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
  47 dscp_mt_check(const char *tablename, const void *info,
  48               const struct xt_match *match, void *matchinfo,
  49               unsigned int hook_mask)
  50 {
  51         const u_int8_t dscp = ((struct xt_dscp_info *)matchinfo)->dscp;
  52
  53         if (dscp > XT_DSCP_MAX) {
  54                 printk(KERN_ERR "xt_dscp: dscp %x out of range\n", dscp);
  55                 return false;
  56         }
  57
  58         return true;
  59 }
  60
  61 static bool
  62 tos_mt_v0(const struct sk_buff *skb, const struct xt_match_param *par)
  63 {
  64         const struct ipt_tos_info *info = par->matchinfo;
  65
  66         return (ip_hdr(skb)->tos == info->tos) ^ info->invert;
  67 }
  68
  69 static bool tos_mt(const struct sk_buff *skb, const struct xt_match_param *par)
  70 {
  71         const struct xt_tos_match_info *info = par->matchinfo;
  72
  73         if (par->match->family == NFPROTO_IPV4)
  74                 return ((ip_hdr(skb)->tos & info->tos_mask) ==
  75                        info->tos_value) ^ !!info->invert;
  76         else
  77                 return ((ipv6_get_dsfield(ipv6_hdr(skb)) & info->tos_mask) ==
  78                        info->tos_value) ^ !!info->invert;
  79 }
  80
  81 static struct xt_match dscp_mt_reg[] __read_mostly = {
  82         {
  83                 .name           = "dscp",
  84                 .family         = NFPROTO_IPV4,
  85                 .checkentry     = dscp_mt_check,
  86                 .match          = dscp_mt,
  87                 .matchsize      = sizeof(struct xt_dscp_info),
  88                 .me             = THIS_MODULE,
  89         },
  90         {
  91                 .name           = "dscp",
  92                 .family         = NFPROTO_IPV6,
  93                 .checkentry     = dscp_mt_check,
  94                 .match          = dscp_mt6,
  95                 .matchsize      = sizeof(struct xt_dscp_info),
  96                 .me             = THIS_MODULE,
  97         },
  98         {
  99                 .name           = "tos",
 100                 .revision       = 0,
 101                 .family         = NFPROTO_IPV4,
 102                 .match          = tos_mt_v0,
 103                 .matchsize      = sizeof(struct ipt_tos_info),
 104                 .me             = THIS_MODULE,
 105         },
 106         {
 107                 .name           = "tos",
 108                 .revision       = 1,
 109                 .family         = NFPROTO_IPV4,
 110                 .match          = tos_mt,
 111                 .matchsize      = sizeof(struct xt_tos_match_info),
 112                 .me             = THIS_MODULE,
 113         },
 114         {
 115                 .name           = "tos",
 116                 .revision       = 1,
 117                 .family         = NFPROTO_IPV6,
 118                 .match          = tos_mt,
 119                 .matchsize      = sizeof(struct xt_tos_match_info),
 120                 .me             = THIS_MODULE,
 121         },
 122 };
 123
 124 static int __init dscp_mt_init(void)
 125 {
 126         return xt_register_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
 127 }
 128
 129 static void __exit dscp_mt_exit(void)
 130 {
 131         xt_unregister_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
 132 }
 133
 134 module_init(dscp_mt_init);
 135 module_exit(dscp_mt_exit);