linux-kernel - Re: [Security] [PATCH] Restrict unprivileged access to kernel syslog

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Date:	Tue, 9 Nov 2010 13:39:18 +0800
From:	Eugene Teo <eugeneteo@...nel.sg>
To:	Kees Cook <kees.cook@...onical.com>
Cc:	Dan Rosenberg <drosenberg@...curity.com>, security@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [Security] [PATCH] Restrict unprivileged access to kernel syslog

On Tue, Nov 9, 2010 at 1:34 PM, Kees Cook <kees.cook@...onical.com> wrote:
> On Mon, Nov 08, 2010 at 10:28:58PM -0500, Dan Rosenberg wrote:
>> The kernel syslog contains debugging information that is often useful
>> during exploitation of other vulnerabilities, such as kernel heap
>> addresses.  Rather than futilely attempt to sanitize hundreds (or
>> thousands) of printk statements and simultaneously cripple useful
>> debugging functionality, it is far simpler to create an option that
>> prevents unprivileged users from reading the syslog.
>>
>> This patch, loosely based on grsecurity's GRKERNSEC_DMESG, creates the
>> dmesg_restrict sysctl.  When set to "0", the default, no restrictions
>> are enforced.  When set to "1", only users with CAP_SYS_ADMIN can read
>> the kernel syslog via dmesg(8) or other mechanisms.
>>
>> Signed-off-by: Dan Rosenberg <drosenberg@...curity.com>
>
> Acked-by: Kees Cook <kees.cook@...onical.com>
>
> This looks good to me -- it leaves the /proc file access alone for
> priv-dropping ksyslogd implementations.

Acked-by: Eugene Teo <eugeneteo@...nel.org>

Looks good to me too. Thanks.

Eugene
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