| /* IP tables module for matching the value of the IPv4 and TCP ECN bits |
| * |
| * ipt_ecn.c,v 1.3 2002/05/29 15:09:00 laforge Exp |
| * |
| * (C) 2002 by Harald Welte <laforge@gnumonks.org> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/tcp.h> |
| |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <linux/netfilter_ipv4/ipt_ecn.h> |
| |
| MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
| MODULE_DESCRIPTION("iptables ECN matching module"); |
| MODULE_LICENSE("GPL"); |
| |
| static inline int match_ip(const struct sk_buff *skb, |
| const struct ipt_ecn_info *einfo) |
| { |
| return ((skb->nh.iph->tos&IPT_ECN_IP_MASK) == einfo->ip_ect); |
| } |
| |
| static inline int match_tcp(const struct sk_buff *skb, |
| const struct ipt_ecn_info *einfo, |
| int *hotdrop) |
| { |
| struct tcphdr _tcph, *th; |
| |
| /* In practice, TCP match does this, so can't fail. But let's |
| * be good citizens. |
| */ |
| th = skb_header_pointer(skb, skb->nh.iph->ihl * 4, |
| sizeof(_tcph), &_tcph); |
| if (th == NULL) { |
| *hotdrop = 0; |
| return 0; |
| } |
| |
| if (einfo->operation & IPT_ECN_OP_MATCH_ECE) { |
| if (einfo->invert & IPT_ECN_OP_MATCH_ECE) { |
| if (th->ece == 1) |
| return 0; |
| } else { |
| if (th->ece == 0) |
| return 0; |
| } |
| } |
| |
| if (einfo->operation & IPT_ECN_OP_MATCH_CWR) { |
| if (einfo->invert & IPT_ECN_OP_MATCH_CWR) { |
| if (th->cwr == 1) |
| return 0; |
| } else { |
| if (th->cwr == 0) |
| return 0; |
| } |
| } |
| |
| return 1; |
| } |
| |
| static int match(const struct sk_buff *skb, const struct net_device *in, |
| const struct net_device *out, const void *matchinfo, |
| int offset, int *hotdrop) |
| { |
| const struct ipt_ecn_info *info = matchinfo; |
| |
| if (info->operation & IPT_ECN_OP_MATCH_IP) |
| if (!match_ip(skb, info)) |
| return 0; |
| |
| if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)) { |
| if (skb->nh.iph->protocol != IPPROTO_TCP) |
| return 0; |
| if (!match_tcp(skb, info, hotdrop)) |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static int checkentry(const char *tablename, const struct ipt_ip *ip, |
| void *matchinfo, unsigned int matchsize, |
| unsigned int hook_mask) |
| { |
| const struct ipt_ecn_info *info = matchinfo; |
| |
| if (matchsize != IPT_ALIGN(sizeof(struct ipt_ecn_info))) |
| return 0; |
| |
| if (info->operation & IPT_ECN_OP_MATCH_MASK) |
| return 0; |
| |
| if (info->invert & IPT_ECN_OP_MATCH_MASK) |
| return 0; |
| |
| if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR) |
| && ip->proto != IPPROTO_TCP) { |
| printk(KERN_WARNING "ipt_ecn: can't match TCP bits in rule for" |
| " non-tcp packets\n"); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static struct ipt_match ecn_match = { |
| .name = "ecn", |
| .match = &match, |
| .checkentry = &checkentry, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init init(void) |
| { |
| return ipt_register_match(&ecn_match); |
| } |
| |
| static void __exit fini(void) |
| { |
| ipt_unregister_match(&ecn_match); |
| } |
| |
| module_init(init); |
| module_exit(fini); |