fastboot: introduce 'oem board' subcommand
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>
Reviewed-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Link: https://lore.kernel.org/r/20240418100129.1691822-2-avromanov@salutedevices.com
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
diff --git a/doc/android/fastboot.rst b/doc/android/fastboot.rst
index 9e337ca..1a60968 100644
--- a/doc/android/fastboot.rst
+++ b/doc/android/fastboot.rst
@@ -30,6 +30,7 @@
- ``oem bootbus`` - this executes ``mmc bootbus %x %s`` to configure eMMC
- ``oem run`` - this executes an arbitrary U-Boot command
- ``oem console`` - this dumps U-Boot console record buffer
+- ``oem board`` - this executes a custom board function which is defined by the vendor
Support for both eMMC and NAND devices is included.
@@ -247,6 +248,23 @@
(``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 defines 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
----------