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 <net/sock.h>
  15 #include <net/af_rxrpc.h>
  16 #include "ar-internal.h"
  17
  18 /*
  19  * removal a call's user ID from the socket tree to make the user ID available
  20  * again and so that it won't be seen again in association with that call
  21  */
  22 void rxrpc_remove_user_ID(struct rxrpc_sock *rx, struct rxrpc_call *call)
  23 {
  24         _debug("RELEASE CALL %d", call->debug_id);
  25
  26         if (test_bit(RXRPC_CALL_HAS_USERID, &call->flags)) {
  27                 write_lock_bh(&rx->call_lock);
  28                 rb_erase(&call->sock_node, &call->socket->calls);
  29                 clear_bit(RXRPC_CALL_HAS_USERID, &call->flags);
  30                 write_unlock_bh(&rx->call_lock);
  31         }
  32
  33         read_lock_bh(&call->state_lock);
  34         if (!test_bit(RXRPC_CALL_RELEASED, &call->flags) &&
  35             !test_and_set_bit(RXRPC_CALL_RELEASE, &call->events))
  36                 rxrpc_queue_call(call);
  37         read_unlock_bh(&call->state_lock);
  38 }
  39
  40 /*
  41  * receive a message from an RxRPC socket
  42  * - we need to be careful about two or more threads calling recvmsg
  43  *   simultaneously
  44  */
  45 int rxrpc_recvmsg(struct kiocb *iocb, struct socket *sock,
  46                   struct msghdr *msg, size_t len, int flags)
  47 {
  48         struct rxrpc_skb_priv *sp;
  49         struct rxrpc_call *call = NULL, *continue_call = NULL;
  50         struct rxrpc_sock *rx = rxrpc_sk(sock->sk);
  51         struct sk_buff *skb;
  52         long timeo;
  53         int copy, ret, ullen, offset, copied = 0;
  54         u32 abort_code;
  55
  56         DEFINE_WAIT(wait);
  57
  58         _enter(",,,%zu,%d", len, flags);
  59
  60         if (flags & (MSG_OOB | MSG_TRUNC))
  61                 return -EOPNOTSUPP;
  62
  63         ullen = msg->msg_flags & MSG_CMSG_COMPAT ? 4 : sizeof(unsigned long);
  64
  65         timeo = sock_rcvtimeo(&rx->sk, flags & MSG_DONTWAIT);
  66         msg->msg_flags |= MSG_MORE;
  67
  68         lock_sock(&rx->sk);
  69
  70         for (;;) {
  71                 /* return immediately if a client socket has no outstanding
  72                  * calls */
  73                 if (RB_EMPTY_ROOT(&rx->calls)) {
  74                         if (copied)
  75                                 goto out;
  76                         if (rx->sk.sk_state != RXRPC_SERVER_LISTENING) {
  77                                 release_sock(&rx->sk);
  78                                 if (continue_call)
  79                                         rxrpc_put_call(continue_call);
  80                                 return -ENODATA;
  81                         }
  82                 }
  83
  84                 /* get the next message on the Rx queue */
  85                 skb = skb_peek(&rx->sk.sk_receive_queue);
  86                 if (!skb) {
  87                         /* nothing remains on the queue */
  88                         if (copied &&
  89                             (msg->msg_flags & MSG_PEEK || timeo == 0))
  90                                 goto out;
  91
  92                         /* wait for a message to turn up */
  93                         release_sock(&rx->sk);
  94                         prepare_to_wait_exclusive(rx->sk.sk_sleep, &wait,
  95                                                   TASK_INTERRUPTIBLE);
  96                         ret = sock_error(&rx->sk);
  97                         if (ret)
  98                                 goto wait_error;
  99
 100                         if (skb_queue_empty(&rx->sk.sk_receive_queue)) {
 101                                 if (signal_pending(current))
 102                                         goto wait_interrupted;
 103                                 timeo = schedule_timeout(timeo);
 104                         }
 105                         finish_wait(rx->sk.sk_sleep, &wait);
 106                         lock_sock(&rx->sk);
 107                         continue;
 108                 }
 109
 110         peek_next_packet:
 111                 sp = rxrpc_skb(skb);
 112                 call = sp->call;
 113                 ASSERT(call != NULL);
 114
 115                 _debug("next pkt %s", rxrpc_pkts[sp->hdr.type]);
 116
 117                 /* make sure we wait for the state to be updated in this call */
 118                 spin_lock_bh(&call->lock);
 119                 spin_unlock_bh(&call->lock);
 120
 121                 if (test_bit(RXRPC_CALL_RELEASED, &call->flags)) {
 122                         _debug("packet from released call");
 123                         if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 124                                 BUG();
 125                         rxrpc_free_skb(skb);
 126                         continue;
 127                 }
 128
 129                 /* determine whether to continue last data receive */
 130                 if (continue_call) {
 131                         _debug("maybe cont");
 132                         if (call != continue_call ||
 133                             skb->mark != RXRPC_SKB_MARK_DATA) {
 134                                 release_sock(&rx->sk);
 135                                 rxrpc_put_call(continue_call);
 136                                 _leave(" = %d [noncont]", copied);
 137                                 return copied;
 138                         }
 139                 }
 140
 141                 rxrpc_get_call(call);
 142
 143                 /* copy the peer address and timestamp */
 144                 if (!continue_call) {
 145                         if (msg->msg_name && msg->msg_namelen > 0)
 146                                 memcpy(msg->msg_name,
 147                                        &call->conn->trans->peer->srx,
 148                                        sizeof(call->conn->trans->peer->srx));
 149                         sock_recv_timestamp(msg, &rx->sk, skb);
 150                 }
 151
 152                 /* receive the message */
 153                 if (skb->mark != RXRPC_SKB_MARK_DATA)
 154                         goto receive_non_data_message;
 155
 156                 _debug("recvmsg DATA #%u { %d, %d }",
 157                        ntohl(sp->hdr.seq), skb->len, sp->offset);
 158
 159                 if (!continue_call) {
 160                         /* only set the control data once per recvmsg() */
 161                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 162                                        ullen, &call->user_call_ID);
 163                         if (ret < 0)
 164                                 goto copy_error;
 165                         ASSERT(test_bit(RXRPC_CALL_HAS_USERID, &call->flags));
 166                 }
 167
 168                 ASSERTCMP(ntohl(sp->hdr.seq), >=, call->rx_data_recv);
 169                 ASSERTCMP(ntohl(sp->hdr.seq), <=, call->rx_data_recv + 1);
 170                 call->rx_data_recv = ntohl(sp->hdr.seq);
 171
 172                 ASSERTCMP(ntohl(sp->hdr.seq), >, call->rx_data_eaten);
 173
 174                 offset = sp->offset;
 175                 copy = skb->len - offset;
 176                 if (copy > len - copied)
 177                         copy = len - copied;
 178
 179                 if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
 180                         ret = skb_copy_datagram_iovec(skb, offset,
 181                                                       msg->msg_iov, copy);
 182                 } else {
 183                         ret = skb_copy_and_csum_datagram_iovec(skb, offset,
 184                                                                msg->msg_iov);
 185                         if (ret == -EINVAL)
 186                                 goto csum_copy_error;
 187                 }
 188
 189                 if (ret < 0)
 190                         goto copy_error;
 191
 192                 /* handle piecemeal consumption of data packets */
 193                 _debug("copied %d+%d", copy, copied);
 194
 195                 offset += copy;
 196                 copied += copy;
 197
 198                 if (!(flags & MSG_PEEK))
 199                         sp->offset = offset;
 200
 201                 if (sp->offset < skb->len) {
 202                         _debug("buffer full");
 203                         ASSERTCMP(copied, ==, len);
 204                         break;
 205                 }
 206
 207                 /* we transferred the whole data packet */
 208                 if (sp->hdr.flags & RXRPC_LAST_PACKET) {
 209                         _debug("last");
 210                         if (call->conn->out_clientflag) {
 211                                  /* last byte of reply received */
 212                                 ret = copied;
 213                                 goto terminal_message;
 214                         }
 215
 216                         /* last bit of request received */
 217                         if (!(flags & MSG_PEEK)) {
 218                                 _debug("eat packet");
 219                                 if (skb_dequeue(&rx->sk.sk_receive_queue) !=
 220                                     skb)
 221                                         BUG();
 222                                 rxrpc_free_skb(skb);
 223                         }
 224                         msg->msg_flags &= ~MSG_MORE;
 225                         break;
 226                 }
 227
 228                 /* move on to the next data message */
 229                 _debug("next");
 230                 if (!continue_call)
 231                         continue_call = sp->call;
 232                 else
 233                         rxrpc_put_call(call);
 234                 call = NULL;
 235
 236                 if (flags & MSG_PEEK) {
 237                         _debug("peek next");
 238                         skb = skb->next;
 239                         if (skb == (struct sk_buff *) &rx->sk.sk_receive_queue)
 240                                 break;
 241                         goto peek_next_packet;
 242                 }
 243
 244                 _debug("eat packet");
 245                 if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 246                         BUG();
 247                 rxrpc_free_skb(skb);
 248         }
 249
 250         /* end of non-terminal data packet reception for the moment */
 251         _debug("end rcv data");
 252 out:
 253         release_sock(&rx->sk);
 254         if (call)
 255                 rxrpc_put_call(call);
 256         if (continue_call)
 257                 rxrpc_put_call(continue_call);
 258         _leave(" = %d [data]", copied);
 259         return copied;
 260
 261         /* handle non-DATA messages such as aborts, incoming connections and
 262          * final ACKs */
 263 receive_non_data_message:
 264         _debug("non-data");
 265
 266         if (skb->mark == RXRPC_SKB_MARK_NEW_CALL) {
 267                 _debug("RECV NEW CALL");
 268                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NEW_CALL, 0, &abort_code);
 269                 if (ret < 0)
 270                         goto copy_error;
 271                 if (!(flags & MSG_PEEK)) {
 272                         if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 273                                 BUG();
 274                         rxrpc_free_skb(skb);
 275                 }
 276                 goto out;
 277         }
 278
 279         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 280                        ullen, &call->user_call_ID);
 281         if (ret < 0)
 282                 goto copy_error;
 283         ASSERT(test_bit(RXRPC_CALL_HAS_USERID, &call->flags));
 284
 285         switch (skb->mark) {
 286         case RXRPC_SKB_MARK_DATA:
 287                 BUG();
 288         case RXRPC_SKB_MARK_FINAL_ACK:
 289                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &abort_code);
 290                 break;
 291         case RXRPC_SKB_MARK_BUSY:
 292                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_BUSY, 0, &abort_code);
 293                 break;
 294         case RXRPC_SKB_MARK_REMOTE_ABORT:
 295                 abort_code = call->abort_code;
 296                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &abort_code);
 297                 break;
 298         case RXRPC_SKB_MARK_NET_ERROR:
 299                 _debug("RECV NET ERROR %d", sp->error);
 300                 abort_code = sp->error;
 301                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &abort_code);
 302                 break;
 303         case RXRPC_SKB_MARK_LOCAL_ERROR:
 304                 _debug("RECV LOCAL ERROR %d", sp->error);
 305                 abort_code = sp->error;
 306                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4,
 307                                &abort_code);
 308                 break;
 309         default:
 310                 BUG();
 311                 break;
 312         }
 313
 314         if (ret < 0)
 315                 goto copy_error;
 316
 317 terminal_message:
 318         _debug("terminal");
 319         msg->msg_flags &= ~MSG_MORE;
 320         msg->msg_flags |= MSG_EOR;
 321
 322         if (!(flags & MSG_PEEK)) {
 323                 _net("free terminal skb %p", skb);
 324                 if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 325                         BUG();
 326                 rxrpc_free_skb(skb);
 327                 rxrpc_remove_user_ID(rx, call);
 328         }
 329
 330         release_sock(&rx->sk);
 331         rxrpc_put_call(call);
 332         if (continue_call)
 333                 rxrpc_put_call(continue_call);
 334         _leave(" = %d", ret);
 335         return ret;
 336
 337 copy_error:
 338         _debug("copy error");
 339         release_sock(&rx->sk);
 340         rxrpc_put_call(call);
 341         if (continue_call)
 342                 rxrpc_put_call(continue_call);
 343         _leave(" = %d", ret);
 344         return ret;
 345
 346 csum_copy_error:
 347         _debug("csum error");
 348         release_sock(&rx->sk);
 349         if (continue_call)
 350                 rxrpc_put_call(continue_call);
 351         rxrpc_kill_skb(skb);
 352         skb_kill_datagram(&rx->sk, skb, flags);
 353         rxrpc_put_call(call);
 354         return -EAGAIN;
 355
 356 wait_interrupted:
 357         ret = sock_intr_errno(timeo);
 358 wait_error:
 359         finish_wait(rx->sk.sk_sleep, &wait);
 360         if (continue_call)
 361                 rxrpc_put_call(continue_call);
 362         if (copied)
 363                 copied = ret;
 364         _leave(" = %d [waitfail %d]", copied, ret);
 365         return copied;
 366
 367 }
 368
 369 /**
 370  * rxrpc_kernel_data_delivered - Record delivery of data message
 371  * @skb: Message holding data
 372  *
 373  * Record the delivery of a data message.  This permits RxRPC to keep its
 374  * tracking correct.  The socket buffer will be deleted.
 375  */
 376 void rxrpc_kernel_data_delivered(struct sk_buff *skb)
 377 {
 378         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 379         struct rxrpc_call *call = sp->call;
 380
 381         ASSERTCMP(ntohl(sp->hdr.seq), >=, call->rx_data_recv);
 382         ASSERTCMP(ntohl(sp->hdr.seq), <=, call->rx_data_recv + 1);
 383         call->rx_data_recv = ntohl(sp->hdr.seq);
 384
 385         ASSERTCMP(ntohl(sp->hdr.seq), >, call->rx_data_eaten);
 386         rxrpc_free_skb(skb);
 387 }
 388
 389 EXPORT_SYMBOL(rxrpc_kernel_data_delivered);
 390
 391 /**
 392  * rxrpc_kernel_is_data_last - Determine if data message is last one
 393  * @skb: Message holding data
 394  *
 395  * Determine if data message is last one for the parent call.
 396  */
 397 bool rxrpc_kernel_is_data_last(struct sk_buff *skb)
 398 {
 399         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 400
 401         ASSERTCMP(skb->mark, ==, RXRPC_SKB_MARK_DATA);
 402
 403         return sp->hdr.flags & RXRPC_LAST_PACKET;
 404 }
 405
 406 EXPORT_SYMBOL(rxrpc_kernel_is_data_last);
 407
 408 /**
 409  * rxrpc_kernel_get_abort_code - Get the abort code from an RxRPC abort message
 410  * @skb: Message indicating an abort
 411  *
 412  * Get the abort code from an RxRPC abort message.
 413  */
 414 u32 rxrpc_kernel_get_abort_code(struct sk_buff *skb)
 415 {
 416         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 417
 418         ASSERTCMP(skb->mark, ==, RXRPC_SKB_MARK_REMOTE_ABORT);
 419
 420         return sp->call->abort_code;
 421 }
 422
 423 EXPORT_SYMBOL(rxrpc_kernel_get_abort_code);
 424
 425 /**
 426  * rxrpc_kernel_get_error - Get the error number from an RxRPC error message
 427  * @skb: Message indicating an error
 428  *
 429  * Get the error number from an RxRPC error message.
 430  */
 431 int rxrpc_kernel_get_error_number(struct sk_buff *skb)
 432 {
 433         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 434
 435         return sp->error;
 436 }
 437
 438 EXPORT_SYMBOL(rxrpc_kernel_get_error_number);