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

[Laine Stump]

On 08/04/2016 07:59 AM, Jonatan Schlag wrote:


Am Do, 4. Aug, 2016 um 1:38 schrieb Michal Privoznik 
<mpriv...@redhat.com>:
On 04.08.2016 12:12, Jonatan Schlag wrote:

    Am Do, 4. Aug, 2016 um 11:32 schrieb Michal Privoznik
    <mpriv...@redhat.com <mailto:mpriv...@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
    <http://people.ipfire.org/%7Ejschlag/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.

Are you checking it after the operation has failed and libvirt has 
continued? If libvirt fails to access the file, it will then set 
everything back to its original state, so looking at the file ownership 
after the fact tells you nothing. If you really want to see if the file 
has the proper ownership, you need to attach gdb to libvirtd and set an 
appropriate breakpoint.

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