net/rxrpc/recvmsg.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* RxRPC recvmsg() implementation
   3  *
   4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/net.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/export.h>
  13 #include <linux/sched/signal.h>
  14
  15 #include <net/sock.h>
  16 #include <net/af_rxrpc.h>
  17 #include "ar-internal.h"
  18
  19 /*
  20  * Post a call for attention by the socket or kernel service.  Further
  21  * notifications are suppressed by putting recvmsg_link on a dummy queue.
  22  */
  23 void rxrpc_notify_socket(struct rxrpc_call *call)
  24 {
  25         struct rxrpc_sock *rx;
  26         struct sock *sk;
  27
  28         _enter("%d", call->debug_id);
  29
  30         if (!list_empty(&call->recvmsg_link))
  31                 return;
  32
  33         rcu_read_lock();
  34
  35         rx = rcu_dereference(call->socket);
  36         sk = &rx->sk;
  37         if (rx && sk->sk_state < RXRPC_CLOSE) {
  38                 if (call->notify_rx) {
  39                         spin_lock_bh(&call->notify_lock);
  40                         call->notify_rx(sk, call, call->user_call_ID);
  41                         spin_unlock_bh(&call->notify_lock);
  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, false, true,
 145                                   rxrpc_propose_ack_terminal_ack);
 146                 //rxrpc_send_ack_packet(call, false, NULL);
 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->expect_req_by = jiffies + MAX_JIFFY_OFFSET;
 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, true,
 217                                           rxrpc_propose_ack_rotate_rx);
 218                 if (call->ackr_reason && call->ackr_reason != RXRPC_ACK_DELAY)
 219                         rxrpc_send_ack_packet(call, false, NULL);
 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;
 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         if (test_and_clear_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags) &&
 313             call->ackr_reason)
 314                 rxrpc_send_ack_packet(call, false, NULL);
 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         if (ret == -EAGAIN)
 416                 set_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags);
 417         return ret;
 418 }
 419
 420 /*
 421  * Receive a message from an RxRPC socket
 422  * - we need to be careful about two or more threads calling recvmsg
 423  *   simultaneously
 424  */
 425 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 426                   int flags)
 427 {
 428         struct rxrpc_call *call;
 429         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 430         struct list_head *l;
 431         size_t copied = 0;
 432         long timeo;
 433         int ret;
 434
 435         DEFINE_WAIT(wait);
 436
 437         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0, 0, 0, 0);
 438
 439         if (flags & (MSG_OOB | MSG_TRUNC))
 440                 return -EOPNOTSUPP;
 441
 442         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
 443
 444 try_again:
 445         lock_sock(&rx->sk);
 446
 447         /* Return immediately if a client socket has no outstanding calls */
 448         if (RB_EMPTY_ROOT(&rx->calls) &&
 449             list_empty(&rx->recvmsg_q) &&
 450             rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
 451                 release_sock(&rx->sk);
 452                 return -ENODATA;
 453         }
 454
 455         if (list_empty(&rx->recvmsg_q)) {
 456                 ret = -EWOULDBLOCK;
 457                 if (timeo == 0) {
 458                         call = NULL;
 459                         goto error_no_call;
 460                 }
 461
 462                 release_sock(&rx->sk);
 463
 464                 /* Wait for something to happen */
 465                 prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
 466                                           TASK_INTERRUPTIBLE);
 467                 ret = sock_error(&rx->sk);
 468                 if (ret)
 469                         goto wait_error;
 470
 471                 if (list_empty(&rx->recvmsg_q)) {
 472                         if (signal_pending(current))
 473                                 goto wait_interrupted;
 474                         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait,
 475                                             0, 0, 0, 0);
 476                         timeo = schedule_timeout(timeo);
 477                 }
 478                 finish_wait(sk_sleep(&rx->sk), &wait);
 479                 goto try_again;
 480         }
 481
 482         /* Find the next call and dequeue it if we're not just peeking.  If we
 483          * do dequeue it, that comes with a ref that we will need to release.
 484          */
 485         write_lock_bh(&rx->recvmsg_lock);
 486         l = rx->recvmsg_q.next;
 487         call = list_entry(l, struct rxrpc_call, recvmsg_link);
 488         if (!(flags & MSG_PEEK))
 489                 list_del_init(&call->recvmsg_link);
 490         else
 491                 rxrpc_get_call(call, rxrpc_call_got);
 492         write_unlock_bh(&rx->recvmsg_lock);
 493
 494         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0, 0, 0, 0);
 495
 496         /* We're going to drop the socket lock, so we need to lock the call
 497          * against interference by sendmsg.
 498          */
 499         if (!mutex_trylock(&call->user_mutex)) {
 500                 ret = -EWOULDBLOCK;
 501                 if (flags & MSG_DONTWAIT)
 502                         goto error_requeue_call;
 503                 ret = -ERESTARTSYS;
 504                 if (mutex_lock_interruptible(&call->user_mutex) < 0)
 505                         goto error_requeue_call;
 506         }
 507
 508         release_sock(&rx->sk);
 509
 510         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
 511                 BUG();
 512
 513         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
 514                 if (flags & MSG_CMSG_COMPAT) {
 515                         unsigned int id32 = call->user_call_ID;
 516
 517                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 518                                        sizeof(unsigned int), &id32);
 519                 } else {
 520                         unsigned long idl = call->user_call_ID;
 521
 522                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 523                                        sizeof(unsigned long), &idl);
 524                 }
 525                 if (ret < 0)
 526                         goto error_unlock_call;
 527         }
 528
 529         if (msg->msg_name) {
 530                 struct sockaddr_rxrpc *srx = msg->msg_name;
 531                 size_t len = sizeof(call->peer->srx);
 532
 533                 memcpy(msg->msg_name, &call->peer->srx, len);
 534                 srx->srx_service = call->service_id;
 535                 msg->msg_namelen = len;
 536         }
 537
 538         switch (READ_ONCE(call->state)) {
 539         case RXRPC_CALL_SERVER_ACCEPTING:
 540                 ret = rxrpc_recvmsg_new_call(rx, call, msg, flags);
 541                 break;
 542         case RXRPC_CALL_CLIENT_RECV_REPLY:
 543         case RXRPC_CALL_SERVER_RECV_REQUEST:
 544         case RXRPC_CALL_SERVER_ACK_REQUEST:
 545                 ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
 546                                          flags, &copied);
 547                 if (ret == -EAGAIN)
 548                         ret = 0;
 549
 550                 if (after(call->rx_top, call->rx_hard_ack) &&
 551                     call->rxtx_buffer[(call->rx_hard_ack + 1) & RXRPC_RXTX_BUFF_MASK])
 552                         rxrpc_notify_socket(call);
 553                 break;
 554         default:
 555                 ret = 0;
 556                 break;
 557         }
 558
 559         if (ret < 0)
 560                 goto error_unlock_call;
 561
 562         if (call->state == RXRPC_CALL_COMPLETE) {
 563                 ret = rxrpc_recvmsg_term(call, msg);
 564                 if (ret < 0)
 565                         goto error_unlock_call;
 566                 if (!(flags & MSG_PEEK))
 567                         rxrpc_release_call(rx, call);
 568                 msg->msg_flags |= MSG_EOR;
 569                 ret = 1;
 570         }
 571
 572         if (ret == 0)
 573                 msg->msg_flags |= MSG_MORE;
 574         else
 575                 msg->msg_flags &= ~MSG_MORE;
 576         ret = copied;
 577
 578 error_unlock_call:
 579         mutex_unlock(&call->user_mutex);
 580         rxrpc_put_call(call, rxrpc_call_put);
 581         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 582         return ret;
 583
 584 error_requeue_call:
 585         if (!(flags & MSG_PEEK)) {
 586                 write_lock_bh(&rx->recvmsg_lock);
 587                 list_add(&call->recvmsg_link, &rx->recvmsg_q);
 588                 write_unlock_bh(&rx->recvmsg_lock);
 589                 trace_rxrpc_recvmsg(call, rxrpc_recvmsg_requeue, 0, 0, 0, 0);
 590         } else {
 591                 rxrpc_put_call(call, rxrpc_call_put);
 592         }
 593 error_no_call:
 594         release_sock(&rx->sk);
 595 error_trace:
 596         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 597         return ret;
 598
 599 wait_interrupted:
 600         ret = sock_intr_errno(timeo);
 601 wait_error:
 602         finish_wait(sk_sleep(&rx->sk), &wait);
 603         call = NULL;
 604         goto error_trace;
 605 }
 606
 607 /**
 608  * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 609  * @sock: The socket that the call exists on
 610  * @call: The call to send data through
 611  * @iter: The buffer to receive into
 612  * @want_more: True if more data is expected to be read
 613  * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 614  * @_service: Where to store the actual service ID (may be upgraded)
 615  *
 616  * Allow a kernel service to receive data and pick up information about the
 617  * state of a call.  Returns 0 if got what was asked for and there's more
 618  * available, 1 if we got what was asked for and we're at the end of the data
 619  * and -EAGAIN if we need more data.
 620  *
 621  * Note that we may return -EAGAIN to drain empty packets at the end of the
 622  * data, even if we've already copied over the requested data.
 623  *
 624  * *_abort should also be initialised to 0.
 625  */
 626 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 627                            struct iov_iter *iter,
 628                            bool want_more, u32 *_abort, u16 *_service)
 629 {
 630         size_t offset = 0;
 631         int ret;
 632
 633         _enter("{%d,%s},%zu,%d",
 634                call->debug_id, rxrpc_call_states[call->state],
 635                iov_iter_count(iter), want_more);
 636
 637         ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_ACCEPTING);
 638
 639         mutex_lock(&call->user_mutex);
 640
 641         switch (READ_ONCE(call->state)) {
 642         case RXRPC_CALL_CLIENT_RECV_REPLY:
 643         case RXRPC_CALL_SERVER_RECV_REQUEST:
 644         case RXRPC_CALL_SERVER_ACK_REQUEST:
 645                 ret = rxrpc_recvmsg_data(sock, call, NULL, iter,
 646                                          iov_iter_count(iter), 0,
 647                                          &offset);
 648                 if (ret < 0)
 649                         goto out;
 650
 651                 /* We can only reach here with a partially full buffer if we
 652                  * have reached the end of the data.  We must otherwise have a
 653                  * full buffer or have been given -EAGAIN.
 654                  */
 655                 if (ret == 1) {
 656                         if (iov_iter_count(iter) > 0)
 657                                 goto short_data;
 658                         if (!want_more)
 659                                 goto read_phase_complete;
 660                         ret = 0;
 661                         goto out;
 662                 }
 663
 664                 if (!want_more)
 665                         goto excess_data;
 666                 goto out;
 667
 668         case RXRPC_CALL_COMPLETE:
 669                 goto call_complete;
 670
 671         default:
 672                 ret = -EINPROGRESS;
 673                 goto out;
 674         }
 675
 676 read_phase_complete:
 677         ret = 1;
 678 out:
 679         switch (call->ackr_reason) {
 680         case RXRPC_ACK_IDLE:
 681                 break;
 682         case RXRPC_ACK_DELAY:
 683                 if (ret != -EAGAIN)
 684                         break;
 685                 /* Fall through */
 686         default:
 687                 rxrpc_send_ack_packet(call, false, NULL);
 688         }
 689
 690         if (_service)
 691                 *_service = call->service_id;
 692         mutex_unlock(&call->user_mutex);
 693         _leave(" = %d [%zu,%d]", ret, iov_iter_count(iter), *_abort);
 694         return ret;
 695
 696 short_data:
 697         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("short_data"));
 698         ret = -EBADMSG;
 699         goto out;
 700 excess_data:
 701         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("excess_data"));
 702         ret = -EMSGSIZE;
 703         goto out;
 704 call_complete:
 705         *_abort = call->abort_code;
 706         ret = call->error;
 707         if (call->completion == RXRPC_CALL_SUCCEEDED) {
 708                 ret = 1;
 709                 if (iov_iter_count(iter) > 0)
 710                         ret = -ECONNRESET;
 711         }
 712         goto out;
 713 }
 714 EXPORT_SYMBOL(rxrpc_kernel_recv_data);
 715
 716 /**
 717  * rxrpc_kernel_get_reply_time - Get timestamp on first reply packet
 718  * @sock: The socket that the call exists on
 719  * @call: The call to query
 720  * @_ts: Where to put the timestamp
 721  *
 722  * Retrieve the timestamp from the first DATA packet of the reply if it is
 723  * in the ring.  Returns true if successful, false if not.
 724  */
 725 bool rxrpc_kernel_get_reply_time(struct socket *sock, struct rxrpc_call *call,
 726                                  ktime_t *_ts)
 727 {
 728         struct sk_buff *skb;
 729         rxrpc_seq_t hard_ack, top, seq;
 730         bool success = false;
 731
 732         mutex_lock(&call->user_mutex);
 733
 734         if (READ_ONCE(call->state) != RXRPC_CALL_CLIENT_RECV_REPLY)
 735                 goto out;
 736
 737         hard_ack = call->rx_hard_ack;
 738         if (hard_ack != 0)
 739                 goto out;
 740
 741         seq = hard_ack + 1;
 742         top = smp_load_acquire(&call->rx_top);
 743         if (after(seq, top))
 744                 goto out;
 745
 746         skb = call->rxtx_buffer[seq & RXRPC_RXTX_BUFF_MASK];
 747         if (!skb)
 748                 goto out;
 749
 750         *_ts = skb_get_ktime(skb);
 751         success = true;
 752
 753 out:
 754         mutex_unlock(&call->user_mutex);
 755         return success;
 756 }
 757 EXPORT_SYMBOL(rxrpc_kernel_get_reply_time);