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From: "Tobin C. Harding" <me@tobin.cc>
To: Kaiwan N Billimoria <kaiwan@kaiwantech.com>
Cc: Kees Cook <keescook@chromium.org>,
	kernel-hardening@lists.openwall.com,
	LKML <linux-kernel@vger.kernel.org>,
	Network Development <netdev@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Tycho Andersen <tycho@tycho.ws>
Subject: Re: [kernel-hardening] Re: [RFC 0/3] kallsyms: don't leak address when printing symbol
Date: Thu, 30 Nov 2017 10:58:34 +1100	[thread overview]
Message-ID: <20171129235834.GQ6217@eros> (raw)
In-Reply-To: <CAPDLWs8tJ5voge-gS-W+gxpRRk2GximPkGm1d9pxf5QNbCKufA@mail.gmail.com>

On Tue, Nov 28, 2017 at 08:58:44AM +0530, Kaiwan N Billimoria wrote:
> On Tue, Nov 28, 2017 at 7:20 AM, Tobin C. Harding <me@tobin.cc> wrote:
> >
> > Noob question: how do we _know_ this. In other words how do we know no
> > userland tools rely on the current behaviour? No stress to answer Kees,
> > this is a pretty general kernel dev question.
> 
> Perhaps I'm reading this wrong, but anyway: besides ftrace, kprobes
> will require a
> symbol-to-address lookup. Specifically, in the function
> kprobe_lookup_name() which
> in turn invokes kallsyms_lookup_name().

We should be right for this call chain because the patch doesn't touch
kallsyms_lookup_name().

> AFAIK, SystemTap (userland) is built on top of the kprobes infrastructure..

This actually indirectly answers the concern. Since no userland tool
should be looking up a kernel address the only code we can break is
kernel code.


thanks,
Tobin

      reply	other threads:[~2017-11-29 23:58 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-27 22:30 [RFC 0/3] kallsyms: don't leak address when printing symbol Tobin C. Harding
2017-11-27 22:30 ` [RFC 1/3] kallsyms: don't leak address when symbol not found Tobin C. Harding
2017-11-30  0:16   ` Tobin C. Harding
2017-11-27 22:30 ` [RFC 2/3] vsprintf: print <no-symbol> if " Tobin C. Harding
2017-11-27 22:30 ` [RFC 3/3] trace: print address " Tobin C. Harding
2017-11-28  0:52 ` [RFC 0/3] kallsyms: don't leak address when printing symbol Kees Cook
2017-11-28  1:50   ` Tobin C. Harding
2017-11-28  3:28     ` [kernel-hardening] " Kaiwan N Billimoria
2017-11-29 23:58       ` Tobin C. Harding [this message]

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