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

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Message-ID: <202402221309.79CE163C@keescook>
Date: Thu, 22 Feb 2024 13:10:00 -0800
From: Kees Cook <keescook@...omium.org>
To: Tycho Andersen <tycho@...ho.pizza>
Cc: "Tobin C. Harding" <me@...in.cc>, Greg KH <gregkh@...uxfoundation.org>,
	Guixiong Wei <guixiongwei@...il.com>,
	linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] leaking_addresses: Provide mechanism to scan binary files

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@...omium.org>
> > 
> > Patch itself is
> > 
> > Reviewed-by: Tycho Andersen <tandersen@...flix.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