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1 /* SCTP kernel implementation
2 * (C) Copyright IBM Corp. 2003, 2004
3 *
4 * This file is part of the SCTP kernel implementation
5 *
6 * This file contains the code relating the chunk abstraction.
7 *
8 * This SCTP implementation is free software;
9 * you can redistribute it and/or modify it under the terms of
10 * the GNU General Public License as published by
11 * the Free Software Foundation; either version 2, or (at your option)
12 * any later version.
13 *
14 * This SCTP implementation is distributed in the hope that it
15 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
16 * ************************
17 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
18 * See the GNU General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with GNU CC; see the file COPYING. If not, see
22 * <http://www.gnu.org/licenses/>.
23 *
24 * Please send any bug reports or fixes you make to the
25 * email address(es):
26 * lksctp developers <linux-sctp@vger.kernel.org>
27 *
28 * Written or modified by:
29 * Jon Grimm <jgrimm@us.ibm.com>
30 * Sridhar Samudrala <sri@us.ibm.com>
31 */
32
33 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34
35 #include <linux/types.h>
36 #include <linux/kernel.h>
37 #include <linux/net.h>
38 #include <linux/inet.h>
39 #include <linux/skbuff.h>
40 #include <linux/slab.h>
41 #include <net/sock.h>
42 #include <net/sctp/sctp.h>
43 #include <net/sctp/sm.h>
44
45 /* This file is mostly in anticipation of future work, but initially
46 * populate with fragment tracking for an outbound message.
47 */
48
49 /* Initialize datamsg from memory. */
50 static void sctp_datamsg_init(struct sctp_datamsg *msg)
51 {
52 atomic_set(&msg->refcnt, 1);
53 msg->send_failed = 0;
54 msg->send_error = 0;
55 msg->can_abandon = 0;
56 msg->can_delay = 1;
57 msg->expires_at = 0;
58 INIT_LIST_HEAD(&msg->chunks);
59 }
60
61 /* Allocate and initialize datamsg. */
62 static struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)
63 {
64 struct sctp_datamsg *msg;
65 msg = kmalloc(sizeof(struct sctp_datamsg), gfp);
66 if (msg) {
67 sctp_datamsg_init(msg);
68 SCTP_DBG_OBJCNT_INC(datamsg);
69 }
70 return msg;
71 }
72
73 void sctp_datamsg_free(struct sctp_datamsg *msg)
74 {
75 struct sctp_chunk *chunk;
76
77 /* This doesn't have to be a _safe vairant because
78 * sctp_chunk_free() only drops the refs.
79 */
80 list_for_each_entry(chunk, &msg->chunks, frag_list)
81 sctp_chunk_free(chunk);
82
83 sctp_datamsg_put(msg);
84 }
85
86 /* Final destructruction of datamsg memory. */
87 static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
88 {
89 struct list_head *pos, *temp;
90 struct sctp_chunk *chunk;
91 struct sctp_sock *sp;
92 struct sctp_ulpevent *ev;
93 struct sctp_association *asoc = NULL;
94 int error = 0, notify;
95
96 /* If we failed, we may need to notify. */
97 notify = msg->send_failed ? -1 : 0;
98
99 /* Release all references. */
100 list_for_each_safe(pos, temp, &msg->chunks) {
101 list_del_init(pos);
102 chunk = list_entry(pos, struct sctp_chunk, frag_list);
103 /* Check whether we _really_ need to notify. */
104 if (notify < 0) {
105 asoc = chunk->asoc;
106 if (msg->send_error)
107 error = msg->send_error;
108 else
109 error = asoc->outqueue.error;
110
111 sp = sctp_sk(asoc->base.sk);
112 notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,
113 &sp->subscribe);
114 }
115
116 /* Generate a SEND FAILED event only if enabled. */
117 if (notify > 0) {
118 int sent;
119 if (chunk->has_tsn)
120 sent = SCTP_DATA_SENT;
121 else
122 sent = SCTP_DATA_UNSENT;
123
124 ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
125 error, GFP_ATOMIC);
126 if (ev)
127 sctp_ulpq_tail_event(&asoc->ulpq, ev);
128 }
129
130 sctp_chunk_put(chunk);
131 }
132
133 SCTP_DBG_OBJCNT_DEC(datamsg);
134 kfree(msg);
135 }
136
137 /* Hold a reference. */
138 static void sctp_datamsg_hold(struct sctp_datamsg *msg)
139 {
140 atomic_inc(&msg->refcnt);
141 }
142
143 /* Release a reference. */
144 void sctp_datamsg_put(struct sctp_datamsg *msg)
145 {
146 if (atomic_dec_and_test(&msg->refcnt))
147 sctp_datamsg_destroy(msg);
148 }
149
150 /* Assign a chunk to this datamsg. */
151 static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
152 {
153 sctp_datamsg_hold(msg);
154 chunk->msg = msg;
155 }
156
157
158 /* A data chunk can have a maximum payload of (2^16 - 20). Break
159 * down any such message into smaller chunks. Opportunistically, fragment
160 * the chunks down to the current MTU constraints. We may get refragmented
161 * later if the PMTU changes, but it is _much better_ to fragment immediately
162 * with a reasonable guess than always doing our fragmentation on the
163 * soft-interrupt.
164 */
165 struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
166 struct sctp_sndrcvinfo *sinfo,
167 struct iov_iter *from)
168 {
169 int max, whole, i, offset, over, err;
170 int len, first_len;
171 int max_data;
172 struct sctp_chunk *chunk;
173 struct sctp_datamsg *msg;
174 struct list_head *pos, *temp;
175 size_t msg_len = iov_iter_count(from);
176 __u8 frag;
177
178 msg = sctp_datamsg_new(GFP_KERNEL);
179 if (!msg)
180 return ERR_PTR(-ENOMEM);
181
182 /* Note: Calculate this outside of the loop, so that all fragments
183 * have the same expiration.
184 */
185 if (sinfo->sinfo_timetolive) {
186 /* sinfo_timetolive is in milliseconds */
187 msg->expires_at = jiffies +
188 msecs_to_jiffies(sinfo->sinfo_timetolive);
189 msg->can_abandon = 1;
190
191 pr_debug("%s: msg:%p expires_at:%ld jiffies:%ld\n", __func__,
192 msg, msg->expires_at, jiffies);
193 }
194
195 /* This is the biggest possible DATA chunk that can fit into
196 * the packet
197 */
198 max_data = (asoc->pathmtu -
199 sctp_sk(asoc->base.sk)->pf->af->net_header_len -
200 sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk)) & ~3;
201
202 max = asoc->frag_point;
203 /* If the the peer requested that we authenticate DATA chunks
204 * we need to account for bundling of the AUTH chunks along with
205 * DATA.
206 */
207 if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
208 struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);
209
210 if (hmac_desc)
211 max_data -= WORD_ROUND(sizeof(sctp_auth_chunk_t) +
212 hmac_desc->hmac_len);
213 }
214
215 /* Now, check if we need to reduce our max */
216 if (max > max_data)
217 max = max_data;
218
219 whole = 0;
220 first_len = max;
221
222 /* Check to see if we have a pending SACK and try to let it be bundled
223 * with this message. Do this if we don't have any data queued already.
224 * To check that, look at out_qlen and retransmit list.
225 * NOTE: we will not reduce to account for SACK, if the message would
226 * not have been fragmented.
227 */
228 if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) &&
229 asoc->outqueue.out_qlen == 0 &&
230 list_empty(&asoc->outqueue.retransmit) &&
231 msg_len > max)
232 max_data -= WORD_ROUND(sizeof(sctp_sack_chunk_t));
233
234 /* Encourage Cookie-ECHO bundling. */
235 if (asoc->state < SCTP_STATE_COOKIE_ECHOED)
236 max_data -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;
237
238 /* Now that we adjusted completely, reset first_len */
239 if (first_len > max_data)
240 first_len = max_data;
241
242 /* Account for a different sized first fragment */
243 if (msg_len >= first_len) {
244 msg_len -= first_len;
245 whole = 1;
246 msg->can_delay = 0;
247 }
248
249 /* How many full sized? How many bytes leftover? */
250 whole += msg_len / max;
251 over = msg_len % max;
252 offset = 0;
253
254 if ((whole > 1) || (whole && over))
255 SCTP_INC_STATS_USER(sock_net(asoc->base.sk), SCTP_MIB_FRAGUSRMSGS);
256
257 /* Create chunks for all the full sized DATA chunks. */
258 for (i = 0, len = first_len; i < whole; i++) {
259 frag = SCTP_DATA_MIDDLE_FRAG;
260
261 if (0 == i)
262 frag |= SCTP_DATA_FIRST_FRAG;
263
264 if ((i == (whole - 1)) && !over) {
265 frag |= SCTP_DATA_LAST_FRAG;
266
267 /* The application requests to set the I-bit of the
268 * last DATA chunk of a user message when providing
269 * the user message to the SCTP implementation.
270 */
271 if ((sinfo->sinfo_flags & SCTP_EOF) ||
272 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
273 frag |= SCTP_DATA_SACK_IMM;
274 }
275
276 chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag, 0);
277
278 if (!chunk) {
279 err = -ENOMEM;
280 goto errout;
281 }
282
283 err = sctp_user_addto_chunk(chunk, len, from);
284 if (err < 0)
285 goto errout_chunk_free;
286
287 /* Put the chunk->skb back into the form expected by send. */
288 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
289 - (__u8 *)chunk->skb->data);
290
291 sctp_datamsg_assign(msg, chunk);
292 list_add_tail(&chunk->frag_list, &msg->chunks);
293
294 /* The first chunk, the first chunk was likely short
295 * to allow bundling, so reset to full size.
296 */
297 if (0 == i)
298 len = max;
299 }
300
301 /* .. now the leftover bytes. */
302 if (over) {
303 if (!whole)
304 frag = SCTP_DATA_NOT_FRAG;
305 else
306 frag = SCTP_DATA_LAST_FRAG;
307
308 if ((sinfo->sinfo_flags & SCTP_EOF) ||
309 (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
310 frag |= SCTP_DATA_SACK_IMM;
311
312 chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag, 0);
313
314 if (!chunk) {
315 err = -ENOMEM;
316 goto errout;
317 }
318
319 err = sctp_user_addto_chunk(chunk, over, from);
320
321 /* Put the chunk->skb back into the form expected by send. */
322 __skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
323 - (__u8 *)chunk->skb->data);
324 if (err < 0)
325 goto errout_chunk_free;
326
327 sctp_datamsg_assign(msg, chunk);
328 list_add_tail(&chunk->frag_list, &msg->chunks);
329 }
330
331 return msg;
332
333 errout_chunk_free:
334 sctp_chunk_free(chunk);
335
336 errout:
337 list_for_each_safe(pos, temp, &msg->chunks) {
338 list_del_init(pos);
339 chunk = list_entry(pos, struct sctp_chunk, frag_list);
340 sctp_chunk_free(chunk);
341 }
342 sctp_datamsg_put(msg);
343 return ERR_PTR(err);
344 }
345
346 /* Check whether this message has expired. */
347 int sctp_chunk_abandoned(struct sctp_chunk *chunk)
348 {
349 struct sctp_datamsg *msg = chunk->msg;
350
351 if (!msg->can_abandon)
352 return 0;
353
354 if (time_after(jiffies, msg->expires_at))
355 return 1;
356
357 return 0;
358 }
359
360 /* This chunk (and consequently entire message) has failed in its sending. */
361 void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
362 {
363 chunk->msg->send_failed = 1;
364 chunk->msg->send_error = error;
365 }