[libvirt-users] Libvirt: dynamic ownership did not work

[Michal Privoznik]

On 04.08.2016 13:59, Jonatan Schlag wrote:
> 
> 
> Am Do, 4. Aug, 2016 um 1:38 schrieb Michal Privoznik <mprivozn at redhat.com>:
>> On 04.08.2016 12:12, Jonatan Schlag wrote:
>>>
>>>
>>>  Am Do, 4. Aug, 2016 um 11:32 schrieb Michal Privoznik
>>>  <mprivozn at redhat.com>:
>>>>  On 03.08.2016 21:17, Jonatan Schlag wrote:
>>>>>   Hi,
>>>>>   I have a very strange problem with libvirt. I work on some machines
>>>>>  with
>>>>>   libvirt (Debian/ Arch Linux) and libvirt set the ownership of images
>>>>>   file automatically to the qemu user / group for example on Arch
>>>>>  Linux to
>>>>>   nobody:kvm.
>>>>>   So when I copy an image file with root and use I then with qemu,
>>>>>  libvirt
>>>>>   change the owner/ group to nobody:kvm.
>>>>>
>>>>>   But I also compiled libvirt for a machine (gcc 4.9.4 glibc 2.12)
>>>>> and on
>>>>>   this machine libvirt did not change the ownership of the image files
>>>>>   which results in this error:
>>>>>
>>>>>   libvirtError: internal error: process exited while connecting to
>>>>>   monitor: able-ticketing,seamless-migration=on -device
>>>>>
>>>>>  
>>>>> qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,vram64_size_mb=0,vgamem_mb=16,bus=pci.0,addr=0x2
>>>>>
>>>>>
>>>>>   -device intel-hda,id=sound0,bus=pci.0,addr=0x4 -device
>>>>>   hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 -chardev
>>>>>   spicevmc,id=charredir0,name=usbredir -device
>>>>>   usb-redir,chardev=charredir0,id=redir0 -device
>>>>>   virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x7 -msg timestamp=on
>>>>>   2016-08-03T18:19:47.494512Z qemu-system-x86_64: -drive
>>>>>
>>>>>  
>>>>> file=/data/hdd1/libvirt/images/test.img,format=raw,if=none,id=drive-virtio-disk0:
>>>>>
>>>>>
>>>>>   Could not open '/data/hdd1/libvirt/images/test.img': Permission
>>>>> denied
>>>>
>>>>  Can you please share the debug logs?
>>>>
>>>>  http://wiki.libvirt.org/page/DebugLogs
>>>>
>>>>  Also, my initial suspect, before diving any deeper is that usually,
>>>> when
>>>>  users compile libvirt on their own, they forget to set the correct
>>>>  prefix, therefore libvirt is looking for its config files NOT under
>>>>  /etc/libvirt but /usr/local/etc/ or whatever.
>>>>
>>>>  BTW: is the daemon running under root?
>>>>
>>>>  Michal
>>>
>>>  Hi,
>>>
>>>  The daemon runs under root.
>>>
>>>  I uploaded the debug logs to:
>>>
>>>  http://people.ipfire.org/~jschlag/1363864/1_libvirtd.log
>>>
>>>  The UID of the user nobody is 99, the GID of the group kvm is 1011.
>>>
>>>  I added my configure options to the bug report.
>>>
>>>  Following the log the ownership is changed but why is the file still
>>>  owned by root:root?
>>
>> Right. the file is set ownership.
> But the file ist still owned by root:root and so it is not accessable by
> qemu as nobody:kvm. In the moment the only possible way is that the
> change of the ownership fail, but then there should be an error message,
> but there is no error message in the log.

Then the other option that comes to my mind is a race with somebody else
on the system. You can attach gdb to the daemon and set breakpoint to
virSecurityDACSetOwnershipInternal(). In the arguments you should see
the path eventually among with uid:gid.

BTW: what's the domain XML?

Michal