From: Kees Cook <kees@ubuntu.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
James Morris <jmorris@namei.org>,
James Carter <jwcart2@tycho.nsa.gov>,
Eric Paris <eparis@redhat.com>,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov,
Stephen Smalley <sds@tycho.nsa.gov>,
spender@grsecurity.net, Daniel J Walsh <dwalsh@redhat.com>,
cl@linux-foundation.org, Arjan van de Ven <arjan@infradead.org>,
Chad Sellers <csellers@tresys.com>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
mingo@elte.hu
Subject: Re: mmap_min_addr and your local LSM (ok, just SELinux)
Date: Tue, 28 Jul 2009 08:56:22 -0700 [thread overview]
Message-ID: <20090728155622.GO7316@outflux.net> (raw)
In-Reply-To: <87zlapgo2u.fsf@basil.nowhere.org>
On Tue, Jul 28, 2009 at 11:21:29AM +0200, Andi Kleen wrote:
> Alan Cox <alan@lxorguk.ukuu.org.uk> writes:
>
> > A dumb question perhaps, but while addling my brain over the tty layer I
> > was wondering if for the specific case of jump through NULL (which seems
> > to be the most common but by no means only problem case that gets
> > exploited) is there any reason we can't set a default breakpoint for
>
> You mean a hardware breakpoint? Hardware break points are a precious
> scarce resource. The people who rely on them would be likely
> unhappy if you take one way from them.
Could the page table flags be used to mask this region? i.e. force
PROT_NONE (with the "desired" flags stored elsewhere) and in the segv
handler check if it is kernel or user space, and then fix-up the flags and
continue if it's userspace? (I really don't know the internals on this,
but it would need to restore PROT_NONE on task-switch or something...)
-Kees
--
Kees Cook
Ubuntu Security Team
next prev parent reply other threads:[~2009-07-28 16:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-20 23:23 mmap_min_addr and your local LSM (ok, just SELinux) Eric Paris
2009-07-21 0:14 ` Christopher Pardy
2009-07-21 13:41 ` Daniel J Walsh
2009-07-21 3:45 ` James Morris
2009-07-21 14:44 ` James Carter
2009-07-22 10:06 ` James Morris
2009-07-28 0:19 ` Alan Cox
2009-07-28 3:28 ` Kyle Moffett
2009-07-28 9:21 ` Andi Kleen
2009-07-28 10:00 ` Alan Cox
2009-07-28 11:21 ` Andi Kleen
2009-07-28 13:35 ` Brad Spengler
2009-07-28 14:48 ` Andi Kleen
2009-07-28 15:56 ` Kees Cook [this message]
2009-07-28 16:23 ` Andi Kleen
2009-07-21 3:48 ` Arjan van de Ven
2009-07-21 11:51 ` Brad Spengler
2009-07-21 4:13 ` Kyle McMartin
2009-07-21 11:31 ` Arnd Bergmann
2009-07-30 9:06 ` Pavel Machek
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