From: Daniel Axtens <dja@axtens.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,
oss@buserror.net
Cc: linux-kernel@vger.kernel.org, zhaohongjiang@huawei.com
Subject: Re: [PATCH v3 0/6] implement KASLR for powerpc/fsl_booke/64
Date: Wed, 26 Feb 2020 22:41:46 +1100 [thread overview]
Message-ID: <87r1yhr2x1.fsf@dja-thinkpad.axtens.net> (raw)
In-Reply-To: <8171d326-5138-4f5c-cff6-ad3ee606f0c2@huawei.com>
Jason Yan <yanaijie@huawei.com> writes:
> Hi Daniel,
>
> 在 2020/2/26 15:16, Daniel Axtens 写道:
>> 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?
>
> Yes.
>
>> 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.
>>
>
> Thanks for reminding this.
>
>> Maybe replacing the REG format string in KASLR mode would be sufficient?
>>
>
> Most archs have removed the address printing when dumping stack. Do we
> really have to print this?
>
> If we have to do this, maybe we can use "%pK" so that they will be
> hidden from unprivileged users.
I suspect that you will find it easier to convince people to accept a
change to %pK than removal :)
BTW, I have a T4240RDB so I might be able to test this series at some
point - do I need an updated bootloader to pass in a random seed, or is
the kernel able to get enough randomness by itself? (Sorry if this is
explained elsewhere in the series, I have only skimmed it lightly!)
Regards,
Daniel
>
> Thanks,
> Jason
>
>> Regards,
>> Daniel
>>
>>
>>> v2->v3:
>>> Fix build error when KASLR is disabled.
>>> v1->v2:
>>> Add __kaslr_offset for the secondary cpu boot up.
>>>
>>> Jason Yan (6):
>>> powerpc/fsl_booke/kaslr: refactor kaslr_legal_offset() and
>>> kaslr_early_init()
>>> powerpc/fsl_booke/64: introduce reloc_kernel_entry() helper
>>> powerpc/fsl_booke/64: implement KASLR for fsl_booke64
>>> powerpc/fsl_booke/64: do not clear the BSS for the second pass
>>> powerpc/fsl_booke/64: clear the original kernel if randomized
>>> powerpc/fsl_booke/kaslr: rename kaslr-booke32.rst to kaslr-booke.rst
>>> and add 64bit part
>>>
>>> .../{kaslr-booke32.rst => kaslr-booke.rst} | 35 +++++++--
>>> arch/powerpc/Kconfig | 2 +-
>>> arch/powerpc/kernel/exceptions-64e.S | 23 ++++++
>>> arch/powerpc/kernel/head_64.S | 14 ++++
>>> arch/powerpc/kernel/setup_64.c | 4 +-
>>> arch/powerpc/mm/mmu_decl.h | 19 ++---
>>> arch/powerpc/mm/nohash/kaslr_booke.c | 71 +++++++++++++------
>>> 7 files changed, 132 insertions(+), 36 deletions(-)
>>> rename Documentation/powerpc/{kaslr-booke32.rst => kaslr-booke.rst} (59%)
>>>
>>> --
>>> 2.17.2
>>
>> .
>>
next prev parent reply other threads:[~2020-02-26 11:41 UTC|newest]
Thread overview: 49+ 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 [this message]
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
2020-03-05 3:22 ` Jason Yan
2020-03-04 12:47 [PATCH] vfsprintf: only hash addresses in security environment Jason Yan
2020-03-04 18:34 ` Kees Cook
2020-03-04 21:11 ` [PATCH v3 0/6] implement KASLR for powerpc/fsl_booke/64 Scott Wood
2020-03-04 22:36 ` Kees Cook
2020-03-05 18:51 ` Linus Torvalds
2020-03-06 18:33 ` Scott Wood
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