| Message ID | 20200515104359.1178606-2-jean-philippe@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | PCI, iommu: Factor 'untrusted' check for ATS enablement | expand |
Hi Jean-Philippe, thanks for doing this! On Fri, May 15, 2020 at 12:43:59PM +0200, Jean-Philippe Brucker wrote: > Add pci_ats_supported(), which checks whether a device has an ATS > capability, and whether it is trusted. A device is untrusted if it is > plugged into an external-facing port such as Thunderbolt and could be > spoof an existing device to exploit weaknesses in the IOMMU > configuration. PCIe ATS is one such weaknesses since it allows > endpoints to cache IOMMU translations and emit transactions with > 'Translated' Address Type (10b) that partially bypass the IOMMU > translation. > > The SMMUv3 and VT-d IOMMU drivers already disallow ATS and transactions > with 'Translated' Address Type for untrusted devices. Add the check to > pci_enable_ats() to let other drivers (AMD IOMMU for now) benefit from > it. > > By checking ats_cap, the pci_ats_supported() helper also returns whether > ATS was globally disabled with pci=noats, and could later include more > things, for example whether the whole PCIe hierarchy down to the > endpoint supports ATS. > > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> > --- > include/linux/pci-ats.h | 3 +++ > drivers/pci/ats.c | 18 +++++++++++++++++- > 2 files changed, 20 insertions(+), 1 deletion(-) > > diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h > index d08f0869f1213e..f75c307f346de9 100644 > --- a/include/linux/pci-ats.h > +++ b/include/linux/pci-ats.h > @@ -6,11 +6,14 @@ > > #ifdef CONFIG_PCI_ATS > /* Address Translation Service */ > +bool pci_ats_supported(struct pci_dev *dev); > int pci_enable_ats(struct pci_dev *dev, int ps); > void pci_disable_ats(struct pci_dev *dev); > int pci_ats_queue_depth(struct pci_dev *dev); > int pci_ats_page_aligned(struct pci_dev *dev); > #else /* CONFIG_PCI_ATS */ > +static inline bool pci_ats_supported(struct pci_dev *d) > +{ return false; } > static inline int pci_enable_ats(struct pci_dev *d, int ps) > { return -ENODEV; } > static inline void pci_disable_ats(struct pci_dev *d) { } > diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c > index 390e92f2d8d1fc..15fa0c37fd8e44 100644 > --- a/drivers/pci/ats.c > +++ b/drivers/pci/ats.c > @@ -30,6 +30,22 @@ void pci_ats_init(struct pci_dev *dev) > dev->ats_cap = pos; > } > > +/** > + * pci_ats_supported - check if the device can use ATS > + * @dev: the PCI device > + * > + * Returns true if the device supports ATS and is allowed to use it, false > + * otherwise. > + */ > +bool pci_ats_supported(struct pci_dev *dev) > +{ > + if (!dev->ats_cap) > + return false; > + > + return !dev->untrusted; dev->untrusted is an 'unsigned int :1', so while this works I would prefer 'return (dev->untrusted == 0);' here, to be more type-safe. With that changed: Reviewed-by: Joerg Roedel <jroedel@suse.de> > +} > +EXPORT_SYMBOL_GPL(pci_ats_supported); > + > /** > * pci_enable_ats - enable the ATS capability > * @dev: the PCI device > @@ -42,7 +58,7 @@ int pci_enable_ats(struct pci_dev *dev, int ps) > u16 ctrl; > struct pci_dev *pdev; > > - if (!dev->ats_cap) > + if (!pci_ats_supported(dev)) > return -EINVAL; > > if (WARN_ON(dev->ats_enabled)) > -- > 2.26.2
On Fri, May 15, 2020 at 12:43:59PM +0200, Jean-Philippe Brucker wrote: > Add pci_ats_supported(), which checks whether a device has an ATS > capability, and whether it is trusted. A device is untrusted if it is > plugged into an external-facing port such as Thunderbolt and could be > spoof an existing device to exploit weaknesses in the IOMMU > configuration. PCIe ATS is one such weaknesses since it allows > endpoints to cache IOMMU translations and emit transactions with > 'Translated' Address Type (10b) that partially bypass the IOMMU > translation. > > The SMMUv3 and VT-d IOMMU drivers already disallow ATS and transactions > with 'Translated' Address Type for untrusted devices. Add the check to > pci_enable_ats() to let other drivers (AMD IOMMU for now) benefit from > it. > > By checking ats_cap, the pci_ats_supported() helper also returns whether > ATS was globally disabled with pci=noats, and could later include more > things, for example whether the whole PCIe hierarchy down to the > endpoint supports ATS. > > Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> Acked-by: Bjorn Helgaas <bhelgaas@google.com> > --- > include/linux/pci-ats.h | 3 +++ > drivers/pci/ats.c | 18 +++++++++++++++++- > 2 files changed, 20 insertions(+), 1 deletion(-) > > diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h > index d08f0869f1213e..f75c307f346de9 100644 > --- a/include/linux/pci-ats.h > +++ b/include/linux/pci-ats.h > @@ -6,11 +6,14 @@ > > #ifdef CONFIG_PCI_ATS > /* Address Translation Service */ > +bool pci_ats_supported(struct pci_dev *dev); > int pci_enable_ats(struct pci_dev *dev, int ps); > void pci_disable_ats(struct pci_dev *dev); > int pci_ats_queue_depth(struct pci_dev *dev); > int pci_ats_page_aligned(struct pci_dev *dev); > #else /* CONFIG_PCI_ATS */ > +static inline bool pci_ats_supported(struct pci_dev *d) > +{ return false; } > static inline int pci_enable_ats(struct pci_dev *d, int ps) > { return -ENODEV; } > static inline void pci_disable_ats(struct pci_dev *d) { } > diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c > index 390e92f2d8d1fc..15fa0c37fd8e44 100644 > --- a/drivers/pci/ats.c > +++ b/drivers/pci/ats.c > @@ -30,6 +30,22 @@ void pci_ats_init(struct pci_dev *dev) > dev->ats_cap = pos; > } > > +/** > + * pci_ats_supported - check if the device can use ATS > + * @dev: the PCI device > + * > + * Returns true if the device supports ATS and is allowed to use it, false > + * otherwise. > + */ > +bool pci_ats_supported(struct pci_dev *dev) > +{ > + if (!dev->ats_cap) > + return false; > + > + return !dev->untrusted; > +} > +EXPORT_SYMBOL_GPL(pci_ats_supported); > + > /** > * pci_enable_ats - enable the ATS capability > * @dev: the PCI device > @@ -42,7 +58,7 @@ int pci_enable_ats(struct pci_dev *dev, int ps) > u16 ctrl; > struct pci_dev *pdev; > > - if (!dev->ats_cap) > + if (!pci_ats_supported(dev)) > return -EINVAL; > > if (WARN_ON(dev->ats_enabled)) > -- > 2.26.2 >
diff --git a/include/linux/pci-ats.h b/include/linux/pci-ats.h index d08f0869f1213e..f75c307f346de9 100644 --- a/include/linux/pci-ats.h +++ b/include/linux/pci-ats.h @@ -6,11 +6,14 @@ #ifdef CONFIG_PCI_ATS /* Address Translation Service */ +bool pci_ats_supported(struct pci_dev *dev); int pci_enable_ats(struct pci_dev *dev, int ps); void pci_disable_ats(struct pci_dev *dev); int pci_ats_queue_depth(struct pci_dev *dev); int pci_ats_page_aligned(struct pci_dev *dev); #else /* CONFIG_PCI_ATS */ +static inline bool pci_ats_supported(struct pci_dev *d) +{ return false; } static inline int pci_enable_ats(struct pci_dev *d, int ps) { return -ENODEV; } static inline void pci_disable_ats(struct pci_dev *d) { } diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c index 390e92f2d8d1fc..15fa0c37fd8e44 100644 --- a/drivers/pci/ats.c +++ b/drivers/pci/ats.c @@ -30,6 +30,22 @@ void pci_ats_init(struct pci_dev *dev) dev->ats_cap = pos; } +/** + * pci_ats_supported - check if the device can use ATS + * @dev: the PCI device + * + * Returns true if the device supports ATS and is allowed to use it, false + * otherwise. + */ +bool pci_ats_supported(struct pci_dev *dev) +{ + if (!dev->ats_cap) + return false; + + return !dev->untrusted; +} +EXPORT_SYMBOL_GPL(pci_ats_supported); + /** * pci_enable_ats - enable the ATS capability * @dev: the PCI device @@ -42,7 +58,7 @@ int pci_enable_ats(struct pci_dev *dev, int ps) u16 ctrl; struct pci_dev *pdev; - if (!dev->ats_cap) + if (!pci_ats_supported(dev)) return -EINVAL; if (WARN_ON(dev->ats_enabled))
Add pci_ats_supported(), which checks whether a device has an ATS capability, and whether it is trusted. A device is untrusted if it is plugged into an external-facing port such as Thunderbolt and could be spoof an existing device to exploit weaknesses in the IOMMU configuration. PCIe ATS is one such weaknesses since it allows endpoints to cache IOMMU translations and emit transactions with 'Translated' Address Type (10b) that partially bypass the IOMMU translation. The SMMUv3 and VT-d IOMMU drivers already disallow ATS and transactions with 'Translated' Address Type for untrusted devices. Add the check to pci_enable_ats() to let other drivers (AMD IOMMU for now) benefit from it. By checking ats_cap, the pci_ats_supported() helper also returns whether ATS was globally disabled with pci=noats, and could later include more things, for example whether the whole PCIe hierarchy down to the endpoint supports ATS. Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> --- include/linux/pci-ats.h | 3 +++ drivers/pci/ats.c | 18 +++++++++++++++++- 2 files changed, 20 insertions(+), 1 deletion(-)