[libvirt-users] accessing USB as storage device through lxc container.

[ravi mh]

Thanks Martin for the info.



I have tried the below snippet in the libvirt xml.

 <hostdev mode='capabilities' type='storage'>
      <source>
        <block>/dev/sdc1</block>
      </source>
    </hostdev>

------------

root at ir800-lxc:~# mount /dev/sdc1 /mnt/usbdr/

mount: permission denied (are you root?)

----------

It works if the usernamespace is not enabled.



The reason being, we have enabled the username and hence its unprivileged
container.

As per this patch:
https://www.redhat.com/archives/libvir-list/2012-November/msg01555.html,
the capabilities with USB as storage is available for mounting if its
privileged container.

Is there a way to mount this inside the container with usernamespace
enabled and with some capabilities turned on?



Regards,
*Ravi M H*



On Thu, Feb 2, 2017 at 9:09 PM, Martin Kletzander <mkletzan at redhat.com>
wrote:

> On Thu, Feb 02, 2017 at 06:30:24PM -0800, ravi mh wrote:
>
>> Hi all,
>>
>> I am not able to access USB as storage device in the lxc container.
>> Having tried to pass the usb device with the product and vendor id, not
>> able to see the device mounted in the lxc file system.
>>
>>
> It won't be mounted, it will just be passed through as a device,
> i.e. you will see it in the lsusb output.  If you need to mount it, then
> it needs to be done either in the container (for which you might need
> some capability) or mounted on the host and just using device
> <filesystem/> instead.
>
> However, they are seen as char devices in the container at the location.
>> There is no issue of ACL, as the capabilities restrictions have been
>> dropped.
>>
>> Has anyone successfully mounted the storage device in the libvirt.  Having
>> gone through the libvirt documentation, couldnt find further information
>> of
>> enabling the usb as storage device.  Any pointers towards that would be
>> useful.
>>
>>
>> Host OS:
>>
>> IR800-GOS-1:~# lsusb
>> Bus 001 Device 003: ID 8644:800b
>> Bus 001 Device 001: ID 1d6b:0002
>> Bus 002 Device 001: ID 1d6b:0001
>> IR800-GOS-1:~#
>>
>> Lxc app container:
>>
>> root at ir800-lxc:/mnt/usb# ls -la  /dev/bus/usb/001/003
>> *crwx-*-----    1 root     root      189,   2 Feb  3 01:44
>> /dev/bus/usb/001/003
>>
>>
>>
>> ----------libvirt xml snippet ------------
>>
>>    <hostdev mode='subsystem' type='usb' managed='yes'>
>>      <source>
>>        <vendor id='0x8644'/>
>>        <product id='0x800b'/>
>>      </source>
>>    </hostdev>
>>
>> -----------------------------
>> while changing the mode from subsystem to capabilities, it issues error
>> for
>> validating against the schema.
>>
>> ---------------while changing the hostdev mode='capabilities'----------
>>
>> virsh # edit n01_1
>> *error: XML document failed to validate against schema: Unable to validate
>> doc against /usr/share/libvirt/schemas/domain.rng*
>> Extra element devices in interleave
>> Element domain failed to validate content
>>
>> Failed. Try again? [y,n,i,f,?]:
>> error: XML document failed to validate against schema: Unable to validate
>> doc against /usr/share/libvirt/schemas/domain.rng
>>
>> --------------------------------------------
>>
>>
>> Regards,
>> *Ravi*
>>
>
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>
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