netfilter: nf_tables: add new nft_masq expression

The nft_masq expression is intended to perform NAT in the masquerade flavour.

We decided to have the masquerade functionality in a separated expression other
than nft_nat.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 59 insertions, 0 deletions

diff --git a/net/netfilter/nft_masq.c b/net/netfilter/nft_masq.c
new file mode 100644
index 000000000000..6637bab00567
--- /dev/null
+++ b/net/netfilter/nft_masq.c
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2014 Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/netlink.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter/nf_tables.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nft_masq.h>
+
+const struct nla_policy nft_masq_policy[NFTA_MASQ_MAX + 1] = {
+	[NFTA_MASQ_FLAGS]	= { .type = NLA_U32 },
+};
+EXPORT_SYMBOL_GPL(nft_masq_policy);
+
+int nft_masq_init(const struct nft_ctx *ctx,
+		  const struct nft_expr *expr,
+		  const struct nlattr * const tb[])
+{
+	struct nft_masq *priv = nft_expr_priv(expr);
+
+	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;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nft_masq_init);
+
+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)))
+		goto nla_put_failure;
+
+	return 0;
+
+nla_put_failure:
+	return -1;
+}
+EXPORT_SYMBOL_GPL(nft_masq_dump);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>");