[PATCH 13/19] netfilter: ip6tables: add MASQUERADE target

kaber
2012-08-09T20:18:35Z

From: Patrick McHardy <kaber@trash.net>

Signed-off-by: Patrick McHardy <kaber@trash.net>
---
include/net/addrconf.h | 2 +-
net/ipv4/netfilter/ipt_MASQUERADE.c | 3 +-
net/ipv6/addrconf.c | 2 +-
net/ipv6/netfilter/Kconfig | 12 +++
net/ipv6/netfilter/Makefile | 1 +
net/ipv6/netfilter/ip6t_MASQUERADE.c | 135 ++++++++++++++++++++++++++++++++++
6 files changed, 152 insertions(+), 3 deletions(-)
create mode 100644 net/ipv6/netfilter/ip6t_MASQUERADE.c

diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 089a09d..9e63e76 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -78,7 +78,7 @@ extern struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net,
int strict);

extern int ipv6_dev_get_saddr(struct net *net,
- struct net_device *dev,
+ const struct net_device *dev,
const struct in6_addr *daddr,
unsigned int srcprefs,
struct in6_addr *saddr);
diff --git a/net/ipv4/netfilter/ipt_MASQUERADE.c b/net/ipv4/netfilter/ipt_MASQUERADE.c
index 1c3aa28..5d5d4d1 100644
--- a/net/ipv4/netfilter/ipt_MASQUERADE.c
+++ b/net/ipv4/netfilter/ipt_MASQUERADE.c
@@ -99,7 +99,8 @@ device_cmp(struct nf_conn *i, void *ifindex)

if (!nat)
return 0;
-
+ if (nf_ct_l3num(i) != NFPROTO_IPV4)
+ return 0;
return nat->masq_index == (int)(long)ifindex;
}

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 7918181..6536404 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1095,7 +1095,7 @@ out:
return ret;
}

-int ipv6_dev_get_saddr(struct net *net, struct net_device *dst_dev,
+int ipv6_dev_get_saddr(struct net *net, const struct net_device *dst_dev,
const struct in6_addr *daddr, unsigned int prefs,
struct in6_addr *saddr)
{
diff --git a/net/ipv6/netfilter/Kconfig b/net/ipv6/netfilter/Kconfig
index b27e0ad..54a5032 100644
--- a/net/ipv6/netfilter/Kconfig
+++ b/net/ipv6/netfilter/Kconfig
@@ -144,6 +144,18 @@ config IP6_NF_TARGET_HL
(e.g. when running oldconfig). It selects
CONFIG_NETFILTER_XT_TARGET_HL.

+config IP6_NF_TARGET_MASQUERADE
+ tristate "MASQUERADE target support"
+ depends on NF_NAT_IPV6
+ help
+ Masquerading is a special case of NAT: all outgoing connections are
+ changed to seem to come from a particular interface's address, and
+ if the interface goes down, those connections are lost. This is
+ only useful for dialup accounts with dynamic IP address (ie. your IP
+ address will be different on next dialup).
+
+ 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 7677937..068bad1 100644
--- a/net/ipv6/netfilter/Makefile
+++ b/net/ipv6/netfilter/Makefile
@@ -34,4 +34,5 @@ obj-$(CONFIG_IP6_NF_MATCH_RPFILTER) += ip6t_rpfilter.o
obj-$(CONFIG_IP6_NF_MATCH_RT) += ip6t_rt.o

# targets
+obj-$(CONFIG_IP6_NF_TARGET_MASQUERADE) += ip6t_MASQUERADE.o
obj-$(CONFIG_IP6_NF_TARGET_REJECT) += ip6t_REJECT.o
diff --git a/net/ipv6/netfilter/ip6t_MASQUERADE.c b/net/ipv6/netfilter/ip6t_MASQUERADE.c
new file mode 100644
index 0000000..60e9053
--- /dev/null
+++ b/net/ipv6/netfilter/ip6t_MASQUERADE.c
@@ -0,0 +1,135 @@
+/*
+ * 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 IPv6 MASQUERADE target. Development of IPv6
+ * NAT funded by Astaro.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/ipv6.h>
+#include <linux/netfilter.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter/x_tables.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/addrconf.h>
+#include <net/ipv6.h>
+
+static unsigned int
+masquerade_tg6(struct sk_buff *skb, const struct xt_action_param *par)
+{
+ const struct nf_nat_range *range = par->targinfo;
+ enum ip_conntrack_info ctinfo;
+ struct in6_addr src;
+ struct nf_conn *ct;
+ struct nf_nat_range newrange;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ NF_CT_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED ||
+ ctinfo == IP_CT_RELATED_REPLY));
+
+ if (ipv6_dev_get_saddr(dev_net(par->out), par->out,
+ &ipv6_hdr(skb)->daddr, 0, &src) < 0)
+ return NF_DROP;
+
+ nfct_nat(ct)->masq_index = par->out->ifindex;
+
+ newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
+ newrange.min_addr.in6 = src;
+ newrange.max_addr.in6 = src;
+ newrange.min_proto = range->min_proto;
+ newrange.max_proto = range->max_proto;
+
+ return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_SRC);
+}
+
+static int masquerade_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 int device_cmp(struct nf_conn *ct, void *ifindex)
+{
+ const struct nf_conn_nat *nat = nfct_nat(ct);
+
+ if (!nat)
+ return 0;
+ if (nf_ct_l3num(ct) != NFPROTO_IPV6)
+ return 0;
+ return nat->masq_index == (int)(long)ifindex;
+}
+
+static int masq_device_event(struct notifier_block *this,
+ unsigned long event, void *ptr)
+{
+ const struct net_device *dev = ptr;
+ struct net *net = dev_net(dev);
+
+ if (event == NETDEV_DOWN)
+ nf_ct_iterate_cleanup(net, device_cmp,
+ (void *)(long)dev->ifindex);
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block masq_dev_notifier = {
+ .notifier_call = masq_device_event,
+};
+
+static int masq_inet_event(struct notifier_block *this,
+ unsigned long event, void *ptr)
+{
+ struct inet6_ifaddr *ifa = ptr;
+
+ return masq_device_event(this, event, ifa->idev->dev);
+}
+
+static struct notifier_block masq_inet_notifier = {
+ .notifier_call = masq_inet_event,
+};
+
+static struct xt_target masquerade_tg6_reg __read_mostly = {
+ .name = "MASQUERADE",
+ .family = NFPROTO_IPV6,
+ .checkentry = masquerade_tg6_checkentry,
+ .target = masquerade_tg6,
+ .targetsize = sizeof(struct nf_nat_range),
+ .table = "nat",
+ .hooks = 1 << NF_INET_POST_ROUTING,
+ .me = THIS_MODULE,
+};
+
+static int __init masquerade_tg6_init(void)
+{
+ int err;
+
+ err = xt_register_target(&masquerade_tg6_reg);
+ if (err == 0) {
+ register_netdevice_notifier(&masq_dev_notifier);
+ register_inet6addr_notifier(&masq_inet_notifier);
+ }
+
+ return err;
+}
+static void __exit masquerade_tg6_exit(void)
+{
+ unregister_inet6addr_notifier(&masq_inet_notifier);
+ unregister_netdevice_notifier(&masq_dev_notifier);
+ xt_unregister_target(&masquerade_tg6_reg);
+}
+
+module_init(masquerade_tg6_init);
+module_exit(masquerade_tg6_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
+MODULE_DESCRIPTION("Xtables: automatic address SNAT");
--
1.7.1