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[deliverable/linux.git] / net / core / datagram.c
1 /*
2 * SUCS NET3:
3 *
4 * Generic datagram handling routines. These are generic for all
5 * protocols. Possibly a generic IP version on top of these would
6 * make sense. Not tonight however 8-).
7 * This is used because UDP, RAW, PACKET, DDP, IPX, AX.25 and
8 * NetROM layer all have identical poll code and mostly
9 * identical recvmsg() code. So we share it here. The poll was
10 * shared before but buried in udp.c so I moved it.
11 *
12 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>. (datagram_poll() from old
13 * udp.c code)
14 *
15 * Fixes:
16 * Alan Cox : NULL return from skb_peek_copy()
17 * understood
18 * Alan Cox : Rewrote skb_read_datagram to avoid the
19 * skb_peek_copy stuff.
20 * Alan Cox : Added support for SOCK_SEQPACKET.
21 * IPX can no longer use the SO_TYPE hack
22 * but AX.25 now works right, and SPX is
23 * feasible.
24 * Alan Cox : Fixed write poll of non IP protocol
25 * crash.
26 * Florian La Roche: Changed for my new skbuff handling.
27 * Darryl Miles : Fixed non-blocking SOCK_SEQPACKET.
28 * Linus Torvalds : BSD semantic fixes.
29 * Alan Cox : Datagram iovec handling
30 * Darryl Miles : Fixed non-blocking SOCK_STREAM.
31 * Alan Cox : POSIXisms
32 * Pete Wyckoff : Unconnected accept() fix.
33 *
34 */
35
36 #include <linux/module.h>
37 #include <linux/types.h>
38 #include <linux/kernel.h>
39 #include <asm/uaccess.h>
40 #include <asm/system.h>
41 #include <linux/mm.h>
42 #include <linux/interrupt.h>
43 #include <linux/errno.h>
44 #include <linux/sched.h>
45 #include <linux/inet.h>
46 #include <linux/netdevice.h>
47 #include <linux/rtnetlink.h>
48 #include <linux/poll.h>
49 #include <linux/highmem.h>
50 #include <linux/spinlock.h>
51
52 #include <net/protocol.h>
53 #include <linux/skbuff.h>
54
55 #include <net/checksum.h>
56 #include <net/sock.h>
57 #include <net/tcp_states.h>
58
59 /*
60 * Is a socket 'connection oriented' ?
61 */
62 static inline int connection_based(struct sock *sk)
63 {
64 return sk->sk_type == SOCK_SEQPACKET || sk->sk_type == SOCK_STREAM;
65 }
66
67 /*
68 * Wait for a packet..
69 */
70 static int wait_for_packet(struct sock *sk, int *err, long *timeo_p)
71 {
72 int error;
73 DEFINE_WAIT(wait);
74
75 prepare_to_wait_exclusive(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
76
77 /* Socket errors? */
78 error = sock_error(sk);
79 if (error)
80 goto out_err;
81
82 if (!skb_queue_empty(&sk->sk_receive_queue))
83 goto out;
84
85 /* Socket shut down? */
86 if (sk->sk_shutdown & RCV_SHUTDOWN)
87 goto out_noerr;
88
89 /* Sequenced packets can come disconnected.
90 * If so we report the problem
91 */
92 error = -ENOTCONN;
93 if (connection_based(sk) &&
94 !(sk->sk_state == TCP_ESTABLISHED || sk->sk_state == TCP_LISTEN))
95 goto out_err;
96
97 /* handle signals */
98 if (signal_pending(current))
99 goto interrupted;
100
101 error = 0;
102 *timeo_p = schedule_timeout(*timeo_p);
103 out:
104 finish_wait(sk->sk_sleep, &wait);
105 return error;
106 interrupted:
107 error = sock_intr_errno(*timeo_p);
108 out_err:
109 *err = error;
110 goto out;
111 out_noerr:
112 *err = 0;
113 error = 1;
114 goto out;
115 }
116
117 /**
118 * __skb_recv_datagram - Receive a datagram skbuff
119 * @sk: socket
120 * @flags: MSG_ flags
121 * @peeked: returns non-zero if this packet has been seen before
122 * @err: error code returned
123 *
124 * Get a datagram skbuff, understands the peeking, nonblocking wakeups
125 * and possible races. This replaces identical code in packet, raw and
126 * udp, as well as the IPX AX.25 and Appletalk. It also finally fixes
127 * the long standing peek and read race for datagram sockets. If you
128 * alter this routine remember it must be re-entrant.
129 *
130 * This function will lock the socket if a skb is returned, so the caller
131 * needs to unlock the socket in that case (usually by calling
132 * skb_free_datagram)
133 *
134 * * It does not lock socket since today. This function is
135 * * free of race conditions. This measure should/can improve
136 * * significantly datagram socket latencies at high loads,
137 * * when data copying to user space takes lots of time.
138 * * (BTW I've just killed the last cli() in IP/IPv6/core/netlink/packet
139 * * 8) Great win.)
140 * * --ANK (980729)
141 *
142 * The order of the tests when we find no data waiting are specified
143 * quite explicitly by POSIX 1003.1g, don't change them without having
144 * the standard around please.
145 */
146 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
147 int *peeked, int *err)
148 {
149 struct sk_buff *skb;
150 long timeo;
151 /*
152 * Caller is allowed not to check sk->sk_err before skb_recv_datagram()
153 */
154 int error = sock_error(sk);
155
156 if (error)
157 goto no_packet;
158
159 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
160
161 do {
162 /* Again only user level code calls this function, so nothing
163 * interrupt level will suddenly eat the receive_queue.
164 *
165 * Look at current nfs client by the way...
166 * However, this function was corrent in any case. 8)
167 */
168 unsigned long cpu_flags;
169
170 spin_lock_irqsave(&sk->sk_receive_queue.lock, cpu_flags);
171 skb = skb_peek(&sk->sk_receive_queue);
172 if (skb) {
173 *peeked = skb->peeked;
174 if (flags & MSG_PEEK) {
175 skb->peeked = 1;
176 atomic_inc(&skb->users);
177 } else
178 __skb_unlink(skb, &sk->sk_receive_queue);
179 }
180 spin_unlock_irqrestore(&sk->sk_receive_queue.lock, cpu_flags);
181
182 if (skb)
183 return skb;
184
185 /* User doesn't want to wait */
186 error = -EAGAIN;
187 if (!timeo)
188 goto no_packet;
189
190 } while (!wait_for_packet(sk, err, &timeo));
191
192 return NULL;
193
194 no_packet:
195 *err = error;
196 return NULL;
197 }
198 EXPORT_SYMBOL(__skb_recv_datagram);
199
200 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
201 int noblock, int *err)
202 {
203 int peeked;
204
205 return __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
206 &peeked, err);
207 }
208
209 void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
210 {
211 consume_skb(skb);
212 sk_mem_reclaim_partial(sk);
213 }
214
215 /**
216 * skb_kill_datagram - Free a datagram skbuff forcibly
217 * @sk: socket
218 * @skb: datagram skbuff
219 * @flags: MSG_ flags
220 *
221 * This function frees a datagram skbuff that was received by
222 * skb_recv_datagram. The flags argument must match the one
223 * used for skb_recv_datagram.
224 *
225 * If the MSG_PEEK flag is set, and the packet is still on the
226 * receive queue of the socket, it will be taken off the queue
227 * before it is freed.
228 *
229 * This function currently only disables BH when acquiring the
230 * sk_receive_queue lock. Therefore it must not be used in a
231 * context where that lock is acquired in an IRQ context.
232 *
233 * It returns 0 if the packet was removed by us.
234 */
235
236 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags)
237 {
238 int err = 0;
239
240 if (flags & MSG_PEEK) {
241 err = -ENOENT;
242 spin_lock_bh(&sk->sk_receive_queue.lock);
243 if (skb == skb_peek(&sk->sk_receive_queue)) {
244 __skb_unlink(skb, &sk->sk_receive_queue);
245 atomic_dec(&skb->users);
246 err = 0;
247 }
248 spin_unlock_bh(&sk->sk_receive_queue.lock);
249 }
250
251 skb_free_datagram(sk, skb);
252 return err;
253 }
254
255 EXPORT_SYMBOL(skb_kill_datagram);
256
257 /**
258 * skb_copy_datagram_iovec - Copy a datagram to an iovec.
259 * @skb: buffer to copy
260 * @offset: offset in the buffer to start copying from
261 * @to: io vector to copy to
262 * @len: amount of data to copy from buffer to iovec
263 *
264 * Note: the iovec is modified during the copy.
265 */
266 int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset,
267 struct iovec *to, int len)
268 {
269 int start = skb_headlen(skb);
270 int i, copy = start - offset;
271
272 /* Copy header. */
273 if (copy > 0) {
274 if (copy > len)
275 copy = len;
276 if (memcpy_toiovec(to, skb->data + offset, copy))
277 goto fault;
278 if ((len -= copy) == 0)
279 return 0;
280 offset += copy;
281 }
282
283 /* Copy paged appendix. Hmm... why does this look so complicated? */
284 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
285 int end;
286
287 WARN_ON(start > offset + len);
288
289 end = start + skb_shinfo(skb)->frags[i].size;
290 if ((copy = end - offset) > 0) {
291 int err;
292 u8 *vaddr;
293 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
294 struct page *page = frag->page;
295
296 if (copy > len)
297 copy = len;
298 vaddr = kmap(page);
299 err = memcpy_toiovec(to, vaddr + frag->page_offset +
300 offset - start, copy);
301 kunmap(page);
302 if (err)
303 goto fault;
304 if (!(len -= copy))
305 return 0;
306 offset += copy;
307 }
308 start = end;
309 }
310
311 if (skb_shinfo(skb)->frag_list) {
312 struct sk_buff *list = skb_shinfo(skb)->frag_list;
313
314 for (; list; list = list->next) {
315 int end;
316
317 WARN_ON(start > offset + len);
318
319 end = start + list->len;
320 if ((copy = end - offset) > 0) {
321 if (copy > len)
322 copy = len;
323 if (skb_copy_datagram_iovec(list,
324 offset - start,
325 to, copy))
326 goto fault;
327 if ((len -= copy) == 0)
328 return 0;
329 offset += copy;
330 }
331 start = end;
332 }
333 }
334 if (!len)
335 return 0;
336
337 fault:
338 return -EFAULT;
339 }
340
341 /**
342 * skb_copy_datagram_from_iovec - Copy a datagram from an iovec.
343 * @skb: buffer to copy
344 * @offset: offset in the buffer to start copying to
345 * @from: io vector to copy to
346 * @len: amount of data to copy to buffer from iovec
347 *
348 * Returns 0 or -EFAULT.
349 * Note: the iovec is modified during the copy.
350 */
351 int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
352 struct iovec *from, int len)
353 {
354 int start = skb_headlen(skb);
355 int i, copy = start - offset;
356
357 /* Copy header. */
358 if (copy > 0) {
359 if (copy > len)
360 copy = len;
361 if (memcpy_fromiovec(skb->data + offset, from, copy))
362 goto fault;
363 if ((len -= copy) == 0)
364 return 0;
365 offset += copy;
366 }
367
368 /* Copy paged appendix. Hmm... why does this look so complicated? */
369 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
370 int end;
371
372 WARN_ON(start > offset + len);
373
374 end = start + skb_shinfo(skb)->frags[i].size;
375 if ((copy = end - offset) > 0) {
376 int err;
377 u8 *vaddr;
378 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
379 struct page *page = frag->page;
380
381 if (copy > len)
382 copy = len;
383 vaddr = kmap(page);
384 err = memcpy_fromiovec(vaddr + frag->page_offset +
385 offset - start, from, copy);
386 kunmap(page);
387 if (err)
388 goto fault;
389
390 if (!(len -= copy))
391 return 0;
392 offset += copy;
393 }
394 start = end;
395 }
396
397 if (skb_shinfo(skb)->frag_list) {
398 struct sk_buff *list = skb_shinfo(skb)->frag_list;
399
400 for (; list; list = list->next) {
401 int end;
402
403 WARN_ON(start > offset + len);
404
405 end = start + list->len;
406 if ((copy = end - offset) > 0) {
407 if (copy > len)
408 copy = len;
409 if (skb_copy_datagram_from_iovec(list,
410 offset - start,
411 from, copy))
412 goto fault;
413 if ((len -= copy) == 0)
414 return 0;
415 offset += copy;
416 }
417 start = end;
418 }
419 }
420 if (!len)
421 return 0;
422
423 fault:
424 return -EFAULT;
425 }
426 EXPORT_SYMBOL(skb_copy_datagram_from_iovec);
427
428 static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
429 u8 __user *to, int len,
430 __wsum *csump)
431 {
432 int start = skb_headlen(skb);
433 int pos = 0;
434 int i, copy = start - offset;
435
436 /* Copy header. */
437 if (copy > 0) {
438 int err = 0;
439 if (copy > len)
440 copy = len;
441 *csump = csum_and_copy_to_user(skb->data + offset, to, copy,
442 *csump, &err);
443 if (err)
444 goto fault;
445 if ((len -= copy) == 0)
446 return 0;
447 offset += copy;
448 to += copy;
449 pos = copy;
450 }
451
452 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
453 int end;
454
455 WARN_ON(start > offset + len);
456
457 end = start + skb_shinfo(skb)->frags[i].size;
458 if ((copy = end - offset) > 0) {
459 __wsum csum2;
460 int err = 0;
461 u8 *vaddr;
462 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
463 struct page *page = frag->page;
464
465 if (copy > len)
466 copy = len;
467 vaddr = kmap(page);
468 csum2 = csum_and_copy_to_user(vaddr +
469 frag->page_offset +
470 offset - start,
471 to, copy, 0, &err);
472 kunmap(page);
473 if (err)
474 goto fault;
475 *csump = csum_block_add(*csump, csum2, pos);
476 if (!(len -= copy))
477 return 0;
478 offset += copy;
479 to += copy;
480 pos += copy;
481 }
482 start = end;
483 }
484
485 if (skb_shinfo(skb)->frag_list) {
486 struct sk_buff *list = skb_shinfo(skb)->frag_list;
487
488 for (; list; list=list->next) {
489 int end;
490
491 WARN_ON(start > offset + len);
492
493 end = start + list->len;
494 if ((copy = end - offset) > 0) {
495 __wsum csum2 = 0;
496 if (copy > len)
497 copy = len;
498 if (skb_copy_and_csum_datagram(list,
499 offset - start,
500 to, copy,
501 &csum2))
502 goto fault;
503 *csump = csum_block_add(*csump, csum2, pos);
504 if ((len -= copy) == 0)
505 return 0;
506 offset += copy;
507 to += copy;
508 pos += copy;
509 }
510 start = end;
511 }
512 }
513 if (!len)
514 return 0;
515
516 fault:
517 return -EFAULT;
518 }
519
520 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
521 {
522 __sum16 sum;
523
524 sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
525 if (likely(!sum)) {
526 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
527 netdev_rx_csum_fault(skb->dev);
528 skb->ip_summed = CHECKSUM_UNNECESSARY;
529 }
530 return sum;
531 }
532 EXPORT_SYMBOL(__skb_checksum_complete_head);
533
534 __sum16 __skb_checksum_complete(struct sk_buff *skb)
535 {
536 return __skb_checksum_complete_head(skb, skb->len);
537 }
538 EXPORT_SYMBOL(__skb_checksum_complete);
539
540 /**
541 * skb_copy_and_csum_datagram_iovec - Copy and checkum skb to user iovec.
542 * @skb: skbuff
543 * @hlen: hardware length
544 * @iov: io vector
545 *
546 * Caller _must_ check that skb will fit to this iovec.
547 *
548 * Returns: 0 - success.
549 * -EINVAL - checksum failure.
550 * -EFAULT - fault during copy. Beware, in this case iovec
551 * can be modified!
552 */
553 int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
554 int hlen, struct iovec *iov)
555 {
556 __wsum csum;
557 int chunk = skb->len - hlen;
558
559 if (!chunk)
560 return 0;
561
562 /* Skip filled elements.
563 * Pretty silly, look at memcpy_toiovec, though 8)
564 */
565 while (!iov->iov_len)
566 iov++;
567
568 if (iov->iov_len < chunk) {
569 if (__skb_checksum_complete(skb))
570 goto csum_error;
571 if (skb_copy_datagram_iovec(skb, hlen, iov, chunk))
572 goto fault;
573 } else {
574 csum = csum_partial(skb->data, hlen, skb->csum);
575 if (skb_copy_and_csum_datagram(skb, hlen, iov->iov_base,
576 chunk, &csum))
577 goto fault;
578 if (csum_fold(csum))
579 goto csum_error;
580 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
581 netdev_rx_csum_fault(skb->dev);
582 iov->iov_len -= chunk;
583 iov->iov_base += chunk;
584 }
585 return 0;
586 csum_error:
587 return -EINVAL;
588 fault:
589 return -EFAULT;
590 }
591
592 /**
593 * datagram_poll - generic datagram poll
594 * @file: file struct
595 * @sock: socket
596 * @wait: poll table
597 *
598 * Datagram poll: Again totally generic. This also handles
599 * sequenced packet sockets providing the socket receive queue
600 * is only ever holding data ready to receive.
601 *
602 * Note: when you _don't_ use this routine for this protocol,
603 * and you use a different write policy from sock_writeable()
604 * then please supply your own write_space callback.
605 */
606 unsigned int datagram_poll(struct file *file, struct socket *sock,
607 poll_table *wait)
608 {
609 struct sock *sk = sock->sk;
610 unsigned int mask;
611
612 poll_wait(file, sk->sk_sleep, wait);
613 mask = 0;
614
615 /* exceptional events? */
616 if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
617 mask |= POLLERR;
618 if (sk->sk_shutdown & RCV_SHUTDOWN)
619 mask |= POLLRDHUP;
620 if (sk->sk_shutdown == SHUTDOWN_MASK)
621 mask |= POLLHUP;
622
623 /* readable? */
624 if (!skb_queue_empty(&sk->sk_receive_queue) ||
625 (sk->sk_shutdown & RCV_SHUTDOWN))
626 mask |= POLLIN | POLLRDNORM;
627
628 /* Connection-based need to check for termination and startup */
629 if (connection_based(sk)) {
630 if (sk->sk_state == TCP_CLOSE)
631 mask |= POLLHUP;
632 /* connection hasn't started yet? */
633 if (sk->sk_state == TCP_SYN_SENT)
634 return mask;
635 }
636
637 /* writable? */
638 if (sock_writeable(sk))
639 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
640 else
641 set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
642
643 return mask;
644 }
645
646 EXPORT_SYMBOL(datagram_poll);
647 EXPORT_SYMBOL(skb_copy_and_csum_datagram_iovec);
648 EXPORT_SYMBOL(skb_copy_datagram_iovec);
649 EXPORT_SYMBOL(skb_free_datagram);
650 EXPORT_SYMBOL(skb_recv_datagram);
Linux kernel - Deliverables
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