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Commit 2b03bf73 authored by Laura Garcia Liebana's avatar Laura Garcia Liebana Committed by Pablo Neira Ayuso
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netfilter: nft_numgen: add number generation offset 



Add support of an offset value for incremental counter and random. With
this option the sysadmin is able to start the counter to a certain value
and then apply the generated number.

Example:

	meta mark set numgen inc mod 2 offset 100

This will generate marks with the serie 100, 101, 100, 101, ...

Suggested-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: default avatarLaura Garcia Liebana <nevola@gmail.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 14e2dee0

include/uapi/linux/netfilter/nf_tables.h

+2 −0
Original line number Diff line number Diff line
@@ -1136,12 +1136,14 @@ enum nft_trace_types { 
 * @NFTA_NG_DREG: destination register (NLA_U32)

 * @NFTA_NG_MODULUS: maximum counter value (NLA_U32)

 * @NFTA_NG_TYPE: operation type (NLA_U32)

 * @NFTA_NG_OFFSET: offset to be added to the counter (NLA_U32)

 */

enum nft_ng_attributes {

	NFTA_NG_UNSPEC,

	NFTA_NG_DREG,

	NFTA_NG_MODULUS,

	NFTA_NG_TYPE,

	NFTA_NG_OFFSET,

	__NFTA_NG_MAX

};

#define NFTA_NG_MAX	(__NFTA_NG_MAX - 1)

net/netfilter/nft_numgen.c

+26 −6
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ struct nft_ng_inc { 
	enum nft_registers      dreg:8;

	u32			modulus;

	atomic_t		counter;

	u32			offset;

};



static void nft_ng_inc_eval(const struct nft_expr *expr,
@@ -37,13 +38,14 @@ static void nft_ng_inc_eval(const struct nft_expr *expr, 
		nval = (oval + 1 < priv->modulus) ? oval + 1 : 0;

	} while (atomic_cmpxchg(&priv->counter, oval, nval) != oval);



	regs->data[priv->dreg] = nval;

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

}



static const struct nla_policy nft_ng_policy[NFTA_NG_MAX + 1] = {

	[NFTA_NG_DREG]		= { .type = NLA_U32 },

	[NFTA_NG_MODULUS]	= { .type = NLA_U32 },

	[NFTA_NG_TYPE]		= { .type = NLA_U32 },

	[NFTA_NG_OFFSET]	= { .type = NLA_U32 },

};



static int nft_ng_inc_init(const struct nft_ctx *ctx,
@@ -52,10 +54,16 @@ static int nft_ng_inc_init(const struct nft_ctx *ctx, 
{

	struct nft_ng_inc *priv = nft_expr_priv(expr);



	if (tb[NFTA_NG_OFFSET])

		priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));



	priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));

	if (priv->modulus == 0)

		return -ERANGE;



	if (priv->offset + priv->modulus - 1 < priv->offset)

		return -EOVERFLOW;



	priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]);

	atomic_set(&priv->counter, 0);
@@ -64,7 +72,7 @@ static int nft_ng_inc_init(const struct nft_ctx *ctx, 
}



static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg,

		       u32 modulus, enum nft_ng_types type)

		       u32 modulus, enum nft_ng_types type, u32 offset)

{

	if (nft_dump_register(skb, NFTA_NG_DREG, dreg))

		goto nla_put_failure;
@@ -72,6 +80,8 @@ static int nft_ng_dump(struct sk_buff *skb, enum nft_registers dreg, 
		goto nla_put_failure;

	if (nla_put_be32(skb, NFTA_NG_TYPE, htonl(type)))

		goto nla_put_failure;

	if (nla_put_be32(skb, NFTA_NG_OFFSET, htonl(offset)))

		goto nla_put_failure;



	return 0;
@@ -83,12 +93,14 @@ static int nft_ng_inc_dump(struct sk_buff *skb, const struct nft_expr *expr) 
{

	const struct nft_ng_inc *priv = nft_expr_priv(expr);



	return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL);

	return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_INCREMENTAL,

			   priv->offset);

}



struct nft_ng_random {

	enum nft_registers      dreg:8;

	u32			modulus;

	u32			offset;

};



static void nft_ng_random_eval(const struct nft_expr *expr,
@@ -97,9 +109,10 @@ static void nft_ng_random_eval(const struct nft_expr *expr, 
{

	struct nft_ng_random *priv = nft_expr_priv(expr);

	struct rnd_state *state = this_cpu_ptr(&nft_numgen_prandom_state);

	u32 val;



	regs->data[priv->dreg] = reciprocal_scale(prandom_u32_state(state),

						  priv->modulus);

	val = reciprocal_scale(prandom_u32_state(state), priv->modulus);

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

}



static int nft_ng_random_init(const struct nft_ctx *ctx,
@@ -108,10 +121,16 @@ static int nft_ng_random_init(const struct nft_ctx *ctx, 
{

	struct nft_ng_random *priv = nft_expr_priv(expr);



	if (tb[NFTA_NG_OFFSET])

		priv->offset = ntohl(nla_get_be32(tb[NFTA_NG_OFFSET]));



	priv->modulus = ntohl(nla_get_be32(tb[NFTA_NG_MODULUS]));

	if (priv->modulus == 0)

		return -ERANGE;



	if (priv->offset + priv->modulus - 1 < priv->offset)

		return -EOVERFLOW;



	prandom_init_once(&nft_numgen_prandom_state);



	priv->dreg = nft_parse_register(tb[NFTA_NG_DREG]);
@@ -124,7 +143,8 @@ static int nft_ng_random_dump(struct sk_buff *skb, const struct nft_expr *expr) 
{

	const struct nft_ng_random *priv = nft_expr_priv(expr);



	return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM);

	return nft_ng_dump(skb, priv->dreg, priv->modulus, NFT_NG_RANDOM,

			   priv->offset);

}



static struct nft_expr_type nft_ng_type;