mac80211: fix another race in aggregation start
[linux-2.6.git] / net / netfilter / xt_IDLETIMER.c
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 MODULE_ALIAS("ipt_IDLETIMER");
317 MODULE_ALIAS("ip6t_IDLETIMER");