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  * Transition a call to the complete state.
  63  */
  64 bool __rxrpc_set_call_completion(struct rxrpc_call *call,
  65                                  enum rxrpc_call_completion compl,
  66                                  u32 abort_code,
  67                                  int error)
  68 {
  69         if (call->state < RXRPC_CALL_COMPLETE) {
  70                 call->abort_code = abort_code;
  71                 call->error = error;
  72                 call->completion = compl;
  73                 call->state = RXRPC_CALL_COMPLETE;
  74                 trace_rxrpc_call_complete(call);
  75                 wake_up(&call->waitq);
  76                 rxrpc_notify_socket(call);
  77                 return true;
  78         }
  79         return false;
  80 }
  81
  82 bool rxrpc_set_call_completion(struct rxrpc_call *call,
  83                                enum rxrpc_call_completion compl,
  84                                u32 abort_code,
  85                                int error)
  86 {
  87         bool ret = false;
  88
  89         if (call->state < RXRPC_CALL_COMPLETE) {
  90                 write_lock_bh(&call->state_lock);
  91                 ret = __rxrpc_set_call_completion(call, compl, abort_code, error);
  92                 write_unlock_bh(&call->state_lock);
  93         }
  94         return ret;
  95 }
  96
  97 /*
  98  * Record that a call successfully completed.
  99  */
 100 bool __rxrpc_call_completed(struct rxrpc_call *call)
 101 {
 102         return __rxrpc_set_call_completion(call, RXRPC_CALL_SUCCEEDED, 0, 0);
 103 }
 104
 105 bool rxrpc_call_completed(struct rxrpc_call *call)
 106 {
 107         bool ret = false;
 108
 109         if (call->state < RXRPC_CALL_COMPLETE) {
 110                 write_lock_bh(&call->state_lock);
 111                 ret = __rxrpc_call_completed(call);
 112                 write_unlock_bh(&call->state_lock);
 113         }
 114         return ret;
 115 }
 116
 117 /*
 118  * Record that a call is locally aborted.
 119  */
 120 bool __rxrpc_abort_call(const char *why, struct rxrpc_call *call,
 121                         rxrpc_seq_t seq, u32 abort_code, int error)
 122 {
 123         trace_rxrpc_abort(call->debug_id, why, call->cid, call->call_id, seq,
 124                           abort_code, error);
 125         return __rxrpc_set_call_completion(call, RXRPC_CALL_LOCALLY_ABORTED,
 126                                            abort_code, error);
 127 }
 128
 129 bool rxrpc_abort_call(const char *why, struct rxrpc_call *call,
 130                       rxrpc_seq_t seq, u32 abort_code, int error)
 131 {
 132         bool ret;
 133
 134         write_lock_bh(&call->state_lock);
 135         ret = __rxrpc_abort_call(why, call, seq, abort_code, error);
 136         write_unlock_bh(&call->state_lock);
 137         return ret;
 138 }
 139
 140 /*
 141  * Pass a call terminating message to userspace.
 142  */
 143 static int rxrpc_recvmsg_term(struct rxrpc_call *call, struct msghdr *msg)
 144 {
 145         u32 tmp = 0;
 146         int ret;
 147
 148         switch (call->completion) {
 149         case RXRPC_CALL_SUCCEEDED:
 150                 ret = 0;
 151                 if (rxrpc_is_service_call(call))
 152                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &tmp);
 153                 break;
 154         case RXRPC_CALL_REMOTELY_ABORTED:
 155                 tmp = call->abort_code;
 156                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
 157                 break;
 158         case RXRPC_CALL_LOCALLY_ABORTED:
 159                 tmp = call->abort_code;
 160                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &tmp);
 161                 break;
 162         case RXRPC_CALL_NETWORK_ERROR:
 163                 tmp = -call->error;
 164                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &tmp);
 165                 break;
 166         case RXRPC_CALL_LOCAL_ERROR:
 167                 tmp = -call->error;
 168                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4, &tmp);
 169                 break;
 170         default:
 171                 pr_err("Invalid terminal call state %u\n", call->state);
 172                 BUG();
 173                 break;
 174         }
 175
 176         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_terminal, call->rx_hard_ack,
 177                             call->rx_pkt_offset, call->rx_pkt_len, ret);
 178         return ret;
 179 }
 180
 181 /*
 182  * End the packet reception phase.
 183  */
 184 static void rxrpc_end_rx_phase(struct rxrpc_call *call, rxrpc_serial_t serial)
 185 {
 186         _enter("%d,%s", call->debug_id, rxrpc_call_states[call->state]);
 187
 188         trace_rxrpc_receive(call, rxrpc_receive_end, 0, call->rx_top);
 189         ASSERTCMP(call->rx_hard_ack, ==, call->rx_top);
 190
 191         if (call->state == RXRPC_CALL_CLIENT_RECV_REPLY) {
 192                 rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, serial, false, true,
 193                                   rxrpc_propose_ack_terminal_ack);
 194                 //rxrpc_send_ack_packet(call, false, NULL);
 195         }
 196
 197         write_lock_bh(&call->state_lock);
 198
 199         switch (call->state) {
 200         case RXRPC_CALL_CLIENT_RECV_REPLY:
 201                 __rxrpc_call_completed(call);
 202                 write_unlock_bh(&call->state_lock);
 203                 break;
 204
 205         case RXRPC_CALL_SERVER_RECV_REQUEST:
 206                 call->tx_phase = true;
 207                 call->state = RXRPC_CALL_SERVER_ACK_REQUEST;
 208                 call->expect_req_by = jiffies + MAX_JIFFY_OFFSET;
 209                 write_unlock_bh(&call->state_lock);
 210                 rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial, false, true,
 211                                   rxrpc_propose_ack_processing_op);
 212                 break;
 213         default:
 214                 write_unlock_bh(&call->state_lock);
 215                 break;
 216         }
 217 }
 218
 219 /*
 220  * Discard a packet we've used up and advance the Rx window by one.
 221  */
 222 static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
 223 {
 224         struct rxrpc_skb_priv *sp;
 225         struct sk_buff *skb;
 226         rxrpc_serial_t serial;
 227         rxrpc_seq_t hard_ack, top;
 228         bool last = false;
 229         u8 subpacket;
 230         int ix;
 231
 232         _enter("%d", call->debug_id);
 233
 234         hard_ack = call->rx_hard_ack;
 235         top = smp_load_acquire(&call->rx_top);
 236         ASSERT(before(hard_ack, top));
 237
 238         hard_ack++;
 239         ix = hard_ack & RXRPC_RXTX_BUFF_MASK;
 240         skb = call->rxtx_buffer[ix];
 241         rxrpc_see_skb(skb, rxrpc_skb_rotated);
 242         sp = rxrpc_skb(skb);
 243
 244         subpacket = call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
 245         serial = sp->hdr.serial + subpacket;
 246
 247         if (subpacket == sp->nr_subpackets - 1 &&
 248             sp->rx_flags & RXRPC_SKB_INCL_LAST)
 249                 last = true;
 250
 251         call->rxtx_buffer[ix] = NULL;
 252         call->rxtx_annotations[ix] = 0;
 253         /* Barrier against rxrpc_input_data(). */
 254         smp_store_release(&call->rx_hard_ack, hard_ack);
 255
 256         rxrpc_free_skb(skb, rxrpc_skb_freed);
 257
 258         trace_rxrpc_receive(call, rxrpc_receive_rotate, serial, hard_ack);
 259         if (last) {
 260                 rxrpc_end_rx_phase(call, serial);
 261         } else {
 262                 /* Check to see if there's an ACK that needs sending. */
 263                 if (atomic_inc_return(&call->ackr_nr_consumed) > 2)
 264                         rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, serial,
 265                                           true, false,
 266                                           rxrpc_propose_ack_rotate_rx);
 267                 if (call->ackr_reason && call->ackr_reason != RXRPC_ACK_DELAY)
 268                         rxrpc_send_ack_packet(call, false, NULL);
 269         }
 270 }
 271
 272 /*
 273  * Decrypt and verify a (sub)packet.  The packet's length may be changed due to
 274  * padding, but if this is the case, the packet length will be resident in the
 275  * socket buffer.  Note that we can't modify the master skb info as the skb may
 276  * be the home to multiple subpackets.
 277  */
 278 static int rxrpc_verify_packet(struct rxrpc_call *call, struct sk_buff *skb,
 279                                u8 annotation,
 280                                unsigned int offset, unsigned int len)
 281 {
 282         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 283         rxrpc_seq_t seq = sp->hdr.seq;
 284         u16 cksum = sp->hdr.cksum;
 285         u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;
 286
 287         _enter("");
 288
 289         /* For all but the head jumbo subpacket, the security checksum is in a
 290          * jumbo header immediately prior to the data.
 291          */
 292         if (subpacket > 0) {
 293                 __be16 tmp;
 294                 if (skb_copy_bits(skb, offset - 2, &tmp, 2) < 0)
 295                         BUG();
 296                 cksum = ntohs(tmp);
 297                 seq += subpacket;
 298         }
 299
 300         return call->security->verify_packet(call, skb, offset, len,
 301                                              seq, cksum);
 302 }
 303
 304 /*
 305  * Locate the data within a packet.  This is complicated by:
 306  *
 307  * (1) An skb may contain a jumbo packet - so we have to find the appropriate
 308  *     subpacket.
 309  *
 310  * (2) The (sub)packets may be encrypted and, if so, the encrypted portion
 311  *     contains an extra header which includes the true length of the data,
 312  *     excluding any encrypted padding.
 313  */
 314 static int rxrpc_locate_data(struct rxrpc_call *call, struct sk_buff *skb,
 315                              u8 *_annotation,
 316                              unsigned int *_offset, unsigned int *_len,
 317                              bool *_last)
 318 {
 319         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 320         unsigned int offset = sizeof(struct rxrpc_wire_header);
 321         unsigned int len;
 322         bool last = false;
 323         int ret;
 324         u8 annotation = *_annotation;
 325         u8 subpacket = annotation & RXRPC_RX_ANNO_SUBPACKET;
 326
 327         /* Locate the subpacket */
 328         offset += subpacket * RXRPC_JUMBO_SUBPKTLEN;
 329         len = skb->len - offset;
 330         if (subpacket < sp->nr_subpackets - 1)
 331                 len = RXRPC_JUMBO_DATALEN;
 332         else if (sp->rx_flags & RXRPC_SKB_INCL_LAST)
 333                 last = true;
 334
 335         if (!(annotation & RXRPC_RX_ANNO_VERIFIED)) {
 336                 ret = rxrpc_verify_packet(call, skb, annotation, offset, len);
 337                 if (ret < 0)
 338                         return ret;
 339                 *_annotation |= RXRPC_RX_ANNO_VERIFIED;
 340         }
 341
 342         *_offset = offset;
 343         *_len = len;
 344         *_last = last;
 345         call->security->locate_data(call, skb, _offset, _len);
 346         return 0;
 347 }
 348
 349 /*
 350  * Deliver messages to a call.  This keeps processing packets until the buffer
 351  * is filled and we find either more DATA (returns 0) or the end of the DATA
 352  * (returns 1).  If more packets are required, it returns -EAGAIN.
 353  */
 354 static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call,
 355                               struct msghdr *msg, struct iov_iter *iter,
 356                               size_t len, int flags, size_t *_offset)
 357 {
 358         struct rxrpc_skb_priv *sp;
 359         struct sk_buff *skb;
 360         rxrpc_serial_t serial;
 361         rxrpc_seq_t hard_ack, top, seq;
 362         size_t remain;
 363         bool rx_pkt_last;
 364         unsigned int rx_pkt_offset, rx_pkt_len;
 365         int ix, copy, ret = -EAGAIN, ret2;
 366
 367         if (test_and_clear_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags) &&
 368             call->ackr_reason)
 369                 rxrpc_send_ack_packet(call, false, NULL);
 370
 371         rx_pkt_offset = call->rx_pkt_offset;
 372         rx_pkt_len = call->rx_pkt_len;
 373         rx_pkt_last = call->rx_pkt_last;
 374
 375         if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) {
 376                 seq = call->rx_hard_ack;
 377                 ret = 1;
 378                 goto done;
 379         }
 380
 381         /* Barriers against rxrpc_input_data(). */
 382         hard_ack = call->rx_hard_ack;
 383         seq = hard_ack + 1;
 384
 385         while (top = smp_load_acquire(&call->rx_top),
 386                before_eq(seq, top)
 387                ) {
 388                 ix = seq & RXRPC_RXTX_BUFF_MASK;
 389                 skb = call->rxtx_buffer[ix];
 390                 if (!skb) {
 391                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq,
 392                                             rx_pkt_offset, rx_pkt_len, 0);
 393                         break;
 394                 }
 395                 smp_rmb();
 396                 rxrpc_see_skb(skb, rxrpc_skb_seen);
 397                 sp = rxrpc_skb(skb);
 398
 399                 if (!(flags & MSG_PEEK)) {
 400                         serial = sp->hdr.serial;
 401                         serial += call->rxtx_annotations[ix] & RXRPC_RX_ANNO_SUBPACKET;
 402                         trace_rxrpc_receive(call, rxrpc_receive_front,
 403                                             serial, seq);
 404                 }
 405
 406                 if (msg)
 407                         sock_recv_timestamp(msg, sock->sk, skb);
 408
 409                 if (rx_pkt_offset == 0) {
 410                         ret2 = rxrpc_locate_data(call, skb,
 411                                                  &call->rxtx_annotations[ix],
 412                                                  &rx_pkt_offset, &rx_pkt_len,
 413                                                  &rx_pkt_last);
 414                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq,
 415                                             rx_pkt_offset, rx_pkt_len, ret2);
 416                         if (ret2 < 0) {
 417                                 ret = ret2;
 418                                 goto out;
 419                         }
 420                 } else {
 421                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq,
 422                                             rx_pkt_offset, rx_pkt_len, 0);
 423                 }
 424
 425                 /* We have to handle short, empty and used-up DATA packets. */
 426                 remain = len - *_offset;
 427                 copy = rx_pkt_len;
 428                 if (copy > remain)
 429                         copy = remain;
 430                 if (copy > 0) {
 431                         ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter,
 432                                                       copy);
 433                         if (ret2 < 0) {
 434                                 ret = ret2;
 435                                 goto out;
 436                         }
 437
 438                         /* handle piecemeal consumption of data packets */
 439                         rx_pkt_offset += copy;
 440                         rx_pkt_len -= copy;
 441                         *_offset += copy;
 442                 }
 443
 444                 if (rx_pkt_len > 0) {
 445                         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq,
 446                                             rx_pkt_offset, rx_pkt_len, 0);
 447                         ASSERTCMP(*_offset, ==, len);
 448                         ret = 0;
 449                         break;
 450                 }
 451
 452                 /* The whole packet has been transferred. */
 453                 if (!(flags & MSG_PEEK))
 454                         rxrpc_rotate_rx_window(call);
 455                 rx_pkt_offset = 0;
 456                 rx_pkt_len = 0;
 457
 458                 if (rx_pkt_last) {
 459                         ASSERTCMP(seq, ==, READ_ONCE(call->rx_top));
 460                         ret = 1;
 461                         goto out;
 462                 }
 463
 464                 seq++;
 465         }
 466
 467 out:
 468         if (!(flags & MSG_PEEK)) {
 469                 call->rx_pkt_offset = rx_pkt_offset;
 470                 call->rx_pkt_len = rx_pkt_len;
 471                 call->rx_pkt_last = rx_pkt_last;
 472         }
 473 done:
 474         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_data_return, seq,
 475                             rx_pkt_offset, rx_pkt_len, ret);
 476         if (ret == -EAGAIN)
 477                 set_bit(RXRPC_CALL_RX_UNDERRUN, &call->flags);
 478         return ret;
 479 }
 480
 481 /*
 482  * Receive a message from an RxRPC socket
 483  * - we need to be careful about two or more threads calling recvmsg
 484  *   simultaneously
 485  */
 486 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 487                   int flags)
 488 {
 489         struct rxrpc_call *call;
 490         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
 491         struct list_head *l;
 492         size_t copied = 0;
 493         long timeo;
 494         int ret;
 495
 496         DEFINE_WAIT(wait);
 497
 498         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_enter, 0, 0, 0, 0);
 499
 500         if (flags & (MSG_OOB | MSG_TRUNC))
 501                 return -EOPNOTSUPP;
 502
 503         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
 504
 505 try_again:
 506         lock_sock(&rx->sk);
 507
 508         /* Return immediately if a client socket has no outstanding calls */
 509         if (RB_EMPTY_ROOT(&rx->calls) &&
 510             list_empty(&rx->recvmsg_q) &&
 511             rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
 512                 release_sock(&rx->sk);
 513                 return -EAGAIN;
 514         }
 515
 516         if (list_empty(&rx->recvmsg_q)) {
 517                 ret = -EWOULDBLOCK;
 518                 if (timeo == 0) {
 519                         call = NULL;
 520                         goto error_no_call;
 521                 }
 522
 523                 release_sock(&rx->sk);
 524
 525                 /* Wait for something to happen */
 526                 prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
 527                                           TASK_INTERRUPTIBLE);
 528                 ret = sock_error(&rx->sk);
 529                 if (ret)
 530                         goto wait_error;
 531
 532                 if (list_empty(&rx->recvmsg_q)) {
 533                         if (signal_pending(current))
 534                                 goto wait_interrupted;
 535                         trace_rxrpc_recvmsg(NULL, rxrpc_recvmsg_wait,
 536                                             0, 0, 0, 0);
 537                         timeo = schedule_timeout(timeo);
 538                 }
 539                 finish_wait(sk_sleep(&rx->sk), &wait);
 540                 goto try_again;
 541         }
 542
 543         /* Find the next call and dequeue it if we're not just peeking.  If we
 544          * do dequeue it, that comes with a ref that we will need to release.
 545          */
 546         write_lock_bh(&rx->recvmsg_lock);
 547         l = rx->recvmsg_q.next;
 548         call = list_entry(l, struct rxrpc_call, recvmsg_link);
 549         if (!(flags & MSG_PEEK))
 550                 list_del_init(&call->recvmsg_link);
 551         else
 552                 rxrpc_get_call(call, rxrpc_call_got);
 553         write_unlock_bh(&rx->recvmsg_lock);
 554
 555         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_dequeue, 0, 0, 0, 0);
 556
 557         /* We're going to drop the socket lock, so we need to lock the call
 558          * against interference by sendmsg.
 559          */
 560         if (!mutex_trylock(&call->user_mutex)) {
 561                 ret = -EWOULDBLOCK;
 562                 if (flags & MSG_DONTWAIT)
 563                         goto error_requeue_call;
 564                 ret = -ERESTARTSYS;
 565                 if (mutex_lock_interruptible(&call->user_mutex) < 0)
 566                         goto error_requeue_call;
 567         }
 568
 569         release_sock(&rx->sk);
 570
 571         if (test_bit(RXRPC_CALL_RELEASED, &call->flags))
 572                 BUG();
 573
 574         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
 575                 if (flags & MSG_CMSG_COMPAT) {
 576                         unsigned int id32 = call->user_call_ID;
 577
 578                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 579                                        sizeof(unsigned int), &id32);
 580                 } else {
 581                         unsigned long idl = call->user_call_ID;
 582
 583                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 584                                        sizeof(unsigned long), &idl);
 585                 }
 586                 if (ret < 0)
 587                         goto error_unlock_call;
 588         }
 589
 590         if (msg->msg_name && call->peer) {
 591                 struct sockaddr_rxrpc *srx = msg->msg_name;
 592                 size_t len = sizeof(call->peer->srx);
 593
 594                 memcpy(msg->msg_name, &call->peer->srx, len);
 595                 srx->srx_service = call->service_id;
 596                 msg->msg_namelen = len;
 597         }
 598
 599         switch (READ_ONCE(call->state)) {
 600         case RXRPC_CALL_CLIENT_RECV_REPLY:
 601         case RXRPC_CALL_SERVER_RECV_REQUEST:
 602         case RXRPC_CALL_SERVER_ACK_REQUEST:
 603                 ret = rxrpc_recvmsg_data(sock, call, msg, &msg->msg_iter, len,
 604                                          flags, &copied);
 605                 if (ret == -EAGAIN)
 606                         ret = 0;
 607
 608                 if (after(call->rx_top, call->rx_hard_ack) &&
 609                     call->rxtx_buffer[(call->rx_hard_ack + 1) & RXRPC_RXTX_BUFF_MASK])
 610                         rxrpc_notify_socket(call);
 611                 break;
 612         default:
 613                 ret = 0;
 614                 break;
 615         }
 616
 617         if (ret < 0)
 618                 goto error_unlock_call;
 619
 620         if (call->state == RXRPC_CALL_COMPLETE) {
 621                 ret = rxrpc_recvmsg_term(call, msg);
 622                 if (ret < 0)
 623                         goto error_unlock_call;
 624                 if (!(flags & MSG_PEEK))
 625                         rxrpc_release_call(rx, call);
 626                 msg->msg_flags |= MSG_EOR;
 627                 ret = 1;
 628         }
 629
 630         if (ret == 0)
 631                 msg->msg_flags |= MSG_MORE;
 632         else
 633                 msg->msg_flags &= ~MSG_MORE;
 634         ret = copied;
 635
 636 error_unlock_call:
 637         mutex_unlock(&call->user_mutex);
 638         rxrpc_put_call(call, rxrpc_call_put);
 639         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 640         return ret;
 641
 642 error_requeue_call:
 643         if (!(flags & MSG_PEEK)) {
 644                 write_lock_bh(&rx->recvmsg_lock);
 645                 list_add(&call->recvmsg_link, &rx->recvmsg_q);
 646                 write_unlock_bh(&rx->recvmsg_lock);
 647                 trace_rxrpc_recvmsg(call, rxrpc_recvmsg_requeue, 0, 0, 0, 0);
 648         } else {
 649                 rxrpc_put_call(call, rxrpc_call_put);
 650         }
 651 error_no_call:
 652         release_sock(&rx->sk);
 653 error_trace:
 654         trace_rxrpc_recvmsg(call, rxrpc_recvmsg_return, 0, 0, 0, ret);
 655         return ret;
 656
 657 wait_interrupted:
 658         ret = sock_intr_errno(timeo);
 659 wait_error:
 660         finish_wait(sk_sleep(&rx->sk), &wait);
 661         call = NULL;
 662         goto error_trace;
 663 }
 664
 665 /**
 666  * rxrpc_kernel_recv_data - Allow a kernel service to receive data/info
 667  * @sock: The socket that the call exists on
 668  * @call: The call to send data through
 669  * @iter: The buffer to receive into
 670  * @_len: The amount of data we want to receive (decreased on return)
 671  * @want_more: True if more data is expected to be read
 672  * @_abort: Where the abort code is stored if -ECONNABORTED is returned
 673  * @_service: Where to store the actual service ID (may be upgraded)
 674  *
 675  * Allow a kernel service to receive data and pick up information about the
 676  * state of a call.  Returns 0 if got what was asked for and there's more
 677  * available, 1 if we got what was asked for and we're at the end of the data
 678  * and -EAGAIN if we need more data.
 679  *
 680  * Note that we may return -EAGAIN to drain empty packets at the end of the
 681  * data, even if we've already copied over the requested data.
 682  *
 683  * *_abort should also be initialised to 0.
 684  */
 685 int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
 686                            struct iov_iter *iter, size_t *_len,
 687                            bool want_more, u32 *_abort, u16 *_service)
 688 {
 689         size_t offset = 0;
 690         int ret;
 691
 692         _enter("{%d,%s},%zu,%d",
 693                call->debug_id, rxrpc_call_states[call->state],
 694                *_len, want_more);
 695
 696         ASSERTCMP(call->state, !=, RXRPC_CALL_SERVER_SECURING);
 697
 698         mutex_lock(&call->user_mutex);
 699
 700         switch (READ_ONCE(call->state)) {
 701         case RXRPC_CALL_CLIENT_RECV_REPLY:
 702         case RXRPC_CALL_SERVER_RECV_REQUEST:
 703         case RXRPC_CALL_SERVER_ACK_REQUEST:
 704                 ret = rxrpc_recvmsg_data(sock, call, NULL, iter,
 705                                          *_len, 0, &offset);
 706                 *_len -= offset;
 707                 if (ret < 0)
 708                         goto out;
 709
 710                 /* We can only reach here with a partially full buffer if we
 711                  * have reached the end of the data.  We must otherwise have a
 712                  * full buffer or have been given -EAGAIN.
 713                  */
 714                 if (ret == 1) {
 715                         if (iov_iter_count(iter) > 0)
 716                                 goto short_data;
 717                         if (!want_more)
 718                                 goto read_phase_complete;
 719                         ret = 0;
 720                         goto out;
 721                 }
 722
 723                 if (!want_more)
 724                         goto excess_data;
 725                 goto out;
 726
 727         case RXRPC_CALL_COMPLETE:
 728                 goto call_complete;
 729
 730         default:
 731                 ret = -EINPROGRESS;
 732                 goto out;
 733         }
 734
 735 read_phase_complete:
 736         ret = 1;
 737 out:
 738         switch (call->ackr_reason) {
 739         case RXRPC_ACK_IDLE:
 740                 break;
 741         case RXRPC_ACK_DELAY:
 742                 if (ret != -EAGAIN)
 743                         break;
 744                 fallthrough;
 745         default:
 746                 rxrpc_send_ack_packet(call, false, NULL);
 747         }
 748
 749         if (_service)
 750                 *_service = call->service_id;
 751         mutex_unlock(&call->user_mutex);
 752         _leave(" = %d [%zu,%d]", ret, iov_iter_count(iter), *_abort);
 753         return ret;
 754
 755 short_data:
 756         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("short_data"));
 757         ret = -EBADMSG;
 758         goto out;
 759 excess_data:
 760         trace_rxrpc_rx_eproto(call, 0, tracepoint_string("excess_data"));
 761         ret = -EMSGSIZE;
 762         goto out;
 763 call_complete:
 764         *_abort = call->abort_code;
 765         ret = call->error;
 766         if (call->completion == RXRPC_CALL_SUCCEEDED) {
 767                 ret = 1;
 768                 if (iov_iter_count(iter) > 0)
 769                         ret = -ECONNRESET;
 770         }
 771         goto out;
 772 }
 773 EXPORT_SYMBOL(rxrpc_kernel_recv_data);