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 #include <net/inet_sock.h>
53
54 struct idletimer_tg_attr {
55 struct attribute attr;
56 ssize_t (*show)(struct kobject *kobj,
57 struct attribute *attr, char *buf);
58 };
59
60 struct idletimer_tg {
61 struct list_head entry;
62 struct timer_list timer;
63 struct work_struct work;
64
65 struct kobject *kobj;
66 struct idletimer_tg_attr attr;
67
68 struct timespec delayed_timer_trigger;
69 struct timespec last_modified_timer;
70 struct timespec last_suspend_time;
71 struct notifier_block pm_nb;
72
73 int timeout;
74 unsigned int refcnt;
75 bool work_pending;
76 bool send_nl_msg;
77 bool active;
78 uid_t uid;
79 };
80
81 static LIST_HEAD(idletimer_tg_list);
82 static DEFINE_MUTEX(list_mutex);
83 static DEFINE_SPINLOCK(timestamp_lock);
84
85 static struct kobject *idletimer_tg_kobj;
86
check_for_delayed_trigger(struct idletimer_tg * timer,struct timespec * ts)87 static bool check_for_delayed_trigger(struct idletimer_tg *timer,
88 struct timespec *ts)
89 {
90 bool state;
91 struct timespec temp;
92 spin_lock_bh(×tamp_lock);
93 timer->work_pending = false;
94 if ((ts->tv_sec - timer->last_modified_timer.tv_sec) > timer->timeout ||
95 timer->delayed_timer_trigger.tv_sec != 0) {
96 state = false;
97 temp.tv_sec = timer->timeout;
98 temp.tv_nsec = 0;
99 if (timer->delayed_timer_trigger.tv_sec != 0) {
100 temp = timespec_add(timer->delayed_timer_trigger, temp);
101 ts->tv_sec = temp.tv_sec;
102 ts->tv_nsec = temp.tv_nsec;
103 timer->delayed_timer_trigger.tv_sec = 0;
104 timer->work_pending = true;
105 schedule_work(&timer->work);
106 } else {
107 temp = timespec_add(timer->last_modified_timer, temp);
108 ts->tv_sec = temp.tv_sec;
109 ts->tv_nsec = temp.tv_nsec;
110 }
111 } else {
112 state = timer->active;
113 }
114 spin_unlock_bh(×tamp_lock);
115 return state;
116 }
117
notify_netlink_uevent(const char * iface,struct idletimer_tg * timer)118 static void notify_netlink_uevent(const char *iface, struct idletimer_tg *timer)
119 {
120 char iface_msg[NLMSG_MAX_SIZE];
121 char state_msg[NLMSG_MAX_SIZE];
122 char timestamp_msg[NLMSG_MAX_SIZE];
123 char uid_msg[NLMSG_MAX_SIZE];
124 char *envp[] = { iface_msg, state_msg, timestamp_msg, uid_msg, NULL };
125 int res;
126 struct timespec ts;
127 uint64_t time_ns;
128 bool state;
129
130 res = snprintf(iface_msg, NLMSG_MAX_SIZE, "INTERFACE=%s",
131 iface);
132 if (NLMSG_MAX_SIZE <= res) {
133 pr_err("message too long (%d)", res);
134 return;
135 }
136
137 get_monotonic_boottime(&ts);
138 state = check_for_delayed_trigger(timer, &ts);
139 res = snprintf(state_msg, NLMSG_MAX_SIZE, "STATE=%s",
140 state ? "active" : "inactive");
141
142 if (NLMSG_MAX_SIZE <= res) {
143 pr_err("message too long (%d)", res);
144 return;
145 }
146
147 if (state) {
148 res = snprintf(uid_msg, NLMSG_MAX_SIZE, "UID=%u", timer->uid);
149 if (NLMSG_MAX_SIZE <= res)
150 pr_err("message too long (%d)", res);
151 } else {
152 res = snprintf(uid_msg, NLMSG_MAX_SIZE, "UID=");
153 if (NLMSG_MAX_SIZE <= res)
154 pr_err("message too long (%d)", res);
155 }
156
157 time_ns = timespec_to_ns(&ts);
158 res = snprintf(timestamp_msg, NLMSG_MAX_SIZE, "TIME_NS=%llu", time_ns);
159 if (NLMSG_MAX_SIZE <= res) {
160 timestamp_msg[0] = '\0';
161 pr_err("message too long (%d)", res);
162 }
163
164 pr_debug("putting nlmsg: <%s> <%s> <%s> <%s>\n", iface_msg, state_msg,
165 timestamp_msg, uid_msg);
166 kobject_uevent_env(idletimer_tg_kobj, KOBJ_CHANGE, envp);
167 return;
168
169
170 }
171
172 static
__idletimer_tg_find_by_label(const char * label)173 struct idletimer_tg *__idletimer_tg_find_by_label(const char *label)
174 {
175 struct idletimer_tg *entry;
176
177 BUG_ON(!label);
178
179 list_for_each_entry(entry, &idletimer_tg_list, entry) {
180 if (!strcmp(label, entry->attr.attr.name))
181 return entry;
182 }
183
184 return NULL;
185 }
186
idletimer_tg_show(struct kobject * kobj,struct attribute * attr,char * buf)187 static ssize_t idletimer_tg_show(struct kobject *kobj, struct attribute *attr,
188 char *buf)
189 {
190 struct idletimer_tg *timer;
191 unsigned long expires = 0;
192 unsigned long now = jiffies;
193
194 mutex_lock(&list_mutex);
195
196 timer = __idletimer_tg_find_by_label(attr->name);
197 if (timer)
198 expires = timer->timer.expires;
199
200 mutex_unlock(&list_mutex);
201
202 if (time_after(expires, now))
203 return sprintf(buf, "%u\n",
204 jiffies_to_msecs(expires - now) / 1000);
205
206 if (timer->send_nl_msg)
207 return sprintf(buf, "0 %d\n",
208 jiffies_to_msecs(now - expires) / 1000);
209 else
210 return sprintf(buf, "0\n");
211 }
212
idletimer_tg_work(struct work_struct * work)213 static void idletimer_tg_work(struct work_struct *work)
214 {
215 struct idletimer_tg *timer = container_of(work, struct idletimer_tg,
216 work);
217
218 sysfs_notify(idletimer_tg_kobj, NULL, timer->attr.attr.name);
219
220 if (timer->send_nl_msg)
221 notify_netlink_uevent(timer->attr.attr.name, timer);
222 }
223
idletimer_tg_expired(unsigned long data)224 static void idletimer_tg_expired(unsigned long data)
225 {
226 struct idletimer_tg *timer = (struct idletimer_tg *) data;
227
228 pr_debug("timer %s expired\n", timer->attr.attr.name);
229 spin_lock_bh(×tamp_lock);
230 timer->active = false;
231 timer->work_pending = true;
232 schedule_work(&timer->work);
233 spin_unlock_bh(×tamp_lock);
234 }
235
idletimer_resume(struct notifier_block * notifier,unsigned long pm_event,void * unused)236 static int idletimer_resume(struct notifier_block *notifier,
237 unsigned long pm_event, void *unused)
238 {
239 struct timespec ts;
240 unsigned long time_diff, now = jiffies;
241 struct idletimer_tg *timer = container_of(notifier,
242 struct idletimer_tg, pm_nb);
243 if (!timer)
244 return NOTIFY_DONE;
245 switch (pm_event) {
246 case PM_SUSPEND_PREPARE:
247 get_monotonic_boottime(&timer->last_suspend_time);
248 break;
249 case PM_POST_SUSPEND:
250 spin_lock_bh(×tamp_lock);
251 if (!timer->active) {
252 spin_unlock_bh(×tamp_lock);
253 break;
254 }
255 /* since jiffies are not updated when suspended now represents
256 * the time it would have suspended */
257 if (time_after(timer->timer.expires, now)) {
258 get_monotonic_boottime(&ts);
259 ts = timespec_sub(ts, timer->last_suspend_time);
260 time_diff = timespec_to_jiffies(&ts);
261 if (timer->timer.expires > (time_diff + now)) {
262 mod_timer_pending(&timer->timer,
263 (timer->timer.expires - time_diff));
264 } else {
265 del_timer(&timer->timer);
266 timer->timer.expires = 0;
267 timer->active = false;
268 timer->work_pending = true;
269 schedule_work(&timer->work);
270 }
271 }
272 spin_unlock_bh(×tamp_lock);
273 break;
274 default:
275 break;
276 }
277 return NOTIFY_DONE;
278 }
279
idletimer_tg_create(struct idletimer_tg_info * info)280 static int idletimer_tg_create(struct idletimer_tg_info *info)
281 {
282 int ret;
283
284 info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL);
285 if (!info->timer) {
286 ret = -ENOMEM;
287 goto out;
288 }
289
290 sysfs_attr_init(&info->timer->attr.attr);
291 info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);
292 if (!info->timer->attr.attr.name) {
293 ret = -ENOMEM;
294 goto out_free_timer;
295 }
296 info->timer->attr.attr.mode = S_IRUGO;
297 info->timer->attr.show = idletimer_tg_show;
298
299 ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr);
300 if (ret < 0) {
301 pr_debug("couldn't add file to sysfs");
302 goto out_free_attr;
303 }
304
305 list_add(&info->timer->entry, &idletimer_tg_list);
306
307 setup_timer(&info->timer->timer, idletimer_tg_expired,
308 (unsigned long) info->timer);
309 info->timer->refcnt = 1;
310 info->timer->send_nl_msg = (info->send_nl_msg == 0) ? false : true;
311 info->timer->active = true;
312 info->timer->timeout = info->timeout;
313
314 info->timer->delayed_timer_trigger.tv_sec = 0;
315 info->timer->delayed_timer_trigger.tv_nsec = 0;
316 info->timer->work_pending = false;
317 info->timer->uid = 0;
318 get_monotonic_boottime(&info->timer->last_modified_timer);
319
320 info->timer->pm_nb.notifier_call = idletimer_resume;
321 ret = register_pm_notifier(&info->timer->pm_nb);
322 if (ret)
323 printk(KERN_WARNING "[%s] Failed to register pm notifier %d\n",
324 __func__, ret);
325
326 INIT_WORK(&info->timer->work, idletimer_tg_work);
327
328 mod_timer(&info->timer->timer,
329 msecs_to_jiffies(info->timeout * 1000) + jiffies);
330
331 return 0;
332
333 out_free_attr:
334 kfree(info->timer->attr.attr.name);
335 out_free_timer:
336 kfree(info->timer);
337 out:
338 return ret;
339 }
340
reset_timer(const struct idletimer_tg_info * info,struct sk_buff * skb)341 static void reset_timer(const struct idletimer_tg_info *info,
342 struct sk_buff *skb)
343 {
344 unsigned long now = jiffies;
345 struct idletimer_tg *timer = info->timer;
346 bool timer_prev;
347
348 spin_lock_bh(×tamp_lock);
349 timer_prev = timer->active;
350 timer->active = true;
351 /* timer_prev is used to guard overflow problem in time_before*/
352 if (!timer_prev || time_before(timer->timer.expires, now)) {
353 pr_debug("Starting Checkentry timer (Expired, Jiffies): %lu, %lu\n",
354 timer->timer.expires, now);
355
356 /* Stores the uid resposible for waking up the radio */
357 if (skb && (skb->sk)) {
358 timer->uid = from_kuid_munged(current_user_ns(),
359 sock_i_uid(skb_to_full_sk(skb)));
360 }
361
362 /* checks if there is a pending inactive notification*/
363 if (timer->work_pending)
364 timer->delayed_timer_trigger = timer->last_modified_timer;
365 else {
366 timer->work_pending = true;
367 schedule_work(&timer->work);
368 }
369 }
370
371 get_monotonic_boottime(&timer->last_modified_timer);
372 mod_timer(&timer->timer,
373 msecs_to_jiffies(info->timeout * 1000) + now);
374 spin_unlock_bh(×tamp_lock);
375 }
376
377 /*
378 * The actual xt_tables plugin.
379 */
idletimer_tg_target(struct sk_buff * skb,const struct xt_action_param * par)380 static unsigned int idletimer_tg_target(struct sk_buff *skb,
381 const struct xt_action_param *par)
382 {
383 const struct idletimer_tg_info *info = par->targinfo;
384 unsigned long now = jiffies;
385
386 pr_debug("resetting timer %s, timeout period %u\n",
387 info->label, info->timeout);
388
389 BUG_ON(!info->timer);
390
391 info->timer->active = true;
392
393 if (time_before(info->timer->timer.expires, now)) {
394 schedule_work(&info->timer->work);
395 pr_debug("Starting timer %s (Expired, Jiffies): %lu, %lu\n",
396 info->label, info->timer->timer.expires, now);
397 }
398
399 /* TODO: Avoid modifying timers on each packet */
400 reset_timer(info, skb);
401 return XT_CONTINUE;
402 }
403
idletimer_tg_checkentry(const struct xt_tgchk_param * par)404 static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
405 {
406 struct idletimer_tg_info *info = par->targinfo;
407 int ret;
408
409 pr_debug("checkentry targinfo %s\n", info->label);
410
411 if (info->timeout == 0) {
412 pr_debug("timeout value is zero\n");
413 return -EINVAL;
414 }
415 if (info->timeout >= INT_MAX / 1000) {
416 pr_debug("timeout value is too big\n");
417 return -EINVAL;
418 }
419 if (info->label[0] == '\0' ||
420 strnlen(info->label,
421 MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) {
422 pr_debug("label is empty or not nul-terminated\n");
423 return -EINVAL;
424 }
425
426 mutex_lock(&list_mutex);
427
428 info->timer = __idletimer_tg_find_by_label(info->label);
429 if (info->timer) {
430 info->timer->refcnt++;
431 reset_timer(info, NULL);
432 pr_debug("increased refcnt of timer %s to %u\n",
433 info->label, info->timer->refcnt);
434 } else {
435 ret = idletimer_tg_create(info);
436 if (ret < 0) {
437 pr_debug("failed to create timer\n");
438 mutex_unlock(&list_mutex);
439 return ret;
440 }
441 }
442
443 mutex_unlock(&list_mutex);
444
445 return 0;
446 }
447
idletimer_tg_destroy(const struct xt_tgdtor_param * par)448 static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
449 {
450 const struct idletimer_tg_info *info = par->targinfo;
451
452 pr_debug("destroy targinfo %s\n", info->label);
453
454 mutex_lock(&list_mutex);
455
456 if (--info->timer->refcnt == 0) {
457 pr_debug("deleting timer %s\n", info->label);
458
459 list_del(&info->timer->entry);
460 del_timer_sync(&info->timer->timer);
461 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
462 unregister_pm_notifier(&info->timer->pm_nb);
463 cancel_work_sync(&info->timer->work);
464 kfree(info->timer->attr.attr.name);
465 kfree(info->timer);
466 } else {
467 pr_debug("decreased refcnt of timer %s to %u\n",
468 info->label, info->timer->refcnt);
469 }
470
471 mutex_unlock(&list_mutex);
472 }
473
474 static struct xt_target idletimer_tg __read_mostly = {
475 .name = "IDLETIMER",
476 .revision = 1,
477 .family = NFPROTO_UNSPEC,
478 .target = idletimer_tg_target,
479 .targetsize = sizeof(struct idletimer_tg_info),
480 .checkentry = idletimer_tg_checkentry,
481 .destroy = idletimer_tg_destroy,
482 .me = THIS_MODULE,
483 };
484
485 static struct class *idletimer_tg_class;
486
487 static struct device *idletimer_tg_device;
488
idletimer_tg_init(void)489 static int __init idletimer_tg_init(void)
490 {
491 int err;
492
493 idletimer_tg_class = class_create(THIS_MODULE, "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_target(&idletimer_tg);
511 if (err < 0) {
512 pr_debug("couldn't register xt target\n");
513 goto out_dev;
514 }
515
516 return 0;
517 out_dev:
518 device_destroy(idletimer_tg_class, MKDEV(0, 0));
519 out_class:
520 class_destroy(idletimer_tg_class);
521 out:
522 return err;
523 }
524
idletimer_tg_exit(void)525 static void __exit idletimer_tg_exit(void)
526 {
527 xt_unregister_target(&idletimer_tg);
528
529 device_destroy(idletimer_tg_class, MKDEV(0, 0));
530 class_destroy(idletimer_tg_class);
531 }
532
533 module_init(idletimer_tg_init);
534 module_exit(idletimer_tg_exit);
535
536 MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>");
537 MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>");
538 MODULE_DESCRIPTION("Xtables: idle time monitor");
539 MODULE_LICENSE("GPL v2");
540 MODULE_ALIAS("ipt_IDLETIMER");
541 MODULE_ALIAS("ip6t_IDLETIMER");
542 MODULE_ALIAS("arpt_IDLETIMER");
543