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