lkml.org 
[lkml]   [2012]   [Jan]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH v3 4/4] Allow unprivileged chroot when safe
    From
    Date
    On Mon, 2012-01-30 at 16:38 -0600, Will Drewry wrote:
    > On Mon, Jan 30, 2012 at 4:18 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
    > > On Mon, 2012-01-30 at 16:58 -0500, Colin Walters 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.
    > >>
    > >> System daemons that do chroot for a modicum of security already start
    > >> privileged, so this doesn't help them either.
    > >
    > > I thought this was all for sandboxing? If a browers (or user) wants to
    > > run some untrusted code, perhaps a chroot is the best way to do so. It
    > > just will break if it needs to access /proc or /dev.

    I think you'll find your definition of "code" becomes very limited
    without /dev/null, /dev/zero and /proc/cpuinfo for example, as used by
    glibc.

    Personally I find it amazing we're even debating putting new
    security-relevant API in the kernel with no known userspace consumer.
    It can always go in later if someone actually wants it.

    > Interestingly, I believe this change would work for the Chromium
    > setuid sandbox[1]. It uses a fancy clone trick (CLONE_FS) to start the
    > process then chroot once all its dependencies are loaded. It then
    > chroot()s to /proc/self/fd_info (or another empty process-specific
    > directory).

    But...it's setuid, so it can call chroot already? I'm not following how
    this change would benefit the helper.




    \
     
     \ /
      Last update: 2012-01-30 23:51    [W:0.023 / U:0.276 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site