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/moduleparam.h>
  10 #include <linux/udp.h>
  11
  12 #include <net/netfilter/nf_nat_helper.h>
  13 #include <net/netfilter/nf_nat_rule.h>
  14 #include <net/netfilter/nf_conntrack_helper.h>
  15 #include <net/netfilter/nf_conntrack_expect.h>
  16 #include <linux/netfilter/nf_conntrack_tftp.h>
  17
  18 MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
  19 MODULE_DESCRIPTION("TFTP NAT helper");
  20 MODULE_LICENSE("GPL");
  21 MODULE_ALIAS("ip_nat_tftp");
  22
  23 static unsigned int help(struct sk_buff *skb,
  24                          enum ip_conntrack_info ctinfo,
  25                          struct nf_conntrack_expect *exp)
  26 {
  27         const struct nf_conn *ct = exp->master;
  28
  29         exp->saved_proto.udp.port
  30                 = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
  31         exp->dir = IP_CT_DIR_REPLY;
  32         exp->expectfn = nf_nat_follow_master;
  33         if (nf_ct_expect_related(exp) != 0)
  34                 return NF_DROP;
  35         return NF_ACCEPT;
  36 }
  37
  38 static void __exit nf_nat_tftp_fini(void)
  39 {
  40         rcu_assign_pointer(nf_nat_tftp_hook, NULL);
  41         synchronize_rcu();
  42 }
  43
  44 static int __init nf_nat_tftp_init(void)
  45 {
  46         BUG_ON(nf_nat_tftp_hook != NULL);
  47         rcu_assign_pointer(nf_nat_tftp_hook, help);
  48         return 0;
  49 }
  50
  51 module_init(nf_nat_tftp_init);
  52 module_exit(nf_nat_tftp_fini);