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 <[email protected]>
  10  *
  11  * Converted to x_tables and reworked for upstream inclusion
  12  * by Luciano Coelho <[email protected]>
  13  *
  14  * Contact: Luciano Coelho <[email protected]>
  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 sysfs_emit(buf, "%ld\n", time_diff);
  89
  90         return sysfs_emit(buf, "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 = kzalloc(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         if (info->send_nl_msg)
 350                 return -EOPNOTSUPP;
 351
 352         ret = idletimer_tg_helper((struct idletimer_tg_info *)info);
 353         if(ret < 0)
 354         {
 355                 pr_debug("checkentry helper return invalid\n");
 356                 return -EINVAL;
 357         }
 358
 359         if (info->timer_type > XT_IDLETIMER_ALARM) {
 360                 pr_debug("invalid value for timer type\n");
 361                 return -EINVAL;
 362         }
 363
 364         mutex_lock(&list_mutex);
 365
 366         info->timer = __idletimer_tg_find_by_label(info->label);
 367         if (info->timer) {
 368                 if (info->timer->timer_type != info->timer_type) {
 369                         pr_debug("Adding/Replacing rule with same label and different timer type is not allowed\n");
 370                         mutex_unlock(&list_mutex);
 371                         return -EINVAL;
 372                 }
 373
 374                 info->timer->refcnt++;
 375                 if (info->timer_type & XT_IDLETIMER_ALARM) {
 376                         /* calculate remaining expiry time */
 377                         ktime_t tout = alarm_expires_remaining(&info->timer->alarm);
 378                         struct timespec64 ktimespec = ktime_to_timespec64(tout);
 379
 380                         if (ktimespec.tv_sec > 0) {
 381                                 pr_debug("time_expiry_remaining %lld\n",
 382                                          ktimespec.tv_sec);
 383                                 alarm_start_relative(&info->timer->alarm, tout);
 384                         }
 385                 } else {
 386                                 mod_timer(&info->timer->timer,
 387                                         msecs_to_jiffies(info->timeout * 1000) + jiffies);
 388                 }
 389                 pr_debug("increased refcnt of timer %s to %u\n",
 390                          info->label, info->timer->refcnt);
 391         } else {
 392                 ret = idletimer_tg_create_v1(info);
 393                 if (ret < 0) {
 394                         pr_debug("failed to create timer\n");
 395                         mutex_unlock(&list_mutex);
 396                         return ret;
 397                 }
 398         }
 399
 400         mutex_unlock(&list_mutex);
 401         return 0;
 402 }
 403
 404 static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
 405 {
 406         const struct idletimer_tg_info *info = par->targinfo;
 407
 408         pr_debug("destroy targinfo %s\n", info->label);
 409
 410         mutex_lock(&list_mutex);
 411
 412         if (--info->timer->refcnt == 0) {
 413                 pr_debug("deleting timer %s\n", info->label);
 414
 415                 list_del(&info->timer->entry);
 416                 timer_shutdown_sync(&info->timer->timer);
 417                 cancel_work_sync(&info->timer->work);
 418                 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
 419                 kfree(info->timer->attr.attr.name);
 420                 kfree(info->timer);
 421         } else {
 422                 pr_debug("decreased refcnt of timer %s to %u\n",
 423                          info->label, info->timer->refcnt);
 424         }
 425
 426         mutex_unlock(&list_mutex);
 427 }
 428
 429 static void idletimer_tg_destroy_v1(const struct xt_tgdtor_param *par)
 430 {
 431         const struct idletimer_tg_info_v1 *info = par->targinfo;
 432
 433         pr_debug("destroy targinfo %s\n", info->label);
 434
 435         mutex_lock(&list_mutex);
 436
 437         if (--info->timer->refcnt == 0) {
 438                 pr_debug("deleting timer %s\n", info->label);
 439
 440                 list_del(&info->timer->entry);
 441                 if (info->timer->timer_type & XT_IDLETIMER_ALARM) {
 442                         alarm_cancel(&info->timer->alarm);
 443                 } else {
 444                         timer_shutdown_sync(&info->timer->timer);
 445                 }
 446                 cancel_work_sync(&info->timer->work);
 447                 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
 448                 kfree(info->timer->attr.attr.name);
 449                 kfree(info->timer);
 450         } else {
 451                 pr_debug("decreased refcnt of timer %s to %u\n",
 452                          info->label, info->timer->refcnt);
 453         }
 454
 455         mutex_unlock(&list_mutex);
 456 }
 457
 458
 459 static struct xt_target idletimer_tg[] __read_mostly = {
 460         {
 461         .name           = "IDLETIMER",
 462         .family         = NFPROTO_UNSPEC,
 463         .target         = idletimer_tg_target,
 464         .targetsize     = sizeof(struct idletimer_tg_info),
 465         .usersize       = offsetof(struct idletimer_tg_info, timer),
 466         .checkentry     = idletimer_tg_checkentry,
 467         .destroy        = idletimer_tg_destroy,
 468         .me             = THIS_MODULE,
 469         },
 470         {
 471         .name           = "IDLETIMER",
 472         .family         = NFPROTO_UNSPEC,
 473         .revision       = 1,
 474         .target         = idletimer_tg_target_v1,
 475         .targetsize     = sizeof(struct idletimer_tg_info_v1),
 476         .usersize       = offsetof(struct idletimer_tg_info_v1, timer),
 477         .checkentry     = idletimer_tg_checkentry_v1,
 478         .destroy        = idletimer_tg_destroy_v1,
 479         .me             = THIS_MODULE,
 480         },
 481
 482
 483 };
 484
 485 static struct class *idletimer_tg_class;
 486
 487 static struct device *idletimer_tg_device;
 488
 489 static int __init idletimer_tg_init(void)
 490 {
 491         int err;
 492
 493         idletimer_tg_class = class_create("xt_idletimer");
 494         err = PTR_ERR(idletimer_tg_class);
 495         if (IS_ERR(idletimer_tg_class)) {
 496                 pr_debug("couldn't register device class\n");
 497                 goto out;
 498         }
 499
 500         idletimer_tg_device = device_create(idletimer_tg_class, NULL,
 501                                             MKDEV(0, 0), NULL, "timers");
 502         err = PTR_ERR(idletimer_tg_device);
 503         if (IS_ERR(idletimer_tg_device)) {
 504                 pr_debug("couldn't register system device\n");
 505                 goto out_class;
 506         }
 507
 508         idletimer_tg_kobj = &idletimer_tg_device->kobj;
 509
 510         err = xt_register_targets(idletimer_tg, ARRAY_SIZE(idletimer_tg));
 511
 512         if (err < 0) {
 513                 pr_debug("couldn't register xt target\n");
 514                 goto out_dev;
 515         }
 516
 517         return 0;
 518 out_dev:
 519         device_destroy(idletimer_tg_class, MKDEV(0, 0));
 520 out_class:
 521         class_destroy(idletimer_tg_class);
 522 out:
 523         return err;
 524 }
 525
 526 static void __exit idletimer_tg_exit(void)
 527 {
 528         xt_unregister_targets(idletimer_tg, ARRAY_SIZE(idletimer_tg));
 529
 530         device_destroy(idletimer_tg_class, MKDEV(0, 0));
 531         class_destroy(idletimer_tg_class);
 532 }
 533
 534 module_init(idletimer_tg_init);
 535 module_exit(idletimer_tg_exit);
 536
 537 MODULE_AUTHOR("Timo Teras <[email protected]>");
 538 MODULE_AUTHOR("Luciano Coelho <[email protected]>");
 539 MODULE_DESCRIPTION("Xtables: idle time monitor");
 540 MODULE_LICENSE("GPL v2");
 541 MODULE_ALIAS("ipt_IDLETIMER");
 542 MODULE_ALIAS("ip6t_IDLETIMER");