vsock: fix bind() behaviour taking care of CID

When we are looking for a socket bound to a specific address,
we also have to take into account the CID.

This patch is useful with multi-transports support because it
allows the binding of the same port with different CID, and
it prevents a connection to a wrong socket bound to the same
port, but with different CID.
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: NJorgen Hansen <jhansen@vmware.com>
Signed-off-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/vmw_vsock/af_vsock.c

@@ -228,10 +228,16 @@ static struct sock *__vsock_find_bound_socket(struct sockaddr_vm *addr)
 {
 	struct vsock_sock *vsk;
 
-	list_for_each_entry(vsk, vsock_bound_sockets(addr), bound_table)
-		if (addr->svm_port == vsk->local_addr.svm_port)
+	list_for_each_entry(vsk, vsock_bound_sockets(addr), bound_table) {
+		if (vsock_addr_equals_addr(addr, &vsk->local_addr))
 			return sk_vsock(vsk);
 
+		if (addr->svm_port == vsk->local_addr.svm_port &&
+		    (vsk->local_addr.svm_cid == VMADDR_CID_ANY ||
+		     addr->svm_cid == VMADDR_CID_ANY))
+			return sk_vsock(vsk);
+	}
+
 	return NULL;
 }