From: Scott Wood <oss@buserror.net>
To: Daniel Axtens <dja@axtens.net>, 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: linux-kernel@vger.kernel.org, zhaohongjiang@huawei.com
Subject: Re: [PATCH v3 0/6] implement KASLR for powerpc/fsl_booke/64
Date: Wed, 04 Mar 2020 15:21:21 -0600 [thread overview]
Message-ID: <d673649d6f371e82d4a94ba62bfd0d44efeca7b4.camel@buserror.net> (raw)
In-Reply-To: <87tv3drf79.fsf@dja-thinkpad.axtens.net>
On Wed, 2020-02-26 at 18:16 +1100, Daniel Axtens wrote:
> Hi Jason,
>
> > This is a try to implement KASLR for Freescale BookE64 which is based on
> > my earlier implementation for Freescale BookE32:
> > https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=131718
> >
> > The implementation for Freescale BookE64 is similar as BookE32. One
> > difference is that Freescale BookE64 set up a TLB mapping of 1G during
> > booting. Another difference is that ppc64 needs the kernel to be
> > 64K-aligned. So we can randomize the kernel in this 1G mapping and make
> > it 64K-aligned. This can save some code to creat another TLB map at
> > early boot. The disadvantage is that we only have about 1G/64K = 16384
> > slots to put the kernel in.
> >
> > KERNELBASE
> >
> > 64K |--> kernel <--|
> > | | |
> > +--+--+--+ +--+--+--+--+--+--+--+--+--+ +--+--+
> > | | | |....| | | | | | | | | |....| | |
> > +--+--+--+ +--+--+--+--+--+--+--+--+--+ +--+--+
> > | | 1G
> > |-----> offset <-----|
> >
> > kernstart_virt_addr
> >
> > I'm not sure if the slot numbers is enough or the design has any
> > defects. If you have some better ideas, I would be happy to hear that.
> >
> > Thank you all.
> >
>
> Are you making any attempt to hide kernel address leaks in this series?
> I've just been looking at the stackdump code just now, and it directly
> prints link registers and stack pointers, which is probably enough to
> determine the kernel base address:
>
> SPs: LRs: %pS pointer
> [ 0.424506] [c0000000de403970] [c000000001fc0458] dump_stack+0xfc/0x154
> (unreliable)
> [ 0.424593] [c0000000de4039c0] [c000000000267eec] panic+0x258/0x5ac
> [ 0.424659] [c0000000de403a60] [c0000000024d7a00]
> mount_block_root+0x634/0x7c0
> [ 0.424734] [c0000000de403be0] [c0000000024d8100]
> prepare_namespace+0x1ec/0x23c
> [ 0.424811] [c0000000de403c60] [c0000000024d7010]
> kernel_init_freeable+0x804/0x880
>
> git grep \\\"REG\\\" arch/powerpc shows a few other uses like this, all
> in process.c or in xmon.
>
> Maybe replacing the REG format string in KASLR mode would be sufficient?
Whatever we decide to do here, it's not book3e-specific so it should be
considered separately from these patches.
-Scott
next prev parent reply other threads:[~2020-03-04 21:25 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-06 2:58 [PATCH v3 0/6] implement KASLR for powerpc/fsl_booke/64 Jason Yan
2020-02-06 2:58 ` [PATCH v3 1/6] powerpc/fsl_booke/kaslr: refactor kaslr_legal_offset() and kaslr_early_init() Jason Yan
2020-02-20 13:40 ` Christophe Leroy
2020-02-26 2:11 ` Jason Yan
2020-02-06 2:58 ` [PATCH v3 2/6] powerpc/fsl_booke/64: introduce reloc_kernel_entry() helper Jason Yan
2020-02-20 13:41 ` Christophe Leroy
2020-02-06 2:58 ` [PATCH v3 3/6] powerpc/fsl_booke/64: implement KASLR for fsl_booke64 Jason Yan
2020-02-20 13:48 ` Christophe Leroy
2020-02-26 2:40 ` Jason Yan
2020-02-26 3:33 ` Jason Yan
2020-02-26 5:04 ` [RFC PATCH] Use IS_ENABLED() instead of #ifdefs Christophe Leroy
2020-02-26 6:26 ` Jason Yan
2020-02-26 5:10 ` [PATCH v3 3/6] powerpc/fsl_booke/64: implement KASLR for fsl_booke64 Christophe Leroy
2020-02-26 5:08 ` Christophe Leroy
2020-03-04 21:44 ` Scott Wood
2020-03-05 2:32 ` Jason Yan
2020-02-06 2:58 ` [PATCH v3 4/6] powerpc/fsl_booke/64: do not clear the BSS for the second pass Jason Yan
2020-03-04 21:49 ` Scott Wood
2020-03-05 3:14 ` Jason Yan
2020-02-06 2:58 ` [PATCH v3 5/6] powerpc/fsl_booke/64: clear the original kernel if randomized Jason Yan
2020-02-20 13:49 ` Christophe Leroy
2020-02-26 2:44 ` Jason Yan
2020-03-04 21:53 ` Scott Wood
2020-03-05 3:20 ` Jason Yan
2020-02-06 2:58 ` [PATCH v3 6/6] powerpc/fsl_booke/kaslr: rename kaslr-booke32.rst to kaslr-booke.rst and add 64bit part Jason Yan
2020-02-20 13:50 ` Christophe Leroy
2020-02-26 2:46 ` Jason Yan
2020-02-13 3:00 ` [PATCH v3 0/6] implement KASLR for powerpc/fsl_booke/64 Jason Yan
2020-02-20 3:33 ` Jason Yan
2020-02-26 7:16 ` Daniel Axtens
2020-02-26 8:18 ` Jason Yan
2020-02-26 11:41 ` Daniel Axtens
2020-02-27 1:55 ` Jason Yan
2020-02-28 5:53 ` Scott Wood
2020-02-28 6:47 ` Jason Yan
2020-02-29 4:28 ` Scott Wood
2020-02-29 7:27 ` Jason Yan
2020-02-29 22:54 ` Scott Wood
2020-03-02 2:17 ` Jason Yan
2020-03-02 3:24 ` Scott Wood
2020-03-02 7:12 ` Jason Yan
2020-03-02 8:47 ` Scott Wood
2020-03-02 9:37 ` Jason Yan
2020-03-04 21:21 ` Scott Wood [this message]
2020-03-05 3:22 ` Jason Yan
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