netfilter: xtables: add CT target

Add a new target for the raw table, which can be used to specify conntrack
parameters for specific connections, f.i. the conntrack helper.

The target attaches a "template" connection tracking entry to the skb, which
is used by the conntrack core when initializing a new conntrack.

Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Patrick McHardy 2010-02-03 17:17:06 +01:00
Родитель b2a15a604d
Коммит 84f3bb9ae9
7 изменённых файлов: 211 добавлений и 0 удалений

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@ -6,6 +6,7 @@ header-y += nfnetlink_queue.h
header-y += xt_CLASSIFY.h
header-y += xt_CONNMARK.h
header-y += xt_CONNSECMARK.h
header-y += xt_CT.h
header-y += xt_DSCP.h
header-y += xt_LED.h
header-y += xt_MARK.h

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@ -0,0 +1,17 @@
#ifndef _XT_CT_H
#define _XT_CT_H
#define XT_CT_NOTRACK 0x1
struct xt_ct_target_info {
u_int16_t flags;
u_int16_t __unused;
u_int32_t ct_events;
u_int32_t exp_events;
char helper[16];
/* Used internally by the kernel */
struct nf_conn *ct __attribute__((aligned(8)));
};
#endif /* _XT_CT_H */

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@ -42,6 +42,9 @@ struct nf_conntrack_helper {
extern struct nf_conntrack_helper *
__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum);
extern struct nf_conntrack_helper *
nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum);
extern int nf_conntrack_helper_register(struct nf_conntrack_helper *);
extern void nf_conntrack_helper_unregister(struct nf_conntrack_helper *);

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@ -341,6 +341,18 @@ config NETFILTER_XT_TARGET_CONNSECMARK
To compile it as a module, choose M here. If unsure, say N.
config NETFILTER_XT_TARGET_CT
tristate '"CT" target support'
depends on NF_CONNTRACK
depends on IP_NF_RAW || IP6_NF_RAW
depends on NETFILTER_ADVANCED
help
This options adds a `CT' target, which allows to specify initial
connection tracking parameters like events to be delivered and
the helper to be used.
To compile it as a module, choose M here. If unsure, say N.
config NETFILTER_XT_TARGET_DSCP
tristate '"DSCP" and "TOS" target support'
depends on IP_NF_MANGLE || IP6_NF_MANGLE

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@ -44,6 +44,7 @@ obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o
obj-$(CONFIG_NETFILTER_XT_TARGET_CLASSIFY) += xt_CLASSIFY.o
obj-$(CONFIG_NETFILTER_XT_TARGET_CONNMARK) += xt_CONNMARK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_CT) += xt_CT.o
obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o
obj-$(CONFIG_NETFILTER_XT_TARGET_HL) += xt_HL.o
obj-$(CONFIG_NETFILTER_XT_TARGET_LED) += xt_LED.o

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@ -83,6 +83,25 @@ __nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
}
EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
struct nf_conntrack_helper *
nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
{
struct nf_conntrack_helper *h;
h = __nf_conntrack_helper_find(name, l3num, protonum);
#ifdef CONFIG_MODULES
if (h == NULL) {
if (request_module("nfct-helper-%s", name) == 0)
h = __nf_conntrack_helper_find(name, l3num, protonum);
}
#endif
if (h != NULL && !try_module_get(h->me))
h = NULL;
return h;
}
EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
{
struct nf_conn_help *help;

158
net/netfilter/xt_CT.c Normal file
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@ -0,0 +1,158 @@
/*
* 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.
*/
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/selinux.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>
static unsigned int xt_ct_target(struct sk_buff *skb,
const struct xt_target_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 == AF_INET) {
const struct ipt_entry *e = par->entryinfo;
if (e->ip.invflags & IPT_INV_PROTO)
return 0;
return e->ip.proto;
} else if (par->family == AF_INET6) {
const struct ip6t_entry *e = par->entryinfo;
if (e->ipv6.invflags & IP6T_INV_PROTO)
return 0;
return e->ipv6.proto;
} else
return 0;
}
static bool 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;
u8 proto;
if (info->flags & ~XT_CT_NOTRACK)
return false;
if (info->flags & XT_CT_NOTRACK) {
ct = &nf_conntrack_untracked;
atomic_inc(&ct->ct_general.use);
goto out;
}
if (nf_ct_l3proto_try_module_get(par->family) < 0)
goto err1;
memset(&t, 0, sizeof(t));
ct = nf_conntrack_alloc(par->net, &t, &t, GFP_KERNEL);
if (IS_ERR(ct))
goto err2;
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->helper[0]) {
proto = xt_ct_find_proto(par);
if (!proto)
goto err3;
help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
if (help == NULL)
goto err3;
help->helper = nf_conntrack_helper_try_module_get(info->helper,
par->family,
proto);
if (help->helper == NULL)
goto err3;
}
__set_bit(IPS_TEMPLATE_BIT, &ct->status);
__set_bit(IPS_CONFIRMED_BIT, &ct->status);
out:
info->ct = ct;
return true;
err3:
nf_conntrack_free(ct);
err2:
nf_ct_l3proto_module_put(par->family);
err1:
return false;
}
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 (ct != &nf_conntrack_untracked) {
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 = XT_ALIGN(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");