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_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_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 data 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_data(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         u8 flags = sp->hdr.flags;
 367
 368         for (;;) {
 369                 if (flags & RXRPC_REQUEST_ACK)
 370                         __set_bit(sp->nr_subpackets, sp->rx_req_ack);
 371                 sp->nr_subpackets++;
 372
 373                 if (!(flags & RXRPC_JUMBO_PACKET))
 374                         break;
 375
 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         }
 385
 386         if (flags & RXRPC_LAST_PACKET)
 387                 sp->rx_flags |= RXRPC_SKB_INCL_LAST;
 388         return true;
 389
 390 protocol_error:
 391         return false;
 392 }
 393
 394 /*
 395  * Handle reception of a duplicate packet.
 396  *
 397  * We have to take care to avoid an attack here whereby we're given a series of
 398  * jumbograms, each with a sequence number one before the preceding one and
 399  * filled up to maximum UDP size.  If they never send us the first packet in
 400  * the sequence, they can cause us to have to hold on to around 2MiB of kernel
 401  * space until the call times out.
 402  *
 403  * We limit the space usage by only accepting three duplicate jumbo packets per
 404  * call.  After that, we tell the other side we're no longer accepting jumbos
 405  * (that information is encoded in the ACK packet).
 406  */
 407 static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
 408                                  bool is_jumbo, bool *_jumbo_bad)
 409 {
 410         /* Discard normal packets that are duplicates. */
 411         if (is_jumbo)
 412                 return;
 413
 414         /* Skip jumbo subpackets that are duplicates.  When we've had three or
 415          * more partially duplicate jumbo packets, we refuse to take any more
 416          * jumbos for this call.
 417          */
 418         if (!*_jumbo_bad) {
 419                 call->nr_jumbo_bad++;
 420                 *_jumbo_bad = true;
 421         }
 422 }
 423
 424 /*
 425  * Process a DATA packet, adding the packet to the Rx ring.  The caller's
 426  * packet ref must be passed on or discarded.
 427  */
 428 static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
 429 {
 430         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 431         enum rxrpc_call_state state;
 432         unsigned int j;
 433         rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
 434         rxrpc_seq_t seq0 = sp->hdr.seq, hard_ack;
 435         bool immediate_ack = false, jumbo_bad = false;
 436         u8 ack = 0;
 437
 438         _enter("{%u,%u},{%u,%u}",
 439                call->rx_hard_ack, call->rx_top, skb->len, seq0);
 440
 441         _proto("Rx DATA %%%u { #%u f=%02x n=%u }",
 442                sp->hdr.serial, seq0, sp->hdr.flags, sp->nr_subpackets);
 443
 444         state = READ_ONCE(call->state);
 445         if (state >= RXRPC_CALL_COMPLETE) {
 446                 rxrpc_free_skb(skb, rxrpc_skb_freed);
 447                 return;
 448         }
 449
 450         if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST) {
 451                 unsigned long timo = READ_ONCE(call->next_req_timo);
 452                 unsigned long now, expect_req_by;
 453
 454                 if (timo) {
 455                         now = jiffies;
 456                         expect_req_by = now + timo;
 457                         WRITE_ONCE(call->expect_req_by, expect_req_by);
 458                         rxrpc_reduce_call_timer(call, expect_req_by, now,
 459                                                 rxrpc_timer_set_for_idle);
 460                 }
 461         }
 462
 463         spin_lock(&call->input_lock);
 464
 465         /* Received data implicitly ACKs all of the request packets we sent
 466          * when we're acting as a client.
 467          */
 468         if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
 469              state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
 470             !rxrpc_receiving_reply(call))
 471                 goto unlock;
 472
 473         call->ackr_prev_seq = seq0;
 474         hard_ack = READ_ONCE(call->rx_hard_ack);
 475
 476         if (sp->nr_subpackets > 1) {
 477                 if (call->nr_jumbo_bad > 3) {
 478                         ack = RXRPC_ACK_NOSPACE;
 479                         ack_serial = serial;
 480                         goto ack;
 481                 }
 482         }
 483
 484         for (j = 0; j < sp->nr_subpackets; j++) {
 485                 rxrpc_serial_t serial = sp->hdr.serial + j;
 486                 rxrpc_seq_t seq = seq0 + j;
 487                 unsigned int ix = seq & RXRPC_RXTX_BUFF_MASK;
 488                 bool terminal = (j == sp->nr_subpackets - 1);
 489                 bool last = terminal && (sp->rx_flags & RXRPC_SKB_INCL_LAST);
 490                 u8 flags, annotation = j;
 491
 492                 _proto("Rx DATA+%u %%%u { #%x t=%u l=%u }",
 493                      j, serial, seq, terminal, last);
 494
 495                 if (last) {
 496                         if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 497                             seq != call->rx_top) {
 498                                 rxrpc_proto_abort("LSN", call, seq);
 499                                 goto unlock;
 500                         }
 501                 } else {
 502                         if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 503                             after_eq(seq, call->rx_top)) {
 504                                 rxrpc_proto_abort("LSA", call, seq);
 505                                 goto unlock;
 506                         }
 507                 }
 508
 509                 flags = 0;
 510                 if (last)
 511                         flags |= RXRPC_LAST_PACKET;
 512                 if (!terminal)
 513                         flags |= RXRPC_JUMBO_PACKET;
 514                 if (test_bit(j, sp->rx_req_ack))
 515                         flags |= RXRPC_REQUEST_ACK;
 516                 trace_rxrpc_rx_data(call->debug_id, seq, serial, flags, annotation);
 517
 518                 if (before_eq(seq, hard_ack)) {
 519                         ack = RXRPC_ACK_DUPLICATE;
 520                         ack_serial = serial;
 521                         continue;
 522                 }
 523
 524                 if (call->rxtx_buffer[ix]) {
 525                         rxrpc_input_dup_data(call, seq, sp->nr_subpackets > 1,
 526                                              &jumbo_bad);
 527                         if (ack != RXRPC_ACK_DUPLICATE) {
 528                                 ack = RXRPC_ACK_DUPLICATE;
 529                                 ack_serial = serial;
 530                         }
 531                         immediate_ack = true;
 532                         continue;
 533                 }
 534
 535                 if (after(seq, hard_ack + call->rx_winsize)) {
 536                         ack = RXRPC_ACK_EXCEEDS_WINDOW;
 537                         ack_serial = serial;
 538                         if (flags & RXRPC_JUMBO_PACKET) {
 539                                 if (!jumbo_bad) {
 540                                         call->nr_jumbo_bad++;
 541                                         jumbo_bad = true;
 542                                 }
 543                         }
 544
 545                         goto ack;
 546                 }
 547
 548                 if (flags & RXRPC_REQUEST_ACK && !ack) {
 549                         ack = RXRPC_ACK_REQUESTED;
 550                         ack_serial = serial;
 551                 }
 552
 553                 /* Queue the packet.  We use a couple of memory barriers here as need
 554                  * to make sure that rx_top is perceived to be set after the buffer
 555                  * pointer and that the buffer pointer is set after the annotation and
 556                  * the skb data.
 557                  *
 558                  * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
 559                  * and also rxrpc_fill_out_ack().
 560                  */
 561                 if (!terminal)
 562                         rxrpc_get_skb(skb, rxrpc_skb_got);
 563                 call->rxtx_annotations[ix] = annotation;
 564                 smp_wmb();
 565                 call->rxtx_buffer[ix] = skb;
 566                 if (after(seq, call->rx_top)) {
 567                         smp_store_release(&call->rx_top, seq);
 568                 } else if (before(seq, call->rx_top)) {
 569                         /* Send an immediate ACK if we fill in a hole */
 570                         if (!ack) {
 571                                 ack = RXRPC_ACK_DELAY;
 572                                 ack_serial = serial;
 573                         }
 574                         immediate_ack = true;
 575                 }
 576
 577                 if (terminal) {
 578                         /* From this point on, we're not allowed to touch the
 579                          * packet any longer as its ref now belongs to the Rx
 580                          * ring.
 581                          */
 582                         skb = NULL;
 583                 }
 584
 585                 if (last) {
 586                         set_bit(RXRPC_CALL_RX_LAST, &call->flags);
 587                         if (!ack) {
 588                                 ack = RXRPC_ACK_DELAY;
 589                                 ack_serial = serial;
 590                         }
 591                         trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
 592                 } else {
 593                         trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
 594                 }
 595
 596                 if (after_eq(seq, call->rx_expect_next)) {
 597                         if (after(seq, call->rx_expect_next)) {
 598                                 _net("OOS %u > %u", seq, call->rx_expect_next);
 599                                 ack = RXRPC_ACK_OUT_OF_SEQUENCE;
 600                                 ack_serial = serial;
 601                         }
 602                         call->rx_expect_next = seq + 1;
 603                 }
 604         }
 605
 606 ack:
 607         if (ack)
 608                 rxrpc_propose_ACK(call, ack, ack_serial,
 609                                   immediate_ack, true,
 610                                   rxrpc_propose_ack_input_data);
 611         else
 612                 rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial,
 613                                   false, true,
 614                                   rxrpc_propose_ack_input_data);
 615
 616         if (seq0 == READ_ONCE(call->rx_hard_ack) + 1) {
 617                 trace_rxrpc_notify_socket(call->debug_id, serial);
 618                 rxrpc_notify_socket(call);
 619         }
 620
 621 unlock:
 622         spin_unlock(&call->input_lock);
 623         rxrpc_free_skb(skb, rxrpc_skb_freed);
 624         _leave(" [queued]");
 625 }
 626
 627 /*
 628  * Process a requested ACK.
 629  */
 630 static void rxrpc_input_requested_ack(struct rxrpc_call *call,
 631                                       ktime_t resp_time,
 632                                       rxrpc_serial_t orig_serial,
 633                                       rxrpc_serial_t ack_serial)
 634 {
 635         struct rxrpc_skb_priv *sp;
 636         struct sk_buff *skb;
 637         ktime_t sent_at;
 638         int ix;
 639
 640         for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
 641                 skb = call->rxtx_buffer[ix];
 642                 if (!skb)
 643                         continue;
 644
 645                 sent_at = skb->tstamp;
 646                 smp_rmb(); /* Read timestamp before serial. */
 647                 sp = rxrpc_skb(skb);
 648                 if (sp->hdr.serial != orig_serial)
 649                         continue;
 650                 goto found;
 651         }
 652
 653         return;
 654
 655 found:
 656         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
 657                            orig_serial, ack_serial, sent_at, resp_time);
 658 }
 659
 660 /*
 661  * Process the response to a ping that we sent to find out if we lost an ACK.
 662  *
 663  * If we got back a ping response that indicates a lower tx_top than what we
 664  * had at the time of the ping transmission, we adjudge all the DATA packets
 665  * sent between the response tx_top and the ping-time tx_top to have been lost.
 666  */
 667 static void rxrpc_input_check_for_lost_ack(struct rxrpc_call *call)
 668 {
 669         rxrpc_seq_t top, bottom, seq;
 670         bool resend = false;
 671
 672         spin_lock_bh(&call->lock);
 673
 674         bottom = call->tx_hard_ack + 1;
 675         top = call->acks_lost_top;
 676         if (before(bottom, top)) {
 677                 for (seq = bottom; before_eq(seq, top); seq++) {
 678                         int ix = seq & RXRPC_RXTX_BUFF_MASK;
 679                         u8 annotation = call->rxtx_annotations[ix];
 680                         u8 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 681
 682                         if (anno_type != RXRPC_TX_ANNO_UNACK)
 683                                 continue;
 684                         annotation &= ~RXRPC_TX_ANNO_MASK;
 685                         annotation |= RXRPC_TX_ANNO_RETRANS;
 686                         call->rxtx_annotations[ix] = annotation;
 687                         resend = true;
 688                 }
 689         }
 690
 691         spin_unlock_bh(&call->lock);
 692
 693         if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 694                 rxrpc_queue_call(call);
 695 }
 696
 697 /*
 698  * Process a ping response.
 699  */
 700 static void rxrpc_input_ping_response(struct rxrpc_call *call,
 701                                       ktime_t resp_time,
 702                                       rxrpc_serial_t orig_serial,
 703                                       rxrpc_serial_t ack_serial)
 704 {
 705         rxrpc_serial_t ping_serial;
 706         ktime_t ping_time;
 707
 708         ping_time = call->ping_time;
 709         smp_rmb();
 710         ping_serial = READ_ONCE(call->ping_serial);
 711
 712         if (orig_serial == call->acks_lost_ping)
 713                 rxrpc_input_check_for_lost_ack(call);
 714
 715         if (before(orig_serial, ping_serial) ||
 716             !test_and_clear_bit(RXRPC_CALL_PINGING, &call->flags))
 717                 return;
 718         if (after(orig_serial, ping_serial))
 719                 return;
 720
 721         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
 722                            orig_serial, ack_serial, ping_time, resp_time);
 723 }
 724
 725 /*
 726  * Process the extra information that may be appended to an ACK packet
 727  */
 728 static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 729                                 struct rxrpc_ackinfo *ackinfo)
 730 {
 731         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 732         struct rxrpc_peer *peer;
 733         unsigned int mtu;
 734         bool wake = false;
 735         u32 rwind = ntohl(ackinfo->rwind);
 736
 737         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 738                sp->hdr.serial,
 739                ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
 740                rwind, ntohl(ackinfo->jumbo_max));
 741
 742         if (call->tx_winsize != rwind) {
 743                 if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
 744                         rwind = RXRPC_RXTX_BUFF_SIZE - 1;
 745                 if (rwind > call->tx_winsize)
 746                         wake = true;
 747                 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial,
 748                                             ntohl(ackinfo->rwind), wake);
 749                 call->tx_winsize = rwind;
 750         }
 751
 752         if (call->cong_ssthresh > rwind)
 753                 call->cong_ssthresh = rwind;
 754
 755         mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
 756
 757         peer = call->peer;
 758         if (mtu < peer->maxdata) {
 759                 spin_lock_bh(&peer->lock);
 760                 peer->maxdata = mtu;
 761                 peer->mtu = mtu + peer->hdrsize;
 762                 spin_unlock_bh(&peer->lock);
 763                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 764         }
 765
 766         if (wake)
 767                 wake_up(&call->waitq);
 768 }
 769
 770 /*
 771  * Process individual soft ACKs.
 772  *
 773  * Each ACK in the array corresponds to one packet and can be either an ACK or
 774  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 775  * packets that lie beyond the end of the ACK list are scheduled for resend by
 776  * the timer on the basis that the peer might just not have processed them at
 777  * the time the ACK was sent.
 778  */
 779 static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 780                                   rxrpc_seq_t seq, int nr_acks,
 781                                   struct rxrpc_ack_summary *summary)
 782 {
 783         int ix;
 784         u8 annotation, anno_type;
 785
 786         for (; nr_acks > 0; nr_acks--, seq++) {
 787                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 788                 annotation = call->rxtx_annotations[ix];
 789                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 790                 annotation &= ~RXRPC_TX_ANNO_MASK;
 791                 switch (*acks++) {
 792                 case RXRPC_ACK_TYPE_ACK:
 793                         summary->nr_acks++;
 794                         if (anno_type == RXRPC_TX_ANNO_ACK)
 795                                 continue;
 796                         summary->nr_new_acks++;
 797                         call->rxtx_annotations[ix] =
 798                                 RXRPC_TX_ANNO_ACK | annotation;
 799                         break;
 800                 case RXRPC_ACK_TYPE_NACK:
 801                         if (!summary->nr_nacks &&
 802                             call->acks_lowest_nak != seq) {
 803                                 call->acks_lowest_nak = seq;
 804                                 summary->new_low_nack = true;
 805                         }
 806                         summary->nr_nacks++;
 807                         if (anno_type == RXRPC_TX_ANNO_NAK)
 808                                 continue;
 809                         summary->nr_new_nacks++;
 810                         if (anno_type == RXRPC_TX_ANNO_RETRANS)
 811                                 continue;
 812                         call->rxtx_annotations[ix] =
 813                                 RXRPC_TX_ANNO_NAK | annotation;
 814                         break;
 815                 default:
 816                         return rxrpc_proto_abort("SFT", call, 0);
 817                 }
 818         }
 819 }
 820
 821 /*
 822  * Process an ACK packet.
 823  *
 824  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 825  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 826  *
 827  * A hard-ACK means that a packet has been processed and may be discarded; a
 828  * soft-ACK means that the packet may be discarded and retransmission
 829  * requested.  A phase is complete when all packets are hard-ACK'd.
 830  */
 831 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 832 {
 833         struct rxrpc_ack_summary summary = { 0 };
 834         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 835         union {
 836                 struct rxrpc_ackpacket ack;
 837                 struct rxrpc_ackinfo info;
 838                 u8 acks[RXRPC_MAXACKS];
 839         } buf;
 840         rxrpc_serial_t acked_serial;
 841         rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
 842         int nr_acks, offset, ioffset;
 843
 844         _enter("");
 845
 846         offset = sizeof(struct rxrpc_wire_header);
 847         if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
 848                 _debug("extraction failure");
 849                 return rxrpc_proto_abort("XAK", call, 0);
 850         }
 851         offset += sizeof(buf.ack);
 852
 853         acked_serial = ntohl(buf.ack.serial);
 854         first_soft_ack = ntohl(buf.ack.firstPacket);
 855         prev_pkt = ntohl(buf.ack.previousPacket);
 856         hard_ack = first_soft_ack - 1;
 857         nr_acks = buf.ack.nAcks;
 858         summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
 859                               buf.ack.reason : RXRPC_ACK__INVALID);
 860
 861         trace_rxrpc_rx_ack(call, sp->hdr.serial, acked_serial,
 862                            first_soft_ack, prev_pkt,
 863                            summary.ack_reason, nr_acks);
 864
 865         if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
 866                 rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
 867                                           sp->hdr.serial);
 868         if (buf.ack.reason == RXRPC_ACK_REQUESTED)
 869                 rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
 870                                           sp->hdr.serial);
 871
 872         if (buf.ack.reason == RXRPC_ACK_PING) {
 873                 _proto("Rx ACK %%%u PING Request", sp->hdr.serial);
 874                 rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 875                                   sp->hdr.serial, true, true,
 876                                   rxrpc_propose_ack_respond_to_ping);
 877         } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 878                 rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 879                                   sp->hdr.serial, true, true,
 880                                   rxrpc_propose_ack_respond_to_ack);
 881         }
 882
 883         /* Discard any out-of-order or duplicate ACKs (outside lock). */
 884         if (before(first_soft_ack, call->ackr_first_seq) ||
 885             before(prev_pkt, call->ackr_prev_seq))
 886                 return;
 887
 888         buf.info.rxMTU = 0;
 889         ioffset = offset + nr_acks + 3;
 890         if (skb->len >= ioffset + sizeof(buf.info) &&
 891             skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
 892                 return rxrpc_proto_abort("XAI", call, 0);
 893
 894         spin_lock(&call->input_lock);
 895
 896         /* Discard any out-of-order or duplicate ACKs (inside lock). */
 897         if (before(first_soft_ack, call->ackr_first_seq) ||
 898             before(prev_pkt, call->ackr_prev_seq))
 899                 goto out;
 900         call->acks_latest_ts = skb->tstamp;
 901         call->acks_latest = sp->hdr.serial;
 902
 903         call->ackr_first_seq = first_soft_ack;
 904         call->ackr_prev_seq = prev_pkt;
 905
 906         /* Parse rwind and mtu sizes if provided. */
 907         if (buf.info.rxMTU)
 908                 rxrpc_input_ackinfo(call, skb, &buf.info);
 909
 910         if (first_soft_ack == 0) {
 911                 rxrpc_proto_abort("AK0", call, 0);
 912                 goto out;
 913         }
 914
 915         /* Ignore ACKs unless we are or have just been transmitting. */
 916         switch (READ_ONCE(call->state)) {
 917         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 918         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 919         case RXRPC_CALL_SERVER_SEND_REPLY:
 920         case RXRPC_CALL_SERVER_AWAIT_ACK:
 921                 break;
 922         default:
 923                 goto out;
 924         }
 925
 926         if (before(hard_ack, call->tx_hard_ack) ||
 927             after(hard_ack, call->tx_top)) {
 928                 rxrpc_proto_abort("AKW", call, 0);
 929                 goto out;
 930         }
 931         if (nr_acks > call->tx_top - hard_ack) {
 932                 rxrpc_proto_abort("AKN", call, 0);
 933                 goto out;
 934         }
 935
 936         if (after(hard_ack, call->tx_hard_ack)) {
 937                 if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
 938                         rxrpc_end_tx_phase(call, false, "ETA");
 939                         goto out;
 940                 }
 941         }
 942
 943         if (nr_acks > 0) {
 944                 if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0) {
 945                         rxrpc_proto_abort("XSA", call, 0);
 946                         goto out;
 947                 }
 948                 rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
 949                                       &summary);
 950         }
 951
 952         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 953             RXRPC_TX_ANNO_LAST &&
 954             summary.nr_acks == call->tx_top - hard_ack &&
 955             rxrpc_is_client_call(call))
 956                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
 957                                   false, true,
 958                                   rxrpc_propose_ack_ping_for_lost_reply);
 959
 960         rxrpc_congestion_management(call, skb, &summary, acked_serial);
 961 out:
 962         spin_unlock(&call->input_lock);
 963 }
 964
 965 /*
 966  * Process an ACKALL packet.
 967  */
 968 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
 969 {
 970         struct rxrpc_ack_summary summary = { 0 };
 971         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 972
 973         _proto("Rx ACKALL %%%u", sp->hdr.serial);
 974
 975         spin_lock(&call->input_lock);
 976
 977         if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
 978                 rxrpc_end_tx_phase(call, false, "ETL");
 979
 980         spin_unlock(&call->input_lock);
 981 }
 982
 983 /*
 984  * Process an ABORT packet directed at a call.
 985  */
 986 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
 987 {
 988         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 989         __be32 wtmp;
 990         u32 abort_code = RX_CALL_DEAD;
 991
 992         _enter("");
 993
 994         if (skb->len >= 4 &&
 995             skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
 996                           &wtmp, sizeof(wtmp)) >= 0)
 997                 abort_code = ntohl(wtmp);
 998
 999         trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
1000
1001         _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
1002
1003         if (rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
1004                                       abort_code, -ECONNABORTED))
1005                 rxrpc_notify_socket(call);
1006 }
1007
1008 /*
1009  * Process an incoming call packet.
1010  */
1011 static void rxrpc_input_call_packet(struct rxrpc_call *call,
1012                                     struct sk_buff *skb)
1013 {
1014         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1015         unsigned long timo;
1016
1017         _enter("%p,%p", call, skb);
1018
1019         timo = READ_ONCE(call->next_rx_timo);
1020         if (timo) {
1021                 unsigned long now = jiffies, expect_rx_by;
1022
1023                 expect_rx_by = now + timo;
1024                 WRITE_ONCE(call->expect_rx_by, expect_rx_by);
1025                 rxrpc_reduce_call_timer(call, expect_rx_by, now,
1026                                         rxrpc_timer_set_for_normal);
1027         }
1028
1029         switch (sp->hdr.type) {
1030         case RXRPC_PACKET_TYPE_DATA:
1031                 rxrpc_input_data(call, skb);
1032                 goto no_free;
1033
1034         case RXRPC_PACKET_TYPE_ACK:
1035                 rxrpc_input_ack(call, skb);
1036                 break;
1037
1038         case RXRPC_PACKET_TYPE_BUSY:
1039                 _proto("Rx BUSY %%%u", sp->hdr.serial);
1040
1041                 /* Just ignore BUSY packets from the server; the retry and
1042                  * lifespan timers will take care of business.  BUSY packets
1043                  * from the client don't make sense.
1044                  */
1045                 break;
1046
1047         case RXRPC_PACKET_TYPE_ABORT:
1048                 rxrpc_input_abort(call, skb);
1049                 break;
1050
1051         case RXRPC_PACKET_TYPE_ACKALL:
1052                 rxrpc_input_ackall(call, skb);
1053                 break;
1054
1055         default:
1056                 break;
1057         }
1058
1059         rxrpc_free_skb(skb, rxrpc_skb_freed);
1060 no_free:
1061         _leave("");
1062 }
1063
1064 /*
1065  * Handle a new service call on a channel implicitly completing the preceding
1066  * call on that channel.  This does not apply to client conns.
1067  *
1068  * TODO: If callNumber > call_id + 1, renegotiate security.
1069  */
1070 static void rxrpc_input_implicit_end_call(struct rxrpc_sock *rx,
1071                                           struct rxrpc_connection *conn,
1072                                           struct rxrpc_call *call)
1073 {
1074         switch (READ_ONCE(call->state)) {
1075         case RXRPC_CALL_SERVER_AWAIT_ACK:
1076                 rxrpc_call_completed(call);
1077                 /* Fall through */
1078         case RXRPC_CALL_COMPLETE:
1079                 break;
1080         default:
1081                 if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
1082                         set_bit(RXRPC_CALL_EV_ABORT, &call->events);
1083                         rxrpc_queue_call(call);
1084                 }
1085                 trace_rxrpc_improper_term(call);
1086                 break;
1087         }
1088
1089         spin_lock(&rx->incoming_lock);
1090         __rxrpc_disconnect_call(conn, call);
1091         spin_unlock(&rx->incoming_lock);
1092         rxrpc_notify_socket(call);
1093 }
1094
1095 /*
1096  * post connection-level events to the connection
1097  * - this includes challenges, responses, some aborts and call terminal packet
1098  *   retransmission.
1099  */
1100 static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
1101                                       struct sk_buff *skb)
1102 {
1103         _enter("%p,%p", conn, skb);
1104
1105         skb_queue_tail(&conn->rx_queue, skb);
1106         rxrpc_queue_conn(conn);
1107 }
1108
1109 /*
1110  * post endpoint-level events to the local endpoint
1111  * - this includes debug and version messages
1112  */
1113 static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
1114                                        struct sk_buff *skb)
1115 {
1116         _enter("%p,%p", local, skb);
1117
1118         if (rxrpc_get_local_maybe(local)) {
1119                 skb_queue_tail(&local->event_queue, skb);
1120                 rxrpc_queue_local(local);
1121         } else {
1122                 rxrpc_free_skb(skb, rxrpc_skb_freed);
1123         }
1124 }
1125
1126 /*
1127  * put a packet up for transport-level abort
1128  */
1129 static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
1130 {
1131         CHECK_SLAB_OKAY(&local->usage);
1132
1133         if (rxrpc_get_local_maybe(local)) {
1134                 skb_queue_tail(&local->reject_queue, skb);
1135                 rxrpc_queue_local(local);
1136         } else {
1137                 rxrpc_free_skb(skb, rxrpc_skb_freed);
1138         }
1139 }
1140
1141 /*
1142  * Extract the wire header from a packet and translate the byte order.
1143  */
1144 static noinline
1145 int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
1146 {
1147         struct rxrpc_wire_header whdr;
1148
1149         /* dig out the RxRPC connection details */
1150         if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0) {
1151                 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
1152                                       tracepoint_string("bad_hdr"));
1153                 return -EBADMSG;
1154         }
1155
1156         memset(sp, 0, sizeof(*sp));
1157         sp->hdr.epoch           = ntohl(whdr.epoch);
1158         sp->hdr.cid             = ntohl(whdr.cid);
1159         sp->hdr.callNumber      = ntohl(whdr.callNumber);
1160         sp->hdr.seq             = ntohl(whdr.seq);
1161         sp->hdr.serial          = ntohl(whdr.serial);
1162         sp->hdr.flags           = whdr.flags;
1163         sp->hdr.type            = whdr.type;
1164         sp->hdr.userStatus      = whdr.userStatus;
1165         sp->hdr.securityIndex   = whdr.securityIndex;
1166         sp->hdr._rsvd           = ntohs(whdr._rsvd);
1167         sp->hdr.serviceId       = ntohs(whdr.serviceId);
1168         return 0;
1169 }
1170
1171 /*
1172  * handle data received on the local endpoint
1173  * - may be called in interrupt context
1174  *
1175  * [!] Note that as this is called from the encap_rcv hook, the socket is not
1176  * held locked by the caller and nothing prevents sk_user_data on the UDP from
1177  * being cleared in the middle of processing this function.
1178  *
1179  * Called with the RCU read lock held from the IP layer via UDP.
1180  */
1181 int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
1182 {
1183         struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
1184         struct rxrpc_connection *conn;
1185         struct rxrpc_channel *chan;
1186         struct rxrpc_call *call = NULL;
1187         struct rxrpc_skb_priv *sp;
1188         struct rxrpc_peer *peer = NULL;
1189         struct rxrpc_sock *rx = NULL;
1190         unsigned int channel;
1191
1192         _enter("%p", udp_sk);
1193
1194         if (unlikely(!local)) {
1195                 kfree_skb(skb);
1196                 return 0;
1197         }
1198         if (skb->tstamp == 0)
1199                 skb->tstamp = ktime_get_real();
1200
1201         rxrpc_new_skb(skb, rxrpc_skb_received);
1202
1203         skb_pull(skb, sizeof(struct udphdr));
1204
1205         /* The UDP protocol already released all skb resources;
1206          * we are free to add our own data there.
1207          */
1208         sp = rxrpc_skb(skb);
1209
1210         /* dig out the RxRPC connection details */
1211         if (rxrpc_extract_header(sp, skb) < 0)
1212                 goto bad_message;
1213
1214         if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
1215                 static int lose;
1216                 if ((lose++ & 7) == 7) {
1217                         trace_rxrpc_rx_lose(sp);
1218                         rxrpc_free_skb(skb, rxrpc_skb_lost);
1219                         return 0;
1220                 }
1221         }
1222
1223         if (skb->tstamp == 0)
1224                 skb->tstamp = ktime_get_real();
1225         trace_rxrpc_rx_packet(sp);
1226
1227         switch (sp->hdr.type) {
1228         case RXRPC_PACKET_TYPE_VERSION:
1229                 if (rxrpc_to_client(sp))
1230                         goto discard;
1231                 rxrpc_post_packet_to_local(local, skb);
1232                 goto out;
1233
1234         case RXRPC_PACKET_TYPE_BUSY:
1235                 if (rxrpc_to_server(sp))
1236                         goto discard;
1237                 /* Fall through */
1238         case RXRPC_PACKET_TYPE_ACK:
1239         case RXRPC_PACKET_TYPE_ACKALL:
1240                 if (sp->hdr.callNumber == 0)
1241                         goto bad_message;
1242                 /* Fall through */
1243         case RXRPC_PACKET_TYPE_ABORT:
1244                 break;
1245
1246         case RXRPC_PACKET_TYPE_DATA:
1247                 if (sp->hdr.callNumber == 0 ||
1248                     sp->hdr.seq == 0)
1249                         goto bad_message;
1250                 if (!rxrpc_validate_data(skb))
1251                         goto bad_message;
1252                 break;
1253
1254         case RXRPC_PACKET_TYPE_CHALLENGE:
1255                 if (rxrpc_to_server(sp))
1256                         goto discard;
1257                 break;
1258         case RXRPC_PACKET_TYPE_RESPONSE:
1259                 if (rxrpc_to_client(sp))
1260                         goto discard;
1261                 break;
1262
1263                 /* Packet types 9-11 should just be ignored. */
1264         case RXRPC_PACKET_TYPE_PARAMS:
1265         case RXRPC_PACKET_TYPE_10:
1266         case RXRPC_PACKET_TYPE_11:
1267                 goto discard;
1268
1269         default:
1270                 _proto("Rx Bad Packet Type %u", sp->hdr.type);
1271                 goto bad_message;
1272         }
1273
1274         if (sp->hdr.serviceId == 0)
1275                 goto bad_message;
1276
1277         if (rxrpc_to_server(sp)) {
1278                 /* Weed out packets to services we're not offering.  Packets
1279                  * that would begin a call are explicitly rejected and the rest
1280                  * are just discarded.
1281                  */
1282                 rx = rcu_dereference(local->service);
1283                 if (!rx || (sp->hdr.serviceId != rx->srx.srx_service &&
1284                             sp->hdr.serviceId != rx->second_service)) {
1285                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
1286                             sp->hdr.seq == 1)
1287                                 goto unsupported_service;
1288                         goto discard;
1289                 }
1290         }
1291
1292         conn = rxrpc_find_connection_rcu(local, skb, &peer);
1293         if (conn) {
1294                 if (sp->hdr.securityIndex != conn->security_ix)
1295                         goto wrong_security;
1296
1297                 if (sp->hdr.serviceId != conn->service_id) {
1298                         int old_id;
1299
1300                         if (!test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags))
1301                                 goto reupgrade;
1302                         old_id = cmpxchg(&conn->service_id, conn->params.service_id,
1303                                          sp->hdr.serviceId);
1304
1305                         if (old_id != conn->params.service_id &&
1306                             old_id != sp->hdr.serviceId)
1307                                 goto reupgrade;
1308                 }
1309
1310                 if (sp->hdr.callNumber == 0) {
1311                         /* Connection-level packet */
1312                         _debug("CONN %p {%d}", conn, conn->debug_id);
1313                         rxrpc_post_packet_to_conn(conn, skb);
1314                         goto out;
1315                 }
1316
1317                 if ((int)sp->hdr.serial - (int)conn->hi_serial > 0)
1318                         conn->hi_serial = sp->hdr.serial;
1319
1320                 /* Call-bound packets are routed by connection channel. */
1321                 channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1322                 chan = &conn->channels[channel];
1323
1324                 /* Ignore really old calls */
1325                 if (sp->hdr.callNumber < chan->last_call)
1326                         goto discard;
1327
1328                 if (sp->hdr.callNumber == chan->last_call) {
1329                         if (chan->call ||
1330                             sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
1331                                 goto discard;
1332
1333                         /* For the previous service call, if completed
1334                          * successfully, we discard all further packets.
1335                          */
1336                         if (rxrpc_conn_is_service(conn) &&
1337                             chan->last_type == RXRPC_PACKET_TYPE_ACK)
1338                                 goto discard;
1339
1340                         /* But otherwise we need to retransmit the final packet
1341                          * from data cached in the connection record.
1342                          */
1343                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
1344                                 trace_rxrpc_rx_data(chan->call_debug_id,
1345                                                     sp->hdr.seq,
1346                                                     sp->hdr.serial,
1347                                                     sp->hdr.flags, 0);
1348                         rxrpc_post_packet_to_conn(conn, skb);
1349                         goto out;
1350                 }
1351
1352                 call = rcu_dereference(chan->call);
1353
1354                 if (sp->hdr.callNumber > chan->call_id) {
1355                         if (rxrpc_to_client(sp))
1356                                 goto reject_packet;
1357                         if (call)
1358                                 rxrpc_input_implicit_end_call(rx, conn, call);
1359                         call = NULL;
1360                 }
1361
1362                 if (call) {
1363                         if (sp->hdr.serviceId != call->service_id)
1364                                 call->service_id = sp->hdr.serviceId;
1365                         if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
1366                                 call->rx_serial = sp->hdr.serial;
1367                         if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
1368                                 set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
1369                 }
1370         }
1371
1372         if (!call || atomic_read(&call->usage) == 0) {
1373                 if (rxrpc_to_client(sp) ||
1374                     sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1375                         goto bad_message;
1376                 if (sp->hdr.seq != 1)
1377                         goto discard;
1378                 call = rxrpc_new_incoming_call(local, rx, skb);
1379                 if (!call)
1380                         goto reject_packet;
1381                 rxrpc_send_ping(call, skb);
1382                 mutex_unlock(&call->user_mutex);
1383         }
1384
1385         /* Process a call packet; this either discards or passes on the ref
1386          * elsewhere.
1387          */
1388         rxrpc_input_call_packet(call, skb);
1389         goto out;
1390
1391 discard:
1392         rxrpc_free_skb(skb, rxrpc_skb_freed);
1393 out:
1394         trace_rxrpc_rx_done(0, 0);
1395         return 0;
1396
1397 wrong_security:
1398         trace_rxrpc_abort(0, "SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1399                           RXKADINCONSISTENCY, EBADMSG);
1400         skb->priority = RXKADINCONSISTENCY;
1401         goto post_abort;
1402
1403 unsupported_service:
1404         trace_rxrpc_abort(0, "INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1405                           RX_INVALID_OPERATION, EOPNOTSUPP);
1406         skb->priority = RX_INVALID_OPERATION;
1407         goto post_abort;
1408
1409 reupgrade:
1410         trace_rxrpc_abort(0, "UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1411                           RX_PROTOCOL_ERROR, EBADMSG);
1412         goto protocol_error;
1413
1414 bad_message:
1415         trace_rxrpc_abort(0, "BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1416                           RX_PROTOCOL_ERROR, EBADMSG);
1417 protocol_error:
1418         skb->priority = RX_PROTOCOL_ERROR;
1419 post_abort:
1420         skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
1421 reject_packet:
1422         trace_rxrpc_rx_done(skb->mark, skb->priority);
1423         rxrpc_reject_packet(local, skb);
1424         _leave(" [badmsg]");
1425         return 0;
1426 }