On Thu, May 16, 2019 at 08:07:05AM +0300, Jarkko Sakkinen wrote:
> On Wed, May 15, 2019 at 07:27:02AM -0700, Andy Lutomirski wrote:
> >
> > > On May 15, 2019, at 4:00 AM, Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> wrote:
> > >
> > >> On Wed, May 15, 2019 at 01:35:31PM +0300, Jarkko Sakkinen wrote:
> > >> This brings me to an open question in Andy's model: lets say that we
> > >> change the source for SIGSTRUCT from memory address to fd. How can the
> > >> policy prevent the use not creating a file containing a SIGSTRUCT and
> > >> passing fd of that to the EINIT ioctl?
> > >
> >
> > The policy will presumably check the label on the file that the fd points to.
>
> Right (checked SELinux documentation).
>
> Got one idea from this. Right now creation and initialization does not
> require any VMAs to be created (since v20). Requiring to map a VMA for
> copying the data would bring in my opinion a glitch to this model that
> we have done effort to build up.
>
> What if we similarly change EADD ioctl in a way that it'd take an fd
> and an offset? This way we can enforce policy to the source where the
> enclave data is loaded from. On the other hand, loading SIGSTRUCT from
> fd enforces a legit structure for the enclave.
>
> This would still allow to construct enclaves in VMA independent way.
The API would turn into this:
/**
* struct sgx_enclave_add_page - parameter structure for the
* %SGX_IOC_ENCLAVE_ADD_PAGE ioctl
* @fd: file containing the page data
* @offset: offset in the file containing the page data
* @secinfo: address for the SECINFO data
* @mrmask: bitmask for the measured 256 byte chunks
*/
struct sgx_enclave_add_page {
__u64 fd;
__u64 offset;
__u64 secinfo;
__u16 mrmask;
} __attribute__((__packed__));
/**
* struct sgx_enclave_init - parameter structure for the
* %SGX_IOC_ENCLAVE_INIT ioctl
* @fd: file containing the sigstruct
* @offset: offset in the file containing the sigstruct
*/
struct sgx_enclave_init {
__u64 fd;
__u64 offset;
};
/Jarkko
