linux-kernel - Re: [PATCH v6,04/24] v4l: add documentation for restricted memory flag

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <03aca2439ac31ec01b24233384cc8c8d5179df02.camel@collabora.com>
Date: Wed, 12 Jun 2024 16:58:58 -0400
From: Nicolas Dufresne <nicolas.dufresne@...labora.com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc: Tomasz Figa <tfiga@...omium.org>, Yunfei Dong
 <yunfei.dong@...iatek.com>,  Jeffrey Kardatzke <jkardatzke@...gle.com>,
 Nícolas "F . R . A . Prado" <nfraprado@...labora.com>, 
 Nathan Hebert <nhebert@...omium.org>, Hans Verkuil
 <hverkuil-cisco@...all.nl>, AngeloGioacchino Del Regno
 <angelogioacchino.delregno@...labora.com>, Benjamin Gaignard
 <benjamin.gaignard@...labora.com>, Sebastian Fricke
 <sebastian.fricke@...labora.com>, Mauro Carvalho Chehab
 <mchehab@...nel.org>,  Marek Szyprowski <m.szyprowski@...sung.com>, Chen-Yu
 Tsai <wenst@...omium.org>, Yong Wu <yong.wu@...iatek.com>,  Hsin-Yi Wang
 <hsinyi@...omium.org>, Fritz Koenig <frkoenig@...omium.org>, Daniel Vetter
 <daniel@...ll.ch>,  Steve Cho <stevecho@...omium.org>, Sumit Semwal
 <sumit.semwal@...aro.org>, Brian Starkey <Brian.Starkey@....com>, John
 Stultz <jstultz@...gle.com>, "T . J . Mercier" <tjmercier@...gle.com>,
 Christian König <christian.koenig@....com>, Matthias
 Brugger <matthias.bgg@...il.com>,  linux-media@...r.kernel.org,
 dri-devel@...ts.freedesktop.org,  linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org,  linux-mediatek@...ts.infradead.org, 
 Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v6,04/24] v4l: add documentation for restricted memory
 flag

Hi,

Le mercredi 12 juin 2024 à 23:25 +0300, Laurent Pinchart a écrit :
> On Wed, Jun 12, 2024 at 03:43:58PM -0400, Nicolas Dufresne wrote:
> > Le mercredi 12 juin 2024 à 13:37 +0900, Tomasz Figa a écrit :
> > > > Why is this flag needed ? Given that the usage model requires the V4L2
> > > > device to be a dma buf importer, why would userspace set the
> > > > V4L2_BUF_CAP_SUPPORTS_RESTRICTED_MEM flag and pass a non-restricted
> > > > buffer to the device ?
> > > 
> > > Given that the flag is specified at REQBUF / CREATE_BUFS time, it's
> > > actually useful to tell the driver the queue is operating in restricted
> > > (aka secure) mode.
> > > 
> > > I suppose we could handle that at the time of a first QBUF, but that
> > > would make the driver initialization and validation quite a bit of pain.
> > > So I'd say that the design being proposed here makes things simpler and
> > > more clear, even if it doesn't add any extra functionality.
> > 
> > There is few more reasons I notice in previous series (haven't read the latest):
> > 
> > - The driver needs to communicate through the OPTEE rather then SCP and some
> > communication are needed just to figure-out things like supported profile/level
> > resolutions etc.
> > - The driver needs to allocate auxiliary buffers in secure heap too, allocation
> > at runtime are not the best
> 
> Will the same driver support both modes on the same system ?

Yes, as per this implementation, it seems you can flip from one mode to another
even on the same instance.

Nicolas

> 
> > Note that the discussion around this flag already took place in the very first
> > iteration of the serie, it was originally using a CID and that was a proposed
> > replacement from Hans.
>