ipv4: Validate route entry type at insert instead of every lookup.

fib_semantic_match() requires that if the type doesn't signal an
automatic error, it must be of type RTN_UNICAST, RTN_LOCAL,
RTN_BROADCAST, RTN_ANYCAST, or RTN_MULTICAST.

Checking this every route lookup is pointless work.

Instead validate it during route insertion, via fib_create_info().

Also, there was nothing making sure the type value was less than
RTN_MAX, so add that missing check while we're here.
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/fib_semantics.c

@@ -707,6 +707,9 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
 	int nhs = 1;
 	struct net *net = cfg->fc_nlinfo.nl_net;
 
+	if (cfg->fc_type > RTN_MAX)
+		goto err_inval;
+
 	/* Fast check to catch the most weird cases */
 	if (fib_props[cfg->fc_type].scope > cfg->fc_scope)
 		goto err_inval;
@@ -812,6 +815,17 @@ struct fib_info *fib_create_info(struct fib_config *cfg)
 		if (cfg->fc_gw || cfg->fc_oif || cfg->fc_mp)
 			goto err_inval;
 		goto link_it;
+	} else {
+		switch (cfg->fc_type) {
+		case RTN_UNICAST:
+		case RTN_LOCAL:
+		case RTN_BROADCAST:
+		case RTN_ANYCAST:
+		case RTN_MULTICAST:
+			break;
+		default:
+			goto err_inval;
+		}
 	}
 
 	if (cfg->fc_scope > RT_SCOPE_HOST)
@@ -915,12 +929,6 @@ int fib_semantic_match(struct fib_table *tb, struct list_head *head,
 			if (fi->fib_flags & RTNH_F_DEAD)
 				continue;
 
-			switch (fa->fa_type) {
-			case RTN_UNICAST:
-			case RTN_LOCAL:
-			case RTN_BROADCAST:
-			case RTN_ANYCAST:
-			case RTN_MULTICAST:
 			for_nexthops(fi) {
 				if (nh->nh_flags & RTNH_F_DEAD)
 					continue;
@@ -938,12 +946,6 @@ int fib_semantic_match(struct fib_table *tb, struct list_head *head,
 #endif
 			endfor_nexthops(fi);
 			continue;
-
-			default:
-				pr_warning("fib_semantic_match bad type %#x\n",
-					   fa->fa_type);
-				return -EINVAL;
-			}
 		}
 		return err;
 	}