linux-kernel - Re: [PATCH] tracing: do not leak kernel addresses

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Date:   Fri, 27 Jul 2018 09:47:30 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Jann Horn <jannh@...gle.com>
Cc:     Golden_Miller83@...tonmail.ch,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Greg KH <greg@...ah.com>, Kees Cook <keescook@...gle.com>,
        salyzyn@...roid.com, kernel list <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, kernel-team@...roid.com,
        stable@...r.kernel.org,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH] tracing: do not leak kernel addresses

On Fri, 27 Jul 2018 15:40:32 +0200
Jann Horn <jannh@...gle.com> wrote:

> > > But the code doesn't go to dmesg. It's only available
> > > via /sys/kernel/debug/tracing/printk_formats which is only available
> > > via root. Nobody else has access to that directory.
> > >
> > > -- Steve  
> >
> > I think the point was that when we take capabilities into account the root
> > privileges aren't unequivocal anymore. The 'root' owned process with only
> > 'CAP_SYSLOG' shouldn't have access to /sys/kernel/debug/tracing/printk_formats  
> 
> Then they shouldn't have access to debugfs at all, right?

That's what I'm thinking.

-- Steve