On Fri, May 31, 2024 at 03:50:34PM +0200, Caleb Connolly wrote:
> As more boards adopt support for the EFI CapsuleUpdate mechanism, there
> is a growing issue of being able to target updates to them properly. The
> current mechanism of hardcoding UUIDs for each board at compile time is
> unsustainable, and maintaining lists of GUIDs is similarly cumbersome.
>
> In this series, I propose that we adopt v5 GUIDs, these are generated
> by using a well-known salt GUID as well as board specific information
> (like the model/revision), these are hashed together and the result is
> truncated to form a new UUID.
Dear Caleb,
Thank you for working on this proposal, this looks very useful.
Indeed, we found out during SystemReady certifications that it is easy for
unique ids to be inadvertently re-used, making them thus non-unique.
I have a doubt regarding the format of the generated UUIDs, which end up in the
ESRT, though.
Here is a quick experiment on the sandbox booting with a DTB using the efidebug
command.
With the patch series, rebased on the master branch:
$ make sandbox_defconfig
$ make
$ ./u-boot --default_fdt
...
U-Boot 2024.07-rc4-00028-g1c96225b0b3 (Jun 19 2024 - 15:29:04 +0200)
...
Model: sandbox
...
Hit any key to stop autoboot: 0
=> efidebug capsule esrt
...
========================================
ESRT: fw_resource_count=2
ESRT: fw_resource_count_max=2
ESRT: fw_resource_version=1
[entry 0]==============================
ESRT: fw_class=FD5DB83C-12F3-A46B-80A9-E3007C7FF56E
...
[entry 1]==============================
ESRT: fw_class=935FE837-FAC8-4394-C008-737D8852C60D
...
========================================
$ uuid -d FD5DB83C-12F3-A46B-80A9-E3007C7FF56E
encode: STR: fd5db83c-12f3-a46b-80a9-e3007c7ff56e
SIV: 336781303264349553179461347850802165102
decode: variant: DCE 1.1, ISO/IEC 11578:1996
version: 10 (unknown)
content: FD:5D:B8:3C:12:F3:04:6B:00:A9:E3:00:7C:7F:F5:6E
(not decipherable: unknown UUID version)
Version 10 does not look right.
$ uuid -d 935FE837-FAC8-4394-C008-737D8852C60D
encode: STR: 935fe837-fac8-4394-c008-737d8852c60d
SIV: 195894493536133784175416063449172723213
decode: variant: reserved (Microsoft GUID)
version: 4 (random data based)
content: 93:5F:E8:37:FA:C8:03:94:00:08:73:7D:88:52:C6:0D
(no semantics: random data only)
A reserved Microsoft GUID variant does not look right.
With the master branch, the (hardcoded) GUIDs are ok:
$ ./u-boot --default_fdt
...
U-Boot 2024.07-rc4-00021-gfe2ce09a075 (Jun 19 2024 - 15:35:08 +0200)
...
Model: sandbox
...
=> efidebug capsule esrt
...
========================================
ESRT: fw_resource_count=2
ESRT: fw_resource_count_max=2
ESRT: fw_resource_version=1
[entry 0]==============================
ESRT: fw_class=09D7CF52-0720-4710-91D1-08469B7FE9C8
...
[entry 1]==============================
ESRT: fw_class=5A7021F5-FEF2-48B4-AABA-832E777418C0
...
========================================
$ uuid -d 09D7CF52-0720-4710-91D1-08469B7FE9C8
encode: STR: 09d7cf52-0720-4710-91d1-08469b7fe9c8
SIV: 13083600744351929150374221048734280136
decode: variant: DCE 1.1, ISO/IEC 11578:1996
version: 4 (random data based)
content: 09:D7:CF:52:07:20:07:10:11:D1:08:46:9B:7F:E9:C8
(no semantics: random data only)
$ uuid -d 5A7021F5-FEF2-48B4-AABA-832E777418C0
encode: STR: 5a7021f5-fef2-48b4-aaba-832e777418c0
SIV: 120212745678117161641696128857923655872
decode: variant: DCE 1.1, ISO/IEC 11578:1996
version: 4 (random data based)
content: 5A:70:21:F5:FE:F2:08:B4:2A:BA:83:2E:77:74:18:C0
(no semantics: random data only)
Also, this is what to expect for a v5 UUID [1]:
$ uuid -d a8f6ae40-d8a7-58f0-be05-a22f94eca9ec
encode: STR: a8f6ae40-d8a7-58f0-be05-a22f94eca9ec
SIV: 224591142595989943290477237735758014956
decode: variant: DCE 1.1, ISO/IEC 11578:1996
version: 5 (name based, SHA-1)
content: A8:F6:AE:40:D8:A7:08:F0:3E:05:A2:2F:94:EC:A9:EC
(not decipherable: truncated SHA-1 message digest only)
Best regards,
Vincent.
[1] https://uuid.ramsey.dev/en/stable/rfc4122/version5.html
>
> The well-known salt GUID can be specific to the architecture (SoC
> vendor), or OEM. It is defined in the board defconfig so that vendors
> can easily bring their own.
>
> Specifically, the following fields are used to generate a GUID for a
> particular fw_image:
>
> * namespace salt
> * board compatible (usually the first entry in the dt root compatible
> array).
> * fw_image name (the string identifying the specific image, especially
> relevant for board that can update multiple images).
>
> == Usage ==
>
> Boards can integrate dynamic UUID support as follows:
>
> 1. Adjust Kconfig to depend on EFI_CAPSULE_DYNAMIC_UUIDS if
> EFI_HAVE_CAPSULE_SUPPORT.
> 2. Skip setting the fw_images image_type_id property.
> 3. Generate a UUID and set CONFIG_EFI_CAPSULE_NAMESPACE_UUID in your
> defconfig.
>
> == Limitations ==
>
> * Changing GUIDs
>
> The primary limitation with this approach is that if any of the source
> fields change, so will the GUID for the board. It is therefore pretty
> important to ensure that GUID changes are caught during development.
>
> * Supporting multiple boards with a single image
>
> This now requires having an entry with the GUID for every board which
> might lead to larger UpdateCapsule images.
>
> == Tooling ==
>
> This series introduces a new tool: genguid. This can be used to generate
> the same GUIDs that the board would at runtime.
>
> This series follows a related discussion started by Ilias:
> https://lore.kernel.org/u-boot/cac_iwjjnha4gmf897mqyzndbgjfg8k4kwgstxwuy72wkyli...@mail.gmail.com/
>
> ---
> Changes in v3:
> - Add manpage for genguid
> - Add dedicated CONFIG_TOOLS_GENGUID option
> - Minor code fixes addressing v2 feedback
> - Link to v2:
> https://lore.kernel.org/r/20240529-b4-dynamic-uuid-v2-0-c26f31057...@linaro.org
>
> Changes in v2:
> - Move namespace UUID to be defined in defconfig
> - Add tests and tooling
> - Only use the first board compatible to generate UUID.
> - Link to v1:
> https://lore.kernel.org/r/20240426-b4-dynamic-uuid-v1-0-e8154e00e...@linaro.org
>
> ---
> Caleb Connolly (7):
> lib: uuid: add UUID v5 support
> efi: add a helper to generate dynamic UUIDs
> doc: uefi: document dynamic UUID generation
> sandbox: switch to dynamic UUIDs
> lib: uuid: supporting building as part of host tools
> tools: add genguid tool
> test: lib/uuid: add unit tests for dynamic UUIDs
>
> arch/Kconfig | 1 +
> board/sandbox/sandbox.c | 16 ---
> configs/sandbox_defconfig | 1 +
> configs/sandbox_flattree_defconfig | 1 +
> doc/develop/uefi/uefi.rst | 31 +++++
> doc/genguid.1 | 52 +++++++
> include/sandbox_efi_capsule.h | 6 +-
> include/uuid.h | 21 ++-
> lib/Kconfig | 8 ++
> lib/efi_loader/Kconfig | 23 +++
> lib/efi_loader/efi_capsule.c | 1 +
> lib/efi_loader/efi_firmware.c | 66 +++++++++
> lib/uuid.c | 81 +++++++++--
> test/lib/uuid.c | 88 ++++++++++++
> .../test_efi_capsule/test_capsule_firmware_fit.py | 2 +-
> .../test_efi_capsule/test_capsule_firmware_raw.py | 8 +-
> .../test_capsule_firmware_signed_fit.py | 2 +-
> .../test_capsule_firmware_signed_raw.py | 4 +-
> test/py/tests/test_efi_capsule/version.dts | 6 +-
> tools/Kconfig | 7 +
> tools/Makefile | 3 +
> tools/binman/etype/efi_capsule.py | 2 +-
> tools/binman/ftest.py | 2 +-
> tools/genguid.c | 154
> +++++++++++++++++++++
> 24 files changed, 538 insertions(+), 48 deletions(-)
> ---
> change-id: 20240422-b4-dynamic-uuid-1a5ab1486c27
> base-commit: 2e682a4a406fc81ef32e05c28542cc8067f1e15f
>
> // Caleb (they/them)
>
