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netfilter: nft_nat: include a flag attribute

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Both SNAT and DNAT (and the upcoming masquerade) can have additional
configuration parameters, such as port randomization and NAT addressing
persistence. We can cover these scenarios by simply adding a flag
attribute for userspace to fill when needed.

The flags to use are defined in include/uapi/linux/netfilter/nf_nat.h:

 NF_NAT_RANGE_MAP_IPS
 NF_NAT_RANGE_PROTO_SPECIFIED
 NF_NAT_RANGE_PROTO_RANDOM
 NF_NAT_RANGE_PERSISTENT
 NF_NAT_RANGE_PROTO_RANDOM_FULLY
 NF_NAT_RANGE_PROTO_RANDOM_ALL

The caller must take care of not messing up with the flags, as they are
added unconditionally to the final resulting nf_nat_range.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Arturo Borrero 2014-09-04 14:06:14 +02:00 committed by Pablo Neira Ayuso
parent b9ac12ef09
commit e42eff8a32
3 changed files with 23 additions and 0 deletions
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5
include/uapi/linux/netfilter/nf_nat.h
View File

@ -13,6 +13,11 @@
#define NF_NAT_RANGE_PROTO_RANDOM_ALL \
(NF_NAT_RANGE_PROTO_RANDOM | NF_NAT_RANGE_PROTO_RANDOM_FULLY)
#define NF_NAT_RANGE_MASK \
(NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED | \
NF_NAT_RANGE_PROTO_RANDOM | NF_NAT_RANGE_PERSISTENT | \
NF_NAT_RANGE_PROTO_RANDOM_FULLY)
struct nf_nat_ipv4_range {
unsigned int flags;
__be32 min_ip;

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

@ -785,6 +785,7 @@ enum nft_nat_types {
* @NFTA_NAT_REG_ADDR_MAX: source register of address range end (NLA_U32: nft_registers)
* @NFTA_NAT_REG_PROTO_MIN: source register of proto range start (NLA_U32: nft_registers)
* @NFTA_NAT_REG_PROTO_MAX: source register of proto range end (NLA_U32: nft_registers)
* @NFTA_NAT_FLAGS: NAT flags (see NF_NAT_RANGE_* in linux/netfilter/nf_nat.h) (NLA_U32)
*/
enum nft_nat_attributes {
NFTA_NAT_UNSPEC,
@ -794,6 +795,7 @@ enum nft_nat_attributes {
NFTA_NAT_REG_ADDR_MAX,
NFTA_NAT_REG_PROTO_MIN,
NFTA_NAT_REG_PROTO_MAX,
NFTA_NAT_FLAGS,
__NFTA_NAT_MAX
};
#define NFTA_NAT_MAX (__NFTA_NAT_MAX - 1)

16
net/netfilter/nft_nat.c
View File

@ -33,6 +33,7 @@ struct nft_nat {
enum nft_registers sreg_proto_max:8;
enum nf_nat_manip_type type:8;
u8 family;
u16 flags;
};
static void nft_nat_eval(const struct nft_expr *expr,
@ -71,6 +72,8 @@ static void nft_nat_eval(const struct nft_expr *expr,
range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
}
range.flags |= priv->flags;
data[NFT_REG_VERDICT].verdict =
nf_nat_setup_info(ct, &range, priv->type);
}
@ -82,6 +85,7 @@ static const struct nla_policy nft_nat_policy[NFTA_NAT_MAX + 1] = {
[NFTA_NAT_REG_ADDR_MAX] = { .type = NLA_U32 },
[NFTA_NAT_REG_PROTO_MIN] = { .type = NLA_U32 },
[NFTA_NAT_REG_PROTO_MAX] = { .type = NLA_U32 },
[NFTA_NAT_FLAGS] = { .type = NLA_U32 },
};
static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
@ -149,6 +153,12 @@ static int nft_nat_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
} else
priv->sreg_proto_max = priv->sreg_proto_min;
if (tb[NFTA_NAT_FLAGS]) {
priv->flags = ntohl(nla_get_be32(tb[NFTA_NAT_FLAGS]));
if (priv->flags & ~NF_NAT_RANGE_MASK)
return -EINVAL;
}
return 0;
}
@ -183,6 +193,12 @@ static int nft_nat_dump(struct sk_buff *skb, const struct nft_expr *expr)
htonl(priv->sreg_proto_max)))
goto nla_put_failure;
}
if (priv->flags != 0) {
if (nla_put_be32(skb, NFTA_NAT_FLAGS, htonl(priv->flags)))
goto nla_put_failure;
}
return 0;
nla_put_failure: