zephyr: fix Mbed TLS configuration header file selection

Mbed TLS already provides MBEDTLS_CFG_FILE Kconfig when it's builtin. So
we only need to override that config when not using the builtin Mbed TLS
version.

This commit also fixes some hardcoding of "mcuboot-mbedtls-cfg.h" in
Kconfig and prj.conf.

Signed-off-by: Valerio Setti <[email protected]>

Author: valeriosetti

boot/zephyr/CMakeLists.txt

@@ -220,7 +220,7 @@ if(CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256 OR CONFIG_BOOT_ENCRYPT_EC256)
   # to set MBEDTLS_CONFIG_FILE ourselves. When using Zephyr's copy, this
   # variable is set by its Kconfig in the Zephyr codebase.
   zephyr_library_compile_definitions(
-    MBEDTLS_CONFIG_FILE="${CMAKE_CURRENT_LIST_DIR}/include/mcuboot-mbedtls-cfg.h"
+    MBEDTLS_CONFIG_FILE="${CONFIG_MBEDTLS_CFG_FILE}"
     )
 elseif(CONFIG_BOOT_SIGNATURE_TYPE_NONE)
   zephyr_library_include_directories(
@@ -266,7 +266,7 @@ elseif(CONFIG_BOOT_SIGNATURE_TYPE_ED25519 OR CONFIG_BOOT_ENCRYPT_X25519)
       ${TINYCRYPT_SHA512_DIR}/source/sha512.c
       )
     zephyr_library_compile_definitions(
-      MBEDTLS_CONFIG_FILE="${CMAKE_CURRENT_LIST_DIR}/include/mcuboot-mbedtls-cfg.h"
+      MBEDTLS_CONFIG_FILE="${CONFIG_MBEDTLS_CFG_FILE}"
       )
   else()
     zephyr_include_directories(include)

boot/zephyr/Kconfig

@@ -360,13 +360,12 @@ config MCUBOOT_CLEANUP_RAM
 	help
 	  Sets contents of memory to 0 before jumping to application.
 
-if MBEDTLS
-
 config MBEDTLS_CFG_FILE
-	default "config-tls-generic.h" if MBEDTLS_BUILTIN || BOOT_USE_PSA_CRYPTO
-	default "mcuboot-mbedtls-cfg.h" if BOOT_USE_MBEDTLS
-
-endif
+	# It might be awkward to define an Mbed TLS header file when TinyCrypt
+	# is used, but the fact is that Mbed TLS' ASN1 parse module is used
+	# also when TinyCrypt is used as crypto backend.
+	default "mcuboot-mbedtls-cfg.h" if BOOT_USE_TINYCRYPT
+	default "mcuboot-mbedtls-cfg.h" if BOOT_USE_MBEDTLS && !MBEDTLS_BUILTIN
 
 config BOOT_HW_KEY
 	bool "Use HW key for image verification"

boot/zephyr/prj.conf

@@ -1,7 +1,6 @@
 CONFIG_PM=n
 
 CONFIG_MAIN_STACK_SIZE=10240
-CONFIG_MBEDTLS_CFG_FILE="mcuboot-mbedtls-cfg.h"
 
 CONFIG_BOOT_SWAP_SAVE_ENCTLV=n
 CONFIG_BOOT_ENCRYPT_IMAGE=n