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    SubjectRe: [PATCH 0/3] vfs: plug some holes involving LAST_BIND symlinks and file bind mounts (try #5)
    Hi!

    > > > > Consider FD passing over unix socket. Passing R/O file descriptor to
    > > > > the other task, then having the task write to the file is certainly bad.
    > > >
    > > > You've omitted the "R/O file descriptor of a file that is writable for
    > > > that other task" part...
    > >
    > > That is 666 for the other task. But the other task can't access it due
    > > to directory being 700 or something. Your fchdir() argument does not
    > > apply here.
    >
    > *snort*
    >
    > What you are advocating is a very limited class of setups that might be
    > usable for protecting files if not for the existing behaviour on a shitload
    > of systems.
    >
    > The thing is, that class *is* very limited. E.g. introduce links and it's
    > fallen apart. Introduce bindings and the same will happen. Just try to
    > extend it one level deeper and fchdir() will bite you, etc. All of that
    > is not dependent on procfs even being there.
    >
    > Access rights belong to file, not to a pathname (and there's no such thing
    > as _the_ pathname of a file).
    >
    > I'd buy that as a minor QoI issue; as a security one - no way.

    Ok, so you see it as a (QoI) problem, but not too major. Good; I hope
    it gets fixed one day.
    Pavel
    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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