netfilter: xtables: idletimer target implementation

This patch implements an idletimer Xtables target that can be used to
identify when interfaces have been idle for a certain period of time.

Timers are identified by labels and are created when a rule is set with a new
label.  The rules also take a timeout value (in seconds) as an option.  If
more than one rule uses the same timer label, the timer will be restarted
whenever any of the rules get a hit.

One entry for each timer is created in sysfs.  This attribute contains the
timer remaining for the timer to expire.  The attributes are located under
the xt_idletimer class:

/sys/class/xt_idletimer/timers/<label>

When the timer expires, the target module sends a sysfs notification to the
userspace, which can then decide what to do (eg. disconnect to save power).

Cc: Timo Teras <timo.teras@iki.fi>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>

2 files changed, 46 insertions, 0 deletions

diff --git a/include/linux/netfilter/Kbuild b/include/linux/netfilter/Kbuild
index 48767cd16453..bb103f43afa0 100644
--- a/include/linux/netfilter/Kbuild
+++ b/include/linux/netfilter/Kbuild
@@ -8,6 +8,7 @@ header-y += xt_CONNMARK.h
 header-y += xt_CONNSECMARK.h
 header-y += xt_CT.h
 header-y += xt_DSCP.h
+header-y += xt_IDLETIMER.h
 header-y += xt_LED.h
 header-y += xt_MARK.h
 header-y += xt_NFLOG.h
diff --git a/include/linux/netfilter/xt_IDLETIMER.h b/include/linux/netfilter/xt_IDLETIMER.h
new file mode 100644
index 000000000000..3e1aa1be942e
--- /dev/null
+++ b/include/linux/netfilter/xt_IDLETIMER.h
@@ -0,0 +1,45 @@
+/*
+ * linux/include/linux/netfilter/xt_IDLETIMER.h
+ *
+ * Header file for Xtables timer target module.
+ *
+ * Copyright (C) 2004, 2010 Nokia Corporation
+ * Written by Timo Teras <ext-timo.teras@nokia.com>
+ *
+ * Converted to x_tables and forward-ported to 2.6.34
+ * by Luciano Coelho <luciano.coelho@nokia.com>
+ *
+ * Contact: Luciano Coelho <luciano.coelho@nokia.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * 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 St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#ifndef _XT_IDLETIMER_H
+#define _XT_IDLETIMER_H
+
+#include <linux/types.h>
+
+#define MAX_IDLETIMER_LABEL_SIZE 28
+
+struct idletimer_tg_info {
+        __u32 timeout;
+
+        char label[MAX_IDLETIMER_LABEL_SIZE];
+
+        /* for kernel module internal use only */
+        struct idletimer_tg *timer __attribute((aligned(8)));
+};
+
+#endif