Commit a4878eea authored by Florian Westphal's avatar Florian Westphal
Browse files

netfilter: nf_tables: relax set/map validation checks 



Its currently not allowed to perform queries on a map, for example:

table t {
	map m {
		typeof ip saddr : meta mark
		..

	chain c {
		ip saddr @m counter

will fail, because kernel requires that userspace provides a destination
register when the referenced set is a map.

However, internally there is no real distinction between sets and maps,
maps are just sets where each key is associated with a value.

Relax this so that maps can be used just like sets.

This allows to have rules that query if a given key exists
without making use of the associated value.

This also permits != checks which don't work for map lookups.

When no destination reg is given for a map, then permit this for named
maps.

Data and dump paths need to be updated to consider priv->dreg_set
instead of the 'set-is-a-map' check.

Checks in reduce and validate callbacks are not changed, this
can be relaxed later if a need arises.

Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
parent b50a8b0d

net/netfilter/nft_lookup.c

+15 −8
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ struct nft_lookup { 
	struct nft_set			*set;

	u8				sreg;

	u8				dreg;

	bool				dreg_set;

	bool				invert;

	struct nft_set_binding		binding;

};
@@ -75,7 +76,7 @@ void nft_lookup_eval(const struct nft_expr *expr, 
	}



	if (ext) {

		if (set->flags & NFT_SET_MAP)

		if (priv->dreg_set)

			nft_data_copy(&regs->data[priv->dreg],

				      nft_set_ext_data(ext), set->dlen);
@@ -122,12 +123,9 @@ static int nft_lookup_init(const struct nft_ctx *ctx, 
		if (flags & ~NFT_LOOKUP_F_INV)

			return -EINVAL;



		if (flags & NFT_LOOKUP_F_INV) {

			if (set->flags & NFT_SET_MAP)

				return -EINVAL;

		if (flags & NFT_LOOKUP_F_INV)

			priv->invert = true;

	}

	}



	if (tb[NFTA_LOOKUP_DREG] != NULL) {

		if (priv->invert)
@@ -140,8 +138,17 @@ static int nft_lookup_init(const struct nft_ctx *ctx, 
					       set->dlen);

		if (err < 0)

			return err;

	} else if (set->flags & NFT_SET_MAP)

		priv->dreg_set = true;

	} else if (set->flags & NFT_SET_MAP) {

		/* Map given, but user asks for lookup only (i.e. to

		 * ignore value assoicated with key).

		 *

		 * This makes no sense for anonymous maps since they are

		 * scoped to the rule, but for named sets this can be useful.

		 */

		if (set->flags & NFT_SET_ANONYMOUS)

			return -EINVAL;

	}



	priv->binding.flags = set->flags & NFT_SET_MAP;
@@ -188,7 +195,7 @@ static int nft_lookup_dump(struct sk_buff *skb, 
		goto nla_put_failure;

	if (nft_dump_register(skb, NFTA_LOOKUP_SREG, priv->sreg))

		goto nla_put_failure;

	if (priv->set->flags & NFT_SET_MAP)

	if (priv->dreg_set)

		if (nft_dump_register(skb, NFTA_LOOKUP_DREG, priv->dreg))

			goto nla_put_failure;

	if (nla_put_be32(skb, NFTA_LOOKUP_FLAGS, htonl(flags)))