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