aboutsummaryrefslogtreecommitdiffstats
path: root/net/sctp/chunk.c
blob: a55e54738b81ff8cf9cd711cf5fc466ac71374c0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
/* SCTP kernel implementation
 * (C) Copyright IBM Corp. 2003, 2004
 *
 * This file is part of the SCTP kernel implementation
 *
 * This file contains the code relating the chunk abstraction.
 *
 * This SCTP implementation is free software;
 * you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This SCTP implementation is distributed in the hope that it
 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 *                 ************************
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU CC; see the file COPYING.  If not, see
 * <http://www.gnu.org/licenses/>.
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <linux-sctp@vger.kernel.org>
 *
 * Written or modified by:
 *    Jon Grimm             <jgrimm@us.ibm.com>
 *    Sridhar Samudrala     <sri@us.ibm.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/net.h>
#include <linux/inet.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>

/* This file is mostly in anticipation of future work, but initially
 * populate with fragment tracking for an outbound message.
 */

/* Initialize datamsg from memory. */
static void sctp_datamsg_init(struct sctp_datamsg *msg)
{
	atomic_set(&msg->refcnt, 1);
	msg->send_failed = 0;
	msg->send_error = 0;
	msg->can_abandon = 0;
	msg->can_delay = 1;
	msg->expires_at = 0;
	INIT_LIST_HEAD(&msg->chunks);
}

/* Allocate and initialize datamsg. */
static struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)
{
	struct sctp_datamsg *msg;
	msg = kmalloc(sizeof(struct sctp_datamsg), gfp);
	if (msg) {
		sctp_datamsg_init(msg);
		SCTP_DBG_OBJCNT_INC(datamsg);
	}
	return msg;
}

/* Final destructruction of datamsg memory. */
static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
{
	struct list_head *pos, *temp;
	struct sctp_chunk *chunk;
	struct sctp_sock *sp;
	struct sctp_ulpevent *ev;
	struct sctp_association *asoc = NULL;
	int error = 0, notify;

	/* If we failed, we may need to notify. */
	notify = msg->send_failed ? -1 : 0;

	/* Release all references. */
	list_for_each_safe(pos, temp, &msg->chunks) {
		list_del_init(pos);
		chunk = list_entry(pos, struct sctp_chunk, frag_list);
		/* Check whether we _really_ need to notify. */
		if (notify < 0) {
			asoc = chunk->asoc;
			if (msg->send_error)
				error = msg->send_error;
			else
				error = asoc->outqueue.error;

			sp = sctp_sk(asoc->base.sk);
			notify = sctp_ulpevent_type_enabled(SCTP_SEND_FAILED,
							    &sp->subscribe);
		}

		/* Generate a SEND FAILED event only if enabled. */
		if (notify > 0) {
			int sent;
			if (chunk->has_tsn)
				sent = SCTP_DATA_SENT;
			else
				sent = SCTP_DATA_UNSENT;

			ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
							    error, GFP_ATOMIC);
			if (ev)
				sctp_ulpq_tail_event(&asoc->ulpq, ev);
		}

		sctp_chunk_put(chunk);
	}

	SCTP_DBG_OBJCNT_DEC(datamsg);
	kfree(msg);
}

/* Hold a reference. */
static void sctp_datamsg_hold(struct sctp_datamsg *msg)
{
	atomic_inc(&msg->refcnt);
}

/* Release a reference. */
void sctp_datamsg_put(struct sctp_datamsg *msg)
{
	if (atomic_dec_and_test(&msg->refcnt))
		sctp_datamsg_destroy(msg);
}

/* Assign a chunk to this datamsg. */
static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
{
	sctp_datamsg_hold(msg);
	chunk->msg = msg;
}


/* A data chunk can have a maximum payload of (2^16 - 20).  Break
 * down any such message into smaller chunks.  Opportunistically, fragment
 * the chunks down to the current MTU constraints.  We may get refragmented
 * later if the PMTU changes, but it is _much better_ to fragment immediately
 * with a reasonable guess than always doing our fragmentation on the
 * soft-interrupt.
 */
struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
					    struct sctp_sndrcvinfo *sinfo,
					    struct iov_iter *from)
{
	int max, whole, i, offset, over, err;
	int len, first_len;
	int max_data;
	struct sctp_chunk *chunk;
	struct sctp_datamsg *msg;
	struct list_head *pos, *temp;
	size_t msg_len = iov_iter_count(from);
	__u8 frag;

	msg = sctp_datamsg_new(GFP_KERNEL);
	if (!msg)
		return ERR_PTR(-ENOMEM);

	/* Note: Calculate this outside of the loop, so that all fragments
	 * have the same expiration.
	 */
	if (sinfo->sinfo_timetolive) {
		/* sinfo_timetolive is in milliseconds */
		msg->expires_at = jiffies +
				    msecs_to_jiffies(sinfo->sinfo_timetolive);
		msg->can_abandon = 1;

		pr_debug("%s: msg:%p expires_at:%ld jiffies:%ld\n", __func__,
			 msg, msg->expires_at, jiffies);
	}

	/* This is the biggest possible DATA chunk that can fit into
	 * the packet
	 */
	max_data = (asoc->pathmtu -
		sctp_sk(asoc->base.sk)->pf->af->net_header_len -
		sizeof(struct sctphdr) - sizeof(struct sctp_data_chunk)) & ~3;

	max = asoc->frag_point;
	/* If the the peer requested that we authenticate DATA chunks
	 * we need to account for bundling of the AUTH chunks along with
	 * DATA.
	 */
	if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
		struct sctp_hmac *hmac_desc = sctp_auth_asoc_get_hmac(asoc);

		if (hmac_desc)
			max_data -= WORD_ROUND(sizeof(sctp_auth_chunk_t) +
					    hmac_desc->hmac_len);
	}

	/* Now, check if we need to reduce our max */
	if (max > max_data)
		max = max_data;

	whole = 0;
	first_len = max;

	/* Check to see if we have a pending SACK and try to let it be bundled
	 * with this message.  Do this if we don't have any data queued already.
	 * To check that, look at out_qlen and retransmit list.
	 * NOTE: we will not reduce to account for SACK, if the message would
	 * not have been fragmented.
	 */
	if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) &&
	    asoc->outqueue.out_qlen == 0 &&
	    list_empty(&asoc->outqueue.retransmit) &&
	    msg_len > max)
		max_data -= WORD_ROUND(sizeof(sctp_sack_chunk_t));

	/* Encourage Cookie-ECHO bundling. */
	if (asoc->state < SCTP_STATE_COOKIE_ECHOED)
		max_data -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;

	/* Now that we adjusted completely, reset first_len */
	if (first_len > max_data)
		first_len = max_data;

	/* Account for a different sized first fragment */
	if (msg_len >= first_len) {
		msg_len -= first_len;
		whole = 1;
		msg->can_delay = 0;
	}

	/* How many full sized?  How many bytes leftover? */
	whole += msg_len / max;
	over = msg_len % max;
	offset = 0;

	if ((whole > 1) || (whole && over))
		SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_FRAGUSRMSGS);

	/* Create chunks for all the full sized DATA chunks. */
	for (i = 0, len = first_len; i < whole; i++) {
		frag = SCTP_DATA_MIDDLE_FRAG;

		if (0 == i)
			frag |= SCTP_DATA_FIRST_FRAG;

		if ((i == (whole - 1)) && !over) {
			frag |= SCTP_DATA_LAST_FRAG;

			/* The application requests to set the I-bit of the
			 * last DATA chunk of a user message when providing
			 * the user message to the SCTP implementation.
			 */
			if ((sinfo->sinfo_flags & SCTP_EOF) ||
			    (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
				frag |= SCTP_DATA_SACK_IMM;
		}

		chunk = sctp_make_datafrag_empty(asoc, sinfo, len, frag,
						 0, GFP_KERNEL);

		if (!chunk) {
			err = -ENOMEM;
			goto errout;
		}

		err = sctp_user_addto_chunk(chunk, len, from);
		if (err < 0)
			goto errout_chunk_free;

		/* Put the chunk->skb back into the form expected by send.  */
		__skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
			   - (__u8 *)chunk->skb->data);

		sctp_datamsg_assign(msg, chunk);
		list_add_tail(&chunk->frag_list, &msg->chunks);

		/* The first chunk, the first chunk was likely short
		 * to allow bundling, so reset to full size.
		 */
		if (0 == i)
			len = max;
	}

	/* .. now the leftover bytes. */
	if (over) {
		if (!whole)
			frag = SCTP_DATA_NOT_FRAG;
		else
			frag = SCTP_DATA_LAST_FRAG;

		if ((sinfo->sinfo_flags & SCTP_EOF) ||
		    (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
			frag |= SCTP_DATA_SACK_IMM;

		chunk = sctp_make_datafrag_empty(asoc, sinfo, over, frag,
						 0, GFP_KERNEL);

		if (!chunk) {
			err = -ENOMEM;
			goto errout;
		}

		err = sctp_user_addto_chunk(chunk, over, from);

		/* Put the chunk->skb back into the form expected by send.  */
		__skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr
			   - (__u8 *)chunk->skb->data);
		if (err < 0)
			goto errout_chunk_free;

		sctp_datamsg_assign(msg, chunk);
		list_add_tail(&chunk->frag_list, &msg->chunks);
	}

	return msg;

errout_chunk_free:
	sctp_chunk_free(chunk);

errout:
	list_for_each_safe(pos, temp, &msg->chunks) {
		list_del_init(pos);
		chunk = list_entry(pos, struct sctp_chunk, frag_list);
		sctp_chunk_free(chunk);
	}
	sctp_datamsg_put(msg);
	return ERR_PTR(err);
}

/* Check whether this message has expired. */
int sctp_chunk_abandoned(struct sctp_chunk *chunk)
{
	if (!chunk->asoc->prsctp_enable ||
	    !SCTP_PR_POLICY(chunk->sinfo.sinfo_flags)) {
		struct sctp_datamsg *msg = chunk->msg;

		if (!msg->can_abandon)
			return 0;

		if (time_after(jiffies, msg->expires_at))
			return 1;

		return 0;
	}

	if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) &&
	    time_after(jiffies, chunk->prsctp_param)) {
		if (chunk->sent_count)
			chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
		else
			chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
		return 1;
	} else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) &&
		   chunk->sent_count > chunk->prsctp_param) {
		chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
		return 1;
	}
	/* PRIO policy is processed by sendmsg, not here */

	return 0;
}

/* This chunk (and consequently entire message) has failed in its sending. */
void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
{
	chunk->msg->send_failed = 1;
	chunk->msg->send_error = error;
}

Privacy Policy