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Diffstat (limited to 'net/ipv4/netfilter/ipt_MASQUERADE.c')
-rw-r--r--net/ipv4/netfilter/ipt_MASQUERADE.c207
1 files changed, 207 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/ipt_MASQUERADE.c b/net/ipv4/netfilter/ipt_MASQUERADE.c
new file mode 100644
index 00000000000..57e9f6cf1c3
--- /dev/null
+++ b/net/ipv4/netfilter/ipt_MASQUERADE.c
@@ -0,0 +1,207 @@
+/* Masquerade. Simple mapping which alters range to a local IP address
+ (depending on route). */
+
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
+ *
+ * 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/config.h>
+#include <linux/types.h>
+#include <linux/ip.h>
+#include <linux/timer.h>
+#include <linux/module.h>
+#include <linux/netfilter.h>
+#include <net/protocol.h>
+#include <net/ip.h>
+#include <net/checksum.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv4/ip_nat_rule.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
+MODULE_DESCRIPTION("iptables MASQUERADE target module");
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+/* Lock protects masq region inside conntrack */
+static DECLARE_RWLOCK(masq_lock);
+
+/* FIXME: Multiple targets. --RR */
+static int
+masquerade_check(const char *tablename,
+ const struct ipt_entry *e,
+ void *targinfo,
+ unsigned int targinfosize,
+ unsigned int hook_mask)
+{
+ const struct ip_nat_multi_range_compat *mr = targinfo;
+
+ if (strcmp(tablename, "nat") != 0) {
+ DEBUGP("masquerade_check: bad table `%s'.\n", tablename);
+ return 0;
+ }
+ if (targinfosize != IPT_ALIGN(sizeof(*mr))) {
+ DEBUGP("masquerade_check: size %u != %u.\n",
+ targinfosize, sizeof(*mr));
+ return 0;
+ }
+ if (hook_mask & ~(1 << NF_IP_POST_ROUTING)) {
+ DEBUGP("masquerade_check: bad hooks %x.\n", hook_mask);
+ return 0;
+ }
+ if (mr->range[0].flags & IP_NAT_RANGE_MAP_IPS) {
+ DEBUGP("masquerade_check: bad MAP_IPS.\n");
+ return 0;
+ }
+ if (mr->rangesize != 1) {
+ DEBUGP("masquerade_check: bad rangesize %u.\n", mr->rangesize);
+ return 0;
+ }
+ return 1;
+}
+
+static unsigned int
+masquerade_target(struct sk_buff **pskb,
+ const struct net_device *in,
+ const struct net_device *out,
+ unsigned int hooknum,
+ const void *targinfo,
+ void *userinfo)
+{
+ struct ip_conntrack *ct;
+ enum ip_conntrack_info ctinfo;
+ const struct ip_nat_multi_range_compat *mr;
+ struct ip_nat_range newrange;
+ struct rtable *rt;
+ u_int32_t newsrc;
+
+ IP_NF_ASSERT(hooknum == NF_IP_POST_ROUTING);
+
+ /* FIXME: For the moment, don't do local packets, breaks
+ testsuite for 2.3.49 --RR */
+ if ((*pskb)->sk)
+ return NF_ACCEPT;
+
+ ct = ip_conntrack_get(*pskb, &ctinfo);
+ IP_NF_ASSERT(ct && (ctinfo == IP_CT_NEW || ctinfo == IP_CT_RELATED
+ || ctinfo == IP_CT_RELATED + IP_CT_IS_REPLY));
+
+ mr = targinfo;
+ rt = (struct rtable *)(*pskb)->dst;
+ newsrc = inet_select_addr(out, rt->rt_gateway, RT_SCOPE_UNIVERSE);
+ if (!newsrc) {
+ printk("MASQUERADE: %s ate my IP address\n", out->name);
+ return NF_DROP;
+ }
+
+ WRITE_LOCK(&masq_lock);
+ ct->nat.masq_index = out->ifindex;
+ WRITE_UNLOCK(&masq_lock);
+
+ /* Transfer from original range. */
+ newrange = ((struct ip_nat_range)
+ { mr->range[0].flags | IP_NAT_RANGE_MAP_IPS,
+ newsrc, newsrc,
+ mr->range[0].min, mr->range[0].max });
+
+ /* Hand modified range to generic setup. */
+ return ip_nat_setup_info(ct, &newrange, hooknum);
+}
+
+static inline int
+device_cmp(struct ip_conntrack *i, void *ifindex)
+{
+ int ret;
+
+ READ_LOCK(&masq_lock);
+ ret = (i->nat.masq_index == (int)(long)ifindex);
+ READ_UNLOCK(&masq_lock);
+
+ return ret;
+}
+
+static int masq_device_event(struct notifier_block *this,
+ unsigned long event,
+ void *ptr)
+{
+ struct net_device *dev = ptr;
+
+ if (event == NETDEV_DOWN) {
+ /* Device was downed. Search entire table for
+ conntracks which were associated with that device,
+ and forget them. */
+ IP_NF_ASSERT(dev->ifindex != 0);
+
+ ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
+ }
+
+ return NOTIFY_DONE;
+}
+
+static int masq_inet_event(struct notifier_block *this,
+ unsigned long event,
+ void *ptr)
+{
+ struct net_device *dev = ((struct in_ifaddr *)ptr)->ifa_dev->dev;
+
+ if (event == NETDEV_DOWN) {
+ /* IP address was deleted. Search entire table for
+ conntracks which were associated with that device,
+ and forget them. */
+ IP_NF_ASSERT(dev->ifindex != 0);
+
+ ip_ct_iterate_cleanup(device_cmp, (void *)(long)dev->ifindex);
+ }
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block masq_dev_notifier = {
+ .notifier_call = masq_device_event,
+};
+
+static struct notifier_block masq_inet_notifier = {
+ .notifier_call = masq_inet_event,
+};
+
+static struct ipt_target masquerade = {
+ .name = "MASQUERADE",
+ .target = masquerade_target,
+ .checkentry = masquerade_check,
+ .me = THIS_MODULE,
+};
+
+static int __init init(void)
+{
+ int ret;
+
+ ret = ipt_register_target(&masquerade);
+
+ if (ret == 0) {
+ /* Register for device down reports */
+ register_netdevice_notifier(&masq_dev_notifier);
+ /* Register IP address change reports */
+ register_inetaddr_notifier(&masq_inet_notifier);
+ }
+
+ return ret;
+}
+
+static void __exit fini(void)
+{
+ ipt_unregister_target(&masquerade);
+ unregister_netdevice_notifier(&masq_dev_notifier);
+ unregister_inetaddr_notifier(&masq_inet_notifier);
+}
+
+module_init(init);
+module_exit(fini);