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    SubjectRe: [patch 1/2] [RFC] Simple tamper-proof device filesystem.
    Quoting Serge E. Hallyn (
    > Quoting Tetsuo Handa (
    > > Hello.
    > >
    > > Serge E. Hallyn wrote:
    > > > CAP_MKNOD will be removed from its capability
    > > I think it is not enough because the root can rename/unlink device files
    > > (mv /dev/sda1 /dev/tmp; mv /dev/sda2 /dev/sda1; mv /dev/tmp /dev/sda2).
    > Sure but that doesn't bother us :)
    > The admin in the container has his own /dev directory and can do what he
    > likes with the devices he's allowed to have. He just shouldn't have
    > access to others. If he wants to rename /dev/sda1 to /dev/sda5 that's
    > his choice.
    > > > To use your approach, i guess we would have to use selinux (or tomoyo)
    > > > to enforce that devices may only be created under /dev?
    > > Everyone can use this filesystem alone.
    > Sure but it is worthless alone.
    > No?

    Oh, no, I'm sorry - I was thinking in terms of my requirements again.
    But your requirements are to ensure that an application accessing a
    device at a well-known location get what it expect.

    So then the main quesiton is still the one I think Al had asked - what
    keeps a rogue CAP_SYS_MOUNT process from doing
    mount --bind /dev/hda1 /dev/null ?


    > What will keep the container admin from doing 'mknod /root/hda1 b 3 1'?
    > > But use with MAC (or whatever access control mechanisms that prevent
    > > attackers from unmounting/overlaying this filesystem) is recomennded.
    > -serge

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      Last update: 2007-12-18 02:59    [W:0.045 / U:33.616 seconds]
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