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    SubjectRe: [PATCH v10 2/7] KEYS: trusted: allow use of kernel RNG for key material
    On Tue, May 17, 2022 at 11:52:55AM -0400, Mimi Zohar wrote:
    > On Fri, 2022-05-13 at 16:57 +0200, Ahmad Fatoum wrote:
    > > static int __init init_trusted(void)
    > > {
    > > + int (*get_random)(unsigned char *key, size_t key_len);
    > > int i, ret = 0;
    > >
    > > for (i = 0; i < ARRAY_SIZE(trusted_key_sources); i++) {
    > > @@ -322,6 +333,28 @@ static int __init init_trusted(void)
    > > strlen(trusted_key_sources[i].name)))
    > > continue;
    > >
    > > + /*
    > > + * We always support trusted.rng="kernel" and "default" as
    > > + * well as trusted.rng=$trusted.source if the trust source
    > > + * defines its own get_random callback.
    > > + */
    >
    > While TEE trusted keys support was upstreamed, there was a lot of
    > discussion about using kernel RNG. One of the concerns was lack of or
    > insuffiencent entropy during early boot on embedded devices. This
    > concern needs to be clearly documented in both Documentation/admin-
    > guide/kernel-parameters.txt and Documentation/security/keys/trusted-
    > encrypted.rst.

    Sounds like FUD. Use `get_random_bytes_wait()`, and you'll be fine.

    Jason

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