Re: [PATCH v25 10/12] LRNG - add TRNG support

[Alexander E. Patrakov]

20.11.2019 13:58, Stephan MÃller ÐÐÑÐÑ:

> Or another idea and apologies if I restart this conversation as there was
> already a discussion around it: what about extending the getrandom(2) call
> instead of adding a device file?
>
> What about adding yet another flag to getrandom: GRND_TRUERANDOM and process
> it as follows:
>
>          if (flags & ~(GRND_NONBLOCK|GRND_RANDOM|GRND_INSECURE|
> GRND_TRUERANDOM))
>                  return -EINVAL;
>
>          //From Andy's tree
>          /*
>           * Requesting insecure and blocking randomness at the same time makes
>           * no sense.
>           */
>          if ((flags & (GRND_INSECURE|GRND_RANDOM)) == (GRND_INSECURE|
> GRND_RANDOM))
>                  return -EINVAL;
>
> 	  /* We only allow GRND_TRUERANDOM by itself or with NONBLOCK */
> 	  if (! ((flags & GRND_TRUERANDOM) &&
>                 ((flags == GRND_TRUERANDOM) ||
>                  (flags == GRND_TRUERANDOM | GRND_NONBLOCK))))
> 		return -EINVAL;
>
> 	if (flags & GRND_TRUERANDOM) {
> 		... do the TRNG processing ...
> 		... may return -ENOPNOTSUPP if no TRNG available ...
> 	}

This would totally miss the point of adding a device node: UNIX 
permissions that don't allow "others" to read and deplete "true" random 
numbers.

--
Alexander E. Patrakov