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Vlad Yasevich60c778b2008-01-11 09:57:09 -05001/* SCTP kernel implementation
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 * (C) Copyright IBM Corp. 2001, 2004
3 * Copyright (c) 1999-2000 Cisco, Inc.
4 * Copyright (c) 1999-2001 Motorola, Inc.
5 *
Vlad Yasevich60c778b2008-01-11 09:57:09 -05006 * This file is part of the SCTP kernel implementation
Linus Torvalds1da177e2005-04-16 15:20:36 -07007 *
8 * These functions handle output processing.
9 *
Vlad Yasevich60c778b2008-01-11 09:57:09 -050010 * This SCTP implementation is free software;
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 * you can redistribute it and/or modify it under the terms of
12 * the GNU General Public License as published by
13 * the Free Software Foundation; either version 2, or (at your option)
14 * any later version.
15 *
Vlad Yasevich60c778b2008-01-11 09:57:09 -050016 * This SCTP implementation is distributed in the hope that it
Linus Torvalds1da177e2005-04-16 15:20:36 -070017 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
18 * ************************
19 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
20 * See the GNU General Public License for more details.
21 *
22 * You should have received a copy of the GNU General Public License
Jeff Kirsher4b2f13a2013-12-06 06:28:48 -080023 * along with GNU CC; see the file COPYING. If not, see
24 * <http://www.gnu.org/licenses/>.
Linus Torvalds1da177e2005-04-16 15:20:36 -070025 *
26 * Please send any bug reports or fixes you make to the
27 * email address(es):
Daniel Borkmann91705c62013-07-23 14:51:47 +020028 * lksctp developers <linux-sctp@vger.kernel.org>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070030 * Written or modified by:
31 * La Monte H.P. Yarroll <piggy@acm.org>
32 * Karl Knutson <karl@athena.chicago.il.us>
33 * Jon Grimm <jgrimm@austin.ibm.com>
34 * Sridhar Samudrala <sri@us.ibm.com>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035 */
36
Joe Perches145ce502010-08-24 13:21:08 +000037#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
38
Linus Torvalds1da177e2005-04-16 15:20:36 -070039#include <linux/types.h>
40#include <linux/kernel.h>
41#include <linux/wait.h>
42#include <linux/time.h>
43#include <linux/ip.h>
44#include <linux/ipv6.h>
45#include <linux/init.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090046#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070047#include <net/inet_ecn.h>
Vlad Yasevich8d2f9e812009-03-21 13:41:09 -070048#include <net/ip.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070049#include <net/icmp.h>
Pavel Emelyanov7c73a6f2008-07-16 20:20:11 -070050#include <net/net_namespace.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
Linus Torvalds1da177e2005-04-16 15:20:36 -070052#include <linux/socket.h> /* for sa_family_t */
53#include <net/sock.h>
54
55#include <net/sctp/sctp.h>
56#include <net/sctp/sm.h>
Vlad Yasevich9ad09772007-12-16 14:06:41 -080057#include <net/sctp/checksum.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
59/* Forward declarations for private helpers. */
Neil Hormaned106272012-07-02 09:59:24 +000060static sctp_xmit_t __sctp_packet_append_chunk(struct sctp_packet *packet,
61 struct sctp_chunk *chunk);
Vlad Yaseviche83963b2009-08-07 10:43:07 -040062static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet,
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 struct sctp_chunk *chunk);
Vlad Yaseviche83963b2009-08-07 10:43:07 -040064static void sctp_packet_append_data(struct sctp_packet *packet,
65 struct sctp_chunk *chunk);
66static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet,
67 struct sctp_chunk *chunk,
68 u16 chunk_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -070069
Wei Yongjunbe297142009-09-04 14:34:06 +080070static void sctp_packet_reset(struct sctp_packet *packet)
71{
72 packet->size = packet->overhead;
73 packet->has_cookie_echo = 0;
74 packet->has_sack = 0;
75 packet->has_data = 0;
76 packet->has_auth = 0;
77 packet->ipfragok = 0;
78 packet->auth = NULL;
79}
80
Linus Torvalds1da177e2005-04-16 15:20:36 -070081/* Config a packet.
82 * This appears to be a followup set of initializations.
83 */
84struct sctp_packet *sctp_packet_config(struct sctp_packet *packet,
85 __u32 vtag, int ecn_capable)
86{
87 struct sctp_chunk *chunk = NULL;
88
Daniel Borkmannbb333812013-06-28 19:49:40 +020089 pr_debug("%s: packet:%p vtag:0x%x\n", __func__, packet, vtag);
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
91 packet->vtag = vtag;
Linus Torvalds1da177e2005-04-16 15:20:36 -070092
93 if (ecn_capable && sctp_packet_empty(packet)) {
94 chunk = sctp_get_ecne_prepend(packet->transport->asoc);
95
96 /* If there a is a prepend chunk stick it on the list before
YOSHIFUJI Hideakid808ad92007-02-09 23:25:18 +090097 * any other chunks get appended.
98 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 if (chunk)
100 sctp_packet_append_chunk(packet, chunk);
101 }
102
103 return packet;
104}
105
106/* Initialize the packet structure. */
107struct sctp_packet *sctp_packet_init(struct sctp_packet *packet,
108 struct sctp_transport *transport,
109 __u16 sport, __u16 dport)
110{
111 struct sctp_association *asoc = transport->asoc;
112 size_t overhead;
113
Daniel Borkmannbb333812013-06-28 19:49:40 +0200114 pr_debug("%s: packet:%p transport:%p\n", __func__, packet, transport);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115
116 packet->transport = transport;
117 packet->source_port = sport;
118 packet->destination_port = dport;
David S. Miller79af02c2005-07-08 21:47:49 -0700119 INIT_LIST_HEAD(&packet->chunk_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 if (asoc) {
YOSHIFUJI Hideakid808ad92007-02-09 23:25:18 +0900121 struct sctp_sock *sp = sctp_sk(asoc->base.sk);
122 overhead = sp->pf->af->net_header_len;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 } else {
124 overhead = sizeof(struct ipv6hdr);
125 }
126 overhead += sizeof(struct sctphdr);
127 packet->overhead = overhead;
Wei Yongjunbe297142009-09-04 14:34:06 +0800128 sctp_packet_reset(packet);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129 packet->vtag = 0;
Daniel Borkmann3e3251b2013-04-18 21:59:37 +0000130
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 return packet;
132}
133
134/* Free a packet. */
135void sctp_packet_free(struct sctp_packet *packet)
136{
David S. Miller79af02c2005-07-08 21:47:49 -0700137 struct sctp_chunk *chunk, *tmp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700138
Daniel Borkmannbb333812013-06-28 19:49:40 +0200139 pr_debug("%s: packet:%p\n", __func__, packet);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700140
David S. Miller79af02c2005-07-08 21:47:49 -0700141 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
142 list_del_init(&chunk->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 sctp_chunk_free(chunk);
David S. Miller79af02c2005-07-08 21:47:49 -0700144 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145}
146
147/* This routine tries to append the chunk to the offered packet. If adding
148 * the chunk causes the packet to exceed the path MTU and COOKIE_ECHO chunk
149 * is not present in the packet, it transmits the input packet.
150 * Data can be bundled with a packet containing a COOKIE_ECHO chunk as long
151 * as it can fit in the packet, but any more data that does not fit in this
152 * packet can be sent only after receiving the COOKIE_ACK.
153 */
154sctp_xmit_t sctp_packet_transmit_chunk(struct sctp_packet *packet,
Vlad Yasevich2e3216c2008-06-19 16:08:18 -0700155 struct sctp_chunk *chunk,
156 int one_packet)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157{
158 sctp_xmit_t retval;
159 int error = 0;
160
Daniel Borkmannbb333812013-06-28 19:49:40 +0200161 pr_debug("%s: packet:%p chunk:%p\n", __func__, packet, chunk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162
163 switch ((retval = (sctp_packet_append_chunk(packet, chunk)))) {
164 case SCTP_XMIT_PMTU_FULL:
165 if (!packet->has_cookie_echo) {
166 error = sctp_packet_transmit(packet);
167 if (error < 0)
168 chunk->skb->sk->sk_err = -error;
169
170 /* If we have an empty packet, then we can NOT ever
171 * return PMTU_FULL.
172 */
Vlad Yasevich2e3216c2008-06-19 16:08:18 -0700173 if (!one_packet)
174 retval = sctp_packet_append_chunk(packet,
175 chunk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 }
177 break;
178
179 case SCTP_XMIT_RWND_FULL:
180 case SCTP_XMIT_OK:
David Laight526cbef2014-07-22 08:59:14 +0000181 case SCTP_XMIT_DELAY:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 break;
Stephen Hemminger3ff50b72007-04-20 17:09:22 -0700183 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184
185 return retval;
186}
187
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700188/* Try to bundle an auth chunk into the packet. */
189static sctp_xmit_t sctp_packet_bundle_auth(struct sctp_packet *pkt,
190 struct sctp_chunk *chunk)
191{
192 struct sctp_association *asoc = pkt->transport->asoc;
193 struct sctp_chunk *auth;
194 sctp_xmit_t retval = SCTP_XMIT_OK;
195
196 /* if we don't have an association, we can't do authentication */
197 if (!asoc)
198 return retval;
199
200 /* See if this is an auth chunk we are bundling or if
201 * auth is already bundled.
202 */
Vlad Yasevich4007cc82009-09-04 18:21:00 -0400203 if (chunk->chunk_hdr->type == SCTP_CID_AUTH || pkt->has_auth)
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700204 return retval;
205
206 /* if the peer did not request this chunk to be authenticated,
207 * don't do it
208 */
209 if (!chunk->auth)
210 return retval;
211
212 auth = sctp_make_auth(asoc);
213 if (!auth)
214 return retval;
215
Neil Hormaned106272012-07-02 09:59:24 +0000216 retval = __sctp_packet_append_chunk(pkt, auth);
217
218 if (retval != SCTP_XMIT_OK)
219 sctp_chunk_free(auth);
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700220
221 return retval;
222}
223
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224/* Try to bundle a SACK with the packet. */
225static sctp_xmit_t sctp_packet_bundle_sack(struct sctp_packet *pkt,
226 struct sctp_chunk *chunk)
227{
228 sctp_xmit_t retval = SCTP_XMIT_OK;
229
230 /* If sending DATA and haven't aleady bundled a SACK, try to
231 * bundle one in to the packet.
232 */
233 if (sctp_chunk_is_data(chunk) && !pkt->has_sack &&
234 !pkt->has_cookie_echo) {
235 struct sctp_association *asoc;
Doug Grahamaf87b822009-07-29 12:05:57 -0400236 struct timer_list *timer;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 asoc = pkt->transport->asoc;
Doug Grahamaf87b822009-07-29 12:05:57 -0400238 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239
Doug Grahamaf87b822009-07-29 12:05:57 -0400240 /* If the SACK timer is running, we have a pending SACK */
241 if (timer_pending(timer)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 struct sctp_chunk *sack;
Neil Horman42448542012-06-30 03:04:26 +0000243
244 if (pkt->transport->sack_generation !=
245 pkt->transport->asoc->peer.sack_generation)
246 return retval;
247
Linus Torvalds1da177e2005-04-16 15:20:36 -0700248 asoc->a_rwnd = asoc->rwnd;
249 sack = sctp_make_sack(asoc);
250 if (sack) {
Neil Hormaned106272012-07-02 09:59:24 +0000251 retval = __sctp_packet_append_chunk(pkt, sack);
252 if (retval != SCTP_XMIT_OK) {
253 sctp_chunk_free(sack);
254 goto out;
255 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 asoc->peer.sack_needed = 0;
Doug Grahamaf87b822009-07-29 12:05:57 -0400257 if (del_timer(timer))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 sctp_association_put(asoc);
259 }
260 }
261 }
Neil Hormaned106272012-07-02 09:59:24 +0000262out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 return retval;
264}
265
Neil Hormaned106272012-07-02 09:59:24 +0000266
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267/* Append a chunk to the offered packet reporting back any inability to do
268 * so.
269 */
Neil Hormaned106272012-07-02 09:59:24 +0000270static sctp_xmit_t __sctp_packet_append_chunk(struct sctp_packet *packet,
271 struct sctp_chunk *chunk)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272{
273 sctp_xmit_t retval = SCTP_XMIT_OK;
274 __u16 chunk_len = WORD_ROUND(ntohs(chunk->chunk_hdr->length));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275
Vlad Yaseviche83963b2009-08-07 10:43:07 -0400276 /* Check to see if this chunk will fit into the packet */
277 retval = sctp_packet_will_fit(packet, chunk, chunk_len);
278 if (retval != SCTP_XMIT_OK)
279 goto finish;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280
Vlad Yaseviche83963b2009-08-07 10:43:07 -0400281 /* We believe that this chunk is OK to add to the packet */
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700282 switch (chunk->chunk_hdr->type) {
wangweidongf7010e62013-12-23 12:16:52 +0800283 case SCTP_CID_DATA:
Vlad Yaseviche83963b2009-08-07 10:43:07 -0400284 /* Account for the data being in the packet */
285 sctp_packet_append_data(packet, chunk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 /* Disallow SACK bundling after DATA. */
287 packet->has_sack = 1;
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700288 /* Disallow AUTH bundling after DATA */
289 packet->has_auth = 1;
290 /* Let it be knows that packet has DATA in it */
291 packet->has_data = 1;
Vlad Yasevich759af002009-01-22 14:53:01 -0800292 /* timestamp the chunk for rtx purposes */
293 chunk->sent_at = jiffies;
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700294 break;
wangweidongf7010e62013-12-23 12:16:52 +0800295 case SCTP_CID_COOKIE_ECHO:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 packet->has_cookie_echo = 1;
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700297 break;
298
wangweidongf7010e62013-12-23 12:16:52 +0800299 case SCTP_CID_SACK:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 packet->has_sack = 1;
Michele Baldessari196d6752012-12-01 04:49:42 +0000301 if (chunk->asoc)
302 chunk->asoc->stats.osacks++;
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700303 break;
304
wangweidongf7010e62013-12-23 12:16:52 +0800305 case SCTP_CID_AUTH:
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700306 packet->has_auth = 1;
307 packet->auth = chunk;
308 break;
309 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310
311 /* It is OK to send this chunk. */
David S. Miller79af02c2005-07-08 21:47:49 -0700312 list_add_tail(&chunk->list, &packet->chunk_list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313 packet->size += chunk_len;
314 chunk->transport = packet->transport;
315finish:
316 return retval;
317}
318
Neil Hormaned106272012-07-02 09:59:24 +0000319/* Append a chunk to the offered packet reporting back any inability to do
320 * so.
321 */
322sctp_xmit_t sctp_packet_append_chunk(struct sctp_packet *packet,
323 struct sctp_chunk *chunk)
324{
325 sctp_xmit_t retval = SCTP_XMIT_OK;
326
Daniel Borkmannbb333812013-06-28 19:49:40 +0200327 pr_debug("%s: packet:%p chunk:%p\n", __func__, packet, chunk);
Neil Hormaned106272012-07-02 09:59:24 +0000328
329 /* Data chunks are special. Before seeing what else we can
330 * bundle into this packet, check to see if we are allowed to
331 * send this DATA.
332 */
333 if (sctp_chunk_is_data(chunk)) {
334 retval = sctp_packet_can_append_data(packet, chunk);
335 if (retval != SCTP_XMIT_OK)
336 goto finish;
337 }
338
339 /* Try to bundle AUTH chunk */
340 retval = sctp_packet_bundle_auth(packet, chunk);
341 if (retval != SCTP_XMIT_OK)
342 goto finish;
343
344 /* Try to bundle SACK chunk */
345 retval = sctp_packet_bundle_sack(packet, chunk);
346 if (retval != SCTP_XMIT_OK)
347 goto finish;
348
349 retval = __sctp_packet_append_chunk(packet, chunk);
350
351finish:
352 return retval;
353}
354
Thomas Graf4c3a5bd2012-09-03 04:27:42 +0000355static void sctp_packet_release_owner(struct sk_buff *skb)
356{
357 sk_free(skb->sk);
358}
359
360static void sctp_packet_set_owner_w(struct sk_buff *skb, struct sock *sk)
361{
362 skb_orphan(skb);
363 skb->sk = sk;
364 skb->destructor = sctp_packet_release_owner;
365
366 /*
367 * The data chunks have already been accounted for in sctp_sendmsg(),
368 * therefore only reserve a single byte to keep socket around until
369 * the packet has been transmitted.
370 */
371 atomic_inc(&sk->sk_wmem_alloc);
372}
373
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374/* All packets are sent to the network through this function from
375 * sctp_outq_tail().
376 *
377 * The return value is a normal kernel error return value.
378 */
379int sctp_packet_transmit(struct sctp_packet *packet)
380{
381 struct sctp_transport *tp = packet->transport;
382 struct sctp_association *asoc = tp->asoc;
383 struct sctphdr *sh;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 struct sk_buff *nskb;
David S. Miller79af02c2005-07-08 21:47:49 -0700385 struct sctp_chunk *chunk, *tmp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386 struct sock *sk;
387 int err = 0;
388 int padding; /* How much padding do we need? */
389 __u8 has_data = 0;
wangweidong04388162013-12-26 13:55:56 +0800390 struct dst_entry *dst;
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700391 unsigned char *auth = NULL; /* pointer to auth in skb data */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392
Daniel Borkmannbb333812013-06-28 19:49:40 +0200393 pr_debug("%s: packet:%p\n", __func__, packet);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394
395 /* Do NOT generate a chunkless packet. */
David S. Miller79af02c2005-07-08 21:47:49 -0700396 if (list_empty(&packet->chunk_list))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 return err;
398
399 /* Set up convenience variables... */
David S. Miller79af02c2005-07-08 21:47:49 -0700400 chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 sk = chunk->skb->sk;
402
403 /* Allocate the new skb. */
Daniel Borkmann9772b542014-12-03 12:13:58 +0100404 nskb = alloc_skb(packet->size + MAX_HEADER, GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 if (!nskb)
406 goto nomem;
407
408 /* Make sure the outbound skb has enough header room reserved. */
Daniel Borkmann9772b542014-12-03 12:13:58 +0100409 skb_reserve(nskb, packet->overhead + MAX_HEADER);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410
411 /* Set the owning socket so that we know where to get the
412 * destination IP address.
413 */
Thomas Graf4c3a5bd2012-09-03 04:27:42 +0000414 sctp_packet_set_owner_w(nskb, sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415
Nicolas Dichtele0268862012-05-04 05:24:54 +0000416 if (!sctp_transport_dst_check(tp)) {
Sridhar Samudrala503b55f2006-06-17 22:57:28 -0700417 sctp_transport_route(tp, NULL, sctp_sk(sk));
418 if (asoc && (asoc->param_flags & SPP_PMTUD_ENABLE)) {
David S. Miller02f3d4c2012-07-16 03:57:14 -0700419 sctp_assoc_sync_pmtu(sk, asoc);
Sridhar Samudrala503b55f2006-06-17 22:57:28 -0700420 }
421 }
Eric Dumazetadf30902009-06-02 05:19:30 +0000422 dst = dst_clone(tp->dst);
Wei Yongjunff0ac742009-06-28 22:49:37 +0000423 if (!dst)
Sridhar Samudrala503b55f2006-06-17 22:57:28 -0700424 goto no_route;
wangweidong04388162013-12-26 13:55:56 +0800425 skb_dst_set(nskb, dst);
Sridhar Samudrala503b55f2006-06-17 22:57:28 -0700426
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 /* Build the SCTP header. */
428 sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr));
Jesse Brandeburg8dc92f72009-04-27 22:35:52 +0000429 skb_reset_transport_header(nskb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 sh->source = htons(packet->source_port);
431 sh->dest = htons(packet->destination_port);
432
433 /* From 6.8 Adler-32 Checksum Calculation:
434 * After the packet is constructed (containing the SCTP common
435 * header and one or more control or DATA chunks), the
436 * transmitter shall:
437 *
438 * 1) Fill in the proper Verification Tag in the SCTP common
439 * header and initialize the checksum field to 0's.
440 */
441 sh->vtag = htonl(packet->vtag);
442 sh->checksum = 0;
443
Linus Torvalds1da177e2005-04-16 15:20:36 -0700444 /**
445 * 6.10 Bundling
446 *
447 * An endpoint bundles chunks by simply including multiple
448 * chunks in one outbound SCTP packet. ...
449 */
450
451 /**
452 * 3.2 Chunk Field Descriptions
453 *
454 * The total length of a chunk (including Type, Length and
455 * Value fields) MUST be a multiple of 4 bytes. If the length
456 * of the chunk is not a multiple of 4 bytes, the sender MUST
457 * pad the chunk with all zero bytes and this padding is not
458 * included in the chunk length field. The sender should
459 * never pad with more than 3 bytes.
460 *
461 * [This whole comment explains WORD_ROUND() below.]
462 */
Daniel Borkmannbb333812013-06-28 19:49:40 +0200463
464 pr_debug("***sctp_transmit_packet***\n");
465
David S. Miller79af02c2005-07-08 21:47:49 -0700466 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
467 list_del_init(&chunk->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468 if (sctp_chunk_is_data(chunk)) {
Vlad Yasevichae19c542010-04-30 22:41:09 -0400469 /* 6.3.1 C4) When data is in flight and when allowed
470 * by rule C5, a new RTT measurement MUST be made each
471 * round trip. Furthermore, new RTT measurements
472 * SHOULD be made no more than once per round-trip
473 * for a given destination transport address.
474 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475
Xufeng Zhang6eabca52013-11-25 11:26:57 +0800476 if (!chunk->resent && !tp->rto_pending) {
Vlad Yasevichae19c542010-04-30 22:41:09 -0400477 chunk->rtt_in_progress = 1;
478 tp->rto_pending = 1;
Neil Hormand8dd1572009-11-23 15:54:00 -0500479 }
Xufeng Zhang6eabca52013-11-25 11:26:57 +0800480
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 has_data = 1;
482 }
483
484 padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len;
485 if (padding)
486 memset(skb_put(chunk->skb, padding), 0, padding);
487
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700488 /* if this is the auth chunk that we are adding,
489 * store pointer where it will be added and put
490 * the auth into the packet.
491 */
492 if (chunk == packet->auth)
493 auth = skb_tail_pointer(nskb);
494
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700495 memcpy(skb_put(nskb, chunk->skb->len),
Sridhar Samudrala503b55f2006-06-17 22:57:28 -0700496 chunk->skb->data, chunk->skb->len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497
Daniel Borkmannbb333812013-06-28 19:49:40 +0200498 pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, "
499 "rtt_in_progress:%d\n", chunk,
500 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
501 chunk->has_tsn ? "TSN" : "No TSN",
502 chunk->has_tsn ? ntohl(chunk->subh.data_hdr->tsn) : 0,
503 ntohs(chunk->chunk_hdr->length), chunk->skb->len,
504 chunk->rtt_in_progress);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700505
506 /*
507 * If this is a control chunk, this is our last
508 * reference. Free data chunks after they've been
509 * acknowledged or have failed.
510 */
511 if (!sctp_chunk_is_data(chunk))
YOSHIFUJI Hideakid808ad92007-02-09 23:25:18 +0900512 sctp_chunk_free(chunk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 }
514
Vlad Yasevich4cd57c82007-09-16 19:32:45 -0700515 /* SCTP-AUTH, Section 6.2
516 * The sender MUST calculate the MAC as described in RFC2104 [2]
517 * using the hash function H as described by the MAC Identifier and
518 * the shared association key K based on the endpoint pair shared key
519 * described by the shared key identifier. The 'data' used for the
520 * computation of the AUTH-chunk is given by the AUTH chunk with its
521 * HMAC field set to zero (as shown in Figure 6) followed by all
522 * chunks that are placed after the AUTH chunk in the SCTP packet.
523 */
524 if (auth)
525 sctp_auth_calculate_hmac(asoc, nskb,
526 (struct sctp_auth_chunk *)auth,
527 GFP_ATOMIC);
528
529 /* 2) Calculate the Adler-32 checksum of the whole packet,
530 * including the SCTP common header and all the
531 * chunks.
532 *
533 * Note: Adler-32 is no longer applicable, as has been replaced
534 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
535 */
David S. Miller71acc0d2013-08-09 13:09:41 -0700536 if (!sctp_checksum_disable) {
Fan Du27127a82013-10-15 22:01:30 -0400537 if (!(dst->dev->features & NETIF_F_SCTP_CSUM) ||
Vlad Yasevichd2dbbba2013-10-15 22:01:31 -0400538 (dst_xfrm(dst) != NULL) || packet->ipfragok) {
Daniel Borkmanne6d8b642013-10-30 11:50:52 +0100539 sh->checksum = sctp_compute_cksum(nskb, 0);
Michał Mirosławb73c43f2011-07-13 14:10:29 +0000540 } else {
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300541 /* no need to seed pseudo checksum for SCTP */
Jesse Brandeburg8dc92f72009-04-27 22:35:52 +0000542 nskb->ip_summed = CHECKSUM_PARTIAL;
wangweidongf7010e62013-12-23 12:16:52 +0800543 nskb->csum_start = skb_transport_header(nskb) - nskb->head;
Jesse Brandeburg8dc92f72009-04-27 22:35:52 +0000544 nskb->csum_offset = offsetof(struct sctphdr, checksum);
Jesse Brandeburg8dc92f72009-04-27 22:35:52 +0000545 }
546 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 /* IP layer ECN support
549 * From RFC 2481
550 * "The ECN-Capable Transport (ECT) bit would be set by the
551 * data sender to indicate that the end-points of the
552 * transport protocol are ECN-capable."
553 *
554 * Now setting the ECT bit all the time, as it should not cause
555 * any problems protocol-wise even if our peer ignores it.
556 *
557 * Note: The works for IPv6 layer checks this bit too later
558 * in transmission. See IP6_ECN_flow_xmit().
559 */
wangweidong131334d2013-12-18 17:18:55 +0800560 tp->af_specific->ecn_capable(nskb->sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561
562 /* Set up the IP options. */
563 /* BUG: not implemented
564 * For v4 this all lives somewhere in sk->sk_opt...
565 */
566
567 /* Dump that on IP! */
Michele Baldessari196d6752012-12-01 04:49:42 +0000568 if (asoc) {
569 asoc->stats.opackets++;
570 if (asoc->peer.last_sent_to != tp)
571 /* Considering the multiple CPU scenario, this is a
572 * "correcter" place for last_sent_to. --xguo
573 */
574 asoc->peer.last_sent_to = tp;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 }
576
577 if (has_data) {
578 struct timer_list *timer;
579 unsigned long timeout;
580
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 /* Restart the AUTOCLOSE timer when sending data. */
Neil Horman9f70f462013-12-10 06:48:15 -0500582 if (sctp_state(asoc, ESTABLISHED) &&
583 asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE]) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 timer = &asoc->timers[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
585 timeout = asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE];
586
587 if (!mod_timer(timer, jiffies + timeout))
588 sctp_association_hold(asoc);
589 }
590 }
591
Daniel Borkmannbb333812013-06-28 19:49:40 +0200592 pr_debug("***sctp_transmit_packet*** skb->len:%d\n", nskb->len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700593
WANG Cong60ff7462014-05-04 16:39:18 -0700594 nskb->ignore_df = packet->ipfragok;
wangweidong131334d2013-12-18 17:18:55 +0800595 tp->af_specific->sctp_xmit(nskb, tp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700596
597out:
Wei Yongjund521c082009-09-02 13:05:33 +0800598 sctp_packet_reset(packet);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599 return err;
600no_route:
601 kfree_skb(nskb);
Alexander Sverdlin29c4afc2015-06-29 10:41:03 +0200602
603 if (asoc)
604 IP_INC_STATS(sock_net(asoc->base.sk), IPSTATS_MIB_OUTNOROUTES);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605
606 /* FIXME: Returning the 'err' will effect all the associations
607 * associated with a socket, although only one of the paths of the
608 * association is unreachable.
609 * The real failure of a transport or association can be passed on
610 * to the user via notifications. So setting this error may not be
611 * required.
612 */
613 /* err = -EHOSTUNREACH; */
614err:
615 /* Control chunks are unreliable so just drop them. DATA chunks
616 * will get resent or dropped later.
617 */
618
David S. Miller79af02c2005-07-08 21:47:49 -0700619 list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
620 list_del_init(&chunk->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621 if (!sctp_chunk_is_data(chunk))
YOSHIFUJI Hideakid808ad92007-02-09 23:25:18 +0900622 sctp_chunk_free(chunk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623 }
624 goto out;
625nomem:
626 err = -ENOMEM;
627 goto err;
628}
629
630/********************************************************************
631 * 2nd Level Abstractions
632 ********************************************************************/
633
Vlad Yaseviche83963b2009-08-07 10:43:07 -0400634/* This private function check to see if a chunk can be added */
635static sctp_xmit_t sctp_packet_can_append_data(struct sctp_packet *packet,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 struct sctp_chunk *chunk)
637{
Vlad Yaseviche83963b2009-08-07 10:43:07 -0400638 size_t datasize, rwnd, inflight, flight_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639 struct sctp_transport *transport = packet->transport;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640 struct sctp_association *asoc = transport->asoc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700641 struct sctp_outq *q = &asoc->outqueue;
642
643 /* RFC 2960 6.1 Transmission of DATA Chunks
644 *
645 * A) At any given time, the data sender MUST NOT transmit new data to
646 * any destination transport address if its peer's rwnd indicates
647 * that the peer has no buffer space (i.e. rwnd is 0, see Section
648 * 6.2.1). However, regardless of the value of rwnd (including if it
649 * is 0), the data sender can always have one DATA chunk in flight to
650 * the receiver if allowed by cwnd (see rule B below). This rule
651 * allows the sender to probe for a change in rwnd that the sender
652 * missed due to the SACK having been lost in transit from the data
653 * receiver to the data sender.
654 */
655
656 rwnd = asoc->peer.rwnd;
Vlad Yaseviche83963b2009-08-07 10:43:07 -0400657 inflight = q->outstanding_bytes;
658 flight_size = transport->flight_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659
660 datasize = sctp_data_size(chunk);
661
David Laight723189f2014-07-22 08:59:08 +0000662 if (datasize > rwnd && inflight > 0)
663 /* We have (at least) one data chunk in flight,
664 * so we can't fall back to rule 6.1 B).
665 */
666 return SCTP_XMIT_RWND_FULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700667
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 /* RFC 2960 6.1 Transmission of DATA Chunks
669 *
670 * B) At any given time, the sender MUST NOT transmit new data
671 * to a given transport address if it has cwnd or more bytes
672 * of data outstanding to that transport address.
673 */
674 /* RFC 7.2.4 & the Implementers Guide 2.8.
675 *
676 * 3) ...
677 * When a Fast Retransmit is being performed the sender SHOULD
678 * ignore the value of cwnd and SHOULD NOT delay retransmission.
679 */
David Laight723189f2014-07-22 08:59:08 +0000680 if (chunk->fast_retransmit != SCTP_NEED_FRTX &&
681 flight_size >= transport->cwnd)
682 return SCTP_XMIT_RWND_FULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683
684 /* Nagle's algorithm to solve small-packet problem:
685 * Inhibit the sending of new chunks when new outgoing data arrives
686 * if any previously transmitted data on the connection remains
687 * unacknowledged.
688 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689
David Laight723189f2014-07-22 08:59:08 +0000690 if (sctp_sk(asoc->base.sk)->nodelay)
691 /* Nagle disabled */
692 return SCTP_XMIT_OK;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693
David Laight723189f2014-07-22 08:59:08 +0000694 if (!sctp_packet_empty(packet))
695 /* Append to packet */
696 return SCTP_XMIT_OK;
697
698 if (inflight == 0)
699 /* Nothing unacked */
700 return SCTP_XMIT_OK;
701
702 if (!sctp_state(asoc, ESTABLISHED))
703 return SCTP_XMIT_OK;
704
705 /* Check whether this chunk and all the rest of pending data will fit
706 * or delay in hopes of bundling a full sized packet.
707 */
708 if (chunk->skb->len + q->out_qlen >= transport->pathmtu - packet->overhead)
709 /* Enough data queued to fill a packet */
710 return SCTP_XMIT_OK;
711
712 /* Don't delay large message writes that may have been fragmented */
713 if (!chunk->msg->can_delay)
714 return SCTP_XMIT_OK;
715
716 /* Defer until all data acked or packet full */
David Laight526cbef2014-07-22 08:59:14 +0000717 return SCTP_XMIT_DELAY;
Vlad Yaseviche83963b2009-08-07 10:43:07 -0400718}
719
720/* This private function does management things when adding DATA chunk */
721static void sctp_packet_append_data(struct sctp_packet *packet,
722 struct sctp_chunk *chunk)
723{
724 struct sctp_transport *transport = packet->transport;
725 size_t datasize = sctp_data_size(chunk);
726 struct sctp_association *asoc = transport->asoc;
727 u32 rwnd = asoc->peer.rwnd;
728
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 /* Keep track of how many bytes are in flight over this transport. */
730 transport->flight_size += datasize;
731
732 /* Keep track of how many bytes are in flight to the receiver. */
733 asoc->outqueue.outstanding_bytes += datasize;
734
Thomas Grafa76c0ad2011-12-19 04:11:40 +0000735 /* Update our view of the receiver's rwnd. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700736 if (datasize < rwnd)
737 rwnd -= datasize;
738 else
739 rwnd = 0;
740
741 asoc->peer.rwnd = rwnd;
742 /* Has been accepted for transmission. */
743 if (!asoc->peer.prsctp_capable)
744 chunk->msg->can_abandon = 0;
Neil Hormand8dd1572009-11-23 15:54:00 -0500745 sctp_chunk_assign_tsn(chunk);
746 sctp_chunk_assign_ssn(chunk);
Vlad Yaseviche83963b2009-08-07 10:43:07 -0400747}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748
Vlad Yaseviche83963b2009-08-07 10:43:07 -0400749static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet,
750 struct sctp_chunk *chunk,
751 u16 chunk_len)
752{
753 size_t psize;
754 size_t pmtu;
755 int too_big;
756 sctp_xmit_t retval = SCTP_XMIT_OK;
757
758 psize = packet->size;
759 pmtu = ((packet->transport->asoc) ?
760 (packet->transport->asoc->pathmtu) :
761 (packet->transport->pathmtu));
762
763 too_big = (psize + chunk_len > pmtu);
764
765 /* Decide if we need to fragment or resubmit later. */
766 if (too_big) {
767 /* It's OK to fragmet at IP level if any one of the following
768 * is true:
769 * 1. The packet is empty (meaning this chunk is greater
770 * the MTU)
771 * 2. The chunk we are adding is a control chunk
772 * 3. The packet doesn't have any data in it yet and data
773 * requires authentication.
774 */
775 if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk) ||
776 (!packet->has_data && chunk->auth)) {
777 /* We no longer do re-fragmentation.
778 * Just fragment at the IP layer, if we
779 * actually hit this condition
780 */
781 packet->ipfragok = 1;
782 } else {
783 retval = SCTP_XMIT_PMTU_FULL;
784 }
785 }
786
Linus Torvalds1da177e2005-04-16 15:20:36 -0700787 return retval;
788}