From: Will Deacon <will.deacon@arm.com>
To: Marc Gonzalez <marc.w.gonzalez@free.fr>
Cc: Douglas Anderson <dianders@chromium.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2] iommu/arm-smmu: Break insecure users by disabling bypass by default
Date: Wed, 24 Apr 2019 12:52:31 +0100 [thread overview]
Message-ID: <20190424115231.GA14829@fuggles.cambridge.arm.com> (raw)
In-Reply-To: <4754bcf1-6423-f1fe-64d4-da4a35b164ad@free.fr>
On Wed, Apr 24, 2019 at 01:36:58PM +0200, Marc Gonzalez wrote:
> On 04/04/2019 17:00, Will Deacon wrote:
>
> > On Fri, Mar 01, 2019 at 11:20:17AM -0800, Douglas Anderson wrote:
> >
> >> If you're bisecting why your peripherals stopped working, it's
> >> probably this CL. Specifically if you see this in your dmesg:
> >> Unexpected global fault, this could be serious
> >> ...then it's almost certainly this CL.
> >>
> >> Running your IOMMU-enabled peripherals with the IOMMU in bypass mode
> >> is insecure and effectively disables the protection they provide.
> >> There are few reasons to allow unmatched stream bypass, and even fewer
> >> good ones.
> >>
> >> This patch starts the transition over to make it much harder to run
> >> your system insecurely. Expected steps:
> >>
> >> 1. By default disable bypass (so anyone insecure will notice) but make
> >> it easy for someone to re-enable bypass with just a KConfig change.
> >> That's this patch.
> >>
> >> 2. After people have had a little time to come to grips with the fact
> >> that they need to set their IOMMUs properly and have had time to
> >> dig into how to do this, the KConfig will be eliminated and bypass
> >> will simply be disabled. Folks who are truly upset and still
> >> haven't fixed their system can either figure out how to add
> >> 'arm-smmu.disable_bypass=n' to their command line or revert the
> >> patch in their own private kernel. Of course these folks will be
> >> less secure.
> >>
> >> Suggested-by: Robin Murphy <robin.murphy@arm.com>
> >> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> >> ---
> >>
> >> Changes in v2:
> >> - Flipped default to 'yes' and changed comments a lot.
> >>
> >> drivers/iommu/Kconfig | 25 +++++++++++++++++++++++++
> >> drivers/iommu/arm-smmu.c | 3 ++-
> >> 2 files changed, 27 insertions(+), 1 deletion(-)
> >
> > Cheers, I'll pick this one up for 5.2.
>
> Hello Will,
>
> You haven't pushed this patch out to linux-next AFAICT.
>
> Is that expected?
It's on my branch for Joerg:
https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=for-joerg/arm-smmu/updates
which I'll send to him today. My SMMU stuff doesn't go directly into -next.
Will
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next prev parent reply other threads:[~2019-04-24 11:52 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-01 19:20 [PATCH v2] iommu/arm-smmu: Break insecure users by disabling bypass by default Douglas Anderson
2019-03-01 19:20 ` Douglas Anderson
2019-03-20 15:48 ` Marc Gonzalez
2019-03-20 15:48 ` Marc Gonzalez
2019-03-20 18:35 ` Robin Murphy
2019-03-20 18:35 ` Robin Murphy
2019-04-02 15:42 ` Marc Gonzalez
2019-04-02 15:42 ` Marc Gonzalez
2019-04-04 15:00 ` Will Deacon
2019-04-04 15:00 ` Will Deacon
2019-04-24 11:36 ` Marc Gonzalez
2019-04-24 11:52 ` Will Deacon [this message]
2019-05-02 10:59 ` Thierry Reding
2019-05-02 11:08 ` Will Deacon
2019-05-02 11:08 ` Will Deacon
2019-05-02 12:45 ` Thierry Reding
2019-05-02 14:08 ` Will Deacon
2019-05-02 14:08 ` Will Deacon
2019-05-02 14:27 ` Robin Murphy
2019-05-02 14:27 ` Robin Murphy
2019-08-19 11:28 ` Thierry Reding
2019-08-19 12:09 ` Will Deacon
2019-08-19 12:09 ` Will Deacon
2019-08-19 13:33 ` Thierry Reding
2019-08-19 14:48 ` Will Deacon
2019-08-19 14:48 ` Will Deacon
2019-08-20 13:55 ` Marc Gonzalez
2019-08-20 14:10 ` Robin Murphy
2019-10-03 18:27 ` Tim Harvey
2019-10-03 18:27 ` Tim Harvey
2019-10-03 18:27 ` Tim Harvey
2019-10-03 20:42 ` Robin Murphy
2019-10-03 20:42 ` Robin Murphy
2019-10-03 20:42 ` Robin Murphy
2019-10-03 20:51 ` Tim Harvey
2019-10-03 20:51 ` Tim Harvey
2019-10-03 20:51 ` Tim Harvey
2019-10-03 22:24 ` Robin Murphy
2019-10-03 22:24 ` Robin Murphy
2019-10-03 22:24 ` Robin Murphy
2019-10-04 15:23 ` Tim Harvey
2019-10-04 15:23 ` Tim Harvey
2019-10-04 15:23 ` Tim Harvey
2019-10-04 16:36 ` Robin Murphy
2019-10-04 16:36 ` Robin Murphy
2019-10-04 16:36 ` Robin Murphy
2019-10-04 17:13 ` Tim Harvey
2019-10-04 17:13 ` Tim Harvey
2019-10-04 17:13 ` Tim Harvey
2019-10-04 18:34 ` Robin Murphy
2019-10-04 18:34 ` Robin Murphy
2019-10-04 18:34 ` Robin Murphy
2019-10-04 20:37 ` Tim Harvey
2019-10-04 20:37 ` Tim Harvey
2019-10-04 20:37 ` Tim Harvey
2019-10-04 23:27 ` Robin Murphy
2019-10-04 23:27 ` Robin Murphy
2019-10-04 23:27 ` Robin Murphy
2019-10-24 16:56 ` Tim Harvey
2019-10-24 16:56 ` Tim Harvey
2019-10-24 16:56 ` Tim Harvey
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