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    SubjectRe: [patch 2.1.97] more capabilities support

    Albert D. Cahalan writes:
    > > Sorry, I guess I was not clear on this. The only requirement for a
    > > process to raise an effective capability is that its Permitted
    > > capability (pP' here) is raised. In the case that you cite here,
    > > the fact that pP' is 1 implies that the process is permitted to raise
    > > its pE' with a system call.
    >
    > So "nobody" gets to use the "remove any file" capability.
    > IMHO it would be nice to be able to stop that.

    The question you originally posed was one of a "setuid" remove script.
    In the current non-capability model, there is no protection against
    'nobody' running it. None besides straigt forward file
    permission/ownership -- as Astor points out.

    > Considering users as:
    >
    > a. authorized to use the capability as desired
    > b. limited by tools & not expected to find holes in the tools
    > c. possibly serious crackers who are likely to look for holes

    > User "nobody" is in group c, and should not be able to
    > execute tools with such power.

    > > If your claim is that when the cleanme.tool runs it will fail to
    > > execute the unlink() operation on files it doesn't own, I hope I've
    > > cleared that up.
    >
    > Just the opposite: the user must not have access to tools with
    > that kind of power because the tools might be buggy.

    The capability model has nothing to say about people's programming
    (in)ability.

    > I'm thinking of the shell removing files. The closest I can imagine
    > is with redirection. Would that fail? Maybe it is good, but it
    > doesn't seem very compatible.

    I have absolutely no idea what you mean by this since I have already
    explained how 'rm' can be safely implemented in this model.


    Andrew

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