From: Jason Cooper <jason@lakedaemon.net>
To: Kees Cook <keescook@chromium.org>
Cc: Thomas Garnier <thgarnie@google.com>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Ingo Molnar <mingo@kernel.org>, Andy Lutomirski <luto@kernel.org>,
"x86@kernel.org" <x86@kernel.org>, Borislav Petkov <bp@suse.de>,
Baoquan He <bhe@redhat.com>, Yinghai Lu <yinghai@kernel.org>,
Juergen Gross <jgross@suse.com>,
Matt Fleming <matt@codeblueprint.co.uk>,
Toshi Kani <toshi.kani@hpe.com>,
Andrew Morton <akpm@linux-foundation.org>,
Dan Williams <dan.j.williams@intel.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Xiao Guangrong <guangrong.xiao@linux.intel.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
Alexander Kuleshov <kuleshovmail@gmail.com>,
Alexander Popov <alpopov@ptsecurity.com>,
Dave Young <dyoung@redhat.com>, Joerg Roedel <jroedel@suse.de>,
Lv Zheng <lv.zheng@intel.com>, Mark Salter <msalter@redhat.com>,
Dmitry Vyukov <dvyukov@google.com>,
Stephen Smalley <sds@tycho.nsa.gov>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
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LKML <linux-kernel@vger.kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>
Subject: Re: [kernel-hardening] [PATCH v7 0/9] x86/mm: memory area address KASLR
Date: Thu, 23 Jun 2016 19:33:58 +0000 [thread overview]
Message-ID: <20160623193358.GL9922@io.lakedaemon.net> (raw)
In-Reply-To: <CAGXu5jK_42d+jkPr4Ck0iL52-ignY9gq-eUZ73_YuhKJERrRxA@mail.gmail.com>
Hey Kees, Thomas,
On Wed, Jun 22, 2016 at 10:05:51AM -0700, Kees Cook wrote:
> On Wed, Jun 22, 2016 at 8:59 AM, Thomas Garnier <thgarnie@google.com> wrote:
> > On Wed, Jun 22, 2016 at 5:47 AM, Jason Cooper <jason@lakedaemon.net> wrote:
> >> Hey Kees,
> >>
> >> On Tue, Jun 21, 2016 at 05:46:57PM -0700, Kees Cook wrote:
> >>> Notable problems that needed solving:
> >> ...
> >>> - Reasonable entropy is needed early at boot before get_random_bytes()
> >>> is available.
> >>
> >> This series is targetting x86, which typically has RDRAND/RDSEED
> >> instructions. Are you referring to other arches? Older x86? Also,
> >> isn't this the same requirement for base address KASLR?
> >>
> >> Don't get me wrong, I want more diverse entropy sources available
> >> earlier in the boot process as well. :-) I'm just wondering what's
> >> different about this series vs base address KASLR wrt early entropy
> >> sources.
> >>
> >
> > I think Kees was referring to the refactor I did to get the similar
> > entropy generation than KASLR module randomization. Our approach was
> > to provide best entropy possible even if you have an older processor
> > or under virtualization without support for these instructions.
> > Unfortunately common on companies with a large number of older
> > machines.
>
> Right, the memory offset KASLR uses the same routines as the kernel
> base KASLR. The issue is with older x86 systems, which continue to be
> very common.
We have the same issue in embedded. :-( Compounded by the fact that
there is no rand instruction (at least not on ARM). So, even if there's
a HW-RNG, you can't access it until the driver is loaded.
This is compounded by the fact that most systems deployed today have
bootloaders a) without hw-rng drivers, b) without dtb editing, and c)
without dtb support at all.
My current thinking is to add a devicetree property
"userspace,random-seed" <address, len>. This way, existing, deployed
boards can append a dtb to a modern kernel with the property set.
The factory bootloader then only needs to amend its boot scripts to read
random-seed from the fs to the given address.
Modern systems that receive a seed from the bootloader via the
random-seed property (typically from the hw-rng) can mix both sources
for increased resilience.
Unfortunately, I'm not very familiar with the internals of x86
bootstrapping. Could GRUB be scripted to do a similar task? How would
the address and size of the seed be passed to the kernel? command line?
thx,
Jason.
next prev parent reply other threads:[~2016-06-23 19:33 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-22 0:46 [kernel-hardening] [PATCH v7 0/9] x86/mm: memory area address KASLR Kees Cook
2016-06-22 0:46 ` [kernel-hardening] [PATCH v7 1/9] x86/mm: Refactor KASLR entropy functions Kees Cook
2016-06-22 0:46 ` [kernel-hardening] [PATCH v7 2/9] x86/mm: Update physical mapping variable names (x86_64) Kees Cook
2016-06-22 0:47 ` [kernel-hardening] [PATCH v7 3/9] x86/mm: PUD VA support for physical mapping (x86_64) Kees Cook
2016-06-22 0:47 ` [kernel-hardening] [PATCH v7 4/9] x86/mm: Separate variable for trampoline PGD (x86_64) Kees Cook
2016-06-22 0:47 ` [kernel-hardening] [PATCH v7 5/9] x86/mm: Implement ASLR for kernel memory regions (x86_64) Kees Cook
2016-06-22 0:47 ` [kernel-hardening] [PATCH v7 6/9] x86/mm: Enable KASLR for physical mapping memory region (x86_64) Kees Cook
2016-06-22 0:47 ` [kernel-hardening] [PATCH v7 7/9] x86/mm: Enable KASLR for vmalloc " Kees Cook
2016-06-22 0:47 ` [kernel-hardening] [PATCH v7 8/9] x86/mm: Enable KASLR for vmemmap " Kees Cook
2016-06-22 0:47 ` [kernel-hardening] [PATCH v7 9/9] x86/mm: Memory hotplug support for KASLR memory randomization (x86_64) Kees Cook
2016-06-22 12:47 ` [kernel-hardening] [PATCH v7 0/9] x86/mm: memory area address KASLR Jason Cooper
2016-06-22 15:59 ` Thomas Garnier
2016-06-22 17:05 ` Kees Cook
2016-06-23 19:33 ` Jason Cooper [this message]
2016-06-23 19:45 ` Sandy Harris
2016-06-23 19:59 ` Kees Cook
2016-06-23 20:19 ` Jason Cooper
2016-06-23 20:16 ` Jason Cooper
2016-06-23 19:58 ` Kees Cook
2016-06-23 20:05 ` Ard Biesheuvel
2016-06-24 1:11 ` Jason Cooper
2016-06-24 10:54 ` Ard Biesheuvel
2016-06-24 16:02 ` [kernel-hardening] devicetree random-seed properties, was: "Re: [PATCH v7 0/9] x86/mm: memory area address KASLR" Jason Cooper
2016-06-24 19:04 ` [kernel-hardening] " Kees Cook
2016-06-24 20:40 ` Andy Lutomirski
2016-06-30 21:48 ` Jason Cooper
2016-06-30 21:56 ` Thomas Garnier
2016-06-30 21:48 ` Jason Cooper
2016-07-07 22:24 ` [kernel-hardening] Re: [PATCH v7 0/9] x86/mm: memory area address KASLR Kees Cook
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