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From: Sean Christopherson <sean.j.christopherson@intel.com>
To: "Dr. Greg" <greg@enjellic.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
	torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
	x86@kernel.org, linux-sgx@vger.kernel.org,
	akpm@linux-foundation.org, dave.hansen@intel.com,
	nhorman@redhat.com, npmccallum@redhat.com,
	haitao.huang@intel.com, andriy.shevchenko@linux.intel.com,
	tglx@linutronix.de, kai.svahn@intel.com, bp@alien8.de,
	josh@joshtriplett.org, luto@kernel.org, kai.huang@intel.com,
	rientjes@google.com, cedric.xing@intel.com,
	puiterwijk@redhat.com
Subject: Re: [PATCH v29 00/20] Intel SGX foundations
Date: Wed, 29 Apr 2020 08:30:04 -0700
Message-ID: <20200429153004.GD15992@linux.intel.com> (raw)
In-Reply-To: <20200426165753.GA11046@wind.enjellic.com>

On Sun, Apr 26, 2020 at 11:57:53AM -0500, Dr. Greg wrote:
> In closing, it is important to note that the proposed SGX driver is
> not available as a module.  This effectively excludes any alternative
> implementations of the driver without replacement of the kernel at
> large.

No it doesn't.  The SGX subsytem won't allocate EPC pages unless userspace
creates an enclave, i.e. preventing unprivileged userspace from accessing
/dev/sgx/enclave will allow loading an alternative out-of-tree SGX module.
Yes, SGX sanitizes the EPC on boot, but that's arguably a good thing for
out-of-tree modules.

And if you want to get crafty and squash in-kernel SGX altogether, boot
with "clearcpuid=<SGX_LC>" and/or "clearcpuid=<SGX>" to disable in-kernel
support entirely.  SGX won't be correctly enumerated in /proc/cpuinfo
relative to the existence of an out-of-tree module, but that seems like a
very minor issue if you're running with a completely different SGX driver.

> It also means that any platform, with SGX hardware support,
> running a kernel with this driver, has the potential for the
> security/privacy issues noted above.

Unless I'm mistaken, /dev/sgx is root-only by default.  There are far
scarier mechanisms available to root for hosing the system.

> If key based policy management is not allowed, then the driver needs
> to be re-architected to have modular support so that alternative
> implementations or the absence of any driver support are at least
> tenable.

As above, using an alternative implementation is teneble, albeit a bit
kludgy.

  parent reply index

Thread overview: 83+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-21 21:52 Jarkko Sakkinen
2020-04-21 21:52 ` [PATCH v29 01/20] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2020-04-21 21:52 ` [PATCH v29 02/20] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2020-04-21 21:52 ` [PATCH v29 03/20] x86/cpufeatures: x86/msr: Intel SGX Launch Control " Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 04/20] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 05/20] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 06/20] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 07/20] x86/cpu/intel: Detect SGX support Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 08/20] x86/sgx: Enumerate and track EPC sections Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 09/20] x86/sgx: Add functions to allocate and free EPC pages Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 10/20] mm: Introduce vm_ops->may_mprotect() Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 11/20] x86/sgx: Linux Enclave Driver Jarkko Sakkinen
2020-05-08 19:09   ` Sean Christopherson
2020-04-21 21:53 ` [PATCH v29 12/20] x86/sgx: Add provisioning Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 13/20] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 14/20] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen
2020-05-06 21:50   ` Sean Christopherson
2020-05-13 21:40     ` Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 15/20] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 16/20] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 17/20] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 18/20] x86/vdso: Implement a vDSO for Intel SGX enclave call Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 19/20] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2020-04-21 21:53 ` [PATCH v29 20/20] docs: x86/sgx: Document SGX micro architecture and kernel internals Jarkko Sakkinen
2020-04-22 16:48 ` [PATCH v29 00/20] Intel SGX foundations Connor Kuehl
2020-04-29  5:22   ` Jarkko Sakkinen
2020-04-26 16:57 ` Dr. Greg
2020-04-29  5:23   ` Jarkko Sakkinen
2020-04-29 15:14     ` Sean Christopherson
2020-04-30  3:59       ` Jarkko Sakkinen
2020-05-02 23:05         ` Dr. Greg
2020-05-03  0:48           ` Andy Lutomirski
2020-05-04  9:34             ` Dr. Greg
2020-04-29 15:30   ` Sean Christopherson [this message]
2020-05-08  0:40     ` Andy Lutomirski
2020-05-07  0:41   ` Thomas Gleixner
2020-05-08 19:02     ` Dr. Greg
2020-05-08 19:56       ` Sean Christopherson
2020-05-14  9:16         ` Dr. Greg
2020-05-14 16:15           ` Sean Christopherson
2020-05-14 16:20             ` Borislav Petkov
2020-05-14 19:29               ` Thomas Gleixner
2020-05-15  9:28               ` Jarkko Sakkinen
2020-05-15  9:42                 ` Borislav Petkov
2020-05-15 16:24                   ` Jarkko Sakkinen
2020-05-15  0:09             ` Jarkko Sakkinen
2020-05-15 19:54           ` Nathaniel McCallum
2020-05-16  9:58             ` Jarkko Sakkinen
2020-05-24 21:27           ` Pavel Machek
2020-05-26  8:16             ` David Laight
2020-04-26 17:03 ` Dr. Greg
2020-04-29 15:27 ` Jethro Beekman
2020-04-30  3:46   ` Jarkko Sakkinen
2020-04-30  7:19     ` Jethro Beekman
2020-04-30  8:23       ` Jarkko Sakkinen
2020-04-30 14:12         ` Jethro Beekman
2020-05-06 12:16           ` Jarkko Sakkinen
2020-05-06 16:39 ` Jordan Hand
2020-05-07 18:06   ` Dr. Greg
2020-05-08 16:16     ` Jordan Hand
2020-05-13 23:09   ` Jarkko Sakkinen
2020-05-06 21:42 ` Nathaniel McCallum
2020-05-06 22:14   ` Sean Christopherson
2020-05-07  5:02     ` Haitao Huang
2020-05-07 16:49       ` Nathaniel McCallum
2020-05-07 19:34         ` Sean Christopherson
2020-05-07 22:35           ` Haitao Huang
2020-05-08  0:25             ` Sean Christopherson
2020-05-28 11:15               ` Jarkko Sakkinen
2020-05-28 11:19                 ` Jarkko Sakkinen
2020-05-07 22:31         ` Haitao Huang
2020-05-13 22:14   ` Jarkko Sakkinen
2020-05-13 22:18     ` Jarkko Sakkinen
2020-05-14  6:31     ` Jethro Beekman
2020-05-14 19:30     ` Thomas Gleixner
2020-05-15  0:22       ` Jarkko Sakkinen
2020-05-08 19:08 ` Sean Christopherson
2020-05-14 19:05   ` Seth Moore
2020-05-15  0:23     ` Jarkko Sakkinen
2020-05-12 11:55 ` Hui, Chunyang
2020-05-12 16:51   ` Dr. Greg
2020-05-14 10:49   ` Jarkko Sakkinen
2020-05-16  8:53 ` [PATCH] x86/cpu/intel: Add nosgx kernel parameter Jarkko Sakkinen

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