net/rxrpc/ar-recvmsg.c

   1 /* RxRPC recvmsg() implementation
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/net.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/export.h>
  15 #include <net/sock.h>
  16 #include <net/af_rxrpc.h>
  17 #include "ar-internal.h"
  18
  19 /*
  20  * removal a call's user ID from the socket tree to make the user ID available
  21  * again and so that it won't be seen again in association with that call
  22  */
  23 void rxrpc_remove_user_ID(struct rxrpc_sock *rx, struct rxrpc_call *call)
  24 {
  25         _debug("RELEASE CALL %d", call->debug_id);
  26
  27         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
  28                 write_lock_bh(&rx->call_lock);
  29                 rb_erase(&call->sock_node, &call->socket->calls);
  30                 clear_bit(RXRPC_CALL_HAS_USERID, &call->flags);
  31                 write_unlock_bh(&rx->call_lock);
  32         }
  33
  34         read_lock_bh(&call->state_lock);
  35         if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
  36             !test_and_set_bit(RXRPC_CALL_RELEASE, &call->events))
  37                 rxrpc_queue_call(call);
  38         read_unlock_bh(&call->state_lock);
  39 }
  40
  41 /*
  42  * receive a message from an RxRPC socket
  43  * - we need to be careful about two or more threads calling recvmsg
  44  *   simultaneously
  45  */
  46 int rxrpc_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
  47                   int flags)
  48 {
  49         struct rxrpc_skb_priv *sp;
  50         struct rxrpc_call *call = NULL, *continue_call = NULL;
  51         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
  52         struct sk_buff *skb;
  53         long timeo;
  54         int copy, ret, ullen, offset, copied = 0;
  55         u32 abort_code;
  56
  57         DEFINE_WAIT(wait);
  58
  59         _enter(",,,%zu,%d", len, flags);
  60
  61         if (flags & (MSG_OOB | MSG_TRUNC))
  62                 return -EOPNOTSUPP;
  63
  64         ullen = msg->msg_flags & MSG_CMSG_COMPAT ? 4 : sizeof(unsigned long);
  65
  66         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
  67         msg->msg_flags |= MSG_MORE;
  68
  69         lock_sock(&rx->sk);
  70
  71         for (;;) {
  72                 /* return immediately if a client socket has no outstanding
  73                  * calls */
  74                 if (RB_EMPTY_ROOT(&rx->calls)) {
  75                         if (copied)
  76                                 goto out;
  77                         if (rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
  78                                 release_sock(&rx->sk);
  79                                 if (continue_call)
  80                                         rxrpc_put_call(continue_call);
  81                                 return -ENODATA;
  82                         }
  83                 }
  84
  85                 /* get the next message on the Rx queue */
  86                 skb = skb_peek(&rx->sk.sk_receive_queue);
  87                 if (!skb) {
  88                         /* nothing remains on the queue */
  89                         if (copied &&
  90                             (flags & MSG_PEEK || timeo == 0))
  91                                 goto out;
  92
  93                         /* wait for a message to turn up */
  94                         release_sock(&rx->sk);
  95                         prepare_to_wait_exclusive(sk_sleep(&rx->sk), &wait,
  96                                                   TASK_INTERRUPTIBLE);
  97                         ret = sock_error(&rx->sk);
  98                         if (ret)
  99                                 goto wait_error;
 100
 101                         if (skb_queue_empty(&rx->sk.sk_receive_queue)) {
 102                                 if (signal_pending(current))
 103                                         goto wait_interrupted;
 104                                 timeo = schedule_timeout(timeo);
 105                         }
 106                         finish_wait(sk_sleep(&rx->sk), &wait);
 107                         lock_sock(&rx->sk);
 108                         continue;
 109                 }
 110
 111         peek_next_packet:
 112                 sp = rxrpc_skb(skb);
 113                 call = sp->call;
 114                 ASSERT(call != NULL);
 115
 116                 _debug("next pkt %s", rxrpc_pkts[sp->hdr.type]);
 117
 118                 /* make sure we wait for the state to be updated in this call */
 119                 spin_lock_bh(&call->lock);
 120                 spin_unlock_bh(&call->lock);
 121
 122                 if (test_bit(RXRPC_CALL_RELEASED, &call->flags)) {
 123                         _debug("packet from released call");
 124                         if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 125                                 BUG();
 126                         rxrpc_free_skb(skb);
 127                         continue;
 128                 }
 129
 130                 /* determine whether to continue last data receive */
 131                 if (continue_call) {
 132                         _debug("maybe cont");
 133                         if (call != continue_call ||
 134                             skb->mark != RXRPC_SKB_MARK_DATA) {
 135                                 release_sock(&rx->sk);
 136                                 rxrpc_put_call(continue_call);
 137                                 _leave(" = %d [noncont]", copied);
 138                                 return copied;
 139                         }
 140                 }
 141
 142                 rxrpc_get_call(call);
 143
 144                 /* copy the peer address and timestamp */
 145                 if (!continue_call) {
 146                         if (msg->msg_name) {
 147                                 size_t len =
 148                                         sizeof(call->conn->trans->peer->srx);
 149                                 memcpy(msg->msg_name,
 150                                        &call->conn->trans->peer->srx, len);
 151                                 msg->msg_namelen = len;
 152                         }
 153                         sock_recv_timestamp(msg, &rx->sk, skb);
 154                 }
 155
 156                 /* receive the message */
 157                 if (skb->mark != RXRPC_SKB_MARK_DATA)
 158                         goto receive_non_data_message;
 159
 160                 _debug("recvmsg DATA #%u { %d, %d }",
 161                        ntohl(sp->hdr.seq), skb->len, sp->offset);
 162
 163                 if (!continue_call) {
 164                         /* only set the control data once per recvmsg() */
 165                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 166                                        ullen, &call->user_call_ID);
 167                         if (ret < 0)
 168                                 goto copy_error;
 169                         ASSERT(test_bit(RXRPC_CALL_HAS_USERID, &call->flags));
 170                 }
 171
 172                 ASSERTCMP(ntohl(sp->hdr.seq), >=, call->rx_data_recv);
 173                 ASSERTCMP(ntohl(sp->hdr.seq), <=, call->rx_data_recv + 1);
 174                 call->rx_data_recv = ntohl(sp->hdr.seq);
 175
 176                 ASSERTCMP(ntohl(sp->hdr.seq), >, call->rx_data_eaten);
 177
 178                 offset = sp->offset;
 179                 copy = skb->len - offset;
 180                 if (copy > len - copied)
 181                         copy = len - copied;
 182
 183                 ret = skb_copy_datagram_msg(skb, offset, msg, copy);
 184
 185                 if (ret < 0)
 186                         goto copy_error;
 187
 188                 /* handle piecemeal consumption of data packets */
 189                 _debug("copied %d+%d", copy, copied);
 190
 191                 offset += copy;
 192                 copied += copy;
 193
 194                 if (!(flags & MSG_PEEK))
 195                         sp->offset = offset;
 196
 197                 if (sp->offset < skb->len) {
 198                         _debug("buffer full");
 199                         ASSERTCMP(copied, ==, len);
 200                         break;
 201                 }
 202
 203                 /* we transferred the whole data packet */
 204                 if (sp->hdr.flags & RXRPC_LAST_PACKET) {
 205                         _debug("last");
 206                         if (call->conn->out_clientflag) {
 207                                  /* last byte of reply received */
 208                                 ret = copied;
 209                                 goto terminal_message;
 210                         }
 211
 212                         /* last bit of request received */
 213                         if (!(flags & MSG_PEEK)) {
 214                                 _debug("eat packet");
 215                                 if (skb_dequeue(&rx->sk.sk_receive_queue) !=
 216                                     skb)
 217                                         BUG();
 218                                 rxrpc_free_skb(skb);
 219                         }
 220                         msg->msg_flags &= ~MSG_MORE;
 221                         break;
 222                 }
 223
 224                 /* move on to the next data message */
 225                 _debug("next");
 226                 if (!continue_call)
 227                         continue_call = sp->call;
 228                 else
 229                         rxrpc_put_call(call);
 230                 call = NULL;
 231
 232                 if (flags & MSG_PEEK) {
 233                         _debug("peek next");
 234                         skb = skb->next;
 235                         if (skb == (struct sk_buff *) &rx->sk.sk_receive_queue)
 236                                 break;
 237                         goto peek_next_packet;
 238                 }
 239
 240                 _debug("eat packet");
 241                 if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 242                         BUG();
 243                 rxrpc_free_skb(skb);
 244         }
 245
 246         /* end of non-terminal data packet reception for the moment */
 247         _debug("end rcv data");
 248 out:
 249         release_sock(&rx->sk);
 250         if (call)
 251                 rxrpc_put_call(call);
 252         if (continue_call)
 253                 rxrpc_put_call(continue_call);
 254         _leave(" = %d [data]", copied);
 255         return copied;
 256
 257         /* handle non-DATA messages such as aborts, incoming connections and
 258          * final ACKs */
 259 receive_non_data_message:
 260         _debug("non-data");
 261
 262         if (skb->mark == RXRPC_SKB_MARK_NEW_CALL) {
 263                 _debug("RECV NEW CALL");
 264                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NEW_CALL, 0, &abort_code);
 265                 if (ret < 0)
 266                         goto copy_error;
 267                 if (!(flags & MSG_PEEK)) {
 268                         if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 269                                 BUG();
 270                         rxrpc_free_skb(skb);
 271                 }
 272                 goto out;
 273         }
 274
 275         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 276                        ullen, &call->user_call_ID);
 277         if (ret < 0)
 278                 goto copy_error;
 279         ASSERT(test_bit(RXRPC_CALL_HAS_USERID, &call->flags));
 280
 281         switch (skb->mark) {
 282         case RXRPC_SKB_MARK_DATA:
 283                 BUG();
 284         case RXRPC_SKB_MARK_FINAL_ACK:
 285                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &abort_code);
 286                 break;
 287         case RXRPC_SKB_MARK_BUSY:
 288                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_BUSY, 0, &abort_code);
 289                 break;
 290         case RXRPC_SKB_MARK_REMOTE_ABORT:
 291                 abort_code = call->abort_code;
 292                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &abort_code);
 293                 break;
 294         case RXRPC_SKB_MARK_NET_ERROR:
 295                 _debug("RECV NET ERROR %d", sp->error);
 296                 abort_code = sp->error;
 297                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &abort_code);
 298                 break;
 299         case RXRPC_SKB_MARK_LOCAL_ERROR:
 300                 _debug("RECV LOCAL ERROR %d", sp->error);
 301                 abort_code = sp->error;
 302                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4,
 303                                &abort_code);
 304                 break;
 305         default:
 306                 BUG();
 307                 break;
 308         }
 309
 310         if (ret < 0)
 311                 goto copy_error;
 312
 313 terminal_message:
 314         _debug("terminal");
 315         msg->msg_flags &= ~MSG_MORE;
 316         msg->msg_flags |= MSG_EOR;
 317
 318         if (!(flags & MSG_PEEK)) {
 319                 _net("free terminal skb %p", skb);
 320                 if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 321                         BUG();
 322                 rxrpc_free_skb(skb);
 323                 rxrpc_remove_user_ID(rx, call);
 324         }
 325
 326         release_sock(&rx->sk);
 327         rxrpc_put_call(call);
 328         if (continue_call)
 329                 rxrpc_put_call(continue_call);
 330         _leave(" = %d", ret);
 331         return ret;
 332
 333 copy_error:
 334         _debug("copy error");
 335         release_sock(&rx->sk);
 336         rxrpc_put_call(call);
 337         if (continue_call)
 338                 rxrpc_put_call(continue_call);
 339         _leave(" = %d", ret);
 340         return ret;
 341
 342 wait_interrupted:
 343         ret = sock_intr_errno(timeo);
 344 wait_error:
 345         finish_wait(sk_sleep(&rx->sk), &wait);
 346         if (continue_call)
 347                 rxrpc_put_call(continue_call);
 348         if (copied)
 349                 copied = ret;
 350         _leave(" = %d [waitfail %d]", copied, ret);
 351         return copied;
 352
 353 }
 354
 355 /**
 356  * rxrpc_kernel_data_delivered - Record delivery of data message
 357  * @skb: Message holding data
 358  *
 359  * Record the delivery of a data message.  This permits RxRPC to keep its
 360  * tracking correct.  The socket buffer will be deleted.
 361  */
 362 void rxrpc_kernel_data_delivered(struct sk_buff *skb)
 363 {
 364         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 365         struct rxrpc_call *call = sp->call;
 366
 367         ASSERTCMP(ntohl(sp->hdr.seq), >=, call->rx_data_recv);
 368         ASSERTCMP(ntohl(sp->hdr.seq), <=, call->rx_data_recv + 1);
 369         call->rx_data_recv = ntohl(sp->hdr.seq);
 370
 371         ASSERTCMP(ntohl(sp->hdr.seq), >, call->rx_data_eaten);
 372         rxrpc_free_skb(skb);
 373 }
 374
 375 EXPORT_SYMBOL(rxrpc_kernel_data_delivered);
 376
 377 /**
 378  * rxrpc_kernel_is_data_last - Determine if data message is last one
 379  * @skb: Message holding data
 380  *
 381  * Determine if data message is last one for the parent call.
 382  */
 383 bool rxrpc_kernel_is_data_last(struct sk_buff *skb)
 384 {
 385         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 386
 387         ASSERTCMP(skb->mark, ==, RXRPC_SKB_MARK_DATA);
 388
 389         return sp->hdr.flags & RXRPC_LAST_PACKET;
 390 }
 391
 392 EXPORT_SYMBOL(rxrpc_kernel_is_data_last);
 393
 394 /**
 395  * rxrpc_kernel_get_abort_code - Get the abort code from an RxRPC abort message
 396  * @skb: Message indicating an abort
 397  *
 398  * Get the abort code from an RxRPC abort message.
 399  */
 400 u32 rxrpc_kernel_get_abort_code(struct sk_buff *skb)
 401 {
 402         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 403
 404         ASSERTCMP(skb->mark, ==, RXRPC_SKB_MARK_REMOTE_ABORT);
 405
 406         return sp->call->abort_code;
 407 }
 408
 409 EXPORT_SYMBOL(rxrpc_kernel_get_abort_code);
 410
 411 /**
 412  * rxrpc_kernel_get_error - Get the error number from an RxRPC error message
 413  * @skb: Message indicating an error
 414  *
 415  * Get the error number from an RxRPC error message.
 416  */
 417 int rxrpc_kernel_get_error_number(struct sk_buff *skb)
 418 {
 419         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 420
 421         return sp->error;
 422 }
 423
 424 EXPORT_SYMBOL(rxrpc_kernel_get_error_number);