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  * Apply a hard ACK by advancing the Tx window.
 197  */
 198 static bool rxrpc_rotate_tx_window(struct rxrpc_call *call, rxrpc_seq_t to,
 199                                    struct rxrpc_ack_summary *summary)
 200 {
 201         struct sk_buff *skb, *list = NULL;
 202         bool rot_last = false;
 203         int ix;
 204         u8 annotation;
 205
 206         if (call->acks_lowest_nak == call->tx_hard_ack) {
 207                 call->acks_lowest_nak = to;
 208         } else if (before_eq(call->acks_lowest_nak, to)) {
 209                 summary->new_low_nack = true;
 210                 call->acks_lowest_nak = to;
 211         }
 212
 213         spin_lock(&call->lock);
 214
 215         while (before(call->tx_hard_ack, to)) {
 216                 call->tx_hard_ack++;
 217                 ix = call->tx_hard_ack & RXRPC_RXTX_BUFF_MASK;
 218                 skb = call->rxtx_buffer[ix];
 219                 annotation = call->rxtx_annotations[ix];
 220                 rxrpc_see_skb(skb, rxrpc_skb_rotated);
 221                 call->rxtx_buffer[ix] = NULL;
 222                 call->rxtx_annotations[ix] = 0;
 223                 skb->next = list;
 224                 list = skb;
 225
 226                 if (annotation & RXRPC_TX_ANNO_LAST) {
 227                         set_bit(RXRPC_CALL_TX_LAST, &call->flags);
 228                         rot_last = true;
 229                 }
 230                 if ((annotation & RXRPC_TX_ANNO_MASK) != RXRPC_TX_ANNO_ACK)
 231                         summary->nr_rot_new_acks++;
 232         }
 233
 234         spin_unlock(&call->lock);
 235
 236         trace_rxrpc_transmit(call, (rot_last ?
 237                                     rxrpc_transmit_rotate_last :
 238                                     rxrpc_transmit_rotate));
 239         wake_up(&call->waitq);
 240
 241         while (list) {
 242                 skb = list;
 243                 list = skb->next;
 244                 skb_mark_not_on_list(skb);
 245                 rxrpc_free_skb(skb, rxrpc_skb_freed);
 246         }
 247
 248         return rot_last;
 249 }
 250
 251 /*
 252  * End the transmission phase of a call.
 253  *
 254  * This occurs when we get an ACKALL packet, the first DATA packet of a reply,
 255  * or a final ACK packet.
 256  */
 257 static bool rxrpc_end_tx_phase(struct rxrpc_call *call, bool reply_begun,
 258                                const char *abort_why)
 259 {
 260         unsigned int state;
 261
 262         ASSERT(test_bit(RXRPC_CALL_TX_LAST, &call->flags));
 263
 264         write_lock(&call->state_lock);
 265
 266         state = call->state;
 267         switch (state) {
 268         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 269         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 270                 if (reply_begun)
 271                         call->state = state = RXRPC_CALL_CLIENT_RECV_REPLY;
 272                 else
 273                         call->state = state = RXRPC_CALL_CLIENT_AWAIT_REPLY;
 274                 break;
 275
 276         case RXRPC_CALL_SERVER_AWAIT_ACK:
 277                 __rxrpc_call_completed(call);
 278                 rxrpc_notify_socket(call);
 279                 state = call->state;
 280                 break;
 281
 282         default:
 283                 goto bad_state;
 284         }
 285
 286         write_unlock(&call->state_lock);
 287         if (state == RXRPC_CALL_CLIENT_AWAIT_REPLY)
 288                 trace_rxrpc_transmit(call, rxrpc_transmit_await_reply);
 289         else
 290                 trace_rxrpc_transmit(call, rxrpc_transmit_end);
 291         _leave(" = ok");
 292         return true;
 293
 294 bad_state:
 295         write_unlock(&call->state_lock);
 296         kdebug("end_tx %s", rxrpc_call_states[call->state]);
 297         rxrpc_proto_abort(abort_why, call, call->tx_top);
 298         return false;
 299 }
 300
 301 /*
 302  * Begin the reply reception phase of a call.
 303  */
 304 static bool rxrpc_receiving_reply(struct rxrpc_call *call)
 305 {
 306         struct rxrpc_ack_summary summary = { 0 };
 307         unsigned long now, timo;
 308         rxrpc_seq_t top = READ_ONCE(call->tx_top);
 309
 310         if (call->ackr_reason) {
 311                 spin_lock_bh(&call->lock);
 312                 call->ackr_reason = 0;
 313                 spin_unlock_bh(&call->lock);
 314                 now = jiffies;
 315                 timo = now + MAX_JIFFY_OFFSET;
 316                 WRITE_ONCE(call->resend_at, timo);
 317                 WRITE_ONCE(call->ack_at, timo);
 318                 trace_rxrpc_timer(call, rxrpc_timer_init_for_reply, now);
 319         }
 320
 321         if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
 322                 if (!rxrpc_rotate_tx_window(call, top, &summary)) {
 323                         rxrpc_proto_abort("TXL", call, top);
 324                         return false;
 325                 }
 326         }
 327         if (!rxrpc_end_tx_phase(call, true, "ETD"))
 328                 return false;
 329         call->tx_phase = false;
 330         return true;
 331 }
 332
 333 /*
 334  * Scan a data packet to validate its structure and to work out how many
 335  * subpackets it contains.
 336  *
 337  * A jumbo packet is a collection of consecutive packets glued together with
 338  * little headers between that indicate how to change the initial header for
 339  * each subpacket.
 340  *
 341  * RXRPC_JUMBO_PACKET must be set on all but the last subpacket - and all but
 342  * the last are RXRPC_JUMBO_DATALEN in size.  The last subpacket may be of any
 343  * size.
 344  */
 345 static bool rxrpc_validate_data(struct sk_buff *skb)
 346 {
 347         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 348         unsigned int offset = sizeof(struct rxrpc_wire_header);
 349         unsigned int len = skb->len;
 350         u8 flags = sp->hdr.flags;
 351
 352         for (;;) {
 353                 if (flags & RXRPC_REQUEST_ACK)
 354                         __set_bit(sp->nr_subpackets, sp->rx_req_ack);
 355                 sp->nr_subpackets++;
 356
 357                 if (!(flags & RXRPC_JUMBO_PACKET))
 358                         break;
 359
 360                 if (len - offset < RXRPC_JUMBO_SUBPKTLEN)
 361                         goto protocol_error;
 362                 if (flags & RXRPC_LAST_PACKET)
 363                         goto protocol_error;
 364                 offset += RXRPC_JUMBO_DATALEN;
 365                 if (skb_copy_bits(skb, offset, &flags, 1) < 0)
 366                         goto protocol_error;
 367                 offset += sizeof(struct rxrpc_jumbo_header);
 368         }
 369
 370         if (flags & RXRPC_LAST_PACKET)
 371                 sp->rx_flags |= RXRPC_SKB_INCL_LAST;
 372         return true;
 373
 374 protocol_error:
 375         return false;
 376 }
 377
 378 /*
 379  * Handle reception of a duplicate packet.
 380  *
 381  * We have to take care to avoid an attack here whereby we're given a series of
 382  * jumbograms, each with a sequence number one before the preceding one and
 383  * filled up to maximum UDP size.  If they never send us the first packet in
 384  * the sequence, they can cause us to have to hold on to around 2MiB of kernel
 385  * space until the call times out.
 386  *
 387  * We limit the space usage by only accepting three duplicate jumbo packets per
 388  * call.  After that, we tell the other side we're no longer accepting jumbos
 389  * (that information is encoded in the ACK packet).
 390  */
 391 static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
 392                                  bool is_jumbo, bool *_jumbo_bad)
 393 {
 394         /* Discard normal packets that are duplicates. */
 395         if (is_jumbo)
 396                 return;
 397
 398         /* Skip jumbo subpackets that are duplicates.  When we've had three or
 399          * more partially duplicate jumbo packets, we refuse to take any more
 400          * jumbos for this call.
 401          */
 402         if (!*_jumbo_bad) {
 403                 call->nr_jumbo_bad++;
 404                 *_jumbo_bad = true;
 405         }
 406 }
 407
 408 /*
 409  * Process a DATA packet, adding the packet to the Rx ring.  The caller's
 410  * packet ref must be passed on or discarded.
 411  */
 412 static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
 413 {
 414         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 415         enum rxrpc_call_state state;
 416         unsigned int j, nr_subpackets;
 417         rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
 418         rxrpc_seq_t seq0 = sp->hdr.seq, hard_ack;
 419         bool immediate_ack = false, jumbo_bad = false;
 420         u8 ack = 0;
 421
 422         _enter("{%u,%u},{%u,%u}",
 423                call->rx_hard_ack, call->rx_top, skb->len, seq0);
 424
 425         _proto("Rx DATA %%%u { #%u f=%02x n=%u }",
 426                sp->hdr.serial, seq0, sp->hdr.flags, sp->nr_subpackets);
 427
 428         state = READ_ONCE(call->state);
 429         if (state >= RXRPC_CALL_COMPLETE) {
 430                 rxrpc_free_skb(skb, rxrpc_skb_freed);
 431                 return;
 432         }
 433
 434         if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST) {
 435                 unsigned long timo = READ_ONCE(call->next_req_timo);
 436                 unsigned long now, expect_req_by;
 437
 438                 if (timo) {
 439                         now = jiffies;
 440                         expect_req_by = now + timo;
 441                         WRITE_ONCE(call->expect_req_by, expect_req_by);
 442                         rxrpc_reduce_call_timer(call, expect_req_by, now,
 443                                                 rxrpc_timer_set_for_idle);
 444                 }
 445         }
 446
 447         spin_lock(&call->input_lock);
 448
 449         /* Received data implicitly ACKs all of the request packets we sent
 450          * when we're acting as a client.
 451          */
 452         if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
 453              state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
 454             !rxrpc_receiving_reply(call))
 455                 goto unlock;
 456
 457         call->ackr_prev_seq = seq0;
 458         hard_ack = READ_ONCE(call->rx_hard_ack);
 459
 460         nr_subpackets = sp->nr_subpackets;
 461         if (nr_subpackets > 1) {
 462                 if (call->nr_jumbo_bad > 3) {
 463                         ack = RXRPC_ACK_NOSPACE;
 464                         ack_serial = serial;
 465                         goto ack;
 466                 }
 467         }
 468
 469         for (j = 0; j < nr_subpackets; j++) {
 470                 rxrpc_serial_t serial = sp->hdr.serial + j;
 471                 rxrpc_seq_t seq = seq0 + j;
 472                 unsigned int ix = seq & RXRPC_RXTX_BUFF_MASK;
 473                 bool terminal = (j == nr_subpackets - 1);
 474                 bool last = terminal && (sp->rx_flags & RXRPC_SKB_INCL_LAST);
 475                 u8 flags, annotation = j;
 476
 477                 _proto("Rx DATA+%u %%%u { #%x t=%u l=%u }",
 478                      j, serial, seq, terminal, last);
 479
 480                 if (last) {
 481                         if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 482                             seq != call->rx_top) {
 483                                 rxrpc_proto_abort("LSN", call, seq);
 484                                 goto unlock;
 485                         }
 486                 } else {
 487                         if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 488                             after_eq(seq, call->rx_top)) {
 489                                 rxrpc_proto_abort("LSA", call, seq);
 490                                 goto unlock;
 491                         }
 492                 }
 493
 494                 flags = 0;
 495                 if (last)
 496                         flags |= RXRPC_LAST_PACKET;
 497                 if (!terminal)
 498                         flags |= RXRPC_JUMBO_PACKET;
 499                 if (test_bit(j, sp->rx_req_ack))
 500                         flags |= RXRPC_REQUEST_ACK;
 501                 trace_rxrpc_rx_data(call->debug_id, seq, serial, flags, annotation);
 502
 503                 if (before_eq(seq, hard_ack)) {
 504                         ack = RXRPC_ACK_DUPLICATE;
 505                         ack_serial = serial;
 506                         continue;
 507                 }
 508
 509                 if (call->rxtx_buffer[ix]) {
 510                         rxrpc_input_dup_data(call, seq, nr_subpackets > 1,
 511                                              &jumbo_bad);
 512                         if (ack != RXRPC_ACK_DUPLICATE) {
 513                                 ack = RXRPC_ACK_DUPLICATE;
 514                                 ack_serial = serial;
 515                         }
 516                         immediate_ack = true;
 517                         continue;
 518                 }
 519
 520                 if (after(seq, hard_ack + call->rx_winsize)) {
 521                         ack = RXRPC_ACK_EXCEEDS_WINDOW;
 522                         ack_serial = serial;
 523                         if (flags & RXRPC_JUMBO_PACKET) {
 524                                 if (!jumbo_bad) {
 525                                         call->nr_jumbo_bad++;
 526                                         jumbo_bad = true;
 527                                 }
 528                         }
 529
 530                         goto ack;
 531                 }
 532
 533                 if (flags & RXRPC_REQUEST_ACK && !ack) {
 534                         ack = RXRPC_ACK_REQUESTED;
 535                         ack_serial = serial;
 536                 }
 537
 538                 /* Queue the packet.  We use a couple of memory barriers here as need
 539                  * to make sure that rx_top is perceived to be set after the buffer
 540                  * pointer and that the buffer pointer is set after the annotation and
 541                  * the skb data.
 542                  *
 543                  * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
 544                  * and also rxrpc_fill_out_ack().
 545                  */
 546                 if (!terminal)
 547                         rxrpc_get_skb(skb, rxrpc_skb_got);
 548                 call->rxtx_annotations[ix] = annotation;
 549                 smp_wmb();
 550                 call->rxtx_buffer[ix] = skb;
 551                 if (after(seq, call->rx_top)) {
 552                         smp_store_release(&call->rx_top, seq);
 553                 } else if (before(seq, call->rx_top)) {
 554                         /* Send an immediate ACK if we fill in a hole */
 555                         if (!ack) {
 556                                 ack = RXRPC_ACK_DELAY;
 557                                 ack_serial = serial;
 558                         }
 559                         immediate_ack = true;
 560                 }
 561
 562                 if (terminal) {
 563                         /* From this point on, we're not allowed to touch the
 564                          * packet any longer as its ref now belongs to the Rx
 565                          * ring.
 566                          */
 567                         skb = NULL;
 568                         sp = NULL;
 569                 }
 570
 571                 if (last) {
 572                         set_bit(RXRPC_CALL_RX_LAST, &call->flags);
 573                         if (!ack) {
 574                                 ack = RXRPC_ACK_DELAY;
 575                                 ack_serial = serial;
 576                         }
 577                         trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
 578                 } else {
 579                         trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
 580                 }
 581
 582                 if (after_eq(seq, call->rx_expect_next)) {
 583                         if (after(seq, call->rx_expect_next)) {
 584                                 _net("OOS %u > %u", seq, call->rx_expect_next);
 585                                 ack = RXRPC_ACK_OUT_OF_SEQUENCE;
 586                                 ack_serial = serial;
 587                         }
 588                         call->rx_expect_next = seq + 1;
 589                 }
 590         }
 591
 592 ack:
 593         if (ack)
 594                 rxrpc_propose_ACK(call, ack, ack_serial,
 595                                   immediate_ack, true,
 596                                   rxrpc_propose_ack_input_data);
 597         else
 598                 rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial,
 599                                   false, true,
 600                                   rxrpc_propose_ack_input_data);
 601
 602         if (seq0 == READ_ONCE(call->rx_hard_ack) + 1) {
 603                 trace_rxrpc_notify_socket(call->debug_id, serial);
 604                 rxrpc_notify_socket(call);
 605         }
 606
 607 unlock:
 608         spin_unlock(&call->input_lock);
 609         rxrpc_free_skb(skb, rxrpc_skb_freed);
 610         _leave(" [queued]");
 611 }
 612
 613 /*
 614  * Process a requested ACK.
 615  */
 616 static void rxrpc_input_requested_ack(struct rxrpc_call *call,
 617                                       ktime_t resp_time,
 618                                       rxrpc_serial_t orig_serial,
 619                                       rxrpc_serial_t ack_serial)
 620 {
 621         struct rxrpc_skb_priv *sp;
 622         struct sk_buff *skb;
 623         ktime_t sent_at;
 624         int ix;
 625
 626         for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
 627                 skb = call->rxtx_buffer[ix];
 628                 if (!skb)
 629                         continue;
 630
 631                 sent_at = skb->tstamp;
 632                 smp_rmb(); /* Read timestamp before serial. */
 633                 sp = rxrpc_skb(skb);
 634                 if (sp->hdr.serial != orig_serial)
 635                         continue;
 636                 goto found;
 637         }
 638
 639         return;
 640
 641 found:
 642         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
 643                            orig_serial, ack_serial, sent_at, resp_time);
 644 }
 645
 646 /*
 647  * Process the response to a ping that we sent to find out if we lost an ACK.
 648  *
 649  * If we got back a ping response that indicates a lower tx_top than what we
 650  * had at the time of the ping transmission, we adjudge all the DATA packets
 651  * sent between the response tx_top and the ping-time tx_top to have been lost.
 652  */
 653 static void rxrpc_input_check_for_lost_ack(struct rxrpc_call *call)
 654 {
 655         rxrpc_seq_t top, bottom, seq;
 656         bool resend = false;
 657
 658         spin_lock_bh(&call->lock);
 659
 660         bottom = call->tx_hard_ack + 1;
 661         top = call->acks_lost_top;
 662         if (before(bottom, top)) {
 663                 for (seq = bottom; before_eq(seq, top); seq++) {
 664                         int ix = seq & RXRPC_RXTX_BUFF_MASK;
 665                         u8 annotation = call->rxtx_annotations[ix];
 666                         u8 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 667
 668                         if (anno_type != RXRPC_TX_ANNO_UNACK)
 669                                 continue;
 670                         annotation &= ~RXRPC_TX_ANNO_MASK;
 671                         annotation |= RXRPC_TX_ANNO_RETRANS;
 672                         call->rxtx_annotations[ix] = annotation;
 673                         resend = true;
 674                 }
 675         }
 676
 677         spin_unlock_bh(&call->lock);
 678
 679         if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 680                 rxrpc_queue_call(call);
 681 }
 682
 683 /*
 684  * Process a ping response.
 685  */
 686 static void rxrpc_input_ping_response(struct rxrpc_call *call,
 687                                       ktime_t resp_time,
 688                                       rxrpc_serial_t orig_serial,
 689                                       rxrpc_serial_t ack_serial)
 690 {
 691         rxrpc_serial_t ping_serial;
 692         ktime_t ping_time;
 693
 694         ping_time = call->ping_time;
 695         smp_rmb();
 696         ping_serial = READ_ONCE(call->ping_serial);
 697
 698         if (orig_serial == call->acks_lost_ping)
 699                 rxrpc_input_check_for_lost_ack(call);
 700
 701         if (before(orig_serial, ping_serial) ||
 702             !test_and_clear_bit(RXRPC_CALL_PINGING, &call->flags))
 703                 return;
 704         if (after(orig_serial, ping_serial))
 705                 return;
 706
 707         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
 708                            orig_serial, ack_serial, ping_time, resp_time);
 709 }
 710
 711 /*
 712  * Process the extra information that may be appended to an ACK packet
 713  */
 714 static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 715                                 struct rxrpc_ackinfo *ackinfo)
 716 {
 717         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 718         struct rxrpc_peer *peer;
 719         unsigned int mtu;
 720         bool wake = false;
 721         u32 rwind = ntohl(ackinfo->rwind);
 722
 723         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 724                sp->hdr.serial,
 725                ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
 726                rwind, ntohl(ackinfo->jumbo_max));
 727
 728         if (call->tx_winsize != rwind) {
 729                 if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
 730                         rwind = RXRPC_RXTX_BUFF_SIZE - 1;
 731                 if (rwind > call->tx_winsize)
 732                         wake = true;
 733                 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial,
 734                                             ntohl(ackinfo->rwind), wake);
 735                 call->tx_winsize = rwind;
 736         }
 737
 738         if (call->cong_ssthresh > rwind)
 739                 call->cong_ssthresh = rwind;
 740
 741         mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
 742
 743         peer = call->peer;
 744         if (mtu < peer->maxdata) {
 745                 spin_lock_bh(&peer->lock);
 746                 peer->maxdata = mtu;
 747                 peer->mtu = mtu + peer->hdrsize;
 748                 spin_unlock_bh(&peer->lock);
 749                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 750         }
 751
 752         if (wake)
 753                 wake_up(&call->waitq);
 754 }
 755
 756 /*
 757  * Process individual soft ACKs.
 758  *
 759  * Each ACK in the array corresponds to one packet and can be either an ACK or
 760  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 761  * packets that lie beyond the end of the ACK list are scheduled for resend by
 762  * the timer on the basis that the peer might just not have processed them at
 763  * the time the ACK was sent.
 764  */
 765 static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 766                                   rxrpc_seq_t seq, int nr_acks,
 767                                   struct rxrpc_ack_summary *summary)
 768 {
 769         int ix;
 770         u8 annotation, anno_type;
 771
 772         for (; nr_acks > 0; nr_acks--, seq++) {
 773                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 774                 annotation = call->rxtx_annotations[ix];
 775                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 776                 annotation &= ~RXRPC_TX_ANNO_MASK;
 777                 switch (*acks++) {
 778                 case RXRPC_ACK_TYPE_ACK:
 779                         summary->nr_acks++;
 780                         if (anno_type == RXRPC_TX_ANNO_ACK)
 781                                 continue;
 782                         summary->nr_new_acks++;
 783                         call->rxtx_annotations[ix] =
 784                                 RXRPC_TX_ANNO_ACK | annotation;
 785                         break;
 786                 case RXRPC_ACK_TYPE_NACK:
 787                         if (!summary->nr_nacks &&
 788                             call->acks_lowest_nak != seq) {
 789                                 call->acks_lowest_nak = seq;
 790                                 summary->new_low_nack = true;
 791                         }
 792                         summary->nr_nacks++;
 793                         if (anno_type == RXRPC_TX_ANNO_NAK)
 794                                 continue;
 795                         summary->nr_new_nacks++;
 796                         if (anno_type == RXRPC_TX_ANNO_RETRANS)
 797                                 continue;
 798                         call->rxtx_annotations[ix] =
 799                                 RXRPC_TX_ANNO_NAK | annotation;
 800                         break;
 801                 default:
 802                         return rxrpc_proto_abort("SFT", call, 0);
 803                 }
 804         }
 805 }
 806
 807 /*
 808  * Process an ACK packet.
 809  *
 810  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 811  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 812  *
 813  * A hard-ACK means that a packet has been processed and may be discarded; a
 814  * soft-ACK means that the packet may be discarded and retransmission
 815  * requested.  A phase is complete when all packets are hard-ACK'd.
 816  */
 817 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 818 {
 819         struct rxrpc_ack_summary summary = { 0 };
 820         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 821         union {
 822                 struct rxrpc_ackpacket ack;
 823                 struct rxrpc_ackinfo info;
 824                 u8 acks[RXRPC_MAXACKS];
 825         } buf;
 826         rxrpc_serial_t acked_serial;
 827         rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
 828         int nr_acks, offset, ioffset;
 829
 830         _enter("");
 831
 832         offset = sizeof(struct rxrpc_wire_header);
 833         if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
 834                 _debug("extraction failure");
 835                 return rxrpc_proto_abort("XAK", call, 0);
 836         }
 837         offset += sizeof(buf.ack);
 838
 839         acked_serial = ntohl(buf.ack.serial);
 840         first_soft_ack = ntohl(buf.ack.firstPacket);
 841         prev_pkt = ntohl(buf.ack.previousPacket);
 842         hard_ack = first_soft_ack - 1;
 843         nr_acks = buf.ack.nAcks;
 844         summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
 845                               buf.ack.reason : RXRPC_ACK__INVALID);
 846
 847         trace_rxrpc_rx_ack(call, sp->hdr.serial, acked_serial,
 848                            first_soft_ack, prev_pkt,
 849                            summary.ack_reason, nr_acks);
 850
 851         if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
 852                 rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
 853                                           sp->hdr.serial);
 854         if (buf.ack.reason == RXRPC_ACK_REQUESTED)
 855                 rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
 856                                           sp->hdr.serial);
 857
 858         if (buf.ack.reason == RXRPC_ACK_PING) {
 859                 _proto("Rx ACK %%%u PING Request", sp->hdr.serial);
 860                 rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 861                                   sp->hdr.serial, true, true,
 862                                   rxrpc_propose_ack_respond_to_ping);
 863         } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 864                 rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 865                                   sp->hdr.serial, true, true,
 866                                   rxrpc_propose_ack_respond_to_ack);
 867         }
 868
 869         /* Discard any out-of-order or duplicate ACKs (outside lock). */
 870         if (before(first_soft_ack, call->ackr_first_seq) ||
 871             before(prev_pkt, call->ackr_prev_seq))
 872                 return;
 873
 874         buf.info.rxMTU = 0;
 875         ioffset = offset + nr_acks + 3;
 876         if (skb->len >= ioffset + sizeof(buf.info) &&
 877             skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
 878                 return rxrpc_proto_abort("XAI", call, 0);
 879
 880         spin_lock(&call->input_lock);
 881
 882         /* Discard any out-of-order or duplicate ACKs (inside lock). */
 883         if (before(first_soft_ack, call->ackr_first_seq) ||
 884             before(prev_pkt, call->ackr_prev_seq))
 885                 goto out;
 886         call->acks_latest_ts = skb->tstamp;
 887         call->acks_latest = sp->hdr.serial;
 888
 889         call->ackr_first_seq = first_soft_ack;
 890         call->ackr_prev_seq = prev_pkt;
 891
 892         /* Parse rwind and mtu sizes if provided. */
 893         if (buf.info.rxMTU)
 894                 rxrpc_input_ackinfo(call, skb, &buf.info);
 895
 896         if (first_soft_ack == 0) {
 897                 rxrpc_proto_abort("AK0", call, 0);
 898                 goto out;
 899         }
 900
 901         /* Ignore ACKs unless we are or have just been transmitting. */
 902         switch (READ_ONCE(call->state)) {
 903         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 904         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 905         case RXRPC_CALL_SERVER_SEND_REPLY:
 906         case RXRPC_CALL_SERVER_AWAIT_ACK:
 907                 break;
 908         default:
 909                 goto out;
 910         }
 911
 912         if (before(hard_ack, call->tx_hard_ack) ||
 913             after(hard_ack, call->tx_top)) {
 914                 rxrpc_proto_abort("AKW", call, 0);
 915                 goto out;
 916         }
 917         if (nr_acks > call->tx_top - hard_ack) {
 918                 rxrpc_proto_abort("AKN", call, 0);
 919                 goto out;
 920         }
 921
 922         if (after(hard_ack, call->tx_hard_ack)) {
 923                 if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
 924                         rxrpc_end_tx_phase(call, false, "ETA");
 925                         goto out;
 926                 }
 927         }
 928
 929         if (nr_acks > 0) {
 930                 if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0) {
 931                         rxrpc_proto_abort("XSA", call, 0);
 932                         goto out;
 933                 }
 934                 rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
 935                                       &summary);
 936         }
 937
 938         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 939             RXRPC_TX_ANNO_LAST &&
 940             summary.nr_acks == call->tx_top - hard_ack &&
 941             rxrpc_is_client_call(call))
 942                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
 943                                   false, true,
 944                                   rxrpc_propose_ack_ping_for_lost_reply);
 945
 946         rxrpc_congestion_management(call, skb, &summary, acked_serial);
 947 out:
 948         spin_unlock(&call->input_lock);
 949 }
 950
 951 /*
 952  * Process an ACKALL packet.
 953  */
 954 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
 955 {
 956         struct rxrpc_ack_summary summary = { 0 };
 957         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 958
 959         _proto("Rx ACKALL %%%u", sp->hdr.serial);
 960
 961         spin_lock(&call->input_lock);
 962
 963         if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
 964                 rxrpc_end_tx_phase(call, false, "ETL");
 965
 966         spin_unlock(&call->input_lock);
 967 }
 968
 969 /*
 970  * Process an ABORT packet directed at a call.
 971  */
 972 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
 973 {
 974         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 975         __be32 wtmp;
 976         u32 abort_code = RX_CALL_DEAD;
 977
 978         _enter("");
 979
 980         if (skb->len >= 4 &&
 981             skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
 982                           &wtmp, sizeof(wtmp)) >= 0)
 983                 abort_code = ntohl(wtmp);
 984
 985         trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
 986
 987         _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
 988
 989         if (rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
 990                                       abort_code, -ECONNABORTED))
 991                 rxrpc_notify_socket(call);
 992 }
 993
 994 /*
 995  * Process an incoming call packet.
 996  */
 997 static void rxrpc_input_call_packet(struct rxrpc_call *call,
 998                                     struct sk_buff *skb)
 999 {
1000         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1001         unsigned long timo;
1002
1003         _enter("%p,%p", call, skb);
1004
1005         timo = READ_ONCE(call->next_rx_timo);
1006         if (timo) {
1007                 unsigned long now = jiffies, expect_rx_by;
1008
1009                 expect_rx_by = now + timo;
1010                 WRITE_ONCE(call->expect_rx_by, expect_rx_by);
1011                 rxrpc_reduce_call_timer(call, expect_rx_by, now,
1012                                         rxrpc_timer_set_for_normal);
1013         }
1014
1015         switch (sp->hdr.type) {
1016         case RXRPC_PACKET_TYPE_DATA:
1017                 rxrpc_input_data(call, skb);
1018                 goto no_free;
1019
1020         case RXRPC_PACKET_TYPE_ACK:
1021                 rxrpc_input_ack(call, skb);
1022                 break;
1023
1024         case RXRPC_PACKET_TYPE_BUSY:
1025                 _proto("Rx BUSY %%%u", sp->hdr.serial);
1026
1027                 /* Just ignore BUSY packets from the server; the retry and
1028                  * lifespan timers will take care of business.  BUSY packets
1029                  * from the client don't make sense.
1030                  */
1031                 break;
1032
1033         case RXRPC_PACKET_TYPE_ABORT:
1034                 rxrpc_input_abort(call, skb);
1035                 break;
1036
1037         case RXRPC_PACKET_TYPE_ACKALL:
1038                 rxrpc_input_ackall(call, skb);
1039                 break;
1040
1041         default:
1042                 break;
1043         }
1044
1045         rxrpc_free_skb(skb, rxrpc_skb_freed);
1046 no_free:
1047         _leave("");
1048 }
1049
1050 /*
1051  * Handle a new service call on a channel implicitly completing the preceding
1052  * call on that channel.  This does not apply to client conns.
1053  *
1054  * TODO: If callNumber > call_id + 1, renegotiate security.
1055  */
1056 static void rxrpc_input_implicit_end_call(struct rxrpc_sock *rx,
1057                                           struct rxrpc_connection *conn,
1058                                           struct rxrpc_call *call)
1059 {
1060         switch (READ_ONCE(call->state)) {
1061         case RXRPC_CALL_SERVER_AWAIT_ACK:
1062                 rxrpc_call_completed(call);
1063                 /* Fall through */
1064         case RXRPC_CALL_COMPLETE:
1065                 break;
1066         default:
1067                 if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
1068                         set_bit(RXRPC_CALL_EV_ABORT, &call->events);
1069                         rxrpc_queue_call(call);
1070                 }
1071                 trace_rxrpc_improper_term(call);
1072                 break;
1073         }
1074
1075         spin_lock(&rx->incoming_lock);
1076         __rxrpc_disconnect_call(conn, call);
1077         spin_unlock(&rx->incoming_lock);
1078         rxrpc_notify_socket(call);
1079 }
1080
1081 /*
1082  * post connection-level events to the connection
1083  * - this includes challenges, responses, some aborts and call terminal packet
1084  *   retransmission.
1085  */
1086 static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
1087                                       struct sk_buff *skb)
1088 {
1089         _enter("%p,%p", conn, skb);
1090
1091         skb_queue_tail(&conn->rx_queue, skb);
1092         rxrpc_queue_conn(conn);
1093 }
1094
1095 /*
1096  * post endpoint-level events to the local endpoint
1097  * - this includes debug and version messages
1098  */
1099 static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
1100                                        struct sk_buff *skb)
1101 {
1102         _enter("%p,%p", local, skb);
1103
1104         if (rxrpc_get_local_maybe(local)) {
1105                 skb_queue_tail(&local->event_queue, skb);
1106                 rxrpc_queue_local(local);
1107         } else {
1108                 rxrpc_free_skb(skb, rxrpc_skb_freed);
1109         }
1110 }
1111
1112 /*
1113  * put a packet up for transport-level abort
1114  */
1115 static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
1116 {
1117         CHECK_SLAB_OKAY(&local->usage);
1118
1119         if (rxrpc_get_local_maybe(local)) {
1120                 skb_queue_tail(&local->reject_queue, skb);
1121                 rxrpc_queue_local(local);
1122         } else {
1123                 rxrpc_free_skb(skb, rxrpc_skb_freed);
1124         }
1125 }
1126
1127 /*
1128  * Extract the wire header from a packet and translate the byte order.
1129  */
1130 static noinline
1131 int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
1132 {
1133         struct rxrpc_wire_header whdr;
1134
1135         /* dig out the RxRPC connection details */
1136         if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0) {
1137                 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
1138                                       tracepoint_string("bad_hdr"));
1139                 return -EBADMSG;
1140         }
1141
1142         memset(sp, 0, sizeof(*sp));
1143         sp->hdr.epoch           = ntohl(whdr.epoch);
1144         sp->hdr.cid             = ntohl(whdr.cid);
1145         sp->hdr.callNumber      = ntohl(whdr.callNumber);
1146         sp->hdr.seq             = ntohl(whdr.seq);
1147         sp->hdr.serial          = ntohl(whdr.serial);
1148         sp->hdr.flags           = whdr.flags;
1149         sp->hdr.type            = whdr.type;
1150         sp->hdr.userStatus      = whdr.userStatus;
1151         sp->hdr.securityIndex   = whdr.securityIndex;
1152         sp->hdr._rsvd           = ntohs(whdr._rsvd);
1153         sp->hdr.serviceId       = ntohs(whdr.serviceId);
1154         return 0;
1155 }
1156
1157 /*
1158  * handle data received on the local endpoint
1159  * - may be called in interrupt context
1160  *
1161  * [!] Note that as this is called from the encap_rcv hook, the socket is not
1162  * held locked by the caller and nothing prevents sk_user_data on the UDP from
1163  * being cleared in the middle of processing this function.
1164  *
1165  * Called with the RCU read lock held from the IP layer via UDP.
1166  */
1167 int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
1168 {
1169         struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
1170         struct rxrpc_connection *conn;
1171         struct rxrpc_channel *chan;
1172         struct rxrpc_call *call = NULL;
1173         struct rxrpc_skb_priv *sp;
1174         struct rxrpc_peer *peer = NULL;
1175         struct rxrpc_sock *rx = NULL;
1176         unsigned int channel;
1177
1178         _enter("%p", udp_sk);
1179
1180         if (unlikely(!local)) {
1181                 kfree_skb(skb);
1182                 return 0;
1183         }
1184         if (skb->tstamp == 0)
1185                 skb->tstamp = ktime_get_real();
1186
1187         rxrpc_new_skb(skb, rxrpc_skb_received);
1188
1189         skb_pull(skb, sizeof(struct udphdr));
1190
1191         /* The UDP protocol already released all skb resources;
1192          * we are free to add our own data there.
1193          */
1194         sp = rxrpc_skb(skb);
1195
1196         /* dig out the RxRPC connection details */
1197         if (rxrpc_extract_header(sp, skb) < 0)
1198                 goto bad_message;
1199
1200         if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
1201                 static int lose;
1202                 if ((lose++ & 7) == 7) {
1203                         trace_rxrpc_rx_lose(sp);
1204                         rxrpc_free_skb(skb, rxrpc_skb_lost);
1205                         return 0;
1206                 }
1207         }
1208
1209         if (skb->tstamp == 0)
1210                 skb->tstamp = ktime_get_real();
1211         trace_rxrpc_rx_packet(sp);
1212
1213         switch (sp->hdr.type) {
1214         case RXRPC_PACKET_TYPE_VERSION:
1215                 if (rxrpc_to_client(sp))
1216                         goto discard;
1217                 rxrpc_post_packet_to_local(local, skb);
1218                 goto out;
1219
1220         case RXRPC_PACKET_TYPE_BUSY:
1221                 if (rxrpc_to_server(sp))
1222                         goto discard;
1223                 /* Fall through */
1224         case RXRPC_PACKET_TYPE_ACK:
1225         case RXRPC_PACKET_TYPE_ACKALL:
1226                 if (sp->hdr.callNumber == 0)
1227                         goto bad_message;
1228                 /* Fall through */
1229         case RXRPC_PACKET_TYPE_ABORT:
1230                 break;
1231
1232         case RXRPC_PACKET_TYPE_DATA:
1233                 if (sp->hdr.callNumber == 0 ||
1234                     sp->hdr.seq == 0)
1235                         goto bad_message;
1236                 if (!rxrpc_validate_data(skb))
1237                         goto bad_message;
1238
1239                 /* Unshare the packet so that it can be modified for in-place
1240                  * decryption.
1241                  */
1242                 if (sp->hdr.securityIndex != 0) {
1243                         struct sk_buff *nskb = skb_unshare(skb, GFP_ATOMIC);
1244                         if (!nskb) {
1245                                 rxrpc_eaten_skb(skb, rxrpc_skb_unshared_nomem);
1246                                 goto out;
1247                         }
1248
1249                         if (nskb != skb) {
1250                                 rxrpc_eaten_skb(skb, rxrpc_skb_received);
1251                                 skb = nskb;
1252                                 rxrpc_new_skb(skb, rxrpc_skb_unshared);
1253                                 sp = rxrpc_skb(skb);
1254                         }
1255                 }
1256                 break;
1257
1258         case RXRPC_PACKET_TYPE_CHALLENGE:
1259                 if (rxrpc_to_server(sp))
1260                         goto discard;
1261                 break;
1262         case RXRPC_PACKET_TYPE_RESPONSE:
1263                 if (rxrpc_to_client(sp))
1264                         goto discard;
1265                 break;
1266
1267                 /* Packet types 9-11 should just be ignored. */
1268         case RXRPC_PACKET_TYPE_PARAMS:
1269         case RXRPC_PACKET_TYPE_10:
1270         case RXRPC_PACKET_TYPE_11:
1271                 goto discard;
1272
1273         default:
1274                 _proto("Rx Bad Packet Type %u", sp->hdr.type);
1275                 goto bad_message;
1276         }
1277
1278         if (sp->hdr.serviceId == 0)
1279                 goto bad_message;
1280
1281         if (rxrpc_to_server(sp)) {
1282                 /* Weed out packets to services we're not offering.  Packets
1283                  * that would begin a call are explicitly rejected and the rest
1284                  * are just discarded.
1285                  */
1286                 rx = rcu_dereference(local->service);
1287                 if (!rx || (sp->hdr.serviceId != rx->srx.srx_service &&
1288                             sp->hdr.serviceId != rx->second_service)) {
1289                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
1290                             sp->hdr.seq == 1)
1291                                 goto unsupported_service;
1292                         goto discard;
1293                 }
1294         }
1295
1296         conn = rxrpc_find_connection_rcu(local, skb, &peer);
1297         if (conn) {
1298                 if (sp->hdr.securityIndex != conn->security_ix)
1299                         goto wrong_security;
1300
1301                 if (sp->hdr.serviceId != conn->service_id) {
1302                         int old_id;
1303
1304                         if (!test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags))
1305                                 goto reupgrade;
1306                         old_id = cmpxchg(&conn->service_id, conn->params.service_id,
1307                                          sp->hdr.serviceId);
1308
1309                         if (old_id != conn->params.service_id &&
1310                             old_id != sp->hdr.serviceId)
1311                                 goto reupgrade;
1312                 }
1313
1314                 if (sp->hdr.callNumber == 0) {
1315                         /* Connection-level packet */
1316                         _debug("CONN %p {%d}", conn, conn->debug_id);
1317                         rxrpc_post_packet_to_conn(conn, skb);
1318                         goto out;
1319                 }
1320
1321                 if ((int)sp->hdr.serial - (int)conn->hi_serial > 0)
1322                         conn->hi_serial = sp->hdr.serial;
1323
1324                 /* Call-bound packets are routed by connection channel. */
1325                 channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1326                 chan = &conn->channels[channel];
1327
1328                 /* Ignore really old calls */
1329                 if (sp->hdr.callNumber < chan->last_call)
1330                         goto discard;
1331
1332                 if (sp->hdr.callNumber == chan->last_call) {
1333                         if (chan->call ||
1334                             sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
1335                                 goto discard;
1336
1337                         /* For the previous service call, if completed
1338                          * successfully, we discard all further packets.
1339                          */
1340                         if (rxrpc_conn_is_service(conn) &&
1341                             chan->last_type == RXRPC_PACKET_TYPE_ACK)
1342                                 goto discard;
1343
1344                         /* But otherwise we need to retransmit the final packet
1345                          * from data cached in the connection record.
1346                          */
1347                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
1348                                 trace_rxrpc_rx_data(chan->call_debug_id,
1349                                                     sp->hdr.seq,
1350                                                     sp->hdr.serial,
1351                                                     sp->hdr.flags, 0);
1352                         rxrpc_post_packet_to_conn(conn, skb);
1353                         goto out;
1354                 }
1355
1356                 call = rcu_dereference(chan->call);
1357
1358                 if (sp->hdr.callNumber > chan->call_id) {
1359                         if (rxrpc_to_client(sp))
1360                                 goto reject_packet;
1361                         if (call)
1362                                 rxrpc_input_implicit_end_call(rx, conn, call);
1363                         call = NULL;
1364                 }
1365
1366                 if (call) {
1367                         if (sp->hdr.serviceId != call->service_id)
1368                                 call->service_id = sp->hdr.serviceId;
1369                         if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
1370                                 call->rx_serial = sp->hdr.serial;
1371                         if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
1372                                 set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
1373                 }
1374         }
1375
1376         if (!call || atomic_read(&call->usage) == 0) {
1377                 if (rxrpc_to_client(sp) ||
1378                     sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1379                         goto bad_message;
1380                 if (sp->hdr.seq != 1)
1381                         goto discard;
1382                 call = rxrpc_new_incoming_call(local, rx, skb);
1383                 if (!call)
1384                         goto reject_packet;
1385         }
1386
1387         /* Process a call packet; this either discards or passes on the ref
1388          * elsewhere.
1389          */
1390         rxrpc_input_call_packet(call, skb);
1391         goto out;
1392
1393 discard:
1394         rxrpc_free_skb(skb, rxrpc_skb_freed);
1395 out:
1396         trace_rxrpc_rx_done(0, 0);
1397         return 0;
1398
1399 wrong_security:
1400         trace_rxrpc_abort(0, "SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1401                           RXKADINCONSISTENCY, EBADMSG);
1402         skb->priority = RXKADINCONSISTENCY;
1403         goto post_abort;
1404
1405 unsupported_service:
1406         trace_rxrpc_abort(0, "INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1407                           RX_INVALID_OPERATION, EOPNOTSUPP);
1408         skb->priority = RX_INVALID_OPERATION;
1409         goto post_abort;
1410
1411 reupgrade:
1412         trace_rxrpc_abort(0, "UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1413                           RX_PROTOCOL_ERROR, EBADMSG);
1414         goto protocol_error;
1415
1416 bad_message:
1417         trace_rxrpc_abort(0, "BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1418                           RX_PROTOCOL_ERROR, EBADMSG);
1419 protocol_error:
1420         skb->priority = RX_PROTOCOL_ERROR;
1421 post_abort:
1422         skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
1423 reject_packet:
1424         trace_rxrpc_rx_done(skb->mark, skb->priority);
1425         rxrpc_reject_packet(local, skb);
1426         _leave(" [badmsg]");
1427         return 0;
1428 }