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/slab.h>
  26 #include <linux/leds.h>
  27 #include <linux/mutex.h>
  28
  29 #include <linux/netfilter/xt_LED.h>
  30
  31 MODULE_LICENSE("GPL");
  32 MODULE_AUTHOR("Adam Nielsen <a.nielsen@shikadi.net>");
  33 MODULE_DESCRIPTION("Xtables: trigger LED devices on packet match");
  34
  35 /*
  36  * This is declared in here (the kernel module) only, to avoid having these
  37  * dependencies in userspace code.  This is what xt_led_info.internal_data
  38  * points to.
  39  */
  40 struct xt_led_info_internal {
  41         struct led_trigger netfilter_led_trigger;
  42         struct timer_list timer;
  43 };
  44
  45 static unsigned int
  46 led_tg(struct sk_buff *skb, const struct xt_target_param *par)
  47 {
  48         const struct xt_led_info *ledinfo = par->targinfo;
  49         struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
  50
  51         /*
  52          * If "always blink" is enabled, and there's still some time until the
  53          * LED will switch off, briefly switch it off now.
  54          */
  55         if ((ledinfo->delay > 0) && ledinfo->always_blink &&
  56             timer_pending(&ledinternal->timer))
  57                 led_trigger_event(&ledinternal->netfilter_led_trigger,LED_OFF);
  58
  59         led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL);
  60
  61         /* If there's a positive delay, start/update the timer */
  62         if (ledinfo->delay > 0) {
  63                 mod_timer(&ledinternal->timer,
  64                           jiffies + msecs_to_jiffies(ledinfo->delay));
  65
  66         /* Otherwise if there was no delay given, blink as fast as possible */
  67         } else if (ledinfo->delay == 0) {
  68                 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
  69         }
  70
  71         /* else the delay is negative, which means switch on and stay on */
  72
  73         return XT_CONTINUE;
  74 }
  75
  76 static void led_timeout_callback(unsigned long data)
  77 {
  78         struct xt_led_info *ledinfo = (struct xt_led_info *)data;
  79         struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
  80
  81         led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
  82 }
  83
  84 static bool led_tg_check(const struct xt_tgchk_param *par)
  85 {
  86         struct xt_led_info *ledinfo = par->targinfo;
  87         struct xt_led_info_internal *ledinternal;
  88         int err;
  89
  90         if (ledinfo->id[0] == '\0') {
  91                 printk(KERN_ERR KBUILD_MODNAME ": No 'id' parameter given.\n");
  92                 return false;
  93         }
  94
  95         ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL);
  96         if (!ledinternal) {
  97                 printk(KERN_CRIT KBUILD_MODNAME ": out of memory\n");
  98                 return false;
  99         }
 100
 101         ledinternal->netfilter_led_trigger.name = ledinfo->id;
 102
 103         err = led_trigger_register(&ledinternal->netfilter_led_trigger);
 104         if (err) {
 105                 printk(KERN_CRIT KBUILD_MODNAME
 106                         ": led_trigger_register() failed\n");
 107                 if (err == -EEXIST)
 108                         printk(KERN_ERR KBUILD_MODNAME
 109                                 ": Trigger name is already in use.\n");
 110                 goto exit_alloc;
 111         }
 112
 113         /* See if we need to set up a timer */
 114         if (ledinfo->delay > 0)
 115                 setup_timer(&ledinternal->timer, led_timeout_callback,
 116                             (unsigned long)ledinfo);
 117
 118         ledinfo->internal_data = ledinternal;
 119
 120         return true;
 121
 122 exit_alloc:
 123         kfree(ledinternal);
 124
 125         return false;
 126 }
 127
 128 static void led_tg_destroy(const struct xt_tgdtor_param *par)
 129 {
 130         const struct xt_led_info *ledinfo = par->targinfo;
 131         struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
 132
 133         if (ledinfo->delay > 0)
 134                 del_timer_sync(&ledinternal->timer);
 135
 136         led_trigger_unregister(&ledinternal->netfilter_led_trigger);
 137         kfree(ledinternal);
 138 }
 139
 140 static struct xt_target led_tg_reg __read_mostly = {
 141         .name           = "LED",
 142         .revision       = 0,
 143         .family         = NFPROTO_UNSPEC,
 144         .target         = led_tg,
 145         .targetsize     = XT_ALIGN(sizeof(struct xt_led_info)),
 146         .checkentry     = led_tg_check,
 147         .destroy        = led_tg_destroy,
 148         .me             = THIS_MODULE,
 149 };
 150
 151 static int __init led_tg_init(void)
 152 {
 153         return xt_register_target(&led_tg_reg);
 154 }
 155
 156 static void __exit led_tg_exit(void)
 157 {
 158         xt_unregister_target(&led_tg_reg);
 159 }
 160
 161 module_init(led_tg_init);
 162 module_exit(led_tg_exit);