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Date: Tue, 18 May 2021 14:54:26 +0800
From: Claire Chang <tientzu@...omium.org>
To: Rob Herring <robh+dt@...nel.org>, mpe@...erman.id.au,
Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
Frank Rowand <frowand.list@...il.com>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
boris.ostrovsky@...cle.com, jgross@...e.com,
Christoph Hellwig <hch@....de>,
Marek Szyprowski <m.szyprowski@...sung.com>
Cc: benh@...nel.crashing.org, paulus@...ba.org,
"list@....net:IOMMU DRIVERS" <iommu@...ts.linux-foundation.org>,
sstabellini@...nel.org, Robin Murphy <robin.murphy@....com>,
grant.likely@....com, xypron.glpk@....de,
Thierry Reding <treding@...dia.com>, mingo@...nel.org,
bauerman@...ux.ibm.com, peterz@...radead.org,
Greg KH <gregkh@...uxfoundation.org>,
Saravana Kannan <saravanak@...gle.com>,
"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
heikki.krogerus@...ux.intel.com,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Randy Dunlap <rdunlap@...radead.org>,
Dan Williams <dan.j.williams@...el.com>,
Bartosz Golaszewski <bgolaszewski@...libre.com>,
linux-devicetree <devicetree@...r.kernel.org>,
lkml <linux-kernel@...r.kernel.org>,
linuxppc-dev@...ts.ozlabs.org, xen-devel@...ts.xenproject.org,
Nicolas Boichat <drinkcat@...omium.org>,
Jim Quinlan <james.quinlan@...adcom.com>,
Tomasz Figa <tfiga@...omium.org>, bskeggs@...hat.com,
Bjorn Helgaas <bhelgaas@...gle.com>, chris@...is-wilson.co.uk,
Daniel Vetter <daniel@...ll.ch>, airlied@...ux.ie,
dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
jani.nikula@...ux.intel.com, Jianxiong Gao <jxgao@...gle.com>,
joonas.lahtinen@...ux.intel.com, linux-pci@...r.kernel.org,
maarten.lankhorst@...ux.intel.com, matthew.auld@...el.com,
nouveau@...ts.freedesktop.org, rodrigo.vivi@...el.com,
thomas.hellstrom@...ux.intel.com
Subject: Re: [PATCH v6 00/15] Restricted DMA
v7: https://lore.kernel.org/patchwork/cover/1431031/
On Mon, May 10, 2021 at 5:50 PM Claire Chang <tientzu@...omium.org> wrote:
>
> From: Claire Chang <tientzu@...gle.com>
>
> This series implements mitigations for lack of DMA access control on
> systems without an IOMMU, which could result in the DMA accessing the
> system memory at unexpected times and/or unexpected addresses, possibly
> leading to data leakage or corruption.
>
> For example, we plan to use the PCI-e bus for Wi-Fi and that PCI-e bus is
> not behind an IOMMU. As PCI-e, by design, gives the device full access to
> system memory, a vulnerability in the Wi-Fi firmware could easily escalate
> to a full system exploit (remote wifi exploits: [1a], [1b] that shows a
> full chain of exploits; [2], [3]).
>
> To mitigate the security concerns, we introduce restricted DMA. Restricted
> DMA utilizes the existing swiotlb to bounce streaming DMA in and out of a
> specially allocated region and does memory allocation from the same region.
> The feature on its own provides a basic level of protection against the DMA
> overwriting buffer contents at unexpected times. However, to protect
> against general data leakage and system memory corruption, the system needs
> to provide a way to restrict the DMA to a predefined memory region (this is
> usually done at firmware level, e.g. MPU in ATF on some ARM platforms [4]).
>
> [1a] https://googleprojectzero.blogspot.com/2017/04/over-air-exploiting-broadcoms-wi-fi_4.html
> [1b] https://googleprojectzero.blogspot.com/2017/04/over-air-exploiting-broadcoms-wi-fi_11.html
> [2] https://blade.tencent.com/en/advisories/qualpwn/
> [3] https://www.bleepingcomputer.com/news/security/vulnerabilities-found-in-highly-popular-firmware-for-wifi-chips/
> [4] https://github.com/ARM-software/arm-trusted-firmware/blob/master/plat/mediatek/mt8183/drivers/emi_mpu/emi_mpu.c#L132
>
> v6:
> Address the comments in v5
>
> v5:
> Rebase on latest linux-next
> https://lore.kernel.org/patchwork/cover/1416899/
>
> v4:
> - Fix spinlock bad magic
> - Use rmem->name for debugfs entry
> - Address the comments in v3
> https://lore.kernel.org/patchwork/cover/1378113/
>
> v3:
> Using only one reserved memory region for both streaming DMA and memory
> allocation.
> https://lore.kernel.org/patchwork/cover/1360992/
>
> v2:
> Building on top of swiotlb.
> https://lore.kernel.org/patchwork/cover/1280705/
>
> v1:
> Using dma_map_ops.
> https://lore.kernel.org/patchwork/cover/1271660/
> *** BLURB HERE ***
>
> Claire Chang (15):
> swiotlb: Refactor swiotlb init functions
> swiotlb: Refactor swiotlb_create_debugfs
> swiotlb: Add DMA_RESTRICTED_POOL
> swiotlb: Add restricted DMA pool initialization
> swiotlb: Add a new get_io_tlb_mem getter
> swiotlb: Update is_swiotlb_buffer to add a struct device argument
> swiotlb: Update is_swiotlb_active to add a struct device argument
> swiotlb: Bounce data from/to restricted DMA pool if available
> swiotlb: Move alloc_size to find_slots
> swiotlb: Refactor swiotlb_tbl_unmap_single
> dma-direct: Add a new wrapper __dma_direct_free_pages()
> swiotlb: Add restricted DMA alloc/free support.
> dma-direct: Allocate memory from restricted DMA pool if available
> dt-bindings: of: Add restricted DMA pool
> of: Add plumbing for restricted DMA pool
>
> .../reserved-memory/reserved-memory.txt | 27 ++
> drivers/gpu/drm/i915/gem/i915_gem_internal.c | 2 +-
> drivers/gpu/drm/nouveau/nouveau_ttm.c | 2 +-
> drivers/iommu/dma-iommu.c | 12 +-
> drivers/of/address.c | 25 ++
> drivers/of/device.c | 3 +
> drivers/of/of_private.h | 5 +
> drivers/pci/xen-pcifront.c | 2 +-
> drivers/xen/swiotlb-xen.c | 2 +-
> include/linux/device.h | 4 +
> include/linux/swiotlb.h | 41 ++-
> kernel/dma/Kconfig | 14 +
> kernel/dma/direct.c | 63 +++--
> kernel/dma/direct.h | 9 +-
> kernel/dma/swiotlb.c | 242 +++++++++++++-----
> 15 files changed, 356 insertions(+), 97 deletions(-)
>
> --
> 2.31.1.607.g51e8a6a459-goog
>
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