linux-kernel - Re: [RFC PATCH 09/11] kallsyms: hide layout and expose seed

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Message-ID: <20200227024253.GA5707@MiWiFi-R3L-srv>
Date:   Thu, 27 Feb 2020 10:42:53 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Kees Cook <keescook@...omium.org>,
        Kristen Carlson Accardi <kristen@...ux.intel.com>,
        dyoung@...hat.com
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        arjan@...ux.intel.com, rick.p.edgecombe@...el.com, x86@...nel.org,
        linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
        kexec@...ts.infradead.org
Subject: Re: [RFC PATCH 09/11] kallsyms: hide layout and expose seed

On 02/06/20 at 09:51am, Kristen Carlson Accardi wrote:
> On Thu, 2020-02-06 at 04:32 -0800, Kees Cook wrote:

> > In the past, making kallsyms entirely unreadable seemed to break
> > weird
> > stuff in userspace. How about having an alternative view that just
> > contains a alphanumeric sort of the symbol names (and they will
> > continue
> > to have zeroed addresses for unprivileged users)?
> > 
> > Or perhaps we wait to hear about this causing a problem, and deal
> > with
> > it then? :)
> > 
> 
> Yeah - I don't know what people want here. Clearly, we can't leave
> kallsyms the way it is. Removing it entirely is a pretty fast way to
> figure out how people use it though :).

Kexec-tools and makedumpfile are the users of /proc/kallsyms currently. 
We use kallsyms to get page_offset_base and _stext.