net_sched: reject unknown tcfa_action values

After the commit 802bfb19 ("net/sched: user-space can't set
unknown tcfa_action values"), unknown tcfa_action values are
converted to TC_ACT_UNSPEC, but the common agreement is instead
rejecting such configurations.

This change also introduces a helper to simplify the destruction
of a single action, avoiding code duplication.

v1 -> v2:
 - helper is now static and renamed according to act_* convention
 - updated extack message, according to the new behavior

Fixes: 802bfb19 ("net/sched: user-space can't set unknown tcfa_action values")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sched/act_api.c

@@ -662,6 +662,13 @@ int tcf_action_destroy(struct tc_action *actions[], int bind)
 	return ret;
 }
 
+static int tcf_action_destroy_1(struct tc_action *a, int bind)
+{
+	struct tc_action *actions[] = { a, NULL };
+
+	return tcf_action_destroy(actions, bind);
+}
+
 static int tcf_action_put(struct tc_action *p)
 {
 	return __tcf_action_put(p, false);
@@ -881,17 +888,16 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
 	if (TC_ACT_EXT_CMP(a->tcfa_action, TC_ACT_GOTO_CHAIN)) {
 		err = tcf_action_goto_chain_init(a, tp);
 		if (err) {
-			struct tc_action *actions[] = { a, NULL };
-
-			tcf_action_destroy(actions, bind);
+			tcf_action_destroy_1(a, bind);
 			NL_SET_ERR_MSG(extack, "Failed to init TC action chain");
 			return ERR_PTR(err);
 		}
 	}
 
 	if (!tcf_action_valid(a->tcfa_action)) {
-		NL_SET_ERR_MSG(extack, "invalid action value, using TC_ACT_UNSPEC instead");
-		a->tcfa_action = TC_ACT_UNSPEC;
+		tcf_action_destroy_1(a, bind);
+		NL_SET_ERR_MSG(extack, "Invalid control action value");
+		return ERR_PTR(-EINVAL);
 	}
 
 	return a;