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From: Will Deacon <will.deacon@arm.com>
To: Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>,
	Kristina Martsenko <Kristina.Martsenko@arm.com>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	Mark Rutland <Mark.Rutland@arm.com>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	Andrew Jones <drjones@redhat.com>,
	Jacob Bramley <Jacob.Bramley@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Marc Zyngier <Marc.Zyngier@arm.com>,
	Adam Wallis <awallis@codeaurora.org>,
	Suzuki Poulose <Suzuki.Poulose@arm.com>,
	Christoffer Dall <Christoffer.Dall@arm.com>,
	"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
	Amit Kachhap <Amit.Kachhap@arm.com>,
	Dave P Martin <Dave.Martin@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Kees Cook <keescook@chromium.org>, nd <nd@arm.com>
Subject: Re: [PATCH v5 07/17] arm64: add basic pointer authentication support
Date: Tue, 23 Oct 2018 11:20:09 +0100
Message-ID: <20181023102008.GA8989@brain-police> (raw)
In-Reply-To: <5ca5bf92-f2b7-48c9-ea41-5efeff09a799@arm.com>

On Tue, Oct 23, 2018 at 09:36:16AM +0100, Ramana Radhakrishnan wrote:
> On 19/10/2018 12:15, Catalin Marinas wrote:
> > On Fri, Oct 05, 2018 at 09:47:44AM +0100, Kristina Martsenko wrote:
> >> diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h
> >> new file mode 100644
> >> index 000000000000..2aefedc31d9e
> >> --- /dev/null
> >> +++ b/arch/arm64/include/asm/pointer_auth.h
> >> @@ -0,0 +1,63 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +#ifndef __ASM_POINTER_AUTH_H
> >> +#define __ASM_POINTER_AUTH_H
> >> +
> >> +#include <linux/random.h>
> >> +
> >> +#include <asm/cpufeature.h>
> >> +#include <asm/sysreg.h>
> >> +
> >> +#ifdef CONFIG_ARM64_PTR_AUTH
> >> +/*
> >> + * Each key is a 128-bit quantity which is split across a pair of 64-bit
> >> + * registers (Lo and Hi).
> >> + */
> >> +struct ptrauth_key {
> >> +	unsigned long lo, hi;
> >> +};
> >> +
> >> +/*
> >> + * We give each process its own instruction A key (APIAKey), which is shared by
> >> + * all threads. This is inherited upon fork(), and reinitialised upon exec*().
> >> + * All other keys are currently unused, with APIBKey, APDAKey, and APBAKey
> >> + * instructions behaving as NOPs.
> >> + */
> > 
> > I don't remember the past discussions but I assume the tools guys are ok
> > with a single key shared by multiple threads. Ramana, could you ack this
> > part, FTR?
> 
> Sorry about the slow response, I've been traveling.
> 
> Ack and Will's response covers the reasons why pretty well. A prctl call 
> would be a good enhancement.

One minor "gotcha" with that is that the glibc prctl() wrapper would need to
be annotated not to use pointer auth, or we'd have to issue the syscall
in-line.

Will

  reply index

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-05  8:47 [PATCH 00/17] ARMv8.3 " Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 01/17] arm64: add pointer authentication register bits Kristina Martsenko
2018-10-11 16:28   ` Will Deacon
2018-10-12  8:53     ` Mark Rutland
2018-10-12  8:56       ` Will Deacon
2018-10-12  9:50         ` Mark Rutland
2018-10-05  8:47 ` [PATCH v5 02/17] arm64/kvm: consistently handle host HCR_EL2 flags Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 03/17] arm64/kvm: hide ptrauth from guests Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 04/17] arm64: Don't trap host pointer auth use to EL2 Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 05/17] arm64/cpufeature: detect pointer authentication Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 06/17] asm-generic: mm_hooks: allow hooks to be overridden individually Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 07/17] arm64: add basic pointer authentication support Kristina Martsenko
2018-10-11 16:00   ` Suzuki K Poulose
2018-10-19 11:15   ` Catalin Marinas
2018-10-19 11:24     ` Will Deacon
2018-10-19 15:36       ` Kees Cook
2018-10-19 15:49         ` Will Deacon
2018-10-19 16:05           ` Kees Cook
2018-10-19 16:16             ` Will Deacon
2018-10-19 15:54         ` Mark Rutland
2018-10-19 16:49       ` Cyrill Gorcunov
2018-11-14 18:11       ` Will Deacon
2018-11-15 10:25         ` Dave Martin
2018-10-23  8:36     ` Ramana Radhakrishnan
2018-10-23 10:20       ` Will Deacon [this message]
2018-10-05  8:47 ` [PATCH v5 08/17] arm64: expose user PAC bit positions via ptrace Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 09/17] arm64: perf: strip PAC when unwinding userspace Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 10/17] arm64: enable pointer authentication Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 11/17] arm64: docs: document " Kristina Martsenko
2018-10-05  9:04   ` Ramana Radhakrishnan
2018-10-16 16:14     ` Kristina Martsenko
2018-10-19 11:35       ` Catalin Marinas
2018-10-19 11:47         ` Marc Zyngier
2018-10-19 12:22         ` Will Deacon
2018-10-19 14:42         ` Kristina Martsenko
2018-10-19 15:10           ` Catalin Marinas
2018-10-19 17:45             ` Will Deacon
2018-11-02  6:02               ` Jon Masters
2018-10-24 10:56         ` Ramana Radhakrishnan
2018-10-15 22:35   ` Kees Cook
2018-11-02  9:46     ` Ramana Radhakrishnan
2018-10-05  8:47 ` [RFC 12/17] arm64: move ptrauth keys to thread_info Kristina Martsenko
2018-10-19 11:38   ` Catalin Marinas
2018-10-05  8:47 ` [RFC 13/17] arm64: install user ptrauth keys at kernel exit time Kristina Martsenko
2018-10-05  8:47 ` [RFC 14/17] arm64: unwind: strip PAC from kernel addresses Kristina Martsenko
2018-10-05  8:47 ` [RFC 15/17] arm64: enable ptrauth earlier Kristina Martsenko
2018-10-06 12:51   ` Amit Kachhap
2018-10-05  8:47 ` [RFC 16/17] arm64: initialize and switch ptrauth kernel keys Kristina Martsenko
2018-10-06 12:56   ` Amit Kachhap
2018-10-05  8:47 ` [RFC 17/17] arm64: compile the kernel with ptrauth -msign-return-address Kristina Martsenko
2018-10-05  9:01   ` Ramana Radhakrishnan
2018-10-11 14:00     ` Kristina Martsenko
2018-10-11 14:23   ` Vladimir Murzin
2018-10-15 22:38     ` Kees Cook
2018-10-15 22:42 ` [PATCH 00/17] ARMv8.3 pointer authentication support Kees Cook
2018-11-13 16:17   ` Kristina Martsenko
2018-11-13 23:09     ` Kees Cook
2018-11-14 15:54       ` Kristina Martsenko
2018-11-14 21:47       ` Mark Rutland
2018-11-14 22:48         ` Kees Cook
2018-10-19 12:36 ` Will Deacon
2018-10-23  8:39   ` Ramana Radhakrishnan

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