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_count == 0)
  95                         goto out;
  96                 if (ktime_before(skb->tstamp,
  97                                  ktime_add_us(call->cong_tstamp,
  98                                               call->peer->srtt_us >> 3)))
  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, nr_unacked = 0;
 417         rxrpc_serial_t serial = sp->hdr.serial, ack_serial = serial;
 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 (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         hard_ack = READ_ONCE(call->rx_hard_ack);
 458
 459         nr_subpackets = sp->nr_subpackets;
 460         if (nr_subpackets > 1) {
 461                 if (call->nr_jumbo_bad > 3) {
 462                         ack = RXRPC_ACK_NOSPACE;
 463                         ack_serial = serial;
 464                         goto ack;
 465                 }
 466         }
 467
 468         for (j = 0; j < nr_subpackets; j++) {
 469                 rxrpc_serial_t serial = sp->hdr.serial + j;
 470                 rxrpc_seq_t seq = seq0 + j;
 471                 unsigned int ix = seq & RXRPC_RXTX_BUFF_MASK;
 472                 bool terminal = (j == nr_subpackets - 1);
 473                 bool last = terminal && (sp->rx_flags & RXRPC_SKB_INCL_LAST);
 474                 u8 flags, annotation = j;
 475
 476                 _proto("Rx DATA+%u %%%u { #%x t=%u l=%u }",
 477                      j, serial, seq, terminal, last);
 478
 479                 if (last) {
 480                         if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 481                             seq != call->rx_top) {
 482                                 rxrpc_proto_abort("LSN", call, seq);
 483                                 goto unlock;
 484                         }
 485                 } else {
 486                         if (test_bit(RXRPC_CALL_RX_LAST, &call->flags) &&
 487                             after_eq(seq, call->rx_top)) {
 488                                 rxrpc_proto_abort("LSA", call, seq);
 489                                 goto unlock;
 490                         }
 491                 }
 492
 493                 flags = 0;
 494                 if (last)
 495                         flags |= RXRPC_LAST_PACKET;
 496                 if (!terminal)
 497                         flags |= RXRPC_JUMBO_PACKET;
 498                 if (test_bit(j, sp->rx_req_ack))
 499                         flags |= RXRPC_REQUEST_ACK;
 500                 trace_rxrpc_rx_data(call->debug_id, seq, serial, flags, annotation);
 501
 502                 if (before_eq(seq, hard_ack)) {
 503                         ack = RXRPC_ACK_DUPLICATE;
 504                         ack_serial = serial;
 505                         continue;
 506                 }
 507
 508                 if (call->rxtx_buffer[ix]) {
 509                         rxrpc_input_dup_data(call, seq, nr_subpackets > 1,
 510                                              &jumbo_bad);
 511                         if (ack != RXRPC_ACK_DUPLICATE) {
 512                                 ack = RXRPC_ACK_DUPLICATE;
 513                                 ack_serial = serial;
 514                         }
 515                         immediate_ack = true;
 516                         continue;
 517                 }
 518
 519                 if (after(seq, hard_ack + call->rx_winsize)) {
 520                         ack = RXRPC_ACK_EXCEEDS_WINDOW;
 521                         ack_serial = serial;
 522                         if (flags & RXRPC_JUMBO_PACKET) {
 523                                 if (!jumbo_bad) {
 524                                         call->nr_jumbo_bad++;
 525                                         jumbo_bad = true;
 526                                 }
 527                         }
 528
 529                         goto ack;
 530                 }
 531
 532                 if (flags & RXRPC_REQUEST_ACK && !ack) {
 533                         ack = RXRPC_ACK_REQUESTED;
 534                         ack_serial = serial;
 535                 }
 536
 537                 if (after(seq0, call->ackr_highest_seq))
 538                         call->ackr_highest_seq = seq0;
 539
 540                 /* Queue the packet.  We use a couple of memory barriers here as need
 541                  * to make sure that rx_top is perceived to be set after the buffer
 542                  * pointer and that the buffer pointer is set after the annotation and
 543                  * the skb data.
 544                  *
 545                  * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
 546                  * and also rxrpc_fill_out_ack().
 547                  */
 548                 if (!terminal)
 549                         rxrpc_get_skb(skb, rxrpc_skb_got);
 550                 call->rxtx_annotations[ix] = annotation;
 551                 smp_wmb();
 552                 call->rxtx_buffer[ix] = skb;
 553                 if (after(seq, call->rx_top)) {
 554                         smp_store_release(&call->rx_top, seq);
 555                 } else if (before(seq, call->rx_top)) {
 556                         /* Send an immediate ACK if we fill in a hole */
 557                         if (!ack) {
 558                                 ack = RXRPC_ACK_DELAY;
 559                                 ack_serial = serial;
 560                         }
 561                         immediate_ack = true;
 562                 }
 563
 564                 if (terminal) {
 565                         /* From this point on, we're not allowed to touch the
 566                          * packet any longer as its ref now belongs to the Rx
 567                          * ring.
 568                          */
 569                         skb = NULL;
 570                         sp = NULL;
 571                 }
 572
 573                 nr_unacked++;
 574
 575                 if (last) {
 576                         set_bit(RXRPC_CALL_RX_LAST, &call->flags);
 577                         if (!ack) {
 578                                 ack = RXRPC_ACK_DELAY;
 579                                 ack_serial = serial;
 580                         }
 581                         trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
 582                 } else {
 583                         trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
 584                 }
 585
 586                 if (after_eq(seq, call->rx_expect_next)) {
 587                         if (after(seq, call->rx_expect_next)) {
 588                                 _net("OOS %u > %u", seq, call->rx_expect_next);
 589                                 ack = RXRPC_ACK_OUT_OF_SEQUENCE;
 590                                 ack_serial = serial;
 591                         }
 592                         call->rx_expect_next = seq + 1;
 593                 }
 594                 if (!ack)
 595                         ack_serial = serial;
 596         }
 597
 598 ack:
 599         if (atomic_add_return(nr_unacked, &call->ackr_nr_unacked) > 2 && !ack)
 600                 ack = RXRPC_ACK_IDLE;
 601
 602         if (ack)
 603                 rxrpc_propose_ACK(call, ack, ack_serial,
 604                                   immediate_ack, true,
 605                                   rxrpc_propose_ack_input_data);
 606         else
 607                 rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial,
 608                                   false, true,
 609                                   rxrpc_propose_ack_input_data);
 610
 611         trace_rxrpc_notify_socket(call->debug_id, serial);
 612         rxrpc_notify_socket(call);
 613
 614 unlock:
 615         spin_unlock(&call->input_lock);
 616         rxrpc_free_skb(skb, rxrpc_skb_freed);
 617         _leave(" [queued]");
 618 }
 619
 620 /*
 621  * Process a requested ACK.
 622  */
 623 static void rxrpc_input_requested_ack(struct rxrpc_call *call,
 624                                       ktime_t resp_time,
 625                                       rxrpc_serial_t orig_serial,
 626                                       rxrpc_serial_t ack_serial)
 627 {
 628         struct rxrpc_skb_priv *sp;
 629         struct sk_buff *skb;
 630         ktime_t sent_at;
 631         int ix;
 632
 633         for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
 634                 skb = call->rxtx_buffer[ix];
 635                 if (!skb)
 636                         continue;
 637
 638                 sent_at = skb->tstamp;
 639                 smp_rmb(); /* Read timestamp before serial. */
 640                 sp = rxrpc_skb(skb);
 641                 if (sp->hdr.serial != orig_serial)
 642                         continue;
 643                 goto found;
 644         }
 645
 646         return;
 647
 648 found:
 649         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
 650                            orig_serial, ack_serial, sent_at, resp_time);
 651 }
 652
 653 /*
 654  * Process the response to a ping that we sent to find out if we lost an ACK.
 655  *
 656  * If we got back a ping response that indicates a lower tx_top than what we
 657  * had at the time of the ping transmission, we adjudge all the DATA packets
 658  * sent between the response tx_top and the ping-time tx_top to have been lost.
 659  */
 660 static void rxrpc_input_check_for_lost_ack(struct rxrpc_call *call)
 661 {
 662         rxrpc_seq_t top, bottom, seq;
 663         bool resend = false;
 664
 665         spin_lock_bh(&call->lock);
 666
 667         bottom = call->tx_hard_ack + 1;
 668         top = call->acks_lost_top;
 669         if (before(bottom, top)) {
 670                 for (seq = bottom; before_eq(seq, top); seq++) {
 671                         int ix = seq & RXRPC_RXTX_BUFF_MASK;
 672                         u8 annotation = call->rxtx_annotations[ix];
 673                         u8 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 674
 675                         if (anno_type != RXRPC_TX_ANNO_UNACK)
 676                                 continue;
 677                         annotation &= ~RXRPC_TX_ANNO_MASK;
 678                         annotation |= RXRPC_TX_ANNO_RETRANS;
 679                         call->rxtx_annotations[ix] = annotation;
 680                         resend = true;
 681                 }
 682         }
 683
 684         spin_unlock_bh(&call->lock);
 685
 686         if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 687                 rxrpc_queue_call(call);
 688 }
 689
 690 /*
 691  * Process a ping response.
 692  */
 693 static void rxrpc_input_ping_response(struct rxrpc_call *call,
 694                                       ktime_t resp_time,
 695                                       rxrpc_serial_t orig_serial,
 696                                       rxrpc_serial_t ack_serial)
 697 {
 698         rxrpc_serial_t ping_serial;
 699         ktime_t ping_time;
 700
 701         ping_time = call->ping_time;
 702         smp_rmb();
 703         ping_serial = READ_ONCE(call->ping_serial);
 704
 705         if (orig_serial == call->acks_lost_ping)
 706                 rxrpc_input_check_for_lost_ack(call);
 707
 708         if (before(orig_serial, ping_serial) ||
 709             !test_and_clear_bit(RXRPC_CALL_PINGING, &call->flags))
 710                 return;
 711         if (after(orig_serial, ping_serial))
 712                 return;
 713
 714         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
 715                            orig_serial, ack_serial, ping_time, resp_time);
 716 }
 717
 718 /*
 719  * Process the extra information that may be appended to an ACK packet
 720  */
 721 static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 722                                 struct rxrpc_ackinfo *ackinfo)
 723 {
 724         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 725         struct rxrpc_peer *peer;
 726         unsigned int mtu;
 727         bool wake = false;
 728         u32 rwind = ntohl(ackinfo->rwind);
 729
 730         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 731                sp->hdr.serial,
 732                ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
 733                rwind, ntohl(ackinfo->jumbo_max));
 734
 735         if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
 736                 rwind = RXRPC_RXTX_BUFF_SIZE - 1;
 737         if (call->tx_winsize != rwind) {
 738                 if (rwind > call->tx_winsize)
 739                         wake = true;
 740                 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake);
 741                 call->tx_winsize = rwind;
 742         }
 743
 744         if (call->cong_ssthresh > rwind)
 745                 call->cong_ssthresh = rwind;
 746
 747         mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
 748
 749         peer = call->peer;
 750         if (mtu < peer->maxdata) {
 751                 spin_lock_bh(&peer->lock);
 752                 peer->maxdata = mtu;
 753                 peer->mtu = mtu + peer->hdrsize;
 754                 spin_unlock_bh(&peer->lock);
 755                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 756         }
 757
 758         if (wake)
 759                 wake_up(&call->waitq);
 760 }
 761
 762 /*
 763  * Process individual soft ACKs.
 764  *
 765  * Each ACK in the array corresponds to one packet and can be either an ACK or
 766  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 767  * packets that lie beyond the end of the ACK list are scheduled for resend by
 768  * the timer on the basis that the peer might just not have processed them at
 769  * the time the ACK was sent.
 770  */
 771 static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 772                                   rxrpc_seq_t seq, int nr_acks,
 773                                   struct rxrpc_ack_summary *summary)
 774 {
 775         int ix;
 776         u8 annotation, anno_type;
 777
 778         for (; nr_acks > 0; nr_acks--, seq++) {
 779                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 780                 annotation = call->rxtx_annotations[ix];
 781                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 782                 annotation &= ~RXRPC_TX_ANNO_MASK;
 783                 switch (*acks++) {
 784                 case RXRPC_ACK_TYPE_ACK:
 785                         summary->nr_acks++;
 786                         if (anno_type == RXRPC_TX_ANNO_ACK)
 787                                 continue;
 788                         summary->nr_new_acks++;
 789                         call->rxtx_annotations[ix] =
 790                                 RXRPC_TX_ANNO_ACK | annotation;
 791                         break;
 792                 case RXRPC_ACK_TYPE_NACK:
 793                         if (!summary->nr_nacks &&
 794                             call->acks_lowest_nak != seq) {
 795                                 call->acks_lowest_nak = seq;
 796                                 summary->new_low_nack = true;
 797                         }
 798                         summary->nr_nacks++;
 799                         if (anno_type == RXRPC_TX_ANNO_NAK)
 800                                 continue;
 801                         summary->nr_new_nacks++;
 802                         if (anno_type == RXRPC_TX_ANNO_RETRANS)
 803                                 continue;
 804                         call->rxtx_annotations[ix] =
 805                                 RXRPC_TX_ANNO_NAK | annotation;
 806                         break;
 807                 default:
 808                         return rxrpc_proto_abort("SFT", call, 0);
 809                 }
 810         }
 811 }
 812
 813 /*
 814  * Return true if the ACK is valid - ie. it doesn't appear to have regressed
 815  * with respect to the ack state conveyed by preceding ACKs.
 816  */
 817 static bool rxrpc_is_ack_valid(struct rxrpc_call *call,
 818                                rxrpc_seq_t first_pkt, rxrpc_seq_t prev_pkt)
 819 {
 820         rxrpc_seq_t base = READ_ONCE(call->acks_first_seq);
 821
 822         if (after(first_pkt, base))
 823                 return true; /* The window advanced */
 824
 825         if (before(first_pkt, base))
 826                 return false; /* firstPacket regressed */
 827
 828         if (after_eq(prev_pkt, call->acks_prev_seq))
 829                 return true; /* previousPacket hasn't regressed. */
 830
 831         /* Some rx implementations put a serial number in previousPacket. */
 832         if (after_eq(prev_pkt, base + call->tx_winsize))
 833                 return false;
 834         return true;
 835 }
 836
 837 /*
 838  * Process an ACK packet.
 839  *
 840  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 841  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 842  *
 843  * A hard-ACK means that a packet has been processed and may be discarded; a
 844  * soft-ACK means that the packet may be discarded and retransmission
 845  * requested.  A phase is complete when all packets are hard-ACK'd.
 846  */
 847 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 848 {
 849         struct rxrpc_ack_summary summary = { 0 };
 850         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 851         union {
 852                 struct rxrpc_ackpacket ack;
 853                 struct rxrpc_ackinfo info;
 854                 u8 acks[RXRPC_MAXACKS];
 855         } buf;
 856         rxrpc_serial_t ack_serial, acked_serial;
 857         rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
 858         int nr_acks, offset, ioffset;
 859
 860         _enter("");
 861
 862         offset = sizeof(struct rxrpc_wire_header);
 863         if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
 864                 _debug("extraction failure");
 865                 return rxrpc_proto_abort("XAK", call, 0);
 866         }
 867         offset += sizeof(buf.ack);
 868
 869         ack_serial = sp->hdr.serial;
 870         acked_serial = ntohl(buf.ack.serial);
 871         first_soft_ack = ntohl(buf.ack.firstPacket);
 872         prev_pkt = ntohl(buf.ack.previousPacket);
 873         hard_ack = first_soft_ack - 1;
 874         nr_acks = buf.ack.nAcks;
 875         summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
 876                               buf.ack.reason : RXRPC_ACK__INVALID);
 877
 878         trace_rxrpc_rx_ack(call, ack_serial, acked_serial,
 879                            first_soft_ack, prev_pkt,
 880                            summary.ack_reason, nr_acks);
 881
 882         if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
 883                 rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
 884                                           ack_serial);
 885         if (buf.ack.reason == RXRPC_ACK_REQUESTED)
 886                 rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
 887                                           ack_serial);
 888
 889         if (buf.ack.reason == RXRPC_ACK_PING) {
 890                 _proto("Rx ACK %%%u PING Request", ack_serial);
 891                 rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 892                                   ack_serial, true, true,
 893                                   rxrpc_propose_ack_respond_to_ping);
 894         } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 895                 rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 896                                   ack_serial, true, true,
 897                                   rxrpc_propose_ack_respond_to_ack);
 898         }
 899
 900         /* Discard any out-of-order or duplicate ACKs (outside lock). */
 901         if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
 902                 trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
 903                                            first_soft_ack, call->acks_first_seq,
 904                                            prev_pkt, call->acks_prev_seq);
 905                 return;
 906         }
 907
 908         buf.info.rxMTU = 0;
 909         ioffset = offset + nr_acks + 3;
 910         if (skb->len >= ioffset + sizeof(buf.info) &&
 911             skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
 912                 return rxrpc_proto_abort("XAI", call, 0);
 913
 914         spin_lock(&call->input_lock);
 915
 916         /* Discard any out-of-order or duplicate ACKs (inside lock). */
 917         if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
 918                 trace_rxrpc_rx_discard_ack(call->debug_id, ack_serial,
 919                                            first_soft_ack, call->acks_first_seq,
 920                                            prev_pkt, call->acks_prev_seq);
 921                 goto out;
 922         }
 923         call->acks_latest_ts = skb->tstamp;
 924
 925         call->acks_first_seq = first_soft_ack;
 926         call->acks_prev_seq = prev_pkt;
 927
 928         /* Parse rwind and mtu sizes if provided. */
 929         if (buf.info.rxMTU)
 930                 rxrpc_input_ackinfo(call, skb, &buf.info);
 931
 932         if (first_soft_ack == 0) {
 933                 rxrpc_proto_abort("AK0", call, 0);
 934                 goto out;
 935         }
 936
 937         /* Ignore ACKs unless we are or have just been transmitting. */
 938         switch (READ_ONCE(call->state)) {
 939         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 940         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 941         case RXRPC_CALL_SERVER_SEND_REPLY:
 942         case RXRPC_CALL_SERVER_AWAIT_ACK:
 943                 break;
 944         default:
 945                 goto out;
 946         }
 947
 948         if (before(hard_ack, call->tx_hard_ack) ||
 949             after(hard_ack, call->tx_top)) {
 950                 rxrpc_proto_abort("AKW", call, 0);
 951                 goto out;
 952         }
 953         if (nr_acks > call->tx_top - hard_ack) {
 954                 rxrpc_proto_abort("AKN", call, 0);
 955                 goto out;
 956         }
 957
 958         if (after(hard_ack, call->tx_hard_ack)) {
 959                 if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
 960                         rxrpc_end_tx_phase(call, false, "ETA");
 961                         goto out;
 962                 }
 963         }
 964
 965         if (nr_acks > 0) {
 966                 if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0) {
 967                         rxrpc_proto_abort("XSA", call, 0);
 968                         goto out;
 969                 }
 970                 rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
 971                                       &summary);
 972         }
 973
 974         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 975             RXRPC_TX_ANNO_LAST &&
 976             summary.nr_acks == call->tx_top - hard_ack &&
 977             rxrpc_is_client_call(call))
 978                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, ack_serial,
 979                                   false, true,
 980                                   rxrpc_propose_ack_ping_for_lost_reply);
 981
 982         rxrpc_congestion_management(call, skb, &summary, acked_serial);
 983 out:
 984         spin_unlock(&call->input_lock);
 985 }
 986
 987 /*
 988  * Process an ACKALL packet.
 989  */
 990 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
 991 {
 992         struct rxrpc_ack_summary summary = { 0 };
 993         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 994
 995         _proto("Rx ACKALL %%%u", sp->hdr.serial);
 996
 997         spin_lock(&call->input_lock);
 998
 999         if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
1000                 rxrpc_end_tx_phase(call, false, "ETL");
1001
1002         spin_unlock(&call->input_lock);
1003 }
1004
1005 /*
1006  * Process an ABORT packet directed at a call.
1007  */
1008 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
1009 {
1010         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1011         __be32 wtmp;
1012         u32 abort_code = RX_CALL_DEAD;
1013
1014         _enter("");
1015
1016         if (skb->len >= 4 &&
1017             skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1018                           &wtmp, sizeof(wtmp)) >= 0)
1019                 abort_code = ntohl(wtmp);
1020
1021         trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
1022
1023         _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
1024
1025         if (rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
1026                                       abort_code, -ECONNABORTED))
1027                 rxrpc_notify_socket(call);
1028 }
1029
1030 /*
1031  * Process an incoming call packet.
1032  */
1033 static void rxrpc_input_call_packet(struct rxrpc_call *call,
1034                                     struct sk_buff *skb)
1035 {
1036         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1037         unsigned long timo;
1038
1039         _enter("%p,%p", call, skb);
1040
1041         timo = READ_ONCE(call->next_rx_timo);
1042         if (timo) {
1043                 unsigned long now = jiffies, expect_rx_by;
1044
1045                 expect_rx_by = now + timo;
1046                 WRITE_ONCE(call->expect_rx_by, expect_rx_by);
1047                 rxrpc_reduce_call_timer(call, expect_rx_by, now,
1048                                         rxrpc_timer_set_for_normal);
1049         }
1050
1051         switch (sp->hdr.type) {
1052         case RXRPC_PACKET_TYPE_DATA:
1053                 rxrpc_input_data(call, skb);
1054                 goto no_free;
1055
1056         case RXRPC_PACKET_TYPE_ACK:
1057                 rxrpc_input_ack(call, skb);
1058                 break;
1059
1060         case RXRPC_PACKET_TYPE_BUSY:
1061                 _proto("Rx BUSY %%%u", sp->hdr.serial);
1062
1063                 /* Just ignore BUSY packets from the server; the retry and
1064                  * lifespan timers will take care of business.  BUSY packets
1065                  * from the client don't make sense.
1066                  */
1067                 break;
1068
1069         case RXRPC_PACKET_TYPE_ABORT:
1070                 rxrpc_input_abort(call, skb);
1071                 break;
1072
1073         case RXRPC_PACKET_TYPE_ACKALL:
1074                 rxrpc_input_ackall(call, skb);
1075                 break;
1076
1077         default:
1078                 break;
1079         }
1080
1081         rxrpc_free_skb(skb, rxrpc_skb_freed);
1082 no_free:
1083         _leave("");
1084 }
1085
1086 /*
1087  * Handle a new service call on a channel implicitly completing the preceding
1088  * call on that channel.  This does not apply to client conns.
1089  *
1090  * TODO: If callNumber > call_id + 1, renegotiate security.
1091  */
1092 static void rxrpc_input_implicit_end_call(struct rxrpc_sock *rx,
1093                                           struct rxrpc_connection *conn,
1094                                           struct rxrpc_call *call)
1095 {
1096         switch (READ_ONCE(call->state)) {
1097         case RXRPC_CALL_SERVER_AWAIT_ACK:
1098                 rxrpc_call_completed(call);
1099                 /* Fall through */
1100         case RXRPC_CALL_COMPLETE:
1101                 break;
1102         default:
1103                 if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
1104                         set_bit(RXRPC_CALL_EV_ABORT, &call->events);
1105                         rxrpc_queue_call(call);
1106                 }
1107                 trace_rxrpc_improper_term(call);
1108                 break;
1109         }
1110
1111         spin_lock(&rx->incoming_lock);
1112         __rxrpc_disconnect_call(conn, call);
1113         spin_unlock(&rx->incoming_lock);
1114         rxrpc_notify_socket(call);
1115 }
1116
1117 /*
1118  * post connection-level events to the connection
1119  * - this includes challenges, responses, some aborts and call terminal packet
1120  *   retransmission.
1121  */
1122 static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
1123                                       struct sk_buff *skb)
1124 {
1125         _enter("%p,%p", conn, skb);
1126
1127         skb_queue_tail(&conn->rx_queue, skb);
1128         rxrpc_queue_conn(conn);
1129 }
1130
1131 /*
1132  * post endpoint-level events to the local endpoint
1133  * - this includes debug and version messages
1134  */
1135 static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
1136                                        struct sk_buff *skb)
1137 {
1138         _enter("%p,%p", local, skb);
1139
1140         if (rxrpc_get_local_maybe(local)) {
1141                 skb_queue_tail(&local->event_queue, skb);
1142                 rxrpc_queue_local(local);
1143         } else {
1144                 rxrpc_free_skb(skb, rxrpc_skb_freed);
1145         }
1146 }
1147
1148 /*
1149  * put a packet up for transport-level abort
1150  */
1151 static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
1152 {
1153         CHECK_SLAB_OKAY(&local->usage);
1154
1155         if (rxrpc_get_local_maybe(local)) {
1156                 skb_queue_tail(&local->reject_queue, skb);
1157                 rxrpc_queue_local(local);
1158         } else {
1159                 rxrpc_free_skb(skb, rxrpc_skb_freed);
1160         }
1161 }
1162
1163 /*
1164  * Extract the wire header from a packet and translate the byte order.
1165  */
1166 static noinline
1167 int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
1168 {
1169         struct rxrpc_wire_header whdr;
1170
1171         /* dig out the RxRPC connection details */
1172         if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0) {
1173                 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
1174                                       tracepoint_string("bad_hdr"));
1175                 return -EBADMSG;
1176         }
1177
1178         memset(sp, 0, sizeof(*sp));
1179         sp->hdr.epoch           = ntohl(whdr.epoch);
1180         sp->hdr.cid             = ntohl(whdr.cid);
1181         sp->hdr.callNumber      = ntohl(whdr.callNumber);
1182         sp->hdr.seq             = ntohl(whdr.seq);
1183         sp->hdr.serial          = ntohl(whdr.serial);
1184         sp->hdr.flags           = whdr.flags;
1185         sp->hdr.type            = whdr.type;
1186         sp->hdr.userStatus      = whdr.userStatus;
1187         sp->hdr.securityIndex   = whdr.securityIndex;
1188         sp->hdr._rsvd           = ntohs(whdr._rsvd);
1189         sp->hdr.serviceId       = ntohs(whdr.serviceId);
1190         return 0;
1191 }
1192
1193 /*
1194  * handle data received on the local endpoint
1195  * - may be called in interrupt context
1196  *
1197  * [!] Note that as this is called from the encap_rcv hook, the socket is not
1198  * held locked by the caller and nothing prevents sk_user_data on the UDP from
1199  * being cleared in the middle of processing this function.
1200  *
1201  * Called with the RCU read lock held from the IP layer via UDP.
1202  */
1203 int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
1204 {
1205         struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
1206         struct rxrpc_connection *conn;
1207         struct rxrpc_channel *chan;
1208         struct rxrpc_call *call = NULL;
1209         struct rxrpc_skb_priv *sp;
1210         struct rxrpc_peer *peer = NULL;
1211         struct rxrpc_sock *rx = NULL;
1212         unsigned int channel;
1213
1214         _enter("%p", udp_sk);
1215
1216         if (unlikely(!local)) {
1217                 kfree_skb(skb);
1218                 return 0;
1219         }
1220         if (skb->tstamp == 0)
1221                 skb->tstamp = ktime_get_real();
1222
1223         rxrpc_new_skb(skb, rxrpc_skb_received);
1224
1225         skb_pull(skb, sizeof(struct udphdr));
1226
1227         /* The UDP protocol already released all skb resources;
1228          * we are free to add our own data there.
1229          */
1230         sp = rxrpc_skb(skb);
1231
1232         /* dig out the RxRPC connection details */
1233         if (rxrpc_extract_header(sp, skb) < 0)
1234                 goto bad_message;
1235
1236         if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
1237                 static int lose;
1238                 if ((lose++ & 7) == 7) {
1239                         trace_rxrpc_rx_lose(sp);
1240                         rxrpc_free_skb(skb, rxrpc_skb_lost);
1241                         return 0;
1242                 }
1243         }
1244
1245         if (skb->tstamp == 0)
1246                 skb->tstamp = ktime_get_real();
1247         trace_rxrpc_rx_packet(sp);
1248
1249         switch (sp->hdr.type) {
1250         case RXRPC_PACKET_TYPE_VERSION:
1251                 if (rxrpc_to_client(sp))
1252                         goto discard;
1253                 rxrpc_post_packet_to_local(local, skb);
1254                 goto out;
1255
1256         case RXRPC_PACKET_TYPE_BUSY:
1257                 if (rxrpc_to_server(sp))
1258                         goto discard;
1259                 /* Fall through */
1260         case RXRPC_PACKET_TYPE_ACK:
1261         case RXRPC_PACKET_TYPE_ACKALL:
1262                 if (sp->hdr.callNumber == 0)
1263                         goto bad_message;
1264                 /* Fall through */
1265         case RXRPC_PACKET_TYPE_ABORT:
1266                 break;
1267
1268         case RXRPC_PACKET_TYPE_DATA:
1269                 if (sp->hdr.callNumber == 0 ||
1270                     sp->hdr.seq == 0)
1271                         goto bad_message;
1272                 if (!rxrpc_validate_data(skb))
1273                         goto bad_message;
1274
1275                 /* Unshare the packet so that it can be modified for in-place
1276                  * decryption.
1277                  */
1278                 if (sp->hdr.securityIndex != 0) {
1279                         struct sk_buff *nskb = skb_unshare(skb, GFP_ATOMIC);
1280                         if (!nskb) {
1281                                 rxrpc_eaten_skb(skb, rxrpc_skb_unshared_nomem);
1282                                 goto out;
1283                         }
1284
1285                         if (nskb != skb) {
1286                                 rxrpc_eaten_skb(skb, rxrpc_skb_received);
1287                                 skb = nskb;
1288                                 rxrpc_new_skb(skb, rxrpc_skb_unshared);
1289                                 sp = rxrpc_skb(skb);
1290                         }
1291                 }
1292                 break;
1293
1294         case RXRPC_PACKET_TYPE_CHALLENGE:
1295                 if (rxrpc_to_server(sp))
1296                         goto discard;
1297                 break;
1298         case RXRPC_PACKET_TYPE_RESPONSE:
1299                 if (rxrpc_to_client(sp))
1300                         goto discard;
1301                 break;
1302
1303                 /* Packet types 9-11 should just be ignored. */
1304         case RXRPC_PACKET_TYPE_PARAMS:
1305         case RXRPC_PACKET_TYPE_10:
1306         case RXRPC_PACKET_TYPE_11:
1307                 goto discard;
1308
1309         default:
1310                 _proto("Rx Bad Packet Type %u", sp->hdr.type);
1311                 goto bad_message;
1312         }
1313
1314         if (sp->hdr.serviceId == 0)
1315                 goto bad_message;
1316
1317         if (rxrpc_to_server(sp)) {
1318                 /* Weed out packets to services we're not offering.  Packets
1319                  * that would begin a call are explicitly rejected and the rest
1320                  * are just discarded.
1321                  */
1322                 rx = rcu_dereference(local->service);
1323                 if (!rx || (sp->hdr.serviceId != rx->srx.srx_service &&
1324                             sp->hdr.serviceId != rx->second_service)) {
1325                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
1326                             sp->hdr.seq == 1)
1327                                 goto unsupported_service;
1328                         goto discard;
1329                 }
1330         }
1331
1332         conn = rxrpc_find_connection_rcu(local, skb, &peer);
1333         if (conn) {
1334                 if (sp->hdr.securityIndex != conn->security_ix)
1335                         goto wrong_security;
1336
1337                 if (sp->hdr.serviceId != conn->service_id) {
1338                         int old_id;
1339
1340                         if (!test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags))
1341                                 goto reupgrade;
1342                         old_id = cmpxchg(&conn->service_id, conn->params.service_id,
1343                                          sp->hdr.serviceId);
1344
1345                         if (old_id != conn->params.service_id &&
1346                             old_id != sp->hdr.serviceId)
1347                                 goto reupgrade;
1348                 }
1349
1350                 if (sp->hdr.callNumber == 0) {
1351                         /* Connection-level packet */
1352                         _debug("CONN %p {%d}", conn, conn->debug_id);
1353                         rxrpc_post_packet_to_conn(conn, skb);
1354                         goto out;
1355                 }
1356
1357                 if ((int)sp->hdr.serial - (int)conn->hi_serial > 0)
1358                         conn->hi_serial = sp->hdr.serial;
1359
1360                 /* Call-bound packets are routed by connection channel. */
1361                 channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1362                 chan = &conn->channels[channel];
1363
1364                 /* Ignore really old calls */
1365                 if (sp->hdr.callNumber < chan->last_call)
1366                         goto discard;
1367
1368                 if (sp->hdr.callNumber == chan->last_call) {
1369                         if (chan->call ||
1370                             sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
1371                                 goto discard;
1372
1373                         /* For the previous service call, if completed
1374                          * successfully, we discard all further packets.
1375                          */
1376                         if (rxrpc_conn_is_service(conn) &&
1377                             chan->last_type == RXRPC_PACKET_TYPE_ACK)
1378                                 goto discard;
1379
1380                         /* But otherwise we need to retransmit the final packet
1381                          * from data cached in the connection record.
1382                          */
1383                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
1384                                 trace_rxrpc_rx_data(chan->call_debug_id,
1385                                                     sp->hdr.seq,
1386                                                     sp->hdr.serial,
1387                                                     sp->hdr.flags, 0);
1388                         rxrpc_post_packet_to_conn(conn, skb);
1389                         goto out;
1390                 }
1391
1392                 call = rcu_dereference(chan->call);
1393
1394                 if (sp->hdr.callNumber > chan->call_id) {
1395                         if (rxrpc_to_client(sp))
1396                                 goto reject_packet;
1397                         if (call)
1398                                 rxrpc_input_implicit_end_call(rx, conn, call);
1399                         call = NULL;
1400                 }
1401
1402                 if (call) {
1403                         if (sp->hdr.serviceId != call->service_id)
1404                                 call->service_id = sp->hdr.serviceId;
1405                         if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
1406                                 call->rx_serial = sp->hdr.serial;
1407                         if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
1408                                 set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
1409                 }
1410         }
1411
1412         if (!call || atomic_read(&call->usage) == 0) {
1413                 if (rxrpc_to_client(sp) ||
1414                     sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1415                         goto bad_message;
1416                 if (sp->hdr.seq != 1)
1417                         goto discard;
1418                 call = rxrpc_new_incoming_call(local, rx, skb);
1419                 if (!call)
1420                         goto reject_packet;
1421         }
1422
1423         /* Process a call packet; this either discards or passes on the ref
1424          * elsewhere.
1425          */
1426         rxrpc_input_call_packet(call, skb);
1427         goto out;
1428
1429 discard:
1430         rxrpc_free_skb(skb, rxrpc_skb_freed);
1431 out:
1432         trace_rxrpc_rx_done(0, 0);
1433         return 0;
1434
1435 wrong_security:
1436         trace_rxrpc_abort(0, "SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1437                           RXKADINCONSISTENCY, EBADMSG);
1438         skb->priority = RXKADINCONSISTENCY;
1439         goto post_abort;
1440
1441 unsupported_service:
1442         trace_rxrpc_abort(0, "INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1443                           RX_INVALID_OPERATION, EOPNOTSUPP);
1444         skb->priority = RX_INVALID_OPERATION;
1445         goto post_abort;
1446
1447 reupgrade:
1448         trace_rxrpc_abort(0, "UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1449                           RX_PROTOCOL_ERROR, EBADMSG);
1450         goto protocol_error;
1451
1452 bad_message:
1453         trace_rxrpc_abort(0, "BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1454                           RX_PROTOCOL_ERROR, EBADMSG);
1455 protocol_error:
1456         skb->priority = RX_PROTOCOL_ERROR;
1457 post_abort:
1458         skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
1459 reject_packet:
1460         trace_rxrpc_rx_done(skb->mark, skb->priority);
1461         rxrpc_reject_packet(local, skb);
1462         _leave(" [badmsg]");
1463         return 0;
1464 }