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Date: Fri, 24 Jul 2020 11:55:57 +0100 From: Giovanni Cabiddu <giovanni.cabiddu@...el.com> To: alex.williamson@...hat.com, herbert@...dor.apana.org.au Cc: cohuck@...hat.com, nhorman@...hat.com, vdronov@...hat.com, bhelgaas@...gle.com, mark.a.chambers@...el.com, gordon.mcfadden@...el.com, ahsan.atta@...el.com, fiona.trahe@...el.com, qat-linux@...el.com, kvm@...r.kernel.org, linux-crypto@...r.kernel.org, linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, Giovanni Cabiddu <giovanni.cabiddu@...el.com> Subject: [PATCH v5 2/5] vfio/pci: Add device denylist Add denylist of devices that by default are not probed by vfio-pci. Devices in this list may be susceptible to untrusted application, even if the IOMMU is enabled. To be accessed via vfio-pci, the user has to explicitly disable the denylist. The denylist can be disabled via the module parameter disable_denylist. Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@...el.com> Reviewed-by: Cornelia Huck <cohuck@...hat.com> Reviewed-by: Fiona Trahe <fiona.trahe@...el.com> --- drivers/vfio/pci/vfio_pci.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 7c0779018b1b..0101f41e7834 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -60,6 +60,10 @@ module_param(enable_sriov, bool, 0644); MODULE_PARM_DESC(enable_sriov, "Enable support for SR-IOV configuration. Enabling SR-IOV on a PF typically requires support of the userspace PF driver, enabling VFs without such support may result in non-functional VFs or PF."); #endif +static bool disable_denylist; +module_param(disable_denylist, bool, 0444); +MODULE_PARM_DESC(disable_denylist, "Disable use of device denylist. Disabling the denylist allows binding to devices with known errata that may lead to exploitable stability or security issues when accessed by untrusted users."); + static inline bool vfio_vga_disabled(void) { #ifdef CONFIG_VFIO_PCI_VGA @@ -69,6 +73,29 @@ static inline bool vfio_vga_disabled(void) #endif } +static bool vfio_pci_dev_in_denylist(struct pci_dev *pdev) +{ + return false; +} + +static bool vfio_pci_is_denylisted(struct pci_dev *pdev) +{ + if (!vfio_pci_dev_in_denylist(pdev)) + return false; + + if (disable_denylist) { + pci_warn(pdev, + "device denylist disabled - allowing device %04x:%04x.\n", + pdev->vendor, pdev->device); + return false; + } + + pci_warn(pdev, "%04x:%04x exists in vfio-pci device denylist, driver probing disallowed.\n", + pdev->vendor, pdev->device); + + return true; +} + /* * Our VGA arbiter participation is limited since we don't know anything * about the device itself. However, if the device is the only VGA device @@ -1847,6 +1874,9 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) struct iommu_group *group; int ret; + if (vfio_pci_is_denylisted(pdev)) + return -EINVAL; + if (pdev->hdr_type != PCI_HEADER_TYPE_NORMAL) return -EINVAL; @@ -2336,6 +2366,9 @@ static int __init vfio_pci_init(void) vfio_pci_fill_ids(); + if (disable_denylist) + pr_warn("device denylist disabled.\n"); + return 0; out_driver: -- 2.26.2
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