Messages in this thread | | | From | Andy Lutomirski <> | Date | Tue, 9 Sep 2014 12:26:57 -0700 | Subject | Re: For review: user_namespace(7) man page |
| |
On Tue, Sep 9, 2014 at 9:05 AM, Eric W. Biederman <ebiederm@xmission.com> wrote: > > We may also want to discuss the specific restrictions on chroot. > > The text about chroot at least gives people a strong hint that the > chroot rules are affected by user namespaces. > > The restrictions that we have settled on to avoid chroot being a problem > are the creator of a user namespace must not be chrooted in their > current mount namespace, and the creator of the user namespace must not > be threaded. > > Andy can you check me on this it looks like unshare is currently buggy > in that it will allow a threaded application to create a user namespace.
I think it's this code in unshare:
/* * If unsharing a user namespace must also unshare the thread. */ if (unshare_flags & CLONE_NEWUSER) unshare_flags |= CLONE_THREAD | CLONE_FS;
I suppose that this should be documented.
CLONE_FS prevents the chroot from leaking out of the namespace. (But see the other thread that I'm about to start...)
--Andy
| |