[Pkg-libvirt-maintainers] Bug#781283: Bug#781283: libvirt-bin: Permission denied with 9p file system

[Boylan, Ross]

Thanks for the fast response.

The UID's match on host and guest.  Notice that the problems with directory listing occurred as root (UID 0).  The copy problem was as ross.  Most of the files are owned by ross (UID 1000).

Eventually,  I'll want to operate from the guest with a UID not present on the host, although I could add it to the host if necessary.

Although it's possible this is a KVM issue, a significant number of similar problems reported on the net were the result of libvirt, usually the security framework (selinux or apparmor--are either relevant for Debian?), but sometimes also the exact mode choices.  The fact that I can't access host files as root from the guest, with libvirt daemon running as root (I think) on the host suggests something is getting in the way.  The apparent logic is "group and  other have no access rights to the file; file's owner UID = 1000; accessing process UID=0; no acesss."

Ross
________________________________________
From: Guido Günther [agx at sigxcpu.org]
Sent: Friday, March 27, 2015 1:22 AM
To: 781283 at bugs.debian.org
Cc: Boylan, Ross
Subject: Re: [Pkg-libvirt-maintainers] Bug#781283: libvirt-bin: Permission denied with 9p file system

Hi Ross,
On Thu, Mar 26, 2015 at 02:17:11PM -0700, Ross Boylan wrote:
> Package: libvirt-bin
> Version: 0.9.12.3-1+deb7u1
> Severity: normal
>
> Operating inside a wheezy VM with fstab including
> SASInstaller    /mnt/SASInstaller   9p  trans=virtio,version=9p2000.L 0 0
> SASUnzip        /mnt/SASUnzip   9p  trans=virtio,version=9p2000.L 0 0
> and libvirt setup with, e.g.,
>     <filesystem type='mount' accessmode='passthrough'>
>       <source dir='/mnt/SASInstaller'/>
>       <target dir='SASInstaller'/>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x0a'
> function='0x0'/>
>     </filesystem>
> Using KVM.
>
> I get lots of "Permission Denied" errors both when listing directory
> contents and when trying to do anything, such as creating a file.
> E.g.,

You need to have matching UIDs in the VM and the host - is that the case? It's working fine
over here since years so it's likely a setup problem on your end.

That said these kind of bugs are better suited for QEMU/KVM since
libvirt only does the setup and QEMU is carrying the actual 9pfs implementation.

Cheers,
 -- Guido