From: mitchelh@codeaurora•org (Mitchel Humpherys)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v3 0/6] Add support for privileged mappings
Date: Fri, 22 Jul 2016 13:39:45 -0700 [thread overview]
Message-ID: <vnkweg6l9zla.fsf@codeaurora.org> (raw)
In-Reply-To: <20160722165107.GH16837@arm.com> (Will Deacon's message of "Fri, 22 Jul 2016 17:51:07 +0100")
On Fri, Jul 22 2016 at 05:51:07 PM, Will Deacon <will.deacon@arm•com> wrote:
> On Tue, Jul 19, 2016 at 01:36:49PM -0700, Mitchel Humpherys wrote:
>> The following patch to the ARM SMMU driver:
>>
>> commit d346180e70b91b3d5a1ae7e5603e65593d4622bc
>> Author: Robin Murphy <robin.murphy@arm•com>
>> Date: Tue Jan 26 18:06:34 2016 +0000
>>
>> iommu/arm-smmu: Treat all device transactions as unprivileged
>>
>> started forcing all SMMU transactions to come through as "unprivileged".
>> The rationale given was that:
>>
>> (1) There is no way in the IOMMU API to even request privileged mappings.
>>
>> (2) It's difficult to implement a DMA mapper that correctly models the
>> ARM VMSAv8 behavior of unprivileged-writeable =>
>> privileged-execute-never.
>>
>> This series rectifies (1) by introducing an IOMMU API for privileged
>> mappings and implements it in io-pgtable-arm.
>>
>> This series rectifies (2) by introducing a new dma attribute
>> (DMA_ATTR_PRIVILEGED) for users of the DMA API that need privileged
>> mappings which are inaccessible to lesser-privileged execution levels, and
>> implements it in the arm64 IOMMU DMA mapper. The one known user (pl330.c)
>> is converted over to the new attribute.
>>
>> Jordan and Jeremy can provide more info on the use case if needed, but the
>> high level is that it's a security feature to prevent attacks such as [1].
>
> This all looks good to me:
>
> Acked-by: Will Deacon <will.deacon@arm•com>
>
> It looks pretty fiddly to merge, however. How are you planning to get
> this upstream?
Fiddly in what way? Do you mean in relation to "dma-mapping: Use
unsigned long for dma_attrs" [1]? I admit I wasn't aware of that
activity until Robin mentioned it. It looks like it's merged on
next/master, shall I rebase/rework on that and resend?
[1] https://lkml.org/lkml/2016/7/13/198
-Mitch
--
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
next prev parent reply other threads:[~2016-07-22 20:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-19 20:36 [PATCH v3 0/6] Add support for privileged mappings Mitchel Humpherys
2016-07-19 20:36 ` [PATCH v3 1/6] iommu: add IOMMU_PRIV attribute Mitchel Humpherys
2016-07-19 20:36 ` [PATCH v3 2/6] iommu/io-pgtable-arm: add support for the IOMMU_PRIV flag Mitchel Humpherys
2016-07-19 20:36 ` [PATCH v3 3/6] common: DMA-mapping: add DMA_ATTR_PRIVILEGED attribute Mitchel Humpherys
2016-07-19 20:36 ` [PATCH v3 4/6] arm64/dma-mapping: Implement DMA_ATTR_PRIVILEGED Mitchel Humpherys
2016-07-19 20:36 ` [PATCH v3 5/6] dmaengine: pl330: Make sure microcode is privileged Mitchel Humpherys
2016-07-19 20:36 ` [PATCH v3 6/6] Revert "iommu/arm-smmu: Treat all device transactions as unprivileged" Mitchel Humpherys
2016-07-22 16:51 ` [PATCH v3 0/6] Add support for privileged mappings Will Deacon
2016-07-22 20:39 ` Mitchel Humpherys [this message]
2016-07-25 9:50 ` Will Deacon
2016-07-25 19:01 ` Mitchel Humpherys
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