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From: Vasiliy Kulikov <segoon@openwall.com>
To: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Pavel Emelyanov <xemul@openvz.org>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Pavel Emelyanov <xemul@parallels.com>,
	Andrey Vagin <avagin@openvz.org>,
	KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
	Ingo Molnar <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Glauber Costa <glommer@parallels.com>,
	Andi Kleen <andi@firstfloor.org>, Tejun Heo <tj@kernel.org>,
	Matt Helsley <matthltc@us.ibm.com>,
	Pekka Enberg <penberg@kernel.org>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Valdis.Kletnieks@vt.edu
Subject: Re: [RFC c/r 2/4] [RFC] syscalls, x86: Add __NR_kcmp syscall v7
Date: Fri, 27 Jan 2012 23:37:26 +0400	[thread overview]
Message-ID: <20120127193726.GA13190@albatros> (raw)
In-Reply-To: <20120127175939.795551339@openvz.org>

Hi Cyrill,

On Fri, Jan 27, 2012 at 21:53 +0400, Cyrill Gorcunov wrote:
> +/*
> + * We don't expose real in-memory order of objects for security
> + * reasons, still the comparision results should be suitable for
> + * sorting. Thus, we obfuscate kernel pointers values (using random
> + * cookies obtaned at early boot stage) and compare the production
> + * instead.
> + */
> +static unsigned long cookies[KCMP_TYPES][2] __read_mostly;
> +
> +static long kptr_obfuscate(long v, int type)
> +{
> +	return (v ^ cookies[type][0]) * cookies[type][1];

AFACS, cookies is fully random value, is it possible that

((v1 ^ cookies[type][0]) * cookies[type][1] == (v2 ^ cookies[type][0]) * cookies[type][1]) &&
(v1 != v2)

for too round cookies[type][1]?

Thanks,

-- 
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments

  parent reply	other threads:[~2012-01-27 19:41 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-27 17:53 [RFC c/r 0/4] [RFC c/r 0/@total@] A pile in c/r sake Cyrill Gorcunov
2012-01-27 17:53 ` [RFC c/r 1/4] fs, proc: Introduce /proc/<pid>/task/<tid>/children entry v9 Cyrill Gorcunov
2012-01-27 17:53 ` [RFC c/r 2/4] [RFC] syscalls, x86: Add __NR_kcmp syscall v7 Cyrill Gorcunov
2012-01-27 18:05   ` H. Peter Anvin
2012-01-27 18:11     ` Cyrill Gorcunov
2012-01-27 18:15   ` Andi Kleen
2012-01-27 18:24     ` Cyrill Gorcunov
2012-01-27 18:30       ` H. Peter Anvin
2012-01-28 17:19         ` Michael Kerrisk
2012-01-28 17:34           ` Cyrill Gorcunov
2012-01-28 17:36             ` Cyrill Gorcunov
2012-01-27 18:31       ` Andi Kleen
2012-01-27 18:40         ` Cyrill Gorcunov
2012-01-27 19:40           ` Andi Kleen
2012-01-27 20:55             ` Eric W. Biederman
2012-01-27 18:40   ` Eric W. Biederman
2012-01-27 18:45     ` Cyrill Gorcunov
2012-01-27 19:10     ` Cyrill Gorcunov
2012-01-27 19:37   ` Vasiliy Kulikov [this message]
2012-01-27 19:59     ` hpanvin@gmail.com
2012-01-27 20:07       ` Cyrill Gorcunov
2012-01-27 20:19   ` KOSAKI Motohiro
2012-01-27 20:33     ` Eric W. Biederman
2012-01-27 20:50       ` Cyrill Gorcunov
2012-01-27 21:19         ` Eric W. Biederman
2012-01-27 20:34     ` Glauber Costa
2012-01-27 20:37       ` H. Peter Anvin
2012-01-27 20:47     ` Cyrill Gorcunov
2012-01-27 17:53 ` [RFC c/r 3/4] c/r: procfs: add arg_start/end, env_start/end and exit_code members to /proc/$pid/stat Cyrill Gorcunov
2012-01-27 18:29   ` Kees Cook
2012-01-27 20:00   ` KOSAKI Motohiro
2012-01-27 20:10     ` Cyrill Gorcunov
2012-01-27 17:53 ` [RFC c/r 4/4] c/r: prctl: Extend PR_SET_MM to set up more mm_struct entries Cyrill Gorcunov
2012-01-27 18:37   ` Kees Cook
2012-01-27 18:43     ` Cyrill Gorcunov
2012-01-27 20:31       ` KOSAKI Motohiro
2012-01-27 20:28     ` KOSAKI Motohiro

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