net/rxrpc/recvmsg.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* RxRPC recvmsg() implementation
   3  *
   4  * Copyright (C) 2007 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/net.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/export.h>
  13 #include <linux/sched/signal.h>
  14
  15 #include <net/sock.h>
  16 #include <net/af_rxrpc.h>
  17 #include "ar-internal.h"
  18
  19 /*
  20  * Post a call for attention by the socket or kernel service.  Further
  21  * notifications are suppressed by putting recvmsg_link on a dummy queue.
  22  */
  23 void rxrpc_notify_socket(struct rxrpc_call *call)
  24 {
  25         struct rxrpc_sock *rx;
  26         struct sock *sk;
  27
  28         _enter("%d", call->debug_id);
  29
  30         if (!list_empty(&call->recvmsg_link))
  31                 return;
  32
  33         rcu_read_lock();
  34
  35         rx = rcu_dereference(call->socket);
  36         sk = &rx->sk;
  37         if (rx && sk->sk_state < RXRPC_CLOSE) {
  38                 if (call->notify_rx) {
  39                         spin_lock_bh(&call->notify_lock);
  40                         call->notify_rx(sk, call, call->user_call_ID);
  41                         spin_unlock_bh(&call->notify_lock);
  42                 } else {
  43                         write_lock_bh(&rx->recvmsg_lock);
  44                         if (list_empty(&call->recvmsg_link)) {
  45                                 rxrpc_get_call(call, rxrpc_call_get_notify_socket);
  46                                 list_add_tail(&call->recvmsg_link, &rx->recvmsg_q);
  47                         }
  48                         write_unlock_bh(&rx->recvmsg_lock);
  49
  50                         if (!sock_flag(sk, SOCK_DEAD)) {
  51                                 _debug("call %ps", sk->sk_data_ready);
  52                                 sk->sk_data_ready(sk);
  53                         }
  54                 }
  55         }
  56
  57         rcu_read_unlock();
  58         _leave("");
  59 }
  60
  61 /*
  62  * Transition a call to the complete state.
  63  */
  64 bool __rxrpc_set_call_completion(struct rxrpc_call *call,
  65                                  enum rxrpc_call_completion compl,
  66                                  u32 abort_code,
  67                                  int error)
  68 {
  69         if (call->state < RXRPC_CALL_COMPLETE) {
  70                 call->abort_code = abort_code;
  71                 call->error = error;
  72                 call->completion = compl;
  73                 call->state = RXRPC_CALL_COMPLETE;
  74                 trace_rxrpc_call_complete(call);
  75                 wake_up(&call->waitq);
  76                 rxrpc_notify_socket(call);
  77                 return true;
  78         }
  79         return false;
  80 }
  81
  82 bool rxrpc_set_call_completion(struct rxrpc_call *call,
  83                                enum rxrpc_call_completion compl,
  84                                u32 abort_code,
  85                                int error)
  86 {
  87         bool ret = false;
  88
  89         if (call->state < RXRPC_CALL_COMPLETE) {
  90                 write_lock_bh(&call->state_lock);
  91                 ret = __rxrpc_set_call_completion(call, compl, abort_code, error);
  92                 write_unlock_bh(&call->state_lock);
  93         }
  94         return ret;
  95 }
  96
  97 /*
  98  * Record that a call successfully completed.
  99  */
 100 bool __rxrpc_call_completed(struct rxrpc_call *call)
 101 {
 102         return __rxrpc_set_call_completion(call, RXRPC_CALL_SUCCEEDED, 0, 0);
 103 }
 104
 105 bool rxrpc_call_completed(struct rxrpc_call *call)
 106 {
 107         bool ret = false;
 108
 109         if (call->state < RXRPC_CALL_COMPLETE) {
 110                 write_lock_bh(&call->state_lock);
 111                 ret = __rxrpc_call_completed(call);
 112                 write_unlock_bh(&call->state_lock);
 113         }
 114         return ret;
 115 }
 116
 117 /*
 118  * Record that a call is locally aborted.
 119  */
 120 bool __rxrpc_abort_call(const char *why, struct rxrpc_call *call,
 121                         rxrpc_seq_t seq, u32 abort_code, int error)
 122 {
 123         trace_rxrpc_abort(call->debug_id, why, call->cid, call->call_id, seq,
 124                           abort_code, error);
 125         return __rxrpc_set_call_completion(call, RXRPC_CALL_LOCALLY_ABORTED,
 126                                            abort_code, error);
 127 }
 128
 129 bool rxrpc_abort_call(const char *why, struct rxrpc_call *call,
 130                       rxrpc_seq_t seq, u32 abort_code, int error)
 131 {
 132         bool ret;
 133
 134         write_lock_bh(&call->state_lock);
 135         ret = __rxrpc_abort_call(why, call, seq, abort_code, error);
 136         write_unlock_bh(&call->state_lock);
 137         return ret;
 138 }
 139
 140 /*
 141  * Pass a call terminating message to userspace.
 142  */
 143 static int rxrpc_recvmsg_term(struct rxrpc_call *call, struct msghdr *msg)
 144 {
 145         u32 tmp = 0;
 146         int ret;
 147
 148         switch (call->completion) {
 149         case RXRPC_CALL_SUCCEEDED:
 150                 ret = 0;
 151                 if (rxrpc_is_service_call(call))
 152                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &tmp);
 153                 break;
 154         case RXRPC_CALL_REMOTELY_ABORTED:
 155                 tmp = call->abort_code;
 156                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
 157                 break;
 158         case RXRPC_CALL_LOCALLY_ABORTED:
 159                 tmp = call->abort_code;
 160                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
 161                 break;
 162         case RXRPC_CALL_NETWORK_ERROR:
 163                 tmp = -call->error;
 164                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &tmp);
 165                 break;
 166         case RXRPC_CALL_LOCAL_ERROR:
 167                 tmp = -call->error;
 168                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4, &tmp);
 169                 break;
 170         default:
 171                 pr_err("Invalid terminal call state %u\n", call->state);
 172                 BUG();
 173                 break;
 174         }
 175
 176         trace_rxrpc_recvdata(call, rxrpc_recvmsg_terminal,
 177                              lower_32_bits(atomic64_read(&call->ackr_window)) - 1,
 178                              call->rx_pkt_offset, call->rx_pkt_len, ret);
 179         return ret;
 180 }
 181
 182 /*
 183  * End the packet reception phase.
 184  */
 185 static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
 186 {
 187         rxrpc_seq_t whigh = READ_ONCE(call->rx_highest_seq);
 188
 189         _enter("%d,%s", call->debug_id, rxrpc_call_states[call->state]);
 190
 191         trace_rxrpc_receive(call, rxrpc_receive_end, 0, whigh);
 192
 193         if (call->state == RXRPC_CALL_CLIENT_RECV_REPLY)
 194                 rxrpc_propose_delay_ACK(call, serial, rxrpc_propose_ack_terminal_ack);
 195
 196         write_lock_bh(&call->state_lock);
 197
 198         switch (call->state) {
 199         case RXRPC_CALL_CLIENT_RECV_REPLY:
 200                 __rxrpc_call_completed(call);
 201                 write_unlock_bh(&call->state_lock);
 202                 break;
 203
 204         case RXRPC_CALL_SERVER_RECV_REQUEST:
 205                 call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
 206                 call->expect_req_by = jiffies + MAX_JIFFY_OFFSET;
 207                 write_unlock_bh(&call->state_lock);
 208                 rxrpc_propose_delay_ACK(call, serial,
 209                                         rxrpc_propose_ack_processing_op);
 210                 break;
 211         default:
 212                 write_unlock_bh(&call->state_lock);
 213                 break;
 214         }
 215 }
 216
 217 /*
 218  * Discard a packet we've used up and advance the Rx window by one.
 219  */
 220 static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
 221 {
 222         struct rxrpc_skb_priv *sp;
 223         struct sk_buff *skb;
 224         rxrpc_serial_t serial;
 225         rxrpc_seq_t old_consumed = call->rx_consumed, tseq;
 226         bool last;
 227         int acked;
 228
 229         _enter("%d", call->debug_id);
 230
 231         skb = skb_dequeue(&call->recvmsg_queue);
 232         rxrpc_see_skb(skb, rxrpc_skb_see_rotate);
 233
 234         sp = rxrpc_skb(skb);
 235         tseq   = sp->hdr.seq;
 236         serial = sp->hdr.serial;
 237         last   = sp->hdr.flags & RXRPC_LAST_PACKET;
 238
 239         /* Barrier against rxrpc_input_data(). */
 240         if (after(tseq, call->rx_consumed))
 241                 smp_store_release(&call->rx_consumed, tseq);
 242
 243         rxrpc_free_skb(skb, rxrpc_skb_put_rotate);
 244
 245         trace_rxrpc_receive(call, last ? rxrpc_receive_rotate_last : rxrpc_receive_rotate,
 246                             serial, call->rx_consumed);
 247         if (last) {
 248                 rxrpc_end_rx_phase(call, serial);
 249                 return;
 250         }
 251
 252         /* Check to see if there's an ACK that needs sending. */
 253         acked = atomic_add_return(call->rx_consumed - old_consumed,
 254                                   &call->ackr_nr_consumed);
 255         if (acked > 2 &&
 256             !test_and_set_bit(RXRPC_CALL_IDLE_ACK_PENDING, &call->flags)) {
 257                 rxrpc_send_ACK(call, RXRPC_ACK_IDLE, serial,
 258                                rxrpc_propose_ack_rotate_rx);
 259                 rxrpc_transmit_ack_packets(call->peer->local);
 260         }
 261 }
 262
 263 /*
 264  * Decrypt and verify a DATA packet.
 265  */
 266 static int rxrpc_verify_data(struct rxrpc_call *call, struct sk_buff *skb)
 267 {
 268         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 269
 270         if (sp->flags & RXRPC_RX_VERIFIED)
 271                 return 0;
 272         return call->security->verify_packet(call, skb);
 273 }
 274
 275 /*
 276  * Deliver messages to a call.  This keeps processing packets until the buffer
 277  * is filled and we find either more DATA (returns 0) or the end of the DATA
 278  * (returns 1).  If more packets are required, it returns -EAGAIN.
 279  */
 280 static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 281                               struct msghdr *msg, struct iov_iter *iter,
 282                               size_t len, int flags, size_t *_offset)
 283 {
 284         struct rxrpc_skb_priv *sp;
 285         struct sk_buff *skb;
 286         rxrpc_seq_t seq = 0;
 287         size_t remain;
 288         unsigned int rx_pkt_offset, rx_pkt_len;
 289         int copy, ret = -EAGAIN, ret2;
 290
 291         rx_pkt_offset = call->rx_pkt_offset;
 292         rx_pkt_len = call->rx_pkt_len;
 293
 294         if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
 295                 seq = lower_32_bits(atomic64_read(&call->ackr_window)) - 1;
 296                 ret = 1;
 297                 goto done;
 298         }
 299
 300         /* No one else can be removing stuff from the queue, so we shouldn't
 301          * need the Rx lock to walk it.
 302          */
 303         skb = skb_peek(&call->recvmsg_queue);
 304         while (skb) {
 305                 rxrpc_see_skb(skb, rxrpc_skb_see_recvmsg);
 306                 sp = rxrpc_skb(skb);
 307                 seq = sp->hdr.seq;
 308
 309                 if (!(flags & MSG_PEEK))
 310                         trace_rxrpc_receive(call, rxrpc_receive_front,
 311                                             sp->hdr.serial, seq);
 312
 313                 if (msg)
 314                         sock_recv_timestamp(msg, sock->sk, skb);
 315
 316                 if (rx_pkt_offset == 0) {
 317                         ret2 = rxrpc_verify_data(call, skb);
 318                         rx_pkt_offset = sp->offset;
 319                         rx_pkt_len = sp->len;
 320                         trace_rxrpc_recvdata(call, rxrpc_recvmsg_next, seq,
 321                                              rx_pkt_offset, rx_pkt_len, ret2);
 322                         if (ret2 < 0) {
 323                                 ret = ret2;
 324                                 goto out;
 325                         }
 326                         rxrpc_transmit_ack_packets(call->peer->local);
 327                 } else {
 328                         trace_rxrpc_recvdata(call, rxrpc_recvmsg_cont, seq,
 329                                              rx_pkt_offset, rx_pkt_len, 0);
 330                 }
 331
 332                 /* We have to handle short, empty and used-up DATA packets. */
 333                 remain = len - *_offset;
 334                 copy = rx_pkt_len;
 335                 if (copy > remain)
 336                         copy = remain;
 337                 if (copy > 0) {
 338                         ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
 339                                                       copy);
 340                         if (ret2 < 0) {
 341                                 ret = ret2;
 342                                 goto out;
 343                         }
 344
 345                         /* handle piecemeal consumption of data packets */
 346                         rx_pkt_offset += copy;
 347                         rx_pkt_len -= copy;
 348                         *_offset += copy;
 349                 }
 350
 351                 if (rx_pkt_len > 0) {
 352                         trace_rxrpc_recvdata(call, rxrpc_recvmsg_full, seq,
 353                                              rx_pkt_offset, rx_pkt_len, 0);
 354                         ASSERTCMP(*_offset, ==, len);
 355                         ret = 0;
 356                         break;
 357                 }
 358
 359                 /* The whole packet has been transferred. */
 360                 if (sp->hdr.flags & RXRPC_LAST_PACKET)
 361                         ret = 1;
 362                 rx_pkt_offset = 0;
 363                 rx_pkt_len = 0;
 364
 365                 skb = skb_peek_next(skb, &call->recvmsg_queue);
 366
 367                 if (!(flags & MSG_PEEK))
 368                         rxrpc_rotate_rx_window(call);
 369         }
 370
 371 out:
 372         if (!(flags & MSG_PEEK)) {
 373                 call->rx_pkt_offset = rx_pkt_offset;
 374                 call->rx_pkt_len = rx_pkt_len;
 375         }
 376 done:
 377         trace_rxrpc_recvdata(call, rxrpc_recvmsg_data_return, seq,
 378                              rx_pkt_offset, rx_pkt_len, ret);
 379         if (ret == -EAGAIN)
 380                 set_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags);
 381         return ret;
 382 }
 383
 384 /*
 385  * Receive a message from an RxRPC socket
 386  * - we need to be careful about two or more threads calling recvmsg
 387  *   simultaneously
 388  */
 389 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 390                   int flags)
 391 {
 392         struct rxrpc_call *call;
 393         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 394         struct list_head *l;
 395         size_t copied = 0;
 396         long timeo;
 397         int ret;
 398
 399         DEFINE_WAIT(wait);
 400
 401         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0);
 402
 403         if (flags & (MSG_OOB | MSG_TRUNC))
 404                 return -EOPNOTSUPP;
 405
 406         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
 407
 408 try_again:
 409         lock_sock(&rx->sk);
 410
 411         /* Return immediately if a client socket has no outstanding calls */
 412         if (RB_EMPTY_ROOT(&rx->calls) &&
 413             list_empty(&rx->recvmsg_q) &&
 414             rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
 415                 release_sock(&rx->sk);
 416                 return -EAGAIN;
 417         }
 418
 419         if (list_empty(&rx->recvmsg_q)) {
 420                 ret = -EWOULDBLOCK;
 421                 if (timeo == 0) {
 422                         call = NULL;
 423                         goto error_no_call;
 424                 }
 425
 426                 release_sock(&rx->sk);
 427
 428                 /* Wait for something to happen */
 429                 prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
 430                                           TASK_INTERRUPTIBLE);
 431                 ret = sock_error(&rx->sk);
 432                 if (ret)
 433                         goto wait_error;
 434
 435                 if (list_empty(&rx->recvmsg_q)) {
 436                         if (signal_pending(current))
 437                                 goto wait_interrupted;
 438                         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait, 0);
 439                         timeo = schedule_timeout(timeo);
 440                 }
 441                 finish_wait(sk_sleep(&rx->sk), &wait);
 442                 goto try_again;
 443         }
 444
 445         /* Find the next call and dequeue it if we're not just peeking.  If we
 446          * do dequeue it, that comes with a ref that we will need to release.
 447          */
 448         write_lock_bh(&rx->recvmsg_lock);
 449         l = rx->recvmsg_q.next;
 450         call = list_entry(l, struct rxrpc_call, recvmsg_link);
 451         if (!(flags & MSG_PEEK))
 452                 list_del_init(&call->recvmsg_link);
 453         else
 454                 rxrpc_get_call(call, rxrpc_call_get_recvmsg);
 455         write_unlock_bh(&rx->recvmsg_lock);
 456
 457         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0);
 458
 459         /* We're going to drop the socket lock, so we need to lock the call
 460          * against interference by sendmsg.
 461          */
 462         if (!mutex_trylock(&call->user_mutex)) {
 463                 ret = -EWOULDBLOCK;
 464                 if (flags & MSG_DONTWAIT)
 465                         goto error_requeue_call;
 466                 ret = -ERESTARTSYS;
 467                 if (mutex_lock_interruptible(&call->user_mutex) < 0)
 468                         goto error_requeue_call;
 469         }
 470
 471         release_sock(&rx->sk);
 472
 473         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
 474                 BUG();
 475
 476         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
 477                 if (flags & MSG_CMSG_COMPAT) {
 478                         unsigned int id32 = call->user_call_ID;
 479
 480                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 481                                        sizeof(unsigned int), &id32);
 482                 } else {
 483                         unsigned long idl = call->user_call_ID;
 484
 485                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 486                                        sizeof(unsigned long), &idl);
 487                 }
 488                 if (ret < 0)
 489                         goto error_unlock_call;
 490         }
 491
 492         if (msg->msg_name && call->peer) {
 493                 struct sockaddr_rxrpc *srx = msg->msg_name;
 494                 size_t len = sizeof(call->peer->srx);
 495
 496                 memcpy(msg->msg_name, &call->peer->srx, len);
 497                 srx->srx_service = call->service_id;
 498                 msg->msg_namelen = len;
 499         }
 500
 501         switch (READ_ONCE(call->state)) {
 502         case RXRPC_CALL_CLIENT_RECV_REPLY:
 503         case RXRPC_CALL_SERVER_RECV_REQUEST:
 504         case RXRPC_CALL_SERVER_ACK_REQUEST:
 505                 ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
 506                                          flags, &copied);
 507                 if (ret == -EAGAIN)
 508                         ret = 0;
 509
 510                 rxrpc_transmit_ack_packets(call->peer->local);
 511                 if (!skb_queue_empty(&call->recvmsg_queue))
 512                         rxrpc_notify_socket(call);
 513                 break;
 514         default:
 515                 ret = 0;
 516                 break;
 517         }
 518
 519         if (ret < 0)
 520                 goto error_unlock_call;
 521
 522         if (call->state == RXRPC_CALL_COMPLETE) {
 523                 ret = rxrpc_recvmsg_term(call, msg);
 524                 if (ret < 0)
 525                         goto error_unlock_call;
 526                 if (!(flags & MSG_PEEK))
 527                         rxrpc_release_call(rx, call);
 528                 msg->msg_flags |= MSG_EOR;
 529                 ret = 1;
 530         }
 531
 532         if (ret == 0)
 533                 msg->msg_flags |= MSG_MORE;
 534         else
 535                 msg->msg_flags &= ~MSG_MORE;
 536         ret = copied;
 537
 538 error_unlock_call:
 539         mutex_unlock(&call->user_mutex);
 540         rxrpc_put_call(call, rxrpc_call_put_recvmsg);
 541         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, ret);
 542         return ret;
 543
 544 error_requeue_call:
 545         if (!(flags & MSG_PEEK)) {
 546                 write_lock_bh(&rx->recvmsg_lock);
 547                 list_add(&call->recvmsg_link, &rx->recvmsg_q);
 548                 write_unlock_bh(&rx->recvmsg_lock);
 549                 trace_rxrpc_recvmsg(call, rxrpc_recvmsg_requeue, 0);
 550         } else {
 551                 rxrpc_put_call(call, rxrpc_call_put_recvmsg);
 552         }
 553 error_no_call:
 554         release_sock(&rx->sk);
 555 error_trace:
 556         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, ret);
 557         return ret;
 558
 559 wait_interrupted:
 560         ret = sock_intr_errno(timeo);
 561 wait_error:
 562         finish_wait(sk_sleep(&rx->sk), &wait);
 563         call = NULL;
 564         goto error_trace;
 565 }
 566
 567 /**
 568  * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 569  * @sock: The socket that the call exists on
 570  * @call: The call to send data through
 571  * @iter: The buffer to receive into
 572  * @_len: The amount of data we want to receive (decreased on return)
 573  * @want_more: True if more data is expected to be read
 574  * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 575  * @_service: Where to store the actual service ID (may be upgraded)
 576  *
 577  * Allow a kernel service to receive data and pick up information about the
 578  * state of a call.  Returns 0 if got what was asked for and there's more
 579  * available, 1 if we got what was asked for and we're at the end of the data
 580  * and -EAGAIN if we need more data.
 581  *
 582  * Note that we may return -EAGAIN to drain empty packets at the end of the
 583  * data, even if we've already copied over the requested data.
 584  *
 585  * *_abort should also be initialised to 0.
 586  */
 587 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 588                            struct iov_iter *iter, size_t *_len,
 589                            bool want_more, u32 *_abort, u16 *_service)
 590 {
 591         size_t offset = 0;
 592         int ret;
 593
 594         _enter("{%d,%s},%zu,%d",
 595                call->debug_id, rxrpc_call_states[call->state],
 596                *_len, want_more);
 597
 598         ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_SECURING);
 599
 600         mutex_lock(&call->user_mutex);
 601
 602         switch (READ_ONCE(call->state)) {
 603         case RXRPC_CALL_CLIENT_RECV_REPLY:
 604         case RXRPC_CALL_SERVER_RECV_REQUEST:
 605         case RXRPC_CALL_SERVER_ACK_REQUEST:
 606                 ret = rxrpc_recvmsg_data(sock, call, NULL, iter,
 607                                          *_len, 0, &offset);
 608                 *_len -= offset;
 609                 if (ret < 0)
 610                         goto out;
 611
 612                 /* We can only reach here with a partially full buffer if we
 613                  * have reached the end of the data.  We must otherwise have a
 614                  * full buffer or have been given -EAGAIN.
 615                  */
 616                 if (ret == 1) {
 617                         if (iov_iter_count(iter) > 0)
 618                                 goto short_data;
 619                         if (!want_more)
 620                                 goto read_phase_complete;
 621                         ret = 0;
 622                         goto out;
 623                 }
 624
 625                 if (!want_more)
 626                         goto excess_data;
 627                 goto out;
 628
 629         case RXRPC_CALL_COMPLETE:
 630                 goto call_complete;
 631
 632         default:
 633                 ret = -EINPROGRESS;
 634                 goto out;
 635         }
 636
 637 read_phase_complete:
 638         ret = 1;
 639 out:
 640         rxrpc_transmit_ack_packets(call->peer->local);
 641         if (_service)
 642                 *_service = call->service_id;
 643         mutex_unlock(&call->user_mutex);
 644         _leave(" = %d [%zu,%d]", ret, iov_iter_count(iter), *_abort);
 645         return ret;
 646
 647 short_data:
 648         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("short_data"));
 649         ret = -EBADMSG;
 650         goto out;
 651 excess_data:
 652         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("excess_data"));
 653         ret = -EMSGSIZE;
 654         goto out;
 655 call_complete:
 656         *_abort = call->abort_code;
 657         ret = call->error;
 658         if (call->completion == RXRPC_CALL_SUCCEEDED) {
 659                 ret = 1;
 660                 if (iov_iter_count(iter) > 0)
 661                         ret = -ECONNRESET;
 662         }
 663         goto out;
 664 }
 665 EXPORT_SYMBOL(rxrpc_kernel_recv_data);