> -----Original Message----- > From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx] > Sent: 02 July 2021 21:30 > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> > Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linux-crypto@xxxxxxxxxxxxxxx; jgg@xxxxxxxxxx; mgurtovoy@xxxxxxxxxx; > Linuxarm <linuxarm@xxxxxxxxxx>; liulongfang <liulongfang@xxxxxxxxxx>; > Zengtao (B) <prime.zeng@xxxxxxxxxxxxx>; yuzenghui > <yuzenghui@xxxxxxxxxx>; Jonathan Cameron > <jonathan.cameron@xxxxxxxxxx>; Wangzhou (B) <wangzhou1@xxxxxxxxxxxxx> > Subject: Re: [RFC v2 2/4] hisi_acc_vfio_pci: Override ioctl method to limit > BAR2 region size > > On Fri, 2 Jul 2021 10:58:47 +0100 > 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, hide the migration region and report only the functional register > > space. > > > > Signed-off-by: Shameer Kolothum > <shameerali.kolothum.thodi@xxxxxxxxxx> > > --- > > drivers/vfio/pci/hisi_acc_vfio_pci.c | 42 +++++++++++++++++++++++++++- > > 1 file changed, 41 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/vfio/pci/hisi_acc_vfio_pci.c > b/drivers/vfio/pci/hisi_acc_vfio_pci.c > > index a9e173098ab5..d57cf6d7adaf 100644 > > --- a/drivers/vfio/pci/hisi_acc_vfio_pci.c > > +++ b/drivers/vfio/pci/hisi_acc_vfio_pci.c > > @@ -12,6 +12,46 @@ > > #include <linux/vfio.h> > > #include <linux/vfio_pci_core.h> > > > > +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(64K) consists of both functional > > + * register space and migration control register space. > > + * Report only the first 32K(functional region) to Guest. > > + */ > > + info.size = pci_resource_len(pdev, info.index) / 2; > > + > > Great, but what actually prevents the user from accessing the full > extent of the BAR since you're re-using core code for read/write/mmap, > which are all basing access on pci_resource_len()? Thanks, Ah..true. Missed that. I will add overrides for read/write/mmap and limit the access. Thanks, Shameer > > Alex > > > + 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(struct vfio_device *core_vdev) > > { > > struct vfio_pci_core_device *vdev = > > @@ -33,7 +73,7 @@ static const struct vfio_device_ops > hisi_acc_vfio_pci_ops = { > > .name = "hisi-acc-vfio-pci", > > .open = hisi_acc_vfio_pci_open, > > .release = vfio_pci_core_release, > > - .ioctl = vfio_pci_core_ioctl, > > + .ioctl = hisi_acc_vfio_pci_ioctl, > > .read = vfio_pci_core_read, > > .write = vfio_pci_core_write, > > .mmap = vfio_pci_core_mmap,
