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>

3 files changed, 87 insertions, 0 deletions

diff --git a/net/ipv6/netfilter/Kconfig b/net/ipv6/netfilter/Kconfig
index 462eebbf4377..0dbe5c7953e5 100644
--- a/net/ipv6/netfilter/Kconfig
+++ b/net/ipv6/netfilter/Kconfig
@@ -97,6 +97,15 @@ config NFT_MASQ_IPV6
           This is the expression that provides IPv4 masquerading support for
           nf_tables.
 
+config NFT_REDIR_IPV6
+        tristate "IPv6 redirect support for nf_tables"
+        depends on NF_TABLES_IPV6
+        depends on NFT_REDIR
+        select NF_NAT_REDIRECT_IPV6
+        help
+          This is the expression that provides IPv4 redirect support for
+          nf_tables.
+
 endif # NF_NAT_IPV6
 
 config IP6_NF_IPTABLES
diff --git a/net/ipv6/netfilter/Makefile b/net/ipv6/netfilter/Makefile
index 6c2baab10f21..d2ac9f5f212c 100644
--- a/net/ipv6/netfilter/Makefile
+++ b/net/ipv6/netfilter/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV6) += nft_chain_route_ipv6.o
 obj-$(CONFIG_NFT_CHAIN_NAT_IPV6) += nft_chain_nat_ipv6.o
 obj-$(CONFIG_NFT_REJECT_IPV6) += nft_reject_ipv6.o
 obj-$(CONFIG_NFT_MASQ_IPV6) += nft_masq_ipv6.o
+obj-$(CONFIG_NFT_REDIR_IPV6) += nft_redir_ipv6.o
 
 # matches
 obj-$(CONFIG_IP6_NF_MATCH_AH) += ip6t_ah.o
diff --git a/net/ipv6/netfilter/nft_redir_ipv6.c b/net/ipv6/netfilter/nft_redir_ipv6.c
new file mode 100644
index 000000000000..83420eeaad1c
--- /dev/null
+++ b/net/ipv6/netfilter/nft_redir_ipv6.c
@@ -0,0 +1,77 @@
+/*
+ * 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_redir.h>
+#include <net/netfilter/ipv6/nf_nat_redirect.h>
+
+static void nft_redir_ipv6_eval(const struct nft_expr *expr,
+                                struct nft_data data[NFT_REG_MAX + 1],
+                                const struct nft_pktinfo *pkt)
+{
+        struct nft_redir *priv = nft_expr_priv(expr);
+        struct nf_nat_range range;
+        unsigned int verdict;
+
+        memset(&range, 0, sizeof(range));
+        if (priv->sreg_proto_min) {
+                range.min_proto.all = (__force __be16)
+                                        data[priv->sreg_proto_min].data[0];
+                range.max_proto.all = (__force __be16)
+                                        data[priv->sreg_proto_max].data[0];
+                range.flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
+        }
+
+        range.flags |= priv->flags;
+
+        verdict = nf_nat_redirect_ipv6(pkt->skb, &range, pkt->ops->hooknum);
+        data[NFT_REG_VERDICT].verdict = verdict;
+}
+
+static struct nft_expr_type nft_redir_ipv6_type;
+static const struct nft_expr_ops nft_redir_ipv6_ops = {
+        .type           = &nft_redir_ipv6_type,
+        .size           = NFT_EXPR_SIZE(sizeof(struct nft_redir)),
+        .eval           = nft_redir_ipv6_eval,
+        .init           = nft_redir_init,
+        .dump           = nft_redir_dump,
+        .validate       = nft_redir_validate,
+};
+
+static struct nft_expr_type nft_redir_ipv6_type __read_mostly = {
+        .family         = NFPROTO_IPV6,
+        .name           = "redir",
+        .ops            = &nft_redir_ipv6_ops,
+        .policy         = nft_redir_policy,
+        .maxattr        = NFTA_REDIR_MAX,
+        .owner          = THIS_MODULE,
+};
+
+static int __init nft_redir_ipv6_module_init(void)
+{
+        return nft_register_expr(&nft_redir_ipv6_type);
+}
+
+static void __exit nft_redir_ipv6_module_exit(void)
+{
+        nft_unregister_expr(&nft_redir_ipv6_type);
+}
+
+module_init(nft_redir_ipv6_module_init);
+module_exit(nft_redir_ipv6_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>");
+MODULE_ALIAS_NFT_AF_EXPR(AF_INET6, "redir");