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

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Message-ID: <20101109120649.62b487e8@lxorguk.ukuu.org.uk>
Date:	Tue, 9 Nov 2010 12:06:49 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Dan Rosenberg <drosenberg@...curity.com>
Cc:	linux-kernel@...r.kernel.org, security@...nel.org,
	stable@...nel.org
Subject: Re: [PATCH] Restrict unprivileged access to kernel syslog

On Mon, 08 Nov 2010 22:28:58 -0500
Dan Rosenberg <drosenberg@...curity.com> 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.

Except for anything that appears on the screen - which is remotely
readable via the screen access APIs. Looks sane to me (pointless but
sane) and the checks match the ones needed to redirect the console so you
need CAP_SYS_ADMIN either way.
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