libvirt dynamic file ownership

Joe Muro
2020-03-20T15:38:36Z

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Hi,

I am trying to understand libvirt dynamic
ownership behavior. I have a VM that uses a qcow2 image with the following
permissions:

$ ll
t257kvxg-10-20-101-40.qcow2 -rw-r--r-- 1 jmuro libvirt 2279079936 Mar
20 11:10 t257kvxg-10-20-101-40.qcow2

When I start the domain the permissions
are changed:

$ virsh start
t257kvxg-10-20-101-40 Domain t257kvxg-10-20-101-40 started
$ ll t257kvxg-10-20-101-40.qcow2 -rw-r--r-- 1 libvirt-qemu
libvirt 2279079936 Mar 20 11:18
t257kvxg-10-20-101-40.qcow2

This is expected behavior based on the settings
in /etc/libvirt/qemu.conf:

user =
"libvirt-qemu" group = "libvirt"
# Whether libvirt should dynamically change file ownership #
to match the configured user/group above. Defaults to 1. # Set to 0 to
disable file ownership changes. #dynamic_ownership =
1

However, when I shutdown the domain, the file
permissions revert to root.

$ ll
t257kvxg-10-20-101-40.qcow2 -rw-r--r-- 1 root root 2282749952 Mar 20
11:20 t257kvxg-10-20-101-40.qcow2

I expect libvirt to revert the file permissions
back to the original. Otherwise, a regular user would lose ownership of the
image file. FWIW: I am starting the domain as a&nbsp;non-root user under
qemu:///system

I am running on Ubuntu 20.04 LTS (Focal Fossa)
with the following libvirt level:

libvirt-clients/focal,now 6.0.0-0ubuntu5 s390x
[installed] libvirt-daemon-driver-qemu/focal,now 6.0.0-0ubuntu5 s390x
[installed,automatic] libvirt-daemon-driver-storage-rbd/focal,now
6.0.0-0ubuntu5 s390x
[installed,automatic] libvirt-daemon-system-systemd/focal,now
6.0.0-0ubuntu5 s390x
[installed,automatic] libvirt-daemon-system/focal,now 6.0.0-0ubuntu5
s390x [installed] libvirt-daemon/focal,now 6.0.0-0ubuntu5 s390x
[installed] libvirt-glib-1.0-0/focal,now 2.0.0-2 s390x
[installed,automatic] libvirt0/focal,now 6.0.0-0ubuntu5 s390x
[installed,automatic] python3-libvirt/focal,now 6.0.0-0ubuntu3 s390x
[installed]

Thanks

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>-Joe