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 */
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 */
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. */
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 */
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. */
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
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. */
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 */
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? */
247 struct 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 */
270 struct 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;
293 out:
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 */
301 bool 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 */
325 static 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 }
374 normal:
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
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