net/rxrpc/input.c

   1 /* RxRPC packet reception
   2  *
   3  * Copyright (C) 2007, 2016 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/net.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/errqueue.h>
  18 #include <linux/udp.h>
  19 #include <linux/in.h>
  20 #include <linux/in6.h>
  21 #include <linux/icmp.h>
  22 #include <linux/gfp.h>
  23 #include <net/sock.h>
  24 #include <net/af_rxrpc.h>
  25 #include <net/ip.h>
  26 #include <net/udp.h>
  27 #include <net/net_namespace.h>
  28 #include "ar-internal.h"
  29
  30 static void rxrpc_proto_abort(const char *why,
  31                               struct rxrpc_call *call, rxrpc_seq_t seq)
  32 {
  33         if (rxrpc_abort_call(why, call, seq, RX_PROTOCOL_ERROR, -EBADMSG)) {
  34                 set_bit(RXRPC_CALL_EV_ABORT, &call->events);
  35                 rxrpc_queue_call(call);
  36         }
  37 }
  38
  39 /*
  40  * Do TCP-style congestion management [RFC 5681].
  41  */
  42 static void rxrpc_congestion_management(struct rxrpc_call *call,
  43                                         struct sk_buff *skb,
  44                                         struct rxrpc_ack_summary *summary,
  45                                         rxrpc_serial_t acked_serial)
  46 {
  47         enum rxrpc_congest_change change = rxrpc_cong_no_change;
  48         unsigned int cumulative_acks = call->cong_cumul_acks;
  49         unsigned int cwnd = call->cong_cwnd;
  50         bool resend = false;
  51
  52         summary->flight_size =
  53                 (call->tx_top - call->tx_hard_ack) - summary->nr_acks;
  54
  55         if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) {
  56                 summary->retrans_timeo = true;
  57                 call->cong_ssthresh = max_t(unsigned int,
  58                                             summary->flight_size / 2, 2);
  59                 cwnd = 1;
  60                 if (cwnd >= call->cong_ssthresh &&
  61                     call->cong_mode == RXRPC_CALL_SLOW_START) {
  62                         call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
  63                         call->cong_tstamp = skb->tstamp;
  64                         cumulative_acks = 0;
  65                 }
  66         }
  67
  68         cumulative_acks += summary->nr_new_acks;
  69         cumulative_acks += summary->nr_rot_new_acks;
  70         if (cumulative_acks > 255)
  71                 cumulative_acks = 255;
  72
  73         summary->mode = call->cong_mode;
  74         summary->cwnd = call->cong_cwnd;
  75         summary->ssthresh = call->cong_ssthresh;
  76         summary->cumulative_acks = cumulative_acks;
  77         summary->dup_acks = call->cong_dup_acks;
  78
  79         switch (call->cong_mode) {
  80         case RXRPC_CALL_SLOW_START:
  81                 if (summary->nr_nacks > 0)
  82                         goto packet_loss_detected;
  83                 if (summary->cumulative_acks > 0)
  84                         cwnd += 1;
  85                 if (cwnd >= call->cong_ssthresh) {
  86                         call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
  87                         call->cong_tstamp = skb->tstamp;
  88                 }
  89                 goto out;
  90
  91         case RXRPC_CALL_CONGEST_AVOIDANCE:
  92                 if (summary->nr_nacks > 0)
  93                         goto packet_loss_detected;
  94
  95                 /* We analyse the number of packets that get ACK'd per RTT
  96                  * period and increase the window if we managed to fill it.
  97                  */
  98                 if (call->peer->rtt_usage == 0)
  99                         goto out;
 100                 if (ktime_before(skb->tstamp,
 101                                  ktime_add_ns(call->cong_tstamp,
 102                                               call->peer->rtt)))
 103                         goto out_no_clear_ca;
 104                 change = rxrpc_cong_rtt_window_end;
 105                 call->cong_tstamp = skb->tstamp;
 106                 if (cumulative_acks >= cwnd)
 107                         cwnd++;
 108                 goto out;
 109
 110         case RXRPC_CALL_PACKET_LOSS:
 111                 if (summary->nr_nacks == 0)
 112                         goto resume_normality;
 113
 114                 if (summary->new_low_nack) {
 115                         change = rxrpc_cong_new_low_nack;
 116                         call->cong_dup_acks = 1;
 117                         if (call->cong_extra > 1)
 118                                 call->cong_extra = 1;
 119                         goto send_extra_data;
 120                 }
 121
 122                 call->cong_dup_acks++;
 123                 if (call->cong_dup_acks < 3)
 124                         goto send_extra_data;
 125
 126                 change = rxrpc_cong_begin_retransmission;
 127                 call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT;
 128                 call->cong_ssthresh = max_t(unsigned int,
 129                                             summary->flight_size / 2, 2);
 130                 cwnd = call->cong_ssthresh + 3;
 131                 call->cong_extra = 0;
 132                 call->cong_dup_acks = 0;
 133                 resend = true;
 134                 goto out;
 135
 136         case RXRPC_CALL_FAST_RETRANSMIT:
 137                 if (!summary->new_low_nack) {
 138                         if (summary->nr_new_acks == 0)
 139                                 cwnd += 1;
 140                         call->cong_dup_acks++;
 141                         if (call->cong_dup_acks == 2) {
 142                                 change = rxrpc_cong_retransmit_again;
 143                                 call->cong_dup_acks = 0;
 144                                 resend = true;
 145                         }
 146                 } else {
 147                         change = rxrpc_cong_progress;
 148                         cwnd = call->cong_ssthresh;
 149                         if (summary->nr_nacks == 0)
 150                                 goto resume_normality;
 151                 }
 152                 goto out;
 153
 154         default:
 155                 BUG();
 156                 goto out;
 157         }
 158
 159 resume_normality:
 160         change = rxrpc_cong_cleared_nacks;
 161         call->cong_dup_acks = 0;
 162         call->cong_extra = 0;
 163         call->cong_tstamp = skb->tstamp;
 164         if (cwnd < call->cong_ssthresh)
 165                 call->cong_mode = RXRPC_CALL_SLOW_START;
 166         else
 167                 call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE;
 168 out:
 169         cumulative_acks = 0;
 170 out_no_clear_ca:
 171         if (cwnd >= RXRPC_RXTX_BUFF_SIZE - 1)
 172                 cwnd = RXRPC_RXTX_BUFF_SIZE - 1;
 173         call->cong_cwnd = cwnd;
 174         call->cong_cumul_acks = cumulative_acks;
 175         trace_rxrpc_congest(call, summary, acked_serial, change);
 176         if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 177                 rxrpc_queue_call(call);
 178         return;
 179
 180 packet_loss_detected:
 181         change = rxrpc_cong_saw_nack;
 182         call->cong_mode = RXRPC_CALL_PACKET_LOSS;
 183         call->cong_dup_acks = 0;
 184         goto send_extra_data;
 185
 186 send_extra_data:
 187         /* Send some previously unsent DATA if we have some to advance the ACK
 188          * state.
 189          */
 190         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 191             RXRPC_TX_ANNO_LAST ||
 192             summary->nr_acks != call->tx_top - call->tx_hard_ack) {
 193                 call->cong_extra++;
 194                 wake_up(&call->waitq);
 195         }
 196         goto out_no_clear_ca;
 197 }
 198
 199 /*
 200  * Ping the other end to fill our RTT cache and to retrieve the rwind
 201  * and MTU parameters.
 202  */
 203 static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb,
 204                             int skew)
 205 {
 206         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 207         ktime_t now = skb->tstamp;
 208
 209         if (call->peer->rtt_usage < 3 ||
 210             ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now))
 211                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
 212                                   true, true,
 213                                   rxrpc_propose_ack_ping_for_params);
 214 }
 215
 216 /*
 217  * Apply a hard ACK by advancing the Tx window.
 218  */
 219 static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
 220                                    struct rxrpc_ack_summary *summary)
 221 {
 222         struct sk_buff *skb, *list = NULL;
 223         bool rot_last = false;
 224         int ix;
 225         u8 annotation;
 226
 227         if (call->acks_lowest_nak == call->tx_hard_ack) {
 228                 call->acks_lowest_nak = to;
 229         } else if (before_eq(call->acks_lowest_nak, to)) {
 230                 summary->new_low_nack = true;
 231                 call->acks_lowest_nak = to;
 232         }
 233
 234         spin_lock(&call->lock);
 235
 236         while (before(call->tx_hard_ack, to)) {
 237                 call->tx_hard_ack++;
 238                 ix = call->tx_hard_ack & RXRPC_RXTX_BUFF_MASK;
 239                 skb = call->rxtx_buffer[ix];
 240                 annotation = call->rxtx_annotations[ix];
 241                 rxrpc_see_skb(skb, rxrpc_skb_tx_rotated);
 242                 call->rxtx_buffer[ix] = NULL;
 243                 call->rxtx_annotations[ix] = 0;
 244                 skb->next = list;
 245                 list = skb;
 246
 247                 if (annotation & RXRPC_TX_ANNO_LAST) {
 248                         set_bit(RXRPC_CALL_TX_LAST, &call->flags);
 249                         rot_last = true;
 250                 }
 251                 if ((annotation & RXRPC_TX_ANNO_MASK) != RXRPC_TX_ANNO_ACK)
 252                         summary->nr_rot_new_acks++;
 253         }
 254
 255         spin_unlock(&call->lock);
 256
 257         trace_rxrpc_transmit(call, (rot_last ?
 258                                     rxrpc_transmit_rotate_last :
 259                                     rxrpc_transmit_rotate));
 260         wake_up(&call->waitq);
 261
 262         while (list) {
 263                 skb = list;
 264                 list = skb->next;
 265                 skb->next = NULL;
 266                 rxrpc_free_skb(skb, rxrpc_skb_tx_freed);
 267         }
 268
 269         return rot_last;
 270 }
 271
 272 /*
 273  * End the transmission phase of a call.
 274  *
 275  * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
 276  * or a final ACK packet.
 277  */
 278 static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
 279                                const char *abort_why)
 280 {
 281         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 (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         trace_rxrpc_notify_socket(call->debug_id, serial);
 616         rxrpc_notify_socket(call);
 617
 618 unlock:
 619         spin_unlock(&call->input_lock);
 620         _leave(" [queued]");
 621 }
 622
 623 /*
 624  * Process a requested ACK.
 625  */
 626 static void rxrpc_input_requested_ack(struct rxrpc_call *call,
 627                                       ktime_t resp_time,
 628                                       rxrpc_serial_t orig_serial,
 629                                       rxrpc_serial_t ack_serial)
 630 {
 631         struct rxrpc_skb_priv *sp;
 632         struct sk_buff *skb;
 633         ktime_t sent_at;
 634         int ix;
 635
 636         for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
 637                 skb = call->rxtx_buffer[ix];
 638                 if (!skb)
 639                         continue;
 640
 641                 sent_at = skb->tstamp;
 642                 smp_rmb(); /* Read timestamp before serial. */
 643                 sp = rxrpc_skb(skb);
 644                 if (sp->hdr.serial != orig_serial)
 645                         continue;
 646                 goto found;
 647         }
 648
 649         return;
 650
 651 found:
 652         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
 653                            orig_serial, ack_serial, sent_at, resp_time);
 654 }
 655
 656 /*
 657  * Process the response to a ping that we sent to find out if we lost an ACK.
 658  *
 659  * If we got back a ping response that indicates a lower tx_top than what we
 660  * had at the time of the ping transmission, we adjudge all the DATA packets
 661  * sent between the response tx_top and the ping-time tx_top to have been lost.
 662  */
 663 static void rxrpc_input_check_for_lost_ack(struct rxrpc_call *call)
 664 {
 665         rxrpc_seq_t top, bottom, seq;
 666         bool resend = false;
 667
 668         spin_lock_bh(&call->lock);
 669
 670         bottom = call->tx_hard_ack + 1;
 671         top = call->acks_lost_top;
 672         if (before(bottom, top)) {
 673                 for (seq = bottom; before_eq(seq, top); seq++) {
 674                         int ix = seq & RXRPC_RXTX_BUFF_MASK;
 675                         u8 annotation = call->rxtx_annotations[ix];
 676                         u8 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 677
 678                         if (anno_type != RXRPC_TX_ANNO_UNACK)
 679                                 continue;
 680                         annotation &= ~RXRPC_TX_ANNO_MASK;
 681                         annotation |= RXRPC_TX_ANNO_RETRANS;
 682                         call->rxtx_annotations[ix] = annotation;
 683                         resend = true;
 684                 }
 685         }
 686
 687         spin_unlock_bh(&call->lock);
 688
 689         if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 690                 rxrpc_queue_call(call);
 691 }
 692
 693 /*
 694  * Process a ping response.
 695  */
 696 static void rxrpc_input_ping_response(struct rxrpc_call *call,
 697                                       ktime_t resp_time,
 698                                       rxrpc_serial_t orig_serial,
 699                                       rxrpc_serial_t ack_serial)
 700 {
 701         rxrpc_serial_t ping_serial;
 702         ktime_t ping_time;
 703
 704         ping_time = call->ping_time;
 705         smp_rmb();
 706         ping_serial = READ_ONCE(call->ping_serial);
 707
 708         if (orig_serial == call->acks_lost_ping)
 709                 rxrpc_input_check_for_lost_ack(call);
 710
 711         if (before(orig_serial, ping_serial) ||
 712             !test_and_clear_bit(RXRPC_CALL_PINGING, &call->flags))
 713                 return;
 714         if (after(orig_serial, ping_serial))
 715                 return;
 716
 717         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
 718                            orig_serial, ack_serial, ping_time, resp_time);
 719 }
 720
 721 /*
 722  * Process the extra information that may be appended to an ACK packet
 723  */
 724 static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 725                                 struct rxrpc_ackinfo *ackinfo)
 726 {
 727         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 728         struct rxrpc_peer *peer;
 729         unsigned int mtu;
 730         bool wake = false;
 731         u32 rwind = ntohl(ackinfo->rwind);
 732
 733         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 734                sp->hdr.serial,
 735                ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
 736                rwind, ntohl(ackinfo->jumbo_max));
 737
 738         if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
 739                 rwind = RXRPC_RXTX_BUFF_SIZE - 1;
 740         if (call->tx_winsize != rwind) {
 741                 if (rwind > call->tx_winsize)
 742                         wake = true;
 743                 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake);
 744                 call->tx_winsize = rwind;
 745         }
 746
 747         if (call->cong_ssthresh > rwind)
 748                 call->cong_ssthresh = rwind;
 749
 750         mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
 751
 752         peer = call->peer;
 753         if (mtu < peer->maxdata) {
 754                 spin_lock_bh(&peer->lock);
 755                 peer->maxdata = mtu;
 756                 peer->mtu = mtu + peer->hdrsize;
 757                 spin_unlock_bh(&peer->lock);
 758                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 759         }
 760
 761         if (wake)
 762                 wake_up(&call->waitq);
 763 }
 764
 765 /*
 766  * Process individual soft ACKs.
 767  *
 768  * Each ACK in the array corresponds to one packet and can be either an ACK or
 769  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 770  * packets that lie beyond the end of the ACK list are scheduled for resend by
 771  * the timer on the basis that the peer might just not have processed them at
 772  * the time the ACK was sent.
 773  */
 774 static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 775                                   rxrpc_seq_t seq, int nr_acks,
 776                                   struct rxrpc_ack_summary *summary)
 777 {
 778         int ix;
 779         u8 annotation, anno_type;
 780
 781         for (; nr_acks > 0; nr_acks--, seq++) {
 782                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 783                 annotation = call->rxtx_annotations[ix];
 784                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 785                 annotation &= ~RXRPC_TX_ANNO_MASK;
 786                 switch (*acks++) {
 787                 case RXRPC_ACK_TYPE_ACK:
 788                         summary->nr_acks++;
 789                         if (anno_type == RXRPC_TX_ANNO_ACK)
 790                                 continue;
 791                         summary->nr_new_acks++;
 792                         call->rxtx_annotations[ix] =
 793                                 RXRPC_TX_ANNO_ACK | annotation;
 794                         break;
 795                 case RXRPC_ACK_TYPE_NACK:
 796                         if (!summary->nr_nacks &&
 797                             call->acks_lowest_nak != seq) {
 798                                 call->acks_lowest_nak = seq;
 799                                 summary->new_low_nack = true;
 800                         }
 801                         summary->nr_nacks++;
 802                         if (anno_type == RXRPC_TX_ANNO_NAK)
 803                                 continue;
 804                         summary->nr_new_nacks++;
 805                         if (anno_type == RXRPC_TX_ANNO_RETRANS)
 806                                 continue;
 807                         call->rxtx_annotations[ix] =
 808                                 RXRPC_TX_ANNO_NAK | annotation;
 809                         break;
 810                 default:
 811                         return rxrpc_proto_abort("SFT", call, 0);
 812                 }
 813         }
 814 }
 815
 816 /*
 817  * Return true if the ACK is valid - ie. it doesn't appear to have regressed
 818  * with respect to the ack state conveyed by preceding ACKs.
 819  */
 820 static bool rxrpc_is_ack_valid(struct rxrpc_call *call,
 821                                rxrpc_seq_t first_pkt, rxrpc_seq_t prev_pkt)
 822 {
 823         rxrpc_seq_t base = READ_ONCE(call->ackr_first_seq);
 824
 825         if (after(first_pkt, base))
 826                 return true; /* The window advanced */
 827
 828         if (before(first_pkt, base))
 829                 return false; /* firstPacket regressed */
 830
 831         if (after_eq(prev_pkt, call->ackr_prev_seq))
 832                 return true; /* previousPacket hasn't regressed. */
 833
 834         /* Some rx implementations put a serial number in previousPacket. */
 835         if (after_eq(prev_pkt, base + call->tx_winsize))
 836                 return false;
 837         return true;
 838 }
 839
 840 /*
 841  * Process an ACK packet.
 842  *
 843  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 844  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 845  *
 846  * A hard-ACK means that a packet has been processed and may be discarded; a
 847  * soft-ACK means that the packet may be discarded and retransmission
 848  * requested.  A phase is complete when all packets are hard-ACK'd.
 849  */
 850 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb,
 851                             u16 skew)
 852 {
 853         struct rxrpc_ack_summary summary = { 0 };
 854         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 855         union {
 856                 struct rxrpc_ackpacket ack;
 857                 struct rxrpc_ackinfo info;
 858                 u8 acks[RXRPC_MAXACKS];
 859         } buf;
 860         rxrpc_serial_t acked_serial;
 861         rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
 862         int nr_acks, offset, ioffset;
 863
 864         _enter("");
 865
 866         offset = sizeof(struct rxrpc_wire_header);
 867         if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
 868                 _debug("extraction failure");
 869                 return rxrpc_proto_abort("XAK", call, 0);
 870         }
 871         offset += sizeof(buf.ack);
 872
 873         acked_serial = ntohl(buf.ack.serial);
 874         first_soft_ack = ntohl(buf.ack.firstPacket);
 875         prev_pkt = ntohl(buf.ack.previousPacket);
 876         hard_ack = first_soft_ack - 1;
 877         nr_acks = buf.ack.nAcks;
 878         summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
 879                               buf.ack.reason : RXRPC_ACK__INVALID);
 880
 881         trace_rxrpc_rx_ack(call, sp->hdr.serial, acked_serial,
 882                            first_soft_ack, prev_pkt,
 883                            summary.ack_reason, nr_acks);
 884
 885         if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
 886                 rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
 887                                           sp->hdr.serial);
 888         if (buf.ack.reason == RXRPC_ACK_REQUESTED)
 889                 rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
 890                                           sp->hdr.serial);
 891
 892         if (buf.ack.reason == RXRPC_ACK_PING) {
 893                 _proto("Rx ACK %%%u PING Request", sp->hdr.serial);
 894                 rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 895                                   skew, sp->hdr.serial, true, true,
 896                                   rxrpc_propose_ack_respond_to_ping);
 897         } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 898                 rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 899                                   skew, sp->hdr.serial, true, true,
 900                                   rxrpc_propose_ack_respond_to_ack);
 901         }
 902
 903         /* Discard any out-of-order or duplicate ACKs (outside lock). */
 904         if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
 905                 trace_rxrpc_rx_discard_ack(call->debug_id, sp->hdr.serial,
 906                                            first_soft_ack, call->ackr_first_seq,
 907                                            prev_pkt, call->ackr_prev_seq);
 908                 return;
 909         }
 910
 911         buf.info.rxMTU = 0;
 912         ioffset = offset + nr_acks + 3;
 913         if (skb->len >= ioffset + sizeof(buf.info) &&
 914             skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
 915                 return rxrpc_proto_abort("XAI", call, 0);
 916
 917         spin_lock(&call->input_lock);
 918
 919         /* Discard any out-of-order or duplicate ACKs (inside lock). */
 920         if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
 921                 trace_rxrpc_rx_discard_ack(call->debug_id, sp->hdr.serial,
 922                                            first_soft_ack, call->ackr_first_seq,
 923                                            prev_pkt, call->ackr_prev_seq);
 924                 goto out;
 925         }
 926         call->acks_latest_ts = skb->tstamp;
 927         call->acks_latest = sp->hdr.serial;
 928
 929         call->ackr_first_seq = first_soft_ack;
 930         call->ackr_prev_seq = prev_pkt;
 931
 932         /* Parse rwind and mtu sizes if provided. */
 933         if (buf.info.rxMTU)
 934                 rxrpc_input_ackinfo(call, skb, &buf.info);
 935
 936         if (first_soft_ack == 0) {
 937                 rxrpc_proto_abort("AK0", call, 0);
 938                 goto out;
 939         }
 940
 941         /* Ignore ACKs unless we are or have just been transmitting. */
 942         switch (READ_ONCE(call->state)) {
 943         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 944         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 945         case RXRPC_CALL_SERVER_SEND_REPLY:
 946         case RXRPC_CALL_SERVER_AWAIT_ACK:
 947                 break;
 948         default:
 949                 goto out;
 950         }
 951
 952         if (before(hard_ack, call->tx_hard_ack) ||
 953             after(hard_ack, call->tx_top)) {
 954                 rxrpc_proto_abort("AKW", call, 0);
 955                 goto out;
 956         }
 957         if (nr_acks > call->tx_top - hard_ack) {
 958                 rxrpc_proto_abort("AKN", call, 0);
 959                 goto out;
 960         }
 961
 962         if (after(hard_ack, call->tx_hard_ack)) {
 963                 if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
 964                         rxrpc_end_tx_phase(call, false, "ETA");
 965                         goto out;
 966                 }
 967         }
 968
 969         if (nr_acks > 0) {
 970                 if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0) {
 971                         rxrpc_proto_abort("XSA", call, 0);
 972                         goto out;
 973                 }
 974                 rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
 975                                       &summary);
 976         }
 977
 978         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 979             RXRPC_TX_ANNO_LAST &&
 980             summary.nr_acks == call->tx_top - hard_ack &&
 981             rxrpc_is_client_call(call))
 982                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial,
 983                                   false, true,
 984                                   rxrpc_propose_ack_ping_for_lost_reply);
 985
 986         rxrpc_congestion_management(call, skb, &summary, acked_serial);
 987 out:
 988         spin_unlock(&call->input_lock);
 989 }
 990
 991 /*
 992  * Process an ACKALL packet.
 993  */
 994 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
 995 {
 996         struct rxrpc_ack_summary summary = { 0 };
 997         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 998
 999         _proto("Rx ACKALL %%%u", sp->hdr.serial);
1000
1001         spin_lock(&call->input_lock);
1002
1003         if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
1004                 rxrpc_end_tx_phase(call, false, "ETL");
1005
1006         spin_unlock(&call->input_lock);
1007 }
1008
1009 /*
1010  * Process an ABORT packet directed at a call.
1011  */
1012 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
1013 {
1014         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1015         __be32 wtmp;
1016         u32 abort_code = RX_CALL_DEAD;
1017
1018         _enter("");
1019
1020         if (skb->len >= 4 &&
1021             skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1022                           &wtmp, sizeof(wtmp)) >= 0)
1023                 abort_code = ntohl(wtmp);
1024
1025         trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
1026
1027         _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
1028
1029         if (rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
1030                                       abort_code, -ECONNABORTED))
1031                 rxrpc_notify_socket(call);
1032 }
1033
1034 /*
1035  * Process an incoming call packet.
1036  */
1037 static void rxrpc_input_call_packet(struct rxrpc_call *call,
1038                                     struct sk_buff *skb, u16 skew)
1039 {
1040         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1041         unsigned long timo;
1042
1043         _enter("%p,%p", call, skb);
1044
1045         timo = READ_ONCE(call->next_rx_timo);
1046         if (timo) {
1047                 unsigned long now = jiffies, expect_rx_by;
1048
1049                 expect_rx_by = now + timo;
1050                 WRITE_ONCE(call->expect_rx_by, expect_rx_by);
1051                 rxrpc_reduce_call_timer(call, expect_rx_by, now,
1052                                         rxrpc_timer_set_for_normal);
1053         }
1054
1055         switch (sp->hdr.type) {
1056         case RXRPC_PACKET_TYPE_DATA:
1057                 rxrpc_input_data(call, skb, skew);
1058                 break;
1059
1060         case RXRPC_PACKET_TYPE_ACK:
1061                 rxrpc_input_ack(call, skb, skew);
1062                 break;
1063
1064         case RXRPC_PACKET_TYPE_BUSY:
1065                 _proto("Rx BUSY %%%u", sp->hdr.serial);
1066
1067                 /* Just ignore BUSY packets from the server; the retry and
1068                  * lifespan timers will take care of business.  BUSY packets
1069                  * from the client don't make sense.
1070                  */
1071                 break;
1072
1073         case RXRPC_PACKET_TYPE_ABORT:
1074                 rxrpc_input_abort(call, skb);
1075                 break;
1076
1077         case RXRPC_PACKET_TYPE_ACKALL:
1078                 rxrpc_input_ackall(call, skb);
1079                 break;
1080
1081         default:
1082                 break;
1083         }
1084
1085         _leave("");
1086 }
1087
1088 /*
1089  * Handle a new service call on a channel implicitly completing the preceding
1090  * call on that channel.  This does not apply to client conns.
1091  *
1092  * TODO: If callNumber > call_id + 1, renegotiate security.
1093  */
1094 static void rxrpc_input_implicit_end_call(struct rxrpc_sock *rx,
1095                                           struct rxrpc_connection *conn,
1096                                           struct rxrpc_call *call)
1097 {
1098         switch (READ_ONCE(call->state)) {
1099         case RXRPC_CALL_SERVER_AWAIT_ACK:
1100                 rxrpc_call_completed(call);
1101                 /* Fall through */
1102         case RXRPC_CALL_COMPLETE:
1103                 break;
1104         default:
1105                 if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
1106                         set_bit(RXRPC_CALL_EV_ABORT, &call->events);
1107                         rxrpc_queue_call(call);
1108                 }
1109                 trace_rxrpc_improper_term(call);
1110                 break;
1111         }
1112
1113         spin_lock(&rx->incoming_lock);
1114         __rxrpc_disconnect_call(conn, call);
1115         spin_unlock(&rx->incoming_lock);
1116         rxrpc_notify_socket(call);
1117 }
1118
1119 /*
1120  * post connection-level events to the connection
1121  * - this includes challenges, responses, some aborts and call terminal packet
1122  *   retransmission.
1123  */
1124 static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
1125                                       struct sk_buff *skb)
1126 {
1127         _enter("%p,%p", conn, skb);
1128
1129         skb_queue_tail(&conn->rx_queue, skb);
1130         rxrpc_queue_conn(conn);
1131 }
1132
1133 /*
1134  * post endpoint-level events to the local endpoint
1135  * - this includes debug and version messages
1136  */
1137 static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
1138                                        struct sk_buff *skb)
1139 {
1140         _enter("%p,%p", local, skb);
1141
1142         if (rxrpc_get_local_maybe(local)) {
1143                 skb_queue_tail(&local->event_queue, skb);
1144                 rxrpc_queue_local(local);
1145         } else {
1146                 rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1147         }
1148 }
1149
1150 /*
1151  * put a packet up for transport-level abort
1152  */
1153 static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
1154 {
1155         CHECK_SLAB_OKAY(&local->usage);
1156
1157         if (rxrpc_get_local_maybe(local)) {
1158                 skb_queue_tail(&local->reject_queue, skb);
1159                 rxrpc_queue_local(local);
1160         } else {
1161                 rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1162         }
1163 }
1164
1165 /*
1166  * Extract the wire header from a packet and translate the byte order.
1167  */
1168 static noinline
1169 int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
1170 {
1171         struct rxrpc_wire_header whdr;
1172
1173         /* dig out the RxRPC connection details */
1174         if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0) {
1175                 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
1176                                       tracepoint_string("bad_hdr"));
1177                 return -EBADMSG;
1178         }
1179
1180         memset(sp, 0, sizeof(*sp));
1181         sp->hdr.epoch           = ntohl(whdr.epoch);
1182         sp->hdr.cid             = ntohl(whdr.cid);
1183         sp->hdr.callNumber      = ntohl(whdr.callNumber);
1184         sp->hdr.seq             = ntohl(whdr.seq);
1185         sp->hdr.serial          = ntohl(whdr.serial);
1186         sp->hdr.flags           = whdr.flags;
1187         sp->hdr.type            = whdr.type;
1188         sp->hdr.userStatus      = whdr.userStatus;
1189         sp->hdr.securityIndex   = whdr.securityIndex;
1190         sp->hdr._rsvd           = ntohs(whdr._rsvd);
1191         sp->hdr.serviceId       = ntohs(whdr.serviceId);
1192         return 0;
1193 }
1194
1195 /*
1196  * handle data received on the local endpoint
1197  * - may be called in interrupt context
1198  *
1199  * [!] Note that as this is called from the encap_rcv hook, the socket is not
1200  * held locked by the caller and nothing prevents sk_user_data on the UDP from
1201  * being cleared in the middle of processing this function.
1202  *
1203  * Called with the RCU read lock held from the IP layer via UDP.
1204  */
1205 int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
1206 {
1207         struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
1208         struct rxrpc_connection *conn;
1209         struct rxrpc_channel *chan;
1210         struct rxrpc_call *call = NULL;
1211         struct rxrpc_skb_priv *sp;
1212         struct rxrpc_peer *peer = NULL;
1213         struct rxrpc_sock *rx = NULL;
1214         unsigned int channel;
1215         int skew = 0;
1216
1217         _enter("%p", udp_sk);
1218
1219         if (unlikely(!local)) {
1220                 kfree_skb(skb);
1221                 return 0;
1222         }
1223         if (skb->tstamp == 0)
1224                 skb->tstamp = ktime_get_real();
1225
1226         rxrpc_new_skb(skb, rxrpc_skb_rx_received);
1227
1228         skb_pull(skb, sizeof(struct udphdr));
1229
1230         /* The UDP protocol already released all skb resources;
1231          * we are free to add our own data there.
1232          */
1233         sp = rxrpc_skb(skb);
1234
1235         /* dig out the RxRPC connection details */
1236         if (rxrpc_extract_header(sp, skb) < 0)
1237                 goto bad_message;
1238
1239         if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
1240                 static int lose;
1241                 if ((lose++ & 7) == 7) {
1242                         trace_rxrpc_rx_lose(sp);
1243                         rxrpc_free_skb(skb, rxrpc_skb_rx_lost);
1244                         return 0;
1245                 }
1246         }
1247
1248         if (skb->tstamp == 0)
1249                 skb->tstamp = ktime_get_real();
1250         trace_rxrpc_rx_packet(sp);
1251
1252         switch (sp->hdr.type) {
1253         case RXRPC_PACKET_TYPE_VERSION:
1254                 if (rxrpc_to_client(sp))
1255                         goto discard;
1256                 rxrpc_post_packet_to_local(local, skb);
1257                 goto out;
1258
1259         case RXRPC_PACKET_TYPE_BUSY:
1260                 if (rxrpc_to_server(sp))
1261                         goto discard;
1262                 /* Fall through */
1263         case RXRPC_PACKET_TYPE_ACK:
1264         case RXRPC_PACKET_TYPE_ACKALL:
1265                 if (sp->hdr.callNumber == 0)
1266                         goto bad_message;
1267                 /* Fall through */
1268         case RXRPC_PACKET_TYPE_ABORT:
1269                 break;
1270
1271         case RXRPC_PACKET_TYPE_DATA:
1272                 if (sp->hdr.callNumber == 0 ||
1273                     sp->hdr.seq == 0)
1274                         goto bad_message;
1275                 if (sp->hdr.flags & RXRPC_JUMBO_PACKET &&
1276                     !rxrpc_validate_jumbo(skb))
1277                         goto bad_message;
1278                 break;
1279
1280         case RXRPC_PACKET_TYPE_CHALLENGE:
1281                 if (rxrpc_to_server(sp))
1282                         goto discard;
1283                 break;
1284         case RXRPC_PACKET_TYPE_RESPONSE:
1285                 if (rxrpc_to_client(sp))
1286                         goto discard;
1287                 break;
1288
1289                 /* Packet types 9-11 should just be ignored. */
1290         case RXRPC_PACKET_TYPE_PARAMS:
1291         case RXRPC_PACKET_TYPE_10:
1292         case RXRPC_PACKET_TYPE_11:
1293                 goto discard;
1294
1295         default:
1296                 _proto("Rx Bad Packet Type %u", sp->hdr.type);
1297                 goto bad_message;
1298         }
1299
1300         if (sp->hdr.serviceId == 0)
1301                 goto bad_message;
1302
1303         if (rxrpc_to_server(sp)) {
1304                 /* Weed out packets to services we're not offering.  Packets
1305                  * that would begin a call are explicitly rejected and the rest
1306                  * are just discarded.
1307                  */
1308                 rx = rcu_dereference(local->service);
1309                 if (!rx || (sp->hdr.serviceId != rx->srx.srx_service &&
1310                             sp->hdr.serviceId != rx->second_service)) {
1311                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
1312                             sp->hdr.seq == 1)
1313                                 goto unsupported_service;
1314                         goto discard;
1315                 }
1316         }
1317
1318         conn = rxrpc_find_connection_rcu(local, skb, &peer);
1319         if (conn) {
1320                 if (sp->hdr.securityIndex != conn->security_ix)
1321                         goto wrong_security;
1322
1323                 if (sp->hdr.serviceId != conn->service_id) {
1324                         int old_id;
1325
1326                         if (!test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags))
1327                                 goto reupgrade;
1328                         old_id = cmpxchg(&conn->service_id, conn->params.service_id,
1329                                          sp->hdr.serviceId);
1330
1331                         if (old_id != conn->params.service_id &&
1332                             old_id != sp->hdr.serviceId)
1333                                 goto reupgrade;
1334                 }
1335
1336                 if (sp->hdr.callNumber == 0) {
1337                         /* Connection-level packet */
1338                         _debug("CONN %p {%d}", conn, conn->debug_id);
1339                         rxrpc_post_packet_to_conn(conn, skb);
1340                         goto out;
1341                 }
1342
1343                 /* Note the serial number skew here */
1344                 skew = (int)sp->hdr.serial - (int)conn->hi_serial;
1345                 if (skew >= 0) {
1346                         if (skew > 0)
1347                                 conn->hi_serial = sp->hdr.serial;
1348                 } else {
1349                         skew = -skew;
1350                         skew = min(skew, 65535);
1351                 }
1352
1353                 /* Call-bound packets are routed by connection channel. */
1354                 channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1355                 chan = &conn->channels[channel];
1356
1357                 /* Ignore really old calls */
1358                 if (sp->hdr.callNumber < chan->last_call)
1359                         goto discard;
1360
1361                 if (sp->hdr.callNumber == chan->last_call) {
1362                         if (chan->call ||
1363                             sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
1364                                 goto discard;
1365
1366                         /* For the previous service call, if completed
1367                          * successfully, we discard all further packets.
1368                          */
1369                         if (rxrpc_conn_is_service(conn) &&
1370                             chan->last_type == RXRPC_PACKET_TYPE_ACK)
1371                                 goto discard;
1372
1373                         /* But otherwise we need to retransmit the final packet
1374                          * from data cached in the connection record.
1375                          */
1376                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
1377                                 trace_rxrpc_rx_data(chan->call_debug_id,
1378                                                     sp->hdr.seq,
1379                                                     sp->hdr.serial,
1380                                                     sp->hdr.flags, 0);
1381                         rxrpc_post_packet_to_conn(conn, skb);
1382                         goto out;
1383                 }
1384
1385                 call = rcu_dereference(chan->call);
1386
1387                 if (sp->hdr.callNumber > chan->call_id) {
1388                         if (rxrpc_to_client(sp))
1389                                 goto reject_packet;
1390                         if (call)
1391                                 rxrpc_input_implicit_end_call(rx, conn, call);
1392                         call = NULL;
1393                 }
1394
1395                 if (call) {
1396                         if (sp->hdr.serviceId != call->service_id)
1397                                 call->service_id = sp->hdr.serviceId;
1398                         if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
1399                                 call->rx_serial = sp->hdr.serial;
1400                         if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
1401                                 set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
1402                 }
1403         }
1404
1405         if (!call || atomic_read(&call->usage) == 0) {
1406                 if (rxrpc_to_client(sp) ||
1407                     sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1408                         goto bad_message;
1409                 if (sp->hdr.seq != 1)
1410                         goto discard;
1411                 call = rxrpc_new_incoming_call(local, rx, skb);
1412                 if (!call)
1413                         goto reject_packet;
1414                 rxrpc_send_ping(call, skb, skew);
1415                 mutex_unlock(&call->user_mutex);
1416         }
1417
1418         rxrpc_input_call_packet(call, skb, skew);
1419         goto discard;
1420
1421 discard:
1422         rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
1423 out:
1424         trace_rxrpc_rx_done(0, 0);
1425         return 0;
1426
1427 wrong_security:
1428         trace_rxrpc_abort(0, "SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1429                           RXKADINCONSISTENCY, EBADMSG);
1430         skb->priority = RXKADINCONSISTENCY;
1431         goto post_abort;
1432
1433 unsupported_service:
1434         trace_rxrpc_abort(0, "INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1435                           RX_INVALID_OPERATION, EOPNOTSUPP);
1436         skb->priority = RX_INVALID_OPERATION;
1437         goto post_abort;
1438
1439 reupgrade:
1440         trace_rxrpc_abort(0, "UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1441                           RX_PROTOCOL_ERROR, EBADMSG);
1442         goto protocol_error;
1443
1444 bad_message:
1445         trace_rxrpc_abort(0, "BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1446                           RX_PROTOCOL_ERROR, EBADMSG);
1447 protocol_error:
1448         skb->priority = RX_PROTOCOL_ERROR;
1449 post_abort:
1450         skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
1451 reject_packet:
1452         trace_rxrpc_rx_done(skb->mark, skb->priority);
1453         rxrpc_reject_packet(local, skb);
1454         _leave(" [badmsg]");
1455         return 0;
1456 }