net/netfilter/xt_dscp.c

   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/x_tables.h>
  17 #include <linux/netfilter/xt_dscp.h>
  18 #include <linux/netfilter_ipv4/ipt_tos.h>
  19
  20 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  21 MODULE_DESCRIPTION("Xtables: DSCP/TOS field match");
  22 MODULE_LICENSE("GPL");
  23 MODULE_ALIAS("ipt_dscp");
  24 MODULE_ALIAS("ip6t_dscp");
  25 MODULE_ALIAS("ipt_tos");
  26 MODULE_ALIAS("ip6t_tos");
  27
  28 static bool
  29 dscp_mt(const struct sk_buff *skb, const struct xt_match_param *par)
  30 {
  31         const struct xt_dscp_info *info = par->matchinfo;
  32         u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
  33
  34         return (dscp == info->dscp) ^ !!info->invert;
  35 }
  36
  37 static bool
  38 dscp_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
  39 {
  40         const struct xt_dscp_info *info = par->matchinfo;
  41         u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
  42
  43         return (dscp == info->dscp) ^ !!info->invert;
  44 }
  45
  46 static bool dscp_mt_check(const struct xt_mtchk_param *par)
  47 {
  48         const struct xt_dscp_info *info = par->matchinfo;
  49
  50         if (info->dscp > XT_DSCP_MAX) {
  51                 printk(KERN_ERR "xt_dscp: dscp %x out of range\n", info->dscp);
  52                 return false;
  53         }
  54
  55         return true;
  56 }
  57
  58 static bool
  59 tos_mt_v0(const struct sk_buff *skb, const struct xt_match_param *par)
  60 {
  61         const struct ipt_tos_info *info = par->matchinfo;
  62
  63         return (ip_hdr(skb)->tos == info->tos) ^ info->invert;
  64 }
  65
  66 static bool tos_mt(const struct sk_buff *skb, const struct xt_match_param *par)
  67 {
  68         const struct xt_tos_match_info *info = par->matchinfo;
  69
  70         if (par->match->family == NFPROTO_IPV4)
  71                 return ((ip_hdr(skb)->tos & info->tos_mask) ==
  72                        info->tos_value) ^ !!info->invert;
  73         else
  74                 return ((ipv6_get_dsfield(ipv6_hdr(skb)) & info->tos_mask) ==
  75                        info->tos_value) ^ !!info->invert;
  76 }
  77
  78 static struct xt_match dscp_mt_reg[] __read_mostly = {
  79         {
  80                 .name           = "dscp",
  81                 .family         = NFPROTO_IPV4,
  82                 .checkentry     = dscp_mt_check,
  83                 .match          = dscp_mt,
  84                 .matchsize      = sizeof(struct xt_dscp_info),
  85                 .me             = THIS_MODULE,
  86         },
  87         {
  88                 .name           = "dscp",
  89                 .family         = NFPROTO_IPV6,
  90                 .checkentry     = dscp_mt_check,
  91                 .match          = dscp_mt6,
  92                 .matchsize      = sizeof(struct xt_dscp_info),
  93                 .me             = THIS_MODULE,
  94         },
  95         {
  96                 .name           = "tos",
  97                 .revision       = 0,
  98                 .family         = NFPROTO_IPV4,
  99                 .match          = tos_mt_v0,
 100                 .matchsize      = sizeof(struct ipt_tos_info),
 101                 .me             = THIS_MODULE,
 102         },
 103         {
 104                 .name           = "tos",
 105                 .revision       = 1,
 106                 .family         = NFPROTO_IPV4,
 107                 .match          = tos_mt,
 108                 .matchsize      = sizeof(struct xt_tos_match_info),
 109                 .me             = THIS_MODULE,
 110         },
 111         {
 112                 .name           = "tos",
 113                 .revision       = 1,
 114                 .family         = NFPROTO_IPV6,
 115                 .match          = tos_mt,
 116                 .matchsize      = sizeof(struct xt_tos_match_info),
 117                 .me             = THIS_MODULE,
 118         },
 119 };
 120
 121 static int __init dscp_mt_init(void)
 122 {
 123         return xt_register_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
 124 }
 125
 126 static void __exit dscp_mt_exit(void)
 127 {
 128         xt_unregister_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
 129 }
 130
 131 module_init(dscp_mt_init);
 132 module_exit(dscp_mt_exit);