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    SubjectRe: [Umbrella-devel] Re: Getting full path from dentry in LSM hooks
    =?UTF-8?B?S3Jpc3RpYW4gU8O4cmVuc2Vu?= <> said:


    > Umbrella is mostly designed for embedded systems (where selinux is
    > overkill) and also it is very easy to understand. Most restrictions will
    > be made to e.g. stop viruses from spreading, and it is quite easy, yet
    > very effective:

    > If an email client receives an malformed email (like the countless
    > attacks on outlook), a simple restriction could be for the process
    > handeling the mail would be "$HOME/.addressbook",

    A mail handling process with the adressbook off-limit sounds _real_ useful.

    > furthermore, you could
    > specify that attachments executed _from_ the emailprogram would not have
    > access to the network.

    I.e., no child of the email program could access the network, not even to
    answer a message. Sounds restrictive.

    > Thus the virus cannot find mail addresses to send
    > itself to - and it cannot even get network access. Simple and effective.


    > Also simple bufferoverflows in suid-root programs may be avoided.


    > The
    > simple way would to set the restriction "no fork", and thus if an
    > attacker tries to fork a (root) shell, this would be denied.

    A simple exec(2) will do. Or overwriting a file. Or... If you restrict all
    potentially dangerous operations, you have nothing useful left.

    > Another way
    > could be to heavily restrict access to the filesystem. If the program is
    > restricted from /var, the root shell spawned by the attack would not
    > have access either. (restrictions are enherited from parent to children).

    Just delete /var. Oops, it is there for a purpose...
    Dr. Horst H. von Brand User #22616
    Departamento de Informatica Fono: +56 32 654431
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