1 /* incoming call handling
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14 #include <linux/module.h>
15 #include <linux/net.h>
16 #include <linux/skbuff.h>
17 #include <linux/errqueue.h>
18 #include <linux/udp.h>
19 #include <linux/in.h>
20 #include <linux/in6.h>
21 #include <linux/icmp.h>
22 #include <linux/gfp.h>
23 #include <linux/circ_buf.h>
24 #include <net/sock.h>
25 #include <net/af_rxrpc.h>
26 #include <net/ip.h>
27 #include "ar-internal.h"
28
29 /*
30 * Preallocate a single service call, connection and peer and, if possible,
31 * give them a user ID and attach the user's side of the ID to them.
32 */
rxrpc_service_prealloc_one(struct rxrpc_sock * rx,struct rxrpc_backlog * b,rxrpc_notify_rx_t notify_rx,rxrpc_user_attach_call_t user_attach_call,unsigned long user_call_ID,gfp_t gfp)33 static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
34 struct rxrpc_backlog *b,
35 rxrpc_notify_rx_t notify_rx,
36 rxrpc_user_attach_call_t user_attach_call,
37 unsigned long user_call_ID, gfp_t gfp)
38 {
39 const void *here = __builtin_return_address(0);
40 struct rxrpc_call *call;
41 int max, tmp;
42 unsigned int size = RXRPC_BACKLOG_MAX;
43 unsigned int head, tail, call_head, call_tail;
44
45 max = rx->sk.sk_max_ack_backlog;
46 tmp = rx->sk.sk_ack_backlog;
47 if (tmp >= max) {
48 _leave(" = -ENOBUFS [full %u]", max);
49 return -ENOBUFS;
50 }
51 max -= tmp;
52
53 /* We don't need more conns and peers than we have calls, but on the
54 * other hand, we shouldn't ever use more peers than conns or conns
55 * than calls.
56 */
57 call_head = b->call_backlog_head;
58 call_tail = READ_ONCE(b->call_backlog_tail);
59 tmp = CIRC_CNT(call_head, call_tail, size);
60 if (tmp >= max) {
61 _leave(" = -ENOBUFS [enough %u]", tmp);
62 return -ENOBUFS;
63 }
64 max = tmp + 1;
65
66 head = b->peer_backlog_head;
67 tail = READ_ONCE(b->peer_backlog_tail);
68 if (CIRC_CNT(head, tail, size) < max) {
69 struct rxrpc_peer *peer = rxrpc_alloc_peer(rx->local, gfp);
70 if (!peer)
71 return -ENOMEM;
72 b->peer_backlog[head] = peer;
73 smp_store_release(&b->peer_backlog_head,
74 (head + 1) & (size - 1));
75 }
76
77 head = b->conn_backlog_head;
78 tail = READ_ONCE(b->conn_backlog_tail);
79 if (CIRC_CNT(head, tail, size) < max) {
80 struct rxrpc_connection *conn;
81
82 conn = rxrpc_prealloc_service_connection(gfp);
83 if (!conn)
84 return -ENOMEM;
85 b->conn_backlog[head] = conn;
86 smp_store_release(&b->conn_backlog_head,
87 (head + 1) & (size - 1));
88
89 trace_rxrpc_conn(conn, rxrpc_conn_new_service,
90 atomic_read(&conn->usage), here);
91 }
92
93 /* Now it gets complicated, because calls get registered with the
94 * socket here, particularly if a user ID is preassigned by the user.
95 */
96 call = rxrpc_alloc_call(gfp);
97 if (!call)
98 return -ENOMEM;
99 call->flags |= (1 << RXRPC_CALL_IS_SERVICE);
100 call->state = RXRPC_CALL_SERVER_PREALLOC;
101
102 trace_rxrpc_call(call, rxrpc_call_new_service,
103 atomic_read(&call->usage),
104 here, (const void *)user_call_ID);
105
106 write_lock(&rx->call_lock);
107 if (user_attach_call) {
108 struct rxrpc_call *xcall;
109 struct rb_node *parent, **pp;
110
111 /* Check the user ID isn't already in use */
112 pp = &rx->calls.rb_node;
113 parent = NULL;
114 while (*pp) {
115 parent = *pp;
116 xcall = rb_entry(parent, struct rxrpc_call, sock_node);
117 if (user_call_ID < call->user_call_ID)
118 pp = &(*pp)->rb_left;
119 else if (user_call_ID > call->user_call_ID)
120 pp = &(*pp)->rb_right;
121 else
122 goto id_in_use;
123 }
124
125 call->user_call_ID = user_call_ID;
126 call->notify_rx = notify_rx;
127 rxrpc_get_call(call, rxrpc_call_got_kernel);
128 user_attach_call(call, user_call_ID);
129 rxrpc_get_call(call, rxrpc_call_got_userid);
130 rb_link_node(&call->sock_node, parent, pp);
131 rb_insert_color(&call->sock_node, &rx->calls);
132 set_bit(RXRPC_CALL_HAS_USERID, &call->flags);
133 }
134
135 list_add(&call->sock_link, &rx->sock_calls);
136
137 write_unlock(&rx->call_lock);
138
139 write_lock(&rxrpc_call_lock);
140 list_add_tail(&call->link, &rxrpc_calls);
141 write_unlock(&rxrpc_call_lock);
142
143 b->call_backlog[call_head] = call;
144 smp_store_release(&b->call_backlog_head, (call_head + 1) & (size - 1));
145 _leave(" = 0 [%d -> %lx]", call->debug_id, user_call_ID);
146 return 0;
147
148 id_in_use:
149 write_unlock(&rx->call_lock);
150 rxrpc_cleanup_call(call);
151 _leave(" = -EBADSLT");
152 return -EBADSLT;
153 }
154
155 /*
156 * Preallocate sufficient service connections, calls and peers to cover the
157 * entire backlog of a socket. When a new call comes in, if we don't have
158 * sufficient of each available, the call gets rejected as busy or ignored.
159 *
160 * The backlog is replenished when a connection is accepted or rejected.
161 */
rxrpc_service_prealloc(struct rxrpc_sock * rx,gfp_t gfp)162 int rxrpc_service_prealloc(struct rxrpc_sock *rx, gfp_t gfp)
163 {
164 struct rxrpc_backlog *b = rx->backlog;
165
166 if (!b) {
167 b = kzalloc(sizeof(struct rxrpc_backlog), gfp);
168 if (!b)
169 return -ENOMEM;
170 rx->backlog = b;
171 }
172
173 if (rx->discard_new_call)
174 return 0;
175
176 while (rxrpc_service_prealloc_one(rx, b, NULL, NULL, 0, gfp) == 0)
177 ;
178
179 return 0;
180 }
181
182 /*
183 * Discard the preallocation on a service.
184 */
rxrpc_discard_prealloc(struct rxrpc_sock * rx)185 void rxrpc_discard_prealloc(struct rxrpc_sock *rx)
186 {
187 struct rxrpc_backlog *b = rx->backlog;
188 unsigned int size = RXRPC_BACKLOG_MAX, head, tail;
189
190 if (!b)
191 return;
192 rx->backlog = NULL;
193
194 /* Make sure that there aren't any incoming calls in progress before we
195 * clear the preallocation buffers.
196 */
197 spin_lock_bh(&rx->incoming_lock);
198 spin_unlock_bh(&rx->incoming_lock);
199
200 head = b->peer_backlog_head;
201 tail = b->peer_backlog_tail;
202 while (CIRC_CNT(head, tail, size) > 0) {
203 struct rxrpc_peer *peer = b->peer_backlog[tail];
204 kfree(peer);
205 tail = (tail + 1) & (size - 1);
206 }
207
208 head = b->conn_backlog_head;
209 tail = b->conn_backlog_tail;
210 while (CIRC_CNT(head, tail, size) > 0) {
211 struct rxrpc_connection *conn = b->conn_backlog[tail];
212 write_lock(&rxrpc_connection_lock);
213 list_del(&conn->link);
214 list_del(&conn->proc_link);
215 write_unlock(&rxrpc_connection_lock);
216 kfree(conn);
217 tail = (tail + 1) & (size - 1);
218 }
219
220 head = b->call_backlog_head;
221 tail = b->call_backlog_tail;
222 while (CIRC_CNT(head, tail, size) > 0) {
223 struct rxrpc_call *call = b->call_backlog[tail];
224 if (rx->discard_new_call) {
225 _debug("discard %lx", call->user_call_ID);
226 rx->discard_new_call(call, call->user_call_ID);
227 rxrpc_put_call(call, rxrpc_call_put_kernel);
228 }
229 rxrpc_call_completed(call);
230 rxrpc_release_call(rx, call);
231 rxrpc_put_call(call, rxrpc_call_put);
232 tail = (tail + 1) & (size - 1);
233 }
234
235 kfree(b);
236 }
237
238 /*
239 * Allocate a new incoming call from the prealloc pool, along with a connection
240 * and a peer as necessary.
241 */
rxrpc_alloc_incoming_call(struct rxrpc_sock * rx,struct rxrpc_local * local,struct rxrpc_connection * conn,struct sk_buff * skb)242 static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx,
243 struct rxrpc_local *local,
244 struct rxrpc_connection *conn,
245 struct sk_buff *skb)
246 {
247 struct rxrpc_backlog *b = rx->backlog;
248 struct rxrpc_peer *peer, *xpeer;
249 struct rxrpc_call *call;
250 unsigned short call_head, conn_head, peer_head;
251 unsigned short call_tail, conn_tail, peer_tail;
252 unsigned short call_count, conn_count;
253
254 /* #calls >= #conns >= #peers must hold true. */
255 call_head = smp_load_acquire(&b->call_backlog_head);
256 call_tail = b->call_backlog_tail;
257 call_count = CIRC_CNT(call_head, call_tail, RXRPC_BACKLOG_MAX);
258 conn_head = smp_load_acquire(&b->conn_backlog_head);
259 conn_tail = b->conn_backlog_tail;
260 conn_count = CIRC_CNT(conn_head, conn_tail, RXRPC_BACKLOG_MAX);
261 ASSERTCMP(conn_count, >=, call_count);
262 peer_head = smp_load_acquire(&b->peer_backlog_head);
263 peer_tail = b->peer_backlog_tail;
264 ASSERTCMP(CIRC_CNT(peer_head, peer_tail, RXRPC_BACKLOG_MAX), >=,
265 conn_count);
266
267 if (call_count == 0)
268 return NULL;
269
270 if (!conn) {
271 /* No connection. We're going to need a peer to start off
272 * with. If one doesn't yet exist, use a spare from the
273 * preallocation set. We dump the address into the spare in
274 * anticipation - and to save on stack space.
275 */
276 xpeer = b->peer_backlog[peer_tail];
277 if (rxrpc_extract_addr_from_skb(&xpeer->srx, skb) < 0)
278 return NULL;
279
280 peer = rxrpc_lookup_incoming_peer(local, xpeer);
281 if (peer == xpeer) {
282 b->peer_backlog[peer_tail] = NULL;
283 smp_store_release(&b->peer_backlog_tail,
284 (peer_tail + 1) &
285 (RXRPC_BACKLOG_MAX - 1));
286 }
287
288 /* Now allocate and set up the connection */
289 conn = b->conn_backlog[conn_tail];
290 b->conn_backlog[conn_tail] = NULL;
291 smp_store_release(&b->conn_backlog_tail,
292 (conn_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
293 rxrpc_get_local(local);
294 conn->params.local = local;
295 conn->params.peer = peer;
296 rxrpc_see_connection(conn);
297 rxrpc_new_incoming_connection(conn, skb);
298 } else {
299 rxrpc_get_connection(conn);
300 }
301
302 /* And now we can allocate and set up a new call */
303 call = b->call_backlog[call_tail];
304 b->call_backlog[call_tail] = NULL;
305 smp_store_release(&b->call_backlog_tail,
306 (call_tail + 1) & (RXRPC_BACKLOG_MAX - 1));
307
308 rxrpc_see_call(call);
309 call->conn = conn;
310 call->peer = rxrpc_get_peer(conn->params.peer);
311 return call;
312 }
313
314 /*
315 * Set up a new incoming call. Called in BH context with the RCU read lock
316 * held.
317 *
318 * If this is for a kernel service, when we allocate the call, it will have
319 * three refs on it: (1) the kernel service, (2) the user_call_ID tree, (3) the
320 * retainer ref obtained from the backlog buffer. Prealloc calls for userspace
321 * services only have the ref from the backlog buffer. We want to pass this
322 * ref to non-BH context to dispose of.
323 *
324 * If we want to report an error, we mark the skb with the packet type and
325 * abort code and return NULL.
326 */
rxrpc_new_incoming_call(struct rxrpc_local * local,struct rxrpc_connection * conn,struct sk_buff * skb)327 struct rxrpc_call *rxrpc_new_incoming_call(struct rxrpc_local *local,
328 struct rxrpc_connection *conn,
329 struct sk_buff *skb)
330 {
331 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
332 struct rxrpc_sock *rx;
333 struct rxrpc_call *call;
334 u16 service_id = sp->hdr.serviceId;
335
336 _enter("");
337
338 /* Get the socket providing the service */
339 rx = rcu_dereference(local->service);
340 if (rx && service_id == rx->srx.srx_service)
341 goto found_service;
342
343 trace_rxrpc_abort("INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
344 RX_INVALID_OPERATION, EOPNOTSUPP);
345 skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
346 skb->priority = RX_INVALID_OPERATION;
347 _leave(" = NULL [service]");
348 return NULL;
349
350 found_service:
351 spin_lock(&rx->incoming_lock);
352 if (rx->sk.sk_state == RXRPC_CLOSE) {
353 trace_rxrpc_abort("CLS", sp->hdr.cid, sp->hdr.callNumber,
354 sp->hdr.seq, RX_INVALID_OPERATION, ESHUTDOWN);
355 skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
356 skb->priority = RX_INVALID_OPERATION;
357 _leave(" = NULL [close]");
358 call = NULL;
359 goto out;
360 }
361
362 call = rxrpc_alloc_incoming_call(rx, local, conn, skb);
363 if (!call) {
364 skb->mark = RXRPC_SKB_MARK_BUSY;
365 _leave(" = NULL [busy]");
366 call = NULL;
367 goto out;
368 }
369
370 trace_rxrpc_receive(call, rxrpc_receive_incoming,
371 sp->hdr.serial, sp->hdr.seq);
372
373 /* Make the call live. */
374 rxrpc_incoming_call(rx, call, skb);
375 conn = call->conn;
376
377 if (rx->notify_new_call)
378 rx->notify_new_call(&rx->sk, call, call->user_call_ID);
379 else
380 sk_acceptq_added(&rx->sk);
381
382 spin_lock(&conn->state_lock);
383 switch (conn->state) {
384 case RXRPC_CONN_SERVICE_UNSECURED:
385 conn->state = RXRPC_CONN_SERVICE_CHALLENGING;
386 set_bit(RXRPC_CONN_EV_CHALLENGE, &call->conn->events);
387 rxrpc_queue_conn(call->conn);
388 break;
389
390 case RXRPC_CONN_SERVICE:
391 write_lock(&call->state_lock);
392 if (rx->discard_new_call)
393 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
394 else
395 call->state = RXRPC_CALL_SERVER_ACCEPTING;
396 write_unlock(&call->state_lock);
397 break;
398
399 case RXRPC_CONN_REMOTELY_ABORTED:
400 rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
401 conn->remote_abort, ECONNABORTED);
402 break;
403 case RXRPC_CONN_LOCALLY_ABORTED:
404 rxrpc_abort_call("CON", call, sp->hdr.seq,
405 conn->local_abort, ECONNABORTED);
406 break;
407 default:
408 BUG();
409 }
410 spin_unlock(&conn->state_lock);
411
412 if (call->state == RXRPC_CALL_SERVER_ACCEPTING)
413 rxrpc_notify_socket(call);
414
415 /* We have to discard the prealloc queue's ref here and rely on a
416 * combination of the RCU read lock and refs held either by the socket
417 * (recvmsg queue, to-be-accepted queue or user ID tree) or the kernel
418 * service to prevent the call from being deallocated too early.
419 */
420 rxrpc_put_call(call, rxrpc_call_put);
421
422 _leave(" = %p{%d}", call, call->debug_id);
423 out:
424 spin_unlock(&rx->incoming_lock);
425 return call;
426 }
427
428 /*
429 * handle acceptance of a call by userspace
430 * - assign the user call ID to the call at the front of the queue
431 */
rxrpc_accept_call(struct rxrpc_sock * rx,unsigned long user_call_ID,rxrpc_notify_rx_t notify_rx)432 struct rxrpc_call *rxrpc_accept_call(struct rxrpc_sock *rx,
433 unsigned long user_call_ID,
434 rxrpc_notify_rx_t notify_rx)
435 {
436 struct rxrpc_call *call;
437 struct rb_node *parent, **pp;
438 int ret;
439
440 _enter(",%lx", user_call_ID);
441
442 ASSERT(!irqs_disabled());
443
444 write_lock(&rx->call_lock);
445
446 if (list_empty(&rx->to_be_accepted)) {
447 write_unlock(&rx->call_lock);
448 kleave(" = -ENODATA [empty]");
449 return ERR_PTR(-ENODATA);
450 }
451
452 /* check the user ID isn't already in use */
453 pp = &rx->calls.rb_node;
454 parent = NULL;
455 while (*pp) {
456 parent = *pp;
457 call = rb_entry(parent, struct rxrpc_call, sock_node);
458
459 if (user_call_ID < call->user_call_ID)
460 pp = &(*pp)->rb_left;
461 else if (user_call_ID > call->user_call_ID)
462 pp = &(*pp)->rb_right;
463 else
464 goto id_in_use;
465 }
466
467 /* Dequeue the first call and check it's still valid. We gain
468 * responsibility for the queue's reference.
469 */
470 call = list_entry(rx->to_be_accepted.next,
471 struct rxrpc_call, accept_link);
472 list_del_init(&call->accept_link);
473 sk_acceptq_removed(&rx->sk);
474 rxrpc_see_call(call);
475
476 write_lock_bh(&call->state_lock);
477 switch (call->state) {
478 case RXRPC_CALL_SERVER_ACCEPTING:
479 call->state = RXRPC_CALL_SERVER_RECV_REQUEST;
480 break;
481 case RXRPC_CALL_COMPLETE:
482 ret = call->error;
483 goto out_release;
484 default:
485 BUG();
486 }
487
488 /* formalise the acceptance */
489 call->notify_rx = notify_rx;
490 call->user_call_ID = user_call_ID;
491 rxrpc_get_call(call, rxrpc_call_got_userid);
492 rb_link_node(&call->sock_node, parent, pp);
493 rb_insert_color(&call->sock_node, &rx->calls);
494 if (test_and_set_bit(RXRPC_CALL_HAS_USERID, &call->flags))
495 BUG();
496
497 write_unlock_bh(&call->state_lock);
498 write_unlock(&rx->call_lock);
499 rxrpc_notify_socket(call);
500 rxrpc_service_prealloc(rx, GFP_KERNEL);
501 _leave(" = %p{%d}", call, call->debug_id);
502 return call;
503
504 out_release:
505 _debug("release %p", call);
506 write_unlock_bh(&call->state_lock);
507 write_unlock(&rx->call_lock);
508 rxrpc_release_call(rx, call);
509 rxrpc_put_call(call, rxrpc_call_put);
510 goto out;
511
512 id_in_use:
513 ret = -EBADSLT;
514 write_unlock(&rx->call_lock);
515 out:
516 rxrpc_service_prealloc(rx, GFP_KERNEL);
517 _leave(" = %d", ret);
518 return ERR_PTR(ret);
519 }
520
521 /*
522 * Handle rejection of a call by userspace
523 * - reject the call at the front of the queue
524 */
rxrpc_reject_call(struct rxrpc_sock * rx)525 int rxrpc_reject_call(struct rxrpc_sock *rx)
526 {
527 struct rxrpc_call *call;
528 bool abort = false;
529 int ret;
530
531 _enter("");
532
533 ASSERT(!irqs_disabled());
534
535 write_lock(&rx->call_lock);
536
537 if (list_empty(&rx->to_be_accepted)) {
538 write_unlock(&rx->call_lock);
539 return -ENODATA;
540 }
541
542 /* Dequeue the first call and check it's still valid. We gain
543 * responsibility for the queue's reference.
544 */
545 call = list_entry(rx->to_be_accepted.next,
546 struct rxrpc_call, accept_link);
547 list_del_init(&call->accept_link);
548 sk_acceptq_removed(&rx->sk);
549 rxrpc_see_call(call);
550
551 write_lock_bh(&call->state_lock);
552 switch (call->state) {
553 case RXRPC_CALL_SERVER_ACCEPTING:
554 __rxrpc_abort_call("REJ", call, 1, RX_USER_ABORT, ECONNABORTED);
555 abort = true;
556 /* fall through */
557 case RXRPC_CALL_COMPLETE:
558 ret = call->error;
559 goto out_discard;
560 default:
561 BUG();
562 }
563
564 out_discard:
565 write_unlock_bh(&call->state_lock);
566 write_unlock(&rx->call_lock);
567 if (abort) {
568 rxrpc_send_abort_packet(call);
569 rxrpc_release_call(rx, call);
570 rxrpc_put_call(call, rxrpc_call_put);
571 }
572 rxrpc_service_prealloc(rx, GFP_KERNEL);
573 _leave(" = %d", ret);
574 return ret;
575 }
576
577 /*
578 * rxrpc_kernel_charge_accept - Charge up socket with preallocated calls
579 * @sock: The socket on which to preallocate
580 * @notify_rx: Event notification function for the call
581 * @user_attach_call: Func to attach call to user_call_ID
582 * @user_call_ID: The tag to attach to the preallocated call
583 * @gfp: The allocation conditions.
584 *
585 * Charge up the socket with preallocated calls, each with a user ID. A
586 * function should be provided to effect the attachment from the user's side.
587 * The user is given a ref to hold on the call.
588 *
589 * Note that the call may be come connected before this function returns.
590 */
rxrpc_kernel_charge_accept(struct socket * sock,rxrpc_notify_rx_t notify_rx,rxrpc_user_attach_call_t user_attach_call,unsigned long user_call_ID,gfp_t gfp)591 int rxrpc_kernel_charge_accept(struct socket *sock,
592 rxrpc_notify_rx_t notify_rx,
593 rxrpc_user_attach_call_t user_attach_call,
594 unsigned long user_call_ID, gfp_t gfp)
595 {
596 struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
597 struct rxrpc_backlog *b = rx->backlog;
598
599 if (sock->sk->sk_state == RXRPC_CLOSE)
600 return -ESHUTDOWN;
601
602 return rxrpc_service_prealloc_one(rx, b, notify_rx,
603 user_attach_call, user_call_ID,
604 gfp);
605 }
606 EXPORT_SYMBOL(rxrpc_kernel_charge_accept);
607