mptcp: send out dedicated packet for ADD_ADDR using port

The process is similar to that of the ADD_ADDR IPv6, this patch also sent
out a pure ack for the ADD_ADDR using port.
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/options.c

@@ -590,7 +590,8 @@ static bool mptcp_established_options_add_addr(struct sock *sk, struct sk_buff *
 	bool port;
 	int len;
 
-	if (mptcp_pm_should_add_signal_ipv6(msk) &&
+	if ((mptcp_pm_should_add_signal_ipv6(msk) ||
+	     mptcp_pm_should_add_signal_port(msk)) &&
 	    skb && skb_is_tcp_pure_ack(skb)) {
 		pr_debug("drop other suboptions");
 		opts->suboptions = 0;

net/mptcp/pm.c

@@ -167,7 +167,8 @@ void mptcp_pm_add_addr_received(struct mptcp_sock *msk,
 
 void mptcp_pm_add_addr_send_ack(struct mptcp_sock *msk)
 {
-	if (!mptcp_pm_should_add_signal_ipv6(msk))
+	if (!mptcp_pm_should_add_signal_ipv6(msk) &&
+	    !mptcp_pm_should_add_signal_port(msk))
 		return;
 
 	mptcp_pm_schedule_work(msk, MPTCP_PM_ADD_ADDR_SEND_ACK);

net/mptcp/pm_netlink.c

@@ -407,7 +407,8 @@ void mptcp_pm_nl_add_addr_send_ack(struct mptcp_sock *msk)
 {
 	struct mptcp_subflow_context *subflow;
 
-	if (!mptcp_pm_should_add_signal_ipv6(msk))
+	if (!mptcp_pm_should_add_signal_ipv6(msk) &&
+	    !mptcp_pm_should_add_signal_port(msk))
 		return;
 
 	__mptcp_flush_join_list(msk);
@@ -417,14 +418,21 @@ void mptcp_pm_nl_add_addr_send_ack(struct mptcp_sock *msk)
 		u8 add_addr;
 
 		spin_unlock_bh(&msk->pm.lock);
+		if (mptcp_pm_should_add_signal_ipv6(msk))
 			pr_debug("send ack for add_addr6");
+		if (mptcp_pm_should_add_signal_port(msk))
+			pr_debug("send ack for add_addr_port");
+
 		lock_sock(ssk);
 		tcp_send_ack(ssk);
 		release_sock(ssk);
 		spin_lock_bh(&msk->pm.lock);
 
 		add_addr = READ_ONCE(msk->pm.add_addr_signal);
+		if (mptcp_pm_should_add_signal_ipv6(msk))
 			add_addr &= ~BIT(MPTCP_ADD_ADDR_IPV6);
+		if (mptcp_pm_should_add_signal_port(msk))
+			add_addr &= ~BIT(MPTCP_ADD_ADDR_PORT);
 		WRITE_ONCE(msk->pm.add_addr_signal, add_addr);
 	}
 }