linux-kernel - Re: [PATCH] kmsg: Honor dmesg

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Message-ID: <20130227180547.GR26411@outflux.net>
Date:	Wed, 27 Feb 2013 10:05:47 -0800
From:	Kees Cook <kees@...flux.net>
To:	Josh Boyer <jwboyer@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	eparis@...hat.com, Christian Kujau <lists@...dbynature.de>,
	stable@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kmsg: Honor dmesg_restrict sysctl on /dev/kmsg

Hi,

On Fri, Feb 22, 2013 at 01:18:57PM -0500, Josh Boyer wrote:
> Originally, the addition of dmesg_restrict covered both the syslog
> method of accessing dmesg, as well as /dev/kmsg itself.  This was done
> indirectly by security_syslog calling cap_syslog before doing any LSM
> checks.

Actually, are the security_syslog() checks in /dev/kmsg correct? There is
only one used in devkmsg_open which uses SYSLOG_ACTION_READ_ALL. Shouldn't
it be using SYSLOG_ACTION_OPEN? And have SYSLOG_ACTION_READ_ALL added to
devkmsg_read? (And should we add one for write?)

-Kees

-- 
Kees Cook
Chrome OS Security
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