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From: Kees Cook <keescook@chromium.org>
To: Alexander Popov <alex.popov@linux.com>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>,
	PaX Team <pageexec@freemail.hu>,
	Brad Spengler <spender@grsecurity.net>,
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	"H . Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
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	Emese Revfy <re.emese@gmail.com>,
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	Dan Williams <dan.j.williams@intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Mathias Krause <minipli@googlemail.com>,
	Vikas Shivappa <vikas.shivappa@linux.intel.com>,
	Kyle Huey <me@kylehuey.com>,
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	Will Deacon <will.deacon@arm.com>, Arnd Bergmann <arnd@arndb.de>,
	Florian Weimer <fweimer@redhat.com>,
	Boris Lukashev <blukashev@sempervictus.com>,
	X86 ML <x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC v10 0/6] Introduce the STACKLEAK feature and a test for it
Date: Wed, 28 Mar 2018 13:13:48 -0700	[thread overview]
Message-ID: <CAGXu5jKRs6Zi7+hDEsH3hW2zsAAQ0aiJoXaOpmxNjHC64ZABTw@mail.gmail.com> (raw)
In-Reply-To: <1522267032-6603-1-git-send-email-alex.popov@linux.com>

On Wed, Mar 28, 2018 at 12:57 PM, Alexander Popov <alex.popov@linux.com> wrote:
> This is the 10th version of the patch series introducing STACKLEAK to the
> mainline kernel. The previous version raised a fervent discussion[0].
> The assembly code introduced by v9 irritated the reviewers.

Thanks for persisting!

> I've found the way to bypass the obstacles[1] of the C implementation.
> So I dare come once again. Let me ask you to look at this code without
> preconception.

The assembly changes are now very minimal; thanks for reworking this.
I hope this addresses both Dave Hansen and Linus's (similar)
objections.

>  1. reduces the information that can be revealed through kernel stack leak bugs.
>     The idea of erasing the thread stack at the end of syscalls is similar to
>     CONFIG_PAGE_POISONING and memzero_explicit() in kernel crypto, which all
>     comply with FDP_RIP.2 (Full Residual Information Protection) of the
>     Common Criteria standard.

Agreed: I continue to believe this is meaningful even if just for
reducing the lifetime of sensitive data on the stack.

-Kees

-- 
Kees Cook
Pixel Security

      parent reply	other threads:[~2018-03-28 20:13 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-28 19:57 [PATCH RFC v10 0/6] Introduce the STACKLEAK feature and a test for it Alexander Popov
2018-03-28 19:57 ` [PATCH RFC v10 1/6] gcc-plugins: Clean up the cgraph_create_edge* macros Alexander Popov
2018-03-28 19:57 ` [PATCH RFC v10 2/6] x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls Alexander Popov
2018-03-28 22:55   ` Dave Hansen
2018-03-29  6:58     ` Alexander Popov
2018-03-29 13:51       ` Dave Hansen
     [not found]         ` <CAFUG7Cd7cSqSHCrqxKUFwBBQLuix0Mi5-=V6pq_U7KtFh20Kqg@mail.gmail.com>
2018-03-29 20:56           ` Alexander Popov
2018-03-29 20:56             ` Alexander Popov
2018-03-29 21:00             ` Dave Hansen
     [not found]   ` <alpine.DEB.2.10.1803291137150.27913@vshiva-Udesk>
2018-03-29 21:34     ` Alexander Popov
2018-03-29 21:34       ` Alexander Popov
2018-03-28 19:57 ` [PATCH RFC v10 3/6] gcc-plugins: Add STACKLEAK plugin for tracking the kernel stack Alexander Popov
2018-03-28 19:57 ` [PATCH RFC v10 4/6] lkdtm: Add a test for STACKLEAK Alexander Popov
2018-03-28 19:57 ` [PATCH RFC v10 5/6] fs/proc: Show STACKLEAK metrics in the /proc file system Alexander Popov
2018-03-28 19:57 ` [PATCH RFC v10 6/6] doc: self-protection: Add information about STACKLEAK feature Alexander Popov
2018-03-28 20:13 ` Kees Cook [this message]

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