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From: Kees Cook <keescook@chromium.org>
To: Russell Currey <ruscur@russell.cc>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>,
	mpe@ellerman.id.au, linux-kernel@vger.kernel.org, dja@axtens.net,
	kernel-hardening@lists.openwall.com,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] lkdtm: Test KUAP directional user access unlocks on powerpc
Date: Sat, 1 Feb 2020 08:40:34 -0800	[thread overview]
Message-ID: <202002010836.76B19684@keescook> (raw)
In-Reply-To: <0b016861756cbe27e66651b5c21229a06558cb57.camel@russell.cc>

On Fri, Jan 31, 2020 at 05:53:14PM +1100, Russell Currey wrote:
> Correct, the ACCESS_USERSPACE test does the same thing.  Splitting this
> into separate R and W tests makes sense, even if it is unlikely that
> one would be broken without the other.

That would be my preference too -- the reason it wasn't separated before
was because it was one big toggle before. I just had both directions in
the test out of a desire for completeness.

Splitting into WRITE_USERSPACE and READ_USERSPACE seems good. Though if
you want to test functionality (read while only write disabled), then
I'm not sure what that should look like. Does the new
user_access_begin() API provide a way to query existing state? I'll go
read the series...

-- 
Kees Cook

      parent reply	other threads:[~2020-02-01 16:40 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-31  5:31 [PATCH] lkdtm: Test KUAP directional user access unlocks on powerpc Russell Currey
2020-01-31  6:44 ` Christophe Leroy
2020-01-31  6:53   ` Russell Currey
2020-01-31  6:58     ` Christophe Leroy
2020-01-31  7:01       ` Russell Currey
2020-02-01 16:40     ` Kees Cook [this message]

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