[PATCH v4 03/11] efi_loader: capsule: add back efi_get_public_key_data()

[Simon Glass]

Hi Masami,

On Wed, 20 Oct 2021 at 02:18, Masami Hiramatsu
<masami.hiramatsu at linaro.org> wrote:
>
> Hi Simon,
>
> 2021年10月15日(金) 9:40 Simon Glass <sjg at chromium.org>:
> >
> > Hi Takahiro,
> >
> > On Thu, 7 Oct 2021 at 00:25, AKASHI Takahiro <takahiro.akashi at linaro.org> wrote:
> > >
> > > The commit 47a25e81d35c ("Revert "efi_capsule: Move signature from DTB to
> > > .rodata"") failed to revert the removal of efi_get_public_key_data().
> > >
> > > Add back this function and move it under lib/efi_loader so that other
> > > platforms can utilize it. It is now declared as a weak function so that
> > > it can be replaced with a platform-specific implementation.
> > >
> > > Fixes: 47a25e81d35c ("Revert "efi_capsule: Move signature from DTB to
> > >         .rodata"")
> > > Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> > > ---
> > >  lib/efi_loader/efi_capsule.c | 36 ++++++++++++++++++++++++++++++++++++
> > >  1 file changed, 36 insertions(+)
> > >
> > > diff --git a/lib/efi_loader/efi_capsule.c b/lib/efi_loader/efi_capsule.c
> > > index b75e4bcba1a9..44f5da61a9be 100644
> > > --- a/lib/efi_loader/efi_capsule.c
> > > +++ b/lib/efi_loader/efi_capsule.c
> > > @@ -11,15 +11,20 @@
> > >  #include <common.h>
> > >  #include <efi_loader.h>
> > >  #include <efi_variable.h>
> > > +#include <env.h>
> > > +#include <fdtdec.h>
> > >  #include <fs.h>
> > >  #include <malloc.h>
> > >  #include <mapmem.h>
> > >  #include <sort.h>
> > > +#include <asm/global_data.h>
> > >
> > >  #include <crypto/pkcs7.h>
> > >  #include <crypto/pkcs7_parser.h>
> > >  #include <linux/err.h>
> > >
> > > +DECLARE_GLOBAL_DATA_PTR;
> > > +
> > >  const efi_guid_t efi_guid_capsule_report = EFI_CAPSULE_REPORT_GUID;
> > >  static const efi_guid_t efi_guid_firmware_management_capsule_id =
> > >                 EFI_FIRMWARE_MANAGEMENT_CAPSULE_ID_GUID;
> > > @@ -251,6 +256,37 @@ out:
> > >  }
> > >
> > >  #if defined(CONFIG_EFI_CAPSULE_AUTHENTICATE)
> > > +int __weak efi_get_public_key_data(void **pkey, efi_uintn_t *pkey_len)
> >
> > I don't think this should be weak. What other way is there of handling
> > this and why would it be platform-specific?
>
> I have a question about the current design of the capsule auth key.
> If the platform has its own key-storage, how can the platform use the
> platform specific storage? Does such platform load the key from the storage
> and generate the dtb node in the platform initialization code? (or
> device driver?)

Are we talking about a public key (which I assume from the function
naming) or some secret key. What is an auth key?

As I understand it, the public key should be provided by the platform
in devicetree that U-Boot uses, by whatever prior stage has access to
the key.

Regards,
Simon