tcp: diag: add support for request sockets to tcp_abort()

Adding support for SYN_RECV request sockets to tcp_abort()
is quite easy after our tcp listener rewrite.

Note that we also need to better handle listeners, or we might
leak not yet accepted children, because of a missing
inet_csk_listen_stop() call.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Tested-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/tcp.c

@@ -3083,6 +3083,15 @@ EXPORT_SYMBOL_GPL(tcp_done);
 int tcp_abort(struct sock *sk, int err)
 {
 	if (!sk_fullsock(sk)) {
+		if (sk->sk_state == TCP_NEW_SYN_RECV) {
+			struct request_sock *req = inet_reqsk(sk);
+
+			local_bh_disable();
+			inet_csk_reqsk_queue_drop_and_put(req->rsk_listener,
+							  req);
+			local_bh_enable();
+			return 0;
+		}
 		sock_gen_put(sk);
 		return -EOPNOTSUPP;
 	}