1/* SCTP kernel reference Implementation
2 * Copyright (c) 1999-2000 Cisco, Inc.
3 * Copyright (c) 1999-2001 Motorola, Inc.
4 * Copyright (c) 2001-2002 International Business Machines, Corp.
5 * Copyright (c) 2001 Intel Corp.
6 * Copyright (c) 2001 Nokia, Inc.
7 * Copyright (c) 2001 La Monte H.P. Yarroll
8 *
9 * This file is part of the SCTP kernel reference Implementation
10 *
11 * This abstraction represents an SCTP endpoint.
12 *
13 * This file is part of the implementation of the add-IP extension,
14 * based on <draft-ietf-tsvwg-addip-sctp-02.txt> June 29, 2001,
15 * for the SCTP kernel reference Implementation.
16 *
17 * The SCTP reference implementation is free software;
18 * you can redistribute it and/or modify it under the terms of
19 * the GNU General Public License as published by
20 * the Free Software Foundation; either version 2, or (at your option)
21 * any later version.
22 *
23 * The SCTP reference implementation is distributed in the hope that it
24 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
25 *                 ************************
26 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
27 * See the GNU General Public License for more details.
28 *
29 * You should have received a copy of the GNU General Public License
30 * along with GNU CC; see the file COPYING.  If not, write to
31 * the Free Software Foundation, 59 Temple Place - Suite 330,
32 * Boston, MA 02111-1307, USA.
33 *
34 * Please send any bug reports or fixes you make to the
35 * email address(es):
36 *    lksctp developers <lksctp-developers@lists.sourceforge.net>
37 *
38 * Or submit a bug report through the following website:
39 *    http://www.sf.net/projects/lksctp
40 *
41 * Written or modified by:
42 *    La Monte H.P. Yarroll <piggy@acm.org>
43 *    Karl Knutson <karl@athena.chicago.il.us>
44 *    Jon Grimm <jgrimm@austin.ibm.com>
45 *    Daisy Chang <daisyc@us.ibm.com>
46 *    Dajiang Zhang <dajiang.zhang@nokia.com>
47 *
48 * Any bugs reported given to us we will try to fix... any fixes shared will
49 * be incorporated into the next SCTP release.
50 */
51
52#include <linux/types.h>
53#include <linux/slab.h>
54#include <linux/in.h>
55#include <linux/random.h>	/* get_random_bytes() */
56#include <linux/crypto.h>
57#include <net/sock.h>
58#include <net/ipv6.h>
59#include <net/sctp/sctp.h>
60#include <net/sctp/sm.h>
61
62/* Forward declarations for internal helpers. */
63static void sctp_endpoint_bh_rcv(struct work_struct *work);
64
65/*
66 * Initialize the base fields of the endpoint structure.
67 */
68static struct sctp_endpoint *sctp_endpoint_init(struct sctp_endpoint *ep,
69						struct sock *sk,
70						gfp_t gfp)
71{
72	memset(ep, 0, sizeof(struct sctp_endpoint));
73
74	ep->digest = kzalloc(SCTP_SIGNATURE_SIZE, gfp);
75	if (!ep->digest)
76		return NULL;
77
78	/* Initialize the base structure. */
79	/* What type of endpoint are we?  */
80	ep->base.type = SCTP_EP_TYPE_SOCKET;
81
82	/* Initialize the basic object fields. */
83	atomic_set(&ep->base.refcnt, 1);
84	ep->base.dead = 0;
85	ep->base.malloced = 1;
86
87	/* Create an input queue.  */
88	sctp_inq_init(&ep->base.inqueue);
89
90	/* Set its top-half handler */
91	sctp_inq_set_th_handler(&ep->base.inqueue, sctp_endpoint_bh_rcv);
92
93	/* Initialize the bind addr area */
94	sctp_bind_addr_init(&ep->base.bind_addr, 0);
95	rwlock_init(&ep->base.addr_lock);
96
97	/* Remember who we are attached to.  */
98	ep->base.sk = sk;
99	sock_hold(ep->base.sk);
100
101	/* Create the lists of associations.  */
102	INIT_LIST_HEAD(&ep->asocs);
103
104	/* Use SCTP specific send buffer space queues.  */
105	ep->sndbuf_policy = sctp_sndbuf_policy;
106	sk->sk_write_space = sctp_write_space;
107	sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
108
109	/* Get the receive buffer policy for this endpoint */
110	ep->rcvbuf_policy = sctp_rcvbuf_policy;
111
112	/* Initialize the secret key used with cookie. */
113	get_random_bytes(&ep->secret_key[0], SCTP_SECRET_SIZE);
114	ep->last_key = ep->current_key = 0;
115	ep->key_changed_at = jiffies;
116
117	return ep;
118}
119
120/* Create a sctp_endpoint with all that boring stuff initialized.
121 * Returns NULL if there isn't enough memory.
122 */
123struct sctp_endpoint *sctp_endpoint_new(struct sock *sk, gfp_t gfp)
124{
125	struct sctp_endpoint *ep;
126
127	/* Build a local endpoint. */
128	ep = t_new(struct sctp_endpoint, gfp);
129	if (!ep)
130		goto fail;
131	if (!sctp_endpoint_init(ep, sk, gfp))
132		goto fail_init;
133	ep->base.malloced = 1;
134	SCTP_DBG_OBJCNT_INC(ep);
135	return ep;
136
137fail_init:
138	kfree(ep);
139fail:
140	return NULL;
141}
142
143/* Add an association to an endpoint.  */
144void sctp_endpoint_add_asoc(struct sctp_endpoint *ep,
145			    struct sctp_association *asoc)
146{
147	struct sock *sk = ep->base.sk;
148
149	/* If this is a temporary association, don't bother
150	 * since we'll be removing it shortly and don't
151	 * want anyone to find it anyway.
152	 */
153	if (asoc->temp)
154		return;
155
156	/* Now just add it to our list of asocs */
157	list_add_tail(&asoc->asocs, &ep->asocs);
158
159	/* Increment the backlog value for a TCP-style listening socket. */
160	if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
161		sk->sk_ack_backlog++;
162}
163
164/* Free the endpoint structure.  Delay cleanup until
165 * all users have released their reference count on this structure.
166 */
167void sctp_endpoint_free(struct sctp_endpoint *ep)
168{
169	ep->base.dead = 1;
170
171	ep->base.sk->sk_state = SCTP_SS_CLOSED;
172
173	/* Unlink this endpoint, so we can't find it again! */
174	sctp_unhash_endpoint(ep);
175
176	sctp_endpoint_put(ep);
177}
178
179/* Final destructor for endpoint.  */
180static void sctp_endpoint_destroy(struct sctp_endpoint *ep)
181{
182	SCTP_ASSERT(ep->base.dead, "Endpoint is not dead", return);
183
184	/* Free up the HMAC transform. */
185	crypto_free_hash(sctp_sk(ep->base.sk)->hmac);
186
187	/* Free the digest buffer */
188	kfree(ep->digest);
189
190	/* Cleanup. */
191	sctp_inq_free(&ep->base.inqueue);
192	sctp_bind_addr_free(&ep->base.bind_addr);
193
194	/* Remove and free the port */
195	if (sctp_sk(ep->base.sk)->bind_hash)
196		sctp_put_port(ep->base.sk);
197
198	/* Give up our hold on the sock. */
199	if (ep->base.sk)
200		sock_put(ep->base.sk);
201
202	/* Finally, free up our memory. */
203	if (ep->base.malloced) {
204		kfree(ep);
205		SCTP_DBG_OBJCNT_DEC(ep);
206	}
207}
208
209/* Hold a reference to an endpoint. */
210void sctp_endpoint_hold(struct sctp_endpoint *ep)
211{
212	atomic_inc(&ep->base.refcnt);
213}
214
215/* Release a reference to an endpoint and clean up if there are
216 * no more references.
217 */
218void sctp_endpoint_put(struct sctp_endpoint *ep)
219{
220	if (atomic_dec_and_test(&ep->base.refcnt))
221		sctp_endpoint_destroy(ep);
222}
223
224/* Is this the endpoint we are looking for?  */
225struct sctp_endpoint *sctp_endpoint_is_match(struct sctp_endpoint *ep,
226					       const union sctp_addr *laddr)
227{
228	struct sctp_endpoint *retval;
229
230	sctp_read_lock(&ep->base.addr_lock);
231	if (htons(ep->base.bind_addr.port) == laddr->v4.sin_port) {
232		if (sctp_bind_addr_match(&ep->base.bind_addr, laddr,
233					 sctp_sk(ep->base.sk))) {
234			retval = ep;
235			goto out;
236		}
237	}
238
239	retval = NULL;
240
241out:
242	sctp_read_unlock(&ep->base.addr_lock);
243	return retval;
244}
245
246/* Find the association that goes with this chunk.
247 * We do a linear search of the associations for this endpoint.
248 * We return the matching transport address too.
249 */
250static struct sctp_association *__sctp_endpoint_lookup_assoc(
251	const struct sctp_endpoint *ep,
252	const union sctp_addr *paddr,
253	struct sctp_transport **transport)
254{
255	int rport;
256	struct sctp_association *asoc;
257	struct list_head *pos;
258
259	rport = ntohs(paddr->v4.sin_port);
260
261	list_for_each(pos, &ep->asocs) {
262		asoc = list_entry(pos, struct sctp_association, asocs);
263		if (rport == asoc->peer.port) {
264			sctp_read_lock(&asoc->base.addr_lock);
265			*transport = sctp_assoc_lookup_paddr(asoc, paddr);
266			sctp_read_unlock(&asoc->base.addr_lock);
267
268			if (*transport)
269				return asoc;
270		}
271	}
272
273	*transport = NULL;
274	return NULL;
275}
276
277/* Lookup association on an endpoint based on a peer address.  BH-safe.  */
278struct sctp_association *sctp_endpoint_lookup_assoc(
279	const struct sctp_endpoint *ep,
280	const union sctp_addr *paddr,
281	struct sctp_transport **transport)
282{
283	struct sctp_association *asoc;
284
285	sctp_local_bh_disable();
286	asoc = __sctp_endpoint_lookup_assoc(ep, paddr, transport);
287	sctp_local_bh_enable();
288
289	return asoc;
290}
291
292/* Look for any peeled off association from the endpoint that matches the
293 * given peer address.
294 */
295int sctp_endpoint_is_peeled_off(struct sctp_endpoint *ep,
296				const union sctp_addr *paddr)
297{
298	struct list_head *pos;
299	struct sctp_sockaddr_entry *addr;
300	struct sctp_bind_addr *bp;
301
302	sctp_read_lock(&ep->base.addr_lock);
303	bp = &ep->base.bind_addr;
304	list_for_each(pos, &bp->address_list) {
305		addr = list_entry(pos, struct sctp_sockaddr_entry, list);
306		if (sctp_has_association(&addr->a, paddr)) {
307			sctp_read_unlock(&ep->base.addr_lock);
308			return 1;
309		}
310	}
311	sctp_read_unlock(&ep->base.addr_lock);
312
313	return 0;
314}
315
316/* Do delayed input processing.  This is scheduled by sctp_rcv().
317 * This may be called on BH or task time.
318 */
319static void sctp_endpoint_bh_rcv(struct work_struct *work)
320{
321	struct sctp_endpoint *ep =
322		container_of(work, struct sctp_endpoint,
323			     base.inqueue.immediate);
324	struct sctp_association *asoc;
325	struct sock *sk;
326	struct sctp_transport *transport;
327	struct sctp_chunk *chunk;
328	struct sctp_inq *inqueue;
329	sctp_subtype_t subtype;
330	sctp_state_t state;
331	int error = 0;
332
333	if (ep->base.dead)
334		return;
335
336	asoc = NULL;
337	inqueue = &ep->base.inqueue;
338	sk = ep->base.sk;
339
340	while (NULL != (chunk = sctp_inq_pop(inqueue))) {
341		subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
342
343		/* We might have grown an association since last we
344		 * looked, so try again.
345		 *
346		 * This happens when we've just processed our
347		 * COOKIE-ECHO chunk.
348		 */
349		if (NULL == chunk->asoc) {
350			asoc = sctp_endpoint_lookup_assoc(ep,
351							  sctp_source(chunk),
352							  &transport);
353			chunk->asoc = asoc;
354			chunk->transport = transport;
355		}
356
357		state = asoc ? asoc->state : SCTP_STATE_CLOSED;
358
359		/* Remember where the last DATA chunk came from so we
360		 * know where to send the SACK.
361		 */
362		if (asoc && sctp_chunk_is_data(chunk))
363			asoc->peer.last_data_from = chunk->transport;
364		else
365			SCTP_INC_STATS(SCTP_MIB_INCTRLCHUNKS);
366
367		if (chunk->transport)
368			chunk->transport->last_time_heard = jiffies;
369
370		error = sctp_do_sm(SCTP_EVENT_T_CHUNK, subtype, state,
371				   ep, asoc, chunk, GFP_ATOMIC);
372
373		if (error && chunk)
374			chunk->pdiscard = 1;
375
376		/* Check to see if the endpoint is freed in response to
377		 * the incoming chunk. If so, get out of the while loop.
378		 */
379		if (!sctp_sk(sk)->ep)
380			break;
381	}
382}
383