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Bug 2040638 - Libvirt needs to document how to validate a AMD SEV guest measurement
Summary: Libvirt needs to document how to validate a AMD SEV guest measurement
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: libvirt
Version: 9.2
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Daniel Berrangé
QA Contact: Luyao Huang
URL:
Whiteboard:
Depends On:
Blocks: 2040646
TreeView+ depends on / blocked
 
Reported: 2022-01-14 10:53 UTC by Daniel Berrangé
Modified: 2023-05-09 08:06 UTC (History)
12 users (show)

Fixed In Version: libvirt-9.0.0-1.el9
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2023-05-09 07:26:11 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker RHELPLAN-108168 0 None None None 2022-01-14 10:55:20 UTC
Red Hat Product Errata RHBA-2023:2171 0 None None None 2023-05-09 07:26:51 UTC

Description Daniel Berrangé 2022-01-14 10:53:32 UTC 
Description of problem:
The current AMD SEV docs in libvirt merely illustrate how to configure a guest with AMD SEV support enabled. At best this means that an *existing* guest will be protected *after* the virt host is compromised.

Ideally users want a guarantee that all new guests are protected, even if the virt host is already compromised. At the very least this requires validating the measurement for a guest exposed by AMD SEV.

Libvirt has the code needed to do that once bug 2030435 is complete.

Figuring out how to actually put this into practice, however, is incredibly difficult and error prone.

For this to be supportable, we need to clearly document how to validate a guest measurement with libvirt.

This needs to be done in a libvirt knowledge base article. 

Version-Release number of selected component (if applicable):
8.0.0
Comment 1 Jaroslav Suchanek 2023-02-02 12:00:50 UTC 
Dan, there is this article for the AMD SEV setup, https://access.redhat.com/articles/4491591. Is there anything else you would suggest to document?
Comment 2 Daniel Berrangé 2023-02-21 13:50:45 UTC 
This is covered in two upstream docs:

https://libvirt.org/kbase/launch_security_sev.html#guest-attestation-for-sev-sev-es-from-a-trusted-host

https://libvirt.org/manpages/virt-qemu-sev-validate.html

both are included in the -docs RPM, so this should be sufficient to consider this bug addressed.
Comment 6 Luyao Huang 2023-02-23 08:58:25 UTC 
Verify this bug with libvirt-docs-9.0.0-6.el9.x86_64:

1. check and review sev update in launch_security_sev.html

# ls /usr/share/doc/libvirt-docs/html/kbase/launch_security_sev.html
/usr/share/doc/libvirt-docs/html/kbase/launch_security_sev.html

In this document, it include important steps/configs for sev guest measurement:

a. If intending to attest the boot measurement, it is required to use a firmware binary that is stateless, as persistent NVRAM can undermine the trust of the secure guest. This is achieved by telling libvirt that a stateless binary is required

...
<os type='efi'>
  <type arch='x86_64' machine='q35'>hvm</type>
  <loader stateless='yes'/>
</os>
...

b. Guest attestation for SEV/SEV-ES from a trusted host


2. check the man page of virt-qemu-sev-validate

# man virt-qemu-sev-validate
Comment 8 errata-xmlrpc 2023-05-09 07:26:11 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (libvirt bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2023:2171
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