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 /* Bail out if empty string or not a string at all. */
100 if (ledinfo->id[0] == '\0' ||
101 !memchr(ledinfo->id, '\0', sizeof(ledinfo->id)))
102 return -EINVAL;
103
104 mutex_lock(&xt_led_mutex);
105
106 ledinternal = led_trigger_lookup(ledinfo->id);
107 if (ledinternal) {
108 ledinternal->refcnt++;
109 goto out;
110 }
111
112 err = -ENOMEM;
113 ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL);
114 if (!ledinternal)
115 goto exit_mutex_only;
116
117 ledinternal->trigger_id = kstrdup(ledinfo->id, GFP_KERNEL);
118 if (!ledinternal->trigger_id)
119 goto exit_internal_alloc;
120
121 ledinternal->refcnt = 1;
122 ledinternal->netfilter_led_trigger.name = ledinternal->trigger_id;
123
124 err = led_trigger_register(&ledinternal->netfilter_led_trigger);
125 if (err) {
126 pr_info_ratelimited("Trigger name is already in use.\n");
127 goto exit_alloc;
128 }
129
130 /* Since the letinternal timer can be shared between multiple targets,
131 * always set it up, even if the current target does not need it
132 */
133 timer_setup(&ledinternal->timer, led_timeout_callback, 0);
134
135 list_add_tail(&ledinternal->list, &xt_led_triggers);
136
137 out:
138 mutex_unlock(&xt_led_mutex);
139
140 ledinfo->internal_data = ledinternal;
141
142 return 0;
143
144 exit_alloc:
145 kfree(ledinternal->trigger_id);
146
147 exit_internal_alloc:
148 kfree(ledinternal);
149
150 exit_mutex_only:
151 mutex_unlock(&xt_led_mutex);
152
153 return err;
154 }
155
led_tg_destroy(const struct xt_tgdtor_param * par)156 static void led_tg_destroy(const struct xt_tgdtor_param *par)
157 {
158 const struct xt_led_info *ledinfo = par->targinfo;
159 struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
160
161 mutex_lock(&xt_led_mutex);
162
163 if (--ledinternal->refcnt) {
164 mutex_unlock(&xt_led_mutex);
165 return;
166 }
167
168 list_del(&ledinternal->list);
169
170 timer_shutdown_sync(&ledinternal->timer);
171
172 led_trigger_unregister(&ledinternal->netfilter_led_trigger);
173
174 mutex_unlock(&xt_led_mutex);
175
176 kfree(ledinternal->trigger_id);
177 kfree(ledinternal);
178 }
179
180 static struct xt_target led_tg_reg[] __read_mostly = {
181 {
182 .name = "LED",
183 .revision = 0,
184 .family = NFPROTO_IPV4,
185 .target = led_tg,
186 .targetsize = sizeof(struct xt_led_info),
187 .usersize = offsetof(struct xt_led_info, internal_data),
188 .checkentry = led_tg_check,
189 .destroy = led_tg_destroy,
190 .me = THIS_MODULE,
191 },
192 #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
193 {
194 .name = "LED",
195 .revision = 0,
196 .family = NFPROTO_IPV6,
197 .target = led_tg,
198 .targetsize = sizeof(struct xt_led_info),
199 .usersize = offsetof(struct xt_led_info, internal_data),
200 .checkentry = led_tg_check,
201 .destroy = led_tg_destroy,
202 .me = THIS_MODULE,
203 },
204 #endif
205 };
206
led_tg_init(void)207 static int __init led_tg_init(void)
208 {
209 return xt_register_targets(led_tg_reg, ARRAY_SIZE(led_tg_reg));
210 }
211
led_tg_exit(void)212 static void __exit led_tg_exit(void)
213 {
214 xt_unregister_targets(led_tg_reg, ARRAY_SIZE(led_tg_reg));
215 }
216
217 module_init(led_tg_init);
218 module_exit(led_tg_exit);
219