Merge pull request #293 from gilles-peskine-arm/entropy-min
Always gather MBEDTLS_ENTROPY_BLOCK_SIZE bytes of entropy
diff --git a/library/entropy.c b/library/entropy.c
index d7091cb..a40ce80 100644
--- a/library/entropy.c
+++ b/library/entropy.c
@@ -327,7 +327,8 @@
int mbedtls_entropy_func( void *data, unsigned char *output, size_t len )
{
- int ret, count = 0, i, done;
+ int ret, count = 0, i, thresholds_reached;
+ size_t strong_size;
mbedtls_entropy_context *ctx = (mbedtls_entropy_context *) data;
unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
@@ -365,12 +366,17 @@
if( ( ret = entropy_gather_internal( ctx ) ) != 0 )
goto exit;
- done = 1;
+ thresholds_reached = 1;
+ strong_size = 0;
for( i = 0; i < ctx->source_count; i++ )
+ {
if( ctx->source[i].size < ctx->source[i].threshold )
- done = 0;
+ thresholds_reached = 0;
+ if( ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG )
+ strong_size += ctx->source[i].size;
+ }
}
- while( ! done );
+ while( ! thresholds_reached || strong_size < MBEDTLS_ENTROPY_BLOCK_SIZE );
memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
diff --git a/tests/suites/test_suite_entropy.data b/tests/suites/test_suite_entropy.data
index 11ced64..b2d20b4 100644
--- a/tests/suites/test_suite_entropy.data
+++ b/tests/suites/test_suite_entropy.data
@@ -1,45 +1,66 @@
Create NV seed_file
nv_seed_file_create:
-Entropy write/update seed file [#1]
+Entropy write/update seed file: good
entropy_seed_file:"data_files/entropy_seed":0
-Entropy write/update seed file [#2]
+Entropy write/update seed file: nonexistent
entropy_seed_file:"no_such_dir/file":MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR
+Entropy no sources
+entropy_no_sources:
+
Entropy too many sources
entropy_too_many_sources:
-Entropy output length #1
+Entropy output length: 0
entropy_func_len:0:0
-Entropy output length #2
+Entropy output length: 1
entropy_func_len:1:0
-Entropy output length #3
+Entropy output length: 2
entropy_func_len:2:0
-Entropy output length #4
+Entropy output length: 31
entropy_func_len:31:0
-Entropy output length #5
+Entropy output length: 65 > BLOCK_SIZE
entropy_func_len:65:MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
Entropy failing source
entropy_source_fail:"data_files/entropy_seed"
-Entropy threshold #1
+Entropy threshold: 16=2*8
entropy_threshold:16:2:8
-Entropy threshold #2
+Entropy threshold: 32=1*32
entropy_threshold:32:1:32
-Entropy threshold #3
+Entropy threshold: 0* never reaches the threshold
entropy_threshold:16:0:MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
-Entropy threshold #4
+Entropy threshold: 1024 never reached
entropy_threshold:1024:1:MBEDTLS_ERR_ENTROPY_SOURCE_FAILED
+Entropy calls: no strong
+entropy_calls:MBEDTLS_ENTROPY_SOURCE_WEAK:MBEDTLS_ENTROPY_SOURCE_WEAK:1:MBEDTLS_ENTROPY_BLOCK_SIZE:MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE
+
+Entropy calls: 1 strong, 1*BLOCK_SIZE
+entropy_calls:MBEDTLS_ENTROPY_SOURCE_STRONG:MBEDTLS_ENTROPY_SOURCE_WEAK:1:MBEDTLS_ENTROPY_BLOCK_SIZE:1
+
+Entropy calls: 1 strong, 2*(BLOCK_SIZE/2)
+entropy_calls:MBEDTLS_ENTROPY_SOURCE_STRONG:MBEDTLS_ENTROPY_SOURCE_WEAK:1:(MBEDTLS_ENTROPY_BLOCK_SIZE+1)/2:2
+
+Entropy calls: 1 strong, BLOCK_SIZE*1
+entropy_calls:MBEDTLS_ENTROPY_SOURCE_STRONG:MBEDTLS_ENTROPY_SOURCE_WEAK:1:1:MBEDTLS_ENTROPY_BLOCK_SIZE
+
+Entropy calls: 1 strong, 2*BLOCK_SIZE to reach threshold
+entropy_calls:MBEDTLS_ENTROPY_SOURCE_STRONG:MBEDTLS_ENTROPY_SOURCE_WEAK:MBEDTLS_ENTROPY_BLOCK_SIZE+1:MBEDTLS_ENTROPY_BLOCK_SIZE:2
+
+Entropy calls: 2 strong, BLOCK_SIZE/2 each
+entropy_calls:MBEDTLS_ENTROPY_SOURCE_STRONG:MBEDTLS_ENTROPY_SOURCE_WEAK:(MBEDTLS_ENTROPY_BLOCK_SIZE+1)/2:(MBEDTLS_ENTROPY_BLOCK_SIZE+1)/2:2
+
Check NV seed standard IO
entropy_nv_seed_std_io:
diff --git a/tests/suites/test_suite_entropy.function b/tests/suites/test_suite_entropy.function
index 0d86ead..9f10a90 100644
--- a/tests/suites/test_suite_entropy.function
+++ b/tests/suites/test_suite_entropy.function
@@ -3,10 +3,19 @@
#include "mbedtls/entropy_poll.h"
#include "string.h"
-/*
- * Number of calls made to entropy_dummy_source()
- */
-static size_t entropy_dummy_calls;
+typedef enum
+{
+ DUMMY_CONSTANT_LENGTH, /* Output context->length bytes */
+ DUMMY_REQUESTED_LENGTH, /* Output whatever length was requested */
+ DUMMY_FAIL, /* Return an error code */
+} entropy_dummy_instruction;
+
+typedef struct
+{
+ entropy_dummy_instruction instruction;
+ size_t length; /* Length to return for DUMMY_CONSTANT_LENGTH */
+ size_t calls; /* Incremented at each call */
+} entropy_dummy_context;
/*
* Dummy entropy source
@@ -14,29 +23,28 @@
* If data is NULL, write exactly the requested length.
* Otherwise, write the length indicated by data or error if negative
*/
-static int entropy_dummy_source( void *data, unsigned char *output,
+static int entropy_dummy_source( void *arg, unsigned char *output,
size_t len, size_t *olen )
{
- entropy_dummy_calls++;
+ entropy_dummy_context *context = arg;
+ ++context->calls;
- if( data == NULL )
- *olen = len;
- else
+ switch( context->instruction )
{
- int *d = (int *) data;
-
- if( *d < 0 )
+ case DUMMY_CONSTANT_LENGTH:
+ *olen = context->length;
+ break;
+ case DUMMY_REQUESTED_LENGTH:
+ *olen = len;
+ break;
+ case DUMMY_FAIL:
return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
- else
- *olen = *d;
}
memset( output, 0x2a, *olen );
-
return( 0 );
}
-#if defined(MBEDTLS_ENTROPY_NV_SEED)
/*
* Ability to clear entropy sources to allow testing with just predefined
* entropy sources. This function or tests depending on it might break if there
@@ -48,11 +56,12 @@
* This might break memory checks in the future if sources need 'free-ing' then
* as well.
*/
-void entropy_clear_sources( mbedtls_entropy_context *ctx )
+static void entropy_clear_sources( mbedtls_entropy_context *ctx )
{
ctx->source_count = 0;
}
+#if defined(MBEDTLS_ENTROPY_NV_SEED)
/*
* NV seed read/write functions that use a buffer instead of a file
*/
@@ -140,10 +149,27 @@
/* END_CASE */
/* BEGIN_CASE */
+void entropy_no_sources( )
+{
+ mbedtls_entropy_context ctx;
+ unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
+
+ mbedtls_entropy_init( &ctx );
+ entropy_clear_sources( &ctx );
+ TEST_EQUAL( mbedtls_entropy_func( &ctx, buf, sizeof( buf ) ),
+ MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED );
+
+exit:
+ mbedtls_entropy_free( &ctx );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
void entropy_too_many_sources( )
{
mbedtls_entropy_context ctx;
size_t i;
+ entropy_dummy_context dummy = {DUMMY_REQUESTED_LENGTH, 0, 0};
mbedtls_entropy_init( &ctx );
@@ -152,10 +178,10 @@
* since we don't know how many sources were automatically added.
*/
for( i = 0; i < MBEDTLS_ENTROPY_MAX_SOURCES; i++ )
- (void) mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL,
+ (void) mbedtls_entropy_add_source( &ctx, entropy_dummy_source, &dummy,
16, MBEDTLS_ENTROPY_SOURCE_WEAK );
- TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source, NULL,
+ TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source, &dummy,
16, MBEDTLS_ENTROPY_SOURCE_WEAK )
== MBEDTLS_ERR_ENTROPY_MAX_SOURCES );
@@ -197,13 +223,13 @@
void entropy_source_fail( char * path )
{
mbedtls_entropy_context ctx;
- int fail = -1;
unsigned char buf[16];
+ entropy_dummy_context dummy = {DUMMY_FAIL, 0, 0};
mbedtls_entropy_init( &ctx );
TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
- &fail, 16,
+ &dummy, 16,
MBEDTLS_ENTROPY_SOURCE_WEAK )
== 0 );
@@ -225,30 +251,87 @@
}
/* END_CASE */
-/* BEGIN_CASE depends_on:ENTROPY_HAVE_STRONG */
+/* BEGIN_CASE */
void entropy_threshold( int threshold, int chunk_size, int result )
{
mbedtls_entropy_context ctx;
+ entropy_dummy_context strong =
+ {DUMMY_CONSTANT_LENGTH, MBEDTLS_ENTROPY_BLOCK_SIZE, 0};
+ entropy_dummy_context weak = {DUMMY_CONSTANT_LENGTH, chunk_size, 0};
unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
int ret;
mbedtls_entropy_init( &ctx );
+ entropy_clear_sources( &ctx );
+ /* Set strong source that reaches its threshold immediately and
+ * a weak source whose threshold is a test parameter. */
TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
- &chunk_size, threshold,
+ &strong, 1,
+ MBEDTLS_ENTROPY_SOURCE_STRONG ) == 0 );
+ TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
+ &weak, threshold,
MBEDTLS_ENTROPY_SOURCE_WEAK ) == 0 );
- entropy_dummy_calls = 0;
ret = mbedtls_entropy_func( &ctx, buf, sizeof( buf ) );
if( result >= 0 )
{
TEST_ASSERT( ret == 0 );
#if defined(MBEDTLS_ENTROPY_NV_SEED)
- // Two times as much calls due to the NV seed update
+ /* If the NV seed functionality is enabled, there are two entropy
+ * updates: before and after updating the NV seed. */
result *= 2;
#endif
- TEST_ASSERT( entropy_dummy_calls == (size_t) result );
+ TEST_ASSERT( weak.calls == (size_t) result );
+ }
+ else
+ {
+ TEST_ASSERT( ret == result );
+ }
+
+exit:
+ mbedtls_entropy_free( &ctx );
+}
+/* END_CASE */
+
+/* BEGIN_CASE */
+void entropy_calls( int strength1, int strength2,
+ int threshold, int chunk_size,
+ int result )
+{
+ /*
+ * if result >= 0: result = expected number of calls to source 1
+ * if result < 0: result = expected return code from mbedtls_entropy_func()
+ */
+
+ mbedtls_entropy_context ctx;
+ entropy_dummy_context dummy1 = {DUMMY_CONSTANT_LENGTH, chunk_size, 0};
+ entropy_dummy_context dummy2 = {DUMMY_CONSTANT_LENGTH, chunk_size, 0};
+ unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE] = { 0 };
+ int ret;
+
+ mbedtls_entropy_init( &ctx );
+ entropy_clear_sources( &ctx );
+
+ TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
+ &dummy1, threshold,
+ strength1 ) == 0 );
+ TEST_ASSERT( mbedtls_entropy_add_source( &ctx, entropy_dummy_source,
+ &dummy2, threshold,
+ strength2 ) == 0 );
+
+ ret = mbedtls_entropy_func( &ctx, buf, sizeof( buf ) );
+
+ if( result >= 0 )
+ {
+ TEST_ASSERT( ret == 0 );
+#if defined(MBEDTLS_ENTROPY_NV_SEED)
+ /* If the NV seed functionality is enabled, there are two entropy
+ * updates: before and after updating the NV seed. */
+ result *= 2;
+#endif
+ TEST_ASSERT( dummy1.calls == (size_t) result );
}
else
{