xt_IDLETIMER:

Add new netlink msg type for IDLETIMER.

Send notifications when the label becomes active after an idle period.
Send netlink message notifications in addition to sysfs notifications.

Change-Id: I31677ef00c94b5f82c8457e5bf9e5e584c23c523
Signed-off-by: Ashish Sharma <ashishsharma@google.com>

3 files changed, 107 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/include/linux/netlink.h b/include/linux/netlink.h
index a9dd895..f434363 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -25,6 +25,7 @@
 #define NETLINK_SCSITRANSPORT	18	/* SCSI Transports */
 #define NETLINK_ECRYPTFS	19
 #define NETLINK_RDMA		20
+#define NETLINK_IDLETIMER	21
 
 #define MAX_LINKS 32		
 
diff --git a/net/netfilter/xt_IDLETIMER.c b/net/netfilter/xt_IDLETIMER.c
index 3bdd443..a192f55 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
@@ -36,10 +37,15 @@
 #include <linux/netfilter.h>
 #include <linux/netfilter/x_tables.h>
 #include <linux/netfilter/xt_IDLETIMER.h>
+#include <linux/netlink.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>
+
+static struct sock *nl_sk;
 
 struct idletimer_tg_attr {
 	struct attribute attr;
@@ -56,6 +62,8 @@ 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 +71,46 @@ static DEFINE_MUTEX(list_mutex);
 
 static struct kobject *idletimer_tg_kobj;
 
+static void notify_netlink(const char *iface, struct idletimer_tg *timer)
+{
+	struct sk_buff *log_skb;
+	size_t size;
+	struct nlmsghdr *nlh;
+	char str[NLMSG_MAX_SIZE];
+	int event_type, res;
+
+	size = NLMSG_SPACE(NLMSG_MAX_SIZE);
+	size = max(size, (size_t)NLMSG_GOODSIZE);
+	log_skb = alloc_skb(size, GFP_ATOMIC);
+	if (!log_skb) {
+		pr_err("xt_cannot alloc skb for logging\n");
+		return;
+	}
+
+	event_type = timer->active ? NL_EVENT_TYPE_ACTIVE
+				: NL_EVENT_TYPE_INACTIVE;
+	res = snprintf(str, NLMSG_MAX_SIZE, "%s %s\n", iface,
+		timer->active ? "ACTIVE" : "INACTIVE");
+	if (NLMSG_MAX_SIZE <= res)
+		goto nlmsg_failure;
+
+	/* NLMSG_PUT() uses "goto nlmsg_failure" */
+	nlh = NLMSG_PUT(log_skb, /*pid*/0, /*seq*/0, event_type,
+			/* Size of message */NLMSG_MAX_SIZE);
+
+	strncpy(NLMSG_DATA(nlh), str, MAX_IDLETIMER_LABEL_SIZE);
+
+	NETLINK_CB(log_skb).dst_group = 1;
+	netlink_broadcast(nl_sk, log_skb, 0, 1, GFP_ATOMIC);
+
+	pr_debug("putting nlmsg: %s", str);
+	return;
+
+nlmsg_failure:  /* Used within NLMSG_PUT() */
+	consume_skb(log_skb);
+	pr_debug("Failed nlmsg_put\n");
+}
+
 static
 struct idletimer_tg *__idletimer_tg_find_by_label(const char *label)
 {
@@ -83,6 +131,7 @@ 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 +141,15 @@ 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 +158,9 @@ 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(timer->attr.attr.name, timer);
 }
 
 static void idletimer_tg_expired(unsigned long data)
@@ -113,6 +169,7 @@ 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);
 }
 
@@ -147,6 +204,8 @@ 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);
@@ -170,14 +229,24 @@ 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;
 }
@@ -186,8 +255,9 @@ 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");
@@ -206,8 +276,17 @@ 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);
@@ -221,6 +300,7 @@ static int idletimer_tg_checkentry(const struct xt_tgchk_param *par)
 	}
 
 	mutex_unlock(&list_mutex);
+
 	return 0;
 }
 
@@ -242,7 +322,7 @@ 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);
@@ -250,6 +330,7 @@ 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),
@@ -289,6 +370,15 @@ static int __init idletimer_tg_init(void)
 		goto out_dev;
 	}
 
+	nl_sk = netlink_kernel_create(&init_net,
+				      NETLINK_IDLETIMER, 1, NULL,
+				      NULL, THIS_MODULE);
+
+	if (!nl_sk) {
+		pr_err("Failed to create netlink socket\n");
+		return -ENOMEM;
+	}
+
 	return 0;
 out_dev:
 	device_destroy(idletimer_tg_class, MKDEV(0, 0));
@@ -315,3 +405,4 @@ MODULE_DESCRIPTION("Xtables: idle time monitor");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("ipt_IDLETIMER");
 MODULE_ALIAS("ip6t_IDLETIMER");
+MODULE_ALIAS("arpt_IDLETIMER");