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From: Emese Revfy <re.emese@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: kernel-hardening@lists.openwall.com, pageexec@freemail.hu,
	spender@grsecurity.net, mmarek@suse.com, keescook@chromium.org,
	linux-kernel@vger.kernel.org, yamada.masahiro@socionext.com,
	linux-kbuild@vger.kernel.org, tytso@mit.edu, linux-mm@kvack.org,
	axboe@kernel.dk, viro@zeniv.linux.org.uk,
	paulmck@linux.vnet.ibm.com, mingo@redhat.com, tglx@linutronix.de,
	bart.vanassche@sandisk.com, davem@davemloft.net
Subject: Re: [PATCH v2 1/3] Add the latent_entropy gcc plugin
Date: Fri, 3 Jun 2016 19:42:52 +0200	[thread overview]
Message-ID: <20160603194252.91064b8e682ad988283fc569@gmail.com> (raw)
In-Reply-To: <20160601124227.e922af8299168c09308d5e1b@linux-foundation.org>

On Wed, 1 Jun 2016 12:42:27 -0700
Andrew Morton <akpm@linux-foundation.org> wrote:

> On Tue, 31 May 2016 01:31:45 +0200 Emese Revfy <re.emese@gmail.com> wrote:
> 
> > This plugin mitigates the problem of the kernel having too little entropy during
> > and after boot for generating crypto keys.
> > 
> > It creates a local variable in every marked function. The value of this variable is
> > modified by randomly chosen operations (add, xor and rol) and
> > random values (gcc generates them at compile time and the stack pointer at runtime).
> > It depends on the control flow (e.g., loops, conditions).
> > 
> > Before the function returns the plugin writes this local variable
> > into the latent_entropy global variable. The value of this global variable is
> > added to the kernel entropy pool in do_one_initcall() and _do_fork().
> 
> I don't think I'm really understanding.  Won't this produce the same
> value on each and every boot?

No, because of interrupts and intentional data races.

-- 
Emese

  reply	other threads:[~2016-06-03 17:36 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-30 23:30 [PATCH v2 0/3] Introduce the latent_entropy gcc plugin Emese Revfy
2016-05-30 23:31 ` [PATCH v2 1/3] Add " Emese Revfy
2016-06-01 19:42   ` Andrew Morton
2016-06-03 17:42     ` Emese Revfy [this message]
2016-06-06 13:38       ` [kernel-hardening] " David Brown
2016-06-06 15:50         ` Kees Cook
2016-06-06 19:30         ` PaX Team
2016-06-06 23:13           ` Theodore Ts'o
2016-06-07 12:19             ` PaX Team
2016-06-07 13:58               ` Theodore Ts'o
2016-06-09 17:22                 ` PaX Team
2016-06-09 19:55                   ` Theodore Ts'o
2016-06-09 20:08                     ` Kees Cook
2016-06-09 21:51   ` Kees Cook
2016-06-13 21:49     ` Emese Revfy
2016-06-14 18:27       ` Kees Cook
2016-06-14 22:31         ` Emese Revfy
2016-05-30 23:32 ` [PATCH v2 2/3] Mark functions with the latent_entropy attribute Emese Revfy
2016-05-30 23:34 ` [PATCH v2 3/3] Add the extra_latent_entropy kernel parameter Emese Revfy
2016-06-09 21:18 ` [PATCH v2 0/3] Introduce the latent_entropy gcc plugin Kees Cook
2016-06-09 23:33   ` Emese Revfy

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