linux-kernel - Re: [PATCH v12 6/6] iommu/vt-d: Check UAPI data processed by IOMMU core

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Date:   Tue, 29 Sep 2020 13:26:03 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     Jacob Pan <jacob.pan.linux@...il.com>,
        iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Jonathan Corbet <corbet@....net>
Cc:     linux-api@...r.kernel.org,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        Yi Liu <yi.l.liu@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>, Wu Hao <hao.wu@...el.com>,
        Yi Sun <yi.y.sun@...el.com>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v12 6/6] iommu/vt-d: Check UAPI data processed by IOMMU
 core

Hi Jacob,

On 9/25/20 6:32 PM, Jacob Pan wrote:
> IOMMU generic layer already does sanity checks on UAPI data for version
> match and argsz range based on generic information.
> 
> This patch adjusts the following data checking responsibilities:
> - removes the redundant version check from VT-d driver
> - removes the check for vendor specific data size
> - adds check for the use of reserved/undefined flags
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Reviewed-by: Eric Auger <eric.auger@...hat.com>

Thanks

Eric
> ---
>  drivers/iommu/intel/iommu.c |  3 +--
>  drivers/iommu/intel/svm.c   | 11 +++++++++--
>  include/uapi/linux/iommu.h  |  1 +
>  3 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 461f3a6864d4..18ed3b3c70d7 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -5408,8 +5408,7 @@ intel_iommu_sva_invalidate(struct iommu_domain *domain, struct device *dev,
>  	int ret = 0;
>  	u64 size = 0;
>  
> -	if (!inv_info || !dmar_domain ||
> -	    inv_info->version != IOMMU_CACHE_INVALIDATE_INFO_VERSION_1)
> +	if (!inv_info || !dmar_domain)
>  		return -EINVAL;
>  
>  	if (!dev || !dev_is_pci(dev))
> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> index 99353d6468fa..0cb9a15f1112 100644
> --- a/drivers/iommu/intel/svm.c
> +++ b/drivers/iommu/intel/svm.c
> @@ -284,8 +284,15 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev,
>  	if (WARN_ON(!iommu) || !data)
>  		return -EINVAL;
>  
> -	if (data->version != IOMMU_GPASID_BIND_VERSION_1 ||
> -	    data->format != IOMMU_PASID_FORMAT_INTEL_VTD)
> +	if (data->format != IOMMU_PASID_FORMAT_INTEL_VTD)
> +		return -EINVAL;
> +
> +	/* IOMMU core ensures argsz is more than the start of the union */
> +	if (data->argsz < offsetofend(struct iommu_gpasid_bind_data, vendor.vtd))
> +		return -EINVAL;
> +
> +	/* Make sure no undefined flags are used in vendor data */
> +	if (data->vendor.vtd.flags & ~(IOMMU_SVA_VTD_GPASID_LAST - 1))
>  		return -EINVAL;
>  
>  	if (!dev_is_pci(dev))
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index 66d4ca40b40f..e1d9e75f2c94 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -288,6 +288,7 @@ struct iommu_gpasid_bind_data_vtd {
>  #define IOMMU_SVA_VTD_GPASID_PWT	(1 << 3) /* page-level write through */
>  #define IOMMU_SVA_VTD_GPASID_EMTE	(1 << 4) /* extended mem type enable */
>  #define IOMMU_SVA_VTD_GPASID_CD		(1 << 5) /* PASID-level cache disable */
> +#define IOMMU_SVA_VTD_GPASID_LAST	(1 << 6)
>  	__u64 flags;
>  	__u32 pat;
>  	__u32 emt;
>