[libvirt] I have no idea why the current version of libvirt works for anyone in enforcing mode.

Daniel J Walsh dwalsh at redhat.com
Fri Mar 13 14:50:04 UTC 2009

On 03/13/2009 09:49 AM, Daniel P. Berrange wrote:
> On Fri, Mar 13, 2009 at 09:44:15AM -0400, Daniel J Walsh wrote:
>> On 03/13/2009 06:19 AM, Daniel P. Berrange wrote:
>>> On Thu, Mar 12, 2009 at 01:39:13PM -0400, Daniel J Walsh wrote:
>>>> Libvirt is executing qemu requiring it to execute pulseaudio which would
>>>> require the folowing permissions,
>>>> #============= svirt_t ==============
>>>> allow svirt_t admin_home_t:dir setattr;
>>>> allow svirt_t admin_home_t:file { read write };
>>>> allow svirt_t pulseaudio_port_t:tcp_socket name_connect;
>>>> allow svirt_t svirt_tmpfs_t:file read;
>>>> allow svirt_t user_tmpfs_t:file read;
>>>> Since qemu(svirt_t) is not allowed these permissions, pulseaudio crashes
>>>> and qemu dies.
>>> I don't see it crashing - when I run with a guest with a sound device
>>> attached, I see the AVC denials, and QEMU just carries on without a
>>> active sound backend AFAICT.
>>>> I believe you need to run without sound if you are running as root.
>>> We can't disable sound unconditonally for root, because not everyone
>>> will be using SELinux so its still valid to allow sound cards. I think
>>> the focus has to be on stopping QEMU from crashing. It might actually
>>> be an SDL bug, rather than a QEMU bug, because I believe its SDL that
>>> is responsible for opening the sound devices.
>>> Daniel
>> How about if we check if you are running with svirt then don't execute
>> the code.  Since I do not want to deal with these avc messages.  Either
>> they will happen always and I have to dontaudit them in which case a
>> compromised svirt attacking the /root directory would be dontaudited, or
>> people are going to see avc's all the time.
> For that scenario I think it'd be better to make virt-manager prevent
> addition of sound hardware, since its in a position to give feedback
> to the user telling them why sound devices aren't allowed.
> Daniel
Well there is no protocol currently to tell virt-manager that the 
libvirt is running with svirt.  I tried to remove a audio device via 
virt-manager and it does nothing.  Also what happens when virt-manager 
configures a remote libvirt?  Does the sound card automatically get added?

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