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                 state = call->state;
 279                 break;
 280
 281         default:
 282                 goto bad_state;
 283         }
 284
 285         write_unlock(&call->state_lock);
 286         if (state == RXRPC_CALL_CLIENT_AWAIT_REPLY)
 287                 trace_rxrpc_transmit(call, rxrpc_transmit_await_reply);
 288         else
 289                 trace_rxrpc_transmit(call, rxrpc_transmit_end);
 290         _leave(" = ok");
 291         return true;
 292
 293 bad_state:
 294         write_unlock(&call->state_lock);
 295         kdebug("end_tx %s", rxrpc_call_states[call->state]);
 296         rxrpc_proto_abort(abort_why, call, call->tx_top);
 297         return false;
 298 }
 299
 300 /*
 301  * Begin the reply reception phase of a call.
 302  */
 303 static bool rxrpc_receiving_reply(struct rxrpc_call *call)
 304 {
 305         struct rxrpc_ack_summary summary = { 0 };
 306         unsigned long now, timo;
 307         rxrpc_seq_t top = READ_ONCE(call->tx_top);
 308
 309         if (call->ackr_reason) {
 310                 spin_lock_bh(&call->lock);
 311                 call->ackr_reason = 0;
 312                 spin_unlock_bh(&call->lock);
 313                 now = jiffies;
 314                 timo = now + MAX_JIFFY_OFFSET;
 315                 WRITE_ONCE(call->resend_at, timo);
 316                 WRITE_ONCE(call->ack_at, timo);
 317                 trace_rxrpc_timer(call, rxrpc_timer_init_for_reply, now);
 318         }
 319
 320         if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
 321                 if (!rxrpc_rotate_tx_window(call, top, &summary)) {
 322                         rxrpc_proto_abort("TXL", call, top);
 323                         return false;
 324                 }
 325         }
 326         if (!rxrpc_end_tx_phase(call, true, "ETD"))
 327                 return false;
 328         call->tx_phase = false;
 329         return true;
 330 }
 331
 332 /*
 333  * Scan a data packet to validate its structure and to work out how many
 334  * subpackets it contains.
 335  *
 336  * A jumbo packet is a collection of consecutive packets glued together with
 337  * little headers between that indicate how to change the initial header for
 338  * each subpacket.
 339  *
 340  * RXRPC_JUMBO_PACKET must be set on all but the last subpacket - and all but
 341  * the last are RXRPC_JUMBO_DATALEN in size.  The last subpacket may be of any
 342  * size.
 343  */
 344 static bool rxrpc_validate_data(struct sk_buff *skb)
 345 {
 346         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 347         unsigned int offset = sizeof(struct rxrpc_wire_header);
 348         unsigned int len = skb->len;
 349         u8 flags = sp->hdr.flags;
 350
 351         for (;;) {
 352                 if (flags & RXRPC_REQUEST_ACK)
 353                         __set_bit(sp->nr_subpackets, sp->rx_req_ack);
 354                 sp->nr_subpackets++;
 355
 356                 if (!(flags & RXRPC_JUMBO_PACKET))
 357                         break;
 358
 359                 if (len - offset < RXRPC_JUMBO_SUBPKTLEN)
 360                         goto protocol_error;
 361                 if (flags & RXRPC_LAST_PACKET)
 362                         goto protocol_error;
 363                 offset += RXRPC_JUMBO_DATALEN;
 364                 if (skb_copy_bits(skb, offset, &flags, 1) < 0)
 365                         goto protocol_error;
 366                 offset += sizeof(struct rxrpc_jumbo_header);
 367         }
 368
 369         if (flags & RXRPC_LAST_PACKET)
 370                 sp->rx_flags |= RXRPC_SKB_INCL_LAST;
 371         return true;
 372
 373 protocol_error:
 374         return false;
 375 }
 376
 377 /*
 378  * Handle reception of a duplicate packet.
 379  *
 380  * We have to take care to avoid an attack here whereby we're given a series of
 381  * jumbograms, each with a sequence number one before the preceding one and
 382  * filled up to maximum UDP size.  If they never send us the first packet in
 383  * the sequence, they can cause us to have to hold on to around 2MiB of kernel
 384  * space until the call times out.
 385  *
 386  * We limit the space usage by only accepting three duplicate jumbo packets per
 387  * call.  After that, we tell the other side we're no longer accepting jumbos
 388  * (that information is encoded in the ACK packet).
 389  */
 390 static void rxrpc_input_dup_data(struct rxrpc_call *call, rxrpc_seq_t seq,
 391                                  bool is_jumbo, bool *_jumbo_bad)
 392 {
 393         /* Discard normal packets that are duplicates. */
 394         if (is_jumbo)
 395                 return;
 396
 397         /* Skip jumbo subpackets that are duplicates.  When we've had three or
 398          * more partially duplicate jumbo packets, we refuse to take any more
 399          * jumbos for this call.
 400          */
 401         if (!*_jumbo_bad) {
 402                 call->nr_jumbo_bad++;
 403                 *_jumbo_bad = true;
 404         }
 405 }
 406
 407 /*
 408  * Process a DATA packet, adding the packet to the Rx ring.  The caller's
 409  * packet ref must be passed on or discarded.
 410  */
 411 static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
 412 {
 413         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 414         enum rxrpc_call_state state;
 415         unsigned int j, nr_subpackets;
 416         rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
 417         rxrpc_seq_t seq0 = sp->hdr.seq, hard_ack;
 418         bool immediate_ack = false, jumbo_bad = false;
 419         u8 ack = 0;
 420
 421         _enter("{%u,%u},{%u,%u}",
 422                call->rx_hard_ack, call->rx_top, skb->len, seq0);
 423
 424         _proto("Rx DATA %%%u { #%u f=%02x n=%u }",
 425                sp->hdr.serial, seq0, sp->hdr.flags, sp->nr_subpackets);
 426
 427         state = READ_ONCE(call->state);
 428         if (state >= RXRPC_CALL_COMPLETE) {
 429                 rxrpc_free_skb(skb, rxrpc_skb_freed);
 430                 return;
 431         }
 432
 433         if (call->state == RXRPC_CALL_SERVER_RECV_REQUEST) {
 434                 unsigned long timo = READ_ONCE(call->next_req_timo);
 435                 unsigned long now, expect_req_by;
 436
 437                 if (timo) {
 438                         now = jiffies;
 439                         expect_req_by = now + timo;
 440                         WRITE_ONCE(call->expect_req_by, expect_req_by);
 441                         rxrpc_reduce_call_timer(call, expect_req_by, now,
 442                                                 rxrpc_timer_set_for_idle);
 443                 }
 444         }
 445
 446         spin_lock(&call->input_lock);
 447
 448         /* Received data implicitly ACKs all of the request packets we sent
 449          * when we're acting as a client.
 450          */
 451         if ((state == RXRPC_CALL_CLIENT_SEND_REQUEST ||
 452              state == RXRPC_CALL_CLIENT_AWAIT_REPLY) &&
 453             !rxrpc_receiving_reply(call))
 454                 goto unlock;
 455
 456         call->ackr_prev_seq = seq0;
 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                 /* Queue the packet.  We use a couple of memory barriers here as need
 538                  * to make sure that rx_top is perceived to be set after the buffer
 539                  * pointer and that the buffer pointer is set after the annotation and
 540                  * the skb data.
 541                  *
 542                  * Barriers against rxrpc_recvmsg_data() and rxrpc_rotate_rx_window()
 543                  * and also rxrpc_fill_out_ack().
 544                  */
 545                 if (!terminal)
 546                         rxrpc_get_skb(skb, rxrpc_skb_got);
 547                 call->rxtx_annotations[ix] = annotation;
 548                 smp_wmb();
 549                 call->rxtx_buffer[ix] = skb;
 550                 if (after(seq, call->rx_top)) {
 551                         smp_store_release(&call->rx_top, seq);
 552                 } else if (before(seq, call->rx_top)) {
 553                         /* Send an immediate ACK if we fill in a hole */
 554                         if (!ack) {
 555                                 ack = RXRPC_ACK_DELAY;
 556                                 ack_serial = serial;
 557                         }
 558                         immediate_ack = true;
 559                 }
 560
 561                 if (terminal) {
 562                         /* From this point on, we're not allowed to touch the
 563                          * packet any longer as its ref now belongs to the Rx
 564                          * ring.
 565                          */
 566                         skb = NULL;
 567                         sp = NULL;
 568                 }
 569
 570                 if (last) {
 571                         set_bit(RXRPC_CALL_RX_LAST, &call->flags);
 572                         if (!ack) {
 573                                 ack = RXRPC_ACK_DELAY;
 574                                 ack_serial = serial;
 575                         }
 576                         trace_rxrpc_receive(call, rxrpc_receive_queue_last, serial, seq);
 577                 } else {
 578                         trace_rxrpc_receive(call, rxrpc_receive_queue, serial, seq);
 579                 }
 580
 581                 if (after_eq(seq, call->rx_expect_next)) {
 582                         if (after(seq, call->rx_expect_next)) {
 583                                 _net("OOS %u > %u", seq, call->rx_expect_next);
 584                                 ack = RXRPC_ACK_OUT_OF_SEQUENCE;
 585                                 ack_serial = serial;
 586                         }
 587                         call->rx_expect_next = seq + 1;
 588                 }
 589         }
 590
 591 ack:
 592         if (ack)
 593                 rxrpc_propose_ACK(call, ack, ack_serial,
 594                                   immediate_ack, true,
 595                                   rxrpc_propose_ack_input_data);
 596         else
 597                 rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial,
 598                                   false, true,
 599                                   rxrpc_propose_ack_input_data);
 600
 601         trace_rxrpc_notify_socket(call->debug_id, serial);
 602         rxrpc_notify_socket(call);
 603
 604 unlock:
 605         spin_unlock(&call->input_lock);
 606         rxrpc_free_skb(skb, rxrpc_skb_freed);
 607         _leave(" [queued]");
 608 }
 609
 610 /*
 611  * Process a requested ACK.
 612  */
 613 static void rxrpc_input_requested_ack(struct rxrpc_call *call,
 614                                       ktime_t resp_time,
 615                                       rxrpc_serial_t orig_serial,
 616                                       rxrpc_serial_t ack_serial)
 617 {
 618         struct rxrpc_skb_priv *sp;
 619         struct sk_buff *skb;
 620         ktime_t sent_at;
 621         int ix;
 622
 623         for (ix = 0; ix < RXRPC_RXTX_BUFF_SIZE; ix++) {
 624                 skb = call->rxtx_buffer[ix];
 625                 if (!skb)
 626                         continue;
 627
 628                 sent_at = skb->tstamp;
 629                 smp_rmb(); /* Read timestamp before serial. */
 630                 sp = rxrpc_skb(skb);
 631                 if (sp->hdr.serial != orig_serial)
 632                         continue;
 633                 goto found;
 634         }
 635
 636         return;
 637
 638 found:
 639         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_requested_ack,
 640                            orig_serial, ack_serial, sent_at, resp_time);
 641 }
 642
 643 /*
 644  * Process the response to a ping that we sent to find out if we lost an ACK.
 645  *
 646  * If we got back a ping response that indicates a lower tx_top than what we
 647  * had at the time of the ping transmission, we adjudge all the DATA packets
 648  * sent between the response tx_top and the ping-time tx_top to have been lost.
 649  */
 650 static void rxrpc_input_check_for_lost_ack(struct rxrpc_call *call)
 651 {
 652         rxrpc_seq_t top, bottom, seq;
 653         bool resend = false;
 654
 655         spin_lock_bh(&call->lock);
 656
 657         bottom = call->tx_hard_ack + 1;
 658         top = call->acks_lost_top;
 659         if (before(bottom, top)) {
 660                 for (seq = bottom; before_eq(seq, top); seq++) {
 661                         int ix = seq & RXRPC_RXTX_BUFF_MASK;
 662                         u8 annotation = call->rxtx_annotations[ix];
 663                         u8 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 664
 665                         if (anno_type != RXRPC_TX_ANNO_UNACK)
 666                                 continue;
 667                         annotation &= ~RXRPC_TX_ANNO_MASK;
 668                         annotation |= RXRPC_TX_ANNO_RETRANS;
 669                         call->rxtx_annotations[ix] = annotation;
 670                         resend = true;
 671                 }
 672         }
 673
 674         spin_unlock_bh(&call->lock);
 675
 676         if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events))
 677                 rxrpc_queue_call(call);
 678 }
 679
 680 /*
 681  * Process a ping response.
 682  */
 683 static void rxrpc_input_ping_response(struct rxrpc_call *call,
 684                                       ktime_t resp_time,
 685                                       rxrpc_serial_t orig_serial,
 686                                       rxrpc_serial_t ack_serial)
 687 {
 688         rxrpc_serial_t ping_serial;
 689         ktime_t ping_time;
 690
 691         ping_time = call->ping_time;
 692         smp_rmb();
 693         ping_serial = READ_ONCE(call->ping_serial);
 694
 695         if (orig_serial == call->acks_lost_ping)
 696                 rxrpc_input_check_for_lost_ack(call);
 697
 698         if (before(orig_serial, ping_serial) ||
 699             !test_and_clear_bit(RXRPC_CALL_PINGING, &call->flags))
 700                 return;
 701         if (after(orig_serial, ping_serial))
 702                 return;
 703
 704         rxrpc_peer_add_rtt(call, rxrpc_rtt_rx_ping_response,
 705                            orig_serial, ack_serial, ping_time, resp_time);
 706 }
 707
 708 /*
 709  * Process the extra information that may be appended to an ACK packet
 710  */
 711 static void rxrpc_input_ackinfo(struct rxrpc_call *call, struct sk_buff *skb,
 712                                 struct rxrpc_ackinfo *ackinfo)
 713 {
 714         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 715         struct rxrpc_peer *peer;
 716         unsigned int mtu;
 717         bool wake = false;
 718         u32 rwind = ntohl(ackinfo->rwind);
 719
 720         _proto("Rx ACK %%%u Info { rx=%u max=%u rwin=%u jm=%u }",
 721                sp->hdr.serial,
 722                ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU),
 723                rwind, ntohl(ackinfo->jumbo_max));
 724
 725         if (rwind > RXRPC_RXTX_BUFF_SIZE - 1)
 726                 rwind = RXRPC_RXTX_BUFF_SIZE - 1;
 727         if (call->tx_winsize != rwind) {
 728                 if (rwind > call->tx_winsize)
 729                         wake = true;
 730                 trace_rxrpc_rx_rwind_change(call, sp->hdr.serial, rwind, wake);
 731                 call->tx_winsize = rwind;
 732         }
 733
 734         if (call->cong_ssthresh > rwind)
 735                 call->cong_ssthresh = rwind;
 736
 737         mtu = min(ntohl(ackinfo->rxMTU), ntohl(ackinfo->maxMTU));
 738
 739         peer = call->peer;
 740         if (mtu < peer->maxdata) {
 741                 spin_lock_bh(&peer->lock);
 742                 peer->maxdata = mtu;
 743                 peer->mtu = mtu + peer->hdrsize;
 744                 spin_unlock_bh(&peer->lock);
 745                 _net("Net MTU %u (maxdata %u)", peer->mtu, peer->maxdata);
 746         }
 747
 748         if (wake)
 749                 wake_up(&call->waitq);
 750 }
 751
 752 /*
 753  * Process individual soft ACKs.
 754  *
 755  * Each ACK in the array corresponds to one packet and can be either an ACK or
 756  * a NAK.  If we get find an explicitly NAK'd packet we resend immediately;
 757  * packets that lie beyond the end of the ACK list are scheduled for resend by
 758  * the timer on the basis that the peer might just not have processed them at
 759  * the time the ACK was sent.
 760  */
 761 static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks,
 762                                   rxrpc_seq_t seq, int nr_acks,
 763                                   struct rxrpc_ack_summary *summary)
 764 {
 765         int ix;
 766         u8 annotation, anno_type;
 767
 768         for (; nr_acks > 0; nr_acks--, seq++) {
 769                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 770                 annotation = call->rxtx_annotations[ix];
 771                 anno_type = annotation & RXRPC_TX_ANNO_MASK;
 772                 annotation &= ~RXRPC_TX_ANNO_MASK;
 773                 switch (*acks++) {
 774                 case RXRPC_ACK_TYPE_ACK:
 775                         summary->nr_acks++;
 776                         if (anno_type == RXRPC_TX_ANNO_ACK)
 777                                 continue;
 778                         summary->nr_new_acks++;
 779                         call->rxtx_annotations[ix] =
 780                                 RXRPC_TX_ANNO_ACK | annotation;
 781                         break;
 782                 case RXRPC_ACK_TYPE_NACK:
 783                         if (!summary->nr_nacks &&
 784                             call->acks_lowest_nak != seq) {
 785                                 call->acks_lowest_nak = seq;
 786                                 summary->new_low_nack = true;
 787                         }
 788                         summary->nr_nacks++;
 789                         if (anno_type == RXRPC_TX_ANNO_NAK)
 790                                 continue;
 791                         summary->nr_new_nacks++;
 792                         if (anno_type == RXRPC_TX_ANNO_RETRANS)
 793                                 continue;
 794                         call->rxtx_annotations[ix] =
 795                                 RXRPC_TX_ANNO_NAK | annotation;
 796                         break;
 797                 default:
 798                         return rxrpc_proto_abort("SFT", call, 0);
 799                 }
 800         }
 801 }
 802
 803 /*
 804  * Return true if the ACK is valid - ie. it doesn't appear to have regressed
 805  * with respect to the ack state conveyed by preceding ACKs.
 806  */
 807 static bool rxrpc_is_ack_valid(struct rxrpc_call *call,
 808                                rxrpc_seq_t first_pkt, rxrpc_seq_t prev_pkt)
 809 {
 810         rxrpc_seq_t base = READ_ONCE(call->ackr_first_seq);
 811
 812         if (after(first_pkt, base))
 813                 return true; /* The window advanced */
 814
 815         if (before(first_pkt, base))
 816                 return false; /* firstPacket regressed */
 817
 818         if (after_eq(prev_pkt, call->ackr_prev_seq))
 819                 return true; /* previousPacket hasn't regressed. */
 820
 821         /* Some rx implementations put a serial number in previousPacket. */
 822         if (after_eq(prev_pkt, base + call->tx_winsize))
 823                 return false;
 824         return true;
 825 }
 826
 827 /*
 828  * Process an ACK packet.
 829  *
 830  * ack.firstPacket is the sequence number of the first soft-ACK'd/NAK'd packet
 831  * in the ACK array.  Anything before that is hard-ACK'd and may be discarded.
 832  *
 833  * A hard-ACK means that a packet has been processed and may be discarded; a
 834  * soft-ACK means that the packet may be discarded and retransmission
 835  * requested.  A phase is complete when all packets are hard-ACK'd.
 836  */
 837 static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 838 {
 839         struct rxrpc_ack_summary summary = { 0 };
 840         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 841         union {
 842                 struct rxrpc_ackpacket ack;
 843                 struct rxrpc_ackinfo info;
 844                 u8 acks[RXRPC_MAXACKS];
 845         } buf;
 846         rxrpc_serial_t acked_serial;
 847         rxrpc_seq_t first_soft_ack, hard_ack, prev_pkt;
 848         int nr_acks, offset, ioffset;
 849
 850         _enter("");
 851
 852         offset = sizeof(struct rxrpc_wire_header);
 853         if (skb_copy_bits(skb, offset, &buf.ack, sizeof(buf.ack)) < 0) {
 854                 _debug("extraction failure");
 855                 return rxrpc_proto_abort("XAK", call, 0);
 856         }
 857         offset += sizeof(buf.ack);
 858
 859         acked_serial = ntohl(buf.ack.serial);
 860         first_soft_ack = ntohl(buf.ack.firstPacket);
 861         prev_pkt = ntohl(buf.ack.previousPacket);
 862         hard_ack = first_soft_ack - 1;
 863         nr_acks = buf.ack.nAcks;
 864         summary.ack_reason = (buf.ack.reason < RXRPC_ACK__INVALID ?
 865                               buf.ack.reason : RXRPC_ACK__INVALID);
 866
 867         trace_rxrpc_rx_ack(call, sp->hdr.serial, acked_serial,
 868                            first_soft_ack, prev_pkt,
 869                            summary.ack_reason, nr_acks);
 870
 871         if (buf.ack.reason == RXRPC_ACK_PING_RESPONSE)
 872                 rxrpc_input_ping_response(call, skb->tstamp, acked_serial,
 873                                           sp->hdr.serial);
 874         if (buf.ack.reason == RXRPC_ACK_REQUESTED)
 875                 rxrpc_input_requested_ack(call, skb->tstamp, acked_serial,
 876                                           sp->hdr.serial);
 877
 878         if (buf.ack.reason == RXRPC_ACK_PING) {
 879                 _proto("Rx ACK %%%u PING Request", sp->hdr.serial);
 880                 rxrpc_propose_ACK(call, RXRPC_ACK_PING_RESPONSE,
 881                                   sp->hdr.serial, true, true,
 882                                   rxrpc_propose_ack_respond_to_ping);
 883         } else if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 884                 rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 885                                   sp->hdr.serial, true, true,
 886                                   rxrpc_propose_ack_respond_to_ack);
 887         }
 888
 889         /* Discard any out-of-order or duplicate ACKs (outside lock). */
 890         if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
 891                 trace_rxrpc_rx_discard_ack(call->debug_id, sp->hdr.serial,
 892                                            first_soft_ack, call->ackr_first_seq,
 893                                            prev_pkt, call->ackr_prev_seq);
 894                 return;
 895         }
 896
 897         buf.info.rxMTU = 0;
 898         ioffset = offset + nr_acks + 3;
 899         if (skb->len >= ioffset + sizeof(buf.info) &&
 900             skb_copy_bits(skb, ioffset, &buf.info, sizeof(buf.info)) < 0)
 901                 return rxrpc_proto_abort("XAI", call, 0);
 902
 903         spin_lock(&call->input_lock);
 904
 905         /* Discard any out-of-order or duplicate ACKs (inside lock). */
 906         if (!rxrpc_is_ack_valid(call, first_soft_ack, prev_pkt)) {
 907                 trace_rxrpc_rx_discard_ack(call->debug_id, sp->hdr.serial,
 908                                            first_soft_ack, call->ackr_first_seq,
 909                                            prev_pkt, call->ackr_prev_seq);
 910                 goto out;
 911         }
 912         call->acks_latest_ts = skb->tstamp;
 913
 914         call->ackr_first_seq = first_soft_ack;
 915         call->ackr_prev_seq = prev_pkt;
 916
 917         /* Parse rwind and mtu sizes if provided. */
 918         if (buf.info.rxMTU)
 919                 rxrpc_input_ackinfo(call, skb, &buf.info);
 920
 921         if (first_soft_ack == 0) {
 922                 rxrpc_proto_abort("AK0", call, 0);
 923                 goto out;
 924         }
 925
 926         /* Ignore ACKs unless we are or have just been transmitting. */
 927         switch (READ_ONCE(call->state)) {
 928         case RXRPC_CALL_CLIENT_SEND_REQUEST:
 929         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 930         case RXRPC_CALL_SERVER_SEND_REPLY:
 931         case RXRPC_CALL_SERVER_AWAIT_ACK:
 932                 break;
 933         default:
 934                 goto out;
 935         }
 936
 937         if (before(hard_ack, call->tx_hard_ack) ||
 938             after(hard_ack, call->tx_top)) {
 939                 rxrpc_proto_abort("AKW", call, 0);
 940                 goto out;
 941         }
 942         if (nr_acks > call->tx_top - hard_ack) {
 943                 rxrpc_proto_abort("AKN", call, 0);
 944                 goto out;
 945         }
 946
 947         if (after(hard_ack, call->tx_hard_ack)) {
 948                 if (rxrpc_rotate_tx_window(call, hard_ack, &summary)) {
 949                         rxrpc_end_tx_phase(call, false, "ETA");
 950                         goto out;
 951                 }
 952         }
 953
 954         if (nr_acks > 0) {
 955                 if (skb_copy_bits(skb, offset, buf.acks, nr_acks) < 0) {
 956                         rxrpc_proto_abort("XSA", call, 0);
 957                         goto out;
 958                 }
 959                 rxrpc_input_soft_acks(call, buf.acks, first_soft_ack, nr_acks,
 960                                       &summary);
 961         }
 962
 963         if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] &
 964             RXRPC_TX_ANNO_LAST &&
 965             summary.nr_acks == call->tx_top - hard_ack &&
 966             rxrpc_is_client_call(call))
 967                 rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial,
 968                                   false, true,
 969                                   rxrpc_propose_ack_ping_for_lost_reply);
 970
 971         rxrpc_congestion_management(call, skb, &summary, acked_serial);
 972 out:
 973         spin_unlock(&call->input_lock);
 974 }
 975
 976 /*
 977  * Process an ACKALL packet.
 978  */
 979 static void rxrpc_input_ackall(struct rxrpc_call *call, struct sk_buff *skb)
 980 {
 981         struct rxrpc_ack_summary summary = { 0 };
 982         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 983
 984         _proto("Rx ACKALL %%%u", sp->hdr.serial);
 985
 986         spin_lock(&call->input_lock);
 987
 988         if (rxrpc_rotate_tx_window(call, call->tx_top, &summary))
 989                 rxrpc_end_tx_phase(call, false, "ETL");
 990
 991         spin_unlock(&call->input_lock);
 992 }
 993
 994 /*
 995  * Process an ABORT packet directed at a call.
 996  */
 997 static void rxrpc_input_abort(struct rxrpc_call *call, struct sk_buff *skb)
 998 {
 999         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1000         __be32 wtmp;
1001         u32 abort_code = RX_CALL_DEAD;
1002
1003         _enter("");
1004
1005         if (skb->len >= 4 &&
1006             skb_copy_bits(skb, sizeof(struct rxrpc_wire_header),
1007                           &wtmp, sizeof(wtmp)) >= 0)
1008                 abort_code = ntohl(wtmp);
1009
1010         trace_rxrpc_rx_abort(call, sp->hdr.serial, abort_code);
1011
1012         _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
1013
1014         rxrpc_set_call_completion(call, RXRPC_CALL_REMOTELY_ABORTED,
1015                                   abort_code, -ECONNABORTED);
1016 }
1017
1018 /*
1019  * Process an incoming call packet.
1020  */
1021 static void rxrpc_input_call_packet(struct rxrpc_call *call,
1022                                     struct sk_buff *skb)
1023 {
1024         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
1025         unsigned long timo;
1026
1027         _enter("%p,%p", call, skb);
1028
1029         timo = READ_ONCE(call->next_rx_timo);
1030         if (timo) {
1031                 unsigned long now = jiffies, expect_rx_by;
1032
1033                 expect_rx_by = now + timo;
1034                 WRITE_ONCE(call->expect_rx_by, expect_rx_by);
1035                 rxrpc_reduce_call_timer(call, expect_rx_by, now,
1036                                         rxrpc_timer_set_for_normal);
1037         }
1038
1039         switch (sp->hdr.type) {
1040         case RXRPC_PACKET_TYPE_DATA:
1041                 rxrpc_input_data(call, skb);
1042                 goto no_free;
1043
1044         case RXRPC_PACKET_TYPE_ACK:
1045                 rxrpc_input_ack(call, skb);
1046                 break;
1047
1048         case RXRPC_PACKET_TYPE_BUSY:
1049                 _proto("Rx BUSY %%%u", sp->hdr.serial);
1050
1051                 /* Just ignore BUSY packets from the server; the retry and
1052                  * lifespan timers will take care of business.  BUSY packets
1053                  * from the client don't make sense.
1054                  */
1055                 break;
1056
1057         case RXRPC_PACKET_TYPE_ABORT:
1058                 rxrpc_input_abort(call, skb);
1059                 break;
1060
1061         case RXRPC_PACKET_TYPE_ACKALL:
1062                 rxrpc_input_ackall(call, skb);
1063                 break;
1064
1065         default:
1066                 break;
1067         }
1068
1069         rxrpc_free_skb(skb, rxrpc_skb_freed);
1070 no_free:
1071         _leave("");
1072 }
1073
1074 /*
1075  * Handle a new service call on a channel implicitly completing the preceding
1076  * call on that channel.  This does not apply to client conns.
1077  *
1078  * TODO: If callNumber > call_id + 1, renegotiate security.
1079  */
1080 static void rxrpc_input_implicit_end_call(struct rxrpc_sock *rx,
1081                                           struct rxrpc_connection *conn,
1082                                           struct rxrpc_call *call)
1083 {
1084         switch (READ_ONCE(call->state)) {
1085         case RXRPC_CALL_SERVER_AWAIT_ACK:
1086                 rxrpc_call_completed(call);
1087                 fallthrough;
1088         case RXRPC_CALL_COMPLETE:
1089                 break;
1090         default:
1091                 if (rxrpc_abort_call("IMP", call, 0, RX_CALL_DEAD, -ESHUTDOWN)) {
1092                         set_bit(RXRPC_CALL_EV_ABORT, &call->events);
1093                         rxrpc_queue_call(call);
1094                 }
1095                 trace_rxrpc_improper_term(call);
1096                 break;
1097         }
1098
1099         spin_lock(&rx->incoming_lock);
1100         __rxrpc_disconnect_call(conn, call);
1101         spin_unlock(&rx->incoming_lock);
1102 }
1103
1104 /*
1105  * post connection-level events to the connection
1106  * - this includes challenges, responses, some aborts and call terminal packet
1107  *   retransmission.
1108  */
1109 static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
1110                                       struct sk_buff *skb)
1111 {
1112         _enter("%p,%p", conn, skb);
1113
1114         skb_queue_tail(&conn->rx_queue, skb);
1115         rxrpc_queue_conn(conn);
1116 }
1117
1118 /*
1119  * post endpoint-level events to the local endpoint
1120  * - this includes debug and version messages
1121  */
1122 static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
1123                                        struct sk_buff *skb)
1124 {
1125         _enter("%p,%p", local, skb);
1126
1127         if (rxrpc_get_local_maybe(local)) {
1128                 skb_queue_tail(&local->event_queue, skb);
1129                 rxrpc_queue_local(local);
1130         } else {
1131                 rxrpc_free_skb(skb, rxrpc_skb_freed);
1132         }
1133 }
1134
1135 /*
1136  * put a packet up for transport-level abort
1137  */
1138 static void rxrpc_reject_packet(struct rxrpc_local *local, struct sk_buff *skb)
1139 {
1140         CHECK_SLAB_OKAY(&local->usage);
1141
1142         if (rxrpc_get_local_maybe(local)) {
1143                 skb_queue_tail(&local->reject_queue, skb);
1144                 rxrpc_queue_local(local);
1145         } else {
1146                 rxrpc_free_skb(skb, rxrpc_skb_freed);
1147         }
1148 }
1149
1150 /*
1151  * Extract the wire header from a packet and translate the byte order.
1152  */
1153 static noinline
1154 int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
1155 {
1156         struct rxrpc_wire_header whdr;
1157
1158         /* dig out the RxRPC connection details */
1159         if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0) {
1160                 trace_rxrpc_rx_eproto(NULL, sp->hdr.serial,
1161                                       tracepoint_string("bad_hdr"));
1162                 return -EBADMSG;
1163         }
1164
1165         memset(sp, 0, sizeof(*sp));
1166         sp->hdr.epoch           = ntohl(whdr.epoch);
1167         sp->hdr.cid             = ntohl(whdr.cid);
1168         sp->hdr.callNumber      = ntohl(whdr.callNumber);
1169         sp->hdr.seq             = ntohl(whdr.seq);
1170         sp->hdr.serial          = ntohl(whdr.serial);
1171         sp->hdr.flags           = whdr.flags;
1172         sp->hdr.type            = whdr.type;
1173         sp->hdr.userStatus      = whdr.userStatus;
1174         sp->hdr.securityIndex   = whdr.securityIndex;
1175         sp->hdr._rsvd           = ntohs(whdr._rsvd);
1176         sp->hdr.serviceId       = ntohs(whdr.serviceId);
1177         return 0;
1178 }
1179
1180 /*
1181  * handle data received on the local endpoint
1182  * - may be called in interrupt context
1183  *
1184  * [!] Note that as this is called from the encap_rcv hook, the socket is not
1185  * held locked by the caller and nothing prevents sk_user_data on the UDP from
1186  * being cleared in the middle of processing this function.
1187  *
1188  * Called with the RCU read lock held from the IP layer via UDP.
1189  */
1190 int rxrpc_input_packet(struct sock *udp_sk, struct sk_buff *skb)
1191 {
1192         struct rxrpc_local *local = rcu_dereference_sk_user_data(udp_sk);
1193         struct rxrpc_connection *conn;
1194         struct rxrpc_channel *chan;
1195         struct rxrpc_call *call = NULL;
1196         struct rxrpc_skb_priv *sp;
1197         struct rxrpc_peer *peer = NULL;
1198         struct rxrpc_sock *rx = NULL;
1199         unsigned int channel;
1200
1201         _enter("%p", udp_sk);
1202
1203         if (unlikely(!local)) {
1204                 kfree_skb(skb);
1205                 return 0;
1206         }
1207         if (skb->tstamp == 0)
1208                 skb->tstamp = ktime_get_real();
1209
1210         rxrpc_new_skb(skb, rxrpc_skb_received);
1211
1212         skb_pull(skb, sizeof(struct udphdr));
1213
1214         /* The UDP protocol already released all skb resources;
1215          * we are free to add our own data there.
1216          */
1217         sp = rxrpc_skb(skb);
1218
1219         /* dig out the RxRPC connection details */
1220         if (rxrpc_extract_header(sp, skb) < 0)
1221                 goto bad_message;
1222
1223         if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
1224                 static int lose;
1225                 if ((lose++ & 7) == 7) {
1226                         trace_rxrpc_rx_lose(sp);
1227                         rxrpc_free_skb(skb, rxrpc_skb_lost);
1228                         return 0;
1229                 }
1230         }
1231
1232         if (skb->tstamp == 0)
1233                 skb->tstamp = ktime_get_real();
1234         trace_rxrpc_rx_packet(sp);
1235
1236         switch (sp->hdr.type) {
1237         case RXRPC_PACKET_TYPE_VERSION:
1238                 if (rxrpc_to_client(sp))
1239                         goto discard;
1240                 rxrpc_post_packet_to_local(local, skb);
1241                 goto out;
1242
1243         case RXRPC_PACKET_TYPE_BUSY:
1244                 if (rxrpc_to_server(sp))
1245                         goto discard;
1246                 fallthrough;
1247         case RXRPC_PACKET_TYPE_ACK:
1248         case RXRPC_PACKET_TYPE_ACKALL:
1249                 if (sp->hdr.callNumber == 0)
1250                         goto bad_message;
1251                 fallthrough;
1252         case RXRPC_PACKET_TYPE_ABORT:
1253                 break;
1254
1255         case RXRPC_PACKET_TYPE_DATA:
1256                 if (sp->hdr.callNumber == 0 ||
1257                     sp->hdr.seq == 0)
1258                         goto bad_message;
1259                 if (!rxrpc_validate_data(skb))
1260                         goto bad_message;
1261
1262                 /* Unshare the packet so that it can be modified for in-place
1263                  * decryption.
1264                  */
1265                 if (sp->hdr.securityIndex != 0) {
1266                         struct sk_buff *nskb = skb_unshare(skb, GFP_ATOMIC);
1267                         if (!nskb) {
1268                                 rxrpc_eaten_skb(skb, rxrpc_skb_unshared_nomem);
1269                                 goto out;
1270                         }
1271
1272                         if (nskb != skb) {
1273                                 rxrpc_eaten_skb(skb, rxrpc_skb_received);
1274                                 skb = nskb;
1275                                 rxrpc_new_skb(skb, rxrpc_skb_unshared);
1276                                 sp = rxrpc_skb(skb);
1277                         }
1278                 }
1279                 break;
1280
1281         case RXRPC_PACKET_TYPE_CHALLENGE:
1282                 if (rxrpc_to_server(sp))
1283                         goto discard;
1284                 break;
1285         case RXRPC_PACKET_TYPE_RESPONSE:
1286                 if (rxrpc_to_client(sp))
1287                         goto discard;
1288                 break;
1289
1290                 /* Packet types 9-11 should just be ignored. */
1291         case RXRPC_PACKET_TYPE_PARAMS:
1292         case RXRPC_PACKET_TYPE_10:
1293         case RXRPC_PACKET_TYPE_11:
1294                 goto discard;
1295
1296         default:
1297                 _proto("Rx Bad Packet Type %u", sp->hdr.type);
1298                 goto bad_message;
1299         }
1300
1301         if (sp->hdr.serviceId == 0)
1302                 goto bad_message;
1303
1304         if (rxrpc_to_server(sp)) {
1305                 /* Weed out packets to services we're not offering.  Packets
1306                  * that would begin a call are explicitly rejected and the rest
1307                  * are just discarded.
1308                  */
1309                 rx = rcu_dereference(local->service);
1310                 if (!rx || (sp->hdr.serviceId != rx->srx.srx_service &&
1311                             sp->hdr.serviceId != rx->second_service)) {
1312                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
1313                             sp->hdr.seq == 1)
1314                                 goto unsupported_service;
1315                         goto discard;
1316                 }
1317         }
1318
1319         conn = rxrpc_find_connection_rcu(local, skb, &peer);
1320         if (conn) {
1321                 if (sp->hdr.securityIndex != conn->security_ix)
1322                         goto wrong_security;
1323
1324                 if (sp->hdr.serviceId != conn->service_id) {
1325                         int old_id;
1326
1327                         if (!test_bit(RXRPC_CONN_PROBING_FOR_UPGRADE, &conn->flags))
1328                                 goto reupgrade;
1329                         old_id = cmpxchg(&conn->service_id, conn->params.service_id,
1330                                          sp->hdr.serviceId);
1331
1332                         if (old_id != conn->params.service_id &&
1333                             old_id != sp->hdr.serviceId)
1334                                 goto reupgrade;
1335                 }
1336
1337                 if (sp->hdr.callNumber == 0) {
1338                         /* Connection-level packet */
1339                         _debug("CONN %p {%d}", conn, conn->debug_id);
1340                         rxrpc_post_packet_to_conn(conn, skb);
1341                         goto out;
1342                 }
1343
1344                 if ((int)sp->hdr.serial - (int)conn->hi_serial > 0)
1345                         conn->hi_serial = sp->hdr.serial;
1346
1347                 /* Call-bound packets are routed by connection channel. */
1348                 channel = sp->hdr.cid & RXRPC_CHANNELMASK;
1349                 chan = &conn->channels[channel];
1350
1351                 /* Ignore really old calls */
1352                 if (sp->hdr.callNumber < chan->last_call)
1353                         goto discard;
1354
1355                 if (sp->hdr.callNumber == chan->last_call) {
1356                         if (chan->call ||
1357                             sp->hdr.type == RXRPC_PACKET_TYPE_ABORT)
1358                                 goto discard;
1359
1360                         /* For the previous service call, if completed
1361                          * successfully, we discard all further packets.
1362                          */
1363                         if (rxrpc_conn_is_service(conn) &&
1364                             chan->last_type == RXRPC_PACKET_TYPE_ACK)
1365                                 goto discard;
1366
1367                         /* But otherwise we need to retransmit the final packet
1368                          * from data cached in the connection record.
1369                          */
1370                         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA)
1371                                 trace_rxrpc_rx_data(chan->call_debug_id,
1372                                                     sp->hdr.seq,
1373                                                     sp->hdr.serial,
1374                                                     sp->hdr.flags, 0);
1375                         rxrpc_post_packet_to_conn(conn, skb);
1376                         goto out;
1377                 }
1378
1379                 call = rcu_dereference(chan->call);
1380
1381                 if (sp->hdr.callNumber > chan->call_id) {
1382                         if (rxrpc_to_client(sp))
1383                                 goto reject_packet;
1384                         if (call)
1385                                 rxrpc_input_implicit_end_call(rx, conn, call);
1386                         call = NULL;
1387                 }
1388
1389                 if (call) {
1390                         if (sp->hdr.serviceId != call->service_id)
1391                                 call->service_id = sp->hdr.serviceId;
1392                         if ((int)sp->hdr.serial - (int)call->rx_serial > 0)
1393                                 call->rx_serial = sp->hdr.serial;
1394                         if (!test_bit(RXRPC_CALL_RX_HEARD, &call->flags))
1395                                 set_bit(RXRPC_CALL_RX_HEARD, &call->flags);
1396                 }
1397         }
1398
1399         if (!call || atomic_read(&call->usage) == 0) {
1400                 if (rxrpc_to_client(sp) ||
1401                     sp->hdr.type != RXRPC_PACKET_TYPE_DATA)
1402                         goto bad_message;
1403                 if (sp->hdr.seq != 1)
1404                         goto discard;
1405                 call = rxrpc_new_incoming_call(local, rx, skb);
1406                 if (!call)
1407                         goto reject_packet;
1408         }
1409
1410         /* Process a call packet; this either discards or passes on the ref
1411          * elsewhere.
1412          */
1413         rxrpc_input_call_packet(call, skb);
1414         goto out;
1415
1416 discard:
1417         rxrpc_free_skb(skb, rxrpc_skb_freed);
1418 out:
1419         trace_rxrpc_rx_done(0, 0);
1420         return 0;
1421
1422 wrong_security:
1423         trace_rxrpc_abort(0, "SEC", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1424                           RXKADINCONSISTENCY, EBADMSG);
1425         skb->priority = RXKADINCONSISTENCY;
1426         goto post_abort;
1427
1428 unsupported_service:
1429         trace_rxrpc_abort(0, "INV", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1430                           RX_INVALID_OPERATION, EOPNOTSUPP);
1431         skb->priority = RX_INVALID_OPERATION;
1432         goto post_abort;
1433
1434 reupgrade:
1435         trace_rxrpc_abort(0, "UPG", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1436                           RX_PROTOCOL_ERROR, EBADMSG);
1437         goto protocol_error;
1438
1439 bad_message:
1440         trace_rxrpc_abort(0, "BAD", sp->hdr.cid, sp->hdr.callNumber, sp->hdr.seq,
1441                           RX_PROTOCOL_ERROR, EBADMSG);
1442 protocol_error:
1443         skb->priority = RX_PROTOCOL_ERROR;
1444 post_abort:
1445         skb->mark = RXRPC_SKB_MARK_REJECT_ABORT;
1446 reject_packet:
1447         trace_rxrpc_rx_done(skb->mark, skb->priority);
1448         rxrpc_reject_packet(local, skb);
1449         _leave(" [badmsg]");
1450         return 0;
1451 }