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); 217