netfilter: nf_tables: add new expression nft_redir

This new expression provides NAT in the redirect flavour, which is to
redirect packets to local machine.

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

1 files changed, 98 insertions, 0 deletions

diff --git a/net/netfilter/nft_redir.c b/net/netfilter/nft_redir.c
new file mode 100644
index 000000000000..e27b4e35718a
--- /dev/null
+++ b/net/netfilter/nft_redir.c
@@ -0,0 +1,98 @@
+/*
+ * 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_nat.h>
+#include <net/netfilter/nf_tables.h>
+#include <net/netfilter/nft_redir.h>
+
+const struct nla_policy nft_redir_policy[NFTA_REDIR_MAX + 1] = {
+	[NFTA_REDIR_REG_PROTO_MIN]	= { .type = NLA_U32 },
+	[NFTA_REDIR_REG_PROTO_MAX]	= { .type = NLA_U32 },
+	[NFTA_REDIR_FLAGS]		= { .type = NLA_U32 },
+};
+EXPORT_SYMBOL_GPL(nft_redir_policy);
+
+int nft_redir_init(const struct nft_ctx *ctx,
+		   const struct nft_expr *expr,
+		   const struct nlattr * const tb[])
+{
+	struct nft_redir *priv = nft_expr_priv(expr);
+	u32 nla_be32;
+	int err;
+
+	err = nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
+	if (err < 0)
+		return err;
+
+	if (tb[NFTA_REDIR_REG_PROTO_MIN]) {
+		nla_be32 = nla_get_be32(tb[NFTA_REDIR_REG_PROTO_MIN]);
+		priv->sreg_proto_min = ntohl(nla_be32);
+		err = nft_validate_input_register(priv->sreg_proto_min);
+		if (err < 0)
+			return err;
+
+		if (tb[NFTA_REDIR_REG_PROTO_MAX]) {
+			nla_be32 = nla_get_be32(tb[NFTA_REDIR_REG_PROTO_MAX]);
+			priv->sreg_proto_max = ntohl(nla_be32);
+			err = nft_validate_input_register(priv->sreg_proto_max);
+			if (err < 0)
+				return err;
+		} else {
+			priv->sreg_proto_max = priv->sreg_proto_min;
+		}
+	}
+
+	if (tb[NFTA_REDIR_FLAGS]) {
+		priv->flags = ntohl(nla_get_be32(tb[NFTA_REDIR_FLAGS]));
+		if (priv->flags & ~NF_NAT_RANGE_MASK)
+			return -EINVAL;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nft_redir_init);
+
+int nft_redir_dump(struct sk_buff *skb, const struct nft_expr *expr)
+{
+	const struct nft_redir *priv = nft_expr_priv(expr);
+
+	if (priv->sreg_proto_min) {
+		if (nla_put_be32(skb, NFTA_REDIR_REG_PROTO_MIN,
+				 htonl(priv->sreg_proto_min)))
+			goto nla_put_failure;
+		if (nla_put_be32(skb, NFTA_REDIR_REG_PROTO_MAX,
+				 htonl(priv->sreg_proto_max)))
+			goto nla_put_failure;
+	}
+
+	if (priv->flags != 0 &&
+	    nla_put_be32(skb, NFTA_REDIR_FLAGS, htonl(priv->flags)))
+			goto nla_put_failure;
+
+	return 0;
+
+nla_put_failure:
+	return -1;
+}
+EXPORT_SYMBOL_GPL(nft_redir_dump);
+
+int nft_redir_validate(const struct nft_ctx *ctx, const struct nft_expr *expr,
+		       const struct nft_data **data)
+{
+	return nft_chain_validate_dependency(ctx->chain, NFT_CHAIN_T_NAT);
+}
+EXPORT_SYMBOL_GPL(nft_redir_validate);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>");