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 sock_hold(ep->base.sk);
114
115 return ep;
116
117 nomem_shkey:
118 sctp_auth_free(ep);
119 nomem:
120 kfree(ep->digest);
121 return NULL;
122
123 }
124
125 /* Create a sctp_endpoint with all that boring stuff initialized.
126 * Returns NULL if there isn't enough memory.
127 */
sctp_endpoint_new(struct sock * sk,gfp_t gfp)128 struct sctp_endpoint *sctp_endpoint_new(struct sock *sk, gfp_t gfp)
129 {
130 struct sctp_endpoint *ep;
131
132 /* Build a local endpoint. */
133 ep = kzalloc(sizeof(*ep), gfp);
134 if (!ep)
135 goto fail;
136
137 if (!sctp_endpoint_init(ep, sk, gfp))
138 goto fail_init;
139
140 SCTP_DBG_OBJCNT_INC(ep);
141 return ep;
142
143 fail_init:
144 kfree(ep);
145 fail:
146 return NULL;
147 }
148
149 /* Add an association to an endpoint. */
sctp_endpoint_add_asoc(struct sctp_endpoint * ep,struct sctp_association * asoc)150 void sctp_endpoint_add_asoc(struct sctp_endpoint *ep,
151 struct sctp_association *asoc)
152 {
153 struct sock *sk = ep->base.sk;
154
155 /* If this is a temporary association, don't bother
156 * since we'll be removing it shortly and don't
157 * want anyone to find it anyway.
158 */
159 if (asoc->temp)
160 return;
161
162 /* Now just add it to our list of asocs */
163 list_add_tail(&asoc->asocs, &ep->asocs);
164
165 /* Increment the backlog value for a TCP-style listening socket. */
166 if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
167 sk->sk_ack_backlog++;
168 }
169
170 /* Free the endpoint structure. Delay cleanup until
171 * all users have released their reference count on this structure.
172 */
sctp_endpoint_free(struct sctp_endpoint * ep)173 void sctp_endpoint_free(struct sctp_endpoint *ep)
174 {
175 ep->base.dead = true;
176
177 inet_sk_set_state(ep->base.sk, SCTP_SS_CLOSED);
178
179 /* Unlink this endpoint, so we can't find it again! */
180 sctp_unhash_endpoint(ep);
181
182 sctp_endpoint_put(ep);
183 }
184
185 /* Final destructor for endpoint. */
sctp_endpoint_destroy(struct sctp_endpoint * ep)186 static void sctp_endpoint_destroy(struct sctp_endpoint *ep)
187 {
188 struct sock *sk;
189
190 if (unlikely(!ep->base.dead)) {
191 WARN(1, "Attempt to destroy undead endpoint %p!\n", ep);
192 return;
193 }
194
195 /* Free the digest buffer */
196 kfree(ep->digest);
197
198 /* SCTP-AUTH: Free up AUTH releated data such as shared keys
199 * chunks and hmacs arrays that were allocated
200 */
201 sctp_auth_destroy_keys(&ep->endpoint_shared_keys);
202 sctp_auth_free(ep);
203
204 /* Cleanup. */
205 sctp_inq_free(&ep->base.inqueue);
206 sctp_bind_addr_free(&ep->base.bind_addr);
207
208 memset(ep->secret_key, 0, sizeof(ep->secret_key));
209
210 sk = ep->base.sk;
211 /* Remove and free the port */
212 if (sctp_sk(sk)->bind_hash)
213 sctp_put_port(sk);
214
215 sctp_sk(sk)->ep = NULL;
216 /* Give up our hold on the sock */
217 sock_put(sk);
218
219 kfree(ep);
220 SCTP_DBG_OBJCNT_DEC(ep);
221 }
222
223 /* Hold a reference to an endpoint. */
sctp_endpoint_hold(struct sctp_endpoint * ep)224 void sctp_endpoint_hold(struct sctp_endpoint *ep)
225 {
226 refcount_inc(&ep->base.refcnt);
227 }
228
229 /* Release a reference to an endpoint and clean up if there are
230 * no more references.
231 */
sctp_endpoint_put(struct sctp_endpoint * ep)232 void sctp_endpoint_put(struct sctp_endpoint *ep)
233 {
234 if (refcount_dec_and_test(&ep->base.refcnt))
235 sctp_endpoint_destroy(ep);
236 }
237
238 /* Is this the endpoint we are looking for? */
sctp_endpoint_is_match(struct sctp_endpoint * ep,struct net * net,const union sctp_addr * laddr)239 struct sctp_endpoint *sctp_endpoint_is_match(struct sctp_endpoint *ep,
240 struct net *net,
241 const union sctp_addr *laddr)
242 {
243 struct sctp_endpoint *retval = NULL;
244
245 if ((htons(ep->base.bind_addr.port) == laddr->v4.sin_port) &&
246 net_eq(sock_net(ep->base.sk), net)) {
247 if (sctp_bind_addr_match(&ep->base.bind_addr, laddr,
248 sctp_sk(ep->base.sk)))
249 retval = ep;
250 }
251
252 return retval;
253 }
254
255 /* Find the association that goes with this chunk.
256 * We lookup the transport from hashtable at first, then get association
257 * through t->assoc.
258 */
sctp_endpoint_lookup_assoc(const struct sctp_endpoint * ep,const union sctp_addr * paddr,struct sctp_transport ** transport)259 struct sctp_association *sctp_endpoint_lookup_assoc(
260 const struct sctp_endpoint *ep,
261 const union sctp_addr *paddr,
262 struct sctp_transport **transport)
263 {
264 struct sctp_association *asoc = NULL;
265 struct sctp_transport *t;
266
267 *transport = NULL;
268
269 /* If the local port is not set, there can't be any associations
270 * on this endpoint.
271 */
272 if (!ep->base.bind_addr.port)
273 return NULL;
274
275 rcu_read_lock();
276 t = sctp_epaddr_lookup_transport(ep, paddr);
277 if (!t)
278 goto out;
279
280 *transport = t;
281 asoc = t->asoc;
282 out:
283 rcu_read_unlock();
284 return asoc;
285 }
286
287 /* Look for any peeled off association from the endpoint that matches the
288 * given peer address.
289 */
sctp_endpoint_is_peeled_off(struct sctp_endpoint * ep,const union sctp_addr * paddr)290 bool sctp_endpoint_is_peeled_off(struct sctp_endpoint *ep,
291 const union sctp_addr *paddr)
292 {
293 struct sctp_sockaddr_entry *addr;
294 struct sctp_bind_addr *bp;
295 struct net *net = sock_net(ep->base.sk);
296
297 bp = &ep->base.bind_addr;
298 /* This function is called with the socket lock held,
299 * so the address_list can not change.
300 */
301 list_for_each_entry(addr, &bp->address_list, list) {
302 if (sctp_has_association(net, &addr->a, paddr))
303 return true;
304 }
305
306 return false;
307 }
308
309 /* Do delayed input processing. This is scheduled by sctp_rcv().
310 * This may be called on BH or task time.
311 */
sctp_endpoint_bh_rcv(struct work_struct * work)312 static void sctp_endpoint_bh_rcv(struct work_struct *work)
313 {
314 struct sctp_endpoint *ep =
315 container_of(work, struct sctp_endpoint,
316 base.inqueue.immediate);
317 struct sctp_association *asoc;
318 struct sock *sk;
319 struct net *net;
320 struct sctp_transport *transport;
321 struct sctp_chunk *chunk;
322 struct sctp_inq *inqueue;
323 union sctp_subtype subtype;
324 enum sctp_state state;
325 int error = 0;
326 int first_time = 1; /* is this the first time through the loop */
327
328 if (ep->base.dead)
329 return;
330
331 asoc = NULL;
332 inqueue = &ep->base.inqueue;
333 sk = ep->base.sk;
334 net = sock_net(sk);
335
336 while (NULL != (chunk = sctp_inq_pop(inqueue))) {
337 subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);
338
339 /* If the first chunk in the packet is AUTH, do special
340 * processing specified in Section 6.3 of SCTP-AUTH spec
341 */
342 if (first_time && (subtype.chunk == SCTP_CID_AUTH)) {
343 struct sctp_chunkhdr *next_hdr;
344
345 next_hdr = sctp_inq_peek(inqueue);
346 if (!next_hdr)
347 goto normal;
348
349 /* If the next chunk is COOKIE-ECHO, skip the AUTH
350 * chunk while saving a pointer to it so we can do
351 * Authentication later (during cookie-echo
352 * processing).
353 */
354 if (next_hdr->type == SCTP_CID_COOKIE_ECHO) {
355 chunk->auth_chunk = skb_clone(chunk->skb,
356 GFP_ATOMIC);
357 chunk->auth = 1;
358 continue;
359 }
360 }
361 normal:
362 /* We might have grown an association since last we
363 * looked, so try again.
364 *
365 * This happens when we've just processed our
366 * COOKIE-ECHO chunk.
367 */
368 if (NULL == chunk->asoc) {
369 asoc = sctp_endpoint_lookup_assoc(ep,
370 sctp_source(chunk),
371 &transport);
372 chunk->asoc = asoc;
373 chunk->transport = transport;
374 }
375
376 state = asoc ? asoc->state : SCTP_STATE_CLOSED;
377 if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
378 continue;
379
380 /* Remember where the last DATA chunk came from so we
381 * know where to send the SACK.
382 */
383 if (asoc && sctp_chunk_is_data(chunk))
384 asoc->peer.last_data_from = chunk->transport;
385 else {
386 SCTP_INC_STATS(sock_net(ep->base.sk), SCTP_MIB_INCTRLCHUNKS);
387 if (asoc)
388 asoc->stats.ictrlchunks++;
389 }
390
391 if (chunk->transport)
392 chunk->transport->last_time_heard = ktime_get();
393
394 error = sctp_do_sm(net, SCTP_EVENT_T_CHUNK, subtype, state,
395 ep, asoc, chunk, GFP_ATOMIC);
396
397 if (error && chunk)
398 chunk->pdiscard = 1;
399
400 /* Check to see if the endpoint is freed in response to
401 * the incoming chunk. If so, get out of the while loop.
402 */
403 if (!sctp_sk(sk)->ep)
404 break;
405
406 if (first_time)
407 first_time = 0;
408 }
409 }
410
