af_unix: Set TCP_ESTABLISHED for datagram sockets too

Currently only unix stream socket sets TCP_ESTABLISHED,
datagram socket can set this too when they connect to its
peer socket. At least __ip4_datagram_connect() does the same.

This will be used to determine whether an AF_UNIX datagram
socket can be redirected to in sockmap.

Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210704190252.11866-5-xiyou.wangcong@gmail.com

Author: Cong Wang

net/unix/af_unix.c

@@ -494,6 +494,7 @@ static void unix_dgram_disconnected(struct sock *sk, struct sock *other)
 			sk_error_report(other);
 		}
 	}
+	sk->sk_state = other->sk_state = TCP_CLOSE;
 }
 
 static void unix_sock_destructor(struct sock *sk)
@@ -1202,6 +1203,9 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 		unix_peer(sk) = other;
 		unix_state_double_unlock(sk, other);
 	}
+
+	if (unix_peer(sk))
+		sk->sk_state = other->sk_state = TCP_ESTABLISHED;
 	return 0;
 
 out_unlock:
@@ -1434,12 +1438,10 @@ static int unix_socketpair(struct socket *socka, struct socket *sockb)
 	init_peercred(ska);
 	init_peercred(skb);
 
-	if (ska->sk_type != SOCK_DGRAM) {
-		ska->sk_state = TCP_ESTABLISHED;
-		skb->sk_state = TCP_ESTABLISHED;
-		socka->state  = SS_CONNECTED;
-		sockb->state  = SS_CONNECTED;
-	}
+	ska->sk_state = TCP_ESTABLISHED;
+	skb->sk_state = TCP_ESTABLISHED;
+	socka->state  = SS_CONNECTED;
+	sockb->state  = SS_CONNECTED;
 	return 0;
 }