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From: Steven Price <steven.price@arm.com>
To: Emil Velikov <emil.l.velikov@gmail.com>
Cc: David Airlie <airlied@linux.ie>,
	Robin Murphy <robin.murphy@arm.com>,
	ML dri-devel <dri-devel@lists.freedesktop.org>,
	Tomeu Vizoso <tomeu.vizoso@collabora.com>
Subject: Re: [PATCH 4/5] drm/panfrost: remove DRM_AUTH and respective comment
Date: Fri, 8 Nov 2019 15:55:24 +0000	[thread overview]
Message-ID: <8a392fc2-20e2-11cf-e06e-b66723a10b86@arm.com> (raw)
In-Reply-To: <CACvgo52zMar0q1CPNd0UnBFU3AZt-m1v7ZKaP0y3p6bSJ6LxFQ@mail.gmail.com>

On 08/11/2019 13:10, Emil Velikov wrote:
> On Fri, 1 Nov 2019 at 13:34, Steven Price <steven.price@arm.com> wrote:
>>
>> On 01/11/2019 13:03, Emil Velikov wrote:
>>> From: Emil Velikov <emil.velikov@collabora.com>
>>>
>>> As of earlier commit we have address space separation. Yet we forgot to
>>> remove the respective comment and DRM_AUTH in the ioctl declaration.
>>>
>>> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
>>> Cc: David Airlie <airlied@linux.ie>
>>> Cc: Daniel Vetter <daniel@ffwll.ch>
>>> Cc: Robin Murphy <robin.murphy@arm.com>
>>> Cc: Steven Price <steven.price@arm.com>
>>> Fixes: 7282f7645d06 ("drm/panfrost: Implement per FD address spaces")
>>> Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
>>
>> Reviewed-by: Steven Price <steven.price@arm.com>
>>
>> I'm not sure DRM_AUTH provided us with much in the first place (because
>> render nodes could snoop/affect the primary node), but since we have
>> address space separation it's clearly not required now.
>>
> Thanks Steve. This is exactly the reason why I removed it from most
> other drivers.
> There are equivalent vmwgfx changes and a DRM core patch in this series.
> 
> Do you think you'll have some time to check those over? Would be
> amazing if I can apply the lot in one go to drm-misc.

I'm afraid I don't know enough about the security model of vmwgfx to
meaningfully comment on those changes. On the surface they look fine,
but it really needs someone who understands whether this exposes an
attack surface.

The DRM core patch concerns me slightly (although again I'm not
completely up to speed on the security mode here). For a device which
doesn't have address space separation (and doesn't support render
nodes), is there anything stopping a process which hasn't authenticated
converting another process's handle to a prime fd? (or injecting dmabufs
into the address space used by the authenticated process - which might
cause address space exhaustion). If that's not a concern then I'm not
sure why the ioctls were originally added with DRM_AUTH...

Steve
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  reply	other threads:[~2019-11-08 15:55 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-01 13:03 [PATCH 1/5] drm/vmwgfx: move the require_exist handling together Emil Velikov
2019-11-01 13:03 ` [PATCH 2/5] drm/vmwgfx: check master authentication in surface_ref ioctls Emil Velikov
2019-11-12 12:53   ` Thomas Hellstrom
2019-11-01 13:03 ` [PATCH 3/5] drm/vmwgfx: drop DRM_AUTH for render ioctls Emil Velikov
2019-11-12 12:54   ` Thomas Hellstrom
2019-11-13 14:48     ` Emil Velikov
2019-11-01 13:03 ` [PATCH 4/5] drm/panfrost: remove DRM_AUTH and respective comment Emil Velikov
2019-11-01 13:34   ` Steven Price
2019-11-08 13:10     ` Emil Velikov
2019-11-08 15:55       ` Steven Price [this message]
2019-11-08 16:42         ` Emil Velikov
2019-11-01 13:03 ` [PATCH 5/5] drm: drop DRM_AUTH from PRIME_TO/FROM_HANDLE ioctls Emil Velikov
     [not found]   ` <20191101130313.8862-5-emil.l.velikov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2019-11-08 13:11     ` Emil Velikov
2019-11-08 13:11       ` Emil Velikov
2019-11-27  7:41   ` Boris Brezillon
2019-11-27 16:27     ` Emil Velikov
     [not found]       ` <CACvgo52UB-sAv55_kREgHbRsg6b5KXv7At0TbgUPdc0e1E+QaA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-11-27 18:04         ` Daniel Vetter
2019-11-27 18:04           ` Daniel Vetter
     [not found]           ` <20191127180456.GD406127-dv86pmgwkMBes7Z6vYuT8azUEOm+Xw19@public.gmane.org>
2019-11-27 18:32             ` Emil Velikov
2019-11-27 18:32               ` Emil Velikov
     [not found]               ` <CACvgo50j0sU18-AqeerkgDq9joJysT_0PuQrgVS1tVhUqV9rcg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2019-11-27 18:37                 ` Daniel Vetter
2019-11-27 18:37                   ` Daniel Vetter
     [not found]                   ` <20191127183700.GN406127-dv86pmgwkMBes7Z6vYuT8azUEOm+Xw19@public.gmane.org>
2019-12-02 17:20                     ` Emil Velikov
2019-12-02 17:20                       ` Emil Velikov
2019-11-27 16:25   ` [PATCH v2] " Emil Velikov
2019-11-08 13:13 ` [PATCH 1/5] drm/vmwgfx: move the require_exist handling together Emil Velikov
2019-11-08 15:22   ` Thomas Hellstrom
2019-11-12 12:50 ` Thomas Hellstrom

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