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, 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, 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         bool last = false;
 181         u8 subpacket;
 182         int ix;
 183
 184         _enter("%d", call->debug_id);
 185
 186         hard_ack = call->rx_hard_ack;
 187         top = smp_load_acquire(&call->rx_top);
 188         ASSERT(before(hard_ack, top));
 189
 190         hard_ack++;
 191         ix = hard_ack & RXRPC_RXTX_BUFF_MASK;
 192         skb = call->rxtx_buffer[ix];
 193         rxrpc_see_skb(skb, rxrpc_skb_rotated);
 194         sp = rxrpc_skb(skb);
 195
 196         subpacket = call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
 197         serial = sp->hdr.serial + subpacket;
 198
 199         if (subpacket == sp->nr_subpackets - 1 &&
 200             sp->rx_flags & RXRPC_SKB_INCL_LAST)
 201                 last = true;
 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_freed);
 209
 210         trace_rxrpc_receive(call, rxrpc_receive_rotate, serial, hard_ack);
 211         if (last) {
 212                 rxrpc_end_rx_phase(call, serial);
 213         } else {
 214                 /* Check to see if there's an ACK that needs sending. */
 215                 if (atomic_inc_return(&call->ackr_nr_consumed) > 2)
 216                         rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, serial,
 217                                           true, false,
 218                                           rxrpc_propose_ack_rotate_rx);
 219                 if (call->ackr_reason && call->ackr_reason != RXRPC_ACK_DELAY)
 220                         rxrpc_send_ack_packet(call, false, NULL);
 221         }
 222 }
 223
 224 /*
 225  * Decrypt and verify a (sub)packet.  The packet's length may be changed due to
 226  * padding, but if this is the case, the packet length will be resident in the
 227  * socket buffer.  Note that we can't modify the master skb info as the skb may
 228  * be the home to multiple subpackets.
 229  */
 230 static int rxrpc_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
 231                                u8 annotation,
 232                                unsigned int offset, unsigned int len)
 233 {
 234         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 235         rxrpc_seq_t seq = sp->hdr.seq;
 236         u16 cksum = sp->hdr.cksum;
 237         u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;
 238
 239         _enter("");
 240
 241         /* For all but the head jumbo subpacket, the security checksum is in a
 242          * jumbo header immediately prior to the data.
 243          */
 244         if (subpacket > 0) {
 245                 __be16 tmp;
 246                 if (skb_copy_bits(skb, offset - 2, &tmp, 2) < 0)
 247                         BUG();
 248                 cksum = ntohs(tmp);
 249                 seq += subpacket;
 250         }
 251
 252         return call->security->verify_packet(call, skb, offset, len,
 253                                              seq, cksum);
 254 }
 255
 256 /*
 257  * Locate the data within a packet.  This is complicated by:
 258  *
 259  * (1) An skb may contain a jumbo packet - so we have to find the appropriate
 260  *     subpacket.
 261  *
 262  * (2) The (sub)packets may be encrypted and, if so, the encrypted portion
 263  *     contains an extra header which includes the true length of the data,
 264  *     excluding any encrypted padding.
 265  */
 266 static int rxrpc_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
 267                              u8 *_annotation,
 268                              unsigned int *_offset, unsigned int *_len,
 269                              bool *_last)
 270 {
 271         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 272         unsigned int offset = sizeof(struct rxrpc_wire_header);
 273         unsigned int len;
 274         bool last = false;
 275         int ret;
 276         u8 annotation = *_annotation;
 277         u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;
 278
 279         /* Locate the subpacket */
 280         offset += subpacket * RXRPC_JUMBO_SUBPKTLEN;
 281         len = skb->len - offset;
 282         if (subpacket < sp->nr_subpackets - 1)
 283                 len = RXRPC_JUMBO_DATALEN;
 284         else if (sp->rx_flags & RXRPC_SKB_INCL_LAST)
 285                 last = true;
 286
 287         if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
 288                 ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
 289                 if (ret < 0)
 290                         return ret;
 291                 *_annotation |= RXRPC_RX_ANNO_VERIFIED;
 292         }
 293
 294         *_offset = offset;
 295         *_len = len;
 296         *_last = last;
 297         call->security->locate_data(call, skb, _offset, _len);
 298         return 0;
 299 }
 300
 301 /*
 302  * Deliver messages to a call.  This keeps processing packets until the buffer
 303  * is filled and we find either more DATA (returns 0) or the end of the DATA
 304  * (returns 1).  If more packets are required, it returns -EAGAIN.
 305  */
 306 static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 307                               struct msghdr *msg, struct iov_iter *iter,
 308                               size_t len, int flags, size_t *_offset)
 309 {
 310         struct rxrpc_skb_priv *sp;
 311         struct sk_buff *skb;
 312         rxrpc_serial_t serial;
 313         rxrpc_seq_t hard_ack, top, seq;
 314         size_t remain;
 315         bool rx_pkt_last;
 316         unsigned int rx_pkt_offset, rx_pkt_len;
 317         int ix, copy, ret = -EAGAIN, ret2;
 318
 319         if (test_and_clear_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags) &&
 320             call->ackr_reason)
 321                 rxrpc_send_ack_packet(call, false, NULL);
 322
 323         rx_pkt_offset = call->rx_pkt_offset;
 324         rx_pkt_len = call->rx_pkt_len;
 325         rx_pkt_last = call->rx_pkt_last;
 326
 327         if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
 328                 seq = call->rx_hard_ack;
 329                 ret = 1;
 330                 goto done;
 331         }
 332
 333         /* Barriers against rxrpc_input_data(). */
 334         hard_ack = call->rx_hard_ack;
 335         seq = hard_ack + 1;
 336
 337         while (top = smp_load_acquire(&call->rx_top),
 338                before_eq(seq, top)
 339                ) {
 340                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 341                 skb = call->rxtx_buffer[ix];
 342                 if (!skb) {
 343                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq,
 344                                             rx_pkt_offset, rx_pkt_len, 0);
 345                         break;
 346                 }
 347                 smp_rmb();
 348                 rxrpc_see_skb(skb, rxrpc_skb_seen);
 349                 sp = rxrpc_skb(skb);
 350
 351                 if (!(flags & MSG_PEEK)) {
 352                         serial = sp->hdr.serial;
 353                         serial += call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
 354                         trace_rxrpc_receive(call, rxrpc_receive_front,
 355                                             serial, seq);
 356                 }
 357
 358                 if (msg)
 359                         sock_recv_timestamp(msg, sock->sk, skb);
 360
 361                 if (rx_pkt_offset == 0) {
 362                         ret2 = rxrpc_locate_data(call, skb,
 363                                                  &call->rxtx_annotations[ix],
 364                                                  &rx_pkt_offset, &rx_pkt_len,
 365                                                  &rx_pkt_last);
 366                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq,
 367                                             rx_pkt_offset, rx_pkt_len, ret2);
 368                         if (ret2 < 0) {
 369                                 ret = ret2;
 370                                 goto out;
 371                         }
 372                 } else {
 373                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq,
 374                                             rx_pkt_offset, rx_pkt_len, 0);
 375                 }
 376
 377                 /* We have to handle short, empty and used-up DATA packets. */
 378                 remain = len - *_offset;
 379                 copy = rx_pkt_len;
 380                 if (copy > remain)
 381                         copy = remain;
 382                 if (copy > 0) {
 383                         ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
 384                                                       copy);
 385                         if (ret2 < 0) {
 386                                 ret = ret2;
 387                                 goto out;
 388                         }
 389
 390                         /* handle piecemeal consumption of data packets */
 391                         rx_pkt_offset += copy;
 392                         rx_pkt_len -= copy;
 393                         *_offset += copy;
 394                 }
 395
 396                 if (rx_pkt_len > 0) {
 397                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq,
 398                                             rx_pkt_offset, rx_pkt_len, 0);
 399                         ASSERTCMP(*_offset, ==, len);
 400                         ret = 0;
 401                         break;
 402                 }
 403
 404                 /* The whole packet has been transferred. */
 405                 if (!(flags & MSG_PEEK))
 406                         rxrpc_rotate_rx_window(call);
 407                 rx_pkt_offset = 0;
 408                 rx_pkt_len = 0;
 409
 410                 if (rx_pkt_last) {
 411                         ASSERTCMP(seq, ==, READ_ONCE(call->rx_top));
 412                         ret = 1;
 413                         goto out;
 414                 }
 415
 416                 seq++;
 417         }
 418
 419 out:
 420         if (!(flags & MSG_PEEK)) {
 421                 call->rx_pkt_offset = rx_pkt_offset;
 422                 call->rx_pkt_len = rx_pkt_len;
 423                 call->rx_pkt_last = rx_pkt_last;
 424         }
 425 done:
 426         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_data_return, seq,
 427                             rx_pkt_offset, rx_pkt_len, ret);
 428         if (ret == -EAGAIN)
 429                 set_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags);
 430         return ret;
 431 }
 432
 433 /*
 434  * Receive a message from an RxRPC socket
 435  * - we need to be careful about two or more threads calling recvmsg
 436  *   simultaneously
 437  */
 438 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 439                   int flags)
 440 {
 441         struct rxrpc_call *call;
 442         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 443         struct list_head *l;
 444         size_t copied = 0;
 445         long timeo;
 446         int ret;
 447
 448         DEFINE_WAIT(wait);
 449
 450         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0, 0, 0, 0);
 451
 452         if (flags & (MSG_OOB | MSG_TRUNC))
 453                 return -EOPNOTSUPP;
 454
 455         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
 456
 457 try_again:
 458         lock_sock(&rx->sk);
 459
 460         /* Return immediately if a client socket has no outstanding calls */
 461         if (RB_EMPTY_ROOT(&rx->calls) &&
 462             list_empty(&rx->recvmsg_q) &&
 463             rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
 464                 release_sock(&rx->sk);
 465                 return -EAGAIN;
 466         }
 467
 468         if (list_empty(&rx->recvmsg_q)) {
 469                 ret = -EWOULDBLOCK;
 470                 if (timeo == 0) {
 471                         call = NULL;
 472                         goto error_no_call;
 473                 }
 474
 475                 release_sock(&rx->sk);
 476
 477                 /* Wait for something to happen */
 478                 prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
 479                                           TASK_INTERRUPTIBLE);
 480                 ret = sock_error(&rx->sk);
 481                 if (ret)
 482                         goto wait_error;
 483
 484                 if (list_empty(&rx->recvmsg_q)) {
 485                         if (signal_pending(current))
 486                                 goto wait_interrupted;
 487                         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait,
 488                                             0, 0, 0, 0);
 489                         timeo = schedule_timeout(timeo);
 490                 }
 491                 finish_wait(sk_sleep(&rx->sk), &wait);
 492                 goto try_again;
 493         }
 494
 495         /* Find the next call and dequeue it if we're not just peeking.  If we
 496          * do dequeue it, that comes with a ref that we will need to release.
 497          */
 498         write_lock_bh(&rx->recvmsg_lock);
 499         l = rx->recvmsg_q.next;
 500         call = list_entry(l, struct rxrpc_call, recvmsg_link);
 501         if (!(flags & MSG_PEEK))
 502                 list_del_init(&call->recvmsg_link);
 503         else
 504                 rxrpc_get_call(call, rxrpc_call_got);
 505         write_unlock_bh(&rx->recvmsg_lock);
 506
 507         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0, 0, 0, 0);
 508
 509         /* We're going to drop the socket lock, so we need to lock the call
 510          * against interference by sendmsg.
 511          */
 512         if (!mutex_trylock(&call->user_mutex)) {
 513                 ret = -EWOULDBLOCK;
 514                 if (flags & MSG_DONTWAIT)
 515                         goto error_requeue_call;
 516                 ret = -ERESTARTSYS;
 517                 if (mutex_lock_interruptible(&call->user_mutex) < 0)
 518                         goto error_requeue_call;
 519         }
 520
 521         release_sock(&rx->sk);
 522
 523         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
 524                 BUG();
 525
 526         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
 527                 if (flags & MSG_CMSG_COMPAT) {
 528                         unsigned int id32 = call->user_call_ID;
 529
 530                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 531                                        sizeof(unsigned int), &id32);
 532                 } else {
 533                         unsigned long idl = call->user_call_ID;
 534
 535                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 536                                        sizeof(unsigned long), &idl);
 537                 }
 538                 if (ret < 0)
 539                         goto error_unlock_call;
 540         }
 541
 542         if (msg->msg_name && call->peer) {
 543                 struct sockaddr_rxrpc *srx = msg->msg_name;
 544                 size_t len = sizeof(call->peer->srx);
 545
 546                 memcpy(msg->msg_name, &call->peer->srx, len);
 547                 srx->srx_service = call->service_id;
 548                 msg->msg_namelen = len;
 549         }
 550
 551         switch (READ_ONCE(call->state)) {
 552         case RXRPC_CALL_SERVER_ACCEPTING:
 553                 ret = rxrpc_recvmsg_new_call(rx, call, msg, flags);
 554                 break;
 555         case RXRPC_CALL_CLIENT_RECV_REPLY:
 556         case RXRPC_CALL_SERVER_RECV_REQUEST:
 557         case RXRPC_CALL_SERVER_ACK_REQUEST:
 558                 ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
 559                                          flags, &copied);
 560                 if (ret == -EAGAIN)
 561                         ret = 0;
 562
 563                 if (after(call->rx_top, call->rx_hard_ack) &&
 564                     call->rxtx_buffer[(call->rx_hard_ack + 1) & RXRPC_RXTX_BUFF_MASK])
 565                         rxrpc_notify_socket(call);
 566                 break;
 567         default:
 568                 ret = 0;
 569                 break;
 570         }
 571
 572         if (ret < 0)
 573                 goto error_unlock_call;
 574
 575         if (call->state == RXRPC_CALL_COMPLETE) {
 576                 ret = rxrpc_recvmsg_term(call, msg);
 577                 if (ret < 0)
 578                         goto error_unlock_call;
 579                 if (!(flags & MSG_PEEK))
 580                         rxrpc_release_call(rx, call);
 581                 msg->msg_flags |= MSG_EOR;
 582                 ret = 1;
 583         }
 584
 585         if (ret == 0)
 586                 msg->msg_flags |= MSG_MORE;
 587         else
 588                 msg->msg_flags &= ~MSG_MORE;
 589         ret = copied;
 590
 591 error_unlock_call:
 592         mutex_unlock(&call->user_mutex);
 593         rxrpc_put_call(call, rxrpc_call_put);
 594         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 595         return ret;
 596
 597 error_requeue_call:
 598         if (!(flags & MSG_PEEK)) {
 599                 write_lock_bh(&rx->recvmsg_lock);
 600                 list_add(&call->recvmsg_link, &rx->recvmsg_q);
 601                 write_unlock_bh(&rx->recvmsg_lock);
 602                 trace_rxrpc_recvmsg(call, rxrpc_recvmsg_requeue, 0, 0, 0, 0);
 603         } else {
 604                 rxrpc_put_call(call, rxrpc_call_put);
 605         }
 606 error_no_call:
 607         release_sock(&rx->sk);
 608 error_trace:
 609         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 610         return ret;
 611
 612 wait_interrupted:
 613         ret = sock_intr_errno(timeo);
 614 wait_error:
 615         finish_wait(sk_sleep(&rx->sk), &wait);
 616         call = NULL;
 617         goto error_trace;
 618 }
 619
 620 /**
 621  * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 622  * @sock: The socket that the call exists on
 623  * @call: The call to send data through
 624  * @iter: The buffer to receive into
 625  * @want_more: True if more data is expected to be read
 626  * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 627  * @_service: Where to store the actual service ID (may be upgraded)
 628  *
 629  * Allow a kernel service to receive data and pick up information about the
 630  * state of a call.  Returns 0 if got what was asked for and there's more
 631  * available, 1 if we got what was asked for and we're at the end of the data
 632  * and -EAGAIN if we need more data.
 633  *
 634  * Note that we may return -EAGAIN to drain empty packets at the end of the
 635  * data, even if we've already copied over the requested data.
 636  *
 637  * *_abort should also be initialised to 0.
 638  */
 639 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 640                            struct iov_iter *iter,
 641                            bool want_more, u32 *_abort, u16 *_service)
 642 {
 643         size_t offset = 0;
 644         int ret;
 645
 646         _enter("{%d,%s},%zu,%d",
 647                call->debug_id, rxrpc_call_states[call->state],
 648                iov_iter_count(iter), want_more);
 649
 650         ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_ACCEPTING);
 651
 652         mutex_lock(&call->user_mutex);
 653
 654         switch (READ_ONCE(call->state)) {
 655         case RXRPC_CALL_CLIENT_RECV_REPLY:
 656         case RXRPC_CALL_SERVER_RECV_REQUEST:
 657         case RXRPC_CALL_SERVER_ACK_REQUEST:
 658                 ret = rxrpc_recvmsg_data(sock, call, NULL, iter,
 659                                          iov_iter_count(iter), 0,
 660                                          &offset);
 661                 if (ret < 0)
 662                         goto out;
 663
 664                 /* We can only reach here with a partially full buffer if we
 665                  * have reached the end of the data.  We must otherwise have a
 666                  * full buffer or have been given -EAGAIN.
 667                  */
 668                 if (ret == 1) {
 669                         if (iov_iter_count(iter) > 0)
 670                                 goto short_data;
 671                         if (!want_more)
 672                                 goto read_phase_complete;
 673                         ret = 0;
 674                         goto out;
 675                 }
 676
 677                 if (!want_more)
 678                         goto excess_data;
 679                 goto out;
 680
 681         case RXRPC_CALL_COMPLETE:
 682                 goto call_complete;
 683
 684         default:
 685                 ret = -EINPROGRESS;
 686                 goto out;
 687         }
 688
 689 read_phase_complete:
 690         ret = 1;
 691 out:
 692         switch (call->ackr_reason) {
 693         case RXRPC_ACK_IDLE:
 694                 break;
 695         case RXRPC_ACK_DELAY:
 696                 if (ret != -EAGAIN)
 697                         break;
 698                 /* Fall through */
 699         default:
 700                 rxrpc_send_ack_packet(call, false, NULL);
 701         }
 702
 703         if (_service)
 704                 *_service = call->service_id;
 705         mutex_unlock(&call->user_mutex);
 706         _leave(" = %d [%zu,%d]", ret, iov_iter_count(iter), *_abort);
 707         return ret;
 708
 709 short_data:
 710         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("short_data"));
 711         ret = -EBADMSG;
 712         goto out;
 713 excess_data:
 714         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("excess_data"));
 715         ret = -EMSGSIZE;
 716         goto out;
 717 call_complete:
 718         *_abort = call->abort_code;
 719         ret = call->error;
 720         if (call->completion == RXRPC_CALL_SUCCEEDED) {
 721                 ret = 1;
 722                 if (iov_iter_count(iter) > 0)
 723                         ret = -ECONNRESET;
 724         }
 725         goto out;
 726 }
 727 EXPORT_SYMBOL(rxrpc_kernel_recv_data);
 728
 729 /**
 730  * rxrpc_kernel_get_reply_time - Get timestamp on first reply packet
 731  * @sock: The socket that the call exists on
 732  * @call: The call to query
 733  * @_ts: Where to put the timestamp
 734  *
 735  * Retrieve the timestamp from the first DATA packet of the reply if it is
 736  * in the ring.  Returns true if successful, false if not.
 737  */
 738 bool rxrpc_kernel_get_reply_time(struct socket *sock, struct rxrpc_call *call,
 739                                  ktime_t *_ts)
 740 {
 741         struct sk_buff *skb;
 742         rxrpc_seq_t hard_ack, top, seq;
 743         bool success = false;
 744
 745         mutex_lock(&call->user_mutex);
 746
 747         if (READ_ONCE(call->state) != RXRPC_CALL_CLIENT_RECV_REPLY)
 748                 goto out;
 749
 750         hard_ack = call->rx_hard_ack;
 751         if (hard_ack != 0)
 752                 goto out;
 753
 754         seq = hard_ack + 1;
 755         top = smp_load_acquire(&call->rx_top);
 756         if (after(seq, top))
 757                 goto out;
 758
 759         skb = call->rxtx_buffer[seq & RXRPC_RXTX_BUFF_MASK];
 760         if (!skb)
 761                 goto out;
 762
 763         *_ts = skb_get_ktime(skb);
 764         success = true;
 765
 766 out:
 767         mutex_unlock(&call->user_mutex);
 768         return success;
 769 }
 770 EXPORT_SYMBOL(rxrpc_kernel_get_reply_time);