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         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
 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(&timestamp_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(&timestamp_lock);
 377 }
 378
 379 /*
 380  * The actual xt_tables plugin.
 381  */
 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
 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
 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
 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
 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");