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 dscp_tg_check(const struct xt_tgchk_param *par)
  65 {
  66         const struct xt_DSCP_info *info = par->targinfo;
  67
  68         if (info->dscp > XT_DSCP_MAX) {
  69                 printk(KERN_WARNING "DSCP: dscp %x out of range\n", info->dscp);
  70                 return false;
  71         }
  72         return true;
  73 }
  74
  75 static unsigned int
  76 tos_tg_v0(struct sk_buff *skb, const struct xt_target_param *par)
  77 {
  78         const struct ipt_tos_target_info *info = par->targinfo;
  79         struct iphdr *iph = ip_hdr(skb);
  80         u_int8_t oldtos;
  81
  82         if ((iph->tos & IPTOS_TOS_MASK) != info->tos) {
  83                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
  84                         return NF_DROP;
  85
  86                 iph      = ip_hdr(skb);
  87                 oldtos   = iph->tos;
  88                 iph->tos = (iph->tos & IPTOS_PREC_MASK) | info->tos;
  89                 csum_replace2(&iph->check, htons(oldtos), htons(iph->tos));
  90         }
  91
  92         return XT_CONTINUE;
  93 }
  94
  95 static bool tos_tg_check_v0(const struct xt_tgchk_param *par)
  96 {
  97         const struct ipt_tos_target_info *info = par->targinfo;
  98         const uint8_t tos = info->tos;
  99
 100         if (tos != IPTOS_LOWDELAY && tos != IPTOS_THROUGHPUT &&
 101             tos != IPTOS_RELIABILITY && tos != IPTOS_MINCOST &&
 102             tos != IPTOS_NORMALSVC) {
 103                 printk(KERN_WARNING "TOS: bad tos value %#x\n", tos);
 104                 return false;
 105         }
 106
 107         return true;
 108 }
 109
 110 static unsigned int
 111 tos_tg(struct sk_buff *skb, const struct xt_target_param *par)
 112 {
 113         const struct xt_tos_target_info *info = par->targinfo;
 114         struct iphdr *iph = ip_hdr(skb);
 115         u_int8_t orig, nv;
 116
 117         orig = ipv4_get_dsfield(iph);
 118         nv   = (orig & ~info->tos_mask) ^ info->tos_value;
 119
 120         if (orig != nv) {
 121                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
 122                         return NF_DROP;
 123                 iph = ip_hdr(skb);
 124                 ipv4_change_dsfield(iph, 0, nv);
 125         }
 126
 127         return XT_CONTINUE;
 128 }
 129
 130 static unsigned int
 131 tos_tg6(struct sk_buff *skb, const struct xt_target_param *par)
 132 {
 133         const struct xt_tos_target_info *info = par->targinfo;
 134         struct ipv6hdr *iph = ipv6_hdr(skb);
 135         u_int8_t orig, nv;
 136
 137         orig = ipv6_get_dsfield(iph);
 138         nv   = (orig & info->tos_mask) ^ info->tos_value;
 139
 140         if (orig != nv) {
 141                 if (!skb_make_writable(skb, sizeof(struct iphdr)))
 142                         return NF_DROP;
 143                 iph = ipv6_hdr(skb);
 144                 ipv6_change_dsfield(iph, 0, nv);
 145         }
 146
 147         return XT_CONTINUE;
 148 }
 149
 150 static struct xt_target dscp_tg_reg[] __read_mostly = {
 151         {
 152                 .name           = "DSCP",
 153                 .family         = NFPROTO_IPV4,
 154                 .checkentry     = dscp_tg_check,
 155                 .target         = dscp_tg,
 156                 .targetsize     = sizeof(struct xt_DSCP_info),
 157                 .table          = "mangle",
 158                 .me             = THIS_MODULE,
 159         },
 160         {
 161                 .name           = "DSCP",
 162                 .family         = NFPROTO_IPV6,
 163                 .checkentry     = dscp_tg_check,
 164                 .target         = dscp_tg6,
 165                 .targetsize     = sizeof(struct xt_DSCP_info),
 166                 .table          = "mangle",
 167                 .me             = THIS_MODULE,
 168         },
 169         {
 170                 .name           = "TOS",
 171                 .revision       = 0,
 172                 .family         = NFPROTO_IPV4,
 173                 .table          = "mangle",
 174                 .target         = tos_tg_v0,
 175                 .targetsize     = sizeof(struct ipt_tos_target_info),
 176                 .checkentry     = tos_tg_check_v0,
 177                 .me             = THIS_MODULE,
 178         },
 179         {
 180                 .name           = "TOS",
 181                 .revision       = 1,
 182                 .family         = NFPROTO_IPV4,
 183                 .table          = "mangle",
 184                 .target         = tos_tg,
 185                 .targetsize     = sizeof(struct xt_tos_target_info),
 186                 .me             = THIS_MODULE,
 187         },
 188         {
 189                 .name           = "TOS",
 190                 .revision       = 1,
 191                 .family         = NFPROTO_IPV6,
 192                 .table          = "mangle",
 193                 .target         = tos_tg6,
 194                 .targetsize     = sizeof(struct xt_tos_target_info),
 195                 .me             = THIS_MODULE,
 196         },
 197 };
 198
 199 static int __init dscp_tg_init(void)
 200 {
 201         return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
 202 }
 203
 204 static void __exit dscp_tg_exit(void)
 205 {
 206         xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
 207 }
 208
 209 module_init(dscp_tg_init);
 210 module_exit(dscp_tg_exit);