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

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

Akashi-san,

On Tue, Jul 20, 2021 at 11:13:40AM +0900, AKASHI Takahiro wrote:
> 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."
> 

Correct.  My patch intentionally leaves out that part and I hope someone
will need it and implement it.

> 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".


Keep in mind that the makefile currently checks for the .esl file.  if the
file is not found there's a compilation error, prompting the user to add a
valid file


Thanks
/Ilias
> 
> -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)
> > > 
> >