Kernel module providing implementation of LED netfilter target. Each
instance of the target appears as a led-trigger device, which can be
associated with one or more LEDs in /sys/class/leds/
Signed-off-by: Adam Nielsen <a.nielsen@xxxxxxxxxxx>
---
Here's the kernel module. I haven't removed the /*noconst*/ as
queried by Alexey Dobriyan, as my justification for having it seems
to have been accepted.
Changes since the last post:
- Fixed variadic-size types in xt_led_info
- Made use of KBUILD_MODNAME
- Added --led-always-blink since Jan suggested the commented out
code could be a feature :-)
- Added KERN_ levels to all printk()s
- Coding style fixes
- xt_led_info moved to the shared .h file
diff -urN linux-2.6.28-rc3-orig/drivers/leds/Kconfig linux-2.6.28-rc3/drivers/leds/Kconfig
--- linux-2.6.28-rc3-orig/drivers/leds/Kconfig 2008-11-09 22:02:17.912599258 +1000
+++ linux-2.6.28-rc3/drivers/leds/Kconfig 2008-11-09 22:47:32.889599211 +1000
@@ -217,4 +217,7 @@
This allows LEDs to be initialised in the ON state.
If unsure, say Y.
+comment "iptables trigger is under Netfilter config (LED target)"
+ depends on LEDS_TRIGGERS
+
endif # NEW_LEDS
diff -urN linux-2.6.28-rc3-orig/include/linux/netfilter/Kbuild linux-2.6.28-rc3/include/linux/netfilter/Kbuild
--- linux-2.6.28-rc3-orig/include/linux/netfilter/Kbuild 2008-11-09 22:02:23.499608250 +1000
+++ linux-2.6.28-rc3/include/linux/netfilter/Kbuild 2008-11-11 17:47:43.800616209 +1000
@@ -7,6 +7,7 @@
header-y += xt_CONNMARK.h
header-y += xt_CONNSECMARK.h
header-y += xt_DSCP.h
+header-y += xt_LED.h
header-y += xt_MARK.h
header-y += xt_NFLOG.h
header-y += xt_NFQUEUE.h
diff -urN linux-2.6.28-rc3-orig/include/linux/netfilter/xt_LED.h linux-2.6.28-rc3/include/linux/netfilter/xt_LED.h
--- linux-2.6.28-rc3-orig/include/linux/netfilter/xt_LED.h 1970-01-01 10:00:00.000000000 +1000
+++ linux-2.6.28-rc3/include/linux/netfilter/xt_LED.h 2008-11-11 17:48:16.746607591 +1000
@@ -0,0 +1,12 @@
+#ifndef _XT_LED_H
+#define _XT_LED_H
+
+struct xt_led_info {
+ char id[26]; /* Unique ID for this trigger in the LED class */
+ __u32 delay; /* Delay until LED is switched off after trigger */
+ __u8 always_blink; /* Blink even if the LED is already on */
+
+ void *internal_data; /* Kernel data used in the module */
+};
+
+#endif /* _XT_LED_H */
diff -urN linux-2.6.28-rc3-orig/net/netfilter/Kconfig linux-2.6.28-rc3/net/netfilter/Kconfig
--- linux-2.6.28-rc3-orig/net/netfilter/Kconfig 2008-11-09 22:02:24.010636621 +1000
+++ linux-2.6.28-rc3/net/netfilter/Kconfig 2008-11-10 20:37:42.030603692 +1000
@@ -357,6 +357,30 @@
To compile it as a module, choose M here. If unsure, say N.
+config NETFILTER_XT_TARGET_LED
+ tristate '"LED" target support'
+ depends on LEDS_CLASS
+ depends on NETFILTER_ADVANCED
+ help
+ This option adds a `LED' target, which allows you to blink LEDs in
+ response to particular packets passing through your machine.
+
+ This can be used to turn a spare LED into a network activity LED,
+ which only flashes in response to FTP transfers, for example. Or
+ you could have an LED which lights up for a minute or two every time
+ somebody connects to your machine via SSH.
+
+ You will need support for the "led" class to make this work.
+
+ To create an LED trigger for incoming SSH traffic:
+ iptables -A INPUT -p tcp --dport 22 -j LED --led-trigger-id ssh --led-delay 1000
+
+ Then attach the new trigger to an LED on your system:
+ echo netfilter-ssh > /sys/class/leds/<ledname>/trigger
+
+ For more information on the LEDs available on your system, see
+ Documentation/leds-class.txt
+
config NETFILTER_XT_TARGET_MARK
tristate '"MARK" target support'
default m if NETFILTER_ADVANCED=n
diff -urN linux-2.6.28-rc3-orig/net/netfilter/Makefile linux-2.6.28-rc3/net/netfilter/Makefile
--- linux-2.6.28-rc3-orig/net/netfilter/Makefile 2008-11-09 22:02:24.010636621 +1000
+++ linux-2.6.28-rc3/net/netfilter/Makefile 2008-11-09 22:38:22.580607716 +1000
@@ -45,6 +45,7 @@
obj-$(CONFIG_NETFILTER_XT_TARGET_CONNMARK) += xt_CONNMARK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_DSCP) += xt_DSCP.o
+obj-$(CONFIG_NETFILTER_XT_TARGET_LED) += xt_LED.o
obj-$(CONFIG_NETFILTER_XT_TARGET_MARK) += xt_MARK.o
obj-$(CONFIG_NETFILTER_XT_TARGET_NFLOG) += xt_NFLOG.o
obj-$(CONFIG_NETFILTER_XT_TARGET_NFQUEUE) += xt_NFQUEUE.o
diff -urN linux-2.6.28-rc3-orig/net/netfilter/xt_LED.c linux-2.6.28-rc3/net/netfilter/xt_LED.c
--- linux-2.6.28-rc3-orig/net/netfilter/xt_LED.c 1970-01-01 10:00:00.000000000 +1000
+++ linux-2.6.28-rc3/net/netfilter/xt_LED.c 2008-11-11 20:33:48.599617594 +1000
@@ -0,0 +1,191 @@
+/*
+ * xt_LED.c - netfilter target to make LEDs blink upon packet matches
+ *
+ * Copyright (C) 2008 Adam Nielsen <a.nielsen@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301 USA.
+ *
+ */
+
+/*
+ * Known issues:
+ *
+ * - It's possible to add multiple led triggers with the same name (as
+ * set with --led-trigger-id)
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter/x_tables.h>
+#include <linux/leds.h>
+#include <linux/mutex.h>
+
+#include <linux/netfilter/xt_LED.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Adam Nielsen <a.nielsen@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("Xtables: trigger LED devices on packet match");
+
+/* This is declared in here (the kernel module) only, to avoid having these
+ dependencies in userspace code. This is what xt_led_info.internal_data
+ points to. */
+struct xt_led_info_internal {
+ struct led_trigger netfilter_led_trigger;
+ struct timer_list timer;
+ struct mutex led_changing_state;
+};
+
+static unsigned int
+led_tg(struct sk_buff *skb, const struct xt_target_param *par)
+{
+ const struct xt_led_info *ledinfo = par->targinfo;
+ /*noconst*/struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
+
+ /* Make sure the timer callback doesn't go switching the LED off while
+ we're figuring out what to do */
+ if (ledinfo->delay > 0) {
+ mutex_lock(&ledinternal->led_changing_state);
+
+ /* If the LED is currently on, it could be some time before it
+ switches off again. Another matching packet has arrived
+ though, so if always_blink is on, the code below will
+ briefly turn the LED off to signal the new packet. It will
+ be switched on again below, then stay on for the full
+ timeout again. */
+ if (ledinfo->always_blink && timer_pending(&ledinternal->timer))
+ led_trigger_event(&ledinternal->netfilter_led_trigger,
+ LED_OFF);
+ }
+
+ led_trigger_event(&ledinternal->netfilter_led_trigger, LED_FULL);
+
+ /* If there's a positive delay, start/update the timer */
+ if (ledinfo->delay > 0) {
+ mod_timer(&ledinternal->timer,
+ jiffies + msecs_to_jiffies(ledinfo->delay));
+ /* If there's a *huge* delay right here (enough for the timer
+ to expire), it could cause the LED to remain stuck on until
+ the next packet, but it's probably not worth worrying
+ about... */
+ mutex_unlock(&ledinternal->led_changing_state);
+
+ /* Otherwise if there was no delay given, blink as fast as possible */
+ } else if (ledinfo->delay == 0) {
+ led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
+ }
+
+ /* else the delay is negative, which means switch on and stay on */
+
+ return XT_CONTINUE;
+}
+
+static void led_timeout_callback(unsigned long data)
+{
+ struct xt_led_info *ledinfo = (struct xt_led_info *)data;
+ struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
+
+ /* If the timer has expired while we're changing the state, then don't
+ interfere. We also don't want to twiddle with anything after the
+ mutex is unlocked, because by then a new timeout will have been
+ set. */
+ if (mutex_is_locked(&ledinternal->led_changing_state))
+ return;
+
+ led_trigger_event(&ledinternal->netfilter_led_trigger, LED_OFF);
+}
+
+static bool led_tg_check(const struct xt_tgchk_param *par)
+{
+ /*noconst*/ struct xt_led_info *ledinfo = par->targinfo;
+ struct xt_led_info_internal *ledinternal;
+
+ if (ledinfo->id[0] == '\0') {
+ printk(KERN_CRIT KBUILD_MODNAME ": No 'id' parameter given.\n");
+ return false;
+ }
+
+ if (!(ledinternal = kzalloc(sizeof(struct xt_led_info_internal), GFP_KERNEL))) {
+ printk(KERN_CRIT KBUILD_MODNAME ": out of memory\n");
+ return false;
+ }
+
+ ledinternal->netfilter_led_trigger.name = ledinfo->id;
+ mutex_init(&ledinternal->led_changing_state);
+
+ printk(KERN_NOTICE KBUILD_MODNAME ": Adding led trigger \"%s\"\n",
+ ledinfo->id);
+
+ if (led_trigger_register(&ledinternal->netfilter_led_trigger)) {
+ printk(KERN_CRIT KBUILD_MODNAME
+ ": led_trigger_register() failed\n");
+ goto exit_alloc;
+ }
+
+ /* See if we need to set up a timer */
+ if (ledinfo->delay > 0)
+ setup_timer(&ledinternal->timer, led_timeout_callback,
+ (unsigned long) ledinfo);
+
+ ledinfo->internal_data = ledinternal;
+
+ return true;
+
+exit_alloc:
+ kfree(ledinternal);
+
+ return false;
+}
+
+static void led_tg_destroy(const struct xt_tgdtor_param *par)
+{
+ const struct xt_led_info *ledinfo = par->targinfo;
+ /*noconst*/struct xt_led_info_internal *ledinternal = ledinfo->internal_data;
+
+ printk(KERN_NOTICE KBUILD_MODNAME ": Removing led trigger \"%s\"\n",
+ ledinternal->netfilter_led_trigger.name);
+
+ if (ledinfo->delay > 0)
+ del_timer_sync(&ledinternal->timer);
+
+ led_trigger_unregister(&ledinternal->netfilter_led_trigger);
+ kfree(ledinternal);
+}
+
+static struct xt_target led_tg_reg __read_mostly = {
+ .name = "LED",
+ .revision = 0,
+ .family = NFPROTO_UNSPEC,
+ .target = led_tg,
+ .targetsize = XT_ALIGN(sizeof(struct xt_led_info)),
+ .checkentry = led_tg_check,
+ .destroy = led_tg_destroy,
+ .me = THIS_MODULE,
+};
+
+static int __init led_tg_init(void)
+{
+ printk(KERN_NOTICE KBUILD_MODNAME ": Registering LED netfilter target\n");
+ return xt_register_target(&led_tg_reg);
+}
+
+static void __exit led_tg_exit(void)
+{
+ printk(KERN_NOTICE KBUILD_MODNAME ": Unregistering LED netfilter target\n");
+ xt_unregister_target(&led_tg_reg);
+}
+
+module_init(led_tg_init);
+module_exit(led_tg_exit);
--
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