From: Theodore Ts'o <tytso-3s7WtUTddSA@public•gmane.org>
To: Daniel Borkmann
<dborkman-H+wXaHxf7aLQT0dZR+AlfA@public•gmane.org>,
davem-fT/PcQaiUtIeIZ0/mPfg9Q@public•gmane.org,
shemminger-OTpzqLSitTUnbdJkjeBofR2eb7JE58TQ@public•gmane.org,
fweimer-H+wXaHxf7aLQT0dZR+AlfA@public•gmane.org,
netdev-u79uwXL29TY76Z2rM5mHXA@public•gmane.org,
Eric Dumazet
<eric.dumazet-Re5JQEeQqe8AvxtiuMwx3w@public•gmane.org>,
linux-wireless-u79uwXL29TY76Z2rM5mHXA@public•gmane.org,
keescook-F7+t8E8rja9g9hUCZPvPmw@public•gmane.org
Subject: Re: [PATCH] random: seed random_int_secret at least poorly at core_initcall time
Date: Wed, 13 Nov 2013 21:54:48 -0500 [thread overview]
Message-ID: <20131114025448.GB31602@thunk.org> (raw)
In-Reply-To: <20131112134603.GE14929-5j1vdhnGyZutBveJljeh2VPnkB77EeZ12LY78lusg7I@public.gmane.org>
On Tue, Nov 12, 2013 at 02:46:03PM +0100, Hannes Frederic Sowa wrote:
> > It is needed by fork to set up the stack canary. And this actually gets
> > called before the secret is initialized.
>
> Maybe we could use this for the time being and use the seeding method
> of kaslr as soon as it hits the tree?
Hmm, from what I can tell even early_initcall() is going to be early
enough. The stack canary is set up by boot_init_stack_canary(), which
is run very, very early in start_kerne() --- way before
early_initcalls, or even before interrupts are enabled. So adding
random_int_secret_init_early() as a core_initcall is still too late.
I wonder if we need to do something in common with what Kees has been
considering for the kaslr code, since it's a similar issue --- we need
random number way earlier than we can really afford to initialize
/dev/random.
- Ted
P.S. Unless I'm missing something (and I hope I am), it would appear
that the stack canary is going to easily predictable by an attacker on
non-x86 platforms that don't have RDRAND. Has someone tested whether
or not the stack canary isn't constant across ARM or pre-Sandy Bridge
x86 systems?
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next prev parent reply other threads:[~2013-11-14 2:54 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-11 11:20 [PATCH net-next 0/6] prandom fixes/improvements Daniel Borkmann
2013-11-11 11:20 ` [PATCH net-next 1/6] random32: fix off-by-one in seeding requirement Daniel Borkmann
2013-11-11 11:20 ` [PATCH net-next 2/6] random32: add periodic reseeding Daniel Borkmann
2013-11-11 11:20 ` [PATCH net-next 3/6] random32: add prandom_reseed_late() and call when nonblocking pool becomes initialized Daniel Borkmann
2013-11-11 13:43 ` Theodore Ts'o
2013-11-12 0:03 ` Hannes Frederic Sowa
[not found] ` <20131112000307.GB14929-5j1vdhnGyZutBveJljeh2VPnkB77EeZ12LY78lusg7I@public.gmane.org>
2013-11-12 0:37 ` Karl Beldan
2013-11-12 8:36 ` Johannes Berg
[not found] ` <1384245375.14301.1.camel-8Nb76shvtaUJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2013-11-12 11:13 ` Karl Beldan
2013-11-12 13:09 ` Hannes Frederic Sowa
2013-11-12 11:53 ` Theodore Ts'o
2013-11-12 12:04 ` Johannes Berg
[not found] ` <20131112115350.GA14077-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2013-11-12 13:16 ` Hannes Frederic Sowa
[not found] ` <20131112131627.GD14929-5j1vdhnGyZutBveJljeh2VPnkB77EeZ12LY78lusg7I@public.gmane.org>
2013-11-12 13:46 ` [PATCH] random: seed random_int_secret at least poorly at core_initcall time Hannes Frederic Sowa
[not found] ` <20131112134603.GE14929-5j1vdhnGyZutBveJljeh2VPnkB77EeZ12LY78lusg7I@public.gmane.org>
2013-11-14 2:54 ` Theodore Ts'o [this message]
2013-11-14 4:18 ` Hannes Frederic Sowa
[not found] ` <20131114041829.GA26901-5j1vdhnGyZutBveJljeh2VPnkB77EeZ12LY78lusg7I@public.gmane.org>
2013-11-14 5:05 ` Hannes Frederic Sowa
2013-11-15 18:42 ` Kees Cook
[not found] ` <CAGXu5jJJtjvAqROzsekOd9Y5wbiw=G9ToNryOfP8auhQRrYORw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-11-16 7:40 ` Hannes Frederic Sowa
[not found] ` <20131114025448.GB31602-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2013-11-15 18:33 ` Kees Cook
[not found] ` <CAGXu5j+ySEdQBXKkspYC=svfekBja2Z_2tcWSAOEbvyiMLf=aA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-11-15 18:45 ` Dave Jones
2013-11-15 19:07 ` Kees Cook
2013-11-15 21:05 ` Theodore Ts'o
2013-11-11 11:20 ` [PATCH net-next 4/6] random32: move rnd_state to linux/random.h Daniel Borkmann
2013-11-11 11:20 ` [PATCH net-next 5/6] random32: upgrade taus88 generator to taus113 from errata paper Daniel Borkmann
2013-11-11 11:20 ` [PATCH net-next 6/6] random32: add test cases for taus113 implementation Daniel Borkmann
2013-11-11 19:33 ` [PATCH net-next 0/6] prandom fixes/improvements David Miller
2013-11-11 19:44 ` Hannes Frederic Sowa
2013-11-11 20:00 ` David Miller
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