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SubjectRe: [PATCH 6/7][RFC] netfilter: xt_IDLETIMER: Add new netlink msg type
On Fri, Sep 21, 2012 at 10:10:52PM -0400, John Stultz wrote:
> 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.

I think this can be candidate to be included once some comestical
issues are fixed.

> 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
> + *

we can live without that extra line above.

> * 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

better define this NLMSG_MAX_SIZE inside xt_IDLETIMER.c, this header
is exported to user-space and that definition is not useful.

> +
> +#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)));
> };

you have to define two structures:

struct idletimer_tg_info
struct idletimer_tg_info_v1

and register both revisions. This (rudimentary) mechanism allows us to
keep backward compatibility.

See net/netfilter/xt_socket.c for instance.

> 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;
> +
> +

extra lines.

> +}
> +
> 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);
> + }

AFAICS, this seems to fix the case in which timer has expired and we
refresh it without sending the notification.

Should go in a different patch.

> +
> + /* 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);
> +

we don't need this.

> 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);

remove this change.

> }
>
> 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");

Interesting, they are really using this with arptables?

> --
> 1.7.9.5
>
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