Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Thu, 29 Aug 2019 09:57:20 +0800
From: Jason Yan <yanaijie@...wei.com>
To: Scott Wood <oss@...error.net>, <mpe@...erman.id.au>,
	<linuxppc-dev@...ts.ozlabs.org>, <diana.craciun@....com>,
	<christophe.leroy@....fr>, <benh@...nel.crashing.org>, <paulus@...ba.org>,
	<npiggin@...il.com>, <keescook@...omium.org>,
	<kernel-hardening@...ts.openwall.com>
CC: <wangkefeng.wang@...wei.com>, <linux-kernel@...r.kernel.org>,
	<jingxiangfeng@...wei.com>, <zhaohongjiang@...wei.com>,
	<thunder.leizhen@...wei.com>, <fanchengyang@...wei.com>, <yebin10@...wei.com>
Subject: Re: [PATCH v6 00/12] implement KASLR for powerpc/fsl_booke/32



On 2019/8/28 12:05, Scott Wood wrote:
> On Fri, 2019-08-09 at 18:07 +0800, Jason Yan wrote:
>> This series implements KASLR for powerpc/fsl_booke/32, as a security
>> feature that deters exploit attempts relying on knowledge of the location
>> of kernel internals.
>>
>> Since CONFIG_RELOCATABLE has already supported, what we need to do is
>> map or copy kernel to a proper place and relocate.
> 
> Have you tested this with a kernel that was loaded at a non-zero address?  I
> tried loading a kernel at 0x04000000 (by changing the address in the uImage,
> and setting bootm_low to 04000000 in U-Boot), and it works without
> CONFIG_RANDOMIZE and fails with.
> 

Not yet. I will test this kind of cases in the next days. Thank you so
much. If there are any other corner cases that have to be tested, please
let me know.

>>   Freescale Book-E
>> parts expect lowmem to be mapped by fixed TLB entries(TLB1). The TLB1
>> entries are not suitable to map the kernel directly in a randomized
>> region, so we chose to copy the kernel to a proper place and restart to
>> relocate.
>>
>> Entropy is derived from the banner and timer base, which will change every
>> build and boot. This not so much safe so additionally the bootloader may
>> pass entropy via the /chosen/kaslr-seed node in device tree.
> 
> How complicated would it be to directly access the HW RNG (if present) that
> early in the boot?  It'd be nice if a U-Boot update weren't required (and
> particularly concerning that KASLR would appear to work without a U-Boot
> update, but without decent entropy).
> 
> -Scott
> 
> 
> 
> .
> 

Powered by blists - more mailing lists

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