summaryrefslogtreecommitdiff
path: root/net/rxrpc/recvmsg.c
blob: 490b1927215c78aa5ec2775984a5d7ef2ccc0b8e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
// SPDX-License-Identifier: GPL-2.0-or-later
/* RxRPC recvmsg() implementation
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/export.h>
#include <linux/sched/signal.h>

#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"

/*
 * Post a call for attention by the socket or kernel service.  Further
 * notifications are suppressed by putting recvmsg_link on a dummy queue.
 */
void rxrpc_notify_socket(struct rxrpc_call *call)
{
	struct rxrpc_sock *rx;
	struct sock *sk;

	_enter("%d", call->debug_id);

	if (!list_empty(&call->recvmsg_link))
		return;

	rcu_read_lock();

	rx = rcu_dereference(call->socket);
	sk = &rx->sk;
	if (rx && sk->sk_state < RXRPC_CLOSE) {
		if (call->notify_rx) {
			spin_lock_bh(&call->notify_lock);
			call->notify_rx(sk, call, call->user_call_ID);
			spin_unlock_bh(&call->notify_lock);
		} else {
			write_lock_bh(&rx->recvmsg_lock);
			if (list_empty(&call->recvmsg_link)) {
				rxrpc_get_call(call, rxrpc_call_got);
				list_add_tail(&call->recvmsg_link, &rx->recvmsg_q);
			}
			write_unlock_bh(&rx->recvmsg_lock);

			if (!sock_flag(sk, SOCK_DEAD)) {
				_debug("call %ps", sk->sk_data_ready);
				sk->sk_data_ready(sk);
			}
		}
	}

	rcu_read_unlock();
	_leave("");
}

/*
 * Transition a call to the complete state.
 */
bool __rxrpc_set_call_completion(struct rxrpc_call *call,
				 enum rxrpc_call_completion compl,
				 u32 abort_code,
				 int error)
{
	if (call->state < RXRPC_CALL_COMPLETE) {
		call->abort_code = abort_code;
		call->error = error;
		call->completion = compl,
		call->state = RXRPC_CALL_COMPLETE;
		trace_rxrpc_call_complete(call);
		wake_up(&call->waitq);
		rxrpc_notify_socket(call);
		return true;
	}
	return false;
}

bool rxrpc_set_call_completion(struct rxrpc_call *call,
			       enum rxrpc_call_completion compl,
			       u32 abort_code,
			       int error)
{
	bool ret = false;

	if (call->state < RXRPC_CALL_COMPLETE) {
		write_lock_bh(&call->state_lock);
		ret = __rxrpc_set_call_completion(call, compl, abort_code, error);
		write_unlock_bh(&call->state_lock);
	}
	return ret;
}

/*
 * Record that a call successfully completed.
 */
bool __rxrpc_call_completed(struct rxrpc_call *call)
{
	return __rxrpc_set_call_completion(call, RXRPC_CALL_SUCCEEDED, 0, 0);
}

bool rxrpc_call_completed(struct rxrpc_call *call)
{
	bool ret = false;

	if (call->state < RXRPC_CALL_COMPLETE) {
		write_lock_bh(&call->state_lock);
		ret = __rxrpc_call_completed(call);
		write_unlock_bh(&call->state_lock);
	}
	return ret;
}

/*
 * Record that a call is locally aborted.
 */
bool __rxrpc_abort_call(const char *why, struct rxrpc_call *call,
			rxrpc_seq_t seq, u32 abort_code, int error)
{
	trace_rxrpc_abort(call->debug_id, why, call->cid, call->call_id, seq,
			  abort_code, error);
	return __rxrpc_set_call_completion(call, RXRPC_CALL_LOCALLY_ABORTED,
					   abort_code, error);
}

bool rxrpc_abort_call(const char *why, struct rxrpc_call *call,
		      rxrpc_seq_t seq, u32 abort_code, int error)
{
	bool ret;

	write_lock_bh(&call->state_lock);
	ret = __rxrpc_abort_call(why, call, seq, abort_code, error);
	write_unlock_bh(&call->state_lock);
	return ret;
}

/*
 * Pass a call terminating message to userspace.
 */
static int rxrpc_recvmsg_term(struct rxrpc_call *call, struct msghdr *msg)
{
	u32 tmp = 0;
	int ret;

	switch (call->completion) {
	case RXRPC_CALL_SUCCEEDED:
		ret = 0;
		if (rxrpc_is_service_call(call))
			ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &tmp);
		break;
	case RXRPC_CALL_REMOTELY_ABORTED:
		tmp = call->abort_code;
		ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
		break;
	case RXRPC_CALL_LOCALLY_ABORTED:
		tmp = call->abort_code;
		ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
		break;
	case RXRPC_CALL_NETWORK_ERROR:
		tmp = -call->error;
		ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &tmp);
		break;
	case RXRPC_CALL_LOCAL_ERROR:
		tmp = -call->error;
		ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4, &tmp);
		break;
	default:
		pr_err("Invalid terminal call state %u\n", call->state);
		BUG();
		break;
	}

	trace_rxrpc_recvmsg(call, rxrpc_recvmsg_terminal, call->rx_hard_ack,
			    call->rx_pkt_offset, call->rx_pkt_len, ret);
	return ret;
}

/*
 * Pass back notification of a new call.  The call is added to the
 * to-be-accepted list.  This means that the next call to be accepted might not
 * be the last call seen awaiting acceptance, but unless we leave this on the
 * front of the queue and block all other messages until someone gives us a
 * user_ID for it, there's not a lot we can do.
 */
static int rxrpc_recvmsg_new_call(struct rxrpc_sock *rx,
				  struct rxrpc_call *call,
				  struct msghdr *msg, int flags)
{
	int tmp = 0, ret;

	ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NEW_CALL, 0, &tmp);

	if (ret == 0 && !(flags & MSG_PEEK)) {
		_debug("to be accepted");
		write_lock_bh(&rx->recvmsg_lock);
		list_del_init(&call->recvmsg_link);
		write_unlock_bh(&rx->recvmsg_lock);

		rxrpc_get_call(call, rxrpc_call_got);
		write_lock(&rx->call_lock);
		list_add_tail(&call->accept_link, &rx->to_be_accepted);
		write_unlock(&rx->call_lock);
	}

	trace_rxrpc_recvmsg(call, rxrpc_recvmsg_to_be_accepted, 1, 0, 0, ret);
	return ret;
}

/*
 * End the packet reception phase.
 */
static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
{
	_enter("%d,%s", call->debug_id, rxrpc_call_states[call->state]);

	trace_rxrpc_receive(call, rxrpc_receive_end, 0, call->rx_top);
	ASSERTCMP(call->rx_hard_ack, ==, call->rx_top);

	if (call->state == RXRPC_CALL_CLIENT_RECV_REPLY) {
		rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, serial, false, true,
				  rxrpc_propose_ack_terminal_ack);
		//rxrpc_send_ack_packet(call, false, NULL);
	}

	write_lock_bh(&call->state_lock);

	switch (call->state) {
	case RXRPC_CALL_CLIENT_RECV_REPLY:
		__rxrpc_call_completed(call);
		write_unlock_bh(&call->state_lock);
		break;

	case RXRPC_CALL_SERVER_RECV_REQUEST:
		call->tx_phase = true;
		call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
		call->expect_req_by = jiffies + MAX_JIFFY_OFFSET;
		write_unlock_bh(&call->state_lock);
		rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial, false, true,
				  rxrpc_propose_ack_processing_op);
		break;
	default:
		write_unlock_bh(&call->state_lock);
		break;
	}
}

/*
 * Discard a packet we've used up and advance the Rx window by one.
 */
static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
{
	struct rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	rxrpc_serial_t serial;
	rxrpc_seq_t hard_ack, top;
	bool last = false;
	u8 subpacket;
	int ix;

	_enter("%d", call->debug_id);

	hard_ack = call->rx_hard_ack;
	top = smp_load_acquire(&call->rx_top);
	ASSERT(before(hard_ack, top));

	hard_ack++;
	ix = hard_ack & RXRPC_RXTX_BUFF_MASK;
	skb = call->rxtx_buffer[ix];
	rxrpc_see_skb(skb, rxrpc_skb_rotated);
	sp = rxrpc_skb(skb);

	subpacket = call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
	serial = sp->hdr.serial + subpacket;

	if (subpacket == sp->nr_subpackets - 1 &&
	    sp->rx_flags & RXRPC_SKB_INCL_LAST)
		last = true;

	call->rxtx_buffer[ix] = NULL;
	call->rxtx_annotations[ix] = 0;
	/* Barrier against rxrpc_input_data(). */
	smp_store_release(&call->rx_hard_ack, hard_ack);

	rxrpc_free_skb(skb, rxrpc_skb_freed);

	trace_rxrpc_receive(call, rxrpc_receive_rotate, serial, hard_ack);
	if (last) {
		rxrpc_end_rx_phase(call, serial);
	} else {
		/* Check to see if there's an ACK that needs sending. */
		if (after_eq(hard_ack, call->ackr_consumed + 2) ||
		    after_eq(top, call->ackr_seen + 2) ||
		    (hard_ack == top && after(hard_ack, call->ackr_consumed)))
			rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial,
					  true, true,
					  rxrpc_propose_ack_rotate_rx);
		if (call->ackr_reason && call->ackr_reason != RXRPC_ACK_DELAY)
			rxrpc_send_ack_packet(call, false, NULL);
	}
}

/*
 * Decrypt and verify a (sub)packet.  The packet's length may be changed due to
 * padding, but if this is the case, the packet length will be resident in the
 * socket buffer.  Note that we can't modify the master skb info as the skb may
 * be the home to multiple subpackets.
 */
static int rxrpc_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
			       u8 annotation,
			       unsigned int offset, unsigned int len)
{
	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
	rxrpc_seq_t seq = sp->hdr.seq;
	u16 cksum = sp->hdr.cksum;
	u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;

	_enter("");

	/* For all but the head jumbo subpacket, the security checksum is in a
	 * jumbo header immediately prior to the data.
	 */
	if (subpacket > 0) {
		__be16 tmp;
		if (skb_copy_bits(skb, offset - 2, &tmp, 2) < 0)
			BUG();
		cksum = ntohs(tmp);
		seq += subpacket;
	}

	return call->security->verify_packet(call, skb, offset, len,
					     seq, cksum);
}

/*
 * Locate the data within a packet.  This is complicated by:
 *
 * (1) An skb may contain a jumbo packet - so we have to find the appropriate
 *     subpacket.
 *
 * (2) The (sub)packets may be encrypted and, if so, the encrypted portion
 *     contains an extra header which includes the true length of the data,
 *     excluding any encrypted padding.
 */
static int rxrpc_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
			     u8 *_annotation,
			     unsigned int *_offset, unsigned int *_len,
			     bool *_last)
{
	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
	unsigned int offset = sizeof(struct rxrpc_wire_header);
	unsigned int len;
	bool last = false;
	int ret;
	u8 annotation = *_annotation;
	u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;

	/* Locate the subpacket */
	offset += subpacket * RXRPC_JUMBO_SUBPKTLEN;
	len = skb->len - offset;
	if (subpacket < sp->nr_subpackets - 1)
		len = RXRPC_JUMBO_DATALEN;
	else if (sp->rx_flags & RXRPC_SKB_INCL_LAST)
		last = true;

	if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
		ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
		if (ret < 0)
			return ret;
		*_annotation |= RXRPC_RX_ANNO_VERIFIED;
	}

	*_offset = offset;
	*_len = len;
	*_last = last;
	call->security->locate_data(call, skb, _offset, _len);
	return 0;
}

/*
 * Deliver messages to a call.  This keeps processing packets until the buffer
 * is filled and we find either more DATA (returns 0) or the end of the DATA
 * (returns 1).  If more packets are required, it returns -EAGAIN.
 */
static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
			      struct msghdr *msg, struct iov_iter *iter,
			      size_t len, int flags, size_t *_offset)
{
	struct rxrpc_skb_priv *sp;
	struct sk_buff *skb;
	rxrpc_serial_t serial;
	rxrpc_seq_t hard_ack, top, seq;
	size_t remain;
	bool rx_pkt_last;
	unsigned int rx_pkt_offset, rx_pkt_len;
	int ix, copy, ret = -EAGAIN, ret2;

	if (test_and_clear_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags) &&
	    call->ackr_reason)
		rxrpc_send_ack_packet(call, false, NULL);

	rx_pkt_offset = call->rx_pkt_offset;
	rx_pkt_len = call->rx_pkt_len;
	rx_pkt_last = call->rx_pkt_last;

	if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
		seq = call->rx_hard_ack;
		ret = 1;
		goto done;
	}

	/* Barriers against rxrpc_input_data(). */
	hard_ack = call->rx_hard_ack;
	seq = hard_ack + 1;

	while (top = smp_load_acquire(&call->rx_top),
	       before_eq(seq, top)
	       ) {
		ix = seq & RXRPC_RXTX_BUFF_MASK;
		skb = call->rxtx_buffer[ix];
		if (!skb) {
			trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq,
					    rx_pkt_offset, rx_pkt_len, 0);
			break;
		}
		smp_rmb();
		rxrpc_see_skb(skb, rxrpc_skb_seen);
		sp = rxrpc_skb(skb);

		if (!(flags & MSG_PEEK)) {
			serial = sp->hdr.serial;
			serial += call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
			trace_rxrpc_receive(call, rxrpc_receive_front,
					    serial, seq);
		}

		if (msg)
			sock_recv_timestamp(msg, sock->sk, skb);

		if (rx_pkt_offset == 0) {
			ret2 = rxrpc_locate_data(call, skb,
						 &call->rxtx_annotations[ix],
						 &rx_pkt_offset, &rx_pkt_len,
						 &rx_pkt_last);
			trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq,
					    rx_pkt_offset, rx_pkt_len, ret2);
			if (ret2 < 0) {
				ret = ret2;
				goto out;
			}
		} else {
			trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq,
					    rx_pkt_offset, rx_pkt_len, 0);
		}

		/* We have to handle short, empty and used-up DATA packets. */
		remain = len - *_offset;
		copy = rx_pkt_len;
		if (copy > remain)
			copy = remain;
		if (copy > 0) {
			ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
						      copy);
			if (ret2 < 0) {
				ret = ret2;
				goto out;
			}

			/* handle piecemeal consumption of data packets */
			rx_pkt_offset += copy;
			rx_pkt_len -= copy;
			*_offset += copy;
		}

		if (rx_pkt_len > 0) {
			trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq,
					    rx_pkt_offset, rx_pkt_len, 0);
			ASSERTCMP(*_offset, ==, len);
			ret = 0;
			break;
		}

		/* The whole packet has been transferred. */
		if (!(flags & MSG_PEEK))
			rxrpc_rotate_rx_window(call);
		rx_pkt_offset = 0;
		rx_pkt_len = 0;

		if (rx_pkt_last) {
			ASSERTCMP(seq, ==, READ_ONCE(call->rx_top));
			ret = 1;
			goto out;
		}

		seq++;
	}

out:
	if (!(flags & MSG_PEEK)) {
		call->rx_pkt_offset = rx_pkt_offset;
		call->rx_pkt_len = rx_pkt_len;
		call->rx_pkt_last = rx_pkt_last;
	}
done:
	trace_rxrpc_recvmsg(call, rxrpc_recvmsg_data_return, seq,
			    rx_pkt_offset, rx_pkt_len, ret);
	if (ret == -EAGAIN)
		set_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags);
	return ret;
}

/*
 * Receive a message from an RxRPC socket
 * - we need to be careful about two or more threads calling recvmsg
 *   simultaneously
 */
int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
		  int flags)
{
	struct rxrpc_call *call;
	struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
	struct list_head *l;
	size_t copied = 0;
	long timeo;
	int ret;

	DEFINE_WAIT(wait);

	trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0, 0, 0, 0);

	if (flags & (MSG_OOB | MSG_TRUNC))
		return -EOPNOTSUPP;

	timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);

try_again:
	lock_sock(&rx->sk);

	/* Return immediately if a client socket has no outstanding calls */
	if (RB_EMPTY_ROOT(&rx->calls) &&
	    list_empty(&rx->recvmsg_q) &&
	    rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
		release_sock(&rx->sk);
		return -EAGAIN;
	}

	if (list_empty(&rx->recvmsg_q)) {
		ret = -EWOULDBLOCK;
		if (timeo == 0) {
			call = NULL;
			goto error_no_call;
		}

		release_sock(&rx->sk);

		/* Wait for something to happen */
		prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
					  TASK_INTERRUPTIBLE);
		ret = sock_error(&rx->sk);
		if (ret)
			goto wait_error;

		if (list_empty(&rx->recvmsg_q)) {
			if (signal_pending(current))
				goto wait_interrupted;
			trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait,
					    0, 0, 0, 0);
			timeo = schedule_timeout(timeo);
		}
		finish_wait(sk_sleep(&rx->sk), &wait);
		goto try_again;
	}

	/* Find the next call and dequeue it if we're not just peeking.  If we
	 * do dequeue it, that comes with a ref that we will need to release.
	 */
	write_lock_bh(&rx->recvmsg_lock);
	l = rx->recvmsg_q.next;
	call = list_entry(l, struct rxrpc_call, recvmsg_link);
	if (!(flags & MSG_PEEK))
		list_del_init(&call->recvmsg_link);
	else
		rxrpc_get_call(call, rxrpc_call_got);
	write_unlock_bh(&rx->recvmsg_lock);

	trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0, 0, 0, 0);

	/* We're going to drop the socket lock, so we need to lock the call
	 * against interference by sendmsg.
	 */
	if (!mutex_trylock(&call->user_mutex)) {
		ret = -EWOULDBLOCK;
		if (flags & MSG_DONTWAIT)
			goto error_requeue_call;
		ret = -ERESTARTSYS;
		if (mutex_lock_interruptible(&call->user_mutex) < 0)
			goto error_requeue_call;
	}

	release_sock(&rx->sk);

	if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
		BUG();

	if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
		if (flags & MSG_CMSG_COMPAT) {
			unsigned int id32 = call->user_call_ID;

			ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
				       sizeof(unsigned int), &id32);
		} else {
			unsigned long idl = call->user_call_ID;

			ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
				       sizeof(unsigned long), &idl);
		}
		if (ret < 0)
			goto error_unlock_call;
	}

	if (msg->msg_name) {
		struct sockaddr_rxrpc *srx = msg->msg_name;
		size_t len = sizeof(call->peer->srx);

		memcpy(msg->msg_name, &call->peer->srx, len);
		srx->srx_service = call->service_id;
		msg->msg_namelen = len;
	}

	switch (READ_ONCE(call->state)) {
	case RXRPC_CALL_SERVER_ACCEPTING:
		ret = rxrpc_recvmsg_new_call(rx, call, msg, flags);
		break;
	case RXRPC_CALL_CLIENT_RECV_REPLY:
	case RXRPC_CALL_SERVER_RECV_REQUEST:
	case RXRPC_CALL_SERVER_ACK_REQUEST:
		ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
					 flags, &copied);
		if (ret == -EAGAIN)
			ret = 0;

		if (after(call->rx_top, call->rx_hard_ack) &&
		    call->rxtx_buffer[(call->rx_hard_ack + 1) & RXRPC_RXTX_BUFF_MASK])
			rxrpc_notify_socket(call);
		break;
	default:
		ret = 0;
		break;
	}

	if (ret < 0)
		goto error_unlock_call;

	if (call->state == RXRPC_CALL_COMPLETE) {
		ret = rxrpc_recvmsg_term(call, msg);
		if (ret < 0)
			goto error_unlock_call;
		if (!(flags & MSG_PEEK))
			rxrpc_release_call(rx, call);
		msg->msg_flags |= MSG_EOR;
		ret = 1;
	}

	if (ret == 0)
		msg->msg_flags |= MSG_MORE;
	else
		msg->msg_flags &= ~MSG_MORE;
	ret = copied;

error_unlock_call:
	mutex_unlock(&call->user_mutex);
	rxrpc_put_call(call, rxrpc_call_put);
	trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
	return ret;

error_requeue_call:
	if (!(flags & MSG_PEEK)) {
		write_lock_bh(&rx->recvmsg_lock);
		list_add(&call->recvmsg_link, &rx->recvmsg_q);
		write_unlock_bh(&rx->recvmsg_lock);
		trace_rxrpc_recvmsg(call, rxrpc_recvmsg_requeue, 0, 0, 0, 0);
	} else {
		rxrpc_put_call(call, rxrpc_call_put);
	}
error_no_call:
	release_sock(&rx->sk);
error_trace:
	trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
	return ret;

wait_interrupted:
	ret = sock_intr_errno(timeo);
wait_error:
	finish_wait(sk_sleep(&rx->sk), &wait);
	call = NULL;
	goto error_trace;
}

/**
 * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 * @sock: The socket that the call exists on
 * @call: The call to send data through
 * @iter: The buffer to receive into
 * @want_more: True if more data is expected to be read
 * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 * @_service: Where to store the actual service ID (may be upgraded)
 *
 * Allow a kernel service to receive data and pick up information about the
 * state of a call.  Returns 0 if got what was asked for and there's more
 * available, 1 if we got what was asked for and we're at the end of the data
 * and -EAGAIN if we need more data.
 *
 * Note that we may return -EAGAIN to drain empty packets at the end of the
 * data, even if we've already copied over the requested data.
 *
 * *_abort should also be initialised to 0.
 */
int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
			   struct iov_iter *iter,
			   bool want_more, u32 *_abort, u16 *_service)
{
	size_t offset = 0;
	int ret;

	_enter("{%d,%s},%zu,%d",
	       call->debug_id, rxrpc_call_states[call->state],
	       iov_iter_count(iter), want_more);

	ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_ACCEPTING);

	mutex_lock(&call->user_mutex);

	switch (READ_ONCE(call->state)) {
	case RXRPC_CALL_CLIENT_RECV_REPLY:
	case RXRPC_CALL_SERVER_RECV_REQUEST:
	case RXRPC_CALL_SERVER_ACK_REQUEST:
		ret = rxrpc_recvmsg_data(sock, call, NULL, iter,
					 iov_iter_count(iter), 0,
					 &offset);
		if (ret < 0)
			goto out;

		/* We can only reach here with a partially full buffer if we
		 * have reached the end of the data.  We must otherwise have a
		 * full buffer or have been given -EAGAIN.
		 */
		if (ret == 1) {
			if (iov_iter_count(iter) > 0)
				goto short_data;
			if (!want_more)
				goto read_phase_complete;
			ret = 0;
			goto out;
		}

		if (!want_more)
			goto excess_data;
		goto out;

	case RXRPC_CALL_COMPLETE:
		goto call_complete;

	default:
		ret = -EINPROGRESS;
		goto out;
	}

read_phase_complete:
	ret = 1;
out:
	switch (call->ackr_reason) {
	case RXRPC_ACK_IDLE:
		break;
	case RXRPC_ACK_DELAY:
		if (ret != -EAGAIN)
			break;
		/* Fall through */
	default:
		rxrpc_send_ack_packet(call, false, NULL);
	}

	if (_service)
		*_service = call->service_id;
	mutex_unlock(&call->user_mutex);
	_leave(" = %d [%zu,%d]", ret, iov_iter_count(iter), *_abort);
	return ret;

short_data:
	trace_rxrpc_rx_eproto(call, 0, tracepoint_string("short_data"));
	ret = -EBADMSG;
	goto out;
excess_data:
	trace_rxrpc_rx_eproto(call, 0, tracepoint_string("excess_data"));
	ret = -EMSGSIZE;
	goto out;
call_complete:
	*_abort = call->abort_code;
	ret = call->error;
	if (call->completion == RXRPC_CALL_SUCCEEDED) {
		ret = 1;
		if (iov_iter_count(iter) > 0)
			ret = -ECONNRESET;
	}
	goto out;
}
EXPORT_SYMBOL(rxrpc_kernel_recv_data);

/**
 * rxrpc_kernel_get_reply_time - Get timestamp on first reply packet
 * @sock: The socket that the call exists on
 * @call: The call to query
 * @_ts: Where to put the timestamp
 *
 * Retrieve the timestamp from the first DATA packet of the reply if it is
 * in the ring.  Returns true if successful, false if not.
 */
bool rxrpc_kernel_get_reply_time(struct socket *sock, struct rxrpc_call *call,
				 ktime_t *_ts)
{
	struct sk_buff *skb;
	rxrpc_seq_t hard_ack, top, seq;
	bool success = false;

	mutex_lock(&call->user_mutex);

	if (READ_ONCE(call->state) != RXRPC_CALL_CLIENT_RECV_REPLY)
		goto out;

	hard_ack = call->rx_hard_ack;
	if (hard_ack != 0)
		goto out;

	seq = hard_ack + 1;
	top = smp_load_acquire(&call->rx_top);
	if (after(seq, top))
		goto out;

	skb = call->rxtx_buffer[seq & RXRPC_RXTX_BUFF_MASK];
	if (!skb)
		goto out;

	*_ts = skb_get_ktime(skb);
	success = true;

out:
	mutex_unlock(&call->user_mutex);
	return success;
}
EXPORT_SYMBOL(rxrpc_kernel_get_reply_time);