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
  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 bool 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                 printk(KERN_ERR KBUILD_MODNAME ": 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                 printk(KERN_CRIT KBUILD_MODNAME ": out of memory\n");
  97                 return false;
  98         }
  99
 100         ledinternal->netfilter_led_trigger.name = ledinfo->id;
 101
 102         err = led_trigger_register(&ledinternal->netfilter_led_trigger);
 103         if (err) {
 104                 printk(KERN_CRIT KBUILD_MODNAME
 105                         ": led_trigger_register() failed\n");
 106                 if (err == -EEXIST)
 107                         printk(KERN_ERR KBUILD_MODNAME
 108                                 ": Trigger name is already in use.\n");
 109                 goto exit_alloc;
 110         }
 111
 112         /* See if we need to set up a timer */
 113         if (ledinfo->delay > 0)
 114                 setup_timer(&ledinternal->timer, led_timeout_callback,
 115                             (unsigned long)ledinfo);
 116
 117         ledinfo->internal_data = ledinternal;
 118
 119         return true;
 120
 121 exit_alloc:
 122         kfree(ledinternal);
 123
 124         return false;
 125 }
 126
 127 static void led_tg_destroy(const struct xt_tgdtor_param *par)
 128 {
 129         const struct xt_led_info *ledinfo = par->targinfo;
 130         struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
 131
 132         if (ledinfo->delay > 0)
 133                 del_timer_sync(&ledinternal->timer);
 134
 135         led_trigger_unregister(&ledinternal->netfilter_led_trigger);
 136         kfree(ledinternal);
 137 }
 138
 139 static struct xt_target led_tg_reg __read_mostly = {
 140         .name           = "LED",
 141         .revision       = 0,
 142         .family         = NFPROTO_UNSPEC,
 143         .target         = led_tg,
 144         .targetsize     = XT_ALIGN(sizeof(struct xt_led_info)),
 145         .checkentry     = led_tg_check,
 146         .destroy        = led_tg_destroy,
 147         .me             = THIS_MODULE,
 148 };
 149
 150 static int __init led_tg_init(void)
 151 {
 152         return xt_register_target(&led_tg_reg);
 153 }
 154
 155 static void __exit led_tg_exit(void)
 156 {
 157         xt_unregister_target(&led_tg_reg);
 158 }
 159
 160 module_init(led_tg_init);
 161 module_exit(led_tg_exit);