linux-kernel - Re: [PATCH v2] kmsg: Honor dmesg

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Date:	Wed, 24 Apr 2013 14:30:53 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Kees Cook <keescook@...omium.org>
Cc:	Josh Boyer <jwboyer@...hat.com>, Kay Sievers <kay@...y.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Eric Paris <eparis@...hat.com>,
	Christian Kujau <lists@...dbynature.de>,
	"# 3.4.x" <stable@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>, Karel Zak <kzak@...hat.com>
Subject: Re: [PATCH v2] kmsg: Honor dmesg_restrict sysctl on /dev/kmsg

On Wed, Apr 24, 2013 at 1:35 PM, Kees Cook <keescook@...omium.org> wrote:
>
> That said, I much prefer doing the privilege test at read time since
> that means passing a file descriptor to another process doesn't mean
> the new process can just continue reading.

Bullshit.

That's exactly the wrong kind of thinking. If you had privileges to
open something, and you pass it off, it's *your* choice.

In contrast, the "anybody can open, but some people can read/write"
has several times resulted in real security issues. Notably the whole
"open something, then fool a suid program to write its error message
to it".

This whole discussion has been f*cking moronic. The "security"
arguments have been utter shite with clearly no thinking behind it,
the feature is total crap (people need dmesg to do basic bug
reporting), and I'm seriously considering just getting rid of this
idiotic dmesg_restrict thing entirely. Your comment is the very
epitome of bad security thinking.

                Linus
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