| Message ID | 20250221000943.973221-2-jperaza@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | PCI/ACPI: Support Microsoft's "DmaProperty" | expand |
On Fri, Feb 21, 2025 at 12:09:40AM +0000, Joshua Peraza wrote: > From: Rajat Jain <rajatja@google.com> > > The "DmaProperty" is supported and currently documented and used by > Microsoft [link 1 below], to flag internal PCIe root ports that need > DMA protection [link 2 below]. We have discussed with them and reached > a common understanding that they shall change their MSDN documentation > to say that the same property can be used to protect any PCI device, > and not just internal PCIe root ports (since there is no point > introducing yet another property for arbitrary PCI devices). This helps > with security from internal devices that offer an attack surface for > DMA attacks (e.g. internal network devices). > > Support DmaProperty to mark DMA from a PCI device as untrusted. > > Link: [1] https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports#identifying-internal-pcie-ports-accessible-to-users-and-requiring-dma-protection > Link: [2] https://docs.microsoft.com/en-us/windows/security/information-protection/kernel-dma-protection-for-thunderbolt > Signed-off-by: Rajat Jain <rajatja@google.com> > Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> > Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > Signed-off-by: Joshua Peraza <jperaza@google.com> > --- > drivers/acpi/property.c | 3 +++ > drivers/pci/pci-acpi.c | 22 ++++++++++++++++++++++ > 2 files changed, 25 insertions(+) Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c index 436019d96027..bb1459c43b6b 100644 --- a/drivers/acpi/property.c +++ b/drivers/acpi/property.c @@ -56,6 +56,9 @@ static const guid_t prp_guids[] = { /* Storage device needs D3 GUID: 5025030f-842f-4ab4-a561-99a5189762d0 */ GUID_INIT(0x5025030f, 0x842f, 0x4ab4, 0xa5, 0x61, 0x99, 0xa5, 0x18, 0x97, 0x62, 0xd0), + /* DmaProperty for PCI devices GUID: 70d24161-6dd5-4c9e-8070-705531292865 */ + GUID_INIT(0x70d24161, 0x6dd5, 0x4c9e, + 0x80, 0x70, 0x70, 0x55, 0x31, 0x29, 0x28, 0x65), }; /* ACPI _DSD data subnodes GUID [1]: dbb8e3e6-5886-4ba6-8795-1319f52a966b */ diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index af370628e583..a457ae3e811a 100644 --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -1438,12 +1438,34 @@ static void pci_acpi_set_external_facing(struct pci_dev *dev) dev->external_facing = 1; } +static int pci_dev_has_dma_property(struct pci_dev *dev) +{ + struct acpi_device *adev; + const union acpi_object *obj; + + adev = ACPI_COMPANION(&dev->dev); + if (!adev) + return 0; + + /* + * Property used by Microsoft Windows to enforce IOMMU DMA + * protection from any device, that the system may not fully trust; + * we'll honour it the same way. + */ + if (!acpi_dev_get_property(adev, "DmaProperty", ACPI_TYPE_INTEGER, + &obj) && obj->integer.value == 1) + return 1; + + return 0; +} + void pci_acpi_setup(struct device *dev, struct acpi_device *adev) { struct pci_dev *pci_dev = to_pci_dev(dev); pci_acpi_optimize_delay(pci_dev, adev->handle); pci_acpi_set_external_facing(pci_dev); + pci_dev->untrusted |= pci_dev_has_dma_property(pci_dev); pci_acpi_add_edr_notifier(pci_dev); pci_acpi_add_pm_notifier(adev, pci_dev);