nft_bitwise.c

/*
 * Copyright (c) 2008-2009 Patrick McHardy <kaber@trash.net>
 *
 * 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.
 *
 * Development of this code funded by Astaro AG (http://www.astaro.com/)
 */

#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_bitwise {
	enum nft_registers	sreg:8;
	enum nft_registers	dreg:8;
	u8			len;
	struct nft_data		mask;
	struct nft_data		xor;
};

static void nft_bitwise_eval(const struct nft_expr *expr,
			     struct nft_regs *regs,
			     const struct nft_pktinfo *pkt)
{
	const struct nft_bitwise *priv = nft_expr_priv(expr);
	const u32 *src = &regs->data[priv->sreg];
	u32 *dst = &regs->data[priv->dreg];
	unsigned int i;

	for (i = 0; i < DIV_ROUND_UP(priv->len, 4); i++)
		dst[i] = (src[i] & priv->mask.data[i]) ^ priv->xor.data[i];
}

static const struct nla_policy nft_bitwise_policy[NFTA_BITWISE_MAX + 1] = {
	[NFTA_BITWISE_SREG]	= { .type = NLA_U32 },
	[NFTA_BITWISE_DREG]	= { .type = NLA_U32 },
	[NFTA_BITWISE_LEN]	= { .type = NLA_U32 },
	[NFTA_BITWISE_MASK]	= { .type = NLA_NESTED },
	[NFTA_BITWISE_XOR]	= { .type = NLA_NESTED },
};

static int nft_bitwise_init(const struct nft_ctx *ctx,
			    const struct nft_expr *expr,
			    const struct nlattr * const tb[])
{
	struct nft_bitwise *priv = nft_expr_priv(expr);
	struct nft_data_desc d1, d2;
	int err;

	if (tb[NFTA_BITWISE_SREG] == NULL ||
	    tb[NFTA_BITWISE_DREG] == NULL ||
	    tb[NFTA_BITWISE_LEN] == NULL ||
	    tb[NFTA_BITWISE_MASK] == NULL ||
	    tb[NFTA_BITWISE_XOR] == NULL)
		return -EINVAL;

	priv->len  = ntohl(nla_get_be32(tb[NFTA_BITWISE_LEN]));
	priv->sreg = nft_parse_register(tb[NFTA_BITWISE_SREG]);
	err = nft_validate_register_load(priv->sreg, priv->len);
	if (err < 0)
		return err;

	priv->dreg = nft_parse_register(tb[NFTA_BITWISE_DREG]);
	err = nft_validate_register_store(ctx, priv->dreg, NULL,
					  NFT_DATA_VALUE, priv->len);
	if (err < 0)
		return err;

	err = nft_data_init(NULL, &priv->mask, &d1, tb[NFTA_BITWISE_MASK]);
	if (err < 0)
		return err;
	if (d1.len != priv->len)
		return -EINVAL;

	err = nft_data_init(NULL, &priv->xor, &d2, tb[NFTA_BITWISE_XOR]);
	if (err < 0)
		return err;
	if (d2.len != priv->len)
		return -EINVAL;

	return 0;
}

static int nft_bitwise_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
	const struct nft_bitwise *priv = nft_expr_priv(expr);

	if (nft_dump_register(skb, NFTA_BITWISE_SREG, priv->sreg))
		goto nla_put_failure;
	if (nft_dump_register(skb, NFTA_BITWISE_DREG, priv->dreg))
		goto nla_put_failure;
	if (nla_put_be32(skb, NFTA_BITWISE_LEN, htonl(priv->len)))
		goto nla_put_failure;

	if (nft_data_dump(skb, NFTA_BITWISE_MASK, &priv->mask,
			  NFT_DATA_VALUE, priv->len) < 0)
		goto nla_put_failure;

	if (nft_data_dump(skb, NFTA_BITWISE_XOR, &priv->xor,
			  NFT_DATA_VALUE, priv->len) < 0)
		goto nla_put_failure;

	return 0;

nla_put_failure:
	return -1;
}

static struct nft_expr_type nft_bitwise_type;
static const struct nft_expr_ops nft_bitwise_ops = {
	.type		= &nft_bitwise_type,
	.size		= NFT_EXPR_SIZE(sizeof(struct nft_bitwise)),
	.eval		= nft_bitwise_eval,
	.init		= nft_bitwise_init,
	.dump		= nft_bitwise_dump,
};

static struct nft_expr_type nft_bitwise_type __read_mostly = {
	.name		= "bitwise",
	.ops		= &nft_bitwise_ops,
	.policy		= nft_bitwise_policy,
	.maxattr	= NFTA_BITWISE_MAX,
	.owner		= THIS_MODULE,
};

int __init nft_bitwise_module_init(void)
{
	return nft_register_expr(&nft_bitwise_type);
}

void nft_bitwise_module_exit(void)
{
	nft_unregister_expr(&nft_bitwise_type);
}