Commit b9ccc07e authored by Laura Garcia Liebana's avatar Laura Garcia Liebana Committed by Pablo Neira Ayuso
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netfilter: nft_hash: add map lookups for hashing operations 



This patch creates new attributes to accept a map as argument and
then perform the lookup with the generated hash accordingly.

Both current hash functions are supported: Jenkins and Symmetric Hash.

Signed-off-by: default avatarLaura Garcia Liebana <nevola@gmail.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 978d8f90

include/uapi/linux/netfilter/nf_tables.h

+4 −0
Original line number Diff line number Diff line
@@ -856,6 +856,8 @@ enum nft_hash_types { 
 * @NFTA_HASH_SEED: seed value (NLA_U32)

 * @NFTA_HASH_OFFSET: add this offset value to hash result (NLA_U32)

 * @NFTA_HASH_TYPE: hash operation (NLA_U32: nft_hash_types)

 * @NFTA_HASH_SET_NAME: name of the map to lookup (NLA_STRING)

 * @NFTA_HASH_SET_ID: id of the map (NLA_U32)

 */

enum nft_hash_attributes {

	NFTA_HASH_UNSPEC,
@@ -866,6 +868,8 @@ enum nft_hash_attributes { 
	NFTA_HASH_SEED,

	NFTA_HASH_OFFSET,

	NFTA_HASH_TYPE,

	NFTA_HASH_SET_NAME,

	NFTA_HASH_SET_ID,

	__NFTA_HASH_MAX,

};

#define NFTA_HASH_MAX	(__NFTA_HASH_MAX - 1)

net/netfilter/nft_hash.c

+130 −1
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ struct nft_jhash { 
	u32			modulus;

	u32			seed;

	u32			offset;

	struct nft_set		*map;

};



static void nft_jhash_eval(const struct nft_expr *expr,
@@ -35,14 +36,39 @@ static void nft_jhash_eval(const struct nft_expr *expr, 
	const void *data = &regs->data[priv->sreg];

	u32 h;



	h = reciprocal_scale(jhash(data, priv->len, priv->seed), priv->modulus);

	h = reciprocal_scale(jhash(data, priv->len, priv->seed),

			     priv->modulus);



	regs->data[priv->dreg] = h + priv->offset;

}



static void nft_jhash_map_eval(const struct nft_expr *expr,

			       struct nft_regs *regs,

			       const struct nft_pktinfo *pkt)

{

	struct nft_jhash *priv = nft_expr_priv(expr);

	const void *data = &regs->data[priv->sreg];

	const struct nft_set *map = priv->map;

	const struct nft_set_ext *ext;

	u32 result;

	bool found;



	result = reciprocal_scale(jhash(data, priv->len, priv->seed),

					priv->modulus) + priv->offset;



	found = map->ops->lookup(nft_net(pkt), map, &result, &ext);

	if (!found)

		return;



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

		      nft_set_ext_data(ext), map->dlen);

}



struct nft_symhash {

	enum nft_registers      dreg:8;

	u32			modulus;

	u32			offset;

	struct nft_set		*map;

};



static void nft_symhash_eval(const struct nft_expr *expr,
@@ -58,6 +84,28 @@ static void nft_symhash_eval(const struct nft_expr *expr, 
	regs->data[priv->dreg] = h + priv->offset;

}



static void nft_symhash_map_eval(const struct nft_expr *expr,

				 struct nft_regs *regs,

				 const struct nft_pktinfo *pkt)

{

	struct nft_symhash *priv = nft_expr_priv(expr);

	struct sk_buff *skb = pkt->skb;

	const struct nft_set *map = priv->map;

	const struct nft_set_ext *ext;

	u32 result;

	bool found;



	result = reciprocal_scale(__skb_get_hash_symmetric(skb),

				  priv->modulus) + priv->offset;



	found = map->ops->lookup(nft_net(pkt), map, &result, &ext);

	if (!found)

		return;



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

		      nft_set_ext_data(ext), map->dlen);

}



static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = {

	[NFTA_HASH_SREG]	= { .type = NLA_U32 },

	[NFTA_HASH_DREG]	= { .type = NLA_U32 },
@@ -66,6 +114,9 @@ static const struct nla_policy nft_hash_policy[NFTA_HASH_MAX + 1] = { 
	[NFTA_HASH_SEED]	= { .type = NLA_U32 },

	[NFTA_HASH_OFFSET]	= { .type = NLA_U32 },

	[NFTA_HASH_TYPE]	= { .type = NLA_U32 },

	[NFTA_HASH_SET_NAME]	= { .type = NLA_STRING,

				    .len = NFT_SET_MAXNAMELEN - 1 },

	[NFTA_HASH_SET_ID]	= { .type = NLA_U32 },

};



static int nft_jhash_init(const struct nft_ctx *ctx,
@@ -115,6 +166,23 @@ static int nft_jhash_init(const struct nft_ctx *ctx, 
					   NFT_DATA_VALUE, sizeof(u32));

}



static int nft_jhash_map_init(const struct nft_ctx *ctx,

			      const struct nft_expr *expr,

			      const struct nlattr * const tb[])

{

	struct nft_jhash *priv = nft_expr_priv(expr);

	u8 genmask = nft_genmask_next(ctx->net);



	nft_jhash_init(ctx, expr, tb);

	priv->map = nft_set_lookup_global(ctx->net, ctx->table,

					  tb[NFTA_HASH_SET_NAME],

					  tb[NFTA_HASH_SET_ID], genmask);

	if (IS_ERR(priv->map))

		return PTR_ERR(priv->map);



	return 0;

}



static int nft_symhash_init(const struct nft_ctx *ctx,

			    const struct nft_expr *expr,

			    const struct nlattr * const tb[])
@@ -141,6 +209,23 @@ static int nft_symhash_init(const struct nft_ctx *ctx, 
					   NFT_DATA_VALUE, sizeof(u32));

}



static int nft_symhash_map_init(const struct nft_ctx *ctx,

				const struct nft_expr *expr,

				const struct nlattr * const tb[])

{

	struct nft_jhash *priv = nft_expr_priv(expr);

	u8 genmask = nft_genmask_next(ctx->net);



	nft_symhash_init(ctx, expr, tb);

	priv->map = nft_set_lookup_global(ctx->net, ctx->table,

					  tb[NFTA_HASH_SET_NAME],

					  tb[NFTA_HASH_SET_ID], genmask);

	if (IS_ERR(priv->map))

		return PTR_ERR(priv->map);



	return 0;

}



static int nft_jhash_dump(struct sk_buff *skb,

			  const struct nft_expr *expr)

{
@@ -168,6 +253,18 @@ static int nft_jhash_dump(struct sk_buff *skb, 
	return -1;

}



static int nft_jhash_map_dump(struct sk_buff *skb,

			       const struct nft_expr *expr)

{

	const struct nft_jhash *priv = nft_expr_priv(expr);



	if (nft_jhash_dump(skb, expr) ||

	    nla_put_string(skb, NFTA_HASH_SET_NAME, priv->map->name))

		return -1;



	return 0;

}



static int nft_symhash_dump(struct sk_buff *skb,

			    const struct nft_expr *expr)

{
@@ -188,6 +285,18 @@ static int nft_symhash_dump(struct sk_buff *skb, 
	return -1;

}



static int nft_symhash_map_dump(struct sk_buff *skb,

				const struct nft_expr *expr)

{

	const struct nft_symhash *priv = nft_expr_priv(expr);



	if (nft_symhash_dump(skb, expr) ||

	    nla_put_string(skb, NFTA_HASH_SET_NAME, priv->map->name))

		return -1;



	return 0;

}



static struct nft_expr_type nft_hash_type;

static const struct nft_expr_ops nft_jhash_ops = {

	.type		= &nft_hash_type,
@@ -197,6 +306,14 @@ static const struct nft_expr_ops nft_jhash_ops = { 
	.dump		= nft_jhash_dump,

};



static const struct nft_expr_ops nft_jhash_map_ops = {

	.type		= &nft_hash_type,

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

	.eval		= nft_jhash_map_eval,

	.init		= nft_jhash_map_init,

	.dump		= nft_jhash_map_dump,

};



static const struct nft_expr_ops nft_symhash_ops = {

	.type		= &nft_hash_type,

	.size		= NFT_EXPR_SIZE(sizeof(struct nft_symhash)),
@@ -205,6 +322,14 @@ static const struct nft_expr_ops nft_symhash_ops = { 
	.dump		= nft_symhash_dump,

};



static const struct nft_expr_ops nft_symhash_map_ops = {

	.type		= &nft_hash_type,

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

	.eval		= nft_symhash_map_eval,

	.init		= nft_symhash_map_init,

	.dump		= nft_symhash_map_dump,

};



static const struct nft_expr_ops *

nft_hash_select_ops(const struct nft_ctx *ctx,

		    const struct nlattr * const tb[])
@@ -217,8 +342,12 @@ nft_hash_select_ops(const struct nft_ctx *ctx, 
	type = ntohl(nla_get_be32(tb[NFTA_HASH_TYPE]));

	switch (type) {

	case NFT_HASH_SYM:

		if (tb[NFTA_HASH_SET_NAME])

			return &nft_symhash_map_ops;

		return &nft_symhash_ops;

	case NFT_HASH_JENKINS:

		if (tb[NFTA_HASH_SET_NAME])

			return &nft_jhash_map_ops;

		return &nft_jhash_ops;

	default:

		break;