On 08/18, Roland McGrath wrote:
>
> > In particular, this means that
> >
> > if (event || (clone_flags & CLONE_PTRACE)) {
> > child_engine = utrace_attach_task(child, UTRACE_ATTACH_CREATE
> > ...
> >
> > is not right. CLONE_PTRACE should be ignored unless task_ptrace(current).
> Yes. But we attach to parent->parent, not to parent == current.
Ah yes, I see your point.
> In short: ptrace_report_clone() should "copy" the tracing state from
> current to child when needed. And it should never attach if current
> is not traced.
Correct.
> In particular, this means that
>
On 08/17, Roland McGrath wrote:
>
> > In that case it can share the code with ptrace_traceme().
>
> I'm not sure I quite follow that. Both PTRACE_TRACEME and PTRACE_ATTACH
> paths have to interlock with each other. Auto-tracing in report_clone
> doesn't have to worry about that at all, because of
> Note: we attach the new engine unconditionally, before security check.
> Not good, another task can do ptrace_attach() and get EPERM. Hopefully
> we can live with this race, or somehow fix it later.
I don't think we can accept that and call it non-regressing.
But we can worry about it later.
>
Change ptrace_traceme() to use the new helpers. Kill the now unused
prepare_ptrace_attach/finish_ptrace_attach.
finish_ptrace_attach(ret) logic was wrong. If ->parent has PF_EXITING
we must UTRACE_DETACH but ret == 0. Fix this.
Note: we attach the new engine unconditionally, before security check
