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 15 MODULE_AUTHOR("Magnus Boden <mb@ozaba.mine.nu>"); 16 MODULE_DESCRIPTION("TFTP NAT helper"); 17 MODULE_LICENSE("GPL"); 18 MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME); 19 20 static struct nf_conntrack_nat_helper nat_helper_tftp = 21 NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME); 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) != 0) { 34 nf_ct_helper_log(skb, exp->master, "cannot add expectation"); 35 return NF_DROP; 36 } 37 return NF_ACCEPT; 38 } 39 40 static 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 47 static 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 55 module_init(nf_nat_tftp_init); 56 module_exit(nf_nat_tftp_fini); 57