From: Jarkko Sakkinen <jarkko@kernel.org>
To: Reinette Chatre <reinette.chatre@intel.com>
Cc: Haitao Huang <haitao.huang@linux.intel.com>,
"Dhanraj, Vijay" <vijay.dhanraj@intel.com>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"bp@alien8.de" <bp@alien8.de>,
"Lutomirski, Andy" <luto@kernel.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>, "Christopherson,,
Sean" <seanjc@google.com>, "Huang, Kai" <kai.huang@intel.com>,
"Zhang, Cathy" <cathy.zhang@intel.com>,
"Xing, Cedric" <cedric.xing@intel.com>,
"Huang, Haitao" <haitao.huang@intel.com>,
"Shanahan, Mark" <mark.shanahan@intel.com>,
"hpa@zytor.com" <hpa@zytor.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH V2 16/32] x86/sgx: Support restricting of enclave page permissions
Date: Wed, 30 Mar 2022 18:02:27 +0300 [thread overview]
Message-ID: <YkRxA0g4O29Sv14Y@iki.fi> (raw)
In-Reply-To: <YkRwi6ukQ8sRaYeB@iki.fi>
On Wed, Mar 30, 2022 at 06:00:30PM +0300, Jarkko Sakkinen wrote:
> On Mon, Mar 28, 2022 at 04:22:35PM -0700, Reinette Chatre wrote:
> > Hi Jarkko,
> >
> > On 3/19/2022 5:24 PM, Jarkko Sakkinen wrote:
> > > On Thu, Mar 17, 2022 at 05:11:40PM -0700, Reinette Chatre wrote:
> > >> Hi Jarkko,
> > >>
> > >> On 3/17/2022 3:51 PM, Jarkko Sakkinen wrote:
> > >>> On Thu, Mar 17, 2022 at 03:08:04PM -0700, Reinette Chatre wrote:
> > >>>> Hi Jarkko,
> > >>>>
> > >>>> On 3/16/2022 9:30 PM, Jarkko Sakkinen wrote:
> > >>>>> On Mon, Mar 14, 2022 at 08:32:28AM -0700, Reinette Chatre wrote:
> > >>>>>> Hi Jarkko,
> > >>>>>>
> > >>>>>> On 3/13/2022 8:42 PM, Jarkko Sakkinen wrote:
> > >>>>>>> On Fri, Mar 11, 2022 at 11:28:27AM -0800, Reinette Chatre wrote:
> > >>>>>>>> Supporting permission restriction in an ioctl() enables the runtime to manage
> > >>>>>>>> the enclave memory without needing to map it.
> > >>>>>>>
> > >>>>>>> Which is opposite what you do in EAUG. You can also augment pages without
> > >>>>>>> needing the map them. Sure you get that capability, but it is quite useless
> > >>>>>>> in practice.
> > >>>>>>>
> > >>>>>>>> I have considered the idea of supporting the permission restriction with
> > >>>>>>>> mprotect() but as you can see in this response I did not find it to be
> > >>>>>>>> practical.
> > >>>>>>>
> > >>>>>>> Where is it practical? What is your application? How is it practical to
> > >>>>>>> delegate the concurrency management of a split mprotect() to user space?
> > >>>>>>> How do we get rid off a useless up-call to the host?
> > >>>>>>>
> > >>>>>>
> > >>>>>> The email you responded to contained many obstacles against using mprotect()
> > >>>>>> but you chose to ignore them and snipped them all from your response. Could
> > >>>>>> you please address the issues instead of dismissing them?
> > >>>>>
> > >>>>> I did read the whole email but did not see anything that would make a case
> > >>>>> for fully exposed EMODPR, or having asymmetrical towards how EAUG works.
> > >>>>
> > >>>> I believe that on its own each obstacle I shared with you is significant enough
> > >>>> to not follow that approach. You simply respond that I am just not making a
> > >>>> case without acknowledging any obstacle or providing a reason why the obstacles
> > >>>> are not valid.
> > >>>>
> > >>>> To help me understand your view, could you please respond to each of the
> > >>>> obstacles I list below and how it is not an issue?
> > >>>>
> > >>>>
> > >>>> 1) ABI change:
> > >>>> mprotect() is currently supported to modify VMA permissions
> > >>>> irrespective of EPCM permissions. Supporting EPCM permission
> > >>>> changes with mprotect() would change this behavior.
> > >>>> For example, currently it is possible to have RW enclave
> > >>>> memory and support multiple tasks accessing the memory. Two
> > >>>> tasks can map the memory RW and later one can run mprotect()
> > >>>> to reduce the VMA permissions to read-only without impacting
> > >>>> the access of the other task.
> > >>>> By moving EPCM permission changes to mprotect() this usage
> > >>>> will no longer be supported and current behavior will change.
> > >>>
> > >>> Your concurrency scenario is somewhat artificial. Obviously you need to
> > >>> synchronize somehow, and breaking something that could be done with one
> > >>> system call into two separates is not going to help with that. On the
> > >>> contrary, it will add a yet one more difficulty layer.
> > >>
> > >> This is about supporting multiple threads in a single enclave, they can
> > >> all have their own memory mappings based on the needs. This is currently
> > >> supported in mainline as part of SGX1.
> >
> >
> > Could you please comment on the above?
>
>
> I've probably spent probably over two weeks of my life addressing concerns
> to the point that I feel as I was implementing this feature (that could be
> faster way to get it done).
>
> So I'll just wait the next version and see how it is like and give my
> feedback based on that. It's not really my problem to address every
> possible concern.
Once v3 is out, I'll check what I think is right, and what is wrong
and might send some fixups and see where that leads to. I think it
is more costructive way to move forward. Repeating same arguments
leads to nowhere.
BR, Jarkko
next prev parent reply other threads:[~2022-03-30 15:03 UTC|newest]
Thread overview: 130+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-08 0:45 [PATCH V2 00/32] x86/sgx and selftests/sgx: Support SGX2 Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 01/32] x86/sgx: Add short descriptions to ENCLS wrappers Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 02/32] x86/sgx: Add wrapper for SGX2 EMODPR function Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 03/32] x86/sgx: Add wrapper for SGX2 EMODT function Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 04/32] x86/sgx: Add wrapper for SGX2 EAUG function Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 05/32] Documentation/x86: Document SGX permission details Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 06/32] x86/sgx: Support VMA permissions more relaxed than enclave permissions Reinette Chatre
2022-03-07 17:10 ` Jarkko Sakkinen
2022-03-07 17:36 ` Reinette Chatre
2022-03-08 8:14 ` Jarkko Sakkinen
2022-03-08 9:06 ` Jarkko Sakkinen
2022-03-08 9:12 ` Jarkko Sakkinen
2022-03-08 16:04 ` Reinette Chatre
2022-03-08 17:00 ` Jarkko Sakkinen
2022-03-08 17:49 ` Reinette Chatre
2022-03-08 18:46 ` Jarkko Sakkinen
2022-03-11 11:06 ` Dr. Greg
2022-02-08 0:45 ` [PATCH V2 07/32] x86/sgx: Add pfn_mkwrite() handler for present PTEs Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 08/32] x86/sgx: x86/sgx: Add sgx_encl_page->vm_run_prot_bits for dynamic permission changes Reinette Chatre
2022-03-04 8:55 ` Jarkko Sakkinen
2022-03-04 19:19 ` Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 09/32] x86/sgx: Export sgx_encl_ewb_cpumask() Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 10/32] x86/sgx: Rename sgx_encl_ewb_cpumask() as sgx_encl_cpumask() Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 11/32] x86/sgx: Move PTE zap code to new sgx_zap_enclave_ptes() Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 12/32] x86/sgx: Make sgx_ipi_cb() available internally Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 13/32] x86/sgx: Create utility to validate user provided offset and length Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 14/32] x86/sgx: Keep record of SGX page type Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 15/32] x86/sgx: Support relaxing of enclave page permissions Reinette Chatre
2022-03-04 8:59 ` Jarkko Sakkinen
2022-02-08 0:45 ` [PATCH V2 16/32] x86/sgx: Support restricting " Reinette Chatre
2022-02-21 0:49 ` Jarkko Sakkinen
2022-02-22 18:35 ` Reinette Chatre
2022-02-23 15:46 ` Jarkko Sakkinen
2022-02-23 19:55 ` Reinette Chatre
2022-02-28 12:27 ` Jarkko Sakkinen
2022-02-23 19:21 ` Dhanraj, Vijay
2022-02-23 22:42 ` Reinette Chatre
2022-02-28 12:24 ` Jarkko Sakkinen
2022-02-28 13:19 ` Jarkko Sakkinen
2022-02-28 15:16 ` Dave Hansen
2022-02-28 17:44 ` Dhanraj, Vijay
2022-03-01 13:26 ` Jarkko Sakkinen
2022-03-01 13:42 ` Jarkko Sakkinen
2022-03-01 17:48 ` Reinette Chatre
2022-03-02 2:05 ` Jarkko Sakkinen
2022-03-02 2:11 ` Jarkko Sakkinen
2022-03-02 4:03 ` Jarkko Sakkinen
2022-03-02 22:57 ` Reinette Chatre
2022-03-03 16:08 ` Haitao Huang
2022-03-03 21:23 ` Reinette Chatre
2022-03-03 21:44 ` Dave Hansen
2022-03-05 3:19 ` Jarkko Sakkinen
2022-03-06 0:15 ` Jarkko Sakkinen
2022-03-06 0:25 ` Jarkko Sakkinen
2022-03-10 5:43 ` Jarkko Sakkinen
2022-03-10 5:59 ` Jarkko Sakkinen
2022-03-03 23:18 ` Jarkko Sakkinen
2022-03-04 4:03 ` Haitao Huang
2022-03-04 8:30 ` Jarkko Sakkinen
2022-03-04 15:51 ` Haitao Huang
2022-03-05 1:02 ` Jarkko Sakkinen
2022-03-06 14:24 ` Haitao Huang
2022-03-03 23:12 ` Jarkko Sakkinen
2022-03-04 0:48 ` Reinette Chatre
2022-03-10 6:10 ` Jarkko Sakkinen
2022-03-10 18:33 ` Haitao Huang
2022-03-11 12:10 ` Jarkko Sakkinen
2022-03-11 12:16 ` Jarkko Sakkinen
2022-03-11 12:33 ` Jarkko Sakkinen
2022-03-11 17:53 ` Reinette Chatre
2022-03-11 18:11 ` Jarkko Sakkinen
2022-03-11 19:28 ` Reinette Chatre
2022-03-14 3:42 ` Jarkko Sakkinen
2022-03-14 3:45 ` Jarkko Sakkinen
2022-03-14 3:54 ` Jarkko Sakkinen
2022-03-14 15:32 ` Reinette Chatre
2022-03-17 4:30 ` Jarkko Sakkinen
2022-03-17 22:08 ` Reinette Chatre
2022-03-17 22:51 ` Jarkko Sakkinen
2022-03-18 0:11 ` Reinette Chatre
2022-03-20 0:24 ` Jarkko Sakkinen
2022-03-28 23:22 ` Reinette Chatre
2022-03-30 15:00 ` Jarkko Sakkinen
2022-03-30 15:02 ` Jarkko Sakkinen [this message]
2022-03-14 2:49 ` Jarkko Sakkinen
2022-03-14 2:50 ` Jarkko Sakkinen
2022-03-14 2:58 ` Jarkko Sakkinen
2022-03-14 15:39 ` Haitao Huang
2022-03-17 4:34 ` Jarkko Sakkinen
2022-03-17 14:42 ` Haitao Huang
2022-03-17 4:37 ` Jarkko Sakkinen
2022-03-17 14:47 ` Haitao Huang
2022-03-17 7:01 ` Jarkko Sakkinen
2022-03-17 7:11 ` Jarkko Sakkinen
2022-03-17 14:28 ` Haitao Huang
2022-03-17 21:50 ` Jarkko Sakkinen
2022-03-17 22:00 ` Jarkko Sakkinen
2022-03-17 22:23 ` Jarkko Sakkinen
2022-02-08 0:45 ` [PATCH V2 17/32] selftests/sgx: Add test for EPCM permission changes Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 18/32] selftests/sgx: Add test for TCS page " Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 19/32] x86/sgx: Support adding of pages to an initialized enclave Reinette Chatre
2022-02-19 11:57 ` Jarkko Sakkinen
2022-02-19 12:01 ` Jarkko Sakkinen
2022-02-20 18:40 ` Jarkko Sakkinen
2022-02-22 19:19 ` Reinette Chatre
2022-02-23 15:46 ` Jarkko Sakkinen
2022-03-07 16:16 ` Jarkko Sakkinen
2022-02-08 0:45 ` [PATCH V2 20/32] x86/sgx: Tighten accessible memory range after enclave initialization Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 21/32] selftests/sgx: Test two different SGX2 EAUG flows Reinette Chatre
2022-03-07 16:39 ` Jarkko Sakkinen
2022-02-08 0:45 ` [PATCH V2 22/32] x86/sgx: Support modifying SGX page type Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 23/32] x86/sgx: Support complete page removal Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 24/32] Documentation/x86: Introduce enclave runtime management section Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 25/32] selftests/sgx: Introduce dynamic entry point Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 26/32] selftests/sgx: Introduce TCS initialization enclave operation Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 27/32] selftests/sgx: Test complete changing of page type flow Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 28/32] selftests/sgx: Test faulty enclave behavior Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 29/32] selftests/sgx: Test invalid access to removed enclave page Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 30/32] selftests/sgx: Test reclaiming of untouched page Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 31/32] x86/sgx: Free up EPC pages directly to support large page ranges Reinette Chatre
2022-02-08 0:45 ` [PATCH V2 32/32] selftests/sgx: Page removal stress test Reinette Chatre
2022-02-22 20:27 ` [PATCH V2 00/32] x86/sgx and selftests/sgx: Support SGX2 Nathaniel McCallum
2022-02-22 22:39 ` Reinette Chatre
2022-02-23 13:24 ` Nathaniel McCallum
2022-02-23 18:25 ` Reinette Chatre
2022-03-02 16:57 ` Nathaniel McCallum
2022-03-02 21:20 ` Reinette Chatre
2022-03-03 1:13 ` Nathaniel McCallum
2022-03-03 17:49 ` Reinette Chatre
2022-03-04 0:57 ` Jarkko Sakkinen
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