From: Ben Hutchings <ben@decadent.org.uk>
Date: Sun, 01 Jun 2014 23:29:17 +0100
Subject: netfilter: Avoid ABI change in 3.14.5

The types of fields in struct nf_ct_ext were changed by commit
223b02d923ec ("netfilter: nf_conntrack: reserve two bytes for
nf_ct_ext->len") as u8 is not large enough to store the offsets
that may be needed now.

This ABI change should only affect the conntrack extension modules,
which must be in-tree as they have centrally assigned numbers.
However the structure definition is visible to all modules using
conntrack at all.  Hide the ABI change from genksyms and use a macro
to rename the extension registration function so that it is still not
possible to mismatch conntrack core and extension modules.

--- a/include/net/netfilter/nf_conntrack_extend.h
+++ b/include/net/netfilter/nf_conntrack_extend.h
@@ -47,8 +47,19 @@ enum nf_ct_ext_id {
 /* Extensions: optional stuff which isn't permanently in struct. */
 struct nf_ct_ext {
 	struct rcu_head rcu;
+#ifdef __GENKSYMS__
+	/* Layout expected by modules calling nf_ct_extend_register()
+	 * (which has been removed)
+	 */
+	u8 offset[NF_CT_EXT_NUM];
+	u8 len;
+#else
+	/* Layout expected by modules calling nf_ct_extend_register_16()
+	 * (all newly built modules, thanks to macro definition below)
+	 */
 	u16 offset[NF_CT_EXT_NUM];
 	u16 len;
+#endif
 	char data[0];
 };
 
@@ -118,6 +129,7 @@ struct nf_ct_ext_type {
 	u8 alloc_size;
 };
 
+#define nf_ct_extend_register nf_ct_extend_register_16
 int nf_ct_extend_register(struct nf_ct_ext_type *type);
 void nf_ct_extend_unregister(struct nf_ct_ext_type *type);
 #endif /* _NF_CONNTRACK_EXTEND_H */