netfilter: ip6tables: add MASQUERADE target

Signed-off-by: Patrick McHardy <kaber@trash.net>

7 files changed, 155 insertions, 4 deletions

diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 089a09d001d1..9e63e76b20e7 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/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h
index 1752f1339054..bd8eea720f2e 100644
--- a/include/net/netfilter/nf_nat.h
+++ b/include/net/netfilter/nf_nat.h
@@ -43,7 +43,9 @@ struct nf_conn_nat {
         struct nf_conn *ct;
         union nf_conntrack_nat_help help;
 #if defined(CONFIG_IP_NF_TARGET_MASQUERADE) || \
-    defined(CONFIG_IP_NF_TARGET_MASQUERADE_MODULE)
+    defined(CONFIG_IP_NF_TARGET_MASQUERADE_MODULE) || \
+    defined(CONFIG_IP6_NF_TARGET_MASQUERADE) || \
+    defined(CONFIG_IP6_NF_TARGET_MASQUERADE_MODULE)
         int masq_index;
 #endif
 };
diff --git a/net/ipv4/netfilter/ipt_MASQUERADE.c b/net/ipv4/netfilter/ipt_MASQUERADE.c
index 1c3aa28b51ae..5d5d4d1be9c2 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 e581009cb09e..19d4bffda9d7 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1093,7 +1093,7 @@ 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 b27e0ad4b738..54a5032ea3df 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 76779376da4c..068bad199587 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 000000000000..60e9053bab05
--- /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");