1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * xt_LED.c - netfilter target to make LEDs blink upon packet matches
4 *
5 * Copyright (C) 2008 Adam Nielsen <a.nielsen@shikadi.net>
6 */
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8 #include <linux/module.h>
9 #include <linux/skbuff.h>
10 #include <linux/netfilter/x_tables.h>
11 #include <linux/slab.h>
12 #include <linux/leds.h>
13 #include <linux/mutex.h>
14
15 #include <linux/netfilter/xt_LED.h>
16
17 MODULE_LICENSE("GPL");
18 MODULE_AUTHOR("Adam Nielsen <a.nielsen@shikadi.net>");
19 MODULE_DESCRIPTION("Xtables: trigger LED devices on packet match");
20 MODULE_ALIAS("ipt_LED");
21 MODULE_ALIAS("ip6t_LED");
22
23 static LIST_HEAD(xt_led_triggers);
24 static DEFINE_MUTEX(xt_led_mutex);
25
26 /*
27 * This is declared in here (the kernel module) only, to avoid having these
28 * dependencies in userspace code. This is what xt_led_info.internal_data
29 * points to.
30 */
31 struct xt_led_info_internal {
32 struct list_head list;
33 int refcnt;
34 char *trigger_id;
35 struct led_trigger netfilter_led_trigger;
36 struct timer_list timer;
37 };
38
39 #define XT_LED_BLINK_DELAY 50 /* ms */
40
41 static unsigned int
led_tg(struct sk_buff * skb,const struct xt_action_param * par)42 led_tg(struct sk_buff *skb, const struct xt_action_param *par)
43 {
44 const struct xt_led_info *ledinfo = par->targinfo;
45 struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
46
47 /*
48 * If "always blink" is enabled, and there's still some time until the
49 * LED will switch off, briefly switch it off now.
50 */
51 if ((ledinfo->delay > 0) && ledinfo->always_blink &&
52 timer_pending(&ledinternal->timer))
53 led_trigger_blink_oneshot(&ledinternal->netfilter_led_trigger,
54 XT_LED_BLINK_DELAY, XT_LED_BLINK_DELAY, 1);
55 else
56 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL);
57
58 /* If there's a positive delay, start/update the timer */
59 if (ledinfo->delay > 0) {
60 mod_timer(&ledinternal->timer,
61 jiffies + msecs_to_jiffies(ledinfo->delay));
62
63 /* Otherwise if there was no delay given, blink as fast as possible */
64 } else if (ledinfo->delay == 0) {
65 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
66 }
67
68 /* else the delay is negative, which means switch on and stay on */
69
70 return XT_CONTINUE;
71 }
72
led_timeout_callback(struct timer_list * t)73 static void led_timeout_callback(struct timer_list *t)
74 {
75 struct xt_led_info_internal *ledinternal = from_timer(ledinternal, t,
76 timer);
77
78 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
79 }
80
led_trigger_lookup(const char * name)81 static struct xt_led_info_internal *led_trigger_lookup(const char *name)
82 {
83 struct xt_led_info_internal *ledinternal;
84
85 list_for_each_entry(ledinternal, &xt_led_triggers, list) {
86 if (!strcmp(name, ledinternal->netfilter_led_trigger.name)) {
87 return ledinternal;
88 }
89 }
90 return NULL;
91 }
92
led_tg_check(const struct xt_tgchk_param * par)93 static int led_tg_check(const struct xt_tgchk_param *par)
94 {
95 struct xt_led_info *ledinfo = par->targinfo;
96 struct xt_led_info_internal *ledinternal;
97 int err;
98
99 if (ledinfo->id[0] == '\0')
100 return -EINVAL;
101
102 mutex_lock(&xt_led_mutex);
103
104 ledinternal = led_trigger_lookup(ledinfo->id);
105 if (ledinternal) {
106 ledinternal->refcnt++;
107 goto out;
108 }
109
110 err = -ENOMEM;
111 ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL);
112 if (!ledinternal)
113 goto exit_mutex_only;
114
115 ledinternal->trigger_id = kstrdup(ledinfo->id, GFP_KERNEL);
116 if (!ledinternal->trigger_id)
117 goto exit_internal_alloc;
118
119 ledinternal->refcnt = 1;
120 ledinternal->netfilter_led_trigger.name = ledinternal->trigger_id;
121
122 err = led_trigger_register(&ledinternal->netfilter_led_trigger);
123 if (err) {
124 pr_info_ratelimited("Trigger name is already in use.\n");
125 goto exit_alloc;
126 }
127
128 /* Since the letinternal timer can be shared between multiple targets,
129 * always set it up, even if the current target does not need it
130 */
131 timer_setup(&ledinternal->timer, led_timeout_callback, 0);
132
133 list_add_tail(&ledinternal->list, &xt_led_triggers);
134
135 out:
136 mutex_unlock(&xt_led_mutex);
137
138 ledinfo->internal_data = ledinternal;
139
140 return 0;
141
142 exit_alloc:
143 kfree(ledinternal->trigger_id);
144
145 exit_internal_alloc:
146 kfree(ledinternal);
147
148 exit_mutex_only:
149 mutex_unlock(&xt_led_mutex);
150
151 return err;
152 }
153
led_tg_destroy(const struct xt_tgdtor_param * par)154 static void led_tg_destroy(const struct xt_tgdtor_param *par)
155 {
156 const struct xt_led_info *ledinfo = par->targinfo;
157 struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
158
159 mutex_lock(&xt_led_mutex);
160
161 if (--ledinternal->refcnt) {
162 mutex_unlock(&xt_led_mutex);
163 return;
164 }
165
166 list_del(&ledinternal->list);
167
168 timer_shutdown_sync(&ledinternal->timer);
169
170 led_trigger_unregister(&ledinternal->netfilter_led_trigger);
171
172 mutex_unlock(&xt_led_mutex);
173
174 kfree(ledinternal->trigger_id);
175 kfree(ledinternal);
176 }
177
178 static struct xt_target led_tg_reg __read_mostly = {
179 .name = "LED",
180 .revision = 0,
181 .family = NFPROTO_UNSPEC,
182 .target = led_tg,
183 .targetsize = sizeof(struct xt_led_info),
184 .usersize = offsetof(struct xt_led_info, internal_data),
185 .checkentry = led_tg_check,
186 .destroy = led_tg_destroy,
187 .me = THIS_MODULE,
188 };
189
led_tg_init(void)190 static int __init led_tg_init(void)
191 {
192 return xt_register_target(&led_tg_reg);
193 }
194
led_tg_exit(void)195 static void __exit led_tg_exit(void)
196 {
197 xt_unregister_target(&led_tg_reg);
198 }
199
200 module_init(led_tg_init);
201 module_exit(led_tg_exit);
202