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/kobject.h> 40 #include <linux/workqueue.h> 41 #include <linux/sysfs.h> 42 43 struct idletimer_tg_attr { 44 struct attribute attr; 45 ssize_t (*show)(struct kobject *kobj, 46 struct attribute *attr, char *buf); 47 }; 48 49 struct idletimer_tg { 50 struct list_head entry; 51 struct timer_list timer; 52 struct work_struct work; 53 54 struct kobject *kobj; 55 struct idletimer_tg_attr attr; 56 57 unsigned int refcnt; 58 }; 59 60 static LIST_HEAD(idletimer_tg_list); 61 static DEFINE_MUTEX(list_mutex); 62 63 static struct kobject *idletimer_tg_kobj; 64 65 static 66 struct idletimer_tg *__idletimer_tg_find_by_label(const char *label) 67 { 68 struct idletimer_tg *entry; 69 70 BUG_ON(!label); 71 72 list_for_each_entry(entry, &idletimer_tg_list, entry) { 73 if (!strcmp(label, entry->attr.attr.name)) 74 return entry; 75 } 76 77 return NULL; 78 } 79 80 static ssize_t idletimer_tg_show(struct kobject *kobj, struct attribute *attr, 81 char *buf) 82 { 83 struct idletimer_tg *timer; 84 unsigned long expires = 0; 85 86 mutex_lock(&list_mutex); 87 88 timer = __idletimer_tg_find_by_label(attr->name); 89 if (timer) 90 expires = timer->timer.expires; 91 92 mutex_unlock(&list_mutex); 93 94 if (time_after(expires, jiffies)) 95 return sprintf(buf, "%u\n", 96 jiffies_to_msecs(expires - jiffies) / 1000); 97 98 return sprintf(buf, "0\n"); 99 } 100 101 static void idletimer_tg_work(struct work_struct *work) 102 { 103 struct idletimer_tg *timer = container_of(work, struct idletimer_tg, 104 work); 105 106 sysfs_notify(idletimer_tg_kobj, NULL, timer->attr.attr.name); 107 } 108 109 static void idletimer_tg_expired(unsigned long data) 110 { 111 struct idletimer_tg *timer = (struct idletimer_tg *) data; 112 113 pr_debug("timer %s expired\n", timer->attr.attr.name); 114 115 schedule_work(&timer->work); 116 } 117 118 static int idletimer_tg_create(struct idletimer_tg_info *info) 119 { 120 int ret; 121 122 info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL); 123 if (!info->timer) { 124 pr_debug("couldn't alloc timer\n"); 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 pr_debug("couldn't alloc attribute name\n"); 132 ret = -ENOMEM; 133 goto out_free_timer; 134 } 135 info->timer->attr.attr.mode = S_IRUGO; 136 info->timer->attr.show = idletimer_tg_show; 137 138 ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr); 139 if (ret < 0) { 140 pr_debug("couldn't add file to sysfs"); 141 goto out_free_attr; 142 } 143 144 list_add(&info->timer->entry, &idletimer_tg_list); 145 146 setup_timer(&info->timer->timer, idletimer_tg_expired, 147 (unsigned long) info->timer); 148 info->timer->refcnt = 1; 149 150 mod_timer(&info->timer->timer, 151 msecs_to_jiffies(info->timeout * 1000) + jiffies); 152 153 INIT_WORK(&info->timer->work, idletimer_tg_work); 154 155 return 0; 156 157 out_free_attr: 158 kfree(info->timer->attr.attr.name); 159 out_free_timer: 160 kfree(info->timer); 161 out: 162 return ret; 163 } 164 165 /* 166 * The actual xt_tables plugin. 167 */ 168 static unsigned int idletimer_tg_target(struct sk_buff *skb, 169 const struct xt_action_param *par) 170 { 171 const struct idletimer_tg_info *info = par->targinfo; 172 173 pr_debug("resetting timer %s, timeout period %u\n", 174 info->label, info->timeout); 175 176 BUG_ON(!info->timer); 177 178 mod_timer(&info->timer->timer, 179 msecs_to_jiffies(info->timeout * 1000) + jiffies); 180 181 return XT_CONTINUE; 182 } 183 184 static int idletimer_tg_checkentry(const struct xt_tgchk_param *par) 185 { 186 struct idletimer_tg_info *info = par->targinfo; 187 int ret; 188 189 pr_debug("checkentry targinfo%s\n", info->label); 190 191 if (info->timeout == 0) { 192 pr_debug("timeout value is zero\n"); 193 return -EINVAL; 194 } 195 196 if (info->label[0] == '\0' || 197 strnlen(info->label, 198 MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) { 199 pr_debug("label is empty or not nul-terminated\n"); 200 return -EINVAL; 201 } 202 203 mutex_lock(&list_mutex); 204 205 info->timer = __idletimer_tg_find_by_label(info->label); 206 if (info->timer) { 207 info->timer->refcnt++; 208 mod_timer(&info->timer->timer, 209 msecs_to_jiffies(info->timeout * 1000) + jiffies); 210 211 pr_debug("increased refcnt of timer %s to %u\n", 212 info->label, info->timer->refcnt); 213 } else { 214 ret = idletimer_tg_create(info); 215 if (ret < 0) { 216 pr_debug("failed to create timer\n"); 217 mutex_unlock(&list_mutex); 218 return ret; 219 } 220 } 221 222 mutex_unlock(&list_mutex); 223 return 0; 224 } 225 226 static void idletimer_tg_destroy(const struct xt_tgdtor_param *par) 227 { 228 const struct idletimer_tg_info *info = par->targinfo; 229 230 pr_debug("destroy targinfo %s\n", info->label); 231 232 mutex_lock(&list_mutex); 233 234 if (--info->timer->refcnt == 0) { 235 pr_debug("deleting timer %s\n", info->label); 236 237 list_del(&info->timer->entry); 238 del_timer_sync(&info->timer->timer); 239 sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr); 240 kfree(info->timer->attr.attr.name); 241 kfree(info->timer); 242 } else { 243 pr_debug("decreased refcnt of timer %s to %u\n", 244 info->label, info->timer->refcnt); 245 } 246 247 mutex_unlock(&list_mutex); 248 } 249 250 static struct xt_target idletimer_tg __read_mostly = { 251 .name = "IDLETIMER", 252 .family = NFPROTO_UNSPEC, 253 .target = idletimer_tg_target, 254 .targetsize = sizeof(struct idletimer_tg_info), 255 .checkentry = idletimer_tg_checkentry, 256 .destroy = idletimer_tg_destroy, 257 .me = THIS_MODULE, 258 }; 259 260 static struct class *idletimer_tg_class; 261 262 static struct device *idletimer_tg_device; 263 264 static int __init idletimer_tg_init(void) 265 { 266 int err; 267 268 idletimer_tg_class = class_create(THIS_MODULE, "xt_idletimer"); 269 err = PTR_ERR(idletimer_tg_class); 270 if (IS_ERR(idletimer_tg_class)) { 271 pr_debug("couldn't register device class\n"); 272 goto out; 273 } 274 275 idletimer_tg_device = device_create(idletimer_tg_class, NULL, 276 MKDEV(0, 0), NULL, "timers"); 277 err = PTR_ERR(idletimer_tg_device); 278 if (IS_ERR(idletimer_tg_device)) { 279 pr_debug("couldn't register system device\n"); 280 goto out_class; 281 } 282 283 idletimer_tg_kobj = &idletimer_tg_device->kobj; 284 285 err = xt_register_target(&idletimer_tg); 286 if (err < 0) { 287 pr_debug("couldn't register xt target\n"); 288 goto out_dev; 289 } 290 291 return 0; 292 out_dev: 293 device_destroy(idletimer_tg_class, MKDEV(0, 0)); 294 out_class: 295 class_destroy(idletimer_tg_class); 296 out: 297 return err; 298 } 299 300 static void __exit idletimer_tg_exit(void) 301 { 302 xt_unregister_target(&idletimer_tg); 303 304 device_destroy(idletimer_tg_class, MKDEV(0, 0)); 305 class_destroy(idletimer_tg_class); 306 } 307 308 module_init(idletimer_tg_init); 309 module_exit(idletimer_tg_exit); 310 311 MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>"); 312 MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>"); 313 MODULE_DESCRIPTION("Xtables: idle time monitor"); 314 MODULE_LICENSE("GPL v2"); 315