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

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Date:	Wed, 24 Apr 2013 18:01:11 -0400
From:	Josh Boyer <jwboyer@...hat.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Kees Cook <keescook@...omium.org>, 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 02:30:53PM -0700, Linus Torvalds wrote:
> 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.

I was just trying to get the 3 interfaces all honoring the same thing.

Let this be a lesson to you all: I am the harbinger of security
features removal.  If you see me sending patches, run away or I might
accidentally cross the streams and make your feature undergo total
protonic reversal.

Now if only I could use this power for good, like somehow getting Linus
to remove capabilities entirely...

josh
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