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From: Dave Hansen <dave.hansen@intel.com>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org,
	intel-sgx-kernel-dev@lists.01.org,
	platform-driver-x86@vger.kernel.org
Subject: Re: [intel-sgx-kernel-dev] [PATCH v4 06/12] fs/pipe.c: export create_pipe_files() and replace_fd()
Date: Tue, 24 Oct 2017 08:10:37 -0700	[thread overview]
Message-ID: <a42edcbb-b80c-ea2a-78c3-2d043457cc63@intel.com> (raw)
In-Reply-To: <20171024133913.jpyxdy2xymjuyd7n@linux.intel.com>

On 10/24/2017 06:39 AM, Jarkko Sakkinen wrote:
> On Sun, Oct 22, 2017 at 10:09:16PM -0700, Dave Hansen wrote:
>> On 10/22/2017 07:55 PM, Jarkko Sakkinen wrote:
>>> On Fri, Oct 20, 2017 at 07:32:42AM -0700, Dave Hansen wrote:
>>>> I've always been curious, and the changelog and thread are curiously
>>>> oblique on this topic: what the heck does this driver use pipes *for*?
>>> For communication with the process hosting the launch enclave.
>>
>> But, why pipes?  Why does the kernel have to be the one setting these
>> up?  Why is this communication necessary in the first place?
> 
> 1. Kernel gives a SIGSTRUCT instance to the LE hosting process.
> 2. LE hosting process gives the SIGSTRUCT to the LE.
> 3. LE gives EINITTOKEN to the LE hosting process after generating it.
> 4. LE hosting process gives it back to the kernel.

Let me see if I can turn that into english.  Enclaves are all rooted in
a chain of trust.  To run an enclave, you need to have that enclave
blessed by the hardware or blessed by a "launch enclave" (aka. LE).  The
LE is hosted inside a normal process, just as the enclave we are trying
to launch is hosted in a normal process.  In order to launch a normal
enclave, we talk to the LE which gives us a token that allows us to
start a new enclave.

These pipes are the mechanism that we use so that the process starting
the new process can talk to the launch enclave.

How's that?

> I do not understand why using pipes for this is such a big crime to
> implement this. I do have an alternative proposal if it is.

The crime is not writing a good changelog to explain what you are doing
and why you need to do it.

> What I can do is to use one struct shmem_file instance and assing it
> to a file descriptor instead. Kernel and LE hosting process can then
> use that for communication.

Could you explain a bit about what kind of information needs to go back
and forth?  Is it just "give me a launch key" followed by "here you go",
or is it more complicated than that?

  reply	other threads:[~2017-10-24 15:11 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-16 19:18 [PATCH v4 00/12] Intel(R) SGX Driver Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 01/12] intel_sgx: updated MAINTAINERS Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 02/12] x86: add SGX definition to cpufeature Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 03/12] x86: define the feature control MSR's SGX enable bit Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 04/12] x86: define the feature control MSR's SGX launch control bit Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 05/12] x86: add SGX MSRs to msr-index.h Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 06/12] fs/pipe.c: export create_pipe_files() and replace_fd() Jarkko Sakkinen
2017-10-19  8:06   ` Christoph Hellwig
2017-10-19 12:36     ` Jarkko Sakkinen
2017-10-19 14:55       ` Christoph Hellwig
2017-10-20 10:14         ` Jarkko Sakkinen
2017-10-20 14:32           ` [intel-sgx-kernel-dev] " Dave Hansen
2017-10-23  2:55             ` Jarkko Sakkinen
2017-10-23  5:09               ` Dave Hansen
2017-10-24 13:39                 ` Jarkko Sakkinen
2017-10-24 15:10                   ` Dave Hansen [this message]
2017-10-24 16:40                     ` Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 07/12] intel_sgx: driver for Intel Software Guard Extensions Jarkko Sakkinen
2017-10-18 15:21   ` Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 08/12] intel_sgx: ptrace() support Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 09/12] intel_sgx: driver documentation Jarkko Sakkinen
2017-10-17  0:51   ` Randy Dunlap
2017-10-18 14:25     ` Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 10/12] intel_sgx: in-kernel launch enclave Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 11/12] intel_sgx: glue code for in-kernel LE Jarkko Sakkinen
2017-10-16 19:18 ` [PATCH v4 12/12] intel_sgx: update IA32_SGXLEPUBKEYHASH* MSRs Jarkko Sakkinen

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