1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* RxRPC recvmsg() implementation
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/net.h>
11 #include <linux/skbuff.h>
12 #include <linux/export.h>
13 #include <linux/sched/signal.h>
14
15 #include <net/sock.h>
16 #include <net/af_rxrpc.h>
17 #include "ar-internal.h"
18
19 /*
20 * Post a call for attention by the socket or kernel service. Further
21 * notifications are suppressed by putting recvmsg_link on a dummy queue.
22 */
23 void rxrpc_notify_socket(struct rxrpc_call *call)
24 {
25 struct rxrpc_sock *rx;
26 struct sock *sk;
27
28 _enter("%d", call->debug_id);
29
30 if (!list_empty(&call->recvmsg_link))
31 return;
32
33 rcu_read_lock();
34
35 rx = rcu_dereference(call->socket);
36 sk = &rx->sk;
37 if (rx && sk->sk_state < RXRPC_CLOSE) {
38 if (call->notify_rx) {
39 spin_lock(&call->notify_lock);
40 call->notify_rx(sk, call, call->user_call_ID);
41 spin_unlock(&call->notify_lock);
42 } else {
43 spin_lock(&rx->recvmsg_lock);
44 if (list_empty(&call->recvmsg_link)) {
45 rxrpc_get_call(call, rxrpc_call_get_notify_socket);
46 list_add_tail(&call->recvmsg_link, &rx->recvmsg_q);
47 }
48 spin_unlock(&rx->recvmsg_lock);
49
50 if (!sock_flag(sk, SOCK_DEAD)) {
51 _debug("call %ps", sk->sk_data_ready);
52 sk->sk_data_ready(sk);
53 }
54 }
55 }
56
57 rcu_read_unlock();
58 _leave("");
59 }
60
61 /*
62 * Pass a call terminating message to userspace.
63 */
64 static int rxrpc_recvmsg_term(struct rxrpc_call *call, struct msghdr *msg)
65 {
66 u32 tmp = 0;
67 int ret;
68
69 switch (call->completion) {
70 case RXRPC_CALL_SUCCEEDED:
71 ret = 0;
72 if (rxrpc_is_service_call(call))
73 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &tmp);
74 break;
75 case RXRPC_CALL_REMOTELY_ABORTED:
76 tmp = call->abort_code;
77 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
78 break;
79 case RXRPC_CALL_LOCALLY_ABORTED:
80 tmp = call->abort_code;
81 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
82 break;
83 case RXRPC_CALL_NETWORK_ERROR:
84 tmp = -call->error;
85 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &tmp);
86 break;
87 case RXRPC_CALL_LOCAL_ERROR:
88 tmp = -call->error;
89 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4, &tmp);
90 break;
91 default:
92 pr_err("Invalid terminal call state %u\n", call->completion);
93 BUG();
94 break;
95 }
96
97 trace_rxrpc_recvdata(call, rxrpc_recvmsg_terminal,
98 call->ackr_window - 1,
99 call->rx_pkt_offset, call->rx_pkt_len, ret);
100 return ret;
101 }
102
103 /*
104 * Discard a packet we've used up and advance the Rx window by one.
105 */
106 static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
107 {
108 struct rxrpc_skb_priv *sp;
109 struct sk_buff *skb;
110 rxrpc_serial_t serial;
111 rxrpc_seq_t old_consumed = call->rx_consumed, tseq;
112 bool last;
113 int acked;
114
115 _enter("%d", call->debug_id);
116
117 skb = skb_dequeue(&call->recvmsg_queue);
118 rxrpc_see_skb(skb, rxrpc_skb_see_rotate);
119
120 sp = rxrpc_skb(skb);
121 tseq = sp->hdr.seq;
122 serial = sp->hdr.serial;
123 last = sp->hdr.flags & RXRPC_LAST_PACKET;
124
125 /* Barrier against rxrpc_input_data(). */
126 if (after(tseq, call->rx_consumed))
127 smp_store_release(&call->rx_consumed, tseq);
128
129 rxrpc_free_skb(skb, rxrpc_skb_put_rotate);
130
131 trace_rxrpc_receive(call, last ? rxrpc_receive_rotate_last : rxrpc_receive_rotate,
132 serial, call->rx_consumed);
133
134 if (last)
135 set_bit(RXRPC_CALL_RECVMSG_READ_ALL, &call->flags);
136
137 /* Check to see if there's an ACK that needs sending. */
138 acked = atomic_add_return(call->rx_consumed - old_consumed,
139 &call->ackr_nr_consumed);
140 if (acked > 8 &&
141 !test_and_set_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags))
142 rxrpc_poke_call(call, rxrpc_call_poke_idle);
143 }
144
145 /*
146 * Decrypt and verify a DATA packet.
147 */
148 static int rxrpc_verify_data(struct rxrpc_call *call, struct sk_buff *skb)
149 {
150 struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
151
152 if (sp->flags & RXRPC_RX_VERIFIED)
153 return 0;
154 return call->security->verify_packet(call, skb);
155 }
156
157 /*
158 * Deliver messages to a call. This keeps processing packets until the buffer
159 * is filled and we find either more DATA (returns 0) or the end of the DATA
160 * (returns 1). If more packets are required, it returns -EAGAIN and if the
161 * call has failed it returns -EIO.
162 */
163 static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
164 struct msghdr *msg, struct iov_iter *iter,
165 size_t len, int flags, size_t *_offset)
166 {
167 struct rxrpc_skb_priv *sp;
168 struct sk_buff *skb;
169 rxrpc_seq_t seq = 0;
170 size_t remain;
171 unsigned int rx_pkt_offset, rx_pkt_len;
172 int copy, ret = -EAGAIN, ret2;
173
174 rx_pkt_offset = call->rx_pkt_offset;
175 rx_pkt_len = call->rx_pkt_len;
176
177 if (rxrpc_call_has_failed(call)) {
178 seq = call->ackr_window - 1;
179 ret = -EIO;
180 goto done;
181 }
182
183 if (test_bit(RXRPC_CALL_RECVMSG_READ_ALL, &call->flags)) {
184 seq = call->ackr_window - 1;
185 ret = 1;
186 goto done;
187 }
188
189 /* No one else can be removing stuff from the queue, so we shouldn't
190 * need the Rx lock to walk it.
191 */
192 skb = skb_peek(&call->recvmsg_queue);
193 while (skb) {
194 rxrpc_see_skb(skb, rxrpc_skb_see_recvmsg);
195 sp = rxrpc_skb(skb);
196 seq = sp->hdr.seq;
197
198 if (!(flags & MSG_PEEK))
199 trace_rxrpc_receive(call, rxrpc_receive_front,
200 sp->hdr.serial, seq);
201
202 if (msg)
203 sock_recv_timestamp(msg, sock->sk, skb);
204
205 if (rx_pkt_offset == 0) {
206 ret2 = rxrpc_verify_data(call, skb);
207 trace_rxrpc_recvdata(call, rxrpc_recvmsg_next, seq,
208 sp->offset, sp->len, ret2);
209 if (ret2 < 0) {
210 kdebug("verify = %d", ret2);
211 ret = ret2;
212 goto out;
213 }
214 rx_pkt_offset = sp->offset;
215 rx_pkt_len = sp->len;
216 } else {
217 trace_rxrpc_recvdata(call, rxrpc_recvmsg_cont, seq,
218 rx_pkt_offset, rx_pkt_len, 0);
219 }
220
221 /* We have to handle short, empty and used-up DATA packets. */
222 remain = len - *_offset;
223 copy = rx_pkt_len;
224 if (copy > remain)
225 copy = remain;
226 if (copy > 0) {
227 ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
228 copy);
229 if (ret2 < 0) {
230 ret = ret2;
231 goto out;
232 }
233
234 /* handle piecemeal consumption of data packets */
235 rx_pkt_offset += copy;
236 rx_pkt_len -= copy;
237 *_offset += copy;
238 }
239
240 if (rx_pkt_len > 0) {
241 trace_rxrpc_recvdata(call, rxrpc_recvmsg_full, seq,
242 rx_pkt_offset, rx_pkt_len, 0);
243 ASSERTCMP(*_offset, ==, len);
244 ret = 0;
245 break;
246 }
247
248 /* The whole packet has been transferred. */
249 if (sp->hdr.flags & RXRPC_LAST_PACKET)
250 ret = 1;
251 rx_pkt_offset = 0;
252 rx_pkt_len = 0;
253
254 skb = skb_peek_next(skb, &call->recvmsg_queue);
255
256 if (!(flags & MSG_PEEK))
257 rxrpc_rotate_rx_window(call);
258 }
259
260 out:
261 if (!(flags & MSG_PEEK)) {
262 call->rx_pkt_offset = rx_pkt_offset;
263 call->rx_pkt_len = rx_pkt_len;
264 }
265 done:
266 trace_rxrpc_recvdata(call, rxrpc_recvmsg_data_return, seq,
267 rx_pkt_offset, rx_pkt_len, ret);
268 if (ret == -EAGAIN)
269 set_bit(RXRPC_CALL_RX_IS_IDLE, &call->flags);
270 return ret;
271 }
272
273 /*
274 * Receive a message from an RxRPC socket
275 * - we need to be careful about two or more threads calling recvmsg
276 * simultaneously
277 */
278 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
279 int flags)
280 {
281 struct rxrpc_call *call;
282 struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
283 struct list_head *l;
284 unsigned int call_debug_id = 0;
285 size_t copied = 0;
286 long timeo;
287 int ret;
288
289 DEFINE_WAIT(wait);
290
291 trace_rxrpc_recvmsg(0, rxrpc_recvmsg_enter, 0);
292
293 if (flags & (MSG_OOB | MSG_TRUNC))
294 return -EOPNOTSUPP;
295
296 timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
297
298 try_again:
299 lock_sock(&rx->sk);
300
301 /* Return immediately if a client socket has no outstanding calls */
302 if (RB_EMPTY_ROOT(&rx->calls) &&
303 list_empty(&rx->recvmsg_q) &&
304 rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
305 release_sock(&rx->sk);
306 return -EAGAIN;
307 }
308
309 if (list_empty(&rx->recvmsg_q)) {
310 ret = -EWOULDBLOCK;
311 if (timeo == 0) {
312 call = NULL;
313 goto error_no_call;
314 }
315
316 release_sock(&rx->sk);
317
318 /* Wait for something to happen */
319 prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
320 TASK_INTERRUPTIBLE);
321 ret = sock_error(&rx->sk);
322 if (ret)
323 goto wait_error;
324
325 if (list_empty(&rx->recvmsg_q)) {
326 if (signal_pending(current))
327 goto wait_interrupted;
328 trace_rxrpc_recvmsg(0, rxrpc_recvmsg_wait, 0);
329 timeo = schedule_timeout(timeo);
330 }
331 finish_wait(sk_sleep(&rx->sk), &wait);
332 goto try_again;
333 }
334
335 /* Find the next call and dequeue it if we're not just peeking. If we
336 * do dequeue it, that comes with a ref that we will need to release.
337 * We also want to weed out calls that got requeued whilst we were
338 * shovelling data out.
339 */
340 spin_lock(&rx->recvmsg_lock);
341 l = rx->recvmsg_q.next;
342 call = list_entry(l, struct rxrpc_call, recvmsg_link);
343
344 if (!rxrpc_call_is_complete(call) &&
345 skb_queue_empty(&call->recvmsg_queue)) {
346 list_del_init(&call->recvmsg_link);
347 spin_unlock(&rx->recvmsg_lock);
348 release_sock(&rx->sk);
349 trace_rxrpc_recvmsg(call->debug_id, rxrpc_recvmsg_unqueue, 0);
350 rxrpc_put_call(call, rxrpc_call_put_recvmsg);
351 goto try_again;
352 }
353
354 if (!(flags & MSG_PEEK))
355 list_del_init(&call->recvmsg_link);
356 else
357 rxrpc_get_call(call, rxrpc_call_get_recvmsg);
358 spin_unlock(&rx->recvmsg_lock);
359
360 call_debug_id = call->debug_id;
361 trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_dequeue, 0);
362
363 /* We're going to drop the socket lock, so we need to lock the call
364 * against interference by sendmsg.
365 */
366 if (!mutex_trylock(&call->user_mutex)) {
367 ret = -EWOULDBLOCK;
368 if (flags & MSG_DONTWAIT)
369 goto error_requeue_call;
370 ret = -ERESTARTSYS;
371 if (mutex_lock_interruptible(&call->user_mutex) < 0)
372 goto error_requeue_call;
373 }
374
375 release_sock(&rx->sk);
376
377 if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
378 BUG();
379
380 if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
381 if (flags & MSG_CMSG_COMPAT) {
382 unsigned int id32 = call->user_call_ID;
383
384 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
385 sizeof(unsigned int), &id32);
386 } else {
387 unsigned long idl = call->user_call_ID;
388
389 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
390 sizeof(unsigned long), &idl);
391 }
392 if (ret < 0)
393 goto error_unlock_call;
394 }
395
396 if (msg->msg_name && call->peer) {
397 size_t len = sizeof(call->dest_srx);
398
399 memcpy(msg->msg_name, &call->dest_srx, len);
400 msg->msg_namelen = len;
401 }
402
403 ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
404 flags, &copied);
405 if (ret == -EAGAIN)
406 ret = 0;
407 if (ret == -EIO)
408 goto call_failed;
409 if (ret < 0)
410 goto error_unlock_call;
411
412 if (rxrpc_call_is_complete(call) &&
413 skb_queue_empty(&call->recvmsg_queue))
414 goto call_complete;
415 if (rxrpc_call_has_failed(call))
416 goto call_failed;
417
418 if (!skb_queue_empty(&call->recvmsg_queue))
419 rxrpc_notify_socket(call);
420 goto not_yet_complete;
421
422 call_failed:
423 rxrpc_purge_queue(&call->recvmsg_queue);
424 call_complete:
425 ret = rxrpc_recvmsg_term(call, msg);
426 if (ret < 0)
427 goto error_unlock_call;
428 if (!(flags & MSG_PEEK))
429 rxrpc_release_call(rx, call);
430 msg->msg_flags |= MSG_EOR;
431 ret = 1;
432
433 not_yet_complete:
434 if (ret == 0)
435 msg->msg_flags |= MSG_MORE;
436 else
437 msg->msg_flags &= ~MSG_MORE;
438 ret = copied;
439
440 error_unlock_call:
441 mutex_unlock(&call->user_mutex);
442 rxrpc_put_call(call, rxrpc_call_put_recvmsg);
443 trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_return, ret);
444 return ret;
445
446 error_requeue_call:
447 if (!(flags & MSG_PEEK)) {
448 spin_lock(&rx->recvmsg_lock);
449 list_add(&call->recvmsg_link, &rx->recvmsg_q);
450 spin_unlock(&rx->recvmsg_lock);
451 trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_requeue, 0);
452 } else {
453 rxrpc_put_call(call, rxrpc_call_put_recvmsg);
454 }
455 error_no_call:
456 release_sock(&rx->sk);
457 error_trace:
458 trace_rxrpc_recvmsg(call_debug_id, rxrpc_recvmsg_return, ret);
459 return ret;
460
461 wait_interrupted:
462 ret = sock_intr_errno(timeo);
463 wait_error:
464 finish_wait(sk_sleep(&rx->sk), &wait);
465 call = NULL;
466 goto error_trace;
467 }
468
469 /**
470 * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
471 * @sock: The socket that the call exists on
472 * @call: The call to send data through
473 * @iter: The buffer to receive into
474 * @_len: The amount of data we want to receive (decreased on return)
475 * @want_more: True if more data is expected to be read
476 * @_abort: Where the abort code is stored if -ECONNABORTED is returned
477 * @_service: Where to store the actual service ID (may be upgraded)
478 *
479 * Allow a kernel service to receive data and pick up information about the
480 * state of a call. Returns 0 if got what was asked for and there's more
481 * available, 1 if we got what was asked for and we're at the end of the data
482 * and -EAGAIN if we need more data.
483 *
484 * Note that we may return -EAGAIN to drain empty packets at the end of the
485 * data, even if we've already copied over the requested data.
486 *
487 * *_abort should also be initialised to 0.
488 */
489 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
490 struct iov_iter *iter, size_t *_len,
491 bool want_more, u32 *_abort, u16 *_service)
492 {
493 size_t offset = 0;
494 int ret;
495
496 _enter("{%d},%zu,%d", call->debug_id, *_len, want_more);
497
498 mutex_lock(&call->user_mutex);
499
500 ret = rxrpc_recvmsg_data(sock, call, NULL, iter, *_len, 0, &offset);
501 *_len -= offset;
502 if (ret == -EIO)
503 goto call_failed;
504 if (ret < 0)
505 goto out;
506
507 /* We can only reach here with a partially full buffer if we have
508 * reached the end of the data. We must otherwise have a full buffer
509 * or have been given -EAGAIN.
510 */
511 if (ret == 1) {
512 if (iov_iter_count(iter) > 0)
513 goto short_data;
514 if (!want_more)
515 goto read_phase_complete;
516 ret = 0;
517 goto out;
518 }
519
520 if (!want_more)
521 goto excess_data;
522 goto out;
523
524 read_phase_complete:
525 ret = 1;
526 out:
527 if (_service)
528 *_service = call->dest_srx.srx_service;
529 mutex_unlock(&call->user_mutex);
530 _leave(" = %d [%zu,%d]", ret, iov_iter_count(iter), *_abort);
531 return ret;
532
533 short_data:
534 trace_rxrpc_abort(call->debug_id, rxrpc_recvmsg_short_data,
535 call->cid, call->call_id, call->rx_consumed,
536 0, -EBADMSG);
537 ret = -EBADMSG;
538 goto out;
539 excess_data:
540 trace_rxrpc_abort(call->debug_id, rxrpc_recvmsg_excess_data,
541 call->cid, call->call_id, call->rx_consumed,
542 0, -EMSGSIZE);
543 ret = -EMSGSIZE;
544 goto out;
545 call_failed:
546 *_abort = call->abort_code;
547 ret = call->error;
548 if (call->completion == RXRPC_CALL_SUCCEEDED) {
549 ret = 1;
550 if (iov_iter_count(iter) > 0)
551 ret = -ECONNRESET;
552 }
553 goto out;
554 }
555 EXPORT_SYMBOL(rxrpc_kernel_recv_data);
556
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