[libvirt] [PATCH v3 00/12] Add user namespace support for libvirt lxc

[Gao feng]

On 06/11/2013 02:02 PM, Richard Weinberger wrote:
> Am 11.06.2013 05:12, schrieb Gao feng:
>> On 06/11/2013 04:51 AM, Richard Weinberger wrote:
>>> Am 10.06.2013 21:53, schrieb Richard Weinberger:
>>>> Am 10.06.2013 21:17, schrieb Richard Weinberger:
>>>>> Hi!
>>>>>
>>>>> Am 04.06.2013 13:03, schrieb Daniel P. Berrange:
>>>>>>> It's still under review. needs some ACK.
>>>>>>> If you can help to test or ACK this patchset, it will be very helpful. :)
>>>>>>>
>>>>>>> Actually, I just want to ping...
>>>>>>
>>>>>> I've been away on holiday for 2 weeks, so not had a chance to review
>>>>>> it yet. I'll get to it this week. I hope we'll get this in the 1.0.6
>>>>>> release this month.
>>>>>
>>>>> Finally I've found some time to test version 4 of the userns patch set.
>>>>> But I'm unable to create a container.
>>>>>
>>>>> ---cut---
>>>>> linux:~ # LANG=C /opt/libvirt/bin/virsh -c lxc:/// create c1.conf
>>>>> error: Failed to create domain from c1.conf
>>>>> error: Interner Fehler guest failed to start: PATH=/bin:/sbin TERM=linux container=lxc-libvirt container_uuid=3f86c48b-b027-4838-ba17-6202a1d7398b
>>>>> LIBVIRT_LXC_UUID=3f86c48b-b027-4838-ba17-6202a1d7398b LIBVIRT_LXC_NAME=c1 /bin/bash
>>>>> error receiving signal from container: Input/output error
>>>>> ---cut---
>>>>>
>>>>> lxcContainerWaitForContinue() in src/lxc/lxc_controller.c fails with EIO.
>>>>> Maybe because the clone()'ed child dies and the file descriptor used for synchronization becomes invalid.
>>>>>
>>>>> Here my container config:
>>>>> ---cut---
>>>>> <domain type='lxc'>
>>>>>     <name>c1</name>
>>>>>     <memory>102400</memory>
>>>>>     <os>
>>>>>       <type>exe</type>
>>>>>       <init>/bin/bash</init>
>>>>>     </os>
>>>>>     <idmap>
>>>>>           <uid start='0' target='100000' count='100000'/>
>>>>>           <gid start='0' target='100000' count='100000'/>
>>>>>     </idmap>
>>>>>     <devices>
>>>>>       <console type='pty'/>
>>>>>           <filesystem type='mount'>
>>>>>             <source dir='/root/c1/rootfs'/>
>>>>>             <target dir='/'/>
>>>>>           </filesystem>
>>>>>     </devices>
>>>>> </domain>
>>>>> ---cut---
>>>>>
>>>>> Any ideas how to debug this further?
>>>>> This is Linux 3.9.0 with all namespaces enabled.
>>>>
>>>> Whoops, forgot to add the libvirtd debug output:
>>>>
>>>> ---cut---
>>>> 2013-06-10 19:41:24.661+0000: 29211: debug : virCommandRunAsync:2241 : About to run
>>>> PATH=/usr/lib64/mpi/gcc/openmpi/bin:/sbin:/usr/sbin:/usr/local/sbin:/root/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/usr/games LIBVIRT_DEBUG=1 LIBVIRT_LOG_OUTPUTS=1:stderr
>>>> /opt/libvirt/lib/libvirt_lxc --name c1 --console 20 --security=none --handshake 23 --background
>>>> 2013-06-10 19:41:24.663+0000: 29211: debug : virFileClose:90 : Closed fd 24
>>>> 2013-06-10 19:41:24.663+0000: 29211: debug : virCommandRunAsync:2246 : Command result 0, with PID 29303
>>>> 2013-06-10 19:41:24.664+0000: 29303: debug : virFileClose:90 : Closed fd 3
>>>> 2013-06-10 19:41:24.665+0000: 29303: debug : virFileClose:90 : Closed fd 4
>>>> 2013-06-10 19:41:24.666+0000: 29303: debug : virFileClose:90 : Closed fd 5
>>>> 2013-06-10 19:41:24.666+0000: 29303: debug : virFileClose:90 : Closed fd 6
>>>> 2013-06-10 19:41:24.667+0000: 29303: debug : virFileClose:90 : Closed fd 7
>>>> 2013-06-10 19:41:24.667+0000: 29303: debug : virFileClose:90 : Closed fd 8
>>>> 2013-06-10 19:41:24.668+0000: 29303: debug : virFileClose:90 : Closed fd 9
>>>> 2013-06-10 19:41:24.668+0000: 29303: debug : virFileClose:90 : Closed fd 10
>>>> 2013-06-10 19:41:24.668+0000: 29303: debug : virFileClose:90 : Closed fd 11
>>>> 2013-06-10 19:41:24.668+0000: 29303: debug : virFileClose:90 : Closed fd 12
>>>> 2013-06-10 19:41:24.668+0000: 29303: debug : virFileClose:90 : Closed fd 13
>>>> 2013-06-10 19:41:24.669+0000: 29303: debug : virFileClose:90 : Closed fd 14
>>>> 2013-06-10 19:41:24.669+0000: 29303: debug : virFileClose:90 : Closed fd 15
>>>> 2013-06-10 19:41:24.670+0000: 29303: debug : virFileClose:90 : Closed fd 16
>>>> 2013-06-10 19:41:24.670+0000: 29303: debug : virFileClose:90 : Closed fd 17
>>>> 2013-06-10 19:41:24.670+0000: 29303: debug : virFileClose:90 : Closed fd 18
>>>> 2013-06-10 19:41:24.671+0000: 29303: debug : virFileClose:90 : Closed fd 19
>>>> 2013-06-10 19:41:24.671+0000: 29303: debug : virFileClose:90 : Closed fd 22
>>>> 2013-06-10 19:41:24.790+0000: 29211: debug : virCommandRun:2115 : Result status 0, stdout: '(null)' stderr: '(null)'
>>>> ---cut---
>>>>
>>>> Looks like libvirt_lxc was executed and died silently.
>>>
>>> Found the problem. /opt/libvirt/var/log/libvirt/lxc/c1.log contained the info I needed.
>>> Search permissions for /root were missing. m(
>>> Would be nice if virsh would be able to tell one this...
>>>
>>
>> :)
>> have fun with user namespace & libvirt.
>> And thanks for your test.
> 
> Yeah. So far it looks very good.
> I was able to convert my containers from my custom lxc/userns setup to libvirt+userns.
> 
> One more question, is it by design that virsh lxc-enter-namespace does not setup
> uid/gid mappings?
> 

lxc-enter-namespace doesn't have the need to setup uid/gid mappings, Since lxc-enter-namespace
is running on the host side, the uid/gid mappings already exist, But we should call setid for
the child task of lxc-enter-namespace, this child task running in the container.

I will improve lxc-enter-namespace after this patchset being accepted.

Thanks,
Gao

> Thanks,
> //richard
>