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/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 MODULE_ALIAS("ipt_LED");
  35 MODULE_ALIAS("ip6t_LED");
  36
  37 static LIST_HEAD(xt_led_triggers);
  38 static DEFINE_MUTEX(xt_led_mutex);
  39
  40 /*
  41  * This is declared in here (the kernel module) only, to avoid having these
  42  * dependencies in userspace code.  This is what xt_led_info.internal_data
  43  * points to.
  44  */
  45 struct xt_led_info_internal {
  46         struct list_head list;
  47         int refcnt;
  48         char *trigger_id;
  49         struct led_trigger netfilter_led_trigger;
  50         struct timer_list timer;
  51 };
  52
  53 #define XT_LED_BLINK_DELAY 50 /* ms */
  54
  55 static unsigned int
  56 led_tg(struct sk_buff *skb, const struct xt_action_param *par)
  57 {
  58         const struct xt_led_info *ledinfo = par->targinfo;
  59         struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
  60         unsigned long led_delay = XT_LED_BLINK_DELAY;
  61
  62         /*
  63          * If "always blink" is enabled, and there's still some time until the
  64          * LED will switch off, briefly switch it off now.
  65          */
  66         if ((ledinfo->delay > 0) && ledinfo->always_blink &&
  67             timer_pending(&ledinternal->timer))
  68                 led_trigger_blink_oneshot(&ledinternal->netfilter_led_trigger,
  69                                           &led_delay, &led_delay, 1);
  70         else
  71                 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL);
  72
  73         /* If there's a positive delay, start/update the timer */
  74         if (ledinfo->delay > 0) {
  75                 mod_timer(&ledinternal->timer,
  76                           jiffies + msecs_to_jiffies(ledinfo->delay));
  77
  78         /* Otherwise if there was no delay given, blink as fast as possible */
  79         } else if (ledinfo->delay == 0) {
  80                 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
  81         }
  82
  83         /* else the delay is negative, which means switch on and stay on */
  84
  85         return XT_CONTINUE;
  86 }
  87
  88 static void led_timeout_callback(unsigned long data)
  89 {
  90         struct xt_led_info_internal *ledinternal = (struct xt_led_info_internal *)data;
  91
  92         led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
  93 }
  94
  95 static struct xt_led_info_internal *led_trigger_lookup(const char *name)
  96 {
  97         struct xt_led_info_internal *ledinternal;
  98
  99         list_for_each_entry(ledinternal, &xt_led_triggers, list) {
 100                 if (!strcmp(name, ledinternal->netfilter_led_trigger.name)) {
 101                         return ledinternal;
 102                 }
 103         }
 104         return NULL;
 105 }
 106
 107 static int led_tg_check(const struct xt_tgchk_param *par)
 108 {
 109         struct xt_led_info *ledinfo = par->targinfo;
 110         struct xt_led_info_internal *ledinternal;
 111         int err;
 112
 113         if (ledinfo->id[0] == '\0') {
 114                 pr_info("No 'id' parameter given.\n");
 115                 return -EINVAL;
 116         }
 117
 118         mutex_lock(&xt_led_mutex);
 119
 120         ledinternal = led_trigger_lookup(ledinfo->id);
 121         if (ledinternal) {
 122                 ledinternal->refcnt++;
 123                 goto out;
 124         }
 125
 126         err = -ENOMEM;
 127         ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL);
 128         if (!ledinternal)
 129                 goto exit_mutex_only;
 130
 131         ledinternal->trigger_id = kstrdup(ledinfo->id, GFP_KERNEL);
 132         if (!ledinternal->trigger_id)
 133                 goto exit_internal_alloc;
 134
 135         ledinternal->refcnt = 1;
 136         ledinternal->netfilter_led_trigger.name = ledinternal->trigger_id;
 137
 138         err = led_trigger_register(&ledinternal->netfilter_led_trigger);
 139         if (err) {
 140                 pr_err("Trigger name is already in use.\n");
 141                 goto exit_alloc;
 142         }
 143
 144         /* See if we need to set up a timer */
 145         if (ledinfo->delay > 0)
 146                 setup_timer(&ledinternal->timer, led_timeout_callback,
 147                             (unsigned long)ledinternal);
 148
 149         list_add_tail(&ledinternal->list, &xt_led_triggers);
 150
 151 out:
 152         mutex_unlock(&xt_led_mutex);
 153
 154         ledinfo->internal_data = ledinternal;
 155
 156         return 0;
 157
 158 exit_alloc:
 159         kfree(ledinternal->trigger_id);
 160
 161 exit_internal_alloc:
 162         kfree(ledinternal);
 163
 164 exit_mutex_only:
 165         mutex_unlock(&xt_led_mutex);
 166
 167         return err;
 168 }
 169
 170 static void led_tg_destroy(const struct xt_tgdtor_param *par)
 171 {
 172         const struct xt_led_info *ledinfo = par->targinfo;
 173         struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
 174
 175         mutex_lock(&xt_led_mutex);
 176
 177         if (--ledinternal->refcnt) {
 178                 mutex_unlock(&xt_led_mutex);
 179                 return;
 180         }
 181
 182         list_del(&ledinternal->list);
 183
 184         if (ledinfo->delay > 0)
 185                 del_timer_sync(&ledinternal->timer);
 186
 187         led_trigger_unregister(&ledinternal->netfilter_led_trigger);
 188
 189         mutex_unlock(&xt_led_mutex);
 190
 191         kfree(ledinternal->trigger_id);
 192         kfree(ledinternal);
 193 }
 194
 195 static struct xt_target led_tg_reg __read_mostly = {
 196         .name           = "LED",
 197         .revision       = 0,
 198         .family         = NFPROTO_UNSPEC,
 199         .target         = led_tg,
 200         .targetsize     = sizeof(struct xt_led_info),
 201         .checkentry     = led_tg_check,
 202         .destroy        = led_tg_destroy,
 203         .me             = THIS_MODULE,
 204 };
 205
 206 static int __init led_tg_init(void)
 207 {
 208         return xt_register_target(&led_tg_reg);
 209 }
 210
 211 static void __exit led_tg_exit(void)
 212 {
 213         xt_unregister_target(&led_tg_reg);
 214 }
 215
 216 module_init(led_tg_init);
 217 module_exit(led_tg_exit);