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From: Sean Christopherson <sean.j.christopherson@intel.com>
To: "Dr. Greg" <greg@enjellic.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
	Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	Haitao Huang <haitao.huang@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
	linux-sgx@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Matthew Wilcox <willy@infradead.org>,
	Jethro Beekman <jethro@fortanix.com>,
	Darren Kenny <darren.kenny@oracle.com>,
	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>,
	Josh Triplett <josh@joshtriplett.org>,
	"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>,
	Thomas Gleixner <tglx@linutronix.de>,
	yaozhangx@google.com
Subject: Re: [PATCH v38 10/24] mm: Add vm_ops->mprotect()
Date: Tue, 20 Oct 2020 09:40:00 -0700	[thread overview]
Message-ID: <20201020163959.GB28909@linux.intel.com> (raw)
In-Reply-To: <20201020100118.GA6957@wind.enjellic.com>

On Tue, Oct 20, 2020 at 05:01:18AM -0500, Dr. Greg wrote:
> On Mon, Oct 19, 2020 at 02:31:05PM -0700, Sean Christopherson wrote:
> 
> Good morning, I hope the day is starting well for everyone.
> 
> > On Sun, Oct 18, 2020 at 03:49:20AM -0500, Dr. Greg wrote:
> > > Is this even a relevant control if we cede the notion of dynamically
> > > loadable enclave code, which is the objective of SGX2 hardware, which
> > > will in all likelihood be the only relevant hardware implementation in
> > > the future?
> 
> > Yes, it's still relevant.  Giving the thumbs up to dynamically
> > loadable code is not a purely binary decision, e.g. a user/admin can
> > allow RW->RX transitions but still disallow full RWX permissions.
> 
> With respect to the security issue at hand, the only relevant issue
> would seem to be if a page had write permissions at one time in its
> trajectory to having execute permisions, isn't this correct?

No.  RW->RX has different properties than RWX.  E.g. an enclave that
dynamically loads code is not the same thing as an enclave that allows
simultaneously writing and executing a page.

> The next paragraph of my reply wasn't included in your reply, but I
> did state that the mprotect hook would be relevant if its purpose was
> to disallow this permission trajectory and in the process disable
> enclave dynamic code loading and execution.
> 
> So to assist everyone in understanding this issue and the security
> implications involved, is the ultimate purpose of the mprotect hook to
> disable dynamic code loading?

No, it's to provide line of sight to enforcing granular LSM checks on enclave
pages.  Jumping back to the RWX thing, as a defense in depth measure, a policy
owner could set an SELinux policy to never allow RWX, even for enclaves that
dynamically load code.

Whether or not having per-page granluarity on enclave permission checks is
valuable/interesting is debatable, e.g. it's why LSM integration is notably
absent from the this series.  But, adding the ->mprotect() hook is relatively
cheap and can always be removed if it's deemed unnecessary in the long run.
The reverse is not true; omitting ->mprotect() commits the kernel to an ABI
that is either ugly and potentially painful (require all enclaves to declare
full RWX permissions), or flat out prevents adding granular LSM support in
the future (do nothing).

  reply	other threads:[~2020-10-20 16:40 UTC|newest]

Thread overview: 182+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-15 11:28 [PATCH v38 00/24] Intel SGX foundations Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 01/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 02/24] x86/cpufeatures: x86/msr: Add Intel SGX Launch Control " Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 03/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-09-16 11:44   ` Borislav Petkov
2020-09-16 20:30     ` Jarkko Sakkinen
2020-09-16 20:32       ` Borislav Petkov
2020-09-15 11:28 ` [PATCH v38 04/24] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 05/24] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 06/24] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 07/24] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 08/24] x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 09/24] x86/sgx: Add __sgx_alloc_epc_page() and sgx_free_epc_page() Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 10/24] mm: Add vm_ops->mprotect() Jarkko Sakkinen
2020-09-18 12:44   ` Borislav Petkov
2020-09-18 15:09   ` Andy Lutomirski
2020-09-18 23:24     ` [PATCH v38 10/24] mm: Add vm_ops->mprotect()' Jarkko Sakkinen
2020-09-18 23:53     ` [PATCH v38 10/24] mm: Add vm_ops->mprotect() Sean Christopherson
2020-09-19  0:15       ` Andy Lutomirski
     [not found]         ` <20200922125801.GA133710@linux.intel.com>
2020-09-22 15:11           ` Dave Hansen
2020-09-23 13:30             ` Jarkko Sakkinen
2020-09-23 13:43             ` Jarkko Sakkinen
2020-09-23 14:33             ` Jarkko Sakkinen
2020-09-24 14:50               ` Dave Hansen
2020-09-24 16:27                 ` Sean Christopherson
     [not found]       ` <20200921124946.GF6038@linux.intel.com>
2020-09-21 12:51         ` Jarkko Sakkinen
2020-09-21 13:14         ` Jarkko Sakkinen
     [not found]         ` <20200921165758.GA24156@linux.intel.com>
2020-09-21 21:07           ` Jarkko Sakkinen
2020-09-21 21:18             ` Sean Christopherson
2020-09-22  5:29               ` Jarkko Sakkinen
2020-09-22  5:35                 ` Jarkko Sakkinen
2020-09-22 16:43                   ` Sean Christopherson
2020-09-23 13:50                     ` Jarkko Sakkinen
2020-09-24 19:11                       ` Haitao Huang
2020-09-24 19:28                         ` Sean Christopherson
2020-09-24 19:39                           ` Dave Hansen
2020-09-24 20:01                             ` Sean Christopherson
2020-09-24 20:10                               ` Dave Hansen
2020-09-24 20:25                                 ` Sean Christopherson
2020-09-24 20:54                                   ` Dave Hansen
2020-09-24 23:05                                     ` Sean Christopherson
2020-09-24 23:09                                       ` Dave Hansen
2020-09-25  0:00                                         ` Sean Christopherson
2020-09-25 17:18                                           ` Dave Hansen
2020-09-25 19:43                                             ` Sean Christopherson
2020-09-25 19:53                                               ` Dave Hansen
2020-09-26  4:15                                                 ` Andy Lutomirski
2020-09-28  0:53                                                 ` Jarkko Sakkinen
2020-09-28 14:04                                                   ` Dave Hansen
2020-09-28 16:19                                                     ` Jarkko Sakkinen
2020-09-28 16:48                                                       ` Dave Hansen
2020-09-28 19:32                                                         ` Jarkko Sakkinen
2020-09-28 19:45                                                           ` Dave Hansen
2020-09-28 20:19                                                             ` Jarkko Sakkinen
2020-09-29  1:37                                                               ` Andy Lutomirski
2020-09-29  4:05                                                                 ` Jarkko Sakkinen
2020-09-29 14:24                                                                   ` Dave Hansen
2020-09-30  0:20                                                                     ` Jarkko Sakkinen
2020-09-30 14:35                                                                       ` Dave Hansen
2020-09-28 20:18                                                         ` Jarkko Sakkinen
2020-10-18  8:49                                                     ` Dr. Greg
2020-10-19 21:31                                                       ` Sean Christopherson
2020-10-20 10:01                                                         ` Dr. Greg
2020-10-20 16:40                                                           ` Sean Christopherson [this message]
2020-10-24 14:37                                                             ` Dr. Greg
2020-10-24 15:33                                                               ` Andy Lutomirski
2020-10-26 10:51                                                                 ` Dr. Greg
2020-10-26 22:59                                                                   ` Andy Lutomirski
2020-10-27  0:40                                                                     ` Sean Christopherson
2020-09-24 22:07                                 ` Jarkko Sakkinen
2020-09-24 21:58                           ` Jarkko Sakkinen
2020-09-24 21:55                         ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 11/24] x86/sgx: Add SGX enclave driver Jarkko Sakkinen
2020-09-21  9:30   ` Borislav Petkov
2020-09-21 12:09     ` Jarkko Sakkinen
2020-10-01 17:36   ` Sean Christopherson
2020-10-01 18:49     ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 12/24] x86/sgx: Add SGX_IOC_ENCLAVE_CREATE Jarkko Sakkinen
2020-09-21 10:03   ` Borislav Petkov
2020-09-21 12:28     ` Jarkko Sakkinen
2020-09-21 13:51       ` Borislav Petkov
2020-09-21 19:29         ` Jarkko Sakkinen
2020-10-03  0:23   ` Haitao Huang
2020-10-03  3:24     ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 13/24] x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 14/24] x86/sgx: Add SGX_IOC_ENCLAVE_INIT Jarkko Sakkinen
2020-09-21 17:35   ` Borislav Petkov
2020-09-21 18:10     ` Sean Christopherson
2020-09-21 18:27       ` Borislav Petkov
     [not found]         ` <20200921191658.GA24823@linux.intel.com>
2020-09-22  8:29           ` Borislav Petkov
2020-09-22 11:50             ` Jarkko Sakkinen
2020-09-22 12:56             ` Jethro Beekman
2020-09-22 14:29               ` Borislav Petkov
2020-09-23 14:47                 ` Jarkko Sakkinen
2020-09-23 15:55                   ` Borislav Petkov
2020-09-24 12:23                     ` Jarkko Sakkinen
2020-09-22 16:29               ` Sean Christopherson
2020-09-21 19:22       ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 15/24] x86/sgx: Enable provisioning for remote attestation Jarkko Sakkinen
2020-09-21 18:07   ` Borislav Petkov
2020-09-21 19:27     ` Jarkko Sakkinen
2020-09-21 19:41       ` Borislav Petkov
2020-09-21 21:26         ` Jarkko Sakkinen
2020-09-22  8:30           ` Borislav Petkov
2020-09-15 11:28 ` [PATCH v38 16/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-09-22 10:45   ` Borislav Petkov
2020-09-22 14:03     ` Jarkko Sakkinen
2020-09-22 14:24       ` Borislav Petkov
2020-09-23 14:52         ` Jarkko Sakkinen
2020-09-29  1:14       ` Sean Christopherson
2020-09-29  3:50         ` Jarkko Sakkinen
2020-09-29  8:35           ` Sean Christopherson
2020-09-22 16:24     ` Sean Christopherson
2020-09-22 18:02       ` Borislav Petkov
2020-09-23 15:25       ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 17/24] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen
2020-09-22 15:44   ` Borislav Petkov
2020-09-23 13:20     ` Jarkko Sakkinen
2020-09-23 16:17       ` Borislav Petkov
2020-09-24 11:51         ` Jarkko Sakkinen
2020-09-24 15:57           ` Borislav Petkov
2020-09-24 20:38             ` [PATCH v38 17/24] x86/sgx: ptrace() support for the SGX driver' Jarkko Sakkinen
2020-09-24 20:40               ` Jarkko Sakkinen
2020-09-25  7:53                 ` Borislav Petkov
2020-09-25 11:00                   ` Jarkko Sakkinen
2020-09-25  7:51               ` Borislav Petkov
2020-09-25 11:21                 ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 18/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-09-23 22:07   ` Borislav Petkov
2020-09-24 12:09     ` Jarkko Sakkinen
2020-09-24 16:00       ` Borislav Petkov
2020-09-24 21:07         ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 19/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 20/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-09-24 16:31   ` Borislav Petkov
2020-09-24 23:11     ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 21/24] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-09-24 18:04   ` Borislav Petkov
2020-09-25  1:00     ` Jarkko Sakkinen
2020-09-25  8:28       ` Borislav Petkov
2020-09-27 23:37         ` Jarkko Sakkinen
2020-09-28  8:30           ` Borislav Petkov
2020-09-28 15:02             ` Jarkko Sakkinen
2020-09-25  8:39       ` Jethro Beekman
2020-09-25 11:17         ` Jarkko Sakkinen
2020-09-25 11:43           ` Jethro Beekman
     [not found]     ` <20200925003808.GB20333@linux.intel.com>
2020-09-25  1:04       ` Jarkko Sakkinen
2020-09-25  8:14       ` Borislav Petkov
2020-09-25 10:59         ` Jarkko Sakkinen
2020-09-28 14:36       ` Jarkko Sakkinen
2020-09-25 18:23   ` Andrew Cooper
2020-09-28  0:58     ` Jarkko Sakkinen
2020-09-28 16:44       ` Andrew Cooper
2020-09-28 18:07         ` H.J. Lu
2020-09-28 18:12           ` Andy Lutomirski
2020-09-28 18:17             ` Dave Hansen
2020-09-28 22:07               ` Jarkko Sakkinen
2020-09-28 21:56             ` Jarkko Sakkinen
2020-09-28 22:06               ` H.J. Lu
2020-09-28 22:18                 ` Dave Hansen
2020-09-28 22:41                   ` Andy Lutomirski
2020-09-28 23:38                     ` Andrew Cooper
2020-09-29 14:10                       ` Dave Hansen
2020-09-29 15:01                         ` Andrew Cooper
2020-09-28 21:41           ` Jarkko Sakkinen
2020-09-28 20:42         ` Jarkko Sakkinen
2020-09-28 23:52           ` Andrew Cooper
2020-09-30  0:52             ` Jarkko Sakkinen
2020-09-28 15:43     ` Yu, Yu-cheng
2020-09-28 15:54       ` H.J. Lu
2020-09-28 16:40         ` Yu, Yu-cheng
2020-09-28 21:36         ` Jarkko Sakkinen
2020-09-28 20:56       ` Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 22/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-09-15 11:28 ` [PATCH v38 23/24] docs: x86/sgx: Document SGX micro architecture and kernel internals Jarkko Sakkinen
2020-09-23 13:50   ` Borislav Petkov
2020-09-24 11:28     ` Jarkko Sakkinen
2020-09-24 15:54       ` Borislav Petkov
2020-09-15 11:28 ` [PATCH v38 24/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2020-09-25 22:37   ` Sean Christopherson
2020-09-28  0:44     ` Jarkko Sakkinen
  -- strict thread matches above, loose matches on Subject: below --
2020-09-15 11:04 [PATCH v38 00/24] Intel SGX foundations Jarkko Sakkinen
2020-09-15 11:05 ` [PATCH v38 10/24] mm: Add vm_ops->mprotect() Jarkko Sakkinen

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