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From: Kees Cook <kees.cook@canonical.com>
To: Roland McGrath <roland@redhat.com>
Cc: linux-kernel@vger.kernel.org, Jakub Jelinek <jakub@redhat.com>,
	Ulrich Drepper <drepper@redhat.com>,
	libc-alpha@sourceware.org
Subject: Re: [PATCH] ELF: implement AT_RANDOM for future glibc use
Date: Thu, 2 Oct 2008 22:15:43 -0700	[thread overview]
Message-ID: <20081003051543.GQ10632@outflux.net> (raw)
In-Reply-To: <20081003005258.7FEDE154212@magilla.localdomain>

On Thu, Oct 02, 2008 at 05:52:58PM -0700, Roland McGrath wrote:
> I think the safe available AT_* values to use are 25, 26.

Out of curiosity, why are there gaps?  I figure I can include some
comments in that header to explain the gaps for future AT_* creations.

> I would configure the size in bytes.  Ulrich suggested it be 16 bytes on
> both 32-bit and 64-bit machines.

I was trying to make the size compile-time static so I could avoid
kmalloc'ing a buffer for get_random_bytes().  But maybe avoid that isn't
sensible?

As for 16 bytes on both 32bit and 64bit, I was aiming to have 4
pointer-sized random values.  16 works for 32bit, but I was hoping to
have 32 on 64bit.  Perhaps I am over-estimating?

-Kees

-- 
Kees Cook
Ubuntu Security Team

  reply	other threads:[~2008-10-03  5:18 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20081001201116.GD12527@outflux.net>
     [not found] ` <48E3EFD6.2010704@redhat.com>
     [not found]   ` <20081001215657.GH12527@outflux.net>
     [not found]     ` <20081001220948.GC32107@sunsite.ms.mff.cuni.cz>
     [not found]       ` <20081001222706.68E7E1544B4@magilla.localdomain>
2008-10-03  0:16         ` [PATCH] ELF: implement AT_RANDOM for future glibc use Kees Cook
2008-10-03  0:43           ` Jakub Jelinek
2008-10-03  5:25             ` Kees Cook
2008-10-03  5:29             ` Kees Cook
2008-10-03  5:57               ` Arjan van de Ven
2008-10-03  6:25                 ` Ulrich Drepper
2008-10-03 14:50                   ` [PATCH] ELF: implement AT_RANDOM for glibc PRNG seeding Kees Cook
2008-10-03 14:56                     ` Ulrich Drepper
2008-10-03 14:57                     ` Jakub Jelinek
2008-10-03 17:33                       ` Kees Cook
2008-10-03 17:41                         ` Ulrich Drepper
2008-10-03 17:59                           ` [PATCH v5] " Kees Cook
2008-10-18  5:42                             ` Ulrich Drepper
2008-10-21 20:01                             ` Andrew Morton
2008-10-21 20:22                               ` Ulrich Drepper
2008-10-27  5:46                                 ` Andrew Morton
2008-10-03  0:52           ` [PATCH] ELF: implement AT_RANDOM for future glibc use Roland McGrath
2008-10-03  5:15             ` Kees Cook [this message]
2008-10-03 20:22               ` Roland McGrath
2008-10-06  6:00           ` Andi Kleen
2008-10-06 17:50             ` Kees Cook
2008-10-06 18:25               ` David Wagner
2008-10-06 20:23                 ` Andi Kleen
2008-10-06 22:16                   ` David Wagner
2008-10-06 19:26               ` Andi Kleen
2008-10-06 22:01                 ` Kees Cook
2008-10-06 23:19                   ` Andi Kleen
2008-10-06 23:29                     ` Kees Cook
2008-10-06 23:44                       ` Andi Kleen
2008-10-06 22:07                 ` Kees Cook
2008-10-06 23:28                   ` Andi Kleen
2008-10-06 23:58                   ` Roland McGrath
2008-10-07  0:08                     ` Ulrich Drepper
2008-10-07  0:31                     ` Kees Cook
2008-10-07  0:57                       ` Ulrich Drepper
2008-10-07  1:44                         ` Kees Cook
2008-10-07  1:51                           ` Ulrich Drepper

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