.../reserved-memory/reserved-memory.txt | 36 ++- 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, 362 insertions(+), 100 deletions(-)
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 v8: - Fix reserved-memory.txt and add the reg property in example. - Fix sizeof for of_property_count_elems_of_size in drivers/of/address.c#of_dma_set_restricted_buffer. - Apply Will's suggestion to try the OF node having DMA configuration in drivers/of/address.c#of_dma_set_restricted_buffer. - Fix typo in the comment of drivers/of/address.c#of_dma_set_restricted_buffer. - Add error message for PageHighMem in kernel/dma/swiotlb.c#rmem_swiotlb_device_init and move it to rmem_swiotlb_setup. - Fix the message string in rmem_swiotlb_setup. v7: Fix debugfs, PageHighMem and comment style in rmem_swiotlb_device_init https://lore.kernel.org/patchwork/cover/1431031/ v6: Address the comments in v5 https://lore.kernel.org/patchwork/cover/1423201/ 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/ 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 | 36 ++- 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, 362 insertions(+), 100 deletions(-) -- 2.31.1.818.g46aad6cb9e-goog
I just finished reviewing v7, sorry. Let me find some time to see what difference this version makes.
Hi Claire, On Thu, May 27, 2021 at 08:58:30PM +0800, Claire Chang wrote: > 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 > > v8: > - Fix reserved-memory.txt and add the reg property in example. > - Fix sizeof for of_property_count_elems_of_size in > drivers/of/address.c#of_dma_set_restricted_buffer. > - Apply Will's suggestion to try the OF node having DMA configuration in > drivers/of/address.c#of_dma_set_restricted_buffer. > - Fix typo in the comment of drivers/of/address.c#of_dma_set_restricted_buffer. > - Add error message for PageHighMem in > kernel/dma/swiotlb.c#rmem_swiotlb_device_init and move it to > rmem_swiotlb_setup. > - Fix the message string in rmem_swiotlb_setup. Thanks for the v8. It works for me out of the box on arm64 under KVM, so: Tested-by: Will Deacon <will@kernel.org> Note that something seems to have gone wrong with the mail threading, so the last 5 patches ended up as a separate thread for me. Probably worth posting again with all the patches in one place, if you can. Cheers, Will
On Sat, Jun 5, 2021 at 1:48 AM Will Deacon <will@kernel.org> wrote: > > Hi Claire, > > On Thu, May 27, 2021 at 08:58:30PM +0800, Claire Chang wrote: > > 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 > > > > v8: > > - Fix reserved-memory.txt and add the reg property in example. > > - Fix sizeof for of_property_count_elems_of_size in > > drivers/of/address.c#of_dma_set_restricted_buffer. > > - Apply Will's suggestion to try the OF node having DMA configuration in > > drivers/of/address.c#of_dma_set_restricted_buffer. > > - Fix typo in the comment of drivers/of/address.c#of_dma_set_restricted_buffer. > > - Add error message for PageHighMem in > > kernel/dma/swiotlb.c#rmem_swiotlb_device_init and move it to > > rmem_swiotlb_setup. > > - Fix the message string in rmem_swiotlb_setup. > > Thanks for the v8. It works for me out of the box on arm64 under KVM, so: > > Tested-by: Will Deacon <will@kernel.org> > > Note that something seems to have gone wrong with the mail threading, so > the last 5 patches ended up as a separate thread for me. Probably worth > posting again with all the patches in one place, if you can. Thanks for testing. Christoph also added some comments in v7, so I'll prepare v9. > > Cheers, > > Will
v9 here: https://lore.kernel.org/patchwork/cover/1445081/ On Mon, Jun 7, 2021 at 11:28 AM Claire Chang <tientzu@chromium.org> wrote: > > On Sat, Jun 5, 2021 at 1:48 AM Will Deacon <will@kernel.org> wrote: > > > > Hi Claire, > > > > On Thu, May 27, 2021 at 08:58:30PM +0800, Claire Chang wrote: > > > 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 > > > > > > v8: > > > - Fix reserved-memory.txt and add the reg property in example. > > > - Fix sizeof for of_property_count_elems_of_size in > > > drivers/of/address.c#of_dma_set_restricted_buffer. > > > - Apply Will's suggestion to try the OF node having DMA configuration in > > > drivers/of/address.c#of_dma_set_restricted_buffer. > > > - Fix typo in the comment of drivers/of/address.c#of_dma_set_restricted_buffer. > > > - Add error message for PageHighMem in > > > kernel/dma/swiotlb.c#rmem_swiotlb_device_init and move it to > > > rmem_swiotlb_setup. > > > - Fix the message string in rmem_swiotlb_setup. > > > > Thanks for the v8. It works for me out of the box on arm64 under KVM, so: > > > > Tested-by: Will Deacon <will@kernel.org> > > > > Note that something seems to have gone wrong with the mail threading, so > > the last 5 patches ended up as a separate thread for me. Probably worth > > posting again with all the patches in one place, if you can. > > Thanks for testing. > > Christoph also added some comments in v7, so I'll prepare v9. > > > > > Cheers, > > > > Will
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