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->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                              bool *_last)
 272 {
 273         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 274         unsigned int offset = sizeof(struct rxrpc_wire_header);
 275         unsigned int len;
 276         bool last = false;
 277         int ret;
 278         u8 annotation = *_annotation;
 279         u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;
 280
 281         /* Locate the subpacket */
 282         offset += subpacket * RXRPC_JUMBO_SUBPKTLEN;
 283         len = skb->len - offset;
 284         if (subpacket < sp->nr_subpackets - 1)
 285                 len = RXRPC_JUMBO_DATALEN;
 286         else if (sp->rx_flags & RXRPC_SKB_INCL_LAST)
 287                 last = true;
 288
 289         if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
 290                 ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
 291                 if (ret < 0)
 292                         return ret;
 293                 *_annotation |= RXRPC_RX_ANNO_VERIFIED;
 294         }
 295
 296         *_offset = offset;
 297         *_len = len;
 298         *_last = last;
 299         call->security->locate_data(call, skb, _offset, _len);
 300         return 0;
 301 }
 302
 303 /*
 304  * Deliver messages to a call.  This keeps processing packets until the buffer
 305  * is filled and we find either more DATA (returns 0) or the end of the DATA
 306  * (returns 1).  If more packets are required, it returns -EAGAIN.
 307  */
 308 static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 309                               struct msghdr *msg, struct iov_iter *iter,
 310                               size_t len, int flags, size_t *_offset)
 311 {
 312         struct rxrpc_skb_priv *sp;
 313         struct sk_buff *skb;
 314         rxrpc_serial_t serial;
 315         rxrpc_seq_t hard_ack, top, seq;
 316         size_t remain;
 317         bool rx_pkt_last;
 318         unsigned int rx_pkt_offset, rx_pkt_len;
 319         int ix, copy, ret = -EAGAIN, ret2;
 320
 321         if (test_and_clear_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags) &&
 322             call->ackr_reason)
 323                 rxrpc_send_ack_packet(call, false, NULL);
 324
 325         rx_pkt_offset = call->rx_pkt_offset;
 326         rx_pkt_len = call->rx_pkt_len;
 327         rx_pkt_last = call->rx_pkt_last;
 328
 329         if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
 330                 seq = call->rx_hard_ack;
 331                 ret = 1;
 332                 goto done;
 333         }
 334
 335         /* Barriers against rxrpc_input_data(). */
 336         hard_ack = call->rx_hard_ack;
 337         seq = hard_ack + 1;
 338
 339         while (top = smp_load_acquire(&call->rx_top),
 340                before_eq(seq, top)
 341                ) {
 342                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 343                 skb = call->rxtx_buffer[ix];
 344                 if (!skb) {
 345                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq,
 346                                             rx_pkt_offset, rx_pkt_len, 0);
 347                         break;
 348                 }
 349                 smp_rmb();
 350                 rxrpc_see_skb(skb, rxrpc_skb_seen);
 351                 sp = rxrpc_skb(skb);
 352
 353                 if (!(flags & MSG_PEEK)) {
 354                         serial = sp->hdr.serial;
 355                         serial += call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
 356                         trace_rxrpc_receive(call, rxrpc_receive_front,
 357                                             serial, seq);
 358                 }
 359
 360                 if (msg)
 361                         sock_recv_timestamp(msg, sock->sk, skb);
 362
 363                 if (rx_pkt_offset == 0) {
 364                         ret2 = rxrpc_locate_data(call, skb,
 365                                                  &call->rxtx_annotations[ix],
 366                                                  &rx_pkt_offset, &rx_pkt_len,
 367                                                  &rx_pkt_last);
 368                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq,
 369                                             rx_pkt_offset, rx_pkt_len, ret2);
 370                         if (ret2 < 0) {
 371                                 ret = ret2;
 372                                 goto out;
 373                         }
 374                 } else {
 375                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq,
 376                                             rx_pkt_offset, rx_pkt_len, 0);
 377                 }
 378
 379                 /* We have to handle short, empty and used-up DATA packets. */
 380                 remain = len - *_offset;
 381                 copy = rx_pkt_len;
 382                 if (copy > remain)
 383                         copy = remain;
 384                 if (copy > 0) {
 385                         ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
 386                                                       copy);
 387                         if (ret2 < 0) {
 388                                 ret = ret2;
 389                                 goto out;
 390                         }
 391
 392                         /* handle piecemeal consumption of data packets */
 393                         rx_pkt_offset += copy;
 394                         rx_pkt_len -= copy;
 395                         *_offset += copy;
 396                 }
 397
 398                 if (rx_pkt_len > 0) {
 399                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq,
 400                                             rx_pkt_offset, rx_pkt_len, 0);
 401                         ASSERTCMP(*_offset, ==, len);
 402                         ret = 0;
 403                         break;
 404                 }
 405
 406                 /* The whole packet has been transferred. */
 407                 if (!(flags & MSG_PEEK))
 408                         rxrpc_rotate_rx_window(call);
 409                 rx_pkt_offset = 0;
 410                 rx_pkt_len = 0;
 411
 412                 if (rx_pkt_last) {
 413                         ASSERTCMP(seq, ==, READ_ONCE(call->rx_top));
 414                         ret = 1;
 415                         goto out;
 416                 }
 417
 418                 seq++;
 419         }
 420
 421 out:
 422         if (!(flags & MSG_PEEK)) {
 423                 call->rx_pkt_offset = rx_pkt_offset;
 424                 call->rx_pkt_len = rx_pkt_len;
 425                 call->rx_pkt_last = rx_pkt_last;
 426         }
 427 done:
 428         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_data_return, seq,
 429                             rx_pkt_offset, rx_pkt_len, ret);
 430         if (ret == -EAGAIN)
 431                 set_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags);
 432         return ret;
 433 }
 434
 435 /*
 436  * Receive a message from an RxRPC socket
 437  * - we need to be careful about two or more threads calling recvmsg
 438  *   simultaneously
 439  */
 440 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 441                   int flags)
 442 {
 443         struct rxrpc_call *call;
 444         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 445         struct list_head *l;
 446         size_t copied = 0;
 447         long timeo;
 448         int ret;
 449
 450         DEFINE_WAIT(wait);
 451
 452         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0, 0, 0, 0);
 453
 454         if (flags & (MSG_OOB | MSG_TRUNC))
 455                 return -EOPNOTSUPP;
 456
 457         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
 458
 459 try_again:
 460         lock_sock(&rx->sk);
 461
 462         /* Return immediately if a client socket has no outstanding calls */
 463         if (RB_EMPTY_ROOT(&rx->calls) &&
 464             list_empty(&rx->recvmsg_q) &&
 465             rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
 466                 release_sock(&rx->sk);
 467                 return -ENODATA;
 468         }
 469
 470         if (list_empty(&rx->recvmsg_q)) {
 471                 ret = -EWOULDBLOCK;
 472                 if (timeo == 0) {
 473                         call = NULL;
 474                         goto error_no_call;
 475                 }
 476
 477                 release_sock(&rx->sk);
 478
 479                 /* Wait for something to happen */
 480                 prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
 481                                           TASK_INTERRUPTIBLE);
 482                 ret = sock_error(&rx->sk);
 483                 if (ret)
 484                         goto wait_error;
 485
 486                 if (list_empty(&rx->recvmsg_q)) {
 487                         if (signal_pending(current))
 488                                 goto wait_interrupted;
 489                         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait,
 490                                             0, 0, 0, 0);
 491                         timeo = schedule_timeout(timeo);
 492                 }
 493                 finish_wait(sk_sleep(&rx->sk), &wait);
 494                 goto try_again;
 495         }
 496
 497         /* Find the next call and dequeue it if we're not just peeking.  If we
 498          * do dequeue it, that comes with a ref that we will need to release.
 499          */
 500         write_lock_bh(&rx->recvmsg_lock);
 501         l = rx->recvmsg_q.next;
 502         call = list_entry(l, struct rxrpc_call, recvmsg_link);
 503         if (!(flags & MSG_PEEK))
 504                 list_del_init(&call->recvmsg_link);
 505         else
 506                 rxrpc_get_call(call, rxrpc_call_got);
 507         write_unlock_bh(&rx->recvmsg_lock);
 508
 509         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0, 0, 0, 0);
 510
 511         /* We're going to drop the socket lock, so we need to lock the call
 512          * against interference by sendmsg.
 513          */
 514         if (!mutex_trylock(&call->user_mutex)) {
 515                 ret = -EWOULDBLOCK;
 516                 if (flags & MSG_DONTWAIT)
 517                         goto error_requeue_call;
 518                 ret = -ERESTARTSYS;
 519                 if (mutex_lock_interruptible(&call->user_mutex) < 0)
 520                         goto error_requeue_call;
 521         }
 522
 523         release_sock(&rx->sk);
 524
 525         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
 526                 BUG();
 527
 528         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
 529                 if (flags & MSG_CMSG_COMPAT) {
 530                         unsigned int id32 = call->user_call_ID;
 531
 532                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 533                                        sizeof(unsigned int), &id32);
 534                 } else {
 535                         unsigned long idl = call->user_call_ID;
 536
 537                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 538                                        sizeof(unsigned long), &idl);
 539                 }
 540                 if (ret < 0)
 541                         goto error_unlock_call;
 542         }
 543
 544         if (msg->msg_name) {
 545                 struct sockaddr_rxrpc *srx = msg->msg_name;
 546                 size_t len = sizeof(call->peer->srx);
 547
 548                 memcpy(msg->msg_name, &call->peer->srx, len);
 549                 srx->srx_service = call->service_id;
 550                 msg->msg_namelen = len;
 551         }
 552
 553         switch (READ_ONCE(call->state)) {
 554         case RXRPC_CALL_SERVER_ACCEPTING:
 555                 ret = rxrpc_recvmsg_new_call(rx, call, msg, flags);
 556                 break;
 557         case RXRPC_CALL_CLIENT_RECV_REPLY:
 558         case RXRPC_CALL_SERVER_RECV_REQUEST:
 559         case RXRPC_CALL_SERVER_ACK_REQUEST:
 560                 ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
 561                                          flags, &copied);
 562                 if (ret == -EAGAIN)
 563                         ret = 0;
 564
 565                 if (after(call->rx_top, call->rx_hard_ack) &&
 566                     call->rxtx_buffer[(call->rx_hard_ack + 1) & RXRPC_RXTX_BUFF_MASK])
 567                         rxrpc_notify_socket(call);
 568                 break;
 569         default:
 570                 ret = 0;
 571                 break;
 572         }
 573
 574         if (ret < 0)
 575                 goto error_unlock_call;
 576
 577         if (call->state == RXRPC_CALL_COMPLETE) {
 578                 ret = rxrpc_recvmsg_term(call, msg);
 579                 if (ret < 0)
 580                         goto error_unlock_call;
 581                 if (!(flags & MSG_PEEK))
 582                         rxrpc_release_call(rx, call);
 583                 msg->msg_flags |= MSG_EOR;
 584                 ret = 1;
 585         }
 586
 587         if (ret == 0)
 588                 msg->msg_flags |= MSG_MORE;
 589         else
 590                 msg->msg_flags &= ~MSG_MORE;
 591         ret = copied;
 592
 593 error_unlock_call:
 594         mutex_unlock(&call->user_mutex);
 595         rxrpc_put_call(call, rxrpc_call_put);
 596         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 597         return ret;
 598
 599 error_requeue_call:
 600         if (!(flags & MSG_PEEK)) {
 601                 write_lock_bh(&rx->recvmsg_lock);
 602                 list_add(&call->recvmsg_link, &rx->recvmsg_q);
 603                 write_unlock_bh(&rx->recvmsg_lock);
 604                 trace_rxrpc_recvmsg(call, rxrpc_recvmsg_requeue, 0, 0, 0, 0);
 605         } else {
 606                 rxrpc_put_call(call, rxrpc_call_put);
 607         }
 608 error_no_call:
 609         release_sock(&rx->sk);
 610 error_trace:
 611         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 612         return ret;
 613
 614 wait_interrupted:
 615         ret = sock_intr_errno(timeo);
 616 wait_error:
 617         finish_wait(sk_sleep(&rx->sk), &wait);
 618         call = NULL;
 619         goto error_trace;
 620 }
 621
 622 /**
 623  * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 624  * @sock: The socket that the call exists on
 625  * @call: The call to send data through
 626  * @iter: The buffer to receive into
 627  * @want_more: True if more data is expected to be read
 628  * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 629  * @_service: Where to store the actual service ID (may be upgraded)
 630  *
 631  * Allow a kernel service to receive data and pick up information about the
 632  * state of a call.  Returns 0 if got what was asked for and there's more
 633  * available, 1 if we got what was asked for and we're at the end of the data
 634  * and -EAGAIN if we need more data.
 635  *
 636  * Note that we may return -EAGAIN to drain empty packets at the end of the
 637  * data, even if we've already copied over the requested data.
 638  *
 639  * *_abort should also be initialised to 0.
 640  */
 641 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 642                            struct iov_iter *iter,
 643                            bool want_more, u32 *_abort, u16 *_service)
 644 {
 645         size_t offset = 0;
 646         int ret;
 647
 648         _enter("{%d,%s},%zu,%d",
 649                call->debug_id, rxrpc_call_states[call->state],
 650                iov_iter_count(iter), want_more);
 651
 652         ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_ACCEPTING);
 653
 654         mutex_lock(&call->user_mutex);
 655
 656         switch (READ_ONCE(call->state)) {
 657         case RXRPC_CALL_CLIENT_RECV_REPLY:
 658         case RXRPC_CALL_SERVER_RECV_REQUEST:
 659         case RXRPC_CALL_SERVER_ACK_REQUEST:
 660                 ret = rxrpc_recvmsg_data(sock, call, NULL, iter,
 661                                          iov_iter_count(iter), 0,
 662                                          &offset);
 663                 if (ret < 0)
 664                         goto out;
 665
 666                 /* We can only reach here with a partially full buffer if we
 667                  * have reached the end of the data.  We must otherwise have a
 668                  * full buffer or have been given -EAGAIN.
 669                  */
 670                 if (ret == 1) {
 671                         if (iov_iter_count(iter) > 0)
 672                                 goto short_data;
 673                         if (!want_more)
 674                                 goto read_phase_complete;
 675                         ret = 0;
 676                         goto out;
 677                 }
 678
 679                 if (!want_more)
 680                         goto excess_data;
 681                 goto out;
 682
 683         case RXRPC_CALL_COMPLETE:
 684                 goto call_complete;
 685
 686         default:
 687                 ret = -EINPROGRESS;
 688                 goto out;
 689         }
 690
 691 read_phase_complete:
 692         ret = 1;
 693 out:
 694         switch (call->ackr_reason) {
 695         case RXRPC_ACK_IDLE:
 696                 break;
 697         case RXRPC_ACK_DELAY:
 698                 if (ret != -EAGAIN)
 699                         break;
 700                 /* Fall through */
 701         default:
 702                 rxrpc_send_ack_packet(call, false, NULL);
 703         }
 704
 705         if (_service)
 706                 *_service = call->service_id;
 707         mutex_unlock(&call->user_mutex);
 708         _leave(" = %d [%zu,%d]", ret, iov_iter_count(iter), *_abort);
 709         return ret;
 710
 711 short_data:
 712         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("short_data"));
 713         ret = -EBADMSG;
 714         goto out;
 715 excess_data:
 716         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("excess_data"));
 717         ret = -EMSGSIZE;
 718         goto out;
 719 call_complete:
 720         *_abort = call->abort_code;
 721         ret = call->error;
 722         if (call->completion == RXRPC_CALL_SUCCEEDED) {
 723                 ret = 1;
 724                 if (iov_iter_count(iter) > 0)
 725                         ret = -ECONNRESET;
 726         }
 727         goto out;
 728 }
 729 EXPORT_SYMBOL(rxrpc_kernel_recv_data);
 730
 731 /**
 732  * rxrpc_kernel_get_reply_time - Get timestamp on first reply packet
 733  * @sock: The socket that the call exists on
 734  * @call: The call to query
 735  * @_ts: Where to put the timestamp
 736  *
 737  * Retrieve the timestamp from the first DATA packet of the reply if it is
 738  * in the ring.  Returns true if successful, false if not.
 739  */
 740 bool rxrpc_kernel_get_reply_time(struct socket *sock, struct rxrpc_call *call,
 741                                  ktime_t *_ts)
 742 {
 743         struct sk_buff *skb;
 744         rxrpc_seq_t hard_ack, top, seq;
 745         bool success = false;
 746
 747         mutex_lock(&call->user_mutex);
 748
 749         if (READ_ONCE(call->state) != RXRPC_CALL_CLIENT_RECV_REPLY)
 750                 goto out;
 751
 752         hard_ack = call->rx_hard_ack;
 753         if (hard_ack != 0)
 754                 goto out;
 755
 756         seq = hard_ack + 1;
 757         top = smp_load_acquire(&call->rx_top);
 758         if (after(seq, top))
 759                 goto out;
 760
 761         skb = call->rxtx_buffer[seq & RXRPC_RXTX_BUFF_MASK];
 762         if (!skb)
 763                 goto out;
 764
 765         *_ts = skb_get_ktime(skb);
 766         success = true;
 767
 768 out:
 769         mutex_unlock(&call->user_mutex);
 770         return success;
 771 }
 772 EXPORT_SYMBOL(rxrpc_kernel_get_reply_time);