xref: /openbmc/linux/net/netfilter/xt_IDLETIMER.c (revision 600069da) 
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 		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 
158 out_free_attr:
159 	kfree(info->timer->attr.attr.name);
160 out_free_timer:
161 	kfree(info->timer);
162 out:
163 	return ret;
164 }
165 
166 /*
167  * The actual xt_tables plugin.
168  */
169 static 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 
185 static 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 
227 static 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 
251 static 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 
261 static struct class *idletimer_tg_class;
262 
263 static struct device *idletimer_tg_device;
264 
265 static 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;
293 out_dev:
294 	device_destroy(idletimer_tg_class, MKDEV(0, 0));
295 out_class:
296 	class_destroy(idletimer_tg_class);
297 out:
298 	return err;
299 }
300 
301 static 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 
309 module_init(idletimer_tg_init);
310 module_exit(idletimer_tg_exit);
311 
312 MODULE_AUTHOR("Timo Teras <ext-timo.teras@nokia.com>");
313 MODULE_AUTHOR("Luciano Coelho <luciano.coelho@nokia.com>");
314 MODULE_DESCRIPTION("Xtables: idle time monitor");
315 MODULE_LICENSE("GPL v2");
316