net/ipv4/netfilter/nf_nat_tftp.c

   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
  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
  37 static void __exit nf_nat_tftp_fini(void)
  38 {
  39         rcu_assign_pointer(nf_nat_tftp_hook, NULL);
  40         synchronize_rcu();
  41 }
  42
  43 static int __init nf_nat_tftp_init(void)
  44 {
  45         BUG_ON(nf_nat_tftp_hook != NULL);
  46         rcu_assign_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);