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Date:   Fri, 14 Feb 2020 09:11:46 -0800
From:   Sean Christopherson <sean.j.christopherson@intel.com>
To:     Jethro Beekman <jethro@fortanix.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        linux-kernel@vger.kernel.org, x86@kernel.org,
        linux-sgx@vger.kernel.org, akpm@linux-foundation.org,
        dave.hansen@intel.com, nhorman@redhat.com, npmccallum@redhat.com,
        haitao.huang@intel.com, andriy.shevchenko@linux.intel.com,
        tglx@linutronix.de, kai.svahn@intel.com, bp@alien8.de,
        josh@joshtriplett.org, luto@kernel.org, kai.huang@intel.com,
        rientjes@google.com, cedric.xing@intel.com, puiterwijk@redhat.com,
        linux-security-module@vger.kernel.org,
        Haitao Huang <haitao.huang@linux.intel.com>
Subject: Re: [PATCH v26 10/22] x86/sgx: Linux Enclave Driver
Message-ID: <20200214171146.GD20690@linux.intel.com>
References: <20200209212609.7928-1-jarkko.sakkinen@linux.intel.com>
 <20200209212609.7928-11-jarkko.sakkinen@linux.intel.com>
 <d17c50a7-6900-731b-43a2-d6e49b8eb44d@fortanix.com>
 <20200213180737.GC18610@linux.intel.com>
 <a4d9a58d-6984-5894-f6c8-73f2b2b466aa@fortanix.com>
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On Fri, Feb 14, 2020 at 10:24:10AM +0100, Jethro Beekman wrote:
> On 2020-02-13 19:07, Sean Christopherson wrote:
> > On Thu, Feb 13, 2020 at 02:59:52PM +0100, Jethro Beekman wrote:
> >> On 2020-02-09 22:25, Jarkko Sakkinen wrote:
> >>> +/**
> >>> + * struct sgx_enclave_add_pages - parameter structure for the
> >>> + *                                %SGX_IOC_ENCLAVE_ADD_PAGE ioctl
> >>> + * @src:	start address for the page data
> >>> + * @offset:	starting page offset
> >>> + * @length:	length of the data (multiple of the page size)
> >>> + * @secinfo:	address for the SECINFO data
> >>> + * @flags:	page control flags
> >>> + * @count:	number of bytes added (multiple of the page size)
> >>> + */
> >>> +struct sgx_enclave_add_pages {
> >>> +	__u64	src;
> >>> +	__u64	offset;
> >>> +	__u64	length;
> >>> +	__u64	secinfo;
> >>> +	__u64	flags;
> >>> +	__u64	count;
> >>> +};
> >>
> >> Compared to the last time I looked at the patch set, this API removes the
> >> ability to measure individual pages chunks. That is not acceptable.
> > 
> > Why is it not acceptable?  E.g. what specific use case do you have that
> > _requires_ on measuring partial 4k pages of an enclave?
> 
> The use case is someone gives me an enclave and I want to load it. If I don't
> load it exactly as the enclave author specified, the enclave hash will be
> different, and it won't work.

And if our ABI says "thou shall measure in 4k chunks", then it's an invalid
enclave if its author generated MRENCLAVE using a different granularity.