[libvirt] [PATCH RFC] LXC: don't RO mount /proc, /sys when user namespce enabled

[Chen, Hanxiao]

> -----Original Message-----
> From: Richard Weinberger [mailto:richard.weinberger at gmail.com]
> Sent: Wednesday, December 24, 2014 5:36 AM
> To: Eric Blake
> Cc: Chen, Hanxiao/陈 晗霄; libvir-list at redhat.com
> Subject: Re: [libvirt] [PATCH RFC] LXC: don't RO mount /proc, /sys when user
> namespce enabled
> 
> On Mon, Dec 22, 2014 at 4:12 PM, Eric Blake <eblake at redhat.com> wrote:
> > On 12/21/2014 08:57 PM, Chen Hanxiao wrote:
> >
> > s/namespce/namespace/ in the subject line
> >
> >> If we enabled user ns and provided a uid/gid map,
> >> we do not need to mount /proc, /sys as readonly.
> >> Leave it to kernel for protection.
> >>
> >> Signed-off-by: Chen Hanxiao <chenhanxiao at cn.fujitsu.com>
> >> ---
> >>  src/lxc/lxc_container.c | 6 ++++++
> >>  1 file changed, 6 insertions(+)
> >
> > I'll leave the actual patch review to someone more familiar with LXC
> > namespace setups
> 
> This change will still mount some useless stuff like:
>     { "/.oldroot/proc/sys/net/ipv4", "/proc/sys/net/ipv4", NULL,
> MS_BIND, false, false, true },
>     { "/.oldroot/proc/sys/net/ipv6", "/proc/sys/net/ipv6", NULL,
> MS_BIND, false, false, true },
> 
> You can set skipUserNS for these.

Thanks, I didn't notice that.

> 
> But I *really* would like to see /proc and /sys mounted RW as default.
> Please see my comment to:
> [libvirt] [PATCHv3] lxc: give RW access to /proc/sys/net/ipv[46] to containers

I see your new comments in that thread.
If libvirt enable userns(provided a uid/gid map in XML),
it's safe to drop RO mount completely;
If not, I'm not sure whether it will bring back compatibility issues.

So let's wait for more comments from maintainers.

Regards,
- Chen
> 
> --
> Thanks,
> //richard