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From: Arjan van de Ven <arjan@linux.intel.com>
To: "Serge E. Hallyn" <serge@hallyn.com>, Kees Cook <keescook@chromium.org>
Cc: John Stultz <john.stultz@linaro.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	lkml <linux-kernel@vger.kernel.org>,
	Oren Laadan <orenl@cellrox.com>,
	Ruchi Kandoi <kandoiruchi@google.com>,
	Rom Lemarchand <romlem@android.com>,
	Android Kernel Team <kernel-team@android.com>,
	Todd Kjos <tkjos@google.com>, Colin Cross <ccross@android.com>,
	Nick Kralevich <nnk@google.com>,
	Dmitry Shmidt <dimitrysh@google.com>,
	Elliott Hughes <enh@google.com>
Subject: Re: [PATCH 2/2] proc: Add /proc/<pid>/timerslack_ns interface
Date: Thu, 14 Jul 2016 06:42:04 -0700	[thread overview]
Message-ID: <7d7579a1-2616-0437-5319-23190906a2b4@linux.intel.com> (raw)
In-Reply-To: <20160714124806.GB31333@mail.hallyn.com>

On 7/14/2016 5:48 AM, Serge E. Hallyn wrote:

> Can someone give a detailed explanation of what you could do with
> the new timerslack feature and compare it to what you can do with
> sys_nice?
>

what you can do with the timerslack feature is add upto 4 seconds of extra
time/delay on top of each select()/poll()/nanosleep()/... (basically anything that
uses hrtimers on behalf of the user), and then also control within that
4 second window exactly when that extra delay ends
(which may help a timing attack kind of scenario)

  reply	other threads:[~2016-07-14 13:42 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-17  1:06 [PATCH 0/2] Extend timer_slack_ns to u64 on 32bit systems & add /proc/<pid>/timerslack_ns John Stultz
2016-02-17  1:06 ` [PATCH 1/2] timer: Convert timer_slack_ns from unsigned long to u64 John Stultz
2016-02-17  1:06 ` [PATCH 2/2] proc: Add /proc/<pid>/timerslack_ns interface John Stultz
2016-02-17 19:35   ` Andrew Morton
2016-02-17 20:09     ` Kees Cook
2016-02-17 20:18       ` Andrew Morton
2016-02-17 20:51         ` John Stultz
2016-02-17 21:07           ` Andrew Morton
2016-02-17 22:29         ` John Stultz
2016-02-17 22:45           ` Kees Cook
2016-02-17 22:51             ` John Stultz
2016-02-17 22:53           ` Andrew Morton
2016-02-17 20:49     ` John Stultz
2016-02-18  5:59   ` [PATCH] proc: /proc/<pid>/timerslack_ns permissions fixes John Stultz
2016-02-18 17:52     ` Kees Cook
2016-07-13 23:47   ` [PATCH 2/2] proc: Add /proc/<pid>/timerslack_ns interface John Stultz
2016-07-14  3:39     ` Kees Cook
2016-07-14  5:29       ` Arjan van de Ven
2016-07-14 12:48       ` Serge E. Hallyn
2016-07-14 13:42         ` Arjan van de Ven [this message]
2016-07-14 16:01           ` John Stultz
2016-07-14 16:09         ` John Stultz
2016-07-14 17:45           ` Kees Cook
2016-07-14 17:48             ` Arjan van de Ven
2016-07-14 17:49             ` Serge E. Hallyn
2016-07-14 17:56               ` Kees Cook
2016-07-14 20:21                 ` Serge E. Hallyn

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