Commit 0902b469 authored by Luciano Coelho's avatar Luciano Coelho Committed by Patrick McHardy
Browse files

netfilter: xtables: idletimer target implementation 



This patch implements an idletimer Xtables target that can be used to
identify when interfaces have been idle for a certain period of time.

Timers are identified by labels and are created when a rule is set with a new
label.  The rules also take a timeout value (in seconds) as an option.  If
more than one rule uses the same timer label, the timer will be restarted
whenever any of the rules get a hit.

One entry for each timer is created in sysfs.  This attribute contains the
timer remaining for the timer to expire.  The attributes are located under
the xt_idletimer class:

/sys/class/xt_idletimer/timers/<label>

When the timer expires, the target module sends a sysfs notification to the
userspace, which can then decide what to do (eg. disconnect to save power).

Cc: Timo Teras <timo.teras@iki.fi>
Signed-off-by: default avatarLuciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: default avatarPatrick McHardy <kaber@trash.net>
parent d73f33b1

include/linux/netfilter/Kbuild

+1 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ header-y += xt_CONNMARK.h 
header-y += xt_CONNSECMARK.h

header-y += xt_CT.h

header-y += xt_DSCP.h

header-y += xt_IDLETIMER.h

header-y += xt_LED.h

header-y += xt_MARK.h

header-y += xt_NFLOG.h

include/linux/netfilter/xt_IDLETIMER.h

0 → 100644
+45 −0
Original line number Diff line number Diff line 
/*

 * linux/include/linux/netfilter/xt_IDLETIMER.h

 *

 * Header file for Xtables timer target module.

 *

 * Copyright (C) 2004, 2010 Nokia Corporation

 * Written by Timo Teras <ext-timo.teras@nokia.com>

 *

 * Converted to x_tables and forward-ported to 2.6.34

 * by Luciano Coelho <luciano.coelho@nokia.com>

 *

 * Contact: Luciano Coelho <luciano.coelho@nokia.com>

 *

 * 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.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA

 * 02110-1301 USA

 */



#ifndef _XT_IDLETIMER_H

#define _XT_IDLETIMER_H



#include <linux/types.h>



#define MAX_IDLETIMER_LABEL_SIZE 28



struct idletimer_tg_info {

	__u32 timeout;



	char label[MAX_IDLETIMER_LABEL_SIZE];



	/* for kernel module internal use only */

	struct idletimer_tg *timer __attribute((aligned(8)));

};



#endif

net/netfilter/Kconfig

+12 −0
Original line number Diff line number Diff line
@@ -424,6 +424,18 @@ config NETFILTER_XT_TARGET_HL 
	since you can easily create immortal packets that loop

	forever on the network.



config NETFILTER_XT_TARGET_IDLETIMER

	tristate  "IDLETIMER target support"

	depends on NETFILTER_ADVANCED

	help



	  This option adds the `IDLETIMER' target.  Each matching packet

	  resets the timer associated with label specified when the rule is

	  added.  When the timer expires, it triggers a sysfs notification.

	  The remaining time for expiration can be read via sysfs.



	  To compile it as a module, choose M here.  If unsure, say N.



config NETFILTER_XT_TARGET_LED

	tristate '"LED" target support'

	depends on LEDS_CLASS && LEDS_TRIGGERS

net/netfilter/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -61,6 +61,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_TCPMSS) += xt_TCPMSS.o 
obj-$(CONFIG_NETFILTER_XT_TARGET_TCPOPTSTRIP) += xt_TCPOPTSTRIP.o

obj-$(CONFIG_NETFILTER_XT_TARGET_TEE) += xt_TEE.o

obj-$(CONFIG_NETFILTER_XT_TARGET_TRACE) += xt_TRACE.o

obj-$(CONFIG_NETFILTER_XT_TARGET_IDLETIMER) += xt_IDLETIMER.o



# matches

obj-$(CONFIG_NETFILTER_XT_MATCH_CLUSTER) += xt_cluster.o

net/netfilter/xt_IDLETIMER.c

0 → 100644
+314 −0
Original line number Diff line number Diff line 
/*

 * linux/net/netfilter/xt_IDLETIMER.c

 *

 * Netfilter module to trigger a timer when packet matches.

 * After timer expires a kevent will be sent.

 *

 * Copyright (C) 2004, 2010 Nokia Corporation

 * Written by Timo Teras <ext-timo.teras@nokia.com>

 *

 * Converted to x_tables and reworked for upstream inclusion

 * by Luciano Coelho <luciano.coelho@nokia.com>

 *

 * Contact: Luciano Coelho <luciano.coelho@nokia.com>

 *

 * 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.

 *

 * This program is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA

 * 02110-1301 USA

 */



#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt



#include <linux/module.h>

#include <linux/timer.h>

#include <linux/list.h>

#include <linux/mutex.h>

#include <linux/netfilter.h>

#include <linux/netfilter/x_tables.h>

#include <linux/netfilter/xt_IDLETIMER.h>

#include <linux/kobject.h>

#include <linux/workqueue.h>

#include <linux/sysfs.h>



struct idletimer_tg_attr {

	struct attribute attr;

	ssize_t	(*show)(struct kobject *kobj,

			struct attribute *attr, char *buf);

};



struct idletimer_tg {

	struct list_head entry;

	struct timer_list timer;

	struct work_struct work;



	struct kobject *kobj;

	struct idletimer_tg_attr attr;



	unsigned int refcnt;

};



static LIST_HEAD(idletimer_tg_list);

static DEFINE_MUTEX(list_mutex);



static struct kobject *idletimer_tg_kobj;



static

struct idletimer_tg *__idletimer_tg_find_by_label(const char *label)

{

	struct idletimer_tg *entry;



	BUG_ON(!label);



	list_for_each_entry(entry, &idletimer_tg_list, entry) {

		if (!strcmp(label, entry->attr.attr.name))

			return entry;

	}



	return NULL;

}



static ssize_t idletimer_tg_show(struct kobject *kobj, struct attribute *attr,

				 char *buf)

{

	struct idletimer_tg *timer;

	unsigned long expires = 0;



	mutex_lock(&list_mutex);



	timer =	__idletimer_tg_find_by_label(attr->name);

	if (timer)

		expires = timer->timer.expires;



	mutex_unlock(&list_mutex);



	if (time_after(expires, jiffies))

		return sprintf(buf, "%u\n",

			       jiffies_to_msecs(expires - jiffies) / 1000);



	return sprintf(buf, "0\n");

}



static void idletimer_tg_work(struct work_struct *work)

{

	struct idletimer_tg *timer = container_of(work, struct idletimer_tg,

						  work);



	sysfs_notify(idletimer_tg_kobj, NULL, timer->attr.attr.name);

}



static void idletimer_tg_expired(unsigned long data)

{

	struct idletimer_tg *timer = (struct idletimer_tg *) data;



	pr_debug("timer %s expired\n", timer->attr.attr.name);



	schedule_work(&timer->work);

}



static int idletimer_tg_create(struct idletimer_tg_info *info)

{

	int ret;



	info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL);

	if (!info->timer) {

		pr_debug("couldn't alloc timer\n");

		ret = -ENOMEM;

		goto out;

	}



	info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);

	if (!info->timer->attr.attr.name) {

		pr_debug("couldn't alloc attribute name\n");

		ret = -ENOMEM;

		goto out_free_timer;

	}

	info->timer->attr.attr.mode = S_IRUGO;

	info->timer->attr.show = idletimer_tg_show;



	ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr);

	if (ret < 0) {

		pr_debug("couldn't add file to sysfs");

		goto out_free_attr;

	}



	list_add(&info->timer->entry, &idletimer_tg_list);



	setup_timer(&info->timer->timer, idletimer_tg_expired,

		    (unsigned long) info->timer);

	info->timer->refcnt = 1;



	mod_timer(&info->timer->timer,

		  msecs_to_jiffies(info->timeout * 1000) + jiffies);



	INIT_WORK(&info->timer->work, idletimer_tg_work);



	return 0;



out_free_attr:

	kfree(info->timer->attr.attr.name);

out_free_timer:

	kfree(info->timer);

out:

	return ret;

}



/*

 * The actual xt_tables plugin.

 */

static unsigned int idletimer_tg_target(struct sk_buff *skb,

					 const struct xt_action_param *par)

{

	const struct idletimer_tg_info *info = par->targinfo;



	pr_debug("resetting timer %s, timeout period %u\n",

		 info->label, info->timeout);



	BUG_ON(!info->timer);



	mod_timer(&info->timer->timer,

		  msecs_to_jiffies(info->timeout * 1000) + jiffies);



	return XT_CONTINUE;

}



static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)

{

	struct idletimer_tg_info *info = par->targinfo;

	int ret;



	pr_debug("checkentry targinfo%s\n", info->label);



	if (info->timeout == 0) {

		pr_debug("timeout value is zero\n");

		return -EINVAL;

	}



	if (info->label[0] == '\0' ||

	    strnlen(info->label,

		    MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) {

		pr_debug("label is empty or not nul-terminated\n");

		return -EINVAL;

	}



	mutex_lock(&list_mutex);



	info->timer = __idletimer_tg_find_by_label(info->label);

	if (info->timer) {

		info->timer->refcnt++;

		mod_timer(&info->timer->timer,

			  msecs_to_jiffies(info->timeout * 1000) + jiffies);



		pr_debug("increased refcnt of timer %s to %u\n",

			 info->label, info->timer->refcnt);

	} else {

		ret = idletimer_tg_create(info);

		if (ret < 0) {

			pr_debug("failed to create timer\n");

			mutex_unlock(&list_mutex);

			return ret;

		}

	}



	mutex_unlock(&list_mutex);

	return 0;

}



static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)

{

	const struct idletimer_tg_info *info = par->targinfo;



	pr_debug("destroy targinfo %s\n", info->label);



	mutex_lock(&list_mutex);



	if (--info->timer->refcnt == 0) {

		pr_debug("deleting timer %s\n", info->label);



		list_del(&info->timer->entry);

		del_timer_sync(&info->timer->timer);

		sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);

		kfree(info->timer->attr.attr.name);

		kfree(info->timer);

	} else {

		pr_debug("decreased refcnt of timer %s to %u\n",

			 info->label, info->timer->refcnt);

	}



	mutex_unlock(&list_mutex);

}



static struct xt_target idletimer_tg __read_mostly = {

	.name		= "IDLETIMER",

	.family		= NFPROTO_UNSPEC,

	.target		= idletimer_tg_target,

	.targetsize     = sizeof(struct idletimer_tg_info),

	.checkentry	= idletimer_tg_checkentry,

	.destroy        = idletimer_tg_destroy,

	.me		= THIS_MODULE,

};



static struct class *idletimer_tg_class;



static struct device *idletimer_tg_device;



static int __init idletimer_tg_init(void)

{

	int err;



	idletimer_tg_class = class_create(THIS_MODULE, "xt_idletimer");

	err = PTR_ERR(idletimer_tg_class);

	if (IS_ERR(idletimer_tg_class)) {

		pr_debug("couldn't register device class\n");

		goto out;

	}



	idletimer_tg_device = device_create(idletimer_tg_class, NULL,

					    MKDEV(0, 0), NULL, "timers");

	err = PTR_ERR(idletimer_tg_device);

	if (IS_ERR(idletimer_tg_device)) {

		pr_debug("couldn't register system device\n");

		goto out_class;

	}



	idletimer_tg_kobj = &idletimer_tg_device->kobj;



	err =  xt_register_target(&idletimer_tg);

	if (err < 0) {

		pr_debug("couldn't register xt target\n");

		goto out_dev;

	}



	return 0;

out_dev:

	device_destroy(idletimer_tg_class, MKDEV(0, 0));

out_class:

	class_destroy(idletimer_tg_class);

out:

	return err;

}



static void __exit idletimer_tg_exit(void)

{

	xt_unregister_target(&idletimer_tg);



	device_destroy(idletimer_tg_class, MKDEV(0, 0));

	class_destroy(idletimer_tg_class);

}



module_init(idletimer_tg_init);

module_exit(idletimer_tg_exit);



MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>");

MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>");

MODULE_DESCRIPTION("Xtables: idle time monitor");

MODULE_LICENSE("GPL v2");

CRA Git | Maintained and supported by SUSTech CRA and CCSE