[NETFILTER]: nf_conntrack/nf_nat: add TFTP helper port

Add IPv4 and IPv6 capable nf_conntrack port of the TFTP conntrack/NAT helper.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 58 insertions, 0 deletions

diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 83e83f553ccb..1c0018b6bea4 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -515,6 +515,11 @@ config IP_NF_NAT_TFTP
 	default IP_NF_NAT if IP_NF_TFTP=y
 	default m if IP_NF_TFTP=m
 
+config NF_NAT_TFTP
+	tristate
+	depends on IP_NF_IPTABLES && NF_CONNTRACK && NF_NAT
+	default NF_NAT && NF_CONNTRACK_TFTP
+
 config IP_NF_NAT_AMANDA
 	tristate
 	depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n
diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
index 167b65e89aca..3ca0af0ed5f0 100644
--- a/net/ipv4/netfilter/Makefile
+++ b/net/ipv4/netfilter/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o
 obj-$(CONFIG_NF_NAT_IRC) += nf_nat_irc.o
 obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o
 obj-$(CONFIG_NF_NAT_SIP) += nf_nat_sip.o
+obj-$(CONFIG_NF_NAT_TFTP) += nf_nat_tftp.o
 
 # NAT protocols (nf_nat)
 obj-$(CONFIG_NF_NAT_PROTO_GRE) += nf_nat_proto_gre.o
diff --git a/net/ipv4/netfilter/nf_nat_tftp.c b/net/ipv4/netfilter/nf_nat_tftp.c
new file mode 100644
index 000000000000..2566b79de224
--- /dev/null
+++ b/net/ipv4/netfilter/nf_nat_tftp.c
@@ -0,0 +1,52 @@
+/* (C) 2001-2002 Magnus Boden <mb@ozaba.mine.nu>
+ *
+ * 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/moduleparam.h>
+#include <linux/udp.h>
+
+#include <net/netfilter/nf_nat_helper.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <linux/netfilter/nf_conntrack_tftp.h>
+
+MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
+MODULE_DESCRIPTION("TFTP NAT helper");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ip_nat_tftp");
+
+static unsigned int help(struct sk_buff **pskb,
+			 enum ip_conntrack_info ctinfo,
+			 struct nf_conntrack_expect *exp)
+{
+	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_conntrack_expect_related(exp) != 0)
+		return NF_DROP;
+	return NF_ACCEPT;
+}
+
+static void __exit nf_nat_tftp_fini(void)
+{
+	rcu_assign_pointer(nf_nat_tftp_hook, NULL);
+	synchronize_rcu();
+}
+
+static int __init nf_nat_tftp_init(void)
+{
+	BUG_ON(rcu_dereference(nf_nat_tftp_hook));
+	rcu_assign_pointer(nf_nat_tftp_hook, help);
+	return 0;
+}
+
+module_init(nf_nat_tftp_init);
+module_exit(nf_nat_tftp_fini);