[+cc Greg, Jean-Philippe, Mika, Pavel, Oliver, Joerg since they commented on previous "external-facing" discussion] On Wed, Jan 19, 2022 at 04:04:09PM -0800, Rajat Jain wrote: > Today the pci_dev->untrusted is set for any devices sitting downstream > an external facing port (determined via "ExternalFacingPort" property). > This however, disallows any internal devices to be marked as untrusted. This isn't stated quite accurately. "dev->untrusted" is currently set only by set_pcie_untrusted(), when "dev" has an upstream bridge that is either external-facing or untrusted. But that doesn't disallow or prevent internal devices from being marked as untrusted; it just doesn't implement that. > There are use-cases though, where a platform would like to treat an > internal device as untrusted (perhaps because it runs untrusted > firmware, or offers an attack surface by handling untrusted network > data etc). > > This patch introduces a new "UntrustedDevice" property that can be used > by the firmware to mark any device as untrusted. I think I'm OK with this. Write this last sentence in imperative mood; see https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/maintainer-tip.rst?id=v5.16#n134 for examples. > Signed-off-by: Rajat Jain <rajatja@xxxxxxxxxx> > --- > drivers/pci/pci-acpi.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c > index a42dbf448860..3d9e5fa49451 100644 > --- a/drivers/pci/pci-acpi.c > +++ b/drivers/pci/pci-acpi.c > @@ -1350,12 +1350,25 @@ static void pci_acpi_set_external_facing(struct pci_dev *dev) > dev->external_facing = 1; > } > > +static void pci_acpi_set_untrusted(struct pci_dev *dev) > +{ > + u8 val; > + > + if (device_property_read_u8(&dev->dev, "UntrustedDevice", &val)) > + return; > + > + /* These PCI devices are not trustworthy */ Comment is probably superfluous since the code seems obvious without it. > + if (val) > + dev->untrusted = 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_set_untrusted(pci_dev); > pci_acpi_add_edr_notifier(pci_dev); > > pci_acpi_add_pm_notifier(adev, pci_dev); > -- > 2.34.1.703.g22d0c6ccf7-goog >
