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>
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>
52 #include <net/protocol.h>
53 #include <linux/skbuff.h>
55 #include <net/checksum.h>
57 #include <net/tcp_states.h>
58 #include <trace/events/skb.h>
59 #include <net/busy_poll.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 int 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
);
82 * Wait for the last received packet to be different from skb
84 static int wait_for_more_packets(struct sock
*sk
, int *err
, long *timeo_p
,
85 const struct sk_buff
*skb
)
88 DEFINE_WAIT_FUNC(wait
, receiver_wake_function
);
90 prepare_to_wait_exclusive(sk_sleep(sk
), &wait
, TASK_INTERRUPTIBLE
);
93 error
= sock_error(sk
);
97 if (sk
->sk_receive_queue
.prev
!= skb
)
100 /* Socket shut down? */
101 if (sk
->sk_shutdown
& RCV_SHUTDOWN
)
104 /* Sequenced packets can come disconnected.
105 * If so we report the problem
108 if (connection_based(sk
) &&
109 !(sk
->sk_state
== TCP_ESTABLISHED
|| sk
->sk_state
== TCP_LISTEN
))
113 if (signal_pending(current
))
117 *timeo_p
= schedule_timeout(*timeo_p
);
119 finish_wait(sk_sleep(sk
), &wait
);
122 error
= sock_intr_errno(*timeo_p
);
133 * __skb_recv_datagram - Receive a datagram skbuff
136 * @peeked: returns non-zero if this packet has been seen before
137 * @off: an offset in bytes to peek skb from. Returns an offset
138 * within an skb where data actually starts
139 * @err: error code returned
141 * Get a datagram skbuff, understands the peeking, nonblocking wakeups
142 * and possible races. This replaces identical code in packet, raw and
143 * udp, as well as the IPX AX.25 and Appletalk. It also finally fixes
144 * the long standing peek and read race for datagram sockets. If you
145 * alter this routine remember it must be re-entrant.
147 * This function will lock the socket if a skb is returned, so the caller
148 * needs to unlock the socket in that case (usually by calling
151 * * It does not lock socket since today. This function is
152 * * free of race conditions. This measure should/can improve
153 * * significantly datagram socket latencies at high loads,
154 * * when data copying to user space takes lots of time.
155 * * (BTW I've just killed the last cli() in IP/IPv6/core/netlink/packet
159 * The order of the tests when we find no data waiting are specified
160 * quite explicitly by POSIX 1003.1g, don't change them without having
161 * the standard around please.
163 struct sk_buff
*__skb_recv_datagram(struct sock
*sk
, unsigned int flags
,
164 int *peeked
, int *off
, int *err
)
166 struct sk_buff
*skb
, *last
;
169 * Caller is allowed not to check sk->sk_err before skb_recv_datagram()
171 int error
= sock_error(sk
);
176 timeo
= sock_rcvtimeo(sk
, flags
& MSG_DONTWAIT
);
179 /* Again only user level code calls this function, so nothing
180 * interrupt level will suddenly eat the receive_queue.
182 * Look at current nfs client by the way...
183 * However, this function was correct in any case. 8)
185 unsigned long cpu_flags
;
186 struct sk_buff_head
*queue
= &sk
->sk_receive_queue
;
189 last
= (struct sk_buff
*)queue
;
190 spin_lock_irqsave(&queue
->lock
, cpu_flags
);
191 skb_queue_walk(queue
, skb
) {
193 *peeked
= skb
->peeked
;
194 if (flags
& MSG_PEEK
) {
195 if (_off
>= skb
->len
&& (skb
->len
|| _off
||
201 atomic_inc(&skb
->users
);
203 __skb_unlink(skb
, queue
);
205 spin_unlock_irqrestore(&queue
->lock
, cpu_flags
);
209 spin_unlock_irqrestore(&queue
->lock
, cpu_flags
);
211 if (sk_can_busy_loop(sk
) &&
212 sk_busy_loop(sk
, flags
& MSG_DONTWAIT
))
215 /* User doesn't want to wait */
220 } while (!wait_for_more_packets(sk
, err
, &timeo
, last
));
228 EXPORT_SYMBOL(__skb_recv_datagram
);
230 struct sk_buff
*skb_recv_datagram(struct sock
*sk
, unsigned int flags
,
231 int noblock
, int *err
)
235 return __skb_recv_datagram(sk
, flags
| (noblock
? MSG_DONTWAIT
: 0),
238 EXPORT_SYMBOL(skb_recv_datagram
);
240 void skb_free_datagram(struct sock
*sk
, struct sk_buff
*skb
)
243 sk_mem_reclaim_partial(sk
);
245 EXPORT_SYMBOL(skb_free_datagram
);
247 void skb_free_datagram_locked(struct sock
*sk
, struct sk_buff
*skb
)
251 if (likely(atomic_read(&skb
->users
) == 1))
253 else if (likely(!atomic_dec_and_test(&skb
->users
)))
256 slow
= lock_sock_fast(sk
);
258 sk_mem_reclaim_partial(sk
);
259 unlock_sock_fast(sk
, slow
);
261 /* skb is now orphaned, can be freed outside of locked section */
264 EXPORT_SYMBOL(skb_free_datagram_locked
);
267 * skb_kill_datagram - Free a datagram skbuff forcibly
269 * @skb: datagram skbuff
272 * This function frees a datagram skbuff that was received by
273 * skb_recv_datagram. The flags argument must match the one
274 * used for skb_recv_datagram.
276 * If the MSG_PEEK flag is set, and the packet is still on the
277 * receive queue of the socket, it will be taken off the queue
278 * before it is freed.
280 * This function currently only disables BH when acquiring the
281 * sk_receive_queue lock. Therefore it must not be used in a
282 * context where that lock is acquired in an IRQ context.
284 * It returns 0 if the packet was removed by us.
287 int skb_kill_datagram(struct sock
*sk
, struct sk_buff
*skb
, unsigned int flags
)
291 if (flags
& MSG_PEEK
) {
293 spin_lock_bh(&sk
->sk_receive_queue
.lock
);
294 if (skb
== skb_peek(&sk
->sk_receive_queue
)) {
295 __skb_unlink(skb
, &sk
->sk_receive_queue
);
296 atomic_dec(&skb
->users
);
299 spin_unlock_bh(&sk
->sk_receive_queue
.lock
);
303 atomic_inc(&sk
->sk_drops
);
304 sk_mem_reclaim_partial(sk
);
308 EXPORT_SYMBOL(skb_kill_datagram
);
311 * skb_copy_datagram_iovec - Copy a datagram to an iovec.
312 * @skb: buffer to copy
313 * @offset: offset in the buffer to start copying from
314 * @to: io vector to copy to
315 * @len: amount of data to copy from buffer to iovec
317 * Note: the iovec is modified during the copy.
319 int skb_copy_datagram_iovec(const struct sk_buff
*skb
, int offset
,
320 struct iovec
*to
, int len
)
322 int start
= skb_headlen(skb
);
323 int i
, copy
= start
- offset
;
324 struct sk_buff
*frag_iter
;
326 trace_skb_copy_datagram_iovec(skb
, len
);
332 if (memcpy_toiovec(to
, skb
->data
+ offset
, copy
))
334 if ((len
-= copy
) == 0)
339 /* Copy paged appendix. Hmm... why does this look so complicated? */
340 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
342 const skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
344 WARN_ON(start
> offset
+ len
);
346 end
= start
+ skb_frag_size(frag
);
347 if ((copy
= end
- offset
) > 0) {
350 struct page
*page
= skb_frag_page(frag
);
355 err
= memcpy_toiovec(to
, vaddr
+ frag
->page_offset
+
356 offset
- start
, copy
);
367 skb_walk_frags(skb
, frag_iter
) {
370 WARN_ON(start
> offset
+ len
);
372 end
= start
+ frag_iter
->len
;
373 if ((copy
= end
- offset
) > 0) {
376 if (skb_copy_datagram_iovec(frag_iter
,
380 if ((len
-= copy
) == 0)
392 EXPORT_SYMBOL(skb_copy_datagram_iovec
);
395 * skb_copy_datagram_const_iovec - Copy a datagram to an iovec.
396 * @skb: buffer to copy
397 * @offset: offset in the buffer to start copying from
398 * @to: io vector to copy to
399 * @to_offset: offset in the io vector to start copying to
400 * @len: amount of data to copy from buffer to iovec
402 * Returns 0 or -EFAULT.
403 * Note: the iovec is not modified during the copy.
405 int skb_copy_datagram_const_iovec(const struct sk_buff
*skb
, int offset
,
406 const struct iovec
*to
, int to_offset
,
409 int start
= skb_headlen(skb
);
410 int i
, copy
= start
- offset
;
411 struct sk_buff
*frag_iter
;
417 if (memcpy_toiovecend(to
, skb
->data
+ offset
, to_offset
, copy
))
419 if ((len
-= copy
) == 0)
425 /* Copy paged appendix. Hmm... why does this look so complicated? */
426 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
428 const skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
430 WARN_ON(start
> offset
+ len
);
432 end
= start
+ skb_frag_size(frag
);
433 if ((copy
= end
- offset
) > 0) {
436 struct page
*page
= skb_frag_page(frag
);
441 err
= memcpy_toiovecend(to
, vaddr
+ frag
->page_offset
+
442 offset
- start
, to_offset
, copy
);
454 skb_walk_frags(skb
, frag_iter
) {
457 WARN_ON(start
> offset
+ len
);
459 end
= start
+ frag_iter
->len
;
460 if ((copy
= end
- offset
) > 0) {
463 if (skb_copy_datagram_const_iovec(frag_iter
,
468 if ((len
-= copy
) == 0)
481 EXPORT_SYMBOL(skb_copy_datagram_const_iovec
);
484 * skb_copy_datagram_from_iovec - Copy a datagram from an iovec.
485 * @skb: buffer to copy
486 * @offset: offset in the buffer to start copying to
487 * @from: io vector to copy to
488 * @from_offset: offset in the io vector to start copying from
489 * @len: amount of data to copy to buffer from iovec
491 * Returns 0 or -EFAULT.
492 * Note: the iovec is not modified during the copy.
494 int skb_copy_datagram_from_iovec(struct sk_buff
*skb
, int offset
,
495 const struct iovec
*from
, int from_offset
,
498 int start
= skb_headlen(skb
);
499 int i
, copy
= start
- offset
;
500 struct sk_buff
*frag_iter
;
506 if (memcpy_fromiovecend(skb
->data
+ offset
, from
, from_offset
,
509 if ((len
-= copy
) == 0)
515 /* Copy paged appendix. Hmm... why does this look so complicated? */
516 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
518 const skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
520 WARN_ON(start
> offset
+ len
);
522 end
= start
+ skb_frag_size(frag
);
523 if ((copy
= end
- offset
) > 0) {
526 struct page
*page
= skb_frag_page(frag
);
531 err
= memcpy_fromiovecend(vaddr
+ frag
->page_offset
+
533 from
, from_offset
, copy
);
546 skb_walk_frags(skb
, frag_iter
) {
549 WARN_ON(start
> offset
+ len
);
551 end
= start
+ frag_iter
->len
;
552 if ((copy
= end
- offset
) > 0) {
555 if (skb_copy_datagram_from_iovec(frag_iter
,
561 if ((len
-= copy
) == 0)
574 EXPORT_SYMBOL(skb_copy_datagram_from_iovec
);
576 static int skb_copy_and_csum_datagram(const struct sk_buff
*skb
, int offset
,
577 u8 __user
*to
, int len
,
580 int start
= skb_headlen(skb
);
581 int i
, copy
= start
- offset
;
582 struct sk_buff
*frag_iter
;
590 *csump
= csum_and_copy_to_user(skb
->data
+ offset
, to
, copy
,
594 if ((len
-= copy
) == 0)
601 for (i
= 0; i
< skb_shinfo(skb
)->nr_frags
; i
++) {
603 const skb_frag_t
*frag
= &skb_shinfo(skb
)->frags
[i
];
605 WARN_ON(start
> offset
+ len
);
607 end
= start
+ skb_frag_size(frag
);
608 if ((copy
= end
- offset
) > 0) {
612 struct page
*page
= skb_frag_page(frag
);
617 csum2
= csum_and_copy_to_user(vaddr
+
624 *csump
= csum_block_add(*csump
, csum2
, pos
);
634 skb_walk_frags(skb
, frag_iter
) {
637 WARN_ON(start
> offset
+ len
);
639 end
= start
+ frag_iter
->len
;
640 if ((copy
= end
- offset
) > 0) {
644 if (skb_copy_and_csum_datagram(frag_iter
,
649 *csump
= csum_block_add(*csump
, csum2
, pos
);
650 if ((len
-= copy
) == 0)
665 __sum16
__skb_checksum_complete_head(struct sk_buff
*skb
, int len
)
669 sum
= csum_fold(skb_checksum(skb
, 0, len
, skb
->csum
));
671 if (unlikely(skb
->ip_summed
== CHECKSUM_COMPLETE
))
672 netdev_rx_csum_fault(skb
->dev
);
673 skb
->ip_summed
= CHECKSUM_UNNECESSARY
;
677 EXPORT_SYMBOL(__skb_checksum_complete_head
);
679 __sum16
__skb_checksum_complete(struct sk_buff
*skb
)
681 return __skb_checksum_complete_head(skb
, skb
->len
);
683 EXPORT_SYMBOL(__skb_checksum_complete
);
686 * skb_copy_and_csum_datagram_iovec - Copy and checkum skb to user iovec.
688 * @hlen: hardware length
691 * Caller _must_ check that skb will fit to this iovec.
693 * Returns: 0 - success.
694 * -EINVAL - checksum failure.
695 * -EFAULT - fault during copy. Beware, in this case iovec
698 int skb_copy_and_csum_datagram_iovec(struct sk_buff
*skb
,
699 int hlen
, struct iovec
*iov
)
702 int chunk
= skb
->len
- hlen
;
707 /* Skip filled elements.
708 * Pretty silly, look at memcpy_toiovec, though 8)
710 while (!iov
->iov_len
)
713 if (iov
->iov_len
< chunk
) {
714 if (__skb_checksum_complete(skb
))
716 if (skb_copy_datagram_iovec(skb
, hlen
, iov
, chunk
))
719 csum
= csum_partial(skb
->data
, hlen
, skb
->csum
);
720 if (skb_copy_and_csum_datagram(skb
, hlen
, iov
->iov_base
,
725 if (unlikely(skb
->ip_summed
== CHECKSUM_COMPLETE
))
726 netdev_rx_csum_fault(skb
->dev
);
727 iov
->iov_len
-= chunk
;
728 iov
->iov_base
+= chunk
;
736 EXPORT_SYMBOL(skb_copy_and_csum_datagram_iovec
);
739 * datagram_poll - generic datagram poll
744 * Datagram poll: Again totally generic. This also handles
745 * sequenced packet sockets providing the socket receive queue
746 * is only ever holding data ready to receive.
748 * Note: when you _don't_ use this routine for this protocol,
749 * and you use a different write policy from sock_writeable()
750 * then please supply your own write_space callback.
752 unsigned int datagram_poll(struct file
*file
, struct socket
*sock
,
755 struct sock
*sk
= sock
->sk
;
758 sock_poll_wait(file
, sk_sleep(sk
), wait
);
761 /* exceptional events? */
762 if (sk
->sk_err
|| !skb_queue_empty(&sk
->sk_error_queue
))
764 (sock_flag(sk
, SOCK_SELECT_ERR_QUEUE
) ? POLLPRI
: 0);
766 if (sk
->sk_shutdown
& RCV_SHUTDOWN
)
767 mask
|= POLLRDHUP
| POLLIN
| POLLRDNORM
;
768 if (sk
->sk_shutdown
== SHUTDOWN_MASK
)
772 if (!skb_queue_empty(&sk
->sk_receive_queue
))
773 mask
|= POLLIN
| POLLRDNORM
;
775 /* Connection-based need to check for termination and startup */
776 if (connection_based(sk
)) {
777 if (sk
->sk_state
== TCP_CLOSE
)
779 /* connection hasn't started yet? */
780 if (sk
->sk_state
== TCP_SYN_SENT
)
785 if (sock_writeable(sk
))
786 mask
|= POLLOUT
| POLLWRNORM
| POLLWRBAND
;
788 set_bit(SOCK_ASYNC_NOSPACE
, &sk
->sk_socket
->flags
);
792 EXPORT_SYMBOL(datagram_poll
);