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(struct timer_list *t)
  89 {
  90         struct xt_led_info_internal *ledinternal = from_timer(ledinternal, t,
  91                                                               timer);
  92
  93         led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
  94 }
  95
  96 static struct xt_led_info_internal *led_trigger_lookup(const char *name)
  97 {
  98         struct xt_led_info_internal *ledinternal;
  99
 100         list_for_each_entry(ledinternal, &xt_led_triggers, list) {
 101                 if (!strcmp(name, ledinternal->netfilter_led_trigger.name)) {
 102                         return ledinternal;
 103                 }
 104         }
 105         return NULL;
 106 }
 107
 108 static int led_tg_check(const struct xt_tgchk_param *par)
 109 {
 110         struct xt_led_info *ledinfo = par->targinfo;
 111         struct xt_led_info_internal *ledinternal;
 112         int err;
 113
 114         if (ledinfo->id[0] == '\0')
 115                 return -EINVAL;
 116
 117         mutex_lock(&xt_led_mutex);
 118
 119         ledinternal = led_trigger_lookup(ledinfo->id);
 120         if (ledinternal) {
 121                 ledinternal->refcnt++;
 122                 goto out;
 123         }
 124
 125         err = -ENOMEM;
 126         ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL);
 127         if (!ledinternal)
 128                 goto exit_mutex_only;
 129
 130         ledinternal->trigger_id = kstrdup(ledinfo->id, GFP_KERNEL);
 131         if (!ledinternal->trigger_id)
 132                 goto exit_internal_alloc;
 133
 134         ledinternal->refcnt = 1;
 135         ledinternal->netfilter_led_trigger.name = ledinternal->trigger_id;
 136
 137         err = led_trigger_register(&ledinternal->netfilter_led_trigger);
 138         if (err) {
 139                 pr_info_ratelimited("Trigger name is already in use.\n");
 140                 goto exit_alloc;
 141         }
 142
 143         /* Since the letinternal timer can be shared between multiple targets,
 144          * always set it up, even if the current target does not need it
 145          */
 146         timer_setup(&ledinternal->timer, led_timeout_callback, 0);
 147
 148         list_add_tail(&ledinternal->list, &xt_led_triggers);
 149
 150 out:
 151         mutex_unlock(&xt_led_mutex);
 152
 153         ledinfo->internal_data = ledinternal;
 154
 155         return 0;
 156
 157 exit_alloc:
 158         kfree(ledinternal->trigger_id);
 159
 160 exit_internal_alloc:
 161         kfree(ledinternal);
 162
 163 exit_mutex_only:
 164         mutex_unlock(&xt_led_mutex);
 165
 166         return err;
 167 }
 168
 169 static void led_tg_destroy(const struct xt_tgdtor_param *par)
 170 {
 171         const struct xt_led_info *ledinfo = par->targinfo;
 172         struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
 173
 174         mutex_lock(&xt_led_mutex);
 175
 176         if (--ledinternal->refcnt) {
 177                 mutex_unlock(&xt_led_mutex);
 178                 return;
 179         }
 180
 181         list_del(&ledinternal->list);
 182
 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         .usersize       = offsetof(struct xt_led_info, internal_data),
 200         .checkentry     = led_tg_check,
 201         .destroy        = led_tg_destroy,
 202         .me             = THIS_MODULE,
 203 };
 204
 205 static int __init led_tg_init(void)
 206 {
 207         return xt_register_target(&led_tg_reg);
 208 }
 209
 210 static void __exit led_tg_exit(void)
 211 {
 212         xt_unregister_target(&led_tg_reg);
 213 }
 214
 215 module_init(led_tg_init);
 216 module_exit(led_tg_exit);