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From: Andy Lutomirski <luto@kernel.org>
To: "Sakkinen, Jarkko" <jarkko.sakkinen@intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	James Morris <jmorris@namei.org>,
	kai.huang@intel.com, keyrings@vger.kernel.org,
	Matthew Wilcox <willy@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linux-MM <linux-mm@kvack.org>,
	David Howells <dhowells@redhat.com>,
	LSM List <linux-security-module@vger.kernel.org>,
	Dan Williams <dan.j.williams@intel.com>, X86 ML <x86@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Andrew Lutomirski <luto@kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@intel.com>,
	Alison Schofield <alison.schofield@intel.com>,
	Jun Nakajima <jun.nakajima@intel.com>
Subject: Re: [RFC v2 00/13] Multi-Key Total Memory Encryption API (MKTME)
Date: Wed, 12 Dec 2018 08:29:45 -0800
Message-ID: <CALCETrVztbuRUnp9MUz-Pp85NhY2htNZHGszS+mU_oWoXK3u6A@mail.gmail.com> (raw)
In-Reply-To: <655394650664715c39ef242689fbc8af726f09c3.camel@intel.com>

On Wed, Dec 12, 2018 at 7:31 AM Sakkinen, Jarkko
<jarkko.sakkinen@intel.com> wrote:
>
> On Fri, 2018-12-07 at 15:45 -0800, Jarkko Sakkinen wrote:
> > The brutal fact is that a physical address is an astronomical stretch
> > from a random value or increasing counter. Thus, it is fair to say that
> > MKTME provides only naive measures against replay attacks...
>
> I'll try to summarize how I understand the high level security
> model of MKTME because (would be good idea to document it).
>
> Assumptions:
>
> 1. The hypervisor has not been infiltrated.
> 2. The hypervisor does not leak secrets.
>
> When (1) and (2) hold [1], we harden VMs in two different ways:
>
> A. VMs cannot leak data to each other or can they with L1TF when HT
>    is enabled?

I strongly suspect that, on L1TF-vulnerable CPUs, MKTME provides no
protection whatsoever.  It sounds like MKTME is implemented in the
memory controller -- as far as the rest of the CPU and the cache
hierarchy are concerned, the MKTME key selction bits are just part of
the physical address.  So an attack like L1TF that leaks a cacheline
that's selected by physical address will leak the cleartext if the key
selection bits are set correctly.

(I suppose that, if the attacker needs to brute-force the physical
address, then MKTME makes it a bit harder because the effective
physical address space is larger.)

> B. Protects against cold boot attacks.

TME does this, AFAIK.  MKTME does, too, unless the "user" mode is
used, in which case the protection is weaker.

>
> Isn't this what this about in the nutshell roughly?
>
> [1] XPFO could potentially be an opt-in feature that reduces the
>     damage when either of these assumptions has been broken.
>
> /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
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 [this message]
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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