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 #include <linux/netfilter_ipv4/ipt_TOS.h>
  22
  23 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  24 MODULE_DESCRIPTION("Xtables: DSCP/TOS field modification");
  25 MODULE_LICENSE("GPL");
  26 MODULE_ALIAS("ipt_DSCP");
  27 MODULE_ALIAS("ip6t_DSCP");
  28 MODULE_ALIAS("ipt_TOS");
  29 MODULE_ALIAS("ip6t_TOS");
  30
  31 static unsigned int
  32 dscp_tg(struct sk_buff *skb, const struct xt_target_param *par)
  33 {
  34         const struct xt_DSCP_info *dinfo = par->targinfo;
  35         u_int8_t dscp = ipv4_get_dsfield(ip_hdr(skb)) >> XT_DSCP_SHIFT;
  36
  37         if (dscp != dinfo->dscp) {
  38                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
  39                         return NF_DROP;
  40
  41                 ipv4_change_dsfield(ip_hdr(skb), (__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_target_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), (__u8)(~XT_DSCP_MASK),
  59                                     dinfo->dscp << XT_DSCP_SHIFT);
  60         }
  61         return XT_CONTINUE;
  62 }
  63
  64 static bool
  65 dscp_tg_check(const char *tablename, const void *e_void,
  66               const struct xt_target *target, void *targinfo,
  67               unsigned int hook_mask)
  68 {
  69         const u_int8_t dscp = ((struct xt_DSCP_info *)targinfo)->dscp;
  70
  71         if (dscp > XT_DSCP_MAX) {
  72                 printk(KERN_WARNING "DSCP: dscp %x out of range\n", dscp);
  73                 return false;
  74         }
  75         return true;
  76 }
  77
  78 static unsigned int
  79 tos_tg_v0(struct sk_buff *skb, const struct xt_target_param *par)
  80 {
  81         const struct ipt_tos_target_info *info = par->targinfo;
  82         struct iphdr *iph = ip_hdr(skb);
  83         u_int8_t oldtos;
  84
  85         if ((iph->tos & IPTOS_TOS_MASK) != info->tos) {
  86                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
  87                         return NF_DROP;
  88
  89                 iph      = ip_hdr(skb);
  90                 oldtos   = iph->tos;
  91                 iph->tos = (iph->tos & IPTOS_PREC_MASK) | info->tos;
  92                 csum_replace2(&iph->check, htons(oldtos), htons(iph->tos));
  93         }
  94
  95         return XT_CONTINUE;
  96 }
  97
  98 static bool
  99 tos_tg_check_v0(const char *tablename, const void *e_void,
 100                 const struct xt_target *target, void *targinfo,
 101                 unsigned int hook_mask)
 102 {
 103         const u_int8_t tos = ((struct ipt_tos_target_info *)targinfo)->tos;
 104
 105         if (tos != IPTOS_LOWDELAY && tos != IPTOS_THROUGHPUT &&
 106             tos != IPTOS_RELIABILITY && tos != IPTOS_MINCOST &&
 107             tos != IPTOS_NORMALSVC) {
 108                 printk(KERN_WARNING "TOS: bad tos value %#x\n", tos);
 109                 return false;
 110         }
 111
 112         return true;
 113 }
 114
 115 static unsigned int
 116 tos_tg(struct sk_buff *skb, const struct xt_target_param *par)
 117 {
 118         const struct xt_tos_target_info *info = par->targinfo;
 119         struct iphdr *iph = ip_hdr(skb);
 120         u_int8_t orig, nv;
 121
 122         orig = ipv4_get_dsfield(iph);
 123         nv   = (orig & ~info->tos_mask) ^ info->tos_value;
 124
 125         if (orig != nv) {
 126                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
 127                         return NF_DROP;
 128                 iph = ip_hdr(skb);
 129                 ipv4_change_dsfield(iph, 0, nv);
 130         }
 131
 132         return XT_CONTINUE;
 133 }
 134
 135 static unsigned int
 136 tos_tg6(struct sk_buff *skb, const struct xt_target_param *par)
 137 {
 138         const struct xt_tos_target_info *info = par->targinfo;
 139         struct ipv6hdr *iph = ipv6_hdr(skb);
 140         u_int8_t orig, nv;
 141
 142         orig = ipv6_get_dsfield(iph);
 143         nv   = (orig & info->tos_mask) ^ info->tos_value;
 144
 145         if (orig != nv) {
 146                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
 147                         return NF_DROP;
 148                 iph = ipv6_hdr(skb);
 149                 ipv6_change_dsfield(iph, 0, nv);
 150         }
 151
 152         return XT_CONTINUE;
 153 }
 154
 155 static struct xt_target dscp_tg_reg[] __read_mostly = {
 156         {
 157                 .name           = "DSCP",
 158                 .family         = NFPROTO_IPV4,
 159                 .checkentry     = dscp_tg_check,
 160                 .target         = dscp_tg,
 161                 .targetsize     = sizeof(struct xt_DSCP_info),
 162                 .table          = "mangle",
 163                 .me             = THIS_MODULE,
 164         },
 165         {
 166                 .name           = "DSCP",
 167                 .family         = NFPROTO_IPV6,
 168                 .checkentry     = dscp_tg_check,
 169                 .target         = dscp_tg6,
 170                 .targetsize     = sizeof(struct xt_DSCP_info),
 171                 .table          = "mangle",
 172                 .me             = THIS_MODULE,
 173         },
 174         {
 175                 .name           = "TOS",
 176                 .revision       = 0,
 177                 .family         = NFPROTO_IPV4,
 178                 .table          = "mangle",
 179                 .target         = tos_tg_v0,
 180                 .targetsize     = sizeof(struct ipt_tos_target_info),
 181                 .checkentry     = tos_tg_check_v0,
 182                 .me             = THIS_MODULE,
 183         },
 184         {
 185                 .name           = "TOS",
 186                 .revision       = 1,
 187                 .family         = NFPROTO_IPV4,
 188                 .table          = "mangle",
 189                 .target         = tos_tg,
 190                 .targetsize     = sizeof(struct xt_tos_target_info),
 191                 .me             = THIS_MODULE,
 192         },
 193         {
 194                 .name           = "TOS",
 195                 .revision       = 1,
 196                 .family         = NFPROTO_IPV6,
 197                 .table          = "mangle",
 198                 .target         = tos_tg6,
 199                 .targetsize     = sizeof(struct xt_tos_target_info),
 200                 .me             = THIS_MODULE,
 201         },
 202 };
 203
 204 static int __init dscp_tg_init(void)
 205 {
 206         return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
 207 }
 208
 209 static void __exit dscp_tg_exit(void)
 210 {
 211         xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
 212 }
 213
 214 module_init(dscp_tg_init);
 215 module_exit(dscp_tg_exit);