Import mbedtls-2.16.0

Imports mbedTLS 2.16.0 from https://github.com/ARMmbed/mbedtls.git
commit fb1972db23da ("Merge pull request #544 from ARMmbed/version-2.16")
(tag mbedtls-2.16.0).

Certain files will never be needed and are thus removed (reducing number
of lines to almost 50%):
rm -f circle.yml CMakeLists.txt DartConfiguration.tcl Makefile
rm -f .gitignore .travis.yml .pylint
rm -f include/.gitignore include/CMakeLists.txt library/.gitignore
rm -f library/CMakeLists.txt library/Makefile
rm -rf .git .github doxygen configs programs scripts tests visualc yotta

This is a complete overwrite of previous code so earlier changes in the
branch import/mbedtls-2.6.1 will be added on top of this commit to bring
the changes forward.

Acked-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/lib/libmbedtls/mbedtls/library/entropy.c b/lib/libmbedtls/mbedtls/library/entropy.c
index a4f42dc..f8db1a5 100644
--- a/lib/libmbedtls/mbedtls/library/entropy.c
+++ b/lib/libmbedtls/mbedtls/library/entropy.c
@@ -1,8 +1,8 @@
-// SPDX-License-Identifier: Apache-2.0
 /*
  *  Entropy accumulator implementation
  *
  *  Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
  *
  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
  *  not use this file except in compliance with the License.
@@ -35,6 +35,7 @@
 
 #include "mbedtls/entropy.h"
 #include "mbedtls/entropy_poll.h"
+#include "mbedtls/platform_util.h"
 
 #include <string.h>
 
@@ -59,30 +60,30 @@
 #include "mbedtls/havege.h"
 #endif
 
-/* Implementation that should never be optimized out by the compiler */
-static void mbedtls_zeroize( void *v, size_t n ) {
-    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
-}
-
 #define ENTROPY_MAX_LOOP    256     /**< Maximum amount to loop before error */
 
 void mbedtls_entropy_init( mbedtls_entropy_context *ctx )
 {
-    memset( ctx, 0, sizeof(mbedtls_entropy_context) );
+    ctx->source_count = 0;
+    memset( ctx->source, 0, sizeof( ctx->source ) );
 
 #if defined(MBEDTLS_THREADING_C)
     mbedtls_mutex_init( &ctx->mutex );
 #endif
 
+    ctx->accumulator_started = 0;
 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
-    mbedtls_sha512_starts( &ctx->accumulator, 0 );
+    mbedtls_sha512_init( &ctx->accumulator );
 #else
-    mbedtls_sha256_starts( &ctx->accumulator, 0 );
+    mbedtls_sha256_init( &ctx->accumulator );
 #endif
 #if defined(MBEDTLS_HAVEGE_C)
     mbedtls_havege_init( &ctx->havege_data );
 #endif
 
+    /* Reminder: Update ENTROPY_HAVE_STRONG in the test files
+     *           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 );
@@ -113,6 +114,7 @@
     mbedtls_entropy_add_source( ctx, mbedtls_nv_seed_poll, NULL,
                                 MBEDTLS_ENTROPY_BLOCK_SIZE,
                                 MBEDTLS_ENTROPY_SOURCE_STRONG );
+    ctx->initial_entropy_run = 0;
 #endif
 #endif /* MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES */
 }
@@ -125,7 +127,17 @@
 #if defined(MBEDTLS_THREADING_C)
     mbedtls_mutex_free( &ctx->mutex );
 #endif
-    mbedtls_zeroize( ctx, sizeof( mbedtls_entropy_context ) );
+#if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
+    mbedtls_sha512_free( &ctx->accumulator );
+#else
+    mbedtls_sha256_free( &ctx->accumulator );
+#endif
+#if defined(MBEDTLS_ENTROPY_NV_SEED)
+    ctx->initial_entropy_run = 0;
+#endif
+    ctx->source_count = 0;
+    mbedtls_platform_zeroize( ctx->source, sizeof( ctx->source ) );
+    ctx->accumulator_started = 0;
 }
 
 int mbedtls_entropy_add_source( mbedtls_entropy_context *ctx,
@@ -172,13 +184,16 @@
     unsigned char tmp[MBEDTLS_ENTROPY_BLOCK_SIZE];
     size_t use_len = len;
     const unsigned char *p = data;
+    int ret = 0;
 
     if( use_len > MBEDTLS_ENTROPY_BLOCK_SIZE )
     {
 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
-        mbedtls_sha512( data, len, tmp, 0 );
+        if( ( ret = mbedtls_sha512_ret( data, len, tmp, 0 ) ) != 0 )
+            goto cleanup;
 #else
-        mbedtls_sha256( data, len, tmp, 0 );
+        if( ( ret = mbedtls_sha256_ret( data, len, tmp, 0 ) ) != 0 )
+            goto cleanup;
 #endif
         p = tmp;
         use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
@@ -187,15 +202,35 @@
     header[0] = source_id;
     header[1] = use_len & 0xFF;
 
+    /*
+     * Start the accumulator if this has not already happened. Note that
+     * it is sufficient to start the accumulator here only because all calls to
+     * gather entropy eventually execute this code.
+     */
 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
-    mbedtls_sha512_update( &ctx->accumulator, header, 2 );
-    mbedtls_sha512_update( &ctx->accumulator, p, use_len );
+    if( ctx->accumulator_started == 0 &&
+        ( ret = mbedtls_sha512_starts_ret( &ctx->accumulator, 0 ) ) != 0 )
+        goto cleanup;
+    else
+        ctx->accumulator_started = 1;
+    if( ( ret = mbedtls_sha512_update_ret( &ctx->accumulator, header, 2 ) ) != 0 )
+        goto cleanup;
+    ret = mbedtls_sha512_update_ret( &ctx->accumulator, p, use_len );
 #else
-    mbedtls_sha256_update( &ctx->accumulator, header, 2 );
-    mbedtls_sha256_update( &ctx->accumulator, p, use_len );
+    if( ctx->accumulator_started == 0 &&
+        ( ret = mbedtls_sha256_starts_ret( &ctx->accumulator, 0 ) ) != 0 )
+        goto cleanup;
+    else
+        ctx->accumulator_started = 1;
+    if( ( ret = mbedtls_sha256_update_ret( &ctx->accumulator, header, 2 ) ) != 0 )
+        goto cleanup;
+    ret = mbedtls_sha256_update_ret( &ctx->accumulator, p, use_len );
 #endif
 
-    return( 0 );
+cleanup:
+    mbedtls_platform_zeroize( tmp, sizeof( tmp ) );
+
+    return( ret );
 }
 
 int mbedtls_entropy_update_manual( mbedtls_entropy_context *ctx,
@@ -242,7 +277,7 @@
         if( ( ret = ctx->source[i].f_source( ctx->source[i].p_source,
                         buf, MBEDTLS_ENTROPY_MAX_GATHER, &olen ) ) != 0 )
         {
-            return( ret );
+            goto cleanup;
         }
 
         /*
@@ -250,15 +285,20 @@
          */
         if( olen > 0 )
         {
-            entropy_update( ctx, (unsigned char) i, buf, olen );
+            if( ( ret = entropy_update( ctx, (unsigned char) i,
+                                        buf, olen ) ) != 0 )
+                return( ret );
             ctx->source[i].size += olen;
         }
     }
 
     if( have_one_strong == 0 )
-        return( MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE );
+        ret = MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE;
 
-    return( 0 );
+cleanup:
+    mbedtls_platform_zeroize( buf, sizeof( buf ) );
+
+    return( ret );
 }
 
 /*
@@ -333,33 +373,52 @@
     memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
 
 #if defined(MBEDTLS_ENTROPY_SHA512_ACCUMULATOR)
-    mbedtls_sha512_finish( &ctx->accumulator, buf );
+    /*
+     * Note that at this stage it is assumed that the accumulator was started
+     * in a previous call to entropy_update(). If this is not guaranteed, the
+     * code below will fail.
+     */
+    if( ( ret = mbedtls_sha512_finish_ret( &ctx->accumulator, buf ) ) != 0 )
+        goto exit;
 
     /*
      * Reset accumulator and counters and recycle existing entropy
      */
-    memset( &ctx->accumulator, 0, sizeof( mbedtls_sha512_context ) );
-    mbedtls_sha512_starts( &ctx->accumulator, 0 );
-    mbedtls_sha512_update( &ctx->accumulator, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
+    mbedtls_sha512_free( &ctx->accumulator );
+    mbedtls_sha512_init( &ctx->accumulator );
+    if( ( ret = mbedtls_sha512_starts_ret( &ctx->accumulator, 0 ) ) != 0 )
+        goto exit;
+    if( ( ret = mbedtls_sha512_update_ret( &ctx->accumulator, buf,
+                                           MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )
+        goto exit;
 
     /*
      * Perform second SHA-512 on entropy
      */
-    mbedtls_sha512( buf, MBEDTLS_ENTROPY_BLOCK_SIZE, buf, 0 );
+    if( ( ret = mbedtls_sha512_ret( buf, MBEDTLS_ENTROPY_BLOCK_SIZE,
+                                    buf, 0 ) ) != 0 )
+        goto exit;
 #else /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */
-    mbedtls_sha256_finish( &ctx->accumulator, buf );
+    if( ( ret = mbedtls_sha256_finish_ret( &ctx->accumulator, buf ) ) != 0 )
+        goto exit;
 
     /*
      * Reset accumulator and counters and recycle existing entropy
      */
-    memset( &ctx->accumulator, 0, sizeof( mbedtls_sha256_context ) );
-    mbedtls_sha256_starts( &ctx->accumulator, 0 );
-    mbedtls_sha256_update( &ctx->accumulator, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
+    mbedtls_sha256_free( &ctx->accumulator );
+    mbedtls_sha256_init( &ctx->accumulator );
+    if( ( ret = mbedtls_sha256_starts_ret( &ctx->accumulator, 0 ) ) != 0 )
+        goto exit;
+    if( ( ret = mbedtls_sha256_update_ret( &ctx->accumulator, buf,
+                                           MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )
+        goto exit;
 
     /*
      * Perform second SHA-256 on entropy
      */
-    mbedtls_sha256( buf, MBEDTLS_ENTROPY_BLOCK_SIZE, buf, 0 );
+    if( ( ret = mbedtls_sha256_ret( buf, MBEDTLS_ENTROPY_BLOCK_SIZE,
+                                    buf, 0 ) ) != 0 )
+        goto exit;
 #endif /* MBEDTLS_ENTROPY_SHA512_ACCUMULATOR */
 
     for( i = 0; i < ctx->source_count; i++ )
@@ -370,6 +429,8 @@
     ret = 0;
 
 exit:
+    mbedtls_platform_zeroize( buf, sizeof( buf ) );
+
 #if defined(MBEDTLS_THREADING_C)
     if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
         return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
@@ -382,7 +443,7 @@
 int mbedtls_entropy_update_nv_seed( mbedtls_entropy_context *ctx )
 {
     int ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
-    unsigned char buf[ MBEDTLS_ENTROPY_MAX_SEED_SIZE ];
+    unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
 
     /* Read new seed  and write it to NV */
     if( ( ret = mbedtls_entropy_func( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) ) != 0 )
@@ -393,9 +454,9 @@
 
     /* Manually update the remaining stream with a separator value to diverge */
     memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
-    mbedtls_entropy_update_manual( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
+    ret = mbedtls_entropy_update_manual( ctx, buf, MBEDTLS_ENTROPY_BLOCK_SIZE );
 
-    return( 0 );
+    return( ret );
 }
 #endif /* MBEDTLS_ENTROPY_NV_SEED */
 
@@ -421,12 +482,15 @@
     ret = 0;
 
 exit:
+    mbedtls_platform_zeroize( buf, sizeof( buf ) );
+
     fclose( f );
     return( ret );
 }
 
 int mbedtls_entropy_update_seed_file( mbedtls_entropy_context *ctx, const char *path )
 {
+    int ret = 0;
     FILE *f;
     size_t n;
     unsigned char buf[ MBEDTLS_ENTROPY_MAX_SEED_SIZE ];
@@ -442,14 +506,16 @@
         n = MBEDTLS_ENTROPY_MAX_SEED_SIZE;
 
     if( fread( buf, 1, n, f ) != n )
-    {
-        fclose( f );
-        return( MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR );
-    }
+        ret = MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR;
+    else
+        ret = mbedtls_entropy_update_manual( ctx, buf, n );
 
     fclose( f );
 
-    mbedtls_entropy_update_manual( ctx, buf, n );
+    mbedtls_platform_zeroize( buf, sizeof( buf ) );
+
+    if( ret != 0 )
+        return( ret );
 
     return( mbedtls_entropy_write_seed_file( ctx, path ) );
 }