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