On 08/08/2017 09:22 AM, Magalhaes, Guilherme (Brazil R&D-CL) wrote:
Still on the vTPM requirements, could you help answering the following
1. Where will the boot measurements be stored? What is the integrity
measurement domain for this vTPM? The current proposal is that the
vTPM would be used for the container (or namespace) files/inodes.
What else will be available from the vTPM? For example, will the vTPM
provide the UEFI measurements on the first PCRs (copied/proxied from
The vTPM will receive PCR extends exclusively from the namespace it is
associated with. The UEFI measurements could be retrieved from the
hardware TPM. They are not copied since this would require copying the
UEFI measurement list of the host as well. Otherwise the vTPM allows all
commands to be used.
2. From an attestation/quote perspective, how do you envision the key
material to be managed (e.g. the vTPM EK and/or Attestation Key is
fixed to the physical TPM, or it's cryptographically bound to it)?
For quotes by the vTPM to work the EK and AIK need to be inside the
vTPM. Similarly the EK and AIK of the hardware TPM would need be bound
to the hardware TPM for the quoting of the hardware TPM's PCRs to work.
If there's an official way, design by TCG for example, for how to quote
the PCRs of a virtual TPM by the hardware TPM, I would like to know.
3. Can you elaborate more on the alignment of this solution with the
TCG requirements, especially considering the lack of isolation on the
vTPM solution, do you have a future plan to cover those issues?
A software emulated TPM does have its challenges when it comes to
isolation from the root user, as explained in the last email. I am not
sure there is a solution for protecting it from attacks from root,
though we can protect it from non-root users fairly easily. If there are
other isolation requirements than that, let me know.
4. In a micro services pattern, or a serverless compute pattern, in
which one or more containers are created to handle each individual
request it is possible that there will be several thousand containers
created per hour on a busy server. What is the expected performance
and scalability of vTPMs within such an environment?
A vTPM would be created as part of creating a container. The creation of
certificates takes a couple of seconds to contact the CA and mint the
cert. I would say not all of the containers would need to have a
From: Stefan Berger [mailto:stef...@linux.vnet.ibm.com]
Sent: quinta-feira, 27 de julho de 2017 17:52
To: Magalhaes, Guilherme (Brazil R&D-CL) <guilherme.magalh...@hpe.com>;
Mimi Zohar <zo...@linux.vnet.ibm.com>; Serge E. Hallyn <se...@hallyn.com>
Cc: Mehmet Kayaalp <mkaya...@cs.binghamton.edu>; Yuqiong Sun
<sunyuqiong1...@gmail.com>; containers <email@example.com-
foundation.org>; linux-kernel <firstname.lastname@example.org>; David Safford
<david.saff...@ge.com>; James Bottomley
<james.bottom...@hansenpartnership.com>; linux-security-module <linux-
security-mod...@vger.kernel.org>; ima-devel <linux-ima-
de...@lists.sourceforge.net>; Yuqiong Sun <s...@us.ibm.com>
Subject: Re: [Linux-ima-devel] [RFC PATCH 1/5] ima: extend clone() with IMA
On 07/27/2017 03:39 PM, Magalhaes, Guilherme (Brazil R&D-CL) wrote:
There's a vTPM proxy driver in the kernel that enables spawning a
frontend /dev/tpm%d and an anonymous backend file descriptor where a
vTPM can listen on for TPM commands. I integrated this with 'swtpm' and
I have been working on integrating this into runc. Currently each
container started with runc can get one (or multiple) vTPMs and
/dev/tpm0 [and /dev/tpmrm0 in case of TPM2] then appear inside the
This is an interesting solution especially for nested namespaces with the
recursive application of measurements and a having list per container.
Following the TCG specs/requirements, what could we say about security
guarantees of real TPMs Vs this vTPM implementation?
A non-root user may not be able to do access the (permanent) state of
the vTPM state files since the container management stack would restrict
access to the files using DAC. Access to runtime data is also prevented
since the vTPM would not run under the account of the non-root user.
To protect the vTPM's permanent state file from access by a root user it
comes down to preventing the root user from getting a hold of the key
used for encrypting that file. Encrypting the state of the vTPM is
probably the best we can do to approximate a temper-resistant chip, but
preventing the root user from accessing the key may be more challenging.
Preventing root from accessing runtime data could be achieved by using
XGS or a similar technology.
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