From: Oscar Carter <oscar.carter@gmx.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Oscar Carter <oscar.carter@gmx.com>,
Ingo Molnar <mingo@redhat.com>, Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com, Jann Horn <jannh@google.com>
Subject: Re: [PATCH v2 2/2] kernel/trace: Remove function callback casts
Date: Fri, 24 Jul 2020 19:24:03 +0200 [thread overview]
Message-ID: <20200724172403.GC3123@ubuntu> (raw)
In-Reply-To: <20200724171418.GB3123@ubuntu>
Hi Steven,
On Fri, Jul 24, 2020 at 07:14:18PM +0200, Oscar Carter wrote:
> On Fri, Jul 24, 2020 at 12:35:28PM -0400, Steven Rostedt wrote:
> > On Fri, 24 Jul 2020 18:19:21 +0200
> > Oscar Carter <oscar.carter@gmx.com> wrote:
> >
> > > > The linker trick is far less intrusive, and I believe less error prone.
> > >
> > > If we use the linker trick, the warning -Wcast-function-type dissapears,
> > > but in a way that makes impossible to the compiler to get the necessary
> > > info about function prototypes to insert the commented check. As far I
> > > know, this linker trick (redirection of a function) is hidden for the
> > > CFI build.
> > >
> > > So, in my opinion, the linker trick is not suitable if we want to protect
> > > the function pointers of the ftrace subsystem against an attack that
> > > modifiy the normal flow of the kernel.
> >
> > The linker trick should only affect architectures that don't implement
> > the needed features. I can make it so the linker trick is only applied
> > to those archs, and other archs that want more protection only need to
> > add these features to their architectures.
> >
> > It's much less intrusive than this patch.
>
> Sorry, but I don't understand your proposal. What features an arch need to
> add if want the CFI protection?
Typo correction.
Sorry, but I don't understand your proposal. What features does an arch need
to add if want the CFI protection?
>
> >
> > -- Steve
>
Thanks,
Oscar Carter
next prev parent reply other threads:[~2020-07-24 17:24 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-19 15:50 [PATCH v2 0/2] kernel/trace: Remove function callback casts Oscar Carter
2020-07-19 15:50 ` [PATCH v2 1/2] kernel/trace: Prepare to remove " Oscar Carter
2020-07-19 15:50 ` [PATCH v2 2/2] kernel/trace: Remove " Oscar Carter
2020-07-21 18:05 ` Steven Rostedt
2020-07-24 16:19 ` Oscar Carter
2020-07-24 16:35 ` Steven Rostedt
2020-07-24 17:14 ` Oscar Carter
2020-07-24 17:24 ` Oscar Carter [this message]
2020-07-24 17:36 ` Steven Rostedt
2020-07-24 17:40 ` Steven Rostedt
2020-07-24 17:48 ` Steven Rostedt
2020-07-24 17:55 ` Oscar Carter
2020-07-24 18:34 ` Steven Rostedt
2020-07-25 15:09 ` Oscar Carter
2020-07-25 15:19 ` Oscar Carter
2020-07-26 15:52 ` Oscar Carter
2020-07-27 13:53 ` Steven Rostedt
2020-07-31 14:41 ` Oscar Carter
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