Re: [PATCH v3 4/5] iommu/uapi: Handle data and argsz filled by users

[Lu Baolu]

On 2020/6/25 1:07, Jacob Pan wrote:
> On Wed, 24 Jun 2020 14:54:49 +0800
> Lu Baolu<baolu.lu@xxxxxxxxxxxxxxx>  wrote:
>
> > Hi Jacob,
> >
> > On 2020/6/24 1:03, Jacob Pan wrote:
> > > IOMMU UAPI data has a user filled argsz field which indicates the
> > > data length comes with the API call. User data is not trusted,
> > > argsz must be validated based on the current kernel data size,
> > > mandatory data size, and feature flags.
> > >
> > > User data may also be extended, results in possible argsz increase.
> > > Backward compatibility is ensured based on size and flags checking.
> > > Details are documented in Documentation/userspace-api/iommu.rst
> > >
> > > This patch adds sanity checks in both IOMMU layer and vendor code,
> > > where VT-d is the only user for now.
> > >
> > > Signed-off-by: Liu Yi L<yi.l.liu@xxxxxxxxx>
> > > Signed-off-by: Jacob Pan<jacob.jun.pan@xxxxxxxxxxxxxxx>
> > > ---
> > >    drivers/iommu/intel/svm.c |  3 ++
> > >    drivers/iommu/iommu.c     | 96
> > > ++++++++++++++++++++++++++++++++++++++++++++---
> > > include/linux/iommu.h     |  7 ++-- 3 files changed, 98
> > > insertions(+), 8 deletions(-)
> > >
> > > diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> > > index 713b3a218483..237db56878c0 100644
> > > --- a/drivers/iommu/intel/svm.c
> > > +++ b/drivers/iommu/intel/svm.c
> > > @@ -244,6 +244,9 @@ int intel_svm_bind_gpasid(struct iommu_domain
> > > *domain, struct device *dev, data->format !=
> > > IOMMU_PASID_FORMAT_INTEL_VTD) return -EINVAL;
> > >    
> > > +	if (data->argsz != offsetofend(struct
> > > iommu_gpasid_bind_data, vendor.vtd))
> > > +		return -EINVAL;
> > Need to do size check in intel_iommu_sva_invalidate() as well?
> No need. The difference is that there is no
> vendor specific union for intel_iommu_sva_invalidate().
>
> Generic flags are used to process invalidation data inside
> intel_iommu_sva_invalidate().

Thanks for the explanation. With the nit tweaked,

Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Best regards,
baolu