linux-kernel - Re: [PATCH] tpm: Add module parameter for hwrng quality.

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Date:   Mon, 18 Jun 2018 21:07:12 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Louis Collard <louiscollard@...omium.org>
Cc:     linux-integrity@...r.kernel.org, Peter Huewe <peterhuewe@....de>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, apronin@...omium.org
Subject: Re: [PATCH] tpm: Add module parameter for hwrng quality.

On Fri, Jun 08, 2018 at 02:54:38PM +0800, Louis Collard wrote:
> It is now possible for drivers to easily specify a hwrng quality, however
> most do not currently do this, and in cases where they do, it may be
> desirable to override the driver-specified value with a user-specified
> one. This patch adds a parameter to set or override the hwrng quality.
> 
> Signed-off-by: Louis Collard <louiscollard@...omium.org>
> ---
>  drivers/char/tpm/tpm-chip.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 0a62c19937b6..4def49cfc634 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -33,6 +33,11 @@
>  DEFINE_IDR(dev_nums_idr);
>  static DEFINE_MUTEX(idr_lock);
>  
> +static short override_rng_quality = -1;
> +module_param(override_rng_quality, short, 0644);

Should this be 600 i.e. not to leak this information?

/Jarkko