> -----Original Message----- > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > Sent: 09 February 2022 21:42 > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> > Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linux-crypto@xxxxxxxxxxxxxxx; jgg@xxxxxxxxxx; cohuck@xxxxxxxxxx; > mgurtovoy@xxxxxxxxxx; yishaih@xxxxxxxxxx; Linuxarm > <linuxarm@xxxxxxxxxx>; liulongfang <liulongfang@xxxxxxxxxx>; Zengtao (B) > <prime.zeng@xxxxxxxxxxxxx>; Jonathan Cameron > <jonathan.cameron@xxxxxxxxxx>; Wangzhou (B) <wangzhou1@xxxxxxxxxxxxx> > Subject: Re: [RFC v4 5/8] hisi_acc_vfio_pci: Restrict access to VF dev BAR2 > migration region > > On Tue, 8 Feb 2022 13:34:22 +0000 > Shameer Kolothum <shameerali.kolothum.thodi@xxxxxxxxxx> wrote: > > > 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@xxxxxxxxxx> > > --- > > 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; > > Be careful here, there are nested assignment use cases. This can only > survive one level of assignment before we've restricted more than we > intended. If migration support is dependent on PF access, can we use > that to determine when to when to expose only half the BAR and when to > expose the full BAR? Ok. I will add a check here. > We should also follow the mlx5 lead to use a vendor sub-directory below > drivers/vfio/pci/ Sure. Thanks, Shameer > > Alex > > > + > > + /* 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, > > };
