Re: [PATCH 13/20] signal: Implement force_fatal_sig

Kees Cook
2021-10-21T16:39:47Z

On Thu, Oct 21, 2021 at 11:33:43AM -0500, Eric W. Biederman wrote:
> Kees Cook <keescook@chromium.org> writes:
>
> > On Wed, Oct 20, 2021 at 12:43:59PM -0500, Eric W. Biederman wrote:
> >> This is interesting both because it makes force_sigsegv simpler and
> >> because there are a couple of buggy places in the kernel that call
> >> do_exit(SIGILL) or do_exit(SIGSYS) because there is no straight
> >> forward way today for those places to simply force the exit of a
> >> process with the chosen signal. Creating force_fatal_sig allows
> >> those places to be implemented with normal signal exits.
> >
> > I assume this is talking about seccomp()? :) Should a patch be included
> > in this series to change those?
>
> Actually it is not talking about seccomp. As far as I can tell seccomp
> is deliberately only killing a single thread when it calls do_exit.

Okay, I wasn't entirely sure, but yes, seccomp wants to keep the "kill
only 1 thread" option, which is weird, but useful for the threaded
seccomp monitor case.

> I am thinking about places where we really want the entire process to
> die and not just a single thread. Please see the following changes
> where I actually use force_fatal_sig.

Yeah, I saw that now. Thanks!

--
Kees Cook