linux-kernel - Re: [PATCH v4] kptr_restrict for hiding kernel pointers

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Message-ID: <1293023589.9820.186.camel@dan>
Date:	Wed, 22 Dec 2010 08:13:09 -0500
From:	Dan Rosenberg <drosenberg@...curity.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	linux-security-module@...r.kernel.org, jmorris@...ei.org,
	eric.dumazet@...il.com, tgraf@...radead.org, eugeneteo@...nel.org,
	kees.cook@...onical.com, davem@...emloft.net,
	a.p.zijlstra@...llo.nl, akpm@...ux-foundation.org,
	eparis@...isplace.org,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v4] kptr_restrict for hiding kernel pointers

> Hm, why is it off by default? Is there some user-space regression that is caused by 
> this?
> 
> We really want good security measures to be active by default (and to work by 
> default) - they are not worth much if they are not.
> 

I agree entirely, but I've received a lot of resistance to these types
of changes in net.  I'm afraid that if it's enabled by default, no one
will actually allow use of the %pK specifier where it should be used.

As far as I know, there's no actual breakage of anything in userspace,
but there's a general "it might make it harder to debug things in
certain limited circumstances" sentiment among some.  I never understood
why it is necessary for unprivileged users to be able to debug the
kernel.

Does anyone else have thoughts on this?

> Thanks,
> 
> 	Ingo

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