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| author | Mika Westerberg <mika.westerberg@linux.intel.com> | 2018-08-16 12:28:48 +0300 |
|---|---|---|
| committer | Mika Westerberg <mika.westerberg@linux.intel.com> | 2018-12-05 12:01:55 +0300 |
| commit | 617654aae50eb59dd98aa53fb562e850937f4cde (patch) | |
| tree | 8daf2232117f9b2c759b6f9ae641eab55c0faacf /include/linux/pci.h | |
| parent | 2595646791c319cadfdbf271563aac97d0843dc7 (diff) | |
| download | linux-617654aae50eb59dd98aa53fb562e850937f4cde.tar.xz | |
PCI / ACPI: Identify untrusted PCI devices
A malicious PCI device may use DMA to attack the system. An external
Thunderbolt port is a convenient point to attach such a device. The OS
may use IOMMU to defend against DMA attacks.
Some BIOSes mark these externally facing root ports with this
ACPI _DSD [1]:
Name (_DSD, Package () {
ToUUID ("efcc06cc-73ac-4bc3-bff0-76143807c389"),
Package () {
Package () {"ExternalFacingPort", 1},
Package () {"UID", 0 }
}
})
If we find such a root port, mark it and all its children as untrusted.
The rest of the OS may use this information to enable DMA protection
against malicious devices. For instance the device may be put behind an
IOMMU to keep it from accessing memory outside of what the driver has
allocated for it.
While at it, add a comment on top of prp_guids array explaining the
possible caveat resulting when these GUIDs are treated equivalent.
[1] https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports#identifying-externally-exposed-pcie-root-ports
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Diffstat (limited to 'include/linux/pci.h')
| -rw-r--r-- | include/linux/pci.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/pci.h b/include/linux/pci.h index 11c71c4ecf75..c786a2f27bee 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -396,6 +396,14 @@ struct pci_dev { unsigned int is_hotplug_bridge:1; unsigned int shpc_managed:1; /* SHPC owned by shpchp */ unsigned int is_thunderbolt:1; /* Thunderbolt controller */ + /* + * Devices marked being untrusted are the ones that can potentially + * execute DMA attacks and similar. They are typically connected + * through external ports such as Thunderbolt but not limited to + * that. When an IOMMU is enabled they should be getting full + * mappings to make sure they cannot access arbitrary memory. + */ + unsigned int untrusted:1; unsigned int __aer_firmware_first_valid:1; unsigned int __aer_firmware_first:1; unsigned int broken_intx_masking:1; /* INTx masking can't be used */ |