linux/net/netfilter/xt_DSCP.c
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   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
  22MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  23MODULE_DESCRIPTION("Xtables: DSCP/TOS field modification");
  24MODULE_LICENSE("GPL");
  25MODULE_ALIAS("ipt_DSCP");
  26MODULE_ALIAS("ip6t_DSCP");
  27MODULE_ALIAS("ipt_TOS");
  28MODULE_ALIAS("ip6t_TOS");
  29
  30static unsigned int
  31dscp_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), (__u8)(~XT_DSCP_MASK),
  41                                    dinfo->dscp << XT_DSCP_SHIFT);
  42
  43        }
  44        return XT_CONTINUE;
  45}
  46
  47static unsigned int
  48dscp_tg6(struct sk_buff *skb, const struct xt_action_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
  63static int 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                pr_info("dscp %x out of range\n", info->dscp);
  69                return -EDOM;
  70        }
  71        return 0;
  72}
  73
  74static unsigned int
  75tos_tg(struct sk_buff *skb, const struct xt_action_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
  94static unsigned int
  95tos_tg6(struct sk_buff *skb, const struct xt_action_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
 114static 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
 153static int __init dscp_tg_init(void)
 154{
 155        return xt_register_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
 156}
 157
 158static void __exit dscp_tg_exit(void)
 159{
 160        xt_unregister_targets(dscp_tg_reg, ARRAY_SIZE(dscp_tg_reg));
 161}
 162
 163module_init(dscp_tg_init);
 164module_exit(dscp_tg_exit);
 165
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