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 unsigned long led_delay = XT_LED_BLINK_DELAY;
47
48 /*
49 * If "always blink" is enabled, and there's still some time until the
50 * LED will switch off, briefly switch it off now.
51 */
52 if ((ledinfo->delay > 0) && ledinfo->always_blink &&
53 timer_pending(&ledinternal->timer))
54 led_trigger_blink_oneshot(&ledinternal->netfilter_led_trigger,
55 &led_delay, &led_delay, 1);
56 else
57 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL);
58
59 /* If there's a positive delay, start/update the timer */
60 if (ledinfo->delay > 0) {
61 mod_timer(&ledinternal->timer,
62 jiffies + msecs_to_jiffies(ledinfo->delay));
63
64 /* Otherwise if there was no delay given, blink as fast as possible */
65 } else if (ledinfo->delay == 0) {
66 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
67 }
68
69 /* else the delay is negative, which means switch on and stay on */
70
71 return XT_CONTINUE;
72 }
73
led_timeout_callback(struct timer_list * t)74 static void led_timeout_callback(struct timer_list *t)
75 {
76 struct xt_led_info_internal *ledinternal = from_timer(ledinternal, t,
77 timer);
78
79 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
80 }
81
led_trigger_lookup(const char * name)82 static struct xt_led_info_internal *led_trigger_lookup(const char *name)
83 {
84 struct xt_led_info_internal *ledinternal;
85
86 list_for_each_entry(ledinternal, &xt_led_triggers, list) {
87 if (!strcmp(name, ledinternal->netfilter_led_trigger.name)) {
88 return ledinternal;
89 }
90 }
91 return NULL;
92 }
93
led_tg_check(const struct xt_tgchk_param * par)94 static int led_tg_check(const struct xt_tgchk_param *par)
95 {
96 struct xt_led_info *ledinfo = par->targinfo;
97 struct xt_led_info_internal *ledinternal;
98 int err;
99
100 if (ledinfo->id[0] == '\0')
101 return -EINVAL;
102
103 mutex_lock(&xt_led_mutex);
104
105 ledinternal = led_trigger_lookup(ledinfo->id);
106 if (ledinternal) {
107 ledinternal->refcnt++;
108 goto out;
109 }
110
111 err = -ENOMEM;
112 ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL);
113 if (!ledinternal)
114 goto exit_mutex_only;
115
116 ledinternal->trigger_id = kstrdup(ledinfo->id, GFP_KERNEL);
117 if (!ledinternal->trigger_id)
118 goto exit_internal_alloc;
119
120 ledinternal->refcnt = 1;
121 ledinternal->netfilter_led_trigger.name = ledinternal->trigger_id;
122
123 err = led_trigger_register(&ledinternal->netfilter_led_trigger);
124 if (err) {
125 pr_info_ratelimited("Trigger name is already in use.\n");
126 goto exit_alloc;
127 }
128
129 /* Since the letinternal timer can be shared between multiple targets,
130 * always set it up, even if the current target does not need it
131 */
132 timer_setup(&ledinternal->timer, led_timeout_callback, 0);
133
134 list_add_tail(&ledinternal->list, &xt_led_triggers);
135
136 out:
137 mutex_unlock(&xt_led_mutex);
138
139 ledinfo->internal_data = ledinternal;
140
141 return 0;
142
143 exit_alloc:
144 kfree(ledinternal->trigger_id);
145
146 exit_internal_alloc:
147 kfree(ledinternal);
148
149 exit_mutex_only:
150 mutex_unlock(&xt_led_mutex);
151
152 return err;
153 }
154
led_tg_destroy(const struct xt_tgdtor_param * par)155 static void led_tg_destroy(const struct xt_tgdtor_param *par)
156 {
157 const struct xt_led_info *ledinfo = par->targinfo;
158 struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
159
160 mutex_lock(&xt_led_mutex);
161
162 if (--ledinternal->refcnt) {
163 mutex_unlock(&xt_led_mutex);
164 return;
165 }
166
167 list_del(&ledinternal->list);
168
169 del_timer_sync(&ledinternal->timer);
170
171 led_trigger_unregister(&ledinternal->netfilter_led_trigger);
172
173 mutex_unlock(&xt_led_mutex);
174
175 kfree(ledinternal->trigger_id);
176 kfree(ledinternal);
177 }
178
179 static struct xt_target led_tg_reg __read_mostly = {
180 .name = "LED",
181 .revision = 0,
182 .family = NFPROTO_UNSPEC,
183 .target = led_tg,
184 .targetsize = sizeof(struct xt_led_info),
185 .usersize = offsetof(struct xt_led_info, internal_data),
186 .checkentry = led_tg_check,
187 .destroy = led_tg_destroy,
188 .me = THIS_MODULE,
189 };
190
led_tg_init(void)191 static int __init led_tg_init(void)
192 {
193 return xt_register_target(&led_tg_reg);
194 }
195
led_tg_exit(void)196 static void __exit led_tg_exit(void)
197 {
198 xt_unregister_target(&led_tg_reg);
199 }
200
201 module_init(led_tg_init);
202 module_exit(led_tg_exit);
203