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

[Auger Eric <eric.auger@redhat.com>]

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?


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

Eric