netfilter: core: move ip_ct_attach indirection to struct nf_ct_hook

ip_ct_attach predates struct nf_ct_hook, we can place it there and
remove the exported symbol.
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/linux/netfilter.h

@@ -440,7 +440,6 @@ nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
 #include <linux/netfilter/nf_conntrack_zones_common.h>
 
-extern void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *) __rcu;
 void nf_ct_attach(struct sk_buff *, const struct sk_buff *);
 struct nf_conntrack_tuple;
 bool nf_ct_get_tuple_skb(struct nf_conntrack_tuple *dst_tuple,
@@ -463,6 +462,7 @@ struct nf_ct_hook {
 	void (*destroy)(struct nf_conntrack *);
 	bool (*get_tuple_skb)(struct nf_conntrack_tuple *,
 			      const struct sk_buff *);
+	void (*attach)(struct sk_buff *nskb, const struct sk_buff *skb);
 };
 extern struct nf_ct_hook __rcu *nf_ct_hook;
 

net/netfilter/core.c

@@ -673,25 +673,22 @@ struct nf_ct_hook __rcu *nf_ct_hook __read_mostly;
 EXPORT_SYMBOL_GPL(nf_ct_hook);
 
 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
-/* This does not belong here, but locally generated errors need it if connection
-   tracking in use: without this, connection may not be in hash table, and hence
-   manufactured ICMP or RST packets will not be associated with it. */
-void (*ip_ct_attach)(struct sk_buff *, const struct sk_buff *)
-		__rcu __read_mostly;
-EXPORT_SYMBOL(ip_ct_attach);
-
 struct nf_nat_hook __rcu *nf_nat_hook __read_mostly;
 EXPORT_SYMBOL_GPL(nf_nat_hook);
 
+/* This does not belong here, but locally generated errors need it if connection
+ * tracking in use: without this, connection may not be in hash table, and hence
+ * manufactured ICMP or RST packets will not be associated with it.
+ */
 void nf_ct_attach(struct sk_buff *new, const struct sk_buff *skb)
 {
-	void (*attach)(struct sk_buff *, const struct sk_buff *);
+	const struct nf_ct_hook *ct_hook;
 
 	if (skb->_nfct) {
 		rcu_read_lock();
-		attach = rcu_dereference(ip_ct_attach);
-		if (attach)
-			attach(new, skb);
+		ct_hook = rcu_dereference(nf_ct_hook);
+		if (ct_hook)
+			ct_hook->attach(new, skb);
 		rcu_read_unlock();
 	}
 }

net/netfilter/nf_conntrack_core.c

@@ -2455,7 +2455,6 @@ static int kill_all(struct nf_conn *i, void *data)
 void nf_conntrack_cleanup_start(void)
 {
 	conntrack_gc_work.exiting = true;
-	RCU_INIT_POINTER(ip_ct_attach, NULL);
 }
 
 void nf_conntrack_cleanup_end(void)
@@ -2774,12 +2773,11 @@ static struct nf_ct_hook nf_conntrack_hook = {
 	.update		= nf_conntrack_update,
 	.destroy	= destroy_conntrack,
 	.get_tuple_skb  = nf_conntrack_get_tuple_skb,
+	.attach		= nf_conntrack_attach,
 };
 
 void nf_conntrack_init_end(void)
 {
-	/* For use by REJECT target */
-	RCU_INIT_POINTER(ip_ct_attach, nf_conntrack_attach);
 	RCU_INIT_POINTER(nf_ct_hook, &nf_conntrack_hook);
 }