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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: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Laura Garcia Liebana 2016-09-13 13:49:53 +02:00 committed by Pablo Neira Ayuso
parent 14e2dee099
commit 2b03bf7324
2 changed files with 28 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/uapi/linux/netfilter/nf_tables.h
View File

@ -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)

32
net/netfilter/nft_numgen.c
View File

@ -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;