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