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@salutedevices.com Reviewed-by: Mattijs Korpershoek mkorpershoek@baylibre.com --- doc/android/fastboot.rst | 18 ++++++++++++++++++ drivers/fastboot/Kconfig | 7 +++++++ drivers/fastboot/fb_command.c | 30 ++++++++++++++++++++++++++++++ include/fastboot.h | 1 + 4 files changed, 56 insertions(+)
diff --git a/doc/android/fastboot.rst b/doc/android/fastboot.rst index 1ad8a897c8..2a627f9890 100644 --- a/doc/android/fastboot.rst +++ b/doc/android/fastboot.rst @@ -29,6 +29,7 @@ The following OEM commands are supported (if enabled): with <arg> = boot_ack boot_partition - ``oem bootbus`` - this executes ``mmc bootbus %x %s`` to configure eMMC - ``oem run`` - this executes an arbitrary U-Boot command +- ``oem board`` - this executes a custom board function which is defined by the vendor
Support for both eMMC and NAND devices is included.
@@ -245,6 +246,23 @@ including multiple commands (using e.g. ``;`` or ``&&``) and control structures (``if``, ``while``, etc.). The exit code of ``fastboot`` will reflect the exit code of the command you ran.
+Running Custom Vendor Code +^^^^^^^^^^^^^^^^^^^^^^^^^^ + +U-Boot allows you to execute custom fastboot logic, which can be defined +in board/ files. It can still be used for production devices with verified +boot, because the vendor define logic at compile time by implementing +fastboot_oem_board() function. The attacker will not be able to execute +custom commands / code. For example, this can be useful for custom flashing +or erasing protocols:: + + $ fastboot stage bootloader.img + $ fastboot oem board:write_bootloader + +In this case, ``cmd_parameter`` argument of the function ``fastboot_oem_board()`` +will contain string "write_bootloader" and ``data`` argument is a pointer to +fastboot input buffer, which contains the contents of bootloader.img file. + References ----------
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. + endif # FASTBOOT
endmenu diff --git a/drivers/fastboot/fb_command.c b/drivers/fastboot/fb_command.c index 5fcadcdf50..da29211db1 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 +495,28 @@ static void __maybe_unused oem_bootbus(char *cmd_parameter, char *response) else fastboot_okay(NULL, response); } + +/** + * fastboot_oem_board() - Execute the OEM board command. This is default + * weak implementation, which may be overwritten in board/ files. + * + * @cmd_parameter: Pointer to command parameter + * @data: Pointer to fastboot input buffer + * @size: Size of the fastboot input buffer + * @response: Pointer to fastboot response buffer + */ +void __weak fastboot_oem_board(char *cmd_parameter, void *data, u32 size, char *response) +{ + fastboot_fail("oem board function not defined", response); +} + +/** + * oem_board() - Execute the OEM board command + * + * @cmd_parameter: Pointer to command parameter + * @response: Pointer to fastboot response buffer + */ +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