xref: /openbmc/linux/net/netfilter/xt_IDLETIMER.c (revision 484836ec) 
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 	sysfs_attr_init(&info->timer->attr.attr);
130 	info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);
131 	if (!info->timer->attr.attr.name) {
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 MODULE_ALIAS("ipt_IDLETIMER");
316 MODULE_ALIAS("ip6t_IDLETIMER");
317