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/*
* xt_conntrack - Netfilter module to match connection tracking
* information. (Superset of Rusty's minimalistic state match.)
*
* (C) 2001 Marc Boucher (marc@mbsi.ca).
* Copyright © CC Computer Consultants GmbH, 2007 - 2008
*
* 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.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <net/ipv6.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_conntrack.h>
#include <net/netfilter/nf_conntrack.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>");
MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
MODULE_DESCRIPTION("Xtables: connection tracking state match");
MODULE_ALIAS("ipt_conntrack");
MODULE_ALIAS("ip6t_conntrack");
static bool
conntrack_addrcmp(const union nf_inet_addr *kaddr,
const union nf_inet_addr *uaddr,
const union nf_inet_addr *umask, unsigned int l3proto)
{
if (l3proto == NFPROTO_IPV4)
return ((kaddr->ip ^ uaddr->ip) & umask->ip) == 0;
else if (l3proto == NFPROTO_IPV6)
return ipv6_masked_addr_cmp(&kaddr->in6, &umask->in6,
&uaddr->in6) == 0;
else
return false;
}
static inline bool
conntrack_mt_origsrc(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
&info->origsrc_addr, &info->origsrc_mask, family);
}
static inline bool
conntrack_mt_origdst(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.dst.u3,
&info->origdst_addr, &info->origdst_mask, family);
}
static inline bool
conntrack_mt_replsrc(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.src.u3,
&info->replsrc_addr, &info->replsrc_mask, family);
}
static inline bool
conntrack_mt_repldst(const struct nf_conn *ct,
const struct xt_conntrack_mtinfo2 *info,
u_int8_t family)
{
return conntrack_addrcmp(&ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3,
&info->repldst_addr, &info->repldst_mask, family);
}
static inline bool
ct_proto_port_check(const struct xt_conntrack_mtinfo2 *info,
const struct nf_conn *ct)
{
const struct nf_conntrack_tuple *tuple;
tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
if ((info->match_flags & XT_CONNTRACK_PROTO) &&
(nf_ct_protonum(ct) == info->l4proto) ^
!(info->invert_flags & XT_CONNTRACK_PROTO))
return false;
/* Shortcut to match all recognized protocols by using ->src.all. */
if ((info->match_flags & XT_CONNTRACK_ORIGSRC_PORT) &&
(tuple->src.u.all == info->origsrc_port) ^
!(info->invert_flags & XT_CONNTRACK_ORIGSRC_PORT))
return false;
if ((info->match_flags & XT_CONNTRACK_ORIGDST_PORT) &&
(tuple->dst.u.all == info->origdst_port) ^
!(info->invert_flags & XT_CONNTRACK_ORIGDST_PORT))
return false;
tuple = &ct->tuplehash[IP_CT_DIR_REPLY].tuple;
if ((info->match_flags & XT_CONNTRACK_REPLSRC_PORT) &&
(tuple->src.u.all == info->replsrc_port) ^
!(info->invert_flags & XT_CONNTRACK_REPLSRC_PORT))
return false;
if ((info->match_flags & XT_CONNTRACK_REPLDST_PORT) &&
(tuple->dst.u.all == info->repldst_port) ^
!(info->invert_flags & XT_CONNTRACK_REPLDST_PORT))
return false;
return true;
}
static bool
conntrack_mt(const struct sk_buff *skb, struct xt_action_param *par,
u16 state_mask, u16 status_mask)
{
const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
enum ip_conntrack_info ctinfo;
const struct nf_conn *ct;
unsigned int statebit;
ct = nf_ct_get(skb, &ctinfo);
if (ct) {
if (nf_ct_is_untracked(ct))
statebit = XT_CONNTRACK_STATE_UNTRACKED;
else
statebit = XT_CONNTRACK_STATE_BIT(ctinfo);
} else
statebit = XT_CONNTRACK_STATE_INVALID;
if (info->match_flags & XT_CONNTRACK_STATE) {
if (ct != NULL) {
if (test_bit(IPS_SRC_NAT_BIT, &ct->status))
statebit |= XT_CONNTRACK_STATE_SNAT;
if (test_bit(IPS_DST_NAT_BIT, &ct->status))
statebit |= XT_CONNTRACK_STATE_DNAT;
}
if (!!(state_mask & statebit) ^
!(info->invert_flags & XT_CONNTRACK_STATE))
return false;
}
if (ct == NULL)
return info->match_flags & XT_CONNTRACK_STATE;
if ((info->match_flags & XT_CONNTRACK_DIRECTION) &&
(CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) ^
!!(info->invert_flags & XT_CONNTRACK_DIRECTION))
return false;
if (info->match_flags & XT_CONNTRACK_ORIGSRC)
if (conntrack_mt_origsrc(ct, info, par->family) ^
!(info->invert_flags & XT_CONNTRACK_ORIGSRC))
return false;
if (info->match_flags & XT_CONNTRACK_ORIGDST)
if (conntrack_mt_origdst(ct, info, par->family) ^
!(info->invert_flags & XT_CONNTRACK_ORIGDST))
return false;
if (info->match_flags & XT_CONNTRACK_REPLSRC)
if (conntrack_mt_replsrc(ct, info, par->family) ^
!(info->invert_flags & XT_CONNTRACK_REPLSRC))
return false;
if (info->match_flags & XT_CONNTRACK_REPLDST)
if (conntrack_mt_repldst(ct, info, par->family) ^
!(info->invert_flags & XT_CONNTRACK_REPLDST))
return false;
if (!ct_proto_port_check(info, ct))
return false;
if ((info->match_flags & XT_CONNTRACK_STATUS) &&
(!!(status_mask & ct->status) ^
!(info->invert_flags & XT_CONNTRACK_STATUS)))
return false;
if (info->match_flags & XT_CONNTRACK_EXPIRES) {
unsigned long expires = 0;
if (timer_pending(&ct->timeout))
expires = (ct->timeout.expires - jiffies) / HZ;
if ((expires >= info->expires_min &&
expires <= info->expires_max) ^
!(info->invert_flags & XT_CONNTRACK_EXPIRES))
return false;
}
return true;
}
static bool
conntrack_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_conntrack_mtinfo1 *info = par->matchinfo;
return conntrack_mt(skb, par, info->state_mask, info->status_mask);
}
static bool
conntrack_mt_v2(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_conntrack_mtinfo2 *info = par->matchinfo;
return conntrack_mt(skb, par, info->state_mask, info->status_mask);
}
static int conntrack_mt_check(const struct xt_mtchk_param *par)
{
int ret;
ret = nf_ct_l3proto_try_module_get(par->family);
if (ret < 0)
pr_info("cannot load conntrack support for proto=%u\n",
par->family);
return ret;
}
static void conntrack_mt_destroy(const struct xt_mtdtor_param *par)
{
nf_ct_l3proto_module_put(par->family);
}
static struct xt_match conntrack_mt_reg[] __read_mostly = {
{
.name = "conntrack",
.revision = 1,
.family = NFPROTO_UNSPEC,
.matchsize = sizeof(struct xt_conntrack_mtinfo1),
.match = conntrack_mt_v1,
.checkentry = conntrack_mt_check,
.destroy = conntrack_mt_destroy,
.me = THIS_MODULE,
},
{
.name = "conntrack",
.revision = 2,
.family = NFPROTO_UNSPEC,
.matchsize = sizeof(struct xt_conntrack_mtinfo2),
.match = conntrack_mt_v2,
.checkentry = conntrack_mt_check,
.destroy = conntrack_mt_destroy,
.me = THIS_MODULE,
},
};
static int __init conntrack_mt_init(void)
{
return xt_register_matches(conntrack_mt_reg,
ARRAY_SIZE(conntrack_mt_reg));
}
static void __exit conntrack_mt_exit(void)
{
xt_unregister_matches(conntrack_mt_reg, ARRAY_SIZE(conntrack_mt_reg));
}
module_init(conntrack_mt_init);
module_exit(conntrack_mt_exit);
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