net/netfilter/xt_IDLETIMER.c

   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
  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(&timestamp_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(&timestamp_lock);
 114         return state;
 115 }
 116
 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
 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
 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
 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
 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(&timestamp_lock);
 229         timer->active = false;
 230         timer->work_pending = true;
 231         schedule_work(&timer->work);
 232         spin_unlock_bh(&timestamp_lock);
 233 }
 234
 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(&timestamp_lock);
 250                 if (!timer->active) {
 251                         spin_unlock_bh(&timestamp_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(&timestamp_lock);
 272                 break;
 273         default:
 274                 break;
 275         }
 276         return NOTIFY_DONE;
 277 }
 278
 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         sysfs_attr_init(&info->timer->attr.attr);
 290         info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);
 291         if (!info->timer->attr.attr.name) {
 292                 ret = -ENOMEM;
 293                 goto out_free_timer;
 294         }
 295         info->timer->attr.attr.mode = S_IRUGO;
 296         info->timer->attr.show = idletimer_tg_show;
 297
 298         ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr);
 299         if (ret < 0) {
 300                 pr_debug("couldn't add file to sysfs");
 301                 goto out_free_attr;
 302         }
 303
 304         list_add(&info->timer->entry, &idletimer_tg_list);
 305
 306         setup_timer(&info->timer->timer, idletimer_tg_expired,
 307                     (unsigned long) info->timer);
 308         info->timer->refcnt = 1;
 309         info->timer->send_nl_msg = (info->send_nl_msg == 0) ? false : true;
 310         info->timer->active = true;
 311         info->timer->timeout = info->timeout;
 312
 313         info->timer->delayed_timer_trigger.tv_sec = 0;
 314         info->timer->delayed_timer_trigger.tv_nsec = 0;
 315         info->timer->work_pending = false;
 316         info->timer->uid = 0;
 317         get_monotonic_boottime(&info->timer->last_modified_timer);
 318
 319         info->timer->pm_nb.notifier_call = idletimer_resume;
 320         ret = register_pm_notifier(&info->timer->pm_nb);
 321         if (ret)
 322                 printk(KERN_WARNING "[%s] Failed to register pm notifier %d\n",
 323                                 __func__, ret);
 324
 325         mod_timer(&info->timer->timer,
 326                   msecs_to_jiffies(info->timeout * 1000) + jiffies);
 327
 328         INIT_WORK(&info->timer->work, idletimer_tg_work);
 329
 330         return 0;
 331
 332 out_free_attr:
 333         kfree(info->timer->attr.attr.name);
 334 out_free_timer:
 335         kfree(info->timer);
 336 out:
 337         return ret;
 338 }
 339
 340 static void reset_timer(const struct idletimer_tg_info *info,
 341                         struct sk_buff *skb)
 342 {
 343         unsigned long now = jiffies;
 344         struct idletimer_tg *timer = info->timer;
 345         bool timer_prev;
 346
 347         spin_lock_bh(&timestamp_lock);
 348         timer_prev = timer->active;
 349         timer->active = true;
 350         /* timer_prev is used to guard overflow problem in time_before*/
 351         if (!timer_prev || time_before(timer->timer.expires, now)) {
 352                 pr_debug("Starting Checkentry timer (Expired, Jiffies): %lu, %lu\n",
 353                                 timer->timer.expires, now);
 354
 355                 /* Stores the uid resposible for waking up the radio */
 356                 if (skb && (skb->sk)) {
 357                         timer->uid = from_kuid_munged(current_user_ns(),
 358                                                 sock_i_uid(skb->sk));
 359                 }
 360
 361                 /* checks if there is a pending inactive notification*/
 362                 if (timer->work_pending)
 363                         timer->delayed_timer_trigger = timer->last_modified_timer;
 364                 else {
 365                         timer->work_pending = true;
 366                         schedule_work(&timer->work);
 367                 }
 368         }
 369
 370         get_monotonic_boottime(&timer->last_modified_timer);
 371         mod_timer(&timer->timer,
 372                         msecs_to_jiffies(info->timeout * 1000) + now);
 373         spin_unlock_bh(&timestamp_lock);
 374 }
 375
 376 /*
 377  * The actual xt_tables plugin.
 378  */
 379 static unsigned int idletimer_tg_target(struct sk_buff *skb,
 380                                          const struct xt_action_param *par)
 381 {
 382         const struct idletimer_tg_info *info = par->targinfo;
 383         unsigned long now = jiffies;
 384
 385         pr_debug("resetting timer %s, timeout period %u\n",
 386                  info->label, info->timeout);
 387
 388         BUG_ON(!info->timer);
 389
 390         info->timer->active = true;
 391
 392         if (time_before(info->timer->timer.expires, now)) {
 393                 schedule_work(&info->timer->work);
 394                 pr_debug("Starting timer %s (Expired, Jiffies): %lu, %lu\n",
 395                          info->label, info->timer->timer.expires, now);
 396         }
 397
 398         /* TODO: Avoid modifying timers on each packet */
 399         reset_timer(info, skb);
 400         return XT_CONTINUE;
 401 }
 402
 403 static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
 404 {
 405         struct idletimer_tg_info *info = par->targinfo;
 406         int ret;
 407
 408         pr_debug("checkentry targinfo %s\n", info->label);
 409
 410         if (info->timeout == 0) {
 411                 pr_debug("timeout value is zero\n");
 412                 return -EINVAL;
 413         }
 414
 415         if (info->label[0] == '\0' ||
 416             strnlen(info->label,
 417                     MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) {
 418                 pr_debug("label is empty or not nul-terminated\n");
 419                 return -EINVAL;
 420         }
 421
 422         mutex_lock(&list_mutex);
 423
 424         info->timer = __idletimer_tg_find_by_label(info->label);
 425         if (info->timer) {
 426                 info->timer->refcnt++;
 427                 reset_timer(info, NULL);
 428                 pr_debug("increased refcnt of timer %s to %u\n",
 429                          info->label, info->timer->refcnt);
 430         } else {
 431                 ret = idletimer_tg_create(info);
 432                 if (ret < 0) {
 433                         pr_debug("failed to create timer\n");
 434                         mutex_unlock(&list_mutex);
 435                         return ret;
 436                 }
 437         }
 438
 439         mutex_unlock(&list_mutex);
 440
 441         return 0;
 442 }
 443
 444 static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
 445 {
 446         const struct idletimer_tg_info *info = par->targinfo;
 447
 448         pr_debug("destroy targinfo %s\n", info->label);
 449
 450         mutex_lock(&list_mutex);
 451
 452         if (--info->timer->refcnt == 0) {
 453                 pr_debug("deleting timer %s\n", info->label);
 454
 455                 list_del(&info->timer->entry);
 456                 del_timer_sync(&info->timer->timer);
 457                 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
 458                 unregister_pm_notifier(&info->timer->pm_nb);
 459                 kfree(info->timer->attr.attr.name);
 460                 kfree(info->timer);
 461         } else {
 462                 pr_debug("decreased refcnt of timer %s to %u\n",
 463                 info->label, info->timer->refcnt);
 464         }
 465
 466         mutex_unlock(&list_mutex);
 467 }
 468
 469 static struct xt_target idletimer_tg __read_mostly = {
 470         .name           = "IDLETIMER",
 471         .revision       = 1,
 472         .family         = NFPROTO_UNSPEC,
 473         .target         = idletimer_tg_target,
 474         .targetsize     = sizeof(struct idletimer_tg_info),
 475         .checkentry     = idletimer_tg_checkentry,
 476         .destroy        = idletimer_tg_destroy,
 477         .me             = THIS_MODULE,
 478 };
 479
 480 static struct class *idletimer_tg_class;
 481
 482 static struct device *idletimer_tg_device;
 483
 484 static int __init idletimer_tg_init(void)
 485 {
 486         int err;
 487
 488         idletimer_tg_class = class_create(THIS_MODULE, "xt_idletimer");
 489         err = PTR_ERR(idletimer_tg_class);
 490         if (IS_ERR(idletimer_tg_class)) {
 491                 pr_debug("couldn't register device class\n");
 492                 goto out;
 493         }
 494
 495         idletimer_tg_device = device_create(idletimer_tg_class, NULL,
 496                                             MKDEV(0, 0), NULL, "timers");
 497         err = PTR_ERR(idletimer_tg_device);
 498         if (IS_ERR(idletimer_tg_device)) {
 499                 pr_debug("couldn't register system device\n");
 500                 goto out_class;
 501         }
 502
 503         idletimer_tg_kobj = &idletimer_tg_device->kobj;
 504
 505         err =  xt_register_target(&idletimer_tg);
 506         if (err < 0) {
 507                 pr_debug("couldn't register xt target\n");
 508                 goto out_dev;
 509         }
 510
 511         return 0;
 512 out_dev:
 513         device_destroy(idletimer_tg_class, MKDEV(0, 0));
 514 out_class:
 515         class_destroy(idletimer_tg_class);
 516 out:
 517         return err;
 518 }
 519
 520 static void __exit idletimer_tg_exit(void)
 521 {
 522         xt_unregister_target(&idletimer_tg);
 523
 524         device_destroy(idletimer_tg_class, MKDEV(0, 0));
 525         class_destroy(idletimer_tg_class);
 526 }
 527
 528 module_init(idletimer_tg_init);
 529 module_exit(idletimer_tg_exit);
 530
 531 MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>");
 532 MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>");
 533 MODULE_DESCRIPTION("Xtables: idle time monitor");
 534 MODULE_LICENSE("GPL v2");
 535 MODULE_ALIAS("ipt_IDLETIMER");
 536 MODULE_ALIAS("ip6t_IDLETIMER");
 537 MODULE_ALIAS("arpt_IDLETIMER");