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)
 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, 0, true, false);
 145                 rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ACK);
 146         } else {
 147                 rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, 0, 0, false, false);
 148         }
 149
 150         write_lock_bh(&call->state_lock);
 151
 152         switch (call->state) {
 153         case RXRPC_CALL_CLIENT_RECV_REPLY:
 154                 __rxrpc_call_completed(call);
 155                 break;
 156
 157         case RXRPC_CALL_SERVER_RECV_REQUEST:
 158                 call->tx_phase = true;
 159                 call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
 160                 break;
 161         default:
 162                 break;
 163         }
 164
 165         write_unlock_bh(&call->state_lock);
 166 }
 167
 168 /*
 169  * Discard a packet we've used up and advance the Rx window by one.
 170  */
 171 static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
 172 {
 173         struct rxrpc_skb_priv *sp;
 174         struct sk_buff *skb;
 175         rxrpc_serial_t serial;
 176         rxrpc_seq_t hard_ack, top;
 177         u8 flags;
 178         int ix;
 179
 180         _enter("%d", call->debug_id);
 181
 182         hard_ack = call->rx_hard_ack;
 183         top = smp_load_acquire(&call->rx_top);
 184         ASSERT(before(hard_ack, top));
 185
 186         hard_ack++;
 187         ix = hard_ack & RXRPC_RXTX_BUFF_MASK;
 188         skb = call->rxtx_buffer[ix];
 189         rxrpc_see_skb(skb, rxrpc_skb_rx_rotated);
 190         sp = rxrpc_skb(skb);
 191         flags = sp->hdr.flags;
 192         serial = sp->hdr.serial;
 193         if (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO)
 194                 serial += (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO) - 1;
 195
 196         call->rxtx_buffer[ix] = NULL;
 197         call->rxtx_annotations[ix] = 0;
 198         /* Barrier against rxrpc_input_data(). */
 199         smp_store_release(&call->rx_hard_ack, hard_ack);
 200
 201         rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
 202
 203         _debug("%u,%u,%02x", hard_ack, top, flags);
 204         trace_rxrpc_receive(call, rxrpc_receive_rotate, serial, hard_ack);
 205         if (flags & RXRPC_LAST_PACKET)
 206                 rxrpc_end_rx_phase(call);
 207 }
 208
 209 /*
 210  * Decrypt and verify a (sub)packet.  The packet's length may be changed due to
 211  * padding, but if this is the case, the packet length will be resident in the
 212  * socket buffer.  Note that we can't modify the master skb info as the skb may
 213  * be the home to multiple subpackets.
 214  */
 215 static int rxrpc_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
 216                                u8 annotation,
 217                                unsigned int offset, unsigned int len)
 218 {
 219         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 220         rxrpc_seq_t seq = sp->hdr.seq;
 221         u16 cksum = sp->hdr.cksum;
 222
 223         _enter("");
 224
 225         /* For all but the head jumbo subpacket, the security checksum is in a
 226          * jumbo header immediately prior to the data.
 227          */
 228         if ((annotation & RXRPC_RX_ANNO_JUMBO) > 1) {
 229                 __be16 tmp;
 230                 if (skb_copy_bits(skb, offset - 2, &tmp, 2) < 0)
 231                         BUG();
 232                 cksum = ntohs(tmp);
 233                 seq += (annotation & RXRPC_RX_ANNO_JUMBO) - 1;
 234         }
 235
 236         return call->conn->security->verify_packet(call, skb, offset, len,
 237                                                    seq, cksum);
 238 }
 239
 240 /*
 241  * Locate the data within a packet.  This is complicated by:
 242  *
 243  * (1) An skb may contain a jumbo packet - so we have to find the appropriate
 244  *     subpacket.
 245  *
 246  * (2) The (sub)packets may be encrypted and, if so, the encrypted portion
 247  *     contains an extra header which includes the true length of the data,
 248  *     excluding any encrypted padding.
 249  */
 250 static int rxrpc_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
 251                              u8 *_annotation,
 252                              unsigned int *_offset, unsigned int *_len)
 253 {
 254         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 255         unsigned int offset = *_offset;
 256         unsigned int len = *_len;
 257         int ret;
 258         u8 annotation = *_annotation;
 259
 260         /* Locate the subpacket */
 261         offset = sp->offset;
 262         len = skb->len - sp->offset;
 263         if ((annotation & RXRPC_RX_ANNO_JUMBO) > 0) {
 264                 offset += (((annotation & RXRPC_RX_ANNO_JUMBO) - 1) *
 265                            RXRPC_JUMBO_SUBPKTLEN);
 266                 len = (annotation & RXRPC_RX_ANNO_JLAST) ?
 267                         skb->len - offset : RXRPC_JUMBO_SUBPKTLEN;
 268         }
 269
 270         if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
 271                 ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
 272                 if (ret < 0)
 273                         return ret;
 274                 *_annotation |= RXRPC_RX_ANNO_VERIFIED;
 275         }
 276
 277         *_offset = offset;
 278         *_len = len;
 279         call->conn->security->locate_data(call, skb, _offset, _len);
 280         return 0;
 281 }
 282
 283 /*
 284  * Deliver messages to a call.  This keeps processing packets until the buffer
 285  * is filled and we find either more DATA (returns 0) or the end of the DATA
 286  * (returns 1).  If more packets are required, it returns -EAGAIN.
 287  */
 288 static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 289                               struct msghdr *msg, struct iov_iter *iter,
 290                               size_t len, int flags, size_t *_offset)
 291 {
 292         struct rxrpc_skb_priv *sp;
 293         struct sk_buff *skb;
 294         rxrpc_seq_t hard_ack, top, seq;
 295         size_t remain;
 296         bool last;
 297         unsigned int rx_pkt_offset, rx_pkt_len;
 298         int ix, copy, ret = -EAGAIN, ret2;
 299
 300         rx_pkt_offset = call->rx_pkt_offset;
 301         rx_pkt_len = call->rx_pkt_len;
 302
 303         if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
 304                 seq = call->rx_hard_ack;
 305                 ret = 1;
 306                 goto done;
 307         }
 308
 309         /* Barriers against rxrpc_input_data(). */
 310         hard_ack = call->rx_hard_ack;
 311         top = smp_load_acquire(&call->rx_top);
 312         for (seq = hard_ack + 1; before_eq(seq, top); seq++) {
 313                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 314                 skb = call->rxtx_buffer[ix];
 315                 if (!skb) {
 316                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq,
 317                                             rx_pkt_offset, rx_pkt_len, 0);
 318                         break;
 319                 }
 320                 smp_rmb();
 321                 rxrpc_see_skb(skb, rxrpc_skb_rx_seen);
 322                 sp = rxrpc_skb(skb);
 323
 324                 if (!(flags & MSG_PEEK))
 325                         trace_rxrpc_receive(call, rxrpc_receive_front,
 326                                             sp->hdr.serial, seq);
 327
 328                 if (msg)
 329                         sock_recv_timestamp(msg, sock->sk, skb);
 330
 331                 if (rx_pkt_offset == 0) {
 332                         ret2 = rxrpc_locate_data(call, skb,
 333                                                  &call->rxtx_annotations[ix],
 334                                                  &rx_pkt_offset, &rx_pkt_len);
 335                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq,
 336                                             rx_pkt_offset, rx_pkt_len, ret2);
 337                         if (ret2 < 0) {
 338                                 ret = ret2;
 339                                 goto out;
 340                         }
 341                 } else {
 342                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq,
 343                                             rx_pkt_offset, rx_pkt_len, 0);
 344                 }
 345
 346                 /* We have to handle short, empty and used-up DATA packets. */
 347                 remain = len - *_offset;
 348                 copy = rx_pkt_len;
 349                 if (copy > remain)
 350                         copy = remain;
 351                 if (copy > 0) {
 352                         ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
 353                                                       copy);
 354                         if (ret2 < 0) {
 355                                 ret = ret2;
 356                                 goto out;
 357                         }
 358
 359                         /* handle piecemeal consumption of data packets */
 360                         rx_pkt_offset += copy;
 361                         rx_pkt_len -= copy;
 362                         *_offset += copy;
 363                 }
 364
 365                 if (rx_pkt_len > 0) {
 366                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq,
 367                                             rx_pkt_offset, rx_pkt_len, 0);
 368                         ASSERTCMP(*_offset, ==, len);
 369                         ret = 0;
 370                         break;
 371                 }
 372
 373                 /* The whole packet has been transferred. */
 374                 last = sp->hdr.flags & RXRPC_LAST_PACKET;
 375                 if (!(flags & MSG_PEEK))
 376                         rxrpc_rotate_rx_window(call);
 377                 rx_pkt_offset = 0;
 378                 rx_pkt_len = 0;
 379
 380                 if (last) {
 381                         ASSERTCMP(seq, ==, READ_ONCE(call->rx_top));
 382                         ret = 1;
 383                         goto out;
 384                 }
 385         }
 386
 387 out:
 388         if (!(flags & MSG_PEEK)) {
 389                 call->rx_pkt_offset = rx_pkt_offset;
 390                 call->rx_pkt_len = rx_pkt_len;
 391         }
 392 done:
 393         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_data_return, seq,
 394                             rx_pkt_offset, rx_pkt_len, ret);
 395         return ret;
 396 }
 397
 398 /*
 399  * Receive a message from an RxRPC socket
 400  * - we need to be careful about two or more threads calling recvmsg
 401  *   simultaneously
 402  */
 403 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 404                   int flags)
 405 {
 406         struct rxrpc_call *call;
 407         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 408         struct list_head *l;
 409         size_t copied = 0;
 410         long timeo;
 411         int ret;
 412
 413         DEFINE_WAIT(wait);
 414
 415         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0, 0, 0, 0);
 416
 417         if (flags & (MSG_OOB | MSG_TRUNC))
 418                 return -EOPNOTSUPP;
 419
 420         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
 421
 422 try_again:
 423         lock_sock(&rx->sk);
 424
 425         /* Return immediately if a client socket has no outstanding calls */
 426         if (RB_EMPTY_ROOT(&rx->calls) &&
 427             list_empty(&rx->recvmsg_q) &&
 428             rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
 429                 release_sock(&rx->sk);
 430                 return -ENODATA;
 431         }
 432
 433         if (list_empty(&rx->recvmsg_q)) {
 434                 ret = -EWOULDBLOCK;
 435                 if (timeo == 0) {
 436                         call = NULL;
 437                         goto error_no_call;
 438                 }
 439
 440                 release_sock(&rx->sk);
 441
 442                 /* Wait for something to happen */
 443                 prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
 444                                           TASK_INTERRUPTIBLE);
 445                 ret = sock_error(&rx->sk);
 446                 if (ret)
 447                         goto wait_error;
 448
 449                 if (list_empty(&rx->recvmsg_q)) {
 450                         if (signal_pending(current))
 451                                 goto wait_interrupted;
 452                         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait,
 453                                             0, 0, 0, 0);
 454                         timeo = schedule_timeout(timeo);
 455                 }
 456                 finish_wait(sk_sleep(&rx->sk), &wait);
 457                 goto try_again;
 458         }
 459
 460         /* Find the next call and dequeue it if we're not just peeking.  If we
 461          * do dequeue it, that comes with a ref that we will need to release.
 462          */
 463         write_lock_bh(&rx->recvmsg_lock);
 464         l = rx->recvmsg_q.next;
 465         call = list_entry(l, struct rxrpc_call, recvmsg_link);
 466         if (!(flags & MSG_PEEK))
 467                 list_del_init(&call->recvmsg_link);
 468         else
 469                 rxrpc_get_call(call, rxrpc_call_got);
 470         write_unlock_bh(&rx->recvmsg_lock);
 471
 472         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0, 0, 0, 0);
 473
 474         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
 475                 BUG();
 476
 477         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
 478                 if (flags & MSG_CMSG_COMPAT) {
 479                         unsigned int id32 = call->user_call_ID;
 480
 481                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 482                                        sizeof(unsigned int), &id32);
 483                 } else {
 484                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 485                                        sizeof(unsigned long),
 486                                        &call->user_call_ID);
 487                 }
 488                 if (ret < 0)
 489                         goto error;
 490         }
 491
 492         if (msg->msg_name) {
 493                 size_t len = sizeof(call->conn->params.peer->srx);
 494                 memcpy(msg->msg_name, &call->conn->params.peer->srx, len);
 495                 msg->msg_namelen = len;
 496         }
 497
 498         switch (call->state) {
 499         case RXRPC_CALL_SERVER_ACCEPTING:
 500                 ret = rxrpc_recvmsg_new_call(rx, call, msg, flags);
 501                 break;
 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                 if (after(call->rx_top, call->rx_hard_ack) &&
 511                     call->rxtx_buffer[(call->rx_hard_ack + 1) & RXRPC_RXTX_BUFF_MASK])
 512                         rxrpc_notify_socket(call);
 513                 break;
 514         default:
 515                 ret = 0;
 516                 break;
 517         }
 518
 519         if (ret < 0)
 520                 goto error;
 521
 522         if (call->state == RXRPC_CALL_COMPLETE) {
 523                 ret = rxrpc_recvmsg_term(call, msg);
 524                 if (ret < 0)
 525                         goto error;
 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:
 539         rxrpc_put_call(call, rxrpc_call_put);
 540 error_no_call:
 541         release_sock(&rx->sk);
 542         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 543         return ret;
 544
 545 wait_interrupted:
 546         ret = sock_intr_errno(timeo);
 547 wait_error:
 548         finish_wait(sk_sleep(&rx->sk), &wait);
 549         call = NULL;
 550         goto error_no_call;
 551 }
 552
 553 /**
 554  * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 555  * @sock: The socket that the call exists on
 556  * @call: The call to send data through
 557  * @buf: The buffer to receive into
 558  * @size: The size of the buffer, including data already read
 559  * @_offset: The running offset into the buffer.
 560  * @want_more: True if more data is expected to be read
 561  * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 562  *
 563  * Allow a kernel service to receive data and pick up information about the
 564  * state of a call.  Returns 0 if got what was asked for and there's more
 565  * available, 1 if we got what was asked for and we're at the end of the data
 566  * and -EAGAIN if we need more data.
 567  *
 568  * Note that we may return -EAGAIN to drain empty packets at the end of the
 569  * data, even if we've already copied over the requested data.
 570  *
 571  * This function adds the amount it transfers to *_offset, so this should be
 572  * precleared as appropriate.  Note that the amount remaining in the buffer is
 573  * taken to be size - *_offset.
 574  *
 575  * *_abort should also be initialised to 0.
 576  */
 577 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 578                            void *buf, size_t size, size_t *_offset,
 579                            bool want_more, u32 *_abort)
 580 {
 581         struct iov_iter iter;
 582         struct kvec iov;
 583         int ret;
 584
 585         _enter("{%d,%s},%zu/%zu,%d",
 586                call->debug_id, rxrpc_call_states[call->state],
 587                *_offset, size, want_more);
 588
 589         ASSERTCMP(*_offset, <=, size);
 590         ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_ACCEPTING);
 591
 592         iov.iov_base = buf + *_offset;
 593         iov.iov_len = size - *_offset;
 594         iov_iter_kvec(&iter, ITER_KVEC | READ, &iov, 1, size - *_offset);
 595
 596         lock_sock(sock->sk);
 597
 598         switch (call->state) {
 599         case RXRPC_CALL_CLIENT_RECV_REPLY:
 600         case RXRPC_CALL_SERVER_RECV_REQUEST:
 601         case RXRPC_CALL_SERVER_ACK_REQUEST:
 602                 ret = rxrpc_recvmsg_data(sock, call, NULL, &iter, size, 0,
 603                                          _offset);
 604                 if (ret < 0)
 605                         goto out;
 606
 607                 /* We can only reach here with a partially full buffer if we
 608                  * have reached the end of the data.  We must otherwise have a
 609                  * full buffer or have been given -EAGAIN.
 610                  */
 611                 if (ret == 1) {
 612                         if (*_offset < size)
 613                                 goto short_data;
 614                         if (!want_more)
 615                                 goto read_phase_complete;
 616                         ret = 0;
 617                         goto out;
 618                 }
 619
 620                 if (!want_more)
 621                         goto excess_data;
 622                 goto out;
 623
 624         case RXRPC_CALL_COMPLETE:
 625                 goto call_complete;
 626
 627         default:
 628                 ret = -EINPROGRESS;
 629                 goto out;
 630         }
 631
 632 read_phase_complete:
 633         ret = 1;
 634 out:
 635         release_sock(sock->sk);
 636         _leave(" = %d [%zu,%d]", ret, *_offset, *_abort);
 637         return ret;
 638
 639 short_data:
 640         ret = -EBADMSG;
 641         goto out;
 642 excess_data:
 643         ret = -EMSGSIZE;
 644         goto out;
 645 call_complete:
 646         *_abort = call->abort_code;
 647         ret = call->error;
 648         if (call->completion == RXRPC_CALL_SUCCEEDED) {
 649                 ret = 1;
 650                 if (size > 0)
 651                         ret = -ECONNRESET;
 652         }
 653         goto out;
 654 }
 655 EXPORT_SYMBOL(rxrpc_kernel_recv_data);