Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Fri, 11 Aug 2017 08:09:04 -0700
From: Thomas Garnier <thgarnie@...gle.com>
To: Ingo Molnar <mingo@...nel.org>
Cc: Herbert Xu <herbert@...dor.apana.org.au>, "David S . Miller" <davem@...emloft.net>, 
	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com>, 
	Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...hat.com>, 
	Arnd Bergmann <arnd@...db.de>, Matthias Kaehlcke <mka@...omium.org>, 
	Boris Ostrovsky <boris.ostrovsky@...cle.com>, Juergen Gross <jgross@...e.com>, 
	Paolo Bonzini <pbonzini@...hat.com>, Radim Krčmář <rkrcmar@...hat.com>, 
	Joerg Roedel <joro@...tes.org>, Tom Lendacky <thomas.lendacky@....com>, 
	Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...e.de>, Brian Gerst <brgerst@...il.com>, 
	"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>, "Rafael J . Wysocki" <rjw@...ysocki.net>, 
	Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>, Tejun Heo <tj@...nel.org>, 
	Christoph Lameter <cl@...ux.com>, Paul Gortmaker <paul.gortmaker@...driver.com>, 
	Chris Metcalf <cmetcalf@...lanox.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	"Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>, Nicolas Pitre <nicolas.pitre@...aro.org>, 
	Christopher Li <sparse@...isli.org>, "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>, 
	Lukas Wunner <lukas@...ner.de>, Mika Westerberg <mika.westerberg@...ux.intel.com>, 
	Dou Liyang <douly.fnst@...fujitsu.com>, Daniel Borkmann <daniel@...earbox.net>, 
	Alexei Starovoitov <ast@...nel.org>, Masahiro Yamada <yamada.masahiro@...ionext.com>, 
	Markus Trippelsdorf <markus@...ppelsdorf.de>, Steven Rostedt <rostedt@...dmis.org>, 
	Kees Cook <keescook@...omium.org>, Rik van Riel <riel@...hat.com>, 
	David Howells <dhowells@...hat.com>, Waiman Long <longman@...hat.com>, Kyle Huey <me@...ehuey.com>, 
	Peter Foley <pefoley2@...oley.com>, Tim Chen <tim.c.chen@...ux.intel.com>, 
	Catalin Marinas <catalin.marinas@....com>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, 
	Michal Hocko <mhocko@...e.com>, Matthew Wilcox <mawilcox@...rosoft.com>, 
	"H . J . Lu" <hjl.tools@...il.com>, Paul Bolle <pebolle@...cali.nl>, Rob Landley <rob@...dley.net>, 
	Baoquan He <bhe@...hat.com>, Daniel Micay <danielmicay@...il.com>, 
	"the arch/x86 maintainers" <x86@...nel.org>, linux-crypto@...r.kernel.org, 
	LKML <linux-kernel@...r.kernel.org>, xen-devel@...ts.xenproject.org, 
	kvm list <kvm@...r.kernel.org>, Linux PM list <linux-pm@...r.kernel.org>, 
	linux-arch <linux-arch@...r.kernel.org>, linux-sparse@...r.kernel.org, 
	Kernel Hardening <kernel-hardening@...ts.openwall.com>, 
	Linus Torvalds <torvalds@...ux-foundation.org>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, 
	Borislav Petkov <bp@...en8.de>
Subject: Re: x86: PIE support and option to extend KASLR randomization

On Fri, Aug 11, 2017 at 5:41 AM, Ingo Molnar <mingo@...nel.org> wrote:
>
> * Thomas Garnier <thgarnie@...gle.com> wrote:
>
>> Changes:
>>  - v2:
>>    - Add support for global stack cookie while compiler default to fs without
>>      mcmodel=kernel
>>    - Change patch 7 to correctly jump out of the identity mapping on kexec load
>>      preserve.
>>
>> These patches make the changes necessary to build the kernel as Position
>> Independent Executable (PIE) on x86_64. A PIE kernel can be relocated below
>> the top 2G of the virtual address space. It allows to optionally extend the
>> KASLR randomization range from 1G to 3G.
>
> So this:
>
>  61 files changed, 923 insertions(+), 299 deletions(-)
>
> ... is IMHO an _awful_ lot of churn and extra complexity in pretty fragile pieces
> of code, to gain what appears to be only ~1.5 more bits of randomization!

The range increase is a way to use PIE right away.

>
> Do these changes get us closer to being able to build the kernel as truly position
> independent, i.e. to place it anywhere in the valid x86-64 address space? Or any
> other advantages?

Yes, PIE allows us to put the kernel anywhere in memory. It will allow
us to have a full randomized address space where position and order of
sections are completely random. There is still some work to get there
but being able to build a PIE kernel is a significant step.

>
> Thanks,
>
>         Ingo



-- 
Thomas

Powered by blists - more mailing lists

Your e-mail address:

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.