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   1 /* IP tables module for matching the value of the IPv4/IPv6 DSCP field
   2  *
   3  * xt_dscp.c,v 1.3 2002/08/05 19:00:21 laforge Exp
   4  *
   5  * (C) 2002 by Harald Welte <laforge@netfilter.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/skbuff.h>
  14 #include <linux/ip.h>
  15 #include <linux/ipv6.h>
  16 #include <net/dsfield.h>
  17
  18 #include <linux/netfilter/xt_dscp.h>
  19 #include <linux/netfilter/x_tables.h>
  20
  21 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  22 MODULE_DESCRIPTION("x_tables DSCP matching module");
  23 MODULE_LICENSE("GPL");
  24 MODULE_ALIAS("ipt_dscp");
  25 MODULE_ALIAS("ip6t_dscp");
  26
  27 static int match(const struct sk_buff *skb,
  28                  const struct net_device *in,
  29                  const struct net_device *out,
  30                  const struct xt_match *match,
  31                  const void *matchinfo,
  32                  int offset,
  33                  unsigned int protoff,
  34                  int *hotdrop)
  35 {
  36         const struct xt_dscp_info *info = matchinfo;
  37         u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
  38
  39         return (dscp == info->dscp) ^ !!info->invert;
  40 }
  41
  42 static int match6(const struct sk_buff *skb,
  43                   const struct net_device *in,
  44                   const struct net_device *out,
  45                   const struct xt_match *match,
  46                   const void *matchinfo,
  47                   int offset,
  48                   unsigned int protoff,
  49                   int *hotdrop)
  50 {
  51         const struct xt_dscp_info *info = matchinfo;
  52         u_int8_t dscp = ipv6_get_dsfield(skb->nh.ipv6h) >> XT_DSCP_SHIFT;
  53
  54         return (dscp == info->dscp) ^ !!info->invert;
  55 }
  56
  57 static int checkentry(const char *tablename,
  58                       const void *info,
  59                       const struct xt_match *match,
  60                       void *matchinfo,
  61                       unsigned int hook_mask)
  62 {
  63         const u_int8_t dscp = ((struct xt_dscp_info *)matchinfo)->dscp;
  64
  65         if (dscp > XT_DSCP_MAX) {
  66                 printk(KERN_ERR "xt_dscp: dscp %x out of range\n", dscp);
  67                 return 0;
  68         }
  69
  70         return 1;
  71 }
  72
  73 static struct xt_match xt_dscp_match[] = {
  74         {
  75                 .name           = "dscp",
  76                 .family         = AF_INET,
  77                 .checkentry     = checkentry,
  78                 .match          = match,
  79                 .matchsize      = sizeof(struct xt_dscp_info),
  80                 .me             = THIS_MODULE,
  81         },
  82         {
  83                 .name           = "dscp",
  84                 .family         = AF_INET6,
  85                 .checkentry     = checkentry,
  86                 .match          = match6,
  87                 .matchsize      = sizeof(struct xt_dscp_info),
  88                 .me             = THIS_MODULE,
  89         },
  90 };
  91
  92 static int __init xt_dscp_match_init(void)
  93 {
  94         return xt_register_matches(xt_dscp_match, ARRAY_SIZE(xt_dscp_match));
  95 }
  96
  97 static void __exit xt_dscp_match_fini(void)
  98 {
  99         xt_unregister_matches(xt_dscp_match, ARRAY_SIZE(xt_dscp_match));
 100 }
 101
 102 module_init(xt_dscp_match_init);
 103 module_exit(xt_dscp_match_fini);