release/src-rt-6.x.4708/linux/linux-2.6.36/net/ipv4/netfilter/ipt_TOS.c

   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
  19 MODULE_LICENSE("GPL");
  20 MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
  21 MODULE_DESCRIPTION("iptables TOS mangling module");
  22
  23 static unsigned int target(struct sk_buff *skb, const struct xt_action_param *par)
  24 {
  25         const struct ipt_tos_target_info *tosinfo = par->targinfo;
  26         struct iphdr *iph = ip_hdr(skb);
  27
  28         if ((iph->tos & IPTOS_TOS_MASK) != tosinfo->tos) {
  29                 __u8 oldtos;
  30                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
  31                         return NF_DROP;
  32                 iph = ip_hdr(skb);
  33                 oldtos = iph->tos;
  34                 iph->tos = (iph->tos & IPTOS_PREC_MASK) | tosinfo->tos;
  35                 csum_replace2(&iph->check, htons(oldtos), htons(iph->tos));
  36         }
  37         return XT_CONTINUE;
  38 }
  39
  40 static int checkentry(const struct xt_tgchk_param *par)
  41 {
  42         const u_int8_t tos = ((struct ipt_tos_target_info *)par->targinfo)->tos;
  43
  44         if (tos != IPTOS_LOWDELAY
  45             && tos != IPTOS_THROUGHPUT
  46             && tos != IPTOS_RELIABILITY
  47             && tos != IPTOS_MINCOST
  48             && tos != IPTOS_NORMALSVC) {
  49                 printk(KERN_WARNING "TOS: bad tos value %#x\n", tos);
  50                 return -EINVAL;
  51         }
  52         return 0;
  53 }
  54
  55 static struct xt_target ipt_tos_reg = {
  56         .name           = "TOS",
  57         .family         = NFPROTO_IPV4,
  58         .target         = target,
  59         .targetsize     = sizeof(struct ipt_tos_target_info),
  60         .table          = "mangle",
  61         .checkentry     = checkentry,
  62         .me             = THIS_MODULE,
  63 };
  64
  65 static int __init ipt_tos_init(void)
  66 {
  67         return xt_register_target(&ipt_tos_reg);
  68 }
  69
  70 static void __exit ipt_tos_fini(void)
  71 {
  72         xt_unregister_target(&ipt_tos_reg);
  73 }
  74
  75 module_init(ipt_tos_init);
  76 module_exit(ipt_tos_fini);