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 net_device *in,
  30         const struct net_device *out, const struct xt_match *match,
  31         const void *matchinfo, int offset, unsigned int protoff, bool *hotdrop)
  32 {
  33         const struct xt_dscp_info *info = matchinfo;
  34         u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
  35
  36         return (dscp == info->dscp) ^ !!info->invert;
  37 }
  38
  39 static bool
  40 dscp_mt6(const struct sk_buff *skb, const struct net_device *in,
  41          const struct net_device *out, const struct xt_match *match,
  42          const void *matchinfo, int offset, unsigned int protoff,
  43          bool *hotdrop)
  44 {
  45         const struct xt_dscp_info *info = matchinfo;
  46         u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
  47
  48         return (dscp == info->dscp) ^ !!info->invert;
  49 }
  50
  51 static bool
  52 dscp_mt_check(const char *tablename, const void *info,
  53               const struct xt_match *match, void *matchinfo,
  54               unsigned int hook_mask)
  55 {
  56         const u_int8_t dscp = ((struct xt_dscp_info *)matchinfo)->dscp;
  57
  58         if (dscp > XT_DSCP_MAX) {
  59                 printk(KERN_ERR "xt_dscp: dscp %x out of range\n", dscp);
  60                 return false;
  61         }
  62
  63         return true;
  64 }
  65
  66 static bool tos_mt_v0(const struct sk_buff *skb, const struct net_device *in,
  67                       const struct net_device *out,
  68                       const struct xt_match *match, const void *matchinfo,
  69                       int offset, unsigned int protoff, bool *hotdrop)
  70 {
  71         const struct ipt_tos_info *info = matchinfo;
  72
  73         return (ip_hdr(skb)->tos == info->tos) ^ info->invert;
  74 }
  75
  76 static bool tos_mt(const struct sk_buff *skb, const struct net_device *in,
  77                    const struct net_device *out, const struct xt_match *match,
  78                    const void *matchinfo, int offset, unsigned int protoff,
  79                    bool *hotdrop)
  80 {
  81         const struct xt_tos_match_info *info = matchinfo;
  82
  83         if (match->family == AF_INET)
  84                 return ((ip_hdr(skb)->tos & info->tos_mask) ==
  85                        info->tos_value) ^ !!info->invert;
  86         else
  87                 return ((ipv6_get_dsfield(ipv6_hdr(skb)) & info->tos_mask) ==
  88                        info->tos_value) ^ !!info->invert;
  89 }
  90
  91 static struct xt_match dscp_mt_reg[] __read_mostly = {
  92         {
  93                 .name           = "dscp",
  94                 .family         = AF_INET,
  95                 .checkentry     = dscp_mt_check,
  96                 .match          = dscp_mt,
  97                 .matchsize      = sizeof(struct xt_dscp_info),
  98                 .me             = THIS_MODULE,
  99         },
 100         {
 101                 .name           = "dscp",
 102                 .family         = AF_INET6,
 103                 .checkentry     = dscp_mt_check,
 104                 .match          = dscp_mt6,
 105                 .matchsize      = sizeof(struct xt_dscp_info),
 106                 .me             = THIS_MODULE,
 107         },
 108         {
 109                 .name           = "tos",
 110                 .revision       = 0,
 111                 .family         = AF_INET,
 112                 .match          = tos_mt_v0,
 113                 .matchsize      = sizeof(struct ipt_tos_info),
 114                 .me             = THIS_MODULE,
 115         },
 116         {
 117                 .name           = "tos",
 118                 .revision       = 1,
 119                 .family         = AF_INET,
 120                 .match          = tos_mt,
 121                 .matchsize      = sizeof(struct xt_tos_match_info),
 122                 .me             = THIS_MODULE,
 123         },
 124         {
 125                 .name           = "tos",
 126                 .revision       = 1,
 127                 .family         = AF_INET6,
 128                 .match          = tos_mt,
 129                 .matchsize      = sizeof(struct xt_tos_match_info),
 130                 .me             = THIS_MODULE,
 131         },
 132 };
 133
 134 static int __init dscp_mt_init(void)
 135 {
 136         return xt_register_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
 137 }
 138
 139 static void __exit dscp_mt_exit(void)
 140 {
 141         xt_unregister_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
 142 }
 143
 144 module_init(dscp_mt_init);
 145 module_exit(dscp_mt_exit);