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Message-ID: <20220208133425.1096-6-shameerali.kolothum.thodi@huawei.com> Date: Tue, 8 Feb 2022 13:34:22 +0000 From: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com> To: <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <linux-crypto@...r.kernel.org> CC: <alex.williamson@...hat.com>, <jgg@...dia.com>, <cohuck@...hat.com>, <mgurtovoy@...dia.com>, <yishaih@...dia.com>, <linuxarm@...wei.com>, <liulongfang@...wei.com>, <prime.zeng@...ilicon.com>, <jonathan.cameron@...wei.com>, <wangzhou1@...ilicon.com> Subject: [RFC v4 5/8] hisi_acc_vfio_pci: Restrict access to VF dev BAR2 migration region HiSilicon ACC VF device BAR2 region consists of both functional register space and migration control register space. From a security point of view, it's not advisable to export the migration control region to Guest. Hence, override the ioctl/read/write/mmap methods to hide the migration region and limit the access only to the functional register space. Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com> --- drivers/vfio/pci/hisi_acc_vfio_pci.c | 122 ++++++++++++++++++++++++++- 1 file changed, 118 insertions(+), 4 deletions(-) diff --git a/drivers/vfio/pci/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisi_acc_vfio_pci.c index 8b59e628110e..563ed2cc861f 100644 --- a/drivers/vfio/pci/hisi_acc_vfio_pci.c +++ b/drivers/vfio/pci/hisi_acc_vfio_pci.c @@ -13,6 +13,120 @@ #include <linux/vfio.h> #include <linux/vfio_pci_core.h> +static int hisi_acc_pci_rw_access_check(struct vfio_device *core_vdev, + size_t count, loff_t *ppos, + size_t *new_count) +{ + unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos); + struct vfio_pci_core_device *vdev = + container_of(core_vdev, struct vfio_pci_core_device, vdev); + + if (index == VFIO_PCI_BAR2_REGION_INDEX) { + loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK; + resource_size_t end = pci_resource_len(vdev->pdev, index) / 2; + + /* Check if access is for migration control region */ + if (pos >= end) + return -EINVAL; + + *new_count = min(count, (size_t)(end - pos)); + } + + return 0; +} + +static int hisi_acc_vfio_pci_mmap(struct vfio_device *core_vdev, + struct vm_area_struct *vma) +{ + struct vfio_pci_core_device *vdev = + container_of(core_vdev, struct vfio_pci_core_device, vdev); + unsigned int index; + + index = vma->vm_pgoff >> (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT); + if (index == VFIO_PCI_BAR2_REGION_INDEX) { + u64 req_len, pgoff, req_start; + resource_size_t end = pci_resource_len(vdev->pdev, index) / 2; + + req_len = vma->vm_end - vma->vm_start; + pgoff = vma->vm_pgoff & + ((1U << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1); + req_start = pgoff << PAGE_SHIFT; + + if (req_start + req_len > end) + return -EINVAL; + } + + return vfio_pci_core_mmap(core_vdev, vma); +} + +static ssize_t hisi_acc_vfio_pci_write(struct vfio_device *core_vdev, + const char __user *buf, size_t count, + loff_t *ppos) +{ + size_t new_count = count; + int ret; + + ret = hisi_acc_pci_rw_access_check(core_vdev, count, ppos, &new_count); + if (ret) + return ret; + + return vfio_pci_core_write(core_vdev, buf, new_count, ppos); +} + +static ssize_t hisi_acc_vfio_pci_read(struct vfio_device *core_vdev, + char __user *buf, size_t count, + loff_t *ppos) +{ + size_t new_count = count; + int ret; + + ret = hisi_acc_pci_rw_access_check(core_vdev, count, ppos, &new_count); + if (ret) + return ret; + + return vfio_pci_core_read(core_vdev, buf, new_count, ppos); +} + +static long hisi_acc_vfio_pci_ioctl(struct vfio_device *core_vdev, unsigned int cmd, + unsigned long arg) +{ + struct vfio_pci_core_device *vdev = + container_of(core_vdev, struct vfio_pci_core_device, vdev); + + if (cmd == VFIO_DEVICE_GET_REGION_INFO) { + struct pci_dev *pdev = vdev->pdev; + struct vfio_region_info info; + unsigned long minsz; + + minsz = offsetofend(struct vfio_region_info, offset); + + if (copy_from_user(&info, (void __user *)arg, minsz)) + return -EFAULT; + + if (info.argsz < minsz) + return -EINVAL; + + if (info.index == VFIO_PCI_BAR2_REGION_INDEX) { + info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index); + + /* + * ACC VF dev BAR2 region consists of both functional + * register space and migration control register space. + * Report only the functional region to Guest. + */ + info.size = pci_resource_len(pdev, info.index) / 2; + + info.flags = VFIO_REGION_INFO_FLAG_READ | + VFIO_REGION_INFO_FLAG_WRITE | + VFIO_REGION_INFO_FLAG_MMAP; + + return copy_to_user((void __user *)arg, &info, minsz) ? + -EFAULT : 0; + } + } + return vfio_pci_core_ioctl(core_vdev, cmd, arg); +} + static int hisi_acc_vfio_pci_open_device(struct vfio_device *core_vdev) { struct vfio_pci_core_device *vdev = @@ -32,10 +146,10 @@ static const struct vfio_device_ops hisi_acc_vfio_pci_ops = { .name = "hisi-acc-vfio-pci", .open_device = hisi_acc_vfio_pci_open_device, .close_device = vfio_pci_core_close_device, - .ioctl = vfio_pci_core_ioctl, - .read = vfio_pci_core_read, - .write = vfio_pci_core_write, - .mmap = vfio_pci_core_mmap, + .ioctl = hisi_acc_vfio_pci_ioctl, + .read = hisi_acc_vfio_pci_read, + .write = hisi_acc_vfio_pci_write, + .mmap = hisi_acc_vfio_pci_mmap, .request = vfio_pci_core_request, .match = vfio_pci_core_match, }; -- 2.17.1
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