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    SubjectRe: [patch 1/2] [RFC] Simple tamper-proof device filesystem.
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    Hi,

    On Mon, December 17, 2007 01:40, Tetsuo Handa wrote:
    > Hello.
    >
    > Indan Zupancic wrote:
    >> What prevents them from mounting tmpfs on top of /dev, bypassing your fs?
    > Mandatory access control (MAC) prevents them from mounting tmpfs on top of
    > /dev .
    > MAC mediates namespace manipulation requests such as mount()/umount().
    >
    >> Also, if they have root there are plenty of ways to prevent an administrator
    >> from logging in, e.g. using iptables or changing the password.
    > MAC mediates execution of /sbin/iptables or /usr/bin/passwd .
    >
    > So, use of this filesystem alone is meaningless because
    > attackers with root privileges can do what you are saying.
    > But use of this filesystem with MAC is still valid because
    > MAC can prevent attackers with root privileges from doing what you are saying.

    If MAC can avoid all that, then why can't it also avoid tampering with /dev?
    What security does your filesystem add at all, if it's useless without a MAC
    doing
    all the hard work?

    I think you can better spend your time on read-only bind mounts.

    Greetings,

    Indan




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