Re: [PATCH v28 09/12] LRNG - add Jitter RNG fast noise source

Randy Dunlap
2020-01-16T00:17:41Z

On 1/15/20 2:34 AM, Stephan Müller wrote:

>
> CC: "Eric W. Biederman" <ebiederm@xmission.com>
> CC: "Alexander E. Patrakov" <patrakov@gmail.com>
> CC: "Ahmed S. Darwish" <darwish.07@gmail.com>
> CC: "Theodore Y. Ts'o" <tytso@mit.edu>
> CC: Willy Tarreau <w@1wt.eu>
> CC: Matthew Garrett <mjg59@srcf.ucam.org>
> CC: Vito Caputo <vcaputo@pengaru.com>
> CC: Andreas Dilger <adilger.kernel@dilger.ca>
> CC: Jan Kara <jack@suse.cz>
> CC: Ray Strode <rstrode@redhat.com>
> CC: William Jon McCann <mccann@jhu.edu>
> CC: zhangjs <zachary@baishancloud.com>
> CC: Andy Lutomirski <luto@kernel.org>
> CC: Florian Weimer <fweimer@redhat.com>
> CC: Lennart Poettering <mzxreary@0pointer.de>
> CC: Nicolai Stange <nstange@suse.de>
> Reviewed-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
> Reviewed-by: Roman Drahtmueller <draht@schaltsekun.de>
> Tested-by: Roman Drahtmüller <draht@schaltsekun.de>
> Tested-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
> Tested-by: Neil Horman <nhorman@redhat.com>
> Signed-off-by: Stephan Mueller <smueller@chronox.de>
> ---
> drivers/char/lrng/Kconfig | 11 +++++
> drivers/char/lrng/Makefile | 1 +
> drivers/char/lrng/lrng_jent.c | 89 +++++++++++++++++++++++++++++++++++
> 3 files changed, 101 insertions(+)
> create mode 100644 drivers/char/lrng/lrng_jent.c
>
> diff --git a/drivers/char/lrng/Kconfig b/drivers/char/lrng/Kconfig
> index 0d070a3897dd..10b7cbdb8c8e 100644
> --- a/drivers/char/lrng/Kconfig
> +++ b/drivers/char/lrng/Kconfig
> @@ -92,4 +92,15 @@ config LRNG_KCAPI
> provided by the selected kernel crypto API RNG.
> endif # LRNG_DRNG_SWITCH
>
> +config LRNG_JENT
> + bool "Enable Jitter RNG as LRNG Seed Source"
> + select CRYPTO_JITTERENTROPY

Don't select unless CRYPTO is already set/enabled.

> + help
> + The Linux RNG may use the Jitter RNG as noise source. Enabling
> + this option enables the use of the Jitter RNG. Its default
> + entropy level is 16 bits of entropy per 256 data bits delivered
> + by the Jitter RNG. This entropy level can be changed at boot
> + time or at runtime with the lrng_base.jitterrng configuration
> + variable.
> +
> endif # LRNG

> diff --git a/drivers/char/lrng/lrng_jent.c b/drivers/char/lrng/lrng_jent.c
> new file mode 100644
> index 000000000000..ff0bbe2680c4
> --- /dev/null
> +++ b/drivers/char/lrng/lrng_jent.c
> @@ -0,0 +1,89 @@
> +// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
> +/*
> + * LRNG Fast Noise Source: Jitter RNG
> + *
> + * Copyright (C) 2016 - 2020, Stephan Mueller <smueller@chronox.de>
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/types.h>
> +#include <crypto/internal/jitterentropy.h>
> +
> +#include "lrng_internal.h"
> +
> +/*
> + * Estimated entropy of data is a 16th of LRNG_DRNG_SECURITY_STRENGTH_BITS.
> + * Albeit a full entropy assessment is provided for the noise source indicating
> + * that it provides high entropy rates and considering that it deactivates
> + * when it detects insufficient hardware, the chosen under estimation of
> + * entropy is considered to be acceptable to all reviewers.
> + */
> +static u32 jitterrng = LRNG_DRNG_SECURITY_STRENGTH_BITS>>4;
> +module_param(jitterrng, uint, 0644);
> +MODULE_PARM_DESC(jitterrng, "Entropy in bits of 256 data bits from Jitter "
> + "RNG noise source");

One line for the string, please, not split to 2 lines.

--
~Randy
Reported-by: Randy Dunlap <rdunlap@infradead.org>