[RFC PATCH v2 1/2] fastboot: introduce 'oem board' subcommand
Mattijs Korpershoek
mkorpershoek at baylibre.com
Thu Feb 15 10:14:13 CET 2024
Hi Alexey,
Thank you for the patch.
On jeu., févr. 01, 2024 at 12:20, Alexey Romanov <avromanov at salutedevices.com> wrote:
> Currently, fastboot protocol in U-Boot has no opportunity
> to execute vendor custom code with verifed boot. This patch
> introduce new fastboot subcommand fastboot oem board:<cmd>,
> which allow to run custom oem_board function.
>
> Default implementation is __weak. Vendor must redefine it in
> board/ folder with his own logic.
>
> For example, some vendors have their custom nand/emmc partition
> flashing or erasing. Here some typical command for such use cases:
>
> - flashing:
>
> $ fastboot stage bootloader.img
> $ fastboot oem board:write_bootloader
>
> - erasing:
>
> $ fastboot oem board:erase_env
>
> Signed-off-by: Alexey Romanov <avromanov at salutedevices.com>
Sorry for the delay. I needed time to give this some thoughts and I
waited for Sean to chime as well on this.
I've heard from Neil that this might be related to:
https://github.com/superna9999/pyamlboot/pull/20
I think this can be useful. Not necessarily for writing custom
partitions, but I see this could be used for other things:
1. Provision SoC-specific fuses (serialno/mac addr) at the factory line
(for production devices)
Examples:
$ fastboot oem board:write_serialno ABCDEF
$ fastboot oem board:write_macaddr AA:BB:CC:DD:EE
2. Access secure storage (via an Trusted Application)
But both examples could also be in a fastboot flash format:
$ fastboot flash serialno ABCDEF
One concern I have is that U-Boot forks might use this command as
an excuse to not makes things generic.
I hope that others will chime in on this as well.
I'd like to discuss this more because once this command is in we cannot
remove it later.
> ---
> drivers/fastboot/Kconfig | 7 +++++++
> drivers/fastboot/fb_command.c | 15 +++++++++++++++
> include/fastboot.h | 1 +
> 3 files changed, 23 insertions(+)
>
> diff --git a/drivers/fastboot/Kconfig b/drivers/fastboot/Kconfig
> index a4313d60a9..4d94391a76 100644
> --- a/drivers/fastboot/Kconfig
> +++ b/drivers/fastboot/Kconfig
> @@ -241,6 +241,13 @@ config FASTBOOT_OEM_RUN
> this feature if you are using verified boot, as it will allow an
> attacker to bypass any restrictions you have in place.
>
> +config FASTBOOT_OEM_BOARD
> + bool "Enable the 'oem board' command"
> + help
> + This extends the fastboot protocol with an "oem board" command. This
> + command allows running vendor custom code defined in board/ files.
> + Otherwise, it will do nothing and send fastboot fail.
If we move forward with this, please also document the new command in:
doc/android/fastboot.rst
> +
> endif # FASTBOOT
>
> endmenu
> diff --git a/drivers/fastboot/fb_command.c b/drivers/fastboot/fb_command.c
> index 5fcadcdf50..2298815770 100644
> --- a/drivers/fastboot/fb_command.c
> +++ b/drivers/fastboot/fb_command.c
> @@ -40,6 +40,7 @@ static void reboot_recovery(char *, char *);
> static void oem_format(char *, char *);
> static void oem_partconf(char *, char *);
> static void oem_bootbus(char *, char *);
> +static void oem_board(char *, char *);
> static void run_ucmd(char *, char *);
> static void run_acmd(char *, char *);
>
> @@ -107,6 +108,10 @@ static const struct {
> .command = "oem run",
> .dispatch = CONFIG_IS_ENABLED(FASTBOOT_OEM_RUN, (run_ucmd), (NULL))
> },
> + [FASTBOOT_COMMAND_OEM_BOARD] = {
> + .command = "oem board",
> + .dispatch = CONFIG_IS_ENABLED(FASTBOOT_OEM_BOARD, (oem_board), (NULL))
> + },
> [FASTBOOT_COMMAND_UCMD] = {
> .command = "UCmd",
> .dispatch = CONFIG_IS_ENABLED(FASTBOOT_UUU_SUPPORT, (run_ucmd), (NULL))
> @@ -490,3 +495,13 @@ static void __maybe_unused oem_bootbus(char *cmd_parameter, char *response)
> else
> fastboot_okay(NULL, response);
> }
> +
> +void __weak fastboot_oem_board(char *cmd_parameter, void *data, u32 size, char *response)
> +{
> + fastboot_fail("oem board function not defined", response);
> +}
> +
> +static void __maybe_unused oem_board(char *cmd_parameter, char *response)
> +{
> + fastboot_oem_board(cmd_parameter, fastboot_buf_addr, image_size, response);
> +}
> diff --git a/include/fastboot.h b/include/fastboot.h
> index 296451f89d..06c1f26b6c 100644
> --- a/include/fastboot.h
> +++ b/include/fastboot.h
> @@ -37,6 +37,7 @@ enum {
> FASTBOOT_COMMAND_OEM_PARTCONF,
> FASTBOOT_COMMAND_OEM_BOOTBUS,
> FASTBOOT_COMMAND_OEM_RUN,
> + FASTBOOT_COMMAND_OEM_BOARD,
> FASTBOOT_COMMAND_ACMD,
> FASTBOOT_COMMAND_UCMD,
> FASTBOOT_COMMAND_COUNT
> --
> 2.30.1
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