[lxc-users] no more access to /dev/null from this morning up

[Jean-Charles de Longueville]

On Sun, 9 Oct 2016 12:35:54 -0400
Stéphane Graber <stgraber at ubuntu.com> wrote:

> On Sun, Oct 09, 2016 at 12:15:05PM +0200, Jean-Charles de Longueville
> wrote:
> > Hi
> > 
> > This morning the 3 hosts running LXD/LXC on Ubuntu Xenial behave
> > differently from yesterday morning. I cannot start a container
> > anymore
> > 
> > """
> > root at lab:~# lxc launch ubuntu: test -e
> > Creating test
> > Starting test
> > error: Error calling 'lxd forkstart
> > test /var/lib/lxd/containers /var/log/lxd/test/lxc.conf': err='exit
> > status 1' 
> > lxc 20161009095915.905 ERROR lxc_utils - utils.c:open_devnull:1760
> > - Permission denied - Can't open /dev/null
> > lxc 20161009115915.905 ERROR lxc_sync - sync.c:__sync_wait:57 - An
> > error occurred in another process (expected sequence number 5) 
> > lxc 20161009115915.905 ERROR lxc_start - start.c:__lxc_start:1354 - 
> > failed to spawn 'test'
> > 
> > Try `lxc info --show-log test` for more info
> > """
> > 
> > All containers are giving that same answer. I did not change
> > anything myself and no one else has acces to the machines. How did
> > that happen? And how to fix it? I did google a couple of hours to
> > no extend :/
> > 
> > I did reboot the hosts but nothing changes.  
> 
> What does "ls -lh /dev/null" show on your host?
> 
> I had a friend of mine report something similar a while back, where
> some (out of the archive) package he installed on the host added a
> udev hook which would then accidently interfere with the permission
> of /dev/null (making it 664 and changing ownership too).
> 

thanks.
It was indeed changed to an empty file. I did check but I suppose I did
it wrong. 

[ "$(file -b /dev/null)" == "empty" ] && rm /dev/null &&
mknod /dev/null c 1 3 && chmod 666 /dev/null

I guess I need to find the culprit as it redoes the same change every so
often...