Libvirt uses an side files to store the internal state of managed domains in order to re-read the state upon libvirtd service restart. However, if the state was saved in inconsistent state, the state wasn't re-read and the corresponding domain was lost.
The domain may disappear.
When the libvirtd service is saving the internal state of a domain, the consistent internal state is saved and domains which may break it are disallowed to be started up.
The domain is not longer frogotten.
Description of problem:
If a domain with selinux seclabel is started on a host with selinux disabled, it will disapper after libvirtd service restart.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. set security_driver = "none" in /etc/libvirt/qemu.conf (or alternatively disable SELinux on the host)
2. restart libvirtd service (or the host in case the alternative route in step 1 was chosen)
3. start a domain which contains <seclabel type='dynamic' model='selinux' relabel='yes'/> in its XML configuration
4. restart libvirtd
5. domain is lost (or in shutoff state in case of persistent domain)
Domain disappers from 'virsh list' (or is shown as shut off)
Domain does not disappar (or is shown as running).
This is the behaviour that has been around for ages. However, we'd interchanged this for Bug 923946 which reports slightly different problem.
Moving to POST:
Author: Michal Privoznik <email@example.com>
AuthorDate: Tue Apr 2 17:49:34 2013 +0200
Commit: Michal Privoznik <firstname.lastname@example.org>
CommitDate: Wed Apr 3 10:19:46 2013 +0200
sec_manager: Refuse to start domain with unsupported seclabel
If a user configures a domain to use a seclabel of a specific type,
but the appropriate driver is not accessible, we should refuse to
start the domain. For instance, if user requires selinux, but it is
either non present in the system, or is just disabled, we should not
start the domain. Moreover, since we are touching only those labels we
have a security driver for, the other labels may confuse libvirt when
reconnecting to a domain on libvirtd restart. In our selinux example,
when starting up a domain, missing security label is okay, as we
auto-generate one. But later, when libvirt is re-connecting to a live
qemu instance, we parse a state XML, where security label is required
and it is an error if missing:
error : virSecurityLabelDefParseXML:3228 : XML error: security label
This results in a qemu process left behind without any libvirt control.
Huh, for some reason this bug was in POST, but the patch hasn't been backported. So here's the patch:
# rpm -q libvirt
Following the reproduce steps in comment 0
when start the guest, get expect error
# virsh start virtlab_test
error: Failed to start domain virtlab_test
error: unsupported configuration: Unable to find security driver for label selinux
So this bug can VERIFIED.
BTW, if remove the configuration: security_driver = "none", restart libvirtd, when start the domain, libvirtd will crash, there's a new bug 984793 to track this problem.
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, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.