net/rxrpc/input.c

   1 /* RxRPC packet reception
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/module.h>
  15 #include <linux/net.h>
  16 #include <linux/skbuff.h>
  17 #include <linux/errqueue.h>
  18 #include <linux/udp.h>
  19 #include <linux/in.h>
  20 #include <linux/in6.h>
  21 #include <linux/icmp.h>
  22 #include <linux/gfp.h>
  23 #include <net/sock.h>
  24 #include <net/af_rxrpc.h>
  25 #include <net/ip.h>
  26 #include <net/udp.h>
  27 #include <net/net_namespace.h>
  28 #include "ar-internal.h"
  29
  30 /*
  31  * queue a packet for recvmsg to pass to userspace
  32  * - the caller must hold a lock on call->lock
  33  * - must not be called with interrupts disabled (sk_filter() disables BH's)
  34  * - eats the packet whether successful or not
  35  * - there must be just one reference to the packet, which the caller passes to
  36  *   this function
  37  */
  38 int rxrpc_queue_rcv_skb(struct rxrpc_call *call, struct sk_buff *skb,
  39                         bool force, bool terminal)
  40 {
  41         struct rxrpc_skb_priv *sp;
  42         struct rxrpc_sock *rx = call->socket;
  43         struct sock *sk;
  44         int ret;
  45
  46         _enter(",,%d,%d", force, terminal);
  47
  48         ASSERT(!irqs_disabled());
  49
  50         sp = rxrpc_skb(skb);
  51         ASSERTCMP(sp->call, ==, call);
  52
  53         /* if we've already posted the terminal message for a call, then we
  54          * don't post any more */
  55         if (test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags)) {
  56                 _debug("already terminated");
  57                 ASSERTCMP(call->state, >=, RXRPC_CALL_COMPLETE);
  58                 rxrpc_free_skb(skb);
  59                 return 0;
  60         }
  61
  62         sk = &rx->sk;
  63
  64         if (!force) {
  65                 /* cast skb->rcvbuf to unsigned...  It's pointless, but
  66                  * reduces number of warnings when compiling with -W
  67                  * --ANK */
  68 //              ret = -ENOBUFS;
  69 //              if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
  70 //                  (unsigned int) sk->sk_rcvbuf)
  71 //                      goto out;
  72
  73                 ret = sk_filter(sk, skb);
  74                 if (ret < 0)
  75                         goto out;
  76         }
  77
  78         spin_lock_bh(&sk->sk_receive_queue.lock);
  79         if (!test_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags) &&
  80             !test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
  81             call->socket->sk.sk_state != RXRPC_CLOSE) {
  82                 skb->destructor = rxrpc_packet_destructor;
  83                 skb->dev = NULL;
  84                 skb->sk = sk;
  85                 atomic_add(skb->truesize, &sk->sk_rmem_alloc);
  86
  87                 if (terminal) {
  88                         _debug("<<<< TERMINAL MESSAGE >>>>");
  89                         set_bit(RXRPC_CALL_TERMINAL_MSG, &call->flags);
  90                 }
  91
  92                 /* allow interception by a kernel service */
  93                 if (rx->interceptor) {
  94                         rx->interceptor(sk, call->user_call_ID, skb);
  95                         spin_unlock_bh(&sk->sk_receive_queue.lock);
  96                 } else {
  97                         _net("post skb %p", skb);
  98                         __skb_queue_tail(&sk->sk_receive_queue, skb);
  99                         spin_unlock_bh(&sk->sk_receive_queue.lock);
 100
 101                         if (!sock_flag(sk, SOCK_DEAD))
 102                                 sk->sk_data_ready(sk);
 103                 }
 104                 skb = NULL;
 105         } else {
 106                 spin_unlock_bh(&sk->sk_receive_queue.lock);
 107         }
 108         ret = 0;
 109
 110 out:
 111         rxrpc_free_skb(skb);
 112
 113         _leave(" = %d", ret);
 114         return ret;
 115 }
 116
 117 /*
 118  * process a DATA packet, posting the packet to the appropriate queue
 119  * - eats the packet if successful
 120  */
 121 static int rxrpc_fast_process_data(struct rxrpc_call *call,
 122                                    struct sk_buff *skb, u32 seq)
 123 {
 124         struct rxrpc_skb_priv *sp;
 125         bool terminal;
 126         int ret, ackbit, ack;
 127         u32 serial;
 128         u16 skew;
 129         u8 flags;
 130
 131         _enter("{%u,%u},,{%u}", call->rx_data_post, call->rx_first_oos, seq);
 132
 133         sp = rxrpc_skb(skb);
 134         ASSERTCMP(sp->call, ==, NULL);
 135         flags = sp->hdr.flags;
 136         serial = sp->hdr.serial;
 137         skew = skb->priority;
 138
 139         spin_lock(&call->lock);
 140
 141         if (call->state > RXRPC_CALL_COMPLETE)
 142                 goto discard;
 143
 144         ASSERTCMP(call->rx_data_expect, >=, call->rx_data_post);
 145         ASSERTCMP(call->rx_data_post, >=, call->rx_data_recv);
 146         ASSERTCMP(call->rx_data_recv, >=, call->rx_data_eaten);
 147
 148         if (seq < call->rx_data_post) {
 149                 _debug("dup #%u [-%u]", seq, call->rx_data_post);
 150                 ack = RXRPC_ACK_DUPLICATE;
 151                 ret = -ENOBUFS;
 152                 goto discard_and_ack;
 153         }
 154
 155         /* we may already have the packet in the out of sequence queue */
 156         ackbit = seq - (call->rx_data_eaten + 1);
 157         ASSERTCMP(ackbit, >=, 0);
 158         if (__test_and_set_bit(ackbit, call->ackr_window)) {
 159                 _debug("dup oos #%u [%u,%u]",
 160                        seq, call->rx_data_eaten, call->rx_data_post);
 161                 ack = RXRPC_ACK_DUPLICATE;
 162                 goto discard_and_ack;
 163         }
 164
 165         if (seq >= call->ackr_win_top) {
 166                 _debug("exceed #%u [%u]", seq, call->ackr_win_top);
 167                 __clear_bit(ackbit, call->ackr_window);
 168                 ack = RXRPC_ACK_EXCEEDS_WINDOW;
 169                 goto discard_and_ack;
 170         }
 171
 172         if (seq == call->rx_data_expect) {
 173                 clear_bit(RXRPC_CALL_EXPECT_OOS, &call->flags);
 174                 call->rx_data_expect++;
 175         } else if (seq > call->rx_data_expect) {
 176                 _debug("oos #%u [%u]", seq, call->rx_data_expect);
 177                 call->rx_data_expect = seq + 1;
 178                 if (test_and_set_bit(RXRPC_CALL_EXPECT_OOS, &call->flags)) {
 179                         ack = RXRPC_ACK_OUT_OF_SEQUENCE;
 180                         goto enqueue_and_ack;
 181                 }
 182                 goto enqueue_packet;
 183         }
 184
 185         if (seq != call->rx_data_post) {
 186                 _debug("ahead #%u [%u]", seq, call->rx_data_post);
 187                 goto enqueue_packet;
 188         }
 189
 190         if (test_bit(RXRPC_CALL_RCVD_LAST, &call->flags))
 191                 goto protocol_error;
 192
 193         /* if the packet need security things doing to it, then it goes down
 194          * the slow path */
 195         if (call->conn->security_ix)
 196                 goto enqueue_packet;
 197
 198         sp->call = call;
 199         rxrpc_get_call(call);
 200         atomic_inc(&call->skb_count);
 201         terminal = ((flags & RXRPC_LAST_PACKET) &&
 202                     !(flags & RXRPC_CLIENT_INITIATED));
 203         ret = rxrpc_queue_rcv_skb(call, skb, false, terminal);
 204         if (ret < 0) {
 205                 if (ret == -ENOMEM || ret == -ENOBUFS) {
 206                         __clear_bit(ackbit, call->ackr_window);
 207                         ack = RXRPC_ACK_NOSPACE;
 208                         goto discard_and_ack;
 209                 }
 210                 goto out;
 211         }
 212
 213         skb = NULL;
 214         sp = NULL;
 215
 216         _debug("post #%u", seq);
 217         ASSERTCMP(call->rx_data_post, ==, seq);
 218         call->rx_data_post++;
 219
 220         if (flags & RXRPC_LAST_PACKET)
 221                 set_bit(RXRPC_CALL_RCVD_LAST, &call->flags);
 222
 223         /* if we've reached an out of sequence packet then we need to drain
 224          * that queue into the socket Rx queue now */
 225         if (call->rx_data_post == call->rx_first_oos) {
 226                 _debug("drain rx oos now");
 227                 read_lock(&call->state_lock);
 228                 if (call->state < RXRPC_CALL_COMPLETE &&
 229                     !test_and_set_bit(RXRPC_CALL_EV_DRAIN_RX_OOS, &call->events))
 230                         rxrpc_queue_call(call);
 231                 read_unlock(&call->state_lock);
 232         }
 233
 234         spin_unlock(&call->lock);
 235         atomic_inc(&call->ackr_not_idle);
 236         rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, skew, serial, false);
 237         _leave(" = 0 [posted]");
 238         return 0;
 239
 240 protocol_error:
 241         ret = -EBADMSG;
 242 out:
 243         spin_unlock(&call->lock);
 244         _leave(" = %d", ret);
 245         return ret;
 246
 247 discard_and_ack:
 248         _debug("discard and ACK packet %p", skb);
 249         __rxrpc_propose_ACK(call, ack, skew, serial, true);
 250 discard:
 251         spin_unlock(&call->lock);
 252         rxrpc_free_skb(skb);
 253         _leave(" = 0 [discarded]");
 254         return 0;
 255
 256 enqueue_and_ack:
 257         __rxrpc_propose_ACK(call, ack, skew, serial, true);
 258 enqueue_packet:
 259         _net("defer skb %p", skb);
 260         spin_unlock(&call->lock);
 261         skb_queue_tail(&call->rx_queue, skb);
 262         atomic_inc(&call->ackr_not_idle);
 263         read_lock(&call->state_lock);
 264         if (call->state < RXRPC_CALL_DEAD)
 265                 rxrpc_queue_call(call);
 266         read_unlock(&call->state_lock);
 267         _leave(" = 0 [queued]");
 268         return 0;
 269 }
 270
 271 /*
 272  * assume an implicit ACKALL of the transmission phase of a client socket upon
 273  * reception of the first reply packet
 274  */
 275 static void rxrpc_assume_implicit_ackall(struct rxrpc_call *call, u32 serial)
 276 {
 277         write_lock_bh(&call->state_lock);
 278
 279         switch (call->state) {
 280         case RXRPC_CALL_CLIENT_AWAIT_REPLY:
 281                 call->state = RXRPC_CALL_CLIENT_RECV_REPLY;
 282                 call->acks_latest = serial;
 283
 284                 _debug("implicit ACKALL %%%u", call->acks_latest);
 285                 set_bit(RXRPC_CALL_EV_RCVD_ACKALL, &call->events);
 286                 write_unlock_bh(&call->state_lock);
 287
 288                 if (try_to_del_timer_sync(&call->resend_timer) >= 0) {
 289                         clear_bit(RXRPC_CALL_EV_RESEND_TIMER, &call->events);
 290                         clear_bit(RXRPC_CALL_EV_RESEND, &call->events);
 291                         clear_bit(RXRPC_CALL_RUN_RTIMER, &call->flags);
 292                 }
 293                 break;
 294
 295         default:
 296                 write_unlock_bh(&call->state_lock);
 297                 break;
 298         }
 299 }
 300
 301 /*
 302  * post an incoming packet to the nominated call to deal with
 303  * - must get rid of the sk_buff, either by freeing it or by queuing it
 304  */
 305 void rxrpc_fast_process_packet(struct rxrpc_call *call, struct sk_buff *skb)
 306 {
 307         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 308         __be32 wtmp;
 309         u32 abort_code;
 310
 311         _enter("%p,%p", call, skb);
 312
 313         ASSERT(!irqs_disabled());
 314
 315 #if 0 // INJECT RX ERROR
 316         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA) {
 317                 static int skip = 0;
 318                 if (++skip == 3) {
 319                         printk("DROPPED 3RD PACKET!!!!!!!!!!!!!\n");
 320                         skip = 0;
 321                         goto free_packet;
 322                 }
 323         }
 324 #endif
 325
 326         /* request ACK generation for any ACK or DATA packet that requests
 327          * it */
 328         if (sp->hdr.flags & RXRPC_REQUEST_ACK) {
 329                 _proto("ACK Requested on %%%u", sp->hdr.serial);
 330                 rxrpc_propose_ACK(call, RXRPC_ACK_REQUESTED,
 331                                   skb->priority, sp->hdr.serial, false);
 332         }
 333
 334         switch (sp->hdr.type) {
 335         case RXRPC_PACKET_TYPE_ABORT:
 336                 _debug("abort");
 337
 338                 if (skb_copy_bits(skb, 0, &wtmp, sizeof(wtmp)) < 0)
 339                         goto protocol_error;
 340
 341                 abort_code = ntohl(wtmp);
 342                 _proto("Rx ABORT %%%u { %x }", sp->hdr.serial, abort_code);
 343
 344                 if (__rxrpc_set_call_completion(call,
 345                                                 RXRPC_CALL_REMOTELY_ABORTED,
 346                                                 abort_code, ECONNABORTED)) {
 347                         set_bit(RXRPC_CALL_EV_RCVD_ABORT, &call->events);
 348                         rxrpc_queue_call(call);
 349                 }
 350                 goto free_packet;
 351
 352         case RXRPC_PACKET_TYPE_BUSY:
 353                 _proto("Rx BUSY %%%u", sp->hdr.serial);
 354
 355                 if (rxrpc_conn_is_service(call->conn))
 356                         goto protocol_error;
 357
 358                 write_lock_bh(&call->state_lock);
 359                 switch (call->state) {
 360                 case RXRPC_CALL_CLIENT_SEND_REQUEST:
 361                         __rxrpc_set_call_completion(call,
 362                                                     RXRPC_CALL_SERVER_BUSY,
 363                                                     0, EBUSY);
 364                         set_bit(RXRPC_CALL_EV_RCVD_BUSY, &call->events);
 365                         rxrpc_queue_call(call);
 366                 case RXRPC_CALL_SERVER_BUSY:
 367                         goto free_packet_unlock;
 368                 default:
 369                         goto protocol_error_locked;
 370                 }
 371
 372         default:
 373                 _proto("Rx %s %%%u", rxrpc_pkts[sp->hdr.type], sp->hdr.serial);
 374                 goto protocol_error;
 375
 376         case RXRPC_PACKET_TYPE_DATA:
 377                 _proto("Rx DATA %%%u { #%u }", sp->hdr.serial, sp->hdr.seq);
 378
 379                 if (sp->hdr.seq == 0)
 380                         goto protocol_error;
 381
 382                 call->ackr_prev_seq = sp->hdr.seq;
 383
 384                 /* received data implicitly ACKs all of the request packets we
 385                  * sent when we're acting as a client */
 386                 if (call->state == RXRPC_CALL_CLIENT_AWAIT_REPLY)
 387                         rxrpc_assume_implicit_ackall(call, sp->hdr.serial);
 388
 389                 switch (rxrpc_fast_process_data(call, skb, sp->hdr.seq)) {
 390                 case 0:
 391                         skb = NULL;
 392                         goto done;
 393
 394                 default:
 395                         BUG();
 396
 397                         /* data packet received beyond the last packet */
 398                 case -EBADMSG:
 399                         goto protocol_error;
 400                 }
 401
 402         case RXRPC_PACKET_TYPE_ACKALL:
 403         case RXRPC_PACKET_TYPE_ACK:
 404                 /* ACK processing is done in process context */
 405                 read_lock_bh(&call->state_lock);
 406                 if (call->state < RXRPC_CALL_DEAD) {
 407                         skb_queue_tail(&call->rx_queue, skb);
 408                         rxrpc_queue_call(call);
 409                         skb = NULL;
 410                 }
 411                 read_unlock_bh(&call->state_lock);
 412                 goto free_packet;
 413         }
 414
 415 protocol_error:
 416         _debug("protocol error");
 417         write_lock_bh(&call->state_lock);
 418 protocol_error_locked:
 419         if (__rxrpc_abort_call(call, RX_PROTOCOL_ERROR, EPROTO))
 420                 rxrpc_queue_call(call);
 421 free_packet_unlock:
 422         write_unlock_bh(&call->state_lock);
 423 free_packet:
 424         rxrpc_free_skb(skb);
 425 done:
 426         _leave("");
 427 }
 428
 429 /*
 430  * split up a jumbo data packet
 431  */
 432 static void rxrpc_process_jumbo_packet(struct rxrpc_call *call,
 433                                        struct sk_buff *jumbo)
 434 {
 435         struct rxrpc_jumbo_header jhdr;
 436         struct rxrpc_skb_priv *sp;
 437         struct sk_buff *part;
 438
 439         _enter(",{%u,%u}", jumbo->data_len, jumbo->len);
 440
 441         sp = rxrpc_skb(jumbo);
 442
 443         do {
 444                 sp->hdr.flags &= ~RXRPC_JUMBO_PACKET;
 445
 446                 /* make a clone to represent the first subpacket in what's left
 447                  * of the jumbo packet */
 448                 part = skb_clone(jumbo, GFP_ATOMIC);
 449                 if (!part) {
 450                         /* simply ditch the tail in the event of ENOMEM */
 451                         pskb_trim(jumbo, RXRPC_JUMBO_DATALEN);
 452                         break;
 453                 }
 454                 rxrpc_new_skb(part);
 455
 456                 pskb_trim(part, RXRPC_JUMBO_DATALEN);
 457
 458                 if (!pskb_pull(jumbo, RXRPC_JUMBO_DATALEN))
 459                         goto protocol_error;
 460
 461                 if (skb_copy_bits(jumbo, 0, &jhdr, sizeof(jhdr)) < 0)
 462                         goto protocol_error;
 463                 if (!pskb_pull(jumbo, sizeof(jhdr)))
 464                         BUG();
 465
 466                 sp->hdr.seq     += 1;
 467                 sp->hdr.serial  += 1;
 468                 sp->hdr.flags   = jhdr.flags;
 469                 sp->hdr._rsvd   = ntohs(jhdr._rsvd);
 470
 471                 _proto("Rx DATA Jumbo %%%u", sp->hdr.serial - 1);
 472
 473                 rxrpc_fast_process_packet(call, part);
 474                 part = NULL;
 475
 476         } while (sp->hdr.flags & RXRPC_JUMBO_PACKET);
 477
 478         rxrpc_fast_process_packet(call, jumbo);
 479         _leave("");
 480         return;
 481
 482 protocol_error:
 483         _debug("protocol error");
 484         rxrpc_free_skb(part);
 485         rxrpc_free_skb(jumbo);
 486         if (rxrpc_abort_call(call, RX_PROTOCOL_ERROR, EPROTO))
 487                 rxrpc_queue_call(call);
 488         _leave("");
 489 }
 490
 491 /*
 492  * post an incoming packet to the appropriate call/socket to deal with
 493  * - must get rid of the sk_buff, either by freeing it or by queuing it
 494  */
 495 static void rxrpc_post_packet_to_call(struct rxrpc_call *call,
 496                                       struct sk_buff *skb)
 497 {
 498         struct rxrpc_skb_priv *sp;
 499
 500         _enter("%p,%p", call, skb);
 501
 502         sp = rxrpc_skb(skb);
 503
 504         _debug("extant call [%d]", call->state);
 505
 506         read_lock(&call->state_lock);
 507         switch (call->state) {
 508         case RXRPC_CALL_DEAD:
 509                 goto dead_call;
 510
 511         case RXRPC_CALL_COMPLETE:
 512                 switch (call->completion) {
 513                 case RXRPC_CALL_LOCALLY_ABORTED:
 514                         if (!test_and_set_bit(RXRPC_CALL_EV_ABORT,
 515                                               &call->events)) {
 516                                 rxrpc_queue_call(call);
 517                                 goto free_unlock;
 518                         }
 519                 default:
 520                         goto dead_call;
 521                 case RXRPC_CALL_SUCCEEDED:
 522                         if (rxrpc_conn_is_service(call->conn))
 523                                 goto dead_call;
 524                         goto resend_final_ack;
 525                 }
 526
 527         case RXRPC_CALL_CLIENT_FINAL_ACK:
 528                 goto resend_final_ack;
 529
 530         default:
 531                 break;
 532         }
 533
 534         read_unlock(&call->state_lock);
 535         rxrpc_get_call(call);
 536
 537         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
 538             sp->hdr.flags & RXRPC_JUMBO_PACKET)
 539                 rxrpc_process_jumbo_packet(call, skb);
 540         else
 541                 rxrpc_fast_process_packet(call, skb);
 542
 543         rxrpc_put_call(call);
 544         goto done;
 545
 546 resend_final_ack:
 547         _debug("final ack again");
 548         rxrpc_get_call(call);
 549         set_bit(RXRPC_CALL_EV_ACK_FINAL, &call->events);
 550         rxrpc_queue_call(call);
 551         goto free_unlock;
 552
 553 dead_call:
 554         if (sp->hdr.type != RXRPC_PACKET_TYPE_ABORT) {
 555                 skb->priority = RX_CALL_DEAD;
 556                 rxrpc_reject_packet(call->conn->params.local, skb);
 557                 goto unlock;
 558         }
 559 free_unlock:
 560         rxrpc_free_skb(skb);
 561 unlock:
 562         read_unlock(&call->state_lock);
 563 done:
 564         _leave("");
 565 }
 566
 567 /*
 568  * post connection-level events to the connection
 569  * - this includes challenges, responses, some aborts and call terminal packet
 570  *   retransmission.
 571  */
 572 static void rxrpc_post_packet_to_conn(struct rxrpc_connection *conn,
 573                                       struct sk_buff *skb)
 574 {
 575         _enter("%p,%p", conn, skb);
 576
 577         skb_queue_tail(&conn->rx_queue, skb);
 578         rxrpc_queue_conn(conn);
 579 }
 580
 581 /*
 582  * post endpoint-level events to the local endpoint
 583  * - this includes debug and version messages
 584  */
 585 static void rxrpc_post_packet_to_local(struct rxrpc_local *local,
 586                                        struct sk_buff *skb)
 587 {
 588         _enter("%p,%p", local, skb);
 589
 590         skb_queue_tail(&local->event_queue, skb);
 591         rxrpc_queue_local(local);
 592 }
 593
 594 /*
 595  * Extract the wire header from a packet and translate the byte order.
 596  */
 597 static noinline
 598 int rxrpc_extract_header(struct rxrpc_skb_priv *sp, struct sk_buff *skb)
 599 {
 600         struct rxrpc_wire_header whdr;
 601
 602         /* dig out the RxRPC connection details */
 603         if (skb_copy_bits(skb, 0, &whdr, sizeof(whdr)) < 0)
 604                 return -EBADMSG;
 605         if (!pskb_pull(skb, sizeof(whdr)))
 606                 BUG();
 607
 608         memset(sp, 0, sizeof(*sp));
 609         sp->hdr.epoch           = ntohl(whdr.epoch);
 610         sp->hdr.cid             = ntohl(whdr.cid);
 611         sp->hdr.callNumber      = ntohl(whdr.callNumber);
 612         sp->hdr.seq             = ntohl(whdr.seq);
 613         sp->hdr.serial          = ntohl(whdr.serial);
 614         sp->hdr.flags           = whdr.flags;
 615         sp->hdr.type            = whdr.type;
 616         sp->hdr.userStatus      = whdr.userStatus;
 617         sp->hdr.securityIndex   = whdr.securityIndex;
 618         sp->hdr._rsvd           = ntohs(whdr._rsvd);
 619         sp->hdr.serviceId       = ntohs(whdr.serviceId);
 620         return 0;
 621 }
 622
 623 /*
 624  * handle data received on the local endpoint
 625  * - may be called in interrupt context
 626  *
 627  * The socket is locked by the caller and this prevents the socket from being
 628  * shut down and the local endpoint from going away, thus sk_user_data will not
 629  * be cleared until this function returns.
 630  */
 631 void rxrpc_data_ready(struct sock *sk)
 632 {
 633         struct rxrpc_connection *conn;
 634         struct rxrpc_skb_priv *sp;
 635         struct rxrpc_local *local = sk->sk_user_data;
 636         struct sk_buff *skb;
 637         int ret, skew;
 638
 639         _enter("%p", sk);
 640
 641         ASSERT(!irqs_disabled());
 642
 643         skb = skb_recv_datagram(sk, 0, 1, &ret);
 644         if (!skb) {
 645                 if (ret == -EAGAIN)
 646                         return;
 647                 _debug("UDP socket error %d", ret);
 648                 return;
 649         }
 650
 651         rxrpc_new_skb(skb);
 652
 653         _net("recv skb %p", skb);
 654
 655         /* we'll probably need to checksum it (didn't call sock_recvmsg) */
 656         if (skb_checksum_complete(skb)) {
 657                 rxrpc_free_skb(skb);
 658                 __UDP_INC_STATS(&init_net, UDP_MIB_INERRORS, 0);
 659                 _leave(" [CSUM failed]");
 660                 return;
 661         }
 662
 663         __UDP_INC_STATS(&init_net, UDP_MIB_INDATAGRAMS, 0);
 664
 665         /* The socket buffer we have is owned by UDP, with UDP's data all over
 666          * it, but we really want our own data there.
 667          */
 668         skb_orphan(skb);
 669         sp = rxrpc_skb(skb);
 670
 671         _net("Rx UDP packet from %08x:%04hu",
 672              ntohl(ip_hdr(skb)->saddr), ntohs(udp_hdr(skb)->source));
 673
 674         /* dig out the RxRPC connection details */
 675         if (rxrpc_extract_header(sp, skb) < 0)
 676                 goto bad_message;
 677
 678         _net("Rx RxRPC %s ep=%x call=%x:%x",
 679              sp->hdr.flags & RXRPC_CLIENT_INITIATED ? "ToServer" : "ToClient",
 680              sp->hdr.epoch, sp->hdr.cid, sp->hdr.callNumber);
 681
 682         if (sp->hdr.type >= RXRPC_N_PACKET_TYPES ||
 683             !((RXRPC_SUPPORTED_PACKET_TYPES >> sp->hdr.type) & 1)) {
 684                 _proto("Rx Bad Packet Type %u", sp->hdr.type);
 685                 goto bad_message;
 686         }
 687
 688         if (sp->hdr.type == RXRPC_PACKET_TYPE_VERSION) {
 689                 rxrpc_post_packet_to_local(local, skb);
 690                 goto out;
 691         }
 692
 693         if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
 694             (sp->hdr.callNumber == 0 || sp->hdr.seq == 0))
 695                 goto bad_message;
 696
 697         rcu_read_lock();
 698
 699         conn = rxrpc_find_connection_rcu(local, skb);
 700         if (!conn) {
 701                 skb->priority = 0;
 702                 goto cant_route_call;
 703         }
 704
 705         /* Note the serial number skew here */
 706         skew = (int)sp->hdr.serial - (int)conn->hi_serial;
 707         if (skew >= 0) {
 708                 if (skew > 0)
 709                         conn->hi_serial = sp->hdr.serial;
 710                 skb->priority = 0;
 711         } else {
 712                 skew = -skew;
 713                 skb->priority = min(skew, 65535);
 714         }
 715
 716         if (sp->hdr.callNumber == 0) {
 717                 /* Connection-level packet */
 718                 _debug("CONN %p {%d}", conn, conn->debug_id);
 719                 rxrpc_post_packet_to_conn(conn, skb);
 720                 goto out_unlock;
 721         } else {
 722                 /* Call-bound packets are routed by connection channel. */
 723                 unsigned int channel = sp->hdr.cid & RXRPC_CHANNELMASK;
 724                 struct rxrpc_channel *chan = &conn->channels[channel];
 725                 struct rxrpc_call *call;
 726
 727                 /* Ignore really old calls */
 728                 if (sp->hdr.callNumber < chan->last_call)
 729                         goto discard_unlock;
 730
 731                 if (sp->hdr.callNumber == chan->last_call) {
 732                         /* For the previous service call, if completed
 733                          * successfully, we discard all further packets.
 734                          */
 735                         if (rxrpc_conn_is_service(conn) &&
 736                             (chan->last_type == RXRPC_PACKET_TYPE_ACK ||
 737                              sp->hdr.type == RXRPC_PACKET_TYPE_ABORT))
 738                                 goto discard_unlock;
 739
 740                         /* But otherwise we need to retransmit the final packet
 741                          * from data cached in the connection record.
 742                          */
 743                         rxrpc_post_packet_to_conn(conn, skb);
 744                         goto out_unlock;
 745                 }
 746
 747                 call = rcu_dereference(chan->call);
 748                 if (!call || atomic_read(&call->usage) == 0)
 749                         goto cant_route_call;
 750
 751                 rxrpc_post_packet_to_call(call, skb);
 752                 goto out_unlock;
 753         }
 754
 755 discard_unlock:
 756         rxrpc_free_skb(skb);
 757 out_unlock:
 758         rcu_read_unlock();
 759 out:
 760         return;
 761
 762 cant_route_call:
 763         rcu_read_unlock();
 764
 765         _debug("can't route call");
 766         if (sp->hdr.flags & RXRPC_CLIENT_INITIATED &&
 767             sp->hdr.type == RXRPC_PACKET_TYPE_DATA) {
 768                 if (sp->hdr.seq == 1) {
 769                         _debug("first packet");
 770                         skb_queue_tail(&local->accept_queue, skb);
 771                         rxrpc_queue_work(&local->processor);
 772                         _leave(" [incoming]");
 773                         return;
 774                 }
 775                 skb->priority = RX_INVALID_OPERATION;
 776         } else {
 777                 skb->priority = RX_CALL_DEAD;
 778         }
 779
 780         if (sp->hdr.type != RXRPC_PACKET_TYPE_ABORT) {
 781                 _debug("reject type %d",sp->hdr.type);
 782                 rxrpc_reject_packet(local, skb);
 783         } else {
 784                 rxrpc_free_skb(skb);
 785         }
 786         _leave(" [no call]");
 787         return;
 788
 789 bad_message:
 790         skb->priority = RX_PROTOCOL_ERROR;
 791         rxrpc_reject_packet(local, skb);
 792         _leave(" [badmsg]");
 793 }