net/netfilter/xt_IDLETIMER.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/net/netfilter/xt_IDLETIMER.c
   4  *
   5  * Netfilter module to trigger a timer when packet matches.
   6  * After timer expires a kevent will be sent.
   7  *
   8  * Copyright (C) 2004, 2010 Nokia Corporation
   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
  17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19 #include <linux/module.h>
  20 #include <linux/timer.h>
  21 #include <linux/alarmtimer.h>
  22 #include <linux/list.h>
  23 #include <linux/mutex.h>
  24 #include <linux/netfilter.h>
  25 #include <linux/netfilter/x_tables.h>
  26 #include <linux/netfilter/xt_IDLETIMER.h>
  27 #include <linux/kdev_t.h>
  28 #include <linux/kobject.h>
  29 #include <linux/workqueue.h>
  30 #include <linux/sysfs.h>
  31
  32 struct idletimer_tg {
  33         struct list_head entry;
  34         struct alarm alarm;
  35         struct timer_list timer;
  36         struct work_struct work;
  37
  38         struct kobject *kobj;
  39         struct device_attribute attr;
  40
  41         unsigned int refcnt;
  42         u8 timer_type;
  43 };
  44
  45 static LIST_HEAD(idletimer_tg_list);
  46 static DEFINE_MUTEX(list_mutex);
  47
  48 static struct kobject *idletimer_tg_kobj;
  49
  50 static
  51 struct idletimer_tg *__idletimer_tg_find_by_label(const char *label)
  52 {
  53         struct idletimer_tg *entry;
  54
  55         list_for_each_entry(entry, &idletimer_tg_list, entry) {
  56                 if (!strcmp(label, entry->attr.attr.name))
  57                         return entry;
  58         }
  59
  60         return NULL;
  61 }
  62
  63 static ssize_t idletimer_tg_show(struct device *dev,
  64                                  struct device_attribute *attr, char *buf)
  65 {
  66         struct idletimer_tg *timer;
  67         unsigned long expires = 0;
  68         struct timespec64 ktimespec = {};
  69         long time_diff = 0;
  70
  71         mutex_lock(&list_mutex);
  72
  73         timer = __idletimer_tg_find_by_label(attr->attr.name);
  74         if (timer) {
  75                 if (timer->timer_type & XT_IDLETIMER_ALARM) {
  76                         ktime_t expires_alarm = alarm_expires_remaining(&timer->alarm);
  77                         ktimespec = ktime_to_timespec64(expires_alarm);
  78                         time_diff = ktimespec.tv_sec;
  79                 } else {
  80                         expires = timer->timer.expires;
  81                         time_diff = jiffies_to_msecs(expires - jiffies) / 1000;
  82                 }
  83         }
  84
  85         mutex_unlock(&list_mutex);
  86
  87         if (time_after(expires, jiffies) || ktimespec.tv_sec > 0)
  88                 return snprintf(buf, PAGE_SIZE, "%ld\n", time_diff);
  89
  90         return snprintf(buf, PAGE_SIZE, "0\n");
  91 }
  92
  93 static void idletimer_tg_work(struct work_struct *work)
  94 {
  95         struct idletimer_tg *timer = container_of(work, struct idletimer_tg,
  96                                                   work);
  97
  98         sysfs_notify(idletimer_tg_kobj, NULL, timer->attr.attr.name);
  99 }
 100
 101 static void idletimer_tg_expired(struct timer_list *t)
 102 {
 103         struct idletimer_tg *timer = from_timer(timer, t, timer);
 104
 105         pr_debug("timer %s expired\n", timer->attr.attr.name);
 106
 107         schedule_work(&timer->work);
 108 }
 109
 110 static enum alarmtimer_restart idletimer_tg_alarmproc(struct alarm *alarm,
 111                                                           ktime_t now)
 112 {
 113         struct idletimer_tg *timer = alarm->data;
 114
 115         pr_debug("alarm %s expired\n", timer->attr.attr.name);
 116         schedule_work(&timer->work);
 117         return ALARMTIMER_NORESTART;
 118 }
 119
 120 static int idletimer_check_sysfs_name(const char *name, unsigned int size)
 121 {
 122         int ret;
 123
 124         ret = xt_check_proc_name(name, size);
 125         if (ret < 0)
 126                 return ret;
 127
 128         if (!strcmp(name, "power") ||
 129             !strcmp(name, "subsystem") ||
 130             !strcmp(name, "uevent"))
 131                 return -EINVAL;
 132
 133         return 0;
 134 }
 135
 136 static int idletimer_tg_create(struct idletimer_tg_info *info)
 137 {
 138         int ret;
 139
 140         info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL);
 141         if (!info->timer) {
 142                 ret = -ENOMEM;
 143                 goto out;
 144         }
 145
 146         ret = idletimer_check_sysfs_name(info->label, sizeof(info->label));
 147         if (ret < 0)
 148                 goto out_free_timer;
 149
 150         sysfs_attr_init(&info->timer->attr.attr);
 151         info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);
 152         if (!info->timer->attr.attr.name) {
 153                 ret = -ENOMEM;
 154                 goto out_free_timer;
 155         }
 156         info->timer->attr.attr.mode = 0444;
 157         info->timer->attr.show = idletimer_tg_show;
 158
 159         ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr);
 160         if (ret < 0) {
 161                 pr_debug("couldn't add file to sysfs");
 162                 goto out_free_attr;
 163         }
 164
 165         list_add(&info->timer->entry, &idletimer_tg_list);
 166
 167         timer_setup(&info->timer->timer, idletimer_tg_expired, 0);
 168         info->timer->refcnt = 1;
 169
 170         INIT_WORK(&info->timer->work, idletimer_tg_work);
 171
 172         mod_timer(&info->timer->timer,
 173                   msecs_to_jiffies(info->timeout * 1000) + jiffies);
 174
 175         return 0;
 176
 177 out_free_attr:
 178         kfree(info->timer->attr.attr.name);
 179 out_free_timer:
 180         kfree(info->timer);
 181 out:
 182         return ret;
 183 }
 184
 185 static int idletimer_tg_create_v1(struct idletimer_tg_info_v1 *info)
 186 {
 187         int ret;
 188
 189         info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL);
 190         if (!info->timer) {
 191                 ret = -ENOMEM;
 192                 goto out;
 193         }
 194
 195         ret = idletimer_check_sysfs_name(info->label, sizeof(info->label));
 196         if (ret < 0)
 197                 goto out_free_timer;
 198
 199         sysfs_attr_init(&info->timer->attr.attr);
 200         info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);
 201         if (!info->timer->attr.attr.name) {
 202                 ret = -ENOMEM;
 203                 goto out_free_timer;
 204         }
 205         info->timer->attr.attr.mode = 0444;
 206         info->timer->attr.show = idletimer_tg_show;
 207
 208         ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr);
 209         if (ret < 0) {
 210                 pr_debug("couldn't add file to sysfs");
 211                 goto out_free_attr;
 212         }
 213
 214         /*  notify userspace  */
 215         kobject_uevent(idletimer_tg_kobj,KOBJ_ADD);
 216
 217         list_add(&info->timer->entry, &idletimer_tg_list);
 218         pr_debug("timer type value is %u", info->timer_type);
 219         info->timer->timer_type = info->timer_type;
 220         info->timer->refcnt = 1;
 221
 222         INIT_WORK(&info->timer->work, idletimer_tg_work);
 223
 224         if (info->timer->timer_type & XT_IDLETIMER_ALARM) {
 225                 ktime_t tout;
 226                 alarm_init(&info->timer->alarm, ALARM_BOOTTIME,
 227                            idletimer_tg_alarmproc);
 228                 info->timer->alarm.data = info->timer;
 229                 tout = ktime_set(info->timeout, 0);
 230                 alarm_start_relative(&info->timer->alarm, tout);
 231         } else {
 232                 timer_setup(&info->timer->timer, idletimer_tg_expired, 0);
 233                 mod_timer(&info->timer->timer,
 234                                 msecs_to_jiffies(info->timeout * 1000) + jiffies);
 235         }
 236
 237         return 0;
 238
 239 out_free_attr:
 240         kfree(info->timer->attr.attr.name);
 241 out_free_timer:
 242         kfree(info->timer);
 243 out:
 244         return ret;
 245 }
 246
 247 /*
 248  * The actual xt_tables plugin.
 249  */
 250 static unsigned int idletimer_tg_target(struct sk_buff *skb,
 251                                          const struct xt_action_param *par)
 252 {
 253         const struct idletimer_tg_info *info = par->targinfo;
 254
 255         pr_debug("resetting timer %s, timeout period %u\n",
 256                  info->label, info->timeout);
 257
 258         mod_timer(&info->timer->timer,
 259                   msecs_to_jiffies(info->timeout * 1000) + jiffies);
 260
 261         return XT_CONTINUE;
 262 }
 263
 264 /*
 265  * The actual xt_tables plugin.
 266  */
 267 static unsigned int idletimer_tg_target_v1(struct sk_buff *skb,
 268                                          const struct xt_action_param *par)
 269 {
 270         const struct idletimer_tg_info_v1 *info = par->targinfo;
 271
 272         pr_debug("resetting timer %s, timeout period %u\n",
 273                  info->label, info->timeout);
 274
 275         if (info->timer->timer_type & XT_IDLETIMER_ALARM) {
 276                 ktime_t tout = ktime_set(info->timeout, 0);
 277                 alarm_start_relative(&info->timer->alarm, tout);
 278         } else {
 279                 mod_timer(&info->timer->timer,
 280                                 msecs_to_jiffies(info->timeout * 1000) + jiffies);
 281         }
 282
 283         return XT_CONTINUE;
 284 }
 285
 286 static int idletimer_tg_helper(struct idletimer_tg_info *info)
 287 {
 288         if (info->timeout == 0) {
 289                 pr_debug("timeout value is zero\n");
 290                 return -EINVAL;
 291         }
 292         if (info->timeout >= INT_MAX / 1000) {
 293                 pr_debug("timeout value is too big\n");
 294                 return -EINVAL;
 295         }
 296         if (info->label[0] == '\0' ||
 297             strnlen(info->label,
 298                     MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) {
 299                 pr_debug("label is empty or not nul-terminated\n");
 300                 return -EINVAL;
 301         }
 302         return 0;
 303 }
 304
 305
 306 static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
 307 {
 308         struct idletimer_tg_info *info = par->targinfo;
 309         int ret;
 310
 311         pr_debug("checkentry targinfo%s\n", info->label);
 312
 313         ret = idletimer_tg_helper(info);
 314         if(ret < 0)
 315         {
 316                 pr_debug("checkentry helper return invalid\n");
 317                 return -EINVAL;
 318         }
 319         mutex_lock(&list_mutex);
 320
 321         info->timer = __idletimer_tg_find_by_label(info->label);
 322         if (info->timer) {
 323                 info->timer->refcnt++;
 324                 mod_timer(&info->timer->timer,
 325                           msecs_to_jiffies(info->timeout * 1000) + jiffies);
 326
 327                 pr_debug("increased refcnt of timer %s to %u\n",
 328                          info->label, info->timer->refcnt);
 329         } else {
 330                 ret = idletimer_tg_create(info);
 331                 if (ret < 0) {
 332                         pr_debug("failed to create timer\n");
 333                         mutex_unlock(&list_mutex);
 334                         return ret;
 335                 }
 336         }
 337
 338         mutex_unlock(&list_mutex);
 339         return 0;
 340 }
 341
 342 static int idletimer_tg_checkentry_v1(const struct xt_tgchk_param *par)
 343 {
 344         struct idletimer_tg_info_v1 *info = par->targinfo;
 345         int ret;
 346
 347         pr_debug("checkentry targinfo%s\n", info->label);
 348
 349         ret = idletimer_tg_helper((struct idletimer_tg_info *)info);
 350         if(ret < 0)
 351         {
 352                 pr_debug("checkentry helper return invalid\n");
 353                 return -EINVAL;
 354         }
 355
 356         if (info->timer_type > XT_IDLETIMER_ALARM) {
 357                 pr_debug("invalid value for timer type\n");
 358                 return -EINVAL;
 359         }
 360
 361         mutex_lock(&list_mutex);
 362
 363         info->timer = __idletimer_tg_find_by_label(info->label);
 364         if (info->timer) {
 365                 if (info->timer->timer_type != info->timer_type) {
 366                         pr_debug("Adding/Replacing rule with same label and different timer type is not allowed\n");
 367                         mutex_unlock(&list_mutex);
 368                         return -EINVAL;
 369                 }
 370
 371                 info->timer->refcnt++;
 372                 if (info->timer_type & XT_IDLETIMER_ALARM) {
 373                         /* calculate remaining expiry time */
 374                         ktime_t tout = alarm_expires_remaining(&info->timer->alarm);
 375                         struct timespec64 ktimespec = ktime_to_timespec64(tout);
 376
 377                         if (ktimespec.tv_sec > 0) {
 378                                 pr_debug("time_expiry_remaining %lld\n",
 379                                          ktimespec.tv_sec);
 380                                 alarm_start_relative(&info->timer->alarm, tout);
 381                         }
 382                 } else {
 383                                 mod_timer(&info->timer->timer,
 384                                         msecs_to_jiffies(info->timeout * 1000) + jiffies);
 385                 }
 386                 pr_debug("increased refcnt of timer %s to %u\n",
 387                          info->label, info->timer->refcnt);
 388         } else {
 389                 ret = idletimer_tg_create_v1(info);
 390                 if (ret < 0) {
 391                         pr_debug("failed to create timer\n");
 392                         mutex_unlock(&list_mutex);
 393                         return ret;
 394                 }
 395         }
 396
 397         mutex_unlock(&list_mutex);
 398         return 0;
 399 }
 400
 401 static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
 402 {
 403         const struct idletimer_tg_info *info = par->targinfo;
 404
 405         pr_debug("destroy targinfo %s\n", info->label);
 406
 407         mutex_lock(&list_mutex);
 408
 409         if (--info->timer->refcnt == 0) {
 410                 pr_debug("deleting timer %s\n", info->label);
 411
 412                 list_del(&info->timer->entry);
 413                 del_timer_sync(&info->timer->timer);
 414                 cancel_work_sync(&info->timer->work);
 415                 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
 416                 kfree(info->timer->attr.attr.name);
 417                 kfree(info->timer);
 418         } else {
 419                 pr_debug("decreased refcnt of timer %s to %u\n",
 420                          info->label, info->timer->refcnt);
 421         }
 422
 423         mutex_unlock(&list_mutex);
 424 }
 425
 426 static void idletimer_tg_destroy_v1(const struct xt_tgdtor_param *par)
 427 {
 428         const struct idletimer_tg_info_v1 *info = par->targinfo;
 429
 430         pr_debug("destroy targinfo %s\n", info->label);
 431
 432         mutex_lock(&list_mutex);
 433
 434         if (--info->timer->refcnt == 0) {
 435                 pr_debug("deleting timer %s\n", info->label);
 436
 437                 list_del(&info->timer->entry);
 438                 if (info->timer->timer_type & XT_IDLETIMER_ALARM) {
 439                         alarm_cancel(&info->timer->alarm);
 440                 } else {
 441                         del_timer_sync(&info->timer->timer);
 442                 }
 443                 cancel_work_sync(&info->timer->work);
 444                 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
 445                 kfree(info->timer->attr.attr.name);
 446                 kfree(info->timer);
 447         } else {
 448                 pr_debug("decreased refcnt of timer %s to %u\n",
 449                          info->label, info->timer->refcnt);
 450         }
 451
 452         mutex_unlock(&list_mutex);
 453 }
 454
 455
 456 static struct xt_target idletimer_tg[] __read_mostly = {
 457         {
 458         .name           = "IDLETIMER",
 459         .family         = NFPROTO_UNSPEC,
 460         .target         = idletimer_tg_target,
 461         .targetsize     = sizeof(struct idletimer_tg_info),
 462         .usersize       = offsetof(struct idletimer_tg_info, timer),
 463         .checkentry     = idletimer_tg_checkentry,
 464         .destroy        = idletimer_tg_destroy,
 465         .me             = THIS_MODULE,
 466         },
 467         {
 468         .name           = "IDLETIMER",
 469         .family         = NFPROTO_UNSPEC,
 470         .revision       = 1,
 471         .target         = idletimer_tg_target_v1,
 472         .targetsize     = sizeof(struct idletimer_tg_info_v1),
 473         .usersize       = offsetof(struct idletimer_tg_info_v1, timer),
 474         .checkentry     = idletimer_tg_checkentry_v1,
 475         .destroy        = idletimer_tg_destroy_v1,
 476         .me             = THIS_MODULE,
 477         },
 478
 479
 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_targets(idletimer_tg, ARRAY_SIZE(idletimer_tg));
 508
 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_targets(idletimer_tg, ARRAY_SIZE(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");