net: synack packets can be attached to request sockets

selinux needs few changes to accommodate fact that SYNACK messages
can be attached to a request socket, lacking sk_security pointer

(Only syncookies are still attached to a TCP_LISTEN socket)

Adds a new sk_listener() helper, and use it in selinux and sch_fq

Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported by: kernel test robot <ying.huang@linux.intel.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Eric Paris <eparis@parisplace.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index 3386cce..109b232 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -225,6 +225,7 @@
 		return &q->internal;
 
 	/* SYNACK messages are attached to a TCP_NEW_SYN_RECV request socket
+	 * or a listener (SYNCOOKIE mode)
 	 * 1) request sockets are not full blown,
 	 *    they do not contain sk_pacing_rate
 	 * 2) They are not part of a 'flow' yet
@@ -232,7 +233,7 @@
 	 *    especially if the listener set SO_MAX_PACING_RATE
 	 * 4) We pretend they are orphaned
 	 */
-	if (!sk || sk->sk_state == TCP_NEW_SYN_RECV) {
+	if (!sk || sk_listener(sk)) {
 		unsigned long hash = skb_get_hash(skb) & q->orphan_mask;
 
 		/* By forcing low order bit to 1, we make sure to not