RE: [PATCH v6 09/15] iommu/vt-d: Check ownership for PASIDs from user-space

Liu, Yi L
2020-08-17T05:39:15Z

Hi Eric,

> From: Auger Eric <eric.auger@redhat.com>
> Sent: Sunday, August 16, 2020 12:30 AM
>
> Hi Yi,
>
> On 7/28/20 8:27 AM, Liu Yi L wrote:
> > When an IOMMU domain with nesting attribute is used for guest SVA, a
> > system-wide PASID is allocated for binding with the device and the domain.
> > For security reason, we need to check the PASID passed from user-space.
> > e.g. page table bind/unbind and PASID related cache invalidation.
> >
> > Cc: Kevin Tian <kevin.tian@intel.com>
> > CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > Cc: Alex Williamson <alex.williamson@redhat.com>
> > Cc: Eric Auger <eric.auger@redhat.com>
> > Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> > Cc: Joerg Roedel <joro@8bytes.org>
> > Cc: Lu Baolu <baolu.lu@linux.intel.com>
> > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > ---
> > drivers/iommu/intel/iommu.c | 10 ++++++++++
> > drivers/iommu/intel/svm.c | 7 +++++--
> > 2 files changed, 15 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index b2fe54e..88f4647 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -5436,6 +5436,7 @@ intel_iommu_sva_invalidate(struct iommu_domain
> *domain, struct device *dev,
> > int granu = 0;
> > u64 pasid = 0;
> > u64 addr = 0;
> > + void *pdata;
> >
> > granu = to_vtd_granularity(cache_type, inv_info->granularity);
> > if (granu == -EINVAL) {
> > @@ -5456,6 +5457,15 @@ intel_iommu_sva_invalidate(struct iommu_domain
> *domain, struct device *dev,
> > (inv_info->granu.addr_info.flags &
> IOMMU_INV_ADDR_FLAGS_PASID))
> > pasid = inv_info->granu.addr_info.pasid;
> >
> > + pdata = ioasid_find(dmar_domain->ioasid_sid, pasid, NULL);
> > + if (!pdata) {
> > + ret = -EINVAL;
> > + goto out_unlock;
> > + } else if (IS_ERR(pdata)) {
> > + ret = PTR_ERR(pdata);
> > + goto out_unlock;
> > + }
> > +
> > switch (BIT(cache_type)) {
> > case IOMMU_CACHE_INV_TYPE_IOTLB:
> > /* HW will ignore LSB bits based on address mask */
> > diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> > index c85b8d5..b9b29ad 100644
> > --- a/drivers/iommu/intel/svm.c
> > +++ b/drivers/iommu/intel/svm.c
> > @@ -323,7 +323,7 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain,
> struct device *dev,
> > dmar_domain = to_dmar_domain(domain);
> >
> > mutex_lock(&pasid_mutex);
> > - svm = ioasid_find(INVALID_IOASID_SET, data->hpasid, NULL);
> > + svm = ioasid_find(dmar_domain->ioasid_sid, data->hpasid, NULL);
> A question about the locking strategy. We don't take the
> device_domain_lock here. Could you clarify whether it is safe?

I guess it is better to take the same lock as what iommu_domain_set_attr()
takes. thanks for catching it. :-)

>
> > if (IS_ERR(svm)) {
> > ret = PTR_ERR(svm);
> > goto out;
> > @@ -440,6 +440,7 @@ int intel_svm_unbind_gpasid(struct iommu_domain
> *domain,
> > struct device *dev, u32 pasid)
> > {
> > struct intel_iommu *iommu = intel_svm_device_to_iommu(dev);
> > + struct dmar_domain *dmar_domain;
> > struct intel_svm_dev *sdev;
> > struct intel_svm *svm;
> > int ret = -EINVAL;
> > @@ -447,8 +448,10 @@ int intel_svm_unbind_gpasid(struct iommu_domain
> *domain,
> > if (WARN_ON(!iommu))
> > return -EINVAL;
> >
> > + dmar_domain = to_dmar_domain(domain);
> > +
> > mutex_lock(&pasid_mutex);
> > - svm = ioasid_find(INVALID_IOASID_SET, pasid, NULL);
> > + svm = ioasid_find(dmar_domain->ioasid_sid, pasid, NULL);
> same here.

same.

Regards,
Yi Liu

> > if (!svm) {
> > ret = -EINVAL;
> > goto out;
> >
> Thanks
>
> Eric