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    SubjectRe: [PATCH v3 4/4] Allow unprivileged chroot when safe
    On Mon, Jan 30, 2012 at 2:41 PM, Colin Walters <walters@verbum.org> wrote:
    > 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.

    You don't need a setuid binary. Just have an initscript set up the bind mounts.

    --Andy
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