STM32: guard mbedTLS 3 entropy integration

Keep the STM32 mbedTLS integration on its existing MbedTLS 3 path while allowing the mbedTLS 4 support series to build around it.

The STM32 platform does not enable MbedTLS 4 here; this only hides the legacy entropy and CTR_DRBG context code, hooks, and config disables when building against MbedTLS 4 headers.

Signed-off-by: Peter M <petermm@gmail.com>

Author: petermm

src/platforms/stm32/src/lib/mbedtls_stm32_user_config.h

@@ -21,18 +21,21 @@
 #ifndef MBEDTLS_STM32_USER_CONFIG_H
 #define MBEDTLS_STM32_USER_CONFIG_H
 
-#define MBEDTLS_NO_PLATFORM_ENTROPY
 #define MBEDTLS_PLATFORM_MS_TIME_ALT
 
 #undef MBEDTLS_HAVE_TIME_DATE
 #undef MBEDTLS_TIMING_C
 
+#if !defined(MBEDTLS_VERSION_NUMBER) || MBEDTLS_VERSION_NUMBER < 0x04000000
+#define MBEDTLS_NO_PLATFORM_ENTROPY
+
 #undef MBEDTLS_PSA_CRYPTO_C
 #undef MBEDTLS_PSA_CRYPTO_STORAGE_C
 #undef MBEDTLS_PSA_ITS_FILE_C
 #undef MBEDTLS_PSA_CRYPTO_CLIENT
 #undef MBEDTLS_PSA_INJECT_ENTROPY
 #undef MBEDTLS_LMS_C
+#endif
 
 #undef MBEDTLS_FS_IO
 

src/platforms/stm32/src/lib/stm_sys.h

@@ -27,9 +27,12 @@
 #include "stm32_hal_platform.h"
 
 #ifdef ATOMVM_HAS_MBEDTLS
+#include <mbedtls/version.h>
+#if MBEDTLS_VERSION_NUMBER < 0x04000000
 #include <mbedtls/ctr_drbg.h>
 #include <mbedtls/entropy.h>
 #endif
+#endif
 
 #define STM32_ATOM globalcontext_make_atom(ctx->global, ATOM_STR("\x5", "stm32"))
 
@@ -53,11 +56,13 @@ struct STM32PlatformData
     struct ListHead locked_pins;
 #ifdef ATOMVM_HAS_MBEDTLS
     RNG_HandleTypeDef rng;
+#if MBEDTLS_VERSION_NUMBER < 0x04000000
     mbedtls_entropy_context entropy_ctx;
     mbedtls_ctr_drbg_context random_ctx;
     bool entropy_is_initialized;
     bool random_is_initialized;
 #endif
+#endif
 };
 
 void sys_init_icache(void);

src/platforms/stm32/src/lib/sys.c

@@ -27,19 +27,18 @@
 #include <defaultatoms.h>
 #include <scheduler.h>
 #include <sys.h>
-#if ATOMVM_HAS_MBEDTLS
-#include <sys_mbedtls.h>
-#endif
 
 #ifdef ATOMVM_HAS_MBEDTLS
 #include <mbedtls/platform_time.h>
 #include <sys_mbedtls.h>
 
+#if MBEDTLS_VERSION_NUMBER < 0x04000000
 /* Minimum bytes the entropy pool collects from a hardware source before
  * it's considered seeded. mbedTLS defines this as MBEDTLS_ENTROPY_MIN_HARDWARE
  * in the private library/entropy_poll.h header; use the same value. */
 #define STM32_ENTROPY_MIN_HARDWARE 32
 #endif
+#endif
 
 // #define ENABLE_TRACE
 #include <trace.h>
@@ -226,7 +225,7 @@ void sys_init_platform(GlobalContext *glb)
         AVM_LOGE(TAG, "Out of memory!");
         AVM_ABORT();
     }
-#if ATOMVM_HAS_MBEDTLS
+#ifdef ATOMVM_HAS_MBEDTLS
 #if MBEDTLS_VERSION_NUMBER >= 0x04000000
     psa_status_t status = psa_crypto_init();
     if (status != PSA_SUCCESS) {
@@ -237,8 +236,10 @@ void sys_init_platform(GlobalContext *glb)
     glb->platform_data = platform;
     list_init(&platform->locked_pins);
 #ifdef ATOMVM_HAS_MBEDTLS
+#if MBEDTLS_VERSION_NUMBER < 0x04000000
     platform->entropy_is_initialized = false;
     platform->random_is_initialized = false;
+#endif
     if (stm32_rng_hw_init(platform) != 0) {
         AVM_LOGE(TAG, "Failed to initialize RNG peripheral");
         AVM_ABORT();
@@ -250,12 +251,14 @@ void sys_free_platform(GlobalContext *glb)
 {
     struct STM32PlatformData *platform = glb->platform_data;
 #ifdef ATOMVM_HAS_MBEDTLS
+#if MBEDTLS_VERSION_NUMBER < 0x04000000
     if (platform->random_is_initialized) {
         mbedtls_ctr_drbg_free(&platform->random_ctx);
     }
     if (platform->entropy_is_initialized) {
         mbedtls_entropy_free(&platform->entropy_ctx);
     }
+#endif
     // HAL_RNG_Init succeeded in stm32_rng_hw_init or we aborted
     HAL_RNG_DeInit(&platform->rng);
 #endif
@@ -486,6 +489,7 @@ static int stm32_rng_hw_init(struct STM32PlatformData *platform)
     return 0;
 }
 
+#if MBEDTLS_VERSION_NUMBER < 0x04000000
 int mbedtls_hardware_poll(void *data, unsigned char *output, size_t len, size_t *olen)
 {
     GlobalContext *global = data;
@@ -511,12 +515,14 @@ int mbedtls_hardware_poll(void *data, unsigned char *output, size_t len, size_t
     *olen = written;
     return 0;
 }
+#endif
 
 mbedtls_ms_time_t mbedtls_ms_time(void)
 {
     return (mbedtls_ms_time_t) HAL_GetTick();
 }
 
+#if MBEDTLS_VERSION_NUMBER < 0x04000000
 int sys_mbedtls_entropy_func(void *entropy, unsigned char *buf, size_t size)
 {
     return mbedtls_entropy_func(entropy, buf, size);
@@ -572,4 +578,5 @@ void sys_mbedtls_ctr_drbg_context_unlock(GlobalContext *global)
     UNUSED(global);
 }
 
+#endif
 #endif /* ATOMVM_HAS_MBEDTLS */