net/netfilter/nft_payload.c - kernel/msm - Git at Google

 /*
  * 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/if_vlan.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>

 /* add vlan header into the user buffer for if tag was removed by offloads */
 static bool
 nft_payload_copy_vlan(u32 *d, const struct sk_buff *skb, u8 offset, u8 len)
 {
 	int mac_off = skb_mac_header(skb) - skb->data;
 	u8 vlan_len, *vlanh, *dst_u8 = (u8 *) d;
 	struct vlan_ethhdr veth;

 	vlanh = (u8 *) &veth;
 	if (offset < ETH_HLEN) {
 		u8 ethlen = min_t(u8, len, ETH_HLEN - offset);

 		if (skb_copy_bits(skb, mac_off, &veth, ETH_HLEN))
 			return false;

 		veth.h_vlan_proto = skb->vlan_proto;

 		memcpy(dst_u8, vlanh + offset, ethlen);

 		len -= ethlen;
 		if (len == 0)
 			return true;

 		dst_u8 += ethlen;
 		offset = ETH_HLEN;
 	} else if (offset >= VLAN_ETH_HLEN) {
 		offset -= VLAN_HLEN;
 		goto skip;
 	}

 	veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
 	veth.h_vlan_encapsulated_proto = skb->protocol;

 	vlanh += offset;

 	vlan_len = min_t(u8, len, VLAN_ETH_HLEN - offset);
 	memcpy(dst_u8, vlanh, vlan_len);

 	len -= vlan_len;
 	if (!len)
 		return true;

 	dst_u8 += vlan_len;
  skip:
 	return skb_copy_bits(skb, offset + mac_off, dst_u8, len) == 0;
 }

 static void nft_payload_eval(const struct nft_expr *expr,
 			     struct nft_regs *regs,
 			     const struct nft_pktinfo *pkt)
 {
 	const struct nft_payload *priv = nft_expr_priv(expr);
 	const struct sk_buff *skb = pkt->skb;
 	u32 *dest = &regs->data[priv->dreg];
 	int offset;

 	dest[priv->len / NFT_REG32_SIZE] = 0;
 	switch (priv->base) {
 	case NFT_PAYLOAD_LL_HEADER:
 		if (!skb_mac_header_was_set(skb))
 			goto err;

 		if (skb_vlan_tag_present(skb)) {
 			if (!nft_payload_copy_vlan(dest, skb,
 						   priv->offset, priv->len))
 				goto err;
 			return;
 		}
 		offset = skb_mac_header(skb) - skb->data;
 		break;
 	case NFT_PAYLOAD_NETWORK_HEADER:
 		offset = skb_network_offset(skb);
 		break;
 	case NFT_PAYLOAD_TRANSPORT_HEADER:
 		if (!pkt->tprot_set)
 			goto err;
 		offset = pkt->xt.thoff;
 		break;
 	default:
 		BUG();
 	}
 	offset += priv->offset;

 	if (skb_copy_bits(skb, offset, dest, priv->len) < 0)
 		goto err;
 	return;
 err:
 	regs->verdict.code = NFT_BREAK;
 }

 static const struct nla_policy nft_payload_policy[NFTA_PAYLOAD_MAX + 1] = {
 	[NFTA_PAYLOAD_SREG]		= { .type = NLA_U32 },
 	[NFTA_PAYLOAD_DREG]		= { .type = NLA_U32 },
 	[NFTA_PAYLOAD_BASE]		= { .type = NLA_U32 },
 	[NFTA_PAYLOAD_OFFSET]		= { .type = NLA_U32 },
 	[NFTA_PAYLOAD_LEN]		= { .type = NLA_U32 },
 	[NFTA_PAYLOAD_CSUM_TYPE]	= { .type = NLA_U32 },
 	[NFTA_PAYLOAD_CSUM_OFFSET]	= { .type = NLA_U32 },
 };

 static int nft_payload_init(const struct nft_ctx *ctx,
 			    const struct nft_expr *expr,
 			    const struct nlattr * const tb[])
 {
 	struct nft_payload *priv = nft_expr_priv(expr);

 	priv->base   = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 	priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
 	priv->len    = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
 	priv->dreg   = nft_parse_register(tb[NFTA_PAYLOAD_DREG]);

 	return nft_validate_register_store(ctx, priv->dreg, NULL,
 					   NFT_DATA_VALUE, priv->len);
 }

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

 	if (nft_dump_register(skb, NFTA_PAYLOAD_DREG, priv->dreg) ||
 	    nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
 	    nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
 	    nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)))
 		goto nla_put_failure;
 	return 0;

 nla_put_failure:
 	return -1;
 }

 static struct nft_expr_type nft_payload_type;
 static const struct nft_expr_ops nft_payload_ops = {
 	.type		= &nft_payload_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_payload)),
 	.eval		= nft_payload_eval,
 	.init		= nft_payload_init,
 	.dump		= nft_payload_dump,
 };

 const struct nft_expr_ops nft_payload_fast_ops = {
 	.type		= &nft_payload_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_payload)),
 	.eval		= nft_payload_eval,
 	.init		= nft_payload_init,
 	.dump		= nft_payload_dump,
 };

 static void nft_payload_set_eval(const struct nft_expr *expr,
 				 struct nft_regs *regs,
 				 const struct nft_pktinfo *pkt)
 {
 	const struct nft_payload_set *priv = nft_expr_priv(expr);
 	struct sk_buff *skb = pkt->skb;
 	const u32 *src = &regs->data[priv->sreg];
 	int offset, csum_offset;
 	__wsum fsum, tsum;
 	__sum16 sum;

 	switch (priv->base) {
 	case NFT_PAYLOAD_LL_HEADER:
 		if (!skb_mac_header_was_set(skb))
 			goto err;
 		offset = skb_mac_header(skb) - skb->data;
 		break;
 	case NFT_PAYLOAD_NETWORK_HEADER:
 		offset = skb_network_offset(skb);
 		break;
 	case NFT_PAYLOAD_TRANSPORT_HEADER:
 		if (!pkt->tprot_set)
 			goto err;
 		offset = pkt->xt.thoff;
 		break;
 	default:
 		BUG();
 	}

 	csum_offset = offset + priv->csum_offset;
 	offset += priv->offset;

 	if (priv->csum_type == NFT_PAYLOAD_CSUM_INET &&
 	    (priv->base != NFT_PAYLOAD_TRANSPORT_HEADER ||
 	     skb->ip_summed != CHECKSUM_PARTIAL)) {
 		if (skb_copy_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
 			goto err;

 		fsum = skb_checksum(skb, offset, priv->len, 0);
 		tsum = csum_partial(src, priv->len, 0);
 		sum = csum_fold(csum_add(csum_sub(~csum_unfold(sum), fsum),
 					 tsum));
 		if (sum == 0)
 			sum = CSUM_MANGLED_0;

 		if (!skb_make_writable(skb, csum_offset + sizeof(sum)) ||
 		    skb_store_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
 			goto err;
 	}

 	if (!skb_make_writable(skb, max(offset + priv->len, 0)) ||
 	    skb_store_bits(skb, offset, src, priv->len) < 0)
 		goto err;

 	return;
 err:
 	regs->verdict.code = NFT_BREAK;
 }

 static int nft_payload_set_init(const struct nft_ctx *ctx,
 				const struct nft_expr *expr,
 				const struct nlattr * const tb[])
 {
 	struct nft_payload_set *priv = nft_expr_priv(expr);

 	priv->base        = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 	priv->offset      = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
 	priv->len         = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
 	priv->sreg        = nft_parse_register(tb[NFTA_PAYLOAD_SREG]);

 	if (tb[NFTA_PAYLOAD_CSUM_TYPE])
 		priv->csum_type =
 			ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_TYPE]));
 	if (tb[NFTA_PAYLOAD_CSUM_OFFSET])
 		priv->csum_offset =
 			ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_OFFSET]));

 	switch (priv->csum_type) {
 	case NFT_PAYLOAD_CSUM_NONE:
 	case NFT_PAYLOAD_CSUM_INET:
 		break;
 	default:
 		return -EOPNOTSUPP;
 	}

 	return nft_validate_register_load(priv->sreg, priv->len);
 }

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

 	if (nft_dump_register(skb, NFTA_PAYLOAD_SREG, priv->sreg) ||
 	    nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) ||
 	    nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) ||
 	    nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)) ||
 	    nla_put_be32(skb, NFTA_PAYLOAD_CSUM_TYPE, htonl(priv->csum_type)) ||
 	    nla_put_be32(skb, NFTA_PAYLOAD_CSUM_OFFSET,
 			 htonl(priv->csum_offset)))
 		goto nla_put_failure;
 	return 0;

 nla_put_failure:
 	return -1;
 }

 static const struct nft_expr_ops nft_payload_set_ops = {
 	.type		= &nft_payload_type,
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_payload_set)),
 	.eval		= nft_payload_set_eval,
 	.init		= nft_payload_set_init,
 	.dump		= nft_payload_set_dump,
 };

 static const struct nft_expr_ops *
 nft_payload_select_ops(const struct nft_ctx *ctx,
 		       const struct nlattr * const tb[])
 {
 	enum nft_payload_bases base;
 	unsigned int offset, len;

 	if (tb[NFTA_PAYLOAD_BASE] == NULL ||
 	    tb[NFTA_PAYLOAD_OFFSET] == NULL ||
 	    tb[NFTA_PAYLOAD_LEN] == NULL)
 		return ERR_PTR(-EINVAL);

 	base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
 	switch (base) {
 	case NFT_PAYLOAD_LL_HEADER:
 	case NFT_PAYLOAD_NETWORK_HEADER:
 	case NFT_PAYLOAD_TRANSPORT_HEADER:
 		break;
 	default:
 		return ERR_PTR(-EOPNOTSUPP);
 	}

 	if (tb[NFTA_PAYLOAD_SREG] != NULL) {
 		if (tb[NFTA_PAYLOAD_DREG] != NULL)
 			return ERR_PTR(-EINVAL);
 		return &nft_payload_set_ops;
 	}

 	if (tb[NFTA_PAYLOAD_DREG] == NULL)
 		return ERR_PTR(-EINVAL);

 	offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
 	len    = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));

 	if (len <= 4 && is_power_of_2(len) && IS_ALIGNED(offset, len) &&
 	    base != NFT_PAYLOAD_LL_HEADER)
 		return &nft_payload_fast_ops;
 	else
 		return &nft_payload_ops;
 }

 static struct nft_expr_type nft_payload_type __read_mostly = {
 	.name		= "payload",
 	.select_ops	= nft_payload_select_ops,
 	.policy		= nft_payload_policy,
 	.maxattr	= NFTA_PAYLOAD_MAX,
 	.owner		= THIS_MODULE,
 };

 int __init nft_payload_module_init(void)
 {
 	return nft_register_expr(&nft_payload_type);
 }

 void nft_payload_module_exit(void)
 {
 	nft_unregister_expr(&nft_payload_type);
 }
	/*
	* 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/if_vlan.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>

	/* add vlan header into the user buffer for if tag was removed by offloads */
	static bool
	nft_payload_copy_vlan(u32 d, const struct sk_buff skb, u8 offset, u8 len)
	{
	int mac_off = skb_mac_header(skb) - skb->data;
	u8 vlan_len, vlanh, dst_u8 = (u8 *) d;
	struct vlan_ethhdr veth;

	vlanh = (u8 *) &veth;
	if (offset < ETH_HLEN) {
	u8 ethlen = min_t(u8, len, ETH_HLEN - offset);

	if (skb_copy_bits(skb, mac_off, &veth, ETH_HLEN))
	return false;

	veth.h_vlan_proto = skb->vlan_proto;

	memcpy(dst_u8, vlanh + offset, ethlen);

	len -= ethlen;
	if (len == 0)
	return true;

	dst_u8 += ethlen;
	offset = ETH_HLEN;
	} else if (offset >= VLAN_ETH_HLEN) {
	offset -= VLAN_HLEN;
	goto skip;
	}

	veth.h_vlan_TCI = htons(skb_vlan_tag_get(skb));
	veth.h_vlan_encapsulated_proto = skb->protocol;

	vlanh += offset;

	vlan_len = min_t(u8, len, VLAN_ETH_HLEN - offset);
	memcpy(dst_u8, vlanh, vlan_len);

	len -= vlan_len;
	if (!len)
	return true;

	dst_u8 += vlan_len;
	skip:
	return skb_copy_bits(skb, offset + mac_off, dst_u8, len) == 0;
	}

	static void nft_payload_eval(const struct nft_expr *expr,
	struct nft_regs *regs,
	const struct nft_pktinfo *pkt)
	{
	const struct nft_payload *priv = nft_expr_priv(expr);
	const struct sk_buff *skb = pkt->skb;
	u32 *dest = &regs->data[priv->dreg];
	int offset;

	dest[priv->len / NFT_REG32_SIZE] = 0;
	switch (priv->base) {
	case NFT_PAYLOAD_LL_HEADER:
	if (!skb_mac_header_was_set(skb))
	goto err;

	if (skb_vlan_tag_present(skb)) {
	if (!nft_payload_copy_vlan(dest, skb,
	priv->offset, priv->len))
	goto err;
	return;
	}
	offset = skb_mac_header(skb) - skb->data;
	break;
	case NFT_PAYLOAD_NETWORK_HEADER:
	offset = skb_network_offset(skb);
	break;
	case NFT_PAYLOAD_TRANSPORT_HEADER:
	if (!pkt->tprot_set)
	goto err;
	offset = pkt->xt.thoff;
	break;
	default:
	BUG();
	}
	offset += priv->offset;

	if (skb_copy_bits(skb, offset, dest, priv->len) < 0)
	goto err;
	return;
	err:
	regs->verdict.code = NFT_BREAK;
	}

	static const struct nla_policy nft_payload_policy[NFTA_PAYLOAD_MAX + 1] = {
	[NFTA_PAYLOAD_SREG] = { .type = NLA_U32 },
	[NFTA_PAYLOAD_DREG] = { .type = NLA_U32 },
	[NFTA_PAYLOAD_BASE] = { .type = NLA_U32 },
	[NFTA_PAYLOAD_OFFSET] = { .type = NLA_U32 },
	[NFTA_PAYLOAD_LEN] = { .type = NLA_U32 },
	[NFTA_PAYLOAD_CSUM_TYPE] = { .type = NLA_U32 },
	[NFTA_PAYLOAD_CSUM_OFFSET] = { .type = NLA_U32 },
	};

	static int nft_payload_init(const struct nft_ctx *ctx,
	const struct nft_expr *expr,
	const struct nlattr * const tb[])
	{
	struct nft_payload *priv = nft_expr_priv(expr);

	priv->base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
	priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
	priv->len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
	priv->dreg = nft_parse_register(tb[NFTA_PAYLOAD_DREG]);

	return nft_validate_register_store(ctx, priv->dreg, NULL,
	NFT_DATA_VALUE, priv->len);
	}

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

	if (nft_dump_register(skb, NFTA_PAYLOAD_DREG, priv->dreg) \|\|
	nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) \|\|
	nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) \|\|
	nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)))
	goto nla_put_failure;
	return 0;

	nla_put_failure:
	return -1;
	}

	static struct nft_expr_type nft_payload_type;
	static const struct nft_expr_ops nft_payload_ops = {
	.type = &nft_payload_type,
	.size = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
	.eval = nft_payload_eval,
	.init = nft_payload_init,
	.dump = nft_payload_dump,
	};

	const struct nft_expr_ops nft_payload_fast_ops = {
	.type = &nft_payload_type,
	.size = NFT_EXPR_SIZE(sizeof(struct nft_payload)),
	.eval = nft_payload_eval,
	.init = nft_payload_init,
	.dump = nft_payload_dump,
	};

	static void nft_payload_set_eval(const struct nft_expr *expr,
	struct nft_regs *regs,
	const struct nft_pktinfo *pkt)
	{
	const struct nft_payload_set *priv = nft_expr_priv(expr);
	struct sk_buff *skb = pkt->skb;
	const u32 *src = &regs->data[priv->sreg];
	int offset, csum_offset;
	__wsum fsum, tsum;
	__sum16 sum;

	switch (priv->base) {
	case NFT_PAYLOAD_LL_HEADER:
	if (!skb_mac_header_was_set(skb))
	goto err;
	offset = skb_mac_header(skb) - skb->data;
	break;
	case NFT_PAYLOAD_NETWORK_HEADER:
	offset = skb_network_offset(skb);
	break;
	case NFT_PAYLOAD_TRANSPORT_HEADER:
	if (!pkt->tprot_set)
	goto err;
	offset = pkt->xt.thoff;
	break;
	default:
	BUG();
	}

	csum_offset = offset + priv->csum_offset;
	offset += priv->offset;

	if (priv->csum_type == NFT_PAYLOAD_CSUM_INET &&
	(priv->base != NFT_PAYLOAD_TRANSPORT_HEADER \|\|
	skb->ip_summed != CHECKSUM_PARTIAL)) {
	if (skb_copy_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
	goto err;

	fsum = skb_checksum(skb, offset, priv->len, 0);
	tsum = csum_partial(src, priv->len, 0);
	sum = csum_fold(csum_add(csum_sub(~csum_unfold(sum), fsum),
	tsum));
	if (sum == 0)
	sum = CSUM_MANGLED_0;

	if (!skb_make_writable(skb, csum_offset + sizeof(sum)) \|\|
	skb_store_bits(skb, csum_offset, &sum, sizeof(sum)) < 0)
	goto err;
	}

	if (!skb_make_writable(skb, max(offset + priv->len, 0)) \|\|
	skb_store_bits(skb, offset, src, priv->len) < 0)
	goto err;

	return;
	err:
	regs->verdict.code = NFT_BREAK;
	}

	static int nft_payload_set_init(const struct nft_ctx *ctx,
	const struct nft_expr *expr,
	const struct nlattr * const tb[])
	{
	struct nft_payload_set *priv = nft_expr_priv(expr);

	priv->base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
	priv->offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
	priv->len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));
	priv->sreg = nft_parse_register(tb[NFTA_PAYLOAD_SREG]);

	if (tb[NFTA_PAYLOAD_CSUM_TYPE])
	priv->csum_type =
	ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_TYPE]));
	if (tb[NFTA_PAYLOAD_CSUM_OFFSET])
	priv->csum_offset =
	ntohl(nla_get_be32(tb[NFTA_PAYLOAD_CSUM_OFFSET]));

	switch (priv->csum_type) {
	case NFT_PAYLOAD_CSUM_NONE:
	case NFT_PAYLOAD_CSUM_INET:
	break;
	default:
	return -EOPNOTSUPP;
	}

	return nft_validate_register_load(priv->sreg, priv->len);
	}

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

	if (nft_dump_register(skb, NFTA_PAYLOAD_SREG, priv->sreg) \|\|
	nla_put_be32(skb, NFTA_PAYLOAD_BASE, htonl(priv->base)) \|\|
	nla_put_be32(skb, NFTA_PAYLOAD_OFFSET, htonl(priv->offset)) \|\|
	nla_put_be32(skb, NFTA_PAYLOAD_LEN, htonl(priv->len)) \|\|
	nla_put_be32(skb, NFTA_PAYLOAD_CSUM_TYPE, htonl(priv->csum_type)) \|\|
	nla_put_be32(skb, NFTA_PAYLOAD_CSUM_OFFSET,
	htonl(priv->csum_offset)))
	goto nla_put_failure;
	return 0;

	nla_put_failure:
	return -1;
	}

	static const struct nft_expr_ops nft_payload_set_ops = {
	.type = &nft_payload_type,
	.size = NFT_EXPR_SIZE(sizeof(struct nft_payload_set)),
	.eval = nft_payload_set_eval,
	.init = nft_payload_set_init,
	.dump = nft_payload_set_dump,
	};

	static const struct nft_expr_ops *
	nft_payload_select_ops(const struct nft_ctx *ctx,
	const struct nlattr * const tb[])
	{
	enum nft_payload_bases base;
	unsigned int offset, len;

	if (tb[NFTA_PAYLOAD_BASE] == NULL \|\|
	tb[NFTA_PAYLOAD_OFFSET] == NULL \|\|
	tb[NFTA_PAYLOAD_LEN] == NULL)
	return ERR_PTR(-EINVAL);

	base = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_BASE]));
	switch (base) {
	case NFT_PAYLOAD_LL_HEADER:
	case NFT_PAYLOAD_NETWORK_HEADER:
	case NFT_PAYLOAD_TRANSPORT_HEADER:
	break;
	default:
	return ERR_PTR(-EOPNOTSUPP);
	}

	if (tb[NFTA_PAYLOAD_SREG] != NULL) {
	if (tb[NFTA_PAYLOAD_DREG] != NULL)
	return ERR_PTR(-EINVAL);
	return &nft_payload_set_ops;
	}

	if (tb[NFTA_PAYLOAD_DREG] == NULL)
	return ERR_PTR(-EINVAL);

	offset = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_OFFSET]));
	len = ntohl(nla_get_be32(tb[NFTA_PAYLOAD_LEN]));

	if (len <= 4 && is_power_of_2(len) && IS_ALIGNED(offset, len) &&
	base != NFT_PAYLOAD_LL_HEADER)
	return &nft_payload_fast_ops;
	else
	return &nft_payload_ops;
	}

	static struct nft_expr_type nft_payload_type __read_mostly = {
	.name = "payload",
	.select_ops = nft_payload_select_ops,
	.policy = nft_payload_policy,
	.maxattr = NFTA_PAYLOAD_MAX,
	.owner = THIS_MODULE,
	};

	int __init nft_payload_module_init(void)
	{
	return nft_register_expr(&nft_payload_type);
	}

	void nft_payload_module_exit(void)
	{
	nft_unregister_expr(&nft_payload_type);
	}