Re: [PATCH] leaking_addresses: Provide mechanism to scan binary files

Kees Cook
2024-02-22T21:10:05Z

On Thu, Feb 22, 2024 at 01:00:40PM -0800, Kees Cook wrote:
> On Thu, Feb 22, 2024 at 08:24:02AM -0700, Tycho Andersen wrote:
> > Hi Kees,
> >
> > On Sun, Feb 18, 2024 at 09:38:12AM -0800, Kees Cook wrote:
> > > Introduce --kallsyms argument for scanning binary files for known symbol
> > > addresses. This would have found the exposure in /sys/kernel/notes:
> > >
> > > $ scripts/leaking_addresses.pl --kallsyms=<(sudo cat /proc/kallsyms)
> > > /sys/kernel/notes: hypercall_page @ 156
> > > /sys/kernel/notes: xen_hypercall_set_trap_table @ 156
> > > /sys/kernel/notes: startup_xen @ 132
> > >
> > > Signed-off-by: Kees Cook <keescook@chromium.org>
> >
> > Patch itself is
> >
> > Reviewed-by: Tycho Andersen <tandersen@netflix.com>
> >
> > And if you can carry it, that would be great (see below :).
>
> Sure!
>
> > This does bring up some interesting questions. From off-list
> > discussions with Tobin, I believe he is not particularly interested in
> > maintaining this script any more. I was never set up to do the PRs
> > myself, I agreed to be a reviewer to help Tobin out. I'm happy to
> > adopt it if that makes sense, but I'm curious about the future of the
> > script:
> >
> > 1. is it useful? (seems like yes if you're adding features)
>
> Yes, LKP runs it as part of 0-day, and it's found leaks in the past[1].
> (Though its usage could be improved.)
>
> > 2. does it make sense to live here as a separate thing? should we
> > perhaps run it as part of kselftests or similar? I think that e.g.
> > 681ff0181bbf ("x86/mm/init/32: Stop printing the virtual memory
> > layout") was not discovered with this script, but maybe if we put it
> > inline with some other stuff people regularly run more of these would
> > fall out? Maybe it makes sense to live somewhere else entirely
> > (syzkaller)? I can probably set up some x86/arm64 infra to run it
> > regularly, but that won't catch other less popular arches.
>
> We could certainly do that. It would need some work to clean it up,
> though -- it seems like it wasn't designed to run as root (which is how
> LKP runs it, and likely how at least some CIs would run it).

This is wrong -- it's not run as root. It was fall over very badly. I'm
not sure why the CI output looks strange.

--
Kees Cook