213 lines
5.7 KiB
C
213 lines
5.7 KiB
C
/* Kernel module to match connection tracking information.
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* Superset of Rusty's minimalistic state match.
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*
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* (C) 2001 Marc Boucher (marc@mbsi.ca).
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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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/x_tables.h>
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#include <linux/netfilter/xt_conntrack.h>
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#include <net/netfilter/nf_conntrack.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
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MODULE_DESCRIPTION("iptables connection tracking match module");
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MODULE_ALIAS("ipt_conntrack");
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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 struct xt_match *match,
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const void *matchinfo,
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int offset,
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unsigned int protoff,
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int *hotdrop)
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{
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const struct xt_conntrack_info *sinfo = matchinfo;
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struct nf_conn *ct;
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enum ip_conntrack_info ctinfo;
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unsigned int statebit;
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ct = nf_ct_get((struct sk_buff *)skb, &ctinfo);
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#define FWINV(bool,invflg) ((bool) ^ !!(sinfo->invflags & invflg))
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if (ct == &nf_conntrack_untracked)
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statebit = XT_CONNTRACK_STATE_UNTRACKED;
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else if (ct)
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statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
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else
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statebit = XT_CONNTRACK_STATE_INVALID;
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if (sinfo->flags & XT_CONNTRACK_STATE) {
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if (ct) {
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if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
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statebit |= XT_CONNTRACK_STATE_SNAT;
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if (test_bit(IPS_DST_NAT_BIT, &ct->status))
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statebit |= XT_CONNTRACK_STATE_DNAT;
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}
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if (FWINV((statebit & sinfo->statemask) == 0,
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XT_CONNTRACK_STATE))
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return 0;
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}
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if (ct == NULL) {
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if (sinfo->flags & ~XT_CONNTRACK_STATE)
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return 0;
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return 1;
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}
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if (sinfo->flags & XT_CONNTRACK_PROTO &&
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FWINV(ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.protonum !=
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sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.protonum,
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XT_CONNTRACK_PROTO))
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return 0;
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if (sinfo->flags & XT_CONNTRACK_ORIGSRC &&
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FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip &
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sinfo->sipmsk[IP_CT_DIR_ORIGINAL].s_addr) !=
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sinfo->tuple[IP_CT_DIR_ORIGINAL].src.ip,
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XT_CONNTRACK_ORIGSRC))
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return 0;
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if (sinfo->flags & XT_CONNTRACK_ORIGDST &&
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FWINV((ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3.ip &
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sinfo->dipmsk[IP_CT_DIR_ORIGINAL].s_addr) !=
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sinfo->tuple[IP_CT_DIR_ORIGINAL].dst.ip,
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XT_CONNTRACK_ORIGDST))
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return 0;
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if (sinfo->flags & XT_CONNTRACK_REPLSRC &&
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FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3.ip &
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sinfo->sipmsk[IP_CT_DIR_REPLY].s_addr) !=
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sinfo->tuple[IP_CT_DIR_REPLY].src.ip,
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XT_CONNTRACK_REPLSRC))
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return 0;
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if (sinfo->flags & XT_CONNTRACK_REPLDST &&
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FWINV((ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip &
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sinfo->dipmsk[IP_CT_DIR_REPLY].s_addr) !=
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sinfo->tuple[IP_CT_DIR_REPLY].dst.ip,
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XT_CONNTRACK_REPLDST))
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return 0;
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if (sinfo->flags & XT_CONNTRACK_STATUS &&
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FWINV((ct->status & sinfo->statusmask) == 0,
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XT_CONNTRACK_STATUS))
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return 0;
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if(sinfo->flags & XT_CONNTRACK_EXPIRES) {
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unsigned long expires = timer_pending(&ct->timeout) ?
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(ct->timeout.expires - jiffies)/HZ : 0;
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if (FWINV(!(expires >= sinfo->expires_min &&
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expires <= sinfo->expires_max),
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XT_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
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checkentry(const char *tablename,
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const void *ip,
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const struct xt_match *match,
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void *matchinfo,
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unsigned int hook_mask)
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{
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if (nf_ct_l3proto_try_module_get(match->family) < 0) {
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printk(KERN_WARNING "can't load conntrack support for "
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"proto=%d\n", match->family);
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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 void destroy(const struct xt_match *match, void *matchinfo)
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{
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nf_ct_l3proto_module_put(match->family);
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}
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#ifdef CONFIG_COMPAT
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struct compat_xt_conntrack_info
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{
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compat_uint_t statemask;
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compat_uint_t statusmask;
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struct ip_conntrack_old_tuple tuple[IP_CT_DIR_MAX];
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struct in_addr sipmsk[IP_CT_DIR_MAX];
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struct in_addr dipmsk[IP_CT_DIR_MAX];
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compat_ulong_t expires_min;
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compat_ulong_t expires_max;
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u_int8_t flags;
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u_int8_t invflags;
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};
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static void compat_from_user(void *dst, void *src)
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{
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struct compat_xt_conntrack_info *cm = src;
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struct xt_conntrack_info m = {
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.statemask = cm->statemask,
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.statusmask = cm->statusmask,
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.expires_min = cm->expires_min,
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.expires_max = cm->expires_max,
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.flags = cm->flags,
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.invflags = cm->invflags,
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};
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memcpy(m.tuple, cm->tuple, sizeof(m.tuple));
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memcpy(m.sipmsk, cm->sipmsk, sizeof(m.sipmsk));
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memcpy(m.dipmsk, cm->dipmsk, sizeof(m.dipmsk));
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memcpy(dst, &m, sizeof(m));
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}
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static int compat_to_user(void __user *dst, void *src)
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{
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struct xt_conntrack_info *m = src;
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struct compat_xt_conntrack_info cm = {
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.statemask = m->statemask,
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.statusmask = m->statusmask,
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.expires_min = m->expires_min,
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.expires_max = m->expires_max,
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.flags = m->flags,
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.invflags = m->invflags,
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};
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memcpy(cm.tuple, m->tuple, sizeof(cm.tuple));
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memcpy(cm.sipmsk, m->sipmsk, sizeof(cm.sipmsk));
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memcpy(cm.dipmsk, m->dipmsk, sizeof(cm.dipmsk));
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return copy_to_user(dst, &cm, sizeof(cm)) ? -EFAULT : 0;
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}
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#endif
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static struct xt_match conntrack_match = {
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.name = "conntrack",
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.match = match,
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.checkentry = checkentry,
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.destroy = destroy,
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.matchsize = sizeof(struct xt_conntrack_info),
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#ifdef CONFIG_COMPAT
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.compatsize = sizeof(struct compat_xt_conntrack_info),
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.compat_from_user = compat_from_user,
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.compat_to_user = compat_to_user,
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#endif
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.family = AF_INET,
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.me = THIS_MODULE,
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};
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static int __init xt_conntrack_init(void)
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{
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return xt_register_match(&conntrack_match);
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}
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static void __exit xt_conntrack_fini(void)
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{
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xt_unregister_match(&conntrack_match);
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}
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module_init(xt_conntrack_init);
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module_exit(xt_conntrack_fini);
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