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. */
36 static void sctp_endpoint_bh_rcv(struct work_struct *work);
37 
38 /*
39  * Initialize the base fields of the endpoint structure.
40  */
sctp_endpoint_init(struct sctp_endpoint * ep,struct sock * sk,gfp_t gfp)41 static 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 
118 nomem_shkey:
119 	sctp_auth_free(ep);
120 nomem:
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  */
sctp_endpoint_new(struct sock * sk,gfp_t gfp)129 struct 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 
144 fail_init:
145 	kfree(ep);
146 fail:
147 	return NULL;
148 }
149 
150 /* Add an association to an endpoint.  */
sctp_endpoint_add_asoc(struct sctp_endpoint * ep,struct sctp_association * asoc)151 void 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  */
sctp_endpoint_free(struct sctp_endpoint * ep)174 void 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.  */
sctp_endpoint_destroy_rcu(struct rcu_head * head)187 static 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 
sctp_endpoint_destroy(struct sctp_endpoint * ep)199 static 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. */
sctp_endpoint_hold(struct sctp_endpoint * ep)232 int 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  */
sctp_endpoint_put(struct sctp_endpoint * ep)240 void 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?  */
sctp_endpoint_is_match(struct sctp_endpoint * ep,struct net * net,const union sctp_addr * laddr)247 struct sctp_endpoint *sctp_endpoint_is_match(struct sctp_endpoint *ep,
248 					       struct net *net,
249 					       const union sctp_addr *laddr)
250 {
251 	struct sctp_endpoint *retval = NULL;
252 
253 	if ((htons(ep->base.bind_addr.port) == laddr->v4.sin_port) &&
254 	    net_eq(ep->base.net, net)) {
255 		if (sctp_bind_addr_match(&ep->base.bind_addr, laddr,
256 					 sctp_sk(ep->base.sk)))
257 			retval = ep;
258 	}
259 
260 	return retval;
261 }
262 
263 /* Find the association that goes with this chunk.
264  * We lookup the transport from hashtable at first, then get association
265  * through t->assoc.
266  */
sctp_endpoint_lookup_assoc(const struct sctp_endpoint * ep,const union sctp_addr * paddr,struct sctp_transport ** transport)267 struct sctp_association *sctp_endpoint_lookup_assoc(
268 	const struct sctp_endpoint *ep,
269 	const union sctp_addr *paddr,
270 	struct sctp_transport **transport)
271 {
272 	struct sctp_association *asoc = NULL;
273 	struct sctp_transport *t;
274 
275 	*transport = NULL;
276 
277 	/* If the local port is not set, there can't be any associations
278 	 * on this endpoint.
279 	 */
280 	if (!ep->base.bind_addr.port)
281 		return NULL;
282 
283 	rcu_read_lock();
284 	t = sctp_epaddr_lookup_transport(ep, paddr);
285 	if (!t)
286 		goto out;
287 
288 	*transport = t;
289 	asoc = t->asoc;
290 out:
291 	rcu_read_unlock();
292 	return asoc;
293 }
294 
295 /* Look for any peeled off association from the endpoint that matches the
296  * given peer address.
297  */
sctp_endpoint_is_peeled_off(struct sctp_endpoint * ep,const union sctp_addr * paddr)298 bool sctp_endpoint_is_peeled_off(struct sctp_endpoint *ep,
299 				 const union sctp_addr *paddr)
300 {
301 	struct sctp_sockaddr_entry *addr;
302 	struct net *net = ep->base.net;
303 	struct sctp_bind_addr *bp;
304 
305 	bp = &ep->base.bind_addr;
306 	/* This function is called with the socket lock held,
307 	 * so the address_list can not change.
308 	 */
309 	list_for_each_entry(addr, &bp->address_list, list) {
310 		if (sctp_has_association(net, &addr->a, paddr))
311 			return true;
312 	}
313 
314 	return false;
315 }
316 
317 /* Do delayed input processing.  This is scheduled by sctp_rcv().
318  * This may be called on BH or task time.
319  */
sctp_endpoint_bh_rcv(struct work_struct * work)320 static void sctp_endpoint_bh_rcv(struct work_struct *work)
321 {
322 	struct sctp_endpoint *ep =
323 		container_of(work, struct sctp_endpoint,
324 			     base.inqueue.immediate);
325 	struct sctp_association *asoc;
326 	struct sock *sk;
327 	struct net *net;
328 	struct sctp_transport *transport;
329 	struct sctp_chunk *chunk;
330 	struct sctp_inq *inqueue;
331 	union sctp_subtype subtype;
332 	enum sctp_state state;
333 	int error = 0;
334 	int first_time = 1;	/* is this the first time through the loop */
335 
336 	if (ep->base.dead)
337 		return;
338 
339 	asoc = NULL;
340 	inqueue = &ep->base.inqueue;
341 	sk = ep->base.sk;
342 	net = sock_net(sk);
343 
344 	while (NULL != (chunk = sctp_inq_pop(inqueue))) {
345 		subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
346 
347 		/* If the first chunk in the packet is AUTH, do special
348 		 * processing specified in Section 6.3 of SCTP-AUTH spec
349 		 */
350 		if (first_time && (subtype.chunk == SCTP_CID_AUTH)) {
351 			struct sctp_chunkhdr *next_hdr;
352 
353 			next_hdr = sctp_inq_peek(inqueue);
354 			if (!next_hdr)
355 				goto normal;
356 
357 			/* If the next chunk is COOKIE-ECHO, skip the AUTH
358 			 * chunk while saving a pointer to it so we can do
359 			 * Authentication later (during cookie-echo
360 			 * processing).
361 			 */
362 			if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
363 				chunk->auth_chunk = skb_clone(chunk->skb,
364 								GFP_ATOMIC);
365 				chunk->auth = 1;
366 				continue;
367 			}
368 		}
369 normal:
370 		/* We might have grown an association since last we
371 		 * looked, so try again.
372 		 *
373 		 * This happens when we've just processed our
374 		 * COOKIE-ECHO chunk.
375 		 */
376 		if (NULL == chunk->asoc) {
377 			asoc = sctp_endpoint_lookup_assoc(ep,
378 							  sctp_source(chunk),
379 							  &transport);
380 			chunk->asoc = asoc;
381 			chunk->transport = transport;
382 		}
383 
384 		state = asoc ? asoc->state : SCTP_STATE_CLOSED;
385 		if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
386 			continue;
387 
388 		/* Remember where the last DATA chunk came from so we
389 		 * know where to send the SACK.
390 		 */
391 		if (asoc && sctp_chunk_is_data(chunk))
392 			asoc->peer.last_data_from = chunk->transport;
393 		else {
394 			SCTP_INC_STATS(ep->base.net, SCTP_MIB_INCTRLCHUNKS);
395 			if (asoc)
396 				asoc->stats.ictrlchunks++;
397 		}
398 
399 		if (chunk->transport)
400 			chunk->transport->last_time_heard = ktime_get();
401 
402 		error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype, state,
403 				   ep, asoc, chunk, GFP_ATOMIC);
404 
405 		if (error && chunk)
406 			chunk->pdiscard = 1;
407 
408 		/* Check to see if the endpoint is freed in response to
409 		 * the incoming chunk. If so, get out of the while loop.
410 		 */
411 		if (!sctp_sk(sk)->ep)
412 			break;
413 
414 		if (first_time)
415 			first_time = 0;
416 	}
417 }
418