[NET]: Fix IP_ADD/DROP_MEMBERSHIP to handle only connectionless

Fix IP[V6]_ADD_MEMBERSHIP and IP[V6]_DROP_MEMBERSHIP to
return -EPROTO for connection oriented sockets.

Signed-off-by: Flavio Leitner <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/ipv4/ip_sockglue.c

···
 	{
 		struct ip_mreqn mreq;
 
+		err = -EPROTO;
+		if (inet_sk(sk)->is_icsk)
+			break;
+
 		if (optlen < sizeof(struct ip_mreq))
 			goto e_inval;
 		err = -EFAULT;

net/ipv6/ipv6_sockglue.c

···
 	{
 		struct ipv6_mreq mreq;
 
+		retv = -EPROTO;
+		if (inet_sk(sk)->is_icsk)
+			break;
+
 		retv = -EFAULT;
 		if (copy_from_user(&mreq, optval, sizeof(struct ipv6_mreq)))
 			break;