| Message ID | 20220320062907.3272903-2-rajatja@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | [v4,1/2] PCI: Rename "pci_dev->untrusted" to "pci_dev->poses_dma_risk" | expand |
On Sat, Mar 19, 2022 at 11:29:06PM -0700, Rajat Jain wrote: > The "DmaProperty" is supported and documented by Microsoft here: > https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports > They use this property for DMA protection: > https://docs.microsoft.com/en-us/windows/security/information-protection/kernel-dma-protection-for-thunderbolt > > Support the "DmaProperty" with the same semantics. This is useful for > internal PCI devices that do not hang off a PCIe rootport, but offer > an attack surface for DMA attacks (e.g. internal network devices). > > Signed-off-by: Rajat Jain <rajatja@google.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c index d0986bda2964..20603cacc28d 100644 --- a/drivers/acpi/property.c +++ b/drivers/acpi/property.c @@ -48,6 +48,9 @@ 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: dbb8e3e6-5886-4ba6-8795-1319f52a966b */ diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index 1f15ab7eabf8..5360f1af2ed3 100644 --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -1350,12 +1350,28 @@ static void pci_acpi_set_external_facing(struct pci_dev *dev) dev->external_facing = 1; } +static void pci_acpi_check_for_dma_protection(struct pci_dev *dev) +{ + u8 val; + + /* + * Property also used by Microsoft Windows for same purpose, + * (to implement DMA protection from a device, using the IOMMU). + */ + if (device_property_read_u8(&dev->dev, "DmaProperty", &val)) + return; + + if (val) + dev->poses_dma_risk = 1; +} + 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_acpi_check_for_dma_protection(pci_dev); pci_acpi_add_edr_notifier(pci_dev); pci_acpi_add_pm_notifier(adev, pci_dev);
The "DmaProperty" is supported and documented by Microsoft here: https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports They use this property for DMA protection: https://docs.microsoft.com/en-us/windows/security/information-protection/kernel-dma-protection-for-thunderbolt Support the "DmaProperty" with the same semantics. This is useful for internal PCI devices that do not hang off a PCIe rootport, but offer an attack surface for DMA attacks (e.g. internal network devices). Signed-off-by: Rajat Jain <rajatja@google.com> --- v4: * Add the GUID. * Use the (now) renamed property - pci_dev->poses_dma_risk) * Update the comment and commitlog. v3: * Use Microsoft's documented property "DmaProperty" * Resctrict to ACPI only drivers/acpi/property.c | 3 +++ drivers/pci/pci-acpi.c | 16 ++++++++++++++++ 2 files changed, 19 insertions(+)