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Date: Thu, 13 Aug 2020 09:25:12 +0000
From: "Liu, Yi L" <yi.l.liu@...el.com>
To: Auger Eric <eric.auger@...hat.com>,
Jacob Pan <jacob.jun.pan@...ux.intel.com>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
LKML <linux-kernel@...r.kernel.org>,
Joerg Roedel <joro@...tes.org>,
Alex Williamson <alex.williamson@...hat.com>
CC: Lu Baolu <baolu.lu@...ux.intel.com>,
David Woodhouse <dwmw2@...radead.org>,
"Tian, Kevin" <kevin.tian@...el.com>,
"Raj, Ashok" <ashok.raj@...el.com>,
Christoph Hellwig <hch@...radead.org>,
"Jean-Philippe Brucker" <jean-philippe@...aro.com>,
Jonathan Corbet <corbet@....net>
Subject: RE: [PATCH v7 6/7] iommu/uapi: Handle data and argsz filled by users
Hi Eric,
> From: Auger Eric <eric.auger@...hat.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.liu@intel.com/
https://lore.kernel.org/kvm/1595917664-33276-12-git-send-email-yi.l.liu@intel.com/
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@...el.com>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.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@...hat.com>
>
> Thanks
>
> Eric
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