netfilter: refactor NAT redirect IPv6 code to use it from nf_tables

This patch refactors the IPv6 code so it can be usable both from xt and
nf_tables.

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

3 files changed, 82 insertions, 0 deletions

diff --git a/net/ipv6/netfilter/Kconfig b/net/ipv6/netfilter/Kconfig
index 6af874fc187f..462eebbf4377 100644
--- a/net/ipv6/netfilter/Kconfig
+++ b/net/ipv6/netfilter/Kconfig
@@ -82,6 +82,12 @@ config NF_NAT_MASQUERADE_IPV6
           This is the kernel functionality to provide NAT in the masquerade
           flavour (automatic source address selection) for IPv6.
 
+config NF_NAT_REDIRECT_IPV6
+        tristate "IPv6 redirect support"
+        help
+          This is the kernel functionality to provide NAT in the redirect
+          flavour (redirect packet to local machine) for IPv6.
+
 config NFT_MASQ_IPV6
         tristate "IPv6 masquerade support for nf_tables"
         depends on NF_TABLES_IPV6
diff --git a/net/ipv6/netfilter/Makefile b/net/ipv6/netfilter/Makefile
index fbb25f01143c..6c2baab10f21 100644
--- a/net/ipv6/netfilter/Makefile
+++ b/net/ipv6/netfilter/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_NF_CONNTRACK_IPV6) += nf_conntrack_ipv6.o
 nf_nat_ipv6-y           := nf_nat_l3proto_ipv6.o nf_nat_proto_icmpv6.o
 obj-$(CONFIG_NF_NAT_IPV6) += nf_nat_ipv6.o
 obj-$(CONFIG_NF_NAT_MASQUERADE_IPV6) += nf_nat_masquerade_ipv6.o
+obj-$(CONFIG_NF_NAT_REDIRECT_IPV6) += nf_nat_redirect_ipv6.o
 
 # defrag
 nf_defrag_ipv6-y := nf_defrag_ipv6_hooks.o nf_conntrack_reasm.o
diff --git a/net/ipv6/netfilter/nf_nat_redirect_ipv6.c b/net/ipv6/netfilter/nf_nat_redirect_ipv6.c
new file mode 100644
index 000000000000..ea1308aeb048
--- /dev/null
+++ b/net/ipv6/netfilter/nf_nat_redirect_ipv6.c
@@ -0,0 +1,75 @@
+/*
+ * (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
+ * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
+ *
+ * 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.
+ *
+ * Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
+ * NAT funded by Astaro.
+ */
+
+#include <linux/if.h>
+#include <linux/inetdevice.h>
+#include <linux/ip.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/netfilter.h>
+#include <linux/types.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter/x_tables.h>
+#include <net/addrconf.h>
+#include <net/checksum.h>
+#include <net/protocol.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/ipv6/nf_nat_redirect.h>
+
+static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
+
+unsigned int
+nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range *range,
+                     unsigned int hooknum)
+{
+        struct nf_nat_range newrange;
+        struct in6_addr newdst;
+        enum ip_conntrack_info ctinfo;
+        struct nf_conn *ct;
+
+        ct = nf_ct_get(skb, &ctinfo);
+        if (hooknum == NF_INET_LOCAL_OUT) {
+                newdst = loopback_addr;
+        } else {
+                struct inet6_dev *idev;
+                struct inet6_ifaddr *ifa;
+                bool addr = false;
+
+                rcu_read_lock();
+                idev = __in6_dev_get(skb->dev);
+                if (idev != NULL) {
+                        list_for_each_entry(ifa, &idev->addr_list, if_list) {
+                                newdst = ifa->addr;
+                                addr = true;
+                                break;
+                        }
+                }
+                rcu_read_unlock();
+
+                if (!addr)
+                        return NF_DROP;
+        }
+
+        newrange.flags          = range->flags | NF_NAT_RANGE_MAP_IPS;
+        newrange.min_addr.in6   = newdst;
+        newrange.max_addr.in6   = newdst;
+        newrange.min_proto      = range->min_proto;
+        newrange.max_proto      = range->max_proto;
+
+        return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
+}
+EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv6);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");