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 * Written by Timo Teras <ext-timo.teras@nokia.com> 9 * 10 * Converted to x_tables and reworked for upstream inclusion 11 * by Luciano Coelho <luciano.coelho@nokia.com> 12 * 13 * Contact: Luciano Coelho <luciano.coelho@nokia.com> 14 * 15 * This program is free software; you can redistribute it and/or 16 * modify it under the terms of the GNU General Public License 17 * version 2 as published by the Free Software Foundation. 18 * 19 * This program is distributed in the hope that it will be useful, but 20 * WITHOUT ANY WARRANTY; without even the implied warranty of 21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 22 * General Public License for more details. 23 * 24 * You should have received a copy of the GNU General Public License 25 * along with this program; if not, write to the Free Software 26 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 27 * 02110-1301 USA 28 */ 29 30#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 31 32#include <linux/module.h> 33#include <linux/timer.h> 34#include <linux/list.h> 35#include <linux/mutex.h> 36#include <linux/netfilter.h> 37#include <linux/netfilter/x_tables.h> 38#include <linux/netfilter/xt_IDLETIMER.h> 39#include <linux/kdev_t.h> 40#include <linux/kobject.h> 41#include <linux/workqueue.h> 42#include <linux/sysfs.h> 43 44struct idletimer_tg_attr { 45 struct attribute attr; 46 ssize_t (*show)(struct kobject *kobj, 47 struct attribute *attr, char *buf); 48}; 49 50struct idletimer_tg { 51 struct list_head entry; 52 struct timer_list timer; 53 struct work_struct work; 54 55 struct kobject *kobj; 56 struct idletimer_tg_attr attr; 57 58 unsigned int refcnt; 59}; 60 61static LIST_HEAD(idletimer_tg_list); 62static DEFINE_MUTEX(list_mutex); 63 64static struct kobject *idletimer_tg_kobj; 65 66static 67struct idletimer_tg *__idletimer_tg_find_by_label(const char *label) 68{ 69 struct idletimer_tg *entry; 70 71 BUG_ON(!label); 72 73 list_for_each_entry(entry, &idletimer_tg_list, entry) { 74 if (!strcmp(label, entry->attr.attr.name)) 75 return entry; 76 } 77 78 return NULL; 79} 80 81static ssize_t idletimer_tg_show(struct kobject *kobj, struct attribute *attr, 82 char *buf) 83{ 84 struct idletimer_tg *timer; 85 unsigned long expires = 0; 86 87 mutex_lock(&list_mutex); 88 89 timer = __idletimer_tg_find_by_label(attr->name); 90 if (timer) 91 expires = timer->timer.expires; 92 93 mutex_unlock(&list_mutex); 94 95 if (time_after(expires, jiffies)) 96 return sprintf(buf, "%u\n", 97 jiffies_to_msecs(expires - jiffies) / 1000); 98 99 return sprintf(buf, "0\n"); 100} 101 102static void idletimer_tg_work(struct work_struct *work) 103{ 104 struct idletimer_tg *timer = container_of(work, struct idletimer_tg, 105 work); 106 107 sysfs_notify(idletimer_tg_kobj, NULL, timer->attr.attr.name); 108} 109 110static void idletimer_tg_expired(unsigned long data) 111{ 112 struct idletimer_tg *timer = (struct idletimer_tg *) data; 113 114 pr_debug("timer %s expired\n", timer->attr.attr.name); 115 116 schedule_work(&timer->work); 117} 118 119static int idletimer_tg_create(struct idletimer_tg_info *info) 120{ 121 int ret; 122 123 info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL); 124 if (!info->timer) { 125 pr_debug("couldn't alloc timer\n"); 126 ret = -ENOMEM; 127 goto out; 128 } 129 130 info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL); 131 if (!info->timer->attr.attr.name) { 132 pr_debug("couldn't alloc attribute name\n"); 133 ret = -ENOMEM; 134 goto out_free_timer; 135 } 136 info->timer->attr.attr.mode = S_IRUGO; 137 info->timer->attr.show = idletimer_tg_show; 138 139 ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr); 140 if (ret < 0) { 141 pr_debug("couldn't add file to sysfs"); 142 goto out_free_attr; 143 } 144 145 list_add(&info->timer->entry, &idletimer_tg_list); 146 147 setup_timer(&info->timer->timer, idletimer_tg_expired, 148 (unsigned long) info->timer); 149 info->timer->refcnt = 1; 150 151 mod_timer(&info->timer->timer, 152 msecs_to_jiffies(info->timeout * 1000) + jiffies); 153 154 INIT_WORK(&info->timer->work, idletimer_tg_work); 155 156 return 0; 157 158out_free_attr: 159 kfree(info->timer->attr.attr.name); 160out_free_timer: 161 kfree(info->timer); 162out: 163 return ret; 164} 165 166/* 167 * The actual xt_tables plugin. 168 */ 169static unsigned int idletimer_tg_target(struct sk_buff *skb, 170 const struct xt_action_param *par) 171{ 172 const struct idletimer_tg_info *info = par->targinfo; 173 174 pr_debug("resetting timer %s, timeout period %u\n", 175 info->label, info->timeout); 176 177 BUG_ON(!info->timer); 178 179 mod_timer(&info->timer->timer, 180 msecs_to_jiffies(info->timeout * 1000) + jiffies); 181 182 return XT_CONTINUE; 183} 184 185static int idletimer_tg_checkentry(const struct xt_tgchk_param *par) 186{ 187 struct idletimer_tg_info *info = par->targinfo; 188 int ret; 189 190 pr_debug("checkentry targinfo%s\n", info->label); 191 192 if (info->timeout == 0) { 193 pr_debug("timeout value is zero\n"); 194 return -EINVAL; 195 } 196 197 if (info->label[0] == '\0' || 198 strnlen(info->label, 199 MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) { 200 pr_debug("label is empty or not nul-terminated\n"); 201 return -EINVAL; 202 } 203 204 mutex_lock(&list_mutex); 205 206 info->timer = __idletimer_tg_find_by_label(info->label); 207 if (info->timer) { 208 info->timer->refcnt++; 209 mod_timer(&info->timer->timer, 210 msecs_to_jiffies(info->timeout * 1000) + jiffies); 211 212 pr_debug("increased refcnt of timer %s to %u\n", 213 info->label, info->timer->refcnt); 214 } else { 215 ret = idletimer_tg_create(info); 216 if (ret < 0) { 217 pr_debug("failed to create timer\n"); 218 mutex_unlock(&list_mutex); 219 return ret; 220 } 221 } 222 223 mutex_unlock(&list_mutex); 224 return 0; 225} 226 227static void idletimer_tg_destroy(const struct xt_tgdtor_param *par) 228{ 229 const struct idletimer_tg_info *info = par->targinfo; 230 231 pr_debug("destroy targinfo %s\n", info->label); 232 233 mutex_lock(&list_mutex); 234 235 if (--info->timer->refcnt == 0) { 236 pr_debug("deleting timer %s\n", info->label); 237 238 list_del(&info->timer->entry); 239 del_timer_sync(&info->timer->timer); 240 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr); 241 kfree(info->timer->attr.attr.name); 242 kfree(info->timer); 243 } else { 244 pr_debug("decreased refcnt of timer %s to %u\n", 245 info->label, info->timer->refcnt); 246 } 247 248 mutex_unlock(&list_mutex); 249} 250 251static struct xt_target idletimer_tg __read_mostly = { 252 .name = "IDLETIMER", 253 .family = NFPROTO_UNSPEC, 254 .target = idletimer_tg_target, 255 .targetsize = sizeof(struct idletimer_tg_info), 256 .checkentry = idletimer_tg_checkentry, 257 .destroy = idletimer_tg_destroy, 258 .me = THIS_MODULE, 259}; 260 261static struct class *idletimer_tg_class; 262 263static struct device *idletimer_tg_device; 264 265static int __init idletimer_tg_init(void) 266{ 267 int err; 268 269 idletimer_tg_class = class_create(THIS_MODULE, "xt_idletimer"); 270 err = PTR_ERR(idletimer_tg_class); 271 if (IS_ERR(idletimer_tg_class)) { 272 pr_debug("couldn't register device class\n"); 273 goto out; 274 } 275 276 idletimer_tg_device = device_create(idletimer_tg_class, NULL, 277 MKDEV(0, 0), NULL, "timers"); 278 err = PTR_ERR(idletimer_tg_device); 279 if (IS_ERR(idletimer_tg_device)) { 280 pr_debug("couldn't register system device\n"); 281 goto out_class; 282 } 283 284 idletimer_tg_kobj = &idletimer_tg_device->kobj; 285 286 err = xt_register_target(&idletimer_tg); 287 if (err < 0) { 288 pr_debug("couldn't register xt target\n"); 289 goto out_dev; 290 } 291 292 return 0; 293out_dev: 294 device_destroy(idletimer_tg_class, MKDEV(0, 0)); 295out_class: 296 class_destroy(idletimer_tg_class); 297out: 298 return err; 299} 300 301static void __exit idletimer_tg_exit(void) 302{ 303 xt_unregister_target(&idletimer_tg); 304 305 device_destroy(idletimer_tg_class, MKDEV(0, 0)); 306 class_destroy(idletimer_tg_class); 307} 308 309module_init(idletimer_tg_init); 310module_exit(idletimer_tg_exit); 311 312MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>"); 313MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>"); 314MODULE_DESCRIPTION("Xtables: idle time monitor"); 315MODULE_LICENSE("GPL v2"); 316