Messages in this thread | | | From | Andy Lutomirski <> | Date | Mon, 30 Jan 2012 14:10:22 -0800 | Subject | Re: [PATCH v3 4/4] Allow unprivileged chroot when safe |
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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.
> > System daemons that do chroot for a modicum of security already start > privileged, so this doesn't help them either.
With this change, they wouldn't need to start privileged. (Admittedly, this isn't a great argument for this patch.)
It would be really nice to have unprivileged filesystem namespace features, but that would be more complicated to do safely.
--Andy
> > >
-- Andy Lutomirski AMA Capital Management, LLC Office: (310) 553-5322 Mobile: (650) 906-0647 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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