1// SPDX-License-Identifier: GPL-2.0-or-later
   2/* RxRPC packet reception
   3 *
   4 * Copyright (C) 2007, 2016 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/module.h>
  11#include <linux/net.h>
  12#include <linux/skbuff.h>
  13#include <linux/errqueue.h>
  14#include <linux/udp.h>
  15#include <linux/in.h>
  16#include <linux/in6.h>
  17#include <linux/icmp.h>
  18#include <linux/gfp.h>
  19#include <net/sock.h>
  20#include <net/af_rxrpc.h>
  21#include <net/ip.h>
  22#include <net/udp.h>
  23#include <net/net_namespace.h>
  24#include "ar-internal.h"
  25
  26static void rxrpc_proto_abort(const char *why,
  27			      struct rxrpc_call *call, rxrpc_seq_t seq)
  28{
  29	if (rxrpc_abort_call(why, call, seq, RX_PROTOCOL_ERROR, -EBADMSG)) {
  30		set_bit(RXRPC_CALL_EV_ABORT, &call->events);
  31		rxrpc_queue_call(call);
  32	}
  33}
  34
  35/*
  36 * Do TCP-style congestion management [RFC 5681].
  37 */
  38static void rxrpc_congestion_management(struct rxrpc_call *call,
  39					struct sk_buff *skb,
  40					struct rxrpc_ack_summary *summary,
  41					rxrpc_serial_t acked_serial)
  42{
  43	enum rxrpc_congest_change change = rxrpc_cong_no_change;
  44	unsigned int cumulative_acks = call->cong_cumul_acks;
  45	unsigned int cwnd = call->cong_cwnd;
  46	bool resend = false;
  47
  48	summary->flight_size =
  49		(call->tx_top - call->tx_hard_ack) - summary->nr_acks;
  50
  51	if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
  52		summary->retrans_timeo = true;
  53		call->cong_ssthresh = max_t(unsigned int,
  54					    summary->flight_size / 2, 2);
  55		cwnd = 1;
  56		if (cwnd >= call->cong_ssthresh &&
  57		    call->cong_mode == RXRPC_CALL_SLOW_START) {
  58			call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
  59			call->cong_tstamp = skb->tstamp;
  60			cumulative_acks = 0;
  61		}
  62	}
  63
  64	cumulative_acks += summary->nr_new_acks;
  65	cumulative_acks += summary->nr_rot_new_acks;
  66	if (cumulative_acks > 255)
  67		cumulative_acks = 255;
  68
  69	summary->mode = call->cong_mode;
  70	summary->cwnd = call->cong_cwnd;
  71	summary->ssthresh = call->cong_ssthresh;
  72	summary->cumulative_acks = cumulative_acks;
  73	summary->dup_acks = call->cong_dup_acks;
  74
  75	switch (call->cong_mode) {
  76	case RXRPC_CALL_SLOW_START:
  77		if (summary->nr_nacks > 0)
  78			goto packet_loss_detected;
  79		if (summary->cumulative_acks > 0)
  80			cwnd += 1;
  81		if (cwnd >= call->cong_ssthresh) {
  82			call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
  83			call->cong_tstamp = skb->tstamp;
  84		}
  85		goto out;
  86
  87	case RXRPC_CALL_CONGEST_AVOIDANCE:
  88		if (summary->nr_nacks > 0)
  89			goto packet_loss_detected;
  90
  91		/* We analyse the number of packets that get ACK'd per RTT
  92		 * period and increase the window if we managed to fill it.
  93		 */
  94		if (call->peer->rtt_count == 0)
  95			goto out;
  96		if (ktime_before(skb->tstamp,
  97				 ktime_add_us(call->cong_tstamp,
  98					      call->peer->srtt_us >> 3)))
  99			goto out_no_clear_ca;
 100		change = rxrpc_cong_rtt_window_end;
 101		call->cong_tstamp = skb->tstamp;
 102		if (cumulative_acks >= cwnd)
 103			cwnd++;
 104		goto out;
 105
 106	case RXRPC_CALL_PACKET_LOSS:
 107		if (summary->nr_nacks == 0)
 108			goto resume_normality;
 109
 110		if (summary->new_low_nack) {
 111			change = rxrpc_cong_new_low_nack;
 112			call->cong_dup_acks = 1;
 113			if (call->cong_extra > 1)
 114				call->cong_extra = 1;
 115			goto send_extra_data;
 116		}
 117
 118		call->cong_dup_acks++;
 119		if (call->cong_dup_acks < 3)
 120			goto send_extra_data;
 121
 122		change = rxrpc_cong_begin_retransmission;
 123		call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT;
 124		call->cong_ssthresh = max_t(unsigned int,
 125					    summary->flight_size / 2, 2);
 126		cwnd = call->cong_ssthresh + 3;
 127		call->cong_extra = 0;
 128		call->cong_dup_acks = 0;
 129		resend = true;
 130		goto out;
 131
 132	case RXRPC_CALL_FAST_RETRANSMIT:
 133		if (!summary->new_low_nack) {
 134			if (summary->nr_new_acks == 0)
 135				cwnd += 1;
 136			call->cong_dup_acks++;
 137			if (call->cong_dup_acks == 2) {
 138				change = rxrpc_cong_retransmit_again;
 139				call->cong_dup_acks = 0;
 140				resend = true;
 141			}
 142		} else {
 143			change = rxrpc_cong_progress;
 144			cwnd = call->cong_ssthresh;
 145			if (summary->nr_nacks == 0)
 146				goto resume_normality;
 147		}
 148		goto out;
 149
 150	default:
 151		BUG();
 152		goto out;
 153	}
 154
 155resume_normality:
 156	change = rxrpc_cong_cleared_nacks;
 157	call->cong_dup_acks = 0;
 158	call->cong_extra = 0;
 159	call->cong_tstamp = skb->tstamp;
 160	if (cwnd < call->cong_ssthresh)
 161		call->cong_mode = RXRPC_CALL_SLOW_START;
 162	else
 163		call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 164out:
 165	cumulative_acks = 0;
 166out_no_clear_ca:
 167	if (cwnd >= RXRPC_RXTX_BUFF_SIZE - 1)
 168		cwnd = RXRPC_RXTX_BUFF_SIZE - 1;
 169	call->cong_cwnd = cwnd;
 170	call->cong_cumul_acks = cumulative_acks;
 171	trace_rxrpc_congest(call, summary, acked_serial, change);
 172	if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 173		rxrpc_queue_call(call);
 174	return;
 175
 176packet_loss_detected:
 177	change = rxrpc_cong_saw_nack;
 178	call->cong_mode = RXRPC_CALL_PACKET_LOSS;
 179	call->cong_dup_acks = 0;
 180	goto send_extra_data;
 181
 182send_extra_data:
 183	/* Send some previously unsent DATA if we have some to advance the ACK
 184	 * state.
 185	 */
 186	if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 187	    RXRPC_TX_ANNO_LAST ||
 188	    summary->nr_acks != call->tx_top - call->tx_hard_ack) {
 189		call->cong_extra++;
 190		wake_up(&call->waitq);
 191	}
 192	goto out_no_clear_ca;
 193}
 194
 195/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 196 * Apply a hard ACK by advancing the Tx window.
 197 */
 198static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
 199				   struct rxrpc_ack_summary *summary)
 200{
 201	struct sk_buff *skb, *list = NULL;
 202	bool rot_last = false;
 203	int ix;
 204	u8 annotation;
 205
 206	if (call->acks_lowest_nak == call->tx_hard_ack) {
 207		call->acks_lowest_nak = to;
 208	} else if (before_eq(call->acks_lowest_nak, to)) {
 209		summary->new_low_nack = true;
 210		call->acks_lowest_nak = to;
 211	}
 212
 213	spin_lock(&call->lock);
 214
 215	while (before(call->tx_hard_ack, to)) {
 216		call->tx_hard_ack++;
 217		ix = call->tx_hard_ack & RXRPC_RXTX_BUFF_MASK;
 218		skb = call->rxtx_buffer[ix];
 219		annotation = call->rxtx_annotations[ix];
 220		rxrpc_see_skb(skb, rxrpc_skb_rotated);
 221		call->rxtx_buffer[ix] = NULL;
 222		call->rxtx_annotations[ix] = 0;
 223		skb->next = list;
 224		list = skb;
 225
 226		if (annotation & RXRPC_TX_ANNO_LAST) {
 227			set_bit(RXRPC_CALL_TX_LAST, &call->flags);
 228			rot_last = true;
 229		}
 230		if ((annotation & RXRPC_TX_ANNO_MASK) != RXRPC_TX_ANNO_ACK)
 231			summary->nr_rot_new_acks++;
 232	}
 233
 234	spin_unlock(&call->lock);
 235
 236	trace_rxrpc_transmit(call, (rot_last ?
 237				    rxrpc_transmit_rotate_last :
 238				    rxrpc_transmit_rotate));
 239	wake_up(&call->waitq);
 240
 241	while (list) {
 242		skb = list;
 243		list = skb->next;
 244		skb_mark_not_on_list(skb);
 245		rxrpc_free_skb(skb, rxrpc_skb_freed);
 246	}
 247
 248	return rot_last;
 249}
 250
 251/*
 252 * End the transmission phase of a call.
 253 *
 254 * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
 255 * or a final ACK packet.
 256 */
 257static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
 258			       const char *abort_why)
 259{
 260	unsigned int state;
 261
 262	ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
 263
 264	write_lock(&call->state_lock);
 265
 266	state = call->state;
 267	switch (state) {
 268	case RXRPC_CALL_CLIENT_SEND_REQUEST:
 269	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 270		if (reply_begun)
 271			call->state = state = RXRPC_CALL_CLIENT_RECV_REPLY;
 272		else
 273			call->state = state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
 274		break;
 275
 276	case RXRPC_CALL_SERVER_AWAIT_ACK:
 277		__rxrpc_call_completed(call);
 
 278		state = call->state;
 279		break;
 280
 281	default:
 282		goto bad_state;
 283	}
 284
 285	write_unlock(&call->state_lock);
 286	if (state == RXRPC_CALL_CLIENT_AWAIT_REPLY)
 287		trace_rxrpc_transmit(call, rxrpc_transmit_await_reply);
 288	else
 289		trace_rxrpc_transmit(call, rxrpc_transmit_end);
 290	_leave(" = ok");
 291	return true;
 292
 293bad_state:
 294	write_unlock(&call->state_lock);
 295	kdebug("end_tx %s", rxrpc_call_states[call->state]);
 296	rxrpc_proto_abort(abort_why, call, call->tx_top);
 297	return false;
 298}
 299
 300/*
 301 * Begin the reply reception phase of a call.
 302 */
 303static bool rxrpc_receiving_reply(struct rxrpc_call *call)
 304{
 305	struct rxrpc_ack_summary summary = { 0 };
 306	unsigned long now, timo;
 307	rxrpc_seq_t top = READ_ONCE(call->tx_top);
 308
 309	if (call->ackr_reason) {
 310		spin_lock_bh(&call->lock);
 311		call->ackr_reason = 0;
 312		spin_unlock_bh(&call->lock);
 313		now = jiffies;
 314		timo = now + MAX_JIFFY_OFFSET;
 315		WRITE_ONCE(call->resend_at, timo);
 316		WRITE_ONCE(call->ack_at, timo);
 317		trace_rxrpc_timer(call, rxrpc_timer_init_for_reply, now);
 318	}
 319
 320	if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
 321		if (!rxrpc_rotate_tx_window(call, top, &summary)) {
 322			rxrpc_proto_abort("TXL", call, top);
 323			return false;
 324		}
 325	}
 326	if (!rxrpc_end_tx_phase(call, true, "ETD"))
 327		return false;
 328	call->tx_phase = false;
 329	return true;
 330}
 331
 332/*
 333 * Scan a data packet to validate its structure and to work out how many
 334 * subpackets it contains.
 335 *
 336 * A jumbo packet is a collection of consecutive packets glued together with
 337 * little headers between that indicate how to change the initial header for
 338 * each subpacket.
 339 *
 340 * RXRPC_JUMBO_PACKET must be set on all but the last subpacket - and all but
 341 * the last are RXRPC_JUMBO_DATALEN in size.  The last subpacket may be of any
 342 * size.
 343 */
 344static bool rxrpc_validate_data(struct sk_buff *skb)
 345{
 346	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 347	unsigned int offset = sizeof(struct rxrpc_wire_header);
 348	unsigned int len = skb->len;
 349	u8 flags = sp->hdr.flags;
 350
 351	for (;;) {
 352		if (flags & RXRPC_REQUEST_ACK)
 353			__set_bit(sp->nr_subpackets, sp->rx_req_ack);
 354		sp->nr_subpackets++;
 355
 356		if (!(flags & RXRPC_JUMBO_PACKET))
 357			break;
 358
 359		if (len - offset < RXRPC_JUMBO_SUBPKTLEN)
 360			goto protocol_error;
 361		if (flags & RXRPC_LAST_PACKET)
 362			goto protocol_error;
 363		offset += RXRPC_JUMBO_DATALEN;
 364		if (skb_copy_bits(skb, offset, &flags, 1) < 0)
 365			goto protocol_error;
 366		offset += sizeof(struct rxrpc_jumbo_header);
 367	}
 368
 369	if (flags & RXRPC_LAST_PACKET)
 370		sp->rx_flags |= RXRPC_SKB_INCL_LAST;
 371	return true;
 372
 373protocol_error:
 374	return false;
 375}
 376
 377/*
 378 * Handle reception of a duplicate packet.
 379 *
 380 * We have to take care to avoid an attack here whereby we're given a series of
 381 * jumbograms, each with a sequence number one before the preceding one and
 382 * filled up to maximum UDP size.  If they never send us the first packet in
 383 * the sequence, they can cause us to have to hold on to around 2MiB of kernel
 384 * space until the call times out.
 385 *
 386 * We limit the space usage by only accepting three duplicate jumbo packets per
 387 * call.  After that, we tell the other side we're no longer accepting jumbos
 388 * (that information is encoded in the ACK packet).
 389 */
 390static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
 391				 bool is_jumbo, bool *_jumbo_bad)
 392{
 393	/* Discard normal packets that are duplicates. */
 394	if (is_jumbo)
 395		return;
 396
 397	/* Skip jumbo subpackets that are duplicates.  When we've had three or
 398	 * more partially duplicate jumbo packets, we refuse to take any more
 399	 * jumbos for this call.
 400	 */
 401	if (!*_jumbo_bad) {
 402		call->nr_jumbo_bad++;
 403		*_jumbo_bad = true;
 404	}
 405}
 406
 407/*
 408 * Process a DATA packet, adding the packet to the Rx ring.  The caller's
 409 * packet ref must be passed on or discarded.
 410 */
 411static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
 412{
 413	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 414	enum rxrpc_call_state state;
 415	unsigned int j, nr_subpackets;
 416	rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
 417	rxrpc_seq_t seq0 = sp->hdr.seq, hard_ack;
 418	bool immediate_ack = false, jumbo_bad = false;
 419	u8 ack = 0;
 420
 421	_enter("{%u,%u},{%u,%u}",
 422	       call->rx_hard_ack, call->rx_top, skb->len, seq0);
 423
 424	_proto("Rx DATA %%%u { #%u f=%02x n=%u }",
 425	       sp->hdr.serial, seq0, sp->hdr.flags, sp->nr_subpackets);
 426
 427	state = READ_ONCE(call->state);
 428	if (state >= RXRPC_CALL_COMPLETE) {
 429		rxrpc_free_skb(skb, rxrpc_skb_freed);
 430		return;
 431	}
 432
 433	if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST) {
 434		unsigned long timo = READ_ONCE(call->next_req_timo);
 435		unsigned long now, expect_req_by;
 436
 437		if (timo) {
 438			now = jiffies;
 439			expect_req_by = now + timo;
 440			WRITE_ONCE(call->expect_req_by, expect_req_by);
 441			rxrpc_reduce_call_timer(call, expect_req_by, now,
 442						rxrpc_timer_set_for_idle);
 443		}
 444	}
 445
 446	spin_lock(&call->input_lock);
 447
 448	/* Received data implicitly ACKs all of the request packets we sent
 449	 * when we're acting as a client.
 450	 */
 451	if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
 452	     state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
 453	    !rxrpc_receiving_reply(call))
 454		goto unlock;
 455
 456	call->ackr_prev_seq = seq0;
 457	hard_ack = READ_ONCE(call->rx_hard_ack);
 458
 459	nr_subpackets = sp->nr_subpackets;
 460	if (nr_subpackets > 1) {
 461		if (call->nr_jumbo_bad > 3) {
 462			ack = RXRPC_ACK_NOSPACE;
 463			ack_serial = serial;
 464			goto ack;
 465		}
 466	}
 467
 468	for (j = 0; j < nr_subpackets; j++) {
 469		rxrpc_serial_t serial = sp->hdr.serial + j;
 470		rxrpc_seq_t seq = seq0 + j;
 471		unsigned int ix = seq & RXRPC_RXTX_BUFF_MASK;
 472		bool terminal = (j == nr_subpackets - 1);
 473		bool last = terminal && (sp->rx_flags & RXRPC_SKB_INCL_LAST);
 474		u8 flags, annotation = j;
 475
 476		_proto("Rx DATA+%u %%%u { #%x t=%u l=%u }",
 477		     j, serial, seq, terminal, last);
 478
 479		if (last) {
 480			if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 481			    seq != call->rx_top) {
 482				rxrpc_proto_abort("LSN", call, seq);
 483				goto unlock;
 484			}
 485		} else {
 486			if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 487			    after_eq(seq, call->rx_top)) {
 488				rxrpc_proto_abort("LSA", call, seq);
 489				goto unlock;
 490			}
 491		}
 492
 493		flags = 0;
 494		if (last)
 495			flags |= RXRPC_LAST_PACKET;
 496		if (!terminal)
 497			flags |= RXRPC_JUMBO_PACKET;
 498		if (test_bit(j, sp->rx_req_ack))
 499			flags |= RXRPC_REQUEST_ACK;
 500		trace_rxrpc_rx_data(call->debug_id, seq, serial, flags, annotation);
 501
 502		if (before_eq(seq, hard_ack)) {
 503			ack = RXRPC_ACK_DUPLICATE;
 504			ack_serial = serial;
 505			continue;
 506		}
 507
 508		if (call->rxtx_buffer[ix]) {
 509			rxrpc_input_dup_data(call, seq, nr_subpackets > 1,
 510					     &jumbo_bad);
 511			if (ack != RXRPC_ACK_DUPLICATE) {
 512				ack = RXRPC_ACK_DUPLICATE;
 513				ack_serial = serial;
 514			}
 515			immediate_ack = true;
 516			continue;
 517		}
 518
 519		if (after(seq, hard_ack + call->rx_winsize)) {
 520			ack = RXRPC_ACK_EXCEEDS_WINDOW;
 521			ack_serial = serial;
 522			if (flags & RXRPC_JUMBO_PACKET) {
 523				if (!jumbo_bad) {
 524					call->nr_jumbo_bad++;
 525					jumbo_bad = true;
 526				}
 527			}
 528
 529			goto ack;
 530		}
 531
 532		if (flags & RXRPC_REQUEST_ACK && !ack) {
 533			ack = RXRPC_ACK_REQUESTED;
 534			ack_serial = serial;
 535		}
 536
 537		/* Queue the packet.  We use a couple of memory barriers here as need
 538		 * to make sure that rx_top is perceived to be set after the buffer
 539		 * pointer and that the buffer pointer is set after the annotation and
 540		 * the skb data.
 541		 *
 542		 * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
 543		 * and also rxrpc_fill_out_ack().
 544		 */
 545		if (!terminal)
 546			rxrpc_get_skb(skb, rxrpc_skb_got);
 547		call->rxtx_annotations[ix] = annotation;
 548		smp_wmb();
 549		call->rxtx_buffer[ix] = skb;
 550		if (after(seq, call->rx_top)) {
 551			smp_store_release(&call->rx_top, seq);
 552		} else if (before(seq, call->rx_top)) {
 553			/* Send an immediate ACK if we fill in a hole */
 554			if (!ack) {
 555				ack = RXRPC_ACK_DELAY;
 556				ack_serial = serial;
 557			}
 558			immediate_ack = true;
 559		}
 560
 561		if (terminal) {
 562			/* From this point on, we're not allowed to touch the
 563			 * packet any longer as its ref now belongs to the Rx
 564			 * ring.
 565			 */
 566			skb = NULL;
 567			sp = NULL;
 568		}
 569
 570		if (last) {
 571			set_bit(RXRPC_CALL_RX_LAST, &call->flags);
 572			if (!ack) {
 573				ack = RXRPC_ACK_DELAY;
 574				ack_serial = serial;
 575			}
 576			trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
 577		} else {
 578			trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
 579		}
 580
 581		if (after_eq(seq, call->rx_expect_next)) {
 582			if (after(seq, call->rx_expect_next)) {
 583				_net("OOS %u > %u", seq, call->rx_expect_next);
 584				ack = RXRPC_ACK_OUT_OF_SEQUENCE;
 585				ack_serial = serial;
 586			}
 587			call->rx_expect_next = seq + 1;
 588		}
 589	}
 590
 591ack:
 592	if (ack)
 593		rxrpc_propose_ACK(call, ack, ack_serial,
 594				  immediate_ack, true,
 595				  rxrpc_propose_ack_input_data);
 596	else
 597		rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial,
 598				  false, true,
 599				  rxrpc_propose_ack_input_data);
 600
 601	trace_rxrpc_notify_socket(call->debug_id, serial);
 602	rxrpc_notify_socket(call);
 
 
 603
 604unlock:
 605	spin_unlock(&call->input_lock);
 606	rxrpc_free_skb(skb, rxrpc_skb_freed);
 607	_leave(" [queued]");
 608}
 609
 610/*
 611 * See if there's a cached RTT probe to complete.
 612 */
 613static void rxrpc_complete_rtt_probe(struct rxrpc_call *call,
 614				     ktime_t resp_time,
 615				     rxrpc_serial_t acked_serial,
 616				     rxrpc_serial_t ack_serial,
 617				     enum rxrpc_rtt_rx_trace type)
 618{
 619	rxrpc_serial_t orig_serial;
 620	unsigned long avail;
 621	ktime_t sent_at;
 622	bool matched = false;
 623	int i;
 624
 625	avail = READ_ONCE(call->rtt_avail);
 626	smp_rmb(); /* Read avail bits before accessing data. */
 627
 628	for (i = 0; i < ARRAY_SIZE(call->rtt_serial); i++) {
 629		if (!test_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &avail))
 
 630			continue;
 631
 632		sent_at = call->rtt_sent_at[i];
 633		orig_serial = call->rtt_serial[i];
 634
 635		if (orig_serial == acked_serial) {
 636			clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
 637			smp_mb(); /* Read data before setting avail bit */
 638			set_bit(i, &call->rtt_avail);
 639			if (type != rxrpc_rtt_rx_cancel)
 640				rxrpc_peer_add_rtt(call, type, i, acked_serial, ack_serial,
 641						   sent_at, resp_time);
 642			else
 643				trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_cancel, i,
 644						   orig_serial, acked_serial, 0, 0);
 645			matched = true;
 646		}
 647
 648		/* If a later serial is being acked, then mark this slot as
 649		 * being available.
 650		 */
 651		if (after(acked_serial, orig_serial)) {
 652			trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_obsolete, i,
 653					   orig_serial, acked_serial, 0, 0);
 654			clear_bit(i + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail);
 655			smp_wmb();
 656			set_bit(i, &call->rtt_avail);
 657		}
 658	}
 659
 660	if (!matched)
 661		trace_rxrpc_rtt_rx(call, rxrpc_rtt_rx_lost, 9, 0, acked_serial, 0, 0);
 
 
 
 662}
 663
 664/*
 665 * Process the response to a ping that we sent to find out if we lost an ACK.
 666 *
 667 * If we got back a ping response that indicates a lower tx_top than what we
 668 * had at the time of the ping transmission, we adjudge all the DATA packets
 669 * sent between the response tx_top and the ping-time tx_top to have been lost.
 670 */
 671static void rxrpc_input_check_for_lost_ack(struct rxrpc_call *call)
 672{
 673	rxrpc_seq_t top, bottom, seq;
 674	bool resend = false;
 675
 676	spin_lock_bh(&call->lock);
 677
 678	bottom = call->tx_hard_ack + 1;
 679	top = call->acks_lost_top;
 680	if (before(bottom, top)) {
 681		for (seq = bottom; before_eq(seq, top); seq++) {
 682			int ix = seq & RXRPC_RXTX_BUFF_MASK;
 683			u8 annotation = call->rxtx_annotations[ix];
 684			u8 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 685
 686			if (anno_type != RXRPC_TX_ANNO_UNACK)
 687				continue;
 688			annotation &= ~RXRPC_TX_ANNO_MASK;
 689			annotation |= RXRPC_TX_ANNO_RETRANS;
 690			call->rxtx_annotations[ix] = annotation;
 691			resend = true;
 692		}
 693	}
 694
 695	spin_unlock_bh(&call->lock);
 696
 697	if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 698		rxrpc_queue_call(call);
 699}
 700
 701/*
 702 * Process a ping response.
 703 */
 704static void rxrpc_input_ping_response(struct rxrpc_call *call,
 705				      ktime_t resp_time,
 706				      rxrpc_serial_t acked_serial,
 707				      rxrpc_serial_t ack_serial)
 708{
 709	if (acked_serial == call->acks_lost_ping)
 
 
 
 
 
 
 
 710		rxrpc_input_check_for_lost_ack(call);
 
 
 
 
 
 
 
 
 
 711}
 712
 713/*
 714 * Process the extra information that may be appended to an ACK packet
 715 */
 716static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 717				struct rxrpc_ackinfo *ackinfo)
 718{
 719	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 720	struct rxrpc_peer *peer;
 721	unsigned int mtu;
 722	bool wake = false;
 723	u32 rwind = ntohl(ackinfo->rwind);
 724
 725	_proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 726	       sp->hdr.serial,
 727	       ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
 728	       rwind, ntohl(ackinfo->jumbo_max));
 729
 730	if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
 731		rwind = RXRPC_RXTX_BUFF_SIZE - 1;
 732	if (call->tx_winsize != rwind) {
 
 
 733		if (rwind > call->tx_winsize)
 734			wake = true;
 735		trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake);
 
 736		call->tx_winsize = rwind;
 737	}
 738
 739	if (call->cong_ssthresh > rwind)
 740		call->cong_ssthresh = rwind;
 741
 742	mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
 743
 744	peer = call->peer;
 745	if (mtu < peer->maxdata) {
 746		spin_lock_bh(&peer->lock);
 747		peer->maxdata = mtu;
 748		peer->mtu = mtu + peer->hdrsize;
 749		spin_unlock_bh(&peer->lock);
 750		_net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 751	}
 752
 753	if (wake)
 754		wake_up(&call->waitq);
 755}
 756
 757/*
 758 * Process individual soft ACKs.
 759 *
 760 * Each ACK in the array corresponds to one packet and can be either an ACK or
 761 * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 762 * packets that lie beyond the end of the ACK list are scheduled for resend by
 763 * the timer on the basis that the peer might just not have processed them at
 764 * the time the ACK was sent.
 765 */
 766static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 767				  rxrpc_seq_t seq, int nr_acks,
 768				  struct rxrpc_ack_summary *summary)
 769{
 770	int ix;
 771	u8 annotation, anno_type;
 772
 773	for (; nr_acks > 0; nr_acks--, seq++) {
 774		ix = seq & RXRPC_RXTX_BUFF_MASK;
 775		annotation = call->rxtx_annotations[ix];
 776		anno_type = annotation & RXRPC_TX_ANNO_MASK;
 777		annotation &= ~RXRPC_TX_ANNO_MASK;
 778		switch (*acks++) {
 779		case RXRPC_ACK_TYPE_ACK:
 780			summary->nr_acks++;
 781			if (anno_type == RXRPC_TX_ANNO_ACK)
 782				continue;
 783			summary->nr_new_acks++;
 784			call->rxtx_annotations[ix] =
 785				RXRPC_TX_ANNO_ACK | annotation;
 786			break;
 787		case RXRPC_ACK_TYPE_NACK:
 788			if (!summary->nr_nacks &&
 789			    call->acks_lowest_nak != seq) {
 790				call->acks_lowest_nak = seq;
 791				summary->new_low_nack = true;
 792			}
 793			summary->nr_nacks++;
 794			if (anno_type == RXRPC_TX_ANNO_NAK)
 795				continue;
 796			summary->nr_new_nacks++;
 797			if (anno_type == RXRPC_TX_ANNO_RETRANS)
 798				continue;
 799			call->rxtx_annotations[ix] =
 800				RXRPC_TX_ANNO_NAK | annotation;
 801			break;
 802		default:
 803			return rxrpc_proto_abort("SFT", call, 0);
 804		}
 805	}
 806}
 807
 808/*
 809 * Return true if the ACK is valid - ie. it doesn't appear to have regressed
 810 * with respect to the ack state conveyed by preceding ACKs.
 811 */
 812static bool rxrpc_is_ack_valid(struct rxrpc_call *call,
 813			       rxrpc_seq_t first_pkt, rxrpc_seq_t prev_pkt)
 814{
 815	rxrpc_seq_t base = READ_ONCE(call->ackr_first_seq);
 816
 817	if (after(first_pkt, base))
 818		return true; /* The window advanced */
 819
 820	if (before(first_pkt, base))
 821		return false; /* firstPacket regressed */
 822
 823	if (after_eq(prev_pkt, call->ackr_prev_seq))
 824		return true; /* previousPacket hasn't regressed. */
 825
 826	/* Some rx implementations put a serial number in previousPacket. */
 827	if (after_eq(prev_pkt, base + call->tx_winsize))
 828		return false;
 829	return true;
 830}
 831
 832/*
 833 * Process an ACK packet.
 834 *
 835 * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 836 * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 837 *
 838 * A hard-ACK means that a packet has been processed and may be discarded; a
 839 * soft-ACK means that the packet may be discarded and retransmission
 840 * requested.  A phase is complete when all packets are hard-ACK'd.
 841 */
 842static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 843{
 844	struct rxrpc_ack_summary summary = { 0 };
 845	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 846	union {
 847		struct rxrpc_ackpacket ack;
 848		struct rxrpc_ackinfo info;
 849		u8 acks[RXRPC_MAXACKS];
 850	} buf;
 851	rxrpc_serial_t ack_serial, acked_serial;
 852	rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
 853	int nr_acks, offset, ioffset;
 854
 855	_enter("");
 856
 857	offset = sizeof(struct rxrpc_wire_header);
 858	if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
 859		_debug("extraction failure");
 860		return rxrpc_proto_abort("XAK", call, 0);
 861	}
 862	offset += sizeof(buf.ack);
 863
 864	ack_serial = sp->hdr.serial;
 865	acked_serial = ntohl(buf.ack.serial);
 866	first_soft_ack = ntohl(buf.ack.firstPacket);
 867	prev_pkt = ntohl(buf.ack.previousPacket);
 868	hard_ack = first_soft_ack - 1;
 869	nr_acks = buf.ack.nAcks;
 870	summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
 871			      buf.ack.reason : RXRPC_ACK__INVALID);
 872
 873	trace_rxrpc_rx_ack(call, ack_serial, acked_serial,
 874			   first_soft_ack, prev_pkt,
 875			   summary.ack_reason, nr_acks);
 876
 877	switch (buf.ack.reason) {
 878	case RXRPC_ACK_PING_RESPONSE:
 879		rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
 880					  ack_serial);
 881		rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
 882					 rxrpc_rtt_rx_ping_response);
 883		break;
 884	case RXRPC_ACK_REQUESTED:
 885		rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
 886					 rxrpc_rtt_rx_requested_ack);
 887		break;
 888	default:
 889		if (acked_serial != 0)
 890			rxrpc_complete_rtt_probe(call, skb->tstamp, acked_serial, ack_serial,
 891						 rxrpc_rtt_rx_cancel);
 892		break;
 893	}
 894
 895	if (buf.ack.reason == RXRPC_ACK_PING) {
 896		_proto("Rx ACK %%%u PING Request", ack_serial);
 897		rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 898				  ack_serial, true, true,
 899				  rxrpc_propose_ack_respond_to_ping);
 900	} else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 901		rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 902				  ack_serial, true, true,
 903				  rxrpc_propose_ack_respond_to_ack);
 904	}
 905
 906	/* Discard any out-of-order or duplicate ACKs (outside lock). */
 907	if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
 908		trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
 909					   first_soft_ack, call->ackr_first_seq,
 910					   prev_pkt, call->ackr_prev_seq);
 911		return;
 912	}
 913
 914	buf.info.rxMTU = 0;
 915	ioffset = offset + nr_acks + 3;
 916	if (skb->len >= ioffset + sizeof(buf.info) &&
 917	    skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
 918		return rxrpc_proto_abort("XAI", call, 0);
 919
 920	spin_lock(&call->input_lock);
 921
 922	/* Discard any out-of-order or duplicate ACKs (inside lock). */
 923	if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
 924		trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
 925					   first_soft_ack, call->ackr_first_seq,
 926					   prev_pkt, call->ackr_prev_seq);
 927		goto out;
 928	}
 929	call->acks_latest_ts = skb->tstamp;
 
 930
 931	call->ackr_first_seq = first_soft_ack;
 932	call->ackr_prev_seq = prev_pkt;
 933
 934	/* Parse rwind and mtu sizes if provided. */
 935	if (buf.info.rxMTU)
 936		rxrpc_input_ackinfo(call, skb, &buf.info);
 937
 938	if (first_soft_ack == 0) {
 939		rxrpc_proto_abort("AK0", call, 0);
 940		goto out;
 941	}
 942
 943	/* Ignore ACKs unless we are or have just been transmitting. */
 944	switch (READ_ONCE(call->state)) {
 945	case RXRPC_CALL_CLIENT_SEND_REQUEST:
 946	case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 947	case RXRPC_CALL_SERVER_SEND_REPLY:
 948	case RXRPC_CALL_SERVER_AWAIT_ACK:
 949		break;
 950	default:
 951		goto out;
 952	}
 953
 954	if (before(hard_ack, call->tx_hard_ack) ||
 955	    after(hard_ack, call->tx_top)) {
 956		rxrpc_proto_abort("AKW", call, 0);
 957		goto out;
 958	}
 959	if (nr_acks > call->tx_top - hard_ack) {
 960		rxrpc_proto_abort("AKN", call, 0);
 961		goto out;
 962	}
 963
 964	if (after(hard_ack, call->tx_hard_ack)) {
 965		if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
 966			rxrpc_end_tx_phase(call, false, "ETA");
 967			goto out;
 968		}
 969	}
 970
 971	if (nr_acks > 0) {
 972		if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0) {
 973			rxrpc_proto_abort("XSA", call, 0);
 974			goto out;
 975		}
 976		rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
 977				      &summary);
 978	}
 979
 980	if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 981	    RXRPC_TX_ANNO_LAST &&
 982	    summary.nr_acks == call->tx_top - hard_ack &&
 983	    rxrpc_is_client_call(call))
 984		rxrpc_propose_ACK(call, RXRPC_ACK_PING, ack_serial,
 985				  false, true,
 986				  rxrpc_propose_ack_ping_for_lost_reply);
 987
 988	rxrpc_congestion_management(call, skb, &summary, acked_serial);
 989out:
 990	spin_unlock(&call->input_lock);
 991}
 992
 993/*
 994 * Process an ACKALL packet.
 995 */
 996static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
 997{
 998	struct rxrpc_ack_summary summary = { 0 };
 999	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1000
1001	_proto("Rx ACKALL %%%u", sp->hdr.serial);
1002
1003	spin_lock(&call->input_lock);
1004
1005	if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
1006		rxrpc_end_tx_phase(call, false, "ETL");
1007
1008	spin_unlock(&call->input_lock);
1009}
1010
1011/*
1012 * Process an ABORT packet directed at a call.
1013 */
1014static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
1015{
1016	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1017	__be32 wtmp;
1018	u32 abort_code = RX_CALL_DEAD;
1019
1020	_enter("");
1021
1022	if (skb->len >= 4 &&
1023	    skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1024			  &wtmp, sizeof(wtmp)) >= 0)
1025		abort_code = ntohl(wtmp);
1026
1027	trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
1028
1029	_proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
1030
1031	rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
1032				  abort_code, -ECONNABORTED);
 
1033}
1034
1035/*
1036 * Process an incoming call packet.
1037 */
1038static void rxrpc_input_call_packet(struct rxrpc_call *call,
1039				    struct sk_buff *skb)
1040{
1041	struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1042	unsigned long timo;
1043
1044	_enter("%p,%p", call, skb);
1045
1046	timo = READ_ONCE(call->next_rx_timo);
1047	if (timo) {
1048		unsigned long now = jiffies, expect_rx_by;
1049
1050		expect_rx_by = now + timo;
1051		WRITE_ONCE(call->expect_rx_by, expect_rx_by);
1052		rxrpc_reduce_call_timer(call, expect_rx_by, now,
1053					rxrpc_timer_set_for_normal);
1054	}
1055
1056	switch (sp->hdr.type) {
1057	case RXRPC_PACKET_TYPE_DATA:
1058		rxrpc_input_data(call, skb);
1059		goto no_free;
1060
1061	case RXRPC_PACKET_TYPE_ACK:
1062		rxrpc_input_ack(call, skb);
1063		break;
1064
1065	case RXRPC_PACKET_TYPE_BUSY:
1066		_proto("Rx BUSY %%%u", sp->hdr.serial);
1067
1068		/* Just ignore BUSY packets from the server; the retry and
1069		 * lifespan timers will take care of business.  BUSY packets
1070		 * from the client don't make sense.
1071		 */
1072		break;
1073
1074	case RXRPC_PACKET_TYPE_ABORT:
1075		rxrpc_input_abort(call, skb);
1076		break;
1077
1078	case RXRPC_PACKET_TYPE_ACKALL:
1079		rxrpc_input_ackall(call, skb);
1080		break;
1081
1082	default:
1083		break;
1084	}
1085
1086	rxrpc_free_skb(skb, rxrpc_skb_freed);
1087no_free:
1088	_leave("");
1089}
1090
1091/*
1092 * Handle a new service call on a channel implicitly completing the preceding
1093 * call on that channel.  This does not apply to client conns.
1094 *
1095 * TODO: If callNumber > call_id + 1, renegotiate security.
1096 */
1097static void rxrpc_input_implicit_end_call(struct rxrpc_sock *rx,
1098					  struct rxrpc_connection *conn,
1099					  struct rxrpc_call *call)
1100{
1101	switch (READ_ONCE(call->state)) {
1102	case RXRPC_CALL_SERVER_AWAIT_ACK:
1103		rxrpc_call_completed(call);
1104		fallthrough;
1105	case RXRPC_CALL_COMPLETE:
1106		break;
1107	default:
1108		if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
1109			set_bit(RXRPC_CALL_EV_ABORT, &call->events);
1110			rxrpc_queue_call(call);
1111		}
1112		trace_rxrpc_improper_term(call);
1113		break;
1114	}
1115
1116	spin_lock(&rx->incoming_lock);
1117	__rxrpc_disconnect_call(conn, call);
1118	spin_unlock(&rx->incoming_lock);
 
1119}
1120
1121/*
1122 * post connection-level events to the connection
1123 * - this includes challenges, responses, some aborts and call terminal packet
1124 *   retransmission.
1125 */
1126static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
1127				      struct sk_buff *skb)
1128{
1129	_enter("%p,%p", conn, skb);
1130
1131	skb_queue_tail(&conn->rx_queue, skb);
1132	rxrpc_queue_conn(conn);
1133}
1134
1135/*
1136 * post endpoint-level events to the local endpoint
1137 * - this includes debug and version messages
1138 */
1139static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
1140				       struct sk_buff *skb)
1141{
1142	_enter("%p,%p", local, skb);
1143
1144	if (rxrpc_get_local_maybe(local)) {
1145		skb_queue_tail(&local->event_queue, skb);
1146		rxrpc_queue_local(local);
1147	} else {
1148		rxrpc_free_skb(skb, rxrpc_skb_freed);
1149	}
1150}
1151
1152/*
1153 * put a packet up for transport-level abort
1154 */
1155static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
1156{
1157	CHECK_SLAB_OKAY(&local->usage);
1158
1159	if (rxrpc_get_local_maybe(local)) {
1160		skb_queue_tail(&local->reject_queue, skb);
1161		rxrpc_queue_local(local);
1162	} else {
1163		rxrpc_free_skb(skb, rxrpc_skb_freed);
1164	}
1165}
1166
1167/*
1168 * Extract the wire header from a packet and translate the byte order.
1169 */
1170static noinline
1171int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
1172{
1173	struct rxrpc_wire_header whdr;
1174
1175	/* dig out the RxRPC connection details */
1176	if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0) {
1177		trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
1178				      tracepoint_string("bad_hdr"));
1179		return -EBADMSG;
1180	}
1181
1182	memset(sp, 0, sizeof(*sp));
1183	sp->hdr.epoch		= ntohl(whdr.epoch);
1184	sp->hdr.cid		= ntohl(whdr.cid);
1185	sp->hdr.callNumber	= ntohl(whdr.callNumber);
1186	sp->hdr.seq		= ntohl(whdr.seq);
1187	sp->hdr.serial		= ntohl(whdr.serial);
1188	sp->hdr.flags		= whdr.flags;
1189	sp->hdr.type		= whdr.type;
1190	sp->hdr.userStatus	= whdr.userStatus;
1191	sp->hdr.securityIndex	= whdr.securityIndex;
1192	sp->hdr._rsvd		= ntohs(whdr._rsvd);
1193	sp->hdr.serviceId	= ntohs(whdr.serviceId);
1194	return 0;
1195}
1196
1197/*
1198 * handle data received on the local endpoint
1199 * - may be called in interrupt context
1200 *
1201 * [!] Note that as this is called from the encap_rcv hook, the socket is not
1202 * held locked by the caller and nothing prevents sk_user_data on the UDP from
1203 * being cleared in the middle of processing this function.
1204 *
1205 * Called with the RCU read lock held from the IP layer via UDP.
1206 */
1207int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
1208{
1209	struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
1210	struct rxrpc_connection *conn;
1211	struct rxrpc_channel *chan;
1212	struct rxrpc_call *call = NULL;
1213	struct rxrpc_skb_priv *sp;
1214	struct rxrpc_peer *peer = NULL;
1215	struct rxrpc_sock *rx = NULL;
1216	unsigned int channel;
1217
1218	_enter("%p", udp_sk);
1219
1220	if (unlikely(!local)) {
1221		kfree_skb(skb);
1222		return 0;
1223	}
1224	if (skb->tstamp == 0)
1225		skb->tstamp = ktime_get_real();
1226
1227	rxrpc_new_skb(skb, rxrpc_skb_received);
1228
1229	skb_pull(skb, sizeof(struct udphdr));
1230
1231	/* The UDP protocol already released all skb resources;
1232	 * we are free to add our own data there.
1233	 */
1234	sp = rxrpc_skb(skb);
1235
1236	/* dig out the RxRPC connection details */
1237	if (rxrpc_extract_header(sp, skb) < 0)
1238		goto bad_message;
1239
1240	if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
1241		static int lose;
1242		if ((lose++ & 7) == 7) {
1243			trace_rxrpc_rx_lose(sp);
1244			rxrpc_free_skb(skb, rxrpc_skb_lost);
1245			return 0;
1246		}
1247	}
1248
1249	if (skb->tstamp == 0)
1250		skb->tstamp = ktime_get_real();
1251	trace_rxrpc_rx_packet(sp);
1252
1253	switch (sp->hdr.type) {
1254	case RXRPC_PACKET_TYPE_VERSION:
1255		if (rxrpc_to_client(sp))
1256			goto discard;
1257		rxrpc_post_packet_to_local(local, skb);
1258		goto out;
1259
1260	case RXRPC_PACKET_TYPE_BUSY:
1261		if (rxrpc_to_server(sp))
1262			goto discard;
1263		fallthrough;
1264	case RXRPC_PACKET_TYPE_ACK:
1265	case RXRPC_PACKET_TYPE_ACKALL:
1266		if (sp->hdr.callNumber == 0)
1267			goto bad_message;
1268		fallthrough;
1269	case RXRPC_PACKET_TYPE_ABORT:
1270		break;
1271
1272	case RXRPC_PACKET_TYPE_DATA:
1273		if (sp->hdr.callNumber == 0 ||
1274		    sp->hdr.seq == 0)
1275			goto bad_message;
1276		if (!rxrpc_validate_data(skb))
1277			goto bad_message;
1278
1279		/* Unshare the packet so that it can be modified for in-place
1280		 * decryption.
1281		 */
1282		if (sp->hdr.securityIndex != 0) {
1283			struct sk_buff *nskb = skb_unshare(skb, GFP_ATOMIC);
1284			if (!nskb) {
1285				rxrpc_eaten_skb(skb, rxrpc_skb_unshared_nomem);
1286				goto out;
1287			}
1288
1289			if (nskb != skb) {
1290				rxrpc_eaten_skb(skb, rxrpc_skb_received);
1291				skb = nskb;
1292				rxrpc_new_skb(skb, rxrpc_skb_unshared);
1293				sp = rxrpc_skb(skb);
1294			}
1295		}
1296		break;
1297
1298	case RXRPC_PACKET_TYPE_CHALLENGE:
1299		if (rxrpc_to_server(sp))
1300			goto discard;
1301		break;
1302	case RXRPC_PACKET_TYPE_RESPONSE:
1303		if (rxrpc_to_client(sp))
1304			goto discard;
1305		break;
1306
1307		/* Packet types 9-11 should just be ignored. */
1308	case RXRPC_PACKET_TYPE_PARAMS:
1309	case RXRPC_PACKET_TYPE_10:
1310	case RXRPC_PACKET_TYPE_11:
1311		goto discard;
1312
1313	default:
1314		_proto("Rx Bad Packet Type %u", sp->hdr.type);
1315		goto bad_message;
1316	}
1317
1318	if (sp->hdr.serviceId == 0)
1319		goto bad_message;
1320
1321	if (rxrpc_to_server(sp)) {
1322		/* Weed out packets to services we're not offering.  Packets
1323		 * that would begin a call are explicitly rejected and the rest
1324		 * are just discarded.
1325		 */
1326		rx = rcu_dereference(local->service);
1327		if (!rx || (sp->hdr.serviceId != rx->srx.srx_service &&
1328			    sp->hdr.serviceId != rx->second_service)) {
1329			if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
1330			    sp->hdr.seq == 1)
1331				goto unsupported_service;
1332			goto discard;
1333		}
1334	}
1335
1336	conn = rxrpc_find_connection_rcu(local, skb, &peer);
1337	if (conn) {
1338		if (sp->hdr.securityIndex != conn->security_ix)
1339			goto wrong_security;
1340
1341		if (sp->hdr.serviceId != conn->service_id) {
1342			int old_id;
1343
1344			if (!test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags))
1345				goto reupgrade;
1346			old_id = cmpxchg(&conn->service_id, conn->params.service_id,
1347					 sp->hdr.serviceId);
1348
1349			if (old_id != conn->params.service_id &&
1350			    old_id != sp->hdr.serviceId)
1351				goto reupgrade;
1352		}
1353
1354		if (sp->hdr.callNumber == 0) {
1355			/* Connection-level packet */
1356			_debug("CONN %p {%d}", conn, conn->debug_id);
1357			rxrpc_post_packet_to_conn(conn, skb);
1358			goto out;
1359		}
1360
1361		if ((int)sp->hdr.serial - (int)conn->hi_serial > 0)
1362			conn->hi_serial = sp->hdr.serial;
1363
1364		/* Call-bound packets are routed by connection channel. */
1365		channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1366		chan = &conn->channels[channel];
1367
1368		/* Ignore really old calls */
1369		if (sp->hdr.callNumber < chan->last_call)
1370			goto discard;
1371
1372		if (sp->hdr.callNumber == chan->last_call) {
1373			if (chan->call ||
1374			    sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
1375				goto discard;
1376
1377			/* For the previous service call, if completed
1378			 * successfully, we discard all further packets.
1379			 */
1380			if (rxrpc_conn_is_service(conn) &&
1381			    chan->last_type == RXRPC_PACKET_TYPE_ACK)
1382				goto discard;
1383
1384			/* But otherwise we need to retransmit the final packet
1385			 * from data cached in the connection record.
1386			 */
1387			if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
1388				trace_rxrpc_rx_data(chan->call_debug_id,
1389						    sp->hdr.seq,
1390						    sp->hdr.serial,
1391						    sp->hdr.flags, 0);
1392			rxrpc_post_packet_to_conn(conn, skb);
1393			goto out;
1394		}
1395
1396		call = rcu_dereference(chan->call);
1397
1398		if (sp->hdr.callNumber > chan->call_id) {
1399			if (rxrpc_to_client(sp))
1400				goto reject_packet;
1401			if (call)
1402				rxrpc_input_implicit_end_call(rx, conn, call);
1403			call = NULL;
1404		}
1405
1406		if (call) {
1407			if (sp->hdr.serviceId != call->service_id)
1408				call->service_id = sp->hdr.serviceId;
1409			if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
1410				call->rx_serial = sp->hdr.serial;
1411			if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
1412				set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
1413		}
1414	}
1415
1416	if (!call || atomic_read(&call->usage) == 0) {
1417		if (rxrpc_to_client(sp) ||
1418		    sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1419			goto bad_message;
1420		if (sp->hdr.seq != 1)
1421			goto discard;
1422		call = rxrpc_new_incoming_call(local, rx, skb);
1423		if (!call)
1424			goto reject_packet;
 
 
1425	}
1426
1427	/* Process a call packet; this either discards or passes on the ref
1428	 * elsewhere.
1429	 */
1430	rxrpc_input_call_packet(call, skb);
1431	goto out;
1432
1433discard:
1434	rxrpc_free_skb(skb, rxrpc_skb_freed);
1435out:
1436	trace_rxrpc_rx_done(0, 0);
1437	return 0;
1438
1439wrong_security:
1440	trace_rxrpc_abort(0, "SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1441			  RXKADINCONSISTENCY, EBADMSG);
1442	skb->priority = RXKADINCONSISTENCY;
1443	goto post_abort;
1444
1445unsupported_service:
1446	trace_rxrpc_abort(0, "INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1447			  RX_INVALID_OPERATION, EOPNOTSUPP);
1448	skb->priority = RX_INVALID_OPERATION;
1449	goto post_abort;
1450
1451reupgrade:
1452	trace_rxrpc_abort(0, "UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1453			  RX_PROTOCOL_ERROR, EBADMSG);
1454	goto protocol_error;
1455
1456bad_message:
1457	trace_rxrpc_abort(0, "BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1458			  RX_PROTOCOL_ERROR, EBADMSG);
1459protocol_error:
1460	skb->priority = RX_PROTOCOL_ERROR;
1461post_abort:
1462	skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
1463reject_packet:
1464	trace_rxrpc_rx_done(skb->mark, skb->priority);
1465	rxrpc_reject_packet(local, skb);
1466	_leave(" [badmsg]");
1467	return 0;
1468}