linux-kernel - Re: [RFCv2] arm64: support HAVE_ARCH_RARE_WRITE and HAVE_ARCH_RARE_WRITE

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+kY741QCQsdFE5=B3KuagwhBdHO0FTQPFe3cT48caWVA@mail.gmail.com>
Date:   Thu, 30 Mar 2017 12:49:10 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     Hoeun Ryu <hoeun.ryu@...il.com>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>,
        Andy Lutomirski <luto@...nel.org>,
        PaX Team <pageexec@...email.hu>,
        Emese Revfy <re.emese@...il.com>,
        "x86@...nel.org" <x86@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Laura Abbott <labbott@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Steve Capper <steve.capper@....com>,
        Ganapatrao Kulkarni <gkulkarni@...iumnetworks.com>,
        James Morse <james.morse@....com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFCv2] arm64: support HAVE_ARCH_RARE_WRITE and HAVE_ARCH_RARE_WRITE_MEMCPY

On Thu, Mar 30, 2017 at 12:45 PM, Russell King - ARM Linux
<linux@...linux.org.uk> wrote:
> On Thu, Mar 30, 2017 at 12:38:15PM -0700, Kees Cook wrote:
>> Great work! I think this will need some further changes, though, since
>> it doesn't look to me like this would pass LKDTM's tests if it was
>> built as a module. (This is missing from my ARM attempt too... I
>> haven't figured out how to set the domain on the kernel modules...)
>
> You're not going to be able to do it very easily.  The only way I can
> think of achieving it would be to split the module area into one
> chunk for text, one chunk for write-rare and one chunk for data.

Well, my intention was to just make the entire module area
DOMAIN_WR_RARE. It's overly permissive in the sense that non-data
changes could be made, but this is already an improvement over either
not having this feature at all or x86's version which makes all of RAM
writable.

-Kees

-- 
Kees Cook
Pixel Security