1/* This is a module which is used for setting the TOS field of a packet. */ 2 3/* (C) 1999-2001 Paul `Rusty' Russell 4 * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 */ 10 11#include <linux/module.h> 12#include <linux/skbuff.h> 13#include <linux/ip.h> 14#include <net/checksum.h> 15 16#include <linux/netfilter/x_tables.h> 17#include <linux/netfilter_ipv4/ipt_TOS.h> 18 19MODULE_LICENSE("GPL"); 20MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); 21MODULE_DESCRIPTION("iptables TOS mangling module"); 22 23static unsigned int 24target(struct sk_buff **pskb, 25 const struct net_device *in, 26 const struct net_device *out, 27 unsigned int hooknum, 28 const struct xt_target *target, 29 const void *targinfo) 30{ 31 const struct ipt_tos_target_info *tosinfo = targinfo; 32 struct iphdr *iph = ip_hdr(*pskb); 33 34 if ((iph->tos & IPTOS_TOS_MASK) != tosinfo->tos) { 35 __u8 oldtos; 36 if (!skb_make_writable(pskb, sizeof(struct iphdr))) 37 return NF_DROP; 38 iph = ip_hdr(*pskb); 39 oldtos = iph->tos; 40 iph->tos = (iph->tos & IPTOS_PREC_MASK) | tosinfo->tos; 41 nf_csum_replace2(&iph->check, htons(oldtos), htons(iph->tos)); 42 } 43 return XT_CONTINUE; 44} 45 46static int 47checkentry(const char *tablename, 48 const void *e_void, 49 const struct xt_target *target, 50 void *targinfo, 51 unsigned int hook_mask) 52{ 53 const u_int8_t tos = ((struct ipt_tos_target_info *)targinfo)->tos; 54 55 if (tos != IPTOS_LOWDELAY 56 && tos != IPTOS_THROUGHPUT 57 && tos != IPTOS_RELIABILITY 58 && tos != IPTOS_MINCOST 59 && tos != IPTOS_NORMALSVC) { 60 printk(KERN_WARNING "TOS: bad tos value %#x\n", tos); 61 return 0; 62 } 63 return 1; 64} 65 66static struct xt_target ipt_tos_reg = { 67 .name = "TOS", 68 .family = AF_INET, 69 .target = target, 70 .targetsize = sizeof(struct ipt_tos_target_info), 71 .table = "mangle", 72 .checkentry = checkentry, 73 .me = THIS_MODULE, 74}; 75 76static int __init ipt_tos_init(void) 77{ 78 return xt_register_target(&ipt_tos_reg); 79} 80 81static void __exit ipt_tos_fini(void) 82{ 83 xt_unregister_target(&ipt_tos_reg); 84} 85 86module_init(ipt_tos_init); 87module_exit(ipt_tos_fini); 88