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From: Andy Lutomirski <luto@kernel.org>
To: Reinette Chatre <reinette.chatre@intel.com>,
	dave.hansen@linux.intel.com, jarkko@kernel.org,
	tglx@linutronix.de, bp@alien8.de, mingo@redhat.com,
	linux-sgx@vger.kernel.org, x86@kernel.org
Cc: seanjc@google.com, kai.huang@intel.com, cathy.zhang@intel.com,
	cedric.xing@intel.com, haitao.huang@intel.com,
	mark.shanahan@intel.com, hpa@zytor.com,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 10/25] x86/sgx: Support enclave page permission changes
Date: Fri, 3 Dec 2021 11:38:47 -0800	[thread overview]
Message-ID: <4960c8f9-72e4-0f40-64e4-4384a76d1e69@kernel.org> (raw)
In-Reply-To: <44fe170cfd855760857660b9f56cae8c4747cc15.1638381245.git.reinette.chatre@intel.com>

On 12/1/21 11:23, Reinette Chatre wrote:
> In the initial (SGX1) version of SGX, pages in an enclave need to be
> created with permissions that support all usages of the pages, from the
> time the enclave is initialized until it is unloaded. For example,
> pages used by a JIT compiler or when code needs to otherwise be
> relocated need to always have RWX permissions.
> 
> SGX2 includes two functions that can be used to modify the enclave page
> permissions of regular enclave pages within an initialized enclave.
> ENCLS[EMODPR] is run from the OS and used to restrict enclave page
> permissions while ENCLU[EMODPE] is run from within the enclave to
> extend enclave page permissions.
> 
> Enclave page permission changes need to be approached with care and
> for this reason this initial support is to allow enclave page
> permission changes _only_ if the new permissions are the same or
> more restrictive that the permissions originally vetted at the time the
> pages were added to the enclave. Support for extending enclave page
> permissions beyond what was originally vetted is deferred.
> 

I may well be missing something, but off the top of my head, literally 
the only reason that EMODPR needs CPL0 (i.e. ENCLS) is that it requires 
a TLB flush IPI to take effect.  (Score one for AMD for being having 
superior hardware in this regard.)

Given that, I don't see any reason for the EMODPR operation to be 
treated as security sensitive -- it just needs to be implemented 
correctly.  I don't even see why the host should (or even can!) do any 
useful tracking of the EPCM state.

(But I am confused about one thing: to the extent an enclave actually 
needs EMODPR, is there anything in the hardware or anything that the 
enclave can do short of actually poking the page from all threads and 
confirming that a fault occurs to make sure the OS actually flushed the 
TLB?  ISTM a malicious host could attack an enclave by omitting the TLB 
flush and then exploiting an enclave but that would have been mitigated 
if the flush occurred.)

--Andy

  parent reply	other threads:[~2021-12-03 19:38 UTC|newest]

Thread overview: 155+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-01 19:22 [PATCH 00/25] x86/sgx and selftests/sgx: Support SGX2 Reinette Chatre
2021-12-01 19:22 ` [PATCH 01/25] x86/sgx: Add shortlog descriptions to ENCLS wrappers Reinette Chatre
2021-12-04 18:30   ` Jarkko Sakkinen
2021-12-06 21:13     ` Reinette Chatre
2021-12-11  5:28       ` Jarkko Sakkinen
2021-12-13 22:06         ` Reinette Chatre
2021-12-01 19:23 ` [PATCH 02/25] x86/sgx: Add wrappers for SGX2 functions Reinette Chatre
2021-12-04 22:04   ` Jarkko Sakkinen
2021-12-06 21:15     ` Reinette Chatre
2021-12-01 19:23 ` [PATCH 03/25] x86/sgx: Support VMA permissions exceeding enclave permissions Reinette Chatre
2021-12-04 22:25   ` Jarkko Sakkinen
2021-12-04 22:27     ` Jarkko Sakkinen
2021-12-06 21:16       ` Reinette Chatre
2021-12-11  5:39         ` Jarkko Sakkinen
2021-12-13 22:08           ` Reinette Chatre
2021-12-01 19:23 ` [PATCH 04/25] x86/sgx: Add pfn_mkwrite() handler for present PTEs Reinette Chatre
2021-12-04 22:43   ` Jarkko Sakkinen
2021-12-06 21:18     ` Reinette Chatre
2021-12-11  7:37       ` Jarkko Sakkinen
2021-12-13 22:09         ` Reinette Chatre
2021-12-28 14:51           ` Jarkko Sakkinen
2021-12-01 19:23 ` [PATCH 05/25] x86/sgx: Introduce runtime protection bits Reinette Chatre
2021-12-03 19:28   ` Andy Lutomirski
2021-12-03 22:12     ` Reinette Chatre
2021-12-04  0:38       ` Andy Lutomirski
2021-12-04  1:14         ` Reinette Chatre
2021-12-04 17:56           ` Andy Lutomirski
2021-12-04 23:55             ` Reinette Chatre
2021-12-13 22:34               ` Reinette Chatre
2021-12-04 23:57     ` Jarkko Sakkinen
2021-12-06 21:20       ` Reinette Chatre
2021-12-11  7:42         ` Jarkko Sakkinen
2021-12-13 22:10           ` Reinette Chatre
2021-12-28 14:52             ` Jarkko Sakkinen
2022-01-06 17:46               ` Reinette Chatre
2022-01-07 12:16                 ` Jarkko Sakkinen
2022-01-07 16:14                   ` Haitao Huang
2022-01-08 15:45                     ` Jarkko Sakkinen
2022-01-08 15:51                       ` Jarkko Sakkinen
2022-01-08 16:22                         ` Jarkko Sakkinen
2022-01-10 22:05                           ` Haitao Huang
2022-01-11  1:53                             ` Jarkko Sakkinen
2022-01-11  1:55                               ` Jarkko Sakkinen
2022-01-11  2:03                                 ` Jarkko Sakkinen
2022-01-11  2:15                                   ` Jarkko Sakkinen
2022-01-11  3:48                                     ` Haitao Huang
2022-01-12 23:48                                       ` Jarkko Sakkinen
2022-01-13  2:41                                         ` Haitao Huang
2022-01-14 21:36                                           ` Jarkko Sakkinen
2022-01-11 17:13                               ` Reinette Chatre
2022-01-12 23:50                                 ` Jarkko Sakkinen
2022-01-12 23:56                                   ` Jarkko Sakkinen
2022-01-13 20:09                                     ` Nathaniel McCallum
2022-01-13 21:42                                       ` Reinette Chatre
2022-01-14 21:53                                         ` Jarkko Sakkinen
2022-01-14 21:57                                           ` Jarkko Sakkinen
2022-01-14 22:00                                             ` Jarkko Sakkinen
2022-01-14 22:17                                           ` Jarkko Sakkinen
2022-01-14 22:23                                             ` Jarkko Sakkinen
2022-01-14 22:34                                               ` Jarkko Sakkinen
2022-01-14 23:05                                           ` Reinette Chatre
2022-01-14 23:15                                             ` Jarkko Sakkinen
2022-01-15  0:01                                               ` Reinette Chatre
2022-01-15  0:27                                                 ` Jarkko Sakkinen
2022-01-15  0:41                                                   ` Reinette Chatre
2022-01-15  1:18                                                     ` Jarkko Sakkinen
2022-01-15 11:56                                                       ` Jarkko Sakkinen
2022-01-15 11:59                                                         ` Jarkko Sakkinen
2022-01-17 13:13                                                         ` Nathaniel McCallum
2022-01-18  1:59                                                           ` Jarkko Sakkinen
2022-01-18  2:22                                                             ` Jarkko Sakkinen
2022-01-18  3:31                                                               ` Jarkko Sakkinen
2022-01-18 20:59                                                               ` Reinette Chatre
2022-01-20 12:53                                                                 ` Jarkko Sakkinen
2022-01-20 16:52                                                                   ` Reinette Chatre
2022-01-26 14:41                                                                     ` Jarkko Sakkinen
2022-01-15 16:49                                               ` Jarkko Sakkinen
2022-01-18 21:18                                                 ` Reinette Chatre
2022-01-17 13:27                                         ` Nathaniel McCallum
2022-01-18 21:11                                           ` Reinette Chatre
2021-12-04 22:50   ` Jarkko Sakkinen
2021-12-06 21:28     ` Reinette Chatre
2021-12-01 19:23 ` [PATCH 06/25] x86/sgx: Use more generic name for enclave cpumask function Reinette Chatre
2021-12-04 22:56   ` Jarkko Sakkinen
2021-12-06 21:29     ` Reinette Chatre
2021-12-01 19:23 ` [PATCH 07/25] x86/sgx: Move PTE zap code to separate function Reinette Chatre
2021-12-04 22:59   ` Jarkko Sakkinen
2021-12-06 21:30     ` Reinette Chatre
2021-12-11  7:52       ` Jarkko Sakkinen
2021-12-13 22:11         ` Reinette Chatre
2021-12-28 14:55           ` Jarkko Sakkinen
2022-01-06 17:46             ` Reinette Chatre
2022-01-07 12:26               ` Jarkko Sakkinen
2021-12-01 19:23 ` [PATCH 08/25] x86/sgx: Make SGX IPI callback available internally Reinette Chatre
2021-12-04 23:00   ` Jarkko Sakkinen
2021-12-06 21:36     ` Reinette Chatre
2021-12-11  7:53       ` Jarkko Sakkinen
2021-12-01 19:23 ` [PATCH 09/25] x86/sgx: Keep record of SGX page type Reinette Chatre
2021-12-04 23:03   ` Jarkko Sakkinen
2021-12-01 19:23 ` [PATCH 10/25] x86/sgx: Support enclave page permission changes Reinette Chatre
2021-12-02 23:48   ` Dave Hansen
2021-12-03 18:18     ` Reinette Chatre
2021-12-03  0:32   ` Dave Hansen
2021-12-03 18:18     ` Reinette Chatre
2021-12-03 18:14   ` Dave Hansen
2021-12-03 18:49     ` Reinette Chatre
2021-12-03 19:38   ` Andy Lutomirski [this message]
2021-12-03 22:34     ` Reinette Chatre
2021-12-04  0:42       ` Andy Lutomirski
2021-12-04  1:35         ` Reinette Chatre
2021-12-04 23:08   ` Jarkko Sakkinen
2021-12-06 20:19     ` Dave Hansen
2021-12-11  5:17       ` Jarkko Sakkinen
2021-12-06 21:42     ` Reinette Chatre
2021-12-11  7:57       ` Jarkko Sakkinen
2021-12-13 22:12         ` Reinette Chatre
2021-12-28 14:56           ` Jarkko Sakkinen
2021-12-01 19:23 ` [PATCH 11/25] selftests/sgx: Add test for EPCM " Reinette Chatre
2021-12-01 19:23 ` [PATCH 12/25] selftests/sgx: Add test for TCS page " Reinette Chatre
2021-12-01 19:23 ` [PATCH 13/25] x86/sgx: Support adding of pages to initialized enclave Reinette Chatre
2021-12-03  0:38   ` Dave Hansen
2021-12-03 18:47     ` Reinette Chatre
2021-12-04 23:13   ` Jarkko Sakkinen
2021-12-06 21:44     ` Reinette Chatre
2021-12-11  8:00       ` Jarkko Sakkinen
2021-12-13 22:12         ` Reinette Chatre
2021-12-28 14:57           ` Jarkko Sakkinen
2022-03-01 15:13   ` Jarkko Sakkinen
2022-03-01 17:08     ` Reinette Chatre
2021-12-01 19:23 ` [PATCH 14/25] x86/sgx: Tighten accessible memory range after enclave initialization Reinette Chatre
2021-12-04 23:14   ` Jarkko Sakkinen
2021-12-06 21:45     ` Reinette Chatre
2021-12-11  8:01       ` Jarkko Sakkinen
2021-12-01 19:23 ` [PATCH 15/25] selftests/sgx: Test two different SGX2 EAUG flows Reinette Chatre
2021-12-01 19:23 ` [PATCH 16/25] x86/sgx: Support modifying SGX page type Reinette Chatre
2021-12-04 23:45   ` Jarkko Sakkinen
2021-12-06 21:48     ` Reinette Chatre
2021-12-11  8:02       ` Jarkko Sakkinen
2021-12-13 17:43         ` Dave Hansen
2021-12-21  8:52           ` Jarkko Sakkinen
2021-12-01 19:23 ` [PATCH 17/25] x86/sgx: Support complete page removal Reinette Chatre
2021-12-04 23:45   ` Jarkko Sakkinen
2021-12-06 21:49     ` Reinette Chatre
2021-12-01 19:23 ` [PATCH 18/25] selftests/sgx: Introduce dynamic entry point Reinette Chatre
2021-12-01 19:23 ` [PATCH 19/25] selftests/sgx: Introduce TCS initialization enclave operation Reinette Chatre
2021-12-01 19:23 ` [PATCH 20/25] selftests/sgx: Test complete changing of page type flow Reinette Chatre
2021-12-01 19:23 ` [PATCH 21/25] selftests/sgx: Test faulty enclave behavior Reinette Chatre
2021-12-01 19:23 ` [PATCH 22/25] selftests/sgx: Test invalid access to removed enclave page Reinette Chatre
2021-12-01 19:23 ` [PATCH 23/25] selftests/sgx: Test reclaiming of untouched page Reinette Chatre
2021-12-01 19:23 ` [PATCH 24/25] x86/sgx: Free up EPC pages directly to support large page ranges Reinette Chatre
2021-12-04 23:47   ` Jarkko Sakkinen
2021-12-06 22:07     ` Reinette Chatre
2021-12-01 19:23 ` [PATCH 25/25] selftests/sgx: Page removal stress test Reinette Chatre
2021-12-02 18:30 ` [PATCH 00/25] x86/sgx and selftests/sgx: Support SGX2 Dave Hansen
2021-12-02 20:38   ` Nathaniel McCallum

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