iommu: Don't use lazy flush for untrusted device
Subsystems (2)
PATCH 1/1 iommu: Don't use lazy flush for untrusted device
The lazy IOTLB flushing setup leaves a time window, in which the device can still access some system memory, which has already been unmapped by the device driver. It's not suitable for untrusted devices. A malicious device might use this to attack the system by obtaining data that it shouldn't obtain.
--- drivers/iommu/dma-iommu.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)
drivers/iommu/dma-iommu.c +8 -7
@@ -311,6 +311,11 @@ static void iommu_dma_flush_iotlb_all(struct iova_domain *iovad) domain->ops->flush_iotlb_all (domain); } +static bool dev_is_untrusted (struct device *dev) +{ +return dev_is_pci (dev) &&to_pci_dev (dev)->untrusted; +} +/** * iommu_dma_init_domain - Initialise a DMA mapping domain * @domain: IOMMU domain previously prepared by iommu_get_dma_cookie()
@@ -365,8 +370,9 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,init_iova_domain (iovad,1UL << order, base_pfn); -if (!cookie->fq_domain && !iommu_domain_get_attr (domain, -DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE , &attr) && attr) { +if (!cookie->fq_domain && (!dev || !dev_is_untrusted (dev)) && + !iommu_domain_get_attr (domain,DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE , &attr) && + attr) {if (init_iova_flush_queue (iovad, iommu_dma_flush_iotlb_all, iommu_dma_entry_dtor))pr_warn ("iova flush queue initialization failed\n" );
@@ -508,11 +514,6 @@ static void __iommu_dma_unmap_swiotlb(struct device *dev, dma_addr_t dma_addr, iova_align(iovad, size), dir, attrs); } -static bool dev_is_untrusted (struct device *dev) -{ -return dev_is_pci (dev) &&to_pci_dev (dev)->untrusted; -} -static dma_addr_t __iommu_dma_map (struct device *dev,phys_addr_t phys,size_t size,int prot,u64 dma_mask) {
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2.25.1 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
Quoted 11 lines · Lu Baolu
The lazy IOTLB flushing setup leaves a time window, in which the device can still access some system memory, which has already been unmapped by the device driver. It's not suitable for untrusted devices. A malicious device might use this to attack the system by obtaining data that it shouldn't obtain.
Fixes c588072bba6b5 ("iommu/vt-d: Convert intel iommu driver to the iommu ops")Signed-off-by Lu Baolu <[email protected]>--- drivers/iommu/dma-iommu.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)
Will
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