1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/net/netfilter/xt_IDLETIMER.c
5 * Netfilter module to trigger a timer when packet matches.
6 * After timer expires a kevent will be sent.
8 * Copyright (C) 2004, 2010 Nokia Corporation
9 * Written by Timo Teras <ext-timo.teras@nokia.com>
11 * Converted to x_tables and reworked for upstream inclusion
12 * by Luciano Coelho <luciano.coelho@nokia.com>
14 * Contact: Luciano Coelho <luciano.coelho@nokia.com>
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 #include <linux/module.h>
20 #include <linux/timer.h>
21 #include <linux/list.h>
22 #include <linux/mutex.h>
23 #include <linux/netfilter.h>
24 #include <linux/netfilter/x_tables.h>
25 #include <linux/netfilter/xt_IDLETIMER.h>
26 #include <linux/kdev_t.h>
27 #include <linux/kobject.h>
28 #include <linux/workqueue.h>
29 #include <linux/sysfs.h>
32 struct list_head entry;
33 struct timer_list timer;
34 struct work_struct work;
37 struct device_attribute attr;
42 static LIST_HEAD(idletimer_tg_list);
43 static DEFINE_MUTEX(list_mutex);
45 static struct kobject *idletimer_tg_kobj;
48 struct idletimer_tg *__idletimer_tg_find_by_label(const char *label)
50 struct idletimer_tg *entry;
52 list_for_each_entry(entry, &idletimer_tg_list, entry) {
53 if (!strcmp(label, entry->attr.attr.name))
60 static ssize_t idletimer_tg_show(struct device *dev,
61 struct device_attribute *attr, char *buf)
63 struct idletimer_tg *timer;
64 unsigned long expires = 0;
66 mutex_lock(&list_mutex);
68 timer = __idletimer_tg_find_by_label(attr->attr.name);
70 expires = timer->timer.expires;
72 mutex_unlock(&list_mutex);
74 if (time_after(expires, jiffies))
75 return sprintf(buf, "%u\n",
76 jiffies_to_msecs(expires - jiffies) / 1000);
78 return sprintf(buf, "0\n");
81 static void idletimer_tg_work(struct work_struct *work)
83 struct idletimer_tg *timer = container_of(work, struct idletimer_tg,
86 sysfs_notify(idletimer_tg_kobj, NULL, timer->attr.attr.name);
89 static void idletimer_tg_expired(struct timer_list *t)
91 struct idletimer_tg *timer = from_timer(timer, t, timer);
93 pr_debug("timer %s expired\n", timer->attr.attr.name);
95 schedule_work(&timer->work);
98 static int idletimer_check_sysfs_name(const char *name, unsigned int size)
102 ret = xt_check_proc_name(name, size);
106 if (!strcmp(name, "power") ||
107 !strcmp(name, "subsystem") ||
108 !strcmp(name, "uevent"))
114 static int idletimer_tg_create(struct idletimer_tg_info *info)
118 info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL);
124 ret = idletimer_check_sysfs_name(info->label, sizeof(info->label));
128 sysfs_attr_init(&info->timer->attr.attr);
129 info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);
130 if (!info->timer->attr.attr.name) {
134 info->timer->attr.attr.mode = 0444;
135 info->timer->attr.show = idletimer_tg_show;
137 ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr);
139 pr_debug("couldn't add file to sysfs");
143 list_add(&info->timer->entry, &idletimer_tg_list);
145 timer_setup(&info->timer->timer, idletimer_tg_expired, 0);
146 info->timer->refcnt = 1;
148 INIT_WORK(&info->timer->work, idletimer_tg_work);
150 mod_timer(&info->timer->timer,
151 msecs_to_jiffies(info->timeout * 1000) + jiffies);
156 kfree(info->timer->attr.attr.name);
164 * The actual xt_tables plugin.
166 static unsigned int idletimer_tg_target(struct sk_buff *skb,
167 const struct xt_action_param *par)
169 const struct idletimer_tg_info *info = par->targinfo;
171 pr_debug("resetting timer %s, timeout period %u\n",
172 info->label, info->timeout);
174 mod_timer(&info->timer->timer,
175 msecs_to_jiffies(info->timeout * 1000) + jiffies);
180 static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
182 struct idletimer_tg_info *info = par->targinfo;
185 pr_debug("checkentry targinfo%s\n", info->label);
187 if (info->timeout == 0) {
188 pr_debug("timeout value is zero\n");
191 if (info->timeout >= INT_MAX / 1000) {
192 pr_debug("timeout value is too big\n");
195 if (info->label[0] == '\0' ||
197 MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) {
198 pr_debug("label is empty or not nul-terminated\n");
202 mutex_lock(&list_mutex);
204 info->timer = __idletimer_tg_find_by_label(info->label);
206 info->timer->refcnt++;
207 mod_timer(&info->timer->timer,
208 msecs_to_jiffies(info->timeout * 1000) + jiffies);
210 pr_debug("increased refcnt of timer %s to %u\n",
211 info->label, info->timer->refcnt);
213 ret = idletimer_tg_create(info);
215 pr_debug("failed to create timer\n");
216 mutex_unlock(&list_mutex);
221 mutex_unlock(&list_mutex);
225 static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
227 const struct idletimer_tg_info *info = par->targinfo;
229 pr_debug("destroy targinfo %s\n", info->label);
231 mutex_lock(&list_mutex);
233 if (--info->timer->refcnt == 0) {
234 pr_debug("deleting timer %s\n", info->label);
236 list_del(&info->timer->entry);
237 del_timer_sync(&info->timer->timer);
238 cancel_work_sync(&info->timer->work);
239 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
240 kfree(info->timer->attr.attr.name);
243 pr_debug("decreased refcnt of timer %s to %u\n",
244 info->label, info->timer->refcnt);
247 mutex_unlock(&list_mutex);
250 static struct xt_target idletimer_tg __read_mostly = {
252 .family = NFPROTO_UNSPEC,
253 .target = idletimer_tg_target,
254 .targetsize = sizeof(struct idletimer_tg_info),
255 .usersize = offsetof(struct idletimer_tg_info, timer),
256 .checkentry = idletimer_tg_checkentry,
257 .destroy = idletimer_tg_destroy,
261 static struct class *idletimer_tg_class;
263 static struct device *idletimer_tg_device;
265 static int __init idletimer_tg_init(void)
269 idletimer_tg_class = class_create(THIS_MODULE, "xt_idletimer");
270 err = PTR_ERR(idletimer_tg_class);
271 if (IS_ERR(idletimer_tg_class)) {
272 pr_debug("couldn't register device class\n");
276 idletimer_tg_device = device_create(idletimer_tg_class, NULL,
277 MKDEV(0, 0), NULL, "timers");
278 err = PTR_ERR(idletimer_tg_device);
279 if (IS_ERR(idletimer_tg_device)) {
280 pr_debug("couldn't register system device\n");
284 idletimer_tg_kobj = &idletimer_tg_device->kobj;
286 err = xt_register_target(&idletimer_tg);
288 pr_debug("couldn't register xt target\n");
294 device_destroy(idletimer_tg_class, MKDEV(0, 0));
296 class_destroy(idletimer_tg_class);
301 static void __exit idletimer_tg_exit(void)
303 xt_unregister_target(&idletimer_tg);
305 device_destroy(idletimer_tg_class, MKDEV(0, 0));
306 class_destroy(idletimer_tg_class);
309 module_init(idletimer_tg_init);
310 module_exit(idletimer_tg_exit);
312 MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>");
313 MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>");
314 MODULE_DESCRIPTION("Xtables: idle time monitor");
315 MODULE_LICENSE("GPL v2");
316 MODULE_ALIAS("ipt_IDLETIMER");
317 MODULE_ALIAS("ip6t_IDLETIMER");