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 <linux/sched/signal.h>
  18
  19 #include <net/sock.h>
  20 #include <net/af_rxrpc.h>
  21 #include "ar-internal.h"
  22
  23 /*
  24  * Post a call for attention by the socket or kernel service.  Further
  25  * notifications are suppressed by putting recvmsg_link on a dummy queue.
  26  */
  27 void rxrpc_notify_socket(struct rxrpc_call *call)
  28 {
  29         struct rxrpc_sock *rx;
  30         struct sock *sk;
  31
  32         _enter("%d", call->debug_id);
  33
  34         if (!list_empty(&call->recvmsg_link))
  35                 return;
  36
  37         rcu_read_lock();
  38
  39         rx = rcu_dereference(call->socket);
  40         sk = &rx->sk;
  41         if (rx && sk->sk_state < RXRPC_CLOSE) {
  42                 if (call->notify_rx) {
  43                         spin_lock_bh(&call->notify_lock);
  44                         call->notify_rx(sk, call, call->user_call_ID);
  45                         spin_unlock_bh(&call->notify_lock);
  46                 } else {
  47                         write_lock_bh(&rx->recvmsg_lock);
  48                         if (list_empty(&call->recvmsg_link)) {
  49                                 rxrpc_get_call(call, rxrpc_call_got);
  50                                 list_add_tail(&call->recvmsg_link, &rx->recvmsg_q);
  51                         }
  52                         write_unlock_bh(&rx->recvmsg_lock);
  53
  54                         if (!sock_flag(sk, SOCK_DEAD)) {
  55                                 _debug("call %ps", sk->sk_data_ready);
  56                                 sk->sk_data_ready(sk);
  57                         }
  58                 }
  59         }
  60
  61         rcu_read_unlock();
  62         _leave("");
  63 }
  64
  65 /*
  66  * Pass a call terminating message to userspace.
  67  */
  68 static int rxrpc_recvmsg_term(struct rxrpc_call *call, struct msghdr *msg)
  69 {
  70         u32 tmp = 0;
  71         int ret;
  72
  73         switch (call->completion) {
  74         case RXRPC_CALL_SUCCEEDED:
  75                 ret = 0;
  76                 if (rxrpc_is_service_call(call))
  77                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &tmp);
  78                 break;
  79         case RXRPC_CALL_REMOTELY_ABORTED:
  80                 tmp = call->abort_code;
  81                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
  82                 break;
  83         case RXRPC_CALL_LOCALLY_ABORTED:
  84                 tmp = call->abort_code;
  85                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
  86                 break;
  87         case RXRPC_CALL_NETWORK_ERROR:
  88                 tmp = -call->error;
  89                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &tmp);
  90                 break;
  91         case RXRPC_CALL_LOCAL_ERROR:
  92                 tmp = -call->error;
  93                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4, &tmp);
  94                 break;
  95         default:
  96                 pr_err("Invalid terminal call state %u\n", call->state);
  97                 BUG();
  98                 break;
  99         }
 100
 101         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_terminal, call->rx_hard_ack,
 102                             call->rx_pkt_offset, call->rx_pkt_len, ret);
 103         return ret;
 104 }
 105
 106 /*
 107  * Pass back notification of a new call.  The call is added to the
 108  * to-be-accepted list.  This means that the next call to be accepted might not
 109  * be the last call seen awaiting acceptance, but unless we leave this on the
 110  * front of the queue and block all other messages until someone gives us a
 111  * user_ID for it, there's not a lot we can do.
 112  */
 113 static int rxrpc_recvmsg_new_call(struct rxrpc_sock *rx,
 114                                   struct rxrpc_call *call,
 115                                   struct msghdr *msg, int flags)
 116 {
 117         int tmp = 0, ret;
 118
 119         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NEW_CALL, 0, &tmp);
 120
 121         if (ret == 0 && !(flags & MSG_PEEK)) {
 122                 _debug("to be accepted");
 123                 write_lock_bh(&rx->recvmsg_lock);
 124                 list_del_init(&call->recvmsg_link);
 125                 write_unlock_bh(&rx->recvmsg_lock);
 126
 127                 rxrpc_get_call(call, rxrpc_call_got);
 128                 write_lock(&rx->call_lock);
 129                 list_add_tail(&call->accept_link, &rx->to_be_accepted);
 130                 write_unlock(&rx->call_lock);
 131         }
 132
 133         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_to_be_accepted, 1, 0, 0, ret);
 134         return ret;
 135 }
 136
 137 /*
 138  * End the packet reception phase.
 139  */
 140 static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
 141 {
 142         _enter("%d,%s", call->debug_id, rxrpc_call_states[call->state]);
 143
 144         trace_rxrpc_receive(call, rxrpc_receive_end, 0, call->rx_top);
 145         ASSERTCMP(call->rx_hard_ack, ==, call->rx_top);
 146
 147         if (call->state == RXRPC_CALL_CLIENT_RECV_REPLY) {
 148                 rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, 0, serial, true, false,
 149                                   rxrpc_propose_ack_terminal_ack);
 150                 rxrpc_send_ack_packet(call, false);
 151         }
 152
 153         write_lock_bh(&call->state_lock);
 154
 155         switch (call->state) {
 156         case RXRPC_CALL_CLIENT_RECV_REPLY:
 157                 __rxrpc_call_completed(call);
 158                 write_unlock_bh(&call->state_lock);
 159                 break;
 160
 161         case RXRPC_CALL_SERVER_RECV_REQUEST:
 162                 call->tx_phase = true;
 163                 call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
 164                 call->ack_at = call->expire_at;
 165                 write_unlock_bh(&call->state_lock);
 166                 rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, 0, serial, false, true,
 167                                   rxrpc_propose_ack_processing_op);
 168                 break;
 169         default:
 170                 write_unlock_bh(&call->state_lock);
 171                 break;
 172         }
 173 }
 174
 175 /*
 176  * Discard a packet we've used up and advance the Rx window by one.
 177  */
 178 static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
 179 {
 180         struct rxrpc_skb_priv *sp;
 181         struct sk_buff *skb;
 182         rxrpc_serial_t serial;
 183         rxrpc_seq_t hard_ack, top;
 184         u8 flags;
 185         int ix;
 186
 187         _enter("%d", call->debug_id);
 188
 189         hard_ack = call->rx_hard_ack;
 190         top = smp_load_acquire(&call->rx_top);
 191         ASSERT(before(hard_ack, top));
 192
 193         hard_ack++;
 194         ix = hard_ack & RXRPC_RXTX_BUFF_MASK;
 195         skb = call->rxtx_buffer[ix];
 196         rxrpc_see_skb(skb, rxrpc_skb_rx_rotated);
 197         sp = rxrpc_skb(skb);
 198         flags = sp->hdr.flags;
 199         serial = sp->hdr.serial;
 200         if (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO)
 201                 serial += (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO) - 1;
 202
 203         call->rxtx_buffer[ix] = NULL;
 204         call->rxtx_annotations[ix] = 0;
 205         /* Barrier against rxrpc_input_data(). */
 206         smp_store_release(&call->rx_hard_ack, hard_ack);
 207
 208         rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
 209
 210         _debug("%u,%u,%02x", hard_ack, top, flags);
 211         trace_rxrpc_receive(call, rxrpc_receive_rotate, serial, hard_ack);
 212         if (flags & RXRPC_LAST_PACKET) {
 213                 rxrpc_end_rx_phase(call, serial);
 214         } else {
 215                 /* Check to see if there's an ACK that needs sending. */
 216                 if (after_eq(hard_ack, call->ackr_consumed + 2) ||
 217                     after_eq(top, call->ackr_seen + 2) ||
 218                     (hard_ack == top && after(hard_ack, call->ackr_consumed)))
 219                         rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, 0, serial,
 220                                           true, false,
 221                                           rxrpc_propose_ack_rotate_rx);
 222                 if (call->ackr_reason)
 223                         rxrpc_send_ack_packet(call, false);
 224         }
 225 }
 226
 227 /*
 228  * Decrypt and verify a (sub)packet.  The packet's length may be changed due to
 229  * padding, but if this is the case, the packet length will be resident in the
 230  * socket buffer.  Note that we can't modify the master skb info as the skb may
 231  * be the home to multiple subpackets.
 232  */
 233 static int rxrpc_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
 234                                u8 annotation,
 235                                unsigned int offset, unsigned int len)
 236 {
 237         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 238         rxrpc_seq_t seq = sp->hdr.seq;
 239         u16 cksum = sp->hdr.cksum;
 240
 241         _enter("");
 242
 243         /* For all but the head jumbo subpacket, the security checksum is in a
 244          * jumbo header immediately prior to the data.
 245          */
 246         if ((annotation & RXRPC_RX_ANNO_JUMBO) > 1) {
 247                 __be16 tmp;
 248                 if (skb_copy_bits(skb, offset - 2, &tmp, 2) < 0)
 249                         BUG();
 250                 cksum = ntohs(tmp);
 251                 seq += (annotation & RXRPC_RX_ANNO_JUMBO) - 1;
 252         }
 253
 254         return call->conn->security->verify_packet(call, skb, offset, len,
 255                                                    seq, cksum);
 256 }
 257
 258 /*
 259  * Locate the data within a packet.  This is complicated by:
 260  *
 261  * (1) An skb may contain a jumbo packet - so we have to find the appropriate
 262  *     subpacket.
 263  *
 264  * (2) The (sub)packets may be encrypted and, if so, the encrypted portion
 265  *     contains an extra header which includes the true length of the data,
 266  *     excluding any encrypted padding.
 267  */
 268 static int rxrpc_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
 269                              u8 *_annotation,
 270                              unsigned int *_offset, unsigned int *_len)
 271 {
 272         unsigned int offset = sizeof(struct rxrpc_wire_header);
 273         unsigned int len = *_len;
 274         int ret;
 275         u8 annotation = *_annotation;
 276
 277         /* Locate the subpacket */
 278         len = skb->len - offset;
 279         if ((annotation & RXRPC_RX_ANNO_JUMBO) > 0) {
 280                 offset += (((annotation & RXRPC_RX_ANNO_JUMBO) - 1) *
 281                            RXRPC_JUMBO_SUBPKTLEN);
 282                 len = (annotation & RXRPC_RX_ANNO_JLAST) ?
 283                         skb->len - offset : RXRPC_JUMBO_SUBPKTLEN;
 284         }
 285
 286         if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
 287                 ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
 288                 if (ret < 0)
 289                         return ret;
 290                 *_annotation |= RXRPC_RX_ANNO_VERIFIED;
 291         }
 292
 293         *_offset = offset;
 294         *_len = len;
 295         call->conn->security->locate_data(call, skb, _offset, _len);
 296         return 0;
 297 }
 298
 299 /*
 300  * Deliver messages to a call.  This keeps processing packets until the buffer
 301  * is filled and we find either more DATA (returns 0) or the end of the DATA
 302  * (returns 1).  If more packets are required, it returns -EAGAIN.
 303  */
 304 static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 305                               struct msghdr *msg, struct iov_iter *iter,
 306                               size_t len, int flags, size_t *_offset)
 307 {
 308         struct rxrpc_skb_priv *sp;
 309         struct sk_buff *skb;
 310         rxrpc_seq_t hard_ack, top, seq;
 311         size_t remain;
 312         bool last;
 313         unsigned int rx_pkt_offset, rx_pkt_len;
 314         int ix, copy, ret = -EAGAIN, ret2;
 315
 316         rx_pkt_offset = call->rx_pkt_offset;
 317         rx_pkt_len = call->rx_pkt_len;
 318
 319         if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
 320                 seq = call->rx_hard_ack;
 321                 ret = 1;
 322                 goto done;
 323         }
 324
 325         /* Barriers against rxrpc_input_data(). */
 326         hard_ack = call->rx_hard_ack;
 327         seq = hard_ack + 1;
 328         while (top = smp_load_acquire(&call->rx_top),
 329                before_eq(seq, top)
 330                ) {
 331                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 332                 skb = call->rxtx_buffer[ix];
 333                 if (!skb) {
 334                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq,
 335                                             rx_pkt_offset, rx_pkt_len, 0);
 336                         break;
 337                 }
 338                 smp_rmb();
 339                 rxrpc_see_skb(skb, rxrpc_skb_rx_seen);
 340                 sp = rxrpc_skb(skb);
 341
 342                 if (!(flags & MSG_PEEK))
 343                         trace_rxrpc_receive(call, rxrpc_receive_front,
 344                                             sp->hdr.serial, seq);
 345
 346                 if (msg)
 347                         sock_recv_timestamp(msg, sock->sk, skb);
 348
 349                 if (rx_pkt_offset == 0) {
 350                         ret2 = rxrpc_locate_data(call, skb,
 351                                                  &call->rxtx_annotations[ix],
 352                                                  &rx_pkt_offset, &rx_pkt_len);
 353                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq,
 354                                             rx_pkt_offset, rx_pkt_len, ret2);
 355                         if (ret2 < 0) {
 356                                 ret = ret2;
 357                                 goto out;
 358                         }
 359                 } else {
 360                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq,
 361                                             rx_pkt_offset, rx_pkt_len, 0);
 362                 }
 363
 364                 /* We have to handle short, empty and used-up DATA packets. */
 365                 remain = len - *_offset;
 366                 copy = rx_pkt_len;
 367                 if (copy > remain)
 368                         copy = remain;
 369                 if (copy > 0) {
 370                         ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
 371                                                       copy);
 372                         if (ret2 < 0) {
 373                                 ret = ret2;
 374                                 goto out;
 375                         }
 376
 377                         /* handle piecemeal consumption of data packets */
 378                         rx_pkt_offset += copy;
 379                         rx_pkt_len -= copy;
 380                         *_offset += copy;
 381                 }
 382
 383                 if (rx_pkt_len > 0) {
 384                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq,
 385                                             rx_pkt_offset, rx_pkt_len, 0);
 386                         ASSERTCMP(*_offset, ==, len);
 387                         ret = 0;
 388                         break;
 389                 }
 390
 391                 /* The whole packet has been transferred. */
 392                 last = sp->hdr.flags & RXRPC_LAST_PACKET;
 393                 if (!(flags & MSG_PEEK))
 394                         rxrpc_rotate_rx_window(call);
 395                 rx_pkt_offset = 0;
 396                 rx_pkt_len = 0;
 397
 398                 if (last) {
 399                         ASSERTCMP(seq, ==, READ_ONCE(call->rx_top));
 400                         ret = 1;
 401                         goto out;
 402                 }
 403
 404                 seq++;
 405         }
 406
 407 out:
 408         if (!(flags & MSG_PEEK)) {
 409                 call->rx_pkt_offset = rx_pkt_offset;
 410                 call->rx_pkt_len = rx_pkt_len;
 411         }
 412 done:
 413         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_data_return, seq,
 414                             rx_pkt_offset, rx_pkt_len, ret);
 415         return ret;
 416 }
 417
 418 /*
 419  * Receive a message from an RxRPC socket
 420  * - we need to be careful about two or more threads calling recvmsg
 421  *   simultaneously
 422  */
 423 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 424                   int flags)
 425 {
 426         struct rxrpc_call *call;
 427         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 428         struct list_head *l;
 429         size_t copied = 0;
 430         long timeo;
 431         int ret;
 432
 433         DEFINE_WAIT(wait);
 434
 435         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0, 0, 0, 0);
 436
 437         if (flags & (MSG_OOB | MSG_TRUNC))
 438                 return -EOPNOTSUPP;
 439
 440         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
 441
 442 try_again:
 443         lock_sock(&rx->sk);
 444
 445         /* Return immediately if a client socket has no outstanding calls */
 446         if (RB_EMPTY_ROOT(&rx->calls) &&
 447             list_empty(&rx->recvmsg_q) &&
 448             rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
 449                 release_sock(&rx->sk);
 450                 return -ENODATA;
 451         }
 452
 453         if (list_empty(&rx->recvmsg_q)) {
 454                 ret = -EWOULDBLOCK;
 455                 if (timeo == 0) {
 456                         call = NULL;
 457                         goto error_no_call;
 458                 }
 459
 460                 release_sock(&rx->sk);
 461
 462                 /* Wait for something to happen */
 463                 prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
 464                                           TASK_INTERRUPTIBLE);
 465                 ret = sock_error(&rx->sk);
 466                 if (ret)
 467                         goto wait_error;
 468
 469                 if (list_empty(&rx->recvmsg_q)) {
 470                         if (signal_pending(current))
 471                                 goto wait_interrupted;
 472                         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait,
 473                                             0, 0, 0, 0);
 474                         timeo = schedule_timeout(timeo);
 475                 }
 476                 finish_wait(sk_sleep(&rx->sk), &wait);
 477                 goto try_again;
 478         }
 479
 480         /* Find the next call and dequeue it if we're not just peeking.  If we
 481          * do dequeue it, that comes with a ref that we will need to release.
 482          */
 483         write_lock_bh(&rx->recvmsg_lock);
 484         l = rx->recvmsg_q.next;
 485         call = list_entry(l, struct rxrpc_call, recvmsg_link);
 486         if (!(flags & MSG_PEEK))
 487                 list_del_init(&call->recvmsg_link);
 488         else
 489                 rxrpc_get_call(call, rxrpc_call_got);
 490         write_unlock_bh(&rx->recvmsg_lock);
 491
 492         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0, 0, 0, 0);
 493
 494         /* We're going to drop the socket lock, so we need to lock the call
 495          * against interference by sendmsg.
 496          */
 497         if (!mutex_trylock(&call->user_mutex)) {
 498                 ret = -EWOULDBLOCK;
 499                 if (flags & MSG_DONTWAIT)
 500                         goto error_requeue_call;
 501                 ret = -ERESTARTSYS;
 502                 if (mutex_lock_interruptible(&call->user_mutex) < 0)
 503                         goto error_requeue_call;
 504         }
 505
 506         release_sock(&rx->sk);
 507
 508         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
 509                 BUG();
 510
 511         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
 512                 if (flags & MSG_CMSG_COMPAT) {
 513                         unsigned int id32 = call->user_call_ID;
 514
 515                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 516                                        sizeof(unsigned int), &id32);
 517                 } else {
 518                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 519                                        sizeof(unsigned long),
 520                                        &call->user_call_ID);
 521                 }
 522                 if (ret < 0)
 523                         goto error_unlock_call;
 524         }
 525
 526         if (msg->msg_name) {
 527                 struct sockaddr_rxrpc *srx = msg->msg_name;
 528                 size_t len = sizeof(call->peer->srx);
 529
 530                 memcpy(msg->msg_name, &call->peer->srx, len);
 531                 srx->srx_service = call->service_id;
 532                 msg->msg_namelen = len;
 533         }
 534
 535         switch (READ_ONCE(call->state)) {
 536         case RXRPC_CALL_SERVER_ACCEPTING:
 537                 ret = rxrpc_recvmsg_new_call(rx, call, msg, flags);
 538                 break;
 539         case RXRPC_CALL_CLIENT_RECV_REPLY:
 540         case RXRPC_CALL_SERVER_RECV_REQUEST:
 541         case RXRPC_CALL_SERVER_ACK_REQUEST:
 542                 ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
 543                                          flags, &copied);
 544                 if (ret == -EAGAIN)
 545                         ret = 0;
 546
 547                 if (after(call->rx_top, call->rx_hard_ack) &&
 548                     call->rxtx_buffer[(call->rx_hard_ack + 1) & RXRPC_RXTX_BUFF_MASK])
 549                         rxrpc_notify_socket(call);
 550                 break;
 551         default:
 552                 ret = 0;
 553                 break;
 554         }
 555
 556         if (ret < 0)
 557                 goto error_unlock_call;
 558
 559         if (call->state == RXRPC_CALL_COMPLETE) {
 560                 ret = rxrpc_recvmsg_term(call, msg);
 561                 if (ret < 0)
 562                         goto error_unlock_call;
 563                 if (!(flags & MSG_PEEK))
 564                         rxrpc_release_call(rx, call);
 565                 msg->msg_flags |= MSG_EOR;
 566                 ret = 1;
 567         }
 568
 569         if (ret == 0)
 570                 msg->msg_flags |= MSG_MORE;
 571         else
 572                 msg->msg_flags &= ~MSG_MORE;
 573         ret = copied;
 574
 575 error_unlock_call:
 576         mutex_unlock(&call->user_mutex);
 577         rxrpc_put_call(call, rxrpc_call_put);
 578         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 579         return ret;
 580
 581 error_requeue_call:
 582         if (!(flags & MSG_PEEK)) {
 583                 write_lock_bh(&rx->recvmsg_lock);
 584                 list_add(&call->recvmsg_link, &rx->recvmsg_q);
 585                 write_unlock_bh(&rx->recvmsg_lock);
 586                 trace_rxrpc_recvmsg(call, rxrpc_recvmsg_requeue, 0, 0, 0, 0);
 587         } else {
 588                 rxrpc_put_call(call, rxrpc_call_put);
 589         }
 590 error_no_call:
 591         release_sock(&rx->sk);
 592         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 593         return ret;
 594
 595 wait_interrupted:
 596         ret = sock_intr_errno(timeo);
 597 wait_error:
 598         finish_wait(sk_sleep(&rx->sk), &wait);
 599         call = NULL;
 600         goto error_no_call;
 601 }
 602
 603 /**
 604  * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 605  * @sock: The socket that the call exists on
 606  * @call: The call to send data through
 607  * @buf: The buffer to receive into
 608  * @size: The size of the buffer, including data already read
 609  * @_offset: The running offset into the buffer.
 610  * @want_more: True if more data is expected to be read
 611  * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 612  * @_service: Where to store the actual service ID (may be upgraded)
 613  *
 614  * Allow a kernel service to receive data and pick up information about the
 615  * state of a call.  Returns 0 if got what was asked for and there's more
 616  * available, 1 if we got what was asked for and we're at the end of the data
 617  * and -EAGAIN if we need more data.
 618  *
 619  * Note that we may return -EAGAIN to drain empty packets at the end of the
 620  * data, even if we've already copied over the requested data.
 621  *
 622  * This function adds the amount it transfers to *_offset, so this should be
 623  * precleared as appropriate.  Note that the amount remaining in the buffer is
 624  * taken to be size - *_offset.
 625  *
 626  * *_abort should also be initialised to 0.
 627  */
 628 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 629                            void *buf, size_t size, size_t *_offset,
 630                            bool want_more, u32 *_abort, u16 *_service)
 631 {
 632         struct iov_iter iter;
 633         struct kvec iov;
 634         int ret;
 635
 636         _enter("{%d,%s},%zu/%zu,%d",
 637                call->debug_id, rxrpc_call_states[call->state],
 638                *_offset, size, want_more);
 639
 640         ASSERTCMP(*_offset, <=, size);
 641         ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_ACCEPTING);
 642
 643         iov.iov_base = buf + *_offset;
 644         iov.iov_len = size - *_offset;
 645         iov_iter_kvec(&iter, ITER_KVEC | READ, &iov, 1, size - *_offset);
 646
 647         mutex_lock(&call->user_mutex);
 648
 649         switch (READ_ONCE(call->state)) {
 650         case RXRPC_CALL_CLIENT_RECV_REPLY:
 651         case RXRPC_CALL_SERVER_RECV_REQUEST:
 652         case RXRPC_CALL_SERVER_ACK_REQUEST:
 653                 ret = rxrpc_recvmsg_data(sock, call, NULL, &iter, size, 0,
 654                                          _offset);
 655                 if (ret < 0)
 656                         goto out;
 657
 658                 /* We can only reach here with a partially full buffer if we
 659                  * have reached the end of the data.  We must otherwise have a
 660                  * full buffer or have been given -EAGAIN.
 661                  */
 662                 if (ret == 1) {
 663                         if (*_offset < size)
 664                                 goto short_data;
 665                         if (!want_more)
 666                                 goto read_phase_complete;
 667                         ret = 0;
 668                         goto out;
 669                 }
 670
 671                 if (!want_more)
 672                         goto excess_data;
 673                 goto out;
 674
 675         case RXRPC_CALL_COMPLETE:
 676                 goto call_complete;
 677
 678         default:
 679                 ret = -EINPROGRESS;
 680                 goto out;
 681         }
 682
 683 read_phase_complete:
 684         ret = 1;
 685 out:
 686         if (_service)
 687                 *_service = call->service_id;
 688         mutex_unlock(&call->user_mutex);
 689         _leave(" = %d [%zu,%d]", ret, *_offset, *_abort);
 690         return ret;
 691
 692 short_data:
 693         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("short_data"));
 694         ret = -EBADMSG;
 695         goto out;
 696 excess_data:
 697         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("excess_data"));
 698         ret = -EMSGSIZE;
 699         goto out;
 700 call_complete:
 701         *_abort = call->abort_code;
 702         ret = call->error;
 703         if (call->completion == RXRPC_CALL_SUCCEEDED) {
 704                 ret = 1;
 705                 if (size > 0)
 706                         ret = -ECONNRESET;
 707         }
 708         goto out;
 709 }
 710 EXPORT_SYMBOL(rxrpc_kernel_recv_data);