[PATCH 14/19] netfilter: ip6tables: add REDIRECT target

kaber
2012-08-09T20:18:37Z

From: Patrick McHardy <kaber@trash.net>

Signed-off-by: Patrick McHardy <kaber@trash.net>
---
net/ipv6/netfilter/Kconfig | 11 ++++
net/ipv6/netfilter/Makefile | 1 +
net/ipv6/netfilter/ip6t_REDIRECT.c | 98 ++++++++++++++++++++++++++++++++++++
3 files changed, 110 insertions(+), 0 deletions(-)
create mode 100644 net/ipv6/netfilter/ip6t_REDIRECT.c

diff --git a/net/ipv6/netfilter/Kconfig b/net/ipv6/netfilter/Kconfig
index 54a5032..585590f 100644
--- a/net/ipv6/netfilter/Kconfig
+++ b/net/ipv6/netfilter/Kconfig
@@ -156,6 +156,17 @@ config IP6_NF_TARGET_MASQUERADE

To compile it as a module, choose M here. If unsure, say N.

+config IP6_NF_TARGET_REDIRECT
+ tristate "REDIRECT target support"
+ depends on NF_NAT_IPV6
+ help
+ REDIRECT is a special case of NAT: all incoming connections are
+ mapped onto the incoming interface's address, causing the packets to
+ come to the local machine instead of passing through. This is
+ useful for transparent proxies.
+
+ To compile it as a module, choose M here. If unsure, say N.
+
config IP6_NF_FILTER
tristate "Packet filtering"
default m if NETFILTER_ADVANCED=n
diff --git a/net/ipv6/netfilter/Makefile b/net/ipv6/netfilter/Makefile
index 068bad1..e30a531 100644
--- a/net/ipv6/netfilter/Makefile
+++ b/net/ipv6/netfilter/Makefile
@@ -35,4 +35,5 @@ obj-$(CONFIG_IP6_NF_MATCH_RT) += ip6t_rt.o

# targets
obj-$(CONFIG_IP6_NF_TARGET_MASQUERADE) += ip6t_MASQUERADE.o
+obj-$(CONFIG_IP6_NF_TARGET_REDIRECT) += ip6t_REDIRECT.o
obj-$(CONFIG_IP6_NF_TARGET_REJECT) += ip6t_REJECT.o
diff --git a/net/ipv6/netfilter/ip6t_REDIRECT.c b/net/ipv6/netfilter/ip6t_REDIRECT.c
new file mode 100644
index 0000000..60497a3
--- /dev/null
+++ b/net/ipv6/netfilter/ip6t_REDIRECT.c
@@ -0,0 +1,98 @@
+/*
+ * 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/kernel.h>
+#include <linux/module.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter/x_tables.h>
+#include <net/addrconf.h>
+#include <net/netfilter/nf_nat.h>
+
+static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
+
+static unsigned int
+redirect_tg6(struct sk_buff *skb, const struct xt_action_param *par)
+{
+ const struct nf_nat_range *range = par->targinfo;
+ 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 (par->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);
+}
+
+static int redirect_tg6_checkentry(const struct xt_tgchk_param *par)
+{
+ const struct nf_nat_range *range = par->targinfo;
+
+ if (range->flags & NF_NAT_RANGE_MAP_IPS)
+ return -EINVAL;
+ return 0;
+}
+
+static struct xt_target redirect_tg6_reg __read_mostly = {
+ .name = "REDIRECT",
+ .family = NFPROTO_IPV6,
+ .checkentry = redirect_tg6_checkentry,
+ .target = redirect_tg6,
+ .targetsize = sizeof(struct nf_nat_range),
+ .table = "nat",
+ .hooks = (1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT),
+ .me = THIS_MODULE,
+};
+
+static int __init redirect_tg6_init(void)
+{
+ return xt_register_target(&redirect_tg6_reg);
+}
+
+static void __exit redirect_tg6_exit(void)
+{
+ xt_unregister_target(&redirect_tg6_reg);
+}
+
+module_init(redirect_tg6_init);
+module_exit(redirect_tg6_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
+MODULE_DESCRIPTION("Xtables: Connection redirection to localhost");
--
1.7.1