Hi Lu, On 3/8/22 6:44 AM, Lu Baolu wrote: > Hi folks, > > The iommu group is the minimal isolation boundary for DMA. Devices in > a group can access each other's MMIO registers via peer to peer DMA > and also need share the same I/O address space. > > Once the I/O address space is assigned to user control it is no longer > available to the dma_map* API, which effectively makes the DMA API > non-working. > > Second, userspace can use DMA initiated by a device that it controls > to access the MMIO spaces of other devices in the group. This allows > userspace to indirectly attack any kernel owned device and it's driver. > > Therefore groups must either be entirely under kernel control or > userspace control, never a mixture. Unfortunately some systems have > problems with the granularity of groups and there are a couple of > important exceptions: > > - pci_stub allows the admin to block driver binding on a device and > make it permanently shared with userspace. Since PCI stub does not > do DMA it is safe, however the admin must understand that using > pci_stub allows userspace to attack whatever device it was bound > it. > > - PCI bridges are sometimes included in groups. Typically PCI bridges > do not use DMA, and generally do not have MMIO regions. > > Generally any device that does not have any MMIO registers is a > possible candidate for an exception. > > Currently vfio adopts a workaround to detect violations of the above > restrictions by monitoring the driver core BOUND event, and hardwiring > the above exceptions. Since there is no way for vfio to reject driver > binding at this point, BUG_ON() is triggered if a violation is > captured (kernel driver BOUND event on a group which already has some > devices assigned to userspace). Aside from the bad user experience > this opens a way for root userspace to crash the kernel, even in high > integrity configurations, by manipulating the module binding and > triggering the BUG_ON. > > This series solves this problem by making the user/kernel ownership a > core concept at the IOMMU layer. The driver core enforces kernel > ownership while drivers are bound and violations now result in a error > codes during probe, not BUG_ON failures. > > Patch partitions: > [PATCH 1-4]: Detect DMA ownership conflicts during driver binding; > [PATCH 5-7]: Add security context management for assigned devices; > [PATCH 8-11]: Various cleanups. > > This is also part one of three initial series for IOMMUFD: > * Move IOMMU Group security into the iommu layer > - Generic IOMMUFD implementation > - VFIO ability to consume IOMMUFD > > Change log: > v1: initial post > - https://lore.kernel.org/linux-iommu/20211115020552.2378167-1-baolu.lu@xxxxxxxxxxxxxxx/ > > v2: > - https://lore.kernel.org/linux-iommu/20211128025051.355578-1-baolu.lu@xxxxxxxxxxxxxxx/ > > - Move kernel dma ownership auto-claiming from driver core to bus > callback. [Greg/Christoph/Robin/Jason] > https://lore.kernel.org/linux-iommu/20211115020552.2378167-1-baolu.lu@xxxxxxxxxxxxxxx/T/#m153706912b770682cb12e3c28f57e171aa1f9d0c > > - Code and interface refactoring for iommu_set/release_dma_owner() > interfaces. [Jason] > https://lore.kernel.org/linux-iommu/20211115020552.2378167-1-baolu.lu@xxxxxxxxxxxxxxx/T/#mea70ed8e4e3665aedf32a5a0a7db095bf680325e > > - [NEW]Add new iommu_attach/detach_device_shared() interfaces for > multiple devices group. [Robin/Jason] > https://lore.kernel.org/linux-iommu/20211115020552.2378167-1-baolu.lu@xxxxxxxxxxxxxxx/T/#mea70ed8e4e3665aedf32a5a0a7db095bf680325e > > - [NEW]Use iommu_attach/detach_device_shared() in drm/tegra drivers. > > - Refactoring and description refinement. > > v3: > - https://lore.kernel.org/linux-iommu/20211206015903.88687-1-baolu.lu@xxxxxxxxxxxxxxx/ > > - Rename bus_type::dma_unconfigure to bus_type::dma_cleanup. [Greg] > https://lore.kernel.org/linux-iommu/c3230ace-c878-39db-1663-2b752ff5384e@xxxxxxxxxxxxxxx/T/#m6711e041e47cb0cbe3964fad0a3466f5ae4b3b9b > > - Avoid _platform_dma_configure for platform_bus_type::dma_configure. > [Greg] > https://lore.kernel.org/linux-iommu/c3230ace-c878-39db-1663-2b752ff5384e@xxxxxxxxxxxxxxx/T/#m43fc46286611aa56a5c0eeaad99d539e5519f3f6 > > - Patch "0012-iommu-Add-iommu_at-de-tach_device_shared-for-mult.patch" > and "0018-drm-tegra-Use-the-iommu-dma_owner-mechanism.patch" have > been tested by Dmitry Osipenko <digetx@xxxxxxxxx>. > > v4: > - https://lore.kernel.org/linux-iommu/20211217063708.1740334-1-baolu.lu@xxxxxxxxxxxxxxx/ > - Remove unnecessary tegra->domain chech in the tegra patch. (Jason) > - Remove DMA_OWNER_NONE. (Joerg) > - Change refcount to unsigned int. (Christoph) > - Move mutex lock into group set_dma_owner functions. (Christoph) > - Add kernel doc for iommu_attach/detach_domain_shared(). (Christoph) > - Move dma auto-claim into driver core. (Jason/Christoph) > > v5: > - https://lore.kernel.org/linux-iommu/20220104015644.2294354-1-baolu.lu@xxxxxxxxxxxxxxx/ > - Move kernel dma ownership auto-claiming from driver core to bus > callback. (Greg) > - Refactor the iommu interfaces to make them more specific. > (Jason/Robin) > - Simplify the dma ownership implementation by removing the owner > type. (Jason) > - Commit message refactoring for PCI drivers. (Bjorn) > - Move iommu_attach/detach_device() improvement patches into another > series as there are a lot of code refactoring and cleanup staffs > in various device drivers. > > v6: > - https://lore.kernel.org/linux-iommu/20220218005521.172832-1-baolu.lu@xxxxxxxxxxxxxxx/ > - Refine comments and commit mesages. > - Rename iommu_group_set_dma_owner() to iommu_group_claim_dma_owner(). > - Rename iommu_device_use/unuse_kernel_dma() to > iommu_device_use/unuse_default_domain(). > - Remove unnecessary EXPORT_SYMBOL_GPL. > - Change flag name from no_kernel_api_dma to driver_managed_dma. > - Merge 4 "Add driver dma ownership management" patches into single > one. > > v7: > - We discussed about adding some fields in driver structure and > intercepting it in the bus notifier for driver unbinding. We agreed > that the driver structure should not be used out of the driver core. > - As iommu_group_claim/release_dma_owner() are only used by the VFIO, > there're no use cases for multiple calls for a single group. > - Add some commit messages in "vfio: Set DMA ownership for > VFIO" to describe the intentional enhancement of unsafe bridge > drivers. > - Comments refinement. > > v8: > - Move iommu_use_default_domain() to the end of .dma_configure > callback to avoid firmware-data-ordering thing. > Link: https://lore.kernel.org/linux-iommu/e2698dbe-18e2-1a82-8a12-fe45bc9be534@xxxxxxx/ Feel free to add my T-b Tested-by: Eric Auger <eric.auger@xxxxxxxxxx> Thanks Eric > - Add Acked-by from PCI and VFIO maintainers. > > This is based on next branch of linux-iommu tree: > https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git > and also available on github: > https://github.com/LuBaolu/intel-iommu/commits/iommu-dma-ownership-v8 > > Best regards, > baolu > > Jason Gunthorpe (1): > vfio: Delete the unbound_list > > Lu Baolu (10): > iommu: Add DMA ownership management interfaces > driver core: Add dma_cleanup callback in bus_type > amba: Stop sharing platform_dma_configure() > bus: platform,amba,fsl-mc,PCI: Add device DMA ownership management > PCI: pci_stub: Set driver_managed_dma > PCI: portdrv: Set driver_managed_dma > vfio: Set DMA ownership for VFIO devices > vfio: Remove use of vfio_group_viable() > vfio: Remove iommu group notifier > iommu: Remove iommu group changes notifier > > include/linux/amba/bus.h | 8 + > include/linux/device/bus.h | 3 + > include/linux/fsl/mc.h | 8 + > include/linux/iommu.h | 54 +++--- > include/linux/pci.h | 8 + > include/linux/platform_device.h | 10 +- > drivers/amba/bus.c | 37 +++- > drivers/base/dd.c | 5 + > drivers/base/platform.c | 21 ++- > drivers/bus/fsl-mc/fsl-mc-bus.c | 24 ++- > drivers/iommu/iommu.c | 228 ++++++++++++++++-------- > drivers/pci/pci-driver.c | 18 ++ > drivers/pci/pci-stub.c | 1 + > drivers/pci/pcie/portdrv_pci.c | 2 + > drivers/vfio/fsl-mc/vfio_fsl_mc.c | 1 + > drivers/vfio/pci/vfio_pci.c | 1 + > drivers/vfio/platform/vfio_amba.c | 1 + > drivers/vfio/platform/vfio_platform.c | 1 + > drivers/vfio/vfio.c | 245 ++------------------------ > 19 files changed, 338 insertions(+), 338 deletions(-) >
