[NETFILTER]: Fix invalid module autoloading by splitting iptable_nat

When you've enabled conntrack and NAT as a module (standard case in all
distributions), and you've also enabled the new conntrack netlink
interface, loading ip_conntrack_netlink.ko will auto-load iptable_nat.ko.
This causes a huge performance penalty, since for every packet you iterate
the nat code, even if you don't want it.

This patch splits iptable_nat.ko into the NAT core (ip_nat.ko) and the
iptables frontend (iptable_nat.ko).  Threfore, ip_conntrack_netlink.ko will
only pull ip_nat.ko, but not the frontend.  ip_nat.ko will "only" allocate
some resources, but not affect runtime performance.

This separation is also a nice step in anticipation of new packet filters
(nf-hipac, ipset, pkttables) being able to use the NAT core.

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 7 deletions

diff --git a/include/linux/netfilter_ipv4/ip_nat_core.h b/include/linux/netfilter_ipv4/ip_nat_core.h
index 3b50eb91f007..30db23f06b03 100644
--- a/include/linux/netfilter_ipv4/ip_nat_core.h
+++ b/include/linux/netfilter_ipv4/ip_nat_core.h
@@ -5,16 +5,14 @@
 
 /* This header used to share core functionality between the standalone
    NAT module, and the compatibility layer's use of NAT for masquerading. */
-extern int ip_nat_init(void);
-extern void ip_nat_cleanup(void);
 
-extern unsigned int nat_packet(struct ip_conntrack *ct,
+extern unsigned int ip_nat_packet(struct ip_conntrack *ct,
                                enum ip_conntrack_info conntrackinfo,
                                unsigned int hooknum,
                                struct sk_buff **pskb);
 
-extern int icmp_reply_translation(struct sk_buff **pskb,
-                                  struct ip_conntrack *ct,
-                                  enum ip_nat_manip_type manip,
-                                  enum ip_conntrack_dir dir);
+extern int ip_nat_icmp_reply_translation(struct sk_buff **pskb,
+                                         struct ip_conntrack *ct,
+                                         enum ip_nat_manip_type manip,
+                                         enum ip_conntrack_dir dir);
 #endif /* _IP_NAT_CORE_H */