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From: Yao Qi <yao.qi@arm.com>
To: Mark Rutland <mark.rutland@arm.com>,
	linux-arm-kernel@lists.infradead.org
Cc: arnd@arndb.de, catalin.marinas@arm.com,
	christoffer.dall@linaro.org, Dave.Martin@arm.com,
	jiong.wang@arm.com, kvmarm@lists.cs.columbia.edu,
	linux-arch@vger.kernel.org, marc.zyngier@arm.com,
	suzuki.poulose@arm.com, will.deacon@arm.com,
	linux-kernel@vger.kernel.org,
	kernel-hardening@lists.openwall.com
Subject: Re: [PATCH 00/11] ARMv8.3 pointer authentication userspace support
Date: Mon, 24 Jul 2017 12:52:12 +0100	[thread overview]
Message-ID: <46daaf0b-6b90-61cc-a25f-4177641d1613@arm.com> (raw)
In-Reply-To: <1500480092-28480-1-git-send-email-mark.rutland@arm.com>

On 19/07/17 17:01, Mark Rutland wrote:
> * Should the kernel remove PACs when unwinding user stacks?
>
>   This is simple to do, but it's arguably placing a policy in the kernel as to
>   what we expect user stacks to look like. Regardless, userspace will have to
>   perform this when unwinding with DWARF.

I am not sure what do you mean.  Do you mean stripping a PAC from a
pointer during unwinding, so that user space can unwind the program
without being aware of PAC?  Can kernel remove PAC from all instruction
pointers?  Note that user space debugger may try to unwind in coredump,
so if the contents dumped into coredump including PAC bits, debuggers
still have to be aware of PAC (unless kernel can remove all PAC bits
during coredump too).

IMO, kernel needs to tell the truth to reflect the process/task state
to the user space, and leave the user space to consume.
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  parent reply	other threads:[~2017-07-24 11:52 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-19 16:01 Mark Rutland
2017-07-19 16:01 ` [PATCH 01/11] arm64: docs: describe ELF hwcaps Mark Rutland
2017-07-21 17:05   ` Dave Martin
2017-07-24 10:47     ` Suzuki K Poulose
2017-08-03 14:49   ` Catalin Marinas
2017-08-03 17:57   ` Kees Cook
2017-07-19 16:01 ` [PATCH 02/11] asm-generic: mm_hooks: allow hooks to be overridden individually Mark Rutland
2017-07-19 16:01 ` [PATCH 03/11] arm64: add pointer authentication register bits Mark Rutland
2017-07-19 16:01 ` [PATCH 04/11] arm64/cpufeature: add ARMv8.3 id_aa64isar1 bits Mark Rutland
2017-07-24 10:54   ` Suzuki K Poulose
2017-07-19 16:01 ` [PATCH 05/11] arm64/cpufeature: detect pointer authentication Mark Rutland
2017-07-19 16:01 ` [PATCH 06/11] arm64: Don't trap host pointer auth use to EL2 Mark Rutland
2017-07-24 10:37   ` Dave Martin
2017-07-19 16:01 ` [PATCH 07/11] arm64: add basic pointer authentication support Mark Rutland
2017-07-25 15:26   ` Dave Martin
2017-08-11  7:46   ` Yao Qi
2017-08-11  8:45     ` Dave Martin
2017-07-19 16:01 ` [PATCH 08/11] arm64: expose user PAC bit positions via ptrace Mark Rutland
2017-07-19 16:01 ` [PATCH 09/11] arm64/kvm: preserve host HCR_EL2 value Mark Rutland
2017-08-01 11:00   ` Christoffer Dall
2017-07-19 16:01 ` [PATCH 10/11] arm64/kvm: context-switch ptrauth registers Mark Rutland
2017-08-01 11:00   ` Christoffer Dall
2017-08-01 14:26     ` Mark Rutland
2017-08-01 14:32       ` Will Deacon
2017-08-01 17:02       ` Christoffer Dall
2017-07-19 16:01 ` [PATCH 11/11] arm64: docs: document pointer authentication Mark Rutland
2017-07-21 17:05 ` [PATCH 00/11] ARMv8.3 pointer authentication userspace support Dave Martin
2017-07-25 12:06   ` Mark Rutland
2017-07-25 14:00     ` Jiong Wang
2017-08-11 11:29     ` Mark Rutland
2017-07-24 11:52 ` Yao Qi [this message]
2017-07-25 11:32 ` Yao Qi
2017-07-25 16:01   ` Mark Rutland
2017-07-25 14:12 ` [kernel-hardening] " Li Kun
2017-07-25 15:12   ` Mark Rutland

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