netfilter: conntrack: Add and use nf_ct_set_auto_assign_helper_warned()

The function sets the pernet boolean to avoid the spurious warning from
nf_ct_lookup_helper() when assigning conntrack helpers via nftables.

Fixes: 1a64edf5 ("netfilter: nft_ct: add helper set support")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_conntrack_helper.h

@@ -177,4 +177,5 @@ void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat);
 int nf_nat_helper_try_module_get(const char *name, u16 l3num,
 				 u8 protonum);
 void nf_nat_helper_put(struct nf_conntrack_helper *helper);
+void nf_ct_set_auto_assign_helper_warned(struct net *net);
 #endif /*_NF_CONNTRACK_HELPER_H*/

net/netfilter/nf_conntrack_helper.c

@@ -550,6 +550,12 @@ void nf_nat_helper_unregister(struct nf_conntrack_nat_helper *nat)
 }
 EXPORT_SYMBOL_GPL(nf_nat_helper_unregister);
 
+void nf_ct_set_auto_assign_helper_warned(struct net *net)
+{
+	nf_ct_pernet(net)->auto_assign_helper_warned = true;
+}
+EXPORT_SYMBOL_GPL(nf_ct_set_auto_assign_helper_warned);
+
 void nf_conntrack_helper_pernet_init(struct net *net)
 {
 	struct nf_conntrack_net *cnet = nf_ct_pernet(net);

net/netfilter/nft_ct.c

@@ -1041,6 +1041,9 @@ static int nft_ct_helper_obj_init(const struct nft_ctx *ctx,
 	if (err < 0)
 		goto err_put_helper;
 
+	/* Avoid the bogus warning, helper will be assigned after CT init */
+	nf_ct_set_auto_assign_helper_warned(ctx->net);
+
 	return 0;
 
 err_put_helper: