Re: [PATCH] efi_loader: capsule: add a debug message in case of no key

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

On Thu, May 20, 2021 at 04:06:12AM +0200, Heinrich Schuchardt wrote:
> On 5/10/21 10:19 AM, AKASHI Takahiro wrote:
> > It will probably be a common error case that a certificate (public key)
> > is not provided by the system while capsule authentication is enabled.
> > So add a debug message.
> > 
> > Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> > ---
> >   lib/efi_loader/efi_capsule.c | 4 +++-
> >   1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/lib/efi_loader/efi_capsule.c b/lib/efi_loader/efi_capsule.c
> > index 90893f85e22c..84ddaf50d13f 100644
> > --- a/lib/efi_loader/efi_capsule.c
> > +++ b/lib/efi_loader/efi_capsule.c
> > @@ -316,8 +316,10 @@ efi_status_t efi_capsule_authenticate(const void *capsule, efi_uintn_t capsule_s
> >   	}
> > 
> >   	ret = efi_get_public_key_data(&fdt_pkey, &pkey_len);
> > -	if (ret < 0)
> > +	if (ret < 0) {
> > +		debug("Public key/certificate not found\n");
> 
> Currently the only implementation of efi_get_public_key_data() actually
> providing keys is the one in board/emulation/common/qemu_capsule.c where
> the user has to manually upload the esl file.
> 
> For future implementation it is preferable to build the public key data
> into the U-Boot binary. If it is part of the build process then the only
> error that could come up is that the public key data has the wrong format.

Now Ilias posted a patch to embed a public key in the U-Boot binary.
But it won't be the only solution in the future and the system owners
may want to provide a key in their own way; hence, it might not be "part
of build process."

So I think that adding a message is still valid, even it should be
treated as an error message instead of a debug message to warn "users".

-Takahiro Akashi


> If we are using the weak implementation of efi_get_public_key_data() in
> lib/efi_loader/efi_capsule.cwith CONFIG_EFI_CAPSULE_AUTHENTICATE=y, the
> system is misconfigured. Do we need that weak implementation at all? I
> would prefer to remove to get a build error.
> 
> I suggest that you add a log_err() message with above text into the
> board/emulation/common/qemu_capsule.c implementation of
> efi_get_public_key_data(). This way the user will see that he forgot a step.
> 
> Best regards
> 
> Heinrich
> 
> >   		goto out;
> > +	}
> > 
> >   	pkey = malloc(pkey_len);
> >   	if (!pkey)
> > 
>