than the Cumulative TSN Ack
3319          *     Point indicates an out-of-order SACK.
3320          */
3321         if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
3322                 pr_debug("%s: ctsn:%x, ctsn_ack_point:%x\n", __func__, ctsn,
3323                          asoc->ctsn_ack_point);
3324 
3325                 return SCTP_DISPOSITION_DISCARD;
3326         }
3327 
3328         /* If Cumulative TSN Ack beyond the max tsn currently
3329          * send, terminating the association and respond to the
3330          * sender with an ABORT.
3331          */
3332         if (!TSN_lt(ctsn, asoc->next_tsn))
3333                 return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands);
3334 
3335         /* Return this SACK for further processing.  */
3336         sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_SACK, SCTP_CHUNK(chunk));
3337 
3338         /* Note: We do the rest of the work on the PROCESS_SACK
3339          * sideeffect.
3340          */
3341         return SCTP_DISPOSITION_CONSUME;
3342 }
3343 
3344 /*
3345  * Generate an ABORT in response to a packet.
3346  *
3347  * Section: 8.4 Handle "Out of the blue" Packets, sctpimpguide 2.41
3348  *
3349  * 8) The receiver should respond to the sender of the OOTB packet with
3350  *    an ABORT.  When sending the ABORT, the receiver of the OOTB packet
3351  *    MUST fill in the Verification Tag field of the outbound packet
3352  *    with the value found in the Verification Tag field of the OOTB
3353  *    packet and set the T-bit in the Chunk Flags to indicate that the
3354  *    Verification Tag is reflected.  After sending this ABORT, the
3355  *    receiver of the OOTB packet shall discard the OOTB packet and take
3356  *    no further action.
3357  *
3358  * Verification Tag:
3359  *
3360  * The return value is the disposition of the chunk.
3361 */
3362 static enum sctp_disposition sctp_sf_tabort_8_4_8(
3363                                         struct net *net,
3364                                         const struct sctp_endpoint *ep,
3365                                         const struct sctp_association *asoc,
3366                                         const union sctp_subtype type,
3367                                         void *arg,
3368                                         struct sctp_cmd_seq *commands)
3369 {
3370         struct sctp_packet *packet = NULL;
3371         struct sctp_chunk *chunk = arg;
3372         struct sctp_chunk *abort;
3373 
3374         packet = sctp_ootb_pkt_new(net, asoc, chunk);
3375         if (!packet)
3376                 return SCTP_DISPOSITION_NOMEM;
3377 
3378         /* Make an ABORT. The T bit will be set if the asoc
3379          * is NULL.
3380          */
3381         abort = sctp_make_abort(asoc, chunk, 0);
3382         if (!abort) {
3383                 sctp_ootb_pkt_free(packet);
3384                 return SCTP_DISPOSITION_NOMEM;
3385         }
3386 
3387         /* Reflect vtag if T-Bit is set */
3388         if (sctp_test_T_bit(abort))
3389                 packet->vtag = ntohl(chunk->sctp_hdr->vtag);
3390 
3391         /* Set the skb to the belonging sock for accounting.  */
3392         abort->skb->sk = ep->base.sk;
3393 
3394         sctp_packet_append_chunk(packet, abort);
3395 
3396         sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
3397                         SCTP_PACKET(packet));
3398 
3399         SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
3400 
3401         sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3402         return SCTP_DISPOSITION_CONSUME;
3403 }
3404 
3405 /*
3406  * Received an ERROR chunk from peer.  Generate SCTP_REMOTE_ERROR
3407  * event as ULP notification for each cause included in the chunk.
3408  *
3409  * API 5.3.1.3 - SCTP_REMOTE_ERROR
3410  *
3411  * The return value is the disposition of the chunk.
3412 */
3413 enum sctp_disposition sctp_sf_operr_notify(struct net *net,
3414                                            const struct sctp_endpoint *ep,
3415                                            const struct sctp_association *asoc,
3416                                            const union sctp_subtype type,
3417                                            void *arg,
3418                                            struct sctp_cmd_seq *commands)
3419 {
3420         struct sctp_chunk *chunk = arg;
3421         struct sctp_errhdr *err;
3422 
3423         if (!sctp_vtag_verify(chunk, asoc))
3424                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3425 
3426         /* Make sure that the ERROR chunk has a valid length. */
3427         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_operr_chunk)))
3428                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3429                                                   commands);
3430         sctp_walk_errors(err, chunk->chunk_hdr);
3431         if ((void *)err != (void *)chunk->chunk_end)
3432                 return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
3433                                                   (void *)err, commands);
3434 
3435         sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_OPERR,
3436                         SCTP_CHUNK(chunk));
3437 
3438         return SCTP_DISPOSITION_CONSUME;
3439 }
3440 
3441 /*
3442  * Process an inbound SHUTDOWN ACK.
3443  *
3444  * From Section 9.2:
3445  * Upon the receipt of the SHUTDOWN ACK, the SHUTDOWN sender shall
3446  * stop the T2-shutdown timer, send a SHUTDOWN COMPLETE chunk to its
3447  * peer, and remove all record of the association.
3448  *
3449  * The return value is the disposition.
3450  */
3451 enum sctp_disposition sctp_sf_do_9_2_final(struct net *net,
3452                                            const struct sctp_endpoint *ep,
3453                                            const struct sctp_association *asoc,
3454                                            const union sctp_subtype type,
3455                                            void *arg,
3456                                            struct sctp_cmd_seq *commands)
3457 {
3458         struct sctp_chunk *chunk = arg;
3459         struct sctp_chunk *reply;
3460         struct sctp_ulpevent *ev;
3461 
3462         if (!sctp_vtag_verify(chunk, asoc))
3463                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3464 
3465         /* Make sure that the SHUTDOWN_ACK chunk has a valid length. */
3466         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
3467                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3468                                                   commands);
3469         /* 10.2 H) SHUTDOWN COMPLETE notification
3470          *
3471          * When SCTP completes the shutdown procedures (section 9.2) this
3472          * notification is passed to the upper layer.
3473          */
3474         ev = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_SHUTDOWN_COMP,
3475                                              0, 0, 0, NULL, GFP_ATOMIC);
3476         if (!ev)
3477                 goto nomem;
3478 
3479         /* ...send a SHUTDOWN COMPLETE chunk to its peer, */
3480         reply = sctp_make_shutdown_complete(asoc, chunk);
3481         if (!reply)
3482                 goto nomem_chunk;
3483 
3484         /* Do all the commands now (after allocation), so that we
3485          * have consistent state if memory allocation failes
3486          */
3487         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(ev));
3488 
3489         /* Upon the receipt of the SHUTDOWN ACK, the SHUTDOWN sender shall
3490          * stop the T2-shutdown timer,
3491          */
3492         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
3493                         SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
3494 
3495         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
3496                         SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
3497 
3498         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
3499                         SCTP_STATE(SCTP_STATE_CLOSED));
3500         SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS);
3501         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
3502         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
3503 
3504         /* ...and remove all record of the association. */
3505         sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
3506         return SCTP_DISPOSITION_DELETE_TCB;
3507 
3508 nomem_chunk:
3509         sctp_ulpevent_free(ev);
3510 nomem:
3511         return SCTP_DISPOSITION_NOMEM;
3512 }
3513 
3514 /*
3515  * RFC 2960, 8.4 - Handle "Out of the blue" Packets, sctpimpguide 2.41.
3516  *
3517  * 5) If the packet contains a SHUTDOWN ACK chunk, the receiver should
3518  *    respond to the sender of the OOTB packet with a SHUTDOWN COMPLETE.
3519  *    When sending the SHUTDOWN COMPLETE, the receiver of the OOTB
3520  *    packet must fill in the Verification Tag field of the outbound
3521  *    packet with the Verification Tag received in the SHUTDOWN ACK and
3522  *    set the T-bit in the Chunk Flags to indicate that the Verification
3523  *    Tag is reflected.
3524  *
3525  * 8) The receiver should respond to the sender of the OOTB packet with
3526  *    an ABORT.  When sending the ABORT, the receiver of the OOTB packet
3527  *    MUST fill in the Verification Tag field of the outbound packet
3528  *    with the value found in the Verification Tag field of the OOTB
3529  *    packet and set the T-bit in the Chunk Flags to indicate that the
3530  *    Verification Tag is reflected.  After sending this ABORT, the
3531  *    receiver of the OOTB packet shall discard the OOTB packet and take
3532  *    no further action.
3533  */
3534 enum sctp_disposition sctp_sf_ootb(struct net *net,
3535                                    const struct sctp_endpoint *ep,
3536                                    const struct sctp_association *asoc,
3537                                    const union sctp_subtype type,
3538                                    void *arg, struct sctp_cmd_seq *commands)
3539 {
3540         struct sctp_chunk *chunk = arg;
3541         struct sk_buff *skb = chunk->skb;
3542         struct sctp_chunkhdr *ch;
3543         struct sctp_errhdr *err;
3544         int ootb_cookie_ack = 0;
3545         int ootb_shut_ack = 0;
3546         __u8 *ch_end;
3547 
3548         SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
3549 
3550         ch = (struct sctp_chunkhdr *)chunk->chunk_hdr;
3551         do {
3552                 /* Report violation if the chunk is less then minimal */
3553                 if (ntohs(ch->length) < sizeof(*ch))
3554                         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3555                                                   commands);
3556 
3557                 /* Report violation if chunk len overflows */
3558                 ch_end = ((__u8 *)ch) + SCTP_PAD4(ntohs(ch->length));
3559                 if (ch_end > skb_tail_pointer(skb))
3560                         return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3561                                                   commands);
3562 
3563                 /* Now that we know we at least have a chunk header,
3564                  * do things that are type appropriate.
3565                  */
3566                 if (SCTP_CID_SHUTDOWN_ACK == ch->type)
3567                         ootb_shut_ack = 1;
3568 
3569                 /* RFC 2960, Section 3.3.7
3570                  *   Moreover, under any circumstances, an endpoint that
3571                  *   receives an ABORT  MUST NOT respond to that ABORT by
3572                  *   sending an ABORT of its own.
3573                  */
3574                 if (SCTP_CID_ABORT == ch->type)
3575                         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3576 
3577                 /* RFC 8.4, 7) If the packet contains a "Stale cookie" ERROR
3578                  * or a COOKIE ACK the SCTP Packet should be silently
3579                  * discarded.
3580                  */
3581 
3582                 if (SCTP_CID_COOKIE_ACK == ch->type)
3583                         ootb_cookie_ack = 1;
3584 
3585                 if (SCTP_CID_ERROR == ch->type) {
3586                         sctp_walk_errors(err, ch) {
3587                                 if (SCTP_ERROR_STALE_COOKIE == err->cause) {
3588                                         ootb_cookie_ack = 1;
3589                                         break;
3590                                 }
3591                         }
3592                 }
3593 
3594                 ch = (struct sctp_chunkhdr *)ch_end;
3595         } while (ch_end < skb_tail_pointer(skb));
3596 
3597         if (ootb_shut_ack)
3598                 return sctp_sf_shut_8_4_5(net, ep, asoc, type, arg, commands);
3599         else if (ootb_cookie_ack)
3600                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3601         else
3602                 return sctp_sf_tabort_8_4_8(net, ep, asoc, type, arg, commands);
3603 }
3604 
3605 /*
3606  * Handle an "Out of the blue" SHUTDOWN ACK.
3607  *
3608  * Section: 8.4 5, sctpimpguide 2.41.
3609  *
3610  * 5) If the packet contains a SHUTDOWN ACK chunk, the receiver should
3611  *    respond to the sender of the OOTB packet with a SHUTDOWN COMPLETE.
3612  *    When sending the SHUTDOWN COMPLETE, the receiver of the OOTB
3613  *    packet must fill in the Verification Tag field of the outbound
3614  *    packet with the Verification Tag received in the SHUTDOWN ACK and
3615  *    set the T-bit in the Chunk Flags to indicate that the Verification
3616  *    Tag is reflected.
3617  *
3618  * Inputs
3619  * (endpoint, asoc, type, arg, commands)
3620  *
3621  * Outputs
3622  * (enum sctp_disposition)
3623  *
3624  * The return value is the disposition of the chunk.
3625  */
3626 static enum sctp_disposition sctp_sf_shut_8_4_5(
3627                                         struct net *net,
3628                                         const struct sctp_endpoint *ep,
3629                                         const struct sctp_association *asoc,
3630                                         const union sctp_subtype type,
3631                                         void *arg,
3632                                         struct sctp_cmd_seq *commands)
3633 {
3634         struct sctp_packet *packet = NULL;
3635         struct sctp_chunk *chunk = arg;
3636         struct sctp_chunk *shut;
3637 
3638         packet = sctp_ootb_pkt_new(net, asoc, chunk);
3639         if (!packet)
3640                 return SCTP_DISPOSITION_NOMEM;
3641 
3642         /* Make an SHUTDOWN_COMPLETE.
3643          * The T bit will be set if the asoc is NULL.
3644          */
3645         shut = sctp_make_shutdown_complete(asoc, chunk);
3646         if (!shut) {
3647                 sctp_ootb_pkt_free(packet);
3648                 return SCTP_DISPOSITION_NOMEM;
3649         }
3650 
3651         /* Reflect vtag if T-Bit is set */
3652         if (sctp_test_T_bit(shut))
3653                 packet->vtag = ntohl(chunk->sctp_hdr->vtag);
3654 
3655         /* Set the skb to the belonging sock for accounting.  */
3656         shut->skb->sk = ep->base.sk;
3657 
3658         sctp_packet_append_chunk(packet, shut);
3659 
3660         sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
3661                         SCTP_PACKET(packet));
3662 
3663         SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
3664 
3665         /* If the chunk length is invalid, we don't want to process
3666          * the reset of the packet.
3667          */
3668         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
3669                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3670 
3671         /* We need to discard the rest of the packet to prevent
3672          * potential bomming attacks from additional bundled chunks.
3673          * This is documented in SCTP Threats ID.
3674          */
3675         return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3676 }
3677 
3678 /*
3679  * Handle SHUTDOWN ACK in COOKIE_ECHOED or COOKIE_WAIT state.
3680  *
3681  * Verification Tag:  8.5.1 E) Rules for packet carrying a SHUTDOWN ACK
3682  *   If the receiver is in COOKIE-ECHOED or COOKIE-WAIT state the
3683  *   procedures in section 8.4 SHOULD be followed, in other words it
3684  *   should be treated as an Out Of The Blue packet.
3685  *   [This means that we do NOT check the Verification Tag on these
3686  *   chunks. --piggy ]
3687  *
3688  */
3689 enum sctp_disposition sctp_sf_do_8_5_1_E_sa(struct net *net,
3690                                             const struct sctp_endpoint *ep,
3691                                             const struct sctp_association *asoc,
3692                                             const union sctp_subtype type,
3693                                             void *arg,
3694                                             struct sctp_cmd_seq *commands)
3695 {
3696         struct sctp_chunk *chunk = arg;
3697 
3698         /* Make sure that the SHUTDOWN_ACK chunk has a valid length. */
3699         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
3700                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3701                                                   commands);
3702 
3703         /* Although we do have an association in this case, it corresponds
3704          * to a restarted association. So the packet is treated as an OOTB
3705          * packet and the state function that handles OOTB SHUTDOWN_ACK is
3706          * called with a NULL association.
3707          */
3708         SCTP_INC_STATS(net, SCTP_MIB_OUTOFBLUES);
3709 
3710         return sctp_sf_shut_8_4_5(net, ep, NULL, type, arg, commands);
3711 }
3712 
3713 /* ADDIP Section 4.2 Upon reception of an ASCONF Chunk.  */
3714 enum sctp_disposition sctp_sf_do_asconf(struct net *net,
3715                                         const struct sctp_endpoint *ep,
3716                                         const struct sctp_association *asoc,
3717                                         const union sctp_subtype type,
3718                                         void *arg,
3719                                         struct sctp_cmd_seq *commands)
3720 {
3721         struct sctp_paramhdr *err_param = NULL;
3722         struct sctp_chunk *asconf_ack = NULL;
3723         struct sctp_chunk *chunk = arg;
3724         struct sctp_addiphdr *hdr;
3725         __u32 serial;
3726 
3727         if (!sctp_vtag_verify(chunk, asoc)) {
3728                 sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
3729                                 SCTP_NULL());
3730                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3731         }
3732 
3733         /* ADD-IP: Section 4.1.1
3734          * This chunk MUST be sent in an authenticated way by using
3735          * the mechanism defined in [I-D.ietf-tsvwg-sctp-auth]. If this chunk
3736          * is received unauthenticated it MUST be silently discarded as
3737          * described in [I-D.ietf-tsvwg-sctp-auth].
3738          */
3739         if (!net->sctp.addip_noauth && !chunk->auth)
3740                 return sctp_sf_discard_chunk(net, ep, asoc, type, arg,
3741                                              commands);
3742 
3743         /* Make sure that the ASCONF ADDIP chunk has a valid length.  */
3744         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_addip_chunk)))
3745                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3746                                                   commands);
3747 
3748         hdr = (struct sctp_addiphdr *)chunk->skb->data;
3749         serial = ntohl(hdr->serial);
3750 
3751         /* Verify the ASCONF chunk before processing it. */
3752         if (!sctp_verify_asconf(asoc, chunk, true, &err_param))
3753                 return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
3754                                                   (void *)err_param, commands);
3755 
3756         /* ADDIP 5.2 E1) Compare the value of the serial number to the value
3757          * the endpoint stored in a new association variable
3758          * 'Peer-Serial-Number'.
3759          */
3760         if (serial == asoc->peer.addip_serial + 1) {
3761                 /* If this is the first instance of ASCONF in the packet,
3762                  * we can clean our old ASCONF-ACKs.
3763                  */
3764                 if (!chunk->has_asconf)
3765                         sctp_assoc_clean_asconf_ack_cache(asoc);
3766 
3767                 /* ADDIP 5.2 E4) When the Sequence Number matches the next one
3768                  * expected, process the ASCONF as described below and after
3769                  * processing the ASCONF Chunk, append an ASCONF-ACK Chunk to
3770                  * the response packet and cache a copy of it (in the event it
3771                  * later needs to be retransmitted).
3772                  *
3773                  * Essentially, do V1-V5.
3774                  */
3775                 asconf_ack = sctp_process_asconf((struct sctp_association *)
3776                                                  asoc, chunk);
3777                 if (!asconf_ack)
3778                         return SCTP_DISPOSITION_NOMEM;
3779         } else if (serial < asoc->peer.addip_serial + 1) {
3780                 /* ADDIP 5.2 E2)
3781                  * If the value found in the Sequence Number is less than the
3782                  * ('Peer- Sequence-Number' + 1), simply skip to the next
3783                  * ASCONF, and include in the outbound response packet
3784                  * any previously cached ASCONF-ACK response that was
3785                  * sent and saved that matches the Sequence Number of the
3786                  * ASCONF.  Note: It is possible that no cached ASCONF-ACK
3787                  * Chunk exists.  This will occur when an older ASCONF
3788                  * arrives out of order.  In such a case, the receiver
3789                  * should skip the ASCONF Chunk and not include ASCONF-ACK
3790                  * Chunk for that chunk.
3791                  */
3792                 asconf_ack = sctp_assoc_lookup_asconf_ack(asoc, hdr->serial);
3793                 if (!asconf_ack)
3794                         return SCTP_DISPOSITION_DISCARD;
3795 
3796                 /* Reset the transport so that we select the correct one
3797                  * this time around.  This is to make sure that we don't
3798                  * accidentally use a stale transport that's been removed.
3799                  */
3800                 asconf_ack->transport = NULL;
3801         } else {
3802                 /* ADDIP 5.2 E5) Otherwise, the ASCONF Chunk is discarded since
3803                  * it must be either a stale packet or from an attacker.
3804                  */
3805                 return SCTP_DISPOSITION_DISCARD;
3806         }
3807 
3808         /* ADDIP 5.2 E6)  The destination address of the SCTP packet
3809          * containing the ASCONF-ACK Chunks MUST be the source address of
3810          * the SCTP packet that held the ASCONF Chunks.
3811          *
3812          * To do this properly, we'll set the destination address of the chunk
3813          * and at the transmit time, will try look up the transport to use.
3814          * Since ASCONFs may be bundled, the correct transport may not be
3815          * created until we process the entire packet, thus this workaround.
3816          */
3817         asconf_ack->dest = chunk->source;
3818         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(asconf_ack));
3819         if (asoc->new_transport) {
3820                 sctp_sf_heartbeat(ep, asoc, type, asoc->new_transport, commands);
3821                 ((struct sctp_association *)asoc)->new_transport = NULL;
3822         }
3823 
3824         return SCTP_DISPOSITION_CONSUME;
3825 }
3826 
3827 /*
3828  * ADDIP Section 4.3 General rules for address manipulation
3829  * When building TLV parameters for the ASCONF Chunk that will add or
3830  * delete IP addresses the D0 to D13 rules should be applied:
3831  */
3832 enum sctp_disposition sctp_sf_do_asconf_ack(struct net *net,
3833                                             const struct sctp_endpoint *ep,
3834                                             const struct sctp_association *asoc,
3835                                             const union sctp_subtype type,
3836                                             void *arg,
3837                                             struct sctp_cmd_seq *commands)
3838 {
3839         struct sctp_chunk *last_asconf = asoc->addip_last_asconf;
3840         struct sctp_paramhdr *err_param = NULL;
3841         struct sctp_chunk *asconf_ack = arg;
3842         struct sctp_addiphdr *addip_hdr;
3843         __u32 sent_serial, rcvd_serial;
3844         struct sctp_chunk *abort;
3845 
3846         if (!sctp_vtag_verify(asconf_ack, asoc)) {
3847                 sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
3848                                 SCTP_NULL());
3849                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3850         }
3851 
3852         /* ADD-IP, Section 4.1.2:
3853          * This chunk MUST be sent in an authenticated way by using
3854          * the mechanism defined in [I-D.ietf-tsvwg-sctp-auth]. If this chunk
3855          * is received unauthenticated it MUST be silently discarded as
3856          * described in [I-D.ietf-tsvwg-sctp-auth].
3857          */
3858         if (!net->sctp.addip_noauth && !asconf_ack->auth)
3859                 return sctp_sf_discard_chunk(net, ep, asoc, type, arg,
3860                                              commands);
3861 
3862         /* Make sure that the ADDIP chunk has a valid length.  */
3863         if (!sctp_chunk_length_valid(asconf_ack,
3864                                      sizeof(struct sctp_addip_chunk)))
3865                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3866                                                   commands);
3867 
3868         addip_hdr = (struct sctp_addiphdr *)asconf_ack->skb->data;
3869         rcvd_serial = ntohl(addip_hdr->serial);
3870 
3871         /* Verify the ASCONF-ACK chunk before processing it. */
3872         if (!sctp_verify_asconf(asoc, asconf_ack, false, &err_param))
3873                 return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
3874                            (void *)err_param, commands);
3875 
3876         if (last_asconf) {
3877                 addip_hdr = (struct sctp_addiphdr *)last_asconf->subh.addip_hdr;
3878                 sent_serial = ntohl(addip_hdr->serial);
3879         } else {
3880                 sent_serial = asoc->addip_serial - 1;
3881         }
3882 
3883         /* D0) If an endpoint receives an ASCONF-ACK that is greater than or
3884          * equal to the next serial number to be used but no ASCONF chunk is
3885          * outstanding the endpoint MUST ABORT the association. Note that a
3886          * sequence number is greater than if it is no more than 2^^31-1
3887          * larger than the current sequence number (using serial arithmetic).
3888          */
3889         if (ADDIP_SERIAL_gte(rcvd_serial, sent_serial + 1) &&
3890             !(asoc->addip_last_asconf)) {
3891                 abort = sctp_make_abort(asoc, asconf_ack,
3892                                         sizeof(struct sctp_errhdr));
3893                 if (abort) {
3894                         sctp_init_cause(abort, SCTP_ERROR_ASCONF_ACK, 0);
3895                         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
3896                                         SCTP_CHUNK(abort));
3897                 }
3898                 /* We are going to ABORT, so we might as well stop
3899                  * processing the rest of the chunks in the packet.
3900                  */
3901                 sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
3902                                 SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
3903                 sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
3904                 sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
3905                                 SCTP_ERROR(ECONNABORTED));
3906                 sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
3907                                 SCTP_PERR(SCTP_ERROR_ASCONF_ACK));
3908                 SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
3909                 SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
3910                 return SCTP_DISPOSITION_ABORT;
3911         }
3912 
3913         if ((rcvd_serial == sent_serial) && asoc->addip_last_asconf) {
3914                 sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
3915                                 SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
3916 
3917                 if (!sctp_process_asconf_ack((struct sctp_association *)asoc,
3918                                              asconf_ack)) {
3919                         /* Successfully processed ASCONF_ACK.  We can
3920                          * release the next asconf if we have one.
3921                          */
3922                         sctp_add_cmd_sf(commands, SCTP_CMD_SEND_NEXT_ASCONF,
3923                                         SCTP_NULL());
3924                         return SCTP_DISPOSITION_CONSUME;
3925                 }
3926 
3927                 abort = sctp_make_abort(asoc, asconf_ack,
3928                                         sizeof(struct sctp_errhdr));
3929                 if (abort) {
3930                         sctp_init_cause(abort, SCTP_ERROR_RSRC_LOW, 0);
3931                         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
3932                                         SCTP_CHUNK(abort));
3933                 }
3934                 /* We are going to ABORT, so we might as well stop
3935                  * processing the rest of the chunks in the packet.
3936                  */
3937                 sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
3938                 sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
3939                                 SCTP_ERROR(ECONNABORTED));
3940                 sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
3941                                 SCTP_PERR(SCTP_ERROR_ASCONF_ACK));
3942                 SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
3943                 SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
3944                 return SCTP_DISPOSITION_ABORT;
3945         }
3946 
3947         return SCTP_DISPOSITION_DISCARD;
3948 }
3949 
3950 /* RE-CONFIG Section 5.2 Upon reception of an RECONF Chunk. */
3951 enum sctp_disposition sctp_sf_do_reconf(struct net *net,
3952                                         const struct sctp_endpoint *ep,
3953                                         const struct sctp_association *asoc,
3954                                         const union sctp_subtype type,
3955                                         void *arg,
3956                                         struct sctp_cmd_seq *commands)
3957 {
3958         struct sctp_paramhdr *err_param = NULL;
3959         struct sctp_chunk *chunk = arg;
3960         struct sctp_reconf_chunk *hdr;
3961         union sctp_params param;
3962 
3963         if (!sctp_vtag_verify(chunk, asoc)) {
3964                 sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
3965                                 SCTP_NULL());
3966                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
3967         }
3968 
3969         /* Make sure that the RECONF chunk has a valid length.  */
3970         if (!sctp_chunk_length_valid(chunk, sizeof(*hdr)))
3971                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
3972                                                   commands);
3973 
3974         if (!sctp_verify_reconf(asoc, chunk, &err_param))
3975                 return sctp_sf_violation_paramlen(net, ep, asoc, type, arg,
3976                                                   (void *)err_param, commands);
3977 
3978         hdr = (struct sctp_reconf_chunk *)chunk->chunk_hdr;
3979         sctp_walk_params(param, hdr, params) {
3980                 struct sctp_chunk *reply = NULL;
3981                 struct sctp_ulpevent *ev = NULL;
3982 
3983                 if (param.p->type == SCTP_PARAM_RESET_OUT_REQUEST)
3984                         reply = sctp_process_strreset_outreq(
3985                                 (struct sctp_association *)asoc, param, &ev);
3986                 else if (param.p->type == SCTP_PARAM_RESET_IN_REQUEST)
3987                         reply = sctp_process_strreset_inreq(
3988                                 (struct sctp_association *)asoc, param, &ev);
3989                 else if (param.p->type == SCTP_PARAM_RESET_TSN_REQUEST)
3990                         reply = sctp_process_strreset_tsnreq(
3991                                 (struct sctp_association *)asoc, param, &ev);
3992                 else if (param.p->type == SCTP_PARAM_RESET_ADD_OUT_STREAMS)
3993                         reply = sctp_process_strreset_addstrm_out(
3994                                 (struct sctp_association *)asoc, param, &ev);
3995                 else if (param.p->type == SCTP_PARAM_RESET_ADD_IN_STREAMS)
3996                         reply = sctp_process_strreset_addstrm_in(
3997                                 (struct sctp_association *)asoc, param, &ev);
3998                 else if (param.p->type == SCTP_PARAM_RESET_RESPONSE)
3999                         reply = sctp_process_strreset_resp(
4000                                 (struct sctp_association *)asoc, param, &ev);
4001 
4002                 if (ev)
4003                         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
4004                                         SCTP_ULPEVENT(ev));
4005 
4006                 if (reply)
4007                         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
4008                                         SCTP_CHUNK(reply));
4009         }
4010 
4011         return SCTP_DISPOSITION_CONSUME;
4012 }
4013 
4014 /*
4015  * PR-SCTP Section 3.6 Receiver Side Implementation of PR-SCTP
4016  *
4017  * When a FORWARD TSN chunk arrives, the data receiver MUST first update
4018  * its cumulative TSN point to the value carried in the FORWARD TSN
4019  * chunk, and then MUST further advance its cumulative TSN point locally
4020  * if possible.
4021  * After the above processing, the data receiver MUST stop reporting any
4022  * missing TSNs earlier than or equal to the new cumulative TSN point.
4023  *
4024  * Verification Tag:  8.5 Verification Tag [Normal verification]
4025  *
4026  * The return value is the disposition of the chunk.
4027  */
4028 enum sctp_disposition sctp_sf_eat_fwd_tsn(struct net *net,
4029                                           const struct sctp_endpoint *ep,
4030                                           const struct sctp_association *asoc,
4031                                           const union sctp_subtype type,
4032                                           void *arg,
4033                                           struct sctp_cmd_seq *commands)
4034 {
4035         struct sctp_fwdtsn_hdr *fwdtsn_hdr;
4036         struct sctp_chunk *chunk = arg;
4037         __u16 len;
4038         __u32 tsn;
4039 
4040         if (!sctp_vtag_verify(chunk, asoc)) {
4041                 sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
4042                                 SCTP_NULL());
4043                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4044         }
4045 
4046         if (!asoc->peer.prsctp_capable)
4047                 return sctp_sf_unk_chunk(net, ep, asoc, type, arg, commands);
4048 
4049         /* Make sure that the FORWARD_TSN chunk has valid length.  */
4050         if (!sctp_chunk_length_valid(chunk, sctp_ftsnchk_len(&asoc->stream)))
4051                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4052                                                   commands);
4053 
4054         fwdtsn_hdr = (struct sctp_fwdtsn_hdr *)chunk->skb->data;
4055         chunk->subh.fwdtsn_hdr = fwdtsn_hdr;
4056         len = ntohs(chunk->chunk_hdr->length);
4057         len -= sizeof(struct sctp_chunkhdr);
4058         skb_pull(chunk->skb, len);
4059 
4060         tsn = ntohl(fwdtsn_hdr->new_cum_tsn);
4061         pr_debug("%s: TSN 0x%x\n", __func__, tsn);
4062 
4063         /* The TSN is too high--silently discard the chunk and count on it
4064          * getting retransmitted later.
4065          */
4066         if (sctp_tsnmap_check(&asoc->peer.tsn_map, tsn) < 0)
4067                 goto discard_noforce;
4068 
4069         if (!asoc->stream.si->validate_ftsn(chunk))
4070                 goto discard_noforce;
4071 
4072         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_FWDTSN, SCTP_U32(tsn));
4073         if (len > sctp_ftsnhdr_len(&asoc->stream))
4074                 sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_FWDTSN,
4075                                 SCTP_CHUNK(chunk));
4076 
4077         /* Count this as receiving DATA. */
4078         if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) {
4079                 sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
4080                                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
4081         }
4082 
4083         /* FIXME: For now send a SACK, but DATA processing may
4084          * send another.
4085          */
4086         sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_NOFORCE());
4087 
4088         return SCTP_DISPOSITION_CONSUME;
4089 
4090 discard_noforce:
4091         return SCTP_DISPOSITION_DISCARD;
4092 }
4093 
4094 enum sctp_disposition sctp_sf_eat_fwd_tsn_fast(
4095                                         struct net *net,
4096                                         const struct sctp_endpoint *ep,
4097                                         const struct sctp_association *asoc,
4098                                         const union sctp_subtype type,
4099                                         void *arg,
4100                                         struct sctp_cmd_seq *commands)
4101 {
4102         struct sctp_fwdtsn_hdr *fwdtsn_hdr;
4103         struct sctp_chunk *chunk = arg;
4104         __u16 len;
4105         __u32 tsn;
4106 
4107         if (!sctp_vtag_verify(chunk, asoc)) {
4108                 sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
4109                                 SCTP_NULL());
4110                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4111         }
4112 
4113         if (!asoc->peer.prsctp_capable)
4114                 return sctp_sf_unk_chunk(net, ep, asoc, type, arg, commands);
4115 
4116         /* Make sure that the FORWARD_TSN chunk has a valid length.  */
4117         if (!sctp_chunk_length_valid(chunk, sctp_ftsnchk_len(&asoc->stream)))
4118                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4119                                                   commands);
4120 
4121         fwdtsn_hdr = (struct sctp_fwdtsn_hdr *)chunk->skb->data;
4122         chunk->subh.fwdtsn_hdr = fwdtsn_hdr;
4123         len = ntohs(chunk->chunk_hdr->length);
4124         len -= sizeof(struct sctp_chunkhdr);
4125         skb_pull(chunk->skb, len);
4126 
4127         tsn = ntohl(fwdtsn_hdr->new_cum_tsn);
4128         pr_debug("%s: TSN 0x%x\n", __func__, tsn);
4129 
4130         /* The TSN is too high--silently discard the chunk and count on it
4131          * getting retransmitted later.
4132          */
4133         if (sctp_tsnmap_check(&asoc->peer.tsn_map, tsn) < 0)
4134                 goto gen_shutdown;
4135 
4136         if (!asoc->stream.si->validate_ftsn(chunk))
4137                 goto gen_shutdown;
4138 
4139         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_FWDTSN, SCTP_U32(tsn));
4140         if (len > sctp_ftsnhdr_len(&asoc->stream))
4141                 sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_FWDTSN,
4142                                 SCTP_CHUNK(chunk));
4143 
4144         /* Go a head and force a SACK, since we are shutting down. */
4145 gen_shutdown:
4146         /* Implementor's Guide.
4147          *
4148          * While in SHUTDOWN-SENT state, the SHUTDOWN sender MUST immediately
4149          * respond to each received packet containing one or more DATA chunk(s)
4150          * with a SACK, a SHUTDOWN chunk, and restart the T2-shutdown timer
4151          */
4152         sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SHUTDOWN, SCTP_NULL());
4153         sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
4154         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
4155                         SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
4156 
4157         return SCTP_DISPOSITION_CONSUME;
4158 }
4159 
4160 /*
4161  * SCTP-AUTH Section 6.3 Receiving authenticated chukns
4162  *
4163  *    The receiver MUST use the HMAC algorithm indicated in the HMAC
4164  *    Identifier field.  If this algorithm was not specified by the
4165  *    receiver in the HMAC-ALGO parameter in the INIT or INIT-ACK chunk
4166  *    during association setup, the AUTH chunk and all chunks after it MUST
4167  *    be discarded and an ERROR chunk SHOULD be sent with the error cause
4168  *    defined in Section 4.1.
4169  *
4170  *    If an endpoint with no shared key receives a Shared Key Identifier
4171  *    other than 0, it MUST silently discard all authenticated chunks.  If
4172  *    the endpoint has at least one endpoint pair shared key for the peer,
4173  *    it MUST use the key specified by the Shared Key Identifier if a
4174  *    key has been configured for that Shared Key Identifier.  If no
4175  *    endpoint pair shared key has been configured for that Shared Key
4176  *    Identifier, all authenticated chunks MUST be silently discarded.
4177  *
4178  * Verification Tag:  8.5 Verification Tag [Normal verification]
4179  *
4180  * The return value is the disposition of the chunk.
4181  */
4182 static enum sctp_ierror sctp_sf_authenticate(
4183                                         const struct sctp_association *asoc,
4184                                         struct sctp_chunk *chunk)
4185 {
4186         struct sctp_shared_key *sh_key = NULL;
4187         struct sctp_authhdr *auth_hdr;
4188         __u8 *save_digest, *digest;
4189         struct sctp_hmac *hmac;
4190         unsigned int sig_len;
4191         __u16 key_id;
4192 
4193         /* Pull in the auth header, so we can do some more verification */
4194         auth_hdr = (struct sctp_authhdr *)chunk->skb->data;
4195         chunk->subh.auth_hdr = auth_hdr;
4196         skb_pull(chunk->skb, sizeof(*auth_hdr));
4197 
4198         /* Make sure that we support the HMAC algorithm from the auth
4199          * chunk.
4200          */
4201         if (!sctp_auth_asoc_verify_hmac_id(asoc, auth_hdr->hmac_id))
4202                 return SCTP_IERROR_AUTH_BAD_HMAC;
4203 
4204         /* Make sure that the provided shared key identifier has been
4205          * configured
4206          */
4207         key_id = ntohs(auth_hdr->shkey_id);
4208         if (key_id != asoc->active_key_id) {
4209                 sh_key = sctp_auth_get_shkey(asoc, key_id);
4210                 if (!sh_key)
4211                         return SCTP_IERROR_AUTH_BAD_KEYID;
4212         }
4213 
4214         /* Make sure that the length of the signature matches what
4215          * we expect.
4216          */
4217         sig_len = ntohs(chunk->chunk_hdr->length) -
4218                   sizeof(struct sctp_auth_chunk);
4219         hmac = sctp_auth_get_hmac(ntohs(auth_hdr->hmac_id));
4220         if (sig_len != hmac->hmac_len)
4221                 return SCTP_IERROR_PROTO_VIOLATION;
4222 
4223         /* Now that we've done validation checks, we can compute and
4224          * verify the hmac.  The steps involved are:
4225          *  1. Save the digest from the chunk.
4226          *  2. Zero out the digest in the chunk.
4227          *  3. Compute the new digest
4228          *  4. Compare saved and new digests.
4229          */
4230         digest = auth_hdr->hmac;
4231         skb_pull(chunk->skb, sig_len);
4232 
4233         save_digest = kmemdup(digest, sig_len, GFP_ATOMIC);
4234         if (!save_digest)
4235                 goto nomem;
4236 
4237         memset(digest, 0, sig_len);
4238 
4239         sctp_auth_calculate_hmac(asoc, chunk->skb,
4240                                  (struct sctp_auth_chunk *)chunk->chunk_hdr,
4241                                  sh_key, GFP_ATOMIC);
4242 
4243         /* Discard the packet if the digests do not match */
4244         if (memcmp(save_digest, digest, sig_len)) {
4245                 kfree(save_digest);
4246                 return SCTP_IERROR_BAD_SIG;
4247         }
4248 
4249         kfree(save_digest);
4250         chunk->auth = 1;
4251 
4252         return SCTP_IERROR_NO_ERROR;
4253 nomem:
4254         return SCTP_IERROR_NOMEM;
4255 }
4256 
4257 enum sctp_disposition sctp_sf_eat_auth(struct net *net,
4258                                        const struct sctp_endpoint *ep,
4259                                        const struct sctp_association *asoc,
4260                                        const union sctp_subtype type,
4261                                        void *arg, struct sctp_cmd_seq *commands)
4262 {
4263         struct sctp_chunk *chunk = arg;
4264         struct sctp_authhdr *auth_hdr;
4265         struct sctp_chunk *err_chunk;
4266         enum sctp_ierror error;
4267 
4268         /* Make sure that the peer has AUTH capable */
4269         if (!asoc->peer.auth_capable)
4270                 return sctp_sf_unk_chunk(net, ep, asoc, type, arg, commands);
4271 
4272         if (!sctp_vtag_verify(chunk, asoc)) {
4273                 sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_BAD_TAG,
4274                                 SCTP_NULL());
4275                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4276         }
4277 
4278         /* Make sure that the AUTH chunk has valid length.  */
4279         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_auth_chunk)))
4280                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4281                                                   commands);
4282 
4283         auth_hdr = (struct sctp_authhdr *)chunk->skb->data;
4284         error = sctp_sf_authenticate(asoc, chunk);
4285         switch (error) {
4286         case SCTP_IERROR_AUTH_BAD_HMAC:
4287                 /* Generate the ERROR chunk and discard the rest
4288                  * of the packet
4289                  */
4290                 err_chunk = sctp_make_op_error(asoc, chunk,
4291                                                SCTP_ERROR_UNSUP_HMAC,
4292                                                &auth_hdr->hmac_id,
4293                                                sizeof(__u16), 0);
4294                 if (err_chunk) {
4295                         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
4296                                         SCTP_CHUNK(err_chunk));
4297                 }
4298                 /* Fall Through */
4299         case SCTP_IERROR_AUTH_BAD_KEYID:
4300         case SCTP_IERROR_BAD_SIG:
4301                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4302 
4303         case SCTP_IERROR_PROTO_VIOLATION:
4304                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4305                                                   commands);
4306 
4307         case SCTP_IERROR_NOMEM:
4308                 return SCTP_DISPOSITION_NOMEM;
4309 
4310         default:                        /* Prevent gcc warnings */
4311                 break;
4312         }
4313 
4314         if (asoc->active_key_id != ntohs(auth_hdr->shkey_id)) {
4315                 struct sctp_ulpevent *ev;
4316 
4317                 ev = sctp_ulpevent_make_authkey(asoc, ntohs(auth_hdr->shkey_id),
4318                                     SCTP_AUTH_NEW_KEY, GFP_ATOMIC);
4319 
4320                 if (!ev)
4321                         return -ENOMEM;
4322 
4323                 sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
4324                                 SCTP_ULPEVENT(ev));
4325         }
4326 
4327         return SCTP_DISPOSITION_CONSUME;
4328 }
4329 
4330 /*
4331  * Process an unknown chunk.
4332  *
4333  * Section: 3.2. Also, 2.1 in the implementor's guide.
4334  *
4335  * Chunk Types are encoded such that the highest-order two bits specify
4336  * the action that must be taken if the processing endpoint does not
4337  * recognize the Chunk Type.
4338  *
4339  * 00 - Stop processing this SCTP packet and discard it, do not process
4340  *      any further chunks within it.
4341  *
4342  * 01 - Stop processing this SCTP packet and discard it, do not process
4343  *      any further chunks within it, and report the unrecognized
4344  *      chunk in an 'Unrecognized Chunk Type'.
4345  *
4346  * 10 - Skip this chunk and continue processing.
4347  *
4348  * 11 - Skip this chunk and continue processing, but report in an ERROR
4349  *      Chunk using the 'Unrecognized Chunk Type' cause of error.
4350  *
4351  * The return value is the disposition of the chunk.
4352  */
4353 enum sctp_disposition sctp_sf_unk_chunk(struct net *net,
4354                                         const struct sctp_endpoint *ep,
4355                                         const struct sctp_association *asoc,
4356                                         const union sctp_subtype type,
4357                                         void *arg,
4358                                         struct sctp_cmd_seq *commands)
4359 {
4360         struct sctp_chunk *unk_chunk = arg;
4361         struct sctp_chunk *err_chunk;
4362         struct sctp_chunkhdr *hdr;
4363 
4364         pr_debug("%s: processing unknown chunk id:%d\n", __func__, type.chunk);
4365 
4366         if (!sctp_vtag_verify(unk_chunk, asoc))
4367                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4368 
4369         /* Make sure that the chunk has a valid length.
4370          * Since we don't know the chunk type, we use a general
4371          * chunkhdr structure to make a comparison.
4372          */
4373         if (!sctp_chunk_length_valid(unk_chunk, sizeof(*hdr)))
4374                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4375                                                   commands);
4376 
4377         switch (type.chunk & SCTP_CID_ACTION_MASK) {
4378         case SCTP_CID_ACTION_DISCARD:
4379                 /* Discard the packet.  */
4380                 return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4381         case SCTP_CID_ACTION_DISCARD_ERR:
4382                 /* Generate an ERROR chunk as response. */
4383                 hdr = unk_chunk->chunk_hdr;
4384                 err_chunk = sctp_make_op_error(asoc, unk_chunk,
4385                                                SCTP_ERROR_UNKNOWN_CHUNK, hdr,
4386                                                SCTP_PAD4(ntohs(hdr->length)),
4387                                                0);
4388                 if (err_chunk) {
4389                         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
4390                                         SCTP_CHUNK(err_chunk));
4391                 }
4392 
4393                 /* Discard the packet.  */
4394                 sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);
4395                 return SCTP_DISPOSITION_CONSUME;
4396         case SCTP_CID_ACTION_SKIP:
4397                 /* Skip the chunk.  */
4398                 return SCTP_DISPOSITION_DISCARD;
4399         case SCTP_CID_ACTION_SKIP_ERR:
4400                 /* Generate an ERROR chunk as response. */
4401                 hdr = unk_chunk->chunk_hdr;
4402                 err_chunk = sctp_make_op_error(asoc, unk_chunk,
4403                                                SCTP_ERROR_UNKNOWN_CHUNK, hdr,
4404                                                SCTP_PAD4(ntohs(hdr->length)),
4405                                                0);
4406                 if (err_chunk) {
4407                         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
4408                                         SCTP_CHUNK(err_chunk));
4409                 }
4410                 /* Skip the chunk.  */
4411                 return SCTP_DISPOSITION_CONSUME;
4412         default:
4413                 break;
4414         }
4415 
4416         return SCTP_DISPOSITION_DISCARD;
4417 }
4418 
4419 /*
4420  * Discard the chunk.
4421  *
4422  * Section: 0.2, 5.2.3, 5.2.5, 5.2.6, 6.0, 8.4.6, 8.5.1c, 9.2
4423  * [Too numerous to mention...]
4424  * Verification Tag: No verification needed.
4425  * Inputs
4426  * (endpoint, asoc, chunk)
4427  *
4428  * Outputs
4429  * (asoc, reply_msg, msg_up, timers, counters)
4430  *
4431  * The return value is the disposition of the chunk.
4432  */
4433 enum sctp_disposition sctp_sf_discard_chunk(struct net *net,
4434                                             const struct sctp_endpoint *ep,
4435                                             const struct sctp_association *asoc,
4436                                             const union sctp_subtype type,
4437                                             void *arg,
4438                                             struct sctp_cmd_seq *commands)
4439 {
4440         struct sctp_chunk *chunk = arg;
4441 
4442         /* Make sure that the chunk has a valid length.
4443          * Since we don't know the chunk type, we use a general
4444          * chunkhdr structure to make a comparison.
4445          */
4446         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
4447                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4448                                                   commands);
4449 
4450         pr_debug("%s: chunk:%d is discarded\n", __func__, type.chunk);
4451 
4452         return SCTP_DISPOSITION_DISCARD;
4453 }
4454 
4455 /*
4456  * Discard the whole packet.
4457  *
4458  * Section: 8.4 2)
4459  *
4460  * 2) If the OOTB packet contains an ABORT chunk, the receiver MUST
4461  *    silently discard the OOTB packet and take no further action.
4462  *
4463  * Verification Tag: No verification necessary
4464  *
4465  * Inputs
4466  * (endpoint, asoc, chunk)
4467  *
4468  * Outputs
4469  * (asoc, reply_msg, msg_up, timers, counters)
4470  *
4471  * The return value is the disposition of the chunk.
4472  */
4473 enum sctp_disposition sctp_sf_pdiscard(struct net *net,
4474                                        const struct sctp_endpoint *ep,
4475                                        const struct sctp_association *asoc,
4476                                        const union sctp_subtype type,
4477                                        void *arg, struct sctp_cmd_seq *commands)
4478 {
4479         SCTP_INC_STATS(net, SCTP_MIB_IN_PKT_DISCARDS);
4480         sctp_add_cmd_sf(commands, SCTP_CMD_DISCARD_PACKET, SCTP_NULL());
4481 
4482         return SCTP_DISPOSITION_CONSUME;
4483 }
4484 
4485 
4486 /*
4487  * The other end is violating protocol.
4488  *
4489  * Section: Not specified
4490  * Verification Tag: Not specified
4491  * Inputs
4492  * (endpoint, asoc, chunk)
4493  *
4494  * Outputs
4495  * (asoc, reply_msg, msg_up, timers, counters)
4496  *
4497  * We simply tag the chunk as a violation.  The state machine will log
4498  * the violation and continue.
4499  */
4500 enum sctp_disposition sctp_sf_violation(struct net *net,
4501                                         const struct sctp_endpoint *ep,
4502                                         const struct sctp_association *asoc,
4503                                         const union sctp_subtype type,
4504                                         void *arg,
4505                                         struct sctp_cmd_seq *commands)
4506 {
4507         struct sctp_chunk *chunk = arg;
4508 
4509         /* Make sure that the chunk has a valid length. */
4510         if (!sctp_chunk_length_valid(chunk, sizeof(struct sctp_chunkhdr)))
4511                 return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
4512                                                   commands);
4513 
4514         return SCTP_DISPOSITION_VIOLATION;
4515 }
4516 
4517 /*
4518  * Common function to handle a protocol violation.
4519  */
4520 static enum sctp_disposition sctp_sf_abort_violation(
4521                                         struct net *net,
4522                                         const struct sctp_endpoint *ep,
4523                                         const struct sctp_association *asoc,
4524                                         void *arg,
4525                                         struct sctp_cmd_seq *commands,
4526                                         const __u8 *payload,
4527                                         const size_t paylen)
4528 {
4529         struct sctp_packet *packet = NULL;
4530         struct sctp_chunk *chunk =  arg;
4531         struct sctp_chunk *abort = NULL;
4532 
4533         /* SCTP-AUTH, Section 6.3:
4534          *    It should be noted that if the receiver wants to tear
4535          *    down an association in an authenticated way only, the
4536          *    handling of malformed packets should not result in
4537          *    tearing down the association.
4538          *
4539          * This means that if we only want to abort associations
4540          * in an authenticated way (i.e AUTH+ABORT), then we
4541          * can't destroy this association just because the packet
4542          * was malformed.
4543          */
4544         if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc))
4545                 goto discard;
4546 
4547         /* Make the abort chunk. */
4548         abort = sctp_make_abort_violation(asoc, chunk, payload, paylen);
4549         if (!abort)
4550                 goto nomem;
4551 
4552         if (asoc) {
4553                 /* Treat INIT-ACK as a special case during COOKIE-WAIT. */
4554                 if (chunk->chunk_hdr->type == SCTP_CID_INIT_ACK &&
4555                     !asoc->peer.i.init_tag) {
4556                         struct sctp_initack_chunk *initack;
4557 
4558                         initack = (struct sctp_initack_chunk *)chunk->chunk_hdr;
4559                         if (!sctp_chunk_length_valid(chunk, sizeof(*initack)))
4560                                 abort->chunk_hdr->flags |= SCTP_CHUNK_FLAG_T;
4561                         else {
4562                                 unsigned int inittag;
4563 
4564                                 inittag = ntohl(initack->init_hdr.init_tag);
4565                                 sctp_add_cmd_sf(commands, SCTP_CMD_UPDATE_INITTAG,
4566                                                 SCTP_U32(inittag));
4567                         }
4568                 }
4569 
4570                 sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
4571                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
4572 
4573                 if (asoc->state <= SCTP_STATE_COOKIE_ECHOED) {
4574                         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
4575                                         SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
4576                         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
4577                                         SCTP_ERROR(ECONNREFUSED));
4578                         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
4579                                         SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
4580                 } else {
4581                         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
4582                                         SCTP_ERROR(ECONNABORTED));
4583                         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
4584                                         SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
4585                         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
4586                 }
4587         } else {
4588                 packet = sctp_ootb_pkt_new(net, asoc, chunk);
4589 
4590                 if (!packet)
4591                         goto nomem_pkt;
4592 
4593                 if (sctp_test_T_bit(abort))
4594                         packet->vtag = ntohl(chunk->sctp_hdr->vtag);
4595 
4596                 abort->skb->sk = ep->base.sk;
4597 
4598                 sctp_packet_append_chunk(packet, abort);
4599 
4600                 sctp_add_cmd_sf(commands, SCTP_CMD_SEND_PKT,
4601                         SCTP_PACKET(packet));
4602 
4603                 SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
4604         }
4605 
4606         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
4607 
4608 discard:
4609         sctp_sf_pdiscard(net, ep, asoc, SCTP_ST_CHUNK(0), arg, commands);
4610         return SCTP_DISPOSITION_ABORT;
4611 
4612 nomem_pkt:
4613         sctp_chunk_free(abort);
4614 nomem:
4615         return SCTP_DISPOSITION_NOMEM;
4616 }
4617 
4618 /*
4619  * Handle a protocol violation when the chunk length is invalid.
4620  * "Invalid" length is identified as smaller than the minimal length a
4621  * given chunk can be.  For example, a SACK chunk has invalid length
4622  * if its length is set to be smaller than the size of struct sctp_sack_chunk.
4623  *
4624  * We inform the other end by sending an ABORT with a Protocol Violation
4625  * error code.
4626  *
4627  * Section: Not specified
4628  * Verification Tag:  Nothing to do
4629  * Inputs
4630  * (endpoint, asoc, chunk)
4631  *
4632  * Outputs
4633  * (reply_msg, msg_up, counters)
4634  *
4635  * Generate an  ABORT chunk and terminate the association.
4636  */
4637 static enum sctp_disposition sctp_sf_violation_chunklen(
4638                                         struct net *net,
4639                                         const struct sctp_endpoint *ep,
4640                                         const struct sctp_association *asoc,
4641                                         const union sctp_subtype type,
4642                                         void *arg,
4643                                         struct sctp_cmd_seq *commands)
4644 {
4645         static const char err_str[] = "The following chunk had invalid length:";
4646 
4647         return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str,
4648                                        sizeof(err_str));
4649 }
4650 
4651 /*
4652  * Handle a protocol violation when the parameter length is invalid.
4653  * If the length is smaller than the minimum length of a given parameter,
4654  * or accumulated length in multi parameters exceeds the end of the chunk,
4655  * the length is considered as invalid.
4656  */
4657 static enum sctp_disposition sctp_sf_violation_paramlen(
4658                                         struct net *net,
4659                                         const struct sctp_endpoint *ep,
4660                                         const struct sctp_association *asoc,
4661                                         const union sctp_subtype type,
4662                                         void *arg, void *ext,
4663                                         struct sctp_cmd_seq *commands)
4664 {
4665         struct sctp_paramhdr *param = ext;
4666         struct sctp_chunk *abort = NULL;
4667         struct sctp_chunk *chunk = arg;
4668 
4669         if (sctp_auth_recv_cid(SCTP_CID_ABORT, asoc))
4670                 goto discard;
4671 
4672         /* Make the abort chunk. */
4673         abort = sctp_make_violation_paramlen(asoc, chunk, param);
4674         if (!abort)
4675                 goto nomem;
4676 
4677         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
4678         SCTP_INC_STATS(net, SCTP_MIB_OUTCTRLCHUNKS);
4679 
4680         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
4681                         SCTP_ERROR(ECONNABORTED));
4682         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
4683                         SCTP_PERR(SCTP_ERROR_PROTO_VIOLATION));
4684         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
4685         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
4686 
4687 discard:
4688         sctp_sf_pdiscard(net, ep, asoc, SCTP_ST_CHUNK(0), arg, commands);
4689         return SCTP_DISPOSITION_ABORT;
4690 nomem:
4691         return SCTP_DISPOSITION_NOMEM;
4692 }
4693 
4694 /* Handle a protocol violation when the peer trying to advance the
4695  * cumulative tsn ack to a point beyond the max tsn currently sent.
4696  *
4697  * We inform the other end by sending an ABORT with a Protocol Violation
4698  * error code.
4699  */
4700 static enum sctp_disposition sctp_sf_violation_ctsn(
4701                                         struct net *net,
4702                                         const struct sctp_endpoint *ep,
4703                                         const struct sctp_association *asoc,
4704                                         const union sctp_subtype type,
4705                                         void *arg,
4706                                         struct sctp_cmd_seq *commands)
4707 {
4708         static const char err_str[] = "The cumulative tsn ack beyond the max tsn currently sent:";
4709 
4710         return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str,
4711                                        sizeof(err_str));
4712 }
4713 
4714 /* Handle protocol violation of an invalid chunk bundling.  For example,
4715  * when we have an association and we receive bundled INIT-ACK, or
4716  * SHUDOWN-COMPLETE, our peer is clearly violationg the "MUST NOT bundle"
4717  * statement from the specs.  Additionally, there might be an attacker
4718  * on the path and we may not want to continue this communication.
4719  */
4720 static enum sctp_disposition sctp_sf_violation_chunk(
4721                                         struct net *net,
4722                                         const struct sctp_endpoint *ep,
4723                                         const struct sctp_association *asoc,
4724                                         const union sctp_subtype type,
4725                                         void *arg,
4726                                         struct sctp_cmd_seq *commands)
4727 {
4728         static const char err_str[] = "The following chunk violates protocol:";
4729 
4730         if (!asoc)
4731                 return sctp_sf_violation(net, ep, asoc, type, arg, commands);
4732 
4733         return sctp_sf_abort_violation(net, ep, asoc, arg, commands, err_str,
4734                                        sizeof(err_str));
4735 }
4736 /***************************************************************************
4737  * These are the state functions for handling primitive (Section 10) events.
4738  ***************************************************************************/
4739 /*
4740  * sctp_sf_do_prm_asoc
4741  *
4742  * Section: 10.1 ULP-to-SCTP
4743  * B) Associate
4744  *
4745  * Format: ASSOCIATE(local SCTP instance name, destination transport addr,
4746  * outbound stream count)
4747  * -> association id [,destination transport addr list] [,outbound stream
4748  * count]
4749  *
4750  * This primitive allows the upper layer to initiate an association to a
4751  * specific peer endpoint.
4752  *
4753  * The peer endpoint shall be specified by one of the transport addresses
4754  * which defines the endpoint (see Section 1.4).  If the local SCTP
4755  * instance has not been initialized, the ASSOCIATE is considered an
4756  * error.
4757  * [This is not relevant for the kernel implementation since we do all
4758  * initialization at boot time.  It we hadn't initialized we wouldn't
4759  * get anywhere near this code.]
4760  *
4761  * An association id, which is a local handle to the SCTP association,
4762  * will be returned on successful establishment of the association. If
4763  * SCTP is not able to open an SCTP association with the peer endpoint,
4764  * an error is returned.
4765  * [In the kernel implementation, the struct sctp_association needs to
4766  * be created BEFORE causing this primitive to run.]
4767  *
4768  * Other association parameters may be returned, including the
4769  * complete destination transport addresses of the peer as well as the
4770  * outbound stream count of the local endpoint. One of the transport
4771  * address from the returned destination addresses will be selected by
4772  * the local endpoint as default primary path for sending SCTP packets
4773  * to this peer.  The returned "destination transport addr list" can
4774  * be used by the ULP to change the default primary path or to force
4775  * sending a packet to a specific transport address.  [All of this
4776  * stuff happens when the INIT ACK arrives.  This is a NON-BLOCKING
4777  * function.]
4778  *
4779  * Mandatory attributes:
4780  *
4781  * o local SCTP instance name - obtained from the INITIALIZE operation.
4782  *   [This is the argument asoc.]
4783  * o destination transport addr - specified as one of the transport
4784  * addresses of the peer endpoint with which the association is to be
4785  * established.
4786  *  [This is asoc->peer.active_path.]
4787  * o outbound stream count - the number of outbound streams the ULP
4788  * would like to open towards this peer endpoint.
4789  * [BUG: This is not currently implemented.]
4790  * Optional attributes:
4791  *
4792  * None.
4793  *
4794  * The return value is a disposition.
4795  */
4796 enum sctp_disposition sctp_sf_do_prm_asoc(struct net *net,
4797                                           const struct sctp_endpoint *ep,
4798                                           const struct sctp_association *asoc,
4799                                           const union sctp_subtype type,
4800                                           void *arg,
4801                                           struct sctp_cmd_seq *commands)
4802 {
4803         struct sctp_association *my_asoc;
4804         struct sctp_chunk *repl;
4805 
4806         /* The comment below says that we enter COOKIE-WAIT AFTER
4807          * sending the INIT, but that doesn't actually work in our
4808          * implementation...
4809          */
4810         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
4811                         SCTP_STATE(SCTP_STATE_COOKIE_WAIT));
4812 
4813         /* RFC 2960 5.1 Normal Establishment of an Association
4814          *
4815          * A) "A" first sends an INIT chunk to "Z".  In the INIT, "A"
4816          * must provide its Verification Tag (Tag_A) in the Initiate
4817          * Tag field.  Tag_A SHOULD be a random number in the range of
4818          * 1 to 4294967295 (see 5.3.1 for Tag value selection). ...
4819          */
4820 
4821         repl = sctp_make_init(asoc, &asoc->base.bind_addr, GFP_ATOMIC, 0);
4822         if (!repl)
4823                 goto nomem;
4824 
4825         /* Choose transport for INIT. */
4826         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT,
4827                         SCTP_CHUNK(repl));
4828 
4829         /* Cast away the const modifier, as we want to just
4830          * rerun it through as a sideffect.
4831          */
4832         my_asoc = (struct sctp_association *)asoc;
4833         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(my_asoc));
4834 
4835         /* After sending the INIT, "A" starts the T1-init timer and
4836          * enters the COOKIE-WAIT state.
4837          */
4838         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
4839                         SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
4840         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
4841         return SCTP_DISPOSITION_CONSUME;
4842 
4843 nomem:
4844         return SCTP_DISPOSITION_NOMEM;
4845 }
4846 
4847 /*
4848  * Process the SEND primitive.
4849  *
4850  * Section: 10.1 ULP-to-SCTP
4851  * E) Send
4852  *
4853  * Format: SEND(association id, buffer address, byte count [,context]
4854  *         [,stream id] [,life time] [,destination transport address]
4855  *         [,unorder flag] [,no-bundle flag] [,payload protocol-id] )
4856  * -> result
4857  *
4858  * This is the main method to send user data via SCTP.
4859  *
4860  * Mandatory attributes:
4861  *
4862  *  o association id - local handle to the SCTP association
4863  *
4864  *  o buffer address - the location where the user message to be
4865  *    transmitted is stored;
4866  *
4867  *  o byte count - The size of the user data in number of bytes;
4868  *
4869  * Optional attributes:
4870  *
4871  *  o context - an optional 32 bit integer that will be carried in the
4872  *    sending failure notification to the ULP if the transportation of
4873  *    this User Message fails.
4874  *
4875  *  o stream id - to indicate which stream to send the data on. If not
4876  *    specified, stream 0 will be used.
4877  *
4878  *  o life time - specifies the life time of the user data. The user data
4879  *    will not be sent by SCTP after the life time expires. This
4880  *    parameter can be used to avoid efforts to transmit stale
4881  *    user messages. SCTP notifies the ULP if the data cannot be
4882  *    initiated to transport (i.e. sent to the destination via SCTP's
4883  *    send primitive) within the life time variable. However, the
4884  *    user data will be transmitted if SCTP has attempted to transmit a
4885  *    chunk before the life time expired.
4886  *
4887  *  o destination transport address - specified as one of the destination
4888  *    transport addresses of the peer endpoint to which this packet
4889  *    should be sent. Whenever possible, SCTP should use this destination
4890  *    transport address for sending the packets, instead of the current
4891  *    primary path.
4892  *
4893  *  o unorder flag - this flag, if present, indicates that the user
4894  *    would like the data delivered in an unordered fashion to the peer
4895  *    (i.e., the U flag is set to 1 on all DATA chunks carrying this
4896  *    message).
4897  *
4898  *  o no-bundle flag - instructs SCTP not to bundle this user data with
4899  *    other outbound DATA chunks. SCTP MAY still bundle even when
4900  *    this flag is present, when faced with network congestion.
4901  *
4902  *  o payload protocol-id - A 32 bit unsigned integer that is to be
4903  *    passed to the peer indicating the type of payload protocol data
4904  *    being transmitted. This value is passed as opaque data by SCTP.
4905  *
4906  * The return value is the disposition.
4907  */
4908 enum sctp_disposition sctp_sf_do_prm_send(struct net *net,
4909                                           const struct sctp_endpoint *ep,
4910                                           const struct sctp_association *asoc,
4911                                           const union sctp_subtype type,
4912                                           void *arg,
4913                                           struct sctp_cmd_seq *commands)
4914 {
4915         struct sctp_datamsg *msg = arg;
4916 
4917         sctp_add_cmd_sf(commands, SCTP_CMD_SEND_MSG, SCTP_DATAMSG(msg));
4918         return SCTP_DISPOSITION_CONSUME;
4919 }
4920 
4921 /*
4922  * Process the SHUTDOWN primitive.
4923  *
4924  * Section: 10.1:
4925  * C) Shutdown
4926  *
4927  * Format: SHUTDOWN(association id)
4928  * -> result
4929  *
4930  * Gracefully closes an association. Any locally queued user data
4931  * will be delivered to the peer. The association will be terminated only
4932  * after the peer acknowledges all the SCTP packets sent.  A success code
4933  * will be returned on successful termination of the association. If
4934  * attempting to terminate the association results in a failure, an error
4935  * code shall be returned.
4936  *
4937  * Mandatory attributes:
4938  *
4939  *  o association id - local handle to the SCTP association
4940  *
4941  * Optional attributes:
4942  *
4943  * None.
4944  *
4945  * The return value is the disposition.
4946  */
4947 enum sctp_disposition sctp_sf_do_9_2_prm_shutdown(
4948                                         struct net *net,
4949                                         const struct sctp_endpoint *ep,
4950                                         const struct sctp_association *asoc,
4951                                         const union sctp_subtype type,
4952                                         void *arg,
4953                                         struct sctp_cmd_seq *commands)
4954 {
4955         enum sctp_disposition disposition;
4956 
4957         /* From 9.2 Shutdown of an Association
4958          * Upon receipt of the SHUTDOWN primitive from its upper
4959          * layer, the endpoint enters SHUTDOWN-PENDING state and
4960          * remains there until all outstanding data has been
4961          * acknowledged by its peer. The endpoint accepts no new data
4962          * from its upper layer, but retransmits data to the far end
4963          * if necessary to fill gaps.
4964          */
4965         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
4966                         SCTP_STATE(SCTP_STATE_SHUTDOWN_PENDING));
4967 
4968         disposition = SCTP_DISPOSITION_CONSUME;
4969         if (sctp_outq_is_empty(&asoc->outqueue)) {
4970                 disposition = sctp_sf_do_9_2_start_shutdown(net, ep, asoc, type,
4971                                                             arg, commands);
4972         }
4973 
4974         return disposition;
4975 }
4976 
4977 /*
4978  * Process the ABORT primitive.
4979  *
4980  * Section: 10.1:
4981  * C) Abort
4982  *
4983  * Format: Abort(association id [, cause code])
4984  * -> result
4985  *
4986  * Ungracefully closes an association. Any locally queued user data
4987  * will be discarded and an ABORT chunk is sent to the peer.  A success code
4988  * will be returned on successful abortion of the association. If
4989  * attempting to abort the association results in a failure, an error
4990  * code shall be returned.
4991  *
4992  * Mandatory attributes:
4993  *
4994  *  o association id - local handle to the SCTP association
4995  *
4996  * Optional attributes:
4997  *
4998  *  o cause code - reason of the abort to be passed to the peer
4999  *
5000  * None.
5001  *
5002  * The return value is the disposition.
5003  */
5004 enum sctp_disposition sctp_sf_do_9_1_prm_abort(
5005                                         struct net *net,
5006                                         const struct sctp_endpoint *ep,
5007                                         const struct sctp_association *asoc,
5008                                         const union sctp_subtype type,
5009                                         void *arg,
5010                                         struct sctp_cmd_seq *commands)
5011 {
5012         /* From 9.1 Abort of an Association
5013          * Upon receipt of the ABORT primitive from its upper
5014          * layer, the endpoint enters CLOSED state and
5015          * discard all outstanding data has been
5016          * acknowledged by its peer. The endpoint accepts no new data
5017          * from its upper layer, but retransmits data to the far end
5018          * if necessary to fill gaps.
5019          */
5020         struct sctp_chunk *abort = arg;
5021 
5022         if (abort)
5023                 sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
5024 
5025         /* Even if we can't send the ABORT due to low memory delete the
5026          * TCB.  This is a departure from our typical NOMEM handling.
5027          */
5028 
5029         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5030                         SCTP_ERROR(ECONNABORTED));
5031         /* Delete the established association. */
5032         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
5033                         SCTP_PERR(SCTP_ERROR_USER_ABORT));
5034 
5035         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
5036         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
5037 
5038         return SCTP_DISPOSITION_ABORT;
5039 }
5040 
5041 /* We tried an illegal operation on an association which is closed.  */
5042 enum sctp_disposition sctp_sf_error_closed(struct net *net,
5043                                            const struct sctp_endpoint *ep,
5044                                            const struct sctp_association *asoc,
5045                                            const union sctp_subtype type,
5046                                            void *arg,
5047                                            struct sctp_cmd_seq *commands)
5048 {
5049         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_ERROR, SCTP_ERROR(-EINVAL));
5050         return SCTP_DISPOSITION_CONSUME;
5051 }
5052 
5053 /* We tried an illegal operation on an association which is shutting
5054  * down.
5055  */
5056 enum sctp_disposition sctp_sf_error_shutdown(
5057                                         struct net *net,
5058                                         const struct sctp_endpoint *ep,
5059                                         const struct sctp_association *asoc,
5060                                         const union sctp_subtype type,
5061                                         void *arg,
5062                                         struct sctp_cmd_seq *commands)
5063 {
5064         sctp_add_cmd_sf(commands, SCTP_CMD_REPORT_ERROR,
5065                         SCTP_ERROR(-ESHUTDOWN));
5066         return SCTP_DISPOSITION_CONSUME;
5067 }
5068 
5069 /*
5070  * sctp_cookie_wait_prm_shutdown
5071  *
5072  * Section: 4 Note: 2
5073  * Verification Tag:
5074  * Inputs
5075  * (endpoint, asoc)
5076  *
5077  * The RFC does not explicitly address this issue, but is the route through the
5078  * state table when someone issues a shutdown while in COOKIE_WAIT state.
5079  *
5080  * Outputs
5081  * (timers)
5082  */
5083 enum sctp_disposition sctp_sf_cookie_wait_prm_shutdown(
5084                                         struct net *net,
5085                                         const struct sctp_endpoint *ep,
5086                                         const struct sctp_association *asoc,
5087                                         const union sctp_subtype type,
5088                                         void *arg,
5089                                         struct sctp_cmd_seq *commands)
5090 {
5091         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5092                         SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
5093 
5094         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
5095                         SCTP_STATE(SCTP_STATE_CLOSED));
5096 
5097         SCTP_INC_STATS(net, SCTP_MIB_SHUTDOWNS);
5098 
5099         sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
5100 
5101         return SCTP_DISPOSITION_DELETE_TCB;
5102 }
5103 
5104 /*
5105  * sctp_cookie_echoed_prm_shutdown
5106  *
5107  * Section: 4 Note: 2
5108  * Verification Tag:
5109  * Inputs
5110  * (endpoint, asoc)
5111  *
5112  * The RFC does not explcitly address this issue, but is the route through the
5113  * state table when someone issues a shutdown while in COOKIE_ECHOED state.
5114  *
5115  * Outputs
5116  * (timers)
5117  */
5118 enum sctp_disposition sctp_sf_cookie_echoed_prm_shutdown(
5119                                         struct net *net,
5120                                         const struct sctp_endpoint *ep,
5121                                         const struct sctp_association *asoc,
5122                                         const union sctp_subtype type,
5123                                         void *arg,
5124                                         struct sctp_cmd_seq *commands)
5125 {
5126         /* There is a single T1 timer, so we should be able to use
5127          * common function with the COOKIE-WAIT state.
5128          */
5129         return sctp_sf_cookie_wait_prm_shutdown(net, ep, asoc, type, arg, commands);
5130 }
5131 
5132 /*
5133  * sctp_sf_cookie_wait_prm_abort
5134  *
5135  * Section: 4 Note: 2
5136  * Verification Tag:
5137  * Inputs
5138  * (endpoint, asoc)
5139  *
5140  * The RFC does not explicitly address this issue, but is the route through the
5141  * state table when someone issues an abort while in COOKIE_WAIT state.
5142  *
5143  * Outputs
5144  * (timers)
5145  */
5146 enum sctp_disposition sctp_sf_cookie_wait_prm_abort(
5147                                         struct net *net,
5148                                         const struct sctp_endpoint *ep,
5149                                         const struct sctp_association *asoc,
5150                                         const union sctp_subtype type,
5151                                         void *arg,
5152                                         struct sctp_cmd_seq *commands)
5153 {
5154         struct sctp_chunk *abort = arg;
5155 
5156         /* Stop T1-init timer */
5157         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5158                         SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
5159 
5160         if (abort)
5161                 sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(abort));
5162 
5163         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
5164                         SCTP_STATE(SCTP_STATE_CLOSED));
5165 
5166         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
5167 
5168         /* Even if we can't send the ABORT due to low memory delete the
5169          * TCB.  This is a departure from our typical NOMEM handling.
5170          */
5171 
5172         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5173                         SCTP_ERROR(ECONNREFUSED));
5174         /* Delete the established association. */
5175         sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
5176                         SCTP_PERR(SCTP_ERROR_USER_ABORT));
5177 
5178         return SCTP_DISPOSITION_ABORT;
5179 }
5180 
5181 /*
5182  * sctp_sf_cookie_echoed_prm_abort
5183  *
5184  * Section: 4 Note: 3
5185  * Verification Tag:
5186  * Inputs
5187  * (endpoint, asoc)
5188  *
5189  * The RFC does not explcitly address this issue, but is the route through the
5190  * state table when someone issues an abort while in COOKIE_ECHOED state.
5191  *
5192  * Outputs
5193  * (timers)
5194  */
5195 enum sctp_disposition sctp_sf_cookie_echoed_prm_abort(
5196                                         struct net *net,
5197                                         const struct sctp_endpoint *ep,
5198                                         const struct sctp_association *asoc,
5199                                         const union sctp_subtype type,
5200                                         void *arg,
5201                                         struct sctp_cmd_seq *commands)
5202 {
5203         /* There is a single T1 timer, so we should be able to use
5204          * common function with the COOKIE-WAIT state.
5205          */
5206         return sctp_sf_cookie_wait_prm_abort(net, ep, asoc, type, arg, commands);
5207 }
5208 
5209 /*
5210  * sctp_sf_shutdown_pending_prm_abort
5211  *
5212  * Inputs
5213  * (endpoint, asoc)
5214  *
5215  * The RFC does not explicitly address this issue, but is the route through the
5216  * state table when someone issues an abort while in SHUTDOWN-PENDING state.
5217  *
5218  * Outputs
5219  * (timers)
5220  */
5221 enum sctp_disposition sctp_sf_shutdown_pending_prm_abort(
5222                                         struct net *net,
5223                                         const struct sctp_endpoint *ep,
5224                                         const struct sctp_association *asoc,
5225                                         const union sctp_subtype type,
5226                                         void *arg,
5227                                         struct sctp_cmd_seq *commands)
5228 {
5229         /* Stop the T5-shutdown guard timer.  */
5230         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5231                         SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
5232 
5233         return sctp_sf_do_9_1_prm_abort(net, ep, asoc, type, arg, commands);
5234 }
5235 
5236 /*
5237  * sctp_sf_shutdown_sent_prm_abort
5238  *
5239  * Inputs
5240  * (endpoint, asoc)
5241  *
5242  * The RFC does not explicitly address this issue, but is the route through the
5243  * state table when someone issues an abort while in SHUTDOWN-SENT state.
5244  *
5245  * Outputs
5246  * (timers)
5247  */
5248 enum sctp_disposition sctp_sf_shutdown_sent_prm_abort(
5249                                         struct net *net,
5250                                         const struct sctp_endpoint *ep,
5251                                         const struct sctp_association *asoc,
5252                                         const union sctp_subtype type,
5253                                         void *arg,
5254                                         struct sctp_cmd_seq *commands)
5255 {
5256         /* Stop the T2-shutdown timer.  */
5257         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5258                         SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
5259 
5260         /* Stop the T5-shutdown guard timer.  */
5261         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5262                         SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
5263 
5264         return sctp_sf_do_9_1_prm_abort(net, ep, asoc, type, arg, commands);
5265 }
5266 
5267 /*
5268  * sctp_sf_cookie_echoed_prm_abort
5269  *
5270  * Inputs
5271  * (endpoint, asoc)
5272  *
5273  * The RFC does not explcitly address this issue, but is the route through the
5274  * state table when someone issues an abort while in COOKIE_ECHOED state.
5275  *
5276  * Outputs
5277  * (timers)
5278  */
5279 enum sctp_disposition sctp_sf_shutdown_ack_sent_prm_abort(
5280                                         struct net *net,
5281                                         const struct sctp_endpoint *ep,
5282                                         const struct sctp_association *asoc,
5283                                         const union sctp_subtype type,
5284                                         void *arg,
5285                                         struct sctp_cmd_seq *commands)
5286 {
5287         /* The same T2 timer, so we should be able to use
5288          * common function with the SHUTDOWN-SENT state.
5289          */
5290         return sctp_sf_shutdown_sent_prm_abort(net, ep, asoc, type, arg, commands);
5291 }
5292 
5293 /*
5294  * Process the REQUESTHEARTBEAT primitive
5295  *
5296  * 10.1 ULP-to-SCTP
5297  * J) Request Heartbeat
5298  *
5299  * Format: REQUESTHEARTBEAT(association id, destination transport address)
5300  *
5301  * -> result
5302  *
5303  * Instructs the local endpoint to perform a HeartBeat on the specified
5304  * destination transport address of the given association. The returned
5305  * result should indicate whether the transmission of the HEARTBEAT
5306  * chunk to the destination address is successful.
5307  *
5308  * Mandatory attributes:
5309  *
5310  * o association id - local handle to the SCTP association
5311  *
5312  * o destination transport address - the transport address of the
5313  *   association on which a heartbeat should be issued.
5314  */
5315 enum sctp_disposition sctp_sf_do_prm_requestheartbeat(
5316                                         struct net *net,
5317                                         const struct sctp_endpoint *ep,
5318                                         const struct sctp_association *asoc,
5319                                         const union sctp_subtype type,
5320                                         void *arg,
5321                                         struct sctp_cmd_seq *commands)
5322 {
5323         if (SCTP_DISPOSITION_NOMEM == sctp_sf_heartbeat(ep, asoc, type,
5324                                       (struct sctp_transport *)arg, commands))
5325                 return SCTP_DISPOSITION_NOMEM;
5326 
5327         /*
5328          * RFC 2960 (bis), section 8.3
5329          *
5330          *    D) Request an on-demand HEARTBEAT on a specific destination
5331          *    transport address of a given association.
5332          *
5333          *    The endpoint should increment the respective error  counter of
5334          *    the destination transport address each time a HEARTBEAT is sent
5335          *    to that address and not acknowledged within one RTO.
5336          *
5337          */
5338         sctp_add_cmd_sf(commands, SCTP_CMD_TRANSPORT_HB_SENT,
5339                         SCTP_TRANSPORT(arg));
5340         return SCTP_DISPOSITION_CONSUME;
5341 }
5342 
5343 /*
5344  * ADDIP Section 4.1 ASCONF Chunk Procedures
5345  * When an endpoint has an ASCONF signaled change to be sent to the
5346  * remote endpoint it should do A1 to A9
5347  */
5348 enum sctp_disposition sctp_sf_do_prm_asconf(struct net *net,
5349                                             const struct sctp_endpoint *ep,
5350                                             const struct sctp_association *asoc,
5351                                             const union sctp_subtype type,
5352                                             void *arg,
5353                                             struct sctp_cmd_seq *commands)
5354 {
5355         struct sctp_chunk *chunk = arg;
5356 
5357         sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T4, SCTP_CHUNK(chunk));
5358         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
5359                         SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
5360         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(chunk));
5361         return SCTP_DISPOSITION_CONSUME;
5362 }
5363 
5364 /* RE-CONFIG Section 5.1 RECONF Chunk Procedures */
5365 enum sctp_disposition sctp_sf_do_prm_reconf(struct net *net,
5366                                             const struct sctp_endpoint *ep,
5367                                             const struct sctp_association *asoc,
5368                                             const union sctp_subtype type,
5369                                             void *arg,
5370                                             struct sctp_cmd_seq *commands)
5371 {
5372         struct sctp_chunk *chunk = arg;
5373 
5374         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(chunk));
5375         return SCTP_DISPOSITION_CONSUME;
5376 }
5377 
5378 /*
5379  * Ignore the primitive event
5380  *
5381  * The return value is the disposition of the primitive.
5382  */
5383 enum sctp_disposition sctp_sf_ignore_primitive(
5384                                         struct net *net,
5385                                         const struct sctp_endpoint *ep,
5386                                         const struct sctp_association *asoc,
5387                                         const union sctp_subtype type,
5388                                         void *arg,
5389                                         struct sctp_cmd_seq *commands)
5390 {
5391         pr_debug("%s: primitive type:%d is ignored\n", __func__,
5392                  type.primitive);
5393 
5394         return SCTP_DISPOSITION_DISCARD;
5395 }
5396 
5397 /***************************************************************************
5398  * These are the state functions for the OTHER events.
5399  ***************************************************************************/
5400 
5401 /*
5402  * When the SCTP stack has no more user data to send or retransmit, this
5403  * notification is given to the user. Also, at the time when a user app
5404  * subscribes to this event, if there is no data to be sent or
5405  * retransmit, the stack will immediately send up this notification.
5406  */
5407 enum sctp_disposition sctp_sf_do_no_pending_tsn(
5408                                         struct net *net,
5409                                         const struct sctp_endpoint *ep,
5410                                         const struct sctp_association *asoc,
5411                                         const union sctp_subtype type,
5412                                         void *arg,
5413                                         struct sctp_cmd_seq *commands)
5414 {
5415         struct sctp_ulpevent *event;
5416 
5417         event = sctp_ulpevent_make_sender_dry_event(asoc, GFP_ATOMIC);
5418         if (!event)
5419                 return SCTP_DISPOSITION_NOMEM;
5420 
5421         sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP, SCTP_ULPEVENT(event));
5422 
5423         return SCTP_DISPOSITION_CONSUME;
5424 }
5425 
5426 /*
5427  * Start the shutdown negotiation.
5428  *
5429  * From Section 9.2:
5430  * Once all its outstanding data has been acknowledged, the endpoint
5431  * shall send a SHUTDOWN chunk to its peer including in the Cumulative
5432  * TSN Ack field the last sequential TSN it has received from the peer.
5433  * It shall then start the T2-shutdown timer and enter the SHUTDOWN-SENT
5434  * state. If the timer expires, the endpoint must re-send the SHUTDOWN
5435  * with the updated last sequential TSN received from its peer.
5436  *
5437  * The return value is the disposition.
5438  */
5439 enum sctp_disposition sctp_sf_do_9_2_start_shutdown(
5440                                         struct net *net,
5441                                         const struct sctp_endpoint *ep,
5442                                         const struct sctp_association *asoc,
5443                                         const union sctp_subtype type,
5444                                         void *arg,
5445                                         struct sctp_cmd_seq *commands)
5446 {
5447         struct sctp_chunk *reply;
5448 
5449         /* Once all its outstanding data has been acknowledged, the
5450          * endpoint shall send a SHUTDOWN chunk to its peer including
5451          * in the Cumulative TSN Ack field the last sequential TSN it
5452          * has received from the peer.
5453          */
5454         reply = sctp_make_shutdown(asoc, NULL);
5455         if (!reply)
5456                 goto nomem;
5457 
5458         /* Set the transport for the SHUTDOWN chunk and the timeout for the
5459          * T2-shutdown timer.
5460          */
5461         sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
5462 
5463         /* It shall then start the T2-shutdown timer */
5464         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START,
5465                         SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
5466 
5467         /* RFC 4960 Section 9.2
5468          * The sender of the SHUTDOWN MAY also start an overall guard timer
5469          * 'T5-shutdown-guard' to bound the overall time for shutdown sequence.
5470          */
5471         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
5472                         SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
5473 
5474         if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
5475                 sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5476                                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
5477 
5478         /* and enter the SHUTDOWN-SENT state.  */
5479         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
5480                         SCTP_STATE(SCTP_STATE_SHUTDOWN_SENT));
5481 
5482         /* sctp-implguide 2.10 Issues with Heartbeating and failover
5483          *
5484          * HEARTBEAT ... is discontinued after sending either SHUTDOWN
5485          * or SHUTDOWN-ACK.
5486          */
5487         sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL());
5488 
5489         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
5490 
5491         return SCTP_DISPOSITION_CONSUME;
5492 
5493 nomem:
5494         return SCTP_DISPOSITION_NOMEM;
5495 }
5496 
5497 /*
5498  * Generate a SHUTDOWN ACK now that everything is SACK'd.
5499  *
5500  * From Section 9.2:
5501  *
5502  * If it has no more outstanding DATA chunks, the SHUTDOWN receiver
5503  * shall send a SHUTDOWN ACK and start a T2-shutdown timer of its own,
5504  * entering the SHUTDOWN-ACK-SENT state. If the timer expires, the
5505  * endpoint must re-send the SHUTDOWN ACK.
5506  *
5507  * The return value is the disposition.
5508  */
5509 enum sctp_disposition sctp_sf_do_9_2_shutdown_ack(
5510                                         struct net *net,
5511                                         const struct sctp_endpoint *ep,
5512                                         const struct sctp_association *asoc,
5513                                         const union sctp_subtype type,
5514                                         void *arg,
5515                                         struct sctp_cmd_seq *commands)
5516 {
5517         struct sctp_chunk *chunk = arg;
5518         struct sctp_chunk *reply;
5519 
5520         /* There are 2 ways of getting here:
5521          *    1) called in response to a SHUTDOWN chunk
5522          *    2) called when SCTP_EVENT_NO_PENDING_TSN event is issued.
5523          *
5524          * For the case (2), the arg parameter is set to NULL.  We need
5525          * to check that we have a chunk before accessing it's fields.
5526          */
5527         if (chunk) {
5528                 if (!sctp_vtag_verify(chunk, asoc))
5529                         return sctp_sf_pdiscard(net, ep, asoc, type, arg,
5530                                                 commands);
5531 
5532                 /* Make sure that the SHUTDOWN chunk has a valid length. */
5533                 if (!sctp_chunk_length_valid(
5534                                 chunk, sizeof(struct sctp_shutdown_chunk)))
5535                         return sctp_sf_violation_chunklen(net, ep, asoc, type,
5536                                                           arg, commands);
5537         }
5538 
5539         /* If it has no more outstanding DATA chunks, the SHUTDOWN receiver
5540          * shall send a SHUTDOWN ACK ...
5541          */
5542         reply = sctp_make_shutdown_ack(asoc, chunk);
5543         if (!reply)
5544                 goto nomem;
5545 
5546         /* Set the transport for the SHUTDOWN ACK chunk and the timeout for
5547          * the T2-shutdown timer.
5548          */
5549         sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
5550 
5551         /* and start/restart a T2-shutdown timer of its own, */
5552         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
5553                         SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
5554 
5555         if (asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE])
5556                 sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
5557                                 SCTP_TO(SCTP_EVENT_TIMEOUT_AUTOCLOSE));
5558 
5559         /* Enter the SHUTDOWN-ACK-SENT state.  */
5560         sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
5561                         SCTP_STATE(SCTP_STATE_SHUTDOWN_ACK_SENT));
5562 
5563         /* sctp-implguide 2.10 Issues with Heartbeating and failover
5564          *
5565          * HEARTBEAT ... is discontinued after sending either SHUTDOWN
5566          * or SHUTDOWN-ACK.
5567          */
5568         sctp_add_cmd_sf(commands, SCTP_CMD_HB_TIMERS_STOP, SCTP_NULL());
5569 
5570         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
5571 
5572         return SCTP_DISPOSITION_CONSUME;
5573 
5574 nomem:
5575         return SCTP_DISPOSITION_NOMEM;
5576 }
5577 
5578 /*
5579  * Ignore the event defined as other
5580  *
5581  * The return value is the disposition of the event.
5582  */
5583 enum sctp_disposition sctp_sf_ignore_other(struct net *net,
5584                                            const struct sctp_endpoint *ep,
5585                                            const struct sctp_association *asoc,
5586                                            const union sctp_subtype type,
5587                                            void *arg,
5588                                            struct sctp_cmd_seq *commands)
5589 {
5590         pr_debug("%s: the event other type:%d is ignored\n",
5591                  __func__, type.other);
5592 
5593         return SCTP_DISPOSITION_DISCARD;
5594 }
5595 
5596 /************************************************************
5597  * These are the state functions for handling timeout events.
5598  ************************************************************/
5599 
5600 /*
5601  * RTX Timeout
5602  *
5603  * Section: 6.3.3 Handle T3-rtx Expiration
5604  *
5605  * Whenever the retransmission timer T3-rtx expires for a destination
5606  * address, do the following:
5607  * [See below]
5608  *
5609  * The return value is the disposition of the chunk.
5610  */
5611 enum sctp_disposition sctp_sf_do_6_3_3_rtx(struct net *net,
5612                                            const struct sctp_endpoint *ep,
5613                                            const struct sctp_association *asoc,
5614                                            const union sctp_subtype type,
5615                                            void *arg,
5616                                            struct sctp_cmd_seq *commands)
5617 {
5618         struct sctp_transport *transport = arg;
5619 
5620         SCTP_INC_STATS(net, SCTP_MIB_T3_RTX_EXPIREDS);
5621 
5622         if (asoc->overall_error_count >= asoc->max_retrans) {
5623                 if (asoc->peer.zero_window_announced &&
5624                     asoc->state == SCTP_STATE_SHUTDOWN_PENDING) {
5625                         /*
5626                          * We are here likely because the receiver had its rwnd
5627                          * closed for a while and we have not been able to
5628                          * transmit the locally queued data within the maximum
5629                          * retransmission attempts limit.  Start the T5
5630                          * shutdown guard timer to give the receiver one last
5631                          * chance and some additional time to recover before
5632                          * aborting.
5633                          */
5634                         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_START_ONCE,
5635                                 SCTP_TO(SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD));
5636                 } else {
5637                         sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5638                                         SCTP_ERROR(ETIMEDOUT));
5639                         /* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */
5640                         sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
5641                                         SCTP_PERR(SCTP_ERROR_NO_ERROR));
5642                         SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
5643                         SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
5644                         return SCTP_DISPOSITION_DELETE_TCB;
5645                 }
5646         }
5647 
5648         /* E1) For the destination address for which the timer
5649          * expires, adjust its ssthresh with rules defined in Section
5650          * 7.2.3 and set the cwnd <- MTU.
5651          */
5652 
5653         /* E2) For the destination address for which the timer
5654          * expires, set RTO <- RTO * 2 ("back off the timer").  The
5655          * maximum value discussed in rule C7 above (RTO.max) may be
5656          * used to provide an upper bound to this doubling operation.
5657          */
5658 
5659         /* E3) Determine how many of the earliest (i.e., lowest TSN)
5660          * outstanding DATA chunks for the address for which the
5661          * T3-rtx has expired will fit into a single packet, subject
5662          * to the MTU constraint for the path corresponding to the
5663          * destination transport address to which the retransmission
5664          * is being sent (this may be different from the address for
5665          * which the timer expires [see Section 6.4]).  Call this
5666          * value K. Bundle and retransmit those K DATA chunks in a
5667          * single packet to the destination endpoint.
5668          *
5669          * Note: Any DATA chunks that were sent to the address for
5670          * which the T3-rtx timer expired but did not fit in one MTU
5671          * (rule E3 above), should be marked for retransmission and
5672          * sent as soon as cwnd allows (normally when a SACK arrives).
5673          */
5674 
5675         /* Do some failure management (Section 8.2). */
5676         sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE, SCTP_TRANSPORT(transport));
5677 
5678         /* NB: Rules E4 and F1 are implicit in R1.  */
5679         sctp_add_cmd_sf(commands, SCTP_CMD_RETRAN, SCTP_TRANSPORT(transport));
5680 
5681         return SCTP_DISPOSITION_CONSUME;
5682 }
5683 
5684 /*
5685  * Generate delayed SACK on timeout
5686  *
5687  * Section: 6.2  Acknowledgement on Reception of DATA Chunks
5688  *
5689  * The guidelines on delayed acknowledgement algorithm specified in
5690  * Section 4.2 of [RFC2581] SHOULD be followed.  Specifically, an
5691  * acknowledgement SHOULD be generated for at least every second packet
5692  * (not every second DATA chunk) received, and SHOULD be generated
5693  * within 200 ms of the arrival of any unacknowledged DATA chunk.  In
5694  * some situations it may be beneficial for an SCTP transmitter to be
5695  * more conservative than the algorithms detailed in this document
5696  * allow. However, an SCTP transmitter MUST NOT be more aggressive than
5697  * the following algorithms allow.
5698  */
5699 enum sctp_disposition sctp_sf_do_6_2_sack(struct net *net,
5700                                           const struct sctp_endpoint *ep,
5701                                           const struct sctp_association *asoc,
5702                                           const union sctp_subtype type,
5703                                           void *arg,
5704                                           struct sctp_cmd_seq *commands)
5705 {
5706         SCTP_INC_STATS(net, SCTP_MIB_DELAY_SACK_EXPIREDS);
5707         sctp_add_cmd_sf(commands, SCTP_CMD_GEN_SACK, SCTP_FORCE());
5708         return SCTP_DISPOSITION_CONSUME;
5709 }
5710 
5711 /*
5712  * sctp_sf_t1_init_timer_expire
5713  *
5714  * Section: 4 Note: 2
5715  * Verification Tag:
5716  * Inputs
5717  * (endpoint, asoc)
5718  *
5719  *  RFC 2960 Section 4 Notes
5720  *  2) If the T1-init timer expires, the endpoint MUST retransmit INIT
5721  *     and re-start the T1-init timer without changing state.  This MUST
5722  *     be repeated up to 'Max.Init.Retransmits' times.  After that, the
5723  *     endpoint MUST abort the initialization process and report the
5724  *     error to SCTP user.
5725  *
5726  * Outputs
5727  * (timers, events)
5728  *
5729  */
5730 enum sctp_disposition sctp_sf_t1_init_timer_expire(
5731                                         struct net *net,
5732                                         const struct sctp_endpoint *ep,
5733                                         const struct sctp_association *asoc,
5734                                         const union sctp_subtype type,
5735                                         void *arg,
5736                                         struct sctp_cmd_seq *commands)
5737 {
5738         int attempts = asoc->init_err_counter + 1;
5739         struct sctp_chunk *repl = NULL;
5740         struct sctp_bind_addr *bp;
5741 
5742         pr_debug("%s: timer T1 expired (INIT)\n", __func__);
5743 
5744         SCTP_INC_STATS(net, SCTP_MIB_T1_INIT_EXPIREDS);
5745 
5746         if (attempts <= asoc->max_init_attempts) {
5747                 bp = (struct sctp_bind_addr *) &asoc->base.bind_addr;
5748                 repl = sctp_make_init(asoc, bp, GFP_ATOMIC, 0);
5749                 if (!repl)
5750                         return SCTP_DISPOSITION_NOMEM;
5751 
5752                 /* Choose transport for INIT. */
5753                 sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT,
5754                                 SCTP_CHUNK(repl));
5755 
5756                 /* Issue a sideeffect to do the needed accounting. */
5757                 sctp_add_cmd_sf(commands, SCTP_CMD_INIT_RESTART,
5758                                 SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
5759 
5760                 sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
5761         } else {
5762                 pr_debug("%s: giving up on INIT, attempts:%d "
5763                          "max_init_attempts:%d\n", __func__, attempts,
5764                          asoc->max_init_attempts);
5765 
5766                 sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5767                                 SCTP_ERROR(ETIMEDOUT));
5768                 sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
5769                                 SCTP_PERR(SCTP_ERROR_NO_ERROR));
5770                 return SCTP_DISPOSITION_DELETE_TCB;
5771         }
5772 
5773         return SCTP_DISPOSITION_CONSUME;
5774 }
5775 
5776 /*
5777  * sctp_sf_t1_cookie_timer_expire
5778  *
5779  * Section: 4 Note: 2
5780  * Verification Tag:
5781  * Inputs
5782  * (endpoint, asoc)
5783  *
5784  *  RFC 2960 Section 4 Notes
5785  *  3) If the T1-cookie timer expires, the endpoint MUST retransmit
5786  *     COOKIE ECHO and re-start the T1-cookie timer without changing
5787  *     state.  This MUST be repeated up to 'Max.Init.Retransmits' times.
5788  *     After that, the endpoint MUST abort the initialization process and
5789  *     report the error to SCTP user.
5790  *
5791  * Outputs
5792  * (timers, events)
5793  *
5794  */
5795 enum sctp_disposition sctp_sf_t1_cookie_timer_expire(
5796                                         struct net *net,
5797                                         const struct sctp_endpoint *ep,
5798                                         const struct sctp_association *asoc,
5799                                         const union sctp_subtype type,
5800                                         void *arg,
5801                                         struct sctp_cmd_seq *commands)
5802 {
5803         int attempts = asoc->init_err_counter + 1;
5804         struct sctp_chunk *repl = NULL;
5805 
5806         pr_debug("%s: timer T1 expired (COOKIE-ECHO)\n", __func__);
5807 
5808         SCTP_INC_STATS(net, SCTP_MIB_T1_COOKIE_EXPIREDS);
5809 
5810         if (attempts <= asoc->max_init_attempts) {
5811                 repl = sctp_make_cookie_echo(asoc, NULL);
5812                 if (!repl)
5813                         return SCTP_DISPOSITION_NOMEM;
5814 
5815                 sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT,
5816                                 SCTP_CHUNK(repl));
5817                 /* Issue a sideeffect to do the needed accounting. */
5818                 sctp_add_cmd_sf(commands, SCTP_CMD_COOKIEECHO_RESTART,
5819                                 SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
5820 
5821                 sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(repl));
5822         } else {
5823                 sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5824                                 SCTP_ERROR(ETIMEDOUT));
5825                 sctp_add_cmd_sf(commands, SCTP_CMD_INIT_FAILED,
5826                                 SCTP_PERR(SCTP_ERROR_NO_ERROR));
5827                 return SCTP_DISPOSITION_DELETE_TCB;
5828         }
5829 
5830         return SCTP_DISPOSITION_CONSUME;
5831 }
5832 
5833 /* RFC2960 9.2 If the timer expires, the endpoint must re-send the SHUTDOWN
5834  * with the updated last sequential TSN received from its peer.
5835  *
5836  * An endpoint should limit the number of retransmissions of the
5837  * SHUTDOWN chunk to the protocol parameter 'Association.Max.Retrans'.
5838  * If this threshold is exceeded the endpoint should destroy the TCB and
5839  * MUST report the peer endpoint unreachable to the upper layer (and
5840  * thus the association enters the CLOSED state).  The reception of any
5841  * packet from its peer (i.e. as the peer sends all of its queued DATA
5842  * chunks) should clear the endpoint's retransmission count and restart
5843  * the T2-Shutdown timer,  giving its peer ample opportunity to transmit
5844  * all of its queued DATA chunks that have not yet been sent.
5845  */
5846 enum sctp_disposition sctp_sf_t2_timer_expire(
5847                                         struct net *net,
5848                                         const struct sctp_endpoint *ep,
5849                                         const struct sctp_association *asoc,
5850                                         const union sctp_subtype type,
5851                                         void *arg,
5852                                         struct sctp_cmd_seq *commands)
5853 {
5854         struct sctp_chunk *reply = NULL;
5855 
5856         pr_debug("%s: timer T2 expired\n", __func__);
5857 
5858         SCTP_INC_STATS(net, SCTP_MIB_T2_SHUTDOWN_EXPIREDS);
5859 
5860         ((struct sctp_association *)asoc)->shutdown_retries++;
5861 
5862         if (asoc->overall_error_count >= asoc->max_retrans) {
5863                 sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
5864                                 SCTP_ERROR(ETIMEDOUT));
5865                 /* Note:  CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */
5866                 sctp_add_cmd_sf(commands, SCTP_CMD_ASSOC_FAILED,
5867                                 SCTP_PERR(SCTP_ERROR_NO_ERROR));
5868                 SCTP_INC_STATS(net, SCTP_MIB_ABORTEDS);
5869                 SCTP_DEC_STATS(net, SCTP_MIB_CURRESTAB);
5870                 return SCTP_DISPOSITION_DELETE_TCB;
5871         }
5872 
5873         switch (asoc->state) {
5874         case SCTP_STATE_SHUTDOWN_SENT:
5875                 reply = sctp_make_shutdown(asoc, NULL);
5876                 break;
5877 
5878         case SCTP_STATE_SHUTDOWN_ACK_SENT:
5879                 reply = sctp_make_shutdown_ack(asoc, NULL);
5880                 break;
5881 
5882         default:
5883                 BUG();
5884                 break;
5885         }
5886 
5887         if (!reply)
5888                 goto nomem;
5889 
5890         /* Do some failure management (Section 8.2).
5891          * If we remove the transport an SHUTDOWN was last sent to, don't
5892          * do failure management.
5893          */
5894         if (asoc->shutdown_last_sent_to)
5895                 sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE,
5896                                 SCTP_TRANSPORT(asoc->shutdown_last_sent_to));
5897 
5898         /* Set the transport for the SHUTDOWN/ACK chunk and the timeout for
5899          * the T2-shutdown timer.
5900          */
5901         sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T2, SCTP_CHUNK(reply));
5902 
5903         /* Restart the T2-shutdown timer.  */
5904         sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
5905                         SCTP_TO(SCTP_EVENT_TIMEOUT_T2_SHUTDOWN));
5906         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(reply));
5907         return SCTP_DISPOSITION_CONSUME;
5908 
5909 nomem:
5910         return SCTP_DISPOSITION_NOMEM;
5911 }
5912 
5913 /*
5914  * ADDIP Section 4.1 ASCONF CHunk Procedures
5915  * If the T4 RTO timer expires the endpoint should do B1 to B5
5916  */
5917 enum sctp_disposition sctp_sf_t4_timer_expire(
5918                                         struct net *net,
5919                                         const struct sctp_endpoint *ep,
5920                                         const struct sctp_association *asoc,
5921                                         const union sctp_subtype type,
5922                                         void *arg,
5923                                         struct sctp_cmd_seq *commands)
5924 {
5925         struct sctp_chunk *chunk = asoc->addip_last_asconf;
5926         struct sctp_transport *transport = chunk->transport;
5927 
5928         SCTP_INC_STATS(net, SCTP_MIB_T4_RTO_EXPIREDS);
5929 
5930         /* ADDIP 4.1 B1) Increment the error counters and perform path failure
5931          * detection on the appropriate destination address as defined in
5932          * RFC2960 [5] section 8.1 and 8.2.
5933          */
5934         if (transport)
5935                 sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE,
5936                                 SCTP_TRANSPORT(transport));
5937 
5938         /* Reconfig T4 timer and transport. */
59