On Thu, 23 Jul 2020 22:47:02 +0100
Giovanni Cabiddu <giovanni.cabiddu@xxxxxxxxx> wrote:
> 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@xxxxxxxxx>
> ---
> 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..673f53c4798e 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 prevents binding to devices with known errata that may lead to exploitable stability or security issues when accessed by untrusted users.");
s/prevents/allows/
ie. the denylist prevents binding, therefore disabling the denylist
allows binding
I can fix this on commit without a new version if you agree. I also
see that patch 1/5 didn't change since v2, so I'll transfer Bjorn's
ack. If that sounds good I'll queue the first 3 patches in my next
branch for v5.9. Thanks,
Alex
> +
> 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:
