1 files changed, 97 insertions, 0 deletions
diff --git a/net/netfilter/xt_helper.c b/net/netfilter/xt_helper.c
new file mode 100644
index 0000000..64fc7f2
--- /dev/null
+++ b/net/netfilter/xt_helper.c
@@ -0,0 +1,97 @@
+/* iptables module to match on related connections */
+/*
+ * (C) 2001 Martin Josefsson <gandalf@wlug.westbo.se>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter.h>
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter/xt_helper.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Martin Josefsson <gandalf@netfilter.org>");
+MODULE_DESCRIPTION("Xtables: Related connection matching");
+MODULE_ALIAS("ipt_helper");
+MODULE_ALIAS("ip6t_helper");
+
+
+static bool
+helper_mt(const struct sk_buff *skb, const struct xt_match_param *par)
+{
+	const struct xt_helper_info *info = par->matchinfo;
+	const struct nf_conn *ct;
+	const struct nf_conn_help *master_help;
+	const struct nf_conntrack_helper *helper;
+	enum ip_conntrack_info ctinfo;
+	bool ret = info->invert;
+
+	ct = nf_ct_get(skb, &ctinfo);
+	if (!ct || !ct->master)
+		return ret;
+
+	master_help = nfct_help(ct->master);
+	if (!master_help)
+		return ret;
+
+	/* rcu_read_lock()ed by nf_hook_slow */
+	helper = rcu_dereference(master_help->helper);
+	if (!helper)
+		return ret;
+
+	if (info->name[0] == '\0')
+		ret = !ret;
+	else
+		ret ^= !strncmp(helper->name, info->name,
+				strlen(helper->name));
+	return ret;
+}
+
+static bool helper_mt_check(const struct xt_mtchk_param *par)
+{
+	struct xt_helper_info *info = par->matchinfo;
+
+	if (nf_ct_l3proto_try_module_get(par->family) < 0) {
+		printk(KERN_WARNING "can't load conntrack support for "
+				    "proto=%u\n", par->family);
+		return false;
+	}
+	info->name[29] = '\0';
+	return true;
+}
+
+static void helper_mt_destroy(const struct xt_mtdtor_param *par)
+{
+	nf_ct_l3proto_module_put(par->family);
+}
+
+static struct xt_match helper_mt_reg __read_mostly = {
+	.name       = "helper",
+	.revision   = 0,
+	.family     = NFPROTO_UNSPEC,
+	.checkentry = helper_mt_check,
+	.match      = helper_mt,
+	.destroy    = helper_mt_destroy,
+	.matchsize  = sizeof(struct xt_helper_info),
+	.me         = THIS_MODULE,
+};
+
+static int __init helper_mt_init(void)
+{
+	return xt_register_match(&helper_mt_reg);
+}
+
+static void __exit helper_mt_exit(void)
+{
+	xt_unregister_match(&helper_mt_reg);
+}
+
+module_init(helper_mt_init);
+module_exit(helper_mt_exit);