commit 1df83d4f5b0e6c701a13acd7b795aad3313f2a0e
author Gilles Peskine <Gilles.Peskine@arm.com> Tue Jul 23 16:13:14 2019 +0200
committer Gilles Peskine <Gilles.Peskine@arm.com> Tue Jul 23 16:13:14 2019 +0200
tree ba6dc91f9e2cd33a7133230bde3f136f9b7f2bfe
parent 0e8d495bd9b1f63717ee146070430d32e0f82c27

SE keys: implement persistent storage

For a key in a secure element, persist the key slot.

This is implemented in the nominal case. Failures may not be handled
properly.

library/psa_crypto.c

diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index e048e9f..84b6911 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1469,20 +1469,30 @@
     (void) driver;
 
 #if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
-    if( slot->lifetime == PSA_KEY_LIFETIME_PERSISTENT )
+    if( slot->lifetime != PSA_KEY_LIFETIME_VOLATILE )
     {
         uint8_t *buffer = NULL;
         size_t buffer_size = 0;
-        size_t length;
+        size_t length = 0;
 
-        buffer_size = PSA_KEY_EXPORT_MAX_SIZE( slot->type,
-                                               psa_get_key_slot_bits( slot ) );
-        buffer = mbedtls_calloc( 1, buffer_size );
-        if( buffer == NULL && buffer_size != 0 )
-            return( PSA_ERROR_INSUFFICIENT_MEMORY );
-        status = psa_internal_export_key( slot,
-                                          buffer, buffer_size, &length,
-                                          0 );
+#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
+        if( driver != NULL )
+        {
+            buffer = (uint8_t*) &slot->data.se.slot_number;
+            length = sizeof( slot->data.se.slot_number );
+        }
+        else
+#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
+        {
+            buffer_size = PSA_KEY_EXPORT_MAX_SIZE( slot->type,
+                                                   psa_get_key_slot_bits( slot ) );
+            buffer = mbedtls_calloc( 1, buffer_size );
+            if( buffer == NULL && buffer_size != 0 )
+                return( PSA_ERROR_INSUFFICIENT_MEMORY );
+            status = psa_internal_export_key( slot,
+                                              buffer, buffer_size, &length,
+                                              0 );
+        }
 
         if( status == PSA_SUCCESS )
         {
@@ -1491,9 +1501,14 @@
             status = psa_save_persistent_key( &attributes, buffer, length );
         }
 
-        if( buffer_size != 0 )
-            mbedtls_platform_zeroize( buffer, buffer_size );
-        mbedtls_free( buffer );
+#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
+        if( driver == NULL )
+#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
+        {
+            if( buffer_size != 0 )
+                mbedtls_platform_zeroize( buffer, buffer_size );
+            mbedtls_free( buffer );
+        }
     }
 #endif /* defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */
 

library/psa_crypto_slot_management.c

diff --git a/library/psa_crypto_slot_management.c b/library/psa_crypto_slot_management.c
index 5326fbd..6b87ea0 100644
--- a/library/psa_crypto_slot_management.c
+++ b/library/psa_crypto_slot_management.c
@@ -131,10 +131,28 @@
                                       &key_data, &key_data_length );
     if( status != PSA_SUCCESS )
         goto exit;
+    p_slot->lifetime = psa_get_key_lifetime( &attributes );
     p_slot->type = psa_get_key_type( &attributes );
     p_slot->policy = attributes.policy;
-    status = psa_import_key_into_slot( p_slot,
-                                       key_data, key_data_length );
+
+#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
+    if( psa_key_lifetime_is_external( p_slot->lifetime ) )
+    {
+        if( key_data_length != sizeof( p_slot->data.se.slot_number ) )
+        {
+            status = PSA_ERROR_STORAGE_FAILURE;
+            goto exit;
+        }
+        memcpy( &p_slot->data.se.slot_number, key_data,
+                sizeof( p_slot->data.se.slot_number ) );
+    }
+    else
+#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
+    {
+        status = psa_import_key_into_slot( p_slot,
+                                           key_data, key_data_length );
+    }
+
 exit:
     psa_free_persistent_key_data( key_data, key_data_length );
     return( status );