Date: Mon, 25 Jun 2007 03:09:38 -0400
From: Jakub Jelinek <jakub@redhat.com>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Matt Mackall <mpm@selenic.com>, Alexander Gabert <pappy@gentoo.org>,
       linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
       libc-alpha@sourceware.org, hardened@gentoo.org
Subject: Re: [PATCH] get_random_long() and AT_ENTROPY for auxv, kernel 2.6.21.5
Message-ID: <20070625070938.GN7012@devserv.devel.redhat.com>
Reply-To: Jakub Jelinek <jakub@redhat.com>
References: <4675C678.3080807@gentoo.org> <1182128803.22999.9.camel@laptopd505.fenrus.org> <20070620203022.GO11166@waste.org> <467EADA0.9020101@gentoo.org> <20070625034508.GE11115@waste.org> <1182746583.26621.5.camel@laptopd505.fenrus.org>
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On Sun, Jun 24, 2007 at 09:43:03PM -0700, Arjan van de Ven wrote:
> > - something to do with aux vector headers
> 
> the primary goal is to pass a random value to userspace at process
> start; this to save glibc from having to open /dev/urandom on ever
> program start (which it does now for all apps compiled with
> -fstack-protector, which in various distros is "everything").

There are 2 ways to compile -fstack-protector supporting glibc actually,
only one opens /dev/urandom on every program initialization, the other
computes the stack guard from some bits of the stack address (so indirectly
depends on get_random_int() in stack randomization).
Nevertheless, having one random long (32-bit for 32-bit arches, 64-bit
otherwise) in aux vector would be useful.

	Jakub
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