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 1ad3659102b64d54a8ad814fd7be11132a136319..0880781ad7b699811d5971cbf18f3cd2ccd3082d 100644 (file)
--- 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 c000947d3f38e4fe1f444ad233ccce05b28b4402..6022c6e6be187dfc9c8accedaa5d1ad194d281c9 100644 (file)
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -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)

diff --git a/net/netfilter/nft_nat.c b/net/netfilter/nft_nat.c
index 79ff58cd36dc42c053ef272905457bf08db3d6ef..799550b476fbdeeadc2745aaff97fe5f2b197761 100644 (file)
--- a/net/netfilter/nft_nat.c
+++ b/net/netfilter/nft_nat.c
@@ -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: