1 files changed, 71 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_netbios_ns.c b/net/netfilter/nf_conntrack_netbios_ns.c
new file mode 100644
index 000000000..55415f011
--- /dev/null
+++ b/net/netfilter/nf_conntrack_netbios_ns.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *      NetBIOS name service broadcast connection tracking helper
+ *
+ *      (c) 2005 Patrick McHardy <kaber@trash.net>
+ */
+/*
+ *      This helper tracks locally originating NetBIOS name service
+ *      requests by issuing permanent expectations (valid until
+ *      timing out) matching all reply connections from the
+ *      destination network. The only NetBIOS specific thing is
+ *      actually the port number.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/in.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+
+#define HELPER_NAME	"netbios-ns"
+#define NMBD_PORT	137
+
+MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
+MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ip_conntrack_netbios_ns");
+MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
+
+static unsigned int timeout __read_mostly = 3;
+module_param(timeout, uint, 0400);
+MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds");
+
+static struct nf_conntrack_expect_policy exp_policy = {
+	.max_expected	= 1,
+};
+
+static int netbios_ns_help(struct sk_buff *skb, unsigned int protoff,
+			   struct nf_conn *ct,
+			   enum ip_conntrack_info ctinfo)
+{
+	return nf_conntrack_broadcast_help(skb, ct, ctinfo, timeout);
+}
+
+static struct nf_conntrack_helper helper __read_mostly = {
+	.name			= HELPER_NAME,
+	.tuple.src.l3num	= NFPROTO_IPV4,
+	.tuple.src.u.udp.port	= cpu_to_be16(NMBD_PORT),
+	.tuple.dst.protonum	= IPPROTO_UDP,
+	.me			= THIS_MODULE,
+	.help			= netbios_ns_help,
+	.expect_policy		= &exp_policy,
+};
+
+static int __init nf_conntrack_netbios_ns_init(void)
+{
+	NF_CT_HELPER_BUILD_BUG_ON(0);
+
+	exp_policy.timeout = timeout;
+	return nf_conntrack_helper_register(&helper);
+}
+
+static void __exit nf_conntrack_netbios_ns_fini(void)
+{
+	nf_conntrack_helper_unregister(&helper);
+}
+
+module_init(nf_conntrack_netbios_ns_init);
+module_exit(nf_conntrack_netbios_ns_fini);