Messages in this thread | | | Date | Wed, 28 Oct 2020 15:00:44 -0700 | From | Kees Cook <> | Subject | Re: [seccomp] Request for a "enable on execve" mode for Seccomp filters |
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On Wed, Oct 28, 2020 at 01:42:13PM +0100, Jann Horn wrote: > +luto just in case he has opinions on this > > On Wed, Oct 28, 2020 at 12:18 PM Camille Mougey <commial@gmail.com> wrote: > > From my understanding, there is no way to delay the activation of > > seccomp filters, for instance "until an _execve_ call". > > [...] > > It would also ensure there is only one thread running > > at the filter enabling time. > > You're alluding to cases where library constructor functions launch > threads? Is that a thing anyone does? (And in case someone does it, we > still have TSYNC, so I don't think this would be a real problem.)
Unfortunately, yes, it happens. TSYNC got designed specifically to "recapture" these constructor-launched threads. :( It was a common enough situation Chrome wanted to solve due to some weird GPU libraries that did this during init before Chrome was running.
-- Kees Cook
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