net/rxrpc/input.c

   1 /* RxRPC packet reception
   2  *
   3  * Copyright (C) 2007, 2016 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells ([email protected])
   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
  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  */
  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  */
 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  */
 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  */
 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  */
 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  */
 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  */
 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  */
 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         enum rxrpc_call_state state;
 424         unsigned int offset = sizeof(struct rxrpc_wire_header);
 425         unsigned int ix;
 426         rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
 427         rxrpc_seq_t seq = sp->hdr.seq, hard_ack;
 428         bool immediate_ack = false, jumbo_bad = false, queued;
 429         u16 len;
 430         u8 ack = 0, flags, annotation = 0;
 431
 432         _enter("{%u,%u},{%u,%u}",
 433                call->rx_hard_ack, call->rx_top, skb->len, seq);
 434
 435         _proto("Rx DATA %%%u { #%u f=%02x }",
 436                sp->hdr.serial, seq, sp->hdr.flags);
 437
 438         state = READ_ONCE(call->state);
 439         if (state >= RXRPC_CALL_COMPLETE)
 440                 return;
 441
 442         /* Received data implicitly ACKs all of the request packets we sent
 443          * when we're acting as a client.
 444          */
 445         if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
 446              state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
 447             !rxrpc_receiving_reply(call))
 448                 return;
 449
 450         call->ackr_prev_seq = seq;
 451
 452         hard_ack = READ_ONCE(call->rx_hard_ack);
 453         if (after(seq, hard_ack + call->rx_winsize)) {
 454                 ack = RXRPC_ACK_EXCEEDS_WINDOW;
 455                 ack_serial = serial;
 456                 goto ack;
 457         }
 458
 459         flags = sp->hdr.flags;
 460         if (flags & RXRPC_JUMBO_PACKET) {
 461                 if (call->nr_jumbo_bad > 3) {
 462                         ack = RXRPC_ACK_NOSPACE;
 463                         ack_serial = serial;
 464                         goto ack;
 465                 }
 466                 annotation = 1;
 467         }
 468
 469 next_subpacket:
 470         queued = false;
 471         ix = seq & RXRPC_RXTX_BUFF_MASK;
 472         len = skb->len;
 473         if (flags & RXRPC_JUMBO_PACKET)
 474                 len = RXRPC_JUMBO_DATALEN;
 475
 476         if (flags & RXRPC_LAST_PACKET) {
 477                 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 478                     seq != call->rx_top)
 479                         return rxrpc_proto_abort("LSN", call, seq);
 480         } else {
 481                 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 482                     after_eq(seq, call->rx_top))
 483                         return rxrpc_proto_abort("LSA", call, seq);
 484         }
 485
 486         trace_rxrpc_rx_data(call, seq, serial, flags, annotation);
 487         if (before_eq(seq, hard_ack)) {
 488                 ack = RXRPC_ACK_DUPLICATE;
 489                 ack_serial = serial;
 490                 goto skip;
 491         }
 492
 493         if (flags & RXRPC_REQUEST_ACK && !ack) {
 494                 ack = RXRPC_ACK_REQUESTED;
 495                 ack_serial = serial;
 496         }
 497
 498         if (call->rxtx_buffer[ix]) {
 499                 rxrpc_input_dup_data(call, seq, annotation, &jumbo_bad);
 500                 if (ack != RXRPC_ACK_DUPLICATE) {
 501                         ack = RXRPC_ACK_DUPLICATE;
 502                         ack_serial = serial;
 503                 }
 504                 immediate_ack = true;
 505                 goto skip;
 506         }
 507
 508         /* Queue the packet.  We use a couple of memory barriers here as need
 509          * to make sure that rx_top is perceived to be set after the buffer
 510          * pointer and that the buffer pointer is set after the annotation and
 511          * the skb data.
 512          *
 513          * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
 514          * and also rxrpc_fill_out_ack().
 515          */
 516         rxrpc_get_skb(skb, rxrpc_skb_rx_got);
 517         call->rxtx_annotations[ix] = annotation;
 518         smp_wmb();
 519         call->rxtx_buffer[ix] = skb;
 520         if (after(seq, call->rx_top)) {
 521                 smp_store_release(&call->rx_top, seq);
 522         } else if (before(seq, call->rx_top)) {
 523                 /* Send an immediate ACK if we fill in a hole */
 524                 if (!ack) {
 525                         ack = RXRPC_ACK_DELAY;
 526                         ack_serial = serial;
 527                 }
 528                 immediate_ack = true;
 529         }
 530         if (flags & RXRPC_LAST_PACKET) {
 531                 set_bit(RXRPC_CALL_RX_LAST, &call->flags);
 532                 trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
 533         } else {
 534                 trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
 535         }
 536         queued = true;
 537
 538         if (after_eq(seq, call->rx_expect_next)) {
 539                 if (after(seq, call->rx_expect_next)) {
 540                         _net("OOS %u > %u", seq, call->rx_expect_next);
 541                         ack = RXRPC_ACK_OUT_OF_SEQUENCE;
 542                         ack_serial = serial;
 543                 }
 544                 call->rx_expect_next = seq + 1;
 545         }
 546
 547 skip:
 548         offset += len;
 549         if (flags & RXRPC_JUMBO_PACKET) {
 550                 if (skb_copy_bits(skb, offset, &flags, 1) < 0)
 551                         return rxrpc_proto_abort("XJF", call, seq);
 552                 offset += sizeof(struct rxrpc_jumbo_header);
 553                 seq++;
 554                 serial++;
 555                 annotation++;
 556                 if (flags & RXRPC_JUMBO_PACKET)
 557                         annotation |= RXRPC_RX_ANNO_JLAST;
 558                 if (after(seq, hard_ack + call->rx_winsize)) {
 559                         ack = RXRPC_ACK_EXCEEDS_WINDOW;
 560                         ack_serial = serial;
 561                         if (!jumbo_bad) {
 562                                 call->nr_jumbo_bad++;
 563                                 jumbo_bad = true;
 564                         }
 565                         goto ack;
 566                 }
 567
 568                 _proto("Rx DATA Jumbo %%%u", serial);
 569                 goto next_subpacket;
 570         }
 571
 572         if (queued && flags & RXRPC_LAST_PACKET && !ack) {
 573                 ack = RXRPC_ACK_DELAY;
 574                 ack_serial = serial;
 575         }
 576
 577 ack:
 578         if (ack)
 579                 rxrpc_propose_ACK(call, ack, skew, ack_serial,
 580                                   immediate_ack, true,
 581                                   rxrpc_propose_ack_input_data);
 582
 583         if (sp->hdr.seq == READ_ONCE(call->rx_hard_ack) + 1)
 584                 rxrpc_notify_socket(call);
 585         _leave(" [queued]");
 586 }
 587
 588 /*
 589  * Process a requested ACK.
 590  */
 591 static void rxrpc_input_requested_ack(struct rxrpc_call *call,
 592                                       ktime_t resp_time,
 593                                       rxrpc_serial_t orig_serial,
 594                                       rxrpc_serial_t ack_serial)
 595 {
 596         struct rxrpc_skb_priv *sp;
 597         struct sk_buff *skb;
 598         ktime_t sent_at;
 599         int ix;
 600
 601         for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
 602                 skb = call->rxtx_buffer[ix];
 603                 if (!skb)
 604                         continue;
 605
 606                 sp = rxrpc_skb(skb);
 607                 if (sp->hdr.serial != orig_serial)
 608                         continue;
 609                 smp_rmb();
 610                 sent_at = skb->tstamp;
 611                 goto found;
 612         }
 613         return;
 614
 615 found:
 616         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
 617                            orig_serial, ack_serial, sent_at, resp_time);
 618 }
 619
 620 /*
 621  * Process a ping response.
 622  */
 623 static void rxrpc_input_ping_response(struct rxrpc_call *call,
 624                                       ktime_t resp_time,
 625                                       rxrpc_serial_t orig_serial,
 626                                       rxrpc_serial_t ack_serial)
 627 {
 628         rxrpc_serial_t ping_serial;
 629         ktime_t ping_time;
 630
 631         ping_time = call->ping_time;
 632         smp_rmb();
 633         ping_serial = call->ping_serial;
 634
 635         if (!test_bit(RXRPC_CALL_PINGING, &call->flags) ||
 636             before(orig_serial, ping_serial))
 637                 return;
 638         clear_bit(RXRPC_CALL_PINGING, &call->flags);
 639         if (after(orig_serial, ping_serial))
 640                 return;
 641
 642         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
 643                            orig_serial, ack_serial, ping_time, resp_time);
 644 }
 645
 646 /*
 647  * Process the extra information that may be appended to an ACK packet
 648  */
 649 static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 650                                 struct rxrpc_ackinfo *ackinfo)
 651 {
 652         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 653         struct rxrpc_peer *peer;
 654         unsigned int mtu;
 655         bool wake = false;
 656         u32 rwind = ntohl(ackinfo->rwind);
 657
 658         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 659                sp->hdr.serial,
 660                ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
 661                rwind, ntohl(ackinfo->jumbo_max));
 662
 663         if (call->tx_winsize != rwind) {
 664                 if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
 665                         rwind = RXRPC_RXTX_BUFF_SIZE - 1;
 666                 if (rwind > call->tx_winsize)
 667                         wake = true;
 668                 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial,
 669                                             ntohl(ackinfo->rwind), wake);
 670                 call->tx_winsize = rwind;
 671         }
 672
 673         if (call->cong_ssthresh > rwind)
 674                 call->cong_ssthresh = rwind;
 675
 676         mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
 677
 678         peer = call->peer;
 679         if (mtu < peer->maxdata) {
 680                 spin_lock_bh(&peer->lock);
 681                 peer->maxdata = mtu;
 682                 peer->mtu = mtu + peer->hdrsize;
 683                 spin_unlock_bh(&peer->lock);
 684                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 685         }
 686
 687         if (wake)
 688                 wake_up(&call->waitq);
 689 }
 690
 691 /*
 692  * Process individual soft ACKs.
 693  *
 694  * Each ACK in the array corresponds to one packet and can be either an ACK or
 695  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 696  * packets that lie beyond the end of the ACK list are scheduled for resend by
 697  * the timer on the basis that the peer might just not have processed them at
 698  * the time the ACK was sent.
 699  */
 700 static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 701                                   rxrpc_seq_t seq, int nr_acks,
 702                                   struct rxrpc_ack_summary *summary)
 703 {
 704         int ix;
 705         u8 annotation, anno_type;
 706
 707         for (; nr_acks > 0; nr_acks--, seq++) {
 708                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 709                 annotation = call->rxtx_annotations[ix];
 710                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 711                 annotation &= ~RXRPC_TX_ANNO_MASK;
 712                 switch (*acks++) {
 713                 case RXRPC_ACK_TYPE_ACK:
 714                         summary->nr_acks++;
 715                         if (anno_type == RXRPC_TX_ANNO_ACK)
 716                                 continue;
 717                         summary->nr_new_acks++;
 718                         call->rxtx_annotations[ix] =
 719                                 RXRPC_TX_ANNO_ACK | annotation;
 720                         break;
 721                 case RXRPC_ACK_TYPE_NACK:
 722                         if (!summary->nr_nacks &&
 723                             call->acks_lowest_nak != seq) {
 724                                 call->acks_lowest_nak = seq;
 725                                 summary->new_low_nack = true;
 726                         }
 727                         summary->nr_nacks++;
 728                         if (anno_type == RXRPC_TX_ANNO_NAK)
 729                                 continue;
 730                         summary->nr_new_nacks++;
 731                         if (anno_type == RXRPC_TX_ANNO_RETRANS)
 732                                 continue;
 733                         call->rxtx_annotations[ix] =
 734                                 RXRPC_TX_ANNO_NAK | annotation;
 735                         break;
 736                 default:
 737                         return rxrpc_proto_abort("SFT", call, 0);
 738                 }
 739         }
 740 }
 741
 742 /*
 743  * Process an ACK packet.
 744  *
 745  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 746  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 747  *
 748  * A hard-ACK means that a packet has been processed and may be discarded; a
 749  * soft-ACK means that the packet may be discarded and retransmission
 750  * requested.  A phase is complete when all packets are hard-ACK'd.
 751  */
 752 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
 753                             u16 skew)
 754 {
 755         struct rxrpc_ack_summary summary = { 0 };
 756         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 757         union {
 758                 struct rxrpc_ackpacket ack;
 759                 struct rxrpc_ackinfo info;
 760                 u8 acks[RXRPC_MAXACKS];
 761         } buf;
 762         rxrpc_serial_t acked_serial;
 763         rxrpc_seq_t first_soft_ack, hard_ack;
 764         int nr_acks, offset, ioffset;
 765
 766         _enter("");
 767
 768         offset = sizeof(struct rxrpc_wire_header);
 769         if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
 770                 _debug("extraction failure");
 771                 return rxrpc_proto_abort("XAK", call, 0);
 772         }
 773         offset += sizeof(buf.ack);
 774
 775         acked_serial = ntohl(buf.ack.serial);
 776         first_soft_ack = ntohl(buf.ack.firstPacket);
 777         hard_ack = first_soft_ack - 1;
 778         nr_acks = buf.ack.nAcks;
 779         summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
 780                               buf.ack.reason : RXRPC_ACK__INVALID);
 781
 782         trace_rxrpc_rx_ack(call, sp->hdr.serial, acked_serial,
 783                            first_soft_ack, ntohl(buf.ack.previousPacket),
 784                            summary.ack_reason, nr_acks);
 785
 786         if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
 787                 rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
 788                                           sp->hdr.serial);
 789         if (buf.ack.reason == RXRPC_ACK_REQUESTED)
 790                 rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
 791                                           sp->hdr.serial);
 792
 793         if (buf.ack.reason == RXRPC_ACK_PING) {
 794                 _proto("Rx ACK %%%u PING Request", sp->hdr.serial);
 795                 rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 796                                   skew, sp->hdr.serial, true, true,
 797                                   rxrpc_propose_ack_respond_to_ping);
 798         } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 799                 rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 800                                   skew, sp->hdr.serial, true, true,
 801                                   rxrpc_propose_ack_respond_to_ack);
 802         }
 803
 804         ioffset = offset + nr_acks + 3;
 805         if (skb->len >= ioffset + sizeof(buf.info)) {
 806                 if (skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
 807                         return rxrpc_proto_abort("XAI", call, 0);
 808                 rxrpc_input_ackinfo(call, skb, &buf.info);
 809         }
 810
 811         if (first_soft_ack == 0)
 812                 return rxrpc_proto_abort("AK0", call, 0);
 813
 814         /* Ignore ACKs unless we are or have just been transmitting. */
 815         switch (READ_ONCE(call->state)) {
 816         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 817         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 818         case RXRPC_CALL_SERVER_SEND_REPLY:
 819         case RXRPC_CALL_SERVER_AWAIT_ACK:
 820                 break;
 821         default:
 822                 return;
 823         }
 824
 825         /* Discard any out-of-order or duplicate ACKs. */
 826         if (before_eq(sp->hdr.serial, call->acks_latest)) {
 827                 _debug("discard ACK %d <= %d",
 828                        sp->hdr.serial, call->acks_latest);
 829                 return;
 830         }
 831         call->acks_latest_ts = skb->tstamp;
 832         call->acks_latest = sp->hdr.serial;
 833
 834         if (before(hard_ack, call->tx_hard_ack) ||
 835             after(hard_ack, call->tx_top))
 836                 return rxrpc_proto_abort("AKW", call, 0);
 837         if (nr_acks > call->tx_top - hard_ack)
 838                 return rxrpc_proto_abort("AKN", call, 0);
 839
 840         if (after(hard_ack, call->tx_hard_ack))
 841                 rxrpc_rotate_tx_window(call, hard_ack, &summary);
 842
 843         if (nr_acks > 0) {
 844                 if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0)
 845                         return rxrpc_proto_abort("XSA", call, 0);
 846                 rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
 847                                       &summary);
 848         }
 849
 850         if (test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
 851                 rxrpc_end_tx_phase(call, false, "ETA");
 852                 return;
 853         }
 854
 855         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 856             RXRPC_TX_ANNO_LAST &&
 857             summary.nr_acks == call->tx_top - hard_ack &&
 858             rxrpc_is_client_call(call))
 859                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
 860                                   false, true,
 861                                   rxrpc_propose_ack_ping_for_lost_reply);
 862
 863         return rxrpc_congestion_management(call, skb, &summary, acked_serial);
 864 }
 865
 866 /*
 867  * Process an ACKALL packet.
 868  */
 869 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
 870 {
 871         struct rxrpc_ack_summary summary = { 0 };
 872         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 873
 874         _proto("Rx ACKALL %%%u", sp->hdr.serial);
 875
 876         rxrpc_rotate_tx_window(call, call->tx_top, &summary);
 877         if (test_bit(RXRPC_CALL_TX_LAST, &call->flags))
 878                 rxrpc_end_tx_phase(call, false, "ETL");
 879 }
 880
 881 /*
 882  * Process an ABORT packet directed at a call.
 883  */
 884 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
 885 {
 886         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 887         __be32 wtmp;
 888         u32 abort_code = RX_CALL_DEAD;
 889
 890         _enter("");
 891
 892         if (skb->len >= 4 &&
 893             skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
 894                           &wtmp, sizeof(wtmp)) >= 0)
 895                 abort_code = ntohl(wtmp);
 896
 897         trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
 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  */
 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                 break;
 944         }
 945
 946         _leave("");
 947 }
 948
 949 /*
 950  * Handle a new call on a channel implicitly completing the preceding call on
 951  * that channel.
 952  *
 953  * TODO: If callNumber > call_id + 1, renegotiate security.
 954  */
 955 static void rxrpc_input_implicit_end_call(struct rxrpc_connection *conn,
 956                                           struct rxrpc_call *call)
 957 {
 958         switch (READ_ONCE(call->state)) {
 959         case RXRPC_CALL_SERVER_AWAIT_ACK:
 960                 rxrpc_call_completed(call);
 961                 break;
 962         case RXRPC_CALL_COMPLETE:
 963                 break;
 964         default:
 965                 if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
 966                         set_bit(RXRPC_CALL_EV_ABORT, &call->events);
 967                         rxrpc_queue_call(call);
 968                 }
 969                 break;
 970         }
 971
 972         trace_rxrpc_improper_term(call);
 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  */
 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  */
 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  */
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
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                 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
1026                                       tracepoint_string("bad_hdr"));
1027                 return -EBADMSG;
1028         }
1029
1030         memset(sp, 0, sizeof(*sp));
1031         sp->hdr.epoch           = ntohl(whdr.epoch);
1032         sp->hdr.cid             = ntohl(whdr.cid);
1033         sp->hdr.callNumber      = ntohl(whdr.callNumber);
1034         sp->hdr.seq             = ntohl(whdr.seq);
1035         sp->hdr.serial          = ntohl(whdr.serial);
1036         sp->hdr.flags           = whdr.flags;
1037         sp->hdr.type            = whdr.type;
1038         sp->hdr.userStatus      = whdr.userStatus;
1039         sp->hdr.securityIndex   = whdr.securityIndex;
1040         sp->hdr._rsvd           = ntohs(whdr._rsvd);
1041         sp->hdr.serviceId       = ntohs(whdr.serviceId);
1042         return 0;
1043 }
1044
1045 /*
1046  * handle data received on the local endpoint
1047  * - may be called in interrupt context
1048  *
1049  * The socket is locked by the caller and this prevents the socket from being
1050  * shut down and the local endpoint from going away, thus sk_user_data will not
1051  * be cleared until this function returns.
1052  */
1053 void rxrpc_data_ready(struct sock *udp_sk)
1054 {
1055         struct rxrpc_connection *conn;
1056         struct rxrpc_channel *chan;
1057         struct rxrpc_call *call;
1058         struct rxrpc_skb_priv *sp;
1059         struct rxrpc_local *local = udp_sk->sk_user_data;
1060         struct sk_buff *skb;
1061         unsigned int channel;
1062         int ret, skew;
1063
1064         _enter("%p", udp_sk);
1065
1066         ASSERT(!irqs_disabled());
1067
1068         skb = skb_recv_udp(udp_sk, 0, 1, &ret);
1069         if (!skb) {
1070                 if (ret == -EAGAIN)
1071                         return;
1072                 _debug("UDP socket error %d", ret);
1073                 return;
1074         }
1075
1076         rxrpc_new_skb(skb, rxrpc_skb_rx_received);
1077
1078         _net("recv skb %p", skb);
1079
1080         /* we'll probably need to checksum it (didn't call sock_recvmsg) */
1081         if (skb_checksum_complete(skb)) {
1082                 rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1083                 __UDP_INC_STATS(&init_net, UDP_MIB_INERRORS, 0);
1084                 _leave(" [CSUM failed]");
1085                 return;
1086         }
1087
1088         __UDP_INC_STATS(&init_net, UDP_MIB_INDATAGRAMS, 0);
1089
1090         /* The UDP protocol already released all skb resources;
1091          * we are free to add our own data there.
1092          */
1093         sp = rxrpc_skb(skb);
1094
1095         /* dig out the RxRPC connection details */
1096         if (rxrpc_extract_header(sp, skb) < 0)
1097                 goto bad_message;
1098
1099         if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
1100                 static int lose;
1101                 if ((lose++ & 7) == 7) {
1102                         trace_rxrpc_rx_lose(sp);
1103                         rxrpc_lose_skb(skb, rxrpc_skb_rx_lost);
1104                         return;
1105                 }
1106         }
1107
1108         trace_rxrpc_rx_packet(sp);
1109
1110         _net("Rx RxRPC %s ep=%x call=%x:%x",
1111              sp->hdr.flags & RXRPC_CLIENT_INITIATED ? "ToServer" : "ToClient",
1112              sp->hdr.epoch, sp->hdr.cid, sp->hdr.callNumber);
1113
1114         if (sp->hdr.type >= RXRPC_N_PACKET_TYPES ||
1115             !((RXRPC_SUPPORTED_PACKET_TYPES >> sp->hdr.type) & 1)) {
1116                 _proto("Rx Bad Packet Type %u", sp->hdr.type);
1117                 goto bad_message;
1118         }
1119
1120         switch (sp->hdr.type) {
1121         case RXRPC_PACKET_TYPE_VERSION:
1122                 rxrpc_post_packet_to_local(local, skb);
1123                 goto out;
1124
1125         case RXRPC_PACKET_TYPE_BUSY:
1126                 if (sp->hdr.flags & RXRPC_CLIENT_INITIATED)
1127                         goto discard;
1128
1129         case RXRPC_PACKET_TYPE_DATA:
1130                 if (sp->hdr.callNumber == 0)
1131                         goto bad_message;
1132                 if (sp->hdr.flags & RXRPC_JUMBO_PACKET &&
1133                     !rxrpc_validate_jumbo(skb))
1134                         goto bad_message;
1135                 break;
1136         }
1137
1138         rcu_read_lock();
1139
1140         conn = rxrpc_find_connection_rcu(local, skb);
1141         if (conn) {
1142                 if (sp->hdr.securityIndex != conn->security_ix)
1143                         goto wrong_security;
1144
1145                 if (sp->hdr.serviceId != conn->service_id) {
1146                         if (!test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags) ||
1147                             conn->service_id != conn->params.service_id)
1148                                 goto reupgrade;
1149                         conn->service_id = sp->hdr.serviceId;
1150                 }
1151
1152                 if (sp->hdr.callNumber == 0) {
1153                         /* Connection-level packet */
1154                         _debug("CONN %p {%d}", conn, conn->debug_id);
1155                         rxrpc_post_packet_to_conn(conn, skb);
1156                         goto out_unlock;
1157                 }
1158
1159                 /* Note the serial number skew here */
1160                 skew = (int)sp->hdr.serial - (int)conn->hi_serial;
1161                 if (skew >= 0) {
1162                         if (skew > 0)
1163                                 conn->hi_serial = sp->hdr.serial;
1164                 } else {
1165                         skew = -skew;
1166                         skew = min(skew, 65535);
1167                 }
1168
1169                 /* Call-bound packets are routed by connection channel. */
1170                 channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1171                 chan = &conn->channels[channel];
1172
1173                 /* Ignore really old calls */
1174                 if (sp->hdr.callNumber < chan->last_call)
1175                         goto discard_unlock;
1176
1177                 if (sp->hdr.callNumber == chan->last_call) {
1178                         /* For the previous service call, if completed successfully, we
1179                          * discard all further packets.
1180                          */
1181                         if (rxrpc_conn_is_service(conn) &&
1182                             (chan->last_type == RXRPC_PACKET_TYPE_ACK ||
1183                              sp->hdr.type == RXRPC_PACKET_TYPE_ABORT))
1184                                 goto discard_unlock;
1185
1186                         /* But otherwise we need to retransmit the final packet from
1187                          * data cached in the connection record.
1188                          */
1189                         rxrpc_post_packet_to_conn(conn, skb);
1190                         goto out_unlock;
1191                 }
1192
1193                 call = rcu_dereference(chan->call);
1194
1195                 if (sp->hdr.callNumber > chan->call_id) {
1196                         if (!(sp->hdr.flags & RXRPC_CLIENT_INITIATED)) {
1197                                 rcu_read_unlock();
1198                                 goto reject_packet;
1199                         }
1200                         if (call)
1201                                 rxrpc_input_implicit_end_call(conn, call);
1202                         call = NULL;
1203                 }
1204
1205                 if (call && sp->hdr.serviceId != call->service_id)
1206                         call->service_id = sp->hdr.serviceId;
1207         } else {
1208                 skew = 0;
1209                 call = NULL;
1210         }
1211
1212         if (!call || atomic_read(&call->usage) == 0) {
1213                 if (!(sp->hdr.type & RXRPC_CLIENT_INITIATED) ||
1214                     sp->hdr.callNumber == 0 ||
1215                     sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1216                         goto bad_message_unlock;
1217                 if (sp->hdr.seq != 1)
1218                         goto discard_unlock;
1219                 call = rxrpc_new_incoming_call(local, conn, skb);
1220                 if (!call) {
1221                         rcu_read_unlock();
1222                         goto reject_packet;
1223                 }
1224                 rxrpc_send_ping(call, skb, skew);
1225                 mutex_unlock(&call->user_mutex);
1226         }
1227
1228         rxrpc_input_call_packet(call, skb, skew);
1229         goto discard_unlock;
1230
1231 discard_unlock:
1232         rcu_read_unlock();
1233 discard:
1234         rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1235 out:
1236         trace_rxrpc_rx_done(0, 0);
1237         return;
1238
1239 out_unlock:
1240         rcu_read_unlock();
1241         goto out;
1242
1243 wrong_security:
1244         rcu_read_unlock();
1245         trace_rxrpc_abort("SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1246                           RXKADINCONSISTENCY, EBADMSG);
1247         skb->priority = RXKADINCONSISTENCY;
1248         goto post_abort;
1249
1250 reupgrade:
1251         rcu_read_unlock();
1252         trace_rxrpc_abort("UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1253                           RX_PROTOCOL_ERROR, EBADMSG);
1254         goto protocol_error;
1255
1256 bad_message_unlock:
1257         rcu_read_unlock();
1258 bad_message:
1259         trace_rxrpc_abort("BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1260                           RX_PROTOCOL_ERROR, EBADMSG);
1261 protocol_error:
1262         skb->priority = RX_PROTOCOL_ERROR;
1263 post_abort:
1264         skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
1265 reject_packet:
1266         trace_rxrpc_rx_done(skb->mark, skb->priority);
1267         rxrpc_reject_packet(local, skb);
1268         _leave(" [badmsg]");
1269 }