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_mark_not_on_list(skb);
 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         unsigned int state;
 282
 283         ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
 284
 285         write_lock(&call->state_lock);
 286
 287         state = call->state;
 288         switch (state) {
 289         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 290         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 291                 if (reply_begun)
 292                         call->state = state = RXRPC_CALL_CLIENT_RECV_REPLY;
 293                 else
 294                         call->state = state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
 295                 break;
 296
 297         case RXRPC_CALL_SERVER_AWAIT_ACK:
 298                 __rxrpc_call_completed(call);
 299                 rxrpc_notify_socket(call);
 300                 state = call->state;
 301                 break;
 302
 303         default:
 304                 goto bad_state;
 305         }
 306
 307         write_unlock(&call->state_lock);
 308         if (state == RXRPC_CALL_CLIENT_AWAIT_REPLY)
 309                 trace_rxrpc_transmit(call, rxrpc_transmit_await_reply);
 310         else
 311                 trace_rxrpc_transmit(call, rxrpc_transmit_end);
 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         unsigned long now, timo;
 329         rxrpc_seq_t top = READ_ONCE(call->tx_top);
 330
 331         if (call->ackr_reason) {
 332                 spin_lock_bh(&call->lock);
 333                 call->ackr_reason = 0;
 334                 spin_unlock_bh(&call->lock);
 335                 now = jiffies;
 336                 timo = now + MAX_JIFFY_OFFSET;
 337                 WRITE_ONCE(call->resend_at, timo);
 338                 WRITE_ONCE(call->ack_at, timo);
 339                 trace_rxrpc_timer(call, rxrpc_timer_init_for_reply, now);
 340         }
 341
 342         if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
 343                 if (!rxrpc_rotate_tx_window(call, top, &summary)) {
 344                         rxrpc_proto_abort("TXL", call, top);
 345                         return false;
 346                 }
 347         }
 348         if (!rxrpc_end_tx_phase(call, true, "ETD"))
 349                 return false;
 350         call->tx_phase = false;
 351         return true;
 352 }
 353
 354 /*
 355  * Scan a jumbo packet to validate its structure and to work out how many
 356  * subpackets it contains.
 357  *
 358  * A jumbo packet is a collection of consecutive packets glued together with
 359  * little headers between that indicate how to change the initial header for
 360  * each subpacket.
 361  *
 362  * RXRPC_JUMBO_PACKET must be set on all but the last subpacket - and all but
 363  * the last are RXRPC_JUMBO_DATALEN in size.  The last subpacket may be of any
 364  * size.
 365  */
 366 static bool rxrpc_validate_jumbo(struct sk_buff *skb)
 367 {
 368         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 369         unsigned int offset = sizeof(struct rxrpc_wire_header);
 370         unsigned int len = skb->len;
 371         int nr_jumbo = 1;
 372         u8 flags = sp->hdr.flags;
 373
 374         do {
 375                 nr_jumbo++;
 376                 if (len - offset < RXRPC_JUMBO_SUBPKTLEN)
 377                         goto protocol_error;
 378                 if (flags & RXRPC_LAST_PACKET)
 379                         goto protocol_error;
 380                 offset += RXRPC_JUMBO_DATALEN;
 381                 if (skb_copy_bits(skb, offset, &flags, 1) < 0)
 382                         goto protocol_error;
 383                 offset += sizeof(struct rxrpc_jumbo_header);
 384         } while (flags & RXRPC_JUMBO_PACKET);
 385
 386         sp->nr_jumbo = nr_jumbo;
 387         return true;
 388
 389 protocol_error:
 390         return false;
 391 }
 392
 393 /*
 394  * Handle reception of a duplicate packet.
 395  *
 396  * We have to take care to avoid an attack here whereby we're given a series of
 397  * jumbograms, each with a sequence number one before the preceding one and
 398  * filled up to maximum UDP size.  If they never send us the first packet in
 399  * the sequence, they can cause us to have to hold on to around 2MiB of kernel
 400  * space until the call times out.
 401  *
 402  * We limit the space usage by only accepting three duplicate jumbo packets per
 403  * call.  After that, we tell the other side we're no longer accepting jumbos
 404  * (that information is encoded in the ACK packet).
 405  */
 406 static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
 407                                  u8 annotation, bool *_jumbo_bad)
 408 {
 409         /* Discard normal packets that are duplicates. */
 410         if (annotation == 0)
 411                 return;
 412
 413         /* Skip jumbo subpackets that are duplicates.  When we've had three or
 414          * more partially duplicate jumbo packets, we refuse to take any more
 415          * jumbos for this call.
 416          */
 417         if (!*_jumbo_bad) {
 418                 call->nr_jumbo_bad++;
 419                 *_jumbo_bad = true;
 420         }
 421 }
 422
 423 /*
 424  * Process a DATA packet, adding the packet to the Rx ring.
 425  */
 426 static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb,
 427                              u16 skew)
 428 {
 429         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 430         enum rxrpc_call_state state;
 431         unsigned int offset = sizeof(struct rxrpc_wire_header);
 432         unsigned int ix;
 433         rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
 434         rxrpc_seq_t seq = sp->hdr.seq, hard_ack;
 435         bool immediate_ack = false, jumbo_bad = false, queued;
 436         u16 len;
 437         u8 ack = 0, flags, annotation = 0;
 438
 439         _enter("{%u,%u},{%u,%u}",
 440                call->rx_hard_ack, call->rx_top, skb->len, seq);
 441
 442         _proto("Rx DATA %%%u { #%u f=%02x }",
 443                sp->hdr.serial, seq, sp->hdr.flags);
 444
 445         state = READ_ONCE(call->state);
 446         if (state >= RXRPC_CALL_COMPLETE)
 447                 return;
 448
 449         if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST) {
 450                 unsigned long timo = READ_ONCE(call->next_req_timo);
 451                 unsigned long now, expect_req_by;
 452
 453                 if (timo) {
 454                         now = jiffies;
 455                         expect_req_by = now + timo;
 456                         WRITE_ONCE(call->expect_req_by, expect_req_by);
 457                         rxrpc_reduce_call_timer(call, expect_req_by, now,
 458                                                 rxrpc_timer_set_for_idle);
 459                 }
 460         }
 461
 462         spin_lock(&call->input_lock);
 463
 464         /* Received data implicitly ACKs all of the request packets we sent
 465          * when we're acting as a client.
 466          */
 467         if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
 468              state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
 469             !rxrpc_receiving_reply(call))
 470                 goto unlock;
 471
 472         call->ackr_prev_seq = seq;
 473
 474         hard_ack = READ_ONCE(call->rx_hard_ack);
 475         if (after(seq, hard_ack + call->rx_winsize)) {
 476                 ack = RXRPC_ACK_EXCEEDS_WINDOW;
 477                 ack_serial = serial;
 478                 goto ack;
 479         }
 480
 481         flags = sp->hdr.flags;
 482         if (flags & RXRPC_JUMBO_PACKET) {
 483                 if (call->nr_jumbo_bad > 3) {
 484                         ack = RXRPC_ACK_NOSPACE;
 485                         ack_serial = serial;
 486                         goto ack;
 487                 }
 488                 annotation = 1;
 489         }
 490
 491 next_subpacket:
 492         queued = false;
 493         ix = seq & RXRPC_RXTX_BUFF_MASK;
 494         len = skb->len;
 495         if (flags & RXRPC_JUMBO_PACKET)
 496                 len = RXRPC_JUMBO_DATALEN;
 497
 498         if (flags & RXRPC_LAST_PACKET) {
 499                 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 500                     seq != call->rx_top) {
 501                         rxrpc_proto_abort("LSN", call, seq);
 502                         goto unlock;
 503                 }
 504         } else {
 505                 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 506                     after_eq(seq, call->rx_top)) {
 507                         rxrpc_proto_abort("LSA", call, seq);
 508                         goto unlock;
 509                 }
 510         }
 511
 512         trace_rxrpc_rx_data(call->debug_id, seq, serial, flags, annotation);
 513         if (before_eq(seq, hard_ack)) {
 514                 ack = RXRPC_ACK_DUPLICATE;
 515                 ack_serial = serial;
 516                 goto skip;
 517         }
 518
 519         if (flags & RXRPC_REQUEST_ACK && !ack) {
 520                 ack = RXRPC_ACK_REQUESTED;
 521                 ack_serial = serial;
 522         }
 523
 524         if (call->rxtx_buffer[ix]) {
 525                 rxrpc_input_dup_data(call, seq, annotation, &jumbo_bad);
 526                 if (ack != RXRPC_ACK_DUPLICATE) {
 527                         ack = RXRPC_ACK_DUPLICATE;
 528                         ack_serial = serial;
 529                 }
 530                 immediate_ack = true;
 531                 goto skip;
 532         }
 533
 534         /* Queue the packet.  We use a couple of memory barriers here as need
 535          * to make sure that rx_top is perceived to be set after the buffer
 536          * pointer and that the buffer pointer is set after the annotation and
 537          * the skb data.
 538          *
 539          * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
 540          * and also rxrpc_fill_out_ack().
 541          */
 542         rxrpc_get_skb(skb, rxrpc_skb_rx_got);
 543         call->rxtx_annotations[ix] = annotation;
 544         smp_wmb();
 545         call->rxtx_buffer[ix] = skb;
 546         if (after(seq, call->rx_top)) {
 547                 smp_store_release(&call->rx_top, seq);
 548         } else if (before(seq, call->rx_top)) {
 549                 /* Send an immediate ACK if we fill in a hole */
 550                 if (!ack) {
 551                         ack = RXRPC_ACK_DELAY;
 552                         ack_serial = serial;
 553                 }
 554                 immediate_ack = true;
 555         }
 556         if (flags & RXRPC_LAST_PACKET) {
 557                 set_bit(RXRPC_CALL_RX_LAST, &call->flags);
 558                 trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
 559         } else {
 560                 trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
 561         }
 562         queued = true;
 563
 564         if (after_eq(seq, call->rx_expect_next)) {
 565                 if (after(seq, call->rx_expect_next)) {
 566                         _net("OOS %u > %u", seq, call->rx_expect_next);
 567                         ack = RXRPC_ACK_OUT_OF_SEQUENCE;
 568                         ack_serial = serial;
 569                 }
 570                 call->rx_expect_next = seq + 1;
 571         }
 572
 573 skip:
 574         offset += len;
 575         if (flags & RXRPC_JUMBO_PACKET) {
 576                 if (skb_copy_bits(skb, offset, &flags, 1) < 0) {
 577                         rxrpc_proto_abort("XJF", call, seq);
 578                         goto unlock;
 579                 }
 580                 offset += sizeof(struct rxrpc_jumbo_header);
 581                 seq++;
 582                 serial++;
 583                 annotation++;
 584                 if (flags & RXRPC_JUMBO_PACKET)
 585                         annotation |= RXRPC_RX_ANNO_JLAST;
 586                 if (after(seq, hard_ack + call->rx_winsize)) {
 587                         ack = RXRPC_ACK_EXCEEDS_WINDOW;
 588                         ack_serial = serial;
 589                         if (!jumbo_bad) {
 590                                 call->nr_jumbo_bad++;
 591                                 jumbo_bad = true;
 592                         }
 593                         goto ack;
 594                 }
 595
 596                 _proto("Rx DATA Jumbo %%%u", serial);
 597                 goto next_subpacket;
 598         }
 599
 600         if (queued && flags & RXRPC_LAST_PACKET && !ack) {
 601                 ack = RXRPC_ACK_DELAY;
 602                 ack_serial = serial;
 603         }
 604
 605 ack:
 606         if (ack)
 607                 rxrpc_propose_ACK(call, ack, skew, ack_serial,
 608                                   immediate_ack, true,
 609                                   rxrpc_propose_ack_input_data);
 610         else
 611                 rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, skew, serial,
 612                                   false, true,
 613                                   rxrpc_propose_ack_input_data);
 614
 615         if (sp->hdr.seq == READ_ONCE(call->rx_hard_ack) + 1) {
 616                 trace_rxrpc_notify_socket(call->debug_id, serial);
 617                 rxrpc_notify_socket(call);
 618         }
 619
 620 unlock:
 621         spin_unlock(&call->input_lock);
 622         _leave(" [queued]");
 623 }
 624
 625 /*
 626  * Process a requested ACK.
 627  */
 628 static void rxrpc_input_requested_ack(struct rxrpc_call *call,
 629                                       ktime_t resp_time,
 630                                       rxrpc_serial_t orig_serial,
 631                                       rxrpc_serial_t ack_serial)
 632 {
 633         struct rxrpc_skb_priv *sp;
 634         struct sk_buff *skb;
 635         ktime_t sent_at;
 636         int ix;
 637
 638         for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
 639                 skb = call->rxtx_buffer[ix];
 640                 if (!skb)
 641                         continue;
 642
 643                 sent_at = skb->tstamp;
 644                 smp_rmb(); /* Read timestamp before serial. */
 645                 sp = rxrpc_skb(skb);
 646                 if (sp->hdr.serial != orig_serial)
 647                         continue;
 648                 goto found;
 649         }
 650
 651         return;
 652
 653 found:
 654         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
 655                            orig_serial, ack_serial, sent_at, resp_time);
 656 }
 657
 658 /*
 659  * Process the response to a ping that we sent to find out if we lost an ACK.
 660  *
 661  * If we got back a ping response that indicates a lower tx_top than what we
 662  * had at the time of the ping transmission, we adjudge all the DATA packets
 663  * sent between the response tx_top and the ping-time tx_top to have been lost.
 664  */
 665 static void rxrpc_input_check_for_lost_ack(struct rxrpc_call *call)
 666 {
 667         rxrpc_seq_t top, bottom, seq;
 668         bool resend = false;
 669
 670         spin_lock_bh(&call->lock);
 671
 672         bottom = call->tx_hard_ack + 1;
 673         top = call->acks_lost_top;
 674         if (before(bottom, top)) {
 675                 for (seq = bottom; before_eq(seq, top); seq++) {
 676                         int ix = seq & RXRPC_RXTX_BUFF_MASK;
 677                         u8 annotation = call->rxtx_annotations[ix];
 678                         u8 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 679
 680                         if (anno_type != RXRPC_TX_ANNO_UNACK)
 681                                 continue;
 682                         annotation &= ~RXRPC_TX_ANNO_MASK;
 683                         annotation |= RXRPC_TX_ANNO_RETRANS;
 684                         call->rxtx_annotations[ix] = annotation;
 685                         resend = true;
 686                 }
 687         }
 688
 689         spin_unlock_bh(&call->lock);
 690
 691         if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 692                 rxrpc_queue_call(call);
 693 }
 694
 695 /*
 696  * Process a ping response.
 697  */
 698 static void rxrpc_input_ping_response(struct rxrpc_call *call,
 699                                       ktime_t resp_time,
 700                                       rxrpc_serial_t orig_serial,
 701                                       rxrpc_serial_t ack_serial)
 702 {
 703         rxrpc_serial_t ping_serial;
 704         ktime_t ping_time;
 705
 706         ping_time = call->ping_time;
 707         smp_rmb();
 708         ping_serial = READ_ONCE(call->ping_serial);
 709
 710         if (orig_serial == call->acks_lost_ping)
 711                 rxrpc_input_check_for_lost_ack(call);
 712
 713         if (before(orig_serial, ping_serial) ||
 714             !test_and_clear_bit(RXRPC_CALL_PINGING, &call->flags))
 715                 return;
 716         if (after(orig_serial, ping_serial))
 717                 return;
 718
 719         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
 720                            orig_serial, ack_serial, ping_time, resp_time);
 721 }
 722
 723 /*
 724  * Process the extra information that may be appended to an ACK packet
 725  */
 726 static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 727                                 struct rxrpc_ackinfo *ackinfo)
 728 {
 729         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 730         struct rxrpc_peer *peer;
 731         unsigned int mtu;
 732         bool wake = false;
 733         u32 rwind = ntohl(ackinfo->rwind);
 734
 735         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 736                sp->hdr.serial,
 737                ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
 738                rwind, ntohl(ackinfo->jumbo_max));
 739
 740         if (call->tx_winsize != rwind) {
 741                 if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
 742                         rwind = RXRPC_RXTX_BUFF_SIZE - 1;
 743                 if (rwind > call->tx_winsize)
 744                         wake = true;
 745                 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial,
 746                                             ntohl(ackinfo->rwind), wake);
 747                 call->tx_winsize = rwind;
 748         }
 749
 750         if (call->cong_ssthresh > rwind)
 751                 call->cong_ssthresh = rwind;
 752
 753         mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
 754
 755         peer = call->peer;
 756         if (mtu < peer->maxdata) {
 757                 spin_lock_bh(&peer->lock);
 758                 peer->maxdata = mtu;
 759                 peer->mtu = mtu + peer->hdrsize;
 760                 spin_unlock_bh(&peer->lock);
 761                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 762         }
 763
 764         if (wake)
 765                 wake_up(&call->waitq);
 766 }
 767
 768 /*
 769  * Process individual soft ACKs.
 770  *
 771  * Each ACK in the array corresponds to one packet and can be either an ACK or
 772  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 773  * packets that lie beyond the end of the ACK list are scheduled for resend by
 774  * the timer on the basis that the peer might just not have processed them at
 775  * the time the ACK was sent.
 776  */
 777 static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 778                                   rxrpc_seq_t seq, int nr_acks,
 779                                   struct rxrpc_ack_summary *summary)
 780 {
 781         int ix;
 782         u8 annotation, anno_type;
 783
 784         for (; nr_acks > 0; nr_acks--, seq++) {
 785                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 786                 annotation = call->rxtx_annotations[ix];
 787                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 788                 annotation &= ~RXRPC_TX_ANNO_MASK;
 789                 switch (*acks++) {
 790                 case RXRPC_ACK_TYPE_ACK:
 791                         summary->nr_acks++;
 792                         if (anno_type == RXRPC_TX_ANNO_ACK)
 793                                 continue;
 794                         summary->nr_new_acks++;
 795                         call->rxtx_annotations[ix] =
 796                                 RXRPC_TX_ANNO_ACK | annotation;
 797                         break;
 798                 case RXRPC_ACK_TYPE_NACK:
 799                         if (!summary->nr_nacks &&
 800                             call->acks_lowest_nak != seq) {
 801                                 call->acks_lowest_nak = seq;
 802                                 summary->new_low_nack = true;
 803                         }
 804                         summary->nr_nacks++;
 805                         if (anno_type == RXRPC_TX_ANNO_NAK)
 806                                 continue;
 807                         summary->nr_new_nacks++;
 808                         if (anno_type == RXRPC_TX_ANNO_RETRANS)
 809                                 continue;
 810                         call->rxtx_annotations[ix] =
 811                                 RXRPC_TX_ANNO_NAK | annotation;
 812                         break;
 813                 default:
 814                         return rxrpc_proto_abort("SFT", call, 0);
 815                 }
 816         }
 817 }
 818
 819 /*
 820  * Process an ACK packet.
 821  *
 822  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 823  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 824  *
 825  * A hard-ACK means that a packet has been processed and may be discarded; a
 826  * soft-ACK means that the packet may be discarded and retransmission
 827  * requested.  A phase is complete when all packets are hard-ACK'd.
 828  */
 829 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
 830                             u16 skew)
 831 {
 832         struct rxrpc_ack_summary summary = { 0 };
 833         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 834         union {
 835                 struct rxrpc_ackpacket ack;
 836                 struct rxrpc_ackinfo info;
 837                 u8 acks[RXRPC_MAXACKS];
 838         } buf;
 839         rxrpc_serial_t acked_serial;
 840         rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
 841         int nr_acks, offset, ioffset;
 842
 843         _enter("");
 844
 845         offset = sizeof(struct rxrpc_wire_header);
 846         if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
 847                 _debug("extraction failure");
 848                 return rxrpc_proto_abort("XAK", call, 0);
 849         }
 850         offset += sizeof(buf.ack);
 851
 852         acked_serial = ntohl(buf.ack.serial);
 853         first_soft_ack = ntohl(buf.ack.firstPacket);
 854         prev_pkt = ntohl(buf.ack.previousPacket);
 855         hard_ack = first_soft_ack - 1;
 856         nr_acks = buf.ack.nAcks;
 857         summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
 858                               buf.ack.reason : RXRPC_ACK__INVALID);
 859
 860         trace_rxrpc_rx_ack(call, sp->hdr.serial, acked_serial,
 861                            first_soft_ack, prev_pkt,
 862                            summary.ack_reason, nr_acks);
 863
 864         if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
 865                 rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
 866                                           sp->hdr.serial);
 867         if (buf.ack.reason == RXRPC_ACK_REQUESTED)
 868                 rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
 869                                           sp->hdr.serial);
 870
 871         if (buf.ack.reason == RXRPC_ACK_PING) {
 872                 _proto("Rx ACK %%%u PING Request", sp->hdr.serial);
 873                 rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 874                                   skew, sp->hdr.serial, true, true,
 875                                   rxrpc_propose_ack_respond_to_ping);
 876         } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 877                 rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 878                                   skew, sp->hdr.serial, true, true,
 879                                   rxrpc_propose_ack_respond_to_ack);
 880         }
 881
 882         /* Discard any out-of-order or duplicate ACKs (outside lock). */
 883         if (before(first_soft_ack, call->ackr_first_seq) ||
 884             before(prev_pkt, call->ackr_prev_seq))
 885                 return;
 886
 887         buf.info.rxMTU = 0;
 888         ioffset = offset + nr_acks + 3;
 889         if (skb->len >= ioffset + sizeof(buf.info) &&
 890             skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
 891                 return rxrpc_proto_abort("XAI", call, 0);
 892
 893         spin_lock(&call->input_lock);
 894
 895         /* Discard any out-of-order or duplicate ACKs (inside lock). */
 896         if (before(first_soft_ack, call->ackr_first_seq) ||
 897             before(prev_pkt, call->ackr_prev_seq))
 898                 goto out;
 899         call->acks_latest_ts = skb->tstamp;
 900         call->acks_latest = sp->hdr.serial;
 901
 902         call->ackr_first_seq = first_soft_ack;
 903         call->ackr_prev_seq = prev_pkt;
 904
 905         /* Parse rwind and mtu sizes if provided. */
 906         if (buf.info.rxMTU)
 907                 rxrpc_input_ackinfo(call, skb, &buf.info);
 908
 909         if (first_soft_ack == 0) {
 910                 rxrpc_proto_abort("AK0", call, 0);
 911                 goto out;
 912         }
 913
 914         /* Ignore ACKs unless we are or have just been transmitting. */
 915         switch (READ_ONCE(call->state)) {
 916         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 917         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 918         case RXRPC_CALL_SERVER_SEND_REPLY:
 919         case RXRPC_CALL_SERVER_AWAIT_ACK:
 920                 break;
 921         default:
 922                 goto out;
 923         }
 924
 925         if (before(hard_ack, call->tx_hard_ack) ||
 926             after(hard_ack, call->tx_top)) {
 927                 rxrpc_proto_abort("AKW", call, 0);
 928                 goto out;
 929         }
 930         if (nr_acks > call->tx_top - hard_ack) {
 931                 rxrpc_proto_abort("AKN", call, 0);
 932                 goto out;
 933         }
 934
 935         if (after(hard_ack, call->tx_hard_ack)) {
 936                 if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
 937                         rxrpc_end_tx_phase(call, false, "ETA");
 938                         goto out;
 939                 }
 940         }
 941
 942         if (nr_acks > 0) {
 943                 if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0) {
 944                         rxrpc_proto_abort("XSA", call, 0);
 945                         goto out;
 946                 }
 947                 rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
 948                                       &summary);
 949         }
 950
 951         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 952             RXRPC_TX_ANNO_LAST &&
 953             summary.nr_acks == call->tx_top - hard_ack &&
 954             rxrpc_is_client_call(call))
 955                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
 956                                   false, true,
 957                                   rxrpc_propose_ack_ping_for_lost_reply);
 958
 959         rxrpc_congestion_management(call, skb, &summary, acked_serial);
 960 out:
 961         spin_unlock(&call->input_lock);
 962 }
 963
 964 /*
 965  * Process an ACKALL packet.
 966  */
 967 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
 968 {
 969         struct rxrpc_ack_summary summary = { 0 };
 970         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 971
 972         _proto("Rx ACKALL %%%u", sp->hdr.serial);
 973
 974         spin_lock(&call->input_lock);
 975
 976         if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
 977                 rxrpc_end_tx_phase(call, false, "ETL");
 978
 979         spin_unlock(&call->input_lock);
 980 }
 981
 982 /*
 983  * Process an ABORT packet directed at a call.
 984  */
 985 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
 986 {
 987         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 988         __be32 wtmp;
 989         u32 abort_code = RX_CALL_DEAD;
 990
 991         _enter("");
 992
 993         if (skb->len >= 4 &&
 994             skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
 995                           &wtmp, sizeof(wtmp)) >= 0)
 996                 abort_code = ntohl(wtmp);
 997
 998         trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
 999
1000         _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
1001
1002         if (rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
1003                                       abort_code, -ECONNABORTED))
1004                 rxrpc_notify_socket(call);
1005 }
1006
1007 /*
1008  * Process an incoming call packet.
1009  */
1010 static void rxrpc_input_call_packet(struct rxrpc_call *call,
1011                                     struct sk_buff *skb, u16 skew)
1012 {
1013         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1014         unsigned long timo;
1015
1016         _enter("%p,%p", call, skb);
1017
1018         timo = READ_ONCE(call->next_rx_timo);
1019         if (timo) {
1020                 unsigned long now = jiffies, expect_rx_by;
1021
1022                 expect_rx_by = now + timo;
1023                 WRITE_ONCE(call->expect_rx_by, expect_rx_by);
1024                 rxrpc_reduce_call_timer(call, expect_rx_by, now,
1025                                         rxrpc_timer_set_for_normal);
1026         }
1027
1028         switch (sp->hdr.type) {
1029         case RXRPC_PACKET_TYPE_DATA:
1030                 rxrpc_input_data(call, skb, skew);
1031                 break;
1032
1033         case RXRPC_PACKET_TYPE_ACK:
1034                 rxrpc_input_ack(call, skb, skew);
1035                 break;
1036
1037         case RXRPC_PACKET_TYPE_BUSY:
1038                 _proto("Rx BUSY %%%u", sp->hdr.serial);
1039
1040                 /* Just ignore BUSY packets from the server; the retry and
1041                  * lifespan timers will take care of business.  BUSY packets
1042                  * from the client don't make sense.
1043                  */
1044                 break;
1045
1046         case RXRPC_PACKET_TYPE_ABORT:
1047                 rxrpc_input_abort(call, skb);
1048                 break;
1049
1050         case RXRPC_PACKET_TYPE_ACKALL:
1051                 rxrpc_input_ackall(call, skb);
1052                 break;
1053
1054         default:
1055                 break;
1056         }
1057
1058         _leave("");
1059 }
1060
1061 /*
1062  * Handle a new service call on a channel implicitly completing the preceding
1063  * call on that channel.  This does not apply to client conns.
1064  *
1065  * TODO: If callNumber > call_id + 1, renegotiate security.
1066  */
1067 static void rxrpc_input_implicit_end_call(struct rxrpc_sock *rx,
1068                                           struct rxrpc_connection *conn,
1069                                           struct rxrpc_call *call)
1070 {
1071         switch (READ_ONCE(call->state)) {
1072         case RXRPC_CALL_SERVER_AWAIT_ACK:
1073                 rxrpc_call_completed(call);
1074                 /* Fall through */
1075         case RXRPC_CALL_COMPLETE:
1076                 break;
1077         default:
1078                 if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
1079                         set_bit(RXRPC_CALL_EV_ABORT, &call->events);
1080                         rxrpc_queue_call(call);
1081                 }
1082                 trace_rxrpc_improper_term(call);
1083                 break;
1084         }
1085
1086         spin_lock(&rx->incoming_lock);
1087         __rxrpc_disconnect_call(conn, call);
1088         spin_unlock(&rx->incoming_lock);
1089         rxrpc_notify_socket(call);
1090 }
1091
1092 /*
1093  * post connection-level events to the connection
1094  * - this includes challenges, responses, some aborts and call terminal packet
1095  *   retransmission.
1096  */
1097 static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
1098                                       struct sk_buff *skb)
1099 {
1100         _enter("%p,%p", conn, skb);
1101
1102         skb_queue_tail(&conn->rx_queue, skb);
1103         rxrpc_queue_conn(conn);
1104 }
1105
1106 /*
1107  * post endpoint-level events to the local endpoint
1108  * - this includes debug and version messages
1109  */
1110 static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
1111                                        struct sk_buff *skb)
1112 {
1113         _enter("%p,%p", local, skb);
1114
1115         skb_queue_tail(&local->event_queue, skb);
1116         rxrpc_queue_local(local);
1117 }
1118
1119 /*
1120  * put a packet up for transport-level abort
1121  */
1122 static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
1123 {
1124         CHECK_SLAB_OKAY(&local->usage);
1125
1126         skb_queue_tail(&local->reject_queue, skb);
1127         rxrpc_queue_local(local);
1128 }
1129
1130 /*
1131  * Extract the wire header from a packet and translate the byte order.
1132  */
1133 static noinline
1134 int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
1135 {
1136         struct rxrpc_wire_header whdr;
1137
1138         /* dig out the RxRPC connection details */
1139         if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0) {
1140                 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
1141                                       tracepoint_string("bad_hdr"));
1142                 return -EBADMSG;
1143         }
1144
1145         memset(sp, 0, sizeof(*sp));
1146         sp->hdr.epoch           = ntohl(whdr.epoch);
1147         sp->hdr.cid             = ntohl(whdr.cid);
1148         sp->hdr.callNumber      = ntohl(whdr.callNumber);
1149         sp->hdr.seq             = ntohl(whdr.seq);
1150         sp->hdr.serial          = ntohl(whdr.serial);
1151         sp->hdr.flags           = whdr.flags;
1152         sp->hdr.type            = whdr.type;
1153         sp->hdr.userStatus      = whdr.userStatus;
1154         sp->hdr.securityIndex   = whdr.securityIndex;
1155         sp->hdr._rsvd           = ntohs(whdr._rsvd);
1156         sp->hdr.serviceId       = ntohs(whdr.serviceId);
1157         return 0;
1158 }
1159
1160 /*
1161  * handle data received on the local endpoint
1162  * - may be called in interrupt context
1163  *
1164  * [!] Note that as this is called from the encap_rcv hook, the socket is not
1165  * held locked by the caller and nothing prevents sk_user_data on the UDP from
1166  * being cleared in the middle of processing this function.
1167  *
1168  * Called with the RCU read lock held from the IP layer via UDP.
1169  */
1170 int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
1171 {
1172         struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
1173         struct rxrpc_connection *conn;
1174         struct rxrpc_channel *chan;
1175         struct rxrpc_call *call = NULL;
1176         struct rxrpc_skb_priv *sp;
1177         struct rxrpc_peer *peer = NULL;
1178         struct rxrpc_sock *rx = NULL;
1179         unsigned int channel;
1180         int skew = 0;
1181
1182         _enter("%p", udp_sk);
1183
1184         if (unlikely(!local)) {
1185                 kfree_skb(skb);
1186                 return 0;
1187         }
1188         if (skb->tstamp == 0)
1189                 skb->tstamp = ktime_get_real();
1190
1191         rxrpc_new_skb(skb, rxrpc_skb_rx_received);
1192
1193         skb_pull(skb, sizeof(struct udphdr));
1194
1195         /* The UDP protocol already released all skb resources;
1196          * we are free to add our own data there.
1197          */
1198         sp = rxrpc_skb(skb);
1199
1200         /* dig out the RxRPC connection details */
1201         if (rxrpc_extract_header(sp, skb) < 0)
1202                 goto bad_message;
1203
1204         if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
1205                 static int lose;
1206                 if ((lose++ & 7) == 7) {
1207                         trace_rxrpc_rx_lose(sp);
1208                         rxrpc_free_skb(skb, rxrpc_skb_rx_lost);
1209                         return 0;
1210                 }
1211         }
1212
1213         if (skb->tstamp == 0)
1214                 skb->tstamp = ktime_get_real();
1215         trace_rxrpc_rx_packet(sp);
1216
1217         switch (sp->hdr.type) {
1218         case RXRPC_PACKET_TYPE_VERSION:
1219                 if (rxrpc_to_client(sp))
1220                         goto discard;
1221                 rxrpc_post_packet_to_local(local, skb);
1222                 goto out;
1223
1224         case RXRPC_PACKET_TYPE_BUSY:
1225                 if (rxrpc_to_server(sp))
1226                         goto discard;
1227                 /* Fall through */
1228         case RXRPC_PACKET_TYPE_ACK:
1229         case RXRPC_PACKET_TYPE_ACKALL:
1230                 if (sp->hdr.callNumber == 0)
1231                         goto bad_message;
1232                 /* Fall through */
1233         case RXRPC_PACKET_TYPE_ABORT:
1234                 break;
1235
1236         case RXRPC_PACKET_TYPE_DATA:
1237                 if (sp->hdr.callNumber == 0 ||
1238                     sp->hdr.seq == 0)
1239                         goto bad_message;
1240                 if (sp->hdr.flags & RXRPC_JUMBO_PACKET &&
1241                     !rxrpc_validate_jumbo(skb))
1242                         goto bad_message;
1243                 break;
1244
1245         case RXRPC_PACKET_TYPE_CHALLENGE:
1246                 if (rxrpc_to_server(sp))
1247                         goto discard;
1248                 break;
1249         case RXRPC_PACKET_TYPE_RESPONSE:
1250                 if (rxrpc_to_client(sp))
1251                         goto discard;
1252                 break;
1253
1254                 /* Packet types 9-11 should just be ignored. */
1255         case RXRPC_PACKET_TYPE_PARAMS:
1256         case RXRPC_PACKET_TYPE_10:
1257         case RXRPC_PACKET_TYPE_11:
1258                 goto discard;
1259
1260         default:
1261                 _proto("Rx Bad Packet Type %u", sp->hdr.type);
1262                 goto bad_message;
1263         }
1264
1265         if (sp->hdr.serviceId == 0)
1266                 goto bad_message;
1267
1268         if (rxrpc_to_server(sp)) {
1269                 /* Weed out packets to services we're not offering.  Packets
1270                  * that would begin a call are explicitly rejected and the rest
1271                  * are just discarded.
1272                  */
1273                 rx = rcu_dereference(local->service);
1274                 if (!rx || (sp->hdr.serviceId != rx->srx.srx_service &&
1275                             sp->hdr.serviceId != rx->second_service)) {
1276                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
1277                             sp->hdr.seq == 1)
1278                                 goto unsupported_service;
1279                         goto discard;
1280                 }
1281         }
1282
1283         conn = rxrpc_find_connection_rcu(local, skb, &peer);
1284         if (conn) {
1285                 if (sp->hdr.securityIndex != conn->security_ix)
1286                         goto wrong_security;
1287
1288                 if (sp->hdr.serviceId != conn->service_id) {
1289                         int old_id;
1290
1291                         if (!test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags))
1292                                 goto reupgrade;
1293                         old_id = cmpxchg(&conn->service_id, conn->params.service_id,
1294                                          sp->hdr.serviceId);
1295
1296                         if (old_id != conn->params.service_id &&
1297                             old_id != sp->hdr.serviceId)
1298                                 goto reupgrade;
1299                 }
1300
1301                 if (sp->hdr.callNumber == 0) {
1302                         /* Connection-level packet */
1303                         _debug("CONN %p {%d}", conn, conn->debug_id);
1304                         rxrpc_post_packet_to_conn(conn, skb);
1305                         goto out;
1306                 }
1307
1308                 /* Note the serial number skew here */
1309                 skew = (int)sp->hdr.serial - (int)conn->hi_serial;
1310                 if (skew >= 0) {
1311                         if (skew > 0)
1312                                 conn->hi_serial = sp->hdr.serial;
1313                 } else {
1314                         skew = -skew;
1315                         skew = min(skew, 65535);
1316                 }
1317
1318                 /* Call-bound packets are routed by connection channel. */
1319                 channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1320                 chan = &conn->channels[channel];
1321
1322                 /* Ignore really old calls */
1323                 if (sp->hdr.callNumber < chan->last_call)
1324                         goto discard;
1325
1326                 if (sp->hdr.callNumber == chan->last_call) {
1327                         if (chan->call ||
1328                             sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
1329                                 goto discard;
1330
1331                         /* For the previous service call, if completed
1332                          * successfully, we discard all further packets.
1333                          */
1334                         if (rxrpc_conn_is_service(conn) &&
1335                             chan->last_type == RXRPC_PACKET_TYPE_ACK)
1336                                 goto discard;
1337
1338                         /* But otherwise we need to retransmit the final packet
1339                          * from data cached in the connection record.
1340                          */
1341                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
1342                                 trace_rxrpc_rx_data(chan->call_debug_id,
1343                                                     sp->hdr.seq,
1344                                                     sp->hdr.serial,
1345                                                     sp->hdr.flags, 0);
1346                         rxrpc_post_packet_to_conn(conn, skb);
1347                         goto out;
1348                 }
1349
1350                 call = rcu_dereference(chan->call);
1351
1352                 if (sp->hdr.callNumber > chan->call_id) {
1353                         if (rxrpc_to_client(sp))
1354                                 goto reject_packet;
1355                         if (call)
1356                                 rxrpc_input_implicit_end_call(rx, conn, call);
1357                         call = NULL;
1358                 }
1359
1360                 if (call) {
1361                         if (sp->hdr.serviceId != call->service_id)
1362                                 call->service_id = sp->hdr.serviceId;
1363                         if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
1364                                 call->rx_serial = sp->hdr.serial;
1365                         if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
1366                                 set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
1367                 }
1368         }
1369
1370         if (!call || atomic_read(&call->usage) == 0) {
1371                 if (rxrpc_to_client(sp) ||
1372                     sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1373                         goto bad_message;
1374                 if (sp->hdr.seq != 1)
1375                         goto discard;
1376                 call = rxrpc_new_incoming_call(local, rx, skb);
1377                 if (!call)
1378                         goto reject_packet;
1379                 rxrpc_send_ping(call, skb, skew);
1380                 mutex_unlock(&call->user_mutex);
1381         }
1382
1383         rxrpc_input_call_packet(call, skb, skew);
1384         goto discard;
1385
1386 discard:
1387         rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1388 out:
1389         trace_rxrpc_rx_done(0, 0);
1390         return 0;
1391
1392 wrong_security:
1393         trace_rxrpc_abort(0, "SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1394                           RXKADINCONSISTENCY, EBADMSG);
1395         skb->priority = RXKADINCONSISTENCY;
1396         goto post_abort;
1397
1398 unsupported_service:
1399         trace_rxrpc_abort(0, "INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1400                           RX_INVALID_OPERATION, EOPNOTSUPP);
1401         skb->priority = RX_INVALID_OPERATION;
1402         goto post_abort;
1403
1404 reupgrade:
1405         trace_rxrpc_abort(0, "UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1406                           RX_PROTOCOL_ERROR, EBADMSG);
1407         goto protocol_error;
1408
1409 bad_message:
1410         trace_rxrpc_abort(0, "BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1411                           RX_PROTOCOL_ERROR, EBADMSG);
1412 protocol_error:
1413         skb->priority = RX_PROTOCOL_ERROR;
1414 post_abort:
1415         skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
1416 reject_packet:
1417         trace_rxrpc_rx_done(skb->mark, skb->priority);
1418         rxrpc_reject_packet(local, skb);
1419         _leave(" [badmsg]");
1420         return 0;
1421 }