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Date: Tue, 21 Aug 2018 09:20:11 -0700
From: Laura Abbott <labbott@...hat.com>
To: Alexander Popov <alex.popov@...ux.com>,
kernel-hardening@...ts.openwall.com, Kees Cook <keescook@...omium.org>,
PaX Team <pageexec@...email.hu>, Brad Spengler <spender@...ecurity.net>,
Ingo Molnar <mingo@...nel.org>, Andy Lutomirski <luto@...nel.org>,
Tycho Andersen <tycho@...ho.ws>, Mark Rutland <mark.rutland@....com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>, Borislav Petkov <bp@...en8.de>,
Richard Sandiford <richard.sandiford@....com>,
Thomas Gleixner <tglx@...utronix.de>, "H . Peter Anvin" <hpa@...or.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>, "Dmitry V . Levin"
<ldv@...linux.org>, Emese Revfy <re.emese@...il.com>,
Jonathan Corbet <corbet@....net>, Andrey Ryabinin <aryabinin@...tuozzo.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Thomas Garnier <thgarnie@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
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<dwmw@...zon.co.uk>, Josh Poimboeuf <jpoimboe@...hat.com>,
Steven Rostedt <rostedt@...dmis.org>,
Dominik Brodowski <linux@...inikbrodowski.net>,
Juergen Gross <jgross@...e.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Dan Williams <dan.j.williams@...el.com>,
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Vikas Shivappa <vikas.shivappa@...ux.intel.com>, Kyle Huey
<me@...ehuey.com>, Dmitry Safonov <dsafonov@...tuozzo.com>,
Will Deacon <will.deacon@....com>, Arnd Bergmann <arnd@...db.de>,
Florian Weimer <fweimer@...hat.com>,
Boris Lukashev <blukashev@...pervictus.com>,
Andrey Konovalov <andreyknvl@...gle.com>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v15 0/7] Introduce the STACKLEAK feature and a test for it
On 08/16/2018 03:16 PM, Alexander Popov wrote:
> This is the 15th version of the patch series introducing STACKLEAK to
> the mainline kernel for x86. This version comes with changes according
> to the feedback from Linus Torvalds:
> 1. BUG_ON() in stackleak_erase() is safely eliminated;
> 2. Stack Clash detection (alloca() check) is completely dropped, since global
> '-Wvla' should arrive soon (https://patchwork.kernel.org/patch/10489873).
> stackleak_check_alloca() for arm64 is dropped as well in a separate commit.
>
> This version is rebased onto Linus' tree.
>
> Previous version discussion:
> https://lore.kernel.org/lkml/20180813214328.GA15137@beast/T/#u
>
> Motivation
> ==========
>
> STACKLEAK (initially developed by PaX Team):
>
> 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.
>
> 2. blocks some uninitialized stack variable attacks (e.g. CVE-2017-17712,
> CVE-2010-2963). That kind of bugs should be killed by improving C compilers
> in future, which might take a long time.
>
> Performance impact
> ==================
>
> Hardware: Intel Core i7-4770, 16 GB RAM
>
> Test #1: building the Linux kernel on a single core
> 0.91% slowdown
>
> Test #2: hackbench -s 4096 -l 2000 -g 15 -f 25 -P
> 4.2% slowdown
>
> So the STACKLEAK description in Kconfig includes:
> "The tradeoff is the performance impact: on a single CPU system kernel
> compilation sees a 1% slowdown, other systems and workloads may vary and you are
> advised to test this feature on your expected workload before deploying it".
>
>
> Alexander Popov (7):
> x86/entry: Add STACKLEAK erasing the kernel stack at the end of
> syscalls
> gcc-plugins: Add STACKLEAK plugin for tracking the kernel stack
> lkdtm: Add a test for STACKLEAK
> fs/proc: Show STACKLEAK metrics in the /proc file system
> doc: self-protection: Add information about STACKLEAK feature
> stackleak: Allow runtime disabling of kernel stack erasing
> arm64: Drop unneeded stackleak_check_alloca()
>
> Documentation/security/self-protection.rst | 10 +-
> Documentation/sysctl/kernel.txt | 18 ++
> Documentation/x86/x86_64/mm.txt | 2 +
> arch/Kconfig | 7 +
> arch/arm64/kernel/process.c | 22 --
> arch/x86/Kconfig | 1 +
> arch/x86/entry/calling.h | 14 +
> arch/x86/entry/entry_32.S | 7 +
> arch/x86/entry/entry_64.S | 3 +
> arch/x86/entry/entry_64_compat.S | 5 +
> drivers/misc/lkdtm/Makefile | 2 +
> drivers/misc/lkdtm/core.c | 1 +
> drivers/misc/lkdtm/lkdtm.h | 3 +
> drivers/misc/lkdtm/stackleak.c | 73 +++++
> fs/proc/base.c | 18 ++
> include/linux/sched.h | 5 +
> include/linux/stackleak.h | 35 +++
> kernel/Makefile | 4 +
> kernel/fork.c | 3 +
> kernel/stackleak.c | 132 +++++++++
> kernel/sysctl.c | 15 +-
> scripts/Makefile.gcc-plugins | 10 +
> scripts/gcc-plugins/Kconfig | 51 ++++
> scripts/gcc-plugins/stackleak_plugin.c | 427 +++++++++++++++++++++++++++++
> 24 files changed, 840 insertions(+), 28 deletions(-)
> create mode 100644 drivers/misc/lkdtm/stackleak.c
> create mode 100644 include/linux/stackleak.h
> create mode 100644 kernel/stackleak.c
> create mode 100644 scripts/gcc-plugins/stackleak_plugin.c
>
For arm64:
Tested-by: Laura Abbott <labbott@...hat.com>
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