netfilter: nf_tables: skip set types that do not support for expressions

The bitmap set does not support for expressions, skip it from the
estimation step.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_tables.h

@@ -266,6 +266,7 @@ struct nft_set_iter {
  *	@size: number of set elements
  *	@field_len: length of each field in concatenation, bytes
  *	@field_count: number of concatenated fields in element
+ *	@expr: set must support for expressions
  */
 struct nft_set_desc {
 	unsigned int		klen;
@@ -273,6 +274,7 @@ struct nft_set_desc {
 	unsigned int		size;
 	u8			field_len[NFT_REG32_COUNT];
 	u8			field_count;
+	bool			expr;
 };
 
 /**

net/netfilter/nf_tables_api.c

@@ -4032,6 +4032,9 @@ static int nf_tables_newset(struct net *net, struct sock *nlsk,
 			return err;
 	}
 
+	if (nla[NFTA_SET_EXPR])
+		desc.expr = true;
+
 	table = nft_table_lookup(net, nla[NFTA_SET_TABLE], family, genmask);
 	if (IS_ERR(table)) {
 		NL_SET_BAD_ATTR(extack, nla[NFTA_SET_TABLE]);

net/netfilter/nft_set_bitmap.c

@@ -286,6 +286,8 @@ static bool nft_bitmap_estimate(const struct nft_set_desc *desc, u32 features,
 	/* Make sure bitmaps we don't get bitmaps larger than 16 Kbytes. */
 	if (desc->klen > 2)
 		return false;
+	else if (desc->expr)
+		return false;
 
 	est->size   = nft_bitmap_total_size(desc->klen);
 	est->lookup = NFT_SET_CLASS_O_1;