[RFC PATCH 2/4] scripts/Makefile.lib: Embed capsule public key in platform's dtb

[Sughosh Ganu]

hi Tom,

On Mon, 14 Aug 2023 at 20:34, Tom Rini <trini at konsulko.com> wrote:
>
> On Mon, Aug 14, 2023 at 02:33:07PM +0530, Sughosh Ganu wrote:
> > The EFI capsule authentication logic in u-boot expects the public key
> > in the form of an EFI Signature List(ESL) to be provided as part of
> > the platform's dtb. Currently, the embedding of the ESL file into the
> > dtb needs to be done manually.
> >
> > Add a target for generating a dtsi file which contains the signature
> > node with the ESL file included as a property under the signature
> > node. Include the dtsi file in the dtb. This brings the embedding of
> > the ESL in the dtb into the U-Boot build flow.
> >
> > The path to the ESL file is specified through the
> > CONFIG_EFI_CAPSULE_ESL_FILE symbol.
> >
> > Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> > ---
> >  lib/efi_loader/Kconfig             |  9 +++++++++
> >  lib/efi_loader/capsule_esl.dtsi.in | 11 +++++++++++
> >  scripts/Makefile.lib               | 17 +++++++++++++++++
> >  3 files changed, 37 insertions(+)
> >  create mode 100644 lib/efi_loader/capsule_esl.dtsi.in
> >
> > diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> > index 9989e3f384..f40a62a0ba 100644
> > --- a/lib/efi_loader/Kconfig
> > +++ b/lib/efi_loader/Kconfig
> > @@ -272,6 +272,15 @@ config EFI_CAPSULE_MAX
> >         Select the max capsule index value used for capsule report
> >         variables. This value is used to create CapsuleMax variable.
> >
> > +config EFI_CAPSULE_ESL_FILE
> > +     string "Path to the EFI Signature List File"
> > +     default ""
>
> No default.

I think Simon wanted to keep this so that it would not break the build
if no option was provided.

>
> [snip]
> > diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> > index f41b16781d..cf4eef0b05 100644
> > --- a/scripts/Makefile.lib
> > +++ b/scripts/Makefile.lib
> > @@ -334,8 +334,25 @@ cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
> >               ; \
> >       sed "s:$(pre-tmp):$(<):" $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile)
> >
> > +ifdef CONFIG_EFI_CAPSULE_AUTHENTICATE
> > +quiet_cmd_capsule_esl_gen = CAPSULE_ESL_GEN $@
> > +cmd_capsule_esl_gen = \
> > +     $(shell sed "s:ESL_BIN_FILE:$(capsule_esl_path):" $(capsule_esl_input_file) > $@)
> > +
> > +$(obj)/.capsule_esl.dtsi:
> > +     $(call cmd_capsule_esl_gen)
> > +
> > +capsule_esl_input_file=$(srctree)/lib/efi_loader/capsule_esl.dtsi.in
> > +capsule_esl_dtsi = .capsule_esl.dtsi
> > +capsule_esl_path=$(abspath $(srctree)/$(subst $(quote),,$(CONFIG_EFI_CAPSULE_ESL_FILE)))
>
> This seems right.
>
> > +include_files += $(capsule_esl_dtsi)
> > +
> > +$(obj)/%.dtb: $(src)/%.dts $(DTC) $(obj)/.capsule_esl.dtsi FORCE
> > +     $(call if_changed_dep,dtc)
> > +else
> >  $(obj)/%.dtb: $(src)/%.dts $(DTC) FORCE
> >       $(call if_changed_dep,dtc)
> > +endif
>
> I think this implies to me that we should have been depending on
> $(include_files) (once renamed to be less vague) here already ?

Okay. That can be done. I had kept the .capsule_esl.dtsi as a
dependency primarily because that file needs to be generated before it
can be included. I suppose the same can apply to some other dtsi as
well.

-sughosh