Subject: Re: [PATCH v4] kptr_restrict for hiding kernel pointers
From: Dan Rosenberg <drosenberg@vsecurity.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        linux-security-module@vger.kernel.org, jmorris@namei.org,
        eric.dumazet@gmail.com, tgraf@infradead.org, eugeneteo@kernel.org,
        kees.cook@canonical.com, davem@davemloft.net, a.p.zijlstra@chello.nl,
        akpm@linux-foundation.org, eparis@parisplace.org,
        Linus Torvalds <torvalds@linux-foundation.org>
In-Reply-To: <20101222130349.GB13412@elte.hu>
References: <1292708499.10804.89.camel@dan> <20101222130349.GB13412@elte.hu>
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Date: Wed, 22 Dec 2010 08:13:09 -0500
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> 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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