LXR linux-old/net/ipv4/netfilter/ipt

   1/* IP tables module for matching the value of the IPv4 and TCP ECN bits
   2 *
   3 * ipt_ecn.c,v 1.3 2002/05/29 15:09:00 laforge Exp
   4 *
   5 * (C) 2002 by Harald Welte <laforge@gnumonks.org>
   6 *
   7 * This software is distributed under the terms GNU GPL v2
   8 */
   9
  10#include <linux/module.h>
  11#include <linux/skbuff.h>
  12#include <linux/tcp.h>
  13
  14#include <linux/netfilter_ipv4/ip_tables.h>
  15#include <linux/netfilter_ipv4/ipt_ecn.h>
  16
  17MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
  18MODULE_DESCRIPTION("IP tables ECN matching module");
  19MODULE_LICENSE("GPL");
  20
  21static inline int match_ip(const struct sk_buff *skb,
  22                           const struct iphdr *iph,
  23                           const struct ipt_ecn_info *einfo)
  24{
  25        return ((iph->tos&IPT_ECN_IP_MASK) == einfo->ip_ect);
  26}
  27
  28static inline int match_tcp(const struct sk_buff *skb,
  29                            const struct iphdr *iph,
  30                            const struct ipt_ecn_info *einfo)
  31{
  32        struct tcphdr *tcph = (void *)iph + iph->ihl*4;
  33
  34        if (einfo->operation & IPT_ECN_OP_MATCH_ECE) {
  35                if (einfo->invert & IPT_ECN_OP_MATCH_ECE) {
  36                        if (tcph->ece == 1)
  37                                return 0;
  38                } else {
  39                        if (tcph->ece == 0)
  40                                return 0;
  41                }
  42        }
  43
  44        if (einfo->operation & IPT_ECN_OP_MATCH_CWR) {
  45                if (einfo->invert & IPT_ECN_OP_MATCH_CWR) {
  46                        if (tcph->cwr == 1)
  47                                return 0;
  48                } else {
  49                        if (tcph->cwr == 0)
  50                                return 0;
  51                }
  52        }
  53
  54        return 1;
  55}
  56
  57static int match(const struct sk_buff *skb, const struct net_device *in,
  58                 const struct net_device *out, const void *matchinfo,
  59                 int offset, const void *hdr, u_int16_t datalen,
  60                 int *hotdrop)
  61{
  62        const struct ipt_ecn_info *info = matchinfo;
  63        const struct iphdr *iph = skb->nh.iph;
  64
  65        if (info->operation & IPT_ECN_OP_MATCH_IP)
  66                if (!match_ip(skb, iph, info))
  67                        return 0;
  68
  69        if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)) {
  70                if (iph->protocol != IPPROTO_TCP)
  71                        return 0;
  72                if (!match_tcp(skb, iph, info))
  73                        return 0;
  74        }
  75
  76        return 1;
  77}
  78
  79static int checkentry(const char *tablename, const struct ipt_ip *ip,
  80                      void *matchinfo, unsigned int matchsize,
  81                      unsigned int hook_mask)
  82{
  83        const struct ipt_ecn_info *info = matchinfo;
  84
  85        if (matchsize != IPT_ALIGN(sizeof(struct ipt_ecn_info)))
  86                return 0;
  87
  88        if (info->operation & IPT_ECN_OP_MATCH_MASK)
  89                return 0;
  90
  91        if (info->invert & IPT_ECN_OP_MATCH_MASK)
  92                return 0;
  93
  94        if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)
  95            && ip->proto != IPPROTO_TCP) {
  96                printk(KERN_WARNING "ipt_ecn: can't match TCP bits in rule for"
  97                       " non-tcp packets\n");
  98                return 0;
  99        }
 100
 101        return 1;
 102}
 103
 104static struct ipt_match ecn_match = { { NULL, NULL }, "ecn", &match,
 105                &checkentry, NULL, THIS_MODULE };
 106
 107static int __init init(void)
 108{
 109        return ipt_register_match(&ecn_match);
 110}
 111
 112static void __exit fini(void)
 113{
 114        ipt_unregister_match(&ecn_match);
 115}
 116
 117module_init(init);
 118module_exit(fini);
 119