net/netfilter/xt_dscp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* IP tables module for matching the value of the IPv4/IPv6 DSCP field
   3  *
   4  * (C) 2002 by Harald Welte <laforge@netfilter.org>
   5  */
   6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   7 #include <linux/module.h>
   8 #include <linux/skbuff.h>
   9 #include <linux/ip.h>
  10 #include <linux/ipv6.h>
  11 #include <net/dsfield.h>
  12
  13 #include <linux/netfilter/x_tables.h>
  14 #include <linux/netfilter/xt_dscp.h>
  15
  16 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  17 MODULE_DESCRIPTION("Xtables: DSCP/TOS field match");
  18 MODULE_LICENSE("GPL");
  19 MODULE_ALIAS("ipt_dscp");
  20 MODULE_ALIAS("ip6t_dscp");
  21 MODULE_ALIAS("ipt_tos");
  22 MODULE_ALIAS("ip6t_tos");
  23
  24 static bool
  25 dscp_mt(const struct sk_buff *skb, struct xt_action_param *par)
  26 {
  27         const struct xt_dscp_info *info = par->matchinfo;
  28         u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
  29
  30         return (dscp == info->dscp) ^ !!info->invert;
  31 }
  32
  33 static bool
  34 dscp_mt6(const struct sk_buff *skb, struct xt_action_param *par)
  35 {
  36         const struct xt_dscp_info *info = par->matchinfo;
  37         u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
  38
  39         return (dscp == info->dscp) ^ !!info->invert;
  40 }
  41
  42 static int dscp_mt_check(const struct xt_mtchk_param *par)
  43 {
  44         const struct xt_dscp_info *info = par->matchinfo;
  45
  46         if (info->dscp > XT_DSCP_MAX)
  47                 return -EDOM;
  48
  49         return 0;
  50 }
  51
  52 static bool tos_mt(const struct sk_buff *skb, struct xt_action_param *par)
  53 {
  54         const struct xt_tos_match_info *info = par->matchinfo;
  55
  56         if (xt_family(par) == NFPROTO_IPV4)
  57                 return ((ip_hdr(skb)->tos & info->tos_mask) ==
  58                        info->tos_value) ^ !!info->invert;
  59         else
  60                 return ((ipv6_get_dsfield(ipv6_hdr(skb)) & info->tos_mask) ==
  61                        info->tos_value) ^ !!info->invert;
  62 }
  63
  64 static struct xt_match dscp_mt_reg[] __read_mostly = {
  65         {
  66                 .name           = "dscp",
  67                 .family         = NFPROTO_IPV4,
  68                 .checkentry     = dscp_mt_check,
  69                 .match          = dscp_mt,
  70                 .matchsize      = sizeof(struct xt_dscp_info),
  71                 .me             = THIS_MODULE,
  72         },
  73         {
  74                 .name           = "dscp",
  75                 .family         = NFPROTO_IPV6,
  76                 .checkentry     = dscp_mt_check,
  77                 .match          = dscp_mt6,
  78                 .matchsize      = sizeof(struct xt_dscp_info),
  79                 .me             = THIS_MODULE,
  80         },
  81         {
  82                 .name           = "tos",
  83                 .revision       = 1,
  84                 .family         = NFPROTO_IPV4,
  85                 .match          = tos_mt,
  86                 .matchsize      = sizeof(struct xt_tos_match_info),
  87                 .me             = THIS_MODULE,
  88         },
  89         {
  90                 .name           = "tos",
  91                 .revision       = 1,
  92                 .family         = NFPROTO_IPV6,
  93                 .match          = tos_mt,
  94                 .matchsize      = sizeof(struct xt_tos_match_info),
  95                 .me             = THIS_MODULE,
  96         },
  97 };
  98
  99 static int __init dscp_mt_init(void)
 100 {
 101         return xt_register_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
 102 }
 103
 104 static void __exit dscp_mt_exit(void)
 105 {
 106         xt_unregister_matches(dscp_mt_reg, ARRAY_SIZE(dscp_mt_reg));
 107 }
 108
 109 module_init(dscp_mt_init);
 110 module_exit(dscp_mt_exit);