net/netfilter/xt_DSCP.c

   1 /* x_tables module for setting the IPv4/IPv6 DSCP field, Version 1.8
   2  *
   3  * (C) 2002 by Harald Welte <laforge@netfilter.org>
   4  * based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * See RFC2474 for a description of the DSCP field within the IP Header.
  11 */
  12
  13 #include <linux/module.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/ip.h>
  16 #include <linux/ipv6.h>
  17 #include <net/dsfield.h>
  18
  19 #include <linux/netfilter/x_tables.h>
  20 #include <linux/netfilter/xt_DSCP.h>
  21
  22 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  23 MODULE_DESCRIPTION("Xtables: DSCP/TOS field modification");
  24 MODULE_LICENSE("GPL");
  25 MODULE_ALIAS("ipt_DSCP");
  26 MODULE_ALIAS("ip6t_DSCP");
  27 MODULE_ALIAS("ipt_TOS");
  28 MODULE_ALIAS("ip6t_TOS");
  29
  30 static unsigned int
  31 dscp_tg(struct sk_buff *skb, const struct xt_target_param *par)
  32 {
  33         const struct xt_DSCP_info *dinfo = par->targinfo;
  34         u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
  35
  36         if (dscp != dinfo->dscp) {
  37                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
  38                         return NF_DROP;
  39
  40                 ipv4_change_dsfield(ip_hdr(skb), (__u8)(~XT_DSCP_MASK),
  41                                     dinfo->dscp << XT_DSCP_SHIFT);
  42
  43         }
  44         return XT_CONTINUE;
  45 }
  46
  47 static unsigned int
  48 dscp_tg6(struct sk_buff *skb, const struct xt_target_param *par)
  49 {
  50         const struct xt_DSCP_info *dinfo = par->targinfo;
  51         u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
  52
  53         if (dscp != dinfo->dscp) {
  54                 if (!skb_make_writable(skb, sizeof(struct ipv6hdr)))
  55                         return NF_DROP;
  56
  57                 ipv6_change_dsfield(ipv6_hdr(skb), (__u8)(~XT_DSCP_MASK),
  58                                     dinfo->dscp << XT_DSCP_SHIFT);
  59         }
  60         return XT_CONTINUE;
  61 }
  62
  63 static bool dscp_tg_check(const struct xt_tgchk_param *par)
  64 {
  65         const struct xt_DSCP_info *info = par->targinfo;
  66
  67         if (info->dscp > XT_DSCP_MAX) {
  68                 printk(KERN_WARNING "DSCP: dscp %x out of range\n", info->dscp);
  69                 return false;
  70         }
  71         return true;
  72 }
  73
  74 static unsigned int
  75 tos_tg(struct sk_buff *skb, const struct xt_target_param *par)
  76 {
  77         const struct xt_tos_target_info *info = par->targinfo;
  78         struct iphdr *iph = ip_hdr(skb);
  79         u_int8_t orig, nv;
  80
  81         orig = ipv4_get_dsfield(iph);
  82         nv   = (orig & ~info->tos_mask) ^ info->tos_value;
  83
  84         if (orig != nv) {
  85                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
  86                         return NF_DROP;
  87                 iph = ip_hdr(skb);
  88                 ipv4_change_dsfield(iph, 0, nv);
  89         }
  90
  91         return XT_CONTINUE;
  92 }
  93
  94 static unsigned int
  95 tos_tg6(struct sk_buff *skb, const struct xt_target_param *par)
  96 {
  97         const struct xt_tos_target_info *info = par->targinfo;
  98         struct ipv6hdr *iph = ipv6_hdr(skb);
  99         u_int8_t orig, nv;
 100
 101         orig = ipv6_get_dsfield(iph);
 102         nv   = (orig & info->tos_mask) ^ info->tos_value;
 103
 104         if (orig != nv) {
 105                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
 106                         return NF_DROP;
 107                 iph = ipv6_hdr(skb);
 108                 ipv6_change_dsfield(iph, 0, nv);
 109         }
 110
 111         return XT_CONTINUE;
 112 }
 113
 114 static struct xt_target dscp_tg_reg[] __read_mostly = {
 115         {
 116                 .name           = "DSCP",
 117                 .family         = NFPROTO_IPV4,
 118                 .checkentry     = dscp_tg_check,
 119                 .target         = dscp_tg,
 120                 .targetsize     = sizeof(struct xt_DSCP_info),
 121                 .table          = "mangle",
 122                 .me             = THIS_MODULE,
 123         },
 124         {
 125                 .name           = "DSCP",
 126                 .family         = NFPROTO_IPV6,
 127                 .checkentry     = dscp_tg_check,
 128                 .target         = dscp_tg6,
 129                 .targetsize     = sizeof(struct xt_DSCP_info),
 130                 .table          = "mangle",
 131                 .me             = THIS_MODULE,
 132         },
 133         {
 134                 .name           = "TOS",
 135                 .revision       = 1,
 136                 .family         = NFPROTO_IPV4,
 137                 .table          = "mangle",
 138                 .target         = tos_tg,
 139                 .targetsize     = sizeof(struct xt_tos_target_info),
 140                 .me             = THIS_MODULE,
 141         },
 142         {
 143                 .name           = "TOS",
 144                 .revision       = 1,
 145                 .family         = NFPROTO_IPV6,
 146                 .table          = "mangle",
 147                 .target         = tos_tg6,
 148                 .targetsize     = sizeof(struct xt_tos_target_info),
 149                 .me             = THIS_MODULE,
 150         },
 151 };
 152
 153 static int __init dscp_tg_init(void)
 154 {
 155         return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
 156 }
 157
 158 static void __exit dscp_tg_exit(void)
 159 {
 160         xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
 161 }
 162
 163 module_init(dscp_tg_init);
 164 module_exit(dscp_tg_exit);