netfilter: xtables: Add snapshot of hardidletimer target

This is a snapshot of hardidletimer netfilter target.

This patch implements a hardidletimer 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)

Compared to IDLETIMER, HARDIDLETIMER can send notifications when
CPU is in suspend too, to notify the timer expiry.

v1->v2: Moved all functionality into IDLETIMER module to avoid
code duplication per comment from Florian.

Signed-off-by: Manoj Basapathi <manojbm@codeaurora.org>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 11 insertions, 1 deletions

diff --git a/include/uapi/linux/netfilter/xt_IDLETIMER.h b/include/uapi/linux/netfilter/xt_IDLETIMER.h
index 3c586a19baea..434e6506abaa 100644
--- a/include/uapi/linux/netfilter/xt_IDLETIMER.h
+++ b/include/uapi/linux/netfilter/xt_IDLETIMER.h
@@ -1,4 +1,3 @@
-/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
 /*
  * linux/include/linux/netfilter/xt_IDLETIMER.h
  *
@@ -33,6 +32,7 @@
 #include <linux/types.h>
 
 #define MAX_IDLETIMER_LABEL_SIZE 28
+#define XT_IDLETIMER_ALARM 0x01
 
 struct idletimer_tg_info {
 	__u32 timeout;
@@ -43,4 +43,14 @@ struct idletimer_tg_info {
 	struct idletimer_tg *timer __attribute__((aligned(8)));
 };
 
+struct idletimer_tg_info_v1 {
+	__u32 timeout;
+
+	char label[MAX_IDLETIMER_LABEL_SIZE];
+
+	__u8 timer_type;
+
+	/* for kernel module internal use only */
+	struct idletimer_tg *timer __attribute__((aligned(8)));
+};
 #endif