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BACKPORT: FROMLIST: PCI/ACPI: Support Microsoft's "DmaProperty"

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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: https://lore.kernel.org/all/20250221000943.973221-3-jperaza@google.com/
Bug: 369726566
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
Change-Id: Icd465fdf3789cece45538a2db60b1a5de47e8dcb
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>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Joshua Peraza <jperaza@google.com>
This commit is contained in:
Rajat Jain
2025-02-21 00:09:40 +00:00
committed by Joshua Peraza
parent d975192d74
commit 8f8b58955d
2 changed files with 25 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/acpi/property.c
+3
View File
@@ -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 */
drivers/pci/pci-acpi.c
+22
View File
@@ -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);