| /* Kernel module to match connection tracking information. |
| * Superset of Rusty's minimalistic state match. |
| * |
| * (C) 2001 Marc Boucher (marc@mbsi.ca). |
| * |
| * 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/netfilter_ipv4/ip_conntrack.h> |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <linux/netfilter_ipv4/ipt_conntrack.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>"); |
| MODULE_DESCRIPTION("iptables connection tracking match module"); |
| |
| 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_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)) |
| |
| if (ct == &ip_conntrack_untracked) |
| statebit = IPT_CONNTRACK_STATE_UNTRACKED; |
| else if (ct) |
| statebit = IPT_CONNTRACK_STATE_BIT(ctinfo); |
| else |
| statebit = IPT_CONNTRACK_STATE_INVALID; |
| |
| 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 = { |
| .name = "conntrack", |
| .match = &match, |
| .checkentry = &check, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init init(void) |
| { |
| need_ip_conntrack(); |
| return ipt_register_match(&conntrack_match); |
| } |
| |
| static void __exit fini(void) |
| { |
| ipt_unregister_match(&conntrack_match); |
| } |
| |
| module_init(init); |
| module_exit(fini); |