From c6deafc0d495b3e80cd42cf8de451960f6e2190d Mon Sep 17 00:00:00 2001
From: Hanno Becker <hanno.becker@arm.com>
Date: Sun, 23 Jul 2017 14:06:42 +0100
Subject: [PATCH] Omit RSA key generation test if no strong entropy is present

The RSA key generation test needs strong entropy to succeed. This commit captures the presence of a strong entropy
source in a preprocessor flag and only runs the key generation test if that flag is set.
---
 include/mbedtls/entropy.h            | 10 ++++++++++
 library/entropy.c                    |  3 +++
 tests/suites/test_suite_entropy.data |  8 ++++++--
 tests/suites/test_suite_rsa.function |  2 +-
 4 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/include/mbedtls/entropy.h b/include/mbedtls/entropy.h
index 747aca4df..b374b34ec 100644
--- a/include/mbedtls/entropy.h
+++ b/include/mbedtls/entropy.h
@@ -55,6 +55,16 @@
 #define MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE              -0x003D  /**< No strong sources have been added to poll. */
 #define MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR                 -0x003F  /**< Read/write error in file. */
 
+/* Indicates whether at least one standard strong entropy source is enabled. */
+#if defined(MBEDTLS_TEST_NULL_ENTROPY) ||             \
+    ( !defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES) && \
+      ( !defined(MBEDTLS_NO_PLATFORM_ENTROPY)  ||     \
+         defined(MBEDTLS_HAVEGE_C)             ||     \
+         defined(MBEDTLS_ENTROPY_HARDWARE_ALT) ||     \
+         defined(ENTROPY_NV_SEED) ) )
+#define MBEDTLS_ENTROPY_HAVE_STRONG
+#endif
+
 /**
  * \name SECTION: Module settings
  *
diff --git a/library/entropy.c b/library/entropy.c
index d4d1b27b7..4de168250 100644
--- a/library/entropy.c
+++ b/library/entropy.c
@@ -83,6 +83,9 @@ void mbedtls_entropy_init( mbedtls_entropy_context *ctx )
     mbedtls_havege_init( &ctx->havege_data );
 #endif
 
+    /* Reminder: Update MBEDTLS_ENTROPY_HAVE_STRONG when
+     *           adding more strong entropy sources here. */
+
 #if defined(MBEDTLS_TEST_NULL_ENTROPY)
     mbedtls_entropy_add_source( ctx, mbedtls_null_entropy_poll, NULL,
                                 1, MBEDTLS_ENTROPY_SOURCE_STRONG );
diff --git a/tests/suites/test_suite_entropy.data b/tests/suites/test_suite_entropy.data
index 5cff39984..bf9ce49ed 100644
--- a/tests/suites/test_suite_entropy.data
+++ b/tests/suites/test_suite_entropy.data
@@ -52,10 +52,14 @@ entropy_nv_seed:"000000000000000000000000000000000000000000000000000000000000000
 Check NV seed manually #3
 entropy_nv_seed:"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"
 
-Entropy self test
-depends_on:!MBEDTLS_TEST_NULL_ENTROPY
+Entropy self test (with strong entropy)
+depends_on:!MBEDTLS_TEST_NULL_ENTROPY:MBEDTLS_ENTROPY_HAVE_STRONG
 entropy_selftest:0
 
+Entropy self test (without strong entropy)
+depends_on:!MBEDTLS_TEST_NULL_ENTROPY:!MBEDTLS_ENTROPY_HAVE_STRONG
+entropy_selftest:1
+
 Entropy self test (MBEDTLS_TEST_NULL_ENTROPY)
 depends_on:MBEDTLS_TEST_NULL_ENTROPY
 entropy_selftest:1
diff --git a/tests/suites/test_suite_rsa.function b/tests/suites/test_suite_rsa.function
index e9ae1bf96..f64e1a73a 100644
--- a/tests/suites/test_suite_rsa.function
+++ b/tests/suites/test_suite_rsa.function
@@ -658,7 +658,7 @@ exit:
 }
 /* END_CASE */
 
-/* BEGIN_CASE depends_on:MBEDTLS_CTR_DRBG_C:MBEDTLS_ENTROPY_C */
+/* BEGIN_CASE depends_on:MBEDTLS_CTR_DRBG_C:MBEDTLS_ENTROPY_C:MBEDTLS_ENTROPY_HAVE_STRONG */
 void mbedtls_rsa_gen_key( int nrbits, int exponent, int result)
 {
     mbedtls_rsa_context ctx;