[libvirt-users] virDBusCallMethod:1173 : Launch helper exited with unknown return code

[Karoline Haus]

Laine Stump <laine at laine.org> schrieb am 9:17 Mittwoch, 15.Januar 2014:
 
On 01/15/2014 10:05 AM, Karoline Haus wrote:

Good morning,
>
>
>I'm using libvirtd on Gentoo.
>This is libvirt version: 1.1.3.1
>
>
>I have trouble starting a VM using virsh start $vm. I do this as root, because as non-root user it did not work at all (especially it failed attaching to the networks). So, when I run the command (with sudo), I get the following error in libvirtd.log:
>
>
>2014-01-15 07:51:00.423+0000: 16158: warning : qemuDomainObjTaint:1573 : Domain id=5 name='vader' uuid=f5b8c05b-9c7a-3211-49b9-2bd635f7e2aa is tainted: high-privileges
>
This usually means that libvirt has been configured to run the qemu
    process as root, which introduces the possibility that a guest
    exploiting some theoretical security exploit in qemu could gain
    control of the host system. Normally libvirt installations will by
    default be configured to run the qemu-kvm process as user qemu, with
    all privilege bits cleared; either gentoo's default install of
    libvirt doesn't set things up this way, or you or someone else has
    modified /etc/libvirt/qemu.conf to change the "user" and "group"
    parameters to "root".

To fix this problem, edit /etc/libvirt/qemu.conf and either comment
    out those two parameters (if they aren't already commented out), or
    change them to set both user and group to "qemu" (assuming that
    gentoo follows the standard of adding a "qemu" user when installing
    libvirt), then restart the libvirt service and try starting the
    guest again.

Note, however, that this is a *warning*, not an error, so the guest
    should still be starting up and running. If not, then there should
    be some subsequent error message in the log (and/or look at the end
    of /var/log/libvirt/qemu/${vm}.log for error messages from qemu)


2014-01-15 07:51:00.428+0000: 16158: error : virDBusCallMethod:1173 : Launch helper exited with unknown return code 1
>
>
>At the same time I get an error in /var/log/messages which seems related:
>Jan 15 07:51:00  dbus[15845]: [system] Activating service name='org.freedesktop.machine1' (using servicehelper)
>Jan 15 07:51:00  dbus[15845]: [system] Activated service
          'org.freedesktop.machine1' failed: Launch helper exited with
          unknown return code 1
>
>
>Anyone ever seen this issue? I have no idea where to look for errors because the message don't really tell me much.
The problem is that the part that tells you something is pretty
    short: "Domain [...] is tainted: high-privileges"


I have tried to execute the qemu-kvm command on the command line directly and that worked immediately.
Because when you run qemu-kvm from the commandline, it is being run
    as root. libvirt goes to great lengths to enable running the
    qemu-kvm process as "unprivileged" as possible, so that any
    potential security exploits in qemu-kvm will be as limited as
    possible in the damage they can do. Any operation that requires
    elevated privileges (e.g. creating a tap device to hook up the
    guest's networking, modifying the selinux labelling of various
    resources) is done by libvirt, which passed open file descriptors to
    the newly created resources to a qemu-kvm process that has been
    created running as an unprivileged user, with all privilege bits
    reset and pretty much all system resources limited by cgroups.


So the problem must be in libvirt.
Well, in your system's libvirt configuration anyway.


The problem is not the "Domain is tainted" issue. I have set the privileges back to user libvirt (I had set it to root myself in libvirtd.conf) and the problem still exists.

2014-01-15 10:42:34.963+0000: 16162: info : libvirt version: 1.1.3.1
2014-01-15 10:42:34.963+0000: 16162: error : virDBusCallMethod:1173 : Launch helper exited with unknown return code 1

You can see now the "Domain is tainted" error (warning!) doesn't show anymore, but the domain still does not start. The only error message I get is the one above. 

In /var/log/messages I still get:

Jan 15 10:42:34  dbus[15845]: [system] Activating service name='org.freedesktop.machine1' (using servicehelper)
Jan 15 10:42:34  dbus[15845]: [system] Activated service 'org.freedesktop.machine1' failed: Launch helper exited with unknown return code 1

I think the problem is in org.freedesktop.machine1. For some reason, that service cannot be activated, but I don't understand why.

Any help would be greatly appreciated.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/libvirt-users/attachments/20140115/52844641/attachment.htm>