1 /*
2 * linux/net/netfilter/xt_IDLETIMER.c
3 *
4 * Netfilter module to trigger a timer when packet matches.
5 * After timer expires a kevent will be sent.
6 *
7 * Copyright (C) 2004, 2010 Nokia Corporation
8 *
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 * This program is free software; you can redistribute it and/or
17 * modify it under the terms of the GNU General Public License
18 * version 2 as published by the Free Software Foundation.
19 *
20 * This program is distributed in the hope that it will be useful, but
21 * WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 * General Public License for more details.
24 *
25 * You should have received a copy of the GNU General Public License
26 * along with this program; if not, write to the Free Software
27 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
28 * 02110-1301 USA
29 */
30
31 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
32
33 #include <linux/module.h>
34 #include <linux/timer.h>
35 #include <linux/list.h>
36 #include <linux/mutex.h>
37 #include <linux/netfilter.h>
38 #include <linux/netfilter/x_tables.h>
39 #include <linux/netfilter/xt_IDLETIMER.h>
40 #include <linux/kdev_t.h>
41 #include <linux/kobject.h>
42 #include <linux/skbuff.h>
43 #include <linux/workqueue.h>
44 #include <linux/sysfs.h>
45 #include <linux/rtc.h>
46 #include <linux/time.h>
47 #include <linux/math64.h>
48 #include <linux/suspend.h>
49 #include <linux/notifier.h>
50 #include <net/net_namespace.h>
51 #include <net/sock.h>
52
53 struct idletimer_tg_attr {
54 struct attribute attr;
55 ssize_t (*show)(struct kobject *kobj,
56 struct attribute *attr, char *buf);
57 };
58
59 struct idletimer_tg {
60 struct list_head entry;
61 struct timer_list timer;
62 struct work_struct work;
63
64 struct kobject *kobj;
65 struct idletimer_tg_attr attr;
66
67 struct timespec delayed_timer_trigger;
68 struct timespec last_modified_timer;
69 struct timespec last_suspend_time;
70 struct notifier_block pm_nb;
71
72 int timeout;
73 unsigned int refcnt;
74 bool work_pending;
75 bool send_nl_msg;
76 bool active;
77 uid_t uid;
78 };
79
80 static LIST_HEAD(idletimer_tg_list);
81 static DEFINE_MUTEX(list_mutex);
82 static DEFINE_SPINLOCK(timestamp_lock);
83
84 static struct kobject *idletimer_tg_kobj;
85
check_for_delayed_trigger(struct idletimer_tg * timer,struct timespec * ts)86 static bool check_for_delayed_trigger(struct idletimer_tg *timer,
87 struct timespec *ts)
88 {
89 bool state;
90 struct timespec temp;
91 spin_lock_bh(×tamp_lock);
92 timer->work_pending = false;
93 if ((ts->tv_sec - timer->last_modified_timer.tv_sec) > timer->timeout ||
94 timer->delayed_timer_trigger.tv_sec != 0) {
95 state = false;
96 temp.tv_sec = timer->timeout;
97 temp.tv_nsec = 0;
98 if (timer->delayed_timer_trigger.tv_sec != 0) {
99 temp = timespec_add(timer->delayed_timer_trigger, temp);
100 ts->tv_sec = temp.tv_sec;
101 ts->tv_nsec = temp.tv_nsec;
102 timer->delayed_timer_trigger.tv_sec = 0;
103 timer->work_pending = true;
104 schedule_work(&timer->work);
105 } else {
106 temp = timespec_add(timer->last_modified_timer, temp);
107 ts->tv_sec = temp.tv_sec;
108 ts->tv_nsec = temp.tv_nsec;
109 }
110 } else {
111 state = timer->active;
112 }
113 spin_unlock_bh(×tamp_lock);
114 return state;
115 }
116
notify_netlink_uevent(const char * iface,struct idletimer_tg * timer)117 static void notify_netlink_uevent(const char *iface, struct idletimer_tg *timer)
118 {
119 char iface_msg[NLMSG_MAX_SIZE];
120 char state_msg[NLMSG_MAX_SIZE];
121 char timestamp_msg[NLMSG_MAX_SIZE];
122 char uid_msg[NLMSG_MAX_SIZE];
123 char *envp[] = { iface_msg, state_msg, timestamp_msg, uid_msg, NULL };
124 int res;
125 struct timespec ts;
126 uint64_t time_ns;
127 bool state;
128
129 res = snprintf(iface_msg, NLMSG_MAX_SIZE, "INTERFACE=%s",
130 iface);
131 if (NLMSG_MAX_SIZE <= res) {
132 pr_err("message too long (%d)", res);
133 return;
134 }
135
136 get_monotonic_boottime(&ts);
137 state = check_for_delayed_trigger(timer, &ts);
138 res = snprintf(state_msg, NLMSG_MAX_SIZE, "STATE=%s",
139 state ? "active" : "inactive");
140
141 if (NLMSG_MAX_SIZE <= res) {
142 pr_err("message too long (%d)", res);
143 return;
144 }
145
146 if (state) {
147 res = snprintf(uid_msg, NLMSG_MAX_SIZE, "UID=%u", timer->uid);
148 if (NLMSG_MAX_SIZE <= res)
149 pr_err("message too long (%d)", res);
150 } else {
151 res = snprintf(uid_msg, NLMSG_MAX_SIZE, "UID=");
152 if (NLMSG_MAX_SIZE <= res)
153 pr_err("message too long (%d)", res);
154 }
155
156 time_ns = timespec_to_ns(&ts);
157 res = snprintf(timestamp_msg, NLMSG_MAX_SIZE, "TIME_NS=%llu", time_ns);
158 if (NLMSG_MAX_SIZE <= res) {
159 timestamp_msg[0] = '\0';
160 pr_err("message too long (%d)", res);
161 }
162
163 pr_debug("putting nlmsg: <%s> <%s> <%s> <%s>\n", iface_msg, state_msg,
164 timestamp_msg, uid_msg);
165 kobject_uevent_env(idletimer_tg_kobj, KOBJ_CHANGE, envp);
166 return;
167
168
169 }
170
171 static
__idletimer_tg_find_by_label(const char * label)172 struct idletimer_tg *__idletimer_tg_find_by_label(const char *label)
173 {
174 struct idletimer_tg *entry;
175
176 BUG_ON(!label);
177
178 list_for_each_entry(entry, &idletimer_tg_list, entry) {
179 if (!strcmp(label, entry->attr.attr.name))
180 return entry;
181 }
182
183 return NULL;
184 }
185
idletimer_tg_show(struct kobject * kobj,struct attribute * attr,char * buf)186 static ssize_t idletimer_tg_show(struct kobject *kobj, struct attribute *attr,
187 char *buf)
188 {
189 struct idletimer_tg *timer;
190 unsigned long expires = 0;
191 unsigned long now = jiffies;
192
193 mutex_lock(&list_mutex);
194
195 timer = __idletimer_tg_find_by_label(attr->name);
196 if (timer)
197 expires = timer->timer.expires;
198
199 mutex_unlock(&list_mutex);
200
201 if (time_after(expires, now))
202 return sprintf(buf, "%u\n",
203 jiffies_to_msecs(expires - now) / 1000);
204
205 if (timer->send_nl_msg)
206 return sprintf(buf, "0 %d\n",
207 jiffies_to_msecs(now - expires) / 1000);
208 else
209 return sprintf(buf, "0\n");
210 }
211
idletimer_tg_work(struct work_struct * work)212 static void idletimer_tg_work(struct work_struct *work)
213 {
214 struct idletimer_tg *timer = container_of(work, struct idletimer_tg,
215 work);
216
217 sysfs_notify(idletimer_tg_kobj, NULL, timer->attr.attr.name);
218
219 if (timer->send_nl_msg)
220 notify_netlink_uevent(timer->attr.attr.name, timer);
221 }
222
idletimer_tg_expired(unsigned long data)223 static void idletimer_tg_expired(unsigned long data)
224 {
225 struct idletimer_tg *timer = (struct idletimer_tg *) data;
226
227 pr_debug("timer %s expired\n", timer->attr.attr.name);
228 spin_lock_bh(×tamp_lock);
229 timer->active = false;
230 timer->work_pending = true;
231 schedule_work(&timer->work);
232 spin_unlock_bh(×tamp_lock);
233 }
234
idletimer_resume(struct notifier_block * notifier,unsigned long pm_event,void * unused)235 static int idletimer_resume(struct notifier_block *notifier,
236 unsigned long pm_event, void *unused)
237 {
238 struct timespec ts;
239 unsigned long time_diff, now = jiffies;
240 struct idletimer_tg *timer = container_of(notifier,
241 struct idletimer_tg, pm_nb);
242 if (!timer)
243 return NOTIFY_DONE;
244 switch (pm_event) {
245 case PM_SUSPEND_PREPARE:
246 get_monotonic_boottime(&timer->last_suspend_time);
247 break;
248 case PM_POST_SUSPEND:
249 spin_lock_bh(×tamp_lock);
250 if (!timer->active) {
251 spin_unlock_bh(×tamp_lock);
252 break;
253 }
254 /* since jiffies are not updated when suspended now represents
255 * the time it would have suspended */
256 if (time_after(timer->timer.expires, now)) {
257 get_monotonic_boottime(&ts);
258 ts = timespec_sub(ts, timer->last_suspend_time);
259 time_diff = timespec_to_jiffies(&ts);
260 if (timer->timer.expires > (time_diff + now)) {
261 mod_timer_pending(&timer->timer,
262 (timer->timer.expires - time_diff));
263 } else {
264 del_timer(&timer->timer);
265 timer->timer.expires = 0;
266 timer->active = false;
267 timer->work_pending = true;
268 schedule_work(&timer->work);
269 }
270 }
271 spin_unlock_bh(×tamp_lock);
272 break;
273 default:
274 break;
275 }
276 return NOTIFY_DONE;
277 }
278
idletimer_tg_create(struct idletimer_tg_info * info)279 static int idletimer_tg_create(struct idletimer_tg_info *info)
280 {
281 int ret;
282
283 info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL);
284 if (!info->timer) {
285 ret = -ENOMEM;
286 goto out;
287 }
288
289 info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);
290 if (!info->timer->attr.attr.name) {
291 ret = -ENOMEM;
292 goto out_free_timer;
293 }
294 info->timer->attr.attr.mode = S_IRUGO;
295 info->timer->attr.show = idletimer_tg_show;
296
297 ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr);
298 if (ret < 0) {
299 pr_debug("couldn't add file to sysfs");
300 goto out_free_attr;
301 }
302
303 list_add(&info->timer->entry, &idletimer_tg_list);
304
305 setup_timer(&info->timer->timer, idletimer_tg_expired,
306 (unsigned long) info->timer);
307 info->timer->refcnt = 1;
308 info->timer->send_nl_msg = (info->send_nl_msg == 0) ? false : true;
309 info->timer->active = true;
310 info->timer->timeout = info->timeout;
311
312 info->timer->delayed_timer_trigger.tv_sec = 0;
313 info->timer->delayed_timer_trigger.tv_nsec = 0;
314 info->timer->work_pending = false;
315 info->timer->uid = 0;
316 get_monotonic_boottime(&info->timer->last_modified_timer);
317
318 info->timer->pm_nb.notifier_call = idletimer_resume;
319 ret = register_pm_notifier(&info->timer->pm_nb);
320 if (ret)
321 printk(KERN_WARNING "[%s] Failed to register pm notifier %d\n",
322 __func__, ret);
323
324 mod_timer(&info->timer->timer,
325 msecs_to_jiffies(info->timeout * 1000) + jiffies);
326
327 INIT_WORK(&info->timer->work, idletimer_tg_work);
328
329 return 0;
330
331 out_free_attr:
332 kfree(info->timer->attr.attr.name);
333 out_free_timer:
334 kfree(info->timer);
335 out:
336 return ret;
337 }
338
reset_timer(const struct idletimer_tg_info * info,struct sk_buff * skb)339 static void reset_timer(const struct idletimer_tg_info *info,
340 struct sk_buff *skb)
341 {
342 unsigned long now = jiffies;
343 struct idletimer_tg *timer = info->timer;
344 bool timer_prev;
345
346 spin_lock_bh(×tamp_lock);
347 timer_prev = timer->active;
348 timer->active = true;
349 /* timer_prev is used to guard overflow problem in time_before*/
350 if (!timer_prev || time_before(timer->timer.expires, now)) {
351 pr_debug("Starting Checkentry timer (Expired, Jiffies): %lu, %lu\n",
352 timer->timer.expires, now);
353
354 /* Stores the uid resposible for waking up the radio */
355 if (skb && (skb->sk)) {
356 struct sock *sk = skb->sk;
357 read_lock_bh(&sk->sk_callback_lock);
358 if ((sk->sk_socket) && (sk->sk_socket->file) &&
359 (sk->sk_socket->file->f_cred))
360 timer->uid = sk->sk_socket->file->f_cred->uid;
361 read_unlock_bh(&sk->sk_callback_lock);
362 }
363
364 /* checks if there is a pending inactive notification*/
365 if (timer->work_pending)
366 timer->delayed_timer_trigger = timer->last_modified_timer;
367 else {
368 timer->work_pending = true;
369 schedule_work(&timer->work);
370 }
371 }
372
373 get_monotonic_boottime(&timer->last_modified_timer);
374 mod_timer(&timer->timer,
375 msecs_to_jiffies(info->timeout * 1000) + now);
376 spin_unlock_bh(×tamp_lock);
377 }
378
379 /*
380 * The actual xt_tables plugin.
381 */
idletimer_tg_target(struct sk_buff * skb,const struct xt_action_param * par)382 static unsigned int idletimer_tg_target(struct sk_buff *skb,
383 const struct xt_action_param *par)
384 {
385 const struct idletimer_tg_info *info = par->targinfo;
386 unsigned long now = jiffies;
387
388 pr_debug("resetting timer %s, timeout period %u\n",
389 info->label, info->timeout);
390
391 BUG_ON(!info->timer);
392
393 info->timer->active = true;
394
395 if (time_before(info->timer->timer.expires, now)) {
396 schedule_work(&info->timer->work);
397 pr_debug("Starting timer %s (Expired, Jiffies): %lu, %lu\n",
398 info->label, info->timer->timer.expires, now);
399 }
400
401 /* TODO: Avoid modifying timers on each packet */
402 reset_timer(info, skb);
403 return XT_CONTINUE;
404 }
405
idletimer_tg_checkentry(const struct xt_tgchk_param * par)406 static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
407 {
408 struct idletimer_tg_info *info = par->targinfo;
409 int ret;
410
411 pr_debug("checkentry targinfo %s\n", info->label);
412
413 if (info->timeout == 0) {
414 pr_debug("timeout value is zero\n");
415 return -EINVAL;
416 }
417
418 if (info->label[0] == '\0' ||
419 strnlen(info->label,
420 MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) {
421 pr_debug("label is empty or not nul-terminated\n");
422 return -EINVAL;
423 }
424
425 mutex_lock(&list_mutex);
426
427 info->timer = __idletimer_tg_find_by_label(info->label);
428 if (info->timer) {
429 info->timer->refcnt++;
430 reset_timer(info, NULL);
431 pr_debug("increased refcnt of timer %s to %u\n",
432 info->label, info->timer->refcnt);
433 } else {
434 ret = idletimer_tg_create(info);
435 if (ret < 0) {
436 pr_debug("failed to create timer\n");
437 mutex_unlock(&list_mutex);
438 return ret;
439 }
440 }
441
442 mutex_unlock(&list_mutex);
443
444 return 0;
445 }
446
idletimer_tg_destroy(const struct xt_tgdtor_param * par)447 static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
448 {
449 const struct idletimer_tg_info *info = par->targinfo;
450
451 pr_debug("destroy targinfo %s\n", info->label);
452
453 mutex_lock(&list_mutex);
454
455 if (--info->timer->refcnt == 0) {
456 pr_debug("deleting timer %s\n", info->label);
457
458 list_del(&info->timer->entry);
459 del_timer_sync(&info->timer->timer);
460 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
461 unregister_pm_notifier(&info->timer->pm_nb);
462 kfree(info->timer->attr.attr.name);
463 kfree(info->timer);
464 } else {
465 pr_debug("decreased refcnt of timer %s to %u\n",
466 info->label, info->timer->refcnt);
467 }
468
469 mutex_unlock(&list_mutex);
470 }
471
472 static struct xt_target idletimer_tg __read_mostly = {
473 .name = "IDLETIMER",
474 .revision = 1,
475 .family = NFPROTO_UNSPEC,
476 .target = idletimer_tg_target,
477 .targetsize = sizeof(struct idletimer_tg_info),
478 .checkentry = idletimer_tg_checkentry,
479 .destroy = idletimer_tg_destroy,
480 .me = THIS_MODULE,
481 };
482
483 static struct class *idletimer_tg_class;
484
485 static struct device *idletimer_tg_device;
486
idletimer_tg_init(void)487 static int __init idletimer_tg_init(void)
488 {
489 int err;
490
491 idletimer_tg_class = class_create(THIS_MODULE, "xt_idletimer");
492 err = PTR_ERR(idletimer_tg_class);
493 if (IS_ERR(idletimer_tg_class)) {
494 pr_debug("couldn't register device class\n");
495 goto out;
496 }
497
498 idletimer_tg_device = device_create(idletimer_tg_class, NULL,
499 MKDEV(0, 0), NULL, "timers");
500 err = PTR_ERR(idletimer_tg_device);
501 if (IS_ERR(idletimer_tg_device)) {
502 pr_debug("couldn't register system device\n");
503 goto out_class;
504 }
505
506 idletimer_tg_kobj = &idletimer_tg_device->kobj;
507
508 err = xt_register_target(&idletimer_tg);
509 if (err < 0) {
510 pr_debug("couldn't register xt target\n");
511 goto out_dev;
512 }
513
514 return 0;
515 out_dev:
516 device_destroy(idletimer_tg_class, MKDEV(0, 0));
517 out_class:
518 class_destroy(idletimer_tg_class);
519 out:
520 return err;
521 }
522
idletimer_tg_exit(void)523 static void __exit idletimer_tg_exit(void)
524 {
525 xt_unregister_target(&idletimer_tg);
526
527 device_destroy(idletimer_tg_class, MKDEV(0, 0));
528 class_destroy(idletimer_tg_class);
529 }
530
531 module_init(idletimer_tg_init);
532 module_exit(idletimer_tg_exit);
533
534 MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>");
535 MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>");
536 MODULE_DESCRIPTION("Xtables: idle time monitor");
537 MODULE_LICENSE("GPL v2");
538 MODULE_ALIAS("ipt_IDLETIMER");
539 MODULE_ALIAS("ip6t_IDLETIMER");
540 MODULE_ALIAS("arpt_IDLETIMER");
541