Messages in this thread | | | Subject | Re: [PATCH v3 4/4] Allow unprivileged chroot when safe | From | Colin Walters <> | Date | Mon, 30 Jan 2012 17:41:47 -0500 |
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On Mon, 2012-01-30 at 14:10 -0800, Andy Lutomirski wrote: > On Mon, Jan 30, 2012 at 1:58 PM, Colin Walters <walters@verbum.org> wrote: > > On Mon, 2012-01-30 at 08:17 -0800, Andy Lutomirski wrote: > >> Chroot can easily be used to subvert setuid programs. If no_new_privs, > >> then setuid programs don't gain any privilege, so allow chroot. > > > > Is this needed/desired by anyone now, or are you just using it to "demo" > > NO_NEW_PRIVS? I don't see it as very useful on its own, since in any > > "container"-type chroot you really want /proc and /dev, and your patch > > doesn't help with that. > > It's a demo, but it could still be useful for container-ish things. > If something privileged sets up /proc, /sys, and /dev, then > unprivileged code can chroot into the container. This would allow > much simpler implementations of tools like schroot.
What's the win if you still need a setuid binary? schroot (and my linux-user chroot binary) can just as easily call chroot as they can create bind mounts; I'm not buying a code complexity argument.
> With this change, they wouldn't need to start privileged. > (Admittedly, this isn't a great argument for this patch.)
Right...I'm not aware of anyone who would find that useful.
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