From: Scott Wood <oss@buserror.net>
To: Jason Yan <yanaijie@huawei.com>,
mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org,
diana.craciun@nxp.com, christophe.leroy@c-s.fr,
benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com,
keescook@chromium.org, kernel-hardening@lists.openwall.com
Cc: wangkefeng.wang@huawei.com, linux-kernel@vger.kernel.org,
jingxiangfeng@huawei.com, zhaohongjiang@huawei.com,
thunder.leizhen@huawei.com, fanchengyang@huawei.com,
yebin10@huawei.com
Subject: Re: [PATCH v6 00/12] implement KASLR for powerpc/fsl_booke/32
Date: Tue, 27 Aug 2019 23:59:56 -0500 [thread overview]
Message-ID: <143e5a85bc630d2bb0324114e78bedec8fbeb299.camel@buserror.net> (raw)
In-Reply-To: <a39b81562bcdeda7ffe0c2c29a60ff08c77047a6.camel@buserror.net>
On Tue, 2019-08-27 at 23:05 -0500, Scott Wood wrote:
> On Fri, 2019-08-09 at 18:07 +0800, Jason Yan wrote:
> > 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).
OK, I see that kaslr-seed is used on some other platforms, though arm64 aborts
KASLR if it doesn't get a seed. I'm not sure if that's better than a loud
warning message (or if it was a conscious choice rather than just not having
an alternative implemented), but silently using poor entropy for something
like this seems bad.
-Scott
next prev parent reply other threads:[~2019-08-29 12:05 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-09 10:07 [PATCH v6 00/12] implement KASLR for powerpc/fsl_booke/32 Jason Yan
2019-08-09 10:07 ` [PATCH v6 01/12] powerpc: unify definition of M_IF_NEEDED Jason Yan
2019-08-09 10:07 ` [PATCH v6 02/12] powerpc: move memstart_addr and kernstart_addr to init-common.c Jason Yan
2019-08-09 10:07 ` [PATCH v6 03/12] powerpc: introduce kernstart_virt_addr to store the kernel base Jason Yan
2019-08-09 10:07 ` [PATCH v6 04/12] powerpc/fsl_booke/32: introduce create_tlb_entry() helper Jason Yan
2019-08-27 22:07 ` Scott Wood
2019-08-28 5:33 ` Jason Yan
2019-08-09 10:07 ` [PATCH v6 05/12] powerpc/fsl_booke/32: introduce reloc_kernel_entry() helper Jason Yan
2019-08-09 10:07 ` [PATCH v6 06/12] powerpc/fsl_booke/32: implement KASLR infrastructure Jason Yan
2019-08-28 4:54 ` Scott Wood
2019-08-28 5:47 ` Christophe Leroy
2019-08-29 6:26 ` Jason Yan
2019-08-28 11:03 ` Jason Yan
2019-08-28 16:44 ` Scott Wood
2019-08-09 10:07 ` [PATCH v6 07/12] powerpc/fsl_booke/32: randomize the kernel image offset Jason Yan
2019-08-09 10:07 ` [PATCH v6 08/12] powerpc/fsl_booke/kaslr: clear the original kernel if randomized Jason Yan
2019-08-09 10:07 ` [PATCH v6 09/12] powerpc/fsl_booke/kaslr: support nokaslr cmdline parameter Jason Yan
2019-08-09 10:07 ` [PATCH v6 10/12] powerpc/fsl_booke/kaslr: dump out kernel offset information on panic Jason Yan
2019-08-09 10:07 ` [PATCH v6 11/12] powerpc/fsl_booke/kaslr: export offset in VMCOREINFO ELF notes Jason Yan
2019-08-09 10:08 ` [PATCH v6 12/12] powerpc/fsl_booke/32: Document KASLR implementation Jason Yan
2019-08-19 6:12 ` [PATCH v6 00/12] implement KASLR for powerpc/fsl_booke/32 Jason Yan
2019-08-27 0:39 ` Jason Yan
2019-08-27 1:33 ` Michael Ellerman
2019-08-28 5:08 ` Scott Wood
2019-08-28 13:01 ` Michael Ellerman
2019-08-28 4:05 ` Scott Wood
2019-08-28 4:59 ` Scott Wood [this message]
2019-08-29 2:41 ` Jason Yan
2019-08-29 1:57 ` Jason Yan
2019-09-10 5:34 ` Jason Yan
2019-09-14 14:28 ` Scott Wood
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