Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 2268 insertions, 0 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
new file mode 100644
index 0000000000..3783334ef2
--- /dev/null
+++ b/net/ipv6/tcp_ipv6.c
@@ -0,0 +1,2268 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	TCP over IPv6
+ *	Linux INET6 implementation
+ *
+ *	Authors:
+ *	Pedro Roque		<roque@di.fc.ul.pt>
+ *
+ *	Based on:
+ *	linux/net/ipv4/tcp.c
+ *	linux/net/ipv4/tcp_input.c
+ *	linux/net/ipv4/tcp_output.c
+ *
+ *	Fixes:
+ *	Hideaki YOSHIFUJI	:	sin6_scope_id support
+ *	YOSHIFUJI Hideaki @USAGI and:	Support IPV6_V6ONLY socket option, which
+ *	Alexey Kuznetsov		allow both IPv4 and IPv6 sockets to bind
+ *					a single port at the same time.
+ *	YOSHIFUJI Hideaki @USAGI:	convert /proc/net/tcp6 to seq_file.
+ */
+
+#include <linux/bottom_half.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/socket.h>
+#include <linux/sockios.h>
+#include <linux/net.h>
+#include <linux/jiffies.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/netdevice.h>
+#include <linux/init.h>
+#include <linux/jhash.h>
+#include <linux/ipsec.h>
+#include <linux/times.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/ipv6.h>
+#include <linux/icmpv6.h>
+#include <linux/random.h>
+#include <linux/indirect_call_wrapper.h>
+
+#include <net/tcp.h>
+#include <net/ndisc.h>
+#include <net/inet6_hashtables.h>
+#include <net/inet6_connection_sock.h>
+#include <net/ipv6.h>
+#include <net/transp_v6.h>
+#include <net/addrconf.h>
+#include <net/ip6_route.h>
+#include <net/ip6_checksum.h>
+#include <net/inet_ecn.h>
+#include <net/protocol.h>
+#include <net/xfrm.h>
+#include <net/snmp.h>
+#include <net/dsfield.h>
+#include <net/timewait_sock.h>
+#include <net/inet_common.h>
+#include <net/secure_seq.h>
+#include <net/busy_poll.h>
+
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+
+#include <crypto/hash.h>
+#include <linux/scatterlist.h>
+
+#include <trace/events/tcp.h>
+
+static void	tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb);
+static void	tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
+				      struct request_sock *req);
+
+INDIRECT_CALLABLE_SCOPE int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb);
+
+static const struct inet_connection_sock_af_ops ipv6_mapped;
+const struct inet_connection_sock_af_ops ipv6_specific;
+#ifdef CONFIG_TCP_MD5SIG
+static const struct tcp_sock_af_ops tcp_sock_ipv6_specific;
+static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific;
+#else
+static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(const struct sock *sk,
+						   const struct in6_addr *addr,
+						   int l3index)
+{
+	return NULL;
+}
+#endif
+
+/* Helper returning the inet6 address from a given tcp socket.
+ * It can be used in TCP stack instead of inet6_sk(sk).
+ * This avoids a dereference and allow compiler optimizations.
+ * It is a specialized version of inet6_sk_generic().
+ */
+#define tcp_inet6_sk(sk) (&container_of_const(tcp_sk(sk), \
+					      struct tcp6_sock, tcp)->inet6)
+
+static void inet6_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb)
+{
+	struct dst_entry *dst = skb_dst(skb);
+
+	if (dst && dst_hold_safe(dst)) {
+		const struct rt6_info *rt = (const struct rt6_info *)dst;
+
+		rcu_assign_pointer(sk->sk_rx_dst, dst);
+		sk->sk_rx_dst_ifindex = skb->skb_iif;
+		sk->sk_rx_dst_cookie = rt6_get_cookie(rt);
+	}
+}
+
+static u32 tcp_v6_init_seq(const struct sk_buff *skb)
+{
+	return secure_tcpv6_seq(ipv6_hdr(skb)->daddr.s6_addr32,
+				ipv6_hdr(skb)->saddr.s6_addr32,
+				tcp_hdr(skb)->dest,
+				tcp_hdr(skb)->source);
+}
+
+static u32 tcp_v6_init_ts_off(const struct net *net, const struct sk_buff *skb)
+{
+	return secure_tcpv6_ts_off(net, ipv6_hdr(skb)->daddr.s6_addr32,
+				   ipv6_hdr(skb)->saddr.s6_addr32);
+}
+
+static int tcp_v6_pre_connect(struct sock *sk, struct sockaddr *uaddr,
+			      int addr_len)
+{
+	/* This check is replicated from tcp_v6_connect() and intended to
+	 * prevent BPF program called below from accessing bytes that are out
+	 * of the bound specified by user in addr_len.
+	 */
+	if (addr_len < SIN6_LEN_RFC2133)
+		return -EINVAL;
+
+	sock_owned_by_me(sk);
+
+	return BPF_CGROUP_RUN_PROG_INET6_CONNECT(sk, uaddr, &addr_len);
+}
+
+static int tcp_v6_connect(struct sock *sk, struct sockaddr *uaddr,
+			  int addr_len)
+{
+	struct sockaddr_in6 *usin = (struct sockaddr_in6 *) uaddr;
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct in6_addr *saddr = NULL, *final_p, final;
+	struct inet_timewait_death_row *tcp_death_row;
+	struct ipv6_pinfo *np = tcp_inet6_sk(sk);
+	struct inet_sock *inet = inet_sk(sk);
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct net *net = sock_net(sk);
+	struct ipv6_txoptions *opt;
+	struct dst_entry *dst;
+	struct flowi6 fl6;
+	int addr_type;
+	int err;
+
+	if (addr_len < SIN6_LEN_RFC2133)
+		return -EINVAL;
+
+	if (usin->sin6_family != AF_INET6)
+		return -EAFNOSUPPORT;
+
+	memset(&fl6, 0, sizeof(fl6));
+
+	if (np->sndflow) {
+		fl6.flowlabel = usin->sin6_flowinfo&IPV6_FLOWINFO_MASK;
+		IP6_ECN_flow_init(fl6.flowlabel);
+		if (fl6.flowlabel&IPV6_FLOWLABEL_MASK) {
+			struct ip6_flowlabel *flowlabel;
+			flowlabel = fl6_sock_lookup(sk, fl6.flowlabel);
+			if (IS_ERR(flowlabel))
+				return -EINVAL;
+			fl6_sock_release(flowlabel);
+		}
+	}
+
+	/*
+	 *	connect() to INADDR_ANY means loopback (BSD'ism).
+	 */
+
+	if (ipv6_addr_any(&usin->sin6_addr)) {
+		if (ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr))
+			ipv6_addr_set_v4mapped(htonl(INADDR_LOOPBACK),
+					       &usin->sin6_addr);
+		else
+			usin->sin6_addr = in6addr_loopback;
+	}
+
+	addr_type = ipv6_addr_type(&usin->sin6_addr);
+
+	if (addr_type & IPV6_ADDR_MULTICAST)
+		return -ENETUNREACH;
+
+	if (addr_type&IPV6_ADDR_LINKLOCAL) {
+		if (addr_len >= sizeof(struct sockaddr_in6) &&
+		    usin->sin6_scope_id) {
+			/* If interface is set while binding, indices
+			 * must coincide.
+			 */
+			if (!sk_dev_equal_l3scope(sk, usin->sin6_scope_id))
+				return -EINVAL;
+
+			sk->sk_bound_dev_if = usin->sin6_scope_id;
+		}
+
+		/* Connect to link-local address requires an interface */
+		if (!sk->sk_bound_dev_if)
+			return -EINVAL;
+	}
+
+	if (tp->rx_opt.ts_recent_stamp &&
+	    !ipv6_addr_equal(&sk->sk_v6_daddr, &usin->sin6_addr)) {
+		tp->rx_opt.ts_recent = 0;
+		tp->rx_opt.ts_recent_stamp = 0;
+		WRITE_ONCE(tp->write_seq, 0);
+	}
+
+	sk->sk_v6_daddr = usin->sin6_addr;
+	np->flow_label = fl6.flowlabel;
+
+	/*
+	 *	TCP over IPv4
+	 */
+
+	if (addr_type & IPV6_ADDR_MAPPED) {
+		u32 exthdrlen = icsk->icsk_ext_hdr_len;
+		struct sockaddr_in sin;
+
+		if (ipv6_only_sock(sk))
+			return -ENETUNREACH;
+
+		sin.sin_family = AF_INET;
+		sin.sin_port = usin->sin6_port;
+		sin.sin_addr.s_addr = usin->sin6_addr.s6_addr32[3];
+
+		/* Paired with READ_ONCE() in tcp_(get|set)sockopt() */
+		WRITE_ONCE(icsk->icsk_af_ops, &ipv6_mapped);
+		if (sk_is_mptcp(sk))
+			mptcpv6_handle_mapped(sk, true);
+		sk->sk_backlog_rcv = tcp_v4_do_rcv;
+#ifdef CONFIG_TCP_MD5SIG
+		tp->af_specific = &tcp_sock_ipv6_mapped_specific;
+#endif
+
+		err = tcp_v4_connect(sk, (struct sockaddr *)&sin, sizeof(sin));
+
+		if (err) {
+			icsk->icsk_ext_hdr_len = exthdrlen;
+			/* Paired with READ_ONCE() in tcp_(get|set)sockopt() */
+			WRITE_ONCE(icsk->icsk_af_ops, &ipv6_specific);
+			if (sk_is_mptcp(sk))
+				mptcpv6_handle_mapped(sk, false);
+			sk->sk_backlog_rcv = tcp_v6_do_rcv;
+#ifdef CONFIG_TCP_MD5SIG
+			tp->af_specific = &tcp_sock_ipv6_specific;
+#endif
+			goto failure;
+		}
+		np->saddr = sk->sk_v6_rcv_saddr;
+
+		return err;
+	}
+
+	if (!ipv6_addr_any(&sk->sk_v6_rcv_saddr))
+		saddr = &sk->sk_v6_rcv_saddr;
+
+	fl6.flowi6_proto = IPPROTO_TCP;
+	fl6.daddr = sk->sk_v6_daddr;
+	fl6.saddr = saddr ? *saddr : np->saddr;
+	fl6.flowlabel = ip6_make_flowinfo(np->tclass, np->flow_label);
+	fl6.flowi6_oif = sk->sk_bound_dev_if;
+	fl6.flowi6_mark = sk->sk_mark;
+	fl6.fl6_dport = usin->sin6_port;
+	fl6.fl6_sport = inet->inet_sport;
+	fl6.flowi6_uid = sk->sk_uid;
+
+	opt = rcu_dereference_protected(np->opt, lockdep_sock_is_held(sk));
+	final_p = fl6_update_dst(&fl6, opt, &final);
+
+	security_sk_classify_flow(sk, flowi6_to_flowi_common(&fl6));
+
+	dst = ip6_dst_lookup_flow(net, sk, &fl6, final_p);
+	if (IS_ERR(dst)) {
+		err = PTR_ERR(dst);
+		goto failure;
+	}
+
+	tcp_death_row = &sock_net(sk)->ipv4.tcp_death_row;
+
+	if (!saddr) {
+		saddr = &fl6.saddr;
+
+		err = inet_bhash2_update_saddr(sk, saddr, AF_INET6);
+		if (err)
+			goto failure;
+	}
+
+	/* set the source address */
+	np->saddr = *saddr;
+	inet->inet_rcv_saddr = LOOPBACK4_IPV6;
+
+	sk->sk_gso_type = SKB_GSO_TCPV6;
+	ip6_dst_store(sk, dst, NULL, NULL);
+
+	icsk->icsk_ext_hdr_len = 0;
+	if (opt)
+		icsk->icsk_ext_hdr_len = opt->opt_flen +
+					 opt->opt_nflen;
+
+	tp->rx_opt.mss_clamp = IPV6_MIN_MTU - sizeof(struct tcphdr) - sizeof(struct ipv6hdr);
+
+	inet->inet_dport = usin->sin6_port;
+
+	tcp_set_state(sk, TCP_SYN_SENT);
+	err = inet6_hash_connect(tcp_death_row, sk);
+	if (err)
+		goto late_failure;
+
+	sk_set_txhash(sk);
+
+	if (likely(!tp->repair)) {
+		if (!tp->write_seq)
+			WRITE_ONCE(tp->write_seq,
+				   secure_tcpv6_seq(np->saddr.s6_addr32,
+						    sk->sk_v6_daddr.s6_addr32,
+						    inet->inet_sport,
+						    inet->inet_dport));
+		tp->tsoffset = secure_tcpv6_ts_off(net, np->saddr.s6_addr32,
+						   sk->sk_v6_daddr.s6_addr32);
+	}
+
+	if (tcp_fastopen_defer_connect(sk, &err))
+		return err;
+	if (err)
+		goto late_failure;
+
+	err = tcp_connect(sk);
+	if (err)
+		goto late_failure;
+
+	return 0;
+
+late_failure:
+	tcp_set_state(sk, TCP_CLOSE);
+	inet_bhash2_reset_saddr(sk);
+failure:
+	inet->inet_dport = 0;
+	sk->sk_route_caps = 0;
+	return err;
+}
+
+static void tcp_v6_mtu_reduced(struct sock *sk)
+{
+	struct dst_entry *dst;
+	u32 mtu;
+
+	if ((1 << sk->sk_state) & (TCPF_LISTEN | TCPF_CLOSE))
+		return;
+
+	mtu = READ_ONCE(tcp_sk(sk)->mtu_info);
+
+	/* Drop requests trying to increase our current mss.
+	 * Check done in __ip6_rt_update_pmtu() is too late.
+	 */
+	if (tcp_mtu_to_mss(sk, mtu) >= tcp_sk(sk)->mss_cache)
+		return;
+
+	dst = inet6_csk_update_pmtu(sk, mtu);
+	if (!dst)
+		return;
+
+	if (inet_csk(sk)->icsk_pmtu_cookie > dst_mtu(dst)) {
+		tcp_sync_mss(sk, dst_mtu(dst));
+		tcp_simple_retransmit(sk);
+	}
+}
+
+static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+		u8 type, u8 code, int offset, __be32 info)
+{
+	const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data;
+	const struct tcphdr *th = (struct tcphdr *)(skb->data+offset);
+	struct net *net = dev_net(skb->dev);
+	struct request_sock *fastopen;
+	struct ipv6_pinfo *np;
+	struct tcp_sock *tp;
+	__u32 seq, snd_una;
+	struct sock *sk;
+	bool fatal;
+	int err;
+
+	sk = __inet6_lookup_established(net, net->ipv4.tcp_death_row.hashinfo,
+					&hdr->daddr, th->dest,
+					&hdr->saddr, ntohs(th->source),
+					skb->dev->ifindex, inet6_sdif(skb));
+
+	if (!sk) {
+		__ICMP6_INC_STATS(net, __in6_dev_get(skb->dev),
+				  ICMP6_MIB_INERRORS);
+		return -ENOENT;
+	}
+
+	if (sk->sk_state == TCP_TIME_WAIT) {
+		inet_twsk_put(inet_twsk(sk));
+		return 0;
+	}
+	seq = ntohl(th->seq);
+	fatal = icmpv6_err_convert(type, code, &err);
+	if (sk->sk_state == TCP_NEW_SYN_RECV) {
+		tcp_req_err(sk, seq, fatal);
+		return 0;
+	}
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk) && type != ICMPV6_PKT_TOOBIG)
+		__NET_INC_STATS(net, LINUX_MIB_LOCKDROPPEDICMPS);
+
+	if (sk->sk_state == TCP_CLOSE)
+		goto out;
+
+	if (static_branch_unlikely(&ip6_min_hopcount)) {
+		/* min_hopcount can be changed concurrently from do_ipv6_setsockopt() */
+		if (ipv6_hdr(skb)->hop_limit < READ_ONCE(tcp_inet6_sk(sk)->min_hopcount)) {
+			__NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP);
+			goto out;
+		}
+	}
+
+	tp = tcp_sk(sk);
+	/* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */
+	fastopen = rcu_dereference(tp->fastopen_rsk);
+	snd_una = fastopen ? tcp_rsk(fastopen)->snt_isn : tp->snd_una;
+	if (sk->sk_state != TCP_LISTEN &&
+	    !between(seq, snd_una, tp->snd_nxt)) {
+		__NET_INC_STATS(net, LINUX_MIB_OUTOFWINDOWICMPS);
+		goto out;
+	}
+
+	np = tcp_inet6_sk(sk);
+
+	if (type == NDISC_REDIRECT) {
+		if (!sock_owned_by_user(sk)) {
+			struct dst_entry *dst = __sk_dst_check(sk, np->dst_cookie);
+
+			if (dst)
+				dst->ops->redirect(dst, sk, skb);
+		}
+		goto out;
+	}
+
+	if (type == ICMPV6_PKT_TOOBIG) {
+		u32 mtu = ntohl(info);
+
+		/* We are not interested in TCP_LISTEN and open_requests
+		 * (SYN-ACKs send out by Linux are always <576bytes so
+		 * they should go through unfragmented).
+		 */
+		if (sk->sk_state == TCP_LISTEN)
+			goto out;
+
+		if (!ip6_sk_accept_pmtu(sk))
+			goto out;
+
+		if (mtu < IPV6_MIN_MTU)
+			goto out;
+
+		WRITE_ONCE(tp->mtu_info, mtu);
+
+		if (!sock_owned_by_user(sk))
+			tcp_v6_mtu_reduced(sk);
+		else if (!test_and_set_bit(TCP_MTU_REDUCED_DEFERRED,
+					   &sk->sk_tsq_flags))
+			sock_hold(sk);
+		goto out;
+	}
+
+
+	/* Might be for an request_sock */
+	switch (sk->sk_state) {
+	case TCP_SYN_SENT:
+	case TCP_SYN_RECV:
+		/* Only in fast or simultaneous open. If a fast open socket is
+		 * already accepted it is treated as a connected one below.
+		 */
+		if (fastopen && !fastopen->sk)
+			break;
+
+		ipv6_icmp_error(sk, skb, err, th->dest, ntohl(info), (u8 *)th);
+
+		if (!sock_owned_by_user(sk)) {
+			WRITE_ONCE(sk->sk_err, err);
+			sk_error_report(sk);		/* Wake people up to see the error (see connect in sock.c) */
+
+			tcp_done(sk);
+		} else {
+			WRITE_ONCE(sk->sk_err_soft, err);
+		}
+		goto out;
+	case TCP_LISTEN:
+		break;
+	default:
+		/* check if this ICMP message allows revert of backoff.
+		 * (see RFC 6069)
+		 */
+		if (!fastopen && type == ICMPV6_DEST_UNREACH &&
+		    code == ICMPV6_NOROUTE)
+			tcp_ld_RTO_revert(sk, seq);
+	}
+
+	if (!sock_owned_by_user(sk) && np->recverr) {
+		WRITE_ONCE(sk->sk_err, err);
+		sk_error_report(sk);
+	} else {
+		WRITE_ONCE(sk->sk_err_soft, err);
+	}
+out:
+	bh_unlock_sock(sk);
+	sock_put(sk);
+	return 0;
+}
+
+
+static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
+			      struct flowi *fl,
+			      struct request_sock *req,
+			      struct tcp_fastopen_cookie *foc,
+			      enum tcp_synack_type synack_type,
+			      struct sk_buff *syn_skb)
+{
+	struct inet_request_sock *ireq = inet_rsk(req);
+	const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
+	struct ipv6_txoptions *opt;
+	struct flowi6 *fl6 = &fl->u.ip6;
+	struct sk_buff *skb;
+	int err = -ENOMEM;
+	u8 tclass;
+
+	/* First, grab a route. */
+	if (!dst && (dst = inet6_csk_route_req(sk, fl6, req,
+					       IPPROTO_TCP)) == NULL)
+		goto done;
+
+	skb = tcp_make_synack(sk, dst, req, foc, synack_type, syn_skb);
+
+	if (skb) {
+		__tcp_v6_send_check(skb, &ireq->ir_v6_loc_addr,
+				    &ireq->ir_v6_rmt_addr);
+
+		fl6->daddr = ireq->ir_v6_rmt_addr;
+		if (np->repflow && ireq->pktopts)
+			fl6->flowlabel = ip6_flowlabel(ipv6_hdr(ireq->pktopts));
+
+		tclass = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_reflect_tos) ?
+				(tcp_rsk(req)->syn_tos & ~INET_ECN_MASK) |
+				(np->tclass & INET_ECN_MASK) :
+				np->tclass;
+
+		if (!INET_ECN_is_capable(tclass) &&
+		    tcp_bpf_ca_needs_ecn((struct sock *)req))
+			tclass |= INET_ECN_ECT_0;
+
+		rcu_read_lock();
+		opt = ireq->ipv6_opt;
+		if (!opt)
+			opt = rcu_dereference(np->opt);
+		err = ip6_xmit(sk, skb, fl6, skb->mark ? : READ_ONCE(sk->sk_mark),
+			       opt, tclass, sk->sk_priority);
+		rcu_read_unlock();
+		err = net_xmit_eval(err);
+	}
+
+done:
+	return err;
+}
+
+
+static void tcp_v6_reqsk_destructor(struct request_sock *req)
+{
+	kfree(inet_rsk(req)->ipv6_opt);
+	consume_skb(inet_rsk(req)->pktopts);
+}
+
+#ifdef CONFIG_TCP_MD5SIG
+static struct tcp_md5sig_key *tcp_v6_md5_do_lookup(const struct sock *sk,
+						   const struct in6_addr *addr,
+						   int l3index)
+{
+	return tcp_md5_do_lookup(sk, l3index,
+				 (union tcp_md5_addr *)addr, AF_INET6);
+}
+
+static struct tcp_md5sig_key *tcp_v6_md5_lookup(const struct sock *sk,
+						const struct sock *addr_sk)
+{
+	int l3index;
+
+	l3index = l3mdev_master_ifindex_by_index(sock_net(sk),
+						 addr_sk->sk_bound_dev_if);
+	return tcp_v6_md5_do_lookup(sk, &addr_sk->sk_v6_daddr,
+				    l3index);
+}
+
+static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
+				 sockptr_t optval, int optlen)
+{
+	struct tcp_md5sig cmd;
+	struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&cmd.tcpm_addr;
+	int l3index = 0;
+	u8 prefixlen;
+	u8 flags;
+
+	if (optlen < sizeof(cmd))
+		return -EINVAL;
+
+	if (copy_from_sockptr(&cmd, optval, sizeof(cmd)))
+		return -EFAULT;
+
+	if (sin6->sin6_family != AF_INET6)
+		return -EINVAL;
+
+	flags = cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX;
+
+	if (optname == TCP_MD5SIG_EXT &&
+	    cmd.tcpm_flags & TCP_MD5SIG_FLAG_PREFIX) {
+		prefixlen = cmd.tcpm_prefixlen;
+		if (prefixlen > 128 || (ipv6_addr_v4mapped(&sin6->sin6_addr) &&
+					prefixlen > 32))
+			return -EINVAL;
+	} else {
+		prefixlen = ipv6_addr_v4mapped(&sin6->sin6_addr) ? 32 : 128;
+	}
+
+	if (optname == TCP_MD5SIG_EXT && cmd.tcpm_ifindex &&
+	    cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX) {
+		struct net_device *dev;
+
+		rcu_read_lock();
+		dev = dev_get_by_index_rcu(sock_net(sk), cmd.tcpm_ifindex);
+		if (dev && netif_is_l3_master(dev))
+			l3index = dev->ifindex;
+		rcu_read_unlock();
+
+		/* ok to reference set/not set outside of rcu;
+		 * right now device MUST be an L3 master
+		 */
+		if (!dev || !l3index)
+			return -EINVAL;
+	}
+
+	if (!cmd.tcpm_keylen) {
+		if (ipv6_addr_v4mapped(&sin6->sin6_addr))
+			return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3],
+					      AF_INET, prefixlen,
+					      l3index, flags);
+		return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr,
+				      AF_INET6, prefixlen, l3index, flags);
+	}
+
+	if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
+		return -EINVAL;
+
+	if (ipv6_addr_v4mapped(&sin6->sin6_addr))
+		return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3],
+				      AF_INET, prefixlen, l3index, flags,
+				      cmd.tcpm_key, cmd.tcpm_keylen);
+
+	return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr,
+			      AF_INET6, prefixlen, l3index, flags,
+			      cmd.tcpm_key, cmd.tcpm_keylen);
+}
+
+static int tcp_v6_md5_hash_headers(struct tcp_md5sig_pool *hp,
+				   const struct in6_addr *daddr,
+				   const struct in6_addr *saddr,
+				   const struct tcphdr *th, int nbytes)
+{
+	struct tcp6_pseudohdr *bp;
+	struct scatterlist sg;
+	struct tcphdr *_th;
+
+	bp = hp->scratch;
+	/* 1. TCP pseudo-header (RFC2460) */
+	bp->saddr = *saddr;
+	bp->daddr = *daddr;
+	bp->protocol = cpu_to_be32(IPPROTO_TCP);
+	bp->len = cpu_to_be32(nbytes);
+
+	_th = (struct tcphdr *)(bp + 1);
+	memcpy(_th, th, sizeof(*th));
+	_th->check = 0;
+
+	sg_init_one(&sg, bp, sizeof(*bp) + sizeof(*th));
+	ahash_request_set_crypt(hp->md5_req, &sg, NULL,
+				sizeof(*bp) + sizeof(*th));
+	return crypto_ahash_update(hp->md5_req);
+}
+
+static int tcp_v6_md5_hash_hdr(char *md5_hash, const struct tcp_md5sig_key *key,
+			       const struct in6_addr *daddr, struct in6_addr *saddr,
+			       const struct tcphdr *th)
+{
+	struct tcp_md5sig_pool *hp;
+	struct ahash_request *req;
+
+	hp = tcp_get_md5sig_pool();
+	if (!hp)
+		goto clear_hash_noput;
+	req = hp->md5_req;
+
+	if (crypto_ahash_init(req))
+		goto clear_hash;
+	if (tcp_v6_md5_hash_headers(hp, daddr, saddr, th, th->doff << 2))
+		goto clear_hash;
+	if (tcp_md5_hash_key(hp, key))
+		goto clear_hash;
+	ahash_request_set_crypt(req, NULL, md5_hash, 0);
+	if (crypto_ahash_final(req))
+		goto clear_hash;
+
+	tcp_put_md5sig_pool();
+	return 0;
+
+clear_hash:
+	tcp_put_md5sig_pool();
+clear_hash_noput:
+	memset(md5_hash, 0, 16);
+	return 1;
+}
+
+static int tcp_v6_md5_hash_skb(char *md5_hash,
+			       const struct tcp_md5sig_key *key,
+			       const struct sock *sk,
+			       const struct sk_buff *skb)
+{
+	const struct in6_addr *saddr, *daddr;
+	struct tcp_md5sig_pool *hp;
+	struct ahash_request *req;
+	const struct tcphdr *th = tcp_hdr(skb);
+
+	if (sk) { /* valid for establish/request sockets */
+		saddr = &sk->sk_v6_rcv_saddr;
+		daddr = &sk->sk_v6_daddr;
+	} else {
+		const struct ipv6hdr *ip6h = ipv6_hdr(skb);
+		saddr = &ip6h->saddr;
+		daddr = &ip6h->daddr;
+	}
+
+	hp = tcp_get_md5sig_pool();
+	if (!hp)
+		goto clear_hash_noput;
+	req = hp->md5_req;
+
+	if (crypto_ahash_init(req))
+		goto clear_hash;
+
+	if (tcp_v6_md5_hash_headers(hp, daddr, saddr, th, skb->len))
+		goto clear_hash;
+	if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
+		goto clear_hash;
+	if (tcp_md5_hash_key(hp, key))
+		goto clear_hash;
+	ahash_request_set_crypt(req, NULL, md5_hash, 0);
+	if (crypto_ahash_final(req))
+		goto clear_hash;
+
+	tcp_put_md5sig_pool();
+	return 0;
+
+clear_hash:
+	tcp_put_md5sig_pool();
+clear_hash_noput:
+	memset(md5_hash, 0, 16);
+	return 1;
+}
+
+#endif
+
+static void tcp_v6_init_req(struct request_sock *req,
+			    const struct sock *sk_listener,
+			    struct sk_buff *skb)
+{
+	bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
+	struct inet_request_sock *ireq = inet_rsk(req);
+	const struct ipv6_pinfo *np = tcp_inet6_sk(sk_listener);
+
+	ireq->ir_v6_rmt_addr = ipv6_hdr(skb)->saddr;
+	ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;
+
+	/* So that link locals have meaning */
+	if ((!sk_listener->sk_bound_dev_if || l3_slave) &&
+	    ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)
+		ireq->ir_iif = tcp_v6_iif(skb);
+
+	if (!TCP_SKB_CB(skb)->tcp_tw_isn &&
+	    (ipv6_opt_accepted(sk_listener, skb, &TCP_SKB_CB(skb)->header.h6) ||
+	     np->rxopt.bits.rxinfo ||
+	     np->rxopt.bits.rxoinfo || np->rxopt.bits.rxhlim ||
+	     np->rxopt.bits.rxohlim || np->repflow)) {
+		refcount_inc(&skb->users);
+		ireq->pktopts = skb;
+	}
+}
+
+static struct dst_entry *tcp_v6_route_req(const struct sock *sk,
+					  struct sk_buff *skb,
+					  struct flowi *fl,
+					  struct request_sock *req)
+{
+	tcp_v6_init_req(req, sk, skb);
+
+	if (security_inet_conn_request(sk, skb, req))
+		return NULL;
+
+	return inet6_csk_route_req(sk, &fl->u.ip6, req, IPPROTO_TCP);
+}
+
+struct request_sock_ops tcp6_request_sock_ops __read_mostly = {
+	.family		=	AF_INET6,
+	.obj_size	=	sizeof(struct tcp6_request_sock),
+	.rtx_syn_ack	=	tcp_rtx_synack,
+	.send_ack	=	tcp_v6_reqsk_send_ack,
+	.destructor	=	tcp_v6_reqsk_destructor,
+	.send_reset	=	tcp_v6_send_reset,
+	.syn_ack_timeout =	tcp_syn_ack_timeout,
+};
+
+const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
+	.mss_clamp	=	IPV6_MIN_MTU - sizeof(struct tcphdr) -
+				sizeof(struct ipv6hdr),
+#ifdef CONFIG_TCP_MD5SIG
+	.req_md5_lookup	=	tcp_v6_md5_lookup,
+	.calc_md5_hash	=	tcp_v6_md5_hash_skb,
+#endif
+#ifdef CONFIG_SYN_COOKIES
+	.cookie_init_seq =	cookie_v6_init_sequence,
+#endif
+	.route_req	=	tcp_v6_route_req,
+	.init_seq	=	tcp_v6_init_seq,
+	.init_ts_off	=	tcp_v6_init_ts_off,
+	.send_synack	=	tcp_v6_send_synack,
+};
+
+static void tcp_v6_send_response(const struct sock *sk, struct sk_buff *skb, u32 seq,
+				 u32 ack, u32 win, u32 tsval, u32 tsecr,
+				 int oif, struct tcp_md5sig_key *key, int rst,
+				 u8 tclass, __be32 label, u32 priority, u32 txhash)
+{
+	const struct tcphdr *th = tcp_hdr(skb);
+	struct tcphdr *t1;
+	struct sk_buff *buff;
+	struct flowi6 fl6;
+	struct net *net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
+	struct sock *ctl_sk = net->ipv6.tcp_sk;
+	unsigned int tot_len = sizeof(struct tcphdr);
+	__be32 mrst = 0, *topt;
+	struct dst_entry *dst;
+	__u32 mark = 0;
+
+	if (tsecr)
+		tot_len += TCPOLEN_TSTAMP_ALIGNED;
+#ifdef CONFIG_TCP_MD5SIG
+	if (key)
+		tot_len += TCPOLEN_MD5SIG_ALIGNED;
+#endif
+
+#ifdef CONFIG_MPTCP
+	if (rst && !key) {
+		mrst = mptcp_reset_option(skb);
+
+		if (mrst)
+			tot_len += sizeof(__be32);
+	}
+#endif
+
+	buff = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC);
+	if (!buff)
+		return;
+
+	skb_reserve(buff, MAX_TCP_HEADER);
+
+	t1 = skb_push(buff, tot_len);
+	skb_reset_transport_header(buff);
+
+	/* Swap the send and the receive. */
+	memset(t1, 0, sizeof(*t1));
+	t1->dest = th->source;
+	t1->source = th->dest;
+	t1->doff = tot_len / 4;
+	t1->seq = htonl(seq);
+	t1->ack_seq = htonl(ack);
+	t1->ack = !rst || !th->ack;
+	t1->rst = rst;
+	t1->window = htons(win);
+
+	topt = (__be32 *)(t1 + 1);
+
+	if (tsecr) {
+		*topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
+				(TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
+		*topt++ = htonl(tsval);
+		*topt++ = htonl(tsecr);
+	}
+
+	if (mrst)
+		*topt++ = mrst;
+
+#ifdef CONFIG_TCP_MD5SIG
+	if (key) {
+		*topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
+				(TCPOPT_MD5SIG << 8) | TCPOLEN_MD5SIG);
+		tcp_v6_md5_hash_hdr((__u8 *)topt, key,
+				    &ipv6_hdr(skb)->saddr,
+				    &ipv6_hdr(skb)->daddr, t1);
+	}
+#endif
+
+	memset(&fl6, 0, sizeof(fl6));
+	fl6.daddr = ipv6_hdr(skb)->saddr;
+	fl6.saddr = ipv6_hdr(skb)->daddr;
+	fl6.flowlabel = label;
+
+	buff->ip_summed = CHECKSUM_PARTIAL;
+
+	__tcp_v6_send_check(buff, &fl6.saddr, &fl6.daddr);
+
+	fl6.flowi6_proto = IPPROTO_TCP;
+	if (rt6_need_strict(&fl6.daddr) && !oif)
+		fl6.flowi6_oif = tcp_v6_iif(skb);
+	else {
+		if (!oif && netif_index_is_l3_master(net, skb->skb_iif))
+			oif = skb->skb_iif;
+
+		fl6.flowi6_oif = oif;
+	}
+
+	if (sk) {
+		if (sk->sk_state == TCP_TIME_WAIT)
+			mark = inet_twsk(sk)->tw_mark;
+		else
+			mark = READ_ONCE(sk->sk_mark);
+		skb_set_delivery_time(buff, tcp_transmit_time(sk), true);
+	}
+	if (txhash) {
+		/* autoflowlabel/skb_get_hash_flowi6 rely on buff->hash */
+		skb_set_hash(buff, txhash, PKT_HASH_TYPE_L4);
+	}
+	fl6.flowi6_mark = IP6_REPLY_MARK(net, skb->mark) ?: mark;
+	fl6.fl6_dport = t1->dest;
+	fl6.fl6_sport = t1->source;
+	fl6.flowi6_uid = sock_net_uid(net, sk && sk_fullsock(sk) ? sk : NULL);
+	security_skb_classify_flow(skb, flowi6_to_flowi_common(&fl6));
+
+	/* Pass a socket to ip6_dst_lookup either it is for RST
+	 * Underlying function will use this to retrieve the network
+	 * namespace
+	 */
+	if (sk && sk->sk_state != TCP_TIME_WAIT)
+		dst = ip6_dst_lookup_flow(net, sk, &fl6, NULL); /*sk's xfrm_policy can be referred*/
+	else
+		dst = ip6_dst_lookup_flow(net, ctl_sk, &fl6, NULL);
+	if (!IS_ERR(dst)) {
+		skb_dst_set(buff, dst);
+		ip6_xmit(ctl_sk, buff, &fl6, fl6.flowi6_mark, NULL,
+			 tclass & ~INET_ECN_MASK, priority);
+		TCP_INC_STATS(net, TCP_MIB_OUTSEGS);
+		if (rst)
+			TCP_INC_STATS(net, TCP_MIB_OUTRSTS);
+		return;
+	}
+
+	kfree_skb(buff);
+}
+
+static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
+{
+	const struct tcphdr *th = tcp_hdr(skb);
+	struct ipv6hdr *ipv6h = ipv6_hdr(skb);
+	u32 seq = 0, ack_seq = 0;
+	struct tcp_md5sig_key *key = NULL;
+#ifdef CONFIG_TCP_MD5SIG
+	const __u8 *hash_location = NULL;
+	unsigned char newhash[16];
+	int genhash;
+	struct sock *sk1 = NULL;
+#endif
+	__be32 label = 0;
+	u32 priority = 0;
+	struct net *net;
+	u32 txhash = 0;
+	int oif = 0;
+
+	if (th->rst)
+		return;
+
+	/* If sk not NULL, it means we did a successful lookup and incoming
+	 * route had to be correct. prequeue might have dropped our dst.
+	 */
+	if (!sk && !ipv6_unicast_destination(skb))
+		return;
+
+	net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
+#ifdef CONFIG_TCP_MD5SIG
+	rcu_read_lock();
+	hash_location = tcp_parse_md5sig_option(th);
+	if (sk && sk_fullsock(sk)) {
+		int l3index;
+
+		/* sdif set, means packet ingressed via a device
+		 * in an L3 domain and inet_iif is set to it.
+		 */
+		l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
+		key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr, l3index);
+	} else if (hash_location) {
+		int dif = tcp_v6_iif_l3_slave(skb);
+		int sdif = tcp_v6_sdif(skb);
+		int l3index;
+
+		/*
+		 * active side is lost. Try to find listening socket through
+		 * source port, and then find md5 key through listening socket.
+		 * we are not loose security here:
+		 * Incoming packet is checked with md5 hash with finding key,
+		 * no RST generated if md5 hash doesn't match.
+		 */
+		sk1 = inet6_lookup_listener(net, net->ipv4.tcp_death_row.hashinfo,
+					    NULL, 0, &ipv6h->saddr, th->source,
+					    &ipv6h->daddr, ntohs(th->source),
+					    dif, sdif);
+		if (!sk1)
+			goto out;
+
+		/* sdif set, means packet ingressed via a device
+		 * in an L3 domain and dif is set to it.
+		 */
+		l3index = tcp_v6_sdif(skb) ? dif : 0;
+
+		key = tcp_v6_md5_do_lookup(sk1, &ipv6h->saddr, l3index);
+		if (!key)
+			goto out;
+
+		genhash = tcp_v6_md5_hash_skb(newhash, key, NULL, skb);
+		if (genhash || memcmp(hash_location, newhash, 16) != 0)
+			goto out;
+	}
+#endif
+
+	if (th->ack)
+		seq = ntohl(th->ack_seq);
+	else
+		ack_seq = ntohl(th->seq) + th->syn + th->fin + skb->len -
+			  (th->doff << 2);
+
+	if (sk) {
+		oif = sk->sk_bound_dev_if;
+		if (sk_fullsock(sk)) {
+			const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
+
+			trace_tcp_send_reset(sk, skb);
+			if (np->repflow)
+				label = ip6_flowlabel(ipv6h);
+			priority = sk->sk_priority;
+			txhash = sk->sk_txhash;
+		}
+		if (sk->sk_state == TCP_TIME_WAIT) {
+			label = cpu_to_be32(inet_twsk(sk)->tw_flowlabel);
+			priority = inet_twsk(sk)->tw_priority;
+			txhash = inet_twsk(sk)->tw_txhash;
+		}
+	} else {
+		if (net->ipv6.sysctl.flowlabel_reflect & FLOWLABEL_REFLECT_TCP_RESET)
+			label = ip6_flowlabel(ipv6h);
+	}
+
+	tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, key, 1,
+			     ipv6_get_dsfield(ipv6h), label, priority, txhash);
+
+#ifdef CONFIG_TCP_MD5SIG
+out:
+	rcu_read_unlock();
+#endif
+}
+
+static void tcp_v6_send_ack(const struct sock *sk, struct sk_buff *skb, u32 seq,
+			    u32 ack, u32 win, u32 tsval, u32 tsecr, int oif,
+			    struct tcp_md5sig_key *key, u8 tclass,
+			    __be32 label, u32 priority, u32 txhash)
+{
+	tcp_v6_send_response(sk, skb, seq, ack, win, tsval, tsecr, oif, key, 0,
+			     tclass, label, priority, txhash);
+}
+
+static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
+{
+	struct inet_timewait_sock *tw = inet_twsk(sk);
+	struct tcp_timewait_sock *tcptw = tcp_twsk(sk);
+
+	tcp_v6_send_ack(sk, skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
+			tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
+			tcp_time_stamp_raw() + tcptw->tw_ts_offset,
+			tcptw->tw_ts_recent, tw->tw_bound_dev_if, tcp_twsk_md5_key(tcptw),
+			tw->tw_tclass, cpu_to_be32(tw->tw_flowlabel), tw->tw_priority,
+			tw->tw_txhash);
+
+	inet_twsk_put(tw);
+}
+
+static void tcp_v6_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
+				  struct request_sock *req)
+{
+	int l3index;
+
+	l3index = tcp_v6_sdif(skb) ? tcp_v6_iif_l3_slave(skb) : 0;
+
+	/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
+	 * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
+	 */
+	/* RFC 7323 2.3
+	 * The window field (SEG.WND) of every outgoing segment, with the
+	 * exception of <SYN> segments, MUST be right-shifted by
+	 * Rcv.Wind.Shift bits:
+	 */
+	tcp_v6_send_ack(sk, skb, (sk->sk_state == TCP_LISTEN) ?
+			tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
+			tcp_rsk(req)->rcv_nxt,
+			req->rsk_rcv_wnd >> inet_rsk(req)->rcv_wscale,
+			tcp_time_stamp_raw() + tcp_rsk(req)->ts_off,
+			READ_ONCE(req->ts_recent), sk->sk_bound_dev_if,
+			tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->saddr, l3index),
+			ipv6_get_dsfield(ipv6_hdr(skb)), 0,
+			READ_ONCE(sk->sk_priority),
+			READ_ONCE(tcp_rsk(req)->txhash));
+}
+
+
+static struct sock *tcp_v6_cookie_check(struct sock *sk, struct sk_buff *skb)
+{
+#ifdef CONFIG_SYN_COOKIES
+	const struct tcphdr *th = tcp_hdr(skb);
+
+	if (!th->syn)
+		sk = cookie_v6_check(sk, skb);
+#endif
+	return sk;
+}
+
+u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
+			 struct tcphdr *th, u32 *cookie)
+{
+	u16 mss = 0;
+#ifdef CONFIG_SYN_COOKIES
+	mss = tcp_get_syncookie_mss(&tcp6_request_sock_ops,
+				    &tcp_request_sock_ipv6_ops, sk, th);
+	if (mss) {
+		*cookie = __cookie_v6_init_sequence(iph, th, &mss);
+		tcp_synq_overflow(sk);
+	}
+#endif
+	return mss;
+}
+
+static int tcp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
+{
+	if (skb->protocol == htons(ETH_P_IP))
+		return tcp_v4_conn_request(sk, skb);
+
+	if (!ipv6_unicast_destination(skb))
+		goto drop;
+
+	if (ipv6_addr_v4mapped(&ipv6_hdr(skb)->saddr)) {
+		__IP6_INC_STATS(sock_net(sk), NULL, IPSTATS_MIB_INHDRERRORS);
+		return 0;
+	}
+
+	return tcp_conn_request(&tcp6_request_sock_ops,
+				&tcp_request_sock_ipv6_ops, sk, skb);
+
+drop:
+	tcp_listendrop(sk);
+	return 0; /* don't send reset */
+}
+
+static void tcp_v6_restore_cb(struct sk_buff *skb)
+{
+	/* We need to move header back to the beginning if xfrm6_policy_check()
+	 * and tcp_v6_fill_cb() are going to be called again.
+	 * ip6_datagram_recv_specific_ctl() also expects IP6CB to be there.
+	 */
+	memmove(IP6CB(skb), &TCP_SKB_CB(skb)->header.h6,
+		sizeof(struct inet6_skb_parm));
+}
+
+static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
+					 struct request_sock *req,
+					 struct dst_entry *dst,
+					 struct request_sock *req_unhash,
+					 bool *own_req)
+{
+	struct inet_request_sock *ireq;
+	struct ipv6_pinfo *newnp;
+	const struct ipv6_pinfo *np = tcp_inet6_sk(sk);
+	struct ipv6_txoptions *opt;
+	struct inet_sock *newinet;
+	bool found_dup_sk = false;
+	struct tcp_sock *newtp;
+	struct sock *newsk;
+#ifdef CONFIG_TCP_MD5SIG
+	struct tcp_md5sig_key *key;
+	int l3index;
+#endif
+	struct flowi6 fl6;
+
+	if (skb->protocol == htons(ETH_P_IP)) {
+		/*
+		 *	v6 mapped
+		 */
+
+		newsk = tcp_v4_syn_recv_sock(sk, skb, req, dst,
+					     req_unhash, own_req);
+
+		if (!newsk)
+			return NULL;
+
+		inet_sk(newsk)->pinet6 = tcp_inet6_sk(newsk);
+
+		newnp = tcp_inet6_sk(newsk);
+		newtp = tcp_sk(newsk);
+
+		memcpy(newnp, np, sizeof(struct ipv6_pinfo));
+
+		newnp->saddr = newsk->sk_v6_rcv_saddr;
+
+		inet_csk(newsk)->icsk_af_ops = &ipv6_mapped;
+		if (sk_is_mptcp(newsk))
+			mptcpv6_handle_mapped(newsk, true);
+		newsk->sk_backlog_rcv = tcp_v4_do_rcv;
+#ifdef CONFIG_TCP_MD5SIG
+		newtp->af_specific = &tcp_sock_ipv6_mapped_specific;
+#endif
+
+		newnp->ipv6_mc_list = NULL;
+		newnp->ipv6_ac_list = NULL;
+		newnp->ipv6_fl_list = NULL;
+		newnp->pktoptions  = NULL;
+		newnp->opt	   = NULL;
+		newnp->mcast_oif   = inet_iif(skb);
+		newnp->mcast_hops  = ip_hdr(skb)->ttl;
+		newnp->rcv_flowinfo = 0;
+		if (np->repflow)
+			newnp->flow_label = 0;
+
+		/*
+		 * No need to charge this sock to the relevant IPv6 refcnt debug socks count
+		 * here, tcp_create_openreq_child now does this for us, see the comment in
+		 * that function for the gory details. -acme
+		 */
+
+		/* It is tricky place. Until this moment IPv4 tcp
+		   worked with IPv6 icsk.icsk_af_ops.
+		   Sync it now.
+		 */
+		tcp_sync_mss(newsk, inet_csk(newsk)->icsk_pmtu_cookie);
+
+		return newsk;
+	}
+
+	ireq = inet_rsk(req);
+
+	if (sk_acceptq_is_full(sk))
+		goto out_overflow;
+
+	if (!dst) {
+		dst = inet6_csk_route_req(sk, &fl6, req, IPPROTO_TCP);
+		if (!dst)
+			goto out;
+	}
+
+	newsk = tcp_create_openreq_child(sk, req, skb);
+	if (!newsk)
+		goto out_nonewsk;
+
+	/*
+	 * No need to charge this sock to the relevant IPv6 refcnt debug socks
+	 * count here, tcp_create_openreq_child now does this for us, see the
+	 * comment in that function for the gory details. -acme
+	 */
+
+	newsk->sk_gso_type = SKB_GSO_TCPV6;
+	ip6_dst_store(newsk, dst, NULL, NULL);
+	inet6_sk_rx_dst_set(newsk, skb);
+
+	inet_sk(newsk)->pinet6 = tcp_inet6_sk(newsk);
+
+	newtp = tcp_sk(newsk);
+	newinet = inet_sk(newsk);
+	newnp = tcp_inet6_sk(newsk);
+
+	memcpy(newnp, np, sizeof(struct ipv6_pinfo));
+
+	newsk->sk_v6_daddr = ireq->ir_v6_rmt_addr;
+	newnp->saddr = ireq->ir_v6_loc_addr;
+	newsk->sk_v6_rcv_saddr = ireq->ir_v6_loc_addr;
+	newsk->sk_bound_dev_if = ireq->ir_iif;
+
+	/* Now IPv6 options...
+
+	   First: no IPv4 options.
+	 */
+	newinet->inet_opt = NULL;
+	newnp->ipv6_mc_list = NULL;
+	newnp->ipv6_ac_list = NULL;
+	newnp->ipv6_fl_list = NULL;
+
+	/* Clone RX bits */
+	newnp->rxopt.all = np->rxopt.all;
+
+	newnp->pktoptions = NULL;
+	newnp->opt	  = NULL;
+	newnp->mcast_oif  = tcp_v6_iif(skb);
+	newnp->mcast_hops = ipv6_hdr(skb)->hop_limit;
+	newnp->rcv_flowinfo = ip6_flowinfo(ipv6_hdr(skb));
+	if (np->repflow)
+		newnp->flow_label = ip6_flowlabel(ipv6_hdr(skb));
+
+	/* Set ToS of the new socket based upon the value of incoming SYN.
+	 * ECT bits are set later in tcp_init_transfer().
+	 */
+	if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_reflect_tos))
+		newnp->tclass = tcp_rsk(req)->syn_tos & ~INET_ECN_MASK;
+
+	/* Clone native IPv6 options from listening socket (if any)
+
+	   Yes, keeping reference count would be much more clever,
+	   but we make one more one thing there: reattach optmem
+	   to newsk.
+	 */
+	opt = ireq->ipv6_opt;
+	if (!opt)
+		opt = rcu_dereference(np->opt);
+	if (opt) {
+		opt = ipv6_dup_options(newsk, opt);
+		RCU_INIT_POINTER(newnp->opt, opt);
+	}
+	inet_csk(newsk)->icsk_ext_hdr_len = 0;
+	if (opt)
+		inet_csk(newsk)->icsk_ext_hdr_len = opt->opt_nflen +
+						    opt->opt_flen;
+
+	tcp_ca_openreq_child(newsk, dst);
+
+	tcp_sync_mss(newsk, dst_mtu(dst));
+	newtp->advmss = tcp_mss_clamp(tcp_sk(sk), dst_metric_advmss(dst));
+
+	tcp_initialize_rcv_mss(newsk);
+
+	newinet->inet_daddr = newinet->inet_saddr = LOOPBACK4_IPV6;
+	newinet->inet_rcv_saddr = LOOPBACK4_IPV6;
+
+#ifdef CONFIG_TCP_MD5SIG
+	l3index = l3mdev_master_ifindex_by_index(sock_net(sk), ireq->ir_iif);
+
+	/* Copy over the MD5 key from the original socket */
+	key = tcp_v6_md5_do_lookup(sk, &newsk->sk_v6_daddr, l3index);
+	if (key) {
+		const union tcp_md5_addr *addr;
+
+		addr = (union tcp_md5_addr *)&newsk->sk_v6_daddr;
+		if (tcp_md5_key_copy(newsk, addr, AF_INET6, 128, l3index, key)) {
+			inet_csk_prepare_forced_close(newsk);
+			tcp_done(newsk);
+			goto out;
+		}
+	}
+#endif
+
+	if (__inet_inherit_port(sk, newsk) < 0) {
+		inet_csk_prepare_forced_close(newsk);
+		tcp_done(newsk);
+		goto out;
+	}
+	*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash),
+				       &found_dup_sk);
+	if (*own_req) {
+		tcp_move_syn(newtp, req);
+
+		/* Clone pktoptions received with SYN, if we own the req */
+		if (ireq->pktopts) {
+			newnp->pktoptions = skb_clone_and_charge_r(ireq->pktopts, newsk);
+			consume_skb(ireq->pktopts);
+			ireq->pktopts = NULL;
+			if (newnp->pktoptions)
+				tcp_v6_restore_cb(newnp->pktoptions);
+		}
+	} else {
+		if (!req_unhash && found_dup_sk) {
+			/* This code path should only be executed in the
+			 * syncookie case only
+			 */
+			bh_unlock_sock(newsk);
+			sock_put(newsk);
+			newsk = NULL;
+		}
+	}
+
+	return newsk;
+
+out_overflow:
+	__NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
+out_nonewsk:
+	dst_release(dst);
+out:
+	tcp_listendrop(sk);
+	return NULL;
+}
+
+INDIRECT_CALLABLE_DECLARE(struct dst_entry *ipv4_dst_check(struct dst_entry *,
+							   u32));
+/* The socket must have it's spinlock held when we get
+ * here, unless it is a TCP_LISTEN socket.
+ *
+ * We have a potential double-lock case here, so even when
+ * doing backlog processing we use the BH locking scheme.
+ * This is because we cannot sleep with the original spinlock
+ * held.
+ */
+INDIRECT_CALLABLE_SCOPE
+int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
+{
+	struct ipv6_pinfo *np = tcp_inet6_sk(sk);
+	struct sk_buff *opt_skb = NULL;
+	enum skb_drop_reason reason;
+	struct tcp_sock *tp;
+
+	/* Imagine: socket is IPv6. IPv4 packet arrives,
+	   goes to IPv4 receive handler and backlogged.
+	   From backlog it always goes here. Kerboom...
+	   Fortunately, tcp_rcv_established and rcv_established
+	   handle them correctly, but it is not case with
+	   tcp_v6_hnd_req and tcp_v6_send_reset().   --ANK
+	 */
+
+	if (skb->protocol == htons(ETH_P_IP))
+		return tcp_v4_do_rcv(sk, skb);
+
+	/*
+	 *	socket locking is here for SMP purposes as backlog rcv
+	 *	is currently called with bh processing disabled.
+	 */
+
+	/* Do Stevens' IPV6_PKTOPTIONS.
+
+	   Yes, guys, it is the only place in our code, where we
+	   may make it not affecting IPv4.
+	   The rest of code is protocol independent,
+	   and I do not like idea to uglify IPv4.
+
+	   Actually, all the idea behind IPV6_PKTOPTIONS
+	   looks not very well thought. For now we latch
+	   options, received in the last packet, enqueued
+	   by tcp. Feel free to propose better solution.
+					       --ANK (980728)
+	 */
+	if (np->rxopt.all)
+		opt_skb = skb_clone_and_charge_r(skb, sk);
+
+	reason = SKB_DROP_REASON_NOT_SPECIFIED;
+	if (sk->sk_state == TCP_ESTABLISHED) { /* Fast path */
+		struct dst_entry *dst;
+
+		dst = rcu_dereference_protected(sk->sk_rx_dst,
+						lockdep_sock_is_held(sk));
+
+		sock_rps_save_rxhash(sk, skb);
+		sk_mark_napi_id(sk, skb);
+		if (dst) {
+			if (sk->sk_rx_dst_ifindex != skb->skb_iif ||
+			    INDIRECT_CALL_1(dst->ops->check, ip6_dst_check,
+					    dst, sk->sk_rx_dst_cookie) == NULL) {
+				RCU_INIT_POINTER(sk->sk_rx_dst, NULL);
+				dst_release(dst);
+			}
+		}
+
+		tcp_rcv_established(sk, skb);
+		if (opt_skb)
+			goto ipv6_pktoptions;
+		return 0;
+	}
+
+	if (tcp_checksum_complete(skb))
+		goto csum_err;
+
+	if (sk->sk_state == TCP_LISTEN) {
+		struct sock *nsk = tcp_v6_cookie_check(sk, skb);
+
+		if (!nsk)
+			goto discard;
+
+		if (nsk != sk) {
+			if (tcp_child_process(sk, nsk, skb))
+				goto reset;
+			if (opt_skb)
+				__kfree_skb(opt_skb);
+			return 0;
+		}
+	} else
+		sock_rps_save_rxhash(sk, skb);
+
+	if (tcp_rcv_state_process(sk, skb))
+		goto reset;
+	if (opt_skb)
+		goto ipv6_pktoptions;
+	return 0;
+
+reset:
+	tcp_v6_send_reset(sk, skb);
+discard:
+	if (opt_skb)
+		__kfree_skb(opt_skb);
+	kfree_skb_reason(skb, reason);
+	return 0;
+csum_err:
+	reason = SKB_DROP_REASON_TCP_CSUM;
+	trace_tcp_bad_csum(skb);
+	TCP_INC_STATS(sock_net(sk), TCP_MIB_CSUMERRORS);
+	TCP_INC_STATS(sock_net(sk), TCP_MIB_INERRS);
+	goto discard;
+
+
+ipv6_pktoptions:
+	/* Do you ask, what is it?
+
+	   1. skb was enqueued by tcp.
+	   2. skb is added to tail of read queue, rather than out of order.
+	   3. socket is not in passive state.
+	   4. Finally, it really contains options, which user wants to receive.
+	 */
+	tp = tcp_sk(sk);
+	if (TCP_SKB_CB(opt_skb)->end_seq == tp->rcv_nxt &&
+	    !((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))) {
+		if (np->rxopt.bits.rxinfo || np->rxopt.bits.rxoinfo)
+			np->mcast_oif = tcp_v6_iif(opt_skb);
+		if (np->rxopt.bits.rxhlim || np->rxopt.bits.rxohlim)
+			np->mcast_hops = ipv6_hdr(opt_skb)->hop_limit;
+		if (np->rxopt.bits.rxflow || np->rxopt.bits.rxtclass)
+			np->rcv_flowinfo = ip6_flowinfo(ipv6_hdr(opt_skb));
+		if (np->repflow)
+			np->flow_label = ip6_flowlabel(ipv6_hdr(opt_skb));
+		if (ipv6_opt_accepted(sk, opt_skb, &TCP_SKB_CB(opt_skb)->header.h6)) {
+			tcp_v6_restore_cb(opt_skb);
+			opt_skb = xchg(&np->pktoptions, opt_skb);
+		} else {
+			__kfree_skb(opt_skb);
+			opt_skb = xchg(&np->pktoptions, NULL);
+		}
+	}
+
+	consume_skb(opt_skb);
+	return 0;
+}
+
+static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr,
+			   const struct tcphdr *th)
+{
+	/* This is tricky: we move IP6CB at its correct location into
+	 * TCP_SKB_CB(). It must be done after xfrm6_policy_check(), because
+	 * _decode_session6() uses IP6CB().
+	 * barrier() makes sure compiler won't play aliasing games.
+	 */
+	memmove(&TCP_SKB_CB(skb)->header.h6, IP6CB(skb),
+		sizeof(struct inet6_skb_parm));
+	barrier();
+
+	TCP_SKB_CB(skb)->seq = ntohl(th->seq);
+	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +
+				    skb->len - th->doff*4);
+	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);
+	TCP_SKB_CB(skb)->tcp_flags = tcp_flag_byte(th);
+	TCP_SKB_CB(skb)->tcp_tw_isn = 0;
+	TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr);
+	TCP_SKB_CB(skb)->sacked = 0;
+	TCP_SKB_CB(skb)->has_rxtstamp =
+			skb->tstamp || skb_hwtstamps(skb)->hwtstamp;
+}
+
+INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
+{
+	enum skb_drop_reason drop_reason;
+	int sdif = inet6_sdif(skb);
+	int dif = inet6_iif(skb);
+	const struct tcphdr *th;
+	const struct ipv6hdr *hdr;
+	bool refcounted;
+	struct sock *sk;
+	int ret;
+	struct net *net = dev_net(skb->dev);
+
+	drop_reason = SKB_DROP_REASON_NOT_SPECIFIED;
+	if (skb->pkt_type != PACKET_HOST)
+		goto discard_it;
+
+	/*
+	 *	Count it even if it's bad.
+	 */
+	__TCP_INC_STATS(net, TCP_MIB_INSEGS);
+
+	if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
+		goto discard_it;
+
+	th = (const struct tcphdr *)skb->data;
+
+	if (unlikely(th->doff < sizeof(struct tcphdr) / 4)) {
+		drop_reason = SKB_DROP_REASON_PKT_TOO_SMALL;
+		goto bad_packet;
+	}
+	if (!pskb_may_pull(skb, th->doff*4))
+		goto discard_it;
+
+	if (skb_checksum_init(skb, IPPROTO_TCP, ip6_compute_pseudo))
+		goto csum_error;
+
+	th = (const struct tcphdr *)skb->data;
+	hdr = ipv6_hdr(skb);
+
+lookup:
+	sk = __inet6_lookup_skb(net->ipv4.tcp_death_row.hashinfo, skb, __tcp_hdrlen(th),
+				th->source, th->dest, inet6_iif(skb), sdif,
+				&refcounted);
+	if (!sk)
+		goto no_tcp_socket;
+
+process:
+	if (sk->sk_state == TCP_TIME_WAIT)
+		goto do_time_wait;
+
+	if (sk->sk_state == TCP_NEW_SYN_RECV) {
+		struct request_sock *req = inet_reqsk(sk);
+		bool req_stolen = false;
+		struct sock *nsk;
+
+		sk = req->rsk_listener;
+		if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
+			drop_reason = SKB_DROP_REASON_XFRM_POLICY;
+		else
+			drop_reason = tcp_inbound_md5_hash(sk, skb,
+							   &hdr->saddr, &hdr->daddr,
+							   AF_INET6, dif, sdif);
+		if (drop_reason) {
+			sk_drops_add(sk, skb);
+			reqsk_put(req);
+			goto discard_it;
+		}
+		if (tcp_checksum_complete(skb)) {
+			reqsk_put(req);
+			goto csum_error;
+		}
+		if (unlikely(sk->sk_state != TCP_LISTEN)) {
+			nsk = reuseport_migrate_sock(sk, req_to_sk(req), skb);
+			if (!nsk) {
+				inet_csk_reqsk_queue_drop_and_put(sk, req);
+				goto lookup;
+			}
+			sk = nsk;
+			/* reuseport_migrate_sock() has already held one sk_refcnt
+			 * before returning.
+			 */
+		} else {
+			sock_hold(sk);
+		}
+		refcounted = true;
+		nsk = NULL;
+		if (!tcp_filter(sk, skb)) {
+			th = (const struct tcphdr *)skb->data;
+			hdr = ipv6_hdr(skb);
+			tcp_v6_fill_cb(skb, hdr, th);
+			nsk = tcp_check_req(sk, skb, req, false, &req_stolen);
+		} else {
+			drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
+		}
+		if (!nsk) {
+			reqsk_put(req);
+			if (req_stolen) {
+				/* Another cpu got exclusive access to req
+				 * and created a full blown socket.
+				 * Try to feed this packet to this socket
+				 * instead of discarding it.
+				 */
+				tcp_v6_restore_cb(skb);
+				sock_put(sk);
+				goto lookup;
+			}
+			goto discard_and_relse;
+		}
+		nf_reset_ct(skb);
+		if (nsk == sk) {
+			reqsk_put(req);
+			tcp_v6_restore_cb(skb);
+		} else if (tcp_child_process(sk, nsk, skb)) {
+			tcp_v6_send_reset(nsk, skb);
+			goto discard_and_relse;
+		} else {
+			sock_put(sk);
+			return 0;
+		}
+	}
+
+	if (static_branch_unlikely(&ip6_min_hopcount)) {
+		/* min_hopcount can be changed concurrently from do_ipv6_setsockopt() */
+		if (unlikely(hdr->hop_limit < READ_ONCE(tcp_inet6_sk(sk)->min_hopcount))) {
+			__NET_INC_STATS(net, LINUX_MIB_TCPMINTTLDROP);
+			drop_reason = SKB_DROP_REASON_TCP_MINTTL;
+			goto discard_and_relse;
+		}
+	}
+
+	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb)) {
+		drop_reason = SKB_DROP_REASON_XFRM_POLICY;
+		goto discard_and_relse;
+	}
+
+	drop_reason = tcp_inbound_md5_hash(sk, skb, &hdr->saddr, &hdr->daddr,
+					   AF_INET6, dif, sdif);
+	if (drop_reason)
+		goto discard_and_relse;
+
+	nf_reset_ct(skb);
+
+	if (tcp_filter(sk, skb)) {
+		drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
+		goto discard_and_relse;
+	}
+	th = (const struct tcphdr *)skb->data;
+	hdr = ipv6_hdr(skb);
+	tcp_v6_fill_cb(skb, hdr, th);
+
+	skb->dev = NULL;
+
+	if (sk->sk_state == TCP_LISTEN) {
+		ret = tcp_v6_do_rcv(sk, skb);
+		goto put_and_return;
+	}
+
+	sk_incoming_cpu_update(sk);
+
+	bh_lock_sock_nested(sk);
+	tcp_segs_in(tcp_sk(sk), skb);
+	ret = 0;
+	if (!sock_owned_by_user(sk)) {
+		ret = tcp_v6_do_rcv(sk, skb);
+	} else {
+		if (tcp_add_backlog(sk, skb, &drop_reason))
+			goto discard_and_relse;
+	}
+	bh_unlock_sock(sk);
+put_and_return:
+	if (refcounted)
+		sock_put(sk);
+	return ret ? -1 : 0;
+
+no_tcp_socket:
+	drop_reason = SKB_DROP_REASON_NO_SOCKET;
+	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
+		goto discard_it;
+
+	tcp_v6_fill_cb(skb, hdr, th);
+
+	if (tcp_checksum_complete(skb)) {
+csum_error:
+		drop_reason = SKB_DROP_REASON_TCP_CSUM;
+		trace_tcp_bad_csum(skb);
+		__TCP_INC_STATS(net, TCP_MIB_CSUMERRORS);
+bad_packet:
+		__TCP_INC_STATS(net, TCP_MIB_INERRS);
+	} else {
+		tcp_v6_send_reset(NULL, skb);
+	}
+
+discard_it:
+	SKB_DR_OR(drop_reason, NOT_SPECIFIED);
+	kfree_skb_reason(skb, drop_reason);
+	return 0;
+
+discard_and_relse:
+	sk_drops_add(sk, skb);
+	if (refcounted)
+		sock_put(sk);
+	goto discard_it;
+
+do_time_wait:
+	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
+		drop_reason = SKB_DROP_REASON_XFRM_POLICY;
+		inet_twsk_put(inet_twsk(sk));
+		goto discard_it;
+	}
+
+	tcp_v6_fill_cb(skb, hdr, th);
+
+	if (tcp_checksum_complete(skb)) {
+		inet_twsk_put(inet_twsk(sk));
+		goto csum_error;
+	}
+
+	switch (tcp_timewait_state_process(inet_twsk(sk), skb, th)) {
+	case TCP_TW_SYN:
+	{
+		struct sock *sk2;
+
+		sk2 = inet6_lookup_listener(net, net->ipv4.tcp_death_row.hashinfo,
+					    skb, __tcp_hdrlen(th),
+					    &ipv6_hdr(skb)->saddr, th->source,
+					    &ipv6_hdr(skb)->daddr,
+					    ntohs(th->dest),
+					    tcp_v6_iif_l3_slave(skb),
+					    sdif);
+		if (sk2) {
+			struct inet_timewait_sock *tw = inet_twsk(sk);
+			inet_twsk_deschedule_put(tw);
+			sk = sk2;
+			tcp_v6_restore_cb(skb);
+			refcounted = false;
+			goto process;
+		}
+	}
+		/* to ACK */
+		fallthrough;
+	case TCP_TW_ACK:
+		tcp_v6_timewait_ack(sk, skb);
+		break;
+	case TCP_TW_RST:
+		tcp_v6_send_reset(sk, skb);
+		inet_twsk_deschedule_put(inet_twsk(sk));
+		goto discard_it;
+	case TCP_TW_SUCCESS:
+		;
+	}
+	goto discard_it;
+}
+
+void tcp_v6_early_demux(struct sk_buff *skb)
+{
+	struct net *net = dev_net(skb->dev);
+	const struct ipv6hdr *hdr;
+	const struct tcphdr *th;
+	struct sock *sk;
+
+	if (skb->pkt_type != PACKET_HOST)
+		return;
+
+	if (!pskb_may_pull(skb, skb_transport_offset(skb) + sizeof(struct tcphdr)))
+		return;
+
+	hdr = ipv6_hdr(skb);
+	th = tcp_hdr(skb);
+
+	if (th->doff < sizeof(struct tcphdr) / 4)
+		return;
+
+	/* Note : We use inet6_iif() here, not tcp_v6_iif() */
+	sk = __inet6_lookup_established(net, net->ipv4.tcp_death_row.hashinfo,
+					&hdr->saddr, th->source,
+					&hdr->daddr, ntohs(th->dest),
+					inet6_iif(skb), inet6_sdif(skb));
+	if (sk) {
+		skb->sk = sk;
+		skb->destructor = sock_edemux;
+		if (sk_fullsock(sk)) {
+			struct dst_entry *dst = rcu_dereference(sk->sk_rx_dst);
+
+			if (dst)
+				dst = dst_check(dst, sk->sk_rx_dst_cookie);
+			if (dst &&
+			    sk->sk_rx_dst_ifindex == skb->skb_iif)
+				skb_dst_set_noref(skb, dst);
+		}
+	}
+}
+
+static struct timewait_sock_ops tcp6_timewait_sock_ops = {
+	.twsk_obj_size	= sizeof(struct tcp6_timewait_sock),
+	.twsk_unique	= tcp_twsk_unique,
+	.twsk_destructor = tcp_twsk_destructor,
+};
+
+INDIRECT_CALLABLE_SCOPE void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb)
+{
+	__tcp_v6_send_check(skb, &sk->sk_v6_rcv_saddr, &sk->sk_v6_daddr);
+}
+
+const struct inet_connection_sock_af_ops ipv6_specific = {
+	.queue_xmit	   = inet6_csk_xmit,
+	.send_check	   = tcp_v6_send_check,
+	.rebuild_header	   = inet6_sk_rebuild_header,
+	.sk_rx_dst_set	   = inet6_sk_rx_dst_set,
+	.conn_request	   = tcp_v6_conn_request,
+	.syn_recv_sock	   = tcp_v6_syn_recv_sock,
+	.net_header_len	   = sizeof(struct ipv6hdr),
+	.net_frag_header_len = sizeof(struct frag_hdr),
+	.setsockopt	   = ipv6_setsockopt,
+	.getsockopt	   = ipv6_getsockopt,
+	.addr2sockaddr	   = inet6_csk_addr2sockaddr,
+	.sockaddr_len	   = sizeof(struct sockaddr_in6),
+	.mtu_reduced	   = tcp_v6_mtu_reduced,
+};
+
+#ifdef CONFIG_TCP_MD5SIG
+static const struct tcp_sock_af_ops tcp_sock_ipv6_specific = {
+	.md5_lookup	=	tcp_v6_md5_lookup,
+	.calc_md5_hash	=	tcp_v6_md5_hash_skb,
+	.md5_parse	=	tcp_v6_parse_md5_keys,
+};
+#endif
+
+/*
+ *	TCP over IPv4 via INET6 API
+ */
+static const struct inet_connection_sock_af_ops ipv6_mapped = {
+	.queue_xmit	   = ip_queue_xmit,
+	.send_check	   = tcp_v4_send_check,
+	.rebuild_header	   = inet_sk_rebuild_header,
+	.sk_rx_dst_set	   = inet_sk_rx_dst_set,
+	.conn_request	   = tcp_v6_conn_request,
+	.syn_recv_sock	   = tcp_v6_syn_recv_sock,
+	.net_header_len	   = sizeof(struct iphdr),
+	.setsockopt	   = ipv6_setsockopt,
+	.getsockopt	   = ipv6_getsockopt,
+	.addr2sockaddr	   = inet6_csk_addr2sockaddr,
+	.sockaddr_len	   = sizeof(struct sockaddr_in6),
+	.mtu_reduced	   = tcp_v4_mtu_reduced,
+};
+
+#ifdef CONFIG_TCP_MD5SIG
+static const struct tcp_sock_af_ops tcp_sock_ipv6_mapped_specific = {
+	.md5_lookup	=	tcp_v4_md5_lookup,
+	.calc_md5_hash	=	tcp_v4_md5_hash_skb,
+	.md5_parse	=	tcp_v6_parse_md5_keys,
+};
+#endif
+
+/* NOTE: A lot of things set to zero explicitly by call to
+ *       sk_alloc() so need not be done here.
+ */
+static int tcp_v6_init_sock(struct sock *sk)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+
+	tcp_init_sock(sk);
+
+	icsk->icsk_af_ops = &ipv6_specific;
+
+#ifdef CONFIG_TCP_MD5SIG
+	tcp_sk(sk)->af_specific = &tcp_sock_ipv6_specific;
+#endif
+
+	return 0;
+}
+
+#ifdef CONFIG_PROC_FS
+/* Proc filesystem TCPv6 sock list dumping. */
+static void get_openreq6(struct seq_file *seq,
+			 const struct request_sock *req, int i)
+{
+	long ttd = req->rsk_timer.expires - jiffies;
+	const struct in6_addr *src = &inet_rsk(req)->ir_v6_loc_addr;
+	const struct in6_addr *dest = &inet_rsk(req)->ir_v6_rmt_addr;
+
+	if (ttd < 0)
+		ttd = 0;
+
+	seq_printf(seq,
+		   "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
+		   "%02X %08X:%08X %02X:%08lX %08X %5u %8d %d %d %pK\n",
+		   i,
+		   src->s6_addr32[0], src->s6_addr32[1],
+		   src->s6_addr32[2], src->s6_addr32[3],
+		   inet_rsk(req)->ir_num,
+		   dest->s6_addr32[0], dest->s6_addr32[1],
+		   dest->s6_addr32[2], dest->s6_addr32[3],
+		   ntohs(inet_rsk(req)->ir_rmt_port),
+		   TCP_SYN_RECV,
+		   0, 0, /* could print option size, but that is af dependent. */
+		   1,   /* timers active (only the expire timer) */
+		   jiffies_to_clock_t(ttd),
+		   req->num_timeout,
+		   from_kuid_munged(seq_user_ns(seq),
+				    sock_i_uid(req->rsk_listener)),
+		   0,  /* non standard timer */
+		   0, /* open_requests have no inode */
+		   0, req);
+}
+
+static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
+{
+	const struct in6_addr *dest, *src;
+	__u16 destp, srcp;
+	int timer_active;
+	unsigned long timer_expires;
+	const struct inet_sock *inet = inet_sk(sp);
+	const struct tcp_sock *tp = tcp_sk(sp);
+	const struct inet_connection_sock *icsk = inet_csk(sp);
+	const struct fastopen_queue *fastopenq = &icsk->icsk_accept_queue.fastopenq;
+	int rx_queue;
+	int state;
+
+	dest  = &sp->sk_v6_daddr;
+	src   = &sp->sk_v6_rcv_saddr;
+	destp = ntohs(inet->inet_dport);
+	srcp  = ntohs(inet->inet_sport);
+
+	if (icsk->icsk_pending == ICSK_TIME_RETRANS ||
+	    icsk->icsk_pending == ICSK_TIME_REO_TIMEOUT ||
+	    icsk->icsk_pending == ICSK_TIME_LOSS_PROBE) {
+		timer_active	= 1;
+		timer_expires	= icsk->icsk_timeout;
+	} else if (icsk->icsk_pending == ICSK_TIME_PROBE0) {
+		timer_active	= 4;
+		timer_expires	= icsk->icsk_timeout;
+	} else if (timer_pending(&sp->sk_timer)) {
+		timer_active	= 2;
+		timer_expires	= sp->sk_timer.expires;
+	} else {
+		timer_active	= 0;
+		timer_expires = jiffies;
+	}
+
+	state = inet_sk_state_load(sp);
+	if (state == TCP_LISTEN)
+		rx_queue = READ_ONCE(sp->sk_ack_backlog);
+	else
+		/* Because we don't lock the socket,
+		 * we might find a transient negative value.
+		 */
+		rx_queue = max_t(int, READ_ONCE(tp->rcv_nxt) -
+				      READ_ONCE(tp->copied_seq), 0);
+
+	seq_printf(seq,
+		   "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
+		   "%02X %08X:%08X %02X:%08lX %08X %5u %8d %lu %d %pK %lu %lu %u %u %d\n",
+		   i,
+		   src->s6_addr32[0], src->s6_addr32[1],
+		   src->s6_addr32[2], src->s6_addr32[3], srcp,
+		   dest->s6_addr32[0], dest->s6_addr32[1],
+		   dest->s6_addr32[2], dest->s6_addr32[3], destp,
+		   state,
+		   READ_ONCE(tp->write_seq) - tp->snd_una,
+		   rx_queue,
+		   timer_active,
+		   jiffies_delta_to_clock_t(timer_expires - jiffies),
+		   icsk->icsk_retransmits,
+		   from_kuid_munged(seq_user_ns(seq), sock_i_uid(sp)),
+		   icsk->icsk_probes_out,
+		   sock_i_ino(sp),
+		   refcount_read(&sp->sk_refcnt), sp,
+		   jiffies_to_clock_t(icsk->icsk_rto),
+		   jiffies_to_clock_t(icsk->icsk_ack.ato),
+		   (icsk->icsk_ack.quick << 1) | inet_csk_in_pingpong_mode(sp),
+		   tcp_snd_cwnd(tp),
+		   state == TCP_LISTEN ?
+			fastopenq->max_qlen :
+			(tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh)
+		   );
+}
+
+static void get_timewait6_sock(struct seq_file *seq,
+			       struct inet_timewait_sock *tw, int i)
+{
+	long delta = tw->tw_timer.expires - jiffies;
+	const struct in6_addr *dest, *src;
+	__u16 destp, srcp;
+
+	dest = &tw->tw_v6_daddr;
+	src  = &tw->tw_v6_rcv_saddr;
+	destp = ntohs(tw->tw_dport);
+	srcp  = ntohs(tw->tw_sport);
+
+	seq_printf(seq,
+		   "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
+		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK\n",
+		   i,
+		   src->s6_addr32[0], src->s6_addr32[1],
+		   src->s6_addr32[2], src->s6_addr32[3], srcp,
+		   dest->s6_addr32[0], dest->s6_addr32[1],
+		   dest->s6_addr32[2], dest->s6_addr32[3], destp,
+		   tw->tw_substate, 0, 0,
+		   3, jiffies_delta_to_clock_t(delta), 0, 0, 0, 0,
+		   refcount_read(&tw->tw_refcnt), tw);
+}
+
+static int tcp6_seq_show(struct seq_file *seq, void *v)
+{
+	struct tcp_iter_state *st;
+	struct sock *sk = v;
+
+	if (v == SEQ_START_TOKEN) {
+		seq_puts(seq,
+			 "  sl  "
+			 "local_address                         "
+			 "remote_address                        "
+			 "st tx_queue rx_queue tr tm->when retrnsmt"
+			 "   uid  timeout inode\n");
+		goto out;
+	}
+	st = seq->private;
+
+	if (sk->sk_state == TCP_TIME_WAIT)
+		get_timewait6_sock(seq, v, st->num);
+	else if (sk->sk_state == TCP_NEW_SYN_RECV)
+		get_openreq6(seq, v, st->num);
+	else
+		get_tcp6_sock(seq, v, st->num);
+out:
+	return 0;
+}
+
+static const struct seq_operations tcp6_seq_ops = {
+	.show		= tcp6_seq_show,
+	.start		= tcp_seq_start,
+	.next		= tcp_seq_next,
+	.stop		= tcp_seq_stop,
+};
+
+static struct tcp_seq_afinfo tcp6_seq_afinfo = {
+	.family		= AF_INET6,
+};
+
+int __net_init tcp6_proc_init(struct net *net)
+{
+	if (!proc_create_net_data("tcp6", 0444, net->proc_net, &tcp6_seq_ops,
+			sizeof(struct tcp_iter_state), &tcp6_seq_afinfo))
+		return -ENOMEM;
+	return 0;
+}
+
+void tcp6_proc_exit(struct net *net)
+{
+	remove_proc_entry("tcp6", net->proc_net);
+}
+#endif
+
+struct proto tcpv6_prot = {
+	.name			= "TCPv6",
+	.owner			= THIS_MODULE,
+	.close			= tcp_close,
+	.pre_connect		= tcp_v6_pre_connect,
+	.connect		= tcp_v6_connect,
+	.disconnect		= tcp_disconnect,
+	.accept			= inet_csk_accept,
+	.ioctl			= tcp_ioctl,
+	.init			= tcp_v6_init_sock,
+	.destroy		= tcp_v4_destroy_sock,
+	.shutdown		= tcp_shutdown,
+	.setsockopt		= tcp_setsockopt,
+	.getsockopt		= tcp_getsockopt,
+	.bpf_bypass_getsockopt	= tcp_bpf_bypass_getsockopt,
+	.keepalive		= tcp_set_keepalive,
+	.recvmsg		= tcp_recvmsg,
+	.sendmsg		= tcp_sendmsg,
+	.splice_eof		= tcp_splice_eof,
+	.backlog_rcv		= tcp_v6_do_rcv,
+	.release_cb		= tcp_release_cb,
+	.hash			= inet6_hash,
+	.unhash			= inet_unhash,
+	.get_port		= inet_csk_get_port,
+	.put_port		= inet_put_port,
+#ifdef CONFIG_BPF_SYSCALL
+	.psock_update_sk_prot	= tcp_bpf_update_proto,
+#endif
+	.enter_memory_pressure	= tcp_enter_memory_pressure,
+	.leave_memory_pressure	= tcp_leave_memory_pressure,
+	.stream_memory_free	= tcp_stream_memory_free,
+	.sockets_allocated	= &tcp_sockets_allocated,
+
+	.memory_allocated	= &tcp_memory_allocated,
+	.per_cpu_fw_alloc	= &tcp_memory_per_cpu_fw_alloc,
+
+	.memory_pressure	= &tcp_memory_pressure,
+	.orphan_count		= &tcp_orphan_count,
+	.sysctl_mem		= sysctl_tcp_mem,
+	.sysctl_wmem_offset	= offsetof(struct net, ipv4.sysctl_tcp_wmem),
+	.sysctl_rmem_offset	= offsetof(struct net, ipv4.sysctl_tcp_rmem),
+	.max_header		= MAX_TCP_HEADER,
+	.obj_size		= sizeof(struct tcp6_sock),
+	.ipv6_pinfo_offset = offsetof(struct tcp6_sock, inet6),
+	.slab_flags		= SLAB_TYPESAFE_BY_RCU,
+	.twsk_prot		= &tcp6_timewait_sock_ops,
+	.rsk_prot		= &tcp6_request_sock_ops,
+	.h.hashinfo		= NULL,
+	.no_autobind		= true,
+	.diag_destroy		= tcp_abort,
+};
+EXPORT_SYMBOL_GPL(tcpv6_prot);
+
+static const struct inet6_protocol tcpv6_protocol = {
+	.handler	=	tcp_v6_rcv,
+	.err_handler	=	tcp_v6_err,
+	.flags		=	INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
+};
+
+static struct inet_protosw tcpv6_protosw = {
+	.type		=	SOCK_STREAM,
+	.protocol	=	IPPROTO_TCP,
+	.prot		=	&tcpv6_prot,
+	.ops		=	&inet6_stream_ops,
+	.flags		=	INET_PROTOSW_PERMANENT |
+				INET_PROTOSW_ICSK,
+};
+
+static int __net_init tcpv6_net_init(struct net *net)
+{
+	return inet_ctl_sock_create(&net->ipv6.tcp_sk, PF_INET6,
+				    SOCK_RAW, IPPROTO_TCP, net);
+}
+
+static void __net_exit tcpv6_net_exit(struct net *net)
+{
+	inet_ctl_sock_destroy(net->ipv6.tcp_sk);
+}
+
+static void __net_exit tcpv6_net_exit_batch(struct list_head *net_exit_list)
+{
+	tcp_twsk_purge(net_exit_list, AF_INET6);
+}
+
+static struct pernet_operations tcpv6_net_ops = {
+	.init	    = tcpv6_net_init,
+	.exit	    = tcpv6_net_exit,
+	.exit_batch = tcpv6_net_exit_batch,
+};
+
+int __init tcpv6_init(void)
+{
+	int ret;
+
+	ret = inet6_add_protocol(&tcpv6_protocol, IPPROTO_TCP);
+	if (ret)
+		goto out;
+
+	/* register inet6 protocol */
+	ret = inet6_register_protosw(&tcpv6_protosw);
+	if (ret)
+		goto out_tcpv6_protocol;
+
+	ret = register_pernet_subsys(&tcpv6_net_ops);
+	if (ret)
+		goto out_tcpv6_protosw;
+
+	ret = mptcpv6_init();
+	if (ret)
+		goto out_tcpv6_pernet_subsys;
+
+out:
+	return ret;
+
+out_tcpv6_pernet_subsys:
+	unregister_pernet_subsys(&tcpv6_net_ops);
+out_tcpv6_protosw:
+	inet6_unregister_protosw(&tcpv6_protosw);
+out_tcpv6_protocol:
+	inet6_del_protocol(&tcpv6_protocol, IPPROTO_TCP);
+	goto out;
+}
+
+void tcpv6_exit(void)
+{
+	unregister_pernet_subsys(&tcpv6_net_ops);
+	inet6_unregister_protosw(&tcpv6_protosw);
+	inet6_del_protocol(&tcpv6_protocol, IPPROTO_TCP);
+}