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![Patrick McHardy](/assets/img/avatar_default.png)
Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
134 lines
3.2 KiB
C
134 lines
3.2 KiB
C
/* IP tables module for matching the value of the IPv4 and TCP ECN bits
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*
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* (C) 2002 by Harald Welte <laforge@gnumonks.org>
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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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#include <linux/in.h>
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#include <linux/ip.h>
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#include <net/ip.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/tcp.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv4/ipt_ecn.h>
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MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
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MODULE_DESCRIPTION("iptables ECN matching module");
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MODULE_LICENSE("GPL");
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static inline bool match_ip(const struct sk_buff *skb,
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const struct ipt_ecn_info *einfo)
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{
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return (ip_hdr(skb)->tos & IPT_ECN_IP_MASK) == einfo->ip_ect;
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}
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static inline bool match_tcp(const struct sk_buff *skb,
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const struct ipt_ecn_info *einfo,
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bool *hotdrop)
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{
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struct tcphdr _tcph;
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const struct tcphdr *th;
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/* In practice, TCP match does this, so can't fail. But let's
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* be good citizens.
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*/
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th = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_tcph), &_tcph);
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if (th == NULL) {
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*hotdrop = false;
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return false;
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}
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if (einfo->operation & IPT_ECN_OP_MATCH_ECE) {
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if (einfo->invert & IPT_ECN_OP_MATCH_ECE) {
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if (th->ece == 1)
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return false;
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} else {
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if (th->ece == 0)
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return false;
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}
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}
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if (einfo->operation & IPT_ECN_OP_MATCH_CWR) {
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if (einfo->invert & IPT_ECN_OP_MATCH_CWR) {
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if (th->cwr == 1)
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return false;
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} else {
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if (th->cwr == 0)
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return false;
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}
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}
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return true;
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}
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static bool match(const struct sk_buff *skb,
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const struct net_device *in, const struct net_device *out,
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const struct xt_match *match, const void *matchinfo,
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int offset, unsigned int protoff, bool *hotdrop)
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{
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const struct ipt_ecn_info *info = matchinfo;
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if (info->operation & IPT_ECN_OP_MATCH_IP)
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if (!match_ip(skb, info))
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return false;
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if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)) {
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if (ip_hdr(skb)->protocol != IPPROTO_TCP)
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return false;
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if (!match_tcp(skb, info, hotdrop))
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return false;
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}
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return true;
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}
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static bool checkentry(const char *tablename, const void *ip_void,
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const struct xt_match *match,
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void *matchinfo, unsigned int hook_mask)
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{
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const struct ipt_ecn_info *info = matchinfo;
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const struct ipt_ip *ip = ip_void;
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if (info->operation & IPT_ECN_OP_MATCH_MASK)
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return false;
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if (info->invert & IPT_ECN_OP_MATCH_MASK)
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return false;
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if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)
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&& ip->proto != IPPROTO_TCP) {
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printk(KERN_WARNING "ipt_ecn: can't match TCP bits in rule for"
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" non-tcp packets\n");
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return false;
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}
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return true;
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}
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static struct xt_match ecn_match __read_mostly = {
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.name = "ecn",
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.family = AF_INET,
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.match = match,
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.matchsize = sizeof(struct ipt_ecn_info),
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.checkentry = checkentry,
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.me = THIS_MODULE,
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};
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static int __init ipt_ecn_init(void)
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{
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return xt_register_match(&ecn_match);
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}
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static void __exit ipt_ecn_fini(void)
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{
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xt_unregister_match(&ecn_match);
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}
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module_init(ipt_ecn_init);
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module_exit(ipt_ecn_fini);
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