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    SubjectRe: Out of tree module using LSM
    > Can we please stop this useless discussion?  Trying to check the content
    > of files to see whether they might be malicious is inherently braindead,
    > and no amounts of plugins in random places will fix this.

    Actually it is quite effective especially for files whose content is
    expected not to be executable material - there are some very distinct
    mathematical signatures.

    For the purposes of figuring out what is needed you can consider a random
    simple user case such as a system which protects you against the works of
    Eric S Raymond. Replace the mathematical analysis and heuristics with a
    user space tool which spots the various ESR papers and design it for that
    if it makes you happier.

    SELinux seems to be able to do most of the lifting around the problem as
    it can relabel a file into eric_t and constrain further access to it.

    The big problem to me is that this essentially boils down to revoke() on
    ordinary files, which as we know is _hard_.

    The simple case is
    write cathedral and bazaar in some order
    <trap close -> process -> label eric_t>

    open (eric_t) - SELinux "no"

    Anyone smart will then write it out of order and keep the file open, or
    make sure someone else has it open. At that point close ceases to be a
    point you can check the labelling. Open doesn't seem too helpful either
    as the target may have the file open before it is modified into an ESR

    Even if you can spot the surrepticious assembly of an ESR work on your
    computer you then have to implement revocation in order to take the file
    away from those with it open.

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      Last update: 2007-11-29 18:39    [W:0.021 / U:53.764 seconds]
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