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Commit 0071e184 authored by Arturo Borrero's avatar Arturo Borrero Committed by Pablo Neira Ayuso
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netfilter: nf_tables: add support for inverted logic in nft_lookup 



Introduce a new configuration option for this expression, which allows users
to invert the logic of set lookups.

In _init() we will now return EINVAL if NFT_LOOKUP_F_INV is in anyway
related to a map lookup.

The code in the _eval() function has been untangled and updated to sopport the
XOR of options, as we should consider 4 cases:
 * lookup false, invert false -> NFT_BREAK
 * lookup false, invert true -> return w/o NFT_BREAK
 * lookup true, invert false -> return w/o NFT_BREAK
 * lookup true, invert true -> NFT_BREAK

Signed-off-by: default avatarArturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 82bec71d

include/uapi/linux/netfilter/nf_tables.h

+6 −0
Original line number Diff line number Diff line
@@ -546,6 +546,10 @@ enum nft_cmp_attributes { 
};

#define NFTA_CMP_MAX		(__NFTA_CMP_MAX - 1)



enum nft_lookup_flags {

	NFT_LOOKUP_F_INV = (1 << 0),

};



/**

 * enum nft_lookup_attributes - nf_tables set lookup expression netlink attributes

 *
@@ -553,6 +557,7 @@ enum nft_cmp_attributes { 
 * @NFTA_LOOKUP_SREG: source register of the data to look for (NLA_U32: nft_registers)

 * @NFTA_LOOKUP_DREG: destination register (NLA_U32: nft_registers)

 * @NFTA_LOOKUP_SET_ID: uniquely identifies a set in a transaction (NLA_U32)

 * @NFTA_LOOKUP_FLAGS: flags (NLA_U32: enum nft_lookup_flags)

 */

enum nft_lookup_attributes {

	NFTA_LOOKUP_UNSPEC,
@@ -560,6 +565,7 @@ enum nft_lookup_attributes { 
	NFTA_LOOKUP_SREG,

	NFTA_LOOKUP_DREG,

	NFTA_LOOKUP_SET_ID,

	NFTA_LOOKUP_FLAGS,

	__NFTA_LOOKUP_MAX

};

#define NFTA_LOOKUP_MAX		(__NFTA_LOOKUP_MAX - 1)

net/netfilter/nft_lookup.c

+32 −5
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ struct nft_lookup { 
	struct nft_set			*set;

	enum nft_registers		sreg:8;

	enum nft_registers		dreg:8;

	bool				invert;

	struct nft_set_binding		binding;

};
@@ -32,14 +33,20 @@ static void nft_lookup_eval(const struct nft_expr *expr, 
	const struct nft_lookup *priv = nft_expr_priv(expr);

	const struct nft_set *set = priv->set;

	const struct nft_set_ext *ext;

	bool found;



	if (set->ops->lookup(set, &regs->data[priv->sreg], &ext)) {

		if (set->flags & NFT_SET_MAP)

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

				      nft_set_ext_data(ext), set->dlen);

	found = set->ops->lookup(set, &regs->data[priv->sreg], &ext) ^

		priv->invert;



	if (!found) {

		regs->verdict.code = NFT_BREAK;

		return;

	}

	regs->verdict.code = NFT_BREAK;



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

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

			      nft_set_ext_data(ext), set->dlen);



}



static const struct nla_policy nft_lookup_policy[NFTA_LOOKUP_MAX + 1] = {
@@ -47,6 +54,7 @@ static const struct nla_policy nft_lookup_policy[NFTA_LOOKUP_MAX + 1] = { 
	[NFTA_LOOKUP_SET_ID]	= { .type = NLA_U32 },

	[NFTA_LOOKUP_SREG]	= { .type = NLA_U32 },

	[NFTA_LOOKUP_DREG]	= { .type = NLA_U32 },

	[NFTA_LOOKUP_FLAGS]	= { .type = NLA_U32 },

};



static int nft_lookup_init(const struct nft_ctx *ctx,
@@ -56,6 +64,7 @@ static int nft_lookup_init(const struct nft_ctx *ctx, 
	struct nft_lookup *priv = nft_expr_priv(expr);

	u8 genmask = nft_genmask_next(ctx->net);

	struct nft_set *set;

	u32 flags;

	int err;



	if (tb[NFTA_LOOKUP_SET] == NULL ||
@@ -81,7 +90,22 @@ static int nft_lookup_init(const struct nft_ctx *ctx, 
	if (err < 0)

		return err;



	if (tb[NFTA_LOOKUP_FLAGS]) {

		flags = ntohl(nla_get_be32(tb[NFTA_LOOKUP_FLAGS]));



		if (flags & ~NFT_LOOKUP_F_INV)

			return -EINVAL;



		if (flags & NFT_LOOKUP_F_INV) {

			if (set->flags & NFT_SET_MAP)

				return -EINVAL;

			priv->invert = true;

		}

	}



	if (tb[NFTA_LOOKUP_DREG] != NULL) {

		if (priv->invert)

			return -EINVAL;

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

			return -EINVAL;
@@ -114,6 +138,7 @@ static void nft_lookup_destroy(const struct nft_ctx *ctx, 
static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr)

{

	const struct nft_lookup *priv = nft_expr_priv(expr);

	u32 flags = priv->invert ? NFT_LOOKUP_F_INV : 0;



	if (nla_put_string(skb, NFTA_LOOKUP_SET, priv->set->name))

		goto nla_put_failure;
@@ -122,6 +147,8 @@ static int nft_lookup_dump(struct sk_buff *skb, const struct nft_expr *expr) 
	if (priv->set->flags & NFT_SET_MAP)

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

			goto nla_put_failure;

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

		goto nla_put_failure;

	return 0;



nla_put_failure: