linux-kernel - Re: [kernel-hardening] Re: [PATCH v2] mm: Add SLUB free list pointer obfuscation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAGXu5j+6Bq1YW9EPWGxjbz4bWWf7PvoKi5pbp6sNz8fvkq9ncw@mail.gmail.com>
Date:   Wed, 5 Jul 2017 16:30:56 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>
Cc:     Rik van Riel <riel@...hat.com>, Tycho Andersen <tycho@...ker.com>,
        Laura Abbott <labbott@...hat.com>,
        Daniel Micay <danielmicay@...il.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...nel.org>,
        Josh Triplett <josh@...htriplett.org>,
        Andy Lutomirski <luto@...nel.org>,
        Nicolas Pitre <nicolas.pitre@...aro.org>,
        Tejun Heo <tj@...nel.org>, Daniel Mack <daniel@...que.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Helge Deller <deller@....de>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux-MM <linux-mm@...ck.org>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>
Subject: Re: [kernel-hardening] Re: [PATCH v2] mm: Add SLUB free list pointer obfuscation

On Thu, Jun 29, 2017 at 10:56 AM, Tycho Andersen <tycho@...ker.com> wrote:
> On Thu, Jun 29, 2017 at 01:54:13PM -0400, Rik van Riel wrote:
>> On Thu, 2017-06-29 at 10:47 -0700, Kees Cook wrote:
>> > On Thu, Jun 29, 2017 at 10:05 AM, Christoph Lameter <cl@...ux.com>
>> > wrote:
>> > > On Sun, 25 Jun 2017, Kees Cook wrote:
>> > >
>> > > > The difference gets lost in the noise, but if the above is
>> > > > sensible,
>> > > > it's 0.07% slower. ;)
>> > >
>> > > Hmmm... These differences add up. Also in a repetative benchmark
>> > > like that
>> > > you do not see the impact that the additional cacheline use in the
>> > > cpu
>> > > cache has on larger workloads. Those may be pushed over the edge of
>> > > l1 or
>> > > l2 capacity at some point which then causes drastic regressions.
>> >
>> > Even if that is true, it may be worth it to some people to have the
>> > protection. Given that is significantly hampers a large class of heap
>> > overflow attacks[1], I think it's an important change to have. I'm
>> > not
>> > suggesting this be on by default, it's cleanly behind
>> > CONFIG-controlled macros, and is very limited in scope. If you can
>> > Ack
>> > it we can let system builders decide if they want to risk a possible
>> > performance hit. I'm pretty sure most distros would like to have this
>> > protection.
>>
>> I could certainly see it being useful for all kinds of portable
>> and network-connected systems where security is simply much
>> more important than performance.
>
> Indeed, I believe we would enable this in our kernels.

Andrew and Christoph,

What do you think about carrying this for -mm, since people are
interested in it and it's a very narrow change behind a config (with a
large impact on reducing the expoitability of freelist pointer
overwrites)?

-Kees

-- 
Kees Cook
Pixel Security