Re: sign-file and detached PKCS#7 firmware signatures

[Luis R. Rodriguez]

On Tue, May 19, 2015 at 11:47 AM, David Howells <dhowells@xxxxxxxxxx> wrote:
> Luis R. Rodriguez <mcgrof@xxxxxxxx> wrote:
>
>> I'll also mention:
>>
>> ---
>> The $DIGEST_ALGORITHM needs to be supported on the running kernel and
>> can differ from CONFIG_MODULE_SIG_HASH.
>> ---
>>
>> As I do no think that is quite obvious to a system integrator at first.
>
> Actually, this isn't necessarily so for the firmware.

Sorry by "needs to be supported on the running kernel" I meant "=y" or "=m".

> It *is* for the module signing, but you can always load the module to give you
> the digest algorithm (or public key algorithm) for the firmware.

Sure.

> Though you would still have to be careful with firmware loaded during the
> initramfs phase.

Make sense, how about:

---
The $DIGEST_ALGORITHM needs to be enabled as built-in (=y) or modular
(=m) in the running kernel and can differ from CONFIG_MODULE_SIG_HASH.
If you are enabling the $DIGEST_ALGORITHM as a module take care to
ensure that this module will also be present on the initramfs used as
some modules within the initramfs may need it if using the
firmware_class APIs and firmware signing has been enabled.
---

  Luis
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