net/netfilter/xt_LED.c

   1 /*
   2  * xt_LED.c - netfilter target to make LEDs blink upon packet matches
   3  *
   4  * Copyright (C) 2008 Adam Nielsen <a.nielsen@shikadi.net>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18  * 02110-1301 USA.
  19  *
  20  */
  21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  22 #include <linux/module.h>
  23 #include <linux/skbuff.h>
  24 #include <linux/netfilter/x_tables.h>
  25 #include <linux/leds.h>
  26 #include <linux/mutex.h>
  27
  28 #include <linux/netfilter/xt_LED.h>
  29
  30 MODULE_LICENSE("GPL");
  31 MODULE_AUTHOR("Adam Nielsen <a.nielsen@shikadi.net>");
  32 MODULE_DESCRIPTION("Xtables: trigger LED devices on packet match");
  33
  34 /*
  35  * This is declared in here (the kernel module) only, to avoid having these
  36  * dependencies in userspace code.  This is what xt_led_info.internal_data
  37  * points to.
  38  */
  39 struct xt_led_info_internal {
  40         struct led_trigger netfilter_led_trigger;
  41         struct timer_list timer;
  42 };
  43
  44 static unsigned int
  45 led_tg(struct sk_buff *skb, const struct xt_target_param *par)
  46 {
  47         const struct xt_led_info *ledinfo = par->targinfo;
  48         struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
  49
  50         /*
  51          * If "always blink" is enabled, and there's still some time until the
  52          * LED will switch off, briefly switch it off now.
  53          */
  54         if ((ledinfo->delay > 0) && ledinfo->always_blink &&
  55             timer_pending(&ledinternal->timer))
  56                 led_trigger_event(&ledinternal->netfilter_led_trigger,LED_OFF);
  57
  58         led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL);
  59
  60         /* If there's a positive delay, start/update the timer */
  61         if (ledinfo->delay > 0) {
  62                 mod_timer(&ledinternal->timer,
  63                           jiffies + msecs_to_jiffies(ledinfo->delay));
  64
  65         /* Otherwise if there was no delay given, blink as fast as possible */
  66         } else if (ledinfo->delay == 0) {
  67                 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
  68         }
  69
  70         /* else the delay is negative, which means switch on and stay on */
  71
  72         return XT_CONTINUE;
  73 }
  74
  75 static void led_timeout_callback(unsigned long data)
  76 {
  77         struct xt_led_info *ledinfo = (struct xt_led_info *)data;
  78         struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
  79
  80         led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
  81 }
  82
  83 static int led_tg_check(const struct xt_tgchk_param *par)
  84 {
  85         struct xt_led_info *ledinfo = par->targinfo;
  86         struct xt_led_info_internal *ledinternal;
  87         int err;
  88
  89         if (ledinfo->id[0] == '\0') {
  90                 pr_info("No 'id' parameter given.\n");
  91                 return false;
  92         }
  93
  94         ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL);
  95         if (!ledinternal)
  96                 return false;
  97
  98         ledinternal->netfilter_led_trigger.name = ledinfo->id;
  99
 100         err = led_trigger_register(&ledinternal->netfilter_led_trigger);
 101         if (err) {
 102                 pr_warning("led_trigger_register() failed\n");
 103                 if (err == -EEXIST)
 104                         pr_warning("Trigger name is already in use.\n");
 105                 goto exit_alloc;
 106         }
 107
 108         /* See if we need to set up a timer */
 109         if (ledinfo->delay > 0)
 110                 setup_timer(&ledinternal->timer, led_timeout_callback,
 111                             (unsigned long)ledinfo);
 112
 113         ledinfo->internal_data = ledinternal;
 114
 115         return true;
 116
 117 exit_alloc:
 118         kfree(ledinternal);
 119
 120         return false;
 121 }
 122
 123 static void led_tg_destroy(const struct xt_tgdtor_param *par)
 124 {
 125         const struct xt_led_info *ledinfo = par->targinfo;
 126         struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
 127
 128         if (ledinfo->delay > 0)
 129                 del_timer_sync(&ledinternal->timer);
 130
 131         led_trigger_unregister(&ledinternal->netfilter_led_trigger);
 132         kfree(ledinternal);
 133 }
 134
 135 static struct xt_target led_tg_reg __read_mostly = {
 136         .name           = "LED",
 137         .revision       = 0,
 138         .family         = NFPROTO_UNSPEC,
 139         .target         = led_tg,
 140         .targetsize     = sizeof(struct xt_led_info),
 141         .checkentry     = led_tg_check,
 142         .destroy        = led_tg_destroy,
 143         .me             = THIS_MODULE,
 144 };
 145
 146 static int __init led_tg_init(void)
 147 {
 148         return xt_register_target(&led_tg_reg);
 149 }
 150
 151 static void __exit led_tg_exit(void)
 152 {
 153         xt_unregister_target(&led_tg_reg);
 154 }
 155
 156 module_init(led_tg_init);
 157 module_exit(led_tg_exit);