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TOMOYO Linux Cross Reference
Linux/net/sctp/sm_make_chunk.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  *
  7  * This file is part of the SCTP kernel implementation
  8  *
  9  * These functions work with the state functions in sctp_sm_statefuns.c
 10  * to implement the state operations.  These functions implement the
 11  * steps which require modifying existing data structures.
 12  *
 13  * This SCTP implementation is free software;
 14  * you can redistribute it and/or modify it under the terms of
 15  * the GNU General Public License as published by
 16  * the Free Software Foundation; either version 2, or (at your option)
 17  * any later version.
 18  *
 19  * This SCTP implementation is distributed in the hope that it
 20  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 21  *                 ************************
 22  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 23  * See the GNU General Public License for more details.
 24  *
 25  * You should have received a copy of the GNU General Public License
 26  * along with GNU CC; see the file COPYING.  If not, see
 27  * <http://www.gnu.org/licenses/>.
 28  *
 29  * Please send any bug reports or fixes you make to the
 30  * email address(es):
 31  *    lksctp developers <linux-sctp@vger.kernel.org>
 32  *
 33  * Written or modified by:
 34  *    La Monte H.P. Yarroll <piggy@acm.org>
 35  *    Karl Knutson          <karl@athena.chicago.il.us>
 36  *    C. Robin              <chris@hundredacre.ac.uk>
 37  *    Jon Grimm             <jgrimm@us.ibm.com>
 38  *    Xingang Guo           <xingang.guo@intel.com>
 39  *    Dajiang Zhang         <dajiang.zhang@nokia.com>
 40  *    Sridhar Samudrala     <sri@us.ibm.com>
 41  *    Daisy Chang           <daisyc@us.ibm.com>
 42  *    Ardelle Fan           <ardelle.fan@intel.com>
 43  *    Kevin Gao             <kevin.gao@intel.com>
 44  */
 45 
 46 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 47 
 48 #include <crypto/hash.h>
 49 #include <linux/types.h>
 50 #include <linux/kernel.h>
 51 #include <linux/ip.h>
 52 #include <linux/ipv6.h>
 53 #include <linux/net.h>
 54 #include <linux/inet.h>
 55 #include <linux/scatterlist.h>
 56 #include <linux/slab.h>
 57 #include <net/sock.h>
 58 
 59 #include <linux/skbuff.h>
 60 #include <linux/random.h>       /* for get_random_bytes */
 61 #include <net/sctp/sctp.h>
 62 #include <net/sctp/sm.h>
 63 
 64 static struct sctp_chunk *sctp_make_control(const struct sctp_association *asoc,
 65                                             __u8 type, __u8 flags, int paylen,
 66                                             gfp_t gfp);
 67 static struct sctp_chunk *sctp_make_data(const struct sctp_association *asoc,
 68                                          __u8 flags, int paylen, gfp_t gfp);
 69 static struct sctp_chunk *_sctp_make_chunk(const struct sctp_association *asoc,
 70                                            __u8 type, __u8 flags, int paylen,
 71                                            gfp_t gfp);
 72 static sctp_cookie_param_t *sctp_pack_cookie(const struct sctp_endpoint *ep,
 73                                         const struct sctp_association *asoc,
 74                                         const struct sctp_chunk *init_chunk,
 75                                         int *cookie_len,
 76                                         const __u8 *raw_addrs, int addrs_len);
 77 static int sctp_process_param(struct sctp_association *asoc,
 78                               union sctp_params param,
 79                               const union sctp_addr *peer_addr,
 80                               gfp_t gfp);
 81 static void *sctp_addto_param(struct sctp_chunk *chunk, int len,
 82                               const void *data);
 83 static void  *sctp_addto_chunk_fixed(struct sctp_chunk *, int len,
 84                                      const void *data);
 85 
 86 /* Control chunk destructor */
 87 static void sctp_control_release_owner(struct sk_buff *skb)
 88 {
 89         /*TODO: do memory release */
 90 }
 91 
 92 static void sctp_control_set_owner_w(struct sctp_chunk *chunk)
 93 {
 94         struct sctp_association *asoc = chunk->asoc;
 95         struct sk_buff *skb = chunk->skb;
 96 
 97         /* TODO: properly account for control chunks.
 98          * To do it right we'll need:
 99          *  1) endpoint if association isn't known.
100          *  2) proper memory accounting.
101          *
102          *  For now don't do anything for now.
103          */
104         skb->sk = asoc ? asoc->base.sk : NULL;
105         skb->destructor = sctp_control_release_owner;
106 }
107 
108 /* What was the inbound interface for this chunk? */
109 int sctp_chunk_iif(const struct sctp_chunk *chunk)
110 {
111         struct sk_buff *skb = chunk->skb;
112 
113         return SCTP_INPUT_CB(skb)->af->skb_iif(skb);
114 }
115 
116 /* RFC 2960 3.3.2 Initiation (INIT) (1)
117  *
118  * Note 2: The ECN capable field is reserved for future use of
119  * Explicit Congestion Notification.
120  */
121 static const struct sctp_paramhdr ecap_param = {
122         SCTP_PARAM_ECN_CAPABLE,
123         cpu_to_be16(sizeof(struct sctp_paramhdr)),
124 };
125 static const struct sctp_paramhdr prsctp_param = {
126         SCTP_PARAM_FWD_TSN_SUPPORT,
127         cpu_to_be16(sizeof(struct sctp_paramhdr)),
128 };
129 
130 /* A helper to initialize an op error inside a
131  * provided chunk, as most cause codes will be embedded inside an
132  * abort chunk.
133  */
134 void  sctp_init_cause(struct sctp_chunk *chunk, __be16 cause_code,
135                       size_t paylen)
136 {
137         sctp_errhdr_t err;
138         __u16 len;
139 
140         /* Cause code constants are now defined in network order.  */
141         err.cause = cause_code;
142         len = sizeof(sctp_errhdr_t) + paylen;
143         err.length  = htons(len);
144         chunk->subh.err_hdr = sctp_addto_chunk(chunk, sizeof(sctp_errhdr_t), &err);
145 }
146 
147 /* A helper to initialize an op error inside a
148  * provided chunk, as most cause codes will be embedded inside an
149  * abort chunk.  Differs from sctp_init_cause in that it won't oops
150  * if there isn't enough space in the op error chunk
151  */
152 static int sctp_init_cause_fixed(struct sctp_chunk *chunk, __be16 cause_code,
153                       size_t paylen)
154 {
155         sctp_errhdr_t err;
156         __u16 len;
157 
158         /* Cause code constants are now defined in network order.  */
159         err.cause = cause_code;
160         len = sizeof(sctp_errhdr_t) + paylen;
161         err.length  = htons(len);
162 
163         if (skb_tailroom(chunk->skb) < len)
164                 return -ENOSPC;
165         chunk->subh.err_hdr = sctp_addto_chunk_fixed(chunk,
166                                                      sizeof(sctp_errhdr_t),
167                                                      &err);
168         return 0;
169 }
170 /* 3.3.2 Initiation (INIT) (1)
171  *
172  * This chunk is used to initiate a SCTP association between two
173  * endpoints. The format of the INIT chunk is shown below:
174  *
175  *     0                   1                   2                   3
176  *     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
177  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
178  *    |   Type = 1    |  Chunk Flags  |      Chunk Length             |
179  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
180  *    |                         Initiate Tag                          |
181  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
182  *    |           Advertised Receiver Window Credit (a_rwnd)          |
183  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
184  *    |  Number of Outbound Streams   |  Number of Inbound Streams    |
185  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
186  *    |                          Initial TSN                          |
187  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
188  *    \                                                               \
189  *    /              Optional/Variable-Length Parameters              /
190  *    \                                                               \
191  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
192  *
193  *
194  * The INIT chunk contains the following parameters. Unless otherwise
195  * noted, each parameter MUST only be included once in the INIT chunk.
196  *
197  * Fixed Parameters                     Status
198  * ----------------------------------------------
199  * Initiate Tag                        Mandatory
200  * Advertised Receiver Window Credit   Mandatory
201  * Number of Outbound Streams          Mandatory
202  * Number of Inbound Streams           Mandatory
203  * Initial TSN                         Mandatory
204  *
205  * Variable Parameters                  Status     Type Value
206  * -------------------------------------------------------------
207  * IPv4 Address (Note 1)               Optional    5
208  * IPv6 Address (Note 1)               Optional    6
209  * Cookie Preservative                 Optional    9
210  * Reserved for ECN Capable (Note 2)   Optional    32768 (0x8000)
211  * Host Name Address (Note 3)          Optional    11
212  * Supported Address Types (Note 4)    Optional    12
213  */
214 struct sctp_chunk *sctp_make_init(const struct sctp_association *asoc,
215                              const struct sctp_bind_addr *bp,
216                              gfp_t gfp, int vparam_len)
217 {
218         struct net *net = sock_net(asoc->base.sk);
219         struct sctp_endpoint *ep = asoc->ep;
220         sctp_inithdr_t init;
221         union sctp_params addrs;
222         size_t chunksize;
223         struct sctp_chunk *retval = NULL;
224         int num_types, addrs_len = 0;
225         struct sctp_sock *sp;
226         sctp_supported_addrs_param_t sat;
227         __be16 types[2];
228         sctp_adaptation_ind_param_t aiparam;
229         sctp_supported_ext_param_t ext_param;
230         int num_ext = 0;
231         __u8 extensions[3];
232         sctp_paramhdr_t *auth_chunks = NULL,
233                         *auth_hmacs = NULL;
234 
235         /* RFC 2960 3.3.2 Initiation (INIT) (1)
236          *
237          * Note 1: The INIT chunks can contain multiple addresses that
238          * can be IPv4 and/or IPv6 in any combination.
239          */
240         retval = NULL;
241 
242         /* Convert the provided bind address list to raw format. */
243         addrs = sctp_bind_addrs_to_raw(bp, &addrs_len, gfp);
244 
245         init.init_tag              = htonl(asoc->c.my_vtag);
246         init.a_rwnd                = htonl(asoc->rwnd);
247         init.num_outbound_streams  = htons(asoc->c.sinit_num_ostreams);
248         init.num_inbound_streams   = htons(asoc->c.sinit_max_instreams);
249         init.initial_tsn           = htonl(asoc->c.initial_tsn);
250 
251         /* How many address types are needed? */
252         sp = sctp_sk(asoc->base.sk);
253         num_types = sp->pf->supported_addrs(sp, types);
254 
255         chunksize = sizeof(init) + addrs_len;
256         chunksize += WORD_ROUND(SCTP_SAT_LEN(num_types));
257         chunksize += sizeof(ecap_param);
258 
259         if (asoc->prsctp_enable)
260                 chunksize += sizeof(prsctp_param);
261 
262         /* ADDIP: Section 4.2.7:
263          *  An implementation supporting this extension [ADDIP] MUST list
264          *  the ASCONF,the ASCONF-ACK, and the AUTH  chunks in its INIT and
265          *  INIT-ACK parameters.
266          */
267         if (net->sctp.addip_enable) {
268                 extensions[num_ext] = SCTP_CID_ASCONF;
269                 extensions[num_ext+1] = SCTP_CID_ASCONF_ACK;
270                 num_ext += 2;
271         }
272 
273         if (sp->adaptation_ind)
274                 chunksize += sizeof(aiparam);
275 
276         chunksize += vparam_len;
277 
278         /* Account for AUTH related parameters */
279         if (ep->auth_enable) {
280                 /* Add random parameter length*/
281                 chunksize += sizeof(asoc->c.auth_random);
282 
283                 /* Add HMACS parameter length if any were defined */
284                 auth_hmacs = (sctp_paramhdr_t *)asoc->c.auth_hmacs;
285                 if (auth_hmacs->length)
286                         chunksize += WORD_ROUND(ntohs(auth_hmacs->length));
287                 else
288                         auth_hmacs = NULL;
289 
290                 /* Add CHUNKS parameter length */
291                 auth_chunks = (sctp_paramhdr_t *)asoc->c.auth_chunks;
292                 if (auth_chunks->length)
293                         chunksize += WORD_ROUND(ntohs(auth_chunks->length));
294                 else
295                         auth_chunks = NULL;
296 
297                 extensions[num_ext] = SCTP_CID_AUTH;
298                 num_ext += 1;
299         }
300 
301         /* If we have any extensions to report, account for that */
302         if (num_ext)
303                 chunksize += WORD_ROUND(sizeof(sctp_supported_ext_param_t) +
304                                         num_ext);
305 
306         /* RFC 2960 3.3.2 Initiation (INIT) (1)
307          *
308          * Note 3: An INIT chunk MUST NOT contain more than one Host
309          * Name address parameter. Moreover, the sender of the INIT
310          * MUST NOT combine any other address types with the Host Name
311          * address in the INIT. The receiver of INIT MUST ignore any
312          * other address types if the Host Name address parameter is
313          * present in the received INIT chunk.
314          *
315          * PLEASE DO NOT FIXME [This version does not support Host Name.]
316          */
317 
318         retval = sctp_make_control(asoc, SCTP_CID_INIT, 0, chunksize, gfp);
319         if (!retval)
320                 goto nodata;
321 
322         retval->subh.init_hdr =
323                 sctp_addto_chunk(retval, sizeof(init), &init);
324         retval->param_hdr.v =
325                 sctp_addto_chunk(retval, addrs_len, addrs.v);
326 
327         /* RFC 2960 3.3.2 Initiation (INIT) (1)
328          *
329          * Note 4: This parameter, when present, specifies all the
330          * address types the sending endpoint can support. The absence
331          * of this parameter indicates that the sending endpoint can
332          * support any address type.
333          */
334         sat.param_hdr.type = SCTP_PARAM_SUPPORTED_ADDRESS_TYPES;
335         sat.param_hdr.length = htons(SCTP_SAT_LEN(num_types));
336         sctp_addto_chunk(retval, sizeof(sat), &sat);
337         sctp_addto_chunk(retval, num_types * sizeof(__u16), &types);
338 
339         sctp_addto_chunk(retval, sizeof(ecap_param), &ecap_param);
340 
341         /* Add the supported extensions parameter.  Be nice and add this
342          * fist before addiding the parameters for the extensions themselves
343          */
344         if (num_ext) {
345                 ext_param.param_hdr.type = SCTP_PARAM_SUPPORTED_EXT;
346                 ext_param.param_hdr.length =
347                             htons(sizeof(sctp_supported_ext_param_t) + num_ext);
348                 sctp_addto_chunk(retval, sizeof(sctp_supported_ext_param_t),
349                                 &ext_param);
350                 sctp_addto_param(retval, num_ext, extensions);
351         }
352 
353         if (asoc->prsctp_enable)
354                 sctp_addto_chunk(retval, sizeof(prsctp_param), &prsctp_param);
355 
356         if (sp->adaptation_ind) {
357                 aiparam.param_hdr.type = SCTP_PARAM_ADAPTATION_LAYER_IND;
358                 aiparam.param_hdr.length = htons(sizeof(aiparam));
359                 aiparam.adaptation_ind = htonl(sp->adaptation_ind);
360                 sctp_addto_chunk(retval, sizeof(aiparam), &aiparam);
361         }
362 
363         /* Add SCTP-AUTH chunks to the parameter list */
364         if (ep->auth_enable) {
365                 sctp_addto_chunk(retval, sizeof(asoc->c.auth_random),
366                                  asoc->c.auth_random);
367                 if (auth_hmacs)
368                         sctp_addto_chunk(retval, ntohs(auth_hmacs->length),
369                                         auth_hmacs);
370                 if (auth_chunks)
371                         sctp_addto_chunk(retval, ntohs(auth_chunks->length),
372                                         auth_chunks);
373         }
374 nodata:
375         kfree(addrs.v);
376         return retval;
377 }
378 
379 struct sctp_chunk *sctp_make_init_ack(const struct sctp_association *asoc,
380                                  const struct sctp_chunk *chunk,
381                                  gfp_t gfp, int unkparam_len)
382 {
383         sctp_inithdr_t initack;
384         struct sctp_chunk *retval;
385         union sctp_params addrs;
386         struct sctp_sock *sp;
387         int addrs_len;
388         sctp_cookie_param_t *cookie;
389         int cookie_len;
390         size_t chunksize;
391         sctp_adaptation_ind_param_t aiparam;
392         sctp_supported_ext_param_t ext_param;
393         int num_ext = 0;
394         __u8 extensions[3];
395         sctp_paramhdr_t *auth_chunks = NULL,
396                         *auth_hmacs = NULL,
397                         *auth_random = NULL;
398 
399         retval = NULL;
400 
401         /* Note: there may be no addresses to embed. */
402         addrs = sctp_bind_addrs_to_raw(&asoc->base.bind_addr, &addrs_len, gfp);
403 
404         initack.init_tag                = htonl(asoc->c.my_vtag);
405         initack.a_rwnd                  = htonl(asoc->rwnd);
406         initack.num_outbound_streams    = htons(asoc->c.sinit_num_ostreams);
407         initack.num_inbound_streams     = htons(asoc->c.sinit_max_instreams);
408         initack.initial_tsn             = htonl(asoc->c.initial_tsn);
409 
410         /* FIXME:  We really ought to build the cookie right
411          * into the packet instead of allocating more fresh memory.
412          */
413         cookie = sctp_pack_cookie(asoc->ep, asoc, chunk, &cookie_len,
414                                   addrs.v, addrs_len);
415         if (!cookie)
416                 goto nomem_cookie;
417 
418         /* Calculate the total size of allocation, include the reserved
419          * space for reporting unknown parameters if it is specified.
420          */
421         sp = sctp_sk(asoc->base.sk);
422         chunksize = sizeof(initack) + addrs_len + cookie_len + unkparam_len;
423 
424         /* Tell peer that we'll do ECN only if peer advertised such cap.  */
425         if (asoc->peer.ecn_capable)
426                 chunksize += sizeof(ecap_param);
427 
428         if (asoc->peer.prsctp_capable)
429                 chunksize += sizeof(prsctp_param);
430 
431         if (asoc->peer.asconf_capable) {
432                 extensions[num_ext] = SCTP_CID_ASCONF;
433                 extensions[num_ext+1] = SCTP_CID_ASCONF_ACK;
434                 num_ext += 2;
435         }
436 
437         if (sp->adaptation_ind)
438                 chunksize += sizeof(aiparam);
439 
440         if (asoc->peer.auth_capable) {
441                 auth_random = (sctp_paramhdr_t *)asoc->c.auth_random;
442                 chunksize += ntohs(auth_random->length);
443 
444                 auth_hmacs = (sctp_paramhdr_t *)asoc->c.auth_hmacs;
445                 if (auth_hmacs->length)
446                         chunksize += WORD_ROUND(ntohs(auth_hmacs->length));
447                 else
448                         auth_hmacs = NULL;
449 
450                 auth_chunks = (sctp_paramhdr_t *)asoc->c.auth_chunks;
451                 if (auth_chunks->length)
452                         chunksize += WORD_ROUND(ntohs(auth_chunks->length));
453                 else
454                         auth_chunks = NULL;
455 
456                 extensions[num_ext] = SCTP_CID_AUTH;
457                 num_ext += 1;
458         }
459 
460         if (num_ext)
461                 chunksize += WORD_ROUND(sizeof(sctp_supported_ext_param_t) +
462                                         num_ext);
463 
464         /* Now allocate and fill out the chunk.  */
465         retval = sctp_make_control(asoc, SCTP_CID_INIT_ACK, 0, chunksize, gfp);
466         if (!retval)
467                 goto nomem_chunk;
468 
469         /* RFC 2960 6.4 Multi-homed SCTP Endpoints
470          *
471          * An endpoint SHOULD transmit reply chunks (e.g., SACK,
472          * HEARTBEAT ACK, * etc.) to the same destination transport
473          * address from which it received the DATA or control chunk
474          * to which it is replying.
475          *
476          * [INIT ACK back to where the INIT came from.]
477          */
478         retval->transport = chunk->transport;
479 
480         retval->subh.init_hdr =
481                 sctp_addto_chunk(retval, sizeof(initack), &initack);
482         retval->param_hdr.v = sctp_addto_chunk(retval, addrs_len, addrs.v);
483         sctp_addto_chunk(retval, cookie_len, cookie);
484         if (asoc->peer.ecn_capable)
485                 sctp_addto_chunk(retval, sizeof(ecap_param), &ecap_param);
486         if (num_ext) {
487                 ext_param.param_hdr.type = SCTP_PARAM_SUPPORTED_EXT;
488                 ext_param.param_hdr.length =
489                             htons(sizeof(sctp_supported_ext_param_t) + num_ext);
490                 sctp_addto_chunk(retval, sizeof(sctp_supported_ext_param_t),
491                                  &ext_param);
492                 sctp_addto_param(retval, num_ext, extensions);
493         }
494         if (asoc->peer.prsctp_capable)
495                 sctp_addto_chunk(retval, sizeof(prsctp_param), &prsctp_param);
496 
497         if (sp->adaptation_ind) {
498                 aiparam.param_hdr.type = SCTP_PARAM_ADAPTATION_LAYER_IND;
499                 aiparam.param_hdr.length = htons(sizeof(aiparam));
500                 aiparam.adaptation_ind = htonl(sp->adaptation_ind);
501                 sctp_addto_chunk(retval, sizeof(aiparam), &aiparam);
502         }
503 
504         if (asoc->peer.auth_capable) {
505                 sctp_addto_chunk(retval, ntohs(auth_random->length),
506                                  auth_random);
507                 if (auth_hmacs)
508                         sctp_addto_chunk(retval, ntohs(auth_hmacs->length),
509                                         auth_hmacs);
510                 if (auth_chunks)
511                         sctp_addto_chunk(retval, ntohs(auth_chunks->length),
512                                         auth_chunks);
513         }
514 
515         /* We need to remove the const qualifier at this point.  */
516         retval->asoc = (struct sctp_association *) asoc;
517 
518 nomem_chunk:
519         kfree(cookie);
520 nomem_cookie:
521         kfree(addrs.v);
522         return retval;
523 }
524 
525 /* 3.3.11 Cookie Echo (COOKIE ECHO) (10):
526  *
527  * This chunk is used only during the initialization of an association.
528  * It is sent by the initiator of an association to its peer to complete
529  * the initialization process. This chunk MUST precede any DATA chunk
530  * sent within the association, but MAY be bundled with one or more DATA
531  * chunks in the same packet.
532  *
533  *      0                   1                   2                   3
534  *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
535  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
536  *     |   Type = 10   |Chunk  Flags   |         Length                |
537  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
538  *     /                     Cookie                                    /
539  *     \                                                               \
540  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
541  *
542  * Chunk Flags: 8 bit
543  *
544  *   Set to zero on transmit and ignored on receipt.
545  *
546  * Length: 16 bits (unsigned integer)
547  *
548  *   Set to the size of the chunk in bytes, including the 4 bytes of
549  *   the chunk header and the size of the Cookie.
550  *
551  * Cookie: variable size
552  *
553  *   This field must contain the exact cookie received in the
554  *   State Cookie parameter from the previous INIT ACK.
555  *
556  *   An implementation SHOULD make the cookie as small as possible
557  *   to insure interoperability.
558  */
559 struct sctp_chunk *sctp_make_cookie_echo(const struct sctp_association *asoc,
560                                     const struct sctp_chunk *chunk)
561 {
562         struct sctp_chunk *retval;
563         void *cookie;
564         int cookie_len;
565 
566         cookie = asoc->peer.cookie;
567         cookie_len = asoc->peer.cookie_len;
568 
569         /* Build a cookie echo chunk.  */
570         retval = sctp_make_control(asoc, SCTP_CID_COOKIE_ECHO, 0,
571                                    cookie_len, GFP_ATOMIC);
572         if (!retval)
573                 goto nodata;
574         retval->subh.cookie_hdr =
575                 sctp_addto_chunk(retval, cookie_len, cookie);
576 
577         /* RFC 2960 6.4 Multi-homed SCTP Endpoints
578          *
579          * An endpoint SHOULD transmit reply chunks (e.g., SACK,
580          * HEARTBEAT ACK, * etc.) to the same destination transport
581          * address from which it * received the DATA or control chunk
582          * to which it is replying.
583          *
584          * [COOKIE ECHO back to where the INIT ACK came from.]
585          */
586         if (chunk)
587                 retval->transport = chunk->transport;
588 
589 nodata:
590         return retval;
591 }
592 
593 /* 3.3.12 Cookie Acknowledgement (COOKIE ACK) (11):
594  *
595  * This chunk is used only during the initialization of an
596  * association.  It is used to acknowledge the receipt of a COOKIE
597  * ECHO chunk.  This chunk MUST precede any DATA or SACK chunk sent
598  * within the association, but MAY be bundled with one or more DATA
599  * chunks or SACK chunk in the same SCTP packet.
600  *
601  *      0                   1                   2                   3
602  *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
603  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
604  *     |   Type = 11   |Chunk  Flags   |     Length = 4                |
605  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
606  *
607  * Chunk Flags: 8 bits
608  *
609  *   Set to zero on transmit and ignored on receipt.
610  */
611 struct sctp_chunk *sctp_make_cookie_ack(const struct sctp_association *asoc,
612                                    const struct sctp_chunk *chunk)
613 {
614         struct sctp_chunk *retval;
615 
616         retval = sctp_make_control(asoc, SCTP_CID_COOKIE_ACK, 0, 0, GFP_ATOMIC);
617 
618         /* RFC 2960 6.4 Multi-homed SCTP Endpoints
619          *
620          * An endpoint SHOULD transmit reply chunks (e.g., SACK,
621          * HEARTBEAT ACK, * etc.) to the same destination transport
622          * address from which it * received the DATA or control chunk
623          * to which it is replying.
624          *
625          * [COOKIE ACK back to where the COOKIE ECHO came from.]
626          */
627         if (retval && chunk)
628                 retval->transport = chunk->transport;
629 
630         return retval;
631 }
632 
633 /*
634  *  Appendix A: Explicit Congestion Notification:
635  *  CWR:
636  *
637  *  RFC 2481 details a specific bit for a sender to send in the header of
638  *  its next outbound TCP segment to indicate to its peer that it has
639  *  reduced its congestion window.  This is termed the CWR bit.  For
640  *  SCTP the same indication is made by including the CWR chunk.
641  *  This chunk contains one data element, i.e. the TSN number that
642  *  was sent in the ECNE chunk.  This element represents the lowest
643  *  TSN number in the datagram that was originally marked with the
644  *  CE bit.
645  *
646  *     0                   1                   2                   3
647  *     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
648  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
649  *    | Chunk Type=13 | Flags=00000000|    Chunk Length = 8           |
650  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
651  *    |                      Lowest TSN Number                        |
652  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
653  *
654  *     Note: The CWR is considered a Control chunk.
655  */
656 struct sctp_chunk *sctp_make_cwr(const struct sctp_association *asoc,
657                             const __u32 lowest_tsn,
658                             const struct sctp_chunk *chunk)
659 {
660         struct sctp_chunk *retval;
661         sctp_cwrhdr_t cwr;
662 
663         cwr.lowest_tsn = htonl(lowest_tsn);
664         retval = sctp_make_control(asoc, SCTP_CID_ECN_CWR, 0,
665                                    sizeof(sctp_cwrhdr_t), GFP_ATOMIC);
666 
667         if (!retval)
668                 goto nodata;
669 
670         retval->subh.ecn_cwr_hdr =
671                 sctp_addto_chunk(retval, sizeof(cwr), &cwr);
672 
673         /* RFC 2960 6.4 Multi-homed SCTP Endpoints
674          *
675          * An endpoint SHOULD transmit reply chunks (e.g., SACK,
676          * HEARTBEAT ACK, * etc.) to the same destination transport
677          * address from which it * received the DATA or control chunk
678          * to which it is replying.
679          *
680          * [Report a reduced congestion window back to where the ECNE
681          * came from.]
682          */
683         if (chunk)
684                 retval->transport = chunk->transport;
685 
686 nodata:
687         return retval;
688 }
689 
690 /* Make an ECNE chunk.  This is a congestion experienced report.  */
691 struct sctp_chunk *sctp_make_ecne(const struct sctp_association *asoc,
692                              const __u32 lowest_tsn)
693 {
694         struct sctp_chunk *retval;
695         sctp_ecnehdr_t ecne;
696 
697         ecne.lowest_tsn = htonl(lowest_tsn);
698         retval = sctp_make_control(asoc, SCTP_CID_ECN_ECNE, 0,
699                                    sizeof(sctp_ecnehdr_t), GFP_ATOMIC);
700         if (!retval)
701                 goto nodata;
702         retval->subh.ecne_hdr =
703                 sctp_addto_chunk(retval, sizeof(ecne), &ecne);
704 
705 nodata:
706         return retval;
707 }
708 
709 /* Make a DATA chunk for the given association from the provided
710  * parameters.  However, do not populate the data payload.
711  */
712 struct sctp_chunk *sctp_make_datafrag_empty(struct sctp_association *asoc,
713                                        const struct sctp_sndrcvinfo *sinfo,
714                                        int data_len, __u8 flags, __u16 ssn,
715                                        gfp_t gfp)
716 {
717         struct sctp_chunk *retval;
718         struct sctp_datahdr dp;
719         int chunk_len;
720 
721         /* We assign the TSN as LATE as possible, not here when
722          * creating the chunk.
723          */
724         dp.tsn = 0;
725         dp.stream = htons(sinfo->sinfo_stream);
726         dp.ppid   = sinfo->sinfo_ppid;
727 
728         /* Set the flags for an unordered send.  */
729         if (sinfo->sinfo_flags & SCTP_UNORDERED) {
730                 flags |= SCTP_DATA_UNORDERED;
731                 dp.ssn = 0;
732         } else
733                 dp.ssn = htons(ssn);
734 
735         chunk_len = sizeof(dp) + data_len;
736         retval = sctp_make_data(asoc, flags, chunk_len, gfp);
737         if (!retval)
738                 goto nodata;
739 
740         retval->subh.data_hdr = sctp_addto_chunk(retval, sizeof(dp), &dp);
741         memcpy(&retval->sinfo, sinfo, sizeof(struct sctp_sndrcvinfo));
742 
743 nodata:
744         return retval;
745 }
746 
747 /* Create a selective ackowledgement (SACK) for the given
748  * association.  This reports on which TSN's we've seen to date,
749  * including duplicates and gaps.
750  */
751 struct sctp_chunk *sctp_make_sack(const struct sctp_association *asoc)
752 {
753         struct sctp_chunk *retval;
754         struct sctp_sackhdr sack;
755         int len;
756         __u32 ctsn;
757         __u16 num_gabs, num_dup_tsns;
758         struct sctp_association *aptr = (struct sctp_association *)asoc;
759         struct sctp_tsnmap *map = (struct sctp_tsnmap *)&asoc->peer.tsn_map;
760         struct sctp_gap_ack_block gabs[SCTP_MAX_GABS];
761         struct sctp_transport *trans;
762 
763         memset(gabs, 0, sizeof(gabs));
764         ctsn = sctp_tsnmap_get_ctsn(map);
765 
766         pr_debug("%s: sackCTSNAck sent:0x%x\n", __func__, ctsn);
767 
768         /* How much room is needed in the chunk? */
769         num_gabs = sctp_tsnmap_num_gabs(map, gabs);
770         num_dup_tsns = sctp_tsnmap_num_dups(map);
771 
772         /* Initialize the SACK header.  */
773         sack.cum_tsn_ack            = htonl(ctsn);
774         sack.a_rwnd                 = htonl(asoc->a_rwnd);
775         sack.num_gap_ack_blocks     = htons(num_gabs);
776         sack.num_dup_tsns           = htons(num_dup_tsns);
777 
778         len = sizeof(sack)
779                 + sizeof(struct sctp_gap_ack_block) * num_gabs
780                 + sizeof(__u32) * num_dup_tsns;
781 
782         /* Create the chunk.  */
783         retval = sctp_make_control(asoc, SCTP_CID_SACK, 0, len, GFP_ATOMIC);
784         if (!retval)
785                 goto nodata;
786 
787         /* RFC 2960 6.4 Multi-homed SCTP Endpoints
788          *
789          * An endpoint SHOULD transmit reply chunks (e.g., SACK,
790          * HEARTBEAT ACK, etc.) to the same destination transport
791          * address from which it received the DATA or control chunk to
792          * which it is replying.  This rule should also be followed if
793          * the endpoint is bundling DATA chunks together with the
794          * reply chunk.
795          *
796          * However, when acknowledging multiple DATA chunks received
797          * in packets from different source addresses in a single
798          * SACK, the SACK chunk may be transmitted to one of the
799          * destination transport addresses from which the DATA or
800          * control chunks being acknowledged were received.
801          *
802          * [BUG:  We do not implement the following paragraph.
803          * Perhaps we should remember the last transport we used for a
804          * SACK and avoid that (if possible) if we have seen any
805          * duplicates. --piggy]
806          *
807          * When a receiver of a duplicate DATA chunk sends a SACK to a
808          * multi- homed endpoint it MAY be beneficial to vary the
809          * destination address and not use the source address of the
810          * DATA chunk.  The reason being that receiving a duplicate
811          * from a multi-homed endpoint might indicate that the return
812          * path (as specified in the source address of the DATA chunk)
813          * for the SACK is broken.
814          *
815          * [Send to the address from which we last received a DATA chunk.]
816          */
817         retval->transport = asoc->peer.last_data_from;
818 
819         retval->subh.sack_hdr =
820                 sctp_addto_chunk(retval, sizeof(sack), &sack);
821 
822         /* Add the gap ack block information.   */
823         if (num_gabs)
824                 sctp_addto_chunk(retval, sizeof(__u32) * num_gabs,
825                                  gabs);
826 
827         /* Add the duplicate TSN information.  */
828         if (num_dup_tsns) {
829                 aptr->stats.idupchunks += num_dup_tsns;
830                 sctp_addto_chunk(retval, sizeof(__u32) * num_dup_tsns,
831                                  sctp_tsnmap_get_dups(map));
832         }
833         /* Once we have a sack generated, check to see what our sack
834          * generation is, if its 0, reset the transports to 0, and reset
835          * the association generation to 1
836          *
837          * The idea is that zero is never used as a valid generation for the
838          * association so no transport will match after a wrap event like this,
839          * Until the next sack
840          */
841         if (++aptr->peer.sack_generation == 0) {
842                 list_for_each_entry(trans, &asoc->peer.transport_addr_list,
843                                     transports)
844                         trans->sack_generation = 0;
845                 aptr->peer.sack_generation = 1;
846         }
847 nodata:
848         return retval;
849 }
850 
851 /* Make a SHUTDOWN chunk. */
852 struct sctp_chunk *sctp_make_shutdown(const struct sctp_association *asoc,
853                                       const struct sctp_chunk *chunk)
854 {
855         struct sctp_chunk *retval;
856         sctp_shutdownhdr_t shut;
857         __u32 ctsn;
858 
859         ctsn = sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map);
860         shut.cum_tsn_ack = htonl(ctsn);
861 
862         retval = sctp_make_control(asoc, SCTP_CID_SHUTDOWN, 0,
863                                    sizeof(sctp_shutdownhdr_t), GFP_ATOMIC);
864         if (!retval)
865                 goto nodata;
866 
867         retval->subh.shutdown_hdr =
868                 sctp_addto_chunk(retval, sizeof(shut), &shut);
869 
870         if (chunk)
871                 retval->transport = chunk->transport;
872 nodata:
873         return retval;
874 }
875 
876 struct sctp_chunk *sctp_make_shutdown_ack(const struct sctp_association *asoc,
877                                      const struct sctp_chunk *chunk)
878 {
879         struct sctp_chunk *retval;
880 
881         retval = sctp_make_control(asoc, SCTP_CID_SHUTDOWN_ACK, 0, 0,
882                                    GFP_ATOMIC);
883 
884         /* RFC 2960 6.4 Multi-homed SCTP Endpoints
885          *
886          * An endpoint SHOULD transmit reply chunks (e.g., SACK,
887          * HEARTBEAT ACK, * etc.) to the same destination transport
888          * address from which it * received the DATA or control chunk
889          * to which it is replying.
890          *
891          * [ACK back to where the SHUTDOWN came from.]
892          */
893         if (retval && chunk)
894                 retval->transport = chunk->transport;
895 
896         return retval;
897 }
898 
899 struct sctp_chunk *sctp_make_shutdown_complete(
900         const struct sctp_association *asoc,
901         const struct sctp_chunk *chunk)
902 {
903         struct sctp_chunk *retval;
904         __u8 flags = 0;
905 
906         /* Set the T-bit if we have no association (vtag will be
907          * reflected)
908          */
909         flags |= asoc ? 0 : SCTP_CHUNK_FLAG_T;
910 
911         retval = sctp_make_control(asoc, SCTP_CID_SHUTDOWN_COMPLETE, flags,
912                                    0, GFP_ATOMIC);
913 
914         /* RFC 2960 6.4 Multi-homed SCTP Endpoints
915          *
916          * An endpoint SHOULD transmit reply chunks (e.g., SACK,
917          * HEARTBEAT ACK, * etc.) to the same destination transport
918          * address from which it * received the DATA or control chunk
919          * to which it is replying.
920          *
921          * [Report SHUTDOWN COMPLETE back to where the SHUTDOWN ACK
922          * came from.]
923          */
924         if (retval && chunk)
925                 retval->transport = chunk->transport;
926 
927         return retval;
928 }
929 
930 /* Create an ABORT.  Note that we set the T bit if we have no
931  * association, except when responding to an INIT (sctpimpguide 2.41).
932  */
933 struct sctp_chunk *sctp_make_abort(const struct sctp_association *asoc,
934                               const struct sctp_chunk *chunk,
935                               const size_t hint)
936 {
937         struct sctp_chunk *retval;
938         __u8 flags = 0;
939 
940         /* Set the T-bit if we have no association and 'chunk' is not
941          * an INIT (vtag will be reflected).
942          */
943         if (!asoc) {
944                 if (chunk && chunk->chunk_hdr &&
945                     chunk->chunk_hdr->type == SCTP_CID_INIT)
946                         flags = 0;
947                 else
948                         flags = SCTP_CHUNK_FLAG_T;
949         }
950 
951         retval = sctp_make_control(asoc, SCTP_CID_ABORT, flags, hint,
952                                    GFP_ATOMIC);
953 
954         /* RFC 2960 6.4 Multi-homed SCTP Endpoints
955          *
956          * An endpoint SHOULD transmit reply chunks (e.g., SACK,
957          * HEARTBEAT ACK, * etc.) to the same destination transport
958          * address from which it * received the DATA or control chunk
959          * to which it is replying.
960          *
961          * [ABORT back to where the offender came from.]
962          */
963         if (retval && chunk)
964                 retval->transport = chunk->transport;
965 
966         return retval;
967 }
968 
969 /* Helper to create ABORT with a NO_USER_DATA error.  */
970 struct sctp_chunk *sctp_make_abort_no_data(
971         const struct sctp_association *asoc,
972         const struct sctp_chunk *chunk, __u32 tsn)
973 {
974         struct sctp_chunk *retval;
975         __be32 payload;
976 
977         retval = sctp_make_abort(asoc, chunk, sizeof(sctp_errhdr_t)
978                                  + sizeof(tsn));
979 
980         if (!retval)
981                 goto no_mem;
982 
983         /* Put the tsn back into network byte order.  */
984         payload = htonl(tsn);
985         sctp_init_cause(retval, SCTP_ERROR_NO_DATA, sizeof(payload));
986         sctp_addto_chunk(retval, sizeof(payload), (const void *)&payload);
987 
988         /* RFC 2960 6.4 Multi-homed SCTP Endpoints
989          *
990          * An endpoint SHOULD transmit reply chunks (e.g., SACK,
991          * HEARTBEAT ACK, * etc.) to the same destination transport
992          * address from which it * received the DATA or control chunk
993          * to which it is replying.
994          *
995          * [ABORT back to where the offender came from.]
996          */
997         if (chunk)
998                 retval->transport = chunk->transport;
999 
1000 no_mem:
1001         return retval;
1002 }
1003 
1004 /* Helper to create ABORT with a SCTP_ERROR_USER_ABORT error.  */
1005 struct sctp_chunk *sctp_make_abort_user(const struct sctp_association *asoc,
1006                                         struct msghdr *msg,
1007                                         size_t paylen)
1008 {
1009         struct sctp_chunk *retval;
1010         void *payload = NULL;
1011         int err;
1012 
1013         retval = sctp_make_abort(asoc, NULL, sizeof(sctp_errhdr_t) + paylen);
1014         if (!retval)
1015                 goto err_chunk;
1016 
1017         if (paylen) {
1018                 /* Put the msg_iov together into payload.  */
1019                 payload = kmalloc(paylen, GFP_KERNEL);
1020                 if (!payload)
1021                         goto err_payload;
1022 
1023                 err = memcpy_from_msg(payload, msg, paylen);
1024                 if (err < 0)
1025                         goto err_copy;
1026         }
1027 
1028         sctp_init_cause(retval, SCTP_ERROR_USER_ABORT, paylen);
1029         sctp_addto_chunk(retval, paylen, payload);
1030 
1031         if (paylen)
1032                 kfree(payload);
1033 
1034         return retval;
1035 
1036 err_copy:
1037         kfree(payload);
1038 err_payload:
1039         sctp_chunk_free(retval);
1040         retval = NULL;
1041 err_chunk:
1042         return retval;
1043 }
1044 
1045 /* Append bytes to the end of a parameter.  Will panic if chunk is not big
1046  * enough.
1047  */
1048 static void *sctp_addto_param(struct sctp_chunk *chunk, int len,
1049                               const void *data)
1050 {
1051         void *target;
1052         int chunklen = ntohs(chunk->chunk_hdr->length);
1053 
1054         target = skb_put(chunk->skb, len);
1055 
1056         if (data)
1057                 memcpy(target, data, len);
1058         else
1059                 memset(target, 0, len);
1060 
1061         /* Adjust the chunk length field.  */
1062         chunk->chunk_hdr->length = htons(chunklen + len);
1063         chunk->chunk_end = skb_tail_pointer(chunk->skb);
1064 
1065         return target;
1066 }
1067 
1068 /* Make an ABORT chunk with a PROTOCOL VIOLATION cause code. */
1069 struct sctp_chunk *sctp_make_abort_violation(
1070         const struct sctp_association *asoc,
1071         const struct sctp_chunk *chunk,
1072         const __u8   *payload,
1073         const size_t paylen)
1074 {
1075         struct sctp_chunk  *retval;
1076         struct sctp_paramhdr phdr;
1077 
1078         retval = sctp_make_abort(asoc, chunk, sizeof(sctp_errhdr_t) + paylen
1079                                         + sizeof(sctp_paramhdr_t));
1080         if (!retval)
1081                 goto end;
1082 
1083         sctp_init_cause(retval, SCTP_ERROR_PROTO_VIOLATION, paylen
1084                                         + sizeof(sctp_paramhdr_t));
1085 
1086         phdr.type = htons(chunk->chunk_hdr->type);
1087         phdr.length = chunk->chunk_hdr->length;
1088         sctp_addto_chunk(retval, paylen, payload);
1089         sctp_addto_param(retval, sizeof(sctp_paramhdr_t), &phdr);
1090 
1091 end:
1092         return retval;
1093 }
1094 
1095 struct sctp_chunk *sctp_make_violation_paramlen(
1096         const struct sctp_association *asoc,
1097         const struct sctp_chunk *chunk,
1098         struct sctp_paramhdr *param)
1099 {
1100         struct sctp_chunk *retval;
1101         static const char error[] = "The following parameter had invalid length:";
1102         size_t payload_len = sizeof(error) + sizeof(sctp_errhdr_t) +
1103                                 sizeof(sctp_paramhdr_t);
1104 
1105         retval = sctp_make_abort(asoc, chunk, payload_len);
1106         if (!retval)
1107                 goto nodata;
1108 
1109         sctp_init_cause(retval, SCTP_ERROR_PROTO_VIOLATION,
1110                         sizeof(error) + sizeof(sctp_paramhdr_t));
1111         sctp_addto_chunk(retval, sizeof(error), error);
1112         sctp_addto_param(retval, sizeof(sctp_paramhdr_t), param);
1113 
1114 nodata:
1115         return retval;
1116 }
1117 
1118 struct sctp_chunk *sctp_make_violation_max_retrans(
1119         const struct sctp_association *asoc,
1120         const struct sctp_chunk *chunk)
1121 {
1122         struct sctp_chunk *retval;
1123         static const char error[] = "Association exceeded its max_retans count";
1124         size_t payload_len = sizeof(error) + sizeof(sctp_errhdr_t);
1125 
1126         retval = sctp_make_abort(asoc, chunk, payload_len);
1127         if (!retval)
1128                 goto nodata;
1129 
1130         sctp_init_cause(retval, SCTP_ERROR_PROTO_VIOLATION, sizeof(error));
1131         sctp_addto_chunk(retval, sizeof(error), error);
1132 
1133 nodata:
1134         return retval;
1135 }
1136 
1137 /* Make a HEARTBEAT chunk.  */
1138 struct sctp_chunk *sctp_make_heartbeat(const struct sctp_association *asoc,
1139                                   const struct sctp_transport *transport)
1140 {
1141         struct sctp_chunk *retval;
1142         sctp_sender_hb_info_t hbinfo;
1143 
1144         retval = sctp_make_control(asoc, SCTP_CID_HEARTBEAT, 0,
1145                                    sizeof(hbinfo), GFP_ATOMIC);
1146 
1147         if (!retval)
1148                 goto nodata;
1149 
1150         hbinfo.param_hdr.type = SCTP_PARAM_HEARTBEAT_INFO;
1151         hbinfo.param_hdr.length = htons(sizeof(sctp_sender_hb_info_t));
1152         hbinfo.daddr = transport->ipaddr;
1153         hbinfo.sent_at = jiffies;
1154         hbinfo.hb_nonce = transport->hb_nonce;
1155 
1156         /* Cast away the 'const', as this is just telling the chunk
1157          * what transport it belongs to.
1158          */
1159         retval->transport = (struct sctp_transport *) transport;
1160         retval->subh.hbs_hdr = sctp_addto_chunk(retval, sizeof(hbinfo),
1161                                                 &hbinfo);
1162 
1163 nodata:
1164         return retval;
1165 }
1166 
1167 struct sctp_chunk *sctp_make_heartbeat_ack(const struct sctp_association *asoc,
1168                                       const struct sctp_chunk *chunk,
1169                                       const void *payload, const size_t paylen)
1170 {
1171         struct sctp_chunk *retval;
1172 
1173         retval  = sctp_make_control(asoc, SCTP_CID_HEARTBEAT_ACK, 0, paylen,
1174                                     GFP_ATOMIC);
1175         if (!retval)
1176                 goto nodata;
1177 
1178         retval->subh.hbs_hdr = sctp_addto_chunk(retval, paylen, payload);
1179 
1180         /* RFC 2960 6.4 Multi-homed SCTP Endpoints
1181          *
1182          * An endpoint SHOULD transmit reply chunks (e.g., SACK,
1183          * HEARTBEAT ACK, * etc.) to the same destination transport
1184          * address from which it * received the DATA or control chunk
1185          * to which it is replying.
1186          *
1187          * [HBACK back to where the HEARTBEAT came from.]
1188          */
1189         if (chunk)
1190                 retval->transport = chunk->transport;
1191 
1192 nodata:
1193         return retval;
1194 }
1195 
1196 /* Create an Operation Error chunk with the specified space reserved.
1197  * This routine can be used for containing multiple causes in the chunk.
1198  */
1199 static struct sctp_chunk *sctp_make_op_error_space(
1200         const struct sctp_association *asoc,
1201         const struct sctp_chunk *chunk,
1202         size_t size)
1203 {
1204         struct sctp_chunk *retval;
1205 
1206         retval = sctp_make_control(asoc, SCTP_CID_ERROR, 0,
1207                                    sizeof(sctp_errhdr_t) + size, GFP_ATOMIC);
1208         if (!retval)
1209                 goto nodata;
1210 
1211         /* RFC 2960 6.4 Multi-homed SCTP Endpoints
1212          *
1213          * An endpoint SHOULD transmit reply chunks (e.g., SACK,
1214          * HEARTBEAT ACK, etc.) to the same destination transport
1215          * address from which it received the DATA or control chunk
1216          * to which it is replying.
1217          *
1218          */
1219         if (chunk)
1220                 retval->transport = chunk->transport;
1221 
1222 nodata:
1223         return retval;
1224 }
1225 
1226 /* Create an Operation Error chunk of a fixed size,
1227  * specifically, max(asoc->pathmtu, SCTP_DEFAULT_MAXSEGMENT)
1228  * This is a helper function to allocate an error chunk for
1229  * for those invalid parameter codes in which we may not want
1230  * to report all the errors, if the incoming chunk is large
1231  */
1232 static inline struct sctp_chunk *sctp_make_op_error_fixed(
1233         const struct sctp_association *asoc,
1234         const struct sctp_chunk *chunk)
1235 {
1236         size_t size = asoc ? asoc->pathmtu : 0;
1237 
1238         if (!size)
1239                 size = SCTP_DEFAULT_MAXSEGMENT;
1240 
1241         return sctp_make_op_error_space(asoc, chunk, size);
1242 }
1243 
1244 /* Create an Operation Error chunk.  */
1245 struct sctp_chunk *sctp_make_op_error(const struct sctp_association *asoc,
1246                                  const struct sctp_chunk *chunk,
1247                                  __be16 cause_code, const void *payload,
1248                                  size_t paylen, size_t reserve_tail)
1249 {
1250         struct sctp_chunk *retval;
1251 
1252         retval = sctp_make_op_error_space(asoc, chunk, paylen + reserve_tail);
1253         if (!retval)
1254                 goto nodata;
1255 
1256         sctp_init_cause(retval, cause_code, paylen + reserve_tail);
1257         sctp_addto_chunk(retval, paylen, payload);
1258         if (reserve_tail)
1259                 sctp_addto_param(retval, reserve_tail, NULL);
1260 
1261 nodata:
1262         return retval;
1263 }
1264 
1265 struct sctp_chunk *sctp_make_auth(const struct sctp_association *asoc)
1266 {
1267         struct sctp_chunk *retval;
1268         struct sctp_hmac *hmac_desc;
1269         struct sctp_authhdr auth_hdr;
1270         __u8 *hmac;
1271 
1272         /* Get the first hmac that the peer told us to use */
1273         hmac_desc = sctp_auth_asoc_get_hmac(asoc);
1274         if (unlikely(!hmac_desc))
1275                 return NULL;
1276 
1277         retval = sctp_make_control(asoc, SCTP_CID_AUTH, 0,
1278                         hmac_desc->hmac_len + sizeof(sctp_authhdr_t),
1279                         GFP_ATOMIC);
1280         if (!retval)
1281                 return NULL;
1282 
1283         auth_hdr.hmac_id = htons(hmac_desc->hmac_id);
1284         auth_hdr.shkey_id = htons(asoc->active_key_id);
1285 
1286         retval->subh.auth_hdr = sctp_addto_chunk(retval, sizeof(sctp_authhdr_t),
1287                                                 &auth_hdr);
1288 
1289         hmac = skb_put(retval->skb, hmac_desc->hmac_len);
1290         memset(hmac, 0, hmac_desc->hmac_len);
1291 
1292         /* Adjust the chunk header to include the empty MAC */
1293         retval->chunk_hdr->length =
1294                 htons(ntohs(retval->chunk_hdr->length) + hmac_desc->hmac_len);
1295         retval->chunk_end = skb_tail_pointer(retval->skb);
1296 
1297         return retval;
1298 }
1299 
1300 
1301 /********************************************************************
1302  * 2nd Level Abstractions
1303  ********************************************************************/
1304 
1305 /* Turn an skb into a chunk.
1306  * FIXME: Eventually move the structure directly inside the skb->cb[].
1307  *
1308  * sctpimpguide-05.txt Section 2.8.2
1309  * M1) Each time a new DATA chunk is transmitted
1310  * set the 'TSN.Missing.Report' count for that TSN to 0. The
1311  * 'TSN.Missing.Report' count will be used to determine missing chunks
1312  * and when to fast retransmit.
1313  *
1314  */
1315 struct sctp_chunk *sctp_chunkify(struct sk_buff *skb,
1316                             const struct sctp_association *asoc,
1317                             struct sock *sk, gfp_t gfp)
1318 {
1319         struct sctp_chunk *retval;
1320 
1321         retval = kmem_cache_zalloc(sctp_chunk_cachep, gfp);
1322 
1323         if (!retval)
1324                 goto nodata;
1325         if (!sk)
1326                 pr_debug("%s: chunkifying skb:%p w/o an sk\n", __func__, skb);
1327 
1328         INIT_LIST_HEAD(&retval->list);
1329         retval->skb             = skb;
1330         retval->asoc            = (struct sctp_association *)asoc;
1331         retval->singleton       = 1;
1332 
1333         retval->fast_retransmit = SCTP_CAN_FRTX;
1334 
1335         /* Polish the bead hole.  */
1336         INIT_LIST_HEAD(&retval->transmitted_list);
1337         INIT_LIST_HEAD(&retval->frag_list);
1338         SCTP_DBG_OBJCNT_INC(chunk);
1339         atomic_set(&retval->refcnt, 1);
1340 
1341 nodata:
1342         return retval;
1343 }
1344 
1345 /* Set chunk->source and dest based on the IP header in chunk->skb.  */
1346 void sctp_init_addrs(struct sctp_chunk *chunk, union sctp_addr *src,
1347                      union sctp_addr *dest)
1348 {
1349         memcpy(&chunk->source, src, sizeof(union sctp_addr));
1350         memcpy(&chunk->dest, dest, sizeof(union sctp_addr));
1351 }
1352 
1353 /* Extract the source address from a chunk.  */
1354 const union sctp_addr *sctp_source(const struct sctp_chunk *chunk)
1355 {
1356         /* If we have a known transport, use that.  */
1357         if (chunk->transport) {
1358                 return &chunk->transport->ipaddr;
1359         } else {
1360                 /* Otherwise, extract it from the IP header.  */
1361                 return &chunk->source;
1362         }
1363 }
1364 
1365 /* Create a new chunk, setting the type and flags headers from the
1366  * arguments, reserving enough space for a 'paylen' byte payload.
1367  */
1368 static struct sctp_chunk *_sctp_make_chunk(const struct sctp_association *asoc,
1369                                             __u8 type, __u8 flags, int paylen,
1370                                             gfp_t gfp)
1371 {
1372         struct sctp_chunk *retval;
1373         sctp_chunkhdr_t *chunk_hdr;
1374         struct sk_buff *skb;
1375         struct sock *sk;
1376 
1377         /* No need to allocate LL here, as this is only a chunk. */
1378         skb = alloc_skb(WORD_ROUND(sizeof(sctp_chunkhdr_t) + paylen), gfp);
1379         if (!skb)
1380                 goto nodata;
1381 
1382         /* Make room for the chunk header.  */
1383         chunk_hdr = (sctp_chunkhdr_t *)skb_put(skb, sizeof(sctp_chunkhdr_t));
1384         chunk_hdr->type   = type;
1385         chunk_hdr->flags  = flags;
1386         chunk_hdr->length = htons(sizeof(sctp_chunkhdr_t));
1387 
1388         sk = asoc ? asoc->base.sk : NULL;
1389         retval = sctp_chunkify(skb, asoc, sk, gfp);
1390         if (!retval) {
1391                 kfree_skb(skb);
1392                 goto nodata;
1393         }
1394 
1395         retval->chunk_hdr = chunk_hdr;
1396         retval->chunk_end = ((__u8 *)chunk_hdr) + sizeof(struct sctp_chunkhdr);
1397 
1398         /* Determine if the chunk needs to be authenticated */
1399         if (sctp_auth_send_cid(type, asoc))
1400                 retval->auth = 1;
1401 
1402         return retval;
1403 nodata:
1404         return NULL;
1405 }
1406 
1407 static struct sctp_chunk *sctp_make_data(const struct sctp_association *asoc,
1408                                          __u8 flags, int paylen, gfp_t gfp)
1409 {
1410         return _sctp_make_chunk(asoc, SCTP_CID_DATA, flags, paylen, gfp);
1411 }
1412 
1413 static struct sctp_chunk *sctp_make_control(const struct sctp_association *asoc,
1414                                             __u8 type, __u8 flags, int paylen,
1415                                             gfp_t gfp)
1416 {
1417         struct sctp_chunk *chunk;
1418 
1419         chunk = _sctp_make_chunk(asoc, type, flags, paylen, gfp);
1420         if (chunk)
1421                 sctp_control_set_owner_w(chunk);
1422 
1423         return chunk;
1424 }
1425 
1426 /* Release the memory occupied by a chunk.  */
1427 static void sctp_chunk_destroy(struct sctp_chunk *chunk)
1428 {
1429         BUG_ON(!list_empty(&chunk->list));
1430         list_del_init(&chunk->transmitted_list);
1431 
1432         consume_skb(chunk->skb);
1433         consume_skb(chunk->auth_chunk);
1434 
1435         SCTP_DBG_OBJCNT_DEC(chunk);
1436         kmem_cache_free(sctp_chunk_cachep, chunk);
1437 }
1438 
1439 /* Possibly, free the chunk.  */
1440 void sctp_chunk_free(struct sctp_chunk *chunk)
1441 {
1442         /* Release our reference on the message tracker. */
1443         if (chunk->msg)
1444                 sctp_datamsg_put(chunk->msg);
1445 
1446         sctp_chunk_put(chunk);
1447 }
1448 
1449 /* Grab a reference to the chunk. */
1450 void sctp_chunk_hold(struct sctp_chunk *ch)
1451 {
1452         atomic_inc(&ch->refcnt);
1453 }
1454 
1455 /* Release a reference to the chunk. */
1456 void sctp_chunk_put(struct sctp_chunk *ch)
1457 {
1458         if (atomic_dec_and_test(&ch->refcnt))
1459                 sctp_chunk_destroy(ch);
1460 }
1461 
1462 /* Append bytes to the end of a chunk.  Will panic if chunk is not big
1463  * enough.
1464  */
1465 void *sctp_addto_chunk(struct sctp_chunk *chunk, int len, const void *data)
1466 {
1467         void *target;
1468         void *padding;
1469         int chunklen = ntohs(chunk->chunk_hdr->length);
1470         int padlen = WORD_ROUND(chunklen) - chunklen;
1471 
1472         padding = skb_put(chunk->skb, padlen);
1473         target = skb_put(chunk->skb, len);
1474 
1475         memset(padding, 0, padlen);
1476         memcpy(target, data, len);
1477 
1478         /* Adjust the chunk length field.  */
1479         chunk->chunk_hdr->length = htons(chunklen + padlen + len);
1480         chunk->chunk_end = skb_tail_pointer(chunk->skb);
1481 
1482         return target;
1483 }
1484 
1485 /* Append bytes to the end of a chunk. Returns NULL if there isn't sufficient
1486  * space in the chunk
1487  */
1488 static void *sctp_addto_chunk_fixed(struct sctp_chunk *chunk,
1489                                     int len, const void *data)
1490 {
1491         if (skb_tailroom(chunk->skb) >= len)
1492                 return sctp_addto_chunk(chunk, len, data);
1493         else
1494                 return NULL;
1495 }
1496 
1497 /* Append bytes from user space to the end of a chunk.  Will panic if
1498  * chunk is not big enough.
1499  * Returns a kernel err value.
1500  */
1501 int sctp_user_addto_chunk(struct sctp_chunk *chunk, int len,
1502                           struct iov_iter *from)
1503 {
1504         void *target;
1505         ssize_t copied;
1506 
1507         /* Make room in chunk for data.  */
1508         target = skb_put(chunk->skb, len);
1509 
1510         /* Copy data (whole iovec) into chunk */
1511         copied = copy_from_iter(target, len, from);
1512         if (copied != len)
1513                 return -EFAULT;
1514 
1515         /* Adjust the chunk length field.  */
1516         chunk->chunk_hdr->length =
1517                 htons(ntohs(chunk->chunk_hdr->length) + len);
1518         chunk->chunk_end = skb_tail_pointer(chunk->skb);
1519 
1520         return 0;
1521 }
1522 
1523 /* Helper function to assign a TSN if needed.  This assumes that both
1524  * the data_hdr and association have already been assigned.
1525  */
1526 void sctp_chunk_assign_ssn(struct sctp_chunk *chunk)
1527 {
1528         struct sctp_datamsg *msg;
1529         struct sctp_chunk *lchunk;
1530         struct sctp_stream *stream;
1531         __u16 ssn;
1532         __u16 sid;
1533 
1534         if (chunk->has_ssn)
1535                 return;
1536 
1537         /* All fragments will be on the same stream */
1538         sid = ntohs(chunk->subh.data_hdr->stream);
1539         stream = &chunk->asoc->ssnmap->out;
1540 
1541         /* Now assign the sequence number to the entire message.
1542          * All fragments must have the same stream sequence number.
1543          */
1544         msg = chunk->msg;
1545         list_for_each_entry(lchunk, &msg->chunks, frag_list) {
1546                 if (lchunk->chunk_hdr->flags & SCTP_DATA_UNORDERED) {
1547                         ssn = 0;
1548                 } else {
1549                         if (lchunk->chunk_hdr->flags & SCTP_DATA_LAST_FRAG)
1550                                 ssn = sctp_ssn_next(stream, sid);
1551                         else
1552                                 ssn = sctp_ssn_peek(stream, sid);
1553                 }
1554 
1555                 lchunk->subh.data_hdr->ssn = htons(ssn);
1556                 lchunk->has_ssn = 1;
1557         }
1558 }
1559 
1560 /* Helper function to assign a TSN if needed.  This assumes that both
1561  * the data_hdr and association have already been assigned.
1562  */
1563 void sctp_chunk_assign_tsn(struct sctp_chunk *chunk)
1564 {
1565         if (!chunk->has_tsn) {
1566                 /* This is the last possible instant to
1567                  * assign a TSN.
1568                  */
1569                 chunk->subh.data_hdr->tsn =
1570                         htonl(sctp_association_get_next_tsn(chunk->asoc));
1571                 chunk->has_tsn = 1;
1572         }
1573 }
1574 
1575 /* Create a CLOSED association to use with an incoming packet.  */
1576 struct sctp_association *sctp_make_temp_asoc(const struct sctp_endpoint *ep,
1577                                         struct sctp_chunk *chunk,
1578                                         gfp_t gfp)
1579 {
1580         struct sctp_association *asoc;
1581         struct sk_buff *skb;
1582         sctp_scope_t scope;
1583 
1584         /* Create the bare association.  */
1585         scope = sctp_scope(sctp_source(chunk));
1586         asoc = sctp_association_new(ep, ep->base.sk, scope, gfp);
1587         if (!asoc)
1588                 goto nodata;
1589         asoc->temp = 1;
1590         skb = chunk->skb;
1591         /* Create an entry for the source address of the packet.  */
1592         SCTP_INPUT_CB(skb)->af->from_skb(&asoc->c.peer_addr, skb, 1);
1593 
1594 nodata:
1595         return asoc;
1596 }
1597 
1598 /* Build a cookie representing asoc.
1599  * This INCLUDES the param header needed to put the cookie in the INIT ACK.
1600  */
1601 static sctp_cookie_param_t *sctp_pack_cookie(const struct sctp_endpoint *ep,
1602                                       const struct sctp_association *asoc,
1603                                       const struct sctp_chunk *init_chunk,
1604                                       int *cookie_len,
1605                                       const __u8 *raw_addrs, int addrs_len)
1606 {
1607         sctp_cookie_param_t *retval;
1608         struct sctp_signed_cookie *cookie;
1609         int headersize, bodysize;
1610 
1611         /* Header size is static data prior to the actual cookie, including
1612          * any padding.
1613          */
1614         headersize = sizeof(sctp_paramhdr_t) +
1615                      (sizeof(struct sctp_signed_cookie) -
1616                       sizeof(struct sctp_cookie));
1617         bodysize = sizeof(struct sctp_cookie)
1618                 + ntohs(init_chunk->chunk_hdr->length) + addrs_len;
1619 
1620         /* Pad out the cookie to a multiple to make the signature
1621          * functions simpler to write.
1622          */
1623         if (bodysize % SCTP_COOKIE_MULTIPLE)
1624                 bodysize += SCTP_COOKIE_MULTIPLE
1625                         - (bodysize % SCTP_COOKIE_MULTIPLE);
1626         *cookie_len = headersize + bodysize;
1627 
1628         /* Clear this memory since we are sending this data structure
1629          * out on the network.
1630          */
1631         retval = kzalloc(*cookie_len, GFP_ATOMIC);
1632         if (!retval)
1633                 goto nodata;
1634 
1635         cookie = (struct sctp_signed_cookie *) retval->body;
1636 
1637         /* Set up the parameter header.  */
1638         retval->p.type = SCTP_PARAM_STATE_COOKIE;
1639         retval->p.length = htons(*cookie_len);
1640 
1641         /* Copy the cookie part of the association itself.  */
1642         cookie->c = asoc->c;
1643         /* Save the raw address list length in the cookie. */
1644         cookie->c.raw_addr_list_len = addrs_len;
1645 
1646         /* Remember PR-SCTP capability. */
1647         cookie->c.prsctp_capable = asoc->peer.prsctp_capable;
1648 
1649         /* Save adaptation indication in the cookie. */
1650         cookie->c.adaptation_ind = asoc->peer.adaptation_ind;
1651 
1652         /* Set an expiration time for the cookie.  */
1653         cookie->c.expiration = ktime_add(asoc->cookie_life,
1654                                          ktime_get_real());
1655 
1656         /* Copy the peer's init packet.  */
1657         memcpy(&cookie->c.peer_init[0], init_chunk->chunk_hdr,
1658                ntohs(init_chunk->chunk_hdr->length));
1659 
1660         /* Copy the raw local address list of the association. */
1661         memcpy((__u8 *)&cookie->c.peer_init[0] +
1662                ntohs(init_chunk->chunk_hdr->length), raw_addrs, addrs_len);
1663 
1664         if (sctp_sk(ep->base.sk)->hmac) {
1665                 SHASH_DESC_ON_STACK(desc, sctp_sk(ep->base.sk)->hmac);
1666                 int err;
1667 
1668                 /* Sign the message.  */
1669                 desc->tfm = sctp_sk(ep->base.sk)->hmac;
1670                 desc->flags = 0;
1671 
1672                 err = crypto_shash_setkey(desc->tfm, ep->secret_key,
1673                                           sizeof(ep->secret_key)) ?:
1674                       crypto_shash_digest(desc, (u8 *)&cookie->c, bodysize,
1675                                           cookie->signature);
1676                 shash_desc_zero(desc);
1677                 if (err)
1678                         goto free_cookie;
1679         }
1680 
1681         return retval;
1682 
1683 free_cookie:
1684         kfree(retval);
1685 nodata:
1686         *cookie_len = 0;
1687         return NULL;
1688 }
1689 
1690 /* Unpack the cookie from COOKIE ECHO chunk, recreating the association.  */
1691 struct sctp_association *sctp_unpack_cookie(
1692         const struct sctp_endpoint *ep,
1693         const struct sctp_association *asoc,
1694         struct sctp_chunk *chunk, gfp_t gfp,
1695         int *error, struct sctp_chunk **errp)
1696 {
1697         struct sctp_association *retval = NULL;
1698         struct sctp_signed_cookie *cookie;
1699         struct sctp_cookie *bear_cookie;
1700         int headersize, bodysize, fixed_size;
1701         __u8 *digest = ep->digest;
1702         unsigned int len;
1703         sctp_scope_t scope;
1704         struct sk_buff *skb = chunk->skb;
1705         ktime_t kt;
1706 
1707         /* Header size is static data prior to the actual cookie, including
1708          * any padding.
1709          */
1710         headersize = sizeof(sctp_chunkhdr_t) +
1711                      (sizeof(struct sctp_signed_cookie) -
1712                       sizeof(struct sctp_cookie));
1713         bodysize = ntohs(chunk->chunk_hdr->length) - headersize;
1714         fixed_size = headersize + sizeof(struct sctp_cookie);
1715 
1716         /* Verify that the chunk looks like it even has a cookie.
1717          * There must be enough room for our cookie and our peer's
1718          * INIT chunk.
1719          */
1720         len = ntohs(chunk->chunk_hdr->length);
1721         if (len < fixed_size + sizeof(struct sctp_chunkhdr))
1722                 goto malformed;
1723 
1724         /* Verify that the cookie has been padded out. */
1725         if (bodysize % SCTP_COOKIE_MULTIPLE)
1726                 goto malformed;
1727 
1728         /* Process the cookie.  */
1729         cookie = chunk->subh.cookie_hdr;
1730         bear_cookie = &cookie->c;
1731 
1732         if (!sctp_sk(ep->base.sk)->hmac)
1733                 goto no_hmac;
1734 
1735         /* Check the signature.  */
1736         {
1737                 SHASH_DESC_ON_STACK(desc, sctp_sk(ep->base.sk)->hmac);
1738                 int err;
1739 
1740                 desc->tfm = sctp_sk(ep->base.sk)->hmac;
1741                 desc->flags = 0;
1742 
1743                 err = crypto_shash_setkey(desc->tfm, ep->secret_key,
1744                                           sizeof(ep->secret_key)) ?:
1745                       crypto_shash_digest(desc, (u8 *)bear_cookie, bodysize,
1746                                           digest);
1747                 shash_desc_zero(desc);
1748 
1749                 if (err) {
1750                         *error = -SCTP_IERROR_NOMEM;
1751                         goto fail;
1752                 }
1753         }
1754 
1755         if (memcmp(digest, cookie->signature, SCTP_SIGNATURE_SIZE)) {
1756                 *error = -SCTP_IERROR_BAD_SIG;
1757                 goto fail;
1758         }
1759 
1760 no_hmac:
1761         /* IG Section 2.35.2:
1762          *  3) Compare the port numbers and the verification tag contained
1763          *     within the COOKIE ECHO chunk to the actual port numbers and the
1764          *     verification tag within the SCTP common header of the received
1765          *     packet. If these values do not match the packet MUST be silently
1766          *     discarded,
1767          */
1768         if (ntohl(chunk->sctp_hdr->vtag) != bear_cookie->my_vtag) {
1769                 *error = -SCTP_IERROR_BAD_TAG;
1770                 goto fail;
1771         }
1772 
1773         if (chunk->sctp_hdr->source != bear_cookie->peer_addr.v4.sin_port ||
1774             ntohs(chunk->sctp_hdr->dest) != bear_cookie->my_port) {
1775                 *error = -SCTP_IERROR_BAD_PORTS;
1776                 goto fail;
1777         }
1778 
1779         /* Check to see if the cookie is stale.  If there is already
1780          * an association, there is no need to check cookie's expiration
1781          * for init collision case of lost COOKIE ACK.
1782          * If skb has been timestamped, then use the stamp, otherwise
1783          * use current time.  This introduces a small possibility that
1784          * that a cookie may be considered expired, but his would only slow
1785          * down the new association establishment instead of every packet.
1786          */
1787         if (sock_flag(ep->base.sk, SOCK_TIMESTAMP))
1788                 kt = skb_get_ktime(skb);
1789         else
1790                 kt = ktime_get_real();
1791 
1792         if (!asoc && ktime_before(bear_cookie->expiration, kt)) {
1793                 /*
1794                  * Section 3.3.10.3 Stale Cookie Error (3)
1795                  *
1796                  * Cause of error
1797                  * ---------------
1798                  * Stale Cookie Error:  Indicates the receipt of a valid State
1799                  * Cookie that has expired.
1800                  */
1801                 len = ntohs(chunk->chunk_hdr->length);
1802                 *errp = sctp_make_op_error_space(asoc, chunk, len);
1803                 if (*errp) {
1804                         suseconds_t usecs = ktime_to_us(ktime_sub(kt, bear_cookie->expiration));
1805                         __be32 n = htonl(usecs);
1806 
1807                         sctp_init_cause(*errp, SCTP_ERROR_STALE_COOKIE,
1808                                         sizeof(n));
1809                         sctp_addto_chunk(*errp, sizeof(n), &n);
1810                         *error = -SCTP_IERROR_STALE_COOKIE;
1811                 } else
1812                         *error = -SCTP_IERROR_NOMEM;
1813 
1814                 goto fail;
1815         }
1816 
1817         /* Make a new base association.  */
1818         scope = sctp_scope(sctp_source(chunk));
1819         retval = sctp_association_new(ep, ep->base.sk, scope, gfp);
1820         if (!retval) {
1821                 *error = -SCTP_IERROR_NOMEM;
1822                 goto fail;
1823         }
1824 
1825         /* Set up our peer's port number.  */
1826         retval->peer.port = ntohs(chunk->sctp_hdr->source);
1827 
1828         /* Populate the association from the cookie.  */
1829         memcpy(&retval->c, bear_cookie, sizeof(*bear_cookie));
1830 
1831         if (sctp_assoc_set_bind_addr_from_cookie(retval, bear_cookie,
1832                                                  GFP_ATOMIC) < 0) {
1833                 *error = -SCTP_IERROR_NOMEM;
1834                 goto fail;
1835         }
1836 
1837         /* Also, add the destination address. */
1838         if (list_empty(&retval->base.bind_addr.address_list)) {
1839                 sctp_add_bind_addr(&retval->base.bind_addr, &chunk->dest,
1840                                    sizeof(chunk->dest), SCTP_ADDR_SRC,
1841                                    GFP_ATOMIC);
1842         }
1843 
1844         retval->next_tsn = retval->c.initial_tsn;
1845         retval->ctsn_ack_point = retval->next_tsn - 1;
1846         retval->addip_serial = retval->c.initial_tsn;
1847         retval->adv_peer_ack_point = retval->ctsn_ack_point;
1848         retval->peer.prsctp_capable = retval->c.prsctp_capable;
1849         retval->peer.adaptation_ind = retval->c.adaptation_ind;
1850 
1851         /* The INIT stuff will be done by the side effects.  */
1852         return retval;
1853 
1854 fail:
1855         if (retval)
1856                 sctp_association_free(retval);
1857 
1858         return NULL;
1859 
1860 malformed:
1861         /* Yikes!  The packet is either corrupt or deliberately
1862          * malformed.
1863          */
1864         *error = -SCTP_IERROR_MALFORMED;
1865         goto fail;
1866 }
1867 
1868 /********************************************************************
1869  * 3rd Level Abstractions
1870  ********************************************************************/
1871 
1872 struct __sctp_missing {
1873         __be32 num_missing;
1874         __be16 type;
1875 }  __packed;
1876 
1877 /*
1878  * Report a missing mandatory parameter.
1879  */
1880 static int sctp_process_missing_param(const struct sctp_association *asoc,
1881                                       sctp_param_t paramtype,
1882                                       struct sctp_chunk *chunk,
1883                                       struct sctp_chunk **errp)
1884 {
1885         struct __sctp_missing report;
1886         __u16 len;
1887 
1888         len = WORD_ROUND(sizeof(report));
1889 
1890         /* Make an ERROR chunk, preparing enough room for
1891          * returning multiple unknown parameters.
1892          */
1893         if (!*errp)
1894                 *errp = sctp_make_op_error_space(asoc, chunk, len);
1895 
1896         if (*errp) {
1897                 report.num_missing = htonl(1);
1898                 report.type = paramtype;
1899                 sctp_init_cause(*errp, SCTP_ERROR_MISS_PARAM,
1900                                 sizeof(report));
1901                 sctp_addto_chunk(*errp, sizeof(report), &report);
1902         }
1903 
1904         /* Stop processing this chunk. */
1905         return 0;
1906 }
1907 
1908 /* Report an Invalid Mandatory Parameter.  */
1909 static int sctp_process_inv_mandatory(const struct sctp_association *asoc,
1910                                       struct sctp_chunk *chunk,
1911                                       struct sctp_chunk **errp)
1912 {
1913         /* Invalid Mandatory Parameter Error has no payload. */
1914 
1915         if (!*errp)
1916                 *errp = sctp_make_op_error_space(asoc, chunk, 0);
1917 
1918         if (*errp)
1919                 sctp_init_cause(*errp, SCTP_ERROR_INV_PARAM, 0);
1920 
1921         /* Stop processing this chunk. */
1922         return 0;
1923 }
1924 
1925 static int sctp_process_inv_paramlength(const struct sctp_association *asoc,
1926                                         struct sctp_paramhdr *param,
1927                                         const struct sctp_chunk *chunk,
1928                                         struct sctp_chunk **errp)
1929 {
1930         /* This is a fatal error.  Any accumulated non-fatal errors are
1931          * not reported.
1932          */
1933         if (*errp)
1934                 sctp_chunk_free(*errp);
1935 
1936         /* Create an error chunk and fill it in with our payload. */
1937         *errp = sctp_make_violation_paramlen(asoc, chunk, param);
1938 
1939         return 0;
1940 }
1941 
1942 
1943 /* Do not attempt to handle the HOST_NAME parm.  However, do
1944  * send back an indicator to the peer.
1945  */
1946 static int sctp_process_hn_param(const struct sctp_association *asoc,
1947                                  union sctp_params param,
1948                                  struct sctp_chunk *chunk,
1949                                  struct sctp_chunk **errp)
1950 {
1951         __u16 len = ntohs(param.p->length);
1952 
1953         /* Processing of the HOST_NAME parameter will generate an
1954          * ABORT.  If we've accumulated any non-fatal errors, they
1955          * would be unrecognized parameters and we should not include
1956          * them in the ABORT.
1957          */
1958         if (*errp)
1959                 sctp_chunk_free(*errp);
1960 
1961         *errp = sctp_make_op_error_space(asoc, chunk, len);
1962 
1963         if (*errp) {
1964                 sctp_init_cause(*errp, SCTP_ERROR_DNS_FAILED, len);
1965                 sctp_addto_chunk(*errp, len, param.v);
1966         }
1967 
1968         /* Stop processing this chunk. */
1969         return 0;
1970 }
1971 
1972 static int sctp_verify_ext_param(struct net *net, union sctp_params param)
1973 {
1974         __u16 num_ext = ntohs(param.p->length) - sizeof(sctp_paramhdr_t);
1975         int have_auth = 0;
1976         int have_asconf = 0;
1977         int i;
1978 
1979         for (i = 0; i < num_ext; i++) {
1980                 switch (param.ext->chunks[i]) {
1981                 case SCTP_CID_AUTH:
1982                         have_auth = 1;
1983                         break;
1984                 case SCTP_CID_ASCONF:
1985                 case SCTP_CID_ASCONF_ACK:
1986                         have_asconf = 1;
1987                         break;
1988                 }
1989         }
1990 
1991         /* ADD-IP Security: The draft requires us to ABORT or ignore the
1992          * INIT/INIT-ACK if ADD-IP is listed, but AUTH is not.  Do this
1993          * only if ADD-IP is turned on and we are not backward-compatible
1994          * mode.
1995          */
1996         if (net->sctp.addip_noauth)
1997                 return 1;
1998 
1999         if (net->sctp.addip_enable && !have_auth && have_asconf)
2000                 return 0;
2001 
2002         return 1;
2003 }
2004 
2005 static void sctp_process_ext_param(struct sctp_association *asoc,
2006                                     union sctp_params param)
2007 {
2008         struct net *net = sock_net(asoc->base.sk);
2009         __u16 num_ext = ntohs(param.p->length) - sizeof(sctp_paramhdr_t);
2010         int i;
2011 
2012         for (i = 0; i < num_ext; i++) {
2013                 switch (param.ext->chunks[i]) {
2014                 case SCTP_CID_FWD_TSN:
2015                         if (asoc->prsctp_enable && !asoc->peer.prsctp_capable)
2016                                 asoc->peer.prsctp_capable = 1;
2017                         break;
2018                 case SCTP_CID_AUTH:
2019                         /* if the peer reports AUTH, assume that he
2020                          * supports AUTH.
2021                          */
2022                         if (asoc->ep->auth_enable)
2023                                 asoc->peer.auth_capable = 1;
2024                         break;
2025                 case SCTP_CID_ASCONF:
2026                 case SCTP_CID_ASCONF_ACK:
2027                         if (net->sctp.addip_enable)
2028                                 asoc->peer.asconf_capable = 1;
2029                         break;
2030                 default:
2031                         break;
2032                 }
2033         }
2034 }
2035 
2036 /* RFC 3.2.1 & the Implementers Guide 2.2.
2037  *
2038  * The Parameter Types are encoded such that the
2039  * highest-order two bits specify the action that must be
2040  * taken if the processing endpoint does not recognize the
2041  * Parameter Type.
2042  *
2043  * 00 - Stop processing this parameter; do not process any further
2044  *      parameters within this chunk
2045  *
2046  * 01 - Stop processing this parameter, do not process any further
2047  *      parameters within this chunk, and report the unrecognized
2048  *      parameter in an 'Unrecognized Parameter' ERROR chunk.
2049  *
2050  * 10 - Skip this parameter and continue processing.
2051  *
2052  * 11 - Skip this parameter and continue processing but
2053  *      report the unrecognized parameter in an
2054  *      'Unrecognized Parameter' ERROR chunk.
2055  *
2056  * Return value:
2057  *      SCTP_IERROR_NO_ERROR - continue with the chunk
2058  *      SCTP_IERROR_ERROR    - stop and report an error.
2059  *      SCTP_IERROR_NOMEME   - out of memory.
2060  */
2061 static sctp_ierror_t sctp_process_unk_param(const struct sctp_association *asoc,
2062                                             union sctp_params param,
2063                                             struct sctp_chunk *chunk,
2064                                             struct sctp_chunk **errp)
2065 {
2066         int retval = SCTP_IERROR_NO_ERROR;
2067 
2068         switch (param.p->type & SCTP_PARAM_ACTION_MASK) {
2069         case SCTP_PARAM_ACTION_DISCARD:
2070                 retval =  SCTP_IERROR_ERROR;
2071                 break;
2072         case SCTP_PARAM_ACTION_SKIP:
2073                 break;
2074         case SCTP_PARAM_ACTION_DISCARD_ERR:
2075                 retval =  SCTP_IERROR_ERROR;
2076                 /* Fall through */
2077         case SCTP_PARAM_ACTION_SKIP_ERR:
2078                 /* Make an ERROR chunk, preparing enough room for
2079                  * returning multiple unknown parameters.
2080                  */
2081                 if (NULL == *errp)
2082                         *errp = sctp_make_op_error_fixed(asoc, chunk);
2083 
2084                 if (*errp) {
2085                         if (!sctp_init_cause_fixed(*errp, SCTP_ERROR_UNKNOWN_PARAM,
2086                                         WORD_ROUND(ntohs(param.p->length))))
2087                                 sctp_addto_chunk_fixed(*errp,
2088                                                 WORD_ROUND(ntohs(param.p->length)),
2089                                                 param.v);
2090                 } else {
2091                         /* If there is no memory for generating the ERROR
2092                          * report as specified, an ABORT will be triggered
2093                          * to the peer and the association won't be
2094                          * established.
2095                          */
2096                         retval = SCTP_IERROR_NOMEM;
2097                 }
2098                 break;
2099         default:
2100                 break;
2101         }
2102 
2103         return retval;
2104 }
2105 
2106 /* Verify variable length parameters
2107  * Return values:
2108  *      SCTP_IERROR_ABORT - trigger an ABORT
2109  *      SCTP_IERROR_NOMEM - out of memory (abort)
2110  *      SCTP_IERROR_ERROR - stop processing, trigger an ERROR
2111  *      SCTP_IERROR_NO_ERROR - continue with the chunk
2112  */
2113 static sctp_ierror_t sctp_verify_param(struct net *net,
2114                                         const struct sctp_endpoint *ep,
2115                                         const struct sctp_association *asoc,
2116                                         union sctp_params param,
2117                                         sctp_cid_t cid,
2118                                         struct sctp_chunk *chunk,
2119                                         struct sctp_chunk **err_chunk)
2120 {
2121         struct sctp_hmac_algo_param *hmacs;
2122         int retval = SCTP_IERROR_NO_ERROR;
2123         __u16 n_elt, id = 0;
2124         int i;
2125 
2126         /* FIXME - This routine is not looking at each parameter per the
2127          * chunk type, i.e., unrecognized parameters should be further
2128          * identified based on the chunk id.
2129          */
2130 
2131         switch (param.p->type) {
2132         case SCTP_PARAM_IPV4_ADDRESS:
2133         case SCTP_PARAM_IPV6_ADDRESS:
2134         case SCTP_PARAM_COOKIE_PRESERVATIVE:
2135         case SCTP_PARAM_SUPPORTED_ADDRESS_TYPES:
2136         case SCTP_PARAM_STATE_COOKIE:
2137         case SCTP_PARAM_HEARTBEAT_INFO:
2138         case SCTP_PARAM_UNRECOGNIZED_PARAMETERS:
2139         case SCTP_PARAM_ECN_CAPABLE:
2140         case SCTP_PARAM_ADAPTATION_LAYER_IND:
2141                 break;
2142 
2143         case SCTP_PARAM_SUPPORTED_EXT:
2144                 if (!sctp_verify_ext_param(net, param))
2145                         return SCTP_IERROR_ABORT;
2146                 break;
2147 
2148         case SCTP_PARAM_SET_PRIMARY:
2149                 if (net->sctp.addip_enable)
2150                         break;
2151                 goto fallthrough;
2152 
2153         case SCTP_PARAM_HOST_NAME_ADDRESS:
2154                 /* Tell the peer, we won't support this param.  */
2155                 sctp_process_hn_param(asoc, param, chunk, err_chunk);
2156                 retval = SCTP_IERROR_ABORT;
2157                 break;
2158 
2159         case SCTP_PARAM_FWD_TSN_SUPPORT:
2160                 if (ep->prsctp_enable)
2161                         break;
2162                 goto fallthrough;
2163 
2164         case SCTP_PARAM_RANDOM:
2165                 if (!ep->auth_enable)
2166                         goto fallthrough;
2167 
2168                 /* SCTP-AUTH: Secion 6.1
2169                  * If the random number is not 32 byte long the association
2170                  * MUST be aborted.  The ABORT chunk SHOULD contain the error
2171                  * cause 'Protocol Violation'.
2172                  */
2173                 if (SCTP_AUTH_RANDOM_LENGTH !=
2174                         ntohs(param.p->length) - sizeof(sctp_paramhdr_t)) {
2175                         sctp_process_inv_paramlength(asoc, param.p,
2176                                                         chunk, err_chunk);
2177                         retval = SCTP_IERROR_ABORT;
2178                 }
2179                 break;
2180 
2181         case SCTP_PARAM_CHUNKS:
2182                 if (!ep->auth_enable)
2183                         goto fallthrough;
2184 
2185                 /* SCTP-AUTH: Section 3.2
2186                  * The CHUNKS parameter MUST be included once in the INIT or
2187                  *  INIT-ACK chunk if the sender wants to receive authenticated
2188                  *  chunks.  Its maximum length is 260 bytes.
2189                  */
2190                 if (260 < ntohs(param.p->length)) {
2191                         sctp_process_inv_paramlength(asoc, param.p,
2192                                                      chunk, err_chunk);
2193                         retval = SCTP_IERROR_ABORT;
2194                 }
2195                 break;
2196 
2197         case SCTP_PARAM_HMAC_ALGO:
2198                 if (!ep->auth_enable)
2199                         goto fallthrough;
2200 
2201                 hmacs = (struct sctp_hmac_algo_param *)param.p;
2202                 n_elt = (ntohs(param.p->length) - sizeof(sctp_paramhdr_t)) >> 1;
2203 
2204                 /* SCTP-AUTH: Section 6.1
2205                  * The HMAC algorithm based on SHA-1 MUST be supported and
2206                  * included in the HMAC-ALGO parameter.
2207                  */
2208                 for (i = 0; i < n_elt; i++) {
2209                         id = ntohs(hmacs->hmac_ids[i]);
2210 
2211                         if (id == SCTP_AUTH_HMAC_ID_SHA1)
2212                                 break;
2213                 }
2214 
2215                 if (id != SCTP_AUTH_HMAC_ID_SHA1) {
2216                         sctp_process_inv_paramlength(asoc, param.p, chunk,
2217                                                      err_chunk);
2218                         retval = SCTP_IERROR_ABORT;
2219                 }
2220                 break;
2221 fallthrough:
2222         default:
2223                 pr_debug("%s: unrecognized param:%d for chunk:%d\n",
2224                          __func__, ntohs(param.p->type), cid);
2225 
2226                 retval = sctp_process_unk_param(asoc, param, chunk, err_chunk);
2227                 break;
2228         }
2229         return retval;
2230 }
2231 
2232 /* Verify the INIT packet before we process it.  */
2233 int sctp_verify_init(struct net *net, const struct sctp_endpoint *ep,
2234                      const struct sctp_association *asoc, sctp_cid_t cid,
2235                      sctp_init_chunk_t *peer_init, struct sctp_chunk *chunk,
2236                      struct sctp_chunk **errp)
2237 {
2238         union sctp_params param;
2239         bool has_cookie = false;
2240         int result;
2241 
2242         /* Check for missing mandatory parameters. Note: Initial TSN is
2243          * also mandatory, but is not checked here since the valid range
2244          * is 0..2**32-1. RFC4960, section 3.3.3.
2245          */
2246         if (peer_init->init_hdr.num_outbound_streams == 0 ||
2247             peer_init->init_hdr.num_inbound_streams == 0 ||
2248             peer_init->init_hdr.init_tag == 0 ||
2249             ntohl(peer_init->init_hdr.a_rwnd) < SCTP_DEFAULT_MINWINDOW)
2250                 return sctp_process_inv_mandatory(asoc, chunk, errp);
2251 
2252         sctp_walk_params(param, peer_init, init_hdr.params) {
2253                 if (param.p->type == SCTP_PARAM_STATE_COOKIE)
2254                         has_cookie = true;
2255         }
2256 
2257         /* There is a possibility that a parameter length was bad and
2258          * in that case we would have stoped walking the parameters.
2259          * The current param.p would point at the bad one.
2260          * Current consensus on the mailing list is to generate a PROTOCOL
2261          * VIOLATION error.  We build the ERROR chunk here and let the normal
2262          * error handling code build and send the packet.
2263          */
2264         if (param.v != (void *)chunk->chunk_end)
2265                 return sctp_process_inv_paramlength(asoc, param.p, chunk, errp);
2266 
2267         /* The only missing mandatory param possible today is
2268          * the state cookie for an INIT-ACK chunk.
2269          */
2270         if ((SCTP_CID_INIT_ACK == cid) && !has_cookie)
2271                 return sctp_process_missing_param(asoc, SCTP_PARAM_STATE_COOKIE,
2272                                                   chunk, errp);
2273 
2274         /* Verify all the variable length parameters */
2275         sctp_walk_params(param, peer_init, init_hdr.params) {
2276                 result = sctp_verify_param(net, ep, asoc, param, cid,
2277                                            chunk, errp);
2278                 switch (result) {
2279                 case SCTP_IERROR_ABORT:
2280                 case SCTP_IERROR_NOMEM:
2281                         return 0;
2282                 case SCTP_IERROR_ERROR:
2283                         return 1;
2284                 case SCTP_IERROR_NO_ERROR:
2285                 default:
2286                         break;
2287                 }
2288 
2289         } /* for (loop through all parameters) */
2290 
2291         return 1;
2292 }
2293 
2294 /* Unpack the parameters in an INIT packet into an association.
2295  * Returns 0 on failure, else success.
2296  * FIXME:  This is an association method.
2297  */
2298 int sctp_process_init(struct sctp_association *asoc, struct sctp_chunk *chunk,
2299                       const union sctp_addr *peer_addr,
2300                       sctp_init_chunk_t *peer_init, gfp_t gfp)
2301 {
2302         struct net *net = sock_net(asoc->base.sk);
2303         union sctp_params param;
2304         struct sctp_transport *transport;
2305         struct list_head *pos, *temp;
2306         struct sctp_af *af;
2307         union sctp_addr addr;
2308         char *cookie;
2309         int src_match = 0;
2310 
2311         /* We must include the address that the INIT packet came from.
2312          * This is the only address that matters for an INIT packet.
2313          * When processing a COOKIE ECHO, we retrieve the from address
2314          * of the INIT from the cookie.
2315          */
2316 
2317         /* This implementation defaults to making the first transport
2318          * added as the primary transport.  The source address seems to
2319          * be a a better choice than any of the embedded addresses.
2320          */
2321         if (!sctp_assoc_add_peer(asoc, peer_addr, gfp, SCTP_ACTIVE))
2322                 goto nomem;
2323 
2324         if (sctp_cmp_addr_exact(sctp_source(chunk), peer_addr))
2325                 src_match = 1;
2326 
2327         /* Process the initialization parameters.  */
2328         sctp_walk_params(param, peer_init, init_hdr.params) {
2329                 if (!src_match && (param.p->type == SCTP_PARAM_IPV4_ADDRESS ||
2330                     param.p->type == SCTP_PARAM_IPV6_ADDRESS)) {
2331                         af = sctp_get_af_specific(param_type2af(param.p->type));
2332                         af->from_addr_param(&addr, param.addr,
2333                                             chunk->sctp_hdr->source, 0);
2334                         if (sctp_cmp_addr_exact(sctp_source(chunk), &addr))
2335                                 src_match = 1;
2336                 }
2337 
2338                 if (!sctp_process_param(asoc, param, peer_addr, gfp))
2339                         goto clean_up;
2340         }
2341 
2342         /* source address of chunk may not match any valid address */
2343         if (!src_match)
2344                 goto clean_up;
2345 
2346         /* AUTH: After processing the parameters, make sure that we
2347          * have all the required info to potentially do authentications.
2348          */
2349         if (asoc->peer.auth_capable && (!asoc->peer.peer_random ||
2350                                         !asoc->peer.peer_hmacs))
2351                 asoc->peer.auth_capable = 0;
2352 
2353         /* In a non-backward compatible mode, if the peer claims
2354          * support for ADD-IP but not AUTH,  the ADD-IP spec states
2355          * that we MUST ABORT the association. Section 6.  The section
2356          * also give us an option to silently ignore the packet, which
2357          * is what we'll do here.
2358          */
2359         if (!net->sctp.addip_noauth &&
2360              (asoc->peer.asconf_capable && !asoc->peer.auth_capable)) {
2361                 asoc->peer.addip_disabled_mask |= (SCTP_PARAM_ADD_IP |
2362                                                   SCTP_PARAM_DEL_IP |
2363                                                   SCTP_PARAM_SET_PRIMARY);
2364                 asoc->peer.asconf_capable = 0;
2365                 goto clean_up;
2366         }
2367 
2368         /* Walk list of transports, removing transports in the UNKNOWN state. */
2369         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
2370                 transport = list_entry(pos, struct sctp_transport, transports);
2371                 if (transport->state == SCTP_UNKNOWN) {
2372                         sctp_assoc_rm_peer(asoc, transport);
2373                 }
2374         }
2375 
2376         /* The fixed INIT headers are always in network byte
2377          * order.
2378          */
2379         asoc->peer.i.init_tag =
2380                 ntohl(peer_init->init_hdr.init_tag);
2381         asoc->peer.i.a_rwnd =
2382                 ntohl(peer_init->init_hdr.a_rwnd);
2383         asoc->peer.i.num_outbound_streams =
2384                 ntohs(peer_init->init_hdr.num_outbound_streams);
2385         asoc->peer.i.num_inbound_streams =
2386                 ntohs(peer_init->init_hdr.num_inbound_streams);
2387         asoc->peer.i.initial_tsn =
2388                 ntohl(peer_init->init_hdr.initial_tsn);
2389 
2390         /* Apply the upper bounds for output streams based on peer's
2391          * number of inbound streams.
2392          */
2393         if (asoc->c.sinit_num_ostreams  >
2394             ntohs(peer_init->init_hdr.num_inbound_streams)) {
2395                 asoc->c.sinit_num_ostreams =
2396                         ntohs(peer_init->init_hdr.num_inbound_streams);
2397         }
2398 
2399         if (asoc->c.sinit_max_instreams >
2400             ntohs(peer_init->init_hdr.num_outbound_streams)) {
2401                 asoc->c.sinit_max_instreams =
2402                         ntohs(peer_init->init_hdr.num_outbound_streams);
2403         }
2404 
2405         /* Copy Initiation tag from INIT to VT_peer in cookie.   */
2406         asoc->c.peer_vtag = asoc->peer.i.init_tag;
2407 
2408         /* Peer Rwnd   : Current calculated value of the peer's rwnd.  */
2409         asoc->peer.rwnd = asoc->peer.i.a_rwnd;
2410 
2411         /* Copy cookie in case we need to resend COOKIE-ECHO. */
2412         cookie = asoc->peer.cookie;
2413         if (cookie) {
2414                 asoc->peer.cookie = kmemdup(cookie, asoc->peer.cookie_len, gfp);
2415                 if (!asoc->peer.cookie)
2416                         goto clean_up;
2417         }
2418 
2419         /* RFC 2960 7.2.1 The initial value of ssthresh MAY be arbitrarily
2420          * high (for example, implementations MAY use the size of the receiver
2421          * advertised window).
2422          */
2423         list_for_each_entry(transport, &asoc->peer.transport_addr_list,
2424                         transports) {
2425                 transport->ssthresh = asoc->peer.i.a_rwnd;
2426         }
2427 
2428         /* Set up the TSN tracking pieces.  */
2429         if (!sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_INITIAL,
2430                                 asoc->peer.i.initial_tsn, gfp))
2431                 goto clean_up;
2432 
2433         /* RFC 2960 6.5 Stream Identifier and Stream Sequence Number
2434          *
2435          * The stream sequence number in all the streams shall start
2436          * from 0 when the association is established.  Also, when the
2437          * stream sequence number reaches the value 65535 the next
2438          * stream sequence number shall be set to 0.
2439          */
2440 
2441         /* Allocate storage for the negotiated streams if it is not a temporary
2442          * association.
2443          */
2444         if (!asoc->temp) {
2445                 int error;
2446 
2447                 asoc->ssnmap = sctp_ssnmap_new(asoc->c.sinit_max_instreams,
2448                                                asoc->c.sinit_num_ostreams, gfp);
2449                 if (!asoc->ssnmap)
2450                         goto clean_up;
2451 
2452                 error = sctp_assoc_set_id(asoc, gfp);
2453                 if (error)
2454                         goto clean_up;
2455         }
2456 
2457         /* ADDIP Section 4.1 ASCONF Chunk Procedures
2458          *
2459          * When an endpoint has an ASCONF signaled change to be sent to the
2460          * remote endpoint it should do the following:
2461          * ...
2462          * A2) A serial number should be assigned to the Chunk. The serial
2463          * number should be a monotonically increasing number. All serial
2464          * numbers are defined to be initialized at the start of the
2465          * association to the same value as the Initial TSN.
2466          */
2467         asoc->peer.addip_serial = asoc->peer.i.initial_tsn - 1;
2468         return 1;
2469 
2470 clean_up:
2471         /* Release the transport structures. */
2472         list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
2473                 transport = list_entry(pos, struct sctp_transport, transports);
2474                 if (transport->state != SCTP_ACTIVE)
2475                         sctp_assoc_rm_peer(asoc, transport);
2476         }
2477 
2478 nomem:
2479         return 0;
2480 }
2481 
2482 
2483 /* Update asoc with the option described in param.
2484  *
2485  * RFC2960 3.3.2.1 Optional/Variable Length Parameters in INIT
2486  *
2487  * asoc is the association to update.
2488  * param is the variable length parameter to use for update.
2489  * cid tells us if this is an INIT, INIT ACK or COOKIE ECHO.
2490  * If the current packet is an INIT we want to minimize the amount of
2491  * work we do.  In particular, we should not build transport
2492  * structures for the addresses.
2493  */
2494 static int sctp_process_param(struct sctp_association *asoc,
2495                               union sctp_params param,
2496                               const union sctp_addr *peer_addr,
2497                               gfp_t gfp)
2498 {
2499         struct net *net = sock_net(asoc->base.sk);
2500         union sctp_addr addr;
2501         int i;
2502         __u16 sat;
2503         int retval = 1;
2504         sctp_scope_t scope;
2505         u32 stale;
2506         struct sctp_af *af;
2507         union sctp_addr_param *addr_param;
2508         struct sctp_transport *t;
2509         struct sctp_endpoint *ep = asoc->ep;
2510 
2511         /* We maintain all INIT parameters in network byte order all the
2512          * time.  This allows us to not worry about whether the parameters
2513          * came from a fresh INIT, and INIT ACK, or were stored in a cookie.
2514          */
2515         switch (param.p->type) {
2516         case SCTP_PARAM_IPV6_ADDRESS:
2517                 if (PF_INET6 != asoc->base.sk->sk_family)
2518                         break;
2519                 goto do_addr_param;
2520 
2521         case SCTP_PARAM_IPV4_ADDRESS:
2522                 /* v4 addresses are not allowed on v6-only socket */
2523                 if (ipv6_only_sock(asoc->base.sk))
2524                         break;
2525 do_addr_param:
2526                 af = sctp_get_af_specific(param_type2af(param.p->type));
2527                 af->from_addr_param(&addr, param.addr, htons(asoc->peer.port), 0);
2528                 scope = sctp_scope(peer_addr);
2529                 if (sctp_in_scope(net, &addr, scope))
2530                         if (!sctp_assoc_add_peer(asoc, &addr, gfp, SCTP_UNCONFIRMED))
2531                                 return 0;
2532                 break;
2533 
2534         case SCTP_PARAM_COOKIE_PRESERVATIVE:
2535                 if (!net->sctp.cookie_preserve_enable)
2536                         break;
2537 
2538                 stale = ntohl(param.life->lifespan_increment);
2539 
2540                 /* Suggested Cookie Life span increment's unit is msec,
2541                  * (1/1000sec).
2542                  */
2543                 asoc->cookie_life = ktime_add_ms(asoc->cookie_life, stale);
2544                 break;
2545 
2546         case SCTP_PARAM_HOST_NAME_ADDRESS:
2547                 pr_debug("%s: unimplemented SCTP_HOST_NAME_ADDRESS\n", __func__);
2548                 break;
2549 
2550         case SCTP_PARAM_SUPPORTED_ADDRESS_TYPES:
2551                 /* Turn off the default values first so we'll know which
2552                  * ones are really set by the peer.
2553                  */
2554                 asoc->peer.ipv4_address = 0;
2555                 asoc->peer.ipv6_address = 0;
2556 
2557                 /* Assume that peer supports the address family
2558                  * by which it sends a packet.
2559                  */
2560                 if (peer_addr->sa.sa_family == AF_INET6)
2561                         asoc->peer.ipv6_address = 1;
2562                 else if (peer_addr->sa.sa_family == AF_INET)
2563                         asoc->peer.ipv4_address = 1;
2564 
2565                 /* Cycle through address types; avoid divide by 0. */
2566                 sat = ntohs(param.p->length) - sizeof(sctp_paramhdr_t);
2567                 if (sat)
2568                         sat /= sizeof(__u16);
2569 
2570                 for (i = 0; i < sat; ++i) {
2571                         switch (param.sat->types[i]) {
2572                         case SCTP_PARAM_IPV4_ADDRESS:
2573                                 asoc->peer.ipv4_address = 1;
2574                                 break;
2575 
2576                         case SCTP_PARAM_IPV6_ADDRESS:
2577                                 if (PF_INET6 == asoc->base.sk->sk_family)
2578                                         asoc->peer.ipv6_address = 1;
2579                                 break;
2580 
2581                         case SCTP_PARAM_HOST_NAME_ADDRESS:
2582                                 asoc->peer.hostname_address = 1;
2583                                 break;
2584 
2585                         default: /* Just ignore anything else.  */
2586                                 break;
2587                         }
2588                 }
2589                 break;
2590 
2591         case SCTP_PARAM_STATE_COOKIE:
2592                 asoc->peer.cookie_len =
2593                         ntohs(param.p->length) - sizeof(sctp_paramhdr_t);
2594                 asoc->peer.cookie = param.cookie->body;
2595                 break;
2596 
2597         case SCTP_PARAM_HEARTBEAT_INFO:
2598                 /* Would be odd to receive, but it causes no problems. */
2599                 break;
2600 
2601         case SCTP_PARAM_UNRECOGNIZED_PARAMETERS:
2602                 /* Rejected during verify stage. */
2603                 break;
2604 
2605         case SCTP_PARAM_ECN_CAPABLE:
2606                 asoc->peer.ecn_capable = 1;
2607                 break;
2608 
2609         case SCTP_PARAM_ADAPTATION_LAYER_IND:
2610                 asoc->peer.adaptation_ind = ntohl(param.aind->adaptation_ind);
2611                 break;
2612 
2613         case SCTP_PARAM_SET_PRIMARY:
2614                 if (!net->sctp.addip_enable)
2615                         goto fall_through;
2616 
2617                 addr_param = param.v + sizeof(sctp_addip_param_t);
2618 
2619                 af = sctp_get_af_specific(param_type2af(addr_param->p.type));
2620                 if (af == NULL)
2621                         break;
2622 
2623                 af->from_addr_param(&addr, addr_param,
2624                                     htons(asoc->peer.port), 0);
2625 
2626                 /* if the address is invalid, we can't process it.
2627                  * XXX: see spec for what to do.
2628                  */
2629                 if (!af->addr_valid(&addr, NULL, NULL))
2630                         break;
2631 
2632                 t = sctp_assoc_lookup_paddr(asoc, &addr);
2633                 if (!t)
2634                         break;
2635 
2636                 sctp_assoc_set_primary(asoc, t);
2637                 break;
2638 
2639         case SCTP_PARAM_SUPPORTED_EXT:
2640                 sctp_process_ext_param(asoc, param);
2641                 break;
2642 
2643         case SCTP_PARAM_FWD_TSN_SUPPORT:
2644                 if (asoc->prsctp_enable) {
2645                         asoc->peer.prsctp_capable = 1;
2646                         break;
2647                 }
2648                 /* Fall Through */
2649                 goto fall_through;
2650 
2651         case SCTP_PARAM_RANDOM:
2652                 if (!ep->auth_enable)
2653                         goto fall_through;
2654 
2655                 /* Save peer's random parameter */
2656                 asoc->peer.peer_random = kmemdup(param.p,
2657                                             ntohs(param.p->length), gfp);
2658                 if (!asoc->peer.peer_random) {
2659                         retval = 0;
2660                         break;
2661                 }
2662                 break;
2663 
2664         case SCTP_PARAM_HMAC_ALGO:
2665                 if (!ep->auth_enable)
2666                         goto fall_through;
2667 
2668                 /* Save peer's HMAC list */
2669                 asoc->peer.peer_hmacs = kmemdup(param.p,
2670                                             ntohs(param.p->length), gfp);
2671                 if (!asoc->peer.peer_hmacs) {
2672                         retval = 0;
2673                         break;
2674                 }
2675 
2676                 /* Set the default HMAC the peer requested*/
2677                 sctp_auth_asoc_set_default_hmac(asoc, param.hmac_algo);
2678                 break;
2679 
2680         case SCTP_PARAM_CHUNKS:
2681                 if (!ep->auth_enable)
2682                         goto fall_through;
2683 
2684                 asoc->peer.peer_chunks = kmemdup(param.p,
2685                                             ntohs(param.p->length), gfp);
2686                 if (!asoc->peer.peer_chunks)
2687                         retval = 0;
2688                 break;
2689 fall_through:
2690         default:
2691                 /* Any unrecognized parameters should have been caught
2692                  * and handled by sctp_verify_param() which should be
2693                  * called prior to this routine.  Simply log the error
2694                  * here.
2695                  */
2696                 pr_debug("%s: ignoring param:%d for association:%p.\n",
2697                          __func__, ntohs(param.p->type), asoc);
2698                 break;
2699         }
2700 
2701         return retval;
2702 }
2703 
2704 /* Select a new verification tag.  */
2705 __u32 sctp_generate_tag(const struct sctp_endpoint *ep)
2706 {
2707         /* I believe that this random number generator complies with RFC1750.
2708          * A tag of 0 is reserved for special cases (e.g. INIT).
2709          */
2710         __u32 x;
2711 
2712         do {
2713                 get_random_bytes(&x, sizeof(__u32));
2714         } while (x == 0);
2715 
2716         return x;
2717 }
2718 
2719 /* Select an initial TSN to send during startup.  */
2720 __u32 sctp_generate_tsn(const struct sctp_endpoint *ep)
2721 {
2722         __u32 retval;
2723 
2724         get_random_bytes(&retval, sizeof(__u32));
2725         return retval;
2726 }
2727 
2728 /*
2729  * ADDIP 3.1.1 Address Configuration Change Chunk (ASCONF)
2730  *      0                   1                   2                   3
2731  *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
2732  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2733  *     | Type = 0xC1   |  Chunk Flags  |      Chunk Length             |
2734  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2735  *     |                       Serial Number                           |
2736  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2737  *     |                    Address Parameter                          |
2738  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2739  *     |                     ASCONF Parameter #1                       |
2740  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2741  *     \                                                               \
2742  *     /                             ....                              /
2743  *     \                                                               \
2744  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2745  *     |                     ASCONF Parameter #N                       |
2746  *      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2747  *
2748  * Address Parameter and other parameter will not be wrapped in this function
2749  */
2750 static struct sctp_chunk *sctp_make_asconf(struct sctp_association *asoc,
2751                                            union sctp_addr *addr,
2752                                            int vparam_len)
2753 {
2754         sctp_addiphdr_t asconf;
2755         struct sctp_chunk *retval;
2756         int length = sizeof(asconf) + vparam_len;
2757         union sctp_addr_param addrparam;
2758         int addrlen;
2759         struct sctp_af *af = sctp_get_af_specific(addr->v4.sin_family);
2760 
2761         addrlen = af->to_addr_param(addr, &addrparam);
2762         if (!addrlen)
2763                 return NULL;
2764         length += addrlen;
2765 
2766         /* Create the chunk.  */
2767         retval = sctp_make_control(asoc, SCTP_CID_ASCONF, 0, length,
2768                                    GFP_ATOMIC);
2769         if (!retval)
2770                 return NULL;
2771 
2772         asconf.serial = htonl(asoc->addip_serial++);
2773 
2774         retval->subh.addip_hdr =
2775                 sctp_addto_chunk(retval, sizeof(asconf), &asconf);
2776         retval->param_hdr.v =
2777                 sctp_addto_chunk(retval, addrlen, &addrparam);
2778 
2779         return retval;
2780 }
2781 
2782 /* ADDIP
2783  * 3.2.1 Add IP Address
2784  *      0                   1                   2                   3
2785  *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
2786  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2787  *     |        Type = 0xC001          |    Length = Variable          |
2788  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2789  *     |               ASCONF-Request Correlation ID                   |
2790  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2791  *     |                       Address Parameter                       |
2792  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2793  *
2794  * 3.2.2 Delete IP Address
2795  *      0                   1                   2                   3
2796  *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
2797  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2798  *     |        Type = 0xC002          |    Length = Variable          |
2799  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2800  *     |               ASCONF-Request Correlation ID                   |
2801  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2802  *     |                       Address Parameter                       |
2803  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2804  *
2805  */
2806 struct sctp_chunk *sctp_make_asconf_update_ip(struct sctp_association *asoc,
2807                                               union sctp_addr         *laddr,
2808                                               struct sockaddr         *addrs,
2809                                               int                     addrcnt,
2810                                               __be16                  flags)
2811 {
2812         sctp_addip_param_t      param;
2813         struct sctp_chunk       *retval;
2814         union sctp_addr_param   addr_param;
2815         union sctp_addr         *addr;
2816         void                    *addr_buf;
2817         struct sctp_af          *af;
2818         int                     paramlen = sizeof(param);
2819         int                     addr_param_len = 0;
2820         int                     totallen = 0;
2821         int                     i;
2822         int                     del_pickup = 0;
2823 
2824         /* Get total length of all the address parameters. */
2825         addr_buf = addrs;
2826         for (i = 0; i < addrcnt; i++) {
2827                 addr = addr_buf;
2828                 af = sctp_get_af_specific(addr->v4.sin_family);
2829                 addr_param_len = af->to_addr_param(addr, &addr_param);
2830 
2831                 totallen += paramlen;
2832                 totallen += addr_param_len;
2833 
2834                 addr_buf += af->sockaddr_len;
2835                 if (asoc->asconf_addr_del_pending && !del_pickup) {
2836                         /* reuse the parameter length from the same scope one */
2837                         totallen += paramlen;
2838                         totallen += addr_param_len;
2839                         del_pickup = 1;
2840 
2841                         pr_debug("%s: picked same-scope del_pending addr, "
2842                                  "totallen for all addresses is %d\n",
2843                                  __func__, totallen);
2844                 }
2845         }
2846 
2847         /* Create an asconf chunk with the required length. */
2848         retval = sctp_make_asconf(asoc, laddr, totallen);
2849         if (!retval)
2850                 return NULL;
2851 
2852         /* Add the address parameters to the asconf chunk. */
2853         addr_buf = addrs;
2854         for (i = 0; i < addrcnt; i++) {
2855                 addr = addr_buf;
2856                 af = sctp_get_af_specific(addr->v4.sin_family);
2857                 addr_param_len = af->to_addr_param(addr, &addr_param);
2858                 param.param_hdr.type = flags;
2859                 param.param_hdr.length = htons(paramlen + addr_param_len);
2860                 param.crr_id = i;
2861 
2862                 sctp_addto_chunk(retval, paramlen, &param);
2863                 sctp_addto_chunk(retval, addr_param_len, &addr_param);
2864 
2865                 addr_buf += af->sockaddr_len;
2866         }
2867         if (flags == SCTP_PARAM_ADD_IP && del_pickup) {
2868                 addr = asoc->asconf_addr_del_pending;
2869                 af = sctp_get_af_specific(addr->v4.sin_family);
2870                 addr_param_len = af->to_addr_param(addr, &addr_param);
2871                 param.param_hdr.type = SCTP_PARAM_DEL_IP;
2872                 param.param_hdr.length = htons(paramlen + addr_param_len);
2873                 param.crr_id = i;
2874 
2875                 sctp_addto_chunk(retval, paramlen, &param);
2876                 sctp_addto_chunk(retval, addr_param_len, &addr_param);
2877         }
2878         return retval;
2879 }
2880 
2881 /* ADDIP
2882  * 3.2.4 Set Primary IP Address
2883  *      0                   1                   2                   3
2884  *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
2885  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2886  *     |        Type =0xC004           |    Length = Variable          |
2887  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2888  *     |               ASCONF-Request Correlation ID                   |
2889  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2890  *     |                       Address Parameter                       |
2891  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2892  *
2893  * Create an ASCONF chunk with Set Primary IP address parameter.
2894  */
2895 struct sctp_chunk *sctp_make_asconf_set_prim(struct sctp_association *asoc,
2896                                              union sctp_addr *addr)
2897 {
2898         sctp_addip_param_t      param;
2899         struct sctp_chunk       *retval;
2900         int                     len = sizeof(param);
2901         union sctp_addr_param   addrparam;
2902         int                     addrlen;
2903         struct sctp_af          *af = sctp_get_af_specific(addr->v4.sin_family);
2904 
2905         addrlen = af->to_addr_param(addr, &addrparam);
2906         if (!addrlen)
2907                 return NULL;
2908         len += addrlen;
2909 
2910         /* Create the chunk and make asconf header. */
2911         retval = sctp_make_asconf(asoc, addr, len);
2912         if (!retval)
2913                 return NULL;
2914 
2915         param.param_hdr.type = SCTP_PARAM_SET_PRIMARY;
2916         param.param_hdr.length = htons(len);
2917         param.crr_id = 0;
2918 
2919         sctp_addto_chunk(retval, sizeof(param), &param);
2920         sctp_addto_chunk(retval, addrlen, &addrparam);
2921 
2922         return retval;
2923 }
2924 
2925 /* ADDIP 3.1.2 Address Configuration Acknowledgement Chunk (ASCONF-ACK)
2926  *      0                   1                   2                   3
2927  *      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
2928  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2929  *     | Type = 0x80   |  Chunk Flags  |      Chunk Length             |
2930  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2931  *     |                       Serial Number                           |
2932  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2933  *     |                 ASCONF Parameter Response#1                   |
2934  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2935  *     \                                                               \
2936  *     /                             ....                              /
2937  *     \                                                               \
2938  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2939  *     |                 ASCONF Parameter Response#N                   |
2940  *     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
2941  *
2942  * Create an ASCONF_ACK chunk with enough space for the parameter responses.
2943  */
2944 static struct sctp_chunk *sctp_make_asconf_ack(const struct sctp_association *asoc,
2945                                                __u32 serial, int vparam_len)
2946 {
2947         sctp_addiphdr_t         asconf;
2948         struct sctp_chunk       *retval;
2949         int                     length = sizeof(asconf) + vparam_len;
2950 
2951         /* Create the chunk.  */
2952         retval = sctp_make_control(asoc, SCTP_CID_ASCONF_ACK, 0, length,
2953                                    GFP_ATOMIC);
2954         if (!retval)
2955                 return NULL;
2956 
2957         asconf.serial = htonl(serial);
2958 
2959         retval->subh.addip_hdr =
2960                 sctp_addto_chunk(retval, sizeof(asconf), &asconf);
2961 
2962         return retval;
2963 }
2964 
2965 /* Add response parameters to an ASCONF_ACK chunk. */
2966 static void sctp_add_asconf_response(struct sctp_chunk *chunk, __be32 crr_id,
2967                               __be16 err_code, sctp_addip_param_t *asconf_param)
2968 {
2969         sctp_addip_param_t      ack_param;
2970         sctp_errhdr_t           err_param;
2971         int                     asconf_param_len = 0;
2972         int                     err_param_len = 0;
2973         __be16                  response_type;
2974 
2975         if (SCTP_ERROR_NO_ERROR == err_code) {
2976                 response_type = SCTP_PARAM_SUCCESS_REPORT;
2977         } else {
2978                 response_type = SCTP_PARAM_ERR_CAUSE;
2979                 err_param_len = sizeof(err_param);
2980                 if (asconf_param)
2981                         asconf_param_len =
2982                                  ntohs(asconf_param->param_hdr.length);
2983         }
2984 
2985         /* Add Success Indication or Error Cause Indication parameter. */
2986         ack_param.param_hdr.type = response_type;
2987         ack_param.param_hdr.length = htons(sizeof(ack_param) +
2988                                            err_param_len +
2989                                            asconf_param_len);
2990         ack_param.crr_id = crr_id;
2991         sctp_addto_chunk(chunk, sizeof(ack_param), &ack_param);
2992 
2993         if (SCTP_ERROR_NO_ERROR == err_code)
2994                 return;
2995 
2996         /* Add Error Cause parameter. */
2997         err_param.cause = err_code;
2998         err_param.length = htons(err_param_len + asconf_param_len);
2999         sctp_addto_chunk(chunk, err_param_len, &err_param);
3000 
3001         /* Add the failed TLV copied from ASCONF chunk. */
3002         if (asconf_param)
3003                 sctp_addto_chunk(chunk, asconf_param_len, asconf_param);
3004 }
3005 
3006 /* Process a asconf parameter. */
3007 static __be16 sctp_process_asconf_param(struct sctp_association *asoc,
3008                                        struct sctp_chunk *asconf,
3009                                        sctp_addip_param_t *asconf_param)
3010 {
3011         struct sctp_transport *peer;
3012         struct sctp_af *af;
3013         union sctp_addr addr;
3014         union sctp_addr_param *addr_param;
3015 
3016         addr_param = (void *)asconf_param + sizeof(sctp_addip_param_t);
3017 
3018         if (asconf_param->param_hdr.type != SCTP_PARAM_ADD_IP &&
3019             asconf_param->param_hdr.type != SCTP_PARAM_DEL_IP &&
3020             asconf_param->param_hdr.type != SCTP_PARAM_SET_PRIMARY)
3021                 return SCTP_ERROR_UNKNOWN_PARAM;
3022 
3023         switch (addr_param->p.type) {
3024         case SCTP_PARAM_IPV6_ADDRESS:
3025                 if (!asoc->peer.ipv6_address)
3026                         return SCTP_ERROR_DNS_FAILED;
3027                 break;
3028         case SCTP_PARAM_IPV4_ADDRESS:
3029                 if (!asoc->peer.ipv4_address)
3030                         return SCTP_ERROR_DNS_FAILED;
3031                 break;
3032         default:
3033                 return SCTP_ERROR_DNS_FAILED;
3034         }
3035 
3036         af = sctp_get_af_specific(param_type2af(addr_param->p.type));
3037         if (unlikely(!af))
3038                 return SCTP_ERROR_DNS_FAILED;
3039 
3040         af->from_addr_param(&addr, addr_param, htons(asoc->peer.port), 0);
3041 
3042         /* ADDIP 4.2.1  This parameter MUST NOT contain a broadcast
3043          * or multicast address.
3044          * (note: wildcard is permitted and requires special handling so
3045          *  make sure we check for that)
3046          */
3047         if (!af->is_any(&addr) && !af->addr_valid(&addr, NULL, asconf->skb))
3048                 return SCTP_ERROR_DNS_FAILED;
3049 
3050         switch (asconf_param->param_hdr.type) {
3051         case SCTP_PARAM_ADD_IP:
3052                 /* Section 4.2.1:
3053                  * If the address 0.0.0.0 or ::0 is provided, the source
3054                  * address of the packet MUST be added.
3055                  */
3056                 if (af->is_any(&addr))
3057                         memcpy(&addr, &asconf->source, sizeof(addr));
3058 
3059                 /* ADDIP 4.3 D9) If an endpoint receives an ADD IP address
3060                  * request and does not have the local resources to add this
3061                  * new address to the association, it MUST return an Error
3062                  * Cause TLV set to the new error code 'Operation Refused
3063                  * Due to Resource Shortage'.
3064                  */
3065 
3066                 peer = sctp_assoc_add_peer(asoc, &addr, GFP_ATOMIC, SCTP_UNCONFIRMED);
3067                 if (!peer)
3068                         return SCTP_ERROR_RSRC_LOW;
3069 
3070                 /* Start the heartbeat timer. */
3071                 sctp_transport_reset_hb_timer(peer);
3072                 asoc->new_transport = peer;
3073                 break;
3074         case SCTP_PARAM_DEL_IP:
3075                 /* ADDIP 4.3 D7) If a request is received to delete the
3076                  * last remaining IP address of a peer endpoint, the receiver
3077                  * MUST send an Error Cause TLV with the error cause set to the
3078                  * new error code 'Request to Delete Last Remaining IP Address'.
3079                  */
3080                 if (asoc->peer.transport_count == 1)
3081                         return SCTP_ERROR_DEL_LAST_IP;
3082 
3083                 /* ADDIP 4.3 D8) If a request is received to delete an IP
3084                  * address which is also the source address of the IP packet
3085                  * which contained the ASCONF chunk, the receiver MUST reject
3086                  * this request. To reject the request the receiver MUST send
3087                  * an Error Cause TLV set to the new error code 'Request to
3088                  * Delete Source IP Address'
3089                  */
3090                 if (sctp_cmp_addr_exact(&asconf->source, &addr))
3091                         return SCTP_ERROR_DEL_SRC_IP;
3092 
3093                 /* Section 4.2.2
3094                  * If the address 0.0.0.0 or ::0 is provided, all
3095                  * addresses of the peer except the source address of the
3096                  * packet MUST be deleted.
3097                  */
3098                 if (af->is_any(&addr)) {
3099                         sctp_assoc_set_primary(asoc, asconf->transport);
3100                         sctp_assoc_del_nonprimary_peers(asoc,
3101                                                         asconf->transport);
3102                         return SCTP_ERROR_NO_ERROR;
3103                 }
3104 
3105                 /* If the address is not part of the association, the
3106                  * ASCONF-ACK with Error Cause Indication Parameter
3107                  * which including cause of Unresolvable Address should
3108                  * be sent.
3109                  */
3110                 peer = sctp_assoc_lookup_paddr(asoc, &addr);
3111                 if (!peer)
3112                         return SCTP_ERROR_DNS_FAILED;
3113 
3114                 sctp_assoc_rm_peer(asoc, peer);
3115                 break;
3116         case SCTP_PARAM_SET_PRIMARY:
3117                 /* ADDIP Section 4.2.4
3118                  * If the address 0.0.0.0 or ::0 is provided, the receiver
3119                  * MAY mark the source address of the packet as its
3120                  * primary.
3121                  */
3122                 if (af->is_any(&addr))
3123                         memcpy(&addr.v4, sctp_source(asconf), sizeof(addr));
3124 
3125                 peer = sctp_assoc_lookup_paddr(asoc, &addr);
3126                 if (!peer)
3127                         return SCTP_ERROR_DNS_FAILED;
3128 
3129                 sctp_assoc_set_primary(asoc, peer);
3130                 break;
3131         }
3132 
3133         return SCTP_ERROR_NO_ERROR;
3134 }
3135 
3136 /* Verify the ASCONF packet before we process it. */
3137 bool sctp_verify_asconf(const struct sctp_association *asoc,
3138                         struct sctp_chunk *chunk, bool addr_param_needed,
3139                         struct sctp_paramhdr **errp)
3140 {
3141         sctp_addip_chunk_t *addip = (sctp_addip_chunk_t *) chunk->chunk_hdr;
3142         union sctp_params param;
3143         bool addr_param_seen = false;
3144 
3145         sctp_walk_params(param, addip, addip_hdr.params) {
3146                 size_t length = ntohs(param.p->length);
3147 
3148                 *errp = param.p;
3149                 switch (param.p->type) {
3150                 case SCTP_PARAM_ERR_CAUSE:
3151                         break;
3152                 case SCTP_PARAM_IPV4_ADDRESS:
3153                         if (length != sizeof(sctp_ipv4addr_param_t))
3154                                 return false;
3155                         /* ensure there is only one addr param and it's in the
3156                          * beginning of addip_hdr params, or we reject it.
3157                          */
3158                         if (param.v != addip->addip_hdr.params)
3159                                 return false;
3160                         addr_param_seen = true;
3161                         break;
3162                 case SCTP_PARAM_IPV6_ADDRESS:
3163                         if (length != sizeof(sctp_ipv6addr_param_t))
3164                                 return false;
3165                         if (param.v != addip->addip_hdr.params)
3166                                 return false;
3167                         addr_param_seen = true;
3168                         break;
3169                 case SCTP_PARAM_ADD_IP:
3170                 case SCTP_PARAM_DEL_IP:
3171                 case SCTP_PARAM_SET_PRIMARY:
3172                         /* In ASCONF chunks, these need to be first. */
3173                         if (addr_param_needed && !addr_param_seen)
3174                                 return false;
3175                         length = ntohs(param.addip->param_hdr.length);
3176                         if (length < sizeof(sctp_addip_param_t) +
3177                                      sizeof(sctp_paramhdr_t))
3178                                 return false;
3179                         break;
3180                 case SCTP_PARAM_SUCCESS_REPORT:
3181                 case SCTP_PARAM_ADAPTATION_LAYER_IND:
3182                         if (length != sizeof(sctp_addip_param_t))
3183                                 return false;
3184                         break;
3185                 default:
3186                         /* This is unkown to us, reject! */
3187                         return false;
3188                 }
3189         }
3190 
3191         /* Remaining sanity checks. */
3192         if (addr_param_needed && !addr_param_seen)
3193                 return false;
3194         if (!addr_param_needed && addr_param_seen)
3195                 return false;
3196         if (param.v != chunk->chunk_end)
3197                 return false;
3198 
3199         return true;
3200 }
3201 
3202 /* Process an incoming ASCONF chunk with the next expected serial no. and
3203  * return an ASCONF_ACK chunk to be sent in response.
3204  */
3205 struct sctp_chunk *sctp_process_asconf(struct sctp_association *asoc,
3206                                        struct sctp_chunk *asconf)
3207 {
3208         sctp_addip_chunk_t *addip = (sctp_addip_chunk_t *) asconf->chunk_hdr;
3209         bool all_param_pass = true;
3210         union sctp_params param;
3211         sctp_addiphdr_t         *hdr;
3212         union sctp_addr_param   *addr_param;
3213         sctp_addip_param_t      *asconf_param;
3214         struct sctp_chunk       *asconf_ack;
3215         __be16  err_code;
3216         int     length = 0;
3217         int     chunk_len;
3218         __u32   serial;
3219 
3220         chunk_len = ntohs(asconf->chunk_hdr->length) - sizeof(sctp_chunkhdr_t);
3221         hdr = (sctp_addiphdr_t *)asconf->skb->data;
3222         serial = ntohl(hdr->serial);
3223 
3224         /* Skip the addiphdr and store a pointer to address parameter.  */
3225         length = sizeof(sctp_addiphdr_t);
3226         addr_param = (union sctp_addr_param *)(asconf->skb->data + length);
3227         chunk_len -= length;
3228 
3229         /* Skip the address parameter and store a pointer to the first
3230          * asconf parameter.
3231          */
3232         length = ntohs(addr_param->p.length);
3233         asconf_param = (void *)addr_param + length;
3234         chunk_len -= length;
3235 
3236         /* create an ASCONF_ACK chunk.
3237          * Based on the definitions of parameters, we know that the size of
3238          * ASCONF_ACK parameters are less than or equal to the fourfold of ASCONF
3239          * parameters.
3240          */
3241         asconf_ack = sctp_make_asconf_ack(asoc, serial, chunk_len * 4);
3242         if (!asconf_ack)
3243                 goto done;
3244 
3245         /* Process the TLVs contained within the ASCONF chunk. */
3246         sctp_walk_params(param, addip, addip_hdr.params) {
3247                 /* Skip preceeding address parameters. */
3248                 if (param.p->type == SCTP_PARAM_IPV4_ADDRESS ||
3249                     param.p->type == SCTP_PARAM_IPV6_ADDRESS)
3250                         continue;
3251 
3252                 err_code = sctp_process_asconf_param(asoc, asconf,
3253                                                      param.addip);
3254                 /* ADDIP 4.1 A7)
3255                  * If an error response is received for a TLV parameter,
3256                  * all TLVs with no response before the failed TLV are
3257                  * considered successful if not reported.  All TLVs after
3258                  * the failed response are considered unsuccessful unless
3259                  * a specific success indication is present for the parameter.
3260                  */
3261                 if (err_code != SCTP_ERROR_NO_ERROR)
3262                         all_param_pass = false;
3263                 if (!all_param_pass)
3264                         sctp_add_asconf_response(asconf_ack, param.addip->crr_id,
3265                                                  err_code, param.addip);
3266 
3267                 /* ADDIP 4.3 D11) When an endpoint receiving an ASCONF to add
3268                  * an IP address sends an 'Out of Resource' in its response, it
3269                  * MUST also fail any subsequent add or delete requests bundled
3270                  * in the ASCONF.
3271                  */
3272                 if (err_code == SCTP_ERROR_RSRC_LOW)
3273                         goto done;
3274         }
3275 done:
3276         asoc->peer.addip_serial++;
3277 
3278         /* If we are sending a new ASCONF_ACK hold a reference to it in assoc
3279          * after freeing the reference to old asconf ack if any.
3280          */
3281         if (asconf_ack) {
3282                 sctp_chunk_hold(asconf_ack);
3283                 list_add_tail(&asconf_ack->transmitted_list,
3284                               &asoc->asconf_ack_list);
3285         }
3286 
3287         return asconf_ack;
3288 }
3289 
3290 /* Process a asconf parameter that is successfully acked. */
3291 static void sctp_asconf_param_success(struct sctp_association *asoc,
3292                                      sctp_addip_param_t *asconf_param)
3293 {
3294         struct sctp_af *af;
3295         union sctp_addr addr;
3296         struct sctp_bind_addr *bp = &asoc->base.bind_addr;
3297         union sctp_addr_param *addr_param;
3298         struct sctp_transport *transport;
3299         struct sctp_sockaddr_entry *saddr;
3300 
3301         addr_param = (void *)asconf_param + sizeof(sctp_addip_param_t);
3302 
3303         /* We have checked the packet before, so we do not check again. */
3304         af = sctp_get_af_specific(param_type2af(addr_param->p.type));
3305         af->from_addr_param(&addr, addr_param, htons(bp->port), 0);
3306 
3307         switch (asconf_param->param_hdr.type) {
3308         case SCTP_PARAM_ADD_IP:
3309                 /* This is always done in BH context with a socket lock
3310                  * held, so the list can not change.
3311                  */
3312                 local_bh_disable();
3313                 list_for_each_entry(saddr, &bp->address_list, list) {
3314                         if (sctp_cmp_addr_exact(&saddr->a, &addr))
3315                                 saddr->state = SCTP_ADDR_SRC;
3316                 }
3317                 local_bh_enable();
3318                 list_for_each_entry(transport, &asoc->peer.transport_addr_list,
3319                                 transports) {
3320                         dst_release(transport->dst);
3321                         transport->dst = NULL;
3322                 }
3323                 break;
3324         case SCTP_PARAM_DEL_IP:
3325                 local_bh_disable();
3326                 sctp_del_bind_addr(bp, &addr);
3327                 if (asoc->asconf_addr_del_pending != NULL &&
3328                     sctp_cmp_addr_exact(asoc->asconf_addr_del_pending, &addr)) {
3329                         kfree(asoc->asconf_addr_del_pending);
3330                         asoc->asconf_addr_del_pending = NULL;
3331                 }
3332                 local_bh_enable();
3333                 list_for_each_entry(transport, &asoc->peer.transport_addr_list,
3334                                 transports) {
3335                         dst_release(transport->dst);
3336                         transport->dst = NULL;
3337                 }
3338                 break;
3339         default:
3340                 break;
3341         }
3342 }
3343 
3344 /* Get the corresponding ASCONF response error code from the ASCONF_ACK chunk
3345  * for the given asconf parameter.  If there is no response for this parameter,
3346  * return the error code based on the third argument 'no_err'.
3347  * ADDIP 4.1
3348  * A7) If an error response is received for a TLV parameter, all TLVs with no
3349  * response before the failed TLV are considered successful if not reported.
3350  * All TLVs after the failed response are considered unsuccessful unless a
3351  * specific success indication is present for the parameter.
3352  */
3353 static __be16 sctp_get_asconf_response(struct sctp_chunk *asconf_ack,
3354                                       sctp_addip_param_t *asconf_param,
3355                                       int no_err)
3356 {
3357         sctp_addip_param_t      *asconf_ack_param;
3358         sctp_errhdr_t           *err_param;
3359         int                     length;
3360         int                     asconf_ack_len;
3361         __be16                  err_code;
3362 
3363         if (no_err)
3364                 err_code = SCTP_ERROR_NO_ERROR;
3365         else
3366                 err_code = SCTP_ERROR_REQ_REFUSED;
3367 
3368         asconf_ack_len = ntohs(asconf_ack->chunk_hdr->length) -
3369                              sizeof(sctp_chunkhdr_t);
3370 
3371         /* Skip the addiphdr from the asconf_ack chunk and store a pointer to
3372          * the first asconf_ack parameter.
3373          */
3374         length = sizeof(sctp_addiphdr_t);
3375         asconf_ack_param = (sctp_addip_param_t *)(asconf_ack->skb->data +
3376                                                   length);
3377         asconf_ack_len -= length;
3378 
3379         while (asconf_ack_len > 0) {
3380                 if (asconf_ack_param->crr_id == asconf_param->crr_id) {
3381                         switch (asconf_ack_param->param_hdr.type) {
3382                         case SCTP_PARAM_SUCCESS_REPORT:
3383                                 return SCTP_ERROR_NO_ERROR;
3384                         case SCTP_PARAM_ERR_CAUSE:
3385                                 length = sizeof(sctp_addip_param_t);
3386                                 err_param = (void *)asconf_ack_param + length;
3387                                 asconf_ack_len -= length;
3388                                 if (asconf_ack_len > 0)
3389                                         return err_param->cause;
3390                                 else
3391                                         return SCTP_ERROR_INV_PARAM;
3392                                 break;
3393                         default:
3394                                 return SCTP_ERROR_INV_PARAM;
3395                         }
3396                 }
3397 
3398                 length = ntohs(asconf_ack_param->param_hdr.length);
3399                 asconf_ack_param = (void *)asconf_ack_param + length;
3400                 asconf_ack_len -= length;
3401         }
3402 
3403         return err_code;
3404 }
3405 
3406 /* Process an incoming ASCONF_ACK chunk against the cached last ASCONF chunk. */
3407 int sctp_process_asconf_ack(struct sctp_association *asoc,
3408                             struct sctp_chunk *asconf_ack)
3409 {
3410         struct sctp_chunk       *asconf = asoc->addip_last_asconf;
3411         union sctp_addr_param   *addr_param;
3412         sctp_addip_param_t      *asconf_param;
3413         int     length = 0;
3414         int     asconf_len = asconf->skb->len;
3415         int     all_param_pass = 0;
3416         int     no_err = 1;
3417         int     retval = 0;
3418         __be16  err_code = SCTP_ERROR_NO_ERROR;
3419 
3420         /* Skip the chunkhdr and addiphdr from the last asconf sent and store
3421          * a pointer to address parameter.
3422          */
3423         length = sizeof(sctp_addip_chunk_t);
3424         addr_param = (union sctp_addr_param *)(asconf->skb->data + length);
3425         asconf_len -= length;
3426 
3427         /* Skip the address parameter in the last asconf sent and store a
3428          * pointer to the first asconf parameter.
3429          */
3430         length = ntohs(addr_param->p.length);
3431         asconf_param = (void *)addr_param + length;
3432         asconf_len -= length;
3433 
3434         /* ADDIP 4.1
3435          * A8) If there is no response(s) to specific TLV parameter(s), and no
3436          * failures are indicated, then all request(s) are considered
3437          * successful.
3438          */
3439         if (asconf_ack->skb->len == sizeof(sctp_addiphdr_t))
3440                 all_param_pass = 1;
3441 
3442         /* Process the TLVs contained in the last sent ASCONF chunk. */
3443         while (asconf_len > 0) {
3444                 if (all_param_pass)
3445                         err_code = SCTP_ERROR_NO_ERROR;
3446                 else {
3447                         err_code = sctp_get_asconf_response(asconf_ack,
3448                                                             asconf_param,
3449                                                             no_err);
3450                         if (no_err && (SCTP_ERROR_NO_ERROR != err_code))
3451                                 no_err = 0;
3452                 }
3453 
3454                 switch (err_code) {
3455                 case SCTP_ERROR_NO_ERROR:
3456                         sctp_asconf_param_success(asoc, asconf_param);
3457                         break;
3458 
3459                 case SCTP_ERROR_RSRC_LOW:
3460                         retval = 1;
3461                         break;
3462 
3463                 case SCTP_ERROR_UNKNOWN_PARAM:
3464                         /* Disable sending this type of asconf parameter in
3465                          * future.
3466                          */
3467                         asoc->peer.addip_disabled_mask |=
3468                                 asconf_param->param_hdr.type;
3469                         break;
3470 
3471                 case SCTP_ERROR_REQ_REFUSED:
3472                 case SCTP_ERROR_DEL_LAST_IP:
3473                 case SCTP_ERROR_DEL_SRC_IP:
3474                 default:
3475                          break;
3476                 }
3477 
3478                 /* Skip the processed asconf parameter and move to the next
3479                  * one.
3480                  */
3481                 length = ntohs(asconf_param->param_hdr.length);
3482                 asconf_param = (void *)asconf_param + length;
3483                 asconf_len -= length;
3484         }
3485 
3486         if (no_err && asoc->src_out_of_asoc_ok) {
3487                 asoc->src_out_of_asoc_ok = 0;
3488                 sctp_transport_immediate_rtx(asoc->peer.primary_path);
3489         }
3490 
3491         /* Free the cached last sent asconf chunk. */
3492         list_del_init(&asconf->transmitted_list);
3493         sctp_chunk_free(asconf);
3494         asoc->addip_last_asconf = NULL;
3495 
3496         return retval;
3497 }
3498 
3499 /* Make a FWD TSN chunk. */
3500 struct sctp_chunk *sctp_make_fwdtsn(const struct sctp_association *asoc,
3501                                     __u32 new_cum_tsn, size_t nstreams,
3502                                     struct sctp_fwdtsn_skip *skiplist)
3503 {
3504         struct sctp_chunk *retval = NULL;
3505         struct sctp_fwdtsn_hdr ftsn_hdr;
3506         struct sctp_fwdtsn_skip skip;
3507         size_t hint;
3508         int i;
3509 
3510         hint = (nstreams + 1) * sizeof(__u32);
3511 
3512         retval = sctp_make_control(asoc, SCTP_CID_FWD_TSN, 0, hint, GFP_ATOMIC);
3513 
3514         if (!retval)
3515                 return NULL;
3516 
3517         ftsn_hdr.new_cum_tsn = htonl(new_cum_tsn);
3518         retval->subh.fwdtsn_hdr =
3519                 sctp_addto_chunk(retval, sizeof(ftsn_hdr), &ftsn_hdr);
3520 
3521         for (i = 0; i < nstreams; i++) {
3522                 skip.stream = skiplist[i].stream;
3523                 skip.ssn = skiplist[i].ssn;
3524                 sctp_addto_chunk(retval, sizeof(skip), &skip);
3525         }
3526 
3527         return retval;
3528 }
3529 

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