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From: Casey Schaufler <casey@schaufler-ca.com>
To: "Dr. Greg" <greg@enjellic.com>, casey@schaufler-ca.com
Cc: "Xing, Cedric" <cedric.xing@intel.com>,
	Stephen Smalley <stephen.smalley@gmail.com>,
	"linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>,
	"linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>,
	"selinux@vger.kernel.org" <selinux@vger.kernel.org>,
	"Schaufler, Casey" <casey.schaufler@intel.com>,
	"jmorris@namei.org" <jmorris@namei.org>,
	"luto@kernel.org" <luto@kernel.org>,
	"jethro@fortanix.com" <jethro@fortanix.com>,
	"sds@tycho.nsa.gov" <sds@tycho.nsa.gov>,
	"jarkko.sakkinen@linux.intel.com"
	<jarkko.sakkinen@linux.intel.com>,
	"Christopherson, Sean J" <sean.j.christopherson@intel.com>
Subject: Re: [RFC PATCH v2 1/3] x86/sgx: Add SGX specific LSM hooks
Date: Wed, 3 Jul 2019 08:32:10 -0700
Message-ID: <012fc47d-4e9d-3398-0d9d-d9298a758c8d@schaufler-ca.com> (raw)
In-Reply-To: <20190703094651.GA29601@wind.enjellic.com>

On 7/3/2019 2:46 AM, Dr. Greg wrote:
> On Tue, Jul 02, 2019 at 08:44:40AM -0700, Casey Schaufler wrote:
>
> Good morning, I hope this note finds the week going well for everyone.
>
>> On 7/2/2019 12:42 AM, Xing, Cedric wrote:
>>> ...
>>> Guess this discussion will never end if we don't get into
>>> code. Guess it'd be more productive to talk over phone then come back
>>> to this thread with a conclusion. Will that be ok with you?
>> I don't think that a phone call is going to help. Talking code
>> issues tends to muddle them in my brain. If you can give me a few
>> days I will propose a rough version of how I think your code should
>> be integrated into the LSM environment. I'm spending more time
>> trying (unsuccessfully :( ) to discribe the issues in English than
>> it will probably take in C.
> While Casey is off writing his rosetta stone,

I'd hardly call it that. More of an effort to round the
corners on the square peg. And Cedric has some ideas on
how to approach that.

> let me suggest that the
> most important thing we need to do is to take a little time, step back
> and look at the big picture with respect to what we are trying to
> accomplish and if we are going about it in a way that makes any sense
> from an engineering perspective.
>
> This conversation shouldn't be about SGX, it should be about the best
> way for the kernel/LSM to discipline a Trusted Execution Environment
> (TEE).  As I have noted previously, a TEE is a 'blackbox' that, by
> design, is intended to allow execution of code and processing of data
> in a manner that is resistant to manipulation or inspection by
> untrusted userspace, the kernel and/or the hardware itself.
>
> Given that fact, if we are to be intellectually honest, we need to ask
> ourselves how effective we believe we can be in controlling any TEE
> with kernel based mechanisms.  This is particularly the case if the
> author of any code running in the TEE has adversarial intent.
>
> Here is the list of controls that we believe an LSM can, effectively,
> implement against a TEE:
>
> 1.) Code provenance and origin.
>
> 2.) Cryptographic verification of dynamically executable content.
>
> 2.) The ability of a TEE to implement anonymous executable content.
>
> If people are in agreement with this concept, it is difficult to
> understand why we should be implementing complex state machines and
> the like, whether it is in the driver or the LSM.  Security code has
> to be measured with a metric of effectiveness, otherwise we are
> engaging in security theater.
>
> I believe that if we were using this lens, we would already have a
> mainline SGX driver, since we seem to have most of the needed LSM
> infrastructure and any additional functionality would be a straight
> forward implementation.  Most importantly, the infrastructure would
> not be SGX specific, which would seem to be a desirable political
> concept.

Generality introduced in the absence of multiple instances
often results in unnecessary complexity, unused interfaces
and feature compromise. Guessing what other TEE systems might
do, and constraining SGX to those models (or the other way around)
is a well established road to ruin. The LSM infrastructure is
a fine example. For the first ten years the "general" mechanism
had a single user. I'd say to hold off on the general until there
is more experience with the specific. It's easier to construct
a general mechanism around things that work than to fit things
that need to work into some preconceived notion of generality. 

>
> If we are not willing to engage in this discussion we are going to end
> up with a quasi-technology specific solution that isn't implementing
> any relevant security guarantees.
>
> FWIW, we wouldn't even be having this, now lengthy discussion, if I
> wouldn't have aggressively advocated, starting last November, that an
> SGX driver needed some form of execution control if there was a desire
> for the technology to not pose a security risk to the platform.  So
> humor me a little bit.... :-)
>
> Best wishes for a productive remainder of the week to everyone.
>
> Dr. Greg
>
> As always,
> Dr. Greg Wettstein, Ph.D, Worker
> IDfusion, LLC
> 4206 N. 19th Ave.           Implementing measured information privacy
> Fargo, ND  58102            and integrity architectures.
> PH: 701-281-1686
> FAX: 701-281-3949           EMAIL: greg@idfusion.net
> ------------------------------------------------------------------------------
> "... remember that innovation is saying 'no' to 1000 things."


  reply index

Thread overview: 156+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-19 22:23 [RFC PATCH v4 00/12] security: x86/sgx: SGX vs. LSM Sean Christopherson
2019-06-19 22:23 ` [RFC PATCH v4 01/12] x86/sgx: Use mmu_notifier.release() instead of per-vma refcounting Sean Christopherson
2019-06-20 21:03   ` Jarkko Sakkinen
2019-07-08 14:57     ` Sean Christopherson
2019-07-09 16:18       ` Jarkko Sakkinen
2019-06-19 22:23 ` [RFC PATCH v4 02/12] x86/sgx: Do not naturally align MAP_FIXED address Sean Christopherson
2019-06-20 21:09   ` Jarkko Sakkinen
2019-06-20 22:09     ` Jarkko Sakkinen
2019-06-19 22:23 ` [RFC PATCH v4 03/12] selftests: x86/sgx: Mark the enclave loader as not needing an exec stack Sean Christopherson
2019-06-20 21:17   ` Jarkko Sakkinen
2019-06-19 22:23 ` [RFC PATCH v4 04/12] x86/sgx: Require userspace to define enclave pages' protection bits Sean Christopherson
2019-06-21  1:07   ` Jarkko Sakkinen
2019-06-21  1:16     ` Jarkko Sakkinen
2019-06-21 16:42   ` Xing, Cedric
2019-07-08 16:34     ` Sean Christopherson
2019-07-08 17:29       ` Xing, Cedric
2019-07-01 18:00   ` Andy Lutomirski
2019-07-01 19:22     ` Xing, Cedric
2019-06-19 22:23 ` [RFC PATCH v4 05/12] x86/sgx: Enforce noexec filesystem restriction for enclaves Sean Christopherson
2019-06-21  1:26   ` Jarkko Sakkinen
2019-07-07 19:03     ` Sean Christopherson
2019-06-19 22:23 ` [RFC PATCH v4 06/12] mm: Introduce vm_ops->may_mprotect() Sean Christopherson
2019-06-21  1:35   ` Jarkko Sakkinen
2019-06-19 22:23 ` [RFC PATCH v4 07/12] LSM: x86/sgx: Introduce ->enclave_map() hook for Intel SGX Sean Christopherson
2019-06-21  2:28   ` Jarkko Sakkinen
2019-06-21 16:54   ` Xing, Cedric
2019-06-25 20:48     ` Stephen Smalley
2019-06-27 20:29       ` Xing, Cedric
2019-07-07 18:01         ` Sean Christopherson
2019-06-19 22:23 ` [RFC PATCH v4 08/12] security/selinux: Require SGX_MAPWX to map enclave page WX Sean Christopherson
2019-06-21 17:09   ` Xing, Cedric
2019-06-25 21:05     ` Stephen Smalley
2019-06-27 20:26       ` Xing, Cedric
2019-06-25 20:19   ` Stephen Smalley
2019-06-26 12:49     ` Dr. Greg
2019-06-19 22:23 ` [RFC PATCH v4 09/12] LSM: x86/sgx: Introduce ->enclave_load() hook for Intel SGX Sean Christopherson
2019-06-21 17:05   ` Xing, Cedric
2019-06-25 21:01     ` Stephen Smalley
2019-06-25 21:49       ` Stephen Smalley
2019-06-27 19:38         ` Xing, Cedric
2019-06-19 22:23 ` [RFC PATCH v4 10/12] security/selinux: Add enclave_load() implementation Sean Christopherson
2019-06-21 21:22   ` Xing, Cedric
2019-06-25 21:09     ` Stephen Smalley
2019-06-27 20:19       ` Xing, Cedric
2019-06-28 16:16         ` Stephen Smalley
2019-06-28 21:20           ` Xing, Cedric
2019-06-29  1:15             ` Stephen Smalley
2019-07-01 18:14               ` Xing, Cedric
2019-06-29 23:41       ` Andy Lutomirski
2019-07-01 17:46         ` Xing, Cedric
2019-07-01 17:53           ` Andy Lutomirski
2019-07-01 18:54             ` Xing, Cedric
2019-07-01 19:03               ` Xing, Cedric
2019-07-01 19:32               ` Andy Lutomirski
2019-07-01 20:03                 ` Xing, Cedric
2019-07-07 18:46                   ` Sean Christopherson
2019-06-25 20:34   ` Stephen Smalley
2019-06-19 22:24 ` [RFC PATCH v4 11/12] security/apparmor: " Sean Christopherson
2019-06-19 22:24 ` [RFC PATCH v4 12/12] LSM: x86/sgx: Show line of sight to LSM support SGX2's EAUG Sean Christopherson
2019-06-21 17:18   ` Xing, Cedric
2019-07-08 14:34     ` Sean Christopherson
2019-06-21  1:32 ` [RFC PATCH v4 00/12] security: x86/sgx: SGX vs. LSM Jarkko Sakkinen
2019-06-27 18:56 ` [RFC PATCH v2 0/3] security/x86/sgx: SGX specific LSM hooks Cedric Xing
2019-07-03 23:16   ` Jarkko Sakkinen
2019-07-03 23:22     ` Jarkko Sakkinen
2019-07-03 23:23       ` Jarkko Sakkinen
2019-07-06  5:04     ` Xing, Cedric
2019-07-08 14:46       ` Jarkko Sakkinen
2019-07-07 23:41   ` [RFC PATCH v3 0/4] " Cedric Xing
2019-07-08 15:55     ` Sean Christopherson
2019-07-08 17:49       ` Xing, Cedric
2019-07-08 18:49         ` Sean Christopherson
2019-07-08 22:26           ` Xing, Cedric
2019-07-07 23:41   ` [RFC PATCH v3 1/4] x86/sgx: Add " Cedric Xing
2019-07-07 23:41   ` [RFC PATCH v3 2/4] x86/64: Call LSM hooks from SGX subsystem/module Cedric Xing
2019-07-09  1:03     ` Sean Christopherson
2019-07-07 23:41   ` [RFC PATCH v3 3/4] X86/sgx: Introduce EMA as a new LSM module Cedric Xing
2019-07-08 16:26     ` Casey Schaufler
2019-07-08 17:16       ` Xing, Cedric
2019-07-08 23:53         ` Casey Schaufler
2019-07-09 22:13           ` Xing, Cedric
2019-07-10  0:10             ` Casey Schaufler
2019-07-10  0:55               ` Xing, Cedric
2019-07-10 21:14                 ` Casey Schaufler
2019-07-11 13:51                 ` Stephen Smalley
2019-07-11 15:12                   ` Sean Christopherson
2019-07-11 16:11                     ` Stephen Smalley
2019-07-11 16:25                       ` Sean Christopherson
2019-07-11 16:32                         ` Stephen Smalley
2019-07-11 23:41                           ` Xing, Cedric
2019-07-07 23:41   ` [RFC PATCH v3 4/4] x86/sgx: Implement SGX specific hooks in SELinux Cedric Xing
2019-07-09  1:33     ` Sean Christopherson
2019-07-09 21:26       ` Xing, Cedric
2019-07-10 15:49     ` Sean Christopherson
2019-07-10 16:08       ` Jethro Beekman
2019-07-10 18:16         ` Xing, Cedric
2019-07-10 17:54       ` Xing, Cedric
2019-06-27 18:56 ` [RFC PATCH v2 1/3] x86/sgx: Add SGX specific LSM hooks Cedric Xing
2019-06-27 22:06   ` Casey Schaufler
2019-06-27 22:52     ` Xing, Cedric
2019-06-27 23:37       ` Casey Schaufler
2019-06-28  0:47         ` Xing, Cedric
2019-06-28 17:22           ` Casey Schaufler
2019-06-28 22:29             ` Xing, Cedric
2019-06-29  1:37             ` Stephen Smalley
2019-06-29 21:35               ` Casey Schaufler
2019-07-01 17:57                 ` Xing, Cedric
2019-07-01 19:53                   ` Casey Schaufler
2019-07-01 21:45                     ` Xing, Cedric
2019-07-01 23:11                       ` Casey Schaufler
2019-07-02  7:42                         ` Xing, Cedric
2019-07-02 15:44                           ` Casey Schaufler
2019-07-03  9:46                             ` Dr. Greg
2019-07-03 15:32                               ` Casey Schaufler [this message]
2019-07-07 13:30                                 ` Dr. Greg
2019-07-09  0:02                                   ` Casey Schaufler
2019-07-09  1:52                                     ` Sean Christopherson
2019-07-09 21:16                                       ` Xing, Cedric
2019-07-11 10:22                                     ` Dr. Greg
2019-07-15 22:23                                       ` Andy Lutomirski
2019-06-28 16:37   ` Stephen Smalley
2019-06-28 21:53     ` Xing, Cedric
2019-06-29  1:22       ` Stephen Smalley
2019-07-01 18:02         ` Xing, Cedric
2019-06-29 23:46   ` Andy Lutomirski
2019-07-01 17:11     ` Xing, Cedric
2019-07-01 17:58       ` Andy Lutomirski
2019-07-01 18:31         ` Xing, Cedric
2019-07-01 19:36           ` Andy Lutomirski
2019-07-01 19:56             ` Xing, Cedric
2019-07-02  2:29               ` Andy Lutomirski
2019-07-02  6:35                 ` Xing, Cedric
2019-06-27 18:56 ` [RFC PATCH v2 2/3] x86/sgx: Call LSM hooks from SGX subsystem/module Cedric Xing
2019-06-27 18:56 ` [RFC PATCH v2 3/3] x86/sgx: Implement SGX specific hooks in SELinux Cedric Xing
2019-07-05 16:05 ` [RFC PATCH v4 00/12] security: x86/sgx: SGX vs. LSM Jarkko Sakkinen
2019-07-08 17:29   ` Sean Christopherson
2019-07-08 17:33     ` Xing, Cedric
2019-07-09 16:22     ` Jarkko Sakkinen
2019-07-09 17:09       ` Sean Christopherson
2019-07-09 20:41         ` Xing, Cedric
2019-07-09 22:25           ` Sean Christopherson
2019-07-09 23:11             ` Xing, Cedric
2019-07-10 16:57               ` Sean Christopherson
2019-07-10 20:19         ` Jarkko Sakkinen
2019-07-10 20:31           ` Sean Christopherson
2019-07-11  9:06             ` Jarkko Sakkinen
2019-07-10 22:00           ` Jarkko Sakkinen
2019-07-10 22:16         ` Jarkko Sakkinen
2019-07-10 23:16           ` Xing, Cedric
2019-07-11  9:26             ` Jarkko Sakkinen
2019-07-11 14:32               ` Stephen Smalley
2019-07-11 17:51                 ` Jarkko Sakkinen
2019-07-12  0:08                   ` Xing, Cedric
2019-07-10  1:28     ` Dr. Greg
2019-07-10  2:04       ` Xing, Cedric
2019-07-10  3:21     ` Jethro Beekman

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