1 /* (C) 2001-2002 Magnus Boden <mb@ozaba.mine.nu>
2  *
3  * This program is free software; you can redistribute it and/or modify
4  * it under the terms of the GNU General Public License version 2 as
5  * published by the Free Software Foundation.
6  */
7 
8 #include <linux/module.h>
9 #include <linux/udp.h>
10 
11 #include <net/netfilter/nf_nat_helper.h>
12 #include <net/netfilter/nf_nat_rule.h>
13 #include <net/netfilter/nf_conntrack_helper.h>
14 #include <net/netfilter/nf_conntrack_expect.h>
15 #include <linux/netfilter/nf_conntrack_tftp.h>
16 
17 MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
18 MODULE_DESCRIPTION("TFTP NAT helper");
19 MODULE_LICENSE("GPL");
20 MODULE_ALIAS("ip_nat_tftp");
21 
help(struct sk_buff * skb,enum ip_conntrack_info ctinfo,struct nf_conntrack_expect * exp)22 static unsigned int help(struct sk_buff *skb,
23 			 enum ip_conntrack_info ctinfo,
24 			 struct nf_conntrack_expect *exp)
25 {
26 	const struct nf_conn *ct = exp->master;
27 
28 	exp->saved_proto.udp.port
29 		= ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
30 	exp->dir = IP_CT_DIR_REPLY;
31 	exp->expectfn = nf_nat_follow_master;
32 	if (nf_ct_expect_related(exp) != 0)
33 		return NF_DROP;
34 	return NF_ACCEPT;
35 }
36 
nf_nat_tftp_fini(void)37 static void __exit nf_nat_tftp_fini(void)
38 {
39 	RCU_INIT_POINTER(nf_nat_tftp_hook, NULL);
40 	synchronize_rcu();
41 }
42 
nf_nat_tftp_init(void)43 static int __init nf_nat_tftp_init(void)
44 {
45 	BUG_ON(nf_nat_tftp_hook != NULL);
46 	RCU_INIT_POINTER(nf_nat_tftp_hook, help);
47 	return 0;
48 }
49 
50 module_init(nf_nat_tftp_init);
51 module_exit(nf_nat_tftp_fini);
52