patch-2.3.99-pre2 linux/net/ipv4/netfilter/ipt_MASQUERADE.c

• Lines: 172
• Date: Fri Mar 17 10:56:20 2000
• Orig file: v2.3.99-pre1/linux/net/ipv4/netfilter/ipt_MASQUERADE.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.99-pre1/linux/net/ipv4/netfilter/ipt_MASQUERADE.c linux/net/ipv4/netfilter/ipt_MASQUERADE.c
@@ -0,0 +1,171 @@
+/* Masquerade.  Simple mapping which alters range to a local IP address
+   (depending on route). */
+#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/checksum.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv4/ip_nat_rule.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+
+EXPORT_NO_SYMBOLS;
+
+#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 *mr = targinfo;
+
+	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,
+		  unsigned int hooknum,
+		  const struct net_device *in,
+		  const struct net_device *out,
+		  const void *targinfo,
+		  void *userinfo)
+{
+	struct ip_conntrack *ct;
+	enum ip_conntrack_info ctinfo;
+	const struct ip_nat_range *r;
+	struct ip_nat_multi_range newrange;
+	u_int32_t newsrc;
+	struct rtable *rt;
+
+	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));
+
+	r = targinfo;
+
+	if (ip_route_output(&rt, (*pskb)->nh.iph->daddr,
+			    0,
+			    RT_TOS((*pskb)->nh.iph->tos)|RTO_CONN,
+			    out->ifindex) != 0) {
+		/* Shouldn't happen */
+		printk("MASQUERADE: No route: Rusty's brain broke!\n");
+		return NF_DROP;
+	}
+
+	newsrc = rt->rt_src;
+	DEBUGP("newsrc = %u.%u.%u.%u\n", IP_PARTS(newsrc));
+	ip_rt_put(rt);
+
+	WRITE_LOCK(&masq_lock);
+	ct->nat.masq_index = out->ifindex;
+	WRITE_UNLOCK(&masq_lock);
+
+	/* Transfer from original range. */
+	newrange = ((struct ip_nat_multi_range)
+		{ 1, { { r->flags | IP_NAT_RANGE_MAP_IPS,
+			 newsrc, newsrc,
+			 r->min, r->max } } });
+
+	/* Hand modified range to generic setup. */
+	return ip_nat_setup_info(ct, &newrange, hooknum);
+}
+
+static inline int
+device_cmp(const 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;
+}
+
+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_selective_cleanup(device_cmp, (void *)(long)dev->ifindex);
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block masq_dev_notifier = {
+	masq_device_event,
+	NULL,
+	0
+};
+
+static struct ipt_target masquerade
+= { { NULL, NULL }, "MASQUERADE", masquerade_target, masquerade_check,
+    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);
+	}
+
+	return ret;
+}
+
+static void __exit fini(void)
+{
+	ipt_unregister_target(&masquerade);
+	unregister_netdevice_notifier(&masq_dev_notifier);
+}
+
+module_init(init);
+module_exit(fini);