Re: [PATCH v5 3/5] KEYS: trusted: allow trust sources to use kernel RNG for key material

[Ahmad Fatoum]

On 22.02.22 20:58, Ahmad Fatoum wrote:
> The two existing trusted key sources don't make use of the kernel RNG,
> but instead let the hardware that does the sealing/unsealing also
> generate the random key material. While a previous change offers users
> the choice to use the kernel RNG instead for both, new trust sources
> may want to unconditionally use the kernel RNG for generating key
> material, like it's done elsewhere in the kernel.
> 
> This is especially prudent for hardware that has proven-in-production
> HWRNG drivers implemented, as otherwise code would have to be duplicated
> only to arrive at a possibly worse result.
> 
> Make this possible by turning struct trusted_key_ops::get_random
> into an optional member. If a driver leaves it NULL, kernel RNG
> will be used instead.

The rebase on the change in scope of the previous commit made this
one here quite small. I would squash it into the previous commit
for v6, unless there are objections.


> 
> Acked-by: Sumit Garg <sumit.garg@xxxxxxxxxx>
> Reviewed-by: David Gstir <david@xxxxxxxxxxxxx>
> Tested-By: Tim Harvey <tharvey@xxxxxxxxxxxxx>
> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
> ---
> To: James Bottomley <jejb@xxxxxxxxxxxxx>
> To: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
> To: Mimi Zohar <zohar@xxxxxxxxxxxxx>
> To: David Howells <dhowells@xxxxxxxxxx>
> Cc: James Morris <jmorris@xxxxxxxxx>
> Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx>
> Cc: "Horia Geantă" <horia.geanta@xxxxxxx>
> Cc: Aymen Sghaier <aymen.sghaier@xxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Eric Biggers <ebiggers@xxxxxxxxxx>
> Cc: Jan Luebbe <j.luebbe@xxxxxxxxxxxxxx>
> Cc: David Gstir <david@xxxxxxxxxxxxx>
> Cc: Richard Weinberger <richard@xxxxxx>
> Cc: Franck LENORMAND <franck.lenormand@xxxxxxx>
> Cc: Sumit Garg <sumit.garg@xxxxxxxxxx>
> Cc: Tim Harvey <tharvey@xxxxxxxxxxxxx>
> Cc: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx>
> Cc: Pankaj Gupta <pankaj.gupta@xxxxxxx>
> Cc: keyrings@xxxxxxxxxxxxxxx
> Cc: linux-crypto@xxxxxxxxxxxxxxx
> Cc: linux-integrity@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-security-module@xxxxxxxxxxxxxxx
> ---
>  include/keys/trusted-type.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
> index d89fa2579ac0..4eb64548a74f 100644
> --- a/include/keys/trusted-type.h
> +++ b/include/keys/trusted-type.h
> @@ -64,7 +64,7 @@ struct trusted_key_ops {
>  	/* Unseal a key. */
>  	int (*unseal)(struct trusted_key_payload *p, char *datablob);
>  
> -	/* Get a randomized key. */
> +	/* Optional: Get a randomized key. */
>  	int (*get_random)(unsigned char *key, size_t key_len);
>  
>  	/* Exit key interface. */


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