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>
diff --git a/include/uapi/linux/netfilter/nf_nat.h b/include/uapi/linux/netfilter/nf_nat.h
index 1ad3659..0880781 100644
--- a/include/uapi/linux/netfilter/nf_nat.h
+++ b/include/uapi/linux/netfilter/nf_nat.h
@@ -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;
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index c000947..6022c6e 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -785,6 +785,7 @@
* @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 @@
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)
diff --git a/net/netfilter/nft_nat.c b/net/netfilter/nft_nat.c
index 79ff58c..799550b 100644
--- a/net/netfilter/nft_nat.c
+++ b/net/netfilter/nft_nat.c
@@ -33,6 +33,7 @@
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 @@
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 @@
[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 @@
} 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 @@
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: