Re: [PATCH 09/19] fs: Refuse uid/gid changes which don't map into s_user_ns

Serge E. Hallyn
2015-12-04T19:42:54Z

Quoting Seth Forshee (seth.forshee@canonical.com):
> On Fri, Dec 04, 2015 at 11:27:38AM -0600, Serge E. Hallyn wrote:
> > On Wed, Dec 02, 2015 at 09:40:09AM -0600, Seth Forshee wrote:
> > > Add checks to inode_change_ok to verify that uid and gid changes
> > > will map into the superblock's user namespace. If they do not
> > > fail with -EOVERFLOW. This cannot be overriden with ATTR_FORCE.
> > >
> > > Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
> >
> > Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
> >
> > ... although i could see root on the host being upset that it can't
> > assign a uid not valid in the mounter's ns. But it does seem safer.
>
> That change wouldn't be representable in the backing store though, and
> that could lead to unexpected behaviour. It's better to tell root that
> we can't make the requested change, in my opinion.

Makes sense. Thanks.