Re: [PATCH] seccomp: add ptrace commands for suspend/resume

On Tue, Jun 02, 2015 at 08:48:48PM +0200, Oleg Nesterov wrote:

On 06/02, Tycho Andersen wrote:

quoted

quoted

Do we need to re-enable seccomp if a tracer detaches unexpectedly.
CRIU can be killed and we should try to not affect the task state even
in this case.

Yes, I think Pavel's suggestion on the CRIU list of simply
automatically re-enabling seccomp on ptrace detach

But note that you can't enable tsc if the tracer dies, in this case
the tracee can be running.

Yes, this does complicate things. I think I'll get rid of the TSC
manipulation, since it's not clear to me how to resolve this. (I do
think it makes the API slightly incomplete, though, so suggestions how
to resolve it would be welcome.)

Otherwise, if we use PTRACE_O_ instead, it goes away automatically if
the tracer dies or does PTRACE_DETACH.

IIRC the flag goes away, but we still have to do something in
__ptrace_unlink to clear the seccomp suspended, so I'm not sure if the
automatic-ness helps us.

Tycho