Re: [PATCH v5 09/15] iommu/vt-d: Check ownership for PASIDs from user-space

[Auger Eric]

Hi Yi,

On 7/12/20 1:21 PM, 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 passsed from user-space.
passed
> e.g. page table bind/unbind and PASID related cache invalidation.
> 
> Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> CC: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Cc: Eric Auger <eric.auger@xxxxxxxxxx>
> Cc: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
> Cc: Joerg Roedel <joro@xxxxxxxxxx>
> Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
> Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> ---
>  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 4d54198..a9504cb 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 d2c0e1a..212dee0 100644
> --- a/drivers/iommu/intel/svm.c
> +++ b/drivers/iommu/intel/svm.c
> @@ -319,7 +319,7 @@ 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);
I do not get what the call was supposed to do before that patch?
> +	svm = ioasid_find(dmar_domain->ioasid_sid, data->hpasid, NULL);
>  	if (IS_ERR(svm)) {
>  		ret = PTR_ERR(svm);
>  		goto out;
> @@ -436,6 +436,7 @@ int intel_svm_unbind_gpasid(struct iommu_domain *domain,
>  			    struct device *dev, ioasid_t 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;
> @@ -443,8 +444,10 @@ 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);
just to make sure, about the locking, can't domain->ioasid_sid change
under the hood?

Thanks

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