[PATCH v7 04/11] capsule: authenticate: Add capsule public key in platform's dtb

[Sughosh Ganu]

On Sun, 6 Aug 2023 at 03:42, Tom Rini <trini at konsulko.com> wrote:
>
> On Sat, Aug 05, 2023 at 09:03:53AM -0600, Simon Glass wrote:
> > Hi Sughosh,
> >
> > On Sat, 5 Aug 2023 at 05:35, Sughosh Ganu <sughosh.ganu at linaro.org> 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 signature node in the u-boot dtsi file and include the public
> > > key through the capsule-key property. This file is per architecture,
> > > and is currently being added for sandbox and arm architectures. It
> > > will have to be added for other architectures which need to enable
> > > capsule authentication support.
> > >
> > > 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>
> > > ---
> > > Changes since V6:
> > > * Populate the CONFIG_EFI_CAPSULE_ESL_FILE symbol for sandbox and
> > >   sandbox_flattree which enable capsule authentication.
> > >
> > > Note:
> > > Simon Glass had asked me to rid of the CONFIG_EFI_HAVE_CAPSULE_SUPPORT
> > > ifdef used in the sandbox' u-boot.dtsi file. However, that results in
> > > the sandbox_vpl test failing in CI. Hence that check has been kept.
> > >
> > >
> > >  arch/arm/dts/u-boot.dtsi           | 14 ++++++++++++++
> > >  arch/sandbox/dts/u-boot.dtsi       | 17 +++++++++++++++++
>
> We've already had some go-round as to why this basically identical file
> can't be in like lib/efi_loader/ or something, yes?

Yes, these need to be under the arch/$(ARCH)/dts/ directory for the
dtc to include them as part of the platform's dts.

>
> > >  configs/sandbox_defconfig          |  1 +
> > >  configs/sandbox_flattree_defconfig |  1 +
> > >  lib/efi_loader/Kconfig             |  9 +++++++++
> > >  5 files changed, 42 insertions(+)
> > >  create mode 100644 arch/arm/dts/u-boot.dtsi
> > >  create mode 100644 arch/sandbox/dts/u-boot.dtsi
> > >
> > > diff --git a/arch/arm/dts/u-boot.dtsi b/arch/arm/dts/u-boot.dtsi
> > > new file mode 100644
> > > index 0000000000..4f31da4521
> > > --- /dev/null
> > > +++ b/arch/arm/dts/u-boot.dtsi
> > > @@ -0,0 +1,14 @@
> > > +// SPDX-License-Identifier: GPL-2.0+
> > > +/**
> > > + * Devicetree file with miscellaneous nodes that will be included
> > > + * at build time into the DTB. Currently being used for including
> > > + * capsule related information.
> > > + */
> > > +
> > > +#ifdef CONFIG_EFI_CAPSULE_AUTHENTICATE
> > > +/ {
> > > +       signature {
> > > +               capsule-key = /incbin/(CONFIG_EFI_CAPSULE_ESL_FILE);
> > > +       };
> > > +};
> > > +#endif /* CONFIG_EFI_CAPSULE_AUTHENTICATE */
> > > diff --git a/arch/sandbox/dts/u-boot.dtsi b/arch/sandbox/dts/u-boot.dtsi
> > > new file mode 100644
> > > index 0000000000..60bd004937
> > > --- /dev/null
> > > +++ b/arch/sandbox/dts/u-boot.dtsi
> > > @@ -0,0 +1,17 @@
> > > +// SPDX-License-Identifier: GPL-2.0+
> > > +/*
> > > + * Devicetree file with miscellaneous nodes that will be included
> > > + * at build time into the DTB. Currently being used for including
> > > + * capsule related information.
> > > + *
> > > + */
> > > +
> > > +#ifdef CONFIG_EFI_HAVE_CAPSULE_SUPPORT
> > > +/ {
> > > +#ifdef CONFIG_EFI_CAPSULE_AUTHENTICATE
> > > +       signature {
> > > +               capsule-key = /incbin/(CONFIG_EFI_CAPSULE_ESL_FILE);
> > > +       };
> > > +#endif
> > > +};
> > > +#endif /* CONFIG_EFI_HAVE_CAPSULE_SUPPORT */
>
> And why are these two different?

For the sandbox's u-boot.dtsi, we need CONFIG_EFI_CAPSULE_AUTHENTICATE
so that the ESL file is looked for only when capsule authentication is
enabled. The outer CONFIG_EFI_HAVE_CAPSULE_SUPPORT is to not include
stuff from this file unless capsule support is enabled. Simon had
asked me to rid of the outer ifdef, but the sandbox_vpl test fails
without it.

>
> > > diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> > > index a22e47616f..0d559ff3a1 100644
> > > --- a/lib/efi_loader/Kconfig
> > > +++ b/lib/efi_loader/Kconfig
> > > @@ -235,6 +235,15 @@ 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.

Okay

>
> > > +       depends on EFI_CAPSULE_AUTHENTICATE
> > > +       help
> > > +         Provides the absolute path to the EFI Signature List file which
> >
> > It isn't really an absolute path as it doesn't start with /
> >
> > You really can't/shouldn't use absolute paths in a U-Boot build.
>
> You can't as it will break reproducible builds (or make them harder than
> required).

Okay

-sughosh