[NETFILTER]: Make 'helper' list of ip_nat_core static

This patch makes the 'helper' symbol static to not pollute the namespace
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@redhat.com>

include/linux/netfilter_ipv4/ip_nat_helper.h

@@ -38,11 +38,12 @@ struct ip_nat_helper
 			       struct ip_nat_info *info);
 };
 
-extern struct list_head helpers;
-
 extern int ip_nat_helper_register(struct ip_nat_helper *me);
 extern void ip_nat_helper_unregister(struct ip_nat_helper *me);
 
+extern struct ip_nat_helper *
+ip_nat_find_helper(const struct ip_conntrack_tuple *tuple);
+
 /* These return true or false. */
 extern int ip_nat_mangle_tcp_packet(struct sk_buff **skb,
 				struct ip_conntrack *ct,

net/ipv4/netfilter/ip_nat_core.c

@@ -49,7 +49,6 @@ static unsigned int ip_nat_htable_size;
 static struct list_head *bysource;
 static struct list_head *byipsproto;
 LIST_HEAD(protos);
-LIST_HEAD(helpers);
 
 extern struct ip_nat_protocol unknown_nat_protocol;
 
@@ -498,13 +497,6 @@ get_unique_tuple(struct ip_conntrack_tuple *tuple,
 	return ret;
 }
 
-static inline int
-helper_cmp(const struct ip_nat_helper *helper,
-	   const struct ip_conntrack_tuple *tuple)
-{
-	return ip_ct_tuple_mask_cmp(tuple, &helper->tuple, &helper->mask);
-}
-
 /* Where to manip the reply packets (will be reverse manip). */
 static unsigned int opposite_hook[NF_IP_NUMHOOKS]
 = { [NF_IP_PRE_ROUTING] = NF_IP_POST_ROUTING,
@@ -643,8 +635,7 @@ ip_nat_setup_info(struct ip_conntrack *conntrack,
 
 	/* If there's a helper, assign it; based on new tuple. */
 	if (!conntrack->master)
-		info->helper = LIST_FIND(&helpers, helper_cmp, struct ip_nat_helper *,
-					 &reply);
+		info->helper = ip_nat_find_helper(&reply);
 
 	/* It's done. */
 	info->initialized |= (1 << HOOK2MANIP(hooknum));

net/ipv4/netfilter/ip_nat_helper.c

@@ -47,6 +47,7 @@
 #define DUMP_OFFSET(x)
 #endif
 
+static LIST_HEAD(helpers);
 DECLARE_LOCK(ip_nat_seqofs_lock);
 
 /* Setup TCP sequence correction given this change at this sequence */
@@ -419,6 +420,18 @@ int ip_nat_helper_register(struct ip_nat_helper *me)
 	return ret;
 }
 
+struct ip_nat_helper *
+ip_nat_find_helper(const struct ip_conntrack_tuple *tuple)
+{
+	struct ip_nat_helper *h;
+
+	READ_LOCK(&ip_nat_lock);
+	h = LIST_FIND(&helpers, helper_cmp, struct ip_nat_helper *, tuple);
+	READ_UNLOCK(&ip_nat_lock);
+
+	return h;
+}
+
 static int
 kill_helper(const struct ip_conntrack *i, void *helper)
 {