xref: /openbmc/linux/net/sctp/chunk.c (revision 8b235f2f)
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  }
366