linux/net/netfilter/xt_dscp.c
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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#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
  19MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  20MODULE_DESCRIPTION("Xtables: DSCP/TOS field match");
  21MODULE_LICENSE("GPL");
  22MODULE_ALIAS("ipt_dscp");
  23MODULE_ALIAS("ip6t_dscp");
  24MODULE_ALIAS("ipt_tos");
  25MODULE_ALIAS("ip6t_tos");
  26
  27static bool
  28dscp_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
  36static bool
  37dscp_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
  45static 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                pr_info("dscp %x out of range\n", info->dscp);
  51                return -EDOM;
  52        }
  53
  54        return 0;
  55}
  56
  57static bool tos_mt(const struct sk_buff *skb, struct xt_action_param *par)
  58{
  59        const struct xt_tos_match_info *info = par->matchinfo;
  60
  61        if (par->family == NFPROTO_IPV4)
  62                return ((ip_hdr(skb)->tos & info->tos_mask) ==
  63                       info->tos_value) ^ !!info->invert;
  64        else
  65                return ((ipv6_get_dsfield(ipv6_hdr(skb)) & info->tos_mask) ==
  66                       info->tos_value) ^ !!info->invert;
  67}
  68
  69static struct xt_match dscp_mt_reg[] __read_mostly = {
  70        {
  71                .name           = "dscp",
  72                .family         = NFPROTO_IPV4,
  73                .checkentry     = dscp_mt_check,
  74                .match          = dscp_mt,
  75                .matchsize      = sizeof(struct xt_dscp_info),
  76                .me             = THIS_MODULE,
  77        },
  78        {
  79                .name           = "dscp",
  80                .family         = NFPROTO_IPV6,
  81                .checkentry     = dscp_mt_check,
  82                .match          = dscp_mt6,
  83                .matchsize      = sizeof(struct xt_dscp_info),
  84                .me             = THIS_MODULE,
  85        },
  86        {
  87                .name           = "tos",
  88                .revision       = 1,
  89                .family         = NFPROTO_IPV4,
  90                .match          = tos_mt,
  91                .matchsize      = sizeof(struct xt_tos_match_info),
  92                .me             = THIS_MODULE,
  93        },
  94        {
  95                .name           = "tos",
  96                .revision       = 1,
  97                .family         = NFPROTO_IPV6,
  98                .match          = tos_mt,
  99                .matchsize      = sizeof(struct xt_tos_match_info),
 100                .me             = THIS_MODULE,
 101        },
 102};
 103
 104static int __init dscp_mt_init(void)
 105{
 106        return xt_register_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
 107}
 108
 109static void __exit dscp_mt_exit(void)
 110{
 111        xt_unregister_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
 112}
 113
 114module_init(dscp_mt_init);
 115module_exit(dscp_mt_exit);
 116
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