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

[Sughosh Ganu]

hi Simon,

On Sat, 5 Aug 2023 at 20:34, Simon Glass <sjg at chromium.org> 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 +++++++++++++++++
> >  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 */
> > diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
> > index b6c4f735f2..779af4abc8 100644
> > --- a/configs/sandbox_defconfig
> > +++ b/configs/sandbox_defconfig
> > @@ -341,6 +341,7 @@ CONFIG_EFI_RUNTIME_UPDATE_CAPSULE=y
> >  CONFIG_EFI_CAPSULE_ON_DISK=y
> >  CONFIG_EFI_CAPSULE_FIRMWARE_RAW=y
> >  CONFIG_EFI_CAPSULE_AUTHENTICATE=y
> > +CONFIG_EFI_CAPSULE_ESL_FILE="../../../board/sandbox/SIGNER.esl"
>
> Can we avoid the path here, and just use e.g. good.esl ?

Unfortunately no. I believe the way incbin works in dts is that it
looks for the binary to be included in the same directory as the dts.
Which is why I have to point it to the location of the esl relative to
the dts.

>
> Perhaps this could be fixed up later, e.g. by adding the board
> directory as an include dir when building the DT?

Again, this is not how incbin seems to work in dts. I tried putting
the esl in one of the existing include directory locations, but it
does not pick the file from those dirs. It works with the assumption
that the bin file is to be in the same dir as the dts.

>
> >  CONFIG_EFI_SECURE_BOOT=y
> >  CONFIG_TEST_FDTDEC=y
> >  CONFIG_UNIT_TEST=y
> > diff --git a/configs/sandbox_flattree_defconfig b/configs/sandbox_flattree_defconfig
> > index 8aa295686d..0ca2e4a5ae 100644
> > --- a/configs/sandbox_flattree_defconfig
> > +++ b/configs/sandbox_flattree_defconfig
> > @@ -227,6 +227,7 @@ CONFIG_EFI_RUNTIME_UPDATE_CAPSULE=y
> >  CONFIG_EFI_CAPSULE_ON_DISK=y
> >  CONFIG_EFI_CAPSULE_FIRMWARE_FIT=y
> >  CONFIG_EFI_CAPSULE_AUTHENTICATE=y
> > +CONFIG_EFI_CAPSULE_ESL_FILE="../../../board/sandbox/SIGNER.esl"
> >  CONFIG_UNIT_TEST=y
> >  CONFIG_UT_TIME=y
> >  CONFIG_UT_DM=y
> > 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 ""
> > +       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 /

Will change

>
> You really can't/shouldn't use absolute paths in a U-Boot build.

Okay

-sughosh

>
> > +         will be embedded in the platform's device tree and used for
> > +         capsule authentication at the time of capsule update.
> > +
> >  config EFI_DEVICE_PATH_TO_TEXT
> >         bool "Device path to text protocol"
> >         default y
> > --
> > 2.34.1
> >
>
> Regards,
> Simon