1 files changed, 56 insertions, 0 deletions
diff --git a/net/netfilter/nf_nat_tftp.c b/net/netfilter/nf_nat_tftp.c
new file mode 100644
index 000000000..1a591132d
--- /dev/null
+++ b/net/netfilter/nf_nat_tftp.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* (C) 2001-2002 Magnus Boden <mb@ozaba.mine.nu>
+ */
+
+#include <linux/module.h>
+#include <linux/udp.h>
+
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <net/netfilter/nf_nat_helper.h>
+#include <linux/netfilter/nf_conntrack_tftp.h>
+
+#define NAT_HELPER_NAME "tftp"
+
+MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
+MODULE_DESCRIPTION("TFTP NAT helper");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME);
+
+static struct nf_conntrack_nat_helper nat_helper_tftp =
+	NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME);
+
+static unsigned int help(struct sk_buff *skb,
+			 enum ip_conntrack_info ctinfo,
+			 struct nf_conntrack_expect *exp)
+{
+	const struct nf_conn *ct = exp->master;
+
+	exp->saved_proto.udp.port
+		= ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
+	exp->dir = IP_CT_DIR_REPLY;
+	exp->expectfn = nf_nat_follow_master;
+	if (nf_ct_expect_related(exp, 0) != 0) {
+		nf_ct_helper_log(skb, exp->master, "cannot add expectation");
+		return NF_DROP;
+	}
+	return NF_ACCEPT;
+}
+
+static void __exit nf_nat_tftp_fini(void)
+{
+	nf_nat_helper_unregister(&nat_helper_tftp);
+	RCU_INIT_POINTER(nf_nat_tftp_hook, NULL);
+	synchronize_rcu();
+}
+
+static int __init nf_nat_tftp_init(void)
+{
+	BUG_ON(nf_nat_tftp_hook != NULL);
+	nf_nat_helper_register(&nat_helper_tftp);
+	RCU_INIT_POINTER(nf_nat_tftp_hook, help);
+	return 0;
+}
+
+module_init(nf_nat_tftp_init);
+module_exit(nf_nat_tftp_fini);