netfilter: connlabels: Export setting connlabel length

Add functions to change connlabel length into nf_conntrack_labels.c so
they may be reused by other modules like OVS and nftables without
needing to jump through xt_match_check() hoops.

Suggested-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Joe Stringer <joestringer@nicira.com>
Acked-by: Florian Westphal <fw@strlen.de>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/xt_connlabel.c b/net/netfilter/xt_connlabel.c
index 9f8719d..bb9cbeb 100644
--- a/net/netfilter/xt_connlabel.c
+++ b/net/netfilter/xt_connlabel.c
@@ -42,10 +42,6 @@
 			    XT_CONNLABEL_OP_SET;
 	struct xt_connlabel_mtinfo *info = par->matchinfo;
 	int ret;
-	size_t words;
-
-	if (info->bit > XT_CONNLABEL_MAXBIT)
-		return -ERANGE;
 
 	if (info->options & ~options) {
 		pr_err("Unknown options in mask %x\n", info->options);
@@ -59,19 +55,15 @@
 		return ret;
 	}
 
-	par->net->ct.labels_used++;
-	words = BITS_TO_LONGS(info->bit+1);
-	if (words > par->net->ct.label_words)
-		par->net->ct.label_words = words;
-
+	ret = nf_connlabels_get(par->net, info->bit + 1);
+	if (ret < 0)
+		nf_ct_l3proto_module_put(par->family);
 	return ret;
 }
 
 static void connlabel_mt_destroy(const struct xt_mtdtor_param *par)
 {
-	par->net->ct.labels_used--;
-	if (par->net->ct.labels_used == 0)
-		par->net->ct.label_words = 0;
+	nf_connlabels_put(par->net);
 	nf_ct_l3proto_module_put(par->family);
 }