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netfilter: nft_nat: include a flag attribute 

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: