* Andrew Morton ([email protected]) wrote:
> Chris Wright <[email protected]> wrote:
> > Catherine, the security_sid_to_context() is a raw SELinux function which
> > crept into core code and should not have been there. The fallout fixes
> > included conditionally exporting security_sid_to_context, and finally
> > scm_send/recv unlining.
>
> Yes. So we're OK up the uninlining, right?
Yes, although sid_to_context is meant to be analog to the other
get_peersec calls, and should really be made a proper part of the
interface (can be done later, correctness is the issue at hand).
> > The end result in -mm looks broken to me.
> > Specifically, it now does:
> >
> > ucred->uid = tsk->uid;
> > ucred->gid = tsk->gid;
> > ucred->pid = tsk->tgid;
> > scm->fp = NULL;
> > scm->seq = 0;
> > if (msg->msg_controllen <= 0)
> > return 0;
> >
> > scm->sid = security_sk_sid(sock->sk, NULL, 0);
> >
> > The point of Catherine's original patch was to make sure there's always
> > a security identifier associated with AF_UNIX messages. So receiver
> > can always check it (same as having credentials even w/out sender
> > control message passing them). Now we will have garbage for sid.
>
> This answers the question I've been asking all and sundry for a week, thanks ;)
> So:
>
> - scm-fold-__scm_send-into-scm_send.patch is OK
Yes.
> - scm_send-speedup.patch is wrong
Yes.
> - Catherine's patch introduces a possibly-significant performance
> problem: we're now calling the expensive-on-SELinux security_sk_sid()
> more frequently than we used to.
I don't expect security_sk_sid() to be terribly expensive. It's not
an AVC check, it's just propagating a label. But I've not done any
benchmarking on that.
thanks,
-chris
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