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_call_packet(call, RXRPC_PACKET_TYPE_ACK);
 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_call_packet(call, RXRPC_PACKET_TYPE_ACK);
 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         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 265         unsigned int offset = *_offset;
 266         unsigned int len = *_len;
 267         int ret;
 268         u8 annotation = *_annotation;
 269
 270         /* Locate the subpacket */
 271         offset = sp->offset;
 272         len = skb->len - sp->offset;
 273         if ((annotation & RXRPC_RX_ANNO_JUMBO) > 0) {
 274                 offset += (((annotation & RXRPC_RX_ANNO_JUMBO) - 1) *
 275                            RXRPC_JUMBO_SUBPKTLEN);
 276                 len = (annotation & RXRPC_RX_ANNO_JLAST) ?
 277                         skb->len - offset : RXRPC_JUMBO_SUBPKTLEN;
 278         }
 279
 280         if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
 281                 ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
 282                 if (ret < 0)
 283                         return ret;
 284                 *_annotation |= RXRPC_RX_ANNO_VERIFIED;
 285         }
 286
 287         *_offset = offset;
 288         *_len = len;
 289         call->conn->security->locate_data(call, skb, _offset, _len);
 290         return 0;
 291 }
 292
 293 /*
 294  * Deliver messages to a call.  This keeps processing packets until the buffer
 295  * is filled and we find either more DATA (returns 0) or the end of the DATA
 296  * (returns 1).  If more packets are required, it returns -EAGAIN.
 297  */
 298 static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 299                               struct msghdr *msg, struct iov_iter *iter,
 300                               size_t len, int flags, size_t *_offset)
 301 {
 302         struct rxrpc_skb_priv *sp;
 303         struct sk_buff *skb;
 304         rxrpc_seq_t hard_ack, top, seq;
 305         size_t remain;
 306         bool last;
 307         unsigned int rx_pkt_offset, rx_pkt_len;
 308         int ix, copy, ret = -EAGAIN, ret2;
 309
 310         rx_pkt_offset = call->rx_pkt_offset;
 311         rx_pkt_len = call->rx_pkt_len;
 312
 313         if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
 314                 seq = call->rx_hard_ack;
 315                 ret = 1;
 316                 goto done;
 317         }
 318
 319         /* Barriers against rxrpc_input_data(). */
 320         hard_ack = call->rx_hard_ack;
 321         top = smp_load_acquire(&call->rx_top);
 322         for (seq = hard_ack + 1; before_eq(seq, top); seq++) {
 323                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 324                 skb = call->rxtx_buffer[ix];
 325                 if (!skb) {
 326                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq,
 327                                             rx_pkt_offset, rx_pkt_len, 0);
 328                         break;
 329                 }
 330                 smp_rmb();
 331                 rxrpc_see_skb(skb, rxrpc_skb_rx_seen);
 332                 sp = rxrpc_skb(skb);
 333
 334                 if (!(flags & MSG_PEEK))
 335                         trace_rxrpc_receive(call, rxrpc_receive_front,
 336                                             sp->hdr.serial, seq);
 337
 338                 if (msg)
 339                         sock_recv_timestamp(msg, sock->sk, skb);
 340
 341                 if (rx_pkt_offset == 0) {
 342                         ret2 = rxrpc_locate_data(call, skb,
 343                                                  &call->rxtx_annotations[ix],
 344                                                  &rx_pkt_offset, &rx_pkt_len);
 345                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq,
 346                                             rx_pkt_offset, rx_pkt_len, ret2);
 347                         if (ret2 < 0) {
 348                                 ret = ret2;
 349                                 goto out;
 350                         }
 351                 } else {
 352                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq,
 353                                             rx_pkt_offset, rx_pkt_len, 0);
 354                 }
 355
 356                 /* We have to handle short, empty and used-up DATA packets. */
 357                 remain = len - *_offset;
 358                 copy = rx_pkt_len;
 359                 if (copy > remain)
 360                         copy = remain;
 361                 if (copy > 0) {
 362                         ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
 363                                                       copy);
 364                         if (ret2 < 0) {
 365                                 ret = ret2;
 366                                 goto out;
 367                         }
 368
 369                         /* handle piecemeal consumption of data packets */
 370                         rx_pkt_offset += copy;
 371                         rx_pkt_len -= copy;
 372                         *_offset += copy;
 373                 }
 374
 375                 if (rx_pkt_len > 0) {
 376                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq,
 377                                             rx_pkt_offset, rx_pkt_len, 0);
 378                         ASSERTCMP(*_offset, ==, len);
 379                         ret = 0;
 380                         break;
 381                 }
 382
 383                 /* The whole packet has been transferred. */
 384                 last = sp->hdr.flags & RXRPC_LAST_PACKET;
 385                 if (!(flags & MSG_PEEK))
 386                         rxrpc_rotate_rx_window(call);
 387                 rx_pkt_offset = 0;
 388                 rx_pkt_len = 0;
 389
 390                 if (last) {
 391                         ASSERTCMP(seq, ==, READ_ONCE(call->rx_top));
 392                         ret = 1;
 393                         goto out;
 394                 }
 395         }
 396
 397 out:
 398         if (!(flags & MSG_PEEK)) {
 399                 call->rx_pkt_offset = rx_pkt_offset;
 400                 call->rx_pkt_len = rx_pkt_len;
 401         }
 402 done:
 403         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_data_return, seq,
 404                             rx_pkt_offset, rx_pkt_len, ret);
 405         return ret;
 406 }
 407
 408 /*
 409  * Receive a message from an RxRPC socket
 410  * - we need to be careful about two or more threads calling recvmsg
 411  *   simultaneously
 412  */
 413 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 414                   int flags)
 415 {
 416         struct rxrpc_call *call;
 417         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 418         struct list_head *l;
 419         size_t copied = 0;
 420         long timeo;
 421         int ret;
 422
 423         DEFINE_WAIT(wait);
 424
 425         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0, 0, 0, 0);
 426
 427         if (flags & (MSG_OOB | MSG_TRUNC))
 428                 return -EOPNOTSUPP;
 429
 430         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
 431
 432 try_again:
 433         lock_sock(&rx->sk);
 434
 435         /* Return immediately if a client socket has no outstanding calls */
 436         if (RB_EMPTY_ROOT(&rx->calls) &&
 437             list_empty(&rx->recvmsg_q) &&
 438             rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
 439                 release_sock(&rx->sk);
 440                 return -ENODATA;
 441         }
 442
 443         if (list_empty(&rx->recvmsg_q)) {
 444                 ret = -EWOULDBLOCK;
 445                 if (timeo == 0) {
 446                         call = NULL;
 447                         goto error_no_call;
 448                 }
 449
 450                 release_sock(&rx->sk);
 451
 452                 /* Wait for something to happen */
 453                 prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
 454                                           TASK_INTERRUPTIBLE);
 455                 ret = sock_error(&rx->sk);
 456                 if (ret)
 457                         goto wait_error;
 458
 459                 if (list_empty(&rx->recvmsg_q)) {
 460                         if (signal_pending(current))
 461                                 goto wait_interrupted;
 462                         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait,
 463                                             0, 0, 0, 0);
 464                         timeo = schedule_timeout(timeo);
 465                 }
 466                 finish_wait(sk_sleep(&rx->sk), &wait);
 467                 goto try_again;
 468         }
 469
 470         /* Find the next call and dequeue it if we're not just peeking.  If we
 471          * do dequeue it, that comes with a ref that we will need to release.
 472          */
 473         write_lock_bh(&rx->recvmsg_lock);
 474         l = rx->recvmsg_q.next;
 475         call = list_entry(l, struct rxrpc_call, recvmsg_link);
 476         if (!(flags & MSG_PEEK))
 477                 list_del_init(&call->recvmsg_link);
 478         else
 479                 rxrpc_get_call(call, rxrpc_call_got);
 480         write_unlock_bh(&rx->recvmsg_lock);
 481
 482         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0, 0, 0, 0);
 483
 484         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
 485                 BUG();
 486
 487         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
 488                 if (flags & MSG_CMSG_COMPAT) {
 489                         unsigned int id32 = call->user_call_ID;
 490
 491                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 492                                        sizeof(unsigned int), &id32);
 493                 } else {
 494                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 495                                        sizeof(unsigned long),
 496                                        &call->user_call_ID);
 497                 }
 498                 if (ret < 0)
 499                         goto error;
 500         }
 501
 502         if (msg->msg_name) {
 503                 size_t len = sizeof(call->conn->params.peer->srx);
 504                 memcpy(msg->msg_name, &call->conn->params.peer->srx, len);
 505                 msg->msg_namelen = len;
 506         }
 507
 508         switch (call->state) {
 509         case RXRPC_CALL_SERVER_ACCEPTING:
 510                 ret = rxrpc_recvmsg_new_call(rx, call, msg, flags);
 511                 break;
 512         case RXRPC_CALL_CLIENT_RECV_REPLY:
 513         case RXRPC_CALL_SERVER_RECV_REQUEST:
 514         case RXRPC_CALL_SERVER_ACK_REQUEST:
 515                 ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
 516                                          flags, &copied);
 517                 if (ret == -EAGAIN)
 518                         ret = 0;
 519
 520                 if (after(call->rx_top, call->rx_hard_ack) &&
 521                     call->rxtx_buffer[(call->rx_hard_ack + 1) & RXRPC_RXTX_BUFF_MASK])
 522                         rxrpc_notify_socket(call);
 523                 break;
 524         default:
 525                 ret = 0;
 526                 break;
 527         }
 528
 529         if (ret < 0)
 530                 goto error;
 531
 532         if (call->state == RXRPC_CALL_COMPLETE) {
 533                 ret = rxrpc_recvmsg_term(call, msg);
 534                 if (ret < 0)
 535                         goto error;
 536                 if (!(flags & MSG_PEEK))
 537                         rxrpc_release_call(rx, call);
 538                 msg->msg_flags |= MSG_EOR;
 539                 ret = 1;
 540         }
 541
 542         if (ret == 0)
 543                 msg->msg_flags |= MSG_MORE;
 544         else
 545                 msg->msg_flags &= ~MSG_MORE;
 546         ret = copied;
 547
 548 error:
 549         rxrpc_put_call(call, rxrpc_call_put);
 550 error_no_call:
 551         release_sock(&rx->sk);
 552         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 553         return ret;
 554
 555 wait_interrupted:
 556         ret = sock_intr_errno(timeo);
 557 wait_error:
 558         finish_wait(sk_sleep(&rx->sk), &wait);
 559         call = NULL;
 560         goto error_no_call;
 561 }
 562
 563 /**
 564  * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 565  * @sock: The socket that the call exists on
 566  * @call: The call to send data through
 567  * @buf: The buffer to receive into
 568  * @size: The size of the buffer, including data already read
 569  * @_offset: The running offset into the buffer.
 570  * @want_more: True if more data is expected to be read
 571  * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 572  *
 573  * Allow a kernel service to receive data and pick up information about the
 574  * state of a call.  Returns 0 if got what was asked for and there's more
 575  * available, 1 if we got what was asked for and we're at the end of the data
 576  * and -EAGAIN if we need more data.
 577  *
 578  * Note that we may return -EAGAIN to drain empty packets at the end of the
 579  * data, even if we've already copied over the requested data.
 580  *
 581  * This function adds the amount it transfers to *_offset, so this should be
 582  * precleared as appropriate.  Note that the amount remaining in the buffer is
 583  * taken to be size - *_offset.
 584  *
 585  * *_abort should also be initialised to 0.
 586  */
 587 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 588                            void *buf, size_t size, size_t *_offset,
 589                            bool want_more, u32 *_abort)
 590 {
 591         struct iov_iter iter;
 592         struct kvec iov;
 593         int ret;
 594
 595         _enter("{%d,%s},%zu/%zu,%d",
 596                call->debug_id, rxrpc_call_states[call->state],
 597                *_offset, size, want_more);
 598
 599         ASSERTCMP(*_offset, <=, size);
 600         ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_ACCEPTING);
 601
 602         iov.iov_base = buf + *_offset;
 603         iov.iov_len = size - *_offset;
 604         iov_iter_kvec(&iter, ITER_KVEC | READ, &iov, 1, size - *_offset);
 605
 606         lock_sock(sock->sk);
 607
 608         switch (call->state) {
 609         case RXRPC_CALL_CLIENT_RECV_REPLY:
 610         case RXRPC_CALL_SERVER_RECV_REQUEST:
 611         case RXRPC_CALL_SERVER_ACK_REQUEST:
 612                 ret = rxrpc_recvmsg_data(sock, call, NULL, &iter, size, 0,
 613                                          _offset);
 614                 if (ret < 0)
 615                         goto out;
 616
 617                 /* We can only reach here with a partially full buffer if we
 618                  * have reached the end of the data.  We must otherwise have a
 619                  * full buffer or have been given -EAGAIN.
 620                  */
 621                 if (ret == 1) {
 622                         if (*_offset < size)
 623                                 goto short_data;
 624                         if (!want_more)
 625                                 goto read_phase_complete;
 626                         ret = 0;
 627                         goto out;
 628                 }
 629
 630                 if (!want_more)
 631                         goto excess_data;
 632                 goto out;
 633
 634         case RXRPC_CALL_COMPLETE:
 635                 goto call_complete;
 636
 637         default:
 638                 ret = -EINPROGRESS;
 639                 goto out;
 640         }
 641
 642 read_phase_complete:
 643         ret = 1;
 644 out:
 645         release_sock(sock->sk);
 646         _leave(" = %d [%zu,%d]", ret, *_offset, *_abort);
 647         return ret;
 648
 649 short_data:
 650         ret = -EBADMSG;
 651         goto out;
 652 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 (size > 0)
 661                         ret = -ECONNRESET;
 662         }
 663         goto out;
 664 }
 665 EXPORT_SYMBOL(rxrpc_kernel_recv_data);