1// SPDX-License-Identifier: GPL-2.0-or-later
2/* SCTP kernel implementation
3 * Copyright (c) 1999-2000 Cisco, Inc.
4 * Copyright (c) 1999-2001 Motorola, Inc.
5 * Copyright (c) 2001-2002 International Business Machines, Corp.
6 * Copyright (c) 2001 Intel Corp.
7 * Copyright (c) 2001 Nokia, Inc.
8 * Copyright (c) 2001 La Monte H.P. Yarroll
9 *
10 * This file is part of the SCTP kernel implementation
11 *
12 * This abstraction represents an SCTP endpoint.
13 *
14 * Please send any bug reports or fixes you make to the
15 * email address(es):
16 *    lksctp developers <linux-sctp@vger.kernel.org>
17 *
18 * Written or modified by:
19 *    La Monte H.P. Yarroll <piggy@acm.org>
20 *    Karl Knutson <karl@athena.chicago.il.us>
21 *    Jon Grimm <jgrimm@austin.ibm.com>
22 *    Daisy Chang <daisyc@us.ibm.com>
23 *    Dajiang Zhang <dajiang.zhang@nokia.com>
24 */
25
26#include <linux/types.h>
27#include <linux/slab.h>
28#include <linux/in.h>
29#include <linux/random.h>	/* get_random_bytes() */
30#include <net/sock.h>
31#include <net/ipv6.h>
32#include <net/sctp/sctp.h>
33#include <net/sctp/sm.h>
34
35/* Forward declarations for internal helpers. */
36static void sctp_endpoint_bh_rcv(struct work_struct *work);
37
38/*
39 * Initialize the base fields of the endpoint structure.
40 */
41static struct sctp_endpoint *sctp_endpoint_init(struct sctp_endpoint *ep,
42						struct sock *sk,
43						gfp_t gfp)
44{
45	struct net *net = sock_net(sk);
46	struct sctp_shared_key *null_key;
47
48	ep->digest = kzalloc(SCTP_SIGNATURE_SIZE, gfp);
49	if (!ep->digest)
50		return NULL;
51
52	ep->asconf_enable = net->sctp.addip_enable;
53	ep->auth_enable = net->sctp.auth_enable;
54	if (ep->auth_enable) {
55		if (sctp_auth_init(ep, gfp))
56			goto nomem;
57		if (ep->asconf_enable) {
58			sctp_auth_ep_add_chunkid(ep, SCTP_CID_ASCONF);
59			sctp_auth_ep_add_chunkid(ep, SCTP_CID_ASCONF_ACK);
60		}
61	}
62
63	/* Initialize the base structure. */
64	/* What type of endpoint are we?  */
65	ep->base.type = SCTP_EP_TYPE_SOCKET;
66
67	/* Initialize the basic object fields. */
68	refcount_set(&ep->base.refcnt, 1);
69	ep->base.dead = false;
70
71	/* Create an input queue.  */
72	sctp_inq_init(&ep->base.inqueue);
73
74	/* Set its top-half handler */
75	sctp_inq_set_th_handler(&ep->base.inqueue, sctp_endpoint_bh_rcv);
76
77	/* Initialize the bind addr area */
78	sctp_bind_addr_init(&ep->base.bind_addr, 0);
79
80	/* Create the lists of associations.  */
81	INIT_LIST_HEAD(&ep->asocs);
82
83	/* Use SCTP specific send buffer space queues.  */
84	ep->sndbuf_policy = net->sctp.sndbuf_policy;
85
86	sk->sk_data_ready = sctp_data_ready;
87	sk->sk_write_space = sctp_write_space;
88	sock_set_flag(sk, SOCK_USE_WRITE_QUEUE);
89
90	/* Get the receive buffer policy for this endpoint */
91	ep->rcvbuf_policy = net->sctp.rcvbuf_policy;
92
93	/* Initialize the secret key used with cookie. */
94	get_random_bytes(ep->secret_key, sizeof(ep->secret_key));
95
96	/* SCTP-AUTH extensions*/
97	INIT_LIST_HEAD(&ep->endpoint_shared_keys);
98	null_key = sctp_auth_shkey_create(0, gfp);
99	if (!null_key)
100		goto nomem_shkey;
101
102	list_add(&null_key->key_list, &ep->endpoint_shared_keys);
103
104	/* Add the null key to the endpoint shared keys list and
105	 * set the hmcas and chunks pointers.
106	 */
107	ep->prsctp_enable = net->sctp.prsctp_enable;
108	ep->reconf_enable = net->sctp.reconf_enable;
109	ep->ecn_enable = net->sctp.ecn_enable;
110
111	/* Remember who we are attached to.  */
112	ep->base.sk = sk;
113	ep->base.net = sock_net(sk);
114	sock_hold(ep->base.sk);
115
116	return ep;
117
118nomem_shkey:
119	sctp_auth_free(ep);
120nomem:
121	kfree(ep->digest);
122	return NULL;
123
124}
125
126/* Create a sctp_endpoint with all that boring stuff initialized.
127 * Returns NULL if there isn't enough memory.
128 */
129struct sctp_endpoint *sctp_endpoint_new(struct sock *sk, gfp_t gfp)
130{
131	struct sctp_endpoint *ep;
132
133	/* Build a local endpoint. */
134	ep = kzalloc(sizeof(*ep), gfp);
135	if (!ep)
136		goto fail;
137
138	if (!sctp_endpoint_init(ep, sk, gfp))
139		goto fail_init;
140
141	SCTP_DBG_OBJCNT_INC(ep);
142	return ep;
143
144fail_init:
145	kfree(ep);
146fail:
147	return NULL;
148}
149
150/* Add an association to an endpoint.  */
151void sctp_endpoint_add_asoc(struct sctp_endpoint *ep,
152			    struct sctp_association *asoc)
153{
154	struct sock *sk = ep->base.sk;
155
156	/* If this is a temporary association, don't bother
157	 * since we'll be removing it shortly and don't
158	 * want anyone to find it anyway.
159	 */
160	if (asoc->temp)
161		return;
162
163	/* Now just add it to our list of asocs */
164	list_add_tail(&asoc->asocs, &ep->asocs);
165
166	/* Increment the backlog value for a TCP-style listening socket. */
167	if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
168		sk_acceptq_added(sk);
169}
170
171/* Free the endpoint structure.  Delay cleanup until
172 * all users have released their reference count on this structure.
173 */
174void sctp_endpoint_free(struct sctp_endpoint *ep)
175{
176	ep->base.dead = true;
177
178	inet_sk_set_state(ep->base.sk, SCTP_SS_CLOSED);
179
180	/* Unlink this endpoint, so we can't find it again! */
181	sctp_unhash_endpoint(ep);
182
183	sctp_endpoint_put(ep);
184}
185
186/* Final destructor for endpoint.  */
187static void sctp_endpoint_destroy_rcu(struct rcu_head *head)
188{
189	struct sctp_endpoint *ep = container_of(head, struct sctp_endpoint, rcu);
190	struct sock *sk = ep->base.sk;
191
192	sctp_sk(sk)->ep = NULL;
193	sock_put(sk);
194
195	kfree(ep);
196	SCTP_DBG_OBJCNT_DEC(ep);
197}
198
199static void sctp_endpoint_destroy(struct sctp_endpoint *ep)
200{
201	struct sock *sk;
202
203	if (unlikely(!ep->base.dead)) {
204		WARN(1, "Attempt to destroy undead endpoint %p!\n", ep);
205		return;
206	}
207
208	/* Free the digest buffer */
209	kfree(ep->digest);
210
211	/* SCTP-AUTH: Free up AUTH releated data such as shared keys
212	 * chunks and hmacs arrays that were allocated
213	 */
214	sctp_auth_destroy_keys(&ep->endpoint_shared_keys);
215	sctp_auth_free(ep);
216
217	/* Cleanup. */
218	sctp_inq_free(&ep->base.inqueue);
219	sctp_bind_addr_free(&ep->base.bind_addr);
220
221	memset(ep->secret_key, 0, sizeof(ep->secret_key));
222
223	sk = ep->base.sk;
224	/* Remove and free the port */
225	if (sctp_sk(sk)->bind_hash)
226		sctp_put_port(sk);
227
228	call_rcu(&ep->rcu, sctp_endpoint_destroy_rcu);
229}
230
231/* Hold a reference to an endpoint. */
232int sctp_endpoint_hold(struct sctp_endpoint *ep)
233{
234	return refcount_inc_not_zero(&ep->base.refcnt);
235}
236
237/* Release a reference to an endpoint and clean up if there are
238 * no more references.
239 */
240void sctp_endpoint_put(struct sctp_endpoint *ep)
241{
242	if (refcount_dec_and_test(&ep->base.refcnt))
243		sctp_endpoint_destroy(ep);
244}
245
246/* Is this the endpoint we are looking for?  */
247struct sctp_endpoint *sctp_endpoint_is_match(struct sctp_endpoint *ep,
248					       struct net *net,
249					       const union sctp_addr *laddr,
250					       int dif, int sdif)
251{
252	int bound_dev_if = READ_ONCE(ep->base.sk->sk_bound_dev_if);
253	struct sctp_endpoint *retval = NULL;
254
255	if (net_eq(ep->base.net, net) &&
256	    sctp_sk_bound_dev_eq(net, bound_dev_if, dif, sdif) &&
257	    (htons(ep->base.bind_addr.port) == laddr->v4.sin_port)) {
258		if (sctp_bind_addr_match(&ep->base.bind_addr, laddr,
259					 sctp_sk(ep->base.sk)))
260			retval = ep;
261	}
262
263	return retval;
264}
265
266/* Find the association that goes with this chunk.
267 * We lookup the transport from hashtable at first, then get association
268 * through t->assoc.
269 */
270struct sctp_association *sctp_endpoint_lookup_assoc(
271	const struct sctp_endpoint *ep,
272	const union sctp_addr *paddr,
273	struct sctp_transport **transport)
274{
275	struct sctp_association *asoc = NULL;
276	struct sctp_transport *t;
277
278	*transport = NULL;
279
280	/* If the local port is not set, there can't be any associations
281	 * on this endpoint.
282	 */
283	if (!ep->base.bind_addr.port)
284		return NULL;
285
286	rcu_read_lock();
287	t = sctp_epaddr_lookup_transport(ep, paddr);
288	if (!t)
289		goto out;
290
291	*transport = t;
292	asoc = t->asoc;
293out:
294	rcu_read_unlock();
295	return asoc;
296}
297
298/* Look for any peeled off association from the endpoint that matches the
299 * given peer address.
300 */
301bool sctp_endpoint_is_peeled_off(struct sctp_endpoint *ep,
302				 const union sctp_addr *paddr)
303{
304	int bound_dev_if = READ_ONCE(ep->base.sk->sk_bound_dev_if);
305	struct sctp_sockaddr_entry *addr;
306	struct net *net = ep->base.net;
307	struct sctp_bind_addr *bp;
308
309	bp = &ep->base.bind_addr;
310	/* This function is called with the socket lock held,
311	 * so the address_list can not change.
312	 */
313	list_for_each_entry(addr, &bp->address_list, list) {
314		if (sctp_has_association(net, &addr->a, paddr,
315					 bound_dev_if, bound_dev_if))
316			return true;
317	}
318
319	return false;
320}
321
322/* Do delayed input processing.  This is scheduled by sctp_rcv().
323 * This may be called on BH or task time.
324 */
325static void sctp_endpoint_bh_rcv(struct work_struct *work)
326{
327	struct sctp_endpoint *ep =
328		container_of(work, struct sctp_endpoint,
329			     base.inqueue.immediate);
330	struct sctp_association *asoc;
331	struct sock *sk;
332	struct net *net;
333	struct sctp_transport *transport;
334	struct sctp_chunk *chunk;
335	struct sctp_inq *inqueue;
336	union sctp_subtype subtype;
337	enum sctp_state state;
338	int error = 0;
339	int first_time = 1;	/* is this the first time through the loop */
340
341	if (ep->base.dead)
342		return;
343
344	asoc = NULL;
345	inqueue = &ep->base.inqueue;
346	sk = ep->base.sk;
347	net = sock_net(sk);
348
349	while (NULL != (chunk = sctp_inq_pop(inqueue))) {
350		subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
351
352		/* If the first chunk in the packet is AUTH, do special
353		 * processing specified in Section 6.3 of SCTP-AUTH spec
354		 */
355		if (first_time && (subtype.chunk == SCTP_CID_AUTH)) {
356			struct sctp_chunkhdr *next_hdr;
357
358			next_hdr = sctp_inq_peek(inqueue);
359			if (!next_hdr)
360				goto normal;
361
362			/* If the next chunk is COOKIE-ECHO, skip the AUTH
363			 * chunk while saving a pointer to it so we can do
364			 * Authentication later (during cookie-echo
365			 * processing).
366			 */
367			if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
368				chunk->auth_chunk = skb_clone(chunk->skb,
369								GFP_ATOMIC);
370				chunk->auth = 1;
371				continue;
372			}
373		}
374normal:
375		/* We might have grown an association since last we
376		 * looked, so try again.
377		 *
378		 * This happens when we've just processed our
379		 * COOKIE-ECHO chunk.
380		 */
381		if (NULL == chunk->asoc) {
382			asoc = sctp_endpoint_lookup_assoc(ep,
383							  sctp_source(chunk),
384							  &transport);
385			chunk->asoc = asoc;
386			chunk->transport = transport;
387		}
388
389		state = asoc ? asoc->state : SCTP_STATE_CLOSED;
390		if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
391			continue;
392
393		/* Remember where the last DATA chunk came from so we
394		 * know where to send the SACK.
395		 */
396		if (asoc && sctp_chunk_is_data(chunk))
397			asoc->peer.last_data_from = chunk->transport;
398		else {
399			SCTP_INC_STATS(ep->base.net, SCTP_MIB_INCTRLCHUNKS);
400			if (asoc)
401				asoc->stats.ictrlchunks++;
402		}
403
404		if (chunk->transport)
405			chunk->transport->last_time_heard = ktime_get();
406
407		error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype, state,
408				   ep, asoc, chunk, GFP_ATOMIC);
409
410		if (error && chunk)
411			chunk->pdiscard = 1;
412
413		/* Check to see if the endpoint is freed in response to
414		 * the incoming chunk. If so, get out of the while loop.
415		 */
416		if (!sctp_sk(sk)->ep)
417			break;
418
419		if (first_time)
420			first_time = 0;
421	}
422}
423