Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next

This merges (3f509c6 netfilter: nf_nat_sip: fix incorrect handling
of EBUSY for RTCP expectation) to Patrick McHardy's IPv6 NAT changes.

21 files changed, 760 insertions, 129 deletions

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 6681ccf..4f70ef0 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -149,6 +149,11 @@ void inet_sock_destruct(struct sock *sk)
 		pr_err("Attempt to release alive inet socket %p\n", sk);
 		return;
 	}
+	if (sk->sk_type == SOCK_STREAM) {
+		struct fastopen_queue *fastopenq =
+			inet_csk(sk)->icsk_accept_queue.fastopenq;
+		kfree(fastopenq);
+	}
 
 	WARN_ON(atomic_read(&sk->sk_rmem_alloc));
 	WARN_ON(atomic_read(&sk->sk_wmem_alloc));
@@ -212,6 +217,26 @@ int inet_listen(struct socket *sock, int backlog)
 	 * we can only allow the backlog to be adjusted.
 	 */
 	if (old_state != TCP_LISTEN) {
+		/* Check special setups for testing purpose to enable TFO w/o
+		 * requiring TCP_FASTOPEN sockopt.
+		 * Note that only TCP sockets (SOCK_STREAM) will reach here.
+		 * Also fastopenq may already been allocated because this
+		 * socket was in TCP_LISTEN state previously but was
+		 * shutdown() (rather than close()).
+		 */
+		if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) != 0 &&
+		    inet_csk(sk)->icsk_accept_queue.fastopenq == NULL) {
+			if ((sysctl_tcp_fastopen & TFO_SERVER_WO_SOCKOPT1) != 0)
+				err = fastopen_init_queue(sk, backlog);
+			else if ((sysctl_tcp_fastopen &
+				  TFO_SERVER_WO_SOCKOPT2) != 0)
+				err = fastopen_init_queue(sk,
+				    ((uint)sysctl_tcp_fastopen) >> 16);
+			else
+				err = 0;
+			if (err)
+				goto out;
+		}
 		err = inet_csk_listen_start(sk, backlog);
 		if (err)
 			goto out;
@@ -701,7 +726,8 @@ int inet_accept(struct socket *sock, struct socket *newsock, int flags)
 
 	sock_rps_record_flow(sk2);
 	WARN_ON(!((1 << sk2->sk_state) &
-		  (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT | TCPF_CLOSE)));
+		  (TCPF_ESTABLISHED | TCPF_SYN_RECV |
+		  TCPF_CLOSE_WAIT | TCPF_CLOSE)));
 
 	sock_graft(sk2, newsock);
 
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 6a5e6e4..adf273f 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1147,12 +1147,8 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
 			 void *ptr)
 {
 	struct net_device *dev = ptr;
-	struct in_device *in_dev;
-
-	if (event == NETDEV_UNREGISTER_FINAL)
-		goto out;
+	struct in_device *in_dev = __in_dev_get_rtnl(dev);
 
-	in_dev = __in_dev_get_rtnl(dev);
 	ASSERT_RTNL();
 
 	if (!in_dev) {
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index fd7d9ae..acdee32 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1050,9 +1050,6 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo
 		return NOTIFY_DONE;
 	}
 
-	if (event == NETDEV_UNREGISTER_FINAL)
-		return NOTIFY_DONE;
-
 	in_dev = __in_dev_get_rtnl(dev);
 
 	switch (event) {
@@ -1064,14 +1061,14 @@ static int fib_netdev_event(struct notifier_block *this, unsigned long event, vo
 		fib_sync_up(dev);
 #endif
 		atomic_inc(&net->ipv4.dev_addr_genid);
-		rt_cache_flush(dev_net(dev), -1);
+		rt_cache_flush(net, -1);
 		break;
 	case NETDEV_DOWN:
 		fib_disable_ip(dev, 0, 0);
 		break;
 	case NETDEV_CHANGEMTU:
 	case NETDEV_CHANGE:
-		rt_cache_flush(dev_net(dev), 0);
+		rt_cache_flush(net, 0);
 		break;
 	}
 	return NOTIFY_DONE;
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 7f75f21..8464b79 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -283,7 +283,9 @@ static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 	struct sock *newsk;
+	struct request_sock *req;
 	int error;
 
 	lock_sock(sk);
@@ -296,7 +298,7 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
 		goto out_err;
 
 	/* Find already established connection */
-	if (reqsk_queue_empty(&icsk->icsk_accept_queue)) {
+	if (reqsk_queue_empty(queue)) {
 		long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 
 		/* If this is a non blocking socket don't sleep */
@@ -308,14 +310,32 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
 		if (error)
 			goto out_err;
 	}
-
-	newsk = reqsk_queue_get_child(&icsk->icsk_accept_queue, sk);
-	WARN_ON(newsk->sk_state == TCP_SYN_RECV);
+	req = reqsk_queue_remove(queue);
+	newsk = req->sk;
+
+	sk_acceptq_removed(sk);
+	if (sk->sk_type == SOCK_STREAM && queue->fastopenq != NULL) {
+		spin_lock_bh(&queue->fastopenq->lock);
+		if (tcp_rsk(req)->listener) {
+			/* We are still waiting for the final ACK from 3WHS
+			 * so can't free req now. Instead, we set req->sk to
+			 * NULL to signify that the child socket is taken
+			 * so reqsk_fastopen_remove() will free the req
+			 * when 3WHS finishes (or is aborted).
+			 */
+			req->sk = NULL;
+			req = NULL;
+		}
+		spin_unlock_bh(&queue->fastopenq->lock);
+	}
 out:
 	release_sock(sk);
+	if (req)
+		__reqsk_free(req);
 	return newsk;
 out_err:
 	newsk = NULL;
+	req = NULL;
 	*err = error;
 	goto out;
 }
@@ -720,13 +740,14 @@ EXPORT_SYMBOL_GPL(inet_csk_listen_start);
 void inet_csk_listen_stop(struct sock *sk)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 	struct request_sock *acc_req;
 	struct request_sock *req;
 
 	inet_csk_delete_keepalive_timer(sk);
 
 	/* make all the listen_opt local to us */
-	acc_req = reqsk_queue_yank_acceptq(&icsk->icsk_accept_queue);
+	acc_req = reqsk_queue_yank_acceptq(queue);
 
 	/* Following specs, it would be better either to send FIN
 	 * (and enter FIN-WAIT-1, it is normal close)
@@ -736,7 +757,7 @@ void inet_csk_listen_stop(struct sock *sk)
 	 * To be honest, we are not able to make either
 	 * of the variants now.			--ANK
 	 */
-	reqsk_queue_destroy(&icsk->icsk_accept_queue);
+	reqsk_queue_destroy(queue);
 
 	while ((req = acc_req) != NULL) {
 		struct sock *child = req->sk;
@@ -754,6 +775,19 @@ void inet_csk_listen_stop(struct sock *sk)
 
 		percpu_counter_inc(sk->sk_prot->orphan_count);
 
+		if (sk->sk_type == SOCK_STREAM && tcp_rsk(req)->listener) {
+			BUG_ON(tcp_sk(child)->fastopen_rsk != req);
+			BUG_ON(sk != tcp_rsk(req)->listener);
+
+			/* Paranoid, to prevent race condition if
+			 * an inbound pkt destined for child is
+			 * blocked by sock lock in tcp_v4_rcv().
+			 * Also to satisfy an assertion in
+			 * tcp_v4_destroy_sock().
+			 */
+			tcp_sk(child)->fastopen_rsk = NULL;
+			sock_put(sk);
+		}
 		inet_csk_destroy_sock(child);
 
 		bh_unlock_sock(child);
@@ -763,6 +797,17 @@ void inet_csk_listen_stop(struct sock *sk)
 		sk_acceptq_removed(sk);
 		__reqsk_free(req);
 	}
+	if (queue->fastopenq != NULL) {
+		/* Free all the reqs queued in rskq_rst_head. */
+		spin_lock_bh(&queue->fastopenq->lock);
+		acc_req = queue->fastopenq->rskq_rst_head;
+		queue->fastopenq->rskq_rst_head = NULL;
+		spin_unlock_bh(&queue->fastopenq->lock);
+		while ((req = acc_req) != NULL) {
+			acc_req = req->dl_next;
+			__reqsk_free(req);
+		}
+	}
 	WARN_ON(sk->sk_ack_backlog);
 }
 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 570e61f..8bc005b 100644
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -69,6 +69,7 @@ static inline void inet_diag_unlock_handler(
 
 int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
 			      struct sk_buff *skb, struct inet_diag_req_v2 *req,
+			      struct user_namespace *user_ns,		      	
 			      u32 pid, u32 seq, u16 nlmsg_flags,
 			      const struct nlmsghdr *unlh)
 {
@@ -124,7 +125,7 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
 	}
 #endif
 
-	r->idiag_uid = sock_i_uid(sk);
+	r->idiag_uid = from_kuid_munged(user_ns, sock_i_uid(sk));
 	r->idiag_inode = sock_i_ino(sk);
 
 	if (ext & (1 << (INET_DIAG_MEMINFO - 1))) {
@@ -199,11 +200,12 @@ EXPORT_SYMBOL_GPL(inet_sk_diag_fill);
 
 static int inet_csk_diag_fill(struct sock *sk,
 			      struct sk_buff *skb, struct inet_diag_req_v2 *req,
+			      struct user_namespace *user_ns,
 			      u32 pid, u32 seq, u16 nlmsg_flags,
 			      const struct nlmsghdr *unlh)
 {
 	return inet_sk_diag_fill(sk, inet_csk(sk),
-			skb, req, pid, seq, nlmsg_flags, unlh);
+			skb, req, user_ns, pid, seq, nlmsg_flags, unlh);
 }
 
 static int inet_twsk_diag_fill(struct inet_timewait_sock *tw,
@@ -256,14 +258,16 @@ static int inet_twsk_diag_fill(struct inet_timewait_sock *tw,
 }
 
 static int sk_diag_fill(struct sock *sk, struct sk_buff *skb,
-			struct inet_diag_req_v2 *r, u32 pid, u32 seq, u16 nlmsg_flags,
+			struct inet_diag_req_v2 *r,
+			struct user_namespace *user_ns,
+			u32 pid, u32 seq, u16 nlmsg_flags,
 			const struct nlmsghdr *unlh)
 {
 	if (sk->sk_state == TCP_TIME_WAIT)
 		return inet_twsk_diag_fill((struct inet_timewait_sock *)sk,
 					   skb, r, pid, seq, nlmsg_flags,
 					   unlh);
-	return inet_csk_diag_fill(sk, skb, r, pid, seq, nlmsg_flags, unlh);
+	return inet_csk_diag_fill(sk, skb, r, user_ns, pid, seq, nlmsg_flags, unlh);
 }
 
 int inet_diag_dump_one_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *in_skb,
@@ -311,6 +315,7 @@ int inet_diag_dump_one_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *in_s
 	}
 
 	err = sk_diag_fill(sk, rep, req,
+			   sk_user_ns(NETLINK_CB(in_skb).ssk),
 			   NETLINK_CB(in_skb).pid,
 			   nlh->nlmsg_seq, 0, nlh);
 	if (err < 0) {
@@ -551,6 +556,7 @@ static int inet_csk_diag_dump(struct sock *sk,
 		return 0;
 
 	return inet_csk_diag_fill(sk, skb, r,
+				  sk_user_ns(NETLINK_CB(cb->skb).ssk),
 				  NETLINK_CB(cb->skb).pid,
 				  cb->nlh->nlmsg_seq, NLM_F_MULTI, cb->nlh);
 }
@@ -591,7 +597,9 @@ static int inet_twsk_diag_dump(struct inet_timewait_sock *tw,
 }
 
 static int inet_diag_fill_req(struct sk_buff *skb, struct sock *sk,
-			      struct request_sock *req, u32 pid, u32 seq,
+			      struct request_sock *req,
+			      struct user_namespace *user_ns,
+			      u32 pid, u32 seq,
 			      const struct nlmsghdr *unlh)
 {
 	const struct inet_request_sock *ireq = inet_rsk(req);
@@ -625,7 +633,7 @@ static int inet_diag_fill_req(struct sk_buff *skb, struct sock *sk,
 	r->idiag_expires = jiffies_to_msecs(tmo);
 	r->idiag_rqueue = 0;
 	r->idiag_wqueue = 0;
-	r->idiag_uid = sock_i_uid(sk);
+	r->idiag_uid = from_kuid_munged(user_ns, sock_i_uid(sk));
 	r->idiag_inode = 0;
 #if IS_ENABLED(CONFIG_IPV6)
 	if (r->idiag_family == AF_INET6) {
@@ -702,6 +710,7 @@ static int inet_diag_dump_reqs(struct sk_buff *skb, struct sock *sk,
 			}
 
 			err = inet_diag_fill_req(skb, sk, req,
+					       sk_user_ns(NETLINK_CB(cb->skb).ssk),
 					       NETLINK_CB(cb->skb).pid,
 					       cb->nlh->nlmsg_seq, cb->nlh);
 			if (err < 0) {
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 3a57570..8aa7a4c 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -124,6 +124,8 @@ static DEFINE_SPINLOCK(mfc_unres_lock);
 static struct kmem_cache *mrt_cachep __read_mostly;
 
 static struct mr_table *ipmr_new_table(struct net *net, u32 id);
+static void ipmr_free_table(struct mr_table *mrt);
+
 static int ip_mr_forward(struct net *net, struct mr_table *mrt,
 			 struct sk_buff *skb, struct mfc_cache *cache,
 			 int local);
@@ -131,6 +133,7 @@ static int ipmr_cache_report(struct mr_table *mrt,
 			     struct sk_buff *pkt, vifi_t vifi, int assert);
 static int __ipmr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb,
 			      struct mfc_cache *c, struct rtmsg *rtm);
+static void mroute_clean_tables(struct mr_table *mrt);
 static void ipmr_expire_process(unsigned long arg);
 
 #ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
@@ -271,7 +274,7 @@ static void __net_exit ipmr_rules_exit(struct net *net)
 
 	list_for_each_entry_safe(mrt, next, &net->ipv4.mr_tables, list) {
 		list_del(&mrt->list);
-		kfree(mrt);
+		ipmr_free_table(mrt);
 	}
 	fib_rules_unregister(net->ipv4.mr_rules_ops);
 }
@@ -299,7 +302,7 @@ static int __net_init ipmr_rules_init(struct net *net)
 
 static void __net_exit ipmr_rules_exit(struct net *net)
 {
-	kfree(net->ipv4.mrt);
+	ipmr_free_table(net->ipv4.mrt);
 }
 #endif
 
@@ -336,6 +339,13 @@ static struct mr_table *ipmr_new_table(struct net *net, u32 id)
 	return mrt;
 }
 
+static void ipmr_free_table(struct mr_table *mrt)
+{
+	del_timer_sync(&mrt->ipmr_expire_timer);
+	mroute_clean_tables(mrt);
+	kfree(mrt);
+}
+
 /* Service routines creating virtual interfaces: DVMRP tunnels and PIMREG */
 
 static void ipmr_del_tunnel(struct net_device *dev, struct vifctl *v)
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 6232d47..8f3d054 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -185,10 +185,10 @@ exit:
 	return sk;
 }
 
-static void inet_get_ping_group_range_net(struct net *net, gid_t *low,
-					  gid_t *high)
+static void inet_get_ping_group_range_net(struct net *net, kgid_t *low,
+					  kgid_t *high)
 {
-	gid_t *data = net->ipv4.sysctl_ping_group_range;
+	kgid_t *data = net->ipv4.sysctl_ping_group_range;
 	unsigned int seq;
 
 	do {
@@ -203,19 +203,13 @@ static void inet_get_ping_group_range_net(struct net *net, gid_t *low,
 static int ping_init_sock(struct sock *sk)
 {
 	struct net *net = sock_net(sk);
-	gid_t group = current_egid();
-	gid_t range[2];
+	kgid_t group = current_egid();
 	struct group_info *group_info = get_current_groups();
 	int i, j, count = group_info->ngroups;
 	kgid_t low, high;
 
-	inet_get_ping_group_range_net(net, range, range+1);
-	low = make_kgid(&init_user_ns, range[0]);
-	high = make_kgid(&init_user_ns, range[1]);
-	if (!gid_valid(low) || !gid_valid(high) || gid_lt(high, low))
-		return -EACCES;
-
-	if (range[0] <= group && group <= range[1])
+	inet_get_ping_group_range_net(net, &low, &high);
+	if (gid_lte(low, group) && gid_lte(group, high))
 		return 0;
 
 	for (i = 0; i < group_info->nblocks; i++) {
@@ -845,7 +839,9 @@ static void ping_format_sock(struct sock *sp, struct seq_file *f,
 		bucket, src, srcp, dest, destp, sp->sk_state,
 		sk_wmem_alloc_get(sp),
 		sk_rmem_alloc_get(sp),
-		0, 0L, 0, sock_i_uid(sp), 0, sock_i_ino(sp),
+		0, 0L, 0,
+		from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
+		0, sock_i_ino(sp),
 		atomic_read(&sp->sk_refcnt), sp,
 		atomic_read(&sp->sk_drops), len);
 }
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 957acd1..8de53e1 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -263,6 +263,10 @@ static const struct snmp_mib snmp4_net_list[] = {
 	SNMP_MIB_ITEM("TCPChallengeACK", LINUX_MIB_TCPCHALLENGEACK),
 	SNMP_MIB_ITEM("TCPSYNChallenge", LINUX_MIB_TCPSYNCHALLENGE),
 	SNMP_MIB_ITEM("TCPFastOpenActive", LINUX_MIB_TCPFASTOPENACTIVE),
+	SNMP_MIB_ITEM("TCPFastOpenPassive", LINUX_MIB_TCPFASTOPENPASSIVE),
+	SNMP_MIB_ITEM("TCPFastOpenPassiveFail", LINUX_MIB_TCPFASTOPENPASSIVEFAIL),
+	SNMP_MIB_ITEM("TCPFastOpenListenOverflow", LINUX_MIB_TCPFASTOPENLISTENOVERFLOW),
+	SNMP_MIB_ITEM("TCPFastOpenCookieReqd", LINUX_MIB_TCPFASTOPENCOOKIEREQD),
 	SNMP_MIB_SENTINEL
 };
 
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index ff0f071..f242578 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -992,7 +992,9 @@ static void raw_sock_seq_show(struct seq_file *seq, struct sock *sp, int i)
 		i, src, srcp, dest, destp, sp->sk_state,
 		sk_wmem_alloc_get(sp),
 		sk_rmem_alloc_get(sp),
-		0, 0L, 0, sock_i_uid(sp), 0, sock_i_ino(sp),
+		0, 0L, 0,
+		from_kuid_munged(seq_user_ns(seq), sock_i_uid(sp)),
+		0, sock_i_ino(sp),
 		atomic_read(&sp->sk_refcnt), sp, atomic_read(&sp->sk_drops));
 }
 
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 50f6d3a..dc9549b 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -934,12 +934,14 @@ static u32 __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
 	if (mtu < ip_rt_min_pmtu)
 		mtu = ip_rt_min_pmtu;
 
+	rcu_read_lock();
 	if (fib_lookup(dev_net(rt->dst.dev), fl4, &res) == 0) {
 		struct fib_nh *nh = &FIB_RES_NH(res);
 
 		update_or_create_fnhe(nh, fl4->daddr, 0, mtu,
 				      jiffies + ip_rt_mtu_expires);
 	}
+	rcu_read_unlock();
 	return mtu;
 }
 
@@ -956,7 +958,7 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 		dst->obsolete = DST_OBSOLETE_KILL;
 	} else {
 		rt->rt_pmtu = mtu;
-		dst_set_expires(&rt->dst, ip_rt_mtu_expires);
+		rt->dst.expires = max(1UL, jiffies + ip_rt_mtu_expires);
 	}
 }
 
@@ -1132,10 +1134,7 @@ static unsigned int ipv4_mtu(const struct dst_entry *dst)
 	const struct rtable *rt = (const struct rtable *) dst;
 	unsigned int mtu = rt->rt_pmtu;
 
-	if (mtu && time_after_eq(jiffies, rt->dst.expires))
-		mtu = 0;
-
-	if (!mtu)
+	if (!mtu || time_after_eq(jiffies, rt->dst.expires))
 		mtu = dst_metric_raw(dst, RTAX_MTU);
 
 	if (mtu && rt_is_output_route(rt))
@@ -1263,7 +1262,7 @@ static void ipv4_dst_destroy(struct dst_entry *dst)
 {
 	struct rtable *rt = (struct rtable *) dst;
 
-	if (dst->flags & DST_NOCACHE) {
+	if (!list_empty(&rt->rt_uncached)) {
 		spin_lock_bh(&rt_uncached_lock);
 		list_del(&rt->rt_uncached);
 		spin_unlock_bh(&rt_uncached_lock);
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 650e152..ba48e79 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -319,6 +319,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
 	ireq->tstamp_ok		= tcp_opt.saw_tstamp;
 	req->ts_recent		= tcp_opt.saw_tstamp ? tcp_opt.rcv_tsval : 0;
 	treq->snt_synack	= tcp_opt.saw_tstamp ? tcp_opt.rcv_tsecr : 0;
+	treq->listener		= NULL;
 
 	/* We throwed the options of the initial SYN away, so we hope
 	 * the ACK carries the same options again (see RFC1122 4.2.3.8)
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 1b5ce96..9205e49 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -76,9 +76,9 @@ static int ipv4_local_port_range(ctl_table *table, int write,
 }
 
 
-static void inet_get_ping_group_range_table(struct ctl_table *table, gid_t *low, gid_t *high)
+static void inet_get_ping_group_range_table(struct ctl_table *table, kgid_t *low, kgid_t *high)
 {
-	gid_t *data = table->data;
+	kgid_t *data = table->data;
 	unsigned int seq;
 	do {
 		seq = read_seqbegin(&sysctl_local_ports.lock);
@@ -89,12 +89,12 @@ static void inet_get_ping_group_range_table(struct ctl_table *table, gid_t *low,
 }
 
 /* Update system visible IP port range */
-static void set_ping_group_range(struct ctl_table *table, gid_t range[2])
+static void set_ping_group_range(struct ctl_table *table, kgid_t low, kgid_t high)
 {
-	gid_t *data = table->data;
+	kgid_t *data = table->data;
 	write_seqlock(&sysctl_local_ports.lock);
-	data[0] = range[0];
-	data[1] = range[1];
+	data[0] = low;
+	data[1] = high;
 	write_sequnlock(&sysctl_local_ports.lock);
 }
 
@@ -103,21 +103,33 @@ static int ipv4_ping_group_range(ctl_table *table, int write,
 				 void __user *buffer,
 				 size_t *lenp, loff_t *ppos)
 {
+	struct user_namespace *user_ns = current_user_ns();
 	int ret;
-	gid_t range[2];
+	gid_t urange[2];
+	kgid_t low, high;
 	ctl_table tmp = {
-		.data = &range,
-		.maxlen = sizeof(range),
+		.data = &urange,
+		.maxlen = sizeof(urange),
 		.mode = table->mode,
 		.extra1 = &ip_ping_group_range_min,
 		.extra2 = &ip_ping_group_range_max,
 	};
 
-	inet_get_ping_group_range_table(table, range, range + 1);
+	inet_get_ping_group_range_table(table, &low, &high);
+	urange[0] = from_kgid_munged(user_ns, low);
+	urange[1] = from_kgid_munged(user_ns, high);
 	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
 
-	if (write && ret == 0)
-		set_ping_group_range(table, range);
+	if (write && ret == 0) {
+		low = make_kgid(user_ns, urange[0]);
+		high = make_kgid(user_ns, urange[1]);
+		if (!gid_valid(low) || !gid_valid(high) ||
+		    (urange[1] < urange[0]) || gid_lt(high, low)) {
+			low = make_kgid(&init_user_ns, 1);
+			high = make_kgid(&init_user_ns, 0);
+		}
+		set_ping_group_range(table, low, high);
+	}
 
 	return ret;
 }
@@ -220,6 +232,45 @@ static int ipv4_tcp_mem(ctl_table *ctl, int write,
 	return 0;
 }
 
+int proc_tcp_fastopen_key(ctl_table *ctl, int write, void __user *buffer,
+			  size_t *lenp, loff_t *ppos)
+{
+	ctl_table tbl = { .maxlen = (TCP_FASTOPEN_KEY_LENGTH * 2 + 10) };
+	struct tcp_fastopen_context *ctxt;
+	int ret;
+	u32  user_key[4]; /* 16 bytes, matching TCP_FASTOPEN_KEY_LENGTH */
+
+	tbl.data = kmalloc(tbl.maxlen, GFP_KERNEL);
+	if (!tbl.data)
+		return -ENOMEM;
+
+	rcu_read_lock();
+	ctxt = rcu_dereference(tcp_fastopen_ctx);
+	if (ctxt)
+		memcpy(user_key, ctxt->key, TCP_FASTOPEN_KEY_LENGTH);
+	rcu_read_unlock();
+
+	snprintf(tbl.data, tbl.maxlen, "%08x-%08x-%08x-%08x",
+		user_key[0], user_key[1], user_key[2], user_key[3]);
+	ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
+
+	if (write && ret == 0) {
+		if (sscanf(tbl.data, "%x-%x-%x-%x", user_key, user_key + 1,
+			   user_key + 2, user_key + 3) != 4) {
+			ret = -EINVAL;
+			goto bad_key;
+		}
+		tcp_fastopen_reset_cipher(user_key, TCP_FASTOPEN_KEY_LENGTH);
+	}
+
+bad_key:
+	pr_debug("proc FO key set 0x%x-%x-%x-%x <- 0x%s: %u\n",
+	       user_key[0], user_key[1], user_key[2], user_key[3],
+	       (char *)tbl.data, ret);
+	kfree(tbl.data);
+	return ret;
+}
+
 static struct ctl_table ipv4_table[] = {
 	{
 		.procname	= "tcp_timestamps",
@@ -374,6 +425,12 @@ static struct ctl_table ipv4_table[] = {
 		.proc_handler	= proc_dointvec,
 	},
 	{
+		.procname	= "tcp_fastopen_key",
+		.mode		= 0600,
+		.maxlen		= ((TCP_FASTOPEN_KEY_LENGTH * 2) + 10),
+		.proc_handler	= proc_tcp_fastopen_key,
+	},
+	{
 		.procname	= "tcp_tw_recycle",
 		.data		= &tcp_death_row.sysctl_tw_recycle,
 		.maxlen		= sizeof(int),
@@ -786,7 +843,7 @@ static struct ctl_table ipv4_net_table[] = {
 	{
 		.procname	= "ping_group_range",
 		.data		= &init_net.ipv4.sysctl_ping_group_range,
-		.maxlen		= sizeof(init_net.ipv4.sysctl_ping_group_range),
+		.maxlen		= sizeof(gid_t)*2,
 		.mode		= 0644,
 		.proc_handler	= ipv4_ping_group_range,
 	},
@@ -830,8 +887,8 @@ static __net_init int ipv4_sysctl_init_net(struct net *net)
 	 * Sane defaults - nobody may create ping sockets.
 	 * Boot scripts should set this to distro-specific group.
 	 */
-	net->ipv4.sysctl_ping_group_range[0] = 1;
-	net->ipv4.sysctl_ping_group_range[1] = 0;
+	net->ipv4.sysctl_ping_group_range[0] = make_kgid(&init_user_ns, 1);
+	net->ipv4.sysctl_ping_group_range[1] = make_kgid(&init_user_ns, 0);
 
 	tcp_init_mem(net);
 
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2109ff4..df83d74 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -486,8 +486,9 @@ unsigned int tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
 	if (sk->sk_shutdown & RCV_SHUTDOWN)
 		mask |= POLLIN | POLLRDNORM | POLLRDHUP;
 
-	/* Connected? */
-	if ((1 << sk->sk_state) & ~(TCPF_SYN_SENT | TCPF_SYN_RECV)) {
+	/* Connected or passive Fast Open socket? */
+	if (sk->sk_state != TCP_SYN_SENT &&
+	    (sk->sk_state != TCP_SYN_RECV || tp->fastopen_rsk != NULL)) {
 		int target = sock_rcvlowat(sk, 0, INT_MAX);
 
 		if (tp->urg_seq == tp->copied_seq &&
@@ -840,10 +841,15 @@ static ssize_t do_tcp_sendpages(struct sock *sk, struct page **pages, int poffse
 	ssize_t copied;
 	long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 
-	/* Wait for a connection to finish. */
-	if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
+	/* Wait for a connection to finish. One exception is TCP Fast Open
+	 * (passive side) where data is allowed to be sent before a connection
+	 * is fully established.
+	 */
+	if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
+	    !tcp_passive_fastopen(sk)) {
 		if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 			goto out_err;
+	}
 
 	clear_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
 
@@ -1042,10 +1048,15 @@ int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
 	timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
 
-	/* Wait for a connection to finish. */
-	if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT))
+	/* Wait for a connection to finish. One exception is TCP Fast Open
+	 * (passive side) where data is allowed to be sent before a connection
+	 * is fully established.
+	 */
+	if (((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) &&
+	    !tcp_passive_fastopen(sk)) {
 		if ((err = sk_stream_wait_connect(sk, &timeo)) != 0)
 			goto do_error;
+	}
 
 	if (unlikely(tp->repair)) {
 		if (tp->repair_queue == TCP_RECV_QUEUE) {
@@ -2144,6 +2155,10 @@ void tcp_close(struct sock *sk, long timeout)
 		 * they look as CLOSING or LAST_ACK for Linux)
 		 * Probably, I missed some more holelets.
 		 * 						--ANK
+		 * XXX (TFO) - To start off we don't support SYN+ACK+FIN
+		 * in a single packet! (May consider it later but will
+		 * probably need API support or TCP_CORK SYN-ACK until
+		 * data is written and socket is closed.)
 		 */
 		tcp_send_fin(sk);
 	}
@@ -2215,8 +2230,16 @@ adjudge_to_death:
 		}
 	}
 
-	if (sk->sk_state == TCP_CLOSE)
+	if (sk->sk_state == TCP_CLOSE) {
+		struct request_sock *req = tcp_sk(sk)->fastopen_rsk;
+		/* We could get here with a non-NULL req if the socket is
+		 * aborted (e.g., closed with unread data) before 3WHS
+		 * finishes.
+		 */
+		if (req != NULL)
+			reqsk_fastopen_remove(sk, req, false);
 		inet_csk_destroy_sock(sk);
+	}
 	/* Otherwise, socket is reprieved until protocol close. */
 
 out:
@@ -2688,6 +2711,14 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
 		else
 			icsk->icsk_user_timeout = msecs_to_jiffies(val);
 		break;
+
+	case TCP_FASTOPEN:
+		if (val >= 0 && ((1 << sk->sk_state) & (TCPF_CLOSE |
+		    TCPF_LISTEN)))
+			err = fastopen_init_queue(sk, val);
+		else
+			err = -EINVAL;
+		break;
 	default:
 		err = -ENOPROTOOPT;
 		break;
@@ -3501,11 +3532,15 @@ EXPORT_SYMBOL(tcp_cookie_generator);
 
 void tcp_done(struct sock *sk)
 {
+	struct request_sock *req = tcp_sk(sk)->fastopen_rsk;
+
 	if (sk->sk_state == TCP_SYN_SENT || sk->sk_state == TCP_SYN_RECV)
 		TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS);
 
 	tcp_set_state(sk, TCP_CLOSE);
 	tcp_clear_xmit_timers(sk);
+	if (req != NULL)
+		reqsk_fastopen_remove(sk, req, false);
 
 	sk->sk_shutdown = SHUTDOWN_MASK;
 
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index a7f729c..8f7ef0a 100644
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -1,10 +1,91 @@
+#include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/tcp.h>
+#include <linux/rcupdate.h>
+#include <linux/rculist.h>
+#include <net/inetpeer.h>
+#include <net/tcp.h>
 
-int sysctl_tcp_fastopen;
+int sysctl_tcp_fastopen __read_mostly;
+
+struct tcp_fastopen_context __rcu *tcp_fastopen_ctx;
+
+static DEFINE_SPINLOCK(tcp_fastopen_ctx_lock);
+
+static void tcp_fastopen_ctx_free(struct rcu_head *head)
+{
+	struct tcp_fastopen_context *ctx =
+	    container_of(head, struct tcp_fastopen_context, rcu);
+	crypto_free_cipher(ctx->tfm);
+	kfree(ctx);
+}
+
+int tcp_fastopen_reset_cipher(void *key, unsigned int len)
+{
+	int err;
+	struct tcp_fastopen_context *ctx, *octx;
+
+	ctx = kmalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+	ctx->tfm = crypto_alloc_cipher("aes", 0, 0);
+
+	if (IS_ERR(ctx->tfm)) {
+		err = PTR_ERR(ctx->tfm);
+error:		kfree(ctx);
+		pr_err("TCP: TFO aes cipher alloc error: %d\n", err);
+		return err;
+	}
+	err = crypto_cipher_setkey(ctx->tfm, key, len);
+	if (err) {
+		pr_err("TCP: TFO cipher key error: %d\n", err);
+		crypto_free_cipher(ctx->tfm);
+		goto error;
+	}
+	memcpy(ctx->key, key, len);
+
+	spin_lock(&tcp_fastopen_ctx_lock);
+
+	octx = rcu_dereference_protected(tcp_fastopen_ctx,
+				lockdep_is_held(&tcp_fastopen_ctx_lock));
+	rcu_assign_pointer(tcp_fastopen_ctx, ctx);
+	spin_unlock(&tcp_fastopen_ctx_lock);
+
+	if (octx)
+		call_rcu(&octx->rcu, tcp_fastopen_ctx_free);
+	return err;
+}
+
+/* Computes the fastopen cookie for the peer.
+ * The peer address is a 128 bits long (pad with zeros for IPv4).
+ *
+ * The caller must check foc->len to determine if a valid cookie
+ * has been generated successfully.
+*/
+void tcp_fastopen_cookie_gen(__be32 addr, struct tcp_fastopen_cookie *foc)
+{
+	__be32 peer_addr[4] = { addr, 0, 0, 0 };
+	struct tcp_fastopen_context *ctx;
+
+	rcu_read_lock();
+	ctx = rcu_dereference(tcp_fastopen_ctx);
+	if (ctx) {
+		crypto_cipher_encrypt_one(ctx->tfm,
+					  foc->val,
+					  (__u8 *)peer_addr);
+		foc->len = TCP_FASTOPEN_COOKIE_SIZE;
+	}
+	rcu_read_unlock();
+}
 
 static int __init tcp_fastopen_init(void)
 {
+	__u8 key[TCP_FASTOPEN_KEY_LENGTH];
+
+	get_random_bytes(key, sizeof(key));
+	tcp_fastopen_reset_cipher(key, sizeof(key));
 	return 0;
 }
 
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index bcfccc5..8c304a4 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -378,7 +378,7 @@ static void tcp_fixup_rcvbuf(struct sock *sk)
 /* 4. Try to fixup all. It is made immediately after connection enters
  *    established state.
  */
-static void tcp_init_buffer_space(struct sock *sk)
+void tcp_init_buffer_space(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	int maxwin;
@@ -2930,13 +2930,14 @@ static void tcp_enter_recovery(struct sock *sk, bool ece_ack)
  * tcp_xmit_retransmit_queue().
  */
 static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
-				  int newly_acked_sacked, bool is_dupack,
+				  int prior_sacked, bool is_dupack,
 				  int flag)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
 	int do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) &&
 				    (tcp_fackets_out(tp) > tp->reordering));
+	int newly_acked_sacked = 0;
 	int fast_rexmit = 0;
 
 	if (WARN_ON(!tp->packets_out && tp->sacked_out))
@@ -2996,6 +2997,7 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
 				tcp_add_reno_sack(sk);
 		} else
 			do_lost = tcp_try_undo_partial(sk, pkts_acked);
+		newly_acked_sacked = pkts_acked + tp->sacked_out - prior_sacked;
 		break;
 	case TCP_CA_Loss:
 		if (flag & FLAG_DATA_ACKED)
@@ -3017,6 +3019,7 @@ static void tcp_fastretrans_alert(struct sock *sk, int pkts_acked,
 			if (is_dupack)
 				tcp_add_reno_sack(sk);
 		}
+		newly_acked_sacked = pkts_acked + tp->sacked_out - prior_sacked;
 
 		if (icsk->icsk_ca_state <= TCP_CA_Disorder)
 			tcp_try_undo_dsack(sk);
@@ -3124,6 +3127,12 @@ void tcp_rearm_rto(struct sock *sk)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 
+	/* If the retrans timer is currently being used by Fast Open
+	 * for SYN-ACK retrans purpose, stay put.
+	 */
+	if (tp->fastopen_rsk)
+		return;
+
 	if (!tp->packets_out) {
 		inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 	} else {
@@ -3594,7 +3603,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	int prior_packets;
 	int prior_sacked = tp->sacked_out;
 	int pkts_acked = 0;
-	int newly_acked_sacked = 0;
 	bool frto_cwnd = false;
 
 	/* If the ack is older than previous acks
@@ -3670,8 +3678,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 	flag |= tcp_clean_rtx_queue(sk, prior_fackets, prior_snd_una);
 
 	pkts_acked = prior_packets - tp->packets_out;
-	newly_acked_sacked = (prior_packets - prior_sacked) -
-			     (tp->packets_out - tp->sacked_out);
 
 	if (tp->frto_counter)
 		frto_cwnd = tcp_process_frto(sk, flag);
@@ -3685,7 +3691,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 		    tcp_may_raise_cwnd(sk, flag))
 			tcp_cong_avoid(sk, ack, prior_in_flight);
 		is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));
-		tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked,
+		tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
 				      is_dupack, flag);
 	} else {
 		if ((flag & FLAG_DATA_ACKED) && !frto_cwnd)
@@ -3702,7 +3708,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 no_queue:
 	/* If data was DSACKed, see if we can undo a cwnd reduction. */
 	if (flag & FLAG_DSACKING_ACK)
-		tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked,
+		tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
 				      is_dupack, flag);
 	/* If this ack opens up a zero window, clear backoff.  It was
 	 * being used to time the probes, and is probably far higher than
@@ -3722,8 +3728,7 @@ old_ack:
 	 */
 	if (TCP_SKB_CB(skb)->sacked) {
 		flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una);
-		newly_acked_sacked = tp->sacked_out - prior_sacked;
-		tcp_fastretrans_alert(sk, pkts_acked, newly_acked_sacked,
+		tcp_fastretrans_alert(sk, pkts_acked, prior_sacked,
 				      is_dupack, flag);
 	}
 
@@ -4039,7 +4044,7 @@ static inline bool tcp_sequence(const struct tcp_sock *tp, u32 seq, u32 end_seq)
 }
 
 /* When we get a reset we do this. */
-static void tcp_reset(struct sock *sk)
+void tcp_reset(struct sock *sk)
 {
 	/* We want the right error as BSD sees it (and indeed as we do). */
 	switch (sk->sk_state) {
@@ -5896,7 +5901,9 @@ discard:
 		tcp_send_synack(sk);
 #if 0
 		/* Note, we could accept data and URG from this segment.
-		 * There are no obstacles to make this.
+		 * There are no obstacles to make this (except that we must
+		 * either change tcp_recvmsg() to prevent it from returning data
+		 * before 3WHS completes per RFC793, or employ TCP Fast Open).
 		 *
 		 * However, if we ignore data in ACKless segments sometimes,
 		 * we have no reasons to accept it sometimes.
@@ -5936,6 +5943,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct inet_connection_sock *icsk = inet_csk(sk);
+	struct request_sock *req;
 	int queued = 0;
 
 	tp->rx_opt.saw_tstamp = 0;
@@ -5991,7 +5999,14 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 		return 0;
 	}
 
-	if (!tcp_validate_incoming(sk, skb, th, 0))
+	req = tp->fastopen_rsk;
+	if (req != NULL) {
+		BUG_ON(sk->sk_state != TCP_SYN_RECV &&
+		    sk->sk_state != TCP_FIN_WAIT1);
+
+		if (tcp_check_req(sk, skb, req, NULL, true) == NULL)
+			goto discard;
+	} else if (!tcp_validate_incoming(sk, skb, th, 0))
 		return 0;
 
 	/* step 5: check the ACK field */
@@ -6001,7 +6016,22 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 		switch (sk->sk_state) {
 		case TCP_SYN_RECV:
 			if (acceptable) {
-				tp->copied_seq = tp->rcv_nxt;
+				/* Once we leave TCP_SYN_RECV, we no longer
+				 * need req so release it.
+				 */
+				if (req) {
+					reqsk_fastopen_remove(sk, req, false);
+				} else {
+					/* Make sure socket is routed, for
+					 * correct metrics.
+					 */
+					icsk->icsk_af_ops->rebuild_header(sk);
+					tcp_init_congestion_control(sk);
+
+					tcp_mtup_init(sk);
+					tcp_init_buffer_space(sk);
+					tp->copied_seq = tp->rcv_nxt;
+				}
 				smp_mb();
 				tcp_set_state(sk, TCP_ESTABLISHED);
 				sk->sk_state_change(sk);
@@ -6023,23 +6053,27 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 				if (tp->rx_opt.tstamp_ok)
 					tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
 
-				/* Make sure socket is routed, for
-				 * correct metrics.
-				 */
-				icsk->icsk_af_ops->rebuild_header(sk);
-
-				tcp_init_metrics(sk);
-
-				tcp_init_congestion_control(sk);
+				if (req) {
+					/* Re-arm the timer because data may
+					 * have been sent out. This is similar
+					 * to the regular data transmission case
+					 * when new data has just been ack'ed.
+					 *
+					 * (TFO) - we could try to be more
+					 * aggressive and retranmitting any data
+					 * sooner based on when they were sent
+					 * out.
+					 */
+					tcp_rearm_rto(sk);
+				} else
+					tcp_init_metrics(sk);
 
 				/* Prevent spurious tcp_cwnd_restart() on
 				 * first data packet.
 				 */
 				tp->lsndtime = tcp_time_stamp;
 
-				tcp_mtup_init(sk);
 				tcp_initialize_rcv_mss(sk);
-				tcp_init_buffer_space(sk);
 				tcp_fast_path_on(tp);
 			} else {
 				return 1;
@@ -6047,6 +6081,16 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 			break;
 
 		case TCP_FIN_WAIT1:
+			/* If we enter the TCP_FIN_WAIT1 state and we are a
+			 * Fast Open socket and this is the first acceptable
+			 * ACK we have received, this would have acknowledged
+			 * our SYNACK so stop the SYNACK timer.
+			 */
+			if (acceptable && req != NULL) {
+				/* We no longer need the request sock. */
+				reqsk_fastopen_remove(sk, req, false);
+				tcp_rearm_rto(sk);
+			}
 			if (tp->snd_una == tp->write_seq) {
 				struct dst_entry *dst;
 
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 1e15c5b..e64abed 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -352,6 +352,7 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
 	const int code = icmp_hdr(icmp_skb)->code;
 	struct sock *sk;
 	struct sk_buff *skb;
+	struct request_sock *req;
 	__u32 seq;
 	__u32 remaining;
 	int err;
@@ -394,9 +395,12 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
 
 	icsk = inet_csk(sk);
 	tp = tcp_sk(sk);
+	req = tp->fastopen_rsk;
 	seq = ntohl(th->seq);
 	if (sk->sk_state != TCP_LISTEN &&
-	    !between(seq, tp->snd_una, tp->snd_nxt)) {
+	    !between(seq, tp->snd_una, tp->snd_nxt) &&
+	    (req == NULL || seq != tcp_rsk(req)->snt_isn)) {
+		/* For a Fast Open socket, allow seq to be snt_isn. */
 		NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);
 		goto out;
 	}
@@ -435,6 +439,8 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
 		    !icsk->icsk_backoff)
 			break;
 
+		/* XXX (TFO) - revisit the following logic for TFO */
+
 		if (sock_owned_by_user(sk))
 			break;
 
@@ -466,6 +472,14 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
 		goto out;
 	}
 
+	/* XXX (TFO) - if it's a TFO socket and has been accepted, rather
+	 * than following the TCP_SYN_RECV case and closing the socket,
+	 * we ignore the ICMP error and keep trying like a fully established
+	 * socket. Is this the right thing to do?
+	 */
+	if (req && req->sk == NULL)
+		goto out;
+
 	switch (sk->sk_state) {
 		struct request_sock *req, **prev;
 	case TCP_LISTEN:
@@ -498,7 +512,8 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
 
 	case TCP_SYN_SENT:
 	case TCP_SYN_RECV:  /* Cannot happen.
-			       It can f.e. if SYNs crossed.
+			       It can f.e. if SYNs crossed,
+			       or Fast Open.
 			     */
 		if (!sock_owned_by_user(sk)) {
 			sk->sk_err = err;
@@ -809,8 +824,12 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
 static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 				  struct request_sock *req)
 {
-	tcp_v4_send_ack(skb, tcp_rsk(req)->snt_isn + 1,
-			tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd,
+	/* sk->sk_state == TCP_LISTEN -> for regular TCP_SYN_RECV
+	 * sk->sk_state == TCP_SYN_RECV -> for Fast Open.
+	 */
+	tcp_v4_send_ack(skb, (sk->sk_state == TCP_LISTEN) ?
+			tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
+			tcp_rsk(req)->rcv_nxt, req->rcv_wnd,
 			req->ts_recent,
 			0,
 			tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr,
@@ -839,7 +858,7 @@ static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst,
 	if (!dst && (dst = inet_csk_route_req(sk, &fl4, req)) == NULL)
 		return -1;
 
-	skb = tcp_make_synack(sk, dst, req, rvp);
+	skb = tcp_make_synack(sk, dst, req, rvp, NULL);
 
 	if (skb) {
 		__tcp_v4_send_check(skb, ireq->loc_addr, ireq->rmt_addr);
@@ -1272,6 +1291,178 @@ static const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops = {
 };
 #endif
 
+static bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
+			       struct request_sock *req,
+			       struct tcp_fastopen_cookie *foc,
+			       struct tcp_fastopen_cookie *valid_foc)
+{
+	bool skip_cookie = false;
+	struct fastopen_queue *fastopenq;
+
+	if (likely(!fastopen_cookie_present(foc))) {
+		/* See include/net/tcp.h for the meaning of these knobs */
+		if ((sysctl_tcp_fastopen & TFO_SERVER_ALWAYS) ||
+		    ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD) &&
+		    (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1)))
+			skip_cookie = true; /* no cookie to validate */
+		else
+			return false;
+	}
+	fastopenq = inet_csk(sk)->icsk_accept_queue.fastopenq;
+	/* A FO option is present; bump the counter. */
+	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE);
+
+	/* Make sure the listener has enabled fastopen, and we don't
+	 * exceed the max # of pending TFO requests allowed before trying
+	 * to validating the cookie in order to avoid burning CPU cycles
+	 * unnecessarily.
+	 *
+	 * XXX (TFO) - The implication of checking the max_qlen before
+	 * processing a cookie request is that clients can't differentiate
+	 * between qlen overflow causing Fast Open to be disabled
+	 * temporarily vs a server not supporting Fast Open at all.
+	 */
+	if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) == 0 ||
+	    fastopenq == NULL || fastopenq->max_qlen == 0)
+		return false;
+
+	if (fastopenq->qlen >= fastopenq->max_qlen) {
+		struct request_sock *req1;
+		spin_lock(&fastopenq->lock);
+		req1 = fastopenq->rskq_rst_head;
+		if ((req1 == NULL) || time_after(req1->expires, jiffies)) {
+			spin_unlock(&fastopenq->lock);
+			NET_INC_STATS_BH(sock_net(sk),
+			    LINUX_MIB_TCPFASTOPENLISTENOVERFLOW);
+			/* Avoid bumping LINUX_MIB_TCPFASTOPENPASSIVEFAIL*/
+			foc->len = -1;
+			return false;
+		}
+		fastopenq->rskq_rst_head = req1->dl_next;
+		fastopenq->qlen--;
+		spin_unlock(&fastopenq->lock);
+		reqsk_free(req1);
+	}
+	if (skip_cookie) {
+		tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+		return true;
+	}
+	if (foc->len == TCP_FASTOPEN_COOKIE_SIZE) {
+		if ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_CHKED) == 0) {
+			tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
+			if ((valid_foc->len != TCP_FASTOPEN_COOKIE_SIZE) ||
+			    memcmp(&foc->val[0], &valid_foc->val[0],
+			    TCP_FASTOPEN_COOKIE_SIZE) != 0)
+				return false;
+			valid_foc->len = -1;
+		}
+		/* Acknowledge the data received from the peer. */
+		tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+		return true;
+	} else if (foc->len == 0) { /* Client requesting a cookie */
+		tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
+		NET_INC_STATS_BH(sock_net(sk),
+		    LINUX_MIB_TCPFASTOPENCOOKIEREQD);
+	} else {
+		/* Client sent a cookie with wrong size. Treat it
+		 * the same as invalid and return a valid one.
+		 */
+		tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr, valid_foc);
+	}
+	return false;
+}
+
+static int tcp_v4_conn_req_fastopen(struct sock *sk,
+				    struct sk_buff *skb,
+				    struct sk_buff *skb_synack,
+				    struct request_sock *req,
+				    struct request_values *rvp)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
+	const struct inet_request_sock *ireq = inet_rsk(req);
+	struct sock *child;
+
+	req->retrans = 0;
+	req->sk = NULL;
+
+	child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
+	if (child == NULL) {
+		NET_INC_STATS_BH(sock_net(sk),
+				 LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
+		kfree_skb(skb_synack);
+		return -1;
+	}
+	ip_build_and_send_pkt(skb_synack, sk, ireq->loc_addr,
+			ireq->rmt_addr, ireq->opt);
+	/* XXX (TFO) - is it ok to ignore error and continue? */
+
+	spin_lock(&queue->fastopenq->lock);
+	queue->fastopenq->qlen++;
+	spin_unlock(&queue->fastopenq->lock);
+
+	/* Initialize the child socket. Have to fix some values to take
+	 * into account the child is a Fast Open socket and is created
+	 * only out of the bits carried in the SYN packet.
+	 */
+	tp = tcp_sk(child);
+
+	tp->fastopen_rsk = req;
+	/* Do a hold on the listner sk so that if the listener is being
+	 * closed, the child that has been accepted can live on and still
+	 * access listen_lock.
+	 */
+	sock_hold(sk);
+	tcp_rsk(req)->listener = sk;
+
+	/* RFC1323: The window in SYN & SYN/ACK segments is never
+	 * scaled. So correct it appropriately.
+	 */
+	tp->snd_wnd = ntohs(tcp_hdr(skb)->window);
+
+	/* Activate the retrans timer so that SYNACK can be retransmitted.
+	 * The request socket is not added to the SYN table of the parent
+	 * because it's been added to the accept queue directly.
+	 */
+	inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS,
+	    TCP_TIMEOUT_INIT, TCP_RTO_MAX);
+
+	/* Add the child socket directly into the accept queue */
+	inet_csk_reqsk_queue_add(sk, req, child);
+
+	/* Now finish processing the fastopen child socket. */
+	inet_csk(child)->icsk_af_ops->rebuild_header(child);
+	tcp_init_congestion_control(child);
+	tcp_mtup_init(child);
+	tcp_init_buffer_space(child);
+	tcp_init_metrics(child);
+
+	/* Queue the data carried in the SYN packet. We need to first
+	 * bump skb's refcnt because the caller will attempt to free it.
+	 *
+	 * XXX (TFO) - we honor a zero-payload TFO request for now.
+	 * (Any reason not to?)
+	 */
+	if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq + 1) {
+		/* Don't queue the skb if there is no payload in SYN.
+		 * XXX (TFO) - How about SYN+FIN?
+		 */
+		tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+	} else {
+		skb = skb_get(skb);
+		skb_dst_drop(skb);
+		__skb_pull(skb, tcp_hdr(skb)->doff * 4);
+		skb_set_owner_r(skb, child);
+		__skb_queue_tail(&child->sk_receive_queue, skb);
+		tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+	}
+	sk->sk_data_ready(sk, 0);
+	bh_unlock_sock(child);
+	sock_put(child);
+	WARN_ON(req->sk == NULL);
+	return 0;
+}
+
 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_extend_values tmp_ext;
@@ -1285,6 +1476,11 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 	__be32 daddr = ip_hdr(skb)->daddr;
 	__u32 isn = TCP_SKB_CB(skb)->when;
 	bool want_cookie = false;
+	struct flowi4 fl4;
+	struct tcp_fastopen_cookie foc = { .len = -1 };
+	struct tcp_fastopen_cookie valid_foc = { .len = -1 };
+	struct sk_buff *skb_synack;
+	int do_fastopen;
 
 	/* Never answer to SYNs send to broadcast or multicast */
 	if (skb_rtable(skb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
@@ -1319,7 +1515,8 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 	tcp_clear_options(&tmp_opt);
 	tmp_opt.mss_clamp = TCP_MSS_DEFAULT;
 	tmp_opt.user_mss  = tp->rx_opt.user_mss;
-	tcp_parse_options(skb, &tmp_opt, &hash_location, 0, NULL);
+	tcp_parse_options(skb, &tmp_opt, &hash_location, 0,
+	    want_cookie ? NULL : &foc);
 
 	if (tmp_opt.cookie_plus > 0 &&
 	    tmp_opt.saw_tstamp &&
@@ -1377,8 +1574,6 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 		isn = cookie_v4_init_sequence(sk, skb, &req->mss);
 		req->cookie_ts = tmp_opt.tstamp_ok;
 	} else if (!isn) {
-		struct flowi4 fl4;
-
 		/* VJ's idea. We save last timestamp seen
 		 * from the destination in peer table, when entering
 		 * state TIME-WAIT, and check against it before
@@ -1419,14 +1614,52 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 	tcp_rsk(req)->snt_isn = isn;
 	tcp_rsk(req)->snt_synack = tcp_time_stamp;
 
-	if (tcp_v4_send_synack(sk, dst, req,
-			       (struct request_values *)&tmp_ext,
-			       skb_get_queue_mapping(skb),
-			       want_cookie) ||
-	    want_cookie)
+	if (dst == NULL) {
+		dst = inet_csk_route_req(sk, &fl4, req);
+		if (dst == NULL)
+			goto drop_and_free;
+	}
+	do_fastopen = tcp_fastopen_check(sk, skb, req, &foc, &valid_foc);
+
+	/* We don't call tcp_v4_send_synack() directly because we need
+	 * to make sure a child socket can be created successfully before
+	 * sending back synack!
+	 *
+	 * XXX (TFO) - Ideally one would simply call tcp_v4_send_synack()
+	 * (or better yet, call tcp_send_synack() in the child context
+	 * directly, but will have to fix bunch of other code first)
+	 * after syn_recv_sock() except one will need to first fix the
+	 * latter to remove its dependency on the current implementation
+	 * of tcp_v4_send_synack()->tcp_select_initial_window().
+	 */
+	skb_synack = tcp_make_synack(sk, dst, req,
+	    (struct request_values *)&tmp_ext,
+	    fastopen_cookie_present(&valid_foc) ? &valid_foc : NULL);
+
+	if (skb_synack) {
+		__tcp_v4_send_check(skb_synack, ireq->loc_addr, ireq->rmt_addr);
+		skb_set_queue_mapping(skb_synack, skb_get_queue_mapping(skb));
+	} else
+		goto drop_and_free;
+
+	if (likely(!do_fastopen)) {
+		int err;
+		err = ip_build_and_send_pkt(skb_synack, sk, ireq->loc_addr,
+		     ireq->rmt_addr, ireq->opt);
+		err = net_xmit_eval(err);
+		if (err || want_cookie)
+			goto drop_and_free;
+
+		tcp_rsk(req)->listener = NULL;
+		/* Add the request_sock to the SYN table */
+		inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
+		if (fastopen_cookie_present(&foc) && foc.len != 0)
+			NET_INC_STATS_BH(sock_net(sk),
+			    LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
+	} else if (tcp_v4_conn_req_fastopen(sk, skb, skb_synack, req,
+	    (struct request_values *)&tmp_ext))
 		goto drop_and_free;
 
-	inet_csk_reqsk_queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
 	return 0;
 
 drop_and_release:
@@ -1554,7 +1787,7 @@ static struct sock *tcp_v4_hnd_req(struct sock *sk, struct sk_buff *skb)
 	struct request_sock *req = inet_csk_search_req(sk, &prev, th->source,
 						       iph->saddr, iph->daddr);
 	if (req)
-		return tcp_check_req(sk, skb, req, prev);
+		return tcp_check_req(sk, skb, req, prev, false);
 
 	nsk = inet_lookup_established(sock_net(sk), &tcp_hashinfo, iph->saddr,
 			th->source, iph->daddr, th->dest, inet_iif(skb));
@@ -1977,6 +2210,7 @@ void tcp_v4_destroy_sock(struct sock *sk)
 			 tcp_cookie_values_release);
 		tp->cookie_values = NULL;
 	}
+	BUG_ON(tp->fastopen_rsk != NULL);
 
 	/* If socket is aborted during connect operation */
 	tcp_free_fastopen_req(tp);
@@ -2393,7 +2627,7 @@ void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo)
 EXPORT_SYMBOL(tcp_proc_unregister);
 
 static void get_openreq4(const struct sock *sk, const struct request_sock *req,
-			 struct seq_file *f, int i, int uid, int *len)
+			 struct seq_file *f, int i, kuid_t uid, int *len)
 {
 	const struct inet_request_sock *ireq = inet_rsk(req);
 	long delta = req->expires - jiffies;
@@ -2410,7 +2644,7 @@ static void get_openreq4(const struct sock *sk, const struct request_sock *req,
 		1,    /* timers active (only the expire timer) */
 		jiffies_delta_to_clock_t(delta),
 		req->retrans,
-		uid,
+		from_kuid_munged(seq_user_ns(f), uid),
 		0,  /* non standard timer */
 		0, /* open_requests have no inode */
 		atomic_read(&sk->sk_refcnt),
@@ -2425,6 +2659,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
 	const struct tcp_sock *tp = tcp_sk(sk);
 	const struct inet_connection_sock *icsk = inet_csk(sk);
 	const struct inet_sock *inet = inet_sk(sk);
+	struct fastopen_queue *fastopenq = icsk->icsk_accept_queue.fastopenq;
 	__be32 dest = inet->inet_daddr;
 	__be32 src = inet->inet_rcv_saddr;
 	__u16 destp = ntohs(inet->inet_dport);
@@ -2461,7 +2696,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
 		timer_active,
 		jiffies_delta_to_clock_t(timer_expires - jiffies),
 		icsk->icsk_retransmits,
-		sock_i_uid(sk),
+		from_kuid_munged(seq_user_ns(f), sock_i_uid(sk)),
 		icsk->icsk_probes_out,
 		sock_i_ino(sk),
 		atomic_read(&sk->sk_refcnt), sk,
@@ -2469,7 +2704,9 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
 		jiffies_to_clock_t(icsk->icsk_ack.ato),
 		(icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,
 		tp->snd_cwnd,
-		tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh,
+		sk->sk_state == TCP_LISTEN ?
+		    (fastopenq ? fastopenq->max_qlen : 0) :
+		    (tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh),
 		len);
 }
 
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 6ff7f10..e965319 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -507,6 +507,7 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
 			newicsk->icsk_ack.last_seg_size = skb->len - newtp->tcp_header_len;
 		newtp->rx_opt.mss_clamp = req->mss;
 		TCP_ECN_openreq_child(newtp, req);
+		newtp->fastopen_rsk = NULL;
 
 		TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_PASSIVEOPENS);
 	}
@@ -515,13 +516,18 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
 EXPORT_SYMBOL(tcp_create_openreq_child);
 
 /*
- *	Process an incoming packet for SYN_RECV sockets represented
- *	as a request_sock.
+ * Process an incoming packet for SYN_RECV sockets represented as a
+ * request_sock. Normally sk is the listener socket but for TFO it
+ * points to the child socket.
+ *
+ * XXX (TFO) - The current impl contains a special check for ack
+ * validation and inside tcp_v4_reqsk_send_ack(). Can we do better?
  */
 
 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 			   struct request_sock *req,
-			   struct request_sock **prev)
+			   struct request_sock **prev,
+			   bool fastopen)
 {
 	struct tcp_options_received tmp_opt;
 	const u8 *hash_location;
@@ -530,6 +536,8 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 	__be32 flg = tcp_flag_word(th) & (TCP_FLAG_RST|TCP_FLAG_SYN|TCP_FLAG_ACK);
 	bool paws_reject = false;
 
+	BUG_ON(fastopen == (sk->sk_state == TCP_LISTEN));
+
 	tmp_opt.saw_tstamp = 0;
 	if (th->doff > (sizeof(struct tcphdr)>>2)) {
 		tcp_parse_options(skb, &tmp_opt, &hash_location, 0, NULL);
@@ -565,6 +573,9 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 		 *
 		 * Enforce "SYN-ACK" according to figure 8, figure 6
 		 * of RFC793, fixed by RFC1122.
+		 *
+		 * Note that even if there is new data in the SYN packet
+		 * they will be thrown away too.
 		 */
 		req->rsk_ops->rtx_syn_ack(sk, req, NULL);
 		return NULL;
@@ -622,9 +633,12 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 	 *                  sent (the segment carries an unacceptable ACK) ...
 	 *                  a reset is sent."
 	 *
-	 * Invalid ACK: reset will be sent by listening socket
+	 * Invalid ACK: reset will be sent by listening socket.
+	 * Note that the ACK validity check for a Fast Open socket is done
+	 * elsewhere and is checked directly against the child socket rather
+	 * than req because user data may have been sent out.
 	 */
-	if ((flg & TCP_FLAG_ACK) &&
+	if ((flg & TCP_FLAG_ACK) && !fastopen &&
 	    (TCP_SKB_CB(skb)->ack_seq !=
 	     tcp_rsk(req)->snt_isn + 1 + tcp_s_data_size(tcp_sk(sk))))
 		return sk;
@@ -637,7 +651,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 	/* RFC793: "first check sequence number". */
 
 	if (paws_reject || !tcp_in_window(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq,
-					  tcp_rsk(req)->rcv_isn + 1, tcp_rsk(req)->rcv_isn + 1 + req->rcv_wnd)) {
+					  tcp_rsk(req)->rcv_nxt, tcp_rsk(req)->rcv_nxt + req->rcv_wnd)) {
 		/* Out of window: send ACK and drop. */
 		if (!(flg & TCP_FLAG_RST))
 			req->rsk_ops->send_ack(sk, skb, req);
@@ -648,7 +662,7 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 
 	/* In sequence, PAWS is OK. */
 
-	if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_isn + 1))
+	if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_nxt))
 		req->ts_recent = tmp_opt.rcv_tsval;
 
 	if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn) {
@@ -667,10 +681,19 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 
 	/* ACK sequence verified above, just make sure ACK is
 	 * set.  If ACK not set, just silently drop the packet.
+	 *
+	 * XXX (TFO) - if we ever allow "data after SYN", the
+	 * following check needs to be removed.
 	 */
 	if (!(flg & TCP_FLAG_ACK))
 		return NULL;
 
+	/* For Fast Open no more processing is needed (sk is the
+	 * child socket).
+	 */
+	if (fastopen)
+		return sk;
+
 	/* While TCP_DEFER_ACCEPT is active, drop bare ACK. */
 	if (req->retrans < inet_csk(sk)->icsk_accept_queue.rskq_defer_accept &&
 	    TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) {
@@ -706,11 +729,21 @@ listen_overflow:
 	}
 
 embryonic_reset:
-	NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_EMBRYONICRSTS);
-	if (!(flg & TCP_FLAG_RST))
+	if (!(flg & TCP_FLAG_RST)) {
+		/* Received a bad SYN pkt - for TFO We try not to reset
+		 * the local connection unless it's really necessary to
+		 * avoid becoming vulnerable to outside attack aiming at
+		 * resetting legit local connections.
+		 */
 		req->rsk_ops->send_reset(sk, skb);
-
-	inet_csk_reqsk_queue_drop(sk, req, prev);
+	} else if (fastopen) { /* received a valid RST pkt */
+		reqsk_fastopen_remove(sk, req, true);
+		tcp_reset(sk);
+	}
+	if (!fastopen) {
+		inet_csk_reqsk_queue_drop(sk, req, prev);
+		NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_EMBRYONICRSTS);
+	}
 	return NULL;
 }
 EXPORT_SYMBOL(tcp_check_req);
@@ -719,6 +752,12 @@ EXPORT_SYMBOL(tcp_check_req);
  * Queue segment on the new socket if the new socket is active,
  * otherwise we just shortcircuit this and continue with
  * the new socket.
+ *
+ * For the vast majority of cases child->sk_state will be TCP_SYN_RECV
+ * when entering. But other states are possible due to a race condition
+ * where after __inet_lookup_established() fails but before the listener
+ * locked is obtained, other packets cause the same connection to
+ * be created.
  */
 
 int tcp_child_process(struct sock *parent, struct sock *child,
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index d046326..9383b51 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -702,7 +702,8 @@ static unsigned int tcp_synack_options(struct sock *sk,
 				   unsigned int mss, struct sk_buff *skb,
 				   struct tcp_out_options *opts,
 				   struct tcp_md5sig_key **md5,
-				   struct tcp_extend_values *xvp)
+				   struct tcp_extend_values *xvp,
+				   struct tcp_fastopen_cookie *foc)
 {
 	struct inet_request_sock *ireq = inet_rsk(req);
 	unsigned int remaining = MAX_TCP_OPTION_SPACE;
@@ -747,7 +748,15 @@ static unsigned int tcp_synack_options(struct sock *sk,
 		if (unlikely(!ireq->tstamp_ok))
 			remaining -= TCPOLEN_SACKPERM_ALIGNED;
 	}
-
+	if (foc != NULL) {
+		u32 need = TCPOLEN_EXP_FASTOPEN_BASE + foc->len;
+		need = (need + 3) & ~3U;  /* Align to 32 bits */
+		if (remaining >= need) {
+			opts->options |= OPTION_FAST_OPEN_COOKIE;
+			opts->fastopen_cookie = foc;
+			remaining -= need;
+		}
+	}
 	/* Similar rationale to tcp_syn_options() applies here, too.
 	 * If the <SYN> options fit, the same options should fit now!
 	 */
@@ -2658,7 +2667,8 @@ int tcp_send_synack(struct sock *sk)
  */
 struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
 				struct request_sock *req,
-				struct request_values *rvp)
+				struct request_values *rvp,
+				struct tcp_fastopen_cookie *foc)
 {
 	struct tcp_out_options opts;
 	struct tcp_extend_values *xvp = tcp_xv(rvp);
@@ -2718,7 +2728,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
 #endif
 	TCP_SKB_CB(skb)->when = tcp_time_stamp;
 	tcp_header_size = tcp_synack_options(sk, req, mss,
-					     skb, &opts, &md5, xvp)
+					     skb, &opts, &md5, xvp, foc)
 			+ sizeof(*th);
 
 	skb_push(skb, tcp_header_size);
@@ -2772,7 +2782,8 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
 	}
 
 	th->seq = htonl(TCP_SKB_CB(skb)->seq);
-	th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1);
+	/* XXX data is queued and acked as is. No buffer/window check */
+	th->ack_seq = htonl(tcp_rsk(req)->rcv_nxt);
 
 	/* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */
 	th->window = htons(min(req->rcv_wnd, 65535U));
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index b774a03..fc04711 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -305,6 +305,35 @@ static void tcp_probe_timer(struct sock *sk)
 }
 
 /*
+ *	Timer for Fast Open socket to retransmit SYNACK. Note that the
+ *	sk here is the child socket, not the parent (listener) socket.
+ */
+static void tcp_fastopen_synack_timer(struct sock *sk)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+	int max_retries = icsk->icsk_syn_retries ? :
+	    sysctl_tcp_synack_retries + 1; /* add one more retry for fastopen */
+	struct request_sock *req;
+
+	req = tcp_sk(sk)->fastopen_rsk;
+	req->rsk_ops->syn_ack_timeout(sk, req);
+
+	if (req->retrans >= max_retries) {
+		tcp_write_err(sk);
+		return;
+	}
+	/* XXX (TFO) - Unlike regular SYN-ACK retransmit, we ignore error
+	 * returned from rtx_syn_ack() to make it more persistent like
+	 * regular retransmit because if the child socket has been accepted
+	 * it's not good to give up too easily.
+	 */
+	req->rsk_ops->rtx_syn_ack(sk, req, NULL);
+	req->retrans++;
+	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
+			  TCP_TIMEOUT_INIT << req->retrans, TCP_RTO_MAX);
+}
+
+/*
  *	The TCP retransmit timer.
  */
 
@@ -317,7 +346,15 @@ void tcp_retransmit_timer(struct sock *sk)
 		tcp_resume_early_retransmit(sk);
 		return;
 	}
-
+	if (tp->fastopen_rsk) {
+		BUG_ON(sk->sk_state != TCP_SYN_RECV &&
+		    sk->sk_state != TCP_FIN_WAIT1);
+		tcp_fastopen_synack_timer(sk);
+		/* Before we receive ACK to our SYN-ACK don't retransmit
+		 * anything else (e.g., data or FIN segments).
+		 */
+		return;
+	}
 	if (!tp->packets_out)
 		goto out;
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 6f6d1ac..c4e6432 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2110,7 +2110,9 @@ static void udp4_format_sock(struct sock *sp, struct seq_file *f,
 		bucket, src, srcp, dest, destp, sp->sk_state,
 		sk_wmem_alloc_get(sp),
 		sk_rmem_alloc_get(sp),
-		0, 0L, 0, sock_i_uid(sp), 0, sock_i_ino(sp),
+		0, 0L, 0,
+		from_kuid_munged(seq_user_ns(f), sock_i_uid(sp)),
+		0, sock_i_ino(sp),
 		atomic_read(&sp->sk_refcnt), sp,
 		atomic_read(&sp->sk_drops), len);
 }
diff --git a/net/ipv4/udp_diag.c b/net/ipv4/udp_diag.c
index 16d0960..d2f336e 100644
--- a/net/ipv4/udp_diag.c
+++ b/net/ipv4/udp_diag.c
@@ -24,7 +24,9 @@ static int sk_diag_dump(struct sock *sk, struct sk_buff *skb,
 	if (!inet_diag_bc_sk(bc, sk))
 		return 0;
 
-	return inet_sk_diag_fill(sk, NULL, skb, req, NETLINK_CB(cb->skb).pid,
+	return inet_sk_diag_fill(sk, NULL, skb, req,
+			sk_user_ns(NETLINK_CB(cb->skb).ssk),
+			NETLINK_CB(cb->skb).pid,
 			cb->nlh->nlmsg_seq, NLM_F_MULTI, cb->nlh);
 }
 
@@ -69,6 +71,7 @@ static int udp_dump_one(struct udp_table *tbl, struct sk_buff *in_skb,
 		goto out;
 
 	err = inet_sk_diag_fill(sk, NULL, rep, req,
+			   sk_user_ns(NETLINK_CB(in_skb).ssk),
 			   NETLINK_CB(in_skb).pid,
 			   nlh->nlmsg_seq, 0, nlh);
 	if (err < 0) {