linux-kernel - Re: [RFC] syscalls, x86: Add __NR

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Message-ID: <4F168E93.5010000@parallels.com>
Date:	Wed, 18 Jan 2012 13:19:15 +0400
From:	Pavel Emelyanov <xemul@...allels.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...il.com>
CC:	Cyrill Gorcunov <gorcunov@...il.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Alexey Dobriyan <adobriyan@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrey Vagin <avagin@...nvz.org>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Glauber Costa <glommer@...allels.com>,
	Andi Kleen <andi@...stfloor.org>, Tejun Heo <tj@...nel.org>,
	Matt Helsley <matthltc@...ibm.com>,
	Pekka Enberg <penberg@...nel.org>,
	Eric Dumazet <eric.dumazet@...il.com>,
	Vasiliy Kulikov <segoon@...nwall.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Valdis.Kletnieks@...edu" <Valdis.Kletnieks@...edu>
Subject: Re: [RFC] syscalls, x86: Add __NR_kcmp syscall

> I think Eric only said gt/lt compare is useful. We don't need to expose bare
> pointer order. example, kcmp(rotate(ptr, per-task-random-value)) is enough
> hide the critical information. I think.

The per-task might break thinks up in case

(tsk1->file != tsk2->file) && (rotate(tsk1->file, tsk1->random) == rotate(tsk2->file, tsk2->rotate))

but I agree, that the overall idea of comparing not bare pointers, but those poisoned with
some global value can address the Peter's concerns about rootkits.

Thanks,
Pavel
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