--- /dev/null
+/*
+ * 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@lxorguk.ukuu.org.uk>. (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 <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 <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/pagemap.h>
+#include <linux/uio.h>
+
+#include <net/protocol.h>
+#include <linux/skbuff.h>
+
+#include <net/checksum.h>
+#include <net/sock.h>
+#include <net/tcp_states.h>
+#include <trace/events/skb.h>
+#include <net/busy_poll.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;
+}
+
+static int receiver_wake_function(wait_queue_t *wait, unsigned int mode, int sync,
+ void *key)
+{
+ unsigned long bits = (unsigned long)key;
+
+ /*
+ * Avoid a wakeup if event not interesting for us
+ */
+ if (bits && !(bits & (POLLIN | POLLERR)))
+ return 0;
+ return autoremove_wake_function(wait, mode, sync, key);
+}
+/*
+ * Wait for the last received packet to be different from skb
+ */
+static int wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
+ const struct sk_buff *skb)
+{
+ int error;
+ DEFINE_WAIT_FUNC(wait, receiver_wake_function);
+
+ prepare_to_wait_exclusive(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
+
+ /* Socket errors? */
+ error = sock_error(sk);
+ if (error)
+ goto out_err;
+
+ if (sk->sk_receive_queue.prev != skb)
+ 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_sleep(sk), &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
+ * @peeked: returns non-zero if this packet has been seen before
+ * @off: an offset in bytes to peek skb from. Returns an offset
+ * within an skb where data actually starts
+ * @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 int flags,
+ int *peeked, int *off, int *err)
+{
+ struct sk_buff *skb, *last;
+ 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, flags & MSG_DONTWAIT);
+
+ 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 correct in any case. 8)
+ */
+ unsigned long cpu_flags;
+ struct sk_buff_head *queue = &sk->sk_receive_queue;
+ int _off = *off;
+
+ last = (struct sk_buff *)queue;
+ spin_lock_irqsave(&queue->lock, cpu_flags);
+ skb_queue_walk(queue, skb) {
+ last = skb;
+ *peeked = skb->peeked;
+ if (flags & MSG_PEEK) {
+ if (_off >= skb->len && (skb->len || _off ||
+ skb->peeked)) {
+ _off -= skb->len;
+ continue;
+ }
+ skb->peeked = 1;
+ atomic_inc(&skb->users);
+ } else
+ __skb_unlink(skb, queue);
+
+ spin_unlock_irqrestore(&queue->lock, cpu_flags);
+ *off = _off;
+ return skb;
+ }
+ spin_unlock_irqrestore(&queue->lock, cpu_flags);
+
+ if (sk_can_busy_loop(sk) &&
+ sk_busy_loop(sk, flags & MSG_DONTWAIT))
+ continue;
+
+ /* User doesn't want to wait */
+ error = -EAGAIN;
+ if (!timeo)
+ goto no_packet;
+
+ } while (!wait_for_more_packets(sk, err, &timeo, last));
+
+ return NULL;
+
+no_packet:
+ *err = error;
+ return NULL;
+}
+EXPORT_SYMBOL(__skb_recv_datagram);
+
+struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned int flags,
+ int noblock, int *err)
+{
+ int peeked, off = 0;
+
+ return __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
+ &peeked, &off, err);
+}
+EXPORT_SYMBOL(skb_recv_datagram);
+
+void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
+{
+ consume_skb(skb);
+ sk_mem_reclaim_partial(sk);
+}
+EXPORT_SYMBOL(skb_free_datagram);
+
+void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb)
+{
+ bool slow;
+
+ if (likely(atomic_read(&skb->users) == 1))
+ smp_rmb();
+ else if (likely(!atomic_dec_and_test(&skb->users)))
+ return;
+
+ slow = lock_sock_fast(sk);
+ skb_orphan(skb);
+ sk_mem_reclaim_partial(sk);
+ unlock_sock_fast(sk, slow);
+
+ /* skb is now orphaned, can be freed outside of locked section */
+ __kfree_skb(skb);
+}
+EXPORT_SYMBOL(skb_free_datagram_locked);
+
+/**
+ * skb_kill_datagram - Free a datagram skbuff forcibly
+ * @sk: socket
+ * @skb: datagram skbuff
+ * @flags: MSG_ flags
+ *
+ * This function frees a datagram skbuff that was received by
+ * skb_recv_datagram. The flags argument must match the one
+ * used for skb_recv_datagram.
+ *
+ * If the MSG_PEEK flag is set, and the packet is still on the
+ * receive queue of the socket, it will be taken off the queue
+ * before it is freed.
+ *
+ * This function currently only disables BH when acquiring the
+ * sk_receive_queue lock. Therefore it must not be used in a
+ * context where that lock is acquired in an IRQ context.
+ *
+ * It returns 0 if the packet was removed by us.
+ */
+
+int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags)
+{
+ int err = 0;
+
+ if (flags & MSG_PEEK) {
+ err = -ENOENT;
+ spin_lock_bh(&sk->sk_receive_queue.lock);
+ if (skb == skb_peek(&sk->sk_receive_queue)) {
+ __skb_unlink(skb, &sk->sk_receive_queue);
+ atomic_dec(&skb->users);
+ err = 0;
+ }
+ spin_unlock_bh(&sk->sk_receive_queue.lock);
+ }
+
+ kfree_skb(skb);
+ atomic_inc(&sk->sk_drops);
+ sk_mem_reclaim_partial(sk);
+
+ return err;
+}
+EXPORT_SYMBOL(skb_kill_datagram);
+
+/**
+ * skb_copy_datagram_iter - Copy a datagram to an iovec iterator.
+ * @skb: buffer to copy
+ * @offset: offset in the buffer to start copying from
+ * @to: iovec iterator to copy to
+ * @len: amount of data to copy from buffer to iovec
+ */
+int skb_copy_datagram_iter(const struct sk_buff *skb, int offset,
+ struct iov_iter *to, int len)
+{
+ int start = skb_headlen(skb);
+ int i, copy = start - offset;
+ struct sk_buff *frag_iter;
+
+ trace_skb_copy_datagram_iovec(skb, len);
+
+ /* Copy header. */
+ if (copy > 0) {
+ if (copy > len)
+ copy = len;
+ if (copy_to_iter(skb->data + offset, copy, to) != copy)
+ goto short_copy;
+ if ((len -= copy) == 0)
+ return 0;
+ offset += copy;
+ }
+
+ /* Copy paged appendix. Hmm... why does this look so complicated? */
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ int end;
+ const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+ WARN_ON(start > offset + len);
+
+ end = start + skb_frag_size(frag);
+ if ((copy = end - offset) > 0) {
+ if (copy > len)
+ copy = len;
+ if (copy_page_to_iter(skb_frag_page(frag),
+ frag->page_offset + offset -
+ start, copy, to) != copy)
+ goto short_copy;
+ if (!(len -= copy))
+ return 0;
+ offset += copy;
+ }
+ start = end;
+ }
+
+ skb_walk_frags(skb, frag_iter) {
+ int end;
+
+ WARN_ON(start > offset + len);
+
+ end = start + frag_iter->len;
+ if ((copy = end - offset) > 0) {
+ if (copy > len)
+ copy = len;
+ if (skb_copy_datagram_iter(frag_iter, offset - start,
+ to, copy))
+ goto fault;
+ if ((len -= copy) == 0)
+ return 0;
+ offset += copy;
+ }
+ start = end;
+ }
+ if (!len)
+ return 0;
+
+ /* This is not really a user copy fault, but rather someone
+ * gave us a bogus length on the skb. We should probably
+ * print a warning here as it may indicate a kernel bug.
+ */
+
+fault:
+ return -EFAULT;
+
+short_copy:
+ if (iov_iter_count(to))
+ goto fault;
+
+ return 0;
+}
+EXPORT_SYMBOL(skb_copy_datagram_iter);
+
+/**
+ * skb_copy_datagram_from_iter - Copy a datagram from an iov_iter.
+ * @skb: buffer to copy
+ * @offset: offset in the buffer to start copying to
+ * @from: the copy source
+ * @len: amount of data to copy to buffer from iovec
+ *
+ * Returns 0 or -EFAULT.
+ */
+int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
+ struct iov_iter *from,
+ int len)
+{
+ int start = skb_headlen(skb);
+ int i, copy = start - offset;
+ struct sk_buff *frag_iter;
+
+ /* Copy header. */
+ if (copy > 0) {
+ if (copy > len)
+ copy = len;
+ if (copy_from_iter(skb->data + offset, copy, from) != copy)
+ goto fault;
+ if ((len -= copy) == 0)
+ return 0;
+ offset += copy;
+ }
+
+ /* Copy paged appendix. Hmm... why does this look so complicated? */
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ int end;
+ const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+ WARN_ON(start > offset + len);
+
+ end = start + skb_frag_size(frag);
+ if ((copy = end - offset) > 0) {
+ size_t copied;
+
+ if (copy > len)
+ copy = len;
+ copied = copy_page_from_iter(skb_frag_page(frag),
+ frag->page_offset + offset - start,
+ copy, from);
+ if (copied != copy)
+ goto fault;
+
+ if (!(len -= copy))
+ return 0;
+ offset += copy;
+ }
+ start = end;
+ }
+
+ skb_walk_frags(skb, frag_iter) {
+ int end;
+
+ WARN_ON(start > offset + len);
+
+ end = start + frag_iter->len;
+ if ((copy = end - offset) > 0) {
+ if (copy > len)
+ copy = len;
+ if (skb_copy_datagram_from_iter(frag_iter,
+ offset - start,
+ from, copy))
+ goto fault;
+ if ((len -= copy) == 0)
+ return 0;
+ offset += copy;
+ }
+ start = end;
+ }
+ if (!len)
+ return 0;
+
+fault:
+ return -EFAULT;
+}
+EXPORT_SYMBOL(skb_copy_datagram_from_iter);
+
+/**
+ * zerocopy_sg_from_iter - Build a zerocopy datagram from an iov_iter
+ * @skb: buffer to copy
+ * @from: the source to copy from
+ *
+ * The function will first copy up to headlen, and then pin the userspace
+ * pages and build frags through them.
+ *
+ * Returns 0, -EFAULT or -EMSGSIZE.
+ */
+int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
+{
+ int len = iov_iter_count(from);
+ int copy = min_t(int, skb_headlen(skb), len);
+ int frag = 0;
+
+ /* copy up to skb headlen */
+ if (skb_copy_datagram_from_iter(skb, 0, from, copy))
+ return -EFAULT;
+
+ while (iov_iter_count(from)) {
+ struct page *pages[MAX_SKB_FRAGS];
+ size_t start;
+ ssize_t copied;
+ unsigned long truesize;
+ int n = 0;
+
+ if (frag == MAX_SKB_FRAGS)
+ return -EMSGSIZE;
+
+ copied = iov_iter_get_pages(from, pages, ~0U,
+ MAX_SKB_FRAGS - frag, &start);
+ if (copied < 0)
+ return -EFAULT;
+
+ iov_iter_advance(from, copied);
+
+ truesize = PAGE_ALIGN(copied + start);
+ skb->data_len += copied;
+ skb->len += copied;
+ skb->truesize += truesize;
+ atomic_add(truesize, &skb->sk->sk_wmem_alloc);
+ while (copied) {
+ int size = min_t(int, copied, PAGE_SIZE - start);
+ skb_fill_page_desc(skb, frag++, pages[n], start, size);
+ start = 0;
+ copied -= size;
+ n++;
+ }
+ }
+ return 0;
+}
+EXPORT_SYMBOL(zerocopy_sg_from_iter);
+
+static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
+ struct iov_iter *to, int len,
+ __wsum *csump)
+{
+ int start = skb_headlen(skb);
+ int i, copy = start - offset;
+ struct sk_buff *frag_iter;
+ int pos = 0;
+ int n;
+
+ /* Copy header. */
+ if (copy > 0) {
+ if (copy > len)
+ copy = len;
+ n = csum_and_copy_to_iter(skb->data + offset, copy, csump, to);
+ if (n != copy)
+ goto fault;
+ if ((len -= copy) == 0)
+ return 0;
+ offset += copy;
+ pos = copy;
+ }
+
+ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+ int end;
+ const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+ WARN_ON(start > offset + len);
+
+ end = start + skb_frag_size(frag);
+ if ((copy = end - offset) > 0) {
+ __wsum csum2 = 0;
+ struct page *page = skb_frag_page(frag);
+ u8 *vaddr = kmap(page);
+
+ if (copy > len)
+ copy = len;
+ n = csum_and_copy_to_iter(vaddr + frag->page_offset +
+ offset - start, copy,
+ &csum2, to);
+ kunmap(page);
+ if (n != copy)
+ goto fault;
+ *csump = csum_block_add(*csump, csum2, pos);
+ if (!(len -= copy))
+ return 0;
+ offset += copy;
+ pos += copy;
+ }
+ start = end;
+ }
+
+ skb_walk_frags(skb, frag_iter) {
+ int end;
+
+ WARN_ON(start > offset + len);
+
+ end = start + frag_iter->len;
+ if ((copy = end - offset) > 0) {
+ __wsum csum2 = 0;
+ if (copy > len)
+ copy = len;
+ if (skb_copy_and_csum_datagram(frag_iter,
+ offset - start,
+ to, copy,
+ &csum2))
+ goto fault;
+ *csump = csum_block_add(*csump, csum2, pos);
+ if ((len -= copy) == 0)
+ return 0;
+ offset += copy;
+ pos += copy;
+ }
+ start = end;
+ }
+ if (!len)
+ return 0;
+
+fault:
+ return -EFAULT;
+}
+
+__sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
+{
+ __sum16 sum;
+
+ sum = csum_fold(skb_checksum(skb, 0, len, skb->csum));
+ if (likely(!sum)) {
+ if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
+ !skb->csum_complete_sw)
+ netdev_rx_csum_fault(skb->dev);
+ }
+ skb->csum_valid = !sum;
+ return sum;
+}
+EXPORT_SYMBOL(__skb_checksum_complete_head);
+
+__sum16 __skb_checksum_complete(struct sk_buff *skb)
+{
+ __wsum csum;
+ __sum16 sum;
+
+ csum = skb_checksum(skb, 0, skb->len, 0);
+
+ /* skb->csum holds pseudo checksum */
+ sum = csum_fold(csum_add(skb->csum, csum));
+ if (likely(!sum)) {
+ if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
+ !skb->csum_complete_sw)
+ netdev_rx_csum_fault(skb->dev);
+ }
+
+ /* Save full packet checksum */
+ skb->csum = csum;
+ skb->ip_summed = CHECKSUM_COMPLETE;
+ skb->csum_complete_sw = 1;
+ skb->csum_valid = !sum;
+
+ return sum;
+}
+EXPORT_SYMBOL(__skb_checksum_complete);
+
+/**
+ * skb_copy_and_csum_datagram_msg - Copy and checksum skb to user iovec.
+ * @skb: skbuff
+ * @hlen: hardware length
+ * @msg: destination
+ *
+ * Caller _must_ check that skb will fit to this iovec.
+ *
+ * Returns: 0 - success.
+ * -EINVAL - checksum failure.
+ * -EFAULT - fault during copy.
+ */
+int skb_copy_and_csum_datagram_msg(struct sk_buff *skb,
+ int hlen, struct msghdr *msg)
+{
+ __wsum csum;
+ int chunk = skb->len - hlen;
+
+ if (!chunk)
+ return 0;
+
+ if (msg_data_left(msg) < chunk) {
+ if (__skb_checksum_complete(skb))
+ goto csum_error;
+ if (skb_copy_datagram_msg(skb, hlen, msg, chunk))
+ goto fault;
+ } else {
+ csum = csum_partial(skb->data, hlen, skb->csum);
+ if (skb_copy_and_csum_datagram(skb, hlen, &msg->msg_iter,
+ chunk, &csum))
+ goto fault;
+ if (csum_fold(csum))
+ goto csum_error;
+ if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
+ netdev_rx_csum_fault(skb->dev);
+ }
+ return 0;
+csum_error:
+ return -EINVAL;
+fault:
+ return -EFAULT;
+}
+EXPORT_SYMBOL(skb_copy_and_csum_datagram_msg);
+
+/**
+ * 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;
+
+ sock_poll_wait(file, sk_sleep(sk), wait);
+ mask = 0;
+
+ /* exceptional events? */
+ if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
+ mask |= POLLERR |
+ (sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? POLLPRI : 0);
+
+ if (sk->sk_shutdown & RCV_SHUTDOWN)
+ mask |= POLLRDHUP | POLLIN | POLLRDNORM;
+ if (sk->sk_shutdown == SHUTDOWN_MASK)
+ mask |= POLLHUP;
+
+ /* readable? */
+ if (!skb_queue_empty(&sk->sk_receive_queue))
+ 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);
Code Review / kvmfornfv.git / blobdiff