[libvirt-users] Problems with user namespaces

Jaka Hudoklin jakahudoklin at gmail.com
Fri Sep 6 11:32:52 UTC 2013 

Hello!

Okay i tried again with only staticly linked busybox:
offlinehacker:~/ $ /home/offlinehacker/busybox/busybox
BusyBox v1.17.1 (Debian 1:1.17.1-8) multi-call binary.
Copyright (C) 1998-2009 Erik Andersen, Rob Landley, Denys Vlasenko
and others. Licensed under GPLv2.
See source distribution for full notice.
....

Again my id:
uid=499(offlinehacker) gid=100(users)
groups=100(users),1(wheel),57(networkmanager)

My rootfs tree(/home/offlinehacker/busybox):
busybox
├── [offlineh users   ]  busybox
└── [offlineh users   ]  busybox-static_1.17.1-8_amd64.deb

It works just fine as root and these folders gets created:
busybox
├── [offlineh users   ]  busybox
├── [offlineh users   ]  busybox-static_1.17.1-8_amd64.deb
├── [root     root    ]  dev
├── [root     root    ]  .oldroot
├── [root     root    ]  proc
└── [root     root    ]  sys

When i start it with idmap with clean rootfs(dev proc sys and .oldroot
deleted) i get this error, and it is a  little bit different now:
error: Failed to create domain from helloworld.xml
error: internal error: guest failed to start: 2013-09-06 11:24:57.088+0000:
5794: debug : virFileC

And log is pretty similar:
sep 06 11:24:56 laptop libvirtd[1542]: EVENT_POLL_UPDATE_HANDLE: watch=241
events=1
sep 06 11:24:57 laptop libvirtd[1542]: Skip interrupt, 1 140499747788544
sep 06 11:24:57 laptop libvirtd[1542]: OBJECT_REF: obj=0x7fc878000c90
sep 06 11:24:57 laptop libvirtd[1542]: OBJECT_REF: obj=0x7fc878000c90
sep 06 11:24:57 laptop libvirtd[1542]: server=0x7fc8a60ddd60
client=0x7fc8a60e8bb0 msg=0x7fc8a60e6970 rerr=0x7fc89a32cd40
args=0x7fc8880160a0 ret=0x7fc888016030
sep 06 11:24:57 laptop libvirtd[1542]: priv=0x7fc8a60ea3a0 conn=(nil)
sep 06 11:24:57 laptop libvirtd[1542]: name=lxc:///
sep 06 11:24:57 laptop libvirtd[1542]: Cannot recv data: Connection reset
by peer
sep 06 11:24:57 laptop libvirtd[1542]: internal error: guest failed to
start: 2013-09-06 11:24:57.088+0000: 5794: debug : virFileC

Rootfs after failed creation looks like this:
busybox
├── [offlineh users   ]  busybox
├── [offlineh users   ]  busybox-static_1.17.1-8_amd64.deb
├── [offlineh users   ]  .oldroot
├── [offlineh users   ]  proc
└── [offlineh users   ]  sys

I have debugging enabled, at least LIBVIRT_DEBUG is set to 1 and i get much
more messages. If there's any my granular debug please let me know.

PS: I forgot to mention my version of libvirt is 1.1.2

Thanks, Jaka!


On Fri, Sep 6, 2013 at 3:41 AM, Gao feng <gaofeng at cn.fujitsu.com> wrote:

> On 09/06/2013 03:15 AM, Jaka Hudoklin wrote:
> > Hello!
> >
> > I'm testing user namespaces and I have quite some problem getting them
> to work.
> >
> > First of all, I have user namespaces support enabled in kernel:
> >
> > offlinehacker:~/ $ uname -r
> > 3.10.10
> > offlinehacker:~/ $ ls /proc/self/ns/
> > ipc@  mnt@  net@  pid@  user@  uts@
> >
> > I created simple ubuntu rootfs and when I start container without idmap,
> so without user namespace mappings, it works just fine:
> >
> > Libivrt config:
> >
> > <domain type='lxc'>
> >   <name>helloworld</name>
> >   <memory>102400</memory>
> >   <os>
> >     <type>exe</type>
> >     <init>/bin/dash</init>
> >   </os>
> >   <!--<idmap>
> >     <uid start='0' target='499' count='10'/>
> >     <gid start='0' target='100' count='10'/>
> >   </idmap>-->
> >   <devices>
> >     <console type='pty'/>
> >     <filesystem type='mount'>
> >       <source dir='/home/offlinehacker/rootfs'/>
> >       <target dir='/'/>
> >     </filesystem>
> >   </devices>
> > </domain>
> >
>
> Your configuration looks good.
>
> > This is how my rootfs looks like:
> >
> > offlinehacker:~/ $ ls -la rootfs
> > drwxr-xr-x 23 offlinehacker users          4096 sep  5 19:06 ./
> > drwxr-xr-x 59 offlinehacker users          4096 sep  5 19:06 ../
> > drwxr-xr-x  2 offlinehacker users          4096 avg 27 14:11 bin/
> > drwxr-xr-x  3 offlinehacker users          4096 avg 27 14:11 boot/
> > drwxr-xr-x  4 offlinehacker users          4096 avg 27 14:11 dev/
> > drwxr-xr-x 86 offlinehacker users          4096 sep  5 18:20 etc/
> > drwxr-xr-x  3 offlinehacker users          4096 avg 27 14:11 home/
> > lrwxrwxrwx  1 offlinehacker users            33 avg 27 14:10 initrd.img
> -> /boot/initrd.img-3.2.0-52-virtual
> > drwxr-xr-x 18 offlinehacker users          4096 avg 27 14:10 lib/
> > drwxr-xr-x  2 offlinehacker users          4096 avg 27 14:10 lib64/
> > drwx------  2 offlinehacker users          4096 avg 27 14:11 lost+found/
> > drwxr-xr-x  2 offlinehacker users          4096 avg 27 14:09 media/
> > drwxr-xr-x  2 offlinehacker users          4096 apr 19  2012 mnt/
> > drwxr-xr-x  2 offlinehacker users          4096 avg 27 14:09 opt/
> > -rw-r--r--  1 offlinehacker vboxusers 231671365 avg 27 14:12
> precise-server-cloudimg-amd64-root.tar.gz
> > drwxr-xr-x  2 offlinehacker users          4096 apr 19  2012 proc/
> > drwx------  2 offlinehacker users          4096 sep  3 23:47 root/
> > drwxr-xr-x  2 offlinehacker users          4096 avg 27 14:11 run/
> > drwxr-xr-x  2 offlinehacker users          4096 avg 27 14:11 sbin/
> > drwxr-xr-x  2 offlinehacker users          4096 mar  5  2012 selinux/
> > drwxr-xr-x  2 offlinehacker users          4096 avg 27 14:09 srv/
> > drwxr-xr-x  2 offlinehacker users          4096 apr 14  2012 sys/
> > drwxrwxrwt  2 offlinehacker users          4096 sep  4 01:39 tmp/
> > drwxr-xr-x 10 offlinehacker users          4096 avg 27 14:09 usr/
> > drwxr-xr-x 12 offlinehacker users          4096 sep  5 18:10 var/
> > lrwxrwxrwx  1 offlinehacker users            29 avg 27 14:10 vmlinuz ->
> boot/vmlinuz-3.2.0-52-virtual
> >
> > And this is who I am:
> > offlinehacker:~/ $ id
> > uid=499(offlinehacker) gid=67(libvirtd)
> groups=100(users),1(wheel),57(networkmanager),67(libvirtd)
>
> Can this user exec //home/offlinehacker/rootfs/bin/dash successfully ?
>
> >
> > When I create the container with idmap uncommented I get the following
> error:
> >
> > offlinehacker:~/ $ virsh -c lxc:/// create helloworld.xml
> > error: Failed to create domain from helloworld.xml
> > error: internal error: guest failed to start: 2013-09-05
> 19:08:57.781+0000: 19036: debug
> >
> > And these are the logs:
> > sep 05 19:08:52 laptop libvirtd[1542]: server=0x7fc8a60ddd60
> client=0x7fc8a60e68d0 msg=0x7fc8a60e9380 rerr=0x7fc89a32cd40
> args=0x7fc88800b4a0 ret=0x7fc88800a1c0
> > sep 05 19:08:52 laptop libvirtd[1542]: priv=0x7fc8a60e91f0 conn=(nil)
> > sep 05 19:08:52 laptop libvirtd[1542]: name=lxc:///
> > sep 05 19:08:57 laptop libvirtd[1542]: Cannot recv data: Connection
> reset by peer
> > sep 05 19:08:58 laptop libvirtd[1542]: internal error: guest failed to
> start: 2013-09-05 19:08:57.781+0000: 19036: debug
> >
> > Looks like .oldroot, dev, proc and sys gets created with mapped
> permissions(499:100), but container fails to start.
> >
>
> Please enable debug mode, I need more information.
>
> http://libvirt.org/logging.html
>
> Thansk
>
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