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1  /* RxRPC packet reception
2   *
3   * Copyright (C) 2007, 2016 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 <net/sock.h>
24  #include <net/af_rxrpc.h>
25  #include <net/ip.h>
26  #include <net/udp.h>
27  #include <net/net_namespace.h>
28  #include "ar-internal.h"
29  
rxrpc_proto_abort(const char * why,struct rxrpc_call * call,rxrpc_seq_t seq)30  static void rxrpc_proto_abort(const char *why,
31  			      struct rxrpc_call *call, rxrpc_seq_t seq)
32  {
33  	if (rxrpc_abort_call(why, call, seq, RX_PROTOCOL_ERROR, EBADMSG)) {
34  		set_bit(RXRPC_CALL_EV_ABORT, &call->events);
35  		rxrpc_queue_call(call);
36  	}
37  }
38  
39  /*
40   * Do TCP-style congestion management [RFC 5681].
41   */
rxrpc_congestion_management(struct rxrpc_call * call,struct sk_buff * skb,struct rxrpc_ack_summary * summary,rxrpc_serial_t acked_serial)42  static void rxrpc_congestion_management(struct rxrpc_call *call,
43  					struct sk_buff *skb,
44  					struct rxrpc_ack_summary *summary,
45  					rxrpc_serial_t acked_serial)
46  {
47  	enum rxrpc_congest_change change = rxrpc_cong_no_change;
48  	unsigned int cumulative_acks = call->cong_cumul_acks;
49  	unsigned int cwnd = call->cong_cwnd;
50  	bool resend = false;
51  
52  	summary->flight_size =
53  		(call->tx_top - call->tx_hard_ack) - summary->nr_acks;
54  
55  	if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
56  		summary->retrans_timeo = true;
57  		call->cong_ssthresh = max_t(unsigned int,
58  					    summary->flight_size / 2, 2);
59  		cwnd = 1;
60  		if (cwnd >= call->cong_ssthresh &&
61  		    call->cong_mode == RXRPC_CALL_SLOW_START) {
62  			call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
63  			call->cong_tstamp = skb->tstamp;
64  			cumulative_acks = 0;
65  		}
66  	}
67  
68  	cumulative_acks += summary->nr_new_acks;
69  	cumulative_acks += summary->nr_rot_new_acks;
70  	if (cumulative_acks > 255)
71  		cumulative_acks = 255;
72  
73  	summary->mode = call->cong_mode;
74  	summary->cwnd = call->cong_cwnd;
75  	summary->ssthresh = call->cong_ssthresh;
76  	summary->cumulative_acks = cumulative_acks;
77  	summary->dup_acks = call->cong_dup_acks;
78  
79  	switch (call->cong_mode) {
80  	case RXRPC_CALL_SLOW_START:
81  		if (summary->nr_nacks > 0)
82  			goto packet_loss_detected;
83  		if (summary->cumulative_acks > 0)
84  			cwnd += 1;
85  		if (cwnd >= call->cong_ssthresh) {
86  			call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
87  			call->cong_tstamp = skb->tstamp;
88  		}
89  		goto out;
90  
91  	case RXRPC_CALL_CONGEST_AVOIDANCE:
92  		if (summary->nr_nacks > 0)
93  			goto packet_loss_detected;
94  
95  		/* We analyse the number of packets that get ACK'd per RTT
96  		 * period and increase the window if we managed to fill it.
97  		 */
98  		if (call->peer->rtt_usage == 0)
99  			goto out;
100  		if (ktime_before(skb->tstamp,
101  				 ktime_add_ns(call->cong_tstamp,
102  					      call->peer->rtt)))
103  			goto out_no_clear_ca;
104  		change = rxrpc_cong_rtt_window_end;
105  		call->cong_tstamp = skb->tstamp;
106  		if (cumulative_acks >= cwnd)
107  			cwnd++;
108  		goto out;
109  
110  	case RXRPC_CALL_PACKET_LOSS:
111  		if (summary->nr_nacks == 0)
112  			goto resume_normality;
113  
114  		if (summary->new_low_nack) {
115  			change = rxrpc_cong_new_low_nack;
116  			call->cong_dup_acks = 1;
117  			if (call->cong_extra > 1)
118  				call->cong_extra = 1;
119  			goto send_extra_data;
120  		}
121  
122  		call->cong_dup_acks++;
123  		if (call->cong_dup_acks < 3)
124  			goto send_extra_data;
125  
126  		change = rxrpc_cong_begin_retransmission;
127  		call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT;
128  		call->cong_ssthresh = max_t(unsigned int,
129  					    summary->flight_size / 2, 2);
130  		cwnd = call->cong_ssthresh + 3;
131  		call->cong_extra = 0;
132  		call->cong_dup_acks = 0;
133  		resend = true;
134  		goto out;
135  
136  	case RXRPC_CALL_FAST_RETRANSMIT:
137  		if (!summary->new_low_nack) {
138  			if (summary->nr_new_acks == 0)
139  				cwnd += 1;
140  			call->cong_dup_acks++;
141  			if (call->cong_dup_acks == 2) {
142  				change = rxrpc_cong_retransmit_again;
143  				call->cong_dup_acks = 0;
144  				resend = true;
145  			}
146  		} else {
147  			change = rxrpc_cong_progress;
148  			cwnd = call->cong_ssthresh;
149  			if (summary->nr_nacks == 0)
150  				goto resume_normality;
151  		}
152  		goto out;
153  
154  	default:
155  		BUG();
156  		goto out;
157  	}
158  
159  resume_normality:
160  	change = rxrpc_cong_cleared_nacks;
161  	call->cong_dup_acks = 0;
162  	call->cong_extra = 0;
163  	call->cong_tstamp = skb->tstamp;
164  	if (cwnd < call->cong_ssthresh)
165  		call->cong_mode = RXRPC_CALL_SLOW_START;
166  	else
167  		call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
168  out:
169  	cumulative_acks = 0;
170  out_no_clear_ca:
171  	if (cwnd >= RXRPC_RXTX_BUFF_SIZE - 1)
172  		cwnd = RXRPC_RXTX_BUFF_SIZE - 1;
173  	call->cong_cwnd = cwnd;
174  	call->cong_cumul_acks = cumulative_acks;
175  	trace_rxrpc_congest(call, summary, acked_serial, change);
176  	if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
177  		rxrpc_queue_call(call);
178  	return;
179  
180  packet_loss_detected:
181  	change = rxrpc_cong_saw_nack;
182  	call->cong_mode = RXRPC_CALL_PACKET_LOSS;
183  	call->cong_dup_acks = 0;
184  	goto send_extra_data;
185  
186  send_extra_data:
187  	/* Send some previously unsent DATA if we have some to advance the ACK
188  	 * state.
189  	 */
190  	if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
191  	    RXRPC_TX_ANNO_LAST ||
192  	    summary->nr_acks != call->tx_top - call->tx_hard_ack) {
193  		call->cong_extra++;
194  		wake_up(&call->waitq);
195  	}
196  	goto out_no_clear_ca;
197  }
198  
199  /*
200   * Ping the other end to fill our RTT cache and to retrieve the rwind
201   * and MTU parameters.
202   */
rxrpc_send_ping(struct rxrpc_call * call,struct sk_buff * skb,int skew)203  static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb,
204  			    int skew)
205  {
206  	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
207  	ktime_t now = skb->tstamp;
208  
209  	if (call->peer->rtt_usage < 3 ||
210  	    ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
211  		rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
212  				  true, true,
213  				  rxrpc_propose_ack_ping_for_params);
214  }
215  
216  /*
217   * Apply a hard ACK by advancing the Tx window.
218   */
rxrpc_rotate_tx_window(struct rxrpc_call * call,rxrpc_seq_t to,struct rxrpc_ack_summary * summary)219  static void rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
220  				   struct rxrpc_ack_summary *summary)
221  {
222  	struct sk_buff *skb, *list = NULL;
223  	int ix;
224  	u8 annotation;
225  
226  	if (call->acks_lowest_nak == call->tx_hard_ack) {
227  		call->acks_lowest_nak = to;
228  	} else if (before_eq(call->acks_lowest_nak, to)) {
229  		summary->new_low_nack = true;
230  		call->acks_lowest_nak = to;
231  	}
232  
233  	spin_lock(&call->lock);
234  
235  	while (before(call->tx_hard_ack, to)) {
236  		call->tx_hard_ack++;
237  		ix = call->tx_hard_ack & RXRPC_RXTX_BUFF_MASK;
238  		skb = call->rxtx_buffer[ix];
239  		annotation = call->rxtx_annotations[ix];
240  		rxrpc_see_skb(skb, rxrpc_skb_tx_rotated);
241  		call->rxtx_buffer[ix] = NULL;
242  		call->rxtx_annotations[ix] = 0;
243  		skb->next = list;
244  		list = skb;
245  
246  		if (annotation & RXRPC_TX_ANNO_LAST)
247  			set_bit(RXRPC_CALL_TX_LAST, &call->flags);
248  		if ((annotation & RXRPC_TX_ANNO_MASK) != RXRPC_TX_ANNO_ACK)
249  			summary->nr_rot_new_acks++;
250  	}
251  
252  	spin_unlock(&call->lock);
253  
254  	trace_rxrpc_transmit(call, (test_bit(RXRPC_CALL_TX_LAST, &call->flags) ?
255  				    rxrpc_transmit_rotate_last :
256  				    rxrpc_transmit_rotate));
257  	wake_up(&call->waitq);
258  
259  	while (list) {
260  		skb = list;
261  		list = skb->next;
262  		skb->next = NULL;
263  		rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
264  	}
265  }
266  
267  /*
268   * End the transmission phase of a call.
269   *
270   * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
271   * or a final ACK packet.
272   */
rxrpc_end_tx_phase(struct rxrpc_call * call,bool reply_begun,const char * abort_why)273  static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
274  			       const char *abort_why)
275  {
276  
277  	ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
278  
279  	write_lock(&call->state_lock);
280  
281  	switch (call->state) {
282  	case RXRPC_CALL_CLIENT_SEND_REQUEST:
283  	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
284  		if (reply_begun)
285  			call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
286  		else
287  			call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
288  		break;
289  
290  	case RXRPC_CALL_SERVER_AWAIT_ACK:
291  		__rxrpc_call_completed(call);
292  		rxrpc_notify_socket(call);
293  		break;
294  
295  	default:
296  		goto bad_state;
297  	}
298  
299  	write_unlock(&call->state_lock);
300  	if (call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY) {
301  		rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, 0, 0, false, true,
302  				  rxrpc_propose_ack_client_tx_end);
303  		trace_rxrpc_transmit(call, rxrpc_transmit_await_reply);
304  	} else {
305  		trace_rxrpc_transmit(call, rxrpc_transmit_end);
306  	}
307  	_leave(" = ok");
308  	return true;
309  
310  bad_state:
311  	write_unlock(&call->state_lock);
312  	kdebug("end_tx %s", rxrpc_call_states[call->state]);
313  	rxrpc_proto_abort(abort_why, call, call->tx_top);
314  	return false;
315  }
316  
317  /*
318   * Begin the reply reception phase of a call.
319   */
rxrpc_receiving_reply(struct rxrpc_call * call)320  static bool rxrpc_receiving_reply(struct rxrpc_call *call)
321  {
322  	struct rxrpc_ack_summary summary = { 0 };
323  	rxrpc_seq_t top = READ_ONCE(call->tx_top);
324  
325  	if (call->ackr_reason) {
326  		spin_lock_bh(&call->lock);
327  		call->ackr_reason = 0;
328  		call->resend_at = call->expire_at;
329  		call->ack_at = call->expire_at;
330  		spin_unlock_bh(&call->lock);
331  		rxrpc_set_timer(call, rxrpc_timer_init_for_reply,
332  				ktime_get_real());
333  	}
334  
335  	if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags))
336  		rxrpc_rotate_tx_window(call, top, &summary);
337  	if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
338  		rxrpc_proto_abort("TXL", call, top);
339  		return false;
340  	}
341  	if (!rxrpc_end_tx_phase(call, true, "ETD"))
342  		return false;
343  	call->tx_phase = false;
344  	return true;
345  }
346  
347  /*
348   * Scan a jumbo packet to validate its structure and to work out how many
349   * subpackets it contains.
350   *
351   * A jumbo packet is a collection of consecutive packets glued together with
352   * little headers between that indicate how to change the initial header for
353   * each subpacket.
354   *
355   * RXRPC_JUMBO_PACKET must be set on all but the last subpacket - and all but
356   * the last are RXRPC_JUMBO_DATALEN in size.  The last subpacket may be of any
357   * size.
358   */
rxrpc_validate_jumbo(struct sk_buff * skb)359  static bool rxrpc_validate_jumbo(struct sk_buff *skb)
360  {
361  	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
362  	unsigned int offset = sizeof(struct rxrpc_wire_header);
363  	unsigned int len = skb->len;
364  	int nr_jumbo = 1;
365  	u8 flags = sp->hdr.flags;
366  
367  	do {
368  		nr_jumbo++;
369  		if (len - offset < RXRPC_JUMBO_SUBPKTLEN)
370  			goto protocol_error;
371  		if (flags & RXRPC_LAST_PACKET)
372  			goto protocol_error;
373  		offset += RXRPC_JUMBO_DATALEN;
374  		if (skb_copy_bits(skb, offset, &flags, 1) < 0)
375  			goto protocol_error;
376  		offset += sizeof(struct rxrpc_jumbo_header);
377  	} while (flags & RXRPC_JUMBO_PACKET);
378  
379  	sp->nr_jumbo = nr_jumbo;
380  	return true;
381  
382  protocol_error:
383  	return false;
384  }
385  
386  /*
387   * Handle reception of a duplicate packet.
388   *
389   * We have to take care to avoid an attack here whereby we're given a series of
390   * jumbograms, each with a sequence number one before the preceding one and
391   * filled up to maximum UDP size.  If they never send us the first packet in
392   * the sequence, they can cause us to have to hold on to around 2MiB of kernel
393   * space until the call times out.
394   *
395   * We limit the space usage by only accepting three duplicate jumbo packets per
396   * call.  After that, we tell the other side we're no longer accepting jumbos
397   * (that information is encoded in the ACK packet).
398   */
rxrpc_input_dup_data(struct rxrpc_call * call,rxrpc_seq_t seq,u8 annotation,bool * _jumbo_bad)399  static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
400  				 u8 annotation, bool *_jumbo_bad)
401  {
402  	/* Discard normal packets that are duplicates. */
403  	if (annotation == 0)
404  		return;
405  
406  	/* Skip jumbo subpackets that are duplicates.  When we've had three or
407  	 * more partially duplicate jumbo packets, we refuse to take any more
408  	 * jumbos for this call.
409  	 */
410  	if (!*_jumbo_bad) {
411  		call->nr_jumbo_bad++;
412  		*_jumbo_bad = true;
413  	}
414  }
415  
416  /*
417   * Process a DATA packet, adding the packet to the Rx ring.
418   */
rxrpc_input_data(struct rxrpc_call * call,struct sk_buff * skb,u16 skew)419  static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb,
420  			     u16 skew)
421  {
422  	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
423  	unsigned int offset = sizeof(struct rxrpc_wire_header);
424  	unsigned int ix;
425  	rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
426  	rxrpc_seq_t seq = sp->hdr.seq, hard_ack;
427  	bool immediate_ack = false, jumbo_bad = false, queued;
428  	u16 len;
429  	u8 ack = 0, flags, annotation = 0;
430  
431  	_enter("{%u,%u},{%u,%u}",
432  	       call->rx_hard_ack, call->rx_top, skb->len, seq);
433  
434  	_proto("Rx DATA %%%u { #%u f=%02x }",
435  	       sp->hdr.serial, seq, sp->hdr.flags);
436  
437  	if (call->state >= RXRPC_CALL_COMPLETE)
438  		return;
439  
440  	/* Received data implicitly ACKs all of the request packets we sent
441  	 * when we're acting as a client.
442  	 */
443  	if ((call->state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
444  	     call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
445  	    !rxrpc_receiving_reply(call))
446  		return;
447  
448  	call->ackr_prev_seq = seq;
449  
450  	hard_ack = READ_ONCE(call->rx_hard_ack);
451  	if (after(seq, hard_ack + call->rx_winsize)) {
452  		ack = RXRPC_ACK_EXCEEDS_WINDOW;
453  		ack_serial = serial;
454  		goto ack;
455  	}
456  
457  	flags = sp->hdr.flags;
458  	if (flags & RXRPC_JUMBO_PACKET) {
459  		if (call->nr_jumbo_bad > 3) {
460  			ack = RXRPC_ACK_NOSPACE;
461  			ack_serial = serial;
462  			goto ack;
463  		}
464  		annotation = 1;
465  	}
466  
467  next_subpacket:
468  	queued = false;
469  	ix = seq & RXRPC_RXTX_BUFF_MASK;
470  	len = skb->len;
471  	if (flags & RXRPC_JUMBO_PACKET)
472  		len = RXRPC_JUMBO_DATALEN;
473  
474  	if (flags & RXRPC_LAST_PACKET) {
475  		if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
476  		    seq != call->rx_top)
477  			return rxrpc_proto_abort("LSN", call, seq);
478  	} else {
479  		if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
480  		    after_eq(seq, call->rx_top))
481  			return rxrpc_proto_abort("LSA", call, seq);
482  	}
483  
484  	if (before_eq(seq, hard_ack)) {
485  		ack = RXRPC_ACK_DUPLICATE;
486  		ack_serial = serial;
487  		goto skip;
488  	}
489  
490  	if (flags & RXRPC_REQUEST_ACK && !ack) {
491  		ack = RXRPC_ACK_REQUESTED;
492  		ack_serial = serial;
493  	}
494  
495  	if (call->rxtx_buffer[ix]) {
496  		rxrpc_input_dup_data(call, seq, annotation, &jumbo_bad);
497  		if (ack != RXRPC_ACK_DUPLICATE) {
498  			ack = RXRPC_ACK_DUPLICATE;
499  			ack_serial = serial;
500  		}
501  		immediate_ack = true;
502  		goto skip;
503  	}
504  
505  	/* Queue the packet.  We use a couple of memory barriers here as need
506  	 * to make sure that rx_top is perceived to be set after the buffer
507  	 * pointer and that the buffer pointer is set after the annotation and
508  	 * the skb data.
509  	 *
510  	 * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
511  	 * and also rxrpc_fill_out_ack().
512  	 */
513  	rxrpc_get_skb(skb, rxrpc_skb_rx_got);
514  	call->rxtx_annotations[ix] = annotation;
515  	smp_wmb();
516  	call->rxtx_buffer[ix] = skb;
517  	if (after(seq, call->rx_top)) {
518  		smp_store_release(&call->rx_top, seq);
519  	} else if (before(seq, call->rx_top)) {
520  		/* Send an immediate ACK if we fill in a hole */
521  		if (!ack) {
522  			ack = RXRPC_ACK_DELAY;
523  			ack_serial = serial;
524  		}
525  		immediate_ack = true;
526  	}
527  	if (flags & RXRPC_LAST_PACKET) {
528  		set_bit(RXRPC_CALL_RX_LAST, &call->flags);
529  		trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
530  	} else {
531  		trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
532  	}
533  	queued = true;
534  
535  	if (after_eq(seq, call->rx_expect_next)) {
536  		if (after(seq, call->rx_expect_next)) {
537  			_net("OOS %u > %u", seq, call->rx_expect_next);
538  			ack = RXRPC_ACK_OUT_OF_SEQUENCE;
539  			ack_serial = serial;
540  		}
541  		call->rx_expect_next = seq + 1;
542  	}
543  
544  skip:
545  	offset += len;
546  	if (flags & RXRPC_JUMBO_PACKET) {
547  		if (skb_copy_bits(skb, offset, &flags, 1) < 0)
548  			return rxrpc_proto_abort("XJF", call, seq);
549  		offset += sizeof(struct rxrpc_jumbo_header);
550  		seq++;
551  		serial++;
552  		annotation++;
553  		if (flags & RXRPC_JUMBO_PACKET)
554  			annotation |= RXRPC_RX_ANNO_JLAST;
555  		if (after(seq, hard_ack + call->rx_winsize)) {
556  			ack = RXRPC_ACK_EXCEEDS_WINDOW;
557  			ack_serial = serial;
558  			if (!jumbo_bad) {
559  				call->nr_jumbo_bad++;
560  				jumbo_bad = true;
561  			}
562  			goto ack;
563  		}
564  
565  		_proto("Rx DATA Jumbo %%%u", serial);
566  		goto next_subpacket;
567  	}
568  
569  	if (queued && flags & RXRPC_LAST_PACKET && !ack) {
570  		ack = RXRPC_ACK_DELAY;
571  		ack_serial = serial;
572  	}
573  
574  ack:
575  	if (ack)
576  		rxrpc_propose_ACK(call, ack, skew, ack_serial,
577  				  immediate_ack, true,
578  				  rxrpc_propose_ack_input_data);
579  
580  	if (sp->hdr.seq == READ_ONCE(call->rx_hard_ack) + 1)
581  		rxrpc_notify_socket(call);
582  	_leave(" [queued]");
583  }
584  
585  /*
586   * Process a requested ACK.
587   */
rxrpc_input_requested_ack(struct rxrpc_call * call,ktime_t resp_time,rxrpc_serial_t orig_serial,rxrpc_serial_t ack_serial)588  static void rxrpc_input_requested_ack(struct rxrpc_call *call,
589  				      ktime_t resp_time,
590  				      rxrpc_serial_t orig_serial,
591  				      rxrpc_serial_t ack_serial)
592  {
593  	struct rxrpc_skb_priv *sp;
594  	struct sk_buff *skb;
595  	ktime_t sent_at;
596  	int ix;
597  
598  	for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
599  		skb = call->rxtx_buffer[ix];
600  		if (!skb)
601  			continue;
602  
603  		sp = rxrpc_skb(skb);
604  		if (sp->hdr.serial != orig_serial)
605  			continue;
606  		smp_rmb();
607  		sent_at = skb->tstamp;
608  		goto found;
609  	}
610  	return;
611  
612  found:
613  	rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
614  			   orig_serial, ack_serial, sent_at, resp_time);
615  }
616  
617  /*
618   * Process a ping response.
619   */
rxrpc_input_ping_response(struct rxrpc_call * call,ktime_t resp_time,rxrpc_serial_t orig_serial,rxrpc_serial_t ack_serial)620  static void rxrpc_input_ping_response(struct rxrpc_call *call,
621  				      ktime_t resp_time,
622  				      rxrpc_serial_t orig_serial,
623  				      rxrpc_serial_t ack_serial)
624  {
625  	rxrpc_serial_t ping_serial;
626  	ktime_t ping_time;
627  
628  	ping_time = call->ping_time;
629  	smp_rmb();
630  	ping_serial = call->ping_serial;
631  
632  	if (!test_bit(RXRPC_CALL_PINGING, &call->flags) ||
633  	    before(orig_serial, ping_serial))
634  		return;
635  	clear_bit(RXRPC_CALL_PINGING, &call->flags);
636  	if (after(orig_serial, ping_serial))
637  		return;
638  
639  	rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
640  			   orig_serial, ack_serial, ping_time, resp_time);
641  }
642  
643  /*
644   * Process the extra information that may be appended to an ACK packet
645   */
rxrpc_input_ackinfo(struct rxrpc_call * call,struct sk_buff * skb,struct rxrpc_ackinfo * ackinfo)646  static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
647  				struct rxrpc_ackinfo *ackinfo)
648  {
649  	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
650  	struct rxrpc_peer *peer;
651  	unsigned int mtu;
652  	bool wake = false;
653  	u32 rwind = ntohl(ackinfo->rwind);
654  
655  	_proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
656  	       sp->hdr.serial,
657  	       ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
658  	       rwind, ntohl(ackinfo->jumbo_max));
659  
660  	if (call->tx_winsize != rwind) {
661  		if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
662  			rwind = RXRPC_RXTX_BUFF_SIZE - 1;
663  		if (rwind > call->tx_winsize)
664  			wake = true;
665  		call->tx_winsize = rwind;
666  	}
667  
668  	if (call->cong_ssthresh > rwind)
669  		call->cong_ssthresh = rwind;
670  
671  	mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
672  
673  	peer = call->peer;
674  	if (mtu < peer->maxdata) {
675  		spin_lock_bh(&peer->lock);
676  		peer->maxdata = mtu;
677  		peer->mtu = mtu + peer->hdrsize;
678  		spin_unlock_bh(&peer->lock);
679  		_net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
680  	}
681  
682  	if (wake)
683  		wake_up(&call->waitq);
684  }
685  
686  /*
687   * Process individual soft ACKs.
688   *
689   * Each ACK in the array corresponds to one packet and can be either an ACK or
690   * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
691   * packets that lie beyond the end of the ACK list are scheduled for resend by
692   * the timer on the basis that the peer might just not have processed them at
693   * the time the ACK was sent.
694   */
rxrpc_input_soft_acks(struct rxrpc_call * call,u8 * acks,rxrpc_seq_t seq,int nr_acks,struct rxrpc_ack_summary * summary)695  static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
696  				  rxrpc_seq_t seq, int nr_acks,
697  				  struct rxrpc_ack_summary *summary)
698  {
699  	int ix;
700  	u8 annotation, anno_type;
701  
702  	for (; nr_acks > 0; nr_acks--, seq++) {
703  		ix = seq & RXRPC_RXTX_BUFF_MASK;
704  		annotation = call->rxtx_annotations[ix];
705  		anno_type = annotation & RXRPC_TX_ANNO_MASK;
706  		annotation &= ~RXRPC_TX_ANNO_MASK;
707  		switch (*acks++) {
708  		case RXRPC_ACK_TYPE_ACK:
709  			summary->nr_acks++;
710  			if (anno_type == RXRPC_TX_ANNO_ACK)
711  				continue;
712  			summary->nr_new_acks++;
713  			call->rxtx_annotations[ix] =
714  				RXRPC_TX_ANNO_ACK | annotation;
715  			break;
716  		case RXRPC_ACK_TYPE_NACK:
717  			if (!summary->nr_nacks &&
718  			    call->acks_lowest_nak != seq) {
719  				call->acks_lowest_nak = seq;
720  				summary->new_low_nack = true;
721  			}
722  			summary->nr_nacks++;
723  			if (anno_type == RXRPC_TX_ANNO_NAK)
724  				continue;
725  			summary->nr_new_nacks++;
726  			if (anno_type == RXRPC_TX_ANNO_RETRANS)
727  				continue;
728  			call->rxtx_annotations[ix] =
729  				RXRPC_TX_ANNO_NAK | annotation;
730  			break;
731  		default:
732  			return rxrpc_proto_abort("SFT", call, 0);
733  		}
734  	}
735  }
736  
737  /*
738   * Process an ACK packet.
739   *
740   * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
741   * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
742   *
743   * A hard-ACK means that a packet has been processed and may be discarded; a
744   * soft-ACK means that the packet may be discarded and retransmission
745   * requested.  A phase is complete when all packets are hard-ACK'd.
746   */
rxrpc_input_ack(struct rxrpc_call * call,struct sk_buff * skb,u16 skew)747  static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
748  			    u16 skew)
749  {
750  	struct rxrpc_ack_summary summary = { 0 };
751  	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
752  	union {
753  		struct rxrpc_ackpacket ack;
754  		struct rxrpc_ackinfo info;
755  		u8 acks[RXRPC_MAXACKS];
756  	} buf;
757  	rxrpc_serial_t acked_serial;
758  	rxrpc_seq_t first_soft_ack, hard_ack;
759  	int nr_acks, offset, ioffset;
760  
761  	_enter("");
762  
763  	offset = sizeof(struct rxrpc_wire_header);
764  	if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
765  		_debug("extraction failure");
766  		return rxrpc_proto_abort("XAK", call, 0);
767  	}
768  	offset += sizeof(buf.ack);
769  
770  	acked_serial = ntohl(buf.ack.serial);
771  	first_soft_ack = ntohl(buf.ack.firstPacket);
772  	hard_ack = first_soft_ack - 1;
773  	nr_acks = buf.ack.nAcks;
774  	summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
775  			      buf.ack.reason : RXRPC_ACK__INVALID);
776  
777  	trace_rxrpc_rx_ack(call, first_soft_ack, summary.ack_reason, nr_acks);
778  
779  	_proto("Rx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
780  	       sp->hdr.serial,
781  	       ntohs(buf.ack.maxSkew),
782  	       first_soft_ack,
783  	       ntohl(buf.ack.previousPacket),
784  	       acked_serial,
785  	       rxrpc_ack_names[summary.ack_reason],
786  	       buf.ack.nAcks);
787  
788  	if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
789  		rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
790  					  sp->hdr.serial);
791  	if (buf.ack.reason == RXRPC_ACK_REQUESTED)
792  		rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
793  					  sp->hdr.serial);
794  
795  	if (buf.ack.reason == RXRPC_ACK_PING) {
796  		_proto("Rx ACK %%%u PING Request", sp->hdr.serial);
797  		rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
798  				  skew, sp->hdr.serial, true, true,
799  				  rxrpc_propose_ack_respond_to_ping);
800  	} else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
801  		rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
802  				  skew, sp->hdr.serial, true, true,
803  				  rxrpc_propose_ack_respond_to_ack);
804  	}
805  
806  	ioffset = offset + nr_acks + 3;
807  	if (skb->len >= ioffset + sizeof(buf.info)) {
808  		if (skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
809  			return rxrpc_proto_abort("XAI", call, 0);
810  		rxrpc_input_ackinfo(call, skb, &buf.info);
811  	}
812  
813  	if (first_soft_ack == 0)
814  		return rxrpc_proto_abort("AK0", call, 0);
815  
816  	/* Ignore ACKs unless we are or have just been transmitting. */
817  	switch (call->state) {
818  	case RXRPC_CALL_CLIENT_SEND_REQUEST:
819  	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
820  	case RXRPC_CALL_SERVER_SEND_REPLY:
821  	case RXRPC_CALL_SERVER_AWAIT_ACK:
822  		break;
823  	default:
824  		return;
825  	}
826  
827  	/* Discard any out-of-order or duplicate ACKs. */
828  	if (before_eq(sp->hdr.serial, call->acks_latest)) {
829  		_debug("discard ACK %d <= %d",
830  		       sp->hdr.serial, call->acks_latest);
831  		return;
832  	}
833  	call->acks_latest_ts = skb->tstamp;
834  	call->acks_latest = sp->hdr.serial;
835  
836  	if (before(hard_ack, call->tx_hard_ack) ||
837  	    after(hard_ack, call->tx_top))
838  		return rxrpc_proto_abort("AKW", call, 0);
839  	if (nr_acks > call->tx_top - hard_ack)
840  		return rxrpc_proto_abort("AKN", call, 0);
841  
842  	if (after(hard_ack, call->tx_hard_ack))
843  		rxrpc_rotate_tx_window(call, hard_ack, &summary);
844  
845  	if (nr_acks > 0) {
846  		if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0)
847  			return rxrpc_proto_abort("XSA", call, 0);
848  		rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
849  				      &summary);
850  	}
851  
852  	if (test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
853  		rxrpc_end_tx_phase(call, false, "ETA");
854  		return;
855  	}
856  
857  	if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
858  	    RXRPC_TX_ANNO_LAST &&
859  	    summary.nr_acks == call->tx_top - hard_ack &&
860  	    rxrpc_is_client_call(call))
861  		rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
862  				  false, true,
863  				  rxrpc_propose_ack_ping_for_lost_reply);
864  
865  	return rxrpc_congestion_management(call, skb, &summary, acked_serial);
866  }
867  
868  /*
869   * Process an ACKALL packet.
870   */
rxrpc_input_ackall(struct rxrpc_call * call,struct sk_buff * skb)871  static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
872  {
873  	struct rxrpc_ack_summary summary = { 0 };
874  	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
875  
876  	_proto("Rx ACKALL %%%u", sp->hdr.serial);
877  
878  	rxrpc_rotate_tx_window(call, call->tx_top, &summary);
879  	if (test_bit(RXRPC_CALL_TX_LAST, &call->flags))
880  		rxrpc_end_tx_phase(call, false, "ETL");
881  }
882  
883  /*
884   * Process an ABORT packet.
885   */
rxrpc_input_abort(struct rxrpc_call * call,struct sk_buff * skb)886  static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
887  {
888  	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
889  	__be32 wtmp;
890  	u32 abort_code = RX_CALL_DEAD;
891  
892  	_enter("");
893  
894  	if (skb->len >= 4 &&
895  	    skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
896  			  &wtmp, sizeof(wtmp)) >= 0)
897  		abort_code = ntohl(wtmp);
898  
899  	_proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
900  
901  	if (rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
902  				      abort_code, ECONNABORTED))
903  		rxrpc_notify_socket(call);
904  }
905  
906  /*
907   * Process an incoming call packet.
908   */
rxrpc_input_call_packet(struct rxrpc_call * call,struct sk_buff * skb,u16 skew)909  static void rxrpc_input_call_packet(struct rxrpc_call *call,
910  				    struct sk_buff *skb, u16 skew)
911  {
912  	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
913  
914  	_enter("%p,%p", call, skb);
915  
916  	switch (sp->hdr.type) {
917  	case RXRPC_PACKET_TYPE_DATA:
918  		rxrpc_input_data(call, skb, skew);
919  		break;
920  
921  	case RXRPC_PACKET_TYPE_ACK:
922  		rxrpc_input_ack(call, skb, skew);
923  		break;
924  
925  	case RXRPC_PACKET_TYPE_BUSY:
926  		_proto("Rx BUSY %%%u", sp->hdr.serial);
927  
928  		/* Just ignore BUSY packets from the server; the retry and
929  		 * lifespan timers will take care of business.  BUSY packets
930  		 * from the client don't make sense.
931  		 */
932  		break;
933  
934  	case RXRPC_PACKET_TYPE_ABORT:
935  		rxrpc_input_abort(call, skb);
936  		break;
937  
938  	case RXRPC_PACKET_TYPE_ACKALL:
939  		rxrpc_input_ackall(call, skb);
940  		break;
941  
942  	default:
943  		_proto("Rx %s %%%u", rxrpc_pkts[sp->hdr.type], sp->hdr.serial);
944  		break;
945  	}
946  
947  	_leave("");
948  }
949  
950  /*
951   * Handle a new call on a channel implicitly completing the preceding call on
952   * that channel.
953   *
954   * TODO: If callNumber > call_id + 1, renegotiate security.
955   */
rxrpc_input_implicit_end_call(struct rxrpc_connection * conn,struct rxrpc_call * call)956  static void rxrpc_input_implicit_end_call(struct rxrpc_connection *conn,
957  					  struct rxrpc_call *call)
958  {
959  	switch (call->state) {
960  	case RXRPC_CALL_SERVER_AWAIT_ACK:
961  		rxrpc_call_completed(call);
962  		break;
963  	case RXRPC_CALL_COMPLETE:
964  		break;
965  	default:
966  		if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, ESHUTDOWN)) {
967  			set_bit(RXRPC_CALL_EV_ABORT, &call->events);
968  			rxrpc_queue_call(call);
969  		}
970  		break;
971  	}
972  
973  	__rxrpc_disconnect_call(conn, call);
974  	rxrpc_notify_socket(call);
975  }
976  
977  /*
978   * post connection-level events to the connection
979   * - this includes challenges, responses, some aborts and call terminal packet
980   *   retransmission.
981   */
rxrpc_post_packet_to_conn(struct rxrpc_connection * conn,struct sk_buff * skb)982  static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
983  				      struct sk_buff *skb)
984  {
985  	_enter("%p,%p", conn, skb);
986  
987  	skb_queue_tail(&conn->rx_queue, skb);
988  	rxrpc_queue_conn(conn);
989  }
990  
991  /*
992   * post endpoint-level events to the local endpoint
993   * - this includes debug and version messages
994   */
rxrpc_post_packet_to_local(struct rxrpc_local * local,struct sk_buff * skb)995  static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
996  				       struct sk_buff *skb)
997  {
998  	_enter("%p,%p", local, skb);
999  
1000  	skb_queue_tail(&local->event_queue, skb);
1001  	rxrpc_queue_local(local);
1002  }
1003  
1004  /*
1005   * put a packet up for transport-level abort
1006   */
rxrpc_reject_packet(struct rxrpc_local * local,struct sk_buff * skb)1007  static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
1008  {
1009  	CHECK_SLAB_OKAY(&local->usage);
1010  
1011  	skb_queue_tail(&local->reject_queue, skb);
1012  	rxrpc_queue_local(local);
1013  }
1014  
1015  /*
1016   * Extract the wire header from a packet and translate the byte order.
1017   */
1018  static noinline
rxrpc_extract_header(struct rxrpc_skb_priv * sp,struct sk_buff * skb)1019  int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
1020  {
1021  	struct rxrpc_wire_header whdr;
1022  
1023  	/* dig out the RxRPC connection details */
1024  	if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0)
1025  		return -EBADMSG;
1026  
1027  	memset(sp, 0, sizeof(*sp));
1028  	sp->hdr.epoch		= ntohl(whdr.epoch);
1029  	sp->hdr.cid		= ntohl(whdr.cid);
1030  	sp->hdr.callNumber	= ntohl(whdr.callNumber);
1031  	sp->hdr.seq		= ntohl(whdr.seq);
1032  	sp->hdr.serial		= ntohl(whdr.serial);
1033  	sp->hdr.flags		= whdr.flags;
1034  	sp->hdr.type		= whdr.type;
1035  	sp->hdr.userStatus	= whdr.userStatus;
1036  	sp->hdr.securityIndex	= whdr.securityIndex;
1037  	sp->hdr._rsvd		= ntohs(whdr._rsvd);
1038  	sp->hdr.serviceId	= ntohs(whdr.serviceId);
1039  	return 0;
1040  }
1041  
1042  /*
1043   * handle data received on the local endpoint
1044   * - may be called in interrupt context
1045   *
1046   * The socket is locked by the caller and this prevents the socket from being
1047   * shut down and the local endpoint from going away, thus sk_user_data will not
1048   * be cleared until this function returns.
1049   */
rxrpc_data_ready(struct sock * udp_sk)1050  void rxrpc_data_ready(struct sock *udp_sk)
1051  {
1052  	struct rxrpc_connection *conn;
1053  	struct rxrpc_channel *chan;
1054  	struct rxrpc_call *call;
1055  	struct rxrpc_skb_priv *sp;
1056  	struct rxrpc_local *local = udp_sk->sk_user_data;
1057  	struct sk_buff *skb;
1058  	unsigned int channel;
1059  	int ret, skew;
1060  
1061  	_enter("%p", udp_sk);
1062  
1063  	ASSERT(!irqs_disabled());
1064  
1065  	skb = skb_recv_datagram(udp_sk, 0, 1, &ret);
1066  	if (!skb) {
1067  		if (ret == -EAGAIN)
1068  			return;
1069  		_debug("UDP socket error %d", ret);
1070  		return;
1071  	}
1072  
1073  	rxrpc_new_skb(skb, rxrpc_skb_rx_received);
1074  
1075  	_net("recv skb %p", skb);
1076  
1077  	/* we'll probably need to checksum it (didn't call sock_recvmsg) */
1078  	if (skb_checksum_complete(skb)) {
1079  		rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1080  		__UDP_INC_STATS(&init_net, UDP_MIB_INERRORS, 0);
1081  		_leave(" [CSUM failed]");
1082  		return;
1083  	}
1084  
1085  	__UDP_INC_STATS(&init_net, UDP_MIB_INDATAGRAMS, 0);
1086  
1087  	/* The socket buffer we have is owned by UDP, with UDP's data all over
1088  	 * it, but we really want our own data there.
1089  	 */
1090  	skb_orphan(skb);
1091  	sp = rxrpc_skb(skb);
1092  
1093  	/* dig out the RxRPC connection details */
1094  	if (rxrpc_extract_header(sp, skb) < 0)
1095  		goto bad_message;
1096  
1097  	if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
1098  		static int lose;
1099  		if ((lose++ & 7) == 7) {
1100  			trace_rxrpc_rx_lose(sp);
1101  			rxrpc_lose_skb(skb, rxrpc_skb_rx_lost);
1102  			return;
1103  		}
1104  	}
1105  
1106  	trace_rxrpc_rx_packet(sp);
1107  
1108  	_net("Rx RxRPC %s ep=%x call=%x:%x",
1109  	     sp->hdr.flags & RXRPC_CLIENT_INITIATED ? "ToServer" : "ToClient",
1110  	     sp->hdr.epoch, sp->hdr.cid, sp->hdr.callNumber);
1111  
1112  	if (sp->hdr.type >= RXRPC_N_PACKET_TYPES ||
1113  	    !((RXRPC_SUPPORTED_PACKET_TYPES >> sp->hdr.type) & 1)) {
1114  		_proto("Rx Bad Packet Type %u", sp->hdr.type);
1115  		goto bad_message;
1116  	}
1117  
1118  	switch (sp->hdr.type) {
1119  	case RXRPC_PACKET_TYPE_VERSION:
1120  		rxrpc_post_packet_to_local(local, skb);
1121  		goto out;
1122  
1123  	case RXRPC_PACKET_TYPE_BUSY:
1124  		if (sp->hdr.flags & RXRPC_CLIENT_INITIATED)
1125  			goto discard;
1126  
1127  	case RXRPC_PACKET_TYPE_DATA:
1128  		if (sp->hdr.callNumber == 0)
1129  			goto bad_message;
1130  		if (sp->hdr.flags & RXRPC_JUMBO_PACKET &&
1131  		    !rxrpc_validate_jumbo(skb))
1132  			goto bad_message;
1133  		break;
1134  	}
1135  
1136  	rcu_read_lock();
1137  
1138  	conn = rxrpc_find_connection_rcu(local, skb);
1139  	if (conn) {
1140  		if (sp->hdr.securityIndex != conn->security_ix)
1141  			goto wrong_security;
1142  
1143  		if (sp->hdr.callNumber == 0) {
1144  			/* Connection-level packet */
1145  			_debug("CONN %p {%d}", conn, conn->debug_id);
1146  			rxrpc_post_packet_to_conn(conn, skb);
1147  			goto out_unlock;
1148  		}
1149  
1150  		/* Note the serial number skew here */
1151  		skew = (int)sp->hdr.serial - (int)conn->hi_serial;
1152  		if (skew >= 0) {
1153  			if (skew > 0)
1154  				conn->hi_serial = sp->hdr.serial;
1155  		} else {
1156  			skew = -skew;
1157  			skew = min(skew, 65535);
1158  		}
1159  
1160  		/* Call-bound packets are routed by connection channel. */
1161  		channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1162  		chan = &conn->channels[channel];
1163  
1164  		/* Ignore really old calls */
1165  		if (sp->hdr.callNumber < chan->last_call)
1166  			goto discard_unlock;
1167  
1168  		if (sp->hdr.callNumber == chan->last_call) {
1169  			/* For the previous service call, if completed successfully, we
1170  			 * discard all further packets.
1171  			 */
1172  			if (rxrpc_conn_is_service(conn) &&
1173  			    (chan->last_type == RXRPC_PACKET_TYPE_ACK ||
1174  			     sp->hdr.type == RXRPC_PACKET_TYPE_ABORT))
1175  				goto discard_unlock;
1176  
1177  			/* But otherwise we need to retransmit the final packet from
1178  			 * data cached in the connection record.
1179  			 */
1180  			rxrpc_post_packet_to_conn(conn, skb);
1181  			goto out_unlock;
1182  		}
1183  
1184  		call = rcu_dereference(chan->call);
1185  
1186  		if (sp->hdr.callNumber > chan->call_id) {
1187  			if (!(sp->hdr.flags & RXRPC_CLIENT_INITIATED)) {
1188  				rcu_read_unlock();
1189  				goto reject_packet;
1190  			}
1191  			if (call)
1192  				rxrpc_input_implicit_end_call(conn, call);
1193  			call = NULL;
1194  		}
1195  	} else {
1196  		skew = 0;
1197  		call = NULL;
1198  	}
1199  
1200  	if (!call || atomic_read(&call->usage) == 0) {
1201  		if (!(sp->hdr.type & RXRPC_CLIENT_INITIATED) ||
1202  		    sp->hdr.callNumber == 0 ||
1203  		    sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1204  			goto bad_message_unlock;
1205  		if (sp->hdr.seq != 1)
1206  			goto discard_unlock;
1207  		call = rxrpc_new_incoming_call(local, conn, skb);
1208  		if (!call) {
1209  			rcu_read_unlock();
1210  			goto reject_packet;
1211  		}
1212  		rxrpc_send_ping(call, skb, skew);
1213  	}
1214  
1215  	rxrpc_input_call_packet(call, skb, skew);
1216  	goto discard_unlock;
1217  
1218  discard_unlock:
1219  	rcu_read_unlock();
1220  discard:
1221  	rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1222  out:
1223  	trace_rxrpc_rx_done(0, 0);
1224  	return;
1225  
1226  out_unlock:
1227  	rcu_read_unlock();
1228  	goto out;
1229  
1230  wrong_security:
1231  	rcu_read_unlock();
1232  	trace_rxrpc_abort("SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1233  			  RXKADINCONSISTENCY, EBADMSG);
1234  	skb->priority = RXKADINCONSISTENCY;
1235  	goto post_abort;
1236  
1237  bad_message_unlock:
1238  	rcu_read_unlock();
1239  bad_message:
1240  	trace_rxrpc_abort("BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1241  			  RX_PROTOCOL_ERROR, EBADMSG);
1242  	skb->priority = RX_PROTOCOL_ERROR;
1243  post_abort:
1244  	skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
1245  reject_packet:
1246  	trace_rxrpc_rx_done(skb->mark, skb->priority);
1247  	rxrpc_reject_packet(local, skb);
1248  	_leave(" [badmsg]");
1249  }
1250