From cfb94a372f2d4ee226247447c863f8709863d170 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Fri, 6 Sep 2019 14:14:52 +0800 Subject: [PATCH] iommu/vt-d: Use bounce buffer for untrusted devices The Intel VT-d hardware uses paging for DMA remapping. The minimum mapped window is a page size. The device drivers may map buffers not filling the whole IOMMU window. This allows the device to access to possibly unrelated memory and a malicious device could exploit this to perform DMA attacks. To address this, the Intel IOMMU driver will use bounce pages for those buffers which don't fill whole IOMMU pages. Cc: Ashok Raj Cc: Jacob Pan Cc: Kevin Tian Signed-off-by: Lu Baolu Tested-by: Xu Pengfei Tested-by: Mika Westerberg Signed-off-by: Joerg Roedel --- drivers/iommu/intel-iommu.c | 258 ++++++++++++++++++++++++++++++++++++ 1 file changed, 258 insertions(+) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 12831beead02..b034fe727ead 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -41,9 +41,11 @@ #include #include #include +#include #include #include #include +#include #include "irq_remapping.h" #include "intel-pasid.h" @@ -344,6 +346,8 @@ static int domain_detach_iommu(struct dmar_domain *domain, static bool device_is_rmrr_locked(struct device *dev); static int intel_iommu_attach_device(struct iommu_domain *domain, struct device *dev); +static phys_addr_t intel_iommu_iova_to_phys(struct iommu_domain *domain, + dma_addr_t iova); #ifdef CONFIG_INTEL_IOMMU_DEFAULT_ON int dmar_disabled = 0; @@ -3754,6 +3758,252 @@ static const struct dma_map_ops intel_dma_ops = { .dma_supported = dma_direct_supported, }; +static void +bounce_sync_single(struct device *dev, dma_addr_t addr, size_t size, + enum dma_data_direction dir, enum dma_sync_target target) +{ + struct dmar_domain *domain; + phys_addr_t tlb_addr; + + domain = find_domain(dev); + if (WARN_ON(!domain)) + return; + + tlb_addr = intel_iommu_iova_to_phys(&domain->domain, addr); + if (is_swiotlb_buffer(tlb_addr)) + swiotlb_tbl_sync_single(dev, tlb_addr, size, dir, target); +} + +static dma_addr_t +bounce_map_single(struct device *dev, phys_addr_t paddr, size_t size, + enum dma_data_direction dir, unsigned long attrs, + u64 dma_mask) +{ + size_t aligned_size = ALIGN(size, VTD_PAGE_SIZE); + struct dmar_domain *domain; + struct intel_iommu *iommu; + unsigned long iova_pfn; + unsigned long nrpages; + phys_addr_t tlb_addr; + int prot = 0; + int ret; + + domain = find_domain(dev); + if (WARN_ON(dir == DMA_NONE || !domain)) + return DMA_MAPPING_ERROR; + + iommu = domain_get_iommu(domain); + if (WARN_ON(!iommu)) + return DMA_MAPPING_ERROR; + + nrpages = aligned_nrpages(0, size); + iova_pfn = intel_alloc_iova(dev, domain, + dma_to_mm_pfn(nrpages), dma_mask); + if (!iova_pfn) + return DMA_MAPPING_ERROR; + + /* + * Check if DMAR supports zero-length reads on write only + * mappings.. + */ + if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL || + !cap_zlr(iommu->cap)) + prot |= DMA_PTE_READ; + if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) + prot |= DMA_PTE_WRITE; + + /* + * If both the physical buffer start address and size are + * page aligned, we don't need to use a bounce page. + */ + if (!IS_ALIGNED(paddr | size, VTD_PAGE_SIZE)) { + tlb_addr = swiotlb_tbl_map_single(dev, + __phys_to_dma(dev, io_tlb_start), + paddr, size, aligned_size, dir, attrs); + if (tlb_addr == DMA_MAPPING_ERROR) { + goto swiotlb_error; + } else { + /* Cleanup the padding area. */ + void *padding_start = phys_to_virt(tlb_addr); + size_t padding_size = aligned_size; + + if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) && + (dir == DMA_TO_DEVICE || + dir == DMA_BIDIRECTIONAL)) { + padding_start += size; + padding_size -= size; + } + + memset(padding_start, 0, padding_size); + } + } else { + tlb_addr = paddr; + } + + ret = domain_pfn_mapping(domain, mm_to_dma_pfn(iova_pfn), + tlb_addr >> VTD_PAGE_SHIFT, nrpages, prot); + if (ret) + goto mapping_error; + + trace_bounce_map_single(dev, iova_pfn << PAGE_SHIFT, paddr, size); + + return (phys_addr_t)iova_pfn << PAGE_SHIFT; + +mapping_error: + if (is_swiotlb_buffer(tlb_addr)) + swiotlb_tbl_unmap_single(dev, tlb_addr, size, + aligned_size, dir, attrs); +swiotlb_error: + free_iova_fast(&domain->iovad, iova_pfn, dma_to_mm_pfn(nrpages)); + dev_err(dev, "Device bounce map: %zx@%llx dir %d --- failed\n", + size, (unsigned long long)paddr, dir); + + return DMA_MAPPING_ERROR; +} + +static void +bounce_unmap_single(struct device *dev, dma_addr_t dev_addr, size_t size, + enum dma_data_direction dir, unsigned long attrs) +{ + size_t aligned_size = ALIGN(size, VTD_PAGE_SIZE); + struct dmar_domain *domain; + phys_addr_t tlb_addr; + + domain = find_domain(dev); + if (WARN_ON(!domain)) + return; + + tlb_addr = intel_iommu_iova_to_phys(&domain->domain, dev_addr); + if (WARN_ON(!tlb_addr)) + return; + + intel_unmap(dev, dev_addr, size); + if (is_swiotlb_buffer(tlb_addr)) + swiotlb_tbl_unmap_single(dev, tlb_addr, size, + aligned_size, dir, attrs); + + trace_bounce_unmap_single(dev, dev_addr, size); +} + +static dma_addr_t +bounce_map_page(struct device *dev, struct page *page, unsigned long offset, + size_t size, enum dma_data_direction dir, unsigned long attrs) +{ + return bounce_map_single(dev, page_to_phys(page) + offset, + size, dir, attrs, *dev->dma_mask); +} + +static dma_addr_t +bounce_map_resource(struct device *dev, phys_addr_t phys_addr, size_t size, + enum dma_data_direction dir, unsigned long attrs) +{ + return bounce_map_single(dev, phys_addr, size, + dir, attrs, *dev->dma_mask); +} + +static void +bounce_unmap_page(struct device *dev, dma_addr_t dev_addr, size_t size, + enum dma_data_direction dir, unsigned long attrs) +{ + bounce_unmap_single(dev, dev_addr, size, dir, attrs); +} + +static void +bounce_unmap_resource(struct device *dev, dma_addr_t dev_addr, size_t size, + enum dma_data_direction dir, unsigned long attrs) +{ + bounce_unmap_single(dev, dev_addr, size, dir, attrs); +} + +static void +bounce_unmap_sg(struct device *dev, struct scatterlist *sglist, int nelems, + enum dma_data_direction dir, unsigned long attrs) +{ + struct scatterlist *sg; + int i; + + for_each_sg(sglist, sg, nelems, i) + bounce_unmap_page(dev, sg->dma_address, + sg_dma_len(sg), dir, attrs); +} + +static int +bounce_map_sg(struct device *dev, struct scatterlist *sglist, int nelems, + enum dma_data_direction dir, unsigned long attrs) +{ + int i; + struct scatterlist *sg; + + for_each_sg(sglist, sg, nelems, i) { + sg->dma_address = bounce_map_page(dev, sg_page(sg), + sg->offset, sg->length, + dir, attrs); + if (sg->dma_address == DMA_MAPPING_ERROR) + goto out_unmap; + sg_dma_len(sg) = sg->length; + } + + return nelems; + +out_unmap: + bounce_unmap_sg(dev, sglist, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC); + return 0; +} + +static void +bounce_sync_single_for_cpu(struct device *dev, dma_addr_t addr, + size_t size, enum dma_data_direction dir) +{ + bounce_sync_single(dev, addr, size, dir, SYNC_FOR_CPU); +} + +static void +bounce_sync_single_for_device(struct device *dev, dma_addr_t addr, + size_t size, enum dma_data_direction dir) +{ + bounce_sync_single(dev, addr, size, dir, SYNC_FOR_DEVICE); +} + +static void +bounce_sync_sg_for_cpu(struct device *dev, struct scatterlist *sglist, + int nelems, enum dma_data_direction dir) +{ + struct scatterlist *sg; + int i; + + for_each_sg(sglist, sg, nelems, i) + bounce_sync_single(dev, sg_dma_address(sg), + sg_dma_len(sg), dir, SYNC_FOR_CPU); +} + +static void +bounce_sync_sg_for_device(struct device *dev, struct scatterlist *sglist, + int nelems, enum dma_data_direction dir) +{ + struct scatterlist *sg; + int i; + + for_each_sg(sglist, sg, nelems, i) + bounce_sync_single(dev, sg_dma_address(sg), + sg_dma_len(sg), dir, SYNC_FOR_DEVICE); +} + +static const struct dma_map_ops bounce_dma_ops = { + .alloc = intel_alloc_coherent, + .free = intel_free_coherent, + .map_sg = bounce_map_sg, + .unmap_sg = bounce_unmap_sg, + .map_page = bounce_map_page, + .unmap_page = bounce_unmap_page, + .sync_single_for_cpu = bounce_sync_single_for_cpu, + .sync_single_for_device = bounce_sync_single_for_device, + .sync_sg_for_cpu = bounce_sync_sg_for_cpu, + .sync_sg_for_device = bounce_sync_sg_for_device, + .map_resource = bounce_map_resource, + .unmap_resource = bounce_unmap_resource, + .dma_supported = dma_direct_supported, +}; + static inline int iommu_domain_cache_init(void) { int ret = 0; @@ -5325,6 +5575,11 @@ static int intel_iommu_add_device(struct device *dev) } } + if (device_needs_bounce(dev)) { + dev_info(dev, "Use Intel IOMMU bounce page dma_ops\n"); + set_dma_ops(dev, &bounce_dma_ops); + } + return 0; } @@ -5342,6 +5597,9 @@ static void intel_iommu_remove_device(struct device *dev) iommu_group_remove_device(dev); iommu_device_unlink(&iommu->iommu, dev); + + if (device_needs_bounce(dev)) + set_dma_ops(dev, NULL); } static void intel_iommu_get_resv_regions(struct device *device, -- 2.30.2