On Wed, Feb 9, 2022 at 7:39 PM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > On Wed, Feb 09, 2022 at 06:46:12AM +0100, Greg Kroah-Hartman wrote: > > On Tue, Feb 08, 2022 at 04:23:27PM -0800, Rajat Jain wrote: > > > On Tue, Feb 1, 2022 at 6:01 PM Rajat Jain <rajatja@xxxxxxxxxx> wrote: > > > > > > > > Today the pci_dev->untrusted is set for any devices sitting downstream > > > > an external facing port (determined via "ExternalFacingPort" or the > > > > "external-facing" properties). > > > > > > > > However, currently there is no way for internal devices to be marked as > > > > untrusted. > > > > > > > > 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). > > > > > > > > Introduce a new "UntrustedDevice" property that can be used by the > > > > firmware to mark any device as untrusted. > > > > > > Just to unite the threads (from > > > https://www.spinics.net/lists/linux-pci/msg120221.html). I did reach > > > out to Microsoft but they haven't acknowledged my email. I also pinged > > > them again yesterday, but I suspect I may not be able to break the > > > ice. So this patch may be ready to go in my opinion. > > > > > > I don't see any outstanding comments on this patch, but please let me > > > know if you have any comments. > > > > > > > Signed-off-by: Rajat Jain <rajatja@xxxxxxxxxx> > > > > --- > > > > v2: * Also use the same property for device tree based systems. > > > > * Add documentation (next patch) > > > > > > > > drivers/pci/of.c | 2 ++ > > > > drivers/pci/pci-acpi.c | 1 + > > > > drivers/pci/pci.c | 9 +++++++++ > > > > drivers/pci/pci.h | 2 ++ > > > > 4 files changed, 14 insertions(+) > > > > > > > > diff --git a/drivers/pci/of.c b/drivers/pci/of.c > > > > index cb2e8351c2cc..e8b804664b69 100644 > > > > --- a/drivers/pci/of.c > > > > +++ b/drivers/pci/of.c > > > > @@ -24,6 +24,8 @@ void pci_set_of_node(struct pci_dev *dev) > > > > dev->devfn); > > > > if (dev->dev.of_node) > > > > dev->dev.fwnode = &dev->dev.of_node->fwnode; > > > > + > > > > + pci_set_untrusted(dev); > > > > } > > > > > > > > void pci_release_of_node(struct pci_dev *dev) > > > > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c > > > > index a42dbf448860..2bffbd5c6114 100644 > > > > --- a/drivers/pci/pci-acpi.c > > > > +++ b/drivers/pci/pci-acpi.c > > > > @@ -1356,6 +1356,7 @@ void pci_acpi_setup(struct device *dev, struct acpi_device *adev) > > > > > > > > pci_acpi_optimize_delay(pci_dev, adev->handle); > > > > pci_acpi_set_external_facing(pci_dev); > > > > + pci_set_untrusted(pci_dev); > > > > pci_acpi_add_edr_notifier(pci_dev); > > > > > > > > pci_acpi_add_pm_notifier(adev, pci_dev); > > > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > > > > index 9ecce435fb3f..41e887c27004 100644 > > > > --- a/drivers/pci/pci.c > > > > +++ b/drivers/pci/pci.c > > > > @@ -6869,3 +6869,12 @@ static int __init pci_realloc_setup_params(void) > > > > return 0; > > > > } > > > > pure_initcall(pci_realloc_setup_params); > > > > + > > > > +void pci_set_untrusted(struct pci_dev *pdev) > > > > +{ > > > > + u8 val; > > > > + > > > > + if (!device_property_read_u8(&pdev->dev, "UntrustedDevice", &val) > > If we do this, can we combine it with set_pcie_untrusted(), where we > already set pdev->untrusted? Maybe that needs to be renamed; I don't > see anything PCIe-specific there, and it looks like it works for > conventional PCI as well. > > > Please no, "Untrusted" does not really convey much, if anything here. > > You are taking an odd in-kernel-value and making it a user api. > > > > Where is this "trust" defined? Who defines it? What policy does the > > kernel impose on it? > > I'm a bit hesitant about this, too. It really doesn't have anything > in particular to do with the PCI core. It's not part of the PCI > specs, and it could apply to any kind of device, not just PCI (ACPI, > platform, USB, etc). > > We have: > > dev->removable # struct device > pdev->is_thunderbolt > pdev->untrusted > pdev->external_facing > > and it feels a little hard to keep everything straight. Most of them > are "discovered" based on some DT or ACPI firmware property. None of > them really has anything specifically to do with *PCI*, and I don't > think the PCI core depends on any of them. I think > pdev->is_thunderbolt is the only one we discover based on a PCI > feature (the Thunderbolt Capability), and the things we *use* it for > are actually not things specified by that capability [1]. > > Could drivers just look for these properties directly instead of > relying on the PCI core to get in the middle? Most callers of > device_property_read_*() are in drivers. I do see that doing it in > the PCI core might help enforce standard usage in DT/ACPI, but we > could probably do that in other ways, too. FWIW, I agree that looking at these things in drivers would be better. > [1] https://lore.kernel.org/r/20220204222956.GA220908@bhelgaas
