1/*
2 * xt_LED.c - netfilter target to make LEDs blink upon packet matches
3 *
4 * Copyright (C) 2008 Adam Nielsen <a.nielsen@shikadi.net>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; version 2 of the License.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
18 * 02110-1301 USA.
19 *
20 */
21#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22#include <linux/module.h>
23#include <linux/skbuff.h>
24#include <linux/netfilter/x_tables.h>
25#include <linux/slab.h>
26#include <linux/leds.h>
27#include <linux/mutex.h>
28
29#include <linux/netfilter/xt_LED.h>
30
31MODULE_LICENSE("GPL");
32MODULE_AUTHOR("Adam Nielsen <a.nielsen@shikadi.net>");
33MODULE_DESCRIPTION("Xtables: trigger LED devices on packet match");
34MODULE_ALIAS("ipt_LED");
35MODULE_ALIAS("ip6t_LED");
36
37static LIST_HEAD(xt_led_triggers);
38static DEFINE_MUTEX(xt_led_mutex);
39
40/*
41 * This is declared in here (the kernel module) only, to avoid having these
42 * dependencies in userspace code.  This is what xt_led_info.internal_data
43 * points to.
44 */
45struct xt_led_info_internal {
46	struct list_head list;
47	int refcnt;
48	char *trigger_id;
49	struct led_trigger netfilter_led_trigger;
50	struct timer_list timer;
51};
52
53#define XT_LED_BLINK_DELAY 50 /* ms */
54
55static unsigned int
56led_tg(struct sk_buff *skb, const struct xt_action_param *par)
57{
58	const struct xt_led_info *ledinfo = par->targinfo;
59	struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
60	unsigned long led_delay = XT_LED_BLINK_DELAY;
61
62	/*
63	 * If "always blink" is enabled, and there's still some time until the
64	 * LED will switch off, briefly switch it off now.
65	 */
66	if ((ledinfo->delay > 0) && ledinfo->always_blink &&
67	    timer_pending(&ledinternal->timer))
68		led_trigger_blink_oneshot(&ledinternal->netfilter_led_trigger,
69					  &led_delay, &led_delay, 1);
70	else
71		led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL);
72
73	/* If there's a positive delay, start/update the timer */
74	if (ledinfo->delay > 0) {
75		mod_timer(&ledinternal->timer,
76			  jiffies + msecs_to_jiffies(ledinfo->delay));
77
78	/* Otherwise if there was no delay given, blink as fast as possible */
79	} else if (ledinfo->delay == 0) {
80		led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
81	}
82
83	/* else the delay is negative, which means switch on and stay on */
84
85	return XT_CONTINUE;
86}
87
88static void led_timeout_callback(unsigned long data)
89{
90	struct xt_led_info_internal *ledinternal = (struct xt_led_info_internal *)data;
91
92	led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
93}
94
95static struct xt_led_info_internal *led_trigger_lookup(const char *name)
96{
97	struct xt_led_info_internal *ledinternal;
98
99	list_for_each_entry(ledinternal, &xt_led_triggers, list) {
100		if (!strcmp(name, ledinternal->netfilter_led_trigger.name)) {
101			return ledinternal;
102		}
103	}
104	return NULL;
105}
106
107static int led_tg_check(const struct xt_tgchk_param *par)
108{
109	struct xt_led_info *ledinfo = par->targinfo;
110	struct xt_led_info_internal *ledinternal;
111	int err;
112
113	if (ledinfo->id[0] == '\0') {
114		pr_info("No 'id' parameter given.\n");
115		return -EINVAL;
116	}
117
118	mutex_lock(&xt_led_mutex);
119
120	ledinternal = led_trigger_lookup(ledinfo->id);
121	if (ledinternal) {
122		ledinternal->refcnt++;
123		goto out;
124	}
125
126	err = -ENOMEM;
127	ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL);
128	if (!ledinternal)
129		goto exit_mutex_only;
130
131	ledinternal->trigger_id = kstrdup(ledinfo->id, GFP_KERNEL);
132	if (!ledinternal->trigger_id)
133		goto exit_internal_alloc;
134
135	ledinternal->refcnt = 1;
136	ledinternal->netfilter_led_trigger.name = ledinternal->trigger_id;
137
138	err = led_trigger_register(&ledinternal->netfilter_led_trigger);
139	if (err) {
140		pr_err("Trigger name is already in use.\n");
141		goto exit_alloc;
142	}
143
144	/* See if we need to set up a timer */
145	if (ledinfo->delay > 0)
146		setup_timer(&ledinternal->timer, led_timeout_callback,
147			    (unsigned long)ledinternal);
148
149	list_add_tail(&ledinternal->list, &xt_led_triggers);
150
151out:
152	mutex_unlock(&xt_led_mutex);
153
154	ledinfo->internal_data = ledinternal;
155
156	return 0;
157
158exit_alloc:
159	kfree(ledinternal->trigger_id);
160
161exit_internal_alloc:
162	kfree(ledinternal);
163
164exit_mutex_only:
165	mutex_unlock(&xt_led_mutex);
166
167	return err;
168}
169
170static void led_tg_destroy(const struct xt_tgdtor_param *par)
171{
172	const struct xt_led_info *ledinfo = par->targinfo;
173	struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
174
175	mutex_lock(&xt_led_mutex);
176
177	if (--ledinternal->refcnt) {
178		mutex_unlock(&xt_led_mutex);
179		return;
180	}
181
182	list_del(&ledinternal->list);
183
184	if (ledinfo->delay > 0)
185		del_timer_sync(&ledinternal->timer);
186
187	led_trigger_unregister(&ledinternal->netfilter_led_trigger);
188
189	mutex_unlock(&xt_led_mutex);
190
191	kfree(ledinternal->trigger_id);
192	kfree(ledinternal);
193}
194
195static struct xt_target led_tg_reg __read_mostly = {
196	.name		= "LED",
197	.revision	= 0,
198	.family		= NFPROTO_UNSPEC,
199	.target		= led_tg,
200	.targetsize	= sizeof(struct xt_led_info),
201	.checkentry	= led_tg_check,
202	.destroy	= led_tg_destroy,
203	.me		= THIS_MODULE,
204};
205
206static int __init led_tg_init(void)
207{
208	return xt_register_target(&led_tg_reg);
209}
210
211static void __exit led_tg_exit(void)
212{
213	xt_unregister_target(&led_tg_reg);
214}
215
216module_init(led_tg_init);
217module_exit(led_tg_exit);
218