| /* |
| * SUCS NET3: |
| * |
| * Generic datagram handling routines. These are generic for all |
| * protocols. Possibly a generic IP version on top of these would |
| * make sense. Not tonight however 8-). |
| * This is used because UDP, RAW, PACKET, DDP, IPX, AX.25 and |
| * NetROM layer all have identical poll code and mostly |
| * identical recvmsg() code. So we share it here. The poll was |
| * shared before but buried in udp.c so I moved it. |
| * |
| * Authors: Alan Cox <alan@redhat.com>. (datagram_poll() from old |
| * udp.c code) |
| * |
| * Fixes: |
| * Alan Cox : NULL return from skb_peek_copy() |
| * understood |
| * Alan Cox : Rewrote skb_read_datagram to avoid the |
| * skb_peek_copy stuff. |
| * Alan Cox : Added support for SOCK_SEQPACKET. |
| * IPX can no longer use the SO_TYPE hack |
| * but AX.25 now works right, and SPX is |
| * feasible. |
| * Alan Cox : Fixed write poll of non IP protocol |
| * crash. |
| * Florian La Roche: Changed for my new skbuff handling. |
| * Darryl Miles : Fixed non-blocking SOCK_SEQPACKET. |
| * Linus Torvalds : BSD semantic fixes. |
| * Alan Cox : Datagram iovec handling |
| * Darryl Miles : Fixed non-blocking SOCK_STREAM. |
| * Alan Cox : POSIXisms |
| * Pete Wyckoff : Unconnected accept() fix. |
| * |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/types.h> |
| #include <linux/kernel.h> |
| #include <asm/uaccess.h> |
| #include <asm/system.h> |
| #include <linux/mm.h> |
| #include <linux/interrupt.h> |
| #include <linux/errno.h> |
| #include <linux/sched.h> |
| #include <linux/inet.h> |
| #include <linux/netdevice.h> |
| #include <linux/rtnetlink.h> |
| #include <linux/poll.h> |
| #include <linux/highmem.h> |
| |
| #include <net/protocol.h> |
| #include <linux/skbuff.h> |
| |
| #include <net/checksum.h> |
| #include <net/sock.h> |
| #include <net/tcp_states.h> |
| |
| /* |
| * Is a socket 'connection oriented' ? |
| */ |
| static inline int connection_based(struct sock *sk) |
| { |
| return sk->sk_type == SOCK_SEQPACKET || sk->sk_type == SOCK_STREAM; |
| } |
| |
| /* |
| * Wait for a packet.. |
| */ |
| static int wait_for_packet(struct sock *sk, int *err, long *timeo_p) |
| { |
| int error; |
| DEFINE_WAIT(wait); |
| |
| prepare_to_wait_exclusive(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE); |
| |
| /* Socket errors? */ |
| error = sock_error(sk); |
| if (error) |
| goto out_err; |
| |
| if (!skb_queue_empty(&sk->sk_receive_queue)) |
| goto out; |
| |
| /* Socket shut down? */ |
| if (sk->sk_shutdown & RCV_SHUTDOWN) |
| goto out_noerr; |
| |
| /* Sequenced packets can come disconnected. |
| * If so we report the problem |
| */ |
| error = -ENOTCONN; |
| if (connection_based(sk) && |
| !(sk->sk_state == TCP_ESTABLISHED || sk->sk_state == TCP_LISTEN)) |
| goto out_err; |
| |
| /* handle signals */ |
| if (signal_pending(current)) |
| goto interrupted; |
| |
| error = 0; |
| *timeo_p = schedule_timeout(*timeo_p); |
| out: |
| finish_wait(sk->sk_sleep, &wait); |
| return error; |
| interrupted: |
| error = sock_intr_errno(*timeo_p); |
| out_err: |
| *err = error; |
| goto out; |
| out_noerr: |
| *err = 0; |
| error = 1; |
| goto out; |
| } |
| |
| /** |
| * skb_recv_datagram - Receive a datagram skbuff |
| * @sk: socket |
| * @flags: MSG_ flags |
| * @noblock: blocking operation? |
| * @err: error code returned |
| * |
| * Get a datagram skbuff, understands the peeking, nonblocking wakeups |
| * and possible races. This replaces identical code in packet, raw and |
| * udp, as well as the IPX AX.25 and Appletalk. It also finally fixes |
| * the long standing peek and read race for datagram sockets. If you |
| * alter this routine remember it must be re-entrant. |
| * |
| * This function will lock the socket if a skb is returned, so the caller |
| * needs to unlock the socket in that case (usually by calling |
| * skb_free_datagram) |
| * |
| * * It does not lock socket since today. This function is |
| * * free of race conditions. This measure should/can improve |
| * * significantly datagram socket latencies at high loads, |
| * * when data copying to user space takes lots of time. |
| * * (BTW I've just killed the last cli() in IP/IPv6/core/netlink/packet |
| * * 8) Great win.) |
| * * --ANK (980729) |
| * |
| * The order of the tests when we find no data waiting are specified |
| * quite explicitly by POSIX 1003.1g, don't change them without having |
| * the standard around please. |
| */ |
| struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags, |
| int noblock, int *err) |
| { |
| struct sk_buff *skb; |
| long timeo; |
| /* |
| * Caller is allowed not to check sk->sk_err before skb_recv_datagram() |
| */ |
| int error = sock_error(sk); |
| |
| if (error) |
| goto no_packet; |
| |
| timeo = sock_rcvtimeo(sk, noblock); |
| |
| do { |
| /* Again only user level code calls this function, so nothing |
| * interrupt level will suddenly eat the receive_queue. |
| * |
| * Look at current nfs client by the way... |
| * However, this function was corrent in any case. 8) |
| */ |
| if (flags & MSG_PEEK) { |
| unsigned long cpu_flags; |
| |
| spin_lock_irqsave(&sk->sk_receive_queue.lock, |
| cpu_flags); |
| skb = skb_peek(&sk->sk_receive_queue); |
| if (skb) |
| atomic_inc(&skb->users); |
| spin_unlock_irqrestore(&sk->sk_receive_queue.lock, |
| cpu_flags); |
| } else |
| skb = skb_dequeue(&sk->sk_receive_queue); |
| |
| if (skb) |
| return skb; |
| |
| /* User doesn't want to wait */ |
| error = -EAGAIN; |
| if (!timeo) |
| goto no_packet; |
| |
| } while (!wait_for_packet(sk, err, &timeo)); |
| |
| return NULL; |
| |
| no_packet: |
| *err = error; |
| return NULL; |
| } |
| |
| void skb_free_datagram(struct sock *sk, struct sk_buff *skb) |
| { |
| kfree_skb(skb); |
| } |
| |
| /** |
| * skb_copy_datagram_iovec - Copy a datagram to an iovec. |
| * @skb: buffer to copy |
| * @offset: offset in the buffer to start copying from |
| * @to: io vector to copy to |
| * @len: amount of data to copy from buffer to iovec |
| * |
| * Note: the iovec is modified during the copy. |
| */ |
| int skb_copy_datagram_iovec(const struct sk_buff *skb, int offset, |
| struct iovec *to, int len) |
| { |
| int i, err, fraglen, end = 0; |
| struct sk_buff *next = skb_shinfo(skb)->frag_list; |
| next_skb: |
| fraglen = skb_headlen(skb); |
| i = -1; |
| |
| while (1) { |
| int start = end; |
| |
| if ((end += fraglen) > offset) { |
| int copy = end - offset, o = offset - start; |
| |
| if (copy > len) |
| copy = len; |
| if (i == -1) |
| err = memcpy_toiovec(to, skb->data + o, copy); |
| else { |
| skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; |
| struct page *page = frag->page; |
| void *p = kmap(page) + frag->page_offset + o; |
| err = memcpy_toiovec(to, p, copy); |
| kunmap(page); |
| } |
| if (err) |
| goto fault; |
| if (!(len -= copy)) |
| return 0; |
| offset += copy; |
| } |
| if (++i >= skb_shinfo(skb)->nr_frags) |
| break; |
| fraglen = skb_shinfo(skb)->frags[i].size; |
| } |
| if (next) { |
| skb = next; |
| BUG_ON(skb_shinfo(skb)->frag_list); |
| next = skb->next; |
| goto next_skb; |
| } |
| fault: |
| return -EFAULT; |
| } |
| |
| static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset, |
| u8 __user *to, int len, |
| unsigned int *csump) |
| { |
| int start = skb_headlen(skb); |
| int pos = 0; |
| int i, copy = start - offset; |
| |
| /* Copy header. */ |
| if (copy > 0) { |
| int err = 0; |
| if (copy > len) |
| copy = len; |
| *csump = csum_and_copy_to_user(skb->data + offset, to, copy, |
| *csump, &err); |
| if (err) |
| goto fault; |
| if ((len -= copy) == 0) |
| return 0; |
| offset += copy; |
| to += copy; |
| pos = copy; |
| } |
| |
| for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { |
| int end; |
| |
| BUG_TRAP(start <= offset + len); |
| |
| end = start + skb_shinfo(skb)->frags[i].size; |
| if ((copy = end - offset) > 0) { |
| unsigned int csum2; |
| int err = 0; |
| u8 *vaddr; |
| skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; |
| struct page *page = frag->page; |
| |
| if (copy > len) |
| copy = len; |
| vaddr = kmap(page); |
| csum2 = csum_and_copy_to_user(vaddr + |
| frag->page_offset + |
| offset - start, |
| to, copy, 0, &err); |
| kunmap(page); |
| if (err) |
| goto fault; |
| *csump = csum_block_add(*csump, csum2, pos); |
| if (!(len -= copy)) |
| return 0; |
| offset += copy; |
| to += copy; |
| pos += copy; |
| } |
| start = end; |
| } |
| |
| if (skb_shinfo(skb)->frag_list) { |
| struct sk_buff *list = skb_shinfo(skb)->frag_list; |
| |
| for (; list; list=list->next) { |
| int end; |
| |
| BUG_TRAP(start <= offset + len); |
| |
| end = start + list->len; |
| if ((copy = end - offset) > 0) { |
| unsigned int csum2 = 0; |
| if (copy > len) |
| copy = len; |
| if (skb_copy_and_csum_datagram(list, |
| offset - start, |
| to, copy, |
| &csum2)) |
| goto fault; |
| *csump = csum_block_add(*csump, csum2, pos); |
| if ((len -= copy) == 0) |
| return 0; |
| offset += copy; |
| to += copy; |
| pos += copy; |
| } |
| start = end; |
| } |
| } |
| if (!len) |
| return 0; |
| |
| fault: |
| return -EFAULT; |
| } |
| |
| /** |
| * skb_copy_and_csum_datagram_iovec - Copy and checkum skb to user iovec. |
| * @skb: skbuff |
| * @hlen: hardware length |
| * @iov: io vector |
| * |
| * Caller _must_ check that skb will fit to this iovec. |
| * |
| * Returns: 0 - success. |
| * -EINVAL - checksum failure. |
| * -EFAULT - fault during copy. Beware, in this case iovec |
| * can be modified! |
| */ |
| int skb_copy_and_csum_datagram_iovec(const struct sk_buff *skb, |
| int hlen, struct iovec *iov) |
| { |
| unsigned int csum; |
| int chunk = skb->len - hlen; |
| |
| /* Skip filled elements. |
| * Pretty silly, look at memcpy_toiovec, though 8) |
| */ |
| while (!iov->iov_len) |
| iov++; |
| |
| if (iov->iov_len < chunk) { |
| if ((unsigned short)csum_fold(skb_checksum(skb, 0, chunk + hlen, |
| skb->csum))) |
| goto csum_error; |
| if (skb_copy_datagram_iovec(skb, hlen, iov, chunk)) |
| goto fault; |
| } else { |
| csum = csum_partial(skb->data, hlen, skb->csum); |
| if (skb_copy_and_csum_datagram(skb, hlen, iov->iov_base, |
| chunk, &csum)) |
| goto fault; |
| if ((unsigned short)csum_fold(csum)) |
| goto csum_error; |
| iov->iov_len -= chunk; |
| iov->iov_base += chunk; |
| } |
| return 0; |
| csum_error: |
| return -EINVAL; |
| fault: |
| return -EFAULT; |
| } |
| |
| /** |
| * datagram_poll - generic datagram poll |
| * @file: file struct |
| * @sock: socket |
| * @wait: poll table |
| * |
| * Datagram poll: Again totally generic. This also handles |
| * sequenced packet sockets providing the socket receive queue |
| * is only ever holding data ready to receive. |
| * |
| * Note: when you _don't_ use this routine for this protocol, |
| * and you use a different write policy from sock_writeable() |
| * then please supply your own write_space callback. |
| */ |
| unsigned int datagram_poll(struct file *file, struct socket *sock, |
| poll_table *wait) |
| { |
| struct sock *sk = sock->sk; |
| unsigned int mask; |
| |
| poll_wait(file, sk->sk_sleep, wait); |
| mask = 0; |
| |
| /* exceptional events? */ |
| if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue)) |
| mask |= POLLERR; |
| if (sk->sk_shutdown == SHUTDOWN_MASK) |
| mask |= POLLHUP; |
| |
| /* readable? */ |
| if (!skb_queue_empty(&sk->sk_receive_queue) || |
| (sk->sk_shutdown & RCV_SHUTDOWN)) |
| mask |= POLLIN | POLLRDNORM; |
| |
| /* Connection-based need to check for termination and startup */ |
| if (connection_based(sk)) { |
| if (sk->sk_state == TCP_CLOSE) |
| mask |= POLLHUP; |
| /* connection hasn't started yet? */ |
| if (sk->sk_state == TCP_SYN_SENT) |
| return mask; |
| } |
| |
| /* writable? */ |
| if (sock_writeable(sk)) |
| mask |= POLLOUT | POLLWRNORM | POLLWRBAND; |
| else |
| set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags); |
| |
| return mask; |
| } |
| |
| EXPORT_SYMBOL(datagram_poll); |
| EXPORT_SYMBOL(skb_copy_and_csum_datagram_iovec); |
| EXPORT_SYMBOL(skb_copy_datagram_iovec); |
| EXPORT_SYMBOL(skb_free_datagram); |
| EXPORT_SYMBOL(skb_recv_datagram); |