Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1833 insertions, 0 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
new file mode 100644
index 000000000..6fd1a4b61
--- /dev/null
+++ b/net/ipv6/ip6_output.c
@@ -0,0 +1,1833 @@
+/*
+ *	IPv6 output functions
+ *	Linux INET6 implementation
+ *
+ *	Authors:
+ *	Pedro Roque		<roque@di.fc.ul.pt>
+ *
+ *	Based on linux/net/ipv4/ip_output.c
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ *
+ *	Changes:
+ *	A.N.Kuznetsov	:	airthmetics in fragmentation.
+ *				extension headers are implemented.
+ *				route changes now work.
+ *				ip6_forward does not confuse sniffers.
+ *				etc.
+ *
+ *      H. von Brand    :       Added missing #include <linux/string.h>
+ *	Imran Patel	:	frag id should be in NBO
+ *      Kazunori MIYAZAWA @USAGI
+ *			:       add ip6_append_data and related functions
+ *				for datagram xmit
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/socket.h>
+#include <linux/net.h>
+#include <linux/netdevice.h>
+#include <linux/if_arp.h>
+#include <linux/in6.h>
+#include <linux/tcp.h>
+#include <linux/route.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include <linux/bpf-cgroup.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv6.h>
+
+#include <net/sock.h>
+#include <net/snmp.h>
+
+#include <net/ipv6.h>
+#include <net/ndisc.h>
+#include <net/protocol.h>
+#include <net/ip6_route.h>
+#include <net/addrconf.h>
+#include <net/rawv6.h>
+#include <net/icmp.h>
+#include <net/xfrm.h>
+#include <net/checksum.h>
+#include <linux/mroute6.h>
+#include <net/l3mdev.h>
+#include <net/lwtunnel.h>
+
+static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	struct dst_entry *dst = skb_dst(skb);
+	struct net_device *dev = dst->dev;
+	struct neighbour *neigh;
+	struct in6_addr *nexthop;
+	int ret;
+
+	if (ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr)) {
+		struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
+
+		if (!(dev->flags & IFF_LOOPBACK) && sk_mc_loop(sk) &&
+		    ((mroute6_is_socket(net, skb) &&
+		     !(IP6CB(skb)->flags & IP6SKB_FORWARDED)) ||
+		     ipv6_chk_mcast_addr(dev, &ipv6_hdr(skb)->daddr,
+					 &ipv6_hdr(skb)->saddr))) {
+			struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
+
+			/* Do not check for IFF_ALLMULTI; multicast routing
+			   is not supported in any case.
+			 */
+			if (newskb)
+				NF_HOOK(NFPROTO_IPV6, NF_INET_POST_ROUTING,
+					net, sk, newskb, NULL, newskb->dev,
+					dev_loopback_xmit);
+
+			if (ipv6_hdr(skb)->hop_limit == 0) {
+				IP6_INC_STATS(net, idev,
+					      IPSTATS_MIB_OUTDISCARDS);
+				kfree_skb(skb);
+				return 0;
+			}
+		}
+
+		IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUTMCAST, skb->len);
+
+		if (IPV6_ADDR_MC_SCOPE(&ipv6_hdr(skb)->daddr) <=
+		    IPV6_ADDR_SCOPE_NODELOCAL &&
+		    !(dev->flags & IFF_LOOPBACK)) {
+			kfree_skb(skb);
+			return 0;
+		}
+	}
+
+	if (lwtunnel_xmit_redirect(dst->lwtstate)) {
+		int res = lwtunnel_xmit(skb);
+
+		if (res < 0 || res == LWTUNNEL_XMIT_DONE)
+			return res;
+	}
+
+	rcu_read_lock_bh();
+	nexthop = rt6_nexthop((struct rt6_info *)dst, &ipv6_hdr(skb)->daddr);
+	neigh = __ipv6_neigh_lookup_noref(dst->dev, nexthop);
+	if (unlikely(!neigh))
+		neigh = __neigh_create(&nd_tbl, nexthop, dst->dev, false);
+	if (!IS_ERR(neigh)) {
+		sock_confirm_neigh(skb, neigh);
+		ret = neigh_output(neigh, skb);
+		rcu_read_unlock_bh();
+		return ret;
+	}
+	rcu_read_unlock_bh();
+
+	IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
+	kfree_skb(skb);
+	return -EINVAL;
+}
+
+static int
+ip6_finish_output_gso_slowpath_drop(struct net *net, struct sock *sk,
+				    struct sk_buff *skb, unsigned int mtu)
+{
+	struct sk_buff *segs, *nskb;
+	netdev_features_t features;
+	int ret = 0;
+
+	/* Please see corresponding comment in ip_finish_output_gso
+	 * describing the cases where GSO segment length exceeds the
+	 * egress MTU.
+	 */
+	features = netif_skb_features(skb);
+	segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
+	if (IS_ERR_OR_NULL(segs)) {
+		kfree_skb(skb);
+		return -ENOMEM;
+	}
+
+	consume_skb(skb);
+
+	skb_list_walk_safe(segs, segs, nskb) {
+		int err;
+
+		skb_mark_not_on_list(segs);
+		err = ip6_fragment(net, sk, segs, ip6_finish_output2);
+		if (err && ret == 0)
+			ret = err;
+	}
+
+	return ret;
+}
+
+static int ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	unsigned int mtu;
+	int ret;
+
+	ret = BPF_CGROUP_RUN_PROG_INET_EGRESS(sk, skb);
+	if (ret) {
+		kfree_skb(skb);
+		return ret;
+	}
+
+#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
+	/* Policy lookup after SNAT yielded a new policy */
+	if (skb_dst(skb)->xfrm) {
+		IP6CB(skb)->flags |= IP6SKB_REROUTED;
+		return dst_output(net, sk, skb);
+	}
+#endif
+
+	mtu = ip6_skb_dst_mtu(skb);
+	if (skb_is_gso(skb) && !skb_gso_validate_network_len(skb, mtu))
+		return ip6_finish_output_gso_slowpath_drop(net, sk, skb, mtu);
+
+	if ((skb->len > mtu && !skb_is_gso(skb)) ||
+	    dst_allfrag(skb_dst(skb)) ||
+	    (IP6CB(skb)->frag_max_size && skb->len > IP6CB(skb)->frag_max_size))
+		return ip6_fragment(net, sk, skb, ip6_finish_output2);
+	else
+		return ip6_finish_output2(net, sk, skb);
+}
+
+int ip6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+	struct net_device *dev = skb_dst(skb)->dev;
+	struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
+
+	skb->protocol = htons(ETH_P_IPV6);
+	skb->dev = dev;
+
+	if (unlikely(idev->cnf.disable_ipv6)) {
+		IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS);
+		kfree_skb(skb);
+		return 0;
+	}
+
+	return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING,
+			    net, sk, skb, NULL, dev,
+			    ip6_finish_output,
+			    !(IP6CB(skb)->flags & IP6SKB_REROUTED));
+}
+
+bool ip6_autoflowlabel(struct net *net, const struct ipv6_pinfo *np)
+{
+	if (!np->autoflowlabel_set)
+		return ip6_default_np_autolabel(net);
+	else
+		return np->autoflowlabel;
+}
+
+/*
+ * xmit an sk_buff (used by TCP, SCTP and DCCP)
+ * Note : socket lock is not held for SYNACK packets, but might be modified
+ * by calls to skb_set_owner_w() and ipv6_local_error(),
+ * which are using proper atomic operations or spinlocks.
+ */
+int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6,
+	     __u32 mark, struct ipv6_txoptions *opt, int tclass)
+{
+	struct net *net = sock_net(sk);
+	const struct ipv6_pinfo *np = inet6_sk(sk);
+	struct in6_addr *first_hop = &fl6->daddr;
+	struct dst_entry *dst = skb_dst(skb);
+	unsigned int head_room;
+	struct ipv6hdr *hdr;
+	u8  proto = fl6->flowi6_proto;
+	int seg_len = skb->len;
+	int hlimit = -1;
+	u32 mtu;
+
+	head_room = sizeof(struct ipv6hdr) + LL_RESERVED_SPACE(dst->dev);
+	if (opt)
+		head_room += opt->opt_nflen + opt->opt_flen;
+
+	if (unlikely(skb_headroom(skb) < head_room)) {
+		struct sk_buff *skb2 = skb_realloc_headroom(skb, head_room);
+		if (!skb2) {
+			IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
+				      IPSTATS_MIB_OUTDISCARDS);
+			kfree_skb(skb);
+			return -ENOBUFS;
+		}
+		if (skb->sk)
+			skb_set_owner_w(skb2, skb->sk);
+		consume_skb(skb);
+		skb = skb2;
+	}
+
+	if (opt) {
+		seg_len += opt->opt_nflen + opt->opt_flen;
+
+		if (opt->opt_flen)
+			ipv6_push_frag_opts(skb, opt, &proto);
+
+		if (opt->opt_nflen)
+			ipv6_push_nfrag_opts(skb, opt, &proto, &first_hop,
+					     &fl6->saddr);
+	}
+
+	skb_push(skb, sizeof(struct ipv6hdr));
+	skb_reset_network_header(skb);
+	hdr = ipv6_hdr(skb);
+
+	/*
+	 *	Fill in the IPv6 header
+	 */
+	if (np)
+		hlimit = np->hop_limit;
+	if (hlimit < 0)
+		hlimit = ip6_dst_hoplimit(dst);
+
+	ip6_flow_hdr(hdr, tclass, ip6_make_flowlabel(net, skb, fl6->flowlabel,
+				ip6_autoflowlabel(net, np), fl6));
+
+	hdr->payload_len = htons(seg_len);
+	hdr->nexthdr = proto;
+	hdr->hop_limit = hlimit;
+
+	hdr->saddr = fl6->saddr;
+	hdr->daddr = *first_hop;
+
+	skb->protocol = htons(ETH_P_IPV6);
+	skb->priority = sk->sk_priority;
+	skb->mark = mark;
+
+	mtu = dst_mtu(dst);
+	if ((skb->len <= mtu) || skb->ignore_df || skb_is_gso(skb)) {
+		IP6_UPD_PO_STATS(net, ip6_dst_idev(skb_dst(skb)),
+			      IPSTATS_MIB_OUT, skb->len);
+
+		/* if egress device is enslaved to an L3 master device pass the
+		 * skb to its handler for processing
+		 */
+		skb = l3mdev_ip6_out((struct sock *)sk, skb);
+		if (unlikely(!skb))
+			return 0;
+
+		/* hooks should never assume socket lock is held.
+		 * we promote our socket to non const
+		 */
+		return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT,
+			       net, (struct sock *)sk, skb, NULL, dst->dev,
+			       dst_output);
+	}
+
+	skb->dev = dst->dev;
+	/* ipv6_local_error() does not require socket lock,
+	 * we promote our socket to non const
+	 */
+	ipv6_local_error((struct sock *)sk, EMSGSIZE, fl6, mtu);
+
+	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_FRAGFAILS);
+	kfree_skb(skb);
+	return -EMSGSIZE;
+}
+EXPORT_SYMBOL(ip6_xmit);
+
+static int ip6_call_ra_chain(struct sk_buff *skb, int sel)
+{
+	struct ip6_ra_chain *ra;
+	struct sock *last = NULL;
+
+	read_lock(&ip6_ra_lock);
+	for (ra = ip6_ra_chain; ra; ra = ra->next) {
+		struct sock *sk = ra->sk;
+		if (sk && ra->sel == sel &&
+		    (!sk->sk_bound_dev_if ||
+		     sk->sk_bound_dev_if == skb->dev->ifindex)) {
+			if (last) {
+				struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);
+				if (skb2)
+					rawv6_rcv(last, skb2);
+			}
+			last = sk;
+		}
+	}
+
+	if (last) {
+		rawv6_rcv(last, skb);
+		read_unlock(&ip6_ra_lock);
+		return 1;
+	}
+	read_unlock(&ip6_ra_lock);
+	return 0;
+}
+
+static int ip6_forward_proxy_check(struct sk_buff *skb)
+{
+	struct ipv6hdr *hdr = ipv6_hdr(skb);
+	u8 nexthdr = hdr->nexthdr;
+	__be16 frag_off;
+	int offset;
+
+	if (ipv6_ext_hdr(nexthdr)) {
+		offset = ipv6_skip_exthdr(skb, sizeof(*hdr), &nexthdr, &frag_off);
+		if (offset < 0)
+			return 0;
+	} else
+		offset = sizeof(struct ipv6hdr);
+
+	if (nexthdr == IPPROTO_ICMPV6) {
+		struct icmp6hdr *icmp6;
+
+		if (!pskb_may_pull(skb, (skb_network_header(skb) +
+					 offset + 1 - skb->data)))
+			return 0;
+
+		icmp6 = (struct icmp6hdr *)(skb_network_header(skb) + offset);
+
+		switch (icmp6->icmp6_type) {
+		case NDISC_ROUTER_SOLICITATION:
+		case NDISC_ROUTER_ADVERTISEMENT:
+		case NDISC_NEIGHBOUR_SOLICITATION:
+		case NDISC_NEIGHBOUR_ADVERTISEMENT:
+		case NDISC_REDIRECT:
+			/* For reaction involving unicast neighbor discovery
+			 * message destined to the proxied address, pass it to
+			 * input function.
+			 */
+			return 1;
+		default:
+			break;
+		}
+	}
+
+	/*
+	 * The proxying router can't forward traffic sent to a link-local
+	 * address, so signal the sender and discard the packet. This
+	 * behavior is clarified by the MIPv6 specification.
+	 */
+	if (ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) {
+		dst_link_failure(skb);
+		return -1;
+	}
+
+	return 0;
+}
+
+static inline int ip6_forward_finish(struct net *net, struct sock *sk,
+				     struct sk_buff *skb)
+{
+	struct dst_entry *dst = skb_dst(skb);
+
+	__IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTFORWDATAGRAMS);
+	__IP6_ADD_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTOCTETS, skb->len);
+
+	skb->tstamp = 0;
+	return dst_output(net, sk, skb);
+}
+
+static bool ip6_pkt_too_big(const struct sk_buff *skb, unsigned int mtu)
+{
+	if (skb->len <= mtu)
+		return false;
+
+	/* ipv6 conntrack defrag sets max_frag_size + ignore_df */
+	if (IP6CB(skb)->frag_max_size && IP6CB(skb)->frag_max_size > mtu)
+		return true;
+
+	if (skb->ignore_df)
+		return false;
+
+	if (skb_is_gso(skb) && skb_gso_validate_network_len(skb, mtu))
+		return false;
+
+	return true;
+}
+
+int ip6_forward(struct sk_buff *skb)
+{
+	struct inet6_dev *idev = __in6_dev_get_safely(skb->dev);
+	struct dst_entry *dst = skb_dst(skb);
+	struct ipv6hdr *hdr = ipv6_hdr(skb);
+	struct inet6_skb_parm *opt = IP6CB(skb);
+	struct net *net = dev_net(dst->dev);
+	u32 mtu;
+
+	if (net->ipv6.devconf_all->forwarding == 0)
+		goto error;
+
+	if (skb->pkt_type != PACKET_HOST)
+		goto drop;
+
+	if (unlikely(skb->sk))
+		goto drop;
+
+	if (skb_warn_if_lro(skb))
+		goto drop;
+
+	if (!net->ipv6.devconf_all->disable_policy &&
+	    (!idev || !idev->cnf.disable_policy) &&
+	    !xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
+		__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
+		goto drop;
+	}
+
+	skb_forward_csum(skb);
+
+	/*
+	 *	We DO NOT make any processing on
+	 *	RA packets, pushing them to user level AS IS
+	 *	without ane WARRANTY that application will be able
+	 *	to interpret them. The reason is that we
+	 *	cannot make anything clever here.
+	 *
+	 *	We are not end-node, so that if packet contains
+	 *	AH/ESP, we cannot make anything.
+	 *	Defragmentation also would be mistake, RA packets
+	 *	cannot be fragmented, because there is no warranty
+	 *	that different fragments will go along one path. --ANK
+	 */
+	if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
+		if (ip6_call_ra_chain(skb, ntohs(opt->ra)))
+			return 0;
+	}
+
+	/*
+	 *	check and decrement ttl
+	 */
+	if (hdr->hop_limit <= 1) {
+		/* Force OUTPUT device used as source address */
+		skb->dev = dst->dev;
+		icmpv6_send(skb, ICMPV6_TIME_EXCEED, ICMPV6_EXC_HOPLIMIT, 0);
+		__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
+
+		kfree_skb(skb);
+		return -ETIMEDOUT;
+	}
+
+	/* XXX: idev->cnf.proxy_ndp? */
+	if (net->ipv6.devconf_all->proxy_ndp &&
+	    pneigh_lookup(&nd_tbl, net, &hdr->daddr, skb->dev, 0)) {
+		int proxied = ip6_forward_proxy_check(skb);
+		if (proxied > 0)
+			return ip6_input(skb);
+		else if (proxied < 0) {
+			__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
+			goto drop;
+		}
+	}
+
+	if (!xfrm6_route_forward(skb)) {
+		__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
+		goto drop;
+	}
+	dst = skb_dst(skb);
+
+	/* IPv6 specs say nothing about it, but it is clear that we cannot
+	   send redirects to source routed frames.
+	   We don't send redirects to frames decapsulated from IPsec.
+	 */
+	if (IP6CB(skb)->iif == dst->dev->ifindex &&
+	    opt->srcrt == 0 && !skb_sec_path(skb)) {
+		struct in6_addr *target = NULL;
+		struct inet_peer *peer;
+		struct rt6_info *rt;
+
+		/*
+		 *	incoming and outgoing devices are the same
+		 *	send a redirect.
+		 */
+
+		rt = (struct rt6_info *) dst;
+		if (rt->rt6i_flags & RTF_GATEWAY)
+			target = &rt->rt6i_gateway;
+		else
+			target = &hdr->daddr;
+
+		peer = inet_getpeer_v6(net->ipv6.peers, &hdr->daddr, 1);
+
+		/* Limit redirects both by destination (here)
+		   and by source (inside ndisc_send_redirect)
+		 */
+		if (inet_peer_xrlim_allow(peer, 1*HZ))
+			ndisc_send_redirect(skb, target);
+		if (peer)
+			inet_putpeer(peer);
+	} else {
+		int addrtype = ipv6_addr_type(&hdr->saddr);
+
+		/* This check is security critical. */
+		if (addrtype == IPV6_ADDR_ANY ||
+		    addrtype & (IPV6_ADDR_MULTICAST | IPV6_ADDR_LOOPBACK))
+			goto error;
+		if (addrtype & IPV6_ADDR_LINKLOCAL) {
+			icmpv6_send(skb, ICMPV6_DEST_UNREACH,
+				    ICMPV6_NOT_NEIGHBOUR, 0);
+			goto error;
+		}
+	}
+
+	mtu = ip6_dst_mtu_forward(dst);
+	if (mtu < IPV6_MIN_MTU)
+		mtu = IPV6_MIN_MTU;
+
+	if (ip6_pkt_too_big(skb, mtu)) {
+		/* Again, force OUTPUT device used as source address */
+		skb->dev = dst->dev;
+		icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
+		__IP6_INC_STATS(net, idev, IPSTATS_MIB_INTOOBIGERRORS);
+		__IP6_INC_STATS(net, ip6_dst_idev(dst),
+				IPSTATS_MIB_FRAGFAILS);
+		kfree_skb(skb);
+		return -EMSGSIZE;
+	}
+
+	if (skb_cow(skb, dst->dev->hard_header_len)) {
+		__IP6_INC_STATS(net, ip6_dst_idev(dst),
+				IPSTATS_MIB_OUTDISCARDS);
+		goto drop;
+	}
+
+	hdr = ipv6_hdr(skb);
+
+	/* Mangling hops number delayed to point after skb COW */
+
+	hdr->hop_limit--;
+
+	return NF_HOOK(NFPROTO_IPV6, NF_INET_FORWARD,
+		       net, NULL, skb, skb->dev, dst->dev,
+		       ip6_forward_finish);
+
+error:
+	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INADDRERRORS);
+drop:
+	kfree_skb(skb);
+	return -EINVAL;
+}
+
+static void ip6_copy_metadata(struct sk_buff *to, struct sk_buff *from)
+{
+	to->pkt_type = from->pkt_type;
+	to->priority = from->priority;
+	to->protocol = from->protocol;
+	skb_dst_drop(to);
+	skb_dst_set(to, dst_clone(skb_dst(from)));
+	to->dev = from->dev;
+	to->mark = from->mark;
+
+	skb_copy_hash(to, from);
+
+#ifdef CONFIG_NET_SCHED
+	to->tc_index = from->tc_index;
+#endif
+	nf_copy(to, from);
+	skb_copy_secmark(to, from);
+}
+
+int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb,
+		 int (*output)(struct net *, struct sock *, struct sk_buff *))
+{
+	struct sk_buff *frag;
+	struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
+	struct ipv6_pinfo *np = skb->sk && !dev_recursion_level() ?
+				inet6_sk(skb->sk) : NULL;
+	struct ipv6hdr *tmp_hdr;
+	struct frag_hdr *fh;
+	unsigned int mtu, hlen, left, len, nexthdr_offset;
+	int hroom, troom;
+	__be32 frag_id;
+	int ptr, offset = 0, err = 0;
+	u8 *prevhdr, nexthdr = 0;
+
+	err = ip6_find_1stfragopt(skb, &prevhdr);
+	if (err < 0)
+		goto fail;
+	hlen = err;
+	nexthdr = *prevhdr;
+	nexthdr_offset = prevhdr - skb_network_header(skb);
+
+	mtu = ip6_skb_dst_mtu(skb);
+
+	/* We must not fragment if the socket is set to force MTU discovery
+	 * or if the skb it not generated by a local socket.
+	 */
+	if (unlikely(!skb->ignore_df && skb->len > mtu))
+		goto fail_toobig;
+
+	if (IP6CB(skb)->frag_max_size) {
+		if (IP6CB(skb)->frag_max_size > mtu)
+			goto fail_toobig;
+
+		/* don't send fragments larger than what we received */
+		mtu = IP6CB(skb)->frag_max_size;
+		if (mtu < IPV6_MIN_MTU)
+			mtu = IPV6_MIN_MTU;
+	}
+
+	if (np && np->frag_size < mtu) {
+		if (np->frag_size)
+			mtu = np->frag_size;
+	}
+	if (mtu < hlen + sizeof(struct frag_hdr) + 8)
+		goto fail_toobig;
+	mtu -= hlen + sizeof(struct frag_hdr);
+
+	frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr,
+				    &ipv6_hdr(skb)->saddr);
+
+	if (skb->ip_summed == CHECKSUM_PARTIAL &&
+	    (err = skb_checksum_help(skb)))
+		goto fail;
+
+	prevhdr = skb_network_header(skb) + nexthdr_offset;
+	hroom = LL_RESERVED_SPACE(rt->dst.dev);
+	if (skb_has_frag_list(skb)) {
+		unsigned int first_len = skb_pagelen(skb);
+		struct sk_buff *frag2;
+
+		if (first_len - hlen > mtu ||
+		    ((first_len - hlen) & 7) ||
+		    skb_cloned(skb) ||
+		    skb_headroom(skb) < (hroom + sizeof(struct frag_hdr)))
+			goto slow_path;
+
+		skb_walk_frags(skb, frag) {
+			/* Correct geometry. */
+			if (frag->len > mtu ||
+			    ((frag->len & 7) && frag->next) ||
+			    skb_headroom(frag) < (hlen + hroom + sizeof(struct frag_hdr)))
+				goto slow_path_clean;
+
+			/* Partially cloned skb? */
+			if (skb_shared(frag))
+				goto slow_path_clean;
+
+			BUG_ON(frag->sk);
+			if (skb->sk) {
+				frag->sk = skb->sk;
+				frag->destructor = sock_wfree;
+			}
+			skb->truesize -= frag->truesize;
+		}
+
+		err = 0;
+		offset = 0;
+		/* BUILD HEADER */
+
+		*prevhdr = NEXTHDR_FRAGMENT;
+		tmp_hdr = kmemdup(skb_network_header(skb), hlen, GFP_ATOMIC);
+		if (!tmp_hdr) {
+			err = -ENOMEM;
+			goto fail;
+		}
+		frag = skb_shinfo(skb)->frag_list;
+		skb_frag_list_init(skb);
+
+		__skb_pull(skb, hlen);
+		fh = __skb_push(skb, sizeof(struct frag_hdr));
+		__skb_push(skb, hlen);
+		skb_reset_network_header(skb);
+		memcpy(skb_network_header(skb), tmp_hdr, hlen);
+
+		fh->nexthdr = nexthdr;
+		fh->reserved = 0;
+		fh->frag_off = htons(IP6_MF);
+		fh->identification = frag_id;
+
+		first_len = skb_pagelen(skb);
+		skb->data_len = first_len - skb_headlen(skb);
+		skb->len = first_len;
+		ipv6_hdr(skb)->payload_len = htons(first_len -
+						   sizeof(struct ipv6hdr));
+
+		for (;;) {
+			/* Prepare header of the next frame,
+			 * before previous one went down. */
+			if (frag) {
+				frag->ip_summed = CHECKSUM_NONE;
+				skb_reset_transport_header(frag);
+				fh = __skb_push(frag, sizeof(struct frag_hdr));
+				__skb_push(frag, hlen);
+				skb_reset_network_header(frag);
+				memcpy(skb_network_header(frag), tmp_hdr,
+				       hlen);
+				offset += skb->len - hlen - sizeof(struct frag_hdr);
+				fh->nexthdr = nexthdr;
+				fh->reserved = 0;
+				fh->frag_off = htons(offset);
+				if (frag->next)
+					fh->frag_off |= htons(IP6_MF);
+				fh->identification = frag_id;
+				ipv6_hdr(frag)->payload_len =
+						htons(frag->len -
+						      sizeof(struct ipv6hdr));
+				ip6_copy_metadata(frag, skb);
+			}
+
+			err = output(net, sk, skb);
+			if (!err)
+				IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
+					      IPSTATS_MIB_FRAGCREATES);
+
+			if (err || !frag)
+				break;
+
+			skb = frag;
+			frag = skb->next;
+			skb->next = NULL;
+		}
+
+		kfree(tmp_hdr);
+
+		if (err == 0) {
+			IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
+				      IPSTATS_MIB_FRAGOKS);
+			return 0;
+		}
+
+		kfree_skb_list(frag);
+
+		IP6_INC_STATS(net, ip6_dst_idev(&rt->dst),
+			      IPSTATS_MIB_FRAGFAILS);
+		return err;
+
+slow_path_clean:
+		skb_walk_frags(skb, frag2) {
+			if (frag2 == frag)
+				break;
+			frag2->sk = NULL;
+			frag2->destructor = NULL;
+			skb->truesize += frag2->truesize;
+		}
+	}
+
+slow_path:
+	left = skb->len - hlen;		/* Space per frame */
+	ptr = hlen;			/* Where to start from */
+
+	/*
+	 *	Fragment the datagram.
+	 */
+
+	troom = rt->dst.dev->needed_tailroom;
+
+	/*
+	 *	Keep copying data until we run out.
+	 */
+	while (left > 0)	{
+		u8 *fragnexthdr_offset;
+
+		len = left;
+		/* IF: it doesn't fit, use 'mtu' - the data space left */
+		if (len > mtu)
+			len = mtu;
+		/* IF: we are not sending up to and including the packet end
+		   then align the next start on an eight byte boundary */
+		if (len < left)	{
+			len &= ~7;
+		}
+
+		/* Allocate buffer */
+		frag = alloc_skb(len + hlen + sizeof(struct frag_hdr) +
+				 hroom + troom, GFP_ATOMIC);
+		if (!frag) {
+			err = -ENOMEM;
+			goto fail;
+		}
+
+		/*
+		 *	Set up data on packet
+		 */
+
+		ip6_copy_metadata(frag, skb);
+		skb_reserve(frag, hroom);
+		skb_put(frag, len + hlen + sizeof(struct frag_hdr));
+		skb_reset_network_header(frag);
+		fh = (struct frag_hdr *)(skb_network_header(frag) + hlen);
+		frag->transport_header = (frag->network_header + hlen +
+					  sizeof(struct frag_hdr));
+
+		/*
+		 *	Charge the memory for the fragment to any owner
+		 *	it might possess
+		 */
+		if (skb->sk)
+			skb_set_owner_w(frag, skb->sk);
+
+		/*
+		 *	Copy the packet header into the new buffer.
+		 */
+		skb_copy_from_linear_data(skb, skb_network_header(frag), hlen);
+
+		fragnexthdr_offset = skb_network_header(frag);
+		fragnexthdr_offset += prevhdr - skb_network_header(skb);
+		*fragnexthdr_offset = NEXTHDR_FRAGMENT;
+
+		/*
+		 *	Build fragment header.
+		 */
+		fh->nexthdr = nexthdr;
+		fh->reserved = 0;
+		fh->identification = frag_id;
+
+		/*
+		 *	Copy a block of the IP datagram.
+		 */
+		BUG_ON(skb_copy_bits(skb, ptr, skb_transport_header(frag),
+				     len));
+		left -= len;
+
+		fh->frag_off = htons(offset);
+		if (left > 0)
+			fh->frag_off |= htons(IP6_MF);
+		ipv6_hdr(frag)->payload_len = htons(frag->len -
+						    sizeof(struct ipv6hdr));
+
+		ptr += len;
+		offset += len;
+
+		/*
+		 *	Put this fragment into the sending queue.
+		 */
+		err = output(net, sk, frag);
+		if (err)
+			goto fail;
+
+		IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
+			      IPSTATS_MIB_FRAGCREATES);
+	}
+	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
+		      IPSTATS_MIB_FRAGOKS);
+	consume_skb(skb);
+	return err;
+
+fail_toobig:
+	if (skb->sk && dst_allfrag(skb_dst(skb)))
+		sk_nocaps_add(skb->sk, NETIF_F_GSO_MASK);
+
+	icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
+	err = -EMSGSIZE;
+
+fail:
+	IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)),
+		      IPSTATS_MIB_FRAGFAILS);
+	kfree_skb(skb);
+	return err;
+}
+
+static inline int ip6_rt_check(const struct rt6key *rt_key,
+			       const struct in6_addr *fl_addr,
+			       const struct in6_addr *addr_cache)
+{
+	return (rt_key->plen != 128 || !ipv6_addr_equal(fl_addr, &rt_key->addr)) &&
+		(!addr_cache || !ipv6_addr_equal(fl_addr, addr_cache));
+}
+
+static struct dst_entry *ip6_sk_dst_check(struct sock *sk,
+					  struct dst_entry *dst,
+					  const struct flowi6 *fl6)
+{
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	struct rt6_info *rt;
+
+	if (!dst)
+		goto out;
+
+	if (dst->ops->family != AF_INET6) {
+		dst_release(dst);
+		return NULL;
+	}
+
+	rt = (struct rt6_info *)dst;
+	/* Yes, checking route validity in not connected
+	 * case is not very simple. Take into account,
+	 * that we do not support routing by source, TOS,
+	 * and MSG_DONTROUTE		--ANK (980726)
+	 *
+	 * 1. ip6_rt_check(): If route was host route,
+	 *    check that cached destination is current.
+	 *    If it is network route, we still may
+	 *    check its validity using saved pointer
+	 *    to the last used address: daddr_cache.
+	 *    We do not want to save whole address now,
+	 *    (because main consumer of this service
+	 *    is tcp, which has not this problem),
+	 *    so that the last trick works only on connected
+	 *    sockets.
+	 * 2. oif also should be the same.
+	 */
+	if (ip6_rt_check(&rt->rt6i_dst, &fl6->daddr, np->daddr_cache) ||
+#ifdef CONFIG_IPV6_SUBTREES
+	    ip6_rt_check(&rt->rt6i_src, &fl6->saddr, np->saddr_cache) ||
+#endif
+	   (!(fl6->flowi6_flags & FLOWI_FLAG_SKIP_NH_OIF) &&
+	      (fl6->flowi6_oif && fl6->flowi6_oif != dst->dev->ifindex))) {
+		dst_release(dst);
+		dst = NULL;
+	}
+
+out:
+	return dst;
+}
+
+static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk,
+			       struct dst_entry **dst, struct flowi6 *fl6)
+{
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+	struct neighbour *n;
+	struct rt6_info *rt;
+#endif
+	int err;
+	int flags = 0;
+
+	/* The correct way to handle this would be to do
+	 * ip6_route_get_saddr, and then ip6_route_output; however,
+	 * the route-specific preferred source forces the
+	 * ip6_route_output call _before_ ip6_route_get_saddr.
+	 *
+	 * In source specific routing (no src=any default route),
+	 * ip6_route_output will fail given src=any saddr, though, so
+	 * that's why we try it again later.
+	 */
+	if (ipv6_addr_any(&fl6->saddr) && (!*dst || !(*dst)->error)) {
+		struct fib6_info *from;
+		struct rt6_info *rt;
+		bool had_dst = *dst != NULL;
+
+		if (!had_dst)
+			*dst = ip6_route_output(net, sk, fl6);
+		rt = (*dst)->error ? NULL : (struct rt6_info *)*dst;
+
+		rcu_read_lock();
+		from = rt ? rcu_dereference(rt->from) : NULL;
+		err = ip6_route_get_saddr(net, from, &fl6->daddr,
+					  sk ? inet6_sk(sk)->srcprefs : 0,
+					  &fl6->saddr);
+		rcu_read_unlock();
+
+		if (err)
+			goto out_err_release;
+
+		/* If we had an erroneous initial result, pretend it
+		 * never existed and let the SA-enabled version take
+		 * over.
+		 */
+		if (!had_dst && (*dst)->error) {
+			dst_release(*dst);
+			*dst = NULL;
+		}
+
+		if (fl6->flowi6_oif)
+			flags |= RT6_LOOKUP_F_IFACE;
+	}
+
+	if (!*dst)
+		*dst = ip6_route_output_flags(net, sk, fl6, flags);
+
+	err = (*dst)->error;
+	if (err)
+		goto out_err_release;
+
+#ifdef CONFIG_IPV6_OPTIMISTIC_DAD
+	/*
+	 * Here if the dst entry we've looked up
+	 * has a neighbour entry that is in the INCOMPLETE
+	 * state and the src address from the flow is
+	 * marked as OPTIMISTIC, we release the found
+	 * dst entry and replace it instead with the
+	 * dst entry of the nexthop router
+	 */
+	rt = (struct rt6_info *) *dst;
+	rcu_read_lock_bh();
+	n = __ipv6_neigh_lookup_noref(rt->dst.dev,
+				      rt6_nexthop(rt, &fl6->daddr));
+	err = n && !(n->nud_state & NUD_VALID) ? -EINVAL : 0;
+	rcu_read_unlock_bh();
+
+	if (err) {
+		struct inet6_ifaddr *ifp;
+		struct flowi6 fl_gw6;
+		int redirect;
+
+		ifp = ipv6_get_ifaddr(net, &fl6->saddr,
+				      (*dst)->dev, 1);
+
+		redirect = (ifp && ifp->flags & IFA_F_OPTIMISTIC);
+		if (ifp)
+			in6_ifa_put(ifp);
+
+		if (redirect) {
+			/*
+			 * We need to get the dst entry for the
+			 * default router instead
+			 */
+			dst_release(*dst);
+			memcpy(&fl_gw6, fl6, sizeof(struct flowi6));
+			memset(&fl_gw6.daddr, 0, sizeof(struct in6_addr));
+			*dst = ip6_route_output(net, sk, &fl_gw6);
+			err = (*dst)->error;
+			if (err)
+				goto out_err_release;
+		}
+	}
+#endif
+	if (ipv6_addr_v4mapped(&fl6->saddr) &&
+	    !(ipv6_addr_v4mapped(&fl6->daddr) || ipv6_addr_any(&fl6->daddr))) {
+		err = -EAFNOSUPPORT;
+		goto out_err_release;
+	}
+
+	return 0;
+
+out_err_release:
+	dst_release(*dst);
+	*dst = NULL;
+
+	if (err == -ENETUNREACH)
+		IP6_INC_STATS(net, NULL, IPSTATS_MIB_OUTNOROUTES);
+	return err;
+}
+
+/**
+ *	ip6_dst_lookup - perform route lookup on flow
+ *	@sk: socket which provides route info
+ *	@dst: pointer to dst_entry * for result
+ *	@fl6: flow to lookup
+ *
+ *	This function performs a route lookup on the given flow.
+ *
+ *	It returns zero on success, or a standard errno code on error.
+ */
+int ip6_dst_lookup(struct net *net, struct sock *sk, struct dst_entry **dst,
+		   struct flowi6 *fl6)
+{
+	*dst = NULL;
+	return ip6_dst_lookup_tail(net, sk, dst, fl6);
+}
+EXPORT_SYMBOL_GPL(ip6_dst_lookup);
+
+/**
+ *	ip6_dst_lookup_flow - perform route lookup on flow with ipsec
+ *	@sk: socket which provides route info
+ *	@fl6: flow to lookup
+ *	@final_dst: final destination address for ipsec lookup
+ *
+ *	This function performs a route lookup on the given flow.
+ *
+ *	It returns a valid dst pointer on success, or a pointer encoded
+ *	error code.
+ */
+struct dst_entry *ip6_dst_lookup_flow(struct net *net, const struct sock *sk, struct flowi6 *fl6,
+				      const struct in6_addr *final_dst)
+{
+	struct dst_entry *dst = NULL;
+	int err;
+
+	err = ip6_dst_lookup_tail(net, sk, &dst, fl6);
+	if (err)
+		return ERR_PTR(err);
+	if (final_dst)
+		fl6->daddr = *final_dst;
+
+	return xfrm_lookup_route(net, dst, flowi6_to_flowi(fl6), sk, 0);
+}
+EXPORT_SYMBOL_GPL(ip6_dst_lookup_flow);
+
+/**
+ *	ip6_sk_dst_lookup_flow - perform socket cached route lookup on flow
+ *	@sk: socket which provides the dst cache and route info
+ *	@fl6: flow to lookup
+ *	@final_dst: final destination address for ipsec lookup
+ *	@connected: whether @sk is connected or not
+ *
+ *	This function performs a route lookup on the given flow with the
+ *	possibility of using the cached route in the socket if it is valid.
+ *	It will take the socket dst lock when operating on the dst cache.
+ *	As a result, this function can only be used in process context.
+ *
+ *	In addition, for a connected socket, cache the dst in the socket
+ *	if the current cache is not valid.
+ *
+ *	It returns a valid dst pointer on success, or a pointer encoded
+ *	error code.
+ */
+struct dst_entry *ip6_sk_dst_lookup_flow(struct sock *sk, struct flowi6 *fl6,
+					 const struct in6_addr *final_dst,
+					 bool connected)
+{
+	struct dst_entry *dst = sk_dst_check(sk, inet6_sk(sk)->dst_cookie);
+
+	dst = ip6_sk_dst_check(sk, dst, fl6);
+	if (dst)
+		return dst;
+
+	dst = ip6_dst_lookup_flow(sock_net(sk), sk, fl6, final_dst);
+	if (connected && !IS_ERR(dst))
+		ip6_sk_dst_store_flow(sk, dst_clone(dst), fl6);
+
+	return dst;
+}
+EXPORT_SYMBOL_GPL(ip6_sk_dst_lookup_flow);
+
+static inline struct ipv6_opt_hdr *ip6_opt_dup(struct ipv6_opt_hdr *src,
+					       gfp_t gfp)
+{
+	return src ? kmemdup(src, (src->hdrlen + 1) * 8, gfp) : NULL;
+}
+
+static inline struct ipv6_rt_hdr *ip6_rthdr_dup(struct ipv6_rt_hdr *src,
+						gfp_t gfp)
+{
+	return src ? kmemdup(src, (src->hdrlen + 1) * 8, gfp) : NULL;
+}
+
+static void ip6_append_data_mtu(unsigned int *mtu,
+				int *maxfraglen,
+				unsigned int fragheaderlen,
+				struct sk_buff *skb,
+				struct rt6_info *rt,
+				unsigned int orig_mtu)
+{
+	if (!(rt->dst.flags & DST_XFRM_TUNNEL)) {
+		if (!skb) {
+			/* first fragment, reserve header_len */
+			*mtu = orig_mtu - rt->dst.header_len;
+
+		} else {
+			/*
+			 * this fragment is not first, the headers
+			 * space is regarded as data space.
+			 */
+			*mtu = orig_mtu;
+		}
+		*maxfraglen = ((*mtu - fragheaderlen) & ~7)
+			      + fragheaderlen - sizeof(struct frag_hdr);
+	}
+}
+
+static int ip6_setup_cork(struct sock *sk, struct inet_cork_full *cork,
+			  struct inet6_cork *v6_cork, struct ipcm6_cookie *ipc6,
+			  struct rt6_info *rt, struct flowi6 *fl6)
+{
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	unsigned int mtu;
+	struct ipv6_txoptions *opt = ipc6->opt;
+
+	/*
+	 * setup for corking
+	 */
+	if (opt) {
+		if (WARN_ON(v6_cork->opt))
+			return -EINVAL;
+
+		v6_cork->opt = kzalloc(sizeof(*opt), sk->sk_allocation);
+		if (unlikely(!v6_cork->opt))
+			return -ENOBUFS;
+
+		v6_cork->opt->tot_len = sizeof(*opt);
+		v6_cork->opt->opt_flen = opt->opt_flen;
+		v6_cork->opt->opt_nflen = opt->opt_nflen;
+
+		v6_cork->opt->dst0opt = ip6_opt_dup(opt->dst0opt,
+						    sk->sk_allocation);
+		if (opt->dst0opt && !v6_cork->opt->dst0opt)
+			return -ENOBUFS;
+
+		v6_cork->opt->dst1opt = ip6_opt_dup(opt->dst1opt,
+						    sk->sk_allocation);
+		if (opt->dst1opt && !v6_cork->opt->dst1opt)
+			return -ENOBUFS;
+
+		v6_cork->opt->hopopt = ip6_opt_dup(opt->hopopt,
+						   sk->sk_allocation);
+		if (opt->hopopt && !v6_cork->opt->hopopt)
+			return -ENOBUFS;
+
+		v6_cork->opt->srcrt = ip6_rthdr_dup(opt->srcrt,
+						    sk->sk_allocation);
+		if (opt->srcrt && !v6_cork->opt->srcrt)
+			return -ENOBUFS;
+
+		/* need source address above miyazawa*/
+	}
+	dst_hold(&rt->dst);
+	cork->base.dst = &rt->dst;
+	cork->fl.u.ip6 = *fl6;
+	v6_cork->hop_limit = ipc6->hlimit;
+	v6_cork->tclass = ipc6->tclass;
+	if (rt->dst.flags & DST_XFRM_TUNNEL)
+		mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
+		      READ_ONCE(rt->dst.dev->mtu) : dst_mtu(&rt->dst);
+	else
+		mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ?
+			READ_ONCE(rt->dst.dev->mtu) : dst_mtu(xfrm_dst_path(&rt->dst));
+	if (np->frag_size < mtu) {
+		if (np->frag_size)
+			mtu = np->frag_size;
+	}
+	cork->base.fragsize = mtu;
+	cork->base.gso_size = ipc6->gso_size;
+	cork->base.tx_flags = 0;
+	sock_tx_timestamp(sk, ipc6->sockc.tsflags, &cork->base.tx_flags);
+
+	if (dst_allfrag(xfrm_dst_path(&rt->dst)))
+		cork->base.flags |= IPCORK_ALLFRAG;
+	cork->base.length = 0;
+
+	cork->base.transmit_time = ipc6->sockc.transmit_time;
+
+	return 0;
+}
+
+static int __ip6_append_data(struct sock *sk,
+			     struct flowi6 *fl6,
+			     struct sk_buff_head *queue,
+			     struct inet_cork *cork,
+			     struct inet6_cork *v6_cork,
+			     struct page_frag *pfrag,
+			     int getfrag(void *from, char *to, int offset,
+					 int len, int odd, struct sk_buff *skb),
+			     void *from, int length, int transhdrlen,
+			     unsigned int flags, struct ipcm6_cookie *ipc6)
+{
+	struct sk_buff *skb, *skb_prev = NULL;
+	unsigned int maxfraglen, fragheaderlen, mtu, orig_mtu, pmtu;
+	int exthdrlen = 0;
+	int dst_exthdrlen = 0;
+	int hh_len;
+	int copy;
+	int err;
+	int offset = 0;
+	u32 tskey = 0;
+	struct rt6_info *rt = (struct rt6_info *)cork->dst;
+	struct ipv6_txoptions *opt = v6_cork->opt;
+	int csummode = CHECKSUM_NONE;
+	unsigned int maxnonfragsize, headersize;
+	unsigned int wmem_alloc_delta = 0;
+	bool paged;
+
+	skb = skb_peek_tail(queue);
+	if (!skb) {
+		exthdrlen = opt ? opt->opt_flen : 0;
+		dst_exthdrlen = rt->dst.header_len - rt->rt6i_nfheader_len;
+	}
+
+	paged = !!cork->gso_size;
+	mtu = cork->gso_size ? IP6_MAX_MTU : cork->fragsize;
+	orig_mtu = mtu;
+
+	if (cork->tx_flags & SKBTX_ANY_SW_TSTAMP &&
+	    sk->sk_tsflags & SOF_TIMESTAMPING_OPT_ID)
+		tskey = sk->sk_tskey++;
+
+	hh_len = LL_RESERVED_SPACE(rt->dst.dev);
+
+	fragheaderlen = sizeof(struct ipv6hdr) + rt->rt6i_nfheader_len +
+			(opt ? opt->opt_nflen : 0);
+
+	headersize = sizeof(struct ipv6hdr) +
+		     (opt ? opt->opt_flen + opt->opt_nflen : 0) +
+		     (dst_allfrag(&rt->dst) ?
+		      sizeof(struct frag_hdr) : 0) +
+		     rt->rt6i_nfheader_len;
+
+	if (mtu <= fragheaderlen ||
+	    ((mtu - fragheaderlen) & ~7) + fragheaderlen <= sizeof(struct frag_hdr))
+		goto emsgsize;
+
+	maxfraglen = ((mtu - fragheaderlen) & ~7) + fragheaderlen -
+		     sizeof(struct frag_hdr);
+
+	/* as per RFC 7112 section 5, the entire IPv6 Header Chain must fit
+	 * the first fragment
+	 */
+	if (headersize + transhdrlen > mtu)
+		goto emsgsize;
+
+	if (cork->length + length > mtu - headersize && ipc6->dontfrag &&
+	    (sk->sk_protocol == IPPROTO_UDP ||
+	     sk->sk_protocol == IPPROTO_RAW)) {
+		ipv6_local_rxpmtu(sk, fl6, mtu - headersize +
+				sizeof(struct ipv6hdr));
+		goto emsgsize;
+	}
+
+	if (ip6_sk_ignore_df(sk))
+		maxnonfragsize = sizeof(struct ipv6hdr) + IPV6_MAXPLEN;
+	else
+		maxnonfragsize = mtu;
+
+	if (cork->length + length > maxnonfragsize - headersize) {
+emsgsize:
+		pmtu = max_t(int, mtu - headersize + sizeof(struct ipv6hdr), 0);
+		ipv6_local_error(sk, EMSGSIZE, fl6, pmtu);
+		return -EMSGSIZE;
+	}
+
+	/* CHECKSUM_PARTIAL only with no extension headers and when
+	 * we are not going to fragment
+	 */
+	if (transhdrlen && sk->sk_protocol == IPPROTO_UDP &&
+	    headersize == sizeof(struct ipv6hdr) &&
+	    length <= mtu - headersize &&
+	    (!(flags & MSG_MORE) || cork->gso_size) &&
+	    rt->dst.dev->features & (NETIF_F_IPV6_CSUM | NETIF_F_HW_CSUM))
+		csummode = CHECKSUM_PARTIAL;
+
+	/*
+	 * Let's try using as much space as possible.
+	 * Use MTU if total length of the message fits into the MTU.
+	 * Otherwise, we need to reserve fragment header and
+	 * fragment alignment (= 8-15 octects, in total).
+	 *
+	 * Note that we may need to "move" the data from the tail of
+	 * of the buffer to the new fragment when we split
+	 * the message.
+	 *
+	 * FIXME: It may be fragmented into multiple chunks
+	 *        at once if non-fragmentable extension headers
+	 *        are too large.
+	 * --yoshfuji
+	 */
+
+	cork->length += length;
+	if (!skb)
+		goto alloc_new_skb;
+
+	while (length > 0) {
+		/* Check if the remaining data fits into current packet. */
+		copy = (cork->length <= mtu && !(cork->flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - skb->len;
+		if (copy < length)
+			copy = maxfraglen - skb->len;
+
+		if (copy <= 0) {
+			char *data;
+			unsigned int datalen;
+			unsigned int fraglen;
+			unsigned int fraggap;
+			unsigned int alloclen, alloc_extra;
+			unsigned int pagedlen;
+alloc_new_skb:
+			/* There's no room in the current skb */
+			if (skb)
+				fraggap = skb->len - maxfraglen;
+			else
+				fraggap = 0;
+			/* update mtu and maxfraglen if necessary */
+			if (!skb || !skb_prev)
+				ip6_append_data_mtu(&mtu, &maxfraglen,
+						    fragheaderlen, skb, rt,
+						    orig_mtu);
+
+			skb_prev = skb;
+
+			/*
+			 * If remaining data exceeds the mtu,
+			 * we know we need more fragment(s).
+			 */
+			datalen = length + fraggap;
+
+			if (datalen > (cork->length <= mtu && !(cork->flags & IPCORK_ALLFRAG) ? mtu : maxfraglen) - fragheaderlen)
+				datalen = maxfraglen - fragheaderlen - rt->dst.trailer_len;
+			fraglen = datalen + fragheaderlen;
+			pagedlen = 0;
+
+			alloc_extra = hh_len;
+			alloc_extra += dst_exthdrlen;
+			alloc_extra += rt->dst.trailer_len;
+
+			/* We just reserve space for fragment header.
+			 * Note: this may be overallocation if the message
+			 * (without MSG_MORE) fits into the MTU.
+			 */
+			alloc_extra += sizeof(struct frag_hdr);
+
+			if ((flags & MSG_MORE) &&
+			    !(rt->dst.dev->features&NETIF_F_SG))
+				alloclen = mtu;
+			else if (!paged &&
+				 (fraglen + alloc_extra < SKB_MAX_ALLOC ||
+				  !(rt->dst.dev->features & NETIF_F_SG)))
+				alloclen = fraglen;
+			else {
+				alloclen = min_t(int, fraglen, MAX_HEADER);
+				pagedlen = fraglen - alloclen;
+			}
+			alloclen += alloc_extra;
+
+			if (datalen != length + fraggap) {
+				/*
+				 * this is not the last fragment, the trailer
+				 * space is regarded as data space.
+				 */
+				datalen += rt->dst.trailer_len;
+			}
+
+			fraglen = datalen + fragheaderlen;
+
+			copy = datalen - transhdrlen - fraggap - pagedlen;
+			if (copy < 0) {
+				err = -EINVAL;
+				goto error;
+			}
+			if (transhdrlen) {
+				skb = sock_alloc_send_skb(sk, alloclen,
+						(flags & MSG_DONTWAIT), &err);
+			} else {
+				skb = NULL;
+				if (refcount_read(&sk->sk_wmem_alloc) + wmem_alloc_delta <=
+				    2 * sk->sk_sndbuf)
+					skb = alloc_skb(alloclen,
+							sk->sk_allocation);
+				if (unlikely(!skb))
+					err = -ENOBUFS;
+			}
+			if (!skb)
+				goto error;
+			/*
+			 *	Fill in the control structures
+			 */
+			skb->protocol = htons(ETH_P_IPV6);
+			skb->ip_summed = csummode;
+			skb->csum = 0;
+			/* reserve for fragmentation and ipsec header */
+			skb_reserve(skb, hh_len + sizeof(struct frag_hdr) +
+				    dst_exthdrlen);
+
+			/* Only the initial fragment is time stamped */
+			skb_shinfo(skb)->tx_flags = cork->tx_flags;
+			cork->tx_flags = 0;
+			skb_shinfo(skb)->tskey = tskey;
+			tskey = 0;
+
+			/*
+			 *	Find where to start putting bytes
+			 */
+			data = skb_put(skb, fraglen - pagedlen);
+			skb_set_network_header(skb, exthdrlen);
+			data += fragheaderlen;
+			skb->transport_header = (skb->network_header +
+						 fragheaderlen);
+			if (fraggap) {
+				skb->csum = skb_copy_and_csum_bits(
+					skb_prev, maxfraglen,
+					data + transhdrlen, fraggap, 0);
+				skb_prev->csum = csum_sub(skb_prev->csum,
+							  skb->csum);
+				data += fraggap;
+				pskb_trim_unique(skb_prev, maxfraglen);
+			}
+			if (copy > 0 &&
+			    getfrag(from, data + transhdrlen, offset,
+				    copy, fraggap, skb) < 0) {
+				err = -EFAULT;
+				kfree_skb(skb);
+				goto error;
+			}
+
+			offset += copy;
+			length -= copy + transhdrlen;
+			transhdrlen = 0;
+			exthdrlen = 0;
+			dst_exthdrlen = 0;
+
+			if ((flags & MSG_CONFIRM) && !skb_prev)
+				skb_set_dst_pending_confirm(skb, 1);
+
+			/*
+			 * Put the packet on the pending queue
+			 */
+			if (!skb->destructor) {
+				skb->destructor = sock_wfree;
+				skb->sk = sk;
+				wmem_alloc_delta += skb->truesize;
+			}
+			__skb_queue_tail(queue, skb);
+			continue;
+		}
+
+		if (copy > length)
+			copy = length;
+
+		if (!(rt->dst.dev->features&NETIF_F_SG) &&
+		    skb_tailroom(skb) >= copy) {
+			unsigned int off;
+
+			off = skb->len;
+			if (getfrag(from, skb_put(skb, copy),
+						offset, copy, off, skb) < 0) {
+				__skb_trim(skb, off);
+				err = -EFAULT;
+				goto error;
+			}
+		} else {
+			int i = skb_shinfo(skb)->nr_frags;
+
+			err = -ENOMEM;
+			if (!sk_page_frag_refill(sk, pfrag))
+				goto error;
+
+			if (!skb_can_coalesce(skb, i, pfrag->page,
+					      pfrag->offset)) {
+				err = -EMSGSIZE;
+				if (i == MAX_SKB_FRAGS)
+					goto error;
+
+				__skb_fill_page_desc(skb, i, pfrag->page,
+						     pfrag->offset, 0);
+				skb_shinfo(skb)->nr_frags = ++i;
+				get_page(pfrag->page);
+			}
+			copy = min_t(int, copy, pfrag->size - pfrag->offset);
+			if (getfrag(from,
+				    page_address(pfrag->page) + pfrag->offset,
+				    offset, copy, skb->len, skb) < 0)
+				goto error_efault;
+
+			pfrag->offset += copy;
+			skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
+			skb->len += copy;
+			skb->data_len += copy;
+			skb->truesize += copy;
+			wmem_alloc_delta += copy;
+		}
+		offset += copy;
+		length -= copy;
+	}
+
+	if (wmem_alloc_delta)
+		refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
+	return 0;
+
+error_efault:
+	err = -EFAULT;
+error:
+	cork->length -= length;
+	IP6_INC_STATS(sock_net(sk), rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS);
+	refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc);
+	return err;
+}
+
+int ip6_append_data(struct sock *sk,
+		    int getfrag(void *from, char *to, int offset, int len,
+				int odd, struct sk_buff *skb),
+		    void *from, int length, int transhdrlen,
+		    struct ipcm6_cookie *ipc6, struct flowi6 *fl6,
+		    struct rt6_info *rt, unsigned int flags)
+{
+	struct inet_sock *inet = inet_sk(sk);
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	int exthdrlen;
+	int err;
+
+	if (flags&MSG_PROBE)
+		return 0;
+	if (skb_queue_empty(&sk->sk_write_queue)) {
+		/*
+		 * setup for corking
+		 */
+		err = ip6_setup_cork(sk, &inet->cork, &np->cork,
+				     ipc6, rt, fl6);
+		if (err)
+			return err;
+
+		exthdrlen = (ipc6->opt ? ipc6->opt->opt_flen : 0);
+		length += exthdrlen;
+		transhdrlen += exthdrlen;
+	} else {
+		fl6 = &inet->cork.fl.u.ip6;
+		transhdrlen = 0;
+	}
+
+	return __ip6_append_data(sk, fl6, &sk->sk_write_queue, &inet->cork.base,
+				 &np->cork, sk_page_frag(sk), getfrag,
+				 from, length, transhdrlen, flags, ipc6);
+}
+EXPORT_SYMBOL_GPL(ip6_append_data);
+
+static void ip6_cork_release(struct inet_cork_full *cork,
+			     struct inet6_cork *v6_cork)
+{
+	if (v6_cork->opt) {
+		kfree(v6_cork->opt->dst0opt);
+		kfree(v6_cork->opt->dst1opt);
+		kfree(v6_cork->opt->hopopt);
+		kfree(v6_cork->opt->srcrt);
+		kfree(v6_cork->opt);
+		v6_cork->opt = NULL;
+	}
+
+	if (cork->base.dst) {
+		dst_release(cork->base.dst);
+		cork->base.dst = NULL;
+		cork->base.flags &= ~IPCORK_ALLFRAG;
+	}
+	memset(&cork->fl, 0, sizeof(cork->fl));
+}
+
+struct sk_buff *__ip6_make_skb(struct sock *sk,
+			       struct sk_buff_head *queue,
+			       struct inet_cork_full *cork,
+			       struct inet6_cork *v6_cork)
+{
+	struct sk_buff *skb, *tmp_skb;
+	struct sk_buff **tail_skb;
+	struct in6_addr final_dst_buf, *final_dst = &final_dst_buf;
+	struct ipv6_pinfo *np = inet6_sk(sk);
+	struct net *net = sock_net(sk);
+	struct ipv6hdr *hdr;
+	struct ipv6_txoptions *opt = v6_cork->opt;
+	struct rt6_info *rt = (struct rt6_info *)cork->base.dst;
+	struct flowi6 *fl6 = &cork->fl.u.ip6;
+	unsigned char proto = fl6->flowi6_proto;
+
+	skb = __skb_dequeue(queue);
+	if (!skb)
+		goto out;
+	tail_skb = &(skb_shinfo(skb)->frag_list);
+
+	/* move skb->data to ip header from ext header */
+	if (skb->data < skb_network_header(skb))
+		__skb_pull(skb, skb_network_offset(skb));
+	while ((tmp_skb = __skb_dequeue(queue)) != NULL) {
+		__skb_pull(tmp_skb, skb_network_header_len(skb));
+		*tail_skb = tmp_skb;
+		tail_skb = &(tmp_skb->next);
+		skb->len += tmp_skb->len;
+		skb->data_len += tmp_skb->len;
+		skb->truesize += tmp_skb->truesize;
+		tmp_skb->destructor = NULL;
+		tmp_skb->sk = NULL;
+	}
+
+	/* Allow local fragmentation. */
+	skb->ignore_df = ip6_sk_ignore_df(sk);
+
+	*final_dst = fl6->daddr;
+	__skb_pull(skb, skb_network_header_len(skb));
+	if (opt && opt->opt_flen)
+		ipv6_push_frag_opts(skb, opt, &proto);
+	if (opt && opt->opt_nflen)
+		ipv6_push_nfrag_opts(skb, opt, &proto, &final_dst, &fl6->saddr);
+
+	skb_push(skb, sizeof(struct ipv6hdr));
+	skb_reset_network_header(skb);
+	hdr = ipv6_hdr(skb);
+
+	ip6_flow_hdr(hdr, v6_cork->tclass,
+		     ip6_make_flowlabel(net, skb, fl6->flowlabel,
+					ip6_autoflowlabel(net, np), fl6));
+	hdr->hop_limit = v6_cork->hop_limit;
+	hdr->nexthdr = proto;
+	hdr->saddr = fl6->saddr;
+	hdr->daddr = *final_dst;
+
+	skb->priority = sk->sk_priority;
+	skb->mark = sk->sk_mark;
+
+	skb->tstamp = cork->base.transmit_time;
+
+	skb_dst_set(skb, dst_clone(&rt->dst));
+	IP6_UPD_PO_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUT, skb->len);
+	if (proto == IPPROTO_ICMPV6) {
+		struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb));
+
+		ICMP6MSGOUT_INC_STATS(net, idev, icmp6_hdr(skb)->icmp6_type);
+		ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTMSGS);
+	}
+
+	ip6_cork_release(cork, v6_cork);
+out:
+	return skb;
+}
+
+int ip6_send_skb(struct sk_buff *skb)
+{
+	struct net *net = sock_net(skb->sk);
+	struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
+	int err;
+
+	err = ip6_local_out(net, skb->sk, skb);
+	if (err) {
+		if (err > 0)
+			err = net_xmit_errno(err);
+		if (err)
+			IP6_INC_STATS(net, rt->rt6i_idev,
+				      IPSTATS_MIB_OUTDISCARDS);
+	}
+
+	return err;
+}
+
+int ip6_push_pending_frames(struct sock *sk)
+{
+	struct sk_buff *skb;
+
+	skb = ip6_finish_skb(sk);
+	if (!skb)
+		return 0;
+
+	return ip6_send_skb(skb);
+}
+EXPORT_SYMBOL_GPL(ip6_push_pending_frames);
+
+static void __ip6_flush_pending_frames(struct sock *sk,
+				       struct sk_buff_head *queue,
+				       struct inet_cork_full *cork,
+				       struct inet6_cork *v6_cork)
+{
+	struct sk_buff *skb;
+
+	while ((skb = __skb_dequeue_tail(queue)) != NULL) {
+		if (skb_dst(skb))
+			IP6_INC_STATS(sock_net(sk), ip6_dst_idev(skb_dst(skb)),
+				      IPSTATS_MIB_OUTDISCARDS);
+		kfree_skb(skb);
+	}
+
+	ip6_cork_release(cork, v6_cork);
+}
+
+void ip6_flush_pending_frames(struct sock *sk)
+{
+	__ip6_flush_pending_frames(sk, &sk->sk_write_queue,
+				   &inet_sk(sk)->cork, &inet6_sk(sk)->cork);
+}
+EXPORT_SYMBOL_GPL(ip6_flush_pending_frames);
+
+struct sk_buff *ip6_make_skb(struct sock *sk,
+			     int getfrag(void *from, char *to, int offset,
+					 int len, int odd, struct sk_buff *skb),
+			     void *from, int length, int transhdrlen,
+			     struct ipcm6_cookie *ipc6, struct flowi6 *fl6,
+			     struct rt6_info *rt, unsigned int flags,
+			     struct inet_cork_full *cork)
+{
+	struct inet6_cork v6_cork;
+	struct sk_buff_head queue;
+	int exthdrlen = (ipc6->opt ? ipc6->opt->opt_flen : 0);
+	int err;
+
+	if (flags & MSG_PROBE)
+		return NULL;
+
+	__skb_queue_head_init(&queue);
+
+	cork->base.flags = 0;
+	cork->base.addr = 0;
+	cork->base.opt = NULL;
+	cork->base.dst = NULL;
+	v6_cork.opt = NULL;
+	err = ip6_setup_cork(sk, cork, &v6_cork, ipc6, rt, fl6);
+	if (err) {
+		ip6_cork_release(cork, &v6_cork);
+		return ERR_PTR(err);
+	}
+	if (ipc6->dontfrag < 0)
+		ipc6->dontfrag = inet6_sk(sk)->dontfrag;
+
+	err = __ip6_append_data(sk, fl6, &queue, &cork->base, &v6_cork,
+				&current->task_frag, getfrag, from,
+				length + exthdrlen, transhdrlen + exthdrlen,
+				flags, ipc6);
+	if (err) {
+		__ip6_flush_pending_frames(sk, &queue, cork, &v6_cork);
+		return ERR_PTR(err);
+	}
+
+	return __ip6_make_skb(sk, &queue, cork, &v6_cork);
+}