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   1 /* IP tables module for matching the value of the IPv4/IPv6 DSCP field
   2  *
   3  * (C) 2002 by Harald Welte <laforge@netfilter.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/ip.h>
  13 #include <linux/ipv6.h>
  14 #include <net/dsfield.h>
  15
  16 #include <linux/netfilter/xt_dscp.h>
  17 #include <linux/netfilter/x_tables.h>
  18
  19 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  20 MODULE_DESCRIPTION("x_tables DSCP matching module");
  21 MODULE_LICENSE("GPL");
  22 MODULE_ALIAS("ipt_dscp");
  23 MODULE_ALIAS("ip6t_dscp");
  24
  25 static bool match(const struct sk_buff *skb,
  26                   const struct net_device *in,
  27                   const struct net_device *out,
  28                   const struct xt_match *match,
  29                   const void *matchinfo,
  30                   int offset,
  31                   unsigned int protoff,
  32                   bool *hotdrop)
  33 {
  34         const struct xt_dscp_info *info = matchinfo;
  35         u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
  36
  37         return (dscp == info->dscp) ^ !!info->invert;
  38 }
  39
  40 static bool match6(const struct sk_buff *skb,
  41                    const struct net_device *in,
  42                    const struct net_device *out,
  43                    const struct xt_match *match,
  44                    const void *matchinfo,
  45                    int offset,
  46                    unsigned int protoff,
  47                    bool *hotdrop)
  48 {
  49         const struct xt_dscp_info *info = matchinfo;
  50         u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
  51
  52         return (dscp == info->dscp) ^ !!info->invert;
  53 }
  54
  55 static bool checkentry(const char *tablename,
  56                        const void *info,
  57                        const struct xt_match *match,
  58                        void *matchinfo,
  59                        unsigned int hook_mask)
  60 {
  61         const u_int8_t dscp = ((struct xt_dscp_info *)matchinfo)->dscp;
  62
  63         if (dscp > XT_DSCP_MAX) {
  64                 printk(KERN_ERR "xt_dscp: dscp %x out of range\n", dscp);
  65                 return false;
  66         }
  67
  68         return true;
  69 }
  70
  71 static struct xt_match xt_dscp_match[] __read_mostly = {
  72         {
  73                 .name           = "dscp",
  74                 .family         = AF_INET,
  75                 .checkentry     = checkentry,
  76                 .match          = match,
  77                 .matchsize      = sizeof(struct xt_dscp_info),
  78                 .me             = THIS_MODULE,
  79         },
  80         {
  81                 .name           = "dscp",
  82                 .family         = AF_INET6,
  83                 .checkentry     = checkentry,
  84                 .match          = match6,
  85                 .matchsize      = sizeof(struct xt_dscp_info),
  86                 .me             = THIS_MODULE,
  87         },
  88 };
  89
  90 static int __init xt_dscp_match_init(void)
  91 {
  92         return xt_register_matches(xt_dscp_match, ARRAY_SIZE(xt_dscp_match));
  93 }
  94
  95 static void __exit xt_dscp_match_fini(void)
  96 {
  97         xt_unregister_matches(xt_dscp_match, ARRAY_SIZE(xt_dscp_match));
  98 }
  99
 100 module_init(xt_dscp_match_init);
 101 module_exit(xt_dscp_match_fini);