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/* Kernel module to match connection tracking information.
* Superset of Rusty's minimalistic state match.
* GPL (C) 2001 Marc Boucher (marc@mbsi.ca).
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter_ipv4/ip_conntrack.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv4/ipt_conntrack.h>
static int
match(const struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
const void *matchinfo,
int offset,
const void *hdr,
u_int16_t datalen,
int *hotdrop)
{
const struct ipt_conntrack_info *sinfo = matchinfo;
struct ip_conntrack *ct;
enum ip_conntrack_info ctinfo;
unsigned int statebit;
ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo);
#define FWINV(bool,invflg) ((bool) ^ !!(sinfo->invflags & invflg))
statebit = ct ? IPT_CONNTRACK_STATE_INVALID : IPT_CONNTRACK_STATE_BIT(ctinfo);
if(sinfo->flags & IPT_CONNTRACK_STATE) {
if (ct) {
if(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip !=
ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip)
statebit |= IPT_CONNTRACK_STATE_SNAT;
if(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip !=
ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip)
statebit |= IPT_CONNTRACK_STATE_DNAT;
}
if (FWINV((statebit & sinfo->statemask) == 0, IPT_CONNTRACK_STATE))
return 0;
}
if(sinfo->flags & IPT_CONNTRACK_PROTO) {
if (!ct || FWINV(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum != sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.protonum, IPT_CONNTRACK_PROTO))
return 0;
}
if(sinfo->flags & IPT_CONNTRACK_ORIGSRC) {
if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip&sinfo->sipmsk[IP_CT_DIR_ORIGINAL].s_addr) != sinfo->tuple[IP_CT_DIR_ORIGINAL].src.ip, IPT_CONNTRACK_ORIGSRC))
return 0;
}
if(sinfo->flags & IPT_CONNTRACK_ORIGDST) {
if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip&sinfo->dipmsk[IP_CT_DIR_ORIGINAL].s_addr) != sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.ip, IPT_CONNTRACK_ORIGDST))
return 0;
}
if(sinfo->flags & IPT_CONNTRACK_REPLSRC) {
if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip&sinfo->sipmsk[IP_CT_DIR_REPLY].s_addr) != sinfo->tuple[IP_CT_DIR_REPLY].src.ip, IPT_CONNTRACK_REPLSRC))
return 0;
}
if(sinfo->flags & IPT_CONNTRACK_REPLDST) {
if (!ct || FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip&sinfo->dipmsk[IP_CT_DIR_REPLY].s_addr) != sinfo->tuple[IP_CT_DIR_REPLY].dst.ip, IPT_CONNTRACK_REPLDST))
return 0;
}
if(sinfo->flags & IPT_CONNTRACK_STATUS) {
if (!ct || FWINV((ct->status & sinfo->statusmask) == 0, IPT_CONNTRACK_STATUS))
return 0;
}
if(sinfo->flags & IPT_CONNTRACK_EXPIRES) {
unsigned long expires;
if(!ct)
return 0;
expires = timer_pending(&ct->timeout) ? (ct->timeout.expires - jiffies)/HZ : 0;
if (FWINV(!(expires >= sinfo->expires_min && expires <= sinfo->expires_max), IPT_CONNTRACK_EXPIRES))
return 0;
}
return 1;
}
static int check(const char *tablename,
const struct ipt_ip *ip,
void *matchinfo,
unsigned int matchsize,
unsigned int hook_mask)
{
if (matchsize != IPT_ALIGN(sizeof(struct ipt_conntrack_info)))
return 0;
return 1;
}
static struct ipt_match conntrack_match
= { { NULL, NULL }, "conntrack", &match, &check, NULL, THIS_MODULE };
static int __init init(void)
{
/* NULL if ip_conntrack not a module */
if (ip_conntrack_module)
__MOD_INC_USE_COUNT(ip_conntrack_module);
return ipt_register_match(&conntrack_match);
}
static void __exit fini(void)
{
ipt_unregister_match(&conntrack_match);
if (ip_conntrack_module)
__MOD_DEC_USE_COUNT(ip_conntrack_module);
}
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
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