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