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Commit 114513c1 authored by Bhavya Sokke Mallikarjunappa's avatar Bhavya Sokke Mallikarjunappa Committed by Susheel Yadagiri
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netfilter: xtables: hardidletimer target implementation 



This patch implements a hardidletimer 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_hardidletimer/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)

Compared to xt_IDLETIMER, xt_HARDIDLETIMER can send notifications when CPU
is in suspend too, to notify the timer expiry

Change-Id: I1723d44e02df864d63da7550766ea7d763076de2
Signed-off-by: default avatarBhavya Sokke Mallikarjunappa <bsokke@codeaurora.org>
parent 84099f52

include/uapi/linux/netfilter/xt_HARDIDLETIMER.h

0 → 100644
+55 −0
Original line number Diff line number Diff line 
/*

 * linux/include/linux/netfilter/xt_HARDIDLETIMER.h

 *

 * Header file for Xtables timer target module.

 *

 * Copyright (c) 2014, The Linux Foundation. All rights reserved.

 *

 * 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_HARDIDLETIMER_H

#define _XT_HARDIDLETIMER_H



#include <linux/types.h>



#define MAX_HARDIDLETIMER_LABEL_SIZE 28

#define NLMSG_MAX_SIZE 64



#define NL_EVENT_TYPE_INACTIVE 0

#define NL_EVENT_TYPE_ACTIVE 1



struct hardidletimer_tg_info {

	__u32 timeout;



	char label[MAX_HARDIDLETIMER_LABEL_SIZE];



	/* Use netlink messages for notification in addition to sysfs */

	__u8 send_nl_msg;



	/* for kernel module internal use only */

	struct hardidletimer_tg *timer __attribute__((aligned(8)));

};



#endif

net/netfilter/Kconfig

+14 −0
Original line number Diff line number Diff line
@@ -730,6 +730,20 @@ config NETFILTER_XT_TARGET_IDLETIMER 


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



config NETFILTER_XT_TARGET_HARDIDLETIMER

	tristate  "HARDIDLETIMER target support"

	depends on NETFILTER_ADVANCED

	help



	  This option adds the `HARDIDLETIMER' 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.

          Compared to IDLETIMER HARDIDLETIMER will send notification when

          CPU in suspend too.



	  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
@@ -121,6 +121,7 @@ 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

obj-$(CONFIG_NETFILTER_XT_TARGET_HARDIDLETIMER) += xt_HARDIDLETIMER.o



# matches

obj-$(CONFIG_NETFILTER_XT_MATCH_ADDRTYPE) += xt_addrtype.o

net/netfilter/xt_HARDIDLETIMER.c

0 → 100644
+380 −0
Original line number Diff line number Diff line 
/*

 * linux/net/netfilter/xt_HARDIDLETIMER.c

 *

 * Netfilter module to trigger a timer when packet matches.

 * After timer expires a kevent will be sent.

 *

 * Copyright (c) 2014, The Linux Foundation. All rights reserved.

 *

 * 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/alarmtimer.h>

#include <linux/list.h>

#include <linux/mutex.h>

#include <linux/netfilter.h>

#include <linux/netfilter/x_tables.h>

#include <linux/netfilter/xt_HARDIDLETIMER.h>

#include <linux/kdev_t.h>

#include <linux/kobject.h>

#include <linux/skbuff.h>

#include <linux/workqueue.h>

#include <linux/sysfs.h>

#include <net/net_namespace.h>



struct hardidletimer_tg_attr {

	struct attribute attr;

	ssize_t	(*show)(struct kobject *kobj,

			struct attribute *attr, char *buf);

};



struct hardidletimer_tg {

	struct list_head entry;

	struct alarm alarm;

	struct work_struct work;



	struct kobject *kobj;

	struct hardidletimer_tg_attr attr;



	unsigned int refcnt;

	bool send_nl_msg;

	bool active;

};



static LIST_HEAD(hardidletimer_tg_list);

static DEFINE_MUTEX(list_mutex);



static struct kobject *hardidletimer_tg_kobj;



static void notify_netlink_uevent(const char *iface,

		struct hardidletimer_tg *timer)

{

	char iface_msg[NLMSG_MAX_SIZE];

	char state_msg[NLMSG_MAX_SIZE];

	char *envp[] = { iface_msg, state_msg, NULL };

	int res;



	res = snprintf(iface_msg, NLMSG_MAX_SIZE, "INTERFACE=%s",

		       iface);

	if (NLMSG_MAX_SIZE <= res) {

		pr_err("message too long (%d)", res);

		return;

	}

	res = snprintf(state_msg, NLMSG_MAX_SIZE, "STATE=%s",

		       timer->active ? "active" : "inactive");

	if (NLMSG_MAX_SIZE <= res) {

		pr_err("message too long (%d)", res);

		return;

	}

	pr_debug("putting nlmsg: <%s> <%s>\n", iface_msg, state_msg);

	kobject_uevent_env(hardidletimer_tg_kobj, KOBJ_CHANGE, envp);

	return;





}



static

struct hardidletimer_tg *__hardidletimer_tg_find_by_label(const char *label)

{

	struct hardidletimer_tg *entry;



	BUG_ON(!label);



	list_for_each_entry(entry, &hardidletimer_tg_list, entry) {

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

			return entry;

	}



	return NULL;

}



static ssize_t hardidletimer_tg_show(struct kobject *kobj,

			struct attribute *attr, char *buf)

{

	struct hardidletimer_tg *timer;

	ktime_t expires;

	struct timespec ktimespec;



	memset(&ktimespec, 0, sizeof(struct timespec));

	mutex_lock(&list_mutex);



	timer =	__hardidletimer_tg_find_by_label(attr->name);

	if (timer) {

		expires = alarm_expires_remaining(&timer->alarm);

		ktimespec = ktime_to_timespec(expires);

	}



	mutex_unlock(&list_mutex);



	if (ktimespec.tv_sec >= 0)

		return snprintf(buf, PAGE_SIZE, "%ld\n", ktimespec.tv_sec);



	if (timer->send_nl_msg)

		return snprintf(buf, PAGE_SIZE, "0 %ld\n", ktimespec.tv_sec);

	else

		return snprintf(buf, PAGE_SIZE, "0\n");

}



static void hardidletimer_tg_work(struct work_struct *work)

{

	struct hardidletimer_tg *timer = container_of(work,

				struct hardidletimer_tg, work);



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



	if (timer->send_nl_msg)

		notify_netlink_uevent(timer->attr.attr.name, timer);

}



static enum alarmtimer_restart hardidletimer_tg_alarmproc(struct alarm *alarm,

							ktime_t now)

{

	struct hardidletimer_tg *timer = alarm->data;



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



	timer->active = false;

	schedule_work(&timer->work);

	return ALARMTIMER_NORESTART;

}



static int hardidletimer_tg_create(struct hardidletimer_tg_info *info)

{

	int ret;

	ktime_t tout;



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

	if (!info->timer) {

		ret = -ENOMEM;

		goto out;

	}



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

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

		ret = -ENOMEM;

		goto out_free_timer;

	}

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

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



	ret = sysfs_create_file(hardidletimer_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, &hardidletimer_tg_list);



	alarm_init(&info->timer->alarm, ALARM_BOOTTIME,

				hardidletimer_tg_alarmproc);

	info->timer->alarm.data = info->timer;

	info->timer->refcnt = 1;

	info->timer->send_nl_msg = (info->send_nl_msg == 0) ? false : true;

	info->timer->active = true;

	tout = ktime_set(info->timeout, 0);

	alarm_start_relative(&info->timer->alarm, tout);



	INIT_WORK(&info->timer->work, hardidletimer_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 hardidletimer_tg_target(struct sk_buff *skb,

					 const struct xt_action_param *par)

{

	const struct hardidletimer_tg_info *info = par->targinfo;

	ktime_t tout;



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

		 info->label, info->timeout);



	BUG_ON(!info->timer);



	if (info->timer->active == false) {

		schedule_work(&info->timer->work);

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

	}



	info->timer->active = true;

	/* TODO: Avoid modifying timers on each packet */

	tout = ktime_set(info->timeout, 0);

	alarm_start_relative(&info->timer->alarm, tout);



	return XT_CONTINUE;

}



static int hardidletimer_tg_checkentry(const struct xt_tgchk_param *par)

{

	struct hardidletimer_tg_info *info = par->targinfo;

	int ret;

	ktime_t tout;



	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_HARDIDLETIMER_LABEL_SIZE)

				== MAX_HARDIDLETIMER_LABEL_SIZE) {

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

		return -EINVAL;

	}



	mutex_lock(&list_mutex);



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

	if (info->timer) {

		info->timer->refcnt++;

		if (info->timer->active == false) {

				schedule_work(&info->timer->work);

				pr_debug("Starting Checkentry timer\n");

		}



		info->timer->active = true;

		tout = ktime_set(info->timeout, 0);

		alarm_start_relative(&info->timer->alarm, tout);



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

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

	} else {

		ret = hardidletimer_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 hardidletimer_tg_destroy(const struct xt_tgdtor_param *par)

{

	const struct hardidletimer_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);

		alarm_cancel(&info->timer->alarm);

		sysfs_remove_file(hardidletimer_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 hardidletimer_tg __read_mostly = {

	.name		= "HARDIDLETIMER",

	.revision	= 1,

	.family		= NFPROTO_UNSPEC,

	.target		= hardidletimer_tg_target,

	.targetsize     = sizeof(struct hardidletimer_tg_info),

	.checkentry	= hardidletimer_tg_checkentry,

	.destroy        = hardidletimer_tg_destroy,

	.me		= THIS_MODULE,

};



static struct class *hardidletimer_tg_class;



static struct device *hardidletimer_tg_device;



static int __init hardidletimer_tg_init(void)

{

	int err;



	hardidletimer_tg_class = class_create(THIS_MODULE, "xt_hardidletimer");

	err = PTR_ERR(hardidletimer_tg_class);

	if (IS_ERR(hardidletimer_tg_class)) {

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

		goto out;

	}



	hardidletimer_tg_device = device_create(hardidletimer_tg_class, NULL,

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

	err = PTR_ERR(hardidletimer_tg_device);

	if (IS_ERR(hardidletimer_tg_device)) {

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

		goto out_class;

	}



	hardidletimer_tg_kobj = &hardidletimer_tg_device->kobj;



	err = xt_register_target(&hardidletimer_tg);

	if (err < 0) {

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

		goto out_dev;

	}



	return 0;

out_dev:

	device_destroy(hardidletimer_tg_class, MKDEV(0, 0));

out_class:

	class_destroy(hardidletimer_tg_class);

out:

	return err;

}



static void __exit hardidletimer_tg_exit(void)

{

	xt_unregister_target(&hardidletimer_tg);



	device_destroy(hardidletimer_tg_class, MKDEV(0, 0));

	class_destroy(hardidletimer_tg_class);

}



module_init(hardidletimer_tg_init);

module_exit(hardidletimer_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");