net/rxrpc/input.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* RxRPC packet reception
   3  *
   4  * Copyright (C) 2007, 2016 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/net.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/errqueue.h>
  14 #include <linux/udp.h>
  15 #include <linux/in.h>
  16 #include <linux/in6.h>
  17 #include <linux/icmp.h>
  18 #include <linux/gfp.h>
  19 #include <net/sock.h>
  20 #include <net/af_rxrpc.h>
  21 #include <net/ip.h>
  22 #include <net/udp.h>
  23 #include <net/net_namespace.h>
  24 #include "ar-internal.h"
  25
  26 static void rxrpc_proto_abort(const char *why,
  27                               struct rxrpc_call *call, rxrpc_seq_t seq)
  28 {
  29         if (rxrpc_abort_call(why, call, seq, RX_PROTOCOL_ERROR, -EBADMSG)) {
  30                 set_bit(RXRPC_CALL_EV_ABORT, &call->events);
  31                 rxrpc_queue_call(call);
  32         }
  33 }
  34
  35 /*
  36  * Do TCP-style congestion management [RFC 5681].
  37  */
  38 static void rxrpc_congestion_management(struct rxrpc_call *call,
  39                                         struct sk_buff *skb,
  40                                         struct rxrpc_ack_summary *summary,
  41                                         rxrpc_serial_t acked_serial)
  42 {
  43         enum rxrpc_congest_change change = rxrpc_cong_no_change;
  44         unsigned int cumulative_acks = call->cong_cumul_acks;
  45         unsigned int cwnd = call->cong_cwnd;
  46         bool resend = false;
  47
  48         summary->flight_size =
  49                 (call->tx_top - call->tx_hard_ack) - summary->nr_acks;
  50
  51         if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
  52                 summary->retrans_timeo = true;
  53                 call->cong_ssthresh = max_t(unsigned int,
  54                                             summary->flight_size / 2, 2);
  55                 cwnd = 1;
  56                 if (cwnd >= call->cong_ssthresh &&
  57                     call->cong_mode == RXRPC_CALL_SLOW_START) {
  58                         call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
  59                         call->cong_tstamp = skb->tstamp;
  60                         cumulative_acks = 0;
  61                 }
  62         }
  63
  64         cumulative_acks += summary->nr_new_acks;
  65         cumulative_acks += summary->nr_rot_new_acks;
  66         if (cumulative_acks > 255)
  67                 cumulative_acks = 255;
  68
  69         summary->mode = call->cong_mode;
  70         summary->cwnd = call->cong_cwnd;
  71         summary->ssthresh = call->cong_ssthresh;
  72         summary->cumulative_acks = cumulative_acks;
  73         summary->dup_acks = call->cong_dup_acks;
  74
  75         switch (call->cong_mode) {
  76         case RXRPC_CALL_SLOW_START:
  77                 if (summary->nr_nacks > 0)
  78                         goto packet_loss_detected;
  79                 if (summary->cumulative_acks > 0)
  80                         cwnd += 1;
  81                 if (cwnd >= call->cong_ssthresh) {
  82                         call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
  83                         call->cong_tstamp = skb->tstamp;
  84                 }
  85                 goto out;
  86
  87         case RXRPC_CALL_CONGEST_AVOIDANCE:
  88                 if (summary->nr_nacks > 0)
  89                         goto packet_loss_detected;
  90
  91                 /* We analyse the number of packets that get ACK'd per RTT
  92                  * period and increase the window if we managed to fill it.
  93                  */
  94                 if (call->peer->rtt_usage == 0)
  95                         goto out;
  96                 if (ktime_before(skb->tstamp,
  97                                  ktime_add_ns(call->cong_tstamp,
  98                                               call->peer->rtt)))
  99                         goto out_no_clear_ca;
 100                 change = rxrpc_cong_rtt_window_end;
 101                 call->cong_tstamp = skb->tstamp;
 102                 if (cumulative_acks >= cwnd)
 103                         cwnd++;
 104                 goto out;
 105
 106         case RXRPC_CALL_PACKET_LOSS:
 107                 if (summary->nr_nacks == 0)
 108                         goto resume_normality;
 109
 110                 if (summary->new_low_nack) {
 111                         change = rxrpc_cong_new_low_nack;
 112                         call->cong_dup_acks = 1;
 113                         if (call->cong_extra > 1)
 114                                 call->cong_extra = 1;
 115                         goto send_extra_data;
 116                 }
 117
 118                 call->cong_dup_acks++;
 119                 if (call->cong_dup_acks < 3)
 120                         goto send_extra_data;
 121
 122                 change = rxrpc_cong_begin_retransmission;
 123                 call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT;
 124                 call->cong_ssthresh = max_t(unsigned int,
 125                                             summary->flight_size / 2, 2);
 126                 cwnd = call->cong_ssthresh + 3;
 127                 call->cong_extra = 0;
 128                 call->cong_dup_acks = 0;
 129                 resend = true;
 130                 goto out;
 131
 132         case RXRPC_CALL_FAST_RETRANSMIT:
 133                 if (!summary->new_low_nack) {
 134                         if (summary->nr_new_acks == 0)
 135                                 cwnd += 1;
 136                         call->cong_dup_acks++;
 137                         if (call->cong_dup_acks == 2) {
 138                                 change = rxrpc_cong_retransmit_again;
 139                                 call->cong_dup_acks = 0;
 140                                 resend = true;
 141                         }
 142                 } else {
 143                         change = rxrpc_cong_progress;
 144                         cwnd = call->cong_ssthresh;
 145                         if (summary->nr_nacks == 0)
 146                                 goto resume_normality;
 147                 }
 148                 goto out;
 149
 150         default:
 151                 BUG();
 152                 goto out;
 153         }
 154
 155 resume_normality:
 156         change = rxrpc_cong_cleared_nacks;
 157         call->cong_dup_acks = 0;
 158         call->cong_extra = 0;
 159         call->cong_tstamp = skb->tstamp;
 160         if (cwnd < call->cong_ssthresh)
 161                 call->cong_mode = RXRPC_CALL_SLOW_START;
 162         else
 163                 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 164 out:
 165         cumulative_acks = 0;
 166 out_no_clear_ca:
 167         if (cwnd >= RXRPC_RXTX_BUFF_SIZE - 1)
 168                 cwnd = RXRPC_RXTX_BUFF_SIZE - 1;
 169         call->cong_cwnd = cwnd;
 170         call->cong_cumul_acks = cumulative_acks;
 171         trace_rxrpc_congest(call, summary, acked_serial, change);
 172         if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 173                 rxrpc_queue_call(call);
 174         return;
 175
 176 packet_loss_detected:
 177         change = rxrpc_cong_saw_nack;
 178         call->cong_mode = RXRPC_CALL_PACKET_LOSS;
 179         call->cong_dup_acks = 0;
 180         goto send_extra_data;
 181
 182 send_extra_data:
 183         /* Send some previously unsent DATA if we have some to advance the ACK
 184          * state.
 185          */
 186         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 187             RXRPC_TX_ANNO_LAST ||
 188             summary->nr_acks != call->tx_top - call->tx_hard_ack) {
 189                 call->cong_extra++;
 190                 wake_up(&call->waitq);
 191         }
 192         goto out_no_clear_ca;
 193 }
 194
 195 /*
 196  * Ping the other end to fill our RTT cache and to retrieve the rwind
 197  * and MTU parameters.
 198  */
 199 static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb)
 200 {
 201         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 202         ktime_t now = skb->tstamp;
 203
 204         if (call->peer->rtt_usage < 3 ||
 205             ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
 206                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
 207                                   true, true,
 208                                   rxrpc_propose_ack_ping_for_params);
 209 }
 210
 211 /*
 212  * Apply a hard ACK by advancing the Tx window.
 213  */
 214 static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
 215                                    struct rxrpc_ack_summary *summary)
 216 {
 217         struct sk_buff *skb, *list = NULL;
 218         bool rot_last = false;
 219         int ix;
 220         u8 annotation;
 221
 222         if (call->acks_lowest_nak == call->tx_hard_ack) {
 223                 call->acks_lowest_nak = to;
 224         } else if (before_eq(call->acks_lowest_nak, to)) {
 225                 summary->new_low_nack = true;
 226                 call->acks_lowest_nak = to;
 227         }
 228
 229         spin_lock(&call->lock);
 230
 231         while (before(call->tx_hard_ack, to)) {
 232                 call->tx_hard_ack++;
 233                 ix = call->tx_hard_ack & RXRPC_RXTX_BUFF_MASK;
 234                 skb = call->rxtx_buffer[ix];
 235                 annotation = call->rxtx_annotations[ix];
 236                 rxrpc_see_skb(skb, rxrpc_skb_tx_rotated);
 237                 call->rxtx_buffer[ix] = NULL;
 238                 call->rxtx_annotations[ix] = 0;
 239                 skb->next = list;
 240                 list = skb;
 241
 242                 if (annotation & RXRPC_TX_ANNO_LAST) {
 243                         set_bit(RXRPC_CALL_TX_LAST, &call->flags);
 244                         rot_last = true;
 245                 }
 246                 if ((annotation & RXRPC_TX_ANNO_MASK) != RXRPC_TX_ANNO_ACK)
 247                         summary->nr_rot_new_acks++;
 248         }
 249
 250         spin_unlock(&call->lock);
 251
 252         trace_rxrpc_transmit(call, (rot_last ?
 253                                     rxrpc_transmit_rotate_last :
 254                                     rxrpc_transmit_rotate));
 255         wake_up(&call->waitq);
 256
 257         while (list) {
 258                 skb = list;
 259                 list = skb->next;
 260                 skb_mark_not_on_list(skb);
 261                 rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
 262         }
 263
 264         return rot_last;
 265 }
 266
 267 /*
 268  * End the transmission phase of a call.
 269  *
 270  * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
 271  * or a final ACK packet.
 272  */
 273 static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
 274                                const char *abort_why)
 275 {
 276         unsigned int state;
 277
 278         ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
 279
 280         write_lock(&call->state_lock);
 281
 282         state = call->state;
 283         switch (state) {
 284         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 285         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 286                 if (reply_begun)
 287                         call->state = state = RXRPC_CALL_CLIENT_RECV_REPLY;
 288                 else
 289                         call->state = state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
 290                 break;
 291
 292         case RXRPC_CALL_SERVER_AWAIT_ACK:
 293                 __rxrpc_call_completed(call);
 294                 rxrpc_notify_socket(call);
 295                 state = call->state;
 296                 break;
 297
 298         default:
 299                 goto bad_state;
 300         }
 301
 302         write_unlock(&call->state_lock);
 303         if (state == RXRPC_CALL_CLIENT_AWAIT_REPLY)
 304                 trace_rxrpc_transmit(call, rxrpc_transmit_await_reply);
 305         else
 306                 trace_rxrpc_transmit(call, rxrpc_transmit_end);
 307         _leave(" = ok");
 308         return true;
 309
 310 bad_state:
 311         write_unlock(&call->state_lock);
 312         kdebug("end_tx %s", rxrpc_call_states[call->state]);
 313         rxrpc_proto_abort(abort_why, call, call->tx_top);
 314         return false;
 315 }
 316
 317 /*
 318  * Begin the reply reception phase of a call.
 319  */
 320 static bool rxrpc_receiving_reply(struct rxrpc_call *call)
 321 {
 322         struct rxrpc_ack_summary summary = { 0 };
 323         unsigned long now, timo;
 324         rxrpc_seq_t top = READ_ONCE(call->tx_top);
 325
 326         if (call->ackr_reason) {
 327                 spin_lock_bh(&call->lock);
 328                 call->ackr_reason = 0;
 329                 spin_unlock_bh(&call->lock);
 330                 now = jiffies;
 331                 timo = now + MAX_JIFFY_OFFSET;
 332                 WRITE_ONCE(call->resend_at, timo);
 333                 WRITE_ONCE(call->ack_at, timo);
 334                 trace_rxrpc_timer(call, rxrpc_timer_init_for_reply, now);
 335         }
 336
 337         if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
 338                 if (!rxrpc_rotate_tx_window(call, top, &summary)) {
 339                         rxrpc_proto_abort("TXL", call, top);
 340                         return false;
 341                 }
 342         }
 343         if (!rxrpc_end_tx_phase(call, true, "ETD"))
 344                 return false;
 345         call->tx_phase = false;
 346         return true;
 347 }
 348
 349 /*
 350  * Scan a jumbo packet to validate its structure and to work out how many
 351  * subpackets it contains.
 352  *
 353  * A jumbo packet is a collection of consecutive packets glued together with
 354  * little headers between that indicate how to change the initial header for
 355  * each subpacket.
 356  *
 357  * RXRPC_JUMBO_PACKET must be set on all but the last subpacket - and all but
 358  * the last are RXRPC_JUMBO_DATALEN in size.  The last subpacket may be of any
 359  * size.
 360  */
 361 static bool rxrpc_validate_jumbo(struct sk_buff *skb)
 362 {
 363         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 364         unsigned int offset = sizeof(struct rxrpc_wire_header);
 365         unsigned int len = skb->len;
 366         int nr_jumbo = 1;
 367         u8 flags = sp->hdr.flags;
 368
 369         do {
 370                 nr_jumbo++;
 371                 if (len - offset < RXRPC_JUMBO_SUBPKTLEN)
 372                         goto protocol_error;
 373                 if (flags & RXRPC_LAST_PACKET)
 374                         goto protocol_error;
 375                 offset += RXRPC_JUMBO_DATALEN;
 376                 if (skb_copy_bits(skb, offset, &flags, 1) < 0)
 377                         goto protocol_error;
 378                 offset += sizeof(struct rxrpc_jumbo_header);
 379         } while (flags & RXRPC_JUMBO_PACKET);
 380
 381         sp->nr_jumbo = nr_jumbo;
 382         return true;
 383
 384 protocol_error:
 385         return false;
 386 }
 387
 388 /*
 389  * Handle reception of a duplicate packet.
 390  *
 391  * We have to take care to avoid an attack here whereby we're given a series of
 392  * jumbograms, each with a sequence number one before the preceding one and
 393  * filled up to maximum UDP size.  If they never send us the first packet in
 394  * the sequence, they can cause us to have to hold on to around 2MiB of kernel
 395  * space until the call times out.
 396  *
 397  * We limit the space usage by only accepting three duplicate jumbo packets per
 398  * call.  After that, we tell the other side we're no longer accepting jumbos
 399  * (that information is encoded in the ACK packet).
 400  */
 401 static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
 402                                  u8 annotation, bool *_jumbo_bad)
 403 {
 404         /* Discard normal packets that are duplicates. */
 405         if (annotation == 0)
 406                 return;
 407
 408         /* Skip jumbo subpackets that are duplicates.  When we've had three or
 409          * more partially duplicate jumbo packets, we refuse to take any more
 410          * jumbos for this call.
 411          */
 412         if (!*_jumbo_bad) {
 413                 call->nr_jumbo_bad++;
 414                 *_jumbo_bad = true;
 415         }
 416 }
 417
 418 /*
 419  * Process a DATA packet, adding the packet to the Rx ring.
 420  */
 421 static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
 422 {
 423         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 424         enum rxrpc_call_state state;
 425         unsigned int offset = sizeof(struct rxrpc_wire_header);
 426         unsigned int ix;
 427         rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
 428         rxrpc_seq_t seq = sp->hdr.seq, hard_ack;
 429         bool immediate_ack = false, jumbo_bad = false, queued;
 430         u16 len;
 431         u8 ack = 0, flags, annotation = 0;
 432
 433         _enter("{%u,%u},{%u,%u}",
 434                call->rx_hard_ack, call->rx_top, skb->len, seq);
 435
 436         _proto("Rx DATA %%%u { #%u f=%02x }",
 437                sp->hdr.serial, seq, sp->hdr.flags);
 438
 439         state = READ_ONCE(call->state);
 440         if (state >= RXRPC_CALL_COMPLETE)
 441                 return;
 442
 443         if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST) {
 444                 unsigned long timo = READ_ONCE(call->next_req_timo);
 445                 unsigned long now, expect_req_by;
 446
 447                 if (timo) {
 448                         now = jiffies;
 449                         expect_req_by = now + timo;
 450                         WRITE_ONCE(call->expect_req_by, expect_req_by);
 451                         rxrpc_reduce_call_timer(call, expect_req_by, now,
 452                                                 rxrpc_timer_set_for_idle);
 453                 }
 454         }
 455
 456         spin_lock(&call->input_lock);
 457
 458         /* Received data implicitly ACKs all of the request packets we sent
 459          * when we're acting as a client.
 460          */
 461         if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
 462              state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
 463             !rxrpc_receiving_reply(call))
 464                 goto unlock;
 465
 466         call->ackr_prev_seq = seq;
 467
 468         hard_ack = READ_ONCE(call->rx_hard_ack);
 469         if (after(seq, hard_ack + call->rx_winsize)) {
 470                 ack = RXRPC_ACK_EXCEEDS_WINDOW;
 471                 ack_serial = serial;
 472                 goto ack;
 473         }
 474
 475         flags = sp->hdr.flags;
 476         if (flags & RXRPC_JUMBO_PACKET) {
 477                 if (call->nr_jumbo_bad > 3) {
 478                         ack = RXRPC_ACK_NOSPACE;
 479                         ack_serial = serial;
 480                         goto ack;
 481                 }
 482                 annotation = 1;
 483         }
 484
 485 next_subpacket:
 486         queued = false;
 487         ix = seq & RXRPC_RXTX_BUFF_MASK;
 488         len = skb->len;
 489         if (flags & RXRPC_JUMBO_PACKET)
 490                 len = RXRPC_JUMBO_DATALEN;
 491
 492         if (flags & RXRPC_LAST_PACKET) {
 493                 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 494                     seq != call->rx_top) {
 495                         rxrpc_proto_abort("LSN", call, seq);
 496                         goto unlock;
 497                 }
 498         } else {
 499                 if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 500                     after_eq(seq, call->rx_top)) {
 501                         rxrpc_proto_abort("LSA", call, seq);
 502                         goto unlock;
 503                 }
 504         }
 505
 506         trace_rxrpc_rx_data(call->debug_id, seq, serial, flags, annotation);
 507         if (before_eq(seq, hard_ack)) {
 508                 ack = RXRPC_ACK_DUPLICATE;
 509                 ack_serial = serial;
 510                 goto skip;
 511         }
 512
 513         if (flags & RXRPC_REQUEST_ACK && !ack) {
 514                 ack = RXRPC_ACK_REQUESTED;
 515                 ack_serial = serial;
 516         }
 517
 518         if (call->rxtx_buffer[ix]) {
 519                 rxrpc_input_dup_data(call, seq, annotation, &jumbo_bad);
 520                 if (ack != RXRPC_ACK_DUPLICATE) {
 521                         ack = RXRPC_ACK_DUPLICATE;
 522                         ack_serial = serial;
 523                 }
 524                 immediate_ack = true;
 525                 goto skip;
 526         }
 527
 528         /* Queue the packet.  We use a couple of memory barriers here as need
 529          * to make sure that rx_top is perceived to be set after the buffer
 530          * pointer and that the buffer pointer is set after the annotation and
 531          * the skb data.
 532          *
 533          * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
 534          * and also rxrpc_fill_out_ack().
 535          */
 536         rxrpc_get_skb(skb, rxrpc_skb_rx_got);
 537         call->rxtx_annotations[ix] = annotation;
 538         smp_wmb();
 539         call->rxtx_buffer[ix] = skb;
 540         if (after(seq, call->rx_top)) {
 541                 smp_store_release(&call->rx_top, seq);
 542         } else if (before(seq, call->rx_top)) {
 543                 /* Send an immediate ACK if we fill in a hole */
 544                 if (!ack) {
 545                         ack = RXRPC_ACK_DELAY;
 546                         ack_serial = serial;
 547                 }
 548                 immediate_ack = true;
 549         }
 550         if (flags & RXRPC_LAST_PACKET) {
 551                 set_bit(RXRPC_CALL_RX_LAST, &call->flags);
 552                 trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
 553         } else {
 554                 trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
 555         }
 556         queued = true;
 557
 558         if (after_eq(seq, call->rx_expect_next)) {
 559                 if (after(seq, call->rx_expect_next)) {
 560                         _net("OOS %u > %u", seq, call->rx_expect_next);
 561                         ack = RXRPC_ACK_OUT_OF_SEQUENCE;
 562                         ack_serial = serial;
 563                 }
 564                 call->rx_expect_next = seq + 1;
 565         }
 566
 567 skip:
 568         offset += len;
 569         if (flags & RXRPC_JUMBO_PACKET) {
 570                 if (skb_copy_bits(skb, offset, &flags, 1) < 0) {
 571                         rxrpc_proto_abort("XJF", call, seq);
 572                         goto unlock;
 573                 }
 574                 offset += sizeof(struct rxrpc_jumbo_header);
 575                 seq++;
 576                 serial++;
 577                 annotation++;
 578                 if (flags & RXRPC_JUMBO_PACKET)
 579                         annotation |= RXRPC_RX_ANNO_JLAST;
 580                 if (after(seq, hard_ack + call->rx_winsize)) {
 581                         ack = RXRPC_ACK_EXCEEDS_WINDOW;
 582                         ack_serial = serial;
 583                         if (!jumbo_bad) {
 584                                 call->nr_jumbo_bad++;
 585                                 jumbo_bad = true;
 586                         }
 587                         goto ack;
 588                 }
 589
 590                 _proto("Rx DATA Jumbo %%%u", serial);
 591                 goto next_subpacket;
 592         }
 593
 594         if (queued && flags & RXRPC_LAST_PACKET && !ack) {
 595                 ack = RXRPC_ACK_DELAY;
 596                 ack_serial = serial;
 597         }
 598
 599 ack:
 600         if (ack)
 601                 rxrpc_propose_ACK(call, ack, ack_serial,
 602                                   immediate_ack, true,
 603                                   rxrpc_propose_ack_input_data);
 604         else
 605                 rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial,
 606                                   false, true,
 607                                   rxrpc_propose_ack_input_data);
 608
 609         if (sp->hdr.seq == READ_ONCE(call->rx_hard_ack) + 1) {
 610                 trace_rxrpc_notify_socket(call->debug_id, serial);
 611                 rxrpc_notify_socket(call);
 612         }
 613
 614 unlock:
 615         spin_unlock(&call->input_lock);
 616         _leave(" [queued]");
 617 }
 618
 619 /*
 620  * Process a requested ACK.
 621  */
 622 static void rxrpc_input_requested_ack(struct rxrpc_call *call,
 623                                       ktime_t resp_time,
 624                                       rxrpc_serial_t orig_serial,
 625                                       rxrpc_serial_t ack_serial)
 626 {
 627         struct rxrpc_skb_priv *sp;
 628         struct sk_buff *skb;
 629         ktime_t sent_at;
 630         int ix;
 631
 632         for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
 633                 skb = call->rxtx_buffer[ix];
 634                 if (!skb)
 635                         continue;
 636
 637                 sent_at = skb->tstamp;
 638                 smp_rmb(); /* Read timestamp before serial. */
 639                 sp = rxrpc_skb(skb);
 640                 if (sp->hdr.serial != orig_serial)
 641                         continue;
 642                 goto found;
 643         }
 644
 645         return;
 646
 647 found:
 648         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
 649                            orig_serial, ack_serial, sent_at, resp_time);
 650 }
 651
 652 /*
 653  * Process the response to a ping that we sent to find out if we lost an ACK.
 654  *
 655  * If we got back a ping response that indicates a lower tx_top than what we
 656  * had at the time of the ping transmission, we adjudge all the DATA packets
 657  * sent between the response tx_top and the ping-time tx_top to have been lost.
 658  */
 659 static void rxrpc_input_check_for_lost_ack(struct rxrpc_call *call)
 660 {
 661         rxrpc_seq_t top, bottom, seq;
 662         bool resend = false;
 663
 664         spin_lock_bh(&call->lock);
 665
 666         bottom = call->tx_hard_ack + 1;
 667         top = call->acks_lost_top;
 668         if (before(bottom, top)) {
 669                 for (seq = bottom; before_eq(seq, top); seq++) {
 670                         int ix = seq & RXRPC_RXTX_BUFF_MASK;
 671                         u8 annotation = call->rxtx_annotations[ix];
 672                         u8 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 673
 674                         if (anno_type != RXRPC_TX_ANNO_UNACK)
 675                                 continue;
 676                         annotation &= ~RXRPC_TX_ANNO_MASK;
 677                         annotation |= RXRPC_TX_ANNO_RETRANS;
 678                         call->rxtx_annotations[ix] = annotation;
 679                         resend = true;
 680                 }
 681         }
 682
 683         spin_unlock_bh(&call->lock);
 684
 685         if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 686                 rxrpc_queue_call(call);
 687 }
 688
 689 /*
 690  * Process a ping response.
 691  */
 692 static void rxrpc_input_ping_response(struct rxrpc_call *call,
 693                                       ktime_t resp_time,
 694                                       rxrpc_serial_t orig_serial,
 695                                       rxrpc_serial_t ack_serial)
 696 {
 697         rxrpc_serial_t ping_serial;
 698         ktime_t ping_time;
 699
 700         ping_time = call->ping_time;
 701         smp_rmb();
 702         ping_serial = READ_ONCE(call->ping_serial);
 703
 704         if (orig_serial == call->acks_lost_ping)
 705                 rxrpc_input_check_for_lost_ack(call);
 706
 707         if (before(orig_serial, ping_serial) ||
 708             !test_and_clear_bit(RXRPC_CALL_PINGING, &call->flags))
 709                 return;
 710         if (after(orig_serial, ping_serial))
 711                 return;
 712
 713         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
 714                            orig_serial, ack_serial, ping_time, resp_time);
 715 }
 716
 717 /*
 718  * Process the extra information that may be appended to an ACK packet
 719  */
 720 static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 721                                 struct rxrpc_ackinfo *ackinfo)
 722 {
 723         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 724         struct rxrpc_peer *peer;
 725         unsigned int mtu;
 726         bool wake = false;
 727         u32 rwind = ntohl(ackinfo->rwind);
 728
 729         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 730                sp->hdr.serial,
 731                ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
 732                rwind, ntohl(ackinfo->jumbo_max));
 733
 734         if (call->tx_winsize != rwind) {
 735                 if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
 736                         rwind = RXRPC_RXTX_BUFF_SIZE - 1;
 737                 if (rwind > call->tx_winsize)
 738                         wake = true;
 739                 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial,
 740                                             ntohl(ackinfo->rwind), wake);
 741                 call->tx_winsize = rwind;
 742         }
 743
 744         if (call->cong_ssthresh > rwind)
 745                 call->cong_ssthresh = rwind;
 746
 747         mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
 748
 749         peer = call->peer;
 750         if (mtu < peer->maxdata) {
 751                 spin_lock_bh(&peer->lock);
 752                 peer->maxdata = mtu;
 753                 peer->mtu = mtu + peer->hdrsize;
 754                 spin_unlock_bh(&peer->lock);
 755                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 756         }
 757
 758         if (wake)
 759                 wake_up(&call->waitq);
 760 }
 761
 762 /*
 763  * Process individual soft ACKs.
 764  *
 765  * Each ACK in the array corresponds to one packet and can be either an ACK or
 766  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 767  * packets that lie beyond the end of the ACK list are scheduled for resend by
 768  * the timer on the basis that the peer might just not have processed them at
 769  * the time the ACK was sent.
 770  */
 771 static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 772                                   rxrpc_seq_t seq, int nr_acks,
 773                                   struct rxrpc_ack_summary *summary)
 774 {
 775         int ix;
 776         u8 annotation, anno_type;
 777
 778         for (; nr_acks > 0; nr_acks--, seq++) {
 779                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 780                 annotation = call->rxtx_annotations[ix];
 781                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 782                 annotation &= ~RXRPC_TX_ANNO_MASK;
 783                 switch (*acks++) {
 784                 case RXRPC_ACK_TYPE_ACK:
 785                         summary->nr_acks++;
 786                         if (anno_type == RXRPC_TX_ANNO_ACK)
 787                                 continue;
 788                         summary->nr_new_acks++;
 789                         call->rxtx_annotations[ix] =
 790                                 RXRPC_TX_ANNO_ACK | annotation;
 791                         break;
 792                 case RXRPC_ACK_TYPE_NACK:
 793                         if (!summary->nr_nacks &&
 794                             call->acks_lowest_nak != seq) {
 795                                 call->acks_lowest_nak = seq;
 796                                 summary->new_low_nack = true;
 797                         }
 798                         summary->nr_nacks++;
 799                         if (anno_type == RXRPC_TX_ANNO_NAK)
 800                                 continue;
 801                         summary->nr_new_nacks++;
 802                         if (anno_type == RXRPC_TX_ANNO_RETRANS)
 803                                 continue;
 804                         call->rxtx_annotations[ix] =
 805                                 RXRPC_TX_ANNO_NAK | annotation;
 806                         break;
 807                 default:
 808                         return rxrpc_proto_abort("SFT", call, 0);
 809                 }
 810         }
 811 }
 812
 813 /*
 814  * Process an ACK packet.
 815  *
 816  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 817  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 818  *
 819  * A hard-ACK means that a packet has been processed and may be discarded; a
 820  * soft-ACK means that the packet may be discarded and retransmission
 821  * requested.  A phase is complete when all packets are hard-ACK'd.
 822  */
 823 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 824 {
 825         struct rxrpc_ack_summary summary = { 0 };
 826         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 827         union {
 828                 struct rxrpc_ackpacket ack;
 829                 struct rxrpc_ackinfo info;
 830                 u8 acks[RXRPC_MAXACKS];
 831         } buf;
 832         rxrpc_serial_t acked_serial;
 833         rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
 834         int nr_acks, offset, ioffset;
 835
 836         _enter("");
 837
 838         offset = sizeof(struct rxrpc_wire_header);
 839         if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
 840                 _debug("extraction failure");
 841                 return rxrpc_proto_abort("XAK", call, 0);
 842         }
 843         offset += sizeof(buf.ack);
 844
 845         acked_serial = ntohl(buf.ack.serial);
 846         first_soft_ack = ntohl(buf.ack.firstPacket);
 847         prev_pkt = ntohl(buf.ack.previousPacket);
 848         hard_ack = first_soft_ack - 1;
 849         nr_acks = buf.ack.nAcks;
 850         summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
 851                               buf.ack.reason : RXRPC_ACK__INVALID);
 852
 853         trace_rxrpc_rx_ack(call, sp->hdr.serial, acked_serial,
 854                            first_soft_ack, prev_pkt,
 855                            summary.ack_reason, nr_acks);
 856
 857         if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
 858                 rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
 859                                           sp->hdr.serial);
 860         if (buf.ack.reason == RXRPC_ACK_REQUESTED)
 861                 rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
 862                                           sp->hdr.serial);
 863
 864         if (buf.ack.reason == RXRPC_ACK_PING) {
 865                 _proto("Rx ACK %%%u PING Request", sp->hdr.serial);
 866                 rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 867                                   sp->hdr.serial, true, true,
 868                                   rxrpc_propose_ack_respond_to_ping);
 869         } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 870                 rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 871                                   sp->hdr.serial, true, true,
 872                                   rxrpc_propose_ack_respond_to_ack);
 873         }
 874
 875         /* Discard any out-of-order or duplicate ACKs (outside lock). */
 876         if (before(first_soft_ack, call->ackr_first_seq) ||
 877             before(prev_pkt, call->ackr_prev_seq))
 878                 return;
 879
 880         buf.info.rxMTU = 0;
 881         ioffset = offset + nr_acks + 3;
 882         if (skb->len >= ioffset + sizeof(buf.info) &&
 883             skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
 884                 return rxrpc_proto_abort("XAI", call, 0);
 885
 886         spin_lock(&call->input_lock);
 887
 888         /* Discard any out-of-order or duplicate ACKs (inside lock). */
 889         if (before(first_soft_ack, call->ackr_first_seq) ||
 890             before(prev_pkt, call->ackr_prev_seq))
 891                 goto out;
 892         call->acks_latest_ts = skb->tstamp;
 893         call->acks_latest = sp->hdr.serial;
 894
 895         call->ackr_first_seq = first_soft_ack;
 896         call->ackr_prev_seq = prev_pkt;
 897
 898         /* Parse rwind and mtu sizes if provided. */
 899         if (buf.info.rxMTU)
 900                 rxrpc_input_ackinfo(call, skb, &buf.info);
 901
 902         if (first_soft_ack == 0) {
 903                 rxrpc_proto_abort("AK0", call, 0);
 904                 goto out;
 905         }
 906
 907         /* Ignore ACKs unless we are or have just been transmitting. */
 908         switch (READ_ONCE(call->state)) {
 909         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 910         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 911         case RXRPC_CALL_SERVER_SEND_REPLY:
 912         case RXRPC_CALL_SERVER_AWAIT_ACK:
 913                 break;
 914         default:
 915                 goto out;
 916         }
 917
 918         if (before(hard_ack, call->tx_hard_ack) ||
 919             after(hard_ack, call->tx_top)) {
 920                 rxrpc_proto_abort("AKW", call, 0);
 921                 goto out;
 922         }
 923         if (nr_acks > call->tx_top - hard_ack) {
 924                 rxrpc_proto_abort("AKN", call, 0);
 925                 goto out;
 926         }
 927
 928         if (after(hard_ack, call->tx_hard_ack)) {
 929                 if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
 930                         rxrpc_end_tx_phase(call, false, "ETA");
 931                         goto out;
 932                 }
 933         }
 934
 935         if (nr_acks > 0) {
 936                 if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0) {
 937                         rxrpc_proto_abort("XSA", call, 0);
 938                         goto out;
 939                 }
 940                 rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
 941                                       &summary);
 942         }
 943
 944         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 945             RXRPC_TX_ANNO_LAST &&
 946             summary.nr_acks == call->tx_top - hard_ack &&
 947             rxrpc_is_client_call(call))
 948                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
 949                                   false, true,
 950                                   rxrpc_propose_ack_ping_for_lost_reply);
 951
 952         rxrpc_congestion_management(call, skb, &summary, acked_serial);
 953 out:
 954         spin_unlock(&call->input_lock);
 955 }
 956
 957 /*
 958  * Process an ACKALL packet.
 959  */
 960 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
 961 {
 962         struct rxrpc_ack_summary summary = { 0 };
 963         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 964
 965         _proto("Rx ACKALL %%%u", sp->hdr.serial);
 966
 967         spin_lock(&call->input_lock);
 968
 969         if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
 970                 rxrpc_end_tx_phase(call, false, "ETL");
 971
 972         spin_unlock(&call->input_lock);
 973 }
 974
 975 /*
 976  * Process an ABORT packet directed at a call.
 977  */
 978 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
 979 {
 980         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 981         __be32 wtmp;
 982         u32 abort_code = RX_CALL_DEAD;
 983
 984         _enter("");
 985
 986         if (skb->len >= 4 &&
 987             skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
 988                           &wtmp, sizeof(wtmp)) >= 0)
 989                 abort_code = ntohl(wtmp);
 990
 991         trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
 992
 993         _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
 994
 995         if (rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 996                                       abort_code, -ECONNABORTED))
 997                 rxrpc_notify_socket(call);
 998 }
 999
1000 /*
1001  * Process an incoming call packet.
1002  */
1003 static void rxrpc_input_call_packet(struct rxrpc_call *call,
1004                                     struct sk_buff *skb)
1005 {
1006         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1007         unsigned long timo;
1008
1009         _enter("%p,%p", call, skb);
1010
1011         timo = READ_ONCE(call->next_rx_timo);
1012         if (timo) {
1013                 unsigned long now = jiffies, expect_rx_by;
1014
1015                 expect_rx_by = now + timo;
1016                 WRITE_ONCE(call->expect_rx_by, expect_rx_by);
1017                 rxrpc_reduce_call_timer(call, expect_rx_by, now,
1018                                         rxrpc_timer_set_for_normal);
1019         }
1020
1021         switch (sp->hdr.type) {
1022         case RXRPC_PACKET_TYPE_DATA:
1023                 rxrpc_input_data(call, skb);
1024                 break;
1025
1026         case RXRPC_PACKET_TYPE_ACK:
1027                 rxrpc_input_ack(call, skb);
1028                 break;
1029
1030         case RXRPC_PACKET_TYPE_BUSY:
1031                 _proto("Rx BUSY %%%u", sp->hdr.serial);
1032
1033                 /* Just ignore BUSY packets from the server; the retry and
1034                  * lifespan timers will take care of business.  BUSY packets
1035                  * from the client don't make sense.
1036                  */
1037                 break;
1038
1039         case RXRPC_PACKET_TYPE_ABORT:
1040                 rxrpc_input_abort(call, skb);
1041                 break;
1042
1043         case RXRPC_PACKET_TYPE_ACKALL:
1044                 rxrpc_input_ackall(call, skb);
1045                 break;
1046
1047         default:
1048                 break;
1049         }
1050
1051         _leave("");
1052 }
1053
1054 /*
1055  * Handle a new service call on a channel implicitly completing the preceding
1056  * call on that channel.  This does not apply to client conns.
1057  *
1058  * TODO: If callNumber > call_id + 1, renegotiate security.
1059  */
1060 static void rxrpc_input_implicit_end_call(struct rxrpc_sock *rx,
1061                                           struct rxrpc_connection *conn,
1062                                           struct rxrpc_call *call)
1063 {
1064         switch (READ_ONCE(call->state)) {
1065         case RXRPC_CALL_SERVER_AWAIT_ACK:
1066                 rxrpc_call_completed(call);
1067                 /* Fall through */
1068         case RXRPC_CALL_COMPLETE:
1069                 break;
1070         default:
1071                 if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
1072                         set_bit(RXRPC_CALL_EV_ABORT, &call->events);
1073                         rxrpc_queue_call(call);
1074                 }
1075                 trace_rxrpc_improper_term(call);
1076                 break;
1077         }
1078
1079         spin_lock(&rx->incoming_lock);
1080         __rxrpc_disconnect_call(conn, call);
1081         spin_unlock(&rx->incoming_lock);
1082         rxrpc_notify_socket(call);
1083 }
1084
1085 /*
1086  * post connection-level events to the connection
1087  * - this includes challenges, responses, some aborts and call terminal packet
1088  *   retransmission.
1089  */
1090 static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
1091                                       struct sk_buff *skb)
1092 {
1093         _enter("%p,%p", conn, skb);
1094
1095         skb_queue_tail(&conn->rx_queue, skb);
1096         rxrpc_queue_conn(conn);
1097 }
1098
1099 /*
1100  * post endpoint-level events to the local endpoint
1101  * - this includes debug and version messages
1102  */
1103 static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
1104                                        struct sk_buff *skb)
1105 {
1106         _enter("%p,%p", local, skb);
1107
1108         if (rxrpc_get_local_maybe(local)) {
1109                 skb_queue_tail(&local->event_queue, skb);
1110                 rxrpc_queue_local(local);
1111         } else {
1112                 rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1113         }
1114 }
1115
1116 /*
1117  * put a packet up for transport-level abort
1118  */
1119 static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
1120 {
1121         CHECK_SLAB_OKAY(&local->usage);
1122
1123         if (rxrpc_get_local_maybe(local)) {
1124                 skb_queue_tail(&local->reject_queue, skb);
1125                 rxrpc_queue_local(local);
1126         } else {
1127                 rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1128         }
1129 }
1130
1131 /*
1132  * Extract the wire header from a packet and translate the byte order.
1133  */
1134 static noinline
1135 int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
1136 {
1137         struct rxrpc_wire_header whdr;
1138
1139         /* dig out the RxRPC connection details */
1140         if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0) {
1141                 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
1142                                       tracepoint_string("bad_hdr"));
1143                 return -EBADMSG;
1144         }
1145
1146         memset(sp, 0, sizeof(*sp));
1147         sp->hdr.epoch           = ntohl(whdr.epoch);
1148         sp->hdr.cid             = ntohl(whdr.cid);
1149         sp->hdr.callNumber      = ntohl(whdr.callNumber);
1150         sp->hdr.seq             = ntohl(whdr.seq);
1151         sp->hdr.serial          = ntohl(whdr.serial);
1152         sp->hdr.flags           = whdr.flags;
1153         sp->hdr.type            = whdr.type;
1154         sp->hdr.userStatus      = whdr.userStatus;
1155         sp->hdr.securityIndex   = whdr.securityIndex;
1156         sp->hdr._rsvd           = ntohs(whdr._rsvd);
1157         sp->hdr.serviceId       = ntohs(whdr.serviceId);
1158         return 0;
1159 }
1160
1161 /*
1162  * handle data received on the local endpoint
1163  * - may be called in interrupt context
1164  *
1165  * [!] Note that as this is called from the encap_rcv hook, the socket is not
1166  * held locked by the caller and nothing prevents sk_user_data on the UDP from
1167  * being cleared in the middle of processing this function.
1168  *
1169  * Called with the RCU read lock held from the IP layer via UDP.
1170  */
1171 int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
1172 {
1173         struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
1174         struct rxrpc_connection *conn;
1175         struct rxrpc_channel *chan;
1176         struct rxrpc_call *call = NULL;
1177         struct rxrpc_skb_priv *sp;
1178         struct rxrpc_peer *peer = NULL;
1179         struct rxrpc_sock *rx = NULL;
1180         unsigned int channel;
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                 if ((int)sp->hdr.serial - (int)conn->hi_serial > 0)
1309                         conn->hi_serial = sp->hdr.serial;
1310
1311                 /* Call-bound packets are routed by connection channel. */
1312                 channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1313                 chan = &conn->channels[channel];
1314
1315                 /* Ignore really old calls */
1316                 if (sp->hdr.callNumber < chan->last_call)
1317                         goto discard;
1318
1319                 if (sp->hdr.callNumber == chan->last_call) {
1320                         if (chan->call ||
1321                             sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
1322                                 goto discard;
1323
1324                         /* For the previous service call, if completed
1325                          * successfully, we discard all further packets.
1326                          */
1327                         if (rxrpc_conn_is_service(conn) &&
1328                             chan->last_type == RXRPC_PACKET_TYPE_ACK)
1329                                 goto discard;
1330
1331                         /* But otherwise we need to retransmit the final packet
1332                          * from data cached in the connection record.
1333                          */
1334                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
1335                                 trace_rxrpc_rx_data(chan->call_debug_id,
1336                                                     sp->hdr.seq,
1337                                                     sp->hdr.serial,
1338                                                     sp->hdr.flags, 0);
1339                         rxrpc_post_packet_to_conn(conn, skb);
1340                         goto out;
1341                 }
1342
1343                 call = rcu_dereference(chan->call);
1344
1345                 if (sp->hdr.callNumber > chan->call_id) {
1346                         if (rxrpc_to_client(sp))
1347                                 goto reject_packet;
1348                         if (call)
1349                                 rxrpc_input_implicit_end_call(rx, conn, call);
1350                         call = NULL;
1351                 }
1352
1353                 if (call) {
1354                         if (sp->hdr.serviceId != call->service_id)
1355                                 call->service_id = sp->hdr.serviceId;
1356                         if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
1357                                 call->rx_serial = sp->hdr.serial;
1358                         if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
1359                                 set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
1360                 }
1361         }
1362
1363         if (!call || atomic_read(&call->usage) == 0) {
1364                 if (rxrpc_to_client(sp) ||
1365                     sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1366                         goto bad_message;
1367                 if (sp->hdr.seq != 1)
1368                         goto discard;
1369                 call = rxrpc_new_incoming_call(local, rx, skb);
1370                 if (!call)
1371                         goto reject_packet;
1372                 rxrpc_send_ping(call, skb);
1373                 mutex_unlock(&call->user_mutex);
1374         }
1375
1376         rxrpc_input_call_packet(call, skb);
1377         goto discard;
1378
1379 discard:
1380         rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1381 out:
1382         trace_rxrpc_rx_done(0, 0);
1383         return 0;
1384
1385 wrong_security:
1386         trace_rxrpc_abort(0, "SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1387                           RXKADINCONSISTENCY, EBADMSG);
1388         skb->priority = RXKADINCONSISTENCY;
1389         goto post_abort;
1390
1391 unsupported_service:
1392         trace_rxrpc_abort(0, "INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1393                           RX_INVALID_OPERATION, EOPNOTSUPP);
1394         skb->priority = RX_INVALID_OPERATION;
1395         goto post_abort;
1396
1397 reupgrade:
1398         trace_rxrpc_abort(0, "UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1399                           RX_PROTOCOL_ERROR, EBADMSG);
1400         goto protocol_error;
1401
1402 bad_message:
1403         trace_rxrpc_abort(0, "BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1404                           RX_PROTOCOL_ERROR, EBADMSG);
1405 protocol_error:
1406         skb->priority = RX_PROTOCOL_ERROR;
1407 post_abort:
1408         skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
1409 reject_packet:
1410         trace_rxrpc_rx_done(skb->mark, skb->priority);
1411         rxrpc_reject_packet(local, skb);
1412         _leave(" [badmsg]");
1413         return 0;
1414 }