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1275 |
phoenix |
/* Kernel module to match connection tracking information.
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* Superset of Rusty's minimalistic state match.
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* GPL (C) 2001 Marc Boucher (marc@mbsi.ca).
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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/netfilter_ipv4/ip_conntrack.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv4/ipt_conntrack.h>
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static int
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match(const struct sk_buff *skb,
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const struct net_device *in,
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const struct net_device *out,
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const void *matchinfo,
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int offset,
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const void *hdr,
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u_int16_t datalen,
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int *hotdrop)
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{
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const struct ipt_conntrack_info *sinfo = matchinfo;
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struct ip_conntrack *ct;
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enum ip_conntrack_info ctinfo;
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unsigned int statebit;
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ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo);
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#define FWINV(bool,invflg) ((bool) ^ !!(sinfo->invflags & invflg))
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if (ct)
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statebit = IPT_CONNTRACK_STATE_BIT(ctinfo);
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else
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statebit = IPT_CONNTRACK_STATE_INVALID;
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if(sinfo->flags & IPT_CONNTRACK_STATE) {
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if (ct) {
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if(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip !=
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ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip)
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statebit |= IPT_CONNTRACK_STATE_SNAT;
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if(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.ip !=
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ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.ip)
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statebit |= IPT_CONNTRACK_STATE_DNAT;
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}
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if (FWINV((statebit & sinfo->statemask) == 0, IPT_CONNTRACK_STATE))
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return 0;
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}
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if(sinfo->flags & IPT_CONNTRACK_PROTO) {
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if (!ct || FWINV(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum != sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.protonum, IPT_CONNTRACK_PROTO))
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return 0;
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}
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if(sinfo->flags & IPT_CONNTRACK_ORIGSRC) {
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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))
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return 0;
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}
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if(sinfo->flags & IPT_CONNTRACK_ORIGDST) {
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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))
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return 0;
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}
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if(sinfo->flags & IPT_CONNTRACK_REPLSRC) {
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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))
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return 0;
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}
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if(sinfo->flags & IPT_CONNTRACK_REPLDST) {
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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))
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return 0;
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}
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if(sinfo->flags & IPT_CONNTRACK_STATUS) {
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if (!ct || FWINV((ct->status & sinfo->statusmask) == 0, IPT_CONNTRACK_STATUS))
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return 0;
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}
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if(sinfo->flags & IPT_CONNTRACK_EXPIRES) {
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unsigned long expires;
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if(!ct)
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return 0;
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expires = timer_pending(&ct->timeout) ? (ct->timeout.expires - jiffies)/HZ : 0;
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if (FWINV(!(expires >= sinfo->expires_min && expires <= sinfo->expires_max), IPT_CONNTRACK_EXPIRES))
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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 int check(const char *tablename,
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const struct ipt_ip *ip,
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void *matchinfo,
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unsigned int matchsize,
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unsigned int hook_mask)
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{
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if (matchsize != IPT_ALIGN(sizeof(struct ipt_conntrack_info)))
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return 0;
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return 1;
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}
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static struct ipt_match conntrack_match
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= { { NULL, NULL }, "conntrack", &match, &check, NULL, THIS_MODULE };
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static int __init init(void)
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{
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return ipt_register_match(&conntrack_match);
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}
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static void __exit fini(void)
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{
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ipt_unregister_match(&conntrack_match);
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}
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module_init(init);
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module_exit(fini);
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MODULE_LICENSE("GPL");
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