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   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, &call->conn->trans->peer->srx,
 147                                        sizeof(call->conn->trans->peer->srx));
 148                         sock_recv_timestamp(msg, &rx->sk, skb);
 149                 }
 150
 151                 /* receive the message */
 152                 if (skb->mark != RXRPC_SKB_MARK_DATA)
 153                         goto receive_non_data_message;
 154
 155                 _debug("recvmsg DATA #%u { %d, %d }",
 156                        ntohl(sp->hdr.seq), skb->len, sp->offset);
 157
 158                 if (!continue_call) {
 159                         /* only set the control data once per recvmsg() */
 160                         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 161                                        ullen, &call->user_call_ID);
 162                         if (ret < 0)
 163                                 goto copy_error;
 164                         ASSERT(test_bit(RXRPC_CALL_HAS_USERID, &call->flags));
 165                 }
 166
 167                 ASSERTCMP(ntohl(sp->hdr.seq), >=, call->rx_data_recv);
 168                 ASSERTCMP(ntohl(sp->hdr.seq), <=, call->rx_data_recv + 1);
 169                 call->rx_data_recv = ntohl(sp->hdr.seq);
 170
 171                 ASSERTCMP(ntohl(sp->hdr.seq), >, call->rx_data_eaten);
 172
 173                 offset = sp->offset;
 174                 copy = skb->len - offset;
 175                 if (copy > len - copied)
 176                         copy = len - copied;
 177
 178                 if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
 179                         ret = skb_copy_datagram_iovec(skb, offset,
 180                                                       msg->msg_iov, copy);
 181                 } else {
 182                         ret = skb_copy_and_csum_datagram_iovec(skb, offset,
 183                                                                msg->msg_iov);
 184                         if (ret == -EINVAL)
 185                                 goto csum_copy_error;
 186                 }
 187
 188                 if (ret < 0)
 189                         goto copy_error;
 190
 191                 /* handle piecemeal consumption of data packets */
 192                 _debug("copied %d+%d", copy, copied);
 193
 194                 offset += copy;
 195                 copied += copy;
 196
 197                 if (!(flags & MSG_PEEK))
 198                         sp->offset = offset;
 199
 200                 if (sp->offset < skb->len) {
 201                         _debug("buffer full");
 202                         ASSERTCMP(copied, ==, len);
 203                         break;
 204                 }
 205
 206                 /* we transferred the whole data packet */
 207                 if (sp->hdr.flags & RXRPC_LAST_PACKET) {
 208                         _debug("last");
 209                         if (call->conn->out_clientflag) {
 210                                  /* last byte of reply received */
 211                                 ret = copied;
 212                                 goto terminal_message;
 213                         }
 214
 215                         /* last bit of request received */
 216                         if (!(flags & MSG_PEEK)) {
 217                                 _debug("eat packet");
 218                                 if (skb_dequeue(&rx->sk.sk_receive_queue) !=
 219                                     skb)
 220                                         BUG();
 221                                 rxrpc_free_skb(skb);
 222                         }
 223                         msg->msg_flags &= ~MSG_MORE;
 224                         break;
 225                 }
 226
 227                 /* move on to the next data message */
 228                 _debug("next");
 229                 if (!continue_call)
 230                         continue_call = sp->call;
 231                 else
 232                         rxrpc_put_call(call);
 233                 call = NULL;
 234
 235                 if (flags & MSG_PEEK) {
 236                         _debug("peek next");
 237                         skb = skb->next;
 238                         if (skb == (struct sk_buff *) &rx->sk.sk_receive_queue)
 239                                 break;
 240                         goto peek_next_packet;
 241                 }
 242
 243                 _debug("eat packet");
 244                 if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 245                         BUG();
 246                 rxrpc_free_skb(skb);
 247         }
 248
 249         /* end of non-terminal data packet reception for the moment */
 250         _debug("end rcv data");
 251 out:
 252         release_sock(&rx->sk);
 253         if (call)
 254                 rxrpc_put_call(call);
 255         if (continue_call)
 256                 rxrpc_put_call(continue_call);
 257         _leave(" = %d [data]", copied);
 258         return copied;
 259
 260         /* handle non-DATA messages such as aborts, incoming connections and
 261          * final ACKs */
 262 receive_non_data_message:
 263         _debug("non-data");
 264
 265         if (skb->mark == RXRPC_SKB_MARK_NEW_CALL) {
 266                 _debug("RECV NEW CALL");
 267                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NEW_CALL, 0, &abort_code);
 268                 if (ret < 0)
 269                         goto copy_error;
 270                 if (!(flags & MSG_PEEK)) {
 271                         if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 272                                 BUG();
 273                         rxrpc_free_skb(skb);
 274                 }
 275                 goto out;
 276         }
 277
 278         ret = put_cmsg(msg, SOL_RXRPC, RXRPC_USER_CALL_ID,
 279                        ullen, &call->user_call_ID);
 280         if (ret < 0)
 281                 goto copy_error;
 282         ASSERT(test_bit(RXRPC_CALL_HAS_USERID, &call->flags));
 283
 284         switch (skb->mark) {
 285         case RXRPC_SKB_MARK_DATA:
 286                 BUG();
 287         case RXRPC_SKB_MARK_FINAL_ACK:
 288                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ACK, 0, &abort_code);
 289                 break;
 290         case RXRPC_SKB_MARK_BUSY:
 291                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_BUSY, 0, &abort_code);
 292                 break;
 293         case RXRPC_SKB_MARK_REMOTE_ABORT:
 294                 abort_code = call->abort_code;
 295                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_ABORT, 4, &abort_code);
 296                 break;
 297         case RXRPC_SKB_MARK_NET_ERROR:
 298                 _debug("RECV NET ERROR %d", sp->error);
 299                 abort_code = sp->error;
 300                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_NET_ERROR, 4, &abort_code);
 301                 break;
 302         case RXRPC_SKB_MARK_LOCAL_ERROR:
 303                 _debug("RECV LOCAL ERROR %d", sp->error);
 304                 abort_code = sp->error;
 305                 ret = put_cmsg(msg, SOL_RXRPC, RXRPC_LOCAL_ERROR, 4,
 306                                &abort_code);
 307                 break;
 308         default:
 309                 BUG();
 310                 break;
 311         }
 312
 313         if (ret < 0)
 314                 goto copy_error;
 315
 316 terminal_message:
 317         _debug("terminal");
 318         msg->msg_flags &= ~MSG_MORE;
 319         msg->msg_flags |= MSG_EOR;
 320
 321         if (!(flags & MSG_PEEK)) {
 322                 _net("free terminal skb %p", skb);
 323                 if (skb_dequeue(&rx->sk.sk_receive_queue) != skb)
 324                         BUG();
 325                 rxrpc_free_skb(skb);
 326                 rxrpc_remove_user_ID(rx, call);
 327         }
 328
 329         release_sock(&rx->sk);
 330         rxrpc_put_call(call);
 331         if (continue_call)
 332                 rxrpc_put_call(continue_call);
 333         _leave(" = %d", ret);
 334         return ret;
 335
 336 copy_error:
 337         _debug("copy error");
 338         release_sock(&rx->sk);
 339         rxrpc_put_call(call);
 340         if (continue_call)
 341                 rxrpc_put_call(continue_call);
 342         _leave(" = %d", ret);
 343         return ret;
 344
 345 csum_copy_error:
 346         _debug("csum error");
 347         release_sock(&rx->sk);
 348         if (continue_call)
 349                 rxrpc_put_call(continue_call);
 350         rxrpc_kill_skb(skb);
 351         skb_kill_datagram(&rx->sk, skb, flags);
 352         rxrpc_put_call(call);
 353         return -EAGAIN;
 354
 355 wait_interrupted:
 356         ret = sock_intr_errno(timeo);
 357 wait_error:
 358         finish_wait(rx->sk.sk_sleep, &wait);
 359         if (continue_call)
 360                 rxrpc_put_call(continue_call);
 361         if (copied)
 362                 copied = ret;
 363         _leave(" = %d [waitfail %d]", copied, ret);
 364         return copied;
 365
 366 }
 367
 368 /**
 369  * rxrpc_kernel_data_delivered - Record delivery of data message
 370  * @skb: Message holding data
 371  *
 372  * Record the delivery of a data message.  This permits RxRPC to keep its
 373  * tracking correct.  The socket buffer will be deleted.
 374  */
 375 void rxrpc_kernel_data_delivered(struct sk_buff *skb)
 376 {
 377         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 378         struct rxrpc_call *call = sp->call;
 379
 380         ASSERTCMP(ntohl(sp->hdr.seq), >=, call->rx_data_recv);
 381         ASSERTCMP(ntohl(sp->hdr.seq), <=, call->rx_data_recv + 1);
 382         call->rx_data_recv = ntohl(sp->hdr.seq);
 383
 384         ASSERTCMP(ntohl(sp->hdr.seq), >, call->rx_data_eaten);
 385         rxrpc_free_skb(skb);
 386 }
 387
 388 EXPORT_SYMBOL(rxrpc_kernel_data_delivered);
 389
 390 /**
 391  * rxrpc_kernel_is_data_last - Determine if data message is last one
 392  * @skb: Message holding data
 393  *
 394  * Determine if data message is last one for the parent call.
 395  */
 396 bool rxrpc_kernel_is_data_last(struct sk_buff *skb)
 397 {
 398         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 399
 400         ASSERTCMP(skb->mark, ==, RXRPC_SKB_MARK_DATA);
 401
 402         return sp->hdr.flags & RXRPC_LAST_PACKET;
 403 }
 404
 405 EXPORT_SYMBOL(rxrpc_kernel_is_data_last);
 406
 407 /**
 408  * rxrpc_kernel_get_abort_code - Get the abort code from an RxRPC abort message
 409  * @skb: Message indicating an abort
 410  *
 411  * Get the abort code from an RxRPC abort message.
 412  */
 413 u32 rxrpc_kernel_get_abort_code(struct sk_buff *skb)
 414 {
 415         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 416
 417         ASSERTCMP(skb->mark, ==, RXRPC_SKB_MARK_REMOTE_ABORT);
 418
 419         return sp->call->abort_code;
 420 }
 421
 422 EXPORT_SYMBOL(rxrpc_kernel_get_abort_code);
 423
 424 /**
 425  * rxrpc_kernel_get_error - Get the error number from an RxRPC error message
 426  * @skb: Message indicating an error
 427  *
 428  * Get the error number from an RxRPC error message.
 429  */
 430 int rxrpc_kernel_get_error_number(struct sk_buff *skb)
 431 {
 432         struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
 433
 434         return sp->error;
 435 }
 436
 437 EXPORT_SYMBOL(rxrpc_kernel_get_error_number);