sock_map: Update sock type checks for UDP

Now UDP supports sockmap and redirection, we can safely update
the sock type checks for it accordingly.

Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210331023237.41094-15-xiyou.wangcong@gmail.com

net/core/sock_map.c

@@ -535,7 +535,10 @@ static bool sk_is_udp(const struct sock *sk)
 
 static bool sock_map_redirect_allowed(const struct sock *sk)
 {
-	return sk_is_tcp(sk) && sk->sk_state != TCP_LISTEN;
+	if (sk_is_tcp(sk))
+		return sk->sk_state != TCP_LISTEN;
+	else
+		return sk->sk_state == TCP_ESTABLISHED;
 }
 
 static bool sock_map_sk_is_suitable(const struct sock *sk)