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-rw-r--r--net/core/datagram.c842
1 files changed, 842 insertions, 0 deletions
diff --git a/net/core/datagram.c b/net/core/datagram.c
new file mode 100644
index 000000000..8dabb9a74
--- /dev/null
+++ b/net/core/datagram.c
@@ -0,0 +1,842 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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 <linux/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 <linux/indirect_call_wrapper.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_entry_t *wait, unsigned int mode, int sync,
+ void *key)
+{
+ /*
+ * Avoid a wakeup if event not interesting for us
+ */
+ if (key && !(key_to_poll(key) & (EPOLLIN | EPOLLERR)))
+ return 0;
+ return autoremove_wake_function(wait, mode, sync, key);
+}
+/*
+ * Wait for the last received packet to be different from skb
+ */
+int __skb_wait_for_more_packets(struct sock *sk, struct sk_buff_head *queue,
+ 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 (READ_ONCE(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;
+}
+EXPORT_SYMBOL(__skb_wait_for_more_packets);
+
+static struct sk_buff *skb_set_peeked(struct sk_buff *skb)
+{
+ struct sk_buff *nskb;
+
+ if (skb->peeked)
+ return skb;
+
+ /* We have to unshare an skb before modifying it. */
+ if (!skb_shared(skb))
+ goto done;
+
+ nskb = skb_clone(skb, GFP_ATOMIC);
+ if (!nskb)
+ return ERR_PTR(-ENOMEM);
+
+ skb->prev->next = nskb;
+ skb->next->prev = nskb;
+ nskb->prev = skb->prev;
+ nskb->next = skb->next;
+
+ consume_skb(skb);
+ skb = nskb;
+
+done:
+ skb->peeked = 1;
+
+ return skb;
+}
+
+struct sk_buff *__skb_try_recv_from_queue(struct sock *sk,
+ struct sk_buff_head *queue,
+ unsigned int flags,
+ int *off, int *err,
+ struct sk_buff **last)
+{
+ bool peek_at_off = false;
+ struct sk_buff *skb;
+ int _off = 0;
+
+ if (unlikely(flags & MSG_PEEK && *off >= 0)) {
+ peek_at_off = true;
+ _off = *off;
+ }
+
+ *last = queue->prev;
+ skb_queue_walk(queue, skb) {
+ if (flags & MSG_PEEK) {
+ if (peek_at_off && _off >= skb->len &&
+ (_off || skb->peeked)) {
+ _off -= skb->len;
+ continue;
+ }
+ if (!skb->len) {
+ skb = skb_set_peeked(skb);
+ if (IS_ERR(skb)) {
+ *err = PTR_ERR(skb);
+ return NULL;
+ }
+ }
+ refcount_inc(&skb->users);
+ } else {
+ __skb_unlink(skb, queue);
+ }
+ *off = _off;
+ return skb;
+ }
+ return NULL;
+}
+
+/**
+ * __skb_try_recv_datagram - Receive a datagram skbuff
+ * @sk: socket
+ * @queue: socket queue from which to receive
+ * @flags: MSG\_ flags
+ * @off: an offset in bytes to peek skb from. Returns an offset
+ * within an skb where data actually starts
+ * @err: error code returned
+ * @last: set to last peeked message to inform the wait function
+ * what to look for when peeking
+ *
+ * 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). Returns NULL with @err set to
+ * -EAGAIN if no data was available or to some other value if an
+ * error was detected.
+ *
+ * * 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_try_recv_datagram(struct sock *sk,
+ struct sk_buff_head *queue,
+ unsigned int flags, int *off, int *err,
+ struct sk_buff **last)
+{
+ struct sk_buff *skb;
+ unsigned long cpu_flags;
+ /*
+ * Caller is allowed not to check sk->sk_err before skb_recv_datagram()
+ */
+ int error = sock_error(sk);
+
+ if (error)
+ goto no_packet;
+
+ 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)
+ */
+ spin_lock_irqsave(&queue->lock, cpu_flags);
+ skb = __skb_try_recv_from_queue(sk, queue, flags, off, &error,
+ last);
+ spin_unlock_irqrestore(&queue->lock, cpu_flags);
+ if (error)
+ goto no_packet;
+ if (skb)
+ return skb;
+
+ if (!sk_can_busy_loop(sk))
+ break;
+
+ sk_busy_loop(sk, flags & MSG_DONTWAIT);
+ } while (READ_ONCE(queue->prev) != *last);
+
+ error = -EAGAIN;
+
+no_packet:
+ *err = error;
+ return NULL;
+}
+EXPORT_SYMBOL(__skb_try_recv_datagram);
+
+struct sk_buff *__skb_recv_datagram(struct sock *sk,
+ struct sk_buff_head *sk_queue,
+ unsigned int flags, int *off, int *err)
+{
+ struct sk_buff *skb, *last;
+ long timeo;
+
+ timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+
+ do {
+ skb = __skb_try_recv_datagram(sk, sk_queue, flags, off, err,
+ &last);
+ if (skb)
+ return skb;
+
+ if (*err != -EAGAIN)
+ break;
+ } while (timeo &&
+ !__skb_wait_for_more_packets(sk, sk_queue, err,
+ &timeo, last));
+
+ return NULL;
+}
+EXPORT_SYMBOL(__skb_recv_datagram);
+
+struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned int flags,
+ int *err)
+{
+ int off = 0;
+
+ return __skb_recv_datagram(sk, &sk->sk_receive_queue, flags,
+ &off, err);
+}
+EXPORT_SYMBOL(skb_recv_datagram);
+
+void skb_free_datagram(struct sock *sk, struct sk_buff *skb)
+{
+ consume_skb(skb);
+}
+EXPORT_SYMBOL(skb_free_datagram);
+
+void __skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb, int len)
+{
+ bool slow;
+
+ if (!skb_unref(skb)) {
+ sk_peek_offset_bwd(sk, len);
+ return;
+ }
+
+ slow = lock_sock_fast(sk);
+ sk_peek_offset_bwd(sk, len);
+ skb_orphan(skb);
+ 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);
+
+int __sk_queue_drop_skb(struct sock *sk, struct sk_buff_head *sk_queue,
+ struct sk_buff *skb, unsigned int flags,
+ void (*destructor)(struct sock *sk,
+ struct sk_buff *skb))
+{
+ int err = 0;
+
+ if (flags & MSG_PEEK) {
+ err = -ENOENT;
+ spin_lock_bh(&sk_queue->lock);
+ if (skb->next) {
+ __skb_unlink(skb, sk_queue);
+ refcount_dec(&skb->users);
+ if (destructor)
+ destructor(sk, skb);
+ err = 0;
+ }
+ spin_unlock_bh(&sk_queue->lock);
+ }
+
+ atomic_inc(&sk->sk_drops);
+ return err;
+}
+EXPORT_SYMBOL(__sk_queue_drop_skb);
+
+/**
+ * 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 = __sk_queue_drop_skb(sk, &sk->sk_receive_queue, skb, flags,
+ NULL);
+
+ kfree_skb(skb);
+ return err;
+}
+EXPORT_SYMBOL(skb_kill_datagram);
+
+INDIRECT_CALLABLE_DECLARE(static size_t simple_copy_to_iter(const void *addr,
+ size_t bytes,
+ void *data __always_unused,
+ struct iov_iter *i));
+
+static int __skb_datagram_iter(const struct sk_buff *skb, int offset,
+ struct iov_iter *to, int len, bool fault_short,
+ size_t (*cb)(const void *, size_t, void *,
+ struct iov_iter *), void *data)
+{
+ int start = skb_headlen(skb);
+ int i, copy = start - offset, start_off = offset, n;
+ struct sk_buff *frag_iter;
+
+ /* Copy header. */
+ if (copy > 0) {
+ if (copy > len)
+ copy = len;
+ n = INDIRECT_CALL_1(cb, simple_copy_to_iter,
+ skb->data + offset, copy, data, to);
+ offset += n;
+ if (n != copy)
+ goto short_copy;
+ if ((len -= copy) == 0)
+ return 0;
+ }
+
+ /* 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) {
+ struct page *page = skb_frag_page(frag);
+ u8 *vaddr = kmap(page);
+
+ if (copy > len)
+ copy = len;
+ n = INDIRECT_CALL_1(cb, simple_copy_to_iter,
+ vaddr + skb_frag_off(frag) + offset - start,
+ copy, data, to);
+ kunmap(page);
+ offset += n;
+ if (n != copy)
+ goto short_copy;
+ if (!(len -= copy))
+ return 0;
+ }
+ 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_datagram_iter(frag_iter, offset - start,
+ to, copy, fault_short, cb, data))
+ 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:
+ iov_iter_revert(to, offset - start_off);
+ return -EFAULT;
+
+short_copy:
+ if (fault_short || iov_iter_count(to))
+ goto fault;
+
+ return 0;
+}
+
+/**
+ * skb_copy_and_hash_datagram_iter - Copy datagram to an iovec iterator
+ * and update a hash.
+ * @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
+ * @hash: hash request to update
+ */
+int skb_copy_and_hash_datagram_iter(const struct sk_buff *skb, int offset,
+ struct iov_iter *to, int len,
+ struct ahash_request *hash)
+{
+ return __skb_datagram_iter(skb, offset, to, len, true,
+ hash_and_copy_to_iter, hash);
+}
+EXPORT_SYMBOL(skb_copy_and_hash_datagram_iter);
+
+static size_t simple_copy_to_iter(const void *addr, size_t bytes,
+ void *data __always_unused, struct iov_iter *i)
+{
+ return copy_to_iter(addr, bytes, i);
+}
+
+/**
+ * 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)
+{
+ trace_skb_copy_datagram_iovec(skb, len);
+ return __skb_datagram_iter(skb, offset, to, len, false,
+ simple_copy_to_iter, NULL);
+}
+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),
+ skb_frag_off(frag) + 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);
+
+int __zerocopy_sg_from_iter(struct msghdr *msg, struct sock *sk,
+ struct sk_buff *skb, struct iov_iter *from,
+ size_t length)
+{
+ int frag;
+
+ if (msg && msg->msg_ubuf && msg->sg_from_iter)
+ return msg->sg_from_iter(sk, skb, from, length);
+
+ frag = skb_shinfo(skb)->nr_frags;
+
+ while (length && iov_iter_count(from)) {
+ struct page *pages[MAX_SKB_FRAGS];
+ struct page *last_head = NULL;
+ size_t start;
+ ssize_t copied;
+ unsigned long truesize;
+ int refs, n = 0;
+
+ if (frag == MAX_SKB_FRAGS)
+ return -EMSGSIZE;
+
+ copied = iov_iter_get_pages2(from, pages, length,
+ MAX_SKB_FRAGS - frag, &start);
+ if (copied < 0)
+ return -EFAULT;
+
+ length -= copied;
+
+ truesize = PAGE_ALIGN(copied + start);
+ skb->data_len += copied;
+ skb->len += copied;
+ skb->truesize += truesize;
+ if (sk && sk->sk_type == SOCK_STREAM) {
+ sk_wmem_queued_add(sk, truesize);
+ if (!skb_zcopy_pure(skb))
+ sk_mem_charge(sk, truesize);
+ } else {
+ refcount_add(truesize, &skb->sk->sk_wmem_alloc);
+ }
+ for (refs = 0; copied != 0; start = 0) {
+ int size = min_t(int, copied, PAGE_SIZE - start);
+ struct page *head = compound_head(pages[n]);
+
+ start += (pages[n] - head) << PAGE_SHIFT;
+ copied -= size;
+ n++;
+ if (frag) {
+ skb_frag_t *last = &skb_shinfo(skb)->frags[frag - 1];
+
+ if (head == skb_frag_page(last) &&
+ start == skb_frag_off(last) + skb_frag_size(last)) {
+ skb_frag_size_add(last, size);
+ /* We combined this page, we need to release
+ * a reference. Since compound pages refcount
+ * is shared among many pages, batch the refcount
+ * adjustments to limit false sharing.
+ */
+ last_head = head;
+ refs++;
+ continue;
+ }
+ }
+ if (refs) {
+ page_ref_sub(last_head, refs);
+ refs = 0;
+ }
+ skb_fill_page_desc_noacc(skb, frag++, head, start, size);
+ }
+ if (refs)
+ page_ref_sub(last_head, refs);
+ }
+ return 0;
+}
+EXPORT_SYMBOL(__zerocopy_sg_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 copy = min_t(int, skb_headlen(skb), iov_iter_count(from));
+
+ /* copy up to skb headlen */
+ if (skb_copy_datagram_from_iter(skb, 0, from, copy))
+ return -EFAULT;
+
+ return __zerocopy_sg_from_iter(NULL, NULL, skb, from, ~0U);
+}
+EXPORT_SYMBOL(zerocopy_sg_from_iter);
+
+/**
+ * skb_copy_and_csum_datagram - Copy datagram to an iovec iterator
+ * and update a checksum.
+ * @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
+ * @csump: checksum pointer
+ */
+static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
+ struct iov_iter *to, int len,
+ __wsum *csump)
+{
+ struct csum_state csdata = { .csum = *csump };
+ int ret;
+
+ ret = __skb_datagram_iter(skb, offset, to, len, true,
+ csum_and_copy_to_iter, &csdata);
+ if (ret)
+ return ret;
+
+ *csump = csdata.csum;
+ return 0;
+}
+
+/**
+ * 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))
+ return -EINVAL;
+ 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)) {
+ iov_iter_revert(&msg->msg_iter, chunk);
+ return -EINVAL;
+ }
+
+ if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE) &&
+ !skb->csum_complete_sw)
+ netdev_rx_csum_fault(NULL, skb);
+ }
+ return 0;
+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.
+ */
+__poll_t datagram_poll(struct file *file, struct socket *sock,
+ poll_table *wait)
+{
+ struct sock *sk = sock->sk;
+ __poll_t mask;
+ u8 shutdown;
+
+ sock_poll_wait(file, sock, wait);
+ mask = 0;
+
+ /* exceptional events? */
+ if (READ_ONCE(sk->sk_err) ||
+ !skb_queue_empty_lockless(&sk->sk_error_queue))
+ mask |= EPOLLERR |
+ (sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? EPOLLPRI : 0);
+
+ shutdown = READ_ONCE(sk->sk_shutdown);
+ if (shutdown & RCV_SHUTDOWN)
+ mask |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM;
+ if (shutdown == SHUTDOWN_MASK)
+ mask |= EPOLLHUP;
+
+ /* readable? */
+ if (!skb_queue_empty_lockless(&sk->sk_receive_queue))
+ mask |= EPOLLIN | EPOLLRDNORM;
+
+ /* Connection-based need to check for termination and startup */
+ if (connection_based(sk)) {
+ int state = READ_ONCE(sk->sk_state);
+
+ if (state == TCP_CLOSE)
+ mask |= EPOLLHUP;
+ /* connection hasn't started yet? */
+ if (state == TCP_SYN_SENT)
+ return mask;
+ }
+
+ /* writable? */
+ if (sock_writeable(sk))
+ mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND;
+ else
+ sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
+
+ return mask;
+}
+EXPORT_SYMBOL(datagram_poll);
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-01 23:24:02 +0000