linux-kernel - Re: [PATCH v3 0/7] char/random: Simplify random address requests

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Message-ID: <CAGXu5jK4j2=gFVd_=Spn1e_ke8_5xiWyBgKYf+NYyG5FuFDbdw@mail.gmail.com>
Date:	Wed, 3 Aug 2016 19:41:20 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Jason Cooper <jason@...edaemon.net>
Cc:	Michael Ellerman <mpe@...erman.id.au>,
	"Roberts, William C" <william.c.roberts@...el.com>,
	Yann Droneaud <ydroneaud@...eya.com>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	kernel-hardening <kernel-hardening@...ts.openwall.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Theodore Ts'o" <tytso@....edu>, Arnd Bergmann <arnd@...db.de>,
	Greg KH <gregkh@...uxfoundation.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	"benh@...nel.crashing.org" <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	"David S. Miller" <davem@...emloft.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	"x86@...nel.org" <x86@...nel.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Nick Kralevich <nnk@...gle.com>,
	Jeffrey Vander Stoep <jeffv@...gle.com>,
	Daniel Cashman <dcashman@...roid.com>
Subject: Re: [PATCH v3 0/7] char/random: Simplify random address requests

On Wed, Aug 3, 2016 at 4:39 PM, Jason Cooper <jason@...edaemon.net> wrote:
> Two previous attempts have been made to rework this API.  The first can be
> found at:
>
>   https://lkml.kernel.org/r/cover.1390770607.git.ydroneaud@opteya.com
>
> The second at:
>
>   https://lkml.kernel.org/r/1469471141-25669-1-git-send-email-william.c.roberts@intel.com
>
> Previous versions of this series can been seen at:
>
> RFC:  https://lkml.kernel.org/r/20160726030201.6775-1-jason@lakedaemon.net
>  v1:  https://lkml.kernel.org/r/20160728204730.27453-1-jason@lakedaemon.net
>  v2:  https://lkml.kernel.org/r/20160730154244.403-1-jason@lakedaemon.net
>
> In addition to incorporating ideas from these two previous efforts, this series
> adds several desirable features.  First, we take the range as an argument
> directly, which removes math both before the call and inside the function.
> Second, we return the start address on error.  All callers fell back to the
> start address on error, so we remove the need to check for errors.  Third, we
> cap range to prevent overflow.  Last, we use kerneldoc to describe the new
> function.
>
> If possible, I'd like to request Acks from the various subsystems so that we
> can merge this as one bisectable branch.
>
> Changes from v2:
>  - s/randomize_addr/randomize_page/ (Kees Cook)
>  - PAGE_ALIGN(start) if it wasn't (Kees Cook, Michael Ellerman)
>
> Changes from v1:
>  - Explicitly mention page_aligned start assumption (Yann Droneaud)
>  - pick random pages vice random addresses (Yann Droneaud)
>  - catch range=0 last
>  - Add Ack for arm64 (Will Deacon)
>
> Jason Cooper (7):
>   random: Simplify API for random address requests
>   x86: Use simpler API for random address requests
>   ARM: Use simpler API for random address requests
>   arm64: Use simpler API for random address requests
>   tile: Use simpler API for random address requests
>   unicore32: Use simpler API for random address requests
>   random: Remove unused randomize_range()
>
>  arch/arm/kernel/process.c       |  3 +--
>  arch/arm64/kernel/process.c     |  8 ++------
>  arch/tile/mm/mmap.c             |  3 +--
>  arch/unicore32/kernel/process.c |  3 +--
>  arch/x86/kernel/process.c       |  3 +--
>  arch/x86/kernel/sys_x86_64.c    |  5 +----
>  drivers/char/random.c           | 36 +++++++++++++++++++++++++-----------
>  include/linux/random.h          |  2 +-
>  8 files changed, 33 insertions(+), 30 deletions(-)

This looks great! Thanks for the v3. :)

Acked-by: Kees Cook <keescook@...omium.org>

-Kees

-- 
Kees Cook
Brillo & Chrome OS Security