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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: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Luciano Coelho 2010-06-15 15:04:00 +02:00 committed by Patrick McHardy
parent d73f33b168
commit 0902b469bd
5 changed files with 373 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/netfilter/Kbuild
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@ -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

45
include/linux/netfilter/xt_IDLETIMER.h Normal file
View File

@ -0,0 +1,45 @@
/*
* 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

12
net/netfilter/Kconfig
View File

@ -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

1
net/netfilter/Makefile
View File

@ -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

314
net/netfilter/xt_IDLETIMER.c Normal file
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@ -0,0 +1,314 @@
/*
* 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");