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

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Message-ID: <20180728000428.GI13922@thunk.org>
Date:   Fri, 27 Jul 2018 20:04:28 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Sandeep Patil <sspatil@...gle.com>
Cc:     Steven Rostedt <rostedt@...dmis.org>, Jann Horn <jannh@...gle.com>,
        salyzyn@...gle.com, Nick Desaulniers <ndesaulniers@...gle.com>,
        Golden_Miller83@...tonmail.ch, 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>,
        Jeffrey Vander Stoep <jeffv@...gle.com>
Subject: Re: [PATCH] tracing: do not leak kernel addresses

On Fri, Jul 27, 2018 at 03:05:43PM -0700, Sandeep Patil wrote:
> On Fri, Jul 27, 2018 at 04:21:14PM -0400, Theodore Y. Ts'o wrote:
> > On Fri, Jul 27, 2018 at 04:11:03PM -0400, Steven Rostedt wrote:
> > > That said, I would assume that
> > > other Android utilities are using other debugfs files for system
> > > status and such.
> 
> As of today, I think a lot of information in 'bugreports' is read
> out of debugfs (including things like binder stats). We do have a plan
> to change that.

Hmm, if it's only for bugreports, maybe it can be only mounted when
about root processes getting tricked into reading from debugfs.


> Indeed, I think it can. However, the problem is the last time I tried to
> remove this a whole bunch of things just broke. So, it wasn't about losing
> a functionality here and there. Agree, we need to clean up platform to not use
> debugfs first. Then we can expect Apps or other native processes to not rely
> on debugfs at all.

Is Android controlling access to debugfs files via SELinux?  If so,
then access to debugfs can be gradually cranked down as use cases are
removed.

						- Ted