linux-kernel - Re: [PATCH 1/7] A couple of generated files

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Date:	Tue, 1 Mar 2016 22:15:59 -0500
From:	Sandy Harris <sandyinchina@...il.com>
To:	Jason Cooper <jason@...edaemon.net>
Cc:	"Theodore Ts\\'o" <tytso@....edu>,
	"H. Peter Anvin" <hpa@...or.com>, John Denker <jsd@...n.com>,
	LKML <linux-kernel@...r.kernel.org>, linux-crypto@...r.kernel.org
Subject: Re: [PATCH 1/7] A couple of generated files

This set of patches, plus some later ones that simplify the
code and get rid of one major bug are now at:
https://github.com/sandy-harris

Directory for these changes is random.gcm

An out-of-kernel test program for an older version
is in random.test

On Sat, Nov 7, 2015 at 1:50 PM, Sandy Harris <sandyinchina@...il.com> wrote:

> There are two groups of changes, each controlled by a config
> variable. Default for both is 'n'.
>
> CONFIG_RANDOM_INIT: initialise the pools with data from
> /dev/urandom on the machine that compiles the kernel.
> Comments for the generator program scripts/gen_random.c
> have details.
>
> The main change in random.c is adding conditionals
> to make it use the random data if CONFIG_RANDOM_INIT
> is set. There is also a trivial fix updating a reference to an
> obsoleted in a comment, and I added some sanity-check
> #if tests for odd #define parameter values.
>
> This is a fairly simple change. I do not think it needs a config
> variable; it should just be the default. However I put it under
> config control for testing.
>
> CONFIG_RANDOM_GCM controls a much larger and
> less clearly desirable set of changes. It switches
> compilation between random.c and and a heavily
> modified version random_gcm.c
>
> This uses the hash from AES-GCM instead of SHA-1,
> and that allows a lot of other changes. The main
> design goal was to decouple the two output pools
> so that heavy use of the nonblocking pool cannot
> deplete entropy in the input pool. The nonblocking
> pool usually rekeys from the blocking pool instead.
> random_gcm.c has extensive comments on both
> the rationale for this approach & the details of my
> implementation.
>
> random_gcm.c is not close to being a finished
> product, in particular my code is not yet well
> integrated with existing driver code.
>
> Most of the code was developed and has been
> fairly well tested outside the kernel.
> Test program is at:
> https://github.com/sandy-harris/random.test
>
> I just dropped a large chunk of that code into
> a copy of random.c, made modifications to
> make the style match better & to get it to
> compile in the kernel context, then deleted
> a few chunks of existing driver code and
> replaced them with calls to my stuff.
>
> Proper integration would involve both
> replacing more of the existing code with
> new and moving a few important bits of
> the existing code into some of my functions.
> In particular, my stuff does not yet block
> in the right places.