Commit d9057381 authored by Jacob Pan's avatar Jacob Pan Committed by Joerg Roedel
Browse files

iommu/uapi: Handle data and argsz filled by users 



IOMMU user APIs are responsible for processing user data. This patch
changes the interface such that user pointers can be passed into IOMMU
code directly. Separate kernel APIs without user pointers are introduced
for in-kernel users of the UAPI functionality.

IOMMU UAPI data has a user filled argsz field which indicates the data
length of the structure. 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, resulting in possible argsz increase.
Backward compatibility is ensured based on size and flags (or
the functional equivalent fields) checking.

This patch adds sanity checks in the IOMMU layer. In addition to argsz,
reserved/unused fields in padding, flags, and version are also checked.
Details are documented in Documentation/userspace-api/iommu.rst

Signed-off-by: default avatarLiu Yi L <yi.l.liu@intel.com>
Signed-off-by: default avatarJacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: default avatarJean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: default avatarEric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/1601051567-54787-6-git-send-email-jacob.jun.pan@linux.intel.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 23cc3493

drivers/iommu/iommu.c

+187 −7
Original line number Diff line number Diff line
@@ -1961,27 +1961,190 @@ out_unlock: 
}

EXPORT_SYMBOL_GPL(iommu_attach_device);



/*

 * Check flags and other user provided data for valid combinations. We also

 * make sure no reserved fields or unused flags are set. This is to ensure

 * not breaking userspace in the future when these fields or flags are used.

 */

static int iommu_check_cache_invl_data(struct iommu_cache_invalidate_info *info)

{

	u32 mask;

	int i;



	if (info->version != IOMMU_CACHE_INVALIDATE_INFO_VERSION_1)

		return -EINVAL;



	mask = (1 << IOMMU_CACHE_INV_TYPE_NR) - 1;

	if (info->cache & ~mask)

		return -EINVAL;



	if (info->granularity >= IOMMU_INV_GRANU_NR)

		return -EINVAL;



	switch (info->granularity) {

	case IOMMU_INV_GRANU_ADDR:

		if (info->cache & IOMMU_CACHE_INV_TYPE_PASID)

			return -EINVAL;



		mask = IOMMU_INV_ADDR_FLAGS_PASID |

			IOMMU_INV_ADDR_FLAGS_ARCHID |

			IOMMU_INV_ADDR_FLAGS_LEAF;



		if (info->granu.addr_info.flags & ~mask)

			return -EINVAL;

		break;

	case IOMMU_INV_GRANU_PASID:

		mask = IOMMU_INV_PASID_FLAGS_PASID |

			IOMMU_INV_PASID_FLAGS_ARCHID;

		if (info->granu.pasid_info.flags & ~mask)

			return -EINVAL;



		break;

	case IOMMU_INV_GRANU_DOMAIN:

		if (info->cache & IOMMU_CACHE_INV_TYPE_DEV_IOTLB)

			return -EINVAL;

		break;

	default:

		return -EINVAL;

	}



	/* Check reserved padding fields */

	for (i = 0; i < sizeof(info->padding); i++) {

		if (info->padding[i])

			return -EINVAL;

	}



	return 0;

}



int iommu_uapi_cache_invalidate(struct iommu_domain *domain, struct device *dev,

				struct iommu_cache_invalidate_info *inv_info)

				void __user *uinfo)

{

	struct iommu_cache_invalidate_info inv_info = { 0 };

	u32 minsz;

	int ret;



	if (unlikely(!domain->ops->cache_invalidate))

		return -ENODEV;



	return domain->ops->cache_invalidate(domain, dev, inv_info);

	/*

	 * No new spaces can be added before the variable sized union, the

	 * minimum size is the offset to the union.

	 */

	minsz = offsetof(struct iommu_cache_invalidate_info, granu);



	/* Copy minsz from user to get flags and argsz */

	if (copy_from_user(&inv_info, uinfo, minsz))

		return -EFAULT;



	/* Fields before the variable size union are mandatory */

	if (inv_info.argsz < minsz)

		return -EINVAL;



	/* PASID and address granu require additional info beyond minsz */

	if (inv_info.granularity == IOMMU_INV_GRANU_PASID &&

	    inv_info.argsz < offsetofend(struct iommu_cache_invalidate_info, granu.pasid_info))

		return -EINVAL;



	if (inv_info.granularity == IOMMU_INV_GRANU_ADDR &&

	    inv_info.argsz < offsetofend(struct iommu_cache_invalidate_info, granu.addr_info))

		return -EINVAL;



	/*

	 * User might be using a newer UAPI header which has a larger data

	 * size, we shall support the existing flags within the current

	 * size. Copy the remaining user data _after_ minsz but not more

	 * than the current kernel supported size.

	 */

	if (copy_from_user((void *)&inv_info + minsz, uinfo + minsz,

			   min_t(u32, inv_info.argsz, sizeof(inv_info)) - minsz))

		return -EFAULT;



	/* Now the argsz is validated, check the content */

	ret = iommu_check_cache_invl_data(&inv_info);

	if (ret)

		return ret;



	return domain->ops->cache_invalidate(domain, dev, &inv_info);

}

EXPORT_SYMBOL_GPL(iommu_uapi_cache_invalidate);



int iommu_uapi_sva_bind_gpasid(struct iommu_domain *domain,

			       struct device *dev, struct iommu_gpasid_bind_data *data)

static int iommu_check_bind_data(struct iommu_gpasid_bind_data *data)

{

	u32 mask;

	int i;



	if (data->version != IOMMU_GPASID_BIND_VERSION_1)

		return -EINVAL;



	/* Check the range of supported formats */

	if (data->format >= IOMMU_PASID_FORMAT_LAST)

		return -EINVAL;



	/* Check all flags */

	mask = IOMMU_SVA_GPASID_VAL;

	if (data->flags & ~mask)

		return -EINVAL;



	/* Check reserved padding fields */

	for (i = 0; i < sizeof(data->padding); i++) {

		if (data->padding[i])

			return -EINVAL;

	}



	return 0;

}



static int iommu_sva_prepare_bind_data(void __user *udata,

				       struct iommu_gpasid_bind_data *data)

{

	u32 minsz;



	/*

	 * No new spaces can be added before the variable sized union, the

	 * minimum size is the offset to the union.

	 */

	minsz = offsetof(struct iommu_gpasid_bind_data, vendor);



	/* Copy minsz from user to get flags and argsz */

	if (copy_from_user(data, udata, minsz))

		return -EFAULT;



	/* Fields before the variable size union are mandatory */

	if (data->argsz < minsz)

		return -EINVAL;

	/*

	 * User might be using a newer UAPI header, we shall let IOMMU vendor

	 * driver decide on what size it needs. Since the guest PASID bind data

	 * can be vendor specific, larger argsz could be the result of extension

	 * for one vendor but it should not affect another vendor.

	 * Copy the remaining user data _after_ minsz

	 */

	if (copy_from_user((void *)data + minsz, udata + minsz,

			   min_t(u32, data->argsz, sizeof(*data)) - minsz))

		return -EFAULT;



	return iommu_check_bind_data(data);

}



int iommu_uapi_sva_bind_gpasid(struct iommu_domain *domain, struct device *dev,

			       void __user *udata)

{

	struct iommu_gpasid_bind_data data = { 0 };

	int ret;



	if (unlikely(!domain->ops->sva_bind_gpasid))

		return -ENODEV;



	return domain->ops->sva_bind_gpasid(domain, dev, data);

	ret = iommu_sva_prepare_bind_data(udata, &data);

	if (ret)

		return ret;



	return domain->ops->sva_bind_gpasid(domain, dev, &data);

}

EXPORT_SYMBOL_GPL(iommu_uapi_sva_bind_gpasid);



int iommu_uapi_sva_unbind_gpasid(struct iommu_domain *domain, struct device *dev,

int iommu_sva_unbind_gpasid(struct iommu_domain *domain, struct device *dev,

			     ioasid_t pasid)

{

	if (unlikely(!domain->ops->sva_unbind_gpasid))
@@ -1989,6 +2152,23 @@ int iommu_uapi_sva_unbind_gpasid(struct iommu_domain *domain, struct device *dev 


	return domain->ops->sva_unbind_gpasid(dev, pasid);

}

EXPORT_SYMBOL_GPL(iommu_sva_unbind_gpasid);



int iommu_uapi_sva_unbind_gpasid(struct iommu_domain *domain, struct device *dev,

				 void __user *udata)

{

	struct iommu_gpasid_bind_data data = { 0 };

	int ret;



	if (unlikely(!domain->ops->sva_bind_gpasid))

		return -ENODEV;



	ret = iommu_sva_prepare_bind_data(udata, &data);

	if (ret)

		return ret;



	return iommu_sva_unbind_gpasid(domain, dev, data.hpasid);

}

EXPORT_SYMBOL_GPL(iommu_uapi_sva_unbind_gpasid);



static void __iommu_detach_device(struct iommu_domain *domain,

include/linux/iommu.h

+19 −9
Original line number Diff line number Diff line
@@ -426,10 +426,13 @@ extern void iommu_detach_device(struct iommu_domain *domain, 
				struct device *dev);

extern int iommu_uapi_cache_invalidate(struct iommu_domain *domain,

				       struct device *dev,

				       struct iommu_cache_invalidate_info *inv_info);

				       void __user *uinfo);



extern int iommu_uapi_sva_bind_gpasid(struct iommu_domain *domain,

				      struct device *dev, struct iommu_gpasid_bind_data *data);

				      struct device *dev, void __user *udata);

extern int iommu_uapi_sva_unbind_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);

extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);

extern struct iommu_domain *iommu_get_dma_domain(struct device *dev);
@@ -1032,7 +1035,8 @@ static inline int iommu_sva_get_pasid(struct iommu_sva *handle) 
	return IOMMU_PASID_INVALID;

}



static inline int iommu_uapi_cache_invalidate(struct iommu_domain *domain,

static inline int

iommu_uapi_cache_invalidate(struct iommu_domain *domain,

			    struct device *dev,

			    struct iommu_cache_invalidate_info *inv_info)

{
@@ -1040,14 +1044,20 @@ static inline int iommu_uapi_cache_invalidate(struct iommu_domain *domain, 
}



static inline int iommu_uapi_sva_bind_gpasid(struct iommu_domain *domain,

					     struct device *dev,

					     struct iommu_gpasid_bind_data *data)

					     struct device *dev, void __user *udata)

{

	return -ENODEV;

}



static inline int iommu_uapi_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,

					  ioasid_t pasid)

{

	return -ENODEV;

}

include/uapi/linux/iommu.h

+1 −0
Original line number Diff line number Diff line
@@ -322,6 +322,7 @@ struct iommu_gpasid_bind_data { 
#define IOMMU_GPASID_BIND_VERSION_1	1

	__u32 version;

#define IOMMU_PASID_FORMAT_INTEL_VTD	1

#define IOMMU_PASID_FORMAT_LAST		2

	__u32 format;

	__u32 addr_width;

#define IOMMU_SVA_GPASID_VAL	(1 << 0) /* guest PASID valid */

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