LXR linux/net/netfilter/nf_nat

   1// SPDX-License-Identifier: GPL-2.0-only
   2/* (C) 2001-2002 Magnus Boden <mb@ozaba.mine.nu>
   3 */
   4
   5#include <linux/module.h>
   6#include <linux/udp.h>
   7
   8#include <net/netfilter/nf_conntrack_helper.h>
   9#include <net/netfilter/nf_conntrack_expect.h>
  10#include <net/netfilter/nf_nat_helper.h>
  11#include <linux/netfilter/nf_conntrack_tftp.h>
  12
  13#define NAT_HELPER_NAME "tftp"
  14
  15MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>");
  16MODULE_DESCRIPTION("TFTP NAT helper");
  17MODULE_LICENSE("GPL");
  18MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME);
  19
  20static struct nf_conntrack_nat_helper nat_helper_tftp =
  21        NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME);
  22
  23static 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) != 0) {
  34                nf_ct_helper_log(skb, exp->master, "cannot add expectation");
  35                return NF_DROP;
  36        }
  37        return NF_ACCEPT;
  38}
  39
  40static void __exit nf_nat_tftp_fini(void)
  41{
  42        nf_nat_helper_unregister(&nat_helper_tftp);
  43        RCU_INIT_POINTER(nf_nat_tftp_hook, NULL);
  44        synchronize_rcu();
  45}
  46
  47static int __init nf_nat_tftp_init(void)
  48{
  49        BUG_ON(nf_nat_tftp_hook != NULL);
  50        nf_nat_helper_register(&nat_helper_tftp);
  51        RCU_INIT_POINTER(nf_nat_tftp_hook, help);
  52        return 0;
  53}
  54
  55module_init(nf_nat_tftp_init);
  56module_exit(nf_nat_tftp_fini);
  57