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 <linux/uaccess.h>
41 #include <linux/interrupt.h>
42 #include <linux/errno.h>
43 #include <linux/sched.h>
44 #include <linux/inet.h>
45 #include <linux/netdevice.h>
46 #include <linux/rtnetlink.h>
47 #include <linux/poll.h>
48 #include <linux/highmem.h>
49 #include <linux/spinlock.h>
50 #include <linux/slab.h>
51 #include <linux/pagemap.h>
52 #include <linux/uio.h>
54 #include <net/protocol.h>
55 #include <linux/skbuff.h>
57 #include <net/checksum.h>
59 #include <net/tcp_states.h>
60 #include <trace/events/skb.h>
61 #include <net/busy_poll.h>
64 * Is a socket 'connection oriented' ?
66 static inline int connection_based(struct sock *sk)
68 return sk->sk_type == SOCK_SEQPACKET || sk->sk_type == SOCK_STREAM;
71 static int receiver_wake_function(wait_queue_t *wait, unsigned int mode, int sync,
74 unsigned long bits = (unsigned long)key;
77 * Avoid a wakeup if event not interesting for us
79 if (bits && !(bits & (POLLIN | POLLERR)))
81 return autoremove_wake_function(wait, mode, sync, key);
84 * Wait for the last received packet to be different from skb
86 int __skb_wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
87 const struct sk_buff *skb)
90 DEFINE_WAIT_FUNC(wait, receiver_wake_function);
92 prepare_to_wait_exclusive(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
95 error = sock_error(sk);
99 if (sk->sk_receive_queue.prev != skb)
102 /* Socket shut down? */
103 if (sk->sk_shutdown & RCV_SHUTDOWN)
106 /* Sequenced packets can come disconnected.
107 * If so we report the problem
110 if (connection_based(sk) &&
111 !(sk->sk_state == TCP_ESTABLISHED || sk->sk_state == TCP_LISTEN))
115 if (signal_pending(current))
119 *timeo_p = schedule_timeout(*timeo_p);
121 finish_wait(sk_sleep(sk), &wait);
124 error = sock_intr_errno(*timeo_p);
133 EXPORT_SYMBOL(__skb_wait_for_more_packets);
135 static struct sk_buff *skb_set_peeked(struct sk_buff *skb)
137 struct sk_buff *nskb;
142 /* We have to unshare an skb before modifying it. */
143 if (!skb_shared(skb))
146 nskb = skb_clone(skb, GFP_ATOMIC);
148 return ERR_PTR(-ENOMEM);
150 skb->prev->next = nskb;
151 skb->next->prev = nskb;
152 nskb->prev = skb->prev;
153 nskb->next = skb->next;
165 * __skb_try_recv_datagram - Receive a datagram skbuff
168 * @destructor: invoked under the receive lock on successful dequeue
169 * @peeked: returns non-zero if this packet has been seen before
170 * @off: an offset in bytes to peek skb from. Returns an offset
171 * within an skb where data actually starts
172 * @err: error code returned
173 * @last: set to last peeked message to inform the wait function
174 * what to look for when peeking
176 * Get a datagram skbuff, understands the peeking, nonblocking wakeups
177 * and possible races. This replaces identical code in packet, raw and
178 * udp, as well as the IPX AX.25 and Appletalk. It also finally fixes
179 * the long standing peek and read race for datagram sockets. If you
180 * alter this routine remember it must be re-entrant.
182 * This function will lock the socket if a skb is returned, so
183 * the caller needs to unlock the socket in that case (usually by
184 * calling skb_free_datagram). Returns NULL with *err set to
185 * -EAGAIN if no data was available or to some other value if an
186 * error was detected.
188 * * It does not lock socket since today. This function is
189 * * free of race conditions. This measure should/can improve
190 * * significantly datagram socket latencies at high loads,
191 * * when data copying to user space takes lots of time.
192 * * (BTW I've just killed the last cli() in IP/IPv6/core/netlink/packet
196 * The order of the tests when we find no data waiting are specified
197 * quite explicitly by POSIX 1003.1g, don't change them without having
198 * the standard around please.
200 struct sk_buff *__skb_try_recv_datagram(struct sock *sk, unsigned int flags,
201 void (*destructor)(struct sock *sk,
202 struct sk_buff *skb),
203 int *peeked, int *off, int *err,
204 struct sk_buff **last)
206 struct sk_buff_head *queue = &sk->sk_receive_queue;
208 unsigned long cpu_flags;
210 * Caller is allowed not to check sk->sk_err before skb_recv_datagram()
212 int error = sock_error(sk);
219 /* Again only user level code calls this function, so nothing
220 * interrupt level will suddenly eat the receive_queue.
222 * Look at current nfs client by the way...
223 * However, this function was correct in any case. 8)
227 *last = (struct sk_buff *)queue;
228 spin_lock_irqsave(&queue->lock, cpu_flags);
229 skb_queue_walk(queue, skb) {
231 if (flags & MSG_PEEK) {
232 if (_off >= skb->len && (skb->len || _off ||
238 skb = skb_set_peeked(skb);
240 error = PTR_ERR(skb);
241 spin_unlock_irqrestore(&queue->lock,
247 atomic_inc(&skb->users);
249 __skb_unlink(skb, queue);
253 spin_unlock_irqrestore(&queue->lock, cpu_flags);
258 spin_unlock_irqrestore(&queue->lock, cpu_flags);
259 } while (sk_can_busy_loop(sk) &&
260 sk_busy_loop(sk, flags & MSG_DONTWAIT));
268 EXPORT_SYMBOL(__skb_try_recv_datagram);
270 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
271 void (*destructor)(struct sock *sk,
272 struct sk_buff *skb),
273 int *peeked, int *off, int *err)
275 struct sk_buff *skb, *last;
278 timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
281 skb = __skb_try_recv_datagram(sk, flags, destructor, peeked,
289 !__skb_wait_for_more_packets(sk, err, &timeo, last));
293 EXPORT_SYMBOL(__skb_recv_datagram);
295 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned int flags,
296 int noblock, int *err)
300 return __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
301 NULL, &peeked, &off, err);
303 EXPORT_SYMBOL(skb_recv_datagram);
305 void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
308 sk_mem_reclaim_partial(sk);
310 EXPORT_SYMBOL(skb_free_datagram);
312 void __skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb, int len)
316 if (likely(atomic_read(&skb->users) == 1))
318 else if (likely(!atomic_dec_and_test(&skb->users))) {
319 sk_peek_offset_bwd(sk, len);
323 slow = lock_sock_fast(sk);
324 sk_peek_offset_bwd(sk, len);
326 sk_mem_reclaim_partial(sk);
327 unlock_sock_fast(sk, slow);
329 /* skb is now orphaned, can be freed outside of locked section */
332 EXPORT_SYMBOL(__skb_free_datagram_locked);
334 int __sk_queue_drop_skb(struct sock *sk, struct sk_buff *skb,
336 void (*destructor)(struct sock *sk,
337 struct sk_buff *skb))
341 if (flags & MSG_PEEK) {
343 spin_lock_bh(&sk->sk_receive_queue.lock);
344 if (skb == skb_peek(&sk->sk_receive_queue)) {
345 __skb_unlink(skb, &sk->sk_receive_queue);
346 atomic_dec(&skb->users);
351 spin_unlock_bh(&sk->sk_receive_queue.lock);
354 atomic_inc(&sk->sk_drops);
357 EXPORT_SYMBOL(__sk_queue_drop_skb);
360 * skb_kill_datagram - Free a datagram skbuff forcibly
362 * @skb: datagram skbuff
365 * This function frees a datagram skbuff that was received by
366 * skb_recv_datagram. The flags argument must match the one
367 * used for skb_recv_datagram.
369 * If the MSG_PEEK flag is set, and the packet is still on the
370 * receive queue of the socket, it will be taken off the queue
371 * before it is freed.
373 * This function currently only disables BH when acquiring the
374 * sk_receive_queue lock. Therefore it must not be used in a
375 * context where that lock is acquired in an IRQ context.
377 * It returns 0 if the packet was removed by us.
380 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags)
382 int err = __sk_queue_drop_skb(sk, skb, flags, NULL);
385 sk_mem_reclaim_partial(sk);
388 EXPORT_SYMBOL(skb_kill_datagram);
391 * skb_copy_datagram_iter - Copy a datagram to an iovec iterator.
392 * @skb: buffer to copy
393 * @offset: offset in the buffer to start copying from
394 * @to: iovec iterator to copy to
395 * @len: amount of data to copy from buffer to iovec
397 int skb_copy_datagram_iter(const struct sk_buff *skb, int offset,
398 struct iov_iter *to, int len)
400 int start = skb_headlen(skb);
401 int i, copy = start - offset;
402 struct sk_buff *frag_iter;
404 trace_skb_copy_datagram_iovec(skb, len);
410 if (copy_to_iter(skb->data + offset, copy, to) != copy)
412 if ((len -= copy) == 0)
417 /* Copy paged appendix. Hmm... why does this look so complicated? */
418 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
420 const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
422 WARN_ON(start > offset + len);
424 end = start + skb_frag_size(frag);
425 if ((copy = end - offset) > 0) {
428 if (copy_page_to_iter(skb_frag_page(frag),
429 frag->page_offset + offset -
430 start, copy, to) != 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_iter(frag_iter, offset - start,
451 if ((len -= copy) == 0)
460 /* This is not really a user copy fault, but rather someone
461 * gave us a bogus length on the skb. We should probably
462 * print a warning here as it may indicate a kernel bug.
469 if (iov_iter_count(to))
474 EXPORT_SYMBOL(skb_copy_datagram_iter);
477 * skb_copy_datagram_from_iter - Copy a datagram from an iov_iter.
478 * @skb: buffer to copy
479 * @offset: offset in the buffer to start copying to
480 * @from: the copy source
481 * @len: amount of data to copy to buffer from iovec
483 * Returns 0 or -EFAULT.
485 int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
486 struct iov_iter *from,
489 int start = skb_headlen(skb);
490 int i, copy = start - offset;
491 struct sk_buff *frag_iter;
497 if (copy_from_iter(skb->data + offset, copy, from) != copy)
499 if ((len -= copy) == 0)
504 /* Copy paged appendix. Hmm... why does this look so complicated? */
505 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
507 const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
509 WARN_ON(start > offset + len);
511 end = start + skb_frag_size(frag);
512 if ((copy = end - offset) > 0) {
517 copied = copy_page_from_iter(skb_frag_page(frag),
518 frag->page_offset + offset - start,
530 skb_walk_frags(skb, frag_iter) {
533 WARN_ON(start > offset + len);
535 end = start + frag_iter->len;
536 if ((copy = end - offset) > 0) {
539 if (skb_copy_datagram_from_iter(frag_iter,
543 if ((len -= copy) == 0)
555 EXPORT_SYMBOL(skb_copy_datagram_from_iter);
558 * zerocopy_sg_from_iter - Build a zerocopy datagram from an iov_iter
559 * @skb: buffer to copy
560 * @from: the source to copy from
562 * The function will first copy up to headlen, and then pin the userspace
563 * pages and build frags through them.
565 * Returns 0, -EFAULT or -EMSGSIZE.
567 int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
569 int len = iov_iter_count(from);
570 int copy = min_t(int, skb_headlen(skb), len);
573 /* copy up to skb headlen */
574 if (skb_copy_datagram_from_iter(skb, 0, from, copy))
577 while (iov_iter_count(from)) {
578 struct page *pages[MAX_SKB_FRAGS];
581 unsigned long truesize;
584 if (frag == MAX_SKB_FRAGS)
587 copied = iov_iter_get_pages(from, pages, ~0U,
588 MAX_SKB_FRAGS - frag, &start);
592 iov_iter_advance(from, copied);
594 truesize = PAGE_ALIGN(copied + start);
595 skb->data_len += copied;
597 skb->truesize += truesize;
598 atomic_add(truesize, &skb->sk->sk_wmem_alloc);
600 int size = min_t(int, copied, PAGE_SIZE - start);
601 skb_fill_page_desc(skb, frag++, pages[n], start, size);
609 EXPORT_SYMBOL(zerocopy_sg_from_iter);
611 static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
612 struct iov_iter *to, int len,
615 int start = skb_headlen(skb);
616 int i, copy = start - offset;
617 struct sk_buff *frag_iter;
625 n = csum_and_copy_to_iter(skb->data + offset, copy, csump, to);
628 if ((len -= copy) == 0)
634 for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
636 const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
638 WARN_ON(start > offset + len);
640 end = start + skb_frag_size(frag);
641 if ((copy = end - offset) > 0) {
643 struct page *page = skb_frag_page(frag);
644 u8 *vaddr = kmap(page);
648 n = csum_and_copy_to_iter(vaddr + frag->page_offset +
649 offset - start, copy,
654 *csump = csum_block_add(*csump, csum2, pos);
663 skb_walk_frags(skb, frag_iter) {
666 WARN_ON(start > offset + len);
668 end = start + frag_iter->len;
669 if ((copy = end - offset) > 0) {
673 if (skb_copy_and_csum_datagram(frag_iter,
678 *csump = csum_block_add(*csump, csum2, pos);
679 if ((len -= copy) == 0)
693 __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
697 sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
699 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
700 !skb->csum_complete_sw)
701 netdev_rx_csum_fault(skb->dev);
703 if (!skb_shared(skb))
704 skb->csum_valid = !sum;
707 EXPORT_SYMBOL(__skb_checksum_complete_head);
709 __sum16 __skb_checksum_complete(struct sk_buff *skb)
714 csum = skb_checksum(skb, 0, skb->len, 0);
716 /* skb->csum holds pseudo checksum */
717 sum = csum_fold(csum_add(skb->csum, csum));
719 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
720 !skb->csum_complete_sw)
721 netdev_rx_csum_fault(skb->dev);
724 if (!skb_shared(skb)) {
725 /* Save full packet checksum */
727 skb->ip_summed = CHECKSUM_COMPLETE;
728 skb->csum_complete_sw = 1;
729 skb->csum_valid = !sum;
734 EXPORT_SYMBOL(__skb_checksum_complete);
737 * skb_copy_and_csum_datagram_msg - Copy and checksum skb to user iovec.
739 * @hlen: hardware length
742 * Caller _must_ check that skb will fit to this iovec.
744 * Returns: 0 - success.
745 * -EINVAL - checksum failure.
746 * -EFAULT - fault during copy.
748 int skb_copy_and_csum_datagram_msg(struct sk_buff *skb,
749 int hlen, struct msghdr *msg)
752 int chunk = skb->len - hlen;
757 if (msg_data_left(msg) < chunk) {
758 if (__skb_checksum_complete(skb))
760 if (skb_copy_datagram_msg(skb, hlen, msg, chunk))
763 csum = csum_partial(skb->data, hlen, skb->csum);
764 if (skb_copy_and_csum_datagram(skb, hlen, &msg->msg_iter,
769 if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
770 netdev_rx_csum_fault(skb->dev);
778 EXPORT_SYMBOL(skb_copy_and_csum_datagram_msg);
781 * datagram_poll - generic datagram poll
786 * Datagram poll: Again totally generic. This also handles
787 * sequenced packet sockets providing the socket receive queue
788 * is only ever holding data ready to receive.
790 * Note: when you _don't_ use this routine for this protocol,
791 * and you use a different write policy from sock_writeable()
792 * then please supply your own write_space callback.
794 unsigned int datagram_poll(struct file *file, struct socket *sock,
797 struct sock *sk = sock->sk;
800 sock_poll_wait(file, sk_sleep(sk), wait);
803 /* exceptional events? */
804 if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
806 (sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? POLLPRI : 0);
808 if (sk->sk_shutdown & RCV_SHUTDOWN)
809 mask |= POLLRDHUP | POLLIN | POLLRDNORM;
810 if (sk->sk_shutdown == SHUTDOWN_MASK)
814 if (!skb_queue_empty(&sk->sk_receive_queue))
815 mask |= POLLIN | POLLRDNORM;
817 /* Connection-based need to check for termination and startup */
818 if (connection_based(sk)) {
819 if (sk->sk_state == TCP_CLOSE)
821 /* connection hasn't started yet? */
822 if (sk->sk_state == TCP_SYN_SENT)
827 if (sock_writeable(sk))
828 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
830 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
834 EXPORT_SYMBOL(datagram_poll);