Re: [PATCH v2 2/3] iommu/uapi: Add argsz for user filled data
On Thu, 11 Jun 2020 10:49:36 -0600
Alex Williamson wrote:
> On Wed, 10 Jun 2020 21:12:14 -0700
> Jacob Pan wrote:
>
> > As IOMMU UAPI gets extended, user data size may increase. To support
> > backward compatibiliy, this patch introduces a size field to each
> > UAPI data structures. It is *always* the responsibility for the
> > user to fill in the correct size.
>
> Though at the same time, argsz is user provided data which we don't
> trust. The argsz field allows the user to indicate how much data
> they're providing, it's still the kernel's responsibility to validate
> whether it's correct and sufficient for the requested operation.
> Thanks,
>
Yes, will add this clarification.
Thanks,
Jacob
> Alex
>
> > Specific scenarios for user data handling are documented in:
> > Documentation/userspace-api/iommu.rst
> >
> > Signed-off-by: Liu Yi L
> > Signed-off-by: Jacob Pan
> > ---
> > include/uapi/linux/iommu.h | 6 ++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> > index e907b7091a46..303f148a5cd7 100644
> > --- a/include/uapi/linux/iommu.h
> > +++ b/include/uapi/linux/iommu.h
> > @@ -135,6 +135,7 @@ enum iommu_page_response_code {
> >
> > /**
> > * struct iommu_page_response - Generic page response information
> > + * @argsz: User filled size of this data
> > * @version: API version of this structure
> > * @flags: encodes whether the corresponding fields are valid
> > * (IOMMU_FAULT_PAGE_RESPONSE_* values)
> > @@ -143,6 +144,7 @@ enum iommu_page_response_code {
> > * @code: response code from iommu_page_response_code
> > */
> > struct iommu_page_response {
> > + __u32 argsz;
> > #define IOMMU_PAGE_RESP_VERSION_1 1
> > __u32 version;
> > #define IOMMU_PAGE_RESP_PASID_VALID(1 << 0)
> > @@ -218,6 +220,7 @@ struct iommu_inv_pasid_info {
> > /**
> > * struct iommu_cache_invalidate_info - First level/stage
> > invalidation
> > * information
> > + * @argsz: User filled size of this data
> > * @version: API version of this structure
> > * @cache: bitfield that allows to select which caches to
> > invalidate
> > * @granularity: defines the lowest granularity used for the
> > invalidation: @@ -246,6 +249,7 @@ struct iommu_inv_pasid_info {
> > * must support the used granularity.
> > */
> > struct iommu_cache_invalidate_info {
> > + __u32 argsz;
> > #define IOMMU_CACHE_INVALIDATE_INFO_VERSION_1 1
> > __u32 version;
> > /* IOMMU paging structure cache */
> > @@ -292,6 +296,7 @@ struct iommu_gpasid_bind_data_vtd {
> >
> > /**
> > * struct iommu_gpasid_bind_data - Information about device and
> > guest PASID binding
> > + * @argsz: User filled size of this data
> > * @version: Version of this data structure
> > * @format:PASID table entry format
> > * @flags: Additional information on guest bind request
> > @@ -309,6 +314,7 @@ struct iommu_gpasid_bind_data_vtd {
> > * PASID to host PASID based on this bind data.
> > */
> > struct iommu_gpasid_bind_data {
> > + __u32 argsz;
> > #define IOMMU_GPASID_BIND_VERSION_11
> > __u32 version;
> > #define IOMMU_PASID_FORMAT_INTEL_VTD 1
>
[Jacob Pan]
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Re: [PATCH v2 2/3] iommu/uapi: Add argsz for user filled data
On Wed, 10 Jun 2020 21:12:14 -0700
Jacob Pan wrote:
> As IOMMU UAPI gets extended, user data size may increase. To support
> backward compatibiliy, this patch introduces a size field to each UAPI
> data structures. It is *always* the responsibility for the user to fill in
> the correct size.
Though at the same time, argsz is user provided data which we don't
trust. The argsz field allows the user to indicate how much data
they're providing, it's still the kernel's responsibility to validate
whether it's correct and sufficient for the requested operation.
Thanks,
Alex
> Specific scenarios for user data handling are documented in:
> Documentation/userspace-api/iommu.rst
>
> Signed-off-by: Liu Yi L
> Signed-off-by: Jacob Pan
> ---
> include/uapi/linux/iommu.h | 6 ++
> 1 file changed, 6 insertions(+)
>
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index e907b7091a46..303f148a5cd7 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -135,6 +135,7 @@ enum iommu_page_response_code {
>
> /**
> * struct iommu_page_response - Generic page response information
> + * @argsz: User filled size of this data
> * @version: API version of this structure
> * @flags: encodes whether the corresponding fields are valid
> * (IOMMU_FAULT_PAGE_RESPONSE_* values)
> @@ -143,6 +144,7 @@ enum iommu_page_response_code {
> * @code: response code from iommu_page_response_code
> */
> struct iommu_page_response {
> + __u32 argsz;
> #define IOMMU_PAGE_RESP_VERSION_11
> __u32 version;
> #define IOMMU_PAGE_RESP_PASID_VALID (1 << 0)
> @@ -218,6 +220,7 @@ struct iommu_inv_pasid_info {
> /**
> * struct iommu_cache_invalidate_info - First level/stage invalidation
> * information
> + * @argsz: User filled size of this data
> * @version: API version of this structure
> * @cache: bitfield that allows to select which caches to invalidate
> * @granularity: defines the lowest granularity used for the invalidation:
> @@ -246,6 +249,7 @@ struct iommu_inv_pasid_info {
> * must support the used granularity.
> */
> struct iommu_cache_invalidate_info {
> + __u32 argsz;
> #define IOMMU_CACHE_INVALIDATE_INFO_VERSION_1 1
> __u32 version;
> /* IOMMU paging structure cache */
> @@ -292,6 +296,7 @@ struct iommu_gpasid_bind_data_vtd {
>
> /**
> * struct iommu_gpasid_bind_data - Information about device and guest PASID
> binding
> + * @argsz: User filled size of this data
> * @version: Version of this data structure
> * @format: PASID table entry format
> * @flags: Additional information on guest bind request
> @@ -309,6 +314,7 @@ struct iommu_gpasid_bind_data_vtd {
> * PASID to host PASID based on this bind data.
> */
> struct iommu_gpasid_bind_data {
> + __u32 argsz;
> #define IOMMU_GPASID_BIND_VERSION_1 1
> __u32 version;
> #define IOMMU_PASID_FORMAT_INTEL_VTD 1
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