linux-kernel - Re: [PATCH v36 12/24] x86/sgx: Add SGX_IOC_ENCLAVE

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Date:   Sat, 29 Aug 2020 03:21:02 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     x86@...nel.org, linux-sgx@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jethro Beekman <jethro@...tanix.com>,
        Haitao Huang <haitao.huang@...ux.intel.com>,
        Chunyang Hui <sanqian.hcy@...fin.com>,
        Jordan Hand <jorhand@...ux.microsoft.com>,
        Nathaniel McCallum <npmccallum@...hat.com>,
        Seth Moore <sethmo@...gle.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Suresh Siddha <suresh.b.siddha@...el.com>,
        akpm@...ux-foundation.org, andriy.shevchenko@...ux.intel.com,
        asapek@...gle.com, cedric.xing@...el.com, chenalexchen@...gle.com,
        conradparker@...gle.com, cyhanish@...gle.com,
        dave.hansen@...el.com, haitao.huang@...el.com,
        josh@...htriplett.org, kai.huang@...el.com, kai.svahn@...el.com,
        kmoy@...gle.com, ludloff@...gle.com, luto@...nel.org,
        nhorman@...hat.com, puiterwijk@...hat.com, rientjes@...gle.com,
        tglx@...utronix.de, yaozhangx@...gle.com
Subject: Re: [PATCH v36 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE

On Thu, Aug 27, 2020 at 04:24:50PM +0300, Jarkko Sakkinen wrote:
> > > + * @arg:	userspace pointer to a struct sgx_enclave_create instance
> > > + *
> > > + * Allocate kernel data structures for a new enclave and execute ECREATE after
> > > + * verifying the correctness of the provided SECS.
> > > + *
> > > + * Note, enforcement of restricted and disallowed attributes is deferred until
> > > + * sgx_ioc_enclave_init(), only the architectural correctness of the SECS is
> > > + * checked by sgx_ioc_enclave_create().
> > 
> > From that same review:
> > 
> > "Well, I don't see that checking. Where is it?"
> > 
> > Ok, I'm going to stop here. Please go over v33's review and either
> > address *all* feedback or incorporate it into your patches if you agree
> > with it but do not silently ignore it. One of the things I very strongly
> > detest is ignored review comments.

OK, so sgx_validate_secs() is the validation of what the CPU requires
from the contents of the SECS. That is mean by "architectural
correctness".

I spotted the glitch that makes this confusing.

The change that the comment is related is

https://lore.kernel.org/linux-sgx/20200716135303.276442-16-jarkko.sakkinen@linux.intel.com/

This check in sgx_encl_init() should be relocated to this commit:

	/* Check that the required attributes have been authorized. */
	if (encl->secs_attributes & ~encl->allowed_attributes)
		return -EACCES;

It is the "enforcement of restricted and disallowed attributes" part.

Does this make sense to you?

> > -- 
> > Regards/Gruss,
> >     Boris.

/Jarkko