1 /* 2 * xt_LED.c - netfilter target to make LEDs blink upon packet matches 3 * 4 * Copyright (C) 2008 Adam Nielsen <[email protected]> 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 <[email protected]>"); 33 MODULE_DESCRIPTION("Xtables: trigger LED devices on packet match"); 34 35 static LIST_HEAD(xt_led_triggers); 36 static DEFINE_MUTEX(xt_led_mutex); 37 38 /* 39 * This is declared in here (the kernel module) only, to avoid having these 40 * dependencies in userspace code. This is what xt_led_info.internal_data 41 * points to. 42 */ 43 struct xt_led_info_internal { 44 struct list_head list; 45 int refcnt; 46 char *trigger_id; 47 struct led_trigger netfilter_led_trigger; 48 struct timer_list timer; 49 }; 50 51 static unsigned int 52 led_tg(struct sk_buff *skb, const struct xt_action_param *par) 53 { 54 const struct xt_led_info *ledinfo = par->targinfo; 55 struct xt_led_info_internal *ledinternal = ledinfo->internal_data; 56 57 /* 58 * If "always blink" is enabled, and there's still some time until the 59 * LED will switch off, briefly switch it off now. 60 */ 61 if ((ledinfo->delay > 0) && ledinfo->always_blink && 62 timer_pending(&ledinternal->timer)) 63 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF); 64 65 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL); 66 67 /* If there's a positive delay, start/update the timer */ 68 if (ledinfo->delay > 0) { 69 mod_timer(&ledinternal->timer, 70 jiffies + msecs_to_jiffies(ledinfo->delay)); 71 72 /* Otherwise if there was no delay given, blink as fast as possible */ 73 } else if (ledinfo->delay == 0) { 74 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF); 75 } 76 77 /* else the delay is negative, which means switch on and stay on */ 78 79 return XT_CONTINUE; 80 } 81 82 static void led_timeout_callback(unsigned long data) 83 { 84 struct xt_led_info_internal *ledinternal = (struct xt_led_info_internal *)data; 85 86 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF); 87 } 88 89 static struct xt_led_info_internal *led_trigger_lookup(const char *name) 90 { 91 struct xt_led_info_internal *ledinternal; 92 93 list_for_each_entry(ledinternal, &xt_led_triggers, list) { 94 if (!strcmp(name, ledinternal->netfilter_led_trigger.name)) { 95 return ledinternal; 96 } 97 } 98 return NULL; 99 } 100 101 static int led_tg_check(const struct xt_tgchk_param *par) 102 { 103 struct xt_led_info *ledinfo = par->targinfo; 104 struct xt_led_info_internal *ledinternal; 105 int err; 106 107 if (ledinfo->id[0] == '\0') { 108 pr_info("No 'id' parameter given.\n"); 109 return -EINVAL; 110 } 111 112 mutex_lock(&xt_led_mutex); 113 114 ledinternal = led_trigger_lookup(ledinfo->id); 115 if (ledinternal) { 116 ledinternal->refcnt++; 117 goto out; 118 } 119 120 err = -ENOMEM; 121 ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL); 122 if (!ledinternal) 123 goto exit_mutex_only; 124 125 ledinternal->trigger_id = kstrdup(ledinfo->id, GFP_KERNEL); 126 if (!ledinternal->trigger_id) 127 goto exit_internal_alloc; 128 129 ledinternal->refcnt = 1; 130 ledinternal->netfilter_led_trigger.name = ledinternal->trigger_id; 131 132 err = led_trigger_register(&ledinternal->netfilter_led_trigger); 133 if (err) { 134 pr_warning("led_trigger_register() failed\n"); 135 if (err == -EEXIST) 136 pr_warning("Trigger name is already in use.\n"); 137 goto exit_alloc; 138 } 139 140 /* See if we need to set up a timer */ 141 if (ledinfo->delay > 0) 142 setup_timer(&ledinternal->timer, led_timeout_callback, 143 (unsigned long)ledinternal); 144 145 list_add_tail(&ledinternal->list, &xt_led_triggers); 146 147 out: 148 mutex_unlock(&xt_led_mutex); 149 150 ledinfo->internal_data = ledinternal; 151 152 return 0; 153 154 exit_alloc: 155 kfree(ledinternal->trigger_id); 156 157 exit_internal_alloc: 158 kfree(ledinternal); 159 160 exit_mutex_only: 161 mutex_unlock(&xt_led_mutex); 162 163 return err; 164 } 165 166 static void led_tg_destroy(const struct xt_tgdtor_param *par) 167 { 168 const struct xt_led_info *ledinfo = par->targinfo; 169 struct xt_led_info_internal *ledinternal = ledinfo->internal_data; 170 171 mutex_lock(&xt_led_mutex); 172 173 if (--ledinternal->refcnt) { 174 mutex_unlock(&xt_led_mutex); 175 return; 176 } 177 178 list_del(&ledinternal->list); 179 180 if (ledinfo->delay > 0) 181 del_timer_sync(&ledinternal->timer); 182 183 led_trigger_unregister(&ledinternal->netfilter_led_trigger); 184 185 mutex_unlock(&xt_led_mutex); 186 187 kfree(ledinternal->trigger_id); 188 kfree(ledinternal); 189 } 190 191 static struct xt_target led_tg_reg __read_mostly = { 192 .name = "LED", 193 .revision = 0, 194 .family = NFPROTO_UNSPEC, 195 .target = led_tg, 196 .targetsize = sizeof(struct xt_led_info), 197 .checkentry = led_tg_check, 198 .destroy = led_tg_destroy, 199 .me = THIS_MODULE, 200 }; 201 202 static int __init led_tg_init(void) 203 { 204 return xt_register_target(&led_tg_reg); 205 } 206 207 static void __exit led_tg_exit(void) 208 { 209 xt_unregister_target(&led_tg_reg); 210 } 211 212 module_init(led_tg_init); 213 module_exit(led_tg_exit); 214