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                 write_unlock_bh(&call->state_lock);
 155                 break;
 156
 157         case RXRPC_CALL_SERVER_RECV_REQUEST:
 158                 call->tx_phase = true;
 159                 call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
 160                 call->ack_at = call->expire_at;
 161                 write_unlock_bh(&call->state_lock);
 162                 rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, 0, serial, false, true,
 163                                   rxrpc_propose_ack_processing_op);
 164                 break;
 165         default:
 166                 write_unlock_bh(&call->state_lock);
 167                 break;
 168         }
 169 }
 170
 171 /*
 172  * Discard a packet we've used up and advance the Rx window by one.
 173  */
 174 static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
 175 {
 176         struct rxrpc_skb_priv *sp;
 177         struct sk_buff *skb;
 178         rxrpc_serial_t serial;
 179         rxrpc_seq_t hard_ack, top;
 180         u8 flags;
 181         int ix;
 182
 183         _enter("%d", call->debug_id);
 184
 185         hard_ack = call->rx_hard_ack;
 186         top = smp_load_acquire(&call->rx_top);
 187         ASSERT(before(hard_ack, top));
 188
 189         hard_ack++;
 190         ix = hard_ack & RXRPC_RXTX_BUFF_MASK;
 191         skb = call->rxtx_buffer[ix];
 192         rxrpc_see_skb(skb, rxrpc_skb_rx_rotated);
 193         sp = rxrpc_skb(skb);
 194         flags = sp->hdr.flags;
 195         serial = sp->hdr.serial;
 196         if (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO)
 197                 serial += (call->rxtx_annotations[ix] & RXRPC_RX_ANNO_JUMBO) - 1;
 198
 199         call->rxtx_buffer[ix] = NULL;
 200         call->rxtx_annotations[ix] = 0;
 201         /* Barrier against rxrpc_input_data(). */
 202         smp_store_release(&call->rx_hard_ack, hard_ack);
 203
 204         rxrpc_free_skb(skb, rxrpc_skb_rx_freed);
 205
 206         _debug("%u,%u,%02x", hard_ack, top, flags);
 207         trace_rxrpc_receive(call, rxrpc_receive_rotate, serial, hard_ack);
 208         if (flags & RXRPC_LAST_PACKET) {
 209                 rxrpc_end_rx_phase(call, serial);
 210         } else {
 211                 /* Check to see if there's an ACK that needs sending. */
 212                 if (after_eq(hard_ack, call->ackr_consumed + 2) ||
 213                     after_eq(top, call->ackr_seen + 2) ||
 214                     (hard_ack == top && after(hard_ack, call->ackr_consumed)))
 215                         rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, 0, serial,
 216                                           true, false,
 217                                           rxrpc_propose_ack_rotate_rx);
 218                 if (call->ackr_reason)
 219                         rxrpc_send_ack_packet(call, false);
 220         }
 221 }
 222
 223 /*
 224  * Decrypt and verify a (sub)packet.  The packet's length may be changed due to
 225  * padding, but if this is the case, the packet length will be resident in the
 226  * socket buffer.  Note that we can't modify the master skb info as the skb may
 227  * be the home to multiple subpackets.
 228  */
 229 static int rxrpc_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
 230                                u8 annotation,
 231                                unsigned int offset, unsigned int len)
 232 {
 233         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 234         rxrpc_seq_t seq = sp->hdr.seq;
 235         u16 cksum = sp->hdr.cksum;
 236
 237         _enter("");
 238
 239         /* For all but the head jumbo subpacket, the security checksum is in a
 240          * jumbo header immediately prior to the data.
 241          */
 242         if ((annotation & RXRPC_RX_ANNO_JUMBO) > 1) {
 243                 __be16 tmp;
 244                 if (skb_copy_bits(skb, offset - 2, &tmp, 2) < 0)
 245                         BUG();
 246                 cksum = ntohs(tmp);
 247                 seq += (annotation & RXRPC_RX_ANNO_JUMBO) - 1;
 248         }
 249
 250         return call->conn->security->verify_packet(call, skb, offset, len,
 251                                                    seq, cksum);
 252 }
 253
 254 /*
 255  * Locate the data within a packet.  This is complicated by:
 256  *
 257  * (1) An skb may contain a jumbo packet - so we have to find the appropriate
 258  *     subpacket.
 259  *
 260  * (2) The (sub)packets may be encrypted and, if so, the encrypted portion
 261  *     contains an extra header which includes the true length of the data,
 262  *     excluding any encrypted padding.
 263  */
 264 static int rxrpc_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
 265                              u8 *_annotation,
 266                              unsigned int *_offset, unsigned int *_len)
 267 {
 268         unsigned int offset = sizeof(struct rxrpc_wire_header);
 269         unsigned int len = *_len;
 270         int ret;
 271         u8 annotation = *_annotation;
 272
 273         /* Locate the subpacket */
 274         len = skb->len - offset;
 275         if ((annotation & RXRPC_RX_ANNO_JUMBO) > 0) {
 276                 offset += (((annotation & RXRPC_RX_ANNO_JUMBO) - 1) *
 277                            RXRPC_JUMBO_SUBPKTLEN);
 278                 len = (annotation & RXRPC_RX_ANNO_JLAST) ?
 279                         skb->len - offset : RXRPC_JUMBO_SUBPKTLEN;
 280         }
 281
 282         if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
 283                 ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
 284                 if (ret < 0)
 285                         return ret;
 286                 *_annotation |= RXRPC_RX_ANNO_VERIFIED;
 287         }
 288
 289         *_offset = offset;
 290         *_len = len;
 291         call->conn->security->locate_data(call, skb, _offset, _len);
 292         return 0;
 293 }
 294
 295 /*
 296  * Deliver messages to a call.  This keeps processing packets until the buffer
 297  * is filled and we find either more DATA (returns 0) or the end of the DATA
 298  * (returns 1).  If more packets are required, it returns -EAGAIN.
 299  */
 300 static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 301                               struct msghdr *msg, struct iov_iter *iter,
 302                               size_t len, int flags, size_t *_offset)
 303 {
 304         struct rxrpc_skb_priv *sp;
 305         struct sk_buff *skb;
 306         rxrpc_seq_t hard_ack, top, seq;
 307         size_t remain;
 308         bool last;
 309         unsigned int rx_pkt_offset, rx_pkt_len;
 310         int ix, copy, ret = -EAGAIN, ret2;
 311
 312         rx_pkt_offset = call->rx_pkt_offset;
 313         rx_pkt_len = call->rx_pkt_len;
 314
 315         if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
 316                 seq = call->rx_hard_ack;
 317                 ret = 1;
 318                 goto done;
 319         }
 320
 321         /* Barriers against rxrpc_input_data(). */
 322         hard_ack = call->rx_hard_ack;
 323         top = smp_load_acquire(&call->rx_top);
 324         for (seq = hard_ack + 1; before_eq(seq, top); seq++) {
 325                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 326                 skb = call->rxtx_buffer[ix];
 327                 if (!skb) {
 328                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq,
 329                                             rx_pkt_offset, rx_pkt_len, 0);
 330                         break;
 331                 }
 332                 smp_rmb();
 333                 rxrpc_see_skb(skb, rxrpc_skb_rx_seen);
 334                 sp = rxrpc_skb(skb);
 335
 336                 if (!(flags & MSG_PEEK))
 337                         trace_rxrpc_receive(call, rxrpc_receive_front,
 338                                             sp->hdr.serial, seq);
 339
 340                 if (msg)
 341                         sock_recv_timestamp(msg, sock->sk, skb);
 342
 343                 if (rx_pkt_offset == 0) {
 344                         ret2 = rxrpc_locate_data(call, skb,
 345                                                  &call->rxtx_annotations[ix],
 346                                                  &rx_pkt_offset, &rx_pkt_len);
 347                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq,
 348                                             rx_pkt_offset, rx_pkt_len, ret2);
 349                         if (ret2 < 0) {
 350                                 ret = ret2;
 351                                 goto out;
 352                         }
 353                 } else {
 354                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq,
 355                                             rx_pkt_offset, rx_pkt_len, 0);
 356                 }
 357
 358                 /* We have to handle short, empty and used-up DATA packets. */
 359                 remain = len - *_offset;
 360                 copy = rx_pkt_len;
 361                 if (copy > remain)
 362                         copy = remain;
 363                 if (copy > 0) {
 364                         ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
 365                                                       copy);
 366                         if (ret2 < 0) {
 367                                 ret = ret2;
 368                                 goto out;
 369                         }
 370
 371                         /* handle piecemeal consumption of data packets */
 372                         rx_pkt_offset += copy;
 373                         rx_pkt_len -= copy;
 374                         *_offset += copy;
 375                 }
 376
 377                 if (rx_pkt_len > 0) {
 378                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq,
 379                                             rx_pkt_offset, rx_pkt_len, 0);
 380                         ASSERTCMP(*_offset, ==, len);
 381                         ret = 0;
 382                         break;
 383                 }
 384
 385                 /* The whole packet has been transferred. */
 386                 last = sp->hdr.flags & RXRPC_LAST_PACKET;
 387                 if (!(flags & MSG_PEEK))
 388                         rxrpc_rotate_rx_window(call);
 389                 rx_pkt_offset = 0;
 390                 rx_pkt_len = 0;
 391
 392                 if (last) {
 393                         ASSERTCMP(seq, ==, READ_ONCE(call->rx_top));
 394                         ret = 1;
 395                         goto out;
 396                 }
 397         }
 398
 399 out:
 400         if (!(flags & MSG_PEEK)) {
 401                 call->rx_pkt_offset = rx_pkt_offset;
 402                 call->rx_pkt_len = rx_pkt_len;
 403         }
 404 done:
 405         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_data_return, seq,
 406                             rx_pkt_offset, rx_pkt_len, ret);
 407         return ret;
 408 }
 409
 410 /*
 411  * Receive a message from an RxRPC socket
 412  * - we need to be careful about two or more threads calling recvmsg
 413  *   simultaneously
 414  */
 415 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 416                   int flags)
 417 {
 418         struct rxrpc_call *call;
 419         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 420         struct list_head *l;
 421         size_t copied = 0;
 422         long timeo;
 423         int ret;
 424
 425         DEFINE_WAIT(wait);
 426
 427         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0, 0, 0, 0);
 428
 429         if (flags & (MSG_OOB | MSG_TRUNC))
 430                 return -EOPNOTSUPP;
 431
 432         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
 433
 434 try_again:
 435         lock_sock(&rx->sk);
 436
 437         /* Return immediately if a client socket has no outstanding calls */
 438         if (RB_EMPTY_ROOT(&rx->calls) &&
 439             list_empty(&rx->recvmsg_q) &&
 440             rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
 441                 release_sock(&rx->sk);
 442                 return -ENODATA;
 443         }
 444
 445         if (list_empty(&rx->recvmsg_q)) {
 446                 ret = -EWOULDBLOCK;
 447                 if (timeo == 0) {
 448                         call = NULL;
 449                         goto error_no_call;
 450                 }
 451
 452                 release_sock(&rx->sk);
 453
 454                 /* Wait for something to happen */
 455                 prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
 456                                           TASK_INTERRUPTIBLE);
 457                 ret = sock_error(&rx->sk);
 458                 if (ret)
 459                         goto wait_error;
 460
 461                 if (list_empty(&rx->recvmsg_q)) {
 462                         if (signal_pending(current))
 463                                 goto wait_interrupted;
 464                         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait,
 465                                             0, 0, 0, 0);
 466                         timeo = schedule_timeout(timeo);
 467                 }
 468                 finish_wait(sk_sleep(&rx->sk), &wait);
 469                 goto try_again;
 470         }
 471
 472         /* Find the next call and dequeue it if we're not just peeking.  If we
 473          * do dequeue it, that comes with a ref that we will need to release.
 474          */
 475         write_lock_bh(&rx->recvmsg_lock);
 476         l = rx->recvmsg_q.next;
 477         call = list_entry(l, struct rxrpc_call, recvmsg_link);
 478         if (!(flags & MSG_PEEK))
 479                 list_del_init(&call->recvmsg_link);
 480         else
 481                 rxrpc_get_call(call, rxrpc_call_got);
 482         write_unlock_bh(&rx->recvmsg_lock);
 483
 484         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0, 0, 0, 0);
 485
 486         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
 487                 BUG();
 488
 489         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
 490                 if (flags & MSG_CMSG_COMPAT) {
 491                         unsigned int id32 = call->user_call_ID;
 492
 493                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 494                                        sizeof(unsigned int), &id32);
 495                 } else {
 496                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 497                                        sizeof(unsigned long),
 498                                        &call->user_call_ID);
 499                 }
 500                 if (ret < 0)
 501                         goto error;
 502         }
 503
 504         if (msg->msg_name) {
 505                 size_t len = sizeof(call->conn->params.peer->srx);
 506                 memcpy(msg->msg_name, &call->conn->params.peer->srx, len);
 507                 msg->msg_namelen = len;
 508         }
 509
 510         switch (call->state) {
 511         case RXRPC_CALL_SERVER_ACCEPTING:
 512                 ret = rxrpc_recvmsg_new_call(rx, call, msg, flags);
 513                 break;
 514         case RXRPC_CALL_CLIENT_RECV_REPLY:
 515         case RXRPC_CALL_SERVER_RECV_REQUEST:
 516         case RXRPC_CALL_SERVER_ACK_REQUEST:
 517                 ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
 518                                          flags, &copied);
 519                 if (ret == -EAGAIN)
 520                         ret = 0;
 521
 522                 if (after(call->rx_top, call->rx_hard_ack) &&
 523                     call->rxtx_buffer[(call->rx_hard_ack + 1) & RXRPC_RXTX_BUFF_MASK])
 524                         rxrpc_notify_socket(call);
 525                 break;
 526         default:
 527                 ret = 0;
 528                 break;
 529         }
 530
 531         if (ret < 0)
 532                 goto error;
 533
 534         if (call->state == RXRPC_CALL_COMPLETE) {
 535                 ret = rxrpc_recvmsg_term(call, msg);
 536                 if (ret < 0)
 537                         goto error;
 538                 if (!(flags & MSG_PEEK))
 539                         rxrpc_release_call(rx, call);
 540                 msg->msg_flags |= MSG_EOR;
 541                 ret = 1;
 542         }
 543
 544         if (ret == 0)
 545                 msg->msg_flags |= MSG_MORE;
 546         else
 547                 msg->msg_flags &= ~MSG_MORE;
 548         ret = copied;
 549
 550 error:
 551         rxrpc_put_call(call, rxrpc_call_put);
 552 error_no_call:
 553         release_sock(&rx->sk);
 554         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 555         return ret;
 556
 557 wait_interrupted:
 558         ret = sock_intr_errno(timeo);
 559 wait_error:
 560         finish_wait(sk_sleep(&rx->sk), &wait);
 561         call = NULL;
 562         goto error_no_call;
 563 }
 564
 565 /**
 566  * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 567  * @sock: The socket that the call exists on
 568  * @call: The call to send data through
 569  * @buf: The buffer to receive into
 570  * @size: The size of the buffer, including data already read
 571  * @_offset: The running offset into the buffer.
 572  * @want_more: True if more data is expected to be read
 573  * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 574  *
 575  * Allow a kernel service to receive data and pick up information about the
 576  * state of a call.  Returns 0 if got what was asked for and there's more
 577  * available, 1 if we got what was asked for and we're at the end of the data
 578  * and -EAGAIN if we need more data.
 579  *
 580  * Note that we may return -EAGAIN to drain empty packets at the end of the
 581  * data, even if we've already copied over the requested data.
 582  *
 583  * This function adds the amount it transfers to *_offset, so this should be
 584  * precleared as appropriate.  Note that the amount remaining in the buffer is
 585  * taken to be size - *_offset.
 586  *
 587  * *_abort should also be initialised to 0.
 588  */
 589 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 590                            void *buf, size_t size, size_t *_offset,
 591                            bool want_more, u32 *_abort)
 592 {
 593         struct iov_iter iter;
 594         struct kvec iov;
 595         int ret;
 596
 597         _enter("{%d,%s},%zu/%zu,%d",
 598                call->debug_id, rxrpc_call_states[call->state],
 599                *_offset, size, want_more);
 600
 601         ASSERTCMP(*_offset, <=, size);
 602         ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_ACCEPTING);
 603
 604         iov.iov_base = buf + *_offset;
 605         iov.iov_len = size - *_offset;
 606         iov_iter_kvec(&iter, ITER_KVEC | READ, &iov, 1, size - *_offset);
 607
 608         lock_sock(sock->sk);
 609
 610         switch (call->state) {
 611         case RXRPC_CALL_CLIENT_RECV_REPLY:
 612         case RXRPC_CALL_SERVER_RECV_REQUEST:
 613         case RXRPC_CALL_SERVER_ACK_REQUEST:
 614                 ret = rxrpc_recvmsg_data(sock, call, NULL, &iter, size, 0,
 615                                          _offset);
 616                 if (ret < 0)
 617                         goto out;
 618
 619                 /* We can only reach here with a partially full buffer if we
 620                  * have reached the end of the data.  We must otherwise have a
 621                  * full buffer or have been given -EAGAIN.
 622                  */
 623                 if (ret == 1) {
 624                         if (*_offset < size)
 625                                 goto short_data;
 626                         if (!want_more)
 627                                 goto read_phase_complete;
 628                         ret = 0;
 629                         goto out;
 630                 }
 631
 632                 if (!want_more)
 633                         goto excess_data;
 634                 goto out;
 635
 636         case RXRPC_CALL_COMPLETE:
 637                 goto call_complete;
 638
 639         default:
 640                 ret = -EINPROGRESS;
 641                 goto out;
 642         }
 643
 644 read_phase_complete:
 645         ret = 1;
 646 out:
 647         release_sock(sock->sk);
 648         _leave(" = %d [%zu,%d]", ret, *_offset, *_abort);
 649         return ret;
 650
 651 short_data:
 652         ret = -EBADMSG;
 653         goto out;
 654 excess_data:
 655         ret = -EMSGSIZE;
 656         goto out;
 657 call_complete:
 658         *_abort = call->abort_code;
 659         ret = -call->error;
 660         if (call->completion == RXRPC_CALL_SUCCEEDED) {
 661                 ret = 1;
 662                 if (size > 0)
 663                         ret = -ECONNRESET;
 664         }
 665         goto out;
 666 }
 667 EXPORT_SYMBOL(rxrpc_kernel_recv_data);