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); 216