Messages in this thread Patch in this message | | | Date | Tue, 28 Jul 2020 13:19:44 -0600 | From | Alex Williamson <> | Subject | Re: [PATCH v6 5/6] iommu/uapi: Handle data and argsz filled by users |
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On Thu, 23 Jul 2020 10:25:39 -0700 Jacob Pan <jacob.jun.pan@linux.intel.com> 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. > > 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 | 202 ++++++++++++++++++++++++++++++++++++++++++++++++-- > include/linux/iommu.h | 28 ++++--- > 2 files changed, 213 insertions(+), 17 deletions(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 3a913ce94a3d..1ce2a61058c6 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -1950,33 +1950,219 @@ 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 < 6; i++) {
We could use sizeof(info->padding) here to avoid future issues relative to the number of padding bytes.
> + 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(inv_info.argsz, (u32)sizeof(inv_info)) - minsz))
Could use min_t() to cast both args to the specified type.
> + 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 all supported format, for now just VT-d */ > + mask = IOMMU_PASID_FORMAT_INTEL_VTD; > + if (data->format & ~mask)
data->format is not a bitmask though, it's an index, right? Should defined formats be put into an enum with a last entry place holder for this code to test against? If we end up with holes in the enum, I guess we'd need to use special cases, ex:
switch (data->format) { case IOMMU_PASID_FORMAT_DEPRECATED0: return -EINVAL; case 0 ... IOMMU_PASID_FORMAT_LAST: break; default: return -EINVAL; }
It seems strange and error prone anyway for common code to check against a specific vendor format here.
> + return -EINVAL; > + > + /* Check all flags */ > + mask = IOMMU_SVA_GPASID_VAL; > + if (data->flags & ~mask) > + return -EINVAL; > + > + /* Check reserved padding fields */ > + for (i = 0; i < 8; i++) {
sizeof(data->padding)
> + 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(data->argsz, (u32)sizeof(*data)) - minsz))
min_t() here too. Thanks,
Alex
> + 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; > }
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