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Subject[PATCH v13 00/12] Restricted DMA
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]).


- Fix xen-swiotlb issues
- memset in patch 01/12
- is_swiotlb_force_bounce in patch 06/12
- Fix the dts example typo in reserved-memory.txt
- Add Stefano and Will's Tested-by tag from v12

Split is_dev_swiotlb_force into is_swiotlb_force_bounce (patch 06/12) and
is_swiotlb_for_alloc (patch 09/12)

- Rebase against swiotlb devel/for-linus-5.14
- s/mempry/memory/g
- exchange the order of patch 09/12 and 10/12

Address the comments in v9 to
- fix the dev->dma_io_tlb_mem assignment
- propagate swiotlb_force setting into io_tlb_default_mem->force
- move set_memory_decrypted out of swiotlb_init_io_tlb_mem
- move debugfs_dir declaration into the main CONFIG_DEBUG_FS block
- add swiotlb_ prefix to find_slots and release_slots
- merge the 3 alloc/free related patches

Address the comments in v7 to
- set swiotlb active pool to dev->dma_io_tlb_mem
- get rid of get_io_tlb_mem
- dig out the device struct for is_swiotlb_active
- move debugfs_create_dir out of swiotlb_create_debugfs
- do set_memory_decrypted conditionally in swiotlb_init_io_tlb_mem
- use IS_ENABLED in kernel/dma/direct.c
- fix redefinition of 'of_dma_set_restricted_buffer'

- Fix reserved-memory.txt and add the reg property in example.
- Fix sizeof for of_property_count_elems_of_size in
- Apply Will's suggestion to try the OF node having DMA configuration in
- 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
- Fix the message string in rmem_swiotlb_setup.

Fix debugfs, PageHighMem and comment style in rmem_swiotlb_device_init

Address the comments in v5

Rebase on latest linux-next

- Fix spinlock bad magic
- Use rmem->name for debugfs entry
- Address the comments in v3

Using only one reserved memory region for both streaming DMA and memory

Building on top of swiotlb.

Using dma_map_ops.

Claire Chang (12):
swiotlb: Refactor swiotlb init functions
swiotlb: Refactor swiotlb_create_debugfs
swiotlb: Set dev->dma_io_tlb_mem to the swiotlb pool used
swiotlb: Update is_swiotlb_buffer to add a struct device argument
swiotlb: Update is_swiotlb_active to add a struct device argument
swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing
swiotlb: Move alloc_size to swiotlb_find_slots
swiotlb: Refactor swiotlb_tbl_unmap_single
swiotlb: Add restricted DMA alloc/free support
swiotlb: Add restricted DMA pool initialization
dt-bindings: of: Add restricted DMA pool
of: Add plumbing for restricted DMA pool

.../reserved-memory/reserved-memory.txt | 36 ++-
drivers/base/core.c | 4 +
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 | 33 +++
drivers/of/device.c | 3 +
drivers/of/of_private.h | 6 +
drivers/pci/xen-pcifront.c | 2 +-
drivers/xen/swiotlb-xen.c | 4 +-
include/linux/device.h | 4 +
include/linux/swiotlb.h | 51 +++-
kernel/dma/Kconfig | 14 +
kernel/dma/direct.c | 59 +++--
kernel/dma/direct.h | 8 +-
kernel/dma/swiotlb.c | 250 +++++++++++++-----
16 files changed, 387 insertions(+), 103 deletions(-)


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