[RFC PATCH v2 1/2] fastboot: introduce 'oem board' subcommand

[Alexey Romanov]

Hello,

On Thu, Feb 15, 2024 at 10:14:13AM +0100, Mattijs Korpershoek wrote:
> Hi Alexey,
> 
> Thank you for the patch.
> 
> On jeu., f'evr. 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

Yeah, pyamlboot also uses the same 'bootloader' partition flashing
scheme as I present in the patch 2. This is custom Amlogic protocol.

> 
> 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)

Agree, you are completely right.

> 
> But both examples could also be in a fastboot flash format:
> $ fastboot flash serialno ABCDEF

But this case requires to 'serialno' partition definition in schema?
I didn't fully understand you.

> 
> 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

-- 
Thank you,
Alexey