From 2d20567122e4c1e7295ac7aba77df33d46d04993 Mon Sep 17 00:00:00 2001
From: Janos Follath <janos.follath@arm.com>
Date: Tue, 3 Dec 2019 15:55:56 +0000
Subject: [PATCH] Add two error codes to the Error module

One of the error codes was already reserved, this commit just makes it
explicit. The other one is a new error code for initializing return
values in the library: `MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED` should
not be returned by the library. If it is returned, then it is surely a
bug in the library or somebody is tampering with the device.
---
 include/mbedtls/error.h    |  6 +++++-
 library/error.c            | 11 +++++++++++
 scripts/generate_errors.pl |  2 +-
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/include/mbedtls/error.h b/include/mbedtls/error.h
index 3fff9a054..82b018813 100644
--- a/include/mbedtls/error.h
+++ b/include/mbedtls/error.h
@@ -52,9 +52,10 @@
  * For historical reasons, low-level error codes are divided in even and odd,
  * even codes were assigned first, and -1 is reserved for other errors.
  *
- * Low-level module errors (0x0002-0x007E, 0x0003-0x007F)
+ * Low-level module errors (0x0002-0x007E, 0x0001-0x007F)
  *
  * Module   Nr  Codes assigned
+ * ERROR     2  0x006E          0x0001
  * MPI       7  0x0002-0x0010
  * GCM       3  0x0012-0x0014   0x0013-0x0013
  * BLOWFISH  3  0x0016-0x0018   0x0017-0x0017
@@ -112,6 +113,9 @@
 extern "C" {
 #endif
 
+#define MBEDTLS_ERR_ERROR_GENERIC_ERROR       -0x0001  /**< Generic error */
+#define MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED -0x006E  /**< This is a bug in the library */
+
 /**
  * \brief Translate a mbed TLS error code into a string representation,
  *        Result is truncated if necessary and always includes a terminating
diff --git a/library/error.c b/library/error.c
index d8b578048..53b3a26b5 100644
--- a/library/error.c
+++ b/library/error.c
@@ -109,6 +109,10 @@
 #include "mbedtls/entropy.h"
 #endif
 
+#if defined(MBEDTLS_ERROR_C)
+#include "mbedtls/error.h"
+#endif
+
 #if defined(MBEDTLS_GCM_C)
 #include "mbedtls/gcm.h"
 #endif
@@ -754,6 +758,13 @@ void mbedtls_strerror( int ret, char *buf, size_t buflen )
         mbedtls_snprintf( buf, buflen, "ENTROPY - Read/write error in file" );
 #endif /* MBEDTLS_ENTROPY_C */
 
+#if defined(MBEDTLS_ERROR_C)
+    if( use_ret == -(MBEDTLS_ERR_ERROR_GENERIC_ERROR) )
+        mbedtls_snprintf( buf, buflen, "ERROR - Generic error" );
+    if( use_ret == -(MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED) )
+        mbedtls_snprintf( buf, buflen, "ERROR - This is a bug in the library" );
+#endif /* MBEDTLS_ERROR_C */
+
 #if defined(MBEDTLS_GCM_C)
     if( use_ret == -(MBEDTLS_ERR_GCM_AUTH_FAILED) )
         mbedtls_snprintf( buf, buflen, "GCM - Authenticated decryption failed" );
diff --git a/scripts/generate_errors.pl b/scripts/generate_errors.pl
index 2fe202e8d..7b66ecacb 100755
--- a/scripts/generate_errors.pl
+++ b/scripts/generate_errors.pl
@@ -38,7 +38,7 @@ my $error_format_file = $data_dir.'/error.fmt';
 
 my @low_level_modules = qw( AES ARC4 ARIA ASN1 BASE64 BIGNUM BLOWFISH
                             CAMELLIA CCM CHACHA20 CHACHAPOLY CMAC CTR_DRBG DES
-                            ENTROPY GCM HKDF HMAC_DRBG MD2 MD4 MD5
+                            ENTROPY ERROR GCM HKDF HMAC_DRBG MD2 MD4 MD5
                             NET OID PADLOCK PBKDF2 PLATFORM POLY1305 RIPEMD160
                             SHA1 SHA256 SHA512 THREADING XTEA );
 my @high_level_modules = qw( CIPHER DHM ECP MD