Re: [PATCH v3 5/5] iommu/uapi: Support both kernel and user unbind guest PASID

[Lu Baolu <baolu.lu@linux.intel.com>]

Hi Jacob,

On 2020/6/24 1:03, Jacob Pan wrote:
> Guest SVA unbind data can come from either kernel and user space, if a

either kernel or user space

> user pointer is passed in, IOMMU driver must copy from data from user.

copy data from user

> If the unbind data is assembled in kernel, data can be trusted and
> directly used. This patch creates a wrapper for unbind gpasid such that
> user pointer can be parsed and sanitized before calling into the kernel
> unbind function. Common user data copy code also consolidated.
> 
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
>   drivers/iommu/iommu.c | 70 ++++++++++++++++++++++++++++++++++++++-------------
>   include/linux/iommu.h | 13 ++++++++--
>   2 files changed, 64 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 4a025c429b41..595527e4c6b7 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2010,19 +2010,15 @@ int iommu_cache_invalidate(struct iommu_domain *domain, struct device *dev,
>   }
>   EXPORT_SYMBOL_GPL(iommu_cache_invalidate);
>   
> -int iommu_sva_bind_gpasid(struct iommu_domain *domain, struct device *dev,
> -						void __user *udata)
> -{
>   
> -	struct iommu_gpasid_bind_data data;
> +static int iommu_sva_prepare_bind_data(void __user *udata, bool bind,
> +				       struct iommu_gpasid_bind_data *data)
> +{
>   	unsigned long minsz, maxsz;
>   
> -	if (unlikely(!domain->ops->sva_bind_gpasid))
> -		return -ENODEV;
> -
>   	/* Current kernel data size is the max to be copied from user */
>   	maxsz = sizeof(struct iommu_gpasid_bind_data);
> -	memset((void *)&data, 0, maxsz);
> +	memset((void *)data, 0, maxsz);
>   
>   	/*
>   	 * No new spaces can be added before the variable sized union, the
> @@ -2031,11 +2027,11 @@ int iommu_sva_bind_gpasid(struct iommu_domain *domain, struct device *dev,
>   	minsz = offsetof(struct iommu_gpasid_bind_data, vendor);
>   
>   	/* Copy minsz from user to get flags and argsz */
> -	if (copy_from_user(&data, udata, minsz))
> +	if (copy_from_user(data, udata, minsz))
>   		return -EFAULT;
>   
>   	/* Fields before variable size union is mandatory */
> -	if (data.argsz < minsz)
> +	if (data->argsz < minsz)
>   		return -EINVAL;
>   	/*
>   	 * User might be using a newer UAPI header, we shall let IOMMU vendor
> @@ -2043,26 +2039,66 @@ int iommu_sva_bind_gpasid(struct iommu_domain *domain, struct device *dev,
>   	 * can be vendor specific, larger argsz could be the result of extension
>   	 * for one vendor but it should not affect another vendor.
>   	 */
> -	if (data.argsz > maxsz)
> -		data.argsz = maxsz;
> +	if (data->argsz > maxsz)
> +		data->argsz = maxsz;
> +
> +	/*
> +	 * For unbind, we don't need any extra data, host PASID is included in
> +	 * the minsz and that is all we need.
> +	 */
> +	if (!bind)
> +		return 0;
>   
>   	/* Copy the remaining user data _after_ minsz */
> -	if (copy_from_user((void *)&data + minsz, udata + minsz,
> -				data.argsz - minsz))
> +	if (copy_from_user((void *)data + minsz, udata + minsz,
> +				data->argsz - minsz))
>   		return -EFAULT;
>   
> +	return 0;
> +}
> +
> +int iommu_sva_bind_gpasid(struct iommu_domain *domain, struct device *dev,
> +						void __user *udata)
> +{
> +
> +	struct iommu_gpasid_bind_data data;
> +	int ret;
> +
> +	if (unlikely(!domain->ops->sva_bind_gpasid))
> +		return -ENODEV;
> +
> +	ret = iommu_sva_prepare_bind_data(udata, true, &data);
> +	if (ret)
> +		return ret;
>   
>   	return domain->ops->sva_bind_gpasid(domain, dev, &data);
>   }
>   EXPORT_SYMBOL_GPL(iommu_sva_bind_gpasid);
>   
> -int iommu_sva_unbind_gpasid(struct iommu_domain *domain, struct device *dev,
> -			     ioasid_t pasid)
> +int __iommu_sva_unbind_gpasid(struct iommu_domain *domain, struct device *dev,
> +			struct iommu_gpasid_bind_data *data)
>   {
>   	if (unlikely(!domain->ops->sva_unbind_gpasid))
>   		return -ENODEV;
>   
> -	return domain->ops->sva_unbind_gpasid(dev, pasid);
> +	return domain->ops->sva_unbind_gpasid(dev, data->hpasid);
How about passing @data to the vendor iommu driver as well?

> +}
> +EXPORT_SYMBOL_GPL(__iommu_sva_unbind_gpasid);
> +
> +int iommu_sva_unbind_gpasid(struct iommu_domain *domain, struct device *dev,
> +			void __user *udata)

Keep it aligned.

> +{
> +	struct iommu_gpasid_bind_data data;
> +	int ret;
> +
> +	if (unlikely(!domain->ops->sva_bind_gpasid))
> +		return -ENODEV;
> +
> +	ret = iommu_sva_prepare_bind_data(udata, false, &data);
> +	if (ret)
> +		return ret;
> +
> +	return __iommu_sva_unbind_gpasid(domain, dev, &data);
>   }
>   EXPORT_SYMBOL_GPL(iommu_sva_unbind_gpasid);
>   
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index a688fea42ae5..2567c33dc4e8 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -437,7 +437,9 @@ extern int iommu_cache_invalidate(struct iommu_domain *domain,
>   extern int iommu_sva_bind_gpasid(struct iommu_domain *domain,
>   				struct device *dev, void __user *udata);
>   extern int iommu_sva_unbind_gpasid(struct iommu_domain *domain,
> -				struct device *dev, ioasid_t pasid);
> +				struct device *dev, void __user *udata);
> +extern int __iommu_sva_unbind_gpasid(struct iommu_domain *domain,
> +				struct device *dev, struct iommu_gpasid_bind_data *data);
>   extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);
>   extern struct iommu_domain *iommu_get_dma_domain(struct device *dev);
>   extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
> @@ -1069,7 +1071,14 @@ static inline int iommu_sva_bind_gpasid(struct iommu_domain *domain,
>   }
>   
>   static inline int iommu_sva_unbind_gpasid(struct iommu_domain *domain,
> -					   struct device *dev, int pasid)
> +					   struct device *dev, void __user *udata)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int __iommu_sva_unbind_gpasid(struct iommu_domain *domain,
> +					struct device *dev,
> +					struct iommu_gpasid_bind_data *data)
>   {
>   	return -ENODEV;
>   }
> 

Best regards,
baolu
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