106 lines
2.7 KiB
C
106 lines
2.7 KiB
C
/* iptables module for setting the IPv4 DSCP field, Version 1.8
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*
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* (C) 2002 by Harald Welte <laforge@netfilter.org>
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* based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* See RFC2474 for a description of the DSCP field within the IP Header.
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*
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* ipt_DSCP.c,v 1.8 2002/08/06 18:41:57 laforge Exp
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/ip.h>
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#include <net/checksum.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv4/ipt_DSCP.h>
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MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
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MODULE_DESCRIPTION("iptables DSCP modification module");
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MODULE_LICENSE("GPL");
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static unsigned int
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target(struct sk_buff **pskb,
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const struct net_device *in,
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const struct net_device *out,
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unsigned int hooknum,
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const void *targinfo,
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void *userinfo)
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{
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const struct ipt_DSCP_info *dinfo = targinfo;
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u_int8_t sh_dscp = ((dinfo->dscp << IPT_DSCP_SHIFT) & IPT_DSCP_MASK);
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if (((*pskb)->nh.iph->tos & IPT_DSCP_MASK) != sh_dscp) {
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u_int16_t diffs[2];
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if (!skb_make_writable(pskb, sizeof(struct iphdr)))
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return NF_DROP;
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diffs[0] = htons((*pskb)->nh.iph->tos) ^ 0xFFFF;
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(*pskb)->nh.iph->tos = ((*pskb)->nh.iph->tos & ~IPT_DSCP_MASK)
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| sh_dscp;
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diffs[1] = htons((*pskb)->nh.iph->tos);
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(*pskb)->nh.iph->check
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= csum_fold(csum_partial((char *)diffs,
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sizeof(diffs),
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(*pskb)->nh.iph->check
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^ 0xFFFF));
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}
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return IPT_CONTINUE;
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}
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static int
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checkentry(const char *tablename,
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const struct ipt_entry *e,
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void *targinfo,
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unsigned int targinfosize,
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unsigned int hook_mask)
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{
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const u_int8_t dscp = ((struct ipt_DSCP_info *)targinfo)->dscp;
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if (targinfosize != IPT_ALIGN(sizeof(struct ipt_DSCP_info))) {
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printk(KERN_WARNING "DSCP: targinfosize %u != %Zu\n",
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targinfosize,
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IPT_ALIGN(sizeof(struct ipt_DSCP_info)));
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return 0;
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}
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if (strcmp(tablename, "mangle") != 0) {
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printk(KERN_WARNING "DSCP: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
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return 0;
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}
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if ((dscp > IPT_DSCP_MAX)) {
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printk(KERN_WARNING "DSCP: dscp %x out of range\n", dscp);
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return 0;
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}
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return 1;
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}
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static struct ipt_target ipt_dscp_reg = {
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.name = "DSCP",
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.target = target,
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.checkentry = checkentry,
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.me = THIS_MODULE,
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};
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static int __init init(void)
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{
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return ipt_register_target(&ipt_dscp_reg);
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}
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static void __exit fini(void)
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{
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ipt_unregister_target(&ipt_dscp_reg);
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}
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module_init(init);
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module_exit(fini);
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