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From: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
To: "Huang, Kai" <kai.huang@intel.com>
Cc: "Williams, Dan J" <dan.j.williams@intel.com>,
	"Schofield, Alison" <alison.schofield@intel.com>,
	"luto@kernel.org" <luto@kernel.org>,
	"willy@infradead.org" <willy@infradead.org>,
	"kirill.shutemov@linux.intel.com"
	<kirill.shutemov@linux.intel.com>,
	"jmorris@namei.org" <jmorris@namei.org>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"keyrings@vger.kernel.org" <keyrings@vger.kernel.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"dhowells@redhat.com" <dhowells@redhat.com>,
	"linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>,
	"x86@kernel.org" <x86@kernel.org>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"bp@alien8.de" <bp@alien8.de>,
	"Hansen, Dave" <dave.hansen@intel.com>,
	"Nakajima, Jun" <jun.nakajima@intel.com>
Subject: Re: [RFC v2 00/13] Multi-Key Total Memory Encryption API (MKTME)
Date: Thu, 6 Dec 2018 22:48:38 -0800
Message-ID: <20181207064837.GD12969@intel.com> (raw)
In-Reply-To: <1544148344.28511.21.camel@intel.com>

On Thu, Dec 06, 2018 at 06:05:50PM -0800, Huang, Kai wrote:
> On Wed, 2018-12-05 at 22:19 +0000, Sakkinen, Jarkko wrote:
> > On Tue, 2018-12-04 at 11:19 -0800, Andy Lutomirski wrote:
> > > I'm not Thomas, but I think it's the wrong direction.  As it stands,
> > > encrypt_mprotect() is an incomplete version of mprotect() (since it's
> > > missing the protection key support), and it's also functionally just
> > > MADV_DONTNEED.  In other words, the sole user-visible effect appears
> > > to be that the existing pages are blown away.  The fact that it
> > > changes the key in use doesn't seem terribly useful, since it's
> > > anonymous memory, and the most secure choice is to use CPU-managed
> > > keying, which appears to be the default anyway on TME systems.  It
> > > also has totally unclear semantics WRT swap, and, off the top of my
> > > head, it looks like it may have serious cache-coherency issues and
> > > like swapping the pages might corrupt them, both because there are no
> > > flushes and because the direct-map alias looks like it will use the
> > > default key and therefore appear to contain the wrong data.
> > > 
> > > I would propose a very different direction: don't try to support MKTME
> > > at all for anonymous memory, and instead figure out the important use
> > > cases and support them directly.  The use cases that I can think of
> > > off the top of my head are:
> > > 
> > > 1. pmem.  This should probably use a very different API.
> > > 
> > > 2. Some kind of VM hardening, where a VM's memory can be protected a
> > > little tiny bit from the main kernel.  But I don't see why this is any
> > > better than XPO (eXclusive Page-frame Ownership), which brings to
> > > mind:
> > 
> > What is the threat model anyway for AMD and Intel technologies?
> > 
> > For me it looks like that you can read, write and even replay 
> > encrypted pages both in SME and TME. 
> 
> Right. Neither of them (including MKTME) prevents replay attack. But
> in my understanding SEV doesn't prevent replay attack either since it
> doesn't have integrity protection.

Yep, it doesn't :-) That's why I've been wondering after seeing
presentations concerning SME and SVE what they are good for.

Cold boot attacks are definitely at least something where these
techs can help...

/Jarkko

  reply index

Thread overview: 91+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-04  7:39 Alison Schofield
2018-12-04  7:39 ` [RFC v2 01/13] x86/mktme: Document the MKTME APIs Alison Schofield
2018-12-05 18:11   ` Andy Lutomirski
2018-12-05 19:22     ` Alison Schofield
2018-12-05 23:35       ` Andy Lutomirski
2018-12-06  8:04   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 02/13] mm: Generalize the mprotect implementation to support extensions Alison Schofield
2018-12-06  8:08   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 03/13] syscall/x86: Wire up a new system call for memory encryption keys Alison Schofield
2018-12-04  7:39 ` [RFC v2 04/13] x86/mm: Add helper functions for MKTME " Alison Schofield
2018-12-04  9:14   ` Peter Zijlstra
2018-12-05  5:49     ` Alison Schofield
2018-12-04 15:35   ` Andy Lutomirski
2018-12-05  5:52     ` Alison Schofield
2018-12-06  8:31   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 05/13] x86/mm: Set KeyIDs in encrypted VMAs Alison Schofield
2018-12-06  8:37   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 06/13] mm: Add the encrypt_mprotect() system call Alison Schofield
2018-12-06  8:38   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 07/13] x86/mm: Add helpers for reference counting encrypted VMAs Alison Schofield
2018-12-04  8:58   ` Peter Zijlstra
2018-12-05  5:28     ` Alison Schofield
2018-12-04  7:39 ` [RFC v2 08/13] mm: Use reference counting for " Alison Schofield
2018-12-04  7:39 ` [RFC v2 09/13] mm: Restrict memory encryption to anonymous VMA's Alison Schofield
2018-12-04  9:10   ` Peter Zijlstra
2018-12-05  5:30     ` Alison Schofield
2018-12-05  9:07       ` Peter Zijlstra
2018-12-04  7:39 ` [RFC v2 10/13] keys/mktme: Add the MKTME Key Service type for memory encryption Alison Schofield
2018-12-06  8:51   ` Sakkinen, Jarkko
2018-12-06  8:54     ` Sakkinen, Jarkko
2018-12-06 15:11     ` Dave Hansen
2018-12-06 22:56       ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 11/13] keys/mktme: Program memory encryption keys on a system wide basis Alison Schofield
2018-12-04  9:21   ` Peter Zijlstra
2018-12-04  9:50     ` Kirill A. Shutemov
2018-12-05  5:44       ` Alison Schofield
2018-12-05  5:43     ` Alison Schofield
2018-12-05  9:10       ` Peter Zijlstra
2018-12-05 17:26         ` Alison Schofield
2018-12-04  7:39 ` [RFC v2 12/13] keys/mktme: Save MKTME data if kernel cmdline parameter allows Alison Schofield
2018-12-04  9:22   ` Peter Zijlstra
2018-12-07  2:14   ` Huang, Kai
2018-12-07  3:42     ` Alison Schofield
2018-12-07  6:39     ` Jarkko Sakkinen
2018-12-07  6:45       ` Jarkko Sakkinen
2018-12-07 11:47     ` Kirill A. Shutemov
2018-12-04  7:40 ` [RFC v2 13/13] keys/mktme: Support CPU Hotplug for MKTME keys Alison Schofield
2018-12-04  9:28   ` Peter Zijlstra
2018-12-05  5:32     ` Alison Schofield
2018-12-04  9:31   ` Peter Zijlstra
2018-12-05  5:36     ` Alison Schofield
2018-12-04  9:25 ` [RFC v2 00/13] Multi-Key Total Memory Encryption API (MKTME) Peter Zijlstra
2018-12-04  9:46   ` Kirill A. Shutemov
2018-12-05 20:32     ` Sakkinen, Jarkko
2018-12-06 11:22       ` Kirill A. Shutemov
2018-12-06 14:59         ` Dave Hansen
2018-12-07 10:12           ` Huang, Kai
2018-12-06 21:23         ` Sakkinen, Jarkko
2018-12-07 11:54           ` Kirill A. Shutemov
2018-12-04 19:19 ` Andy Lutomirski
2018-12-04 20:00   ` Andy Lutomirski
2018-12-04 20:32     ` Dave Hansen
2018-12-05 22:19   ` Sakkinen, Jarkko
2018-12-07  2:05     ` Huang, Kai
2018-12-07  6:48       ` Jarkko Sakkinen [this message]
2018-12-07 11:57     ` Kirill A. Shutemov
2018-12-07 21:59       ` Sakkinen, Jarkko
2018-12-07 23:45         ` Sakkinen, Jarkko
2018-12-07 23:48           ` Andy Lutomirski
2018-12-08  1:33           ` Huang, Kai
2018-12-08  3:53             ` Sakkinen, Jarkko
2018-12-12 15:31           ` Sakkinen, Jarkko
2018-12-12 16:29             ` Andy Lutomirski
2018-12-12 16:43               ` Sakkinen, Jarkko
2018-12-12 23:27                 ` Huang, Kai
2018-12-13  5:49                   ` Sakkinen, Jarkko
2018-12-13  5:52                     ` Sakkinen, Jarkko
2018-12-12 23:24               ` Huang, Kai
2018-12-07 23:35       ` Eric Rannaud
2018-12-05 23:49   ` Dave Hansen
2018-12-06  1:09     ` Andy Lutomirski
2018-12-06  1:25       ` Dan Williams
2018-12-06 15:39       ` Dave Hansen
2018-12-06 19:10         ` Andy Lutomirski
2018-12-06 19:31           ` Dave Hansen
2018-12-07  1:55       ` Huang, Kai
2018-12-07  4:23         ` Dave Hansen
2018-12-07 23:53         ` Andy Lutomirski
2018-12-08  1:11           ` Dave Hansen
2018-12-08  2:07           ` Huang, Kai
2018-12-05 20:30 ` Sakkinen, Jarkko

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