[PATCH v2 1/2] lib: uuid: use RNG device if present

[Simon Glass <sjg@chromium.org>]

Hi Mattias,

On Wed, 16 Dec 2020 at 09:28, <matthias.bgg@kernel.org> wrote:
>
> From: Matthias Brugger <mbrugger@suse.com>
>
> When calculating a random UUID we use a weak seed.
> Use a RNG device if present to increase entropy.
>
> Signed-off-by: Matthias Brugger <mbrugger@suse.com>
>
> ---
>
> Changes in v2:
> - fix dm_rng_read() parameters
> - add missing include
>
>  lib/uuid.c | 21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/lib/uuid.c b/lib/uuid.c
> index e62d5ca264..e3487380c3 100644
> --- a/lib/uuid.c
> +++ b/lib/uuid.c
> @@ -15,6 +15,8 @@
>  #include <asm/io.h>
>  #include <part_efi.h>
>  #include <malloc.h>
> +#include <dm/uclass.h>
> +#include <rng.h>
>
>  /*
>   * UUID - Universally Unique IDentifier - 128 bits unique number.
> @@ -249,9 +251,22 @@ void gen_rand_uuid(unsigned char *uuid_bin)
>  {
>         u32 ptr[4];
>         struct uuid *uuid = (struct uuid *)ptr;
> -       int i;
> -
> -       srand(get_ticks() + rand());
> +       int i, ret;
> +       struct udevice *devp;
> +       u8 randv = 0;
> +
> +#if defined(CONFIG_DM_RNG)

This seems a little backwards to me. The caller should request a RNG
device, getting either a hardware one or a software one, and then call
the uclass method to get the uuid.

> +       ret = uclass_get_device(UCLASS_RNG, 0, &devp);
> +       if (ret) {
> +               ret = dm_rng_read(devp, &randv, sizeof(randv));
> +               if (ret < 0)
> +                       randv = 0;
> +       }
> +       if (randv)
> +               srand(randv);
> +       else
> +#endif
> +               srand(get_ticks() + rand());
>
>         /* Set all fields randomly */
>         for (i = 0; i < 4; i++)
> --
> 2.29.2
>

Regards,
Simon