mptcp: sockopt: support IP_LOCAL_PORT_RANGE and IP_BIND_ADDRESS_NO_PORT

Support for IP_BIND_ADDRESS_NO_PORT sockopt was introduced in [1].
Recently [2] allowed its value to be accessed without locking the
socket.

Support for (newer) IP_LOCAL_PORT_RANGE sockopt was introduced in [3].
In the same series a selftest was added in [4]. This selftest also
covers the IP_BIND_ADDRESS_NO_PORT sockopt.

This patch enables getsockopt()/setsockopt() on MPTCP sockets for these
socket options, syncing set values to subflows in sync_socket_options().
Ephemeral port range is synced to subflows, enabling NAT usecase
described in [3].

[1] commit 90c337d ("inet: add IP_BIND_ADDRESS_NO_PORT to overcome
bind(0) limitations")
[2] commit ca571e2 ("inet: move inet->bind_address_no_port to
inet->inet_flags")
[3] commit 91d0b78 ("inet: Add IP_LOCAL_PORT_RANGE socket option")
[4] commit ae54396 ("selftests/net: Cover the IP_LOCAL_PORT_RANGE
socket option")

Signed-off-by: Maxim Galaganov <max@internet.ru>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/sockopt.c

@@ -440,6 +440,8 @@ static bool mptcp_supported_sockopt(int level, int optname)
 		/* should work fine */
 		case IP_FREEBIND:
 		case IP_TRANSPARENT:
+		case IP_BIND_ADDRESS_NO_PORT:
+		case IP_LOCAL_PORT_RANGE:
 
 		/* the following are control cmsg related */
 		case IP_PKTINFO:
@@ -455,7 +457,6 @@ static bool mptcp_supported_sockopt(int level, int optname)
 		/* common stuff that need some love */
 		case IP_TOS:
 		case IP_TTL:
-		case IP_BIND_ADDRESS_NO_PORT:
 		case IP_MTU_DISCOVER:
 		case IP_RECVERR:
 
@@ -710,6 +711,14 @@ static int mptcp_setsockopt_sol_ip_set(struct mptcp_sock *msk, int optname,
 		inet_assign_bit(TRANSPARENT, ssk,
 				inet_test_bit(TRANSPARENT, sk));
 		break;
+	case IP_BIND_ADDRESS_NO_PORT:
+		inet_assign_bit(BIND_ADDRESS_NO_PORT, ssk,
+				inet_test_bit(BIND_ADDRESS_NO_PORT, sk));
+		break;
+	case IP_LOCAL_PORT_RANGE:
+		WRITE_ONCE(inet_sk(ssk)->local_port_range,
+			   READ_ONCE(inet_sk(sk)->local_port_range));
+		break;
 	default:
 		release_sock(sk);
 		WARN_ON_ONCE(1);
@@ -755,6 +764,8 @@ static int mptcp_setsockopt_v4(struct mptcp_sock *msk, int optname,
 	switch (optname) {
 	case IP_FREEBIND:
 	case IP_TRANSPARENT:
+	case IP_BIND_ADDRESS_NO_PORT:
+	case IP_LOCAL_PORT_RANGE:
 		return mptcp_setsockopt_sol_ip_set(msk, optname, optval, optlen);
 	case IP_TOS:
 		return mptcp_setsockopt_v4_set_tos(msk, optname, optval, optlen);
@@ -1350,6 +1361,12 @@ static int mptcp_getsockopt_v4(struct mptcp_sock *msk, int optname,
 	switch (optname) {
 	case IP_TOS:
 		return mptcp_put_int_option(msk, optval, optlen, READ_ONCE(inet_sk(sk)->tos));
+	case IP_BIND_ADDRESS_NO_PORT:
+		return mptcp_put_int_option(msk, optval, optlen,
+				inet_test_bit(BIND_ADDRESS_NO_PORT, sk));
+	case IP_LOCAL_PORT_RANGE:
+		return mptcp_put_int_option(msk, optval, optlen,
+				READ_ONCE(inet_sk(sk)->local_port_range));
 	}
 
 	return -EOPNOTSUPP;
@@ -1450,6 +1467,8 @@ static void sync_socket_options(struct mptcp_sock *msk, struct sock *ssk)
 
 	inet_assign_bit(TRANSPARENT, ssk, inet_test_bit(TRANSPARENT, sk));
 	inet_assign_bit(FREEBIND, ssk, inet_test_bit(FREEBIND, sk));
+	inet_assign_bit(BIND_ADDRESS_NO_PORT, ssk, inet_test_bit(BIND_ADDRESS_NO_PORT, sk));
+	WRITE_ONCE(inet_sk(ssk)->local_port_range, READ_ONCE(inet_sk(sk)->local_port_range));
 }
 
 void mptcp_sockopt_sync_locked(struct mptcp_sock *msk, struct sock *ssk)