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Commit 0f3cd9b3 authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso
Browse files

netfilter: nf_tables: add range expression 



Inverse ranges != [a,b] are not currently possible because rules are
composites of && operations, and we need to express this:

	data < a || data > b

This patch adds a new range expression. Positive ranges can be already
through two cmp expressions:

	cmp(sreg, data, >=)
	cmp(sreg, data, <=)

This new range expression provides an alternative way to express this.

Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 7a682575

include/net/netfilter/nf_tables_core.h

+3 −0
Original line number Diff line number Diff line
@@ -28,6 +28,9 @@ extern const struct nft_expr_ops nft_cmp_fast_ops; 
int nft_cmp_module_init(void);

void nft_cmp_module_exit(void);



int nft_range_module_init(void);

void nft_range_module_exit(void);



int nft_lookup_module_init(void);

void nft_lookup_module_exit(void);

include/uapi/linux/netfilter/nf_tables.h

+29 −0
Original line number Diff line number Diff line
@@ -546,6 +546,35 @@ enum nft_cmp_attributes { 
};

#define NFTA_CMP_MAX		(__NFTA_CMP_MAX - 1)



/**

 * enum nft_range_ops - nf_tables range operator

 *

 * @NFT_RANGE_EQ: equal

 * @NFT_RANGE_NEQ: not equal

 */

enum nft_range_ops {

	NFT_RANGE_EQ,

	NFT_RANGE_NEQ,

};



/**

 * enum nft_range_attributes - nf_tables range expression netlink attributes

 *

 * @NFTA_RANGE_SREG: source register of data to compare (NLA_U32: nft_registers)

 * @NFTA_RANGE_OP: cmp operation (NLA_U32: nft_cmp_ops)

 * @NFTA_RANGE_FROM_DATA: data range from (NLA_NESTED: nft_data_attributes)

 * @NFTA_RANGE_TO_DATA: data range to (NLA_NESTED: nft_data_attributes)

 */

enum nft_range_attributes {

	NFTA_RANGE_UNSPEC,

	NFTA_RANGE_SREG,

	NFTA_RANGE_OP,

	NFTA_RANGE_FROM_DATA,

	NFTA_RANGE_TO_DATA,

	__NFTA_RANGE_MAX

};

#define NFTA_RANGE_MAX		(__NFTA_RANGE_MAX - 1)



enum nft_lookup_flags {

	NFT_LOOKUP_F_INV = (1 << 0),

};

net/netfilter/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -71,8 +71,9 @@ obj-$(CONFIG_NF_DUP_NETDEV) += nf_dup_netdev.o 


# nf_tables

nf_tables-objs += nf_tables_core.o nf_tables_api.o nf_tables_trace.o

nf_tables-objs += nft_immediate.o nft_cmp.o nft_lookup.o nft_dynset.o

nf_tables-objs += nft_immediate.o nft_cmp.o nft_range.o

nf_tables-objs += nft_bitwise.o nft_byteorder.o nft_payload.o

nf_tables-objs += nft_lookup.o nft_dynset.o



obj-$(CONFIG_NF_TABLES)		+= nf_tables.o

obj-$(CONFIG_NF_TABLES_INET)	+= nf_tables_inet.o

net/netfilter/nf_tables_core.c

+6 −1
Original line number Diff line number Diff line
@@ -263,8 +263,13 @@ int __init nf_tables_core_module_init(void) 
	if (err < 0)

		goto err7;



	return 0;

	err = nft_range_module_init();

	if (err < 0)

		goto err8;



	return 0;

err8:

	nft_dynset_module_exit();

err7:

	nft_payload_module_exit();

err6:

net/netfilter/nft_range.c

0 → 100644
+138 −0
Original line number Diff line number Diff line 
/*

 * Copyright (c) 2016 Pablo Neira Ayuso <pablo@netfilter.org>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */



#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/netlink.h>

#include <linux/netfilter.h>

#include <linux/netfilter/nf_tables.h>

#include <net/netfilter/nf_tables_core.h>

#include <net/netfilter/nf_tables.h>



struct nft_range_expr {

	struct nft_data		data_from;

	struct nft_data		data_to;

	enum nft_registers	sreg:8;

	u8			len;

	enum nft_range_ops	op:8;

};



static void nft_range_eval(const struct nft_expr *expr,

			 struct nft_regs *regs,

			 const struct nft_pktinfo *pkt)

{

	const struct nft_range_expr *priv = nft_expr_priv(expr);

	bool mismatch;

	int d1, d2;



	d1 = memcmp(&regs->data[priv->sreg], &priv->data_from, priv->len);

	d2 = memcmp(&regs->data[priv->sreg], &priv->data_to, priv->len);

	switch (priv->op) {

	case NFT_RANGE_EQ:

		mismatch = (d1 < 0 || d2 > 0);

		break;

	case NFT_RANGE_NEQ:

		mismatch = (d1 >= 0 && d2 <= 0);

		break;

	}



	if (mismatch)

		regs->verdict.code = NFT_BREAK;

}



static const struct nla_policy nft_range_policy[NFTA_RANGE_MAX + 1] = {

	[NFTA_RANGE_SREG]		= { .type = NLA_U32 },

	[NFTA_RANGE_OP]			= { .type = NLA_U32 },

	[NFTA_RANGE_FROM_DATA]		= { .type = NLA_NESTED },

	[NFTA_RANGE_TO_DATA]		= { .type = NLA_NESTED },

};



static int nft_range_init(const struct nft_ctx *ctx, const struct nft_expr *expr,

			const struct nlattr * const tb[])

{

	struct nft_range_expr *priv = nft_expr_priv(expr);

	struct nft_data_desc desc_from, desc_to;

	int err;



	err = nft_data_init(NULL, &priv->data_from, sizeof(priv->data_from),

			    &desc_from, tb[NFTA_RANGE_FROM_DATA]);

	if (err < 0)

		return err;



	err = nft_data_init(NULL, &priv->data_to, sizeof(priv->data_to),

			    &desc_to, tb[NFTA_RANGE_TO_DATA]);

	if (err < 0)

		goto err1;



	if (desc_from.len != desc_to.len) {

		err = -EINVAL;

		goto err2;

	}



	priv->sreg = nft_parse_register(tb[NFTA_RANGE_SREG]);

	err = nft_validate_register_load(priv->sreg, desc_from.len);

	if (err < 0)

		goto err2;



	priv->op  = ntohl(nla_get_be32(tb[NFTA_RANGE_OP]));

	priv->len = desc_from.len;

	return 0;

err2:

	nft_data_uninit(&priv->data_to, desc_to.type);

err1:

	nft_data_uninit(&priv->data_from, desc_from.type);

	return err;

}



static int nft_range_dump(struct sk_buff *skb, const struct nft_expr *expr)

{

	const struct nft_range_expr *priv = nft_expr_priv(expr);



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

		goto nla_put_failure;

	if (nla_put_be32(skb, NFTA_RANGE_OP, htonl(priv->op)))

		goto nla_put_failure;



	if (nft_data_dump(skb, NFTA_RANGE_FROM_DATA, &priv->data_from,

			  NFT_DATA_VALUE, priv->len) < 0 ||

	    nft_data_dump(skb, NFTA_RANGE_TO_DATA, &priv->data_to,

			  NFT_DATA_VALUE, priv->len) < 0)

		goto nla_put_failure;

	return 0;



nla_put_failure:

	return -1;

}



static struct nft_expr_type nft_range_type;

static const struct nft_expr_ops nft_range_ops = {

	.type		= &nft_range_type,

	.size		= NFT_EXPR_SIZE(sizeof(struct nft_range_expr)),

	.eval		= nft_range_eval,

	.init		= nft_range_init,

	.dump		= nft_range_dump,

};



static struct nft_expr_type nft_range_type __read_mostly = {

	.name		= "range",

	.ops		= &nft_range_ops,

	.policy		= nft_range_policy,

	.maxattr	= NFTA_RANGE_MAX,

	.owner		= THIS_MODULE,

};



int __init nft_range_module_init(void)

{

	return nft_register_expr(&nft_range_type);

}



void nft_range_module_exit(void)

{

	nft_unregister_expr(&nft_range_type);

}