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