net/netfilter/xt_LED.c

   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
  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
  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
  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
  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
 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
 190 static int __init led_tg_init(void)
 191 {
 192         return xt_register_target(&led_tg_reg);
 193 }
 194
 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);