1 files changed, 80 insertions, 0 deletions
diff --git a/net/netfilter/nf_nat_amanda.c b/net/netfilter/nf_nat_amanda.c
new file mode 100644
index 000000000..98deef6cd
--- /dev/null
+++ b/net/netfilter/nf_nat_amanda.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Amanda extension for TCP NAT alteration.
+ * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca>
+ * based on a copy of HW's ip_nat_irc.c as well as other modules
+ * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/skbuff.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_amanda.h>
+
+#define NAT_HELPER_NAME "amanda"
+
+MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>");
+MODULE_DESCRIPTION("Amanda NAT helper");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME);
+
+static struct nf_conntrack_nat_helper nat_helper_amanda =
+	NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME);
+
+static unsigned int help(struct sk_buff *skb,
+			 enum ip_conntrack_info ctinfo,
+			 unsigned int protoff,
+			 unsigned int matchoff,
+			 unsigned int matchlen,
+			 struct nf_conntrack_expect *exp)
+{
+	char buffer[sizeof("65535")];
+	u_int16_t port;
+
+	/* Connection comes from client. */
+	exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+	exp->dir = IP_CT_DIR_ORIGINAL;
+
+	/* When you see the packet, we need to NAT it the same as the
+	 * this one (ie. same IP: it will be TCP and master is UDP). */
+	exp->expectfn = nf_nat_follow_master;
+
+	/* Try to get same port: if not, try to change it. */
+	port = nf_nat_exp_find_port(exp, ntohs(exp->saved_proto.tcp.port));
+	if (port == 0) {
+		nf_ct_helper_log(skb, exp->master, "all ports in use");
+		return NF_DROP;
+	}
+
+	sprintf(buffer, "%u", port);
+	if (!nf_nat_mangle_udp_packet(skb, exp->master, ctinfo,
+				      protoff, matchoff, matchlen,
+				      buffer, strlen(buffer))) {
+		nf_ct_helper_log(skb, exp->master, "cannot mangle packet");
+		nf_ct_unexpect_related(exp);
+		return NF_DROP;
+	}
+	return NF_ACCEPT;
+}
+
+static void __exit nf_nat_amanda_fini(void)
+{
+	nf_nat_helper_unregister(&nat_helper_amanda);
+	RCU_INIT_POINTER(nf_nat_amanda_hook, NULL);
+	synchronize_rcu();
+}
+
+static int __init nf_nat_amanda_init(void)
+{
+	BUG_ON(nf_nat_amanda_hook != NULL);
+	nf_nat_helper_register(&nat_helper_amanda);
+	RCU_INIT_POINTER(nf_nat_amanda_hook, help);
+	return 0;
+}
+
+module_init(nf_nat_amanda_init);
+module_exit(nf_nat_amanda_fini);