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/*
* Copyright (c) 2010 Patrick McHardy <kaber@trash.net>
*
* 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/gfp.h>
#include <linux/skbuff.h>
#include <linux/netfilter_ipv4/ip_tables.h>
#include <linux/netfilter_ipv6/ip6_tables.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_CT.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_zones.h>
static unsigned int xt_ct_target(struct sk_buff *skb,
const struct xt_action_param *par)
{
const struct xt_ct_target_info *info = par->targinfo;
struct nf_conn *ct = info->ct;
/* Previously seen (loopback)? Ignore. */
if (skb->nfct != NULL)
return XT_CONTINUE;
atomic_inc(&ct->ct_general.use);
skb->nfct = &ct->ct_general;
skb->nfctinfo = IP_CT_NEW;
return XT_CONTINUE;
}
static u8 xt_ct_find_proto(const struct xt_tgchk_param *par)
{
if (par->family == NFPROTO_IPV4) {
const struct ipt_entry *e = par->entryinfo;
if (e->ip.invflags & IPT_INV_PROTO)
return 0;
return e->ip.proto;
} else if (par->family == NFPROTO_IPV6) {
const struct ip6t_entry *e = par->entryinfo;
if (e->ipv6.invflags & IP6T_INV_PROTO)
return 0;
return e->ipv6.proto;
} else
return 0;
}
static int xt_ct_tg_check(const struct xt_tgchk_param *par)
{
struct xt_ct_target_info *info = par->targinfo;
struct nf_conntrack_tuple t;
struct nf_conn_help *help;
struct nf_conn *ct;
int ret = 0;
u8 proto;
if (info->flags & ~(XT_CT_NOTRACK | XT_CT_USERSPACE_HELPER))
return -EOPNOTSUPP;
if (info->flags & XT_CT_NOTRACK) {
ct = nf_ct_untracked_get();
atomic_inc(&ct->ct_general.use);
goto out;
}
#ifndef CONFIG_NF_CONNTRACK_ZONES
if (info->zone)
goto err1;
#endif
ret = nf_ct_l3proto_try_module_get(par->family);
if (ret < 0)
goto err1;
memset(&t, 0, sizeof(t));
ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL);
ret = PTR_ERR(ct);
if (IS_ERR(ct))
goto err2;
ret = 0;
if ((info->ct_events || info->exp_events) &&
!nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
GFP_KERNEL))
goto err3;
if (info->flags & XT_CT_USERSPACE_HELPER) {
__set_bit(IPS_USERSPACE_HELPER_BIT, &ct->status);
} else if (info->helper[0]) {
ret = -ENOENT;
proto = xt_ct_find_proto(par);
if (!proto) {
pr_info("You must specify a L4 protocol, "
"and not use inversions on it.\n");
goto err3;
}
ret = -ENOMEM;
help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
if (help == NULL)
goto err3;
ret = -ENOENT;
help->helper = nf_conntrack_helper_try_module_get(info->helper,
par->family,
proto);
if (help->helper == NULL) {
pr_info("No such helper \"%s\"\n", info->helper);
goto err3;
}
}
__set_bit(IPS_TEMPLATE_BIT, &ct->status);
__set_bit(IPS_CONFIRMED_BIT, &ct->status);
out:
info->ct = ct;
return 0;
err3:
nf_conntrack_free(ct);
err2:
nf_ct_l3proto_module_put(par->family);
err1:
return ret;
}
static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par)
{
struct xt_ct_target_info *info = par->targinfo;
struct nf_conn *ct = info->ct;
struct nf_conn_help *help;
if (!nf_ct_is_untracked(ct)) {
help = nfct_help(ct);
if (help)
module_put(help->helper->me);
nf_ct_l3proto_module_put(par->family);
}
nf_ct_put(info->ct);
}
static struct xt_target xt_ct_tg __read_mostly = {
.name = "CT",
.family = NFPROTO_UNSPEC,
.targetsize = sizeof(struct xt_ct_target_info),
.checkentry = xt_ct_tg_check,
.destroy = xt_ct_tg_destroy,
.target = xt_ct_target,
.table = "raw",
.me = THIS_MODULE,
};
static int __init xt_ct_tg_init(void)
{
return xt_register_target(&xt_ct_tg);
}
static void __exit xt_ct_tg_exit(void)
{
xt_unregister_target(&xt_ct_tg);
}
module_init(xt_ct_tg_init);
module_exit(xt_ct_tg_exit);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Xtables: connection tracking target");
MODULE_ALIAS("ipt_CT");
MODULE_ALIAS("ip6t_CT");
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