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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  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_action_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),
  41                                     (__force __u8)(~XT_DSCP_MASK),
  42                                     dinfo->dscp << XT_DSCP_SHIFT);
  43
  44         }
  45         return XT_CONTINUE;
  46 }
  47
  48 static unsigned int
  49 dscp_tg6(struct sk_buff *skb, const struct xt_action_param *par)
  50 {
  51         const struct xt_DSCP_info *dinfo = par->targinfo;
  52         u_int8_t dscp = ipv6_get_dsfield(ipv6_hdr(skb)) >> XT_DSCP_SHIFT;
  53
  54         if (dscp != dinfo->dscp) {
  55                 if (!skb_make_writable(skb, sizeof(struct ipv6hdr)))
  56                         return NF_DROP;
  57
  58                 ipv6_change_dsfield(ipv6_hdr(skb),
  59                                     (__force __u8)(~XT_DSCP_MASK),
  60                                     dinfo->dscp << XT_DSCP_SHIFT);
  61         }
  62         return XT_CONTINUE;
  63 }
  64
  65 static int dscp_tg_check(const struct xt_tgchk_param *par)
  66 {
  67         const struct xt_DSCP_info *info = par->targinfo;
  68
  69         if (info->dscp > XT_DSCP_MAX) {
  70                 pr_info("dscp %x out of range\n", info->dscp);
  71                 return -EDOM;
  72         }
  73         return 0;
  74 }
  75
  76 static unsigned int
  77 tos_tg(struct sk_buff *skb, const struct xt_action_param *par)
  78 {
  79         const struct xt_tos_target_info *info = par->targinfo;
  80         struct iphdr *iph = ip_hdr(skb);
  81         u_int8_t orig, nv;
  82
  83         orig = ipv4_get_dsfield(iph);
  84         nv   = (orig & ~info->tos_mask) ^ info->tos_value;
  85
  86         if (orig != nv) {
  87                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
  88                         return NF_DROP;
  89                 iph = ip_hdr(skb);
  90                 ipv4_change_dsfield(iph, 0, nv);
  91         }
  92
  93         return XT_CONTINUE;
  94 }
  95
  96 static unsigned int
  97 tos_tg6(struct sk_buff *skb, const struct xt_action_param *par)
  98 {
  99         const struct xt_tos_target_info *info = par->targinfo;
 100         struct ipv6hdr *iph = ipv6_hdr(skb);
 101         u_int8_t orig, nv;
 102
 103         orig = ipv6_get_dsfield(iph);
 104         nv   = (orig & ~info->tos_mask) ^ info->tos_value;
 105
 106         if (orig != nv) {
 107                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
 108                         return NF_DROP;
 109                 iph = ipv6_hdr(skb);
 110                 ipv6_change_dsfield(iph, 0, nv);
 111         }
 112
 113         return XT_CONTINUE;
 114 }
 115
 116 static struct xt_target dscp_tg_reg[] __read_mostly = {
 117         {
 118                 .name           = "DSCP",
 119                 .family         = NFPROTO_IPV4,
 120                 .checkentry     = dscp_tg_check,
 121                 .target         = dscp_tg,
 122                 .targetsize     = sizeof(struct xt_DSCP_info),
 123                 .table          = "mangle",
 124                 .me             = THIS_MODULE,
 125         },
 126         {
 127                 .name           = "DSCP",
 128                 .family         = NFPROTO_IPV6,
 129                 .checkentry     = dscp_tg_check,
 130                 .target         = dscp_tg6,
 131                 .targetsize     = sizeof(struct xt_DSCP_info),
 132                 .table          = "mangle",
 133                 .me             = THIS_MODULE,
 134         },
 135         {
 136                 .name           = "TOS",
 137                 .revision       = 1,
 138                 .family         = NFPROTO_IPV4,
 139                 .table          = "mangle",
 140                 .target         = tos_tg,
 141                 .targetsize     = sizeof(struct xt_tos_target_info),
 142                 .me             = THIS_MODULE,
 143         },
 144         {
 145                 .name           = "TOS",
 146                 .revision       = 1,
 147                 .family         = NFPROTO_IPV6,
 148                 .table          = "mangle",
 149                 .target         = tos_tg6,
 150                 .targetsize     = sizeof(struct xt_tos_target_info),
 151                 .me             = THIS_MODULE,
 152         },
 153 };
 154
 155 static int __init dscp_tg_init(void)
 156 {
 157         return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
 158 }
 159
 160 static void __exit dscp_tg_exit(void)
 161 {
 162         xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
 163 }
 164
 165 module_init(dscp_tg_init);
 166 module_exit(dscp_tg_exit);