[PATCH 2/2] netfilter: idletimers - add send_nl_msg field

[dmitry pervushin]

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: JP Abgrall <jpa@xxxxxxxxxx>
Cc: Ashish Sharma <ashishsharma@xxxxxxxxxx>
Cc: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@xxxxxxxxx>
Signed-off-by: Ashish Sharma <ashishsharma@xxxxxxxxxx>
Signed-off-by: JP Abgrall <jpa@xxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Signed-off-by: dmitry pervushin <dmitry.pervushin@xxxxxxxxxx>
---
 include/uapi/linux/netfilter/xt_IDLETIMER.h |   16 +-
 net/netfilter/xt_IDLETIMER.c                |  234 +++++++++++++++++++--------
 2 files changed, 180 insertions(+), 70 deletions(-)

diff --git a/include/uapi/linux/netfilter/xt_IDLETIMER.h b/include/uapi/linux/netfilter/xt_IDLETIMER.h
index 208ae93..e50bc3d 100644
--- a/include/uapi/linux/netfilter/xt_IDLETIMER.h
+++ b/include/uapi/linux/netfilter/xt_IDLETIMER.h
@@ -39,7 +39,21 @@ struct idletimer_tg_info {
 	char label[MAX_IDLETIMER_LABEL_SIZE];
 
 	/* for kernel module internal use only */
-	struct idletimer_tg *timer __attribute__((aligned(8)));
+	struct idletimer_tg *timer __aligned(8);
 };
 
+#define NL_EVENT_TYPE_INACTIVE 0
+#define NL_EVENT_TYPE_ACTIVE 1
+
+struct idletimer_tg_info_v1 {
+	__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 __aligned(8);
+};
 #endif
diff --git a/net/netfilter/xt_IDLETIMER.c b/net/netfilter/xt_IDLETIMER.c
index 3540c04..6eb25ab 100644
--- a/net/netfilter/xt_IDLETIMER.c
+++ b/net/netfilter/xt_IDLETIMER.c
@@ -41,6 +41,8 @@
 #include <linux/workqueue.h>
 #include <linux/sysfs.h>
 
+#define NLMSG_MAX_SIZE 64
+
 struct idletimer_tg_attr {
 	struct attribute attr;
 	ssize_t	(*show)(struct kobject *kobj,
@@ -56,6 +58,8 @@ 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 +67,30 @@ 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 +111,7 @@ 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 +121,15 @@ 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 +138,9 @@ 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)
@@ -113,50 +149,46 @@ 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);
 }
 
-static int idletimer_tg_create(struct idletimer_tg_info *info)
+static int idletimer_tg_create(struct idletimer_tg *timer, const char *label,
+		unsigned long timeout, bool send_nl_msg)
 {
 	int ret;
 
-	info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL);
-	if (!info->timer) {
+	timer->attr.attr.name = kstrdup(label, GFP_KERNEL);
+	if (!timer->attr.attr.name) {
 		ret = -ENOMEM;
 		goto out;
 	}
+	timer->attr.attr.mode = S_IRUGO;
+	timer->attr.show = idletimer_tg_show;
 
-	info->timer->attr.attr.name = kstrdup(info->label, GFP_KERNEL);
-	if (!info->timer->attr.attr.name) {
-		ret = -ENOMEM;
-		goto out_free_timer;
-	}
-	info->timer->attr.attr.mode = S_IRUGO;
-	info->timer->attr.show = idletimer_tg_show;
-
-	ret = sysfs_create_file(idletimer_tg_kobj, &info->timer->attr.attr);
+	ret = sysfs_create_file(idletimer_tg_kobj, &timer->attr.attr);
 	if (ret < 0) {
 		pr_debug("couldn't add file to sysfs");
 		goto out_free_attr;
 	}
 
-	list_add(&info->timer->entry, &idletimer_tg_list);
+	list_add(&timer->entry, &idletimer_tg_list);
 
-	setup_timer(&info->timer->timer, idletimer_tg_expired,
-		    (unsigned long) info->timer);
-	info->timer->refcnt = 1;
+	setup_timer(&timer->timer, idletimer_tg_expired,
+		    (unsigned long)timer);
+	timer->active = true;
+	timer->refcnt = 1;
+	timer->send_nl_msg = send_nl_msg;
 
-	mod_timer(&info->timer->timer,
-		  msecs_to_jiffies(info->timeout * 1000) + jiffies);
+	mod_timer(&timer->timer,
+		  msecs_to_jiffies(timeout * 1000) + jiffies);
 
-	INIT_WORK(&info->timer->work, idletimer_tg_work);
+	INIT_WORK(&timer->work, idletimer_tg_work);
 
 	return 0;
 
 out_free_attr:
-	kfree(info->timer->attr.attr.name);
-out_free_timer:
-	kfree(info->timer);
+	kfree(timer->attr.attr.name);
 out:
 	return ret;
 }
@@ -164,45 +196,60 @@ out:
 /*
  * The actual xt_tables plugin.
  */
-static unsigned int idletimer_tg_target(struct sk_buff *skb,
-					 const struct xt_action_param *par)
+static unsigned int idletimer_tg_target_do(struct idletimer_tg *timer,
+		const char *label, u32 timeout)
 {
-	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);
+		 label, timeout);
 
-	BUG_ON(!info->timer);
+	BUG_ON(!timer);
+	timer->active = true;
 
-	if (time_before(info->timer->timer.expires, now)) {
-		schedule_work(&info->timer->work);
+	if (time_before(timer->timer.expires, now)) {
+		schedule_work(&timer->work);
 		pr_debug("Starting timer %s (Expired, Jiffies): %lu, %lu\n",
-			 info->label, info->timer->timer.expires, now);
+			 label, timer->timer.expires, now);
 	}
 
 	/* TODO: Avoid modifying timers on each packet */
-	mod_timer(&info->timer->timer,
-		  msecs_to_jiffies(info->timeout * 1000) + now);
+	mod_timer(&timer->timer,
+		  msecs_to_jiffies(timeout * 1000) + now);
 
 	return XT_CONTINUE;
 }
 
-static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
+static unsigned int idletimer_tg_target(struct sk_buff *skb,
+					 const struct xt_action_param *par)
+{
+	const struct idletimer_tg_info *info = par->targinfo;
+	return idletimer_tg_target_do(info->timer, info->label, info->timeout);
+}
+
+static unsigned int idletimer_tg_target_v1(struct sk_buff *skb,
+					 const struct xt_action_param *par)
+{
+	const struct idletimer_tg_info_v1 *info = par->targinfo;
+	return idletimer_tg_target_do(info->timer, info->label, info->timeout);
+}
+
+static int idletimer_tg_checkentry_do(struct idletimer_tg **timer_ret,
+		const char *label, u32 timeout, bool send_nl_msg)
 {
-	struct idletimer_tg_info *info = par->targinfo;
 	int ret;
 	unsigned long now = jiffies;
+	struct idletimer_tg *timer;
 
-	pr_debug("checkentry targinfo%s\n", info->label);
+	pr_debug("checkentry targinfo %s\n", label);
 
-	if (info->timeout == 0) {
+	if (timeout == 0) {
 		pr_debug("timeout value is zero\n");
 		return -EINVAL;
 	}
 
-	if (info->label[0] == '\0' ||
-	    strnlen(info->label,
+	if (label[0] == '\0' ||
+	    strnlen(label,
 		    MAX_IDLETIMER_LABEL_SIZE) == MAX_IDLETIMER_LABEL_SIZE) {
 		pr_debug("label is empty or not nul-terminated\n");
 		return -EINVAL;
@@ -210,22 +257,31 @@ static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
 
 	mutex_lock(&list_mutex);
 
-	info->timer = __idletimer_tg_find_by_label(info->label);
-	if (info->timer) {
-		info->timer->refcnt++;
-		if (time_before(info->timer->timer.expires, now)) {
-			schedule_work(&info->timer->work);
+	timer = __idletimer_tg_find_by_label(label);
+	if (timer) {
+		timer->refcnt++;
+		timer->active = true;
+
+		if (time_before(timer->timer.expires, now)) {
+			schedule_work(&timer->work);
 			pr_debug("Starting Checkentry timer (Expired, Jiffies): %lu, %lu\n",
-				info->timer->timer.expires, now);
+				timer->timer.expires, now);
 		}
-		mod_timer(&info->timer->timer,
-			  msecs_to_jiffies(info->timeout * 1000) + now);
+		mod_timer(&timer->timer,
+			  msecs_to_jiffies(timeout * 1000) + now);
 
 		pr_debug("increased refcnt of timer %s to %u\n",
-			 info->label, info->timer->refcnt);
+			 label, timer->refcnt);
 	} else {
-		ret = idletimer_tg_create(info);
+		timer = kmalloc(sizeof(*timer), GFP_KERNEL);
+		if (!timer) {
+			ret = -ENOMEM;
+			mutex_unlock(&list_mutex);
+			return ret;
+		}
+		ret = idletimer_tg_create(timer, label, timeout, send_nl_msg);
 		if (ret < 0) {
+			kfree(timer);
 			pr_debug("failed to create timer\n");
 			mutex_unlock(&list_mutex);
 			return ret;
@@ -233,41 +289,80 @@ static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
 	}
 
 	mutex_unlock(&list_mutex);
+	*timer_ret = timer;
 	return 0;
 }
 
-static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
+static void idletimer_tg_destroy_do(struct idletimer_tg *timer,
+				    const char *label)
 {
-	const struct idletimer_tg_info *info = par->targinfo;
-
-	pr_debug("destroy targinfo %s\n", info->label);
+	pr_debug("destroy targinfo %s\n", label);
 
 	mutex_lock(&list_mutex);
-
-	if (--info->timer->refcnt == 0) {
-		pr_debug("deleting timer %s\n", info->label);
-
-		list_del(&info->timer->entry);
-		del_timer_sync(&info->timer->timer);
-		sysfs_remove_file(idletimer_tg_kobj, &info->timer->attr.attr);
-		kfree(info->timer->attr.attr.name);
-		kfree(info->timer);
+	if (--timer->refcnt == 0) {
+		pr_debug("deleting timer %s\n", label);
+
+		list_del(&timer->entry);
+		del_timer_sync(&timer->timer);
+		sysfs_remove_file(idletimer_tg_kobj, &timer->attr.attr);
+		kfree(timer->attr.attr.name);
+		kfree(timer);
 	} else {
 		pr_debug("decreased refcnt of timer %s to %u\n",
-			 info->label, info->timer->refcnt);
+			 label, timer->refcnt);
 	}
-
 	mutex_unlock(&list_mutex);
 }
 
-static struct xt_target idletimer_tg __read_mostly = {
+static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
+{
+	struct idletimer_tg_info *info = par->targinfo;
+
+	return idletimer_tg_checkentry_do(&info->timer, info->label,
+		info->timeout, false);
+}
+
+static int idletimer_tg_checkentry_v1(const struct xt_tgchk_param *par)
+{
+	struct idletimer_tg_info_v1 *info = par->targinfo;
+
+	return idletimer_tg_checkentry_do(&info->timer, info->label,
+		info->timeout, info->send_nl_msg);
+}
+
+static void idletimer_tg_destroy(const struct xt_tgdtor_param *par)
+{
+	const struct idletimer_tg_info *info = par->targinfo;
+	idletimer_tg_destroy_do(info->timer, info->label);
+}
+
+static void idletimer_tg_destroy_v1(const struct xt_tgdtor_param *par)
+{
+	const struct idletimer_tg_info_v1 *info = par->targinfo;
+	idletimer_tg_destroy_do(info->timer, info->label);
+}
+
+static struct xt_target idletimer_tg[] __read_mostly = {
+{
 	.name		= "IDLETIMER",
+	.revision	= 0,
 	.family		= NFPROTO_UNSPEC,
 	.target		= idletimer_tg_target,
 	.targetsize     = sizeof(struct idletimer_tg_info),
 	.checkentry	= idletimer_tg_checkentry,
 	.destroy        = idletimer_tg_destroy,
 	.me		= THIS_MODULE,
+},
+{
+	.name		= "IDLETIMER",
+	.revision	= 1,
+	.family		= NFPROTO_UNSPEC,
+	.target		= idletimer_tg_target_v1,
+	.targetsize     = sizeof(struct idletimer_tg_info_v1),
+	.checkentry	= idletimer_tg_checkentry_v1,
+	.destroy        = idletimer_tg_destroy_v1,
+	.me		= THIS_MODULE,
+},
 };
 
 static struct class *idletimer_tg_class;
@@ -295,7 +390,7 @@ static int __init idletimer_tg_init(void)
 
 	idletimer_tg_kobj = &idletimer_tg_device->kobj;
 
-	err =  xt_register_target(&idletimer_tg);
+	err = xt_register_targets(idletimer_tg, ARRAY_SIZE(idletimer_tg));
 	if (err < 0) {
 		pr_debug("couldn't register xt target\n");
 		goto out_dev;
@@ -312,7 +407,7 @@ out:
 
 static void __exit idletimer_tg_exit(void)
 {
-	xt_unregister_target(&idletimer_tg);
+	xt_unregister_targets(idletimer_tg, ARRAY_SIZE(idletimer_tg));
 
 	device_destroy(idletimer_tg_class, MKDEV(0, 0));
 	class_destroy(idletimer_tg_class);
@@ -327,3 +422,4 @@ MODULE_DESCRIPTION("Xtables: idle time monitor");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("ipt_IDLETIMER");
 MODULE_ALIAS("ip6t_IDLETIMER");
+MODULE_ALIAS("arpt_IDLETIMER");
-- 
1.7.10.4

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