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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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