[NET_SCHED]: Use nla_policy for attribute validation in actions

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/act_nat.c b/net/sched/act_nat.c
index 5a512d4..0a3c833 100644
--- a/net/sched/act_nat.c
+++ b/net/sched/act_nat.c
@@ -40,6 +40,10 @@
 	.lock	=	&nat_lock,
 };
 
+static const struct nla_policy nat_policy[TCA_NAT_MAX + 1] = {
+	[TCA_NAT_PARMS]	= { .len = sizeof(struct tc_nat) },
+};
+
 static int tcf_nat_init(struct nlattr *nla, struct nlattr *est,
 			struct tc_action *a, int ovr, int bind)
 {
@@ -52,12 +56,11 @@
 	if (nla == NULL)
 		return -EINVAL;
 
-	err = nla_parse_nested(tb, TCA_NAT_MAX, nla, NULL);
+	err = nla_parse_nested(tb, TCA_NAT_MAX, nla, nat_policy);
 	if (err < 0)
 		return err;
 
-	if (tb[TCA_NAT_PARMS] == NULL ||
-	    nla_len(tb[TCA_NAT_PARMS]) < sizeof(*parm))
+	if (tb[TCA_NAT_PARMS] == NULL)
 		return -EINVAL;
 	parm = nla_data(tb[TCA_NAT_PARMS]);