1 files changed, 138 insertions, 0 deletions
diff --git a/net/netfilter/nf_nat_redirect.c b/net/netfilter/nf_nat_redirect.c
new file mode 100644
index 000000000..5b37487d9
--- /dev/null
+++ b/net/netfilter/nf_nat_redirect.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
+ * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
+ *
+ * Based on Rusty Russell's IPv4 REDIRECT target. Development of IPv6
+ * NAT funded by Astaro.
+ */
+
+#include <linux/if.h>
+#include <linux/inetdevice.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/netfilter.h>
+#include <linux/types.h>
+#include <linux/netfilter_ipv4.h>
+#include <linux/netfilter_ipv6.h>
+#include <linux/netfilter/x_tables.h>
+#include <net/addrconf.h>
+#include <net/checksum.h>
+#include <net/protocol.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_redirect.h>
+
+static unsigned int
+nf_nat_redirect(struct sk_buff *skb, const struct nf_nat_range2 *range,
+		const union nf_inet_addr *newdst)
+{
+	struct nf_nat_range2 newrange;
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct;
+
+	ct = nf_ct_get(skb, &ctinfo);
+
+	memset(&newrange, 0, sizeof(newrange));
+
+	newrange.flags		= range->flags | NF_NAT_RANGE_MAP_IPS;
+	newrange.min_addr	= *newdst;
+	newrange.max_addr	= *newdst;
+	newrange.min_proto	= range->min_proto;
+	newrange.max_proto	= range->max_proto;
+
+	return nf_nat_setup_info(ct, &newrange, NF_NAT_MANIP_DST);
+}
+
+unsigned int
+nf_nat_redirect_ipv4(struct sk_buff *skb, const struct nf_nat_range2 *range,
+		     unsigned int hooknum)
+{
+	union nf_inet_addr newdst = {};
+
+	WARN_ON(hooknum != NF_INET_PRE_ROUTING &&
+		hooknum != NF_INET_LOCAL_OUT);
+
+	/* Local packets: make them go to loopback */
+	if (hooknum == NF_INET_LOCAL_OUT) {
+		newdst.ip = htonl(INADDR_LOOPBACK);
+	} else {
+		const struct in_device *indev;
+
+		indev = __in_dev_get_rcu(skb->dev);
+		if (indev) {
+			const struct in_ifaddr *ifa;
+
+			ifa = rcu_dereference(indev->ifa_list);
+			if (ifa)
+				newdst.ip = ifa->ifa_local;
+		}
+
+		if (!newdst.ip)
+			return NF_DROP;
+	}
+
+	return nf_nat_redirect(skb, range, &newdst);
+}
+EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv4);
+
+static const struct in6_addr loopback_addr = IN6ADDR_LOOPBACK_INIT;
+
+static bool nf_nat_redirect_ipv6_usable(const struct inet6_ifaddr *ifa, unsigned int scope)
+{
+	unsigned int ifa_addr_type = ipv6_addr_type(&ifa->addr);
+
+	if (ifa_addr_type & IPV6_ADDR_MAPPED)
+		return false;
+
+	if ((ifa->flags & IFA_F_TENTATIVE) && (!(ifa->flags & IFA_F_OPTIMISTIC)))
+		return false;
+
+	if (scope) {
+		unsigned int ifa_scope = ifa_addr_type & IPV6_ADDR_SCOPE_MASK;
+
+		if (!(scope & ifa_scope))
+			return false;
+	}
+
+	return true;
+}
+
+unsigned int
+nf_nat_redirect_ipv6(struct sk_buff *skb, const struct nf_nat_range2 *range,
+		     unsigned int hooknum)
+{
+	union nf_inet_addr newdst = {};
+
+	if (hooknum == NF_INET_LOCAL_OUT) {
+		newdst.in6 = loopback_addr;
+	} else {
+		unsigned int scope = ipv6_addr_scope(&ipv6_hdr(skb)->daddr);
+		struct inet6_dev *idev;
+		bool addr = false;
+
+		idev = __in6_dev_get(skb->dev);
+		if (idev != NULL) {
+			const struct inet6_ifaddr *ifa;
+
+			read_lock_bh(&idev->lock);
+			list_for_each_entry(ifa, &idev->addr_list, if_list) {
+				if (!nf_nat_redirect_ipv6_usable(ifa, scope))
+					continue;
+
+				newdst.in6 = ifa->addr;
+				addr = true;
+				break;
+			}
+			read_unlock_bh(&idev->lock);
+		}
+
+		if (!addr)
+			return NF_DROP;
+	}
+
+	return nf_nat_redirect(skb, range, &newdst);
+}
+EXPORT_SYMBOL_GPL(nf_nat_redirect_ipv6);