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Subject: Re: [PATCH v7 6/7] iommu/uapi: Handle data and argsz filled by users
To:     "Liu, Yi L" <yi.l.liu@intel.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Joerg Roedel <joro@8bytes.org>,
        Alex Williamson <alex.williamson@redhat.com>
Cc:     Lu Baolu <baolu.lu@linux.intel.com>,
        David Woodhouse <dwmw2@infradead.org>,
        "Tian, Kevin" <kevin.tian@intel.com>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        Christoph Hellwig <hch@infradead.org>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>,
        Jonathan Corbet <corbet@lwn.net>
References: <1596068467-49322-1-git-send-email-jacob.jun.pan@linux.intel.com>
 <1596068467-49322-7-git-send-email-jacob.jun.pan@linux.intel.com>
 <ee61f1d1-f581-e35f-c50a-80e10b1dd06c@redhat.com>
 <DM5PR11MB14358D98D56B22307F712D47C3430@DM5PR11MB1435.namprd11.prod.outlook.com>
 <55dc3e4c-2717-2c96-d676-708b94e8cf1f@redhat.com>
 <DM5PR11MB1435DFD22AB25E7471D66E58C3430@DM5PR11MB1435.namprd11.prod.outlook.com>
From:   Auger Eric <eric.auger@redhat.com>
Message-ID: <e282d00f-94f7-d5b5-4a69-0c25124cab6a@redhat.com>
Date:   Thu, 13 Aug 2020 12:03:56 +0200
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Hi Yi,

On 8/13/20 11:38 AM, Liu, Yi L wrote:
>> From: Auger Eric <eric.auger@redhat.com>
>> Sent: Thursday, August 13, 2020 5:31 PM
>>
>> Hi Yi,
>>
>> On 8/13/20 11:25 AM, Liu, Yi L wrote:
>>> Hi Eric,
>>>
>>>
>>>> From: Auger Eric <eric.auger@redhat.com>
>>>> Sent: Thursday, August 13, 2020 5:12 PM
>>>>
>>>> Hi Jacob,
>>>>
>>>> On 7/30/20 2:21 AM, Jacob Pan wrote:
>>>>> 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.
>>>> This is just done for a single function, ie. iommu_sva_unbind_gpasid.
>>>>
>>>> If I am not wrong there is no user of this latter after applying the
>>>> whole series? If correct you may remove it at this stage?
>>>
>>> the user of this function is in vfio. And it is the same with
>>> iommu_uapi_sva_bind/unbind_gpasid() and iommu_uapi_cache_invalidate().
>>>
>>> https://lore.kernel.org/kvm/1595917664-33276-11-git-send-email-yi.l.li
>>> u@intel.com/
>>> https://lore.kernel.org/kvm/1595917664-33276-12-git-send-email-yi.l.li
>>> u@intel.com/
>> Yep I know ;-) But this series mostly deals with iommu uapi rework.
>> That's not a big deal though.
> 
> I see. btw. it's great if you can take a look on vfio v6 to see if your comments
> are well addressed. :-)

Yep I will do asap

Thanks

Eric
> 
> Regards,
> Yi Liu
> 
>> Thanks
>>
>> Eric
>>>
>>> Regards,
>>> Yi Liu
>>>
>>>>>
>>>>> 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: Liu Yi L <yi.l.liu@intel.com>
>>>>> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
>>>>> ---
>>>>>  drivers/iommu/iommu.c | 201
>>>> ++++++++++++++++++++++++++++++++++++++++++++++++--
>>>>>  include/linux/iommu.h |  28 ++++---
>>>>>  2 files changed, 212 insertions(+), 17 deletions(-)
>>>>>
>>>>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index
>>>>> 3a913ce94a3d..1ee55c4b3a3a 100644
>>>>> --- a/drivers/iommu/iommu.c
>>>>> +++ b/drivers/iommu/iommu.c
>>>>> @@ -1950,33 +1950,218 @@ int iommu_attach_device(struct iommu_domain
>>>> *domain, struct device *dev)
>>>>>  }
>>>>>  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 = 0;
>>>>> +
>>>>>  	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 variable size union is mandatory */
>>>>> +	if (inv_info.argsz < minsz)
>>>>> +		return -EINVAL;
>>>>> +
>>>>> +	/* PASID and address granu require additional info beyond minsz */
>>>>> +	if (inv_info.argsz == minsz &&
>>>>> +	    ((inv_info.granularity == IOMMU_INV_GRANU_PASID) ||
>>>>> +		    (inv_info.granularity == IOMMU_INV_GRANU_ADDR)))
>>>>> +		return -EINVAL;
>>>>> +
>>>>> +	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 variable size union is 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,
>>>>> -				 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); }
>>>>> +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);
>>>>>  }
>>>>>  EXPORT_SYMBOL_GPL(iommu_uapi_sva_unbind_gpasid);
>>>>>
>>>>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h index
>>>>> 2dcc1a33f6dc..4a02c9e09048 100644
>>>>> --- a/include/linux/iommu.h
>>>>> +++ b/include/linux/iommu.h
>>>>> @@ -432,11 +432,14 @@ 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, 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, @@ -1054,22 +1057,29 @@ 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,
>>>>> -					      struct device *dev,
>>>>> -					      struct iommu_cache_invalidate_info
>>>> *inv_info)
>>>>> +static inline int
>>>>> +iommu_uapi_cache_invalidate(struct iommu_domain *domain,
>>>>> +			    struct device *dev,
>>>>> +			    struct iommu_cache_invalidate_info *inv_info)
>>>>>  {
>>>>>  	return -ENODEV;
>>>>>  }
>>>>>
>>>>>  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,
>>>>> +					  struct iommu_gpasid_bind_data *data)
>>>>>  {
>>>>>  	return -ENODEV;
>>>>>  }
>>>>>
>>>> Otherwise looks good to me
>>>> Reviewed-by: Eric Auger <eric.auger@redhat.com>
>>>>
>>>> Thanks
>>>>
>>>> Eric
>>>
>