On Mon, Jan 30, 2012 at 1:58 PM, Colin Walters <walters@xxxxxxxxxx> 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-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
