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    SubjectRe: [PATCH 0/2] file capabilities: two bugfixes

    --- "Serge E. Hallyn" <serue@us.ibm.com> wrote:

    > Quoting Casey Schaufler (casey@schaufler-ca.com):
    > >
    > > --- "Serge E. Hallyn" <serue@us.ibm.com> wrote:
    > >
    > > > ...
    > > > The other is that root can lose capabilities by
    > > > executing files with
    > > > only some capabilities set. The next two
    > patches
    > > > change these
    > > > behaviors.
    > >
    > > It was the intention of the POSIX group that
    > > capabilities be independent of uid. I would
    > > argue that the old bevavior was correct, that
    > > a program marked to lose a capability ought
    > > to even if the uid is 0.
    >
    > Agreed, and if SECURE_NOROOT is set, that is what
    > happens.
    > But by default SECURE_NOROOT is not set, in which
    > case linux's
    > implementation of capabilities behaves differently
    > for root.
    >
    > Without this latest patch, with SECURE_NOROOT not
    > set, what was
    > actually happening was that the kernel behaved as
    > though
    > SECURE_NOROOT was not set so long as there was no
    > security.capability xattr, and always behaved as
    > though
    > SECURE_NOROOT was set if there was an xattr. That's
    > inconsistent
    > and confusing behavior.
    >
    > The worst part is that root can get around running
    > the code
    > with limited caps by just copying the file and
    > running the
    > copy. So it adds no security benefit, and adds an
    > inconsistency/complication which could cause
    > security risks.

    OK, no worries then.


    Casey Schaufler
    casey@schaufler-ca.com
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