diff --git a/include/net/gre.h b/include/net/gre.h
index 9f03a39..c6ea0c7 100644
--- a/include/net/gre.h
+++ b/include/net/gre.h
@@ -7,6 +7,7 @@
 #define GREPROTO_CISCO		0
 #define GREPROTO_PPTP		1
 #define GREPROTO_MAX		2
+#define GRE_IP_PROTO_MAX	2
 
 struct gre_protocol {
 	int  (*handler)(struct sk_buff *skb);
@@ -22,6 +23,29 @@
 int gre_add_protocol(const struct gre_protocol *proto, u8 version);
 int gre_del_protocol(const struct gre_protocol *proto, u8 version);
 
+struct gre_cisco_protocol {
+	int (*handler)(struct sk_buff *skb, const struct tnl_ptk_info *tpi);
+	int (*err_handler)(struct sk_buff *skb, u32 info,
+			   const struct tnl_ptk_info *tpi);
+	u8 priority;
+};
+
+int gre_cisco_register(struct gre_cisco_protocol *proto);
+int gre_cisco_unregister(struct gre_cisco_protocol *proto);
+
+static inline int ip_gre_calc_hlen(__be16 o_flags)
+{
+	int addend = 4;
+
+	if (o_flags&TUNNEL_CSUM)
+		addend += 4;
+	if (o_flags&TUNNEL_KEY)
+		addend += 4;
+	if (o_flags&TUNNEL_SEQ)
+		addend += 4;
+	return addend;
+}
+
 static inline __be16 gre_flags_to_tnl_flags(__be16 flags)
 {
 	__be16 tflags = 0;