net/rxrpc/recvmsg.c

   1 /* RxRPC recvmsg() implementation
   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/net.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/export.h>
  17 #include <net/sock.h>
  18 #include <net/af_rxrpc.h>
  19 #include "ar-internal.h"
  20
  21 /*
  22  * Post a call for attention by the socket or kernel service.  Further
  23  * notifications are suppressed by putting recvmsg_link on a dummy queue.
  24  */
  25 void rxrpc_notify_socket(struct rxrpc_call *call)
  26 {
  27         struct rxrpc_sock *rx;
  28         struct sock *sk;
  29
  30         _enter("%d", call->debug_id);
  31
  32         if (!list_empty(&call->recvmsg_link))
  33                 return;
  34
  35         rcu_read_lock();
  36
  37         rx = rcu_dereference(call->socket);
  38         sk = &rx->sk;
  39         if (rx && sk->sk_state < RXRPC_CLOSE) {
  40                 if (call->notify_rx) {
  41                         call->notify_rx(sk, call, call->user_call_ID);
  42                 } else {
  43                         write_lock_bh(&rx->recvmsg_lock);
  44                         if (list_empty(&call->recvmsg_link)) {
  45                                 rxrpc_get_call(call, rxrpc_call_got);
  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  * Pass a call terminating message to userspace.
  63  */
  64 static int rxrpc_recvmsg_term(struct rxrpc_call *call, struct msghdr *msg)
  65 {
  66         u32 tmp = 0;
  67         int ret;
  68
  69         switch (call->completion) {
  70         case RXRPC_CALL_SUCCEEDED:
  71                 ret = 0;
  72                 if (rxrpc_is_service_call(call))
  73                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &tmp);
  74                 break;
  75         case RXRPC_CALL_REMOTELY_ABORTED:
  76                 tmp = call->abort_code;
  77                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
  78                 break;
  79         case RXRPC_CALL_LOCALLY_ABORTED:
  80                 tmp = call->abort_code;
  81                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
  82                 break;
  83         case RXRPC_CALL_NETWORK_ERROR:
  84                 tmp = call->error;
  85                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &tmp);
  86                 break;
  87         case RXRPC_CALL_LOCAL_ERROR:
  88                 tmp = call->error;
  89                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4, &tmp);
  90                 break;
  91         default:
  92                 pr_err("Invalid terminal call state %u\n", call->state);
  93                 BUG();
  94                 break;
  95         }
  96
  97         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_terminal, call->rx_hard_ack,
  98                             call->rx_pkt_offset, call->rx_pkt_len, ret);
  99         return ret;
 100 }
 101
 102 /*
 103  * Pass back notification of a new call.  The call is added to the
 104  * to-be-accepted list.  This means that the next call to be accepted might not
 105  * be the last call seen awaiting acceptance, but unless we leave this on the
 106  * front of the queue and block all other messages until someone gives us a
 107  * user_ID for it, there's not a lot we can do.
 108  */
 109 static int rxrpc_recvmsg_new_call(struct rxrpc_sock *rx,
 110                                   struct rxrpc_call *call,
 111                                   struct msghdr *msg, int flags)
 112 {
 113         int tmp = 0, ret;
 114
 115         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NEW_CALL, 0, &tmp);
 116
 117         if (ret == 0 && !(flags & MSG_PEEK)) {
 118                 _debug("to be accepted");
 119                 write_lock_bh(&rx->recvmsg_lock);
 120                 list_del_init(&call->recvmsg_link);
 121                 write_unlock_bh(&rx->recvmsg_lock);
 122
 123                 rxrpc_get_call(call, rxrpc_call_got);
 124                 write_lock(&rx->call_lock);
 125                 list_add_tail(&call->accept_link, &rx->to_be_accepted);
 126                 write_unlock(&rx->call_lock);
 127         }
 128
 129         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_to_be_accepted, 1, 0, 0, ret);
 130         return ret;
 131 }
 132
 133 /*
 134  * End the packet reception phase.
 135  */
 136 static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
 137 {
 138         _enter("%d,%s", call->debug_id, rxrpc_call_states[call->state]);
 139
 140         trace_rxrpc_receive(call, rxrpc_receive_end, 0, call->rx_top);
 141         ASSERTCMP(call->rx_hard_ack, ==, call->rx_top);
 142
 143         if (call->state == RXRPC_CALL_CLIENT_RECV_REPLY) {
 144                 rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, 0, serial, true, false,
 145                                   rxrpc_propose_ack_terminal_ack);
 146                 rxrpc_send_ack_packet(call, false);
 147         }
 148
 149         write_lock_bh(&call->state_lock);
 150
 151         switch (call->state) {
 152         case RXRPC_CALL_CLIENT_RECV_REPLY:
 153                 __rxrpc_call_completed(call);
 154                 break;
 155
 156         case RXRPC_CALL_SERVER_RECV_REQUEST:
 157                 call->tx_phase = true;
 158                 call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
 159                 break;
 160         default:
 161                 break;
 162         }
 163
 164         write_unlock_bh(&call->state_lock);
 165 }
 166
 167 /*
 168  * Discard a packet we've used up and advance the Rx window by one.
 169  */
 170 static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
 171 {
 172         struct rxrpc_skb_priv *sp;
 173         struct sk_buff *skb;
 174         rxrpc_serial_t serial;
 175         rxrpc_seq_t hard_ack, top;
 176         u8 flags;
 177         int ix;
 178
 179         _enter("%d", call->debug_id);
 180
 181         hard_ack = call->rx_hard_ack;
 182         top = smp_load_acquire(&call->rx_top);
 183         ASSERT(before(hard_ack, top));
 184
 185         hard_ack++;
 186         ix = hard_ack & RXRPC_RXTX_BUFF_MASK;
 187         skb = call->rxtx_buffer[ix];
 188         rxrpc_see_skb(skb, rxrpc_skb_rx_rotated);
 189         sp = rxrpc_skb(skb);
 190         flags = sp->hdr.flags;
 191         serial = sp->hdr.serial;
 192         if (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO)
 193                 serial += (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO) - 1;
 194
 195         call->rxtx_buffer[ix] = NULL;
 196         call->rxtx_annotations[ix] = 0;
 197         /* Barrier against rxrpc_input_data(). */
 198         smp_store_release(&call->rx_hard_ack, hard_ack);
 199
 200         rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
 201
 202         _debug("%u,%u,%02x", hard_ack, top, flags);
 203         trace_rxrpc_receive(call, rxrpc_receive_rotate, serial, hard_ack);
 204         if (flags & RXRPC_LAST_PACKET) {
 205                 rxrpc_end_rx_phase(call, serial);
 206         } else {
 207                 /* Check to see if there's an ACK that needs sending. */
 208                 if (after_eq(hard_ack, call->ackr_consumed + 2) ||
 209                     after_eq(top, call->ackr_seen + 2) ||
 210                     (hard_ack == top && after(hard_ack, call->ackr_consumed)))
 211                         rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, 0, serial,
 212                                           true, false,
 213                                           rxrpc_propose_ack_rotate_rx);
 214                 if (call->ackr_reason)
 215                         rxrpc_send_ack_packet(call, false);
 216         }
 217 }
 218
 219 /*
 220  * Decrypt and verify a (sub)packet.  The packet's length may be changed due to
 221  * padding, but if this is the case, the packet length will be resident in the
 222  * socket buffer.  Note that we can't modify the master skb info as the skb may
 223  * be the home to multiple subpackets.
 224  */
 225 static int rxrpc_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
 226                                u8 annotation,
 227                                unsigned int offset, unsigned int len)
 228 {
 229         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 230         rxrpc_seq_t seq = sp->hdr.seq;
 231         u16 cksum = sp->hdr.cksum;
 232
 233         _enter("");
 234
 235         /* For all but the head jumbo subpacket, the security checksum is in a
 236          * jumbo header immediately prior to the data.
 237          */
 238         if ((annotation & RXRPC_RX_ANNO_JUMBO) > 1) {
 239                 __be16 tmp;
 240                 if (skb_copy_bits(skb, offset - 2, &tmp, 2) < 0)
 241                         BUG();
 242                 cksum = ntohs(tmp);
 243                 seq += (annotation & RXRPC_RX_ANNO_JUMBO) - 1;
 244         }
 245
 246         return call->conn->security->verify_packet(call, skb, offset, len,
 247                                                    seq, cksum);
 248 }
 249
 250 /*
 251  * Locate the data within a packet.  This is complicated by:
 252  *
 253  * (1) An skb may contain a jumbo packet - so we have to find the appropriate
 254  *     subpacket.
 255  *
 256  * (2) The (sub)packets may be encrypted and, if so, the encrypted portion
 257  *     contains an extra header which includes the true length of the data,
 258  *     excluding any encrypted padding.
 259  */
 260 static int rxrpc_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
 261                              u8 *_annotation,
 262                              unsigned int *_offset, unsigned int *_len)
 263 {
 264         unsigned int offset = sizeof(struct rxrpc_wire_header);
 265         unsigned int len = *_len;
 266         int ret;
 267         u8 annotation = *_annotation;
 268
 269         /* Locate the subpacket */
 270         len = skb->len - offset;
 271         if ((annotation & RXRPC_RX_ANNO_JUMBO) > 0) {
 272                 offset += (((annotation & RXRPC_RX_ANNO_JUMBO) - 1) *
 273                            RXRPC_JUMBO_SUBPKTLEN);
 274                 len = (annotation & RXRPC_RX_ANNO_JLAST) ?
 275                         skb->len - offset : RXRPC_JUMBO_SUBPKTLEN;
 276         }
 277
 278         if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
 279                 ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
 280                 if (ret < 0)
 281                         return ret;
 282                 *_annotation |= RXRPC_RX_ANNO_VERIFIED;
 283         }
 284
 285         *_offset = offset;
 286         *_len = len;
 287         call->conn->security->locate_data(call, skb, _offset, _len);
 288         return 0;
 289 }
 290
 291 /*
 292  * Deliver messages to a call.  This keeps processing packets until the buffer
 293  * is filled and we find either more DATA (returns 0) or the end of the DATA
 294  * (returns 1).  If more packets are required, it returns -EAGAIN.
 295  */
 296 static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 297                               struct msghdr *msg, struct iov_iter *iter,
 298                               size_t len, int flags, size_t *_offset)
 299 {
 300         struct rxrpc_skb_priv *sp;
 301         struct sk_buff *skb;
 302         rxrpc_seq_t hard_ack, top, seq;
 303         size_t remain;
 304         bool last;
 305         unsigned int rx_pkt_offset, rx_pkt_len;
 306         int ix, copy, ret = -EAGAIN, ret2;
 307
 308         rx_pkt_offset = call->rx_pkt_offset;
 309         rx_pkt_len = call->rx_pkt_len;
 310
 311         if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
 312                 seq = call->rx_hard_ack;
 313                 ret = 1;
 314                 goto done;
 315         }
 316
 317         /* Barriers against rxrpc_input_data(). */
 318         hard_ack = call->rx_hard_ack;
 319         top = smp_load_acquire(&call->rx_top);
 320         for (seq = hard_ack + 1; before_eq(seq, top); seq++) {
 321                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 322                 skb = call->rxtx_buffer[ix];
 323                 if (!skb) {
 324                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq,
 325                                             rx_pkt_offset, rx_pkt_len, 0);
 326                         break;
 327                 }
 328                 smp_rmb();
 329                 rxrpc_see_skb(skb, rxrpc_skb_rx_seen);
 330                 sp = rxrpc_skb(skb);
 331
 332                 if (!(flags & MSG_PEEK))
 333                         trace_rxrpc_receive(call, rxrpc_receive_front,
 334                                             sp->hdr.serial, seq);
 335
 336                 if (msg)
 337                         sock_recv_timestamp(msg, sock->sk, skb);
 338
 339                 if (rx_pkt_offset == 0) {
 340                         ret2 = rxrpc_locate_data(call, skb,
 341                                                  &call->rxtx_annotations[ix],
 342                                                  &rx_pkt_offset, &rx_pkt_len);
 343                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq,
 344                                             rx_pkt_offset, rx_pkt_len, ret2);
 345                         if (ret2 < 0) {
 346                                 ret = ret2;
 347                                 goto out;
 348                         }
 349                 } else {
 350                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq,
 351                                             rx_pkt_offset, rx_pkt_len, 0);
 352                 }
 353
 354                 /* We have to handle short, empty and used-up DATA packets. */
 355                 remain = len - *_offset;
 356                 copy = rx_pkt_len;
 357                 if (copy > remain)
 358                         copy = remain;
 359                 if (copy > 0) {
 360                         ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
 361                                                       copy);
 362                         if (ret2 < 0) {
 363                                 ret = ret2;
 364                                 goto out;
 365                         }
 366
 367                         /* handle piecemeal consumption of data packets */
 368                         rx_pkt_offset += copy;
 369                         rx_pkt_len -= copy;
 370                         *_offset += copy;
 371                 }
 372
 373                 if (rx_pkt_len > 0) {
 374                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq,
 375                                             rx_pkt_offset, rx_pkt_len, 0);
 376                         ASSERTCMP(*_offset, ==, len);
 377                         ret = 0;
 378                         break;
 379                 }
 380
 381                 /* The whole packet has been transferred. */
 382                 last = sp->hdr.flags & RXRPC_LAST_PACKET;
 383                 if (!(flags & MSG_PEEK))
 384                         rxrpc_rotate_rx_window(call);
 385                 rx_pkt_offset = 0;
 386                 rx_pkt_len = 0;
 387
 388                 if (last) {
 389                         ASSERTCMP(seq, ==, READ_ONCE(call->rx_top));
 390                         ret = 1;
 391                         goto out;
 392                 }
 393         }
 394
 395 out:
 396         if (!(flags & MSG_PEEK)) {
 397                 call->rx_pkt_offset = rx_pkt_offset;
 398                 call->rx_pkt_len = rx_pkt_len;
 399         }
 400 done:
 401         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_data_return, seq,
 402                             rx_pkt_offset, rx_pkt_len, ret);
 403         return ret;
 404 }
 405
 406 /*
 407  * Receive a message from an RxRPC socket
 408  * - we need to be careful about two or more threads calling recvmsg
 409  *   simultaneously
 410  */
 411 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 412                   int flags)
 413 {
 414         struct rxrpc_call *call;
 415         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 416         struct list_head *l;
 417         size_t copied = 0;
 418         long timeo;
 419         int ret;
 420
 421         DEFINE_WAIT(wait);
 422
 423         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0, 0, 0, 0);
 424
 425         if (flags & (MSG_OOB | MSG_TRUNC))
 426                 return -EOPNOTSUPP;
 427
 428         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
 429
 430 try_again:
 431         lock_sock(&rx->sk);
 432
 433         /* Return immediately if a client socket has no outstanding calls */
 434         if (RB_EMPTY_ROOT(&rx->calls) &&
 435             list_empty(&rx->recvmsg_q) &&
 436             rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
 437                 release_sock(&rx->sk);
 438                 return -ENODATA;
 439         }
 440
 441         if (list_empty(&rx->recvmsg_q)) {
 442                 ret = -EWOULDBLOCK;
 443                 if (timeo == 0) {
 444                         call = NULL;
 445                         goto error_no_call;
 446                 }
 447
 448                 release_sock(&rx->sk);
 449
 450                 /* Wait for something to happen */
 451                 prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
 452                                           TASK_INTERRUPTIBLE);
 453                 ret = sock_error(&rx->sk);
 454                 if (ret)
 455                         goto wait_error;
 456
 457                 if (list_empty(&rx->recvmsg_q)) {
 458                         if (signal_pending(current))
 459                                 goto wait_interrupted;
 460                         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait,
 461                                             0, 0, 0, 0);
 462                         timeo = schedule_timeout(timeo);
 463                 }
 464                 finish_wait(sk_sleep(&rx->sk), &wait);
 465                 goto try_again;
 466         }
 467
 468         /* Find the next call and dequeue it if we're not just peeking.  If we
 469          * do dequeue it, that comes with a ref that we will need to release.
 470          */
 471         write_lock_bh(&rx->recvmsg_lock);
 472         l = rx->recvmsg_q.next;
 473         call = list_entry(l, struct rxrpc_call, recvmsg_link);
 474         if (!(flags & MSG_PEEK))
 475                 list_del_init(&call->recvmsg_link);
 476         else
 477                 rxrpc_get_call(call, rxrpc_call_got);
 478         write_unlock_bh(&rx->recvmsg_lock);
 479
 480         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0, 0, 0, 0);
 481
 482         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
 483                 BUG();
 484
 485         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
 486                 if (flags & MSG_CMSG_COMPAT) {
 487                         unsigned int id32 = call->user_call_ID;
 488
 489                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 490                                        sizeof(unsigned int), &id32);
 491                 } else {
 492                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 493                                        sizeof(unsigned long),
 494                                        &call->user_call_ID);
 495                 }
 496                 if (ret < 0)
 497                         goto error;
 498         }
 499
 500         if (msg->msg_name) {
 501                 size_t len = sizeof(call->conn->params.peer->srx);
 502                 memcpy(msg->msg_name, &call->conn->params.peer->srx, len);
 503                 msg->msg_namelen = len;
 504         }
 505
 506         switch (call->state) {
 507         case RXRPC_CALL_SERVER_ACCEPTING:
 508                 ret = rxrpc_recvmsg_new_call(rx, call, msg, flags);
 509                 break;
 510         case RXRPC_CALL_CLIENT_RECV_REPLY:
 511         case RXRPC_CALL_SERVER_RECV_REQUEST:
 512         case RXRPC_CALL_SERVER_ACK_REQUEST:
 513                 ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
 514                                          flags, &copied);
 515                 if (ret == -EAGAIN)
 516                         ret = 0;
 517
 518                 if (after(call->rx_top, call->rx_hard_ack) &&
 519                     call->rxtx_buffer[(call->rx_hard_ack + 1) & RXRPC_RXTX_BUFF_MASK])
 520                         rxrpc_notify_socket(call);
 521                 break;
 522         default:
 523                 ret = 0;
 524                 break;
 525         }
 526
 527         if (ret < 0)
 528                 goto error;
 529
 530         if (call->state == RXRPC_CALL_COMPLETE) {
 531                 ret = rxrpc_recvmsg_term(call, msg);
 532                 if (ret < 0)
 533                         goto error;
 534                 if (!(flags & MSG_PEEK))
 535                         rxrpc_release_call(rx, call);
 536                 msg->msg_flags |= MSG_EOR;
 537                 ret = 1;
 538         }
 539
 540         if (ret == 0)
 541                 msg->msg_flags |= MSG_MORE;
 542         else
 543                 msg->msg_flags &= ~MSG_MORE;
 544         ret = copied;
 545
 546 error:
 547         rxrpc_put_call(call, rxrpc_call_put);
 548 error_no_call:
 549         release_sock(&rx->sk);
 550         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 551         return ret;
 552
 553 wait_interrupted:
 554         ret = sock_intr_errno(timeo);
 555 wait_error:
 556         finish_wait(sk_sleep(&rx->sk), &wait);
 557         call = NULL;
 558         goto error_no_call;
 559 }
 560
 561 /**
 562  * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 563  * @sock: The socket that the call exists on
 564  * @call: The call to send data through
 565  * @buf: The buffer to receive into
 566  * @size: The size of the buffer, including data already read
 567  * @_offset: The running offset into the buffer.
 568  * @want_more: True if more data is expected to be read
 569  * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 570  *
 571  * Allow a kernel service to receive data and pick up information about the
 572  * state of a call.  Returns 0 if got what was asked for and there's more
 573  * available, 1 if we got what was asked for and we're at the end of the data
 574  * and -EAGAIN if we need more data.
 575  *
 576  * Note that we may return -EAGAIN to drain empty packets at the end of the
 577  * data, even if we've already copied over the requested data.
 578  *
 579  * This function adds the amount it transfers to *_offset, so this should be
 580  * precleared as appropriate.  Note that the amount remaining in the buffer is
 581  * taken to be size - *_offset.
 582  *
 583  * *_abort should also be initialised to 0.
 584  */
 585 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 586                            void *buf, size_t size, size_t *_offset,
 587                            bool want_more, u32 *_abort)
 588 {
 589         struct iov_iter iter;
 590         struct kvec iov;
 591         int ret;
 592
 593         _enter("{%d,%s},%zu/%zu,%d",
 594                call->debug_id, rxrpc_call_states[call->state],
 595                *_offset, size, want_more);
 596
 597         ASSERTCMP(*_offset, <=, size);
 598         ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_ACCEPTING);
 599
 600         iov.iov_base = buf + *_offset;
 601         iov.iov_len = size - *_offset;
 602         iov_iter_kvec(&iter, ITER_KVEC | READ, &iov, 1, size - *_offset);
 603
 604         lock_sock(sock->sk);
 605
 606         switch (call->state) {
 607         case RXRPC_CALL_CLIENT_RECV_REPLY:
 608         case RXRPC_CALL_SERVER_RECV_REQUEST:
 609         case RXRPC_CALL_SERVER_ACK_REQUEST:
 610                 ret = rxrpc_recvmsg_data(sock, call, NULL, &iter, size, 0,
 611                                          _offset);
 612                 if (ret < 0)
 613                         goto out;
 614
 615                 /* We can only reach here with a partially full buffer if we
 616                  * have reached the end of the data.  We must otherwise have a
 617                  * full buffer or have been given -EAGAIN.
 618                  */
 619                 if (ret == 1) {
 620                         if (*_offset < size)
 621                                 goto short_data;
 622                         if (!want_more)
 623                                 goto read_phase_complete;
 624                         ret = 0;
 625                         goto out;
 626                 }
 627
 628                 if (!want_more)
 629                         goto excess_data;
 630                 goto out;
 631
 632         case RXRPC_CALL_COMPLETE:
 633                 goto call_complete;
 634
 635         default:
 636                 ret = -EINPROGRESS;
 637                 goto out;
 638         }
 639
 640 read_phase_complete:
 641         ret = 1;
 642 out:
 643         release_sock(sock->sk);
 644         _leave(" = %d [%zu,%d]", ret, *_offset, *_abort);
 645         return ret;
 646
 647 short_data:
 648         ret = -EBADMSG;
 649         goto out;
 650 excess_data:
 651         ret = -EMSGSIZE;
 652         goto out;
 653 call_complete:
 654         *_abort = call->abort_code;
 655         ret = call->error;
 656         if (call->completion == RXRPC_CALL_SUCCEEDED) {
 657                 ret = 1;
 658                 if (size > 0)
 659                         ret = -ECONNRESET;
 660         }
 661         goto out;
 662 }
 663 EXPORT_SYMBOL(rxrpc_kernel_recv_data);