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
17MODULE_LICENSE("GPL");
18MODULE_AUTHOR("Adam Nielsen <a.nielsen@shikadi.net>");
19MODULE_DESCRIPTION("Xtables: trigger LED devices on packet match");
20MODULE_ALIAS("ipt_LED");
21MODULE_ALIAS("ip6t_LED");
22
23static LIST_HEAD(xt_led_triggers);
24static 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 */
31struct 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
41static unsigned int
42led_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(timer: &ledinternal->timer))
53 led_trigger_blink_oneshot(trigger: &ledinternal->netfilter_led_trigger,
54 XT_LED_BLINK_DELAY, XT_LED_BLINK_DELAY, invert: 1);
55 else
56 led_trigger_event(trigger: &ledinternal->netfilter_led_trigger, event: LED_FULL);
57
58 /* If there's a positive delay, start/update the timer */
59 if (ledinfo->delay > 0) {
60 mod_timer(timer: &ledinternal->timer,
61 expires: jiffies + msecs_to_jiffies(m: 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(trigger: &ledinternal->netfilter_led_trigger, event: LED_OFF);
66 }
67
68 /* else the delay is negative, which means switch on and stay on */
69
70 return XT_CONTINUE;
71}
72
73static void led_timeout_callback(struct timer_list *t)
74{
75 struct xt_led_info_internal *ledinternal = timer_container_of(ledinternal,
76 t,
77 timer);
78
79 led_trigger_event(trigger: &ledinternal->netfilter_led_trigger, event: LED_OFF);
80}
81
82static 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
94static 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 /* Bail out if empty string or not a string at all. */
101 if (ledinfo->id[0] == '\0' ||
102 !memchr(p: ledinfo->id, c: '\0', size: sizeof(ledinfo->id)))
103 return -EINVAL;
104
105 mutex_lock(&xt_led_mutex);
106
107 ledinternal = led_trigger_lookup(name: ledinfo->id);
108 if (ledinternal) {
109 ledinternal->refcnt++;
110 goto out;
111 }
112
113 err = -ENOMEM;
114 ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL);
115 if (!ledinternal)
116 goto exit_mutex_only;
117
118 ledinternal->trigger_id = kstrdup(s: ledinfo->id, GFP_KERNEL);
119 if (!ledinternal->trigger_id)
120 goto exit_internal_alloc;
121
122 ledinternal->refcnt = 1;
123 ledinternal->netfilter_led_trigger.name = ledinternal->trigger_id;
124
125 err = led_trigger_register(trigger: &ledinternal->netfilter_led_trigger);
126 if (err) {
127 pr_info_ratelimited("Trigger name is already in use.\n");
128 goto exit_alloc;
129 }
130
131 /* Since the letinternal timer can be shared between multiple targets,
132 * always set it up, even if the current target does not need it
133 */
134 timer_setup(&ledinternal->timer, led_timeout_callback, 0);
135
136 list_add_tail(new: &ledinternal->list, head: &xt_led_triggers);
137
138out:
139 mutex_unlock(lock: &xt_led_mutex);
140
141 ledinfo->internal_data = ledinternal;
142
143 return 0;
144
145exit_alloc:
146 kfree(objp: ledinternal->trigger_id);
147
148exit_internal_alloc:
149 kfree(objp: ledinternal);
150
151exit_mutex_only:
152 mutex_unlock(lock: &xt_led_mutex);
153
154 return err;
155}
156
157static void led_tg_destroy(const struct xt_tgdtor_param *par)
158{
159 const struct xt_led_info *ledinfo = par->targinfo;
160 struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
161
162 mutex_lock(&xt_led_mutex);
163
164 if (--ledinternal->refcnt) {
165 mutex_unlock(lock: &xt_led_mutex);
166 return;
167 }
168
169 list_del(entry: &ledinternal->list);
170
171 timer_shutdown_sync(timer: &ledinternal->timer);
172
173 led_trigger_unregister(trigger: &ledinternal->netfilter_led_trigger);
174
175 mutex_unlock(lock: &xt_led_mutex);
176
177 kfree(objp: ledinternal->trigger_id);
178 kfree(objp: ledinternal);
179}
180
181static struct xt_target led_tg_reg[] __read_mostly = {
182 {
183 .name = "LED",
184 .revision = 0,
185 .family = NFPROTO_IPV4,
186 .target = led_tg,
187 .targetsize = sizeof(struct xt_led_info),
188 .usersize = offsetof(struct xt_led_info, internal_data),
189 .checkentry = led_tg_check,
190 .destroy = led_tg_destroy,
191 .me = THIS_MODULE,
192 },
193#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
194 {
195 .name = "LED",
196 .revision = 0,
197 .family = NFPROTO_IPV6,
198 .target = led_tg,
199 .targetsize = sizeof(struct xt_led_info),
200 .usersize = offsetof(struct xt_led_info, internal_data),
201 .checkentry = led_tg_check,
202 .destroy = led_tg_destroy,
203 .me = THIS_MODULE,
204 },
205#endif
206};
207
208static int __init led_tg_init(void)
209{
210 return xt_register_targets(target: led_tg_reg, ARRAY_SIZE(led_tg_reg));
211}
212
213static void __exit led_tg_exit(void)
214{
215 xt_unregister_targets(target: led_tg_reg, ARRAY_SIZE(led_tg_reg));
216}
217
218module_init(led_tg_init);
219module_exit(led_tg_exit);
220

source code of linux/net/netfilter/xt_LED.c