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[209.85.222.174]) by smtp.gmail.com with ESMTPSA id 25sm2259586qtd.51.2021.05.17.23.54.48 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 May 2021 23:54:48 -0700 (PDT) Received: by mail-qk1-f174.google.com with SMTP id 76so8289554qkn.13 for ; Mon, 17 May 2021 23:54:48 -0700 (PDT) X-Received: by 2002:a05:6638:10e4:: with SMTP id g4mr3960623jae.90.1621320877050; Mon, 17 May 2021 23:54:37 -0700 (PDT) MIME-Version: 1.0 References: <20210510095026.3477496-1-tientzu@chromium.org> In-Reply-To: <20210510095026.3477496-1-tientzu@chromium.org> From: Claire Chang Date: Tue, 18 May 2021 14:54:26 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v6 00/15] Restricted DMA To: Rob Herring , mpe@ellerman.id.au, Joerg Roedel , Will Deacon , Frank Rowand , Konrad Rzeszutek Wilk , boris.ostrovsky@oracle.com, jgross@suse.com, Christoph Hellwig , Marek Szyprowski Cc: benh@kernel.crashing.org, paulus@samba.org, "list@263.net:IOMMU DRIVERS" , sstabellini@kernel.org, Robin Murphy , grant.likely@arm.com, xypron.glpk@gmx.de, Thierry Reding , mingo@kernel.org, bauerman@linux.ibm.com, peterz@infradead.org, Greg KH , Saravana Kannan , "Rafael J . Wysocki" , heikki.krogerus@linux.intel.com, Andy Shevchenko , Randy Dunlap , Dan Williams , Bartosz Golaszewski , linux-devicetree , lkml , linuxppc-dev@lists.ozlabs.org, xen-devel@lists.xenproject.org, Nicolas Boichat , Jim Quinlan , Tomasz Figa , bskeggs@redhat.com, Bjorn Helgaas , chris@chris-wilson.co.uk, Daniel Vetter , airlied@linux.ie, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, jani.nikula@linux.intel.com, Jianxiong Gao , joonas.lahtinen@linux.intel.com, linux-pci@vger.kernel.org, maarten.lankhorst@linux.intel.com, matthew.auld@intel.com, nouveau@lists.freedesktop.org, rodrigo.vivi@intel.com, thomas.hellstrom@linux.intel.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org v7: https://lore.kernel.org/patchwork/cover/1431031/ On Mon, May 10, 2021 at 5:50 PM Claire Chang wrote: > > From: Claire Chang > > 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 >