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         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
  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
  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
  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
 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
 191 static int __init led_tg_init(void)
 192 {
 193         return xt_register_target(&led_tg_reg);
 194 }
 195
 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);