netfilter: nf_tables: Unconditionally allocate nft_obj_filter

Prep work for moving the filter into struct netlink_callback's scratch
area.
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_api.c

@@ -7717,11 +7717,9 @@ static int nf_tables_dump_obj(struct sk_buff *skb, struct netlink_callback *cb)
 				goto cont;
 			if (idx < s_idx)
 				goto cont;
-			if (filter && filter->table &&
-			    strcmp(filter->table, table->name))
+			if (filter->table && strcmp(filter->table, table->name))
 				goto cont;
-			if (filter &&
-			    filter->type != NFT_OBJECT_UNSPEC &&
+			if (filter->type != NFT_OBJECT_UNSPEC &&
 			    obj->ops->type->type != filter->type)
 				goto cont;
 
@@ -7756,23 +7754,21 @@ static int nf_tables_dump_obj_start(struct netlink_callback *cb)
 	const struct nlattr * const *nla = cb->data;
 	struct nft_obj_filter *filter = NULL;
 
-	if (nla[NFTA_OBJ_TABLE] || nla[NFTA_OBJ_TYPE]) {
-		filter = kzalloc(sizeof(*filter), GFP_ATOMIC);
-		if (!filter)
-			return -ENOMEM;
+	filter = kzalloc(sizeof(*filter), GFP_ATOMIC);
+	if (!filter)
+		return -ENOMEM;
 
-		if (nla[NFTA_OBJ_TABLE]) {
-			filter->table = nla_strdup(nla[NFTA_OBJ_TABLE], GFP_ATOMIC);
-			if (!filter->table) {
-				kfree(filter);
-				return -ENOMEM;
-			}
+	if (nla[NFTA_OBJ_TABLE]) {
+		filter->table = nla_strdup(nla[NFTA_OBJ_TABLE], GFP_ATOMIC);
+		if (!filter->table) {
+			kfree(filter);
+			return -ENOMEM;
 		}
-
-		if (nla[NFTA_OBJ_TYPE])
-			filter->type = ntohl(nla_get_be32(nla[NFTA_OBJ_TYPE]));
 	}
 
+	if (nla[NFTA_OBJ_TYPE])
+		filter->type = ntohl(nla_get_be32(nla[NFTA_OBJ_TYPE]));
+
 	cb->data = filter;
 	return 0;
 }
@@ -7781,10 +7777,8 @@ static int nf_tables_dump_obj_done(struct netlink_callback *cb)
 {
 	struct nft_obj_filter *filter = cb->data;
 
-	if (filter) {
-		kfree(filter->table);
-		kfree(filter);
-	}
+	kfree(filter->table);
+	kfree(filter);
 
 	return 0;
 }