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From: Andy Lutomirski <luto@kernel.org>
To: Jarkko Sakkinen <kernel.org@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	X86 ML <x86@kernel.org>,
	linux-sgx@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	LSM List <linux-security-module@vger.kernel.org>,
	Jethro Beekman <jethro@fortanix.com>,
	Darren Kenny <darren.kenny@oracle.com>,
	Andy Lutomirski <luto@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	asapek@google.com, Borislav Petkov <bp@alien8.de>,
	"Xing, Cedric" <cedric.xing@intel.com>,
	chenalexchen@google.com, Conrad Parker <conradparker@google.com>,
	cyhanish@google.com, "Huang, Haitao" <haitao.huang@intel.com>,
	"Huang, Kai" <kai.huang@intel.com>,
	"Svahn, Kai" <kai.svahn@intel.com>, Keith Moyer <kmoy@google.com>,
	Christian Ludloff <ludloff@google.com>,
	Neil Horman <nhorman@redhat.com>,
	Nathaniel McCallum <npmccallum@redhat.com>,
	Patrick Uiterwijk <puiterwijk@redhat.com>,
	David Rientjes <rientjes@google.com>,
	"Christopherson, Sean J" <sean.j.christopherson@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	yaozhangx@google.com, Mikko Ylinen <mikko.ylinen@intel.com>
Subject: Re: [PATCH v39 15/24] x86/sgx: Add SGX_IOC_ENCLAVE_PROVISION
Date: Sat, 24 Oct 2020 08:47:28 -0700
Message-ID: <CALCETrWxA6AgU8zg=npS=4NaA1_Pu9UwScEnr_Gk0wF-BOmqqQ@mail.gmail.com> (raw)
In-Reply-To: <20201024113403.GA29427@kernel.org>

On Sat, Oct 24, 2020 at 4:34 AM Jarkko Sakkinen <kernel.org@kernel.org> wrote:
>
> On Fri, Oct 23, 2020 at 07:19:05AM -0700, Dave Hansen wrote:
> > On 10/23/20 3:17 AM, Jarkko Sakkinen wrote:
> > > On Tue, Oct 20, 2020 at 02:19:26PM -0700, Dave Hansen wrote:
> > >> On 10/2/20 9:50 PM, Jarkko Sakkinen wrote:
> > >>> + * Failure to explicitly request access to a restricted attribute will cause
> > >>> + * sgx_ioc_enclave_init() to fail.  Currently, the only restricted attribute
> > >>> + * is access to the PROVISION_KEY.
> > >> Could we also justify why access is restricted, please?  Maybe:
> > >>
> > >>    Access is restricted because PROVISION_KEY is burned uniquely
> > >>    into each each processor, making it a perfect unique identifier
> > >>    with privacy and fingerprinting implications.
> > >>
> > >> Are there any other reasons for doing it this way?
> > > AFAIK, if I interperet the SDM correctl, PROVISION_KEY and
> > > PROVISION_SEALING_KEY also have random salt added, i.e. they change
> > > every boot cycle.
> > >
> > > There is "RAND = yes" on those keys in Table 40-64 of Intel SDM volume
> > > 3D :-)
> >
> > Does that mean there are no privacy implications from access to the
> > provisioning keys?  If that's true, why do we need a separate permission
> > framework for creating provisioning enclaves?
>
> As I've understood it, the key material for those keys is not even
> required in the current SGX architecture, it was used in the legacy EPID
> scheme, but the attribute itself is useful.
>
> Let's assume that we have some sort of quoting enclave Q, which guards a
> public key pair, which signs quotes of other enclaves. Let's assume we
> have an attestation server A, which will enable some capabilities [*],
> if it receives a quote signed with that public key pair.
>
> 1. E gets the report key with EGETKEY.
> 2. E constructs REPORTDATA (37.16) and TARGETINFO (37.17) structures.
>    The former describes the enclaves contents and attributes and latter
>    the target, i.e. Q in this artitificial example.
> 3. E calls EREPORT to generate a structure called REPORT MAC'd with the
>    *targets* report key. It knows, which key to usue from REPORTDATA.
> 4. The runtime will then pass this to Q.
> 5. Q will check if ATTRIBUTE.PROVISION_KEY is set. If it is, Q will
>    know that the enclave is allowed to get attested. Then it will
>    sign the report with the guarded public key pair and send it to
>    the attestation server.

I think you have this a little bit off.  AIUI E won't have
ATTRIBUTE.PROVISION_KEY set -- Q will.  Q uses the provisioning key to
convince an Intel server that it's running on a genuine Intel CPU, and
the Intel server will return a signed certificate that Q can chain off
of to generate attestations for E.

Dave, I would rephrase what you're saying a bit.  The PROVISION_KEY
attribute allows enclaves to access keys that are unique to a
processor and unchangeable.  Unlike other SGX keys, these keys are not
affected by OWNER_EPOCH changes and therefore cannot be reset.

--Andy

  reply index

Thread overview: 117+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-03  4:50 [PATCH v39 00/24] Intel SGX foundations Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 01/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-10-19 14:10   ` Dave Hansen
2020-10-19 17:49     ` Sean Christopherson
2020-10-03  4:50 ` [PATCH v39 02/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 03/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 04/24] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 05/24] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2020-10-19 14:30   ` Dave Hansen
2020-10-19 17:38     ` Sean Christopherson
2020-10-19 17:48       ` Dave Hansen
2020-10-19 17:53         ` Sean Christopherson
2020-10-19 17:58           ` Dave Hansen
2020-10-03  4:50 ` [PATCH v39 06/24] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 07/24] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 08/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-10-19  8:45   ` Jarkko Sakkinen
2020-10-19 12:39     ` Borislav Petkov
2020-10-23  9:01       ` Jarkko Sakkinen
2020-10-19 13:40     ` Dave Hansen
2020-10-23  9:03       ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 09/24] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page() Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 10/24] mm: Add 'mprotect' hook to struct vm_operations_struct Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 11/24] x86/sgx: Add SGX enclave driver Jarkko Sakkinen
2020-10-03 14:39   ` Greg KH
2020-10-04 14:32     ` Jarkko Sakkinen
2020-10-04 15:01       ` Jarkko Sakkinen
2020-10-05  9:42       ` Greg KH
2020-10-05 12:42         ` Jarkko Sakkinen
2020-10-07 18:09           ` Haitao Huang
2020-10-07 19:26             ` Greg KH
2020-10-09  6:44               ` Jarkko Sakkinen
2020-10-14 20:16                 ` Dave Hansen
2020-10-05  8:45     ` Christoph Hellwig
2020-10-05 11:42       ` Jarkko Sakkinen
2020-10-05 11:50         ` Greg KH
2020-10-05 14:23           ` Jarkko Sakkinen
2020-10-05 15:02             ` Greg KH
2020-10-05 16:40               ` Dave Hansen
2020-10-05 20:02                 ` Jarkko Sakkinen
2020-10-09  7:10     ` Pavel Machek
2020-10-09  7:21       ` Greg KH
2020-10-09  8:21         ` Pavel Machek
2020-10-03 19:54   ` Matthew Wilcox
2020-10-04 21:50     ` Jarkko Sakkinen
2020-10-04 22:02       ` Jarkko Sakkinen
2020-10-04 22:27       ` Matthew Wilcox
2020-10-04 23:41         ` Jarkko Sakkinen
2020-10-05  1:30           ` Matthew Wilcox
2020-10-05  3:06             ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE Jarkko Sakkinen
2020-10-16 17:07   ` Dave Hansen
2020-10-18  4:26     ` Jarkko Sakkinen
2020-10-19 20:21       ` Dave Hansen
2020-10-19 20:48         ` Sean Christopherson
2020-10-03  4:50 ` [PATCH v39 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen
2020-10-16 21:25   ` Dave Hansen
2020-10-18  5:03     ` Jarkko Sakkinen
2020-10-19  7:03       ` Jarkko Sakkinen
2020-10-19 20:48       ` Dave Hansen
2020-10-19 21:15         ` Sean Christopherson
2020-10-19 21:44           ` Dave Hansen
2020-10-23 10:11             ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 14/24] x86/sgx: Add SGX_IOC_ENCLAVE_INIT Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 15/24] x86/sgx: Add SGX_IOC_ENCLAVE_PROVISION Jarkko Sakkinen
2020-10-20 15:48   ` Dave Hansen
2020-10-23 10:14     ` Jarkko Sakkinen
2020-10-20 21:19   ` Dave Hansen
2020-10-23 10:17     ` Jarkko Sakkinen
2020-10-23 14:19       ` Dave Hansen
2020-10-24 11:34         ` Jarkko Sakkinen
2020-10-24 15:47           ` Andy Lutomirski [this message]
2020-10-24 20:23             ` Jarkko Sakkinen
2020-10-27 10:38               ` Dr. Greg
2020-10-23 14:23       ` Jethro Beekman
2020-10-24 11:40         ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 16/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-10-03  5:22   ` Haitao Huang
2020-10-03 13:32     ` Jarkko Sakkinen
2020-10-03 18:23       ` Haitao Huang
2020-10-04 22:39         ` Jarkko Sakkinen
2020-10-07 17:25           ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 17/24] x86/sgx: Add ptrace() support for the SGX driver Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 18/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 19/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 20/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-10-06  2:57   ` Sean Christopherson
2020-10-06  8:30     ` Jethro Beekman
2020-10-06 15:15       ` Sean Christopherson
2020-10-06 17:28         ` Jarkko Sakkinen
2020-10-06 23:21           ` Sean Christopherson
2020-10-07  0:22             ` Jarkko Sakkinen
2020-10-07  1:17               ` Sean Christopherson
2020-10-07  3:14                 ` Jarkko Sakkinen
2020-10-07  4:34                   ` Sean Christopherson
2020-10-07  7:39                     ` Jarkko Sakkinen
2020-10-07  8:04                       ` Jarkko Sakkinen
2020-10-07 15:25                       ` Sean Christopherson
2020-10-07 17:08                         ` Jarkko Sakkinen
2020-10-07 17:13                           ` Jarkko Sakkinen
2020-10-06 15:49       ` Jarkko Sakkinen
2020-10-06 15:36     ` Jarkko Sakkinen
2020-10-06 21:39     ` Jarkko Sakkinen
2020-10-07  0:23       ` Jarkko Sakkinen
2020-10-17  1:48   ` Andy Lutomirski
2020-10-17 21:02     ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 22/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-10-12 16:50   ` Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 23/24] docs: x86/sgx: Document SGX micro architecture and kernel internals Jarkko Sakkinen
2020-10-03  4:50 ` [PATCH v39 24/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2020-10-16 21:04   ` Dave Hansen
2020-10-18  4:27     ` Jarkko Sakkinen
2020-10-03 14:32 ` [PATCH v39 00/24] Intel SGX foundations Greg KH
2020-10-03 14:53   ` Jarkko Sakkinen
2020-10-15 19:06 ` Dave Hansen
2020-10-17 20:43   ` Jarkko Sakkinen

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