[AF_RXRPC]: Add an interface to the AF_RXRPC module for the AFS filesystem to use
[linux-3.10.git] / 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, &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);