sctp: sctp should change socket state when shutdown is received

Now sctp doesn't change socket state upon shutdown reception. It changes
just the assoc state, even though it's a TCP-style socket.

For some cases, if we really need to check sk->sk_state, it's necessary to
fix this issue, at least when we use ss or netstat to dump, we can get a
more exact information.

As an improvement, we will change sk->sk_state when we change asoc->state
to SHUTDOWN_RECEIVED, and also do it in sctp_shutdown to keep consistent
with sctp_close.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo R. Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/sm_sideeffect.c

@@ -806,8 +806,10 @@ static void sctp_cmd_new_state(sctp_cmd_seq_t *cmds,
 
 		/* Set the RCV_SHUTDOWN flag when a SHUTDOWN is received. */
 		if (sctp_state(asoc, SHUTDOWN_RECEIVED) &&
-		    sctp_sstate(sk, ESTABLISHED))
+		    sctp_sstate(sk, ESTABLISHED)) {
+			sk->sk_state = SCTP_SS_CLOSING;
 			sk->sk_shutdown |= RCV_SHUTDOWN;
+		}
 	}
 
 	if (sctp_state(asoc, COOKIE_WAIT)) {

net/sctp/socket.c

@@ -4195,6 +4195,7 @@ static void sctp_shutdown(struct sock *sk, int how)
 		return;
 
 	if (how & SEND_SHUTDOWN) {
+		sk->sk_state = SCTP_SS_CLOSING;
 		ep = sctp_sk(sk)->ep;
 		if (!list_empty(&ep->asocs)) {
 			asoc = list_entry(ep->asocs.next,
@@ -7566,10 +7567,13 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
 	/* If the association on the newsk is already closed before accept()
 	 * is called, set RCV_SHUTDOWN flag.
 	 */
-	if (sctp_state(assoc, CLOSED) && sctp_style(newsk, TCP))
+	if (sctp_state(assoc, CLOSED) && sctp_style(newsk, TCP)) {
+		newsk->sk_state = SCTP_SS_CLOSING;
 		newsk->sk_shutdown |= RCV_SHUTDOWN;
+	} else {
+		newsk->sk_state = SCTP_SS_ESTABLISHED;
+	}
 
-	newsk->sk_state = SCTP_SS_ESTABLISHED;
 	release_sock(newsk);
 }