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.
12 * Authors: Alan Cox <alan@lxorguk.ukuu.org.uk>. (datagram_poll() from old
16 * Alan Cox : NULL return from skb_peek_copy()
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
24 * Alan Cox : Fixed write poll of non IP protocol
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.
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>
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 #include <linux/slab.h>
53 #include <net/protocol.h>
54 #include <linux/skbuff.h>
56 #include <net/checksum.h>
58 #include <net/tcp_states.h>
59 #include <trace/events/skb.h>
62 * Is a socket 'connection oriented' ?
64 static inline int connection_based(struct sock *sk)
66 return sk->sk_type == SOCK_SEQPACKET || sk->sk_type == SOCK_STREAM;
69 static int receiver_wake_function(wait_queue_t *wait, unsigned mode, int sync,
72 unsigned long bits = (unsigned long)key;
75 * Avoid a wakeup if event not interesting for us
77 if (bits && !(bits & (POLLIN | POLLERR)))
79 return autoremove_wake_function(wait, mode, sync, key);
84 static int wait_for_packet(struct sock *sk, int *err, long *timeo_p)
87 DEFINE_WAIT_FUNC(wait, receiver_wake_function);
89 prepare_to_wait_exclusive(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
92 error = sock_error(sk);
96 if (!skb_queue_empty(&sk->sk_receive_queue))
99 /* Socket shut down? */
100 if (sk->sk_shutdown & RCV_SHUTDOWN)
103 /* Sequenced packets can come disconnected.
104 * If so we report the problem
107 if (connection_based(sk) &&
108 !(sk->sk_state == TCP_ESTABLISHED || sk->sk_state == TCP_LISTEN))
112 if (signal_pending(current))
116 *timeo_p = schedule_timeout(*timeo_p);
118 finish_wait(sk_sleep(sk), &wait);
121 error = sock_intr_errno(*timeo_p);
132 * __skb_recv_datagram - Receive a datagram skbuff
135 * @peeked: returns non-zero if this packet has been seen before
136 * @err: error code returned
138 * Get a datagram skbuff, understands the peeking, nonblocking wakeups
139 * and possible races. This replaces identical code in packet, raw and
140 * udp, as well as the IPX AX.25 and Appletalk. It also finally fixes
141 * the long standing peek and read race for datagram sockets. If you
142 * alter this routine remember it must be re-entrant.
144 * This function will lock the socket if a skb is returned, so the caller
145 * needs to unlock the socket in that case (usually by calling
148 * * It does not lock socket since today. This function is
149 * * free of race conditions. This measure should/can improve
150 * * significantly datagram socket latencies at high loads,
151 * * when data copying to user space takes lots of time.
152 * * (BTW I've just killed the last cli() in IP/IPv6/core/netlink/packet
156 * The order of the tests when we find no data waiting are specified
157 * quite explicitly by POSIX 1003.1g, don't change them without having
158 * the standard around please.
160 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
161 int *peeked, int *err)
166 * Caller is allowed not to check sk->sk_err before skb_recv_datagram()
168 int error = sock_error(sk);
173 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
176 /* Again only user level code calls this function, so nothing
177 * interrupt level will suddenly eat the receive_queue.
179 * Look at current nfs client by the way...
180 * However, this function was correct in any case. 8)
182 unsigned long cpu_flags;
184 spin_lock_irqsave(&sk->sk_receive_queue.lock, cpu_flags);
185 skb = skb_peek(&sk->sk_receive_queue);
187 *peeked = skb->peeked;
188 if (flags & MSG_PEEK) {
190 atomic_inc(&skb->users);
192 __skb_unlink(skb, &sk->sk_receive_queue);
194 spin_unlock_irqrestore(&sk->sk_receive_queue.lock, cpu_flags);
199 /* User doesn't want to wait */
204 } while (!wait_for_packet(sk, err, &timeo));
212 EXPORT_SYMBOL(__skb_recv_datagram);
214 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
215 int noblock, int *err)
219 return __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
222 EXPORT_SYMBOL(skb_recv_datagram);
224 void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
227 sk_mem_reclaim_partial(sk);
229 EXPORT_SYMBOL(skb_free_datagram);
231 void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb)
235 if (likely(atomic_read(&skb->users) == 1))
237 else if (likely(!atomic_dec_and_test(&skb->users)))
240 slow = lock_sock_fast(sk);
242 sk_mem_reclaim_partial(sk);
243 unlock_sock_fast(sk, slow);
245 /* skb is now orphaned, can be freed outside of locked section */
246 trace_kfree_skb(skb, skb_free_datagram_locked);
249 EXPORT_SYMBOL(skb_free_datagram_locked);
252 * skb_kill_datagram - Free a datagram skbuff forcibly
254 * @skb: datagram skbuff
257 * This function frees a datagram skbuff that was received by
258 * skb_recv_datagram. The flags argument must match the one
259 * used for skb_recv_datagram.
261 * If the MSG_PEEK flag is set, and the packet is still on the
262 * receive queue of the socket, it will be taken off the queue
263 * before it is freed.
265 * This function currently only disables BH when acquiring the
266 * sk_receive_queue lock. Therefore it must not be used in a
267 * context where that lock is acquired in an IRQ context.
269 * It returns 0 if the packet was removed by us.
272 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags)
276 if (flags & MSG_PEEK) {
278 spin_lock_bh(&sk->sk_receive_queue.lock);
279 if (skb == skb_peek(&sk->sk_receive_queue)) {
280 __skb_unlink(skb, &sk->sk_receive_queue);
281 atomic_dec(&skb->users);
284 spin_unlock_bh(&sk->sk_receive_queue.lock);
288 atomic_inc(&sk->sk_drops);
289 sk_mem_reclaim_partial(sk);
293 EXPORT_SYMBOL(skb_kill_datagram);
296 * skb_copy_datagram_iovec - Copy a datagram to an iovec.
297 * @skb: buffer to copy
298 * @offset: offset in the buffer to start copying from
299 * @to: io vector to copy to
300 * @len: amount of data to copy from buffer to iovec
302 * Note: the iovec is modified during the copy.
304 int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset,
305 struct iovec *to, int len)
307 int start = skb_headlen(skb);
308 int i, copy = start - offset;
309 struct sk_buff *frag_iter;
311 trace_skb_copy_datagram_iovec(skb, len);
317 if (memcpy_toiovec(to, skb->data + offset, copy))
319 if ((len -= copy) == 0)
324 /* Copy paged appendix. Hmm... why does this look so complicated? */
325 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
328 WARN_ON(start > offset + len);
330 end = start + skb_shinfo(skb)->frags[i].size;
331 if ((copy = end - offset) > 0) {
334 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
335 struct page *page = frag->page;
340 err = memcpy_toiovec(to, vaddr + frag->page_offset +
341 offset - start, copy);
352 skb_walk_frags(skb, frag_iter) {
355 WARN_ON(start > offset + len);
357 end = start + frag_iter->len;
358 if ((copy = end - offset) > 0) {
361 if (skb_copy_datagram_iovec(frag_iter,
365 if ((len -= copy) == 0)
377 EXPORT_SYMBOL(skb_copy_datagram_iovec);
380 * skb_copy_datagram_const_iovec - Copy a datagram to an iovec.
381 * @skb: buffer to copy
382 * @offset: offset in the buffer to start copying from
383 * @to: io vector to copy to
384 * @to_offset: offset in the io vector to start copying to
385 * @len: amount of data to copy from buffer to iovec
387 * Returns 0 or -EFAULT.
388 * Note: the iovec is not modified during the copy.
390 int skb_copy_datagram_const_iovec(const struct sk_buff *skb, int offset,
391 const struct iovec *to, int to_offset,
394 int start = skb_headlen(skb);
395 int i, copy = start - offset;
396 struct sk_buff *frag_iter;
402 if (memcpy_toiovecend(to, skb->data + offset, to_offset, copy))
404 if ((len -= copy) == 0)
410 /* Copy paged appendix. Hmm... why does this look so complicated? */
411 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
414 WARN_ON(start > offset + len);
416 end = start + skb_shinfo(skb)->frags[i].size;
417 if ((copy = end - offset) > 0) {
420 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
421 struct page *page = frag->page;
426 err = memcpy_toiovecend(to, vaddr + frag->page_offset +
427 offset - start, to_offset, copy);
439 skb_walk_frags(skb, frag_iter) {
442 WARN_ON(start > offset + len);
444 end = start + frag_iter->len;
445 if ((copy = end - offset) > 0) {
448 if (skb_copy_datagram_const_iovec(frag_iter,
453 if ((len -= copy) == 0)
466 EXPORT_SYMBOL(skb_copy_datagram_const_iovec);
469 * skb_copy_datagram_from_iovec - Copy a datagram from an iovec.
470 * @skb: buffer to copy
471 * @offset: offset in the buffer to start copying to
472 * @from: io vector to copy to
473 * @from_offset: offset in the io vector to start copying from
474 * @len: amount of data to copy to buffer from iovec
476 * Returns 0 or -EFAULT.
477 * Note: the iovec is not modified during the copy.
479 int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
480 const struct iovec *from, int from_offset,
483 int start = skb_headlen(skb);
484 int i, copy = start - offset;
485 struct sk_buff *frag_iter;
491 if (memcpy_fromiovecend(skb->data + offset, from, from_offset,
494 if ((len -= copy) == 0)
500 /* Copy paged appendix. Hmm... why does this look so complicated? */
501 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
504 WARN_ON(start > offset + len);
506 end = start + skb_shinfo(skb)->frags[i].size;
507 if ((copy = end - offset) > 0) {
510 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
511 struct page *page = frag->page;
516 err = memcpy_fromiovecend(vaddr + frag->page_offset +
518 from, from_offset, copy);
531 skb_walk_frags(skb, frag_iter) {
534 WARN_ON(start > offset + len);
536 end = start + frag_iter->len;
537 if ((copy = end - offset) > 0) {
540 if (skb_copy_datagram_from_iovec(frag_iter,
546 if ((len -= copy) == 0)
559 EXPORT_SYMBOL(skb_copy_datagram_from_iovec);
561 static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
562 u8 __user *to, int len,
565 int start = skb_headlen(skb);
566 int i, copy = start - offset;
567 struct sk_buff *frag_iter;
575 *csump = csum_and_copy_to_user(skb->data + offset, to, copy,
579 if ((len -= copy) == 0)
586 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
589 WARN_ON(start > offset + len);
591 end = start + skb_shinfo(skb)->frags[i].size;
592 if ((copy = end - offset) > 0) {
596 skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
597 struct page *page = frag->page;
602 csum2 = csum_and_copy_to_user(vaddr +
609 *csump = csum_block_add(*csump, csum2, pos);
619 skb_walk_frags(skb, frag_iter) {
622 WARN_ON(start > offset + len);
624 end = start + frag_iter->len;
625 if ((copy = end - offset) > 0) {
629 if (skb_copy_and_csum_datagram(frag_iter,
634 *csump = csum_block_add(*csump, csum2, pos);
635 if ((len -= copy) == 0)
650 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
654 sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
656 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
657 netdev_rx_csum_fault(skb->dev);
658 skb->ip_summed = CHECKSUM_UNNECESSARY;
662 EXPORT_SYMBOL(__skb_checksum_complete_head);
664 __sum16 __skb_checksum_complete(struct sk_buff *skb)
666 return __skb_checksum_complete_head(skb, skb->len);
668 EXPORT_SYMBOL(__skb_checksum_complete);
671 * skb_copy_and_csum_datagram_iovec - Copy and checkum skb to user iovec.
673 * @hlen: hardware length
676 * Caller _must_ check that skb will fit to this iovec.
678 * Returns: 0 - success.
679 * -EINVAL - checksum failure.
680 * -EFAULT - fault during copy. Beware, in this case iovec
683 int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
684 int hlen, struct iovec *iov)
687 int chunk = skb->len - hlen;
692 /* Skip filled elements.
693 * Pretty silly, look at memcpy_toiovec, though 8)
695 while (!iov->iov_len)
698 if (iov->iov_len < chunk) {
699 if (__skb_checksum_complete(skb))
701 if (skb_copy_datagram_iovec(skb, hlen, iov, chunk))
704 csum = csum_partial(skb->data, hlen, skb->csum);
705 if (skb_copy_and_csum_datagram(skb, hlen, iov->iov_base,
710 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
711 netdev_rx_csum_fault(skb->dev);
712 iov->iov_len -= chunk;
713 iov->iov_base += chunk;
721 EXPORT_SYMBOL(skb_copy_and_csum_datagram_iovec);
724 * datagram_poll - generic datagram poll
729 * Datagram poll: Again totally generic. This also handles
730 * sequenced packet sockets providing the socket receive queue
731 * is only ever holding data ready to receive.
733 * Note: when you _don't_ use this routine for this protocol,
734 * and you use a different write policy from sock_writeable()
735 * then please supply your own write_space callback.
737 unsigned int datagram_poll(struct file *file, struct socket *sock,
740 struct sock *sk = sock->sk;
743 sock_poll_wait(file, sk_sleep(sk), wait);
746 /* exceptional events? */
747 if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
749 if (sk->sk_shutdown & RCV_SHUTDOWN)
750 mask |= POLLRDHUP | POLLIN | POLLRDNORM;
751 if (sk->sk_shutdown == SHUTDOWN_MASK)
755 if (!skb_queue_empty(&sk->sk_receive_queue))
756 mask |= POLLIN | POLLRDNORM;
758 /* Connection-based need to check for termination and startup */
759 if (connection_based(sk)) {
760 if (sk->sk_state == TCP_CLOSE)
762 /* connection hasn't started yet? */
763 if (sk->sk_state == TCP_SYN_SENT)
768 if (sock_writeable(sk))
769 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
771 set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
775 EXPORT_SYMBOL(datagram_poll);