netfilter: nft_masq: support port range

Complete masquerading support by allowing port range selection.

Signed-off-by: Pablo Neira Ayuso <[email protected]>

Author: ummakynes

include/net/netfilter/nft_masq.h

@@ -2,7 +2,9 @@
 #define _NFT_MASQ_H_
 
 struct nft_masq {
-	u32	flags;
+	u32			flags;
+	enum nft_registers      sreg_proto_min:8;
+	enum nft_registers      sreg_proto_max:8;
 };
 
 extern const struct nla_policy nft_masq_policy[];

include/uapi/linux/netfilter/nf_tables.h

@@ -951,10 +951,14 @@ enum nft_nat_attributes {
  * enum nft_masq_attributes - nf_tables masquerade expression attributes
  *
  * @NFTA_MASQ_FLAGS: NAT flags (see NF_NAT_RANGE_* in linux/netfilter/nf_nat.h) (NLA_U32)
+ * @NFTA_MASQ_REG_PROTO_MIN: source register of proto range start (NLA_U32: nft_registers)
+ * @NFTA_MASQ_REG_PROTO_MAX: source register of proto range end (NLA_U32: nft_registers)
  */
 enum nft_masq_attributes {
 	NFTA_MASQ_UNSPEC,
 	NFTA_MASQ_FLAGS,
+	NFTA_MASQ_REG_PROTO_MIN,
+	NFTA_MASQ_REG_PROTO_MAX,
 	__NFTA_MASQ_MAX
 };
 #define NFTA_MASQ_MAX		(__NFTA_MASQ_MAX - 1)

net/ipv4/netfilter/nft_masq_ipv4.c

@@ -25,7 +25,12 @@ static void nft_masq_ipv4_eval(const struct nft_expr *expr,
 
 	memset(&range, 0, sizeof(range));
 	range.flags = priv->flags;
-
+	if (priv->sreg_proto_min) {
+		range.min_proto.all =
+			*(__be16 *)&regs->data[priv->sreg_proto_min];
+		range.max_proto.all =
+			*(__be16 *)&regs->data[priv->sreg_proto_max];
+	}
 	regs->verdict.code = nf_nat_masquerade_ipv4(pkt->skb, pkt->hook,
 						    &range, pkt->out);
 }

net/ipv6/netfilter/nft_masq_ipv6.c

@@ -26,7 +26,12 @@ static void nft_masq_ipv6_eval(const struct nft_expr *expr,
 
 	memset(&range, 0, sizeof(range));
 	range.flags = priv->flags;
-
+	if (priv->sreg_proto_min) {
+		range.min_proto.all =
+			*(__be16 *)&regs->data[priv->sreg_proto_min];
+		range.max_proto.all =
+			*(__be16 *)&regs->data[priv->sreg_proto_max];
+	}
 	regs->verdict.code = nf_nat_masquerade_ipv6(pkt->skb, &range, pkt->out);
 }
 

net/netfilter/nft_masq.c

@@ -17,7 +17,9 @@
 #include <net/netfilter/nft_masq.h>
 
 const struct nla_policy nft_masq_policy[NFTA_MASQ_MAX + 1] = {
-	[NFTA_MASQ_FLAGS]	= { .type = NLA_U32 },
+	[NFTA_MASQ_FLAGS]		= { .type = NLA_U32 },
+	[NFTA_MASQ_REG_PROTO_MIN]	= { .type = NLA_U32 },
+	[NFTA_MASQ_REG_PROTO_MAX]	= { .type = NLA_U32 },
 };
 EXPORT_SYMBOL_GPL(nft_masq_policy);
 
@@ -40,19 +42,40 @@ int nft_masq_init(const struct nft_ctx *ctx,
 		  const struct nft_expr *expr,
 		  const struct nlattr * const tb[])
 {
+	u32 plen = FIELD_SIZEOF(struct nf_nat_range, min_addr.all);
 	struct nft_masq *priv = nft_expr_priv(expr);
 	int err;
 
 	err = nft_masq_validate(ctx, expr, NULL);
 	if (err)
 		return err;
 
-	if (tb[NFTA_MASQ_FLAGS] == NULL)
-		return 0;
-
-	priv->flags = ntohl(nla_get_be32(tb[NFTA_MASQ_FLAGS]));
-	if (priv->flags & ~NF_NAT_RANGE_MASK)
-		return -EINVAL;
+	if (tb[NFTA_MASQ_FLAGS]) {
+		priv->flags = ntohl(nla_get_be32(tb[NFTA_MASQ_FLAGS]));
+		if (priv->flags & ~NF_NAT_RANGE_MASK)
+			return -EINVAL;
+	}
+
+	if (tb[NFTA_MASQ_REG_PROTO_MIN]) {
+		priv->sreg_proto_min =
+			nft_parse_register(tb[NFTA_MASQ_REG_PROTO_MIN]);
+
+		err = nft_validate_register_load(priv->sreg_proto_min, plen);
+		if (err < 0)
+			return err;
+
+		if (tb[NFTA_MASQ_REG_PROTO_MAX]) {
+			priv->sreg_proto_max =
+				nft_parse_register(tb[NFTA_MASQ_REG_PROTO_MAX]);
+
+			err = nft_validate_register_load(priv->sreg_proto_max,
+							 plen);
+			if (err < 0)
+				return err;
+		} else {
+			priv->sreg_proto_max = priv->sreg_proto_min;
+		}
+	}
 
 	return 0;
 }
@@ -62,12 +85,18 @@ int nft_masq_dump(struct sk_buff *skb, const struct nft_expr *expr)
 {
 	const struct nft_masq *priv = nft_expr_priv(expr);
 
-	if (priv->flags == 0)
-		return 0;
-
-	if (nla_put_be32(skb, NFTA_MASQ_FLAGS, htonl(priv->flags)))
+	if (priv->flags != 0 &&
+	    nla_put_be32(skb, NFTA_MASQ_FLAGS, htonl(priv->flags)))
 		goto nla_put_failure;
 
+	if (priv->sreg_proto_min) {
+		if (nft_dump_register(skb, NFTA_MASQ_REG_PROTO_MIN,
+				      priv->sreg_proto_min) ||
+		    nft_dump_register(skb, NFTA_MASQ_REG_PROTO_MAX,
+				      priv->sreg_proto_max))
+			goto nla_put_failure;
+	}
+
 	return 0;
 
 nla_put_failure: