Re: [PATCH V3 10/30] x86/sgx: Create utility to validate user provided offset and length

Jarkko Sakkinen
2022-04-05T06:59:29Z

On Mon, Apr 04, 2022 at 09:49:18AM -0700, Reinette Chatre wrote:
> User provided offset and length is validated when parsing the parameters
> of the SGX_IOC_ENCLAVE_ADD_PAGES ioctl(). Extract this validation
> into a utility that can be used by the SGX2 ioctl()s that will
> also provide these values.
>
> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
> ---
> No changes since V2
>
> Changes since V1:
> - New patch
>
> arch/x86/kernel/cpu/sgx/ioctl.c | 28 ++++++++++++++++++++++------
> 1 file changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
> index 83df20e3e633..f487549bccba 100644
> --- a/arch/x86/kernel/cpu/sgx/ioctl.c
> +++ b/arch/x86/kernel/cpu/sgx/ioctl.c
> @@ -372,6 +372,26 @@ static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src,
> return ret;
> }
>
> +/*
> + * Ensure user provided offset and length values are valid for
> + * an enclave.
> + */
> +static int sgx_validate_offset_length(struct sgx_encl *encl,
> + unsigned long offset,
> + unsigned long length)
> +{
> + if (!IS_ALIGNED(offset, PAGE_SIZE))
> + return -EINVAL;
> +
> + if (!length || length & (PAGE_SIZE - 1))
> + return -EINVAL;
> +
> + if (offset + length - PAGE_SIZE >= encl->size)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> /**
> * sgx_ioc_enclave_add_pages() - The handler for %SGX_IOC_ENCLAVE_ADD_PAGES
> * @encl: an enclave pointer
> @@ -425,14 +445,10 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
> if (copy_from_user(&add_arg, arg, sizeof(add_arg)))
> return -EFAULT;
>
> - if (!IS_ALIGNED(add_arg.offset, PAGE_SIZE) ||
> - !IS_ALIGNED(add_arg.src, PAGE_SIZE))
> - return -EINVAL;
> -
> - if (!add_arg.length || add_arg.length & (PAGE_SIZE - 1))
> + if (!IS_ALIGNED(add_arg.src, PAGE_SIZE))
> return -EINVAL;
>
> - if (add_arg.offset + add_arg.length - PAGE_SIZE >= encl->size)
> + if (sgx_validate_offset_length(encl, add_arg.offset, add_arg.length))
> return -EINVAL;
>
> if (copy_from_user(&secinfo, (void __user *)add_arg.secinfo,
> --
> 2.25.1
>

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko