[Virtio-fs] virtiofs doesn't accept writable group permissions

[stefanx]

Hello German,

Am 04.04.23 um 18:06 schrieb German Maglione:
> Hi Stefan,
>
> On Tue, Apr 4, 2023 at 3:58 PM stefanx <stefanx at lrz.uni-muenchen.de> wrote:
>>
>> Hello,
>>
>> virtiofs doesn't accept writable group permissions (Libvirt/KVM, guest vm and host vm have Ubuntu 22.04):
>>
>> Libvirt XML (host vm):
>>
>>     <filesystem type='mount' accessmode='passthrough'>
>>       <driver type='virtiofs'/>
>>       <source dir='/mnt/xyz'/>
>>       <target dir='mnt-xyz'/>
>>       <address type='pci' domain='0x0000' bus='0x08' slot='0x00' function='0x0'/>
>>     </filesystem>
>>
>> /etc/fstab (guest vm):
>> ```
>> mnt-xyz       /mnt/xyz            virtiofs rw,_netdev 0 0
>> ```
>> In /mnt/xyz/123 I have write permissions at host vm, but not at guest vm. host vm and guest vm have the same LDAP users.
> when you say that you do not have write permission, do you mean that
> when you try to write, it fails?
Now I have made more tests: The user has write permissions to existing files, but cannot create new files on the guest (it's possible on the host)
> Could you send the output of:
> 'ls -lnd /mnt/xyz/123'
> (both in the host and the guest)
>
> and also the output of 'id' in the guest (with the user you are trying to write)

ls -lnd /mnt/xyz/123 
-rw-r--r-- 1 16009 16100 0 Apr  4 19:32 /mnt/xyz/123id 16009gid=16000, groups=...,16100(...),...


We use /mnt/xyz for years in the host without any permission problems, all attributes and permissions for all directories and files in /mnt/xyz/123 are exactly the same on host and guest.


Stefan


>
>
>
>> Any ideas ?
>>
>> Thanks Stefan
>>
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>
>
> --
> German
>