mbedtls: remove unused option MBEDTLS_SSL_EXPORT_KEYS

According to Mbed TLS changelog this feature was set default ON
since 3.1.0 release, so the build symbol is no more available.
This commit removes it from Zephyr.

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

Author: valeriosetti

doc/releases/migration-guide-4.0.rst

@@ -51,6 +51,10 @@ Mbed TLS
   * ``CONFIG_MBEDTLS_ENTROPY_ENABLED`` is now :kconfig:option:``CONFIG_MBEDTLS_ENTROPY_C``,
   * ``CONFIG_MBEDTLS_ZEPHYR_ENTROPY`` is now :kconfig:option:``CONFIG_MBEDTLS_ENTROPY_POLL_ZEPHYR``.
 
+* The Kconfig option ``CONFIG_MBEDTLS_SSL_EXPORT_KEYS`` was removed because the
+  corresponding build symbol was removed in Mbed TLS 3.1.0 and is now assumed to
+  be enabled. (:github:`77657`)
+
 Trusted Firmware-M
 ==================
 

modules/mbedtls/Kconfig.tls-generic

@@ -19,9 +19,6 @@ if MBEDTLS_TLS_VERSION_1_2
 config MBEDTLS_DTLS
 	bool "Support for DTLS"
 
-config MBEDTLS_SSL_EXPORT_KEYS
-	bool "Support for exporting SSL key block and master secret"
-
 config MBEDTLS_SSL_ALPN
 	bool "Support for setting the supported Application Layer Protocols"
 

modules/mbedtls/configs/config-tls-generic.h

@@ -324,10 +324,6 @@
 #define MBEDTLS_ENTROPY_C
 #endif
 
-#if defined(CONFIG_MBEDTLS_SSL_EXPORT_KEYS)
-#define MBEDTLS_SSL_EXPORT_KEYS
-#endif
-
 #if defined(CONFIG_MBEDTLS_SSL_ALPN)
 #define MBEDTLS_SSL_ALPN
 #endif

modules/openthread/CMakeLists.txt

@@ -163,6 +163,11 @@ endforeach()
 string(REPLACE " " ";" OT_PARAM_LIST " ${CONFIG_OPENTHREAD_CUSTOM_PARAMETERS}")
 target_compile_definitions(ot-config INTERFACE ${OT_PARAM_LIST})
 
+# Since Mbed TLS 3.1.0 MBEDTLS_SSL_EXPORT_KEYS was removed as build symbol and
+# it's always assumed to be enabled. Corresponding kconfig was removed from
+# Zephyr as well, but OpenThread code still uses it, so we add it here.
+target_compile_definitions(ot-config INTERFACE -DMBEDTLS_SSL_EXPORT_KEYS)
+
 # Zephyr compiler options
 target_include_directories(ot-config INTERFACE
     $<TARGET_PROPERTY:zephyr_interface,INTERFACE_INCLUDE_DIRECTORIES>

subsys/net/l2/openthread/Kconfig

@@ -193,7 +193,6 @@ config OPENTHREAD_MBEDTLS
 	select MBEDTLS_ECP_DP_SECP256R1_ENABLED if OPENTHREAD_COMMISSIONER || OPENTHREAD_JOINER || \
 	    OPENTHREAD_SRP_CLIENT || OPENTHREAD_SRP_SERVER
 	select MBEDTLS_ECP_NIST_OPTIM if OPENTHREAD_COMMISSIONER || OPENTHREAD_JOINER
-	select MBEDTLS_SSL_EXPORT_KEYS if OPENTHREAD_COMMISSIONER || OPENTHREAD_JOINER
 	select MBEDTLS_CTR_DRBG_ENABLED if OPENTHREAD_COMMISSIONER || OPENTHREAD_JOINER
 	select MBEDTLS_HMAC_DRBG_ENABLED if OPENTHREAD_COMMISSIONER || OPENTHREAD_JOINER || \
 	    OPENTHREAD_SRP_CLIENT || OPENTHREAD_SRP_SERVER