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
----------
diff --git a/drivers/fastboot/Kconfig b/drivers/fastboot/Kconfig
index d6e2be0..0773248 100644
--- a/drivers/fastboot/Kconfig
+++ b/drivers/fastboot/Kconfig
@@ -252,6 +252,13 @@
Add support for the "oem console" command to input and read console
record buffer.
+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 b8782bf..e6d5848 100644
--- a/drivers/fastboot/fb_command.c
+++ b/drivers/fastboot/fb_command.c
@@ -43,6 +43,7 @@
static void oem_partconf(char *, char *);
static void oem_bootbus(char *, char *);
static void oem_console(char *, char *);
+static void oem_board(char *, char *);
static void run_ucmd(char *, char *);
static void run_acmd(char *, char *);
@@ -114,6 +115,10 @@
.command = "oem console",
.dispatch = CONFIG_IS_ENABLED(FASTBOOT_CMD_OEM_CONSOLE, (oem_console), (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))
@@ -549,3 +554,28 @@
else
fastboot_response(FASTBOOT_MULTIRESPONSE_START, response, NULL);
}
+
+/**
+ * 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, (void *)fastboot_buf_addr, image_size, response);
+}
diff --git a/include/fastboot.h b/include/fastboot.h
index c75184c..626221b 100644
--- a/include/fastboot.h
+++ b/include/fastboot.h
@@ -48,6 +48,7 @@
FASTBOOT_COMMAND_OEM_BOOTBUS,
FASTBOOT_COMMAND_OEM_RUN,
FASTBOOT_COMMAND_OEM_CONSOLE,
+ FASTBOOT_COMMAND_OEM_BOARD,
FASTBOOT_COMMAND_ACMD,
FASTBOOT_COMMAND_UCMD,
FASTBOOT_COMMAND_COUNT