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. */
50static 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. */
62static 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
73void 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. */
87static 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. */
138static void sctp_datamsg_hold(struct sctp_datamsg *msg)
139{
140	atomic_inc(&msg->refcnt);
141}
142
143/* Release a reference. */
144void 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. */
151static 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 */
165struct 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
333errout_chunk_free:
334	sctp_chunk_free(chunk);
335
336errout:
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. */
347int 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. */
361void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
362{
363	chunk->msg->send_failed = 1;
364	chunk->msg->send_error = error;
365}
366