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From: Florian Weimer <fweimer@redhat.com>
To: Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>
Cc: James Greenhalgh <James.Greenhalgh@arm.com>,
	 Richard Earnshaw	<Richard.Earnshaw@arm.com>,
	 Marcus Shawcroft <Marcus.Shawcroft@arm.com>,
	 "gcc-patches\@gcc.gnu.org"	<gcc-patches@gcc.gnu.org>,
	 Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	 Will Deacon <Will.Deacon@arm.com>,
	 Mark Rutland <Mark.Rutland@arm.com>,  nd	<nd@arm.com>
Subject: Re: [RFC][AArch64] Add support for system register based stack protector canary access
Date: Mon, 03 Dec 2018 15:31:00 -0000	[thread overview]
Message-ID: <875zwad3v6.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <7a5a57fa-629d-d2ff-6292-e0893647ec8a@arm.com> (Ramana	Radhakrishnan's message of "Mon, 3 Dec 2018 09:55:36 +0000")

* Ramana Radhakrishnan:

> I don't intend to change the defaults in userland, we've discussed this 
> for user-land in the past and as far as glibc and userland is concerned 
> we stick to the options as currently existing. The system register 
> option is really for the kernel to use along with an offset as they 
> control their ABI and this is a decision for them to make.

For userland, I would like to eventually copy the OpenBSD approach for
architectures which have some form of PC-relative addressing: we can
have multiple random canaries in (RELRO) .rodata in sufficiently close
to the code that needs them (assuming that we have split .rodata).  At
least for x86-64, I expect this to be a small win.  It's also a slight
hardening improvement if the reference canary is not stored in writable
memory.

Thanks,
Florian

  parent reply	other threads:[~2018-12-03 15:31 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-03  9:55 Ramana Radhakrishnan
2018-12-03  9:59 ` Jakub Jelinek
2018-12-03 10:03   ` Ramana Radhakrishnan
2018-12-03 15:31 ` Florian Weimer [this message]
2018-12-03 16:40 ` Ard Biesheuvel
2019-01-10 16:53   ` Ramana Radhakrishnan
2019-01-10 10:53 ` Ramana Radhakrishnan
2019-01-10 11:05   ` Jakub Jelinek
2019-01-10 12:51     ` Ramana Radhakrishnan
2019-01-10 15:49 ` James Greenhalgh
2019-01-10 15:55   ` Will Deacon
2019-01-10 16:49   ` Ramana Radhakrishnan
2019-01-19 17:30 ` Jakub Jelinek
2018-12-04  3:51 Wilco Dijkstra
2018-12-04 12:58 ` Florian Weimer
2018-12-07 14:51   ` Ramana Radhakrishnan

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