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 #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
  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(&timestamp_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(&timestamp_lock);
 115         return state;
 116 }
 117
 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
 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
 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
 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
 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(&timestamp_lock);
 230         timer->active = false;
 231         timer->work_pending = true;
 232         schedule_work(&timer->work);
 233         spin_unlock_bh(&timestamp_lock);
 234 }
 235
 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(&timestamp_lock);
 251                 if (!timer->active) {
 252                         spin_unlock_bh(&timestamp_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(&timestamp_lock);
 273                 break;
 274         default:
 275                 break;
 276         }
 277         return NOTIFY_DONE;
 278 }
 279
 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         mod_timer(&info->timer->timer,
 327                   msecs_to_jiffies(info->timeout * 1000) + jiffies);
 328
 329         INIT_WORK(&info->timer->work, idletimer_tg_work);
 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
 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(&timestamp_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(&timestamp_lock);
 375 }
 376
 377 /*
 378  * The actual xt_tables plugin.
 379  */
 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
 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
 416         if (info->label[0] == '\0' ||
 417             strnlen(info->label,
 418                     MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) {
 419                 pr_debug("label is empty or not nul-terminated\n");
 420                 return -EINVAL;
 421         }
 422
 423         mutex_lock(&list_mutex);
 424
 425         info->timer = __idletimer_tg_find_by_label(info->label);
 426         if (info->timer) {
 427                 info->timer->refcnt++;
 428                 reset_timer(info, NULL);
 429                 pr_debug("increased refcnt of timer %s to %u\n",
 430                          info->label, info->timer->refcnt);
 431         } else {
 432                 ret = idletimer_tg_create(info);
 433                 if (ret < 0) {
 434                         pr_debug("failed to create timer\n");
 435                         mutex_unlock(&list_mutex);
 436                         return ret;
 437                 }
 438         }
 439
 440         mutex_unlock(&list_mutex);
 441
 442         return 0;
 443 }
 444
 445 static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
 446 {
 447         const struct idletimer_tg_info *info = par->targinfo;
 448
 449         pr_debug("destroy targinfo %s\n", info->label);
 450
 451         mutex_lock(&list_mutex);
 452
 453         if (--info->timer->refcnt == 0) {
 454                 pr_debug("deleting timer %s\n", info->label);
 455
 456                 list_del(&info->timer->entry);
 457                 del_timer_sync(&info->timer->timer);
 458                 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
 459                 unregister_pm_notifier(&info->timer->pm_nb);
 460                 cancel_work_sync(&info->timer->work);
 461                 kfree(info->timer->attr.attr.name);
 462                 kfree(info->timer);
 463         } else {
 464                 pr_debug("decreased refcnt of timer %s to %u\n",
 465                 info->label, info->timer->refcnt);
 466         }
 467
 468         mutex_unlock(&list_mutex);
 469 }
 470
 471 static struct xt_target idletimer_tg __read_mostly = {
 472         .name           = "IDLETIMER",
 473         .revision       = 1,
 474         .family         = NFPROTO_UNSPEC,
 475         .target         = idletimer_tg_target,
 476         .targetsize     = sizeof(struct idletimer_tg_info),
 477         .checkentry     = idletimer_tg_checkentry,
 478         .destroy        = idletimer_tg_destroy,
 479         .me             = THIS_MODULE,
 480 };
 481
 482 static struct class *idletimer_tg_class;
 483
 484 static struct device *idletimer_tg_device;
 485
 486 static int __init idletimer_tg_init(void)
 487 {
 488         int err;
 489
 490         idletimer_tg_class = class_create(THIS_MODULE, "xt_idletimer");
 491         err = PTR_ERR(idletimer_tg_class);
 492         if (IS_ERR(idletimer_tg_class)) {
 493                 pr_debug("couldn't register device class\n");
 494                 goto out;
 495         }
 496
 497         idletimer_tg_device = device_create(idletimer_tg_class, NULL,
 498                                             MKDEV(0, 0), NULL, "timers");
 499         err = PTR_ERR(idletimer_tg_device);
 500         if (IS_ERR(idletimer_tg_device)) {
 501                 pr_debug("couldn't register system device\n");
 502                 goto out_class;
 503         }
 504
 505         idletimer_tg_kobj = &idletimer_tg_device->kobj;
 506
 507         err =  xt_register_target(&idletimer_tg);
 508         if (err < 0) {
 509                 pr_debug("couldn't register xt target\n");
 510                 goto out_dev;
 511         }
 512
 513         return 0;
 514 out_dev:
 515         device_destroy(idletimer_tg_class, MKDEV(0, 0));
 516 out_class:
 517         class_destroy(idletimer_tg_class);
 518 out:
 519         return err;
 520 }
 521
 522 static void __exit idletimer_tg_exit(void)
 523 {
 524         xt_unregister_target(&idletimer_tg);
 525
 526         device_destroy(idletimer_tg_class, MKDEV(0, 0));
 527         class_destroy(idletimer_tg_class);
 528 }
 529
 530 module_init(idletimer_tg_init);
 531 module_exit(idletimer_tg_exit);
 532
 533 MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>");
 534 MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>");
 535 MODULE_DESCRIPTION("Xtables: idle time monitor");
 536 MODULE_LICENSE("GPL v2");
 537 MODULE_ALIAS("ipt_IDLETIMER");
 538 MODULE_ALIAS("ip6t_IDLETIMER");
 539 MODULE_ALIAS("arpt_IDLETIMER");