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 (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/net.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/errqueue.h>
  18 #include <linux/udp.h>
  19 #include <linux/in.h>
  20 #include <linux/in6.h>
  21 #include <linux/icmp.h>
  22 #include <linux/gfp.h>
  23 #include <net/sock.h>
  24 #include <net/af_rxrpc.h>
  25 #include <net/ip.h>
  26 #include <net/udp.h>
  27 #include <net/net_namespace.h>
  28 #include "ar-internal.h"
  29
  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 bool 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         bool rot_last = false;
 224         int ix;
 225         u8 annotation;
 226
 227         if (call->acks_lowest_nak == call->tx_hard_ack) {
 228                 call->acks_lowest_nak = to;
 229         } else if (before_eq(call->acks_lowest_nak, to)) {
 230                 summary->new_low_nack = true;
 231                 call->acks_lowest_nak = to;
 232         }
 233
 234         spin_lock(&call->lock);
 235
 236         while (before(call->tx_hard_ack, to)) {
 237                 call->tx_hard_ack++;
 238                 ix = call->tx_hard_ack & RXRPC_RXTX_BUFF_MASK;
 239                 skb = call->rxtx_buffer[ix];
 240                 annotation = call->rxtx_annotations[ix];
 241                 rxrpc_see_skb(skb, rxrpc_skb_tx_rotated);
 242                 call->rxtx_buffer[ix] = NULL;
 243                 call->rxtx_annotations[ix] = 0;
 244                 skb->next = list;
 245                 list = skb;
 246
 247                 if (annotation & RXRPC_TX_ANNO_LAST) {
 248                         set_bit(RXRPC_CALL_TX_LAST, &call->flags);
 249                         rot_last = true;
 250                 }
 251                 if ((annotation & RXRPC_TX_ANNO_MASK) != RXRPC_TX_ANNO_ACK)
 252                         summary->nr_rot_new_acks++;
 253         }
 254
 255         spin_unlock(&call->lock);
 256
 257         trace_rxrpc_transmit(call, (rot_last ?
 258                                     rxrpc_transmit_rotate_last :
 259                                     rxrpc_transmit_rotate));
 260         wake_up(&call->waitq);
 261
 262         while (list) {
 263                 skb = list;
 264                 list = skb->next;
 265                 skb->next = NULL;
 266                 rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
 267         }
 268
 269         return rot_last;
 270 }
 271
 272 /*
 273  * End the transmission phase of a call.
 274  *
 275  * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
 276  * or a final ACK packet.
 277  */
 278 static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
 279                                const char *abort_why)
 280 {
 281
 282         ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
 283
 284         write_lock(&call->state_lock);
 285
 286         switch (call->state) {
 287         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 288         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 289                 if (reply_begun)
 290                         call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
 291                 else
 292                         call->state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
 293                 break;
 294
 295         case RXRPC_CALL_SERVER_AWAIT_ACK:
 296                 __rxrpc_call_completed(call);
 297                 rxrpc_notify_socket(call);
 298                 break;
 299
 300         default:
 301                 goto bad_state;
 302         }
 303
 304         write_unlock(&call->state_lock);
 305         if (call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY) {
 306                 rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, 0, 0, false, true,
 307                                   rxrpc_propose_ack_client_tx_end);
 308                 trace_rxrpc_transmit(call, rxrpc_transmit_await_reply);
 309         } else {
 310                 trace_rxrpc_transmit(call, rxrpc_transmit_end);
 311         }
 312         _leave(" = ok");
 313         return true;
 314
 315 bad_state:
 316         write_unlock(&call->state_lock);
 317         kdebug("end_tx %s", rxrpc_call_states[call->state]);
 318         rxrpc_proto_abort(abort_why, call, call->tx_top);
 319         return false;
 320 }
 321
 322 /*
 323  * Begin the reply reception phase of a call.
 324  */
 325 static bool rxrpc_receiving_reply(struct rxrpc_call *call)
 326 {
 327         struct rxrpc_ack_summary summary = { 0 };
 328         rxrpc_seq_t top = READ_ONCE(call->tx_top);
 329
 330         if (call->ackr_reason) {
 331                 spin_lock_bh(&call->lock);
 332                 call->ackr_reason = 0;
 333                 call->resend_at = call->expire_at;
 334                 call->ack_at = call->expire_at;
 335                 spin_unlock_bh(&call->lock);
 336                 rxrpc_set_timer(call, rxrpc_timer_init_for_reply,
 337                                 ktime_get_real());
 338         }
 339
 340         if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
 341                 if (!rxrpc_rotate_tx_window(call, top, &summary)) {
 342                         rxrpc_proto_abort("TXL", call, top);
 343                         return false;
 344                 }
 345         }
 346         if (!rxrpc_end_tx_phase(call, true, "ETD"))
 347                 return false;
 348         call->tx_phase = false;
 349         return true;
 350 }
 351
 352 /*
 353  * Scan a jumbo packet to validate its structure and to work out how many
 354  * subpackets it contains.
 355  *
 356  * A jumbo packet is a collection of consecutive packets glued together with
 357  * little headers between that indicate how to change the initial header for
 358  * each subpacket.
 359  *
 360  * RXRPC_JUMBO_PACKET must be set on all but the last subpacket - and all but
 361  * the last are RXRPC_JUMBO_DATALEN in size.  The last subpacket may be of any
 362  * size.
 363  */
 364 static bool rxrpc_validate_jumbo(struct sk_buff *skb)
 365 {
 366         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 367         unsigned int offset = sizeof(struct rxrpc_wire_header);
 368         unsigned int len = skb->len;
 369         int nr_jumbo = 1;
 370         u8 flags = sp->hdr.flags;
 371
 372         do {
 373                 nr_jumbo++;
 374                 if (len - offset < RXRPC_JUMBO_SUBPKTLEN)
 375                         goto protocol_error;
 376                 if (flags & RXRPC_LAST_PACKET)
 377                         goto protocol_error;
 378                 offset += RXRPC_JUMBO_DATALEN;
 379                 if (skb_copy_bits(skb, offset, &flags, 1) < 0)
 380                         goto protocol_error;
 381                 offset += sizeof(struct rxrpc_jumbo_header);
 382         } while (flags & RXRPC_JUMBO_PACKET);
 383
 384         sp->nr_jumbo = nr_jumbo;
 385         return true;
 386
 387 protocol_error:
 388         return false;
 389 }
 390
 391 /*
 392  * Handle reception of a duplicate packet.
 393  *
 394  * We have to take care to avoid an attack here whereby we're given a series of
 395  * jumbograms, each with a sequence number one before the preceding one and
 396  * filled up to maximum UDP size.  If they never send us the first packet in
 397  * the sequence, they can cause us to have to hold on to around 2MiB of kernel
 398  * space until the call times out.
 399  *
 400  * We limit the space usage by only accepting three duplicate jumbo packets per
 401  * call.  After that, we tell the other side we're no longer accepting jumbos
 402  * (that information is encoded in the ACK packet).
 403  */
 404 static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
 405                                  u8 annotation, bool *_jumbo_bad)
 406 {
 407         /* Discard normal packets that are duplicates. */
 408         if (annotation == 0)
 409                 return;
 410
 411         /* Skip jumbo subpackets that are duplicates.  When we've had three or
 412          * more partially duplicate jumbo packets, we refuse to take any more
 413          * jumbos for this call.
 414          */
 415         if (!*_jumbo_bad) {
 416                 call->nr_jumbo_bad++;
 417                 *_jumbo_bad = true;
 418         }
 419 }
 420
 421 /*
 422  * Process a DATA packet, adding the packet to the Rx ring.
 423  */
 424 static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb,
 425                              u16 skew)
 426 {
 427         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 428         enum rxrpc_call_state state;
 429         unsigned int offset = sizeof(struct rxrpc_wire_header);
 430         unsigned int ix;
 431         rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
 432         rxrpc_seq_t seq = sp->hdr.seq, hard_ack;
 433         bool immediate_ack = false, jumbo_bad = false, queued;
 434         u16 len;
 435         u8 ack = 0, flags, annotation = 0;
 436
 437         _enter("{%u,%u},{%u,%u}",
 438                call->rx_hard_ack, call->rx_top, skb->len, seq);
 439
 440         _proto("Rx DATA %%%u { #%u f=%02x }",
 441                sp->hdr.serial, seq, sp->hdr.flags);
 442
 443         state = READ_ONCE(call->state);
 444         if (state >= RXRPC_CALL_COMPLETE)
 445                 return;
 446
 447         /* Received data implicitly ACKs all of the request packets we sent
 448          * when we're acting as a client.
 449          */
 450         if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
 451              state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
 452             !rxrpc_receiving_reply(call))
 453                 return;
 454
 455         call->ackr_prev_seq = seq;
 456
 457         hard_ack = READ_ONCE(call->rx_hard_ack);
 458         if (after(seq, hard_ack + call->rx_winsize)) {
 459                 ack = RXRPC_ACK_EXCEEDS_WINDOW;
 460                 ack_serial = serial;
 461                 goto ack;
 462         }
 463
 464         flags = sp->hdr.flags;
 465         if (flags & RXRPC_JUMBO_PACKET) {
 466                 if (call->nr_jumbo_bad > 3) {
 467                         ack = RXRPC_ACK_NOSPACE;
 468                         ack_serial = serial;
 469                         goto ack;
 470                 }
 471                 annotation = 1;
 472         }
 473
 474 next_subpacket:
 475         queued = false;
 476         ix = seq & RXRPC_RXTX_BUFF_MASK;
 477         len = skb->len;
 478         if (flags & RXRPC_JUMBO_PACKET)
 479                 len = RXRPC_JUMBO_DATALEN;
 480
 481         if (flags & RXRPC_LAST_PACKET) {
 482                 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 483                     seq != call->rx_top)
 484                         return rxrpc_proto_abort("LSN", call, seq);
 485         } else {
 486                 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 487                     after_eq(seq, call->rx_top))
 488                         return rxrpc_proto_abort("LSA", call, seq);
 489         }
 490
 491         trace_rxrpc_rx_data(call, seq, serial, flags, annotation);
 492         if (before_eq(seq, hard_ack)) {
 493                 ack = RXRPC_ACK_DUPLICATE;
 494                 ack_serial = serial;
 495                 goto skip;
 496         }
 497
 498         if (flags & RXRPC_REQUEST_ACK && !ack) {
 499                 ack = RXRPC_ACK_REQUESTED;
 500                 ack_serial = serial;
 501         }
 502
 503         if (call->rxtx_buffer[ix]) {
 504                 rxrpc_input_dup_data(call, seq, annotation, &jumbo_bad);
 505                 if (ack != RXRPC_ACK_DUPLICATE) {
 506                         ack = RXRPC_ACK_DUPLICATE;
 507                         ack_serial = serial;
 508                 }
 509                 immediate_ack = true;
 510                 goto skip;
 511         }
 512
 513         /* Queue the packet.  We use a couple of memory barriers here as need
 514          * to make sure that rx_top is perceived to be set after the buffer
 515          * pointer and that the buffer pointer is set after the annotation and
 516          * the skb data.
 517          *
 518          * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
 519          * and also rxrpc_fill_out_ack().
 520          */
 521         rxrpc_get_skb(skb, rxrpc_skb_rx_got);
 522         call->rxtx_annotations[ix] = annotation;
 523         smp_wmb();
 524         call->rxtx_buffer[ix] = skb;
 525         if (after(seq, call->rx_top)) {
 526                 smp_store_release(&call->rx_top, seq);
 527         } else if (before(seq, call->rx_top)) {
 528                 /* Send an immediate ACK if we fill in a hole */
 529                 if (!ack) {
 530                         ack = RXRPC_ACK_DELAY;
 531                         ack_serial = serial;
 532                 }
 533                 immediate_ack = true;
 534         }
 535         if (flags & RXRPC_LAST_PACKET) {
 536                 set_bit(RXRPC_CALL_RX_LAST, &call->flags);
 537                 trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
 538         } else {
 539                 trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
 540         }
 541         queued = true;
 542
 543         if (after_eq(seq, call->rx_expect_next)) {
 544                 if (after(seq, call->rx_expect_next)) {
 545                         _net("OOS %u > %u", seq, call->rx_expect_next);
 546                         ack = RXRPC_ACK_OUT_OF_SEQUENCE;
 547                         ack_serial = serial;
 548                 }
 549                 call->rx_expect_next = seq + 1;
 550         }
 551
 552 skip:
 553         offset += len;
 554         if (flags & RXRPC_JUMBO_PACKET) {
 555                 if (skb_copy_bits(skb, offset, &flags, 1) < 0)
 556                         return rxrpc_proto_abort("XJF", call, seq);
 557                 offset += sizeof(struct rxrpc_jumbo_header);
 558                 seq++;
 559                 serial++;
 560                 annotation++;
 561                 if (flags & RXRPC_JUMBO_PACKET)
 562                         annotation |= RXRPC_RX_ANNO_JLAST;
 563                 if (after(seq, hard_ack + call->rx_winsize)) {
 564                         ack = RXRPC_ACK_EXCEEDS_WINDOW;
 565                         ack_serial = serial;
 566                         if (!jumbo_bad) {
 567                                 call->nr_jumbo_bad++;
 568                                 jumbo_bad = true;
 569                         }
 570                         goto ack;
 571                 }
 572
 573                 _proto("Rx DATA Jumbo %%%u", serial);
 574                 goto next_subpacket;
 575         }
 576
 577         if (queued && flags & RXRPC_LAST_PACKET && !ack) {
 578                 ack = RXRPC_ACK_DELAY;
 579                 ack_serial = serial;
 580         }
 581
 582 ack:
 583         if (ack)
 584                 rxrpc_propose_ACK(call, ack, skew, ack_serial,
 585                                   immediate_ack, true,
 586                                   rxrpc_propose_ack_input_data);
 587
 588         rxrpc_notify_socket(call);
 589         _leave(" [queued]");
 590 }
 591
 592 /*
 593  * Process a requested ACK.
 594  */
 595 static void rxrpc_input_requested_ack(struct rxrpc_call *call,
 596                                       ktime_t resp_time,
 597                                       rxrpc_serial_t orig_serial,
 598                                       rxrpc_serial_t ack_serial)
 599 {
 600         struct rxrpc_skb_priv *sp;
 601         struct sk_buff *skb;
 602         ktime_t sent_at;
 603         int ix;
 604
 605         for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
 606                 skb = call->rxtx_buffer[ix];
 607                 if (!skb)
 608                         continue;
 609
 610                 sp = rxrpc_skb(skb);
 611                 if (sp->hdr.serial != orig_serial)
 612                         continue;
 613                 smp_rmb();
 614                 sent_at = skb->tstamp;
 615                 goto found;
 616         }
 617         return;
 618
 619 found:
 620         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
 621                            orig_serial, ack_serial, sent_at, resp_time);
 622 }
 623
 624 /*
 625  * Process a ping response.
 626  */
 627 static void rxrpc_input_ping_response(struct rxrpc_call *call,
 628                                       ktime_t resp_time,
 629                                       rxrpc_serial_t orig_serial,
 630                                       rxrpc_serial_t ack_serial)
 631 {
 632         rxrpc_serial_t ping_serial;
 633         ktime_t ping_time;
 634
 635         ping_time = call->ping_time;
 636         smp_rmb();
 637         ping_serial = call->ping_serial;
 638
 639         if (!test_bit(RXRPC_CALL_PINGING, &call->flags) ||
 640             before(orig_serial, ping_serial))
 641                 return;
 642         clear_bit(RXRPC_CALL_PINGING, &call->flags);
 643         if (after(orig_serial, ping_serial))
 644                 return;
 645
 646         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
 647                            orig_serial, ack_serial, ping_time, resp_time);
 648 }
 649
 650 /*
 651  * Process the extra information that may be appended to an ACK packet
 652  */
 653 static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 654                                 struct rxrpc_ackinfo *ackinfo)
 655 {
 656         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 657         struct rxrpc_peer *peer;
 658         unsigned int mtu;
 659         bool wake = false;
 660         u32 rwind = ntohl(ackinfo->rwind);
 661
 662         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 663                sp->hdr.serial,
 664                ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
 665                rwind, ntohl(ackinfo->jumbo_max));
 666
 667         if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
 668                 rwind = RXRPC_RXTX_BUFF_SIZE - 1;
 669         if (call->tx_winsize != rwind) {
 670                 if (rwind > call->tx_winsize)
 671                         wake = true;
 672                 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake);
 673                 call->tx_winsize = rwind;
 674         }
 675
 676         if (call->cong_ssthresh > rwind)
 677                 call->cong_ssthresh = rwind;
 678
 679         mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
 680
 681         peer = call->peer;
 682         if (mtu < peer->maxdata) {
 683                 spin_lock_bh(&peer->lock);
 684                 peer->maxdata = mtu;
 685                 peer->mtu = mtu + peer->hdrsize;
 686                 spin_unlock_bh(&peer->lock);
 687                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 688         }
 689
 690         if (wake)
 691                 wake_up(&call->waitq);
 692 }
 693
 694 /*
 695  * Process individual soft ACKs.
 696  *
 697  * Each ACK in the array corresponds to one packet and can be either an ACK or
 698  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 699  * packets that lie beyond the end of the ACK list are scheduled for resend by
 700  * the timer on the basis that the peer might just not have processed them at
 701  * the time the ACK was sent.
 702  */
 703 static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 704                                   rxrpc_seq_t seq, int nr_acks,
 705                                   struct rxrpc_ack_summary *summary)
 706 {
 707         int ix;
 708         u8 annotation, anno_type;
 709
 710         for (; nr_acks > 0; nr_acks--, seq++) {
 711                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 712                 annotation = call->rxtx_annotations[ix];
 713                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 714                 annotation &= ~RXRPC_TX_ANNO_MASK;
 715                 switch (*acks++) {
 716                 case RXRPC_ACK_TYPE_ACK:
 717                         summary->nr_acks++;
 718                         if (anno_type == RXRPC_TX_ANNO_ACK)
 719                                 continue;
 720                         summary->nr_new_acks++;
 721                         call->rxtx_annotations[ix] =
 722                                 RXRPC_TX_ANNO_ACK | annotation;
 723                         break;
 724                 case RXRPC_ACK_TYPE_NACK:
 725                         if (!summary->nr_nacks &&
 726                             call->acks_lowest_nak != seq) {
 727                                 call->acks_lowest_nak = seq;
 728                                 summary->new_low_nack = true;
 729                         }
 730                         summary->nr_nacks++;
 731                         if (anno_type == RXRPC_TX_ANNO_NAK)
 732                                 continue;
 733                         summary->nr_new_nacks++;
 734                         if (anno_type == RXRPC_TX_ANNO_RETRANS)
 735                                 continue;
 736                         call->rxtx_annotations[ix] =
 737                                 RXRPC_TX_ANNO_NAK | annotation;
 738                         break;
 739                 default:
 740                         return rxrpc_proto_abort("SFT", call, 0);
 741                 }
 742         }
 743 }
 744
 745 /*
 746  * Process an ACK packet.
 747  *
 748  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 749  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 750  *
 751  * A hard-ACK means that a packet has been processed and may be discarded; a
 752  * soft-ACK means that the packet may be discarded and retransmission
 753  * requested.  A phase is complete when all packets are hard-ACK'd.
 754  */
 755 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
 756                             u16 skew)
 757 {
 758         struct rxrpc_ack_summary summary = { 0 };
 759         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 760         union {
 761                 struct rxrpc_ackpacket ack;
 762                 struct rxrpc_ackinfo info;
 763                 u8 acks[RXRPC_MAXACKS];
 764         } buf;
 765         rxrpc_serial_t acked_serial;
 766         rxrpc_seq_t first_soft_ack, hard_ack;
 767         int nr_acks, offset, ioffset;
 768
 769         _enter("");
 770
 771         offset = sizeof(struct rxrpc_wire_header);
 772         if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
 773                 _debug("extraction failure");
 774                 return rxrpc_proto_abort("XAK", call, 0);
 775         }
 776         offset += sizeof(buf.ack);
 777
 778         acked_serial = ntohl(buf.ack.serial);
 779         first_soft_ack = ntohl(buf.ack.firstPacket);
 780         hard_ack = first_soft_ack - 1;
 781         nr_acks = buf.ack.nAcks;
 782         summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
 783                               buf.ack.reason : RXRPC_ACK__INVALID);
 784
 785         trace_rxrpc_rx_ack(call, sp->hdr.serial, acked_serial,
 786                            first_soft_ack, ntohl(buf.ack.previousPacket),
 787                            summary.ack_reason, nr_acks);
 788
 789         if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
 790                 rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
 791                                           sp->hdr.serial);
 792         if (buf.ack.reason == RXRPC_ACK_REQUESTED)
 793                 rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
 794                                           sp->hdr.serial);
 795
 796         if (buf.ack.reason == RXRPC_ACK_PING) {
 797                 _proto("Rx ACK %%%u PING Request", sp->hdr.serial);
 798                 rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 799                                   skew, sp->hdr.serial, true, true,
 800                                   rxrpc_propose_ack_respond_to_ping);
 801         } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 802                 rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 803                                   skew, sp->hdr.serial, true, true,
 804                                   rxrpc_propose_ack_respond_to_ack);
 805         }
 806
 807         /* Discard any out-of-order or duplicate ACKs. */
 808         if (before_eq(sp->hdr.serial, call->acks_latest)) {
 809                 _debug("discard ACK %d <= %d",
 810                        sp->hdr.serial, call->acks_latest);
 811                 return;
 812         }
 813         call->acks_latest_ts = skb->tstamp;
 814         call->acks_latest = sp->hdr.serial;
 815
 816         /* Parse rwind and mtu sizes if provided. */
 817         ioffset = offset + nr_acks + 3;
 818         if (skb->len >= ioffset + sizeof(buf.info)) {
 819                 if (skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
 820                         return rxrpc_proto_abort("XAI", call, 0);
 821                 rxrpc_input_ackinfo(call, skb, &buf.info);
 822         }
 823
 824         if (first_soft_ack == 0)
 825                 return rxrpc_proto_abort("AK0", call, 0);
 826
 827         /* Ignore ACKs unless we are or have just been transmitting. */
 828         switch (READ_ONCE(call->state)) {
 829         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 830         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 831         case RXRPC_CALL_SERVER_SEND_REPLY:
 832         case RXRPC_CALL_SERVER_AWAIT_ACK:
 833                 break;
 834         default:
 835                 return;
 836         }
 837
 838         if (before(hard_ack, call->tx_hard_ack) ||
 839             after(hard_ack, call->tx_top))
 840                 return rxrpc_proto_abort("AKW", call, 0);
 841         if (nr_acks > call->tx_top - hard_ack)
 842                 return rxrpc_proto_abort("AKN", call, 0);
 843
 844         if (after(hard_ack, call->tx_hard_ack)) {
 845                 if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
 846                         rxrpc_end_tx_phase(call, false, "ETA");
 847                         return;
 848                 }
 849         }
 850
 851         if (nr_acks > 0) {
 852                 if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0)
 853                         return rxrpc_proto_abort("XSA", call, 0);
 854                 rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
 855                                       &summary);
 856         }
 857
 858         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 859             RXRPC_TX_ANNO_LAST &&
 860             summary.nr_acks == call->tx_top - hard_ack &&
 861             rxrpc_is_client_call(call))
 862                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
 863                                   false, true,
 864                                   rxrpc_propose_ack_ping_for_lost_reply);
 865
 866         return rxrpc_congestion_management(call, skb, &summary, acked_serial);
 867 }
 868
 869 /*
 870  * Process an ACKALL packet.
 871  */
 872 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
 873 {
 874         struct rxrpc_ack_summary summary = { 0 };
 875         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 876
 877         _proto("Rx ACKALL %%%u", sp->hdr.serial);
 878
 879         if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
 880                 rxrpc_end_tx_phase(call, false, "ETL");
 881 }
 882
 883 /*
 884  * Process an ABORT packet directed at a call.
 885  */
 886 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
 887 {
 888         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 889         __be32 wtmp;
 890         u32 abort_code = RX_CALL_DEAD;
 891
 892         _enter("");
 893
 894         if (skb->len >= 4 &&
 895             skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
 896                           &wtmp, sizeof(wtmp)) >= 0)
 897                 abort_code = ntohl(wtmp);
 898
 899         trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
 900
 901         _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
 902
 903         if (rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 904                                       abort_code, -ECONNABORTED))
 905                 rxrpc_notify_socket(call);
 906 }
 907
 908 /*
 909  * Process an incoming call packet.
 910  */
 911 static void rxrpc_input_call_packet(struct rxrpc_call *call,
 912                                     struct sk_buff *skb, u16 skew)
 913 {
 914         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 915
 916         _enter("%p,%p", call, skb);
 917
 918         switch (sp->hdr.type) {
 919         case RXRPC_PACKET_TYPE_DATA:
 920                 rxrpc_input_data(call, skb, skew);
 921                 break;
 922
 923         case RXRPC_PACKET_TYPE_ACK:
 924                 rxrpc_input_ack(call, skb, skew);
 925                 break;
 926
 927         case RXRPC_PACKET_TYPE_BUSY:
 928                 _proto("Rx BUSY %%%u", sp->hdr.serial);
 929
 930                 /* Just ignore BUSY packets from the server; the retry and
 931                  * lifespan timers will take care of business.  BUSY packets
 932                  * from the client don't make sense.
 933                  */
 934                 break;
 935
 936         case RXRPC_PACKET_TYPE_ABORT:
 937                 rxrpc_input_abort(call, skb);
 938                 break;
 939
 940         case RXRPC_PACKET_TYPE_ACKALL:
 941                 rxrpc_input_ackall(call, skb);
 942                 break;
 943
 944         default:
 945                 break;
 946         }
 947
 948         _leave("");
 949 }
 950
 951 /*
 952  * Handle a new call on a channel implicitly completing the preceding call on
 953  * that channel.
 954  *
 955  * TODO: If callNumber > call_id + 1, renegotiate security.
 956  */
 957 static void rxrpc_input_implicit_end_call(struct rxrpc_connection *conn,
 958                                           struct rxrpc_call *call)
 959 {
 960         switch (READ_ONCE(call->state)) {
 961         case RXRPC_CALL_SERVER_AWAIT_ACK:
 962                 rxrpc_call_completed(call);
 963                 break;
 964         case RXRPC_CALL_COMPLETE:
 965                 break;
 966         default:
 967                 if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
 968                         set_bit(RXRPC_CALL_EV_ABORT, &call->events);
 969                         rxrpc_queue_call(call);
 970                 }
 971                 break;
 972         }
 973
 974         trace_rxrpc_improper_term(call);
 975         __rxrpc_disconnect_call(conn, call);
 976         rxrpc_notify_socket(call);
 977 }
 978
 979 /*
 980  * post connection-level events to the connection
 981  * - this includes challenges, responses, some aborts and call terminal packet
 982  *   retransmission.
 983  */
 984 static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
 985                                       struct sk_buff *skb)
 986 {
 987         _enter("%p,%p", conn, skb);
 988
 989         skb_queue_tail(&conn->rx_queue, skb);
 990         rxrpc_queue_conn(conn);
 991 }
 992
 993 /*
 994  * post endpoint-level events to the local endpoint
 995  * - this includes debug and version messages
 996  */
 997 static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
 998                                        struct sk_buff *skb)
 999 {
1000         _enter("%p,%p", local, skb);
1001
1002         skb_queue_tail(&local->event_queue, skb);
1003         rxrpc_queue_local(local);
1004 }
1005
1006 /*
1007  * put a packet up for transport-level abort
1008  */
1009 static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
1010 {
1011         CHECK_SLAB_OKAY(&local->usage);
1012
1013         skb_queue_tail(&local->reject_queue, skb);
1014         rxrpc_queue_local(local);
1015 }
1016
1017 /*
1018  * Extract the wire header from a packet and translate the byte order.
1019  */
1020 static noinline
1021 int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
1022 {
1023         struct rxrpc_wire_header whdr;
1024
1025         /* dig out the RxRPC connection details */
1026         if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0) {
1027                 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
1028                                       tracepoint_string("bad_hdr"));
1029                 return -EBADMSG;
1030         }
1031
1032         memset(sp, 0, sizeof(*sp));
1033         sp->hdr.epoch           = ntohl(whdr.epoch);
1034         sp->hdr.cid             = ntohl(whdr.cid);
1035         sp->hdr.callNumber      = ntohl(whdr.callNumber);
1036         sp->hdr.seq             = ntohl(whdr.seq);
1037         sp->hdr.serial          = ntohl(whdr.serial);
1038         sp->hdr.flags           = whdr.flags;
1039         sp->hdr.type            = whdr.type;
1040         sp->hdr.userStatus      = whdr.userStatus;
1041         sp->hdr.securityIndex   = whdr.securityIndex;
1042         sp->hdr._rsvd           = ntohs(whdr._rsvd);
1043         sp->hdr.serviceId       = ntohs(whdr.serviceId);
1044         return 0;
1045 }
1046
1047 /*
1048  * handle data received on the local endpoint
1049  * - may be called in interrupt context
1050  *
1051  * The socket is locked by the caller and this prevents the socket from being
1052  * shut down and the local endpoint from going away, thus sk_user_data will not
1053  * be cleared until this function returns.
1054  */
1055 void rxrpc_data_ready(struct sock *udp_sk)
1056 {
1057         struct rxrpc_connection *conn;
1058         struct rxrpc_channel *chan;
1059         struct rxrpc_call *call;
1060         struct rxrpc_skb_priv *sp;
1061         struct rxrpc_local *local = udp_sk->sk_user_data;
1062         struct sk_buff *skb;
1063         unsigned int channel;
1064         int ret, skew;
1065
1066         _enter("%p", udp_sk);
1067
1068         ASSERT(!irqs_disabled());
1069
1070         skb = skb_recv_udp(udp_sk, 0, 1, &ret);
1071         if (!skb) {
1072                 if (ret == -EAGAIN)
1073                         return;
1074                 _debug("UDP socket error %d", ret);
1075                 return;
1076         }
1077
1078         rxrpc_new_skb(skb, rxrpc_skb_rx_received);
1079
1080         _net("recv skb %p", skb);
1081
1082         /* we'll probably need to checksum it (didn't call sock_recvmsg) */
1083         if (skb_checksum_complete(skb)) {
1084                 rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1085                 __UDP_INC_STATS(&init_net, UDP_MIB_INERRORS, 0);
1086                 _leave(" [CSUM failed]");
1087                 return;
1088         }
1089
1090         __UDP_INC_STATS(&init_net, UDP_MIB_INDATAGRAMS, 0);
1091
1092         /* The UDP protocol already released all skb resources;
1093          * we are free to add our own data there.
1094          */
1095         sp = rxrpc_skb(skb);
1096
1097         /* dig out the RxRPC connection details */
1098         if (rxrpc_extract_header(sp, skb) < 0)
1099                 goto bad_message;
1100
1101         if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
1102                 static int lose;
1103                 if ((lose++ & 7) == 7) {
1104                         trace_rxrpc_rx_lose(sp);
1105                         rxrpc_lose_skb(skb, rxrpc_skb_rx_lost);
1106                         return;
1107                 }
1108         }
1109
1110         trace_rxrpc_rx_packet(sp);
1111
1112         _net("Rx RxRPC %s ep=%x call=%x:%x",
1113              sp->hdr.flags & RXRPC_CLIENT_INITIATED ? "ToServer" : "ToClient",
1114              sp->hdr.epoch, sp->hdr.cid, sp->hdr.callNumber);
1115
1116         if (sp->hdr.type >= RXRPC_N_PACKET_TYPES ||
1117             !((RXRPC_SUPPORTED_PACKET_TYPES >> sp->hdr.type) & 1)) {
1118                 _proto("Rx Bad Packet Type %u", sp->hdr.type);
1119                 goto bad_message;
1120         }
1121
1122         switch (sp->hdr.type) {
1123         case RXRPC_PACKET_TYPE_VERSION:
1124                 rxrpc_post_packet_to_local(local, skb);
1125                 goto out;
1126
1127         case RXRPC_PACKET_TYPE_BUSY:
1128                 if (sp->hdr.flags & RXRPC_CLIENT_INITIATED)
1129                         goto discard;
1130
1131         case RXRPC_PACKET_TYPE_DATA:
1132                 if (sp->hdr.callNumber == 0)
1133                         goto bad_message;
1134                 if (sp->hdr.flags & RXRPC_JUMBO_PACKET &&
1135                     !rxrpc_validate_jumbo(skb))
1136                         goto bad_message;
1137                 break;
1138         }
1139
1140         rcu_read_lock();
1141
1142         conn = rxrpc_find_connection_rcu(local, skb);
1143         if (conn) {
1144                 if (sp->hdr.securityIndex != conn->security_ix)
1145                         goto wrong_security;
1146
1147                 if (sp->hdr.serviceId != conn->service_id) {
1148                         if (!test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags) ||
1149                             conn->service_id != conn->params.service_id)
1150                                 goto reupgrade;
1151                         conn->service_id = sp->hdr.serviceId;
1152                 }
1153
1154                 if (sp->hdr.callNumber == 0) {
1155                         /* Connection-level packet */
1156                         _debug("CONN %p {%d}", conn, conn->debug_id);
1157                         rxrpc_post_packet_to_conn(conn, skb);
1158                         goto out_unlock;
1159                 }
1160
1161                 /* Note the serial number skew here */
1162                 skew = (int)sp->hdr.serial - (int)conn->hi_serial;
1163                 if (skew >= 0) {
1164                         if (skew > 0)
1165                                 conn->hi_serial = sp->hdr.serial;
1166                 } else {
1167                         skew = -skew;
1168                         skew = min(skew, 65535);
1169                 }
1170
1171                 /* Call-bound packets are routed by connection channel. */
1172                 channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1173                 chan = &conn->channels[channel];
1174
1175                 /* Ignore really old calls */
1176                 if (sp->hdr.callNumber < chan->last_call)
1177                         goto discard_unlock;
1178
1179                 if (sp->hdr.callNumber == chan->last_call) {
1180                         if (chan->call ||
1181                             sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
1182                                 goto discard_unlock;
1183
1184                         /* For the previous service call, if completed
1185                          * successfully, we discard all further packets.
1186                          */
1187                         if (rxrpc_conn_is_service(conn) &&
1188                             chan->last_type == RXRPC_PACKET_TYPE_ACK)
1189                                 goto discard_unlock;
1190
1191                         /* But otherwise we need to retransmit the final packet
1192                          * from data cached in the connection record.
1193                          */
1194                         rxrpc_post_packet_to_conn(conn, skb);
1195                         goto out_unlock;
1196                 }
1197
1198                 call = rcu_dereference(chan->call);
1199
1200                 if (sp->hdr.callNumber > chan->call_id) {
1201                         if (!(sp->hdr.flags & RXRPC_CLIENT_INITIATED)) {
1202                                 rcu_read_unlock();
1203                                 goto reject_packet;
1204                         }
1205                         if (call)
1206                                 rxrpc_input_implicit_end_call(conn, call);
1207                         call = NULL;
1208                 }
1209
1210                 if (call && sp->hdr.serviceId != call->service_id)
1211                         call->service_id = sp->hdr.serviceId;
1212         } else {
1213                 skew = 0;
1214                 call = NULL;
1215         }
1216
1217         if (!call || atomic_read(&call->usage) == 0) {
1218                 if (!(sp->hdr.type & RXRPC_CLIENT_INITIATED) ||
1219                     sp->hdr.callNumber == 0 ||
1220                     sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1221                         goto bad_message_unlock;
1222                 if (sp->hdr.seq != 1)
1223                         goto discard_unlock;
1224                 call = rxrpc_new_incoming_call(local, conn, skb);
1225                 if (!call) {
1226                         rcu_read_unlock();
1227                         goto reject_packet;
1228                 }
1229                 rxrpc_send_ping(call, skb, skew);
1230                 mutex_unlock(&call->user_mutex);
1231         }
1232
1233         rxrpc_input_call_packet(call, skb, skew);
1234         goto discard_unlock;
1235
1236 discard_unlock:
1237         rcu_read_unlock();
1238 discard:
1239         rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1240 out:
1241         trace_rxrpc_rx_done(0, 0);
1242         return;
1243
1244 out_unlock:
1245         rcu_read_unlock();
1246         goto out;
1247
1248 wrong_security:
1249         rcu_read_unlock();
1250         trace_rxrpc_abort("SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1251                           RXKADINCONSISTENCY, EBADMSG);
1252         skb->priority = RXKADINCONSISTENCY;
1253         goto post_abort;
1254
1255 reupgrade:
1256         rcu_read_unlock();
1257         trace_rxrpc_abort("UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1258                           RX_PROTOCOL_ERROR, EBADMSG);
1259         goto protocol_error;
1260
1261 bad_message_unlock:
1262         rcu_read_unlock();
1263 bad_message:
1264         trace_rxrpc_abort("BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1265                           RX_PROTOCOL_ERROR, EBADMSG);
1266 protocol_error:
1267         skb->priority = RX_PROTOCOL_ERROR;
1268 post_abort:
1269         skb->mark = RXRPC_SKB_MARK_LOCAL_ABORT;
1270 reject_packet:
1271         trace_rxrpc_rx_done(skb->mark, skb->priority);
1272         rxrpc_reject_packet(local, skb);
1273         _leave(" [badmsg]");
1274 }