[PATCH 6/7][RFC] netfilter: xt_IDLETIMER: Add new netlink msg type

[John Stultz <john.stultz@linaro.org>]

From: JP Abgrall <jpa@google.com>

Send notifications when the label becomes active after an idle period.
Send netlink message notifications in addition to sysfs notifications.
Using a uevent with
  subsystem=xt_idletimer
  INTERFACE=...
  STATE={active,inactive}

This is backport from common android-3.0
commit: beb914e987cbbd368988d2b94a6661cb907c4d5a
with uevent support instead of a new netlink message type.

Cc: netdev@vger.kernel.org
Cc: JP Abgrall <jpa@google.com>
Cc: Ashish Sharma <ashishsharma@google.com>
Cc: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Ashish Sharma <ashishsharma@google.com>
Signed-off-by: JP Abgrall <jpa@google.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
 include/linux/netfilter/xt_IDLETIMER.h |    8 ++++
 net/netfilter/xt_IDLETIMER.c           |   78 +++++++++++++++++++++++++++++---
 2 files changed, 79 insertions(+), 7 deletions(-)

diff --git a/include/linux/netfilter/xt_IDLETIMER.h b/include/linux/netfilter/xt_IDLETIMER.h
index 208ae93..faaa28b 100644
--- a/include/linux/netfilter/xt_IDLETIMER.h
+++ b/include/linux/netfilter/xt_IDLETIMER.h
@@ -4,6 +4,7 @@
  * 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
@@ -32,12 +33,19 @@
 #include <linux/types.h>
 
 #define MAX_IDLETIMER_LABEL_SIZE 28
+#define NLMSG_MAX_SIZE 64
+
+#define NL_EVENT_TYPE_INACTIVE 0
+#define NL_EVENT_TYPE_ACTIVE 1
 
 struct idletimer_tg_info {
 	__u32 timeout;
 
 	char label[MAX_IDLETIMER_LABEL_SIZE];
 
+	/* Use netlink messages for notification in addition to sysfs */
+	__u8 send_nl_msg;
+
 	/* for kernel module internal use only */
 	struct idletimer_tg *timer __attribute__((aligned(8)));
 };
diff --git a/net/netfilter/xt_IDLETIMER.c b/net/netfilter/xt_IDLETIMER.c
index f407ebc1..df91e26 100644
--- a/net/netfilter/xt_IDLETIMER.c
+++ b/net/netfilter/xt_IDLETIMER.c
@@ -5,6 +5,7 @@
  * After timer expires a kevent will be sent.
  *
  * Copyright (C) 2004, 2010 Nokia Corporation
+ *
  * Written by Timo Teras <ext-timo.teras@nokia.com>
  *
  * Converted to x_tables and reworked for upstream inclusion
@@ -38,8 +39,10 @@
 #include <linux/netfilter/xt_IDLETIMER.h>
 #include <linux/kdev_t.h>
 #include <linux/kobject.h>
+#include <linux/skbuff.h>
 #include <linux/workqueue.h>
 #include <linux/sysfs.h>
+#include <net/net_namespace.h>
 
 struct idletimer_tg_attr {
 	struct attribute attr;
@@ -56,6 +59,8 @@ struct idletimer_tg {
 	struct idletimer_tg_attr attr;
 
 	unsigned int refcnt;
+	bool send_nl_msg;
+	bool active;
 };
 
 static LIST_HEAD(idletimer_tg_list);
@@ -63,6 +68,32 @@ static DEFINE_MUTEX(list_mutex);
 
 static struct kobject *idletimer_tg_kobj;
 
+static void notify_netlink_uevent(const char *iface, struct idletimer_tg *timer)
+{
+	char iface_msg[NLMSG_MAX_SIZE];
+	char state_msg[NLMSG_MAX_SIZE];
+	char *envp[] = { iface_msg, state_msg, NULL };
+	int res;
+
+	res = snprintf(iface_msg, NLMSG_MAX_SIZE, "INTERFACE=%s",
+		       iface);
+	if (NLMSG_MAX_SIZE <= res) {
+		pr_err("message too long (%d)", res);
+		return;
+	}
+	res = snprintf(state_msg, NLMSG_MAX_SIZE, "STATE=%s",
+		       timer->active ? "active" : "inactive");
+	if (NLMSG_MAX_SIZE <= res) {
+		pr_err("message too long (%d)", res);
+		return;
+	}
+	pr_debug("putting nlmsg: <%s> <%s>\n", iface_msg, state_msg);
+	kobject_uevent_env(idletimer_tg_kobj, KOBJ_CHANGE, envp);
+	return;
+
+
+}
+
 static
 struct idletimer_tg *__idletimer_tg_find_by_label(const char *label)
 {
@@ -83,6 +114,7 @@ static ssize_t idletimer_tg_show(struct kobject *kobj, struct attribute *attr,
 {
 	struct idletimer_tg *timer;
 	unsigned long expires = 0;
+	unsigned long now = jiffies;
 
 	mutex_lock(&list_mutex);
 
@@ -92,11 +124,15 @@ static ssize_t idletimer_tg_show(struct kobject *kobj, struct attribute *attr,
 
 	mutex_unlock(&list_mutex);
 
-	if (time_after(expires, jiffies))
+	if (time_after(expires, now))
 		return sprintf(buf, "%u\n",
-			       jiffies_to_msecs(expires - jiffies) / 1000);
+			       jiffies_to_msecs(expires - now) / 1000);
 
-	return sprintf(buf, "0\n");
+	if (timer->send_nl_msg)
+		return sprintf(buf, "0 %d\n",
+			jiffies_to_msecs(now - expires) / 1000);
+	else
+		return sprintf(buf, "0\n");
 }
 
 static void idletimer_tg_work(struct work_struct *work)
@@ -105,6 +141,9 @@ static void idletimer_tg_work(struct work_struct *work)
 						  work);
 
 	sysfs_notify(idletimer_tg_kobj, NULL, timer->attr.attr.name);
+
+	if (timer->send_nl_msg)
+		notify_netlink_uevent(timer->attr.attr.name, timer);
 }
 
 static void idletimer_tg_expired(unsigned long data)
@@ -113,6 +152,7 @@ static void idletimer_tg_expired(unsigned long data)
 
 	pr_debug("timer %s expired\n", timer->attr.attr.name);
 
+	timer->active = false;
 	schedule_work(&timer->work);
 }
 
@@ -145,6 +185,8 @@ static int idletimer_tg_create(struct idletimer_tg_info *info)
 	setup_timer(&info->timer->timer, idletimer_tg_expired,
 		    (unsigned long) info->timer);
 	info->timer->refcnt = 1;
+	info->timer->send_nl_msg = (info->send_nl_msg == 0) ? false : true;
+	info->timer->active = true;
 
 	mod_timer(&info->timer->timer,
 		  msecs_to_jiffies(info->timeout * 1000) + jiffies);
@@ -168,14 +210,24 @@ static unsigned int idletimer_tg_target(struct sk_buff *skb,
 					 const struct xt_action_param *par)
 {
 	const struct idletimer_tg_info *info = par->targinfo;
+	unsigned long now = jiffies;
 
 	pr_debug("resetting timer %s, timeout period %u\n",
 		 info->label, info->timeout);
 
 	BUG_ON(!info->timer);
 
+	info->timer->active = true;
+
+	if (time_before(info->timer->timer.expires, now)) {
+		schedule_work(&info->timer->work);
+		pr_debug("Starting timer %s (Expired, Jiffies): %lu, %lu\n",
+			 info->label, info->timer->timer.expires, now);
+	}
+
+	/* TODO: Avoid modifying timers on each packet */
 	mod_timer(&info->timer->timer,
-		  msecs_to_jiffies(info->timeout * 1000) + jiffies);
+		  msecs_to_jiffies(info->timeout * 1000) + now);
 
 	return XT_CONTINUE;
 }
@@ -184,8 +236,9 @@ static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
 {
 	struct idletimer_tg_info *info = par->targinfo;
 	int ret;
+	unsigned long now = jiffies;
 
-	pr_debug("checkentry targinfo%s\n", info->label);
+	pr_debug("checkentry targinfo %s\n", info->label);
 
 	if (info->timeout == 0) {
 		pr_debug("timeout value is zero\n");
@@ -204,8 +257,16 @@ static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
 	info->timer = __idletimer_tg_find_by_label(info->label);
 	if (info->timer) {
 		info->timer->refcnt++;
+		info->timer->active = true;
+
+		if (time_before(info->timer->timer.expires, now)) {
+			schedule_work(&info->timer->work);
+			pr_debug("Starting Checkentry timer (Expired, Jiffies): %lu, %lu\n",
+				info->timer->timer.expires, now);
+		}
+
 		mod_timer(&info->timer->timer,
-			  msecs_to_jiffies(info->timeout * 1000) + jiffies);
+			  msecs_to_jiffies(info->timeout * 1000) + now);
 
 		pr_debug("increased refcnt of timer %s to %u\n",
 			 info->label, info->timer->refcnt);
@@ -219,6 +280,7 @@ static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
 	}
 
 	mutex_unlock(&list_mutex);
+
 	return 0;
 }
 
@@ -240,7 +302,7 @@ static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
 		kfree(info->timer);
 	} else {
 		pr_debug("decreased refcnt of timer %s to %u\n",
-			 info->label, info->timer->refcnt);
+		info->label, info->timer->refcnt);
 	}
 
 	mutex_unlock(&list_mutex);
@@ -248,6 +310,7 @@ static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
 
 static struct xt_target idletimer_tg __read_mostly = {
 	.name		= "IDLETIMER",
+	.revision	= 1,
 	.family		= NFPROTO_UNSPEC,
 	.target		= idletimer_tg_target,
 	.targetsize     = sizeof(struct idletimer_tg_info),
@@ -313,3 +376,4 @@ MODULE_DESCRIPTION("Xtables: idle time monitor");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("ipt_IDLETIMER");
 MODULE_ALIAS("ip6t_IDLETIMER");
+MODULE_ALIAS("arpt_IDLETIMER");
-- 
1.7.9.5