xt_LED.c (5068B)
1// SPDX-License-Identifier: GPL-2.0-only 2/* 3 * xt_LED.c - netfilter target to make LEDs blink upon packet matches 4 * 5 * Copyright (C) 2008 Adam Nielsen <a.nielsen@shikadi.net> 6 */ 7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 8#include <linux/module.h> 9#include <linux/skbuff.h> 10#include <linux/netfilter/x_tables.h> 11#include <linux/slab.h> 12#include <linux/leds.h> 13#include <linux/mutex.h> 14 15#include <linux/netfilter/xt_LED.h> 16 17MODULE_LICENSE("GPL"); 18MODULE_AUTHOR("Adam Nielsen <a.nielsen@shikadi.net>"); 19MODULE_DESCRIPTION("Xtables: trigger LED devices on packet match"); 20MODULE_ALIAS("ipt_LED"); 21MODULE_ALIAS("ip6t_LED"); 22 23static LIST_HEAD(xt_led_triggers); 24static DEFINE_MUTEX(xt_led_mutex); 25 26/* 27 * This is declared in here (the kernel module) only, to avoid having these 28 * dependencies in userspace code. This is what xt_led_info.internal_data 29 * points to. 30 */ 31struct xt_led_info_internal { 32 struct list_head list; 33 int refcnt; 34 char *trigger_id; 35 struct led_trigger netfilter_led_trigger; 36 struct timer_list timer; 37}; 38 39#define XT_LED_BLINK_DELAY 50 /* ms */ 40 41static unsigned int 42led_tg(struct sk_buff *skb, const struct xt_action_param *par) 43{ 44 const struct xt_led_info *ledinfo = par->targinfo; 45 struct xt_led_info_internal *ledinternal = ledinfo->internal_data; 46 unsigned long led_delay = XT_LED_BLINK_DELAY; 47 48 /* 49 * If "always blink" is enabled, and there's still some time until the 50 * LED will switch off, briefly switch it off now. 51 */ 52 if ((ledinfo->delay > 0) && ledinfo->always_blink && 53 timer_pending(&ledinternal->timer)) 54 led_trigger_blink_oneshot(&ledinternal->netfilter_led_trigger, 55 &led_delay, &led_delay, 1); 56 else 57 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL); 58 59 /* If there's a positive delay, start/update the timer */ 60 if (ledinfo->delay > 0) { 61 mod_timer(&ledinternal->timer, 62 jiffies + msecs_to_jiffies(ledinfo->delay)); 63 64 /* Otherwise if there was no delay given, blink as fast as possible */ 65 } else if (ledinfo->delay == 0) { 66 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF); 67 } 68 69 /* else the delay is negative, which means switch on and stay on */ 70 71 return XT_CONTINUE; 72} 73 74static void led_timeout_callback(struct timer_list *t) 75{ 76 struct xt_led_info_internal *ledinternal = from_timer(ledinternal, t, 77 timer); 78 79 led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF); 80} 81 82static struct xt_led_info_internal *led_trigger_lookup(const char *name) 83{ 84 struct xt_led_info_internal *ledinternal; 85 86 list_for_each_entry(ledinternal, &xt_led_triggers, list) { 87 if (!strcmp(name, ledinternal->netfilter_led_trigger.name)) { 88 return ledinternal; 89 } 90 } 91 return NULL; 92} 93 94static int led_tg_check(const struct xt_tgchk_param *par) 95{ 96 struct xt_led_info *ledinfo = par->targinfo; 97 struct xt_led_info_internal *ledinternal; 98 int err; 99 100 if (ledinfo->id[0] == '\0') 101 return -EINVAL; 102 103 mutex_lock(&xt_led_mutex); 104 105 ledinternal = led_trigger_lookup(ledinfo->id); 106 if (ledinternal) { 107 ledinternal->refcnt++; 108 goto out; 109 } 110 111 err = -ENOMEM; 112 ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL); 113 if (!ledinternal) 114 goto exit_mutex_only; 115 116 ledinternal->trigger_id = kstrdup(ledinfo->id, GFP_KERNEL); 117 if (!ledinternal->trigger_id) 118 goto exit_internal_alloc; 119 120 ledinternal->refcnt = 1; 121 ledinternal->netfilter_led_trigger.name = ledinternal->trigger_id; 122 123 err = led_trigger_register(&ledinternal->netfilter_led_trigger); 124 if (err) { 125 pr_info_ratelimited("Trigger name is already in use.\n"); 126 goto exit_alloc; 127 } 128 129 /* Since the letinternal timer can be shared between multiple targets, 130 * always set it up, even if the current target does not need it 131 */ 132 timer_setup(&ledinternal->timer, led_timeout_callback, 0); 133 134 list_add_tail(&ledinternal->list, &xt_led_triggers); 135 136out: 137 mutex_unlock(&xt_led_mutex); 138 139 ledinfo->internal_data = ledinternal; 140 141 return 0; 142 143exit_alloc: 144 kfree(ledinternal->trigger_id); 145 146exit_internal_alloc: 147 kfree(ledinternal); 148 149exit_mutex_only: 150 mutex_unlock(&xt_led_mutex); 151 152 return err; 153} 154 155static void led_tg_destroy(const struct xt_tgdtor_param *par) 156{ 157 const struct xt_led_info *ledinfo = par->targinfo; 158 struct xt_led_info_internal *ledinternal = ledinfo->internal_data; 159 160 mutex_lock(&xt_led_mutex); 161 162 if (--ledinternal->refcnt) { 163 mutex_unlock(&xt_led_mutex); 164 return; 165 } 166 167 list_del(&ledinternal->list); 168 169 del_timer_sync(&ledinternal->timer); 170 171 led_trigger_unregister(&ledinternal->netfilter_led_trigger); 172 173 mutex_unlock(&xt_led_mutex); 174 175 kfree(ledinternal->trigger_id); 176 kfree(ledinternal); 177} 178 179static struct xt_target led_tg_reg __read_mostly = { 180 .name = "LED", 181 .revision = 0, 182 .family = NFPROTO_UNSPEC, 183 .target = led_tg, 184 .targetsize = sizeof(struct xt_led_info), 185 .usersize = offsetof(struct xt_led_info, internal_data), 186 .checkentry = led_tg_check, 187 .destroy = led_tg_destroy, 188 .me = THIS_MODULE, 189}; 190 191static int __init led_tg_init(void) 192{ 193 return xt_register_target(&led_tg_reg); 194} 195 196static void __exit led_tg_exit(void) 197{ 198 xt_unregister_target(&led_tg_reg); 199} 200 201module_init(led_tg_init); 202module_exit(led_tg_exit);