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

[Simon Glass]

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 ?

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

>  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 /

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

> +         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