pico mbedtls

CHANGELOG.md

@@ -26,7 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Crypto functions on generic_unix platform now rely on MbedTLS instead of OpenSSL
 - Platform function providing time used by timers was changed from `sys_monotonic_millis` to `sys_monotonic_time_u64`, `sys_monotonic_time_u64_to_ms` and `sys_monotonic_time_ms_to_u64`.
 - Implement `atomvm:random/0` and `atomvm:rand_bytes/1` on top of `crypto:strong_rand_bytes/1` on
-  generic_unix platform and ESP32
+  generic_unix, ESP32 and RP2040 platforms.
 
 ### Added
 
@@ -41,7 +41,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added support for `crypto:one_time/4,5` on Unix and Pico as well as for `crypto:hash/2` on Pico
 - Added ability to configure STM32 Nucleo boards onboard UART->USB-COM using the `-DBOARD=nucleo` cmake option
 - Added STM32 cmake option `-DAVM_CFG_CONSOLE=` to select a different uart peripheral for the system console
-- Added `crypto:strong_rand_bytes/1` using Mbed-TLS (only on generic_unix and ESP32 platforms)
+- Added `crypto:strong_rand_bytes/1` using Mbed-TLS (only on generic_unix, ESP32 and RP2040
+  platforms)
 
 ### Removed
 

src/platforms/rp2040/src/lib/rp2040_sys.h

@@ -30,6 +30,9 @@
 #include <pico/cond.h>
 #include <pico/util/queue.h>
 
+#include <mbedtls/ctr_drbg.h>
+#include <mbedtls/entropy.h>
+
 #pragma GCC diagnostic pop
 
 #include "sys.h"
@@ -112,6 +115,18 @@ struct RP2040PlatformData
     cond_t event_poll_cond;
 #endif
     queue_t event_queue;
+
+#ifndef AVM_NO_SMP
+    Mutex *entropy_mutex;
+#endif
+    mbedtls_entropy_context entropy_ctx;
+    bool entropy_is_initialized;
+
+#ifndef AVM_NO_SMP
+    Mutex *random_mutex;
+#endif
+    mbedtls_ctr_drbg_context random_ctx;
+    bool random_is_initialized;
 };
 
 typedef void (*port_driver_init_t)(GlobalContext *global);

src/platforms/rp2040/src/lib/sys.c

@@ -44,6 +44,12 @@
 #include <otp_socket.h>
 #endif
 
+#if defined(MBEDTLS_VERSION_NUMBER) && (MBEDTLS_VERSION_NUMBER >= 0x03000000)
+#include <mbedtls/build_info.h>
+#else
+#include <mbedtls/config.h>
+#endif
+
 // libAtomVM
 #include <avmpack.h>
 #include <defaultatoms.h>
@@ -57,6 +63,14 @@
 // Platform uses listeners
 #include "listeners.h"
 
+#ifndef AVM_NO_SMP
+#define SMP_MUTEX_LOCK(mtx) smp_mutex_lock(mtx)
+#define SMP_MUTEX_UNLOCK(mtx) smp_mutex_unlock(mtx)
+#else
+#define SMP_MUTEX_LOCK(mtx)
+#define SMP_MUTEX_UNLOCK(mtx)
+#endif
+
 struct PortDriverDefListItem *port_driver_list;
 struct NifCollectionDefListItem *nif_collection_list;
 
@@ -75,6 +89,9 @@ void sys_init_platform(GlobalContext *glb)
     cyw43_arch_init();
     otp_socket_init(glb);
 #endif
+
+    platform->entropy_is_initialized = false;
+    platform->random_is_initialized = false;
 }
 
 void sys_free_platform(GlobalContext *glb)
@@ -85,6 +102,15 @@ void sys_free_platform(GlobalContext *glb)
 
     struct RP2040PlatformData *platform = glb->platform_data;
     queue_free(&platform->event_queue);
+
+    if (platform->random_is_initialized) {
+        mbedtls_ctr_drbg_free(&platform->random_ctx);
+    }
+
+    if (platform->entropy_is_initialized) {
+        mbedtls_entropy_free(&platform->entropy_ctx);
+    }
+
     free(platform);
 
 #ifndef AVM_NO_SMP
@@ -387,3 +413,70 @@ void sys_unregister_listener_from_event(GlobalContext *global, listener_event_t
     }
     synclist_unlock(&global->listeners);
 }
+
+int sys_mbedtls_entropy_func(void *entropy, unsigned char *buf, size_t size)
+{
+#ifndef MBEDTLS_THREADING_C
+    struct RP2040PlatformData *platform
+        = CONTAINER_OF(entropy, struct RP2040PlatformData, entropy_ctx);
+    SMP_MUTEX_LOCK(platform->entropy_mutex);
+    int result = mbedtls_entropy_func(entropy, buf, size);
+    SMP_MUTEX_UNLOCK(platform->entropy_mutex);
+
+    return result;
+#else
+    return mbedtls_entropy_func(entropy, buf, size);
+#endif
+}
+
+mbedtls_entropy_context *sys_mbedtls_get_entropy_context_lock(GlobalContext *global)
+{
+    struct RP2040PlatformData *platform = global->platform_data;
+
+    SMP_MUTEX_LOCK(platform->entropy_mutex);
+
+    if (!platform->entropy_is_initialized) {
+        mbedtls_entropy_init(&platform->entropy_ctx);
+        platform->entropy_is_initialized = true;
+    }
+
+    return &platform->entropy_ctx;
+}
+
+void sys_mbedtls_entropy_context_unlock(GlobalContext *global)
+{
+    struct RP2040PlatformData *platform = global->platform_data;
+    SMP_MUTEX_UNLOCK(platform->entropy_mutex);
+}
+
+mbedtls_ctr_drbg_context *sys_mbedtls_get_ctr_drbg_context_lock(GlobalContext *global)
+{
+    struct RP2040PlatformData *platform = global->platform_data;
+
+    SMP_MUTEX_LOCK(platform->random_mutex);
+
+    if (!platform->random_is_initialized) {
+        mbedtls_ctr_drbg_init(&platform->random_ctx);
+
+        mbedtls_entropy_context *entropy_ctx = sys_mbedtls_get_entropy_context_lock(global);
+        // Safe to unlock it now, sys_mbedtls_entropy_func will lock it again later
+        sys_mbedtls_entropy_context_unlock(global);
+
+        const char *seed = "AtomVM RP2040 Mbed-TLS initial seed.";
+        int seed_len = strlen(seed);
+        int seed_err = mbedtls_ctr_drbg_seed(&platform->random_ctx, sys_mbedtls_entropy_func,
+            entropy_ctx, (const unsigned char *) seed, seed_len);
+        if (UNLIKELY(seed_err != 0)) {
+            abort();
+        }
+        platform->random_is_initialized = true;
+    }
+
+    return &platform->random_ctx;
+}
+
+void sys_mbedtls_ctr_drbg_context_unlock(GlobalContext *global)
+{
+    struct RP2040PlatformData *platform = global->platform_data;
+    SMP_MUTEX_UNLOCK(platform->random_mutex);
+}