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 kiocb *iocb, struct socket *sock,
  47                   struct msghdr *msg, size_t len, 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_ts_and_drops(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                 if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
 184                         ret = skb_copy_datagram_iovec(skb, offset,
 185                                                       msg->msg_iov, copy);
 186                 } else {
 187                         ret = skb_copy_and_csum_datagram_iovec(skb, offset,
 188                                                                msg->msg_iov);
 189                         if (ret == -EINVAL)
 190                                 goto csum_copy_error;
 191                 }
 192
 193                 if (ret < 0)
 194                         goto copy_error;
 195
 196                 /* handle piecemeal consumption of data packets */
 197                 _debug("copied %d+%d", copy, copied);
 198
 199                 offset += copy;
 200                 copied += copy;
 201
 202                 if (!(flags & MSG_PEEK))
 203                         sp->offset = offset;
 204
 205                 if (sp->offset < skb->len) {
 206                         _debug("buffer full");
 207                         ASSERTCMP(copied, ==, len);
 208                         break;
 209                 }
 210
 211                 /* we transferred the whole data packet */
 212                 if (sp->hdr.flags & RXRPC_LAST_PACKET) {
 213                         _debug("last");
 214                         if (call->conn->out_clientflag) {
 215                                  /* last byte of reply received */
 216                                 ret = copied;
 217                                 goto terminal_message;
 218                         }
 219
 220                         /* last bit of request received */
 221                         if (!(flags & MSG_PEEK)) {
 222                                 _debug("eat packet");
 223                                 if (skb_dequeue(&rx->sk.sk_receive_queue) !=
 224                                     skb)
 225                                         BUG();
 226                                 rxrpc_free_skb(skb);
 227                         }
 228                         msg->msg_flags &= ~MSG_MORE;
 229                         break;
 230                 }
 231
 232                 /* move on to the next data message */
 233                 _debug("next");
 234                 if (!continue_call)
 235                         continue_call = sp->call;
 236                 else
 237                         rxrpc_put_call(call);
 238                 call = NULL;
 239
 240                 if (flags & MSG_PEEK) {
 241                         _debug("peek next");
 242                         skb = skb->next;
 243                         if (skb == (struct sk_buff *) &rx->sk.sk_receive_queue)
 244                                 break;
 245                         goto peek_next_packet;
 246                 }
 247
 248                 _debug("eat packet");
 249                 if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 250                         BUG();
 251                 rxrpc_free_skb(skb);
 252         }
 253
 254         /* end of non-terminal data packet reception for the moment */
 255         _debug("end rcv data");
 256 out:
 257         release_sock(&rx->sk);
 258         if (call)
 259                 rxrpc_put_call(call);
 260         if (continue_call)
 261                 rxrpc_put_call(continue_call);
 262         _leave(" = %d [data]", copied);
 263         return copied;
 264
 265         /* handle non-DATA messages such as aborts, incoming connections and
 266          * final ACKs */
 267 receive_non_data_message:
 268         _debug("non-data");
 269
 270         if (skb->mark == RXRPC_SKB_MARK_NEW_CALL) {
 271                 _debug("RECV NEW CALL");
 272                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NEW_CALL, 0, &abort_code);
 273                 if (ret < 0)
 274                         goto copy_error;
 275                 if (!(flags & MSG_PEEK)) {
 276                         if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 277                                 BUG();
 278                         rxrpc_free_skb(skb);
 279                 }
 280                 goto out;
 281         }
 282
 283         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 284                        ullen, &call->user_call_ID);
 285         if (ret < 0)
 286                 goto copy_error;
 287         ASSERT(test_bit(RXRPC_CALL_HAS_USERID, &call->flags));
 288
 289         switch (skb->mark) {
 290         case RXRPC_SKB_MARK_DATA:
 291                 BUG();
 292         case RXRPC_SKB_MARK_FINAL_ACK:
 293                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &abort_code);
 294                 break;
 295         case RXRPC_SKB_MARK_BUSY:
 296                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_BUSY, 0, &abort_code);
 297                 break;
 298         case RXRPC_SKB_MARK_REMOTE_ABORT:
 299                 abort_code = call->abort_code;
 300                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &abort_code);
 301                 break;
 302         case RXRPC_SKB_MARK_NET_ERROR:
 303                 _debug("RECV NET ERROR %d", sp->error);
 304                 abort_code = sp->error;
 305                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &abort_code);
 306                 break;
 307         case RXRPC_SKB_MARK_LOCAL_ERROR:
 308                 _debug("RECV LOCAL ERROR %d", sp->error);
 309                 abort_code = sp->error;
 310                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4,
 311                                &abort_code);
 312                 break;
 313         default:
 314                 BUG();
 315                 break;
 316         }
 317
 318         if (ret < 0)
 319                 goto copy_error;
 320
 321 terminal_message:
 322         _debug("terminal");
 323         msg->msg_flags &= ~MSG_MORE;
 324         msg->msg_flags |= MSG_EOR;
 325
 326         if (!(flags & MSG_PEEK)) {
 327                 _net("free terminal skb %p", skb);
 328                 if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 329                         BUG();
 330                 rxrpc_free_skb(skb);
 331                 rxrpc_remove_user_ID(rx, call);
 332         }
 333
 334         release_sock(&rx->sk);
 335         rxrpc_put_call(call);
 336         if (continue_call)
 337                 rxrpc_put_call(continue_call);
 338         _leave(" = %d", ret);
 339         return ret;
 340
 341 copy_error:
 342         _debug("copy error");
 343         release_sock(&rx->sk);
 344         rxrpc_put_call(call);
 345         if (continue_call)
 346                 rxrpc_put_call(continue_call);
 347         _leave(" = %d", ret);
 348         return ret;
 349
 350 csum_copy_error:
 351         _debug("csum error");
 352         release_sock(&rx->sk);
 353         if (continue_call)
 354                 rxrpc_put_call(continue_call);
 355         rxrpc_kill_skb(skb);
 356         skb_kill_datagram(&rx->sk, skb, flags);
 357         rxrpc_put_call(call);
 358         return -EAGAIN;
 359
 360 wait_interrupted:
 361         ret = sock_intr_errno(timeo);
 362 wait_error:
 363         finish_wait(sk_sleep(&rx->sk), &wait);
 364         if (continue_call)
 365                 rxrpc_put_call(continue_call);
 366         if (copied)
 367                 copied = ret;
 368         _leave(" = %d [waitfail %d]", copied, ret);
 369         return copied;
 370
 371 }
 372
 373 /**
 374  * rxrpc_kernel_data_delivered - Record delivery of data message
 375  * @skb: Message holding data
 376  *
 377  * Record the delivery of a data message.  This permits RxRPC to keep its
 378  * tracking correct.  The socket buffer will be deleted.
 379  */
 380 void rxrpc_kernel_data_delivered(struct sk_buff *skb)
 381 {
 382         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 383         struct rxrpc_call *call = sp->call;
 384
 385         ASSERTCMP(ntohl(sp->hdr.seq), >=, call->rx_data_recv);
 386         ASSERTCMP(ntohl(sp->hdr.seq), <=, call->rx_data_recv + 1);
 387         call->rx_data_recv = ntohl(sp->hdr.seq);
 388
 389         ASSERTCMP(ntohl(sp->hdr.seq), >, call->rx_data_eaten);
 390         rxrpc_free_skb(skb);
 391 }
 392
 393 EXPORT_SYMBOL(rxrpc_kernel_data_delivered);
 394
 395 /**
 396  * rxrpc_kernel_is_data_last - Determine if data message is last one
 397  * @skb: Message holding data
 398  *
 399  * Determine if data message is last one for the parent call.
 400  */
 401 bool rxrpc_kernel_is_data_last(struct sk_buff *skb)
 402 {
 403         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 404
 405         ASSERTCMP(skb->mark, ==, RXRPC_SKB_MARK_DATA);
 406
 407         return sp->hdr.flags & RXRPC_LAST_PACKET;
 408 }
 409
 410 EXPORT_SYMBOL(rxrpc_kernel_is_data_last);
 411
 412 /**
 413  * rxrpc_kernel_get_abort_code - Get the abort code from an RxRPC abort message
 414  * @skb: Message indicating an abort
 415  *
 416  * Get the abort code from an RxRPC abort message.
 417  */
 418 u32 rxrpc_kernel_get_abort_code(struct sk_buff *skb)
 419 {
 420         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 421
 422         ASSERTCMP(skb->mark, ==, RXRPC_SKB_MARK_REMOTE_ABORT);
 423
 424         return sp->call->abort_code;
 425 }
 426
 427 EXPORT_SYMBOL(rxrpc_kernel_get_abort_code);
 428
 429 /**
 430  * rxrpc_kernel_get_error - Get the error number from an RxRPC error message
 431  * @skb: Message indicating an error
 432  *
 433  * Get the error number from an RxRPC error message.
 434  */
 435 int rxrpc_kernel_get_error_number(struct sk_buff *skb)
 436 {
 437         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 438
 439         return sp->error;
 440 }
 441
 442 EXPORT_SYMBOL(rxrpc_kernel_get_error_number);