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 44 struct idletimer_tg_attr { 45 struct attribute attr; 46 ssize_t (*show)(struct kobject *kobj, 47 struct attribute *attr, char *buf); 48 }; 49 50 struct 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 61 static LIST_HEAD(idletimer_tg_list); 62 static DEFINE_MUTEX(list_mutex); 63 64 static struct kobject *idletimer_tg_kobj; 65 66 static 67 struct 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 81 static 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 } 101 102 static 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 } 109 110 static 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 } 118 119 static 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 ret = -ENOMEM; 126 goto out; 127 } 128 129 info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL); 130 if (!info->timer->attr.attr.name) { 131 ret = -ENOMEM; 132 goto out_free_timer; 133 } 134 info->timer->attr.attr.mode = S_IRUGO; 135 info->timer->attr.show = idletimer_tg_show; 136 137 ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr); 138 if (ret < 0) { 139 pr_debug("couldn't add file to sysfs"); 140 goto out_free_attr; 141 } 142 143 list_add(&info->timer->entry, &idletimer_tg_list); 144 145 setup_timer(&info->timer->timer, idletimer_tg_expired, 146 (unsigned long) info->timer); 147 info->timer->refcnt = 1; 148 149 mod_timer(&info->timer->timer, 150 msecs_to_jiffies(info->timeout * 1000) + jiffies); 151 152 INIT_WORK(&info->timer->work, idletimer_tg_work); 153 154 return 0; 155 156 out_free_attr: 157 kfree(info->timer->attr.attr.name); 158 out_free_timer: 159 kfree(info->timer); 160 out: 161 return ret; 162 } 163 164 /* 165 * The actual xt_tables plugin. 166 */ 167 static unsigned int idletimer_tg_target(struct sk_buff *skb, 168 const struct xt_action_param *par) 169 { 170 const struct idletimer_tg_info *info = par->targinfo; 171 172 pr_debug("resetting timer %s, timeout period %u\n", 173 info->label, info->timeout); 174 175 BUG_ON(!info->timer); 176 177 mod_timer(&info->timer->timer, 178 msecs_to_jiffies(info->timeout * 1000) + jiffies); 179 180 return XT_CONTINUE; 181 } 182 183 static int idletimer_tg_checkentry(const struct xt_tgchk_param *par) 184 { 185 struct idletimer_tg_info *info = par->targinfo; 186 int ret; 187 188 pr_debug("checkentry targinfo%s\n", info->label); 189 190 if (info->timeout == 0) { 191 pr_debug("timeout value is zero\n"); 192 return -EINVAL; 193 } 194 195 if (info->label[0] == '\0' || 196 strnlen(info->label, 197 MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) { 198 pr_debug("label is empty or not nul-terminated\n"); 199 return -EINVAL; 200 } 201 202 mutex_lock(&list_mutex); 203 204 info->timer = __idletimer_tg_find_by_label(info->label); 205 if (info->timer) { 206 info->timer->refcnt++; 207 mod_timer(&info->timer->timer, 208 msecs_to_jiffies(info->timeout * 1000) + jiffies); 209 210 pr_debug("increased refcnt of timer %s to %u\n", 211 info->label, info->timer->refcnt); 212 } else { 213 ret = idletimer_tg_create(info); 214 if (ret < 0) { 215 pr_debug("failed to create timer\n"); 216 mutex_unlock(&list_mutex); 217 return ret; 218 } 219 } 220 221 mutex_unlock(&list_mutex); 222 return 0; 223 } 224 225 static void idletimer_tg_destroy(const struct xt_tgdtor_param *par) 226 { 227 const struct idletimer_tg_info *info = par->targinfo; 228 229 pr_debug("destroy targinfo %s\n", info->label); 230 231 mutex_lock(&list_mutex); 232 233 if (--info->timer->refcnt == 0) { 234 pr_debug("deleting timer %s\n", info->label); 235 236 list_del(&info->timer->entry); 237 del_timer_sync(&info->timer->timer); 238 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr); 239 kfree(info->timer->attr.attr.name); 240 kfree(info->timer); 241 } else { 242 pr_debug("decreased refcnt of timer %s to %u\n", 243 info->label, info->timer->refcnt); 244 } 245 246 mutex_unlock(&list_mutex); 247 } 248 249 static struct xt_target idletimer_tg __read_mostly = { 250 .name = "IDLETIMER", 251 .family = NFPROTO_UNSPEC, 252 .target = idletimer_tg_target, 253 .targetsize = sizeof(struct idletimer_tg_info), 254 .checkentry = idletimer_tg_checkentry, 255 .destroy = idletimer_tg_destroy, 256 .me = THIS_MODULE, 257 }; 258 259 static struct class *idletimer_tg_class; 260 261 static struct device *idletimer_tg_device; 262 263 static int __init idletimer_tg_init(void) 264 { 265 int err; 266 267 idletimer_tg_class = class_create(THIS_MODULE, "xt_idletimer"); 268 err = PTR_ERR(idletimer_tg_class); 269 if (IS_ERR(idletimer_tg_class)) { 270 pr_debug("couldn't register device class\n"); 271 goto out; 272 } 273 274 idletimer_tg_device = device_create(idletimer_tg_class, NULL, 275 MKDEV(0, 0), NULL, "timers"); 276 err = PTR_ERR(idletimer_tg_device); 277 if (IS_ERR(idletimer_tg_device)) { 278 pr_debug("couldn't register system device\n"); 279 goto out_class; 280 } 281 282 idletimer_tg_kobj = &idletimer_tg_device->kobj; 283 284 err = xt_register_target(&idletimer_tg); 285 if (err < 0) { 286 pr_debug("couldn't register xt target\n"); 287 goto out_dev; 288 } 289 290 return 0; 291 out_dev: 292 device_destroy(idletimer_tg_class, MKDEV(0, 0)); 293 out_class: 294 class_destroy(idletimer_tg_class); 295 out: 296 return err; 297 } 298 299 static void __exit idletimer_tg_exit(void) 300 { 301 xt_unregister_target(&idletimer_tg); 302 303 device_destroy(idletimer_tg_class, MKDEV(0, 0)); 304 class_destroy(idletimer_tg_class); 305 } 306 307 module_init(idletimer_tg_init); 308 module_exit(idletimer_tg_exit); 309 310 MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>"); 311 MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>"); 312 MODULE_DESCRIPTION("Xtables: idle time monitor"); 313 MODULE_LICENSE("GPL v2"); 314 MODULE_ALIAS("ipt_IDLETIMER"); 315 MODULE_ALIAS("ip6t_IDLETIMER"); 316