xref: /linux/net/netfilter/xt_IDLETIMER.c (revision 84b9b44b) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * linux/net/netfilter/xt_IDLETIMER.c
4  *
5  * Netfilter module to trigger a timer when packet matches.
6  * After timer expires a kevent will be sent.
7  *
8  * Copyright (C) 2004, 2010 Nokia Corporation
9  * Written by Timo Teras <ext-timo.teras@nokia.com>
10  *
11  * Converted to x_tables and reworked for upstream inclusion
12  * by Luciano Coelho <luciano.coelho@nokia.com>
13  *
14  * Contact: Luciano Coelho <luciano.coelho@nokia.com>
15  */
16 
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18 
19 #include <linux/module.h>
20 #include <linux/timer.h>
21 #include <linux/alarmtimer.h>
22 #include <linux/list.h>
23 #include <linux/mutex.h>
24 #include <linux/netfilter.h>
25 #include <linux/netfilter/x_tables.h>
26 #include <linux/netfilter/xt_IDLETIMER.h>
27 #include <linux/kdev_t.h>
28 #include <linux/kobject.h>
29 #include <linux/workqueue.h>
30 #include <linux/sysfs.h>
31 
32 struct idletimer_tg {
33 	struct list_head entry;
34 	struct alarm alarm;
35 	struct timer_list timer;
36 	struct work_struct work;
37 
38 	struct kobject *kobj;
39 	struct device_attribute attr;
40 
41 	unsigned int refcnt;
42 	u8 timer_type;
43 };
44 
45 static LIST_HEAD(idletimer_tg_list);
46 static DEFINE_MUTEX(list_mutex);
47 
48 static struct kobject *idletimer_tg_kobj;
49 
50 static
51 struct idletimer_tg *__idletimer_tg_find_by_label(const char *label)
52 {
53 	struct idletimer_tg *entry;
54 
55 	list_for_each_entry(entry, &idletimer_tg_list, entry) {
56 		if (!strcmp(label, entry->attr.attr.name))
57 			return entry;
58 	}
59 
60 	return NULL;
61 }
62 
63 static ssize_t idletimer_tg_show(struct device *dev,
64 				 struct device_attribute *attr, char *buf)
65 {
66 	struct idletimer_tg *timer;
67 	unsigned long expires = 0;
68 	struct timespec64 ktimespec = {};
69 	long time_diff = 0;
70 
71 	mutex_lock(&list_mutex);
72 
73 	timer =	__idletimer_tg_find_by_label(attr->attr.name);
74 	if (timer) {
75 		if (timer->timer_type & XT_IDLETIMER_ALARM) {
76 			ktime_t expires_alarm = alarm_expires_remaining(&timer->alarm);
77 			ktimespec = ktime_to_timespec64(expires_alarm);
78 			time_diff = ktimespec.tv_sec;
79 		} else {
80 			expires = timer->timer.expires;
81 			time_diff = jiffies_to_msecs(expires - jiffies) / 1000;
82 		}
83 	}
84 
85 	mutex_unlock(&list_mutex);
86 
87 	if (time_after(expires, jiffies) || ktimespec.tv_sec > 0)
88 		return sysfs_emit(buf, "%ld\n", time_diff);
89 
90 	return sysfs_emit(buf, "0\n");
91 }
92 
93 static void idletimer_tg_work(struct work_struct *work)
94 {
95 	struct idletimer_tg *timer = container_of(work, struct idletimer_tg,
96 						  work);
97 
98 	sysfs_notify(idletimer_tg_kobj, NULL, timer->attr.attr.name);
99 }
100 
101 static void idletimer_tg_expired(struct timer_list *t)
102 {
103 	struct idletimer_tg *timer = from_timer(timer, t, timer);
104 
105 	pr_debug("timer %s expired\n", timer->attr.attr.name);
106 
107 	schedule_work(&timer->work);
108 }
109 
110 static enum alarmtimer_restart idletimer_tg_alarmproc(struct alarm *alarm,
111 							  ktime_t now)
112 {
113 	struct idletimer_tg *timer = alarm->data;
114 
115 	pr_debug("alarm %s expired\n", timer->attr.attr.name);
116 	schedule_work(&timer->work);
117 	return ALARMTIMER_NORESTART;
118 }
119 
120 static int idletimer_check_sysfs_name(const char *name, unsigned int size)
121 {
122 	int ret;
123 
124 	ret = xt_check_proc_name(name, size);
125 	if (ret < 0)
126 		return ret;
127 
128 	if (!strcmp(name, "power") ||
129 	    !strcmp(name, "subsystem") ||
130 	    !strcmp(name, "uevent"))
131 		return -EINVAL;
132 
133 	return 0;
134 }
135 
136 static int idletimer_tg_create(struct idletimer_tg_info *info)
137 {
138 	int ret;
139 
140 	info->timer = kzalloc(sizeof(*info->timer), GFP_KERNEL);
141 	if (!info->timer) {
142 		ret = -ENOMEM;
143 		goto out;
144 	}
145 
146 	ret = idletimer_check_sysfs_name(info->label, sizeof(info->label));
147 	if (ret < 0)
148 		goto out_free_timer;
149 
150 	sysfs_attr_init(&info->timer->attr.attr);
151 	info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);
152 	if (!info->timer->attr.attr.name) {
153 		ret = -ENOMEM;
154 		goto out_free_timer;
155 	}
156 	info->timer->attr.attr.mode = 0444;
157 	info->timer->attr.show = idletimer_tg_show;
158 
159 	ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr);
160 	if (ret < 0) {
161 		pr_debug("couldn't add file to sysfs");
162 		goto out_free_attr;
163 	}
164 
165 	list_add(&info->timer->entry, &idletimer_tg_list);
166 
167 	timer_setup(&info->timer->timer, idletimer_tg_expired, 0);
168 	info->timer->refcnt = 1;
169 
170 	INIT_WORK(&info->timer->work, idletimer_tg_work);
171 
172 	mod_timer(&info->timer->timer,
173 		  msecs_to_jiffies(info->timeout * 1000) + jiffies);
174 
175 	return 0;
176 
177 out_free_attr:
178 	kfree(info->timer->attr.attr.name);
179 out_free_timer:
180 	kfree(info->timer);
181 out:
182 	return ret;
183 }
184 
185 static int idletimer_tg_create_v1(struct idletimer_tg_info_v1 *info)
186 {
187 	int ret;
188 
189 	info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL);
190 	if (!info->timer) {
191 		ret = -ENOMEM;
192 		goto out;
193 	}
194 
195 	ret = idletimer_check_sysfs_name(info->label, sizeof(info->label));
196 	if (ret < 0)
197 		goto out_free_timer;
198 
199 	sysfs_attr_init(&info->timer->attr.attr);
200 	info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);
201 	if (!info->timer->attr.attr.name) {
202 		ret = -ENOMEM;
203 		goto out_free_timer;
204 	}
205 	info->timer->attr.attr.mode = 0444;
206 	info->timer->attr.show = idletimer_tg_show;
207 
208 	ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr);
209 	if (ret < 0) {
210 		pr_debug("couldn't add file to sysfs");
211 		goto out_free_attr;
212 	}
213 
214 	/*  notify userspace  */
215 	kobject_uevent(idletimer_tg_kobj,KOBJ_ADD);
216 
217 	list_add(&info->timer->entry, &idletimer_tg_list);
218 	pr_debug("timer type value is %u", info->timer_type);
219 	info->timer->timer_type = info->timer_type;
220 	info->timer->refcnt = 1;
221 
222 	INIT_WORK(&info->timer->work, idletimer_tg_work);
223 
224 	if (info->timer->timer_type & XT_IDLETIMER_ALARM) {
225 		ktime_t tout;
226 		alarm_init(&info->timer->alarm, ALARM_BOOTTIME,
227 			   idletimer_tg_alarmproc);
228 		info->timer->alarm.data = info->timer;
229 		tout = ktime_set(info->timeout, 0);
230 		alarm_start_relative(&info->timer->alarm, tout);
231 	} else {
232 		timer_setup(&info->timer->timer, idletimer_tg_expired, 0);
233 		mod_timer(&info->timer->timer,
234 				msecs_to_jiffies(info->timeout * 1000) + jiffies);
235 	}
236 
237 	return 0;
238 
239 out_free_attr:
240 	kfree(info->timer->attr.attr.name);
241 out_free_timer:
242 	kfree(info->timer);
243 out:
244 	return ret;
245 }
246 
247 /*
248  * The actual xt_tables plugin.
249  */
250 static unsigned int idletimer_tg_target(struct sk_buff *skb,
251 					 const struct xt_action_param *par)
252 {
253 	const struct idletimer_tg_info *info = par->targinfo;
254 
255 	pr_debug("resetting timer %s, timeout period %u\n",
256 		 info->label, info->timeout);
257 
258 	mod_timer(&info->timer->timer,
259 		  msecs_to_jiffies(info->timeout * 1000) + jiffies);
260 
261 	return XT_CONTINUE;
262 }
263 
264 /*
265  * The actual xt_tables plugin.
266  */
267 static unsigned int idletimer_tg_target_v1(struct sk_buff *skb,
268 					 const struct xt_action_param *par)
269 {
270 	const struct idletimer_tg_info_v1 *info = par->targinfo;
271 
272 	pr_debug("resetting timer %s, timeout period %u\n",
273 		 info->label, info->timeout);
274 
275 	if (info->timer->timer_type & XT_IDLETIMER_ALARM) {
276 		ktime_t tout = ktime_set(info->timeout, 0);
277 		alarm_start_relative(&info->timer->alarm, tout);
278 	} else {
279 		mod_timer(&info->timer->timer,
280 				msecs_to_jiffies(info->timeout * 1000) + jiffies);
281 	}
282 
283 	return XT_CONTINUE;
284 }
285 
286 static int idletimer_tg_helper(struct idletimer_tg_info *info)
287 {
288 	if (info->timeout == 0) {
289 		pr_debug("timeout value is zero\n");
290 		return -EINVAL;
291 	}
292 	if (info->timeout >= INT_MAX / 1000) {
293 		pr_debug("timeout value is too big\n");
294 		return -EINVAL;
295 	}
296 	if (info->label[0] == '\0' ||
297 	    strnlen(info->label,
298 		    MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) {
299 		pr_debug("label is empty or not nul-terminated\n");
300 		return -EINVAL;
301 	}
302 	return 0;
303 }
304 
305 
306 static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
307 {
308 	struct idletimer_tg_info *info = par->targinfo;
309 	int ret;
310 
311 	pr_debug("checkentry targinfo%s\n", info->label);
312 
313 	ret = idletimer_tg_helper(info);
314 	if(ret < 0)
315 	{
316 		pr_debug("checkentry helper return invalid\n");
317 		return -EINVAL;
318 	}
319 	mutex_lock(&list_mutex);
320 
321 	info->timer = __idletimer_tg_find_by_label(info->label);
322 	if (info->timer) {
323 		info->timer->refcnt++;
324 		mod_timer(&info->timer->timer,
325 			  msecs_to_jiffies(info->timeout * 1000) + jiffies);
326 
327 		pr_debug("increased refcnt of timer %s to %u\n",
328 			 info->label, info->timer->refcnt);
329 	} else {
330 		ret = idletimer_tg_create(info);
331 		if (ret < 0) {
332 			pr_debug("failed to create timer\n");
333 			mutex_unlock(&list_mutex);
334 			return ret;
335 		}
336 	}
337 
338 	mutex_unlock(&list_mutex);
339 	return 0;
340 }
341 
342 static int idletimer_tg_checkentry_v1(const struct xt_tgchk_param *par)
343 {
344 	struct idletimer_tg_info_v1 *info = par->targinfo;
345 	int ret;
346 
347 	pr_debug("checkentry targinfo%s\n", info->label);
348 
349 	if (info->send_nl_msg)
350 		return -EOPNOTSUPP;
351 
352 	ret = idletimer_tg_helper((struct idletimer_tg_info *)info);
353 	if(ret < 0)
354 	{
355 		pr_debug("checkentry helper return invalid\n");
356 		return -EINVAL;
357 	}
358 
359 	if (info->timer_type > XT_IDLETIMER_ALARM) {
360 		pr_debug("invalid value for timer type\n");
361 		return -EINVAL;
362 	}
363 
364 	mutex_lock(&list_mutex);
365 
366 	info->timer = __idletimer_tg_find_by_label(info->label);
367 	if (info->timer) {
368 		if (info->timer->timer_type != info->timer_type) {
369 			pr_debug("Adding/Replacing rule with same label and different timer type is not allowed\n");
370 			mutex_unlock(&list_mutex);
371 			return -EINVAL;
372 		}
373 
374 		info->timer->refcnt++;
375 		if (info->timer_type & XT_IDLETIMER_ALARM) {
376 			/* calculate remaining expiry time */
377 			ktime_t tout = alarm_expires_remaining(&info->timer->alarm);
378 			struct timespec64 ktimespec = ktime_to_timespec64(tout);
379 
380 			if (ktimespec.tv_sec > 0) {
381 				pr_debug("time_expiry_remaining %lld\n",
382 					 ktimespec.tv_sec);
383 				alarm_start_relative(&info->timer->alarm, tout);
384 			}
385 		} else {
386 				mod_timer(&info->timer->timer,
387 					msecs_to_jiffies(info->timeout * 1000) + jiffies);
388 		}
389 		pr_debug("increased refcnt of timer %s to %u\n",
390 			 info->label, info->timer->refcnt);
391 	} else {
392 		ret = idletimer_tg_create_v1(info);
393 		if (ret < 0) {
394 			pr_debug("failed to create timer\n");
395 			mutex_unlock(&list_mutex);
396 			return ret;
397 		}
398 	}
399 
400 	mutex_unlock(&list_mutex);
401 	return 0;
402 }
403 
404 static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
405 {
406 	const struct idletimer_tg_info *info = par->targinfo;
407 
408 	pr_debug("destroy targinfo %s\n", info->label);
409 
410 	mutex_lock(&list_mutex);
411 
412 	if (--info->timer->refcnt == 0) {
413 		pr_debug("deleting timer %s\n", info->label);
414 
415 		list_del(&info->timer->entry);
416 		timer_shutdown_sync(&info->timer->timer);
417 		cancel_work_sync(&info->timer->work);
418 		sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
419 		kfree(info->timer->attr.attr.name);
420 		kfree(info->timer);
421 	} else {
422 		pr_debug("decreased refcnt of timer %s to %u\n",
423 			 info->label, info->timer->refcnt);
424 	}
425 
426 	mutex_unlock(&list_mutex);
427 }
428 
429 static void idletimer_tg_destroy_v1(const struct xt_tgdtor_param *par)
430 {
431 	const struct idletimer_tg_info_v1 *info = par->targinfo;
432 
433 	pr_debug("destroy targinfo %s\n", info->label);
434 
435 	mutex_lock(&list_mutex);
436 
437 	if (--info->timer->refcnt == 0) {
438 		pr_debug("deleting timer %s\n", info->label);
439 
440 		list_del(&info->timer->entry);
441 		if (info->timer->timer_type & XT_IDLETIMER_ALARM) {
442 			alarm_cancel(&info->timer->alarm);
443 		} else {
444 			timer_shutdown_sync(&info->timer->timer);
445 		}
446 		cancel_work_sync(&info->timer->work);
447 		sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
448 		kfree(info->timer->attr.attr.name);
449 		kfree(info->timer);
450 	} else {
451 		pr_debug("decreased refcnt of timer %s to %u\n",
452 			 info->label, info->timer->refcnt);
453 	}
454 
455 	mutex_unlock(&list_mutex);
456 }
457 
458 
459 static struct xt_target idletimer_tg[] __read_mostly = {
460 	{
461 	.name		= "IDLETIMER",
462 	.family		= NFPROTO_UNSPEC,
463 	.target		= idletimer_tg_target,
464 	.targetsize     = sizeof(struct idletimer_tg_info),
465 	.usersize	= offsetof(struct idletimer_tg_info, timer),
466 	.checkentry	= idletimer_tg_checkentry,
467 	.destroy        = idletimer_tg_destroy,
468 	.me		= THIS_MODULE,
469 	},
470 	{
471 	.name		= "IDLETIMER",
472 	.family		= NFPROTO_UNSPEC,
473 	.revision	= 1,
474 	.target		= idletimer_tg_target_v1,
475 	.targetsize     = sizeof(struct idletimer_tg_info_v1),
476 	.usersize	= offsetof(struct idletimer_tg_info_v1, timer),
477 	.checkentry	= idletimer_tg_checkentry_v1,
478 	.destroy        = idletimer_tg_destroy_v1,
479 	.me		= THIS_MODULE,
480 	},
481 
482 
483 };
484 
485 static struct class *idletimer_tg_class;
486 
487 static struct device *idletimer_tg_device;
488 
489 static int __init idletimer_tg_init(void)
490 {
491 	int err;
492 
493 	idletimer_tg_class = class_create("xt_idletimer");
494 	err = PTR_ERR(idletimer_tg_class);
495 	if (IS_ERR(idletimer_tg_class)) {
496 		pr_debug("couldn't register device class\n");
497 		goto out;
498 	}
499 
500 	idletimer_tg_device = device_create(idletimer_tg_class, NULL,
501 					    MKDEV(0, 0), NULL, "timers");
502 	err = PTR_ERR(idletimer_tg_device);
503 	if (IS_ERR(idletimer_tg_device)) {
504 		pr_debug("couldn't register system device\n");
505 		goto out_class;
506 	}
507 
508 	idletimer_tg_kobj = &idletimer_tg_device->kobj;
509 
510 	err = xt_register_targets(idletimer_tg, ARRAY_SIZE(idletimer_tg));
511 
512 	if (err < 0) {
513 		pr_debug("couldn't register xt target\n");
514 		goto out_dev;
515 	}
516 
517 	return 0;
518 out_dev:
519 	device_destroy(idletimer_tg_class, MKDEV(0, 0));
520 out_class:
521 	class_destroy(idletimer_tg_class);
522 out:
523 	return err;
524 }
525 
526 static void __exit idletimer_tg_exit(void)
527 {
528 	xt_unregister_targets(idletimer_tg, ARRAY_SIZE(idletimer_tg));
529 
530 	device_destroy(idletimer_tg_class, MKDEV(0, 0));
531 	class_destroy(idletimer_tg_class);
532 }
533 
534 module_init(idletimer_tg_init);
535 module_exit(idletimer_tg_exit);
536 
537 MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>");
538 MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>");
539 MODULE_DESCRIPTION("Xtables: idle time monitor");
540 MODULE_LICENSE("GPL v2");
541 MODULE_ALIAS("ipt_IDLETIMER");
542 MODULE_ALIAS("ip6t_IDLETIMER");
543