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 53struct idletimer_tg_attr { 54 struct attribute attr; 55 ssize_t (*show)(struct kobject *kobj, 56 struct attribute *attr, char *buf); 57}; 58 59struct 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 80static LIST_HEAD(idletimer_tg_list); 81static DEFINE_MUTEX(list_mutex); 82static DEFINE_SPINLOCK(timestamp_lock); 83 84static struct kobject *idletimer_tg_kobj; 85 86static 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(×tamp_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(×tamp_lock); 114 return state; 115} 116 117static 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 171static 172struct 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 186static 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 212static 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 223static 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(×tamp_lock); 229 timer->active = false; 230 timer->work_pending = true; 231 schedule_work(&timer->work); 232 spin_unlock_bh(×tamp_lock); 233} 234 235static 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(×tamp_lock); 250 if (!timer->active) { 251 spin_unlock_bh(×tamp_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(×tamp_lock); 272 break; 273 default: 274 break; 275 } 276 return NOTIFY_DONE; 277} 278 279static 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 sysfs_attr_init(&info->timer->attr.attr); 290 info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL); 291 if (!info->timer->attr.attr.name) { 292 ret = -ENOMEM; 293 goto out_free_timer; 294 } 295 info->timer->attr.attr.mode = S_IRUGO; 296 info->timer->attr.show = idletimer_tg_show; 297 298 ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr); 299 if (ret < 0) { 300 pr_debug("couldn't add file to sysfs"); 301 goto out_free_attr; 302 } 303 304 list_add(&info->timer->entry, &idletimer_tg_list); 305 306 setup_timer(&info->timer->timer, idletimer_tg_expired, 307 (unsigned long) info->timer); 308 info->timer->refcnt = 1; 309 info->timer->send_nl_msg = (info->send_nl_msg == 0) ? false : true; 310 info->timer->active = true; 311 info->timer->timeout = info->timeout; 312 313 info->timer->delayed_timer_trigger.tv_sec = 0; 314 info->timer->delayed_timer_trigger.tv_nsec = 0; 315 info->timer->work_pending = false; 316 info->timer->uid = 0; 317 get_monotonic_boottime(&info->timer->last_modified_timer); 318 319 info->timer->pm_nb.notifier_call = idletimer_resume; 320 ret = register_pm_notifier(&info->timer->pm_nb); 321 if (ret) 322 printk(KERN_WARNING "[%s] Failed to register pm notifier %d\n", 323 __func__, ret); 324 325 mod_timer(&info->timer->timer, 326 msecs_to_jiffies(info->timeout * 1000) + jiffies); 327 328 INIT_WORK(&info->timer->work, idletimer_tg_work); 329 330 return 0; 331 332out_free_attr: 333 kfree(info->timer->attr.attr.name); 334out_free_timer: 335 kfree(info->timer); 336out: 337 return ret; 338} 339 340static void reset_timer(const struct idletimer_tg_info *info, 341 struct sk_buff *skb) 342{ 343 unsigned long now = jiffies; 344 struct idletimer_tg *timer = info->timer; 345 bool timer_prev; 346 347 spin_lock_bh(×tamp_lock); 348 timer_prev = timer->active; 349 timer->active = true; 350 /* timer_prev is used to guard overflow problem in time_before*/ 351 if (!timer_prev || time_before(timer->timer.expires, now)) { 352 pr_debug("Starting Checkentry timer (Expired, Jiffies): %lu, %lu\n", 353 timer->timer.expires, now); 354 355 /* Stores the uid resposible for waking up the radio */ 356 if (skb && (skb->sk)) { 357 timer->uid = from_kuid_munged(current_user_ns(), 358 sock_i_uid(skb->sk)); 359 } 360 361 /* checks if there is a pending inactive notification*/ 362 if (timer->work_pending) 363 timer->delayed_timer_trigger = timer->last_modified_timer; 364 else { 365 timer->work_pending = true; 366 schedule_work(&timer->work); 367 } 368 } 369 370 get_monotonic_boottime(&timer->last_modified_timer); 371 mod_timer(&timer->timer, 372 msecs_to_jiffies(info->timeout * 1000) + now); 373 spin_unlock_bh(×tamp_lock); 374} 375 376/* 377 * The actual xt_tables plugin. 378 */ 379static unsigned int idletimer_tg_target(struct sk_buff *skb, 380 const struct xt_action_param *par) 381{ 382 const struct idletimer_tg_info *info = par->targinfo; 383 unsigned long now = jiffies; 384 385 pr_debug("resetting timer %s, timeout period %u\n", 386 info->label, info->timeout); 387 388 BUG_ON(!info->timer); 389 390 info->timer->active = true; 391 392 if (time_before(info->timer->timer.expires, now)) { 393 schedule_work(&info->timer->work); 394 pr_debug("Starting timer %s (Expired, Jiffies): %lu, %lu\n", 395 info->label, info->timer->timer.expires, now); 396 } 397 398 /* TODO: Avoid modifying timers on each packet */ 399 reset_timer(info, skb); 400 return XT_CONTINUE; 401} 402 403static int idletimer_tg_checkentry(const struct xt_tgchk_param *par) 404{ 405 struct idletimer_tg_info *info = par->targinfo; 406 int ret; 407 408 pr_debug("checkentry targinfo %s\n", info->label); 409 410 if (info->timeout == 0) { 411 pr_debug("timeout value is zero\n"); 412 return -EINVAL; 413 } 414 415 if (info->label[0] == '\0' || 416 strnlen(info->label, 417 MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) { 418 pr_debug("label is empty or not nul-terminated\n"); 419 return -EINVAL; 420 } 421 422 mutex_lock(&list_mutex); 423 424 info->timer = __idletimer_tg_find_by_label(info->label); 425 if (info->timer) { 426 info->timer->refcnt++; 427 reset_timer(info, NULL); 428 pr_debug("increased refcnt of timer %s to %u\n", 429 info->label, info->timer->refcnt); 430 } else { 431 ret = idletimer_tg_create(info); 432 if (ret < 0) { 433 pr_debug("failed to create timer\n"); 434 mutex_unlock(&list_mutex); 435 return ret; 436 } 437 } 438 439 mutex_unlock(&list_mutex); 440 441 return 0; 442} 443 444static void idletimer_tg_destroy(const struct xt_tgdtor_param *par) 445{ 446 const struct idletimer_tg_info *info = par->targinfo; 447 448 pr_debug("destroy targinfo %s\n", info->label); 449 450 mutex_lock(&list_mutex); 451 452 if (--info->timer->refcnt == 0) { 453 pr_debug("deleting timer %s\n", info->label); 454 455 list_del(&info->timer->entry); 456 del_timer_sync(&info->timer->timer); 457 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr); 458 unregister_pm_notifier(&info->timer->pm_nb); 459 kfree(info->timer->attr.attr.name); 460 kfree(info->timer); 461 } else { 462 pr_debug("decreased refcnt of timer %s to %u\n", 463 info->label, info->timer->refcnt); 464 } 465 466 mutex_unlock(&list_mutex); 467} 468 469static struct xt_target idletimer_tg __read_mostly = { 470 .name = "IDLETIMER", 471 .revision = 1, 472 .family = NFPROTO_UNSPEC, 473 .target = idletimer_tg_target, 474 .targetsize = sizeof(struct idletimer_tg_info), 475 .checkentry = idletimer_tg_checkentry, 476 .destroy = idletimer_tg_destroy, 477 .me = THIS_MODULE, 478}; 479 480static struct class *idletimer_tg_class; 481 482static struct device *idletimer_tg_device; 483 484static int __init idletimer_tg_init(void) 485{ 486 int err; 487 488 idletimer_tg_class = class_create(THIS_MODULE, "xt_idletimer"); 489 err = PTR_ERR(idletimer_tg_class); 490 if (IS_ERR(idletimer_tg_class)) { 491 pr_debug("couldn't register device class\n"); 492 goto out; 493 } 494 495 idletimer_tg_device = device_create(idletimer_tg_class, NULL, 496 MKDEV(0, 0), NULL, "timers"); 497 err = PTR_ERR(idletimer_tg_device); 498 if (IS_ERR(idletimer_tg_device)) { 499 pr_debug("couldn't register system device\n"); 500 goto out_class; 501 } 502 503 idletimer_tg_kobj = &idletimer_tg_device->kobj; 504 505 err = xt_register_target(&idletimer_tg); 506 if (err < 0) { 507 pr_debug("couldn't register xt target\n"); 508 goto out_dev; 509 } 510 511 return 0; 512out_dev: 513 device_destroy(idletimer_tg_class, MKDEV(0, 0)); 514out_class: 515 class_destroy(idletimer_tg_class); 516out: 517 return err; 518} 519 520static void __exit idletimer_tg_exit(void) 521{ 522 xt_unregister_target(&idletimer_tg); 523 524 device_destroy(idletimer_tg_class, MKDEV(0, 0)); 525 class_destroy(idletimer_tg_class); 526} 527 528module_init(idletimer_tg_init); 529module_exit(idletimer_tg_exit); 530 531MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>"); 532MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>"); 533MODULE_DESCRIPTION("Xtables: idle time monitor"); 534MODULE_LICENSE("GPL v2"); 535MODULE_ALIAS("ipt_IDLETIMER"); 536MODULE_ALIAS("ip6t_IDLETIMER"); 537MODULE_ALIAS("arpt_IDLETIMER"); 538