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Catch failures of AES or DES operations

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Declare all AES and DES functions that return int as needing to have
their result checked, and do check the result in our code.

A DES or AES block operation can fail in alternative implementations of
mbedtls_internal_aes_encrypt() (under MBEDTLS_AES_ENCRYPT_ALT),
mbedtls_internal_aes_decrypt() (under MBEDTLS_AES_DECRYPT_ALT),
mbedtls_des_crypt_ecb() (under MBEDTLS_DES_CRYPT_ECB_ALT),
mbedtls_des3_crypt_ecb() (under MBEDTLS_DES3_CRYPT_ECB_ALT).
A failure can happen if the accelerator peripheral is in a bad state.
Several block modes were not catching the error.

This commit does the following code changes, grouped together to avoid
having an intermediate commit where the build fails:

* Add MBEDTLS_CHECK_RETURN to all functions returning int in aes.h and des.h.
* Fix all places where this causes a GCC warning, indicating that our code
  was not properly checking the result of an AES operation:
    * In library code: on failure, goto exit and return ret.
    * In pkey programs: goto exit.
    * In the benchmark program: exit (not ideal since there's no error
      message, but it's what the code currently does for failures).
    * In test code: TEST_ASSERT.
* Changelog entry.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine
2021-07-07 21:08:28 +02:00
parent 4b627af36c
commit 7820a574f1
10 changed files with 164 additions and 60 deletions
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8
programs/pkey/dh_client.c
View File

@ -270,7 +270,9 @@ int main( void )
mbedtls_printf( "...\n . Receiving and decrypting the ciphertext" );
fflush( stdout );
mbedtls_aes_setkey_dec( &aes, buf, 256 );
ret = mbedtls_aes_setkey_dec( &aes, buf, 256 );
if( ret != 0 )
goto exit;
memset( buf, 0, sizeof( buf ) );
@ -280,7 +282,9 @@ int main( void )
goto exit;
}
mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_DECRYPT, buf, buf );
ret = mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_DECRYPT, buf, buf );
if( ret != 0 )
goto exit;
buf[16] = '\0';
mbedtls_printf( "\n . Plaintext is \"%s\"\n\n", (char *) buf );

8
programs/pkey/dh_server.c
View File

@ -290,9 +290,13 @@ int main( void )
mbedtls_printf( "...\n . Encrypting and sending the ciphertext" );
fflush( stdout );
mbedtls_aes_setkey_enc( &aes, buf, 256 );
ret = mbedtls_aes_setkey_enc( &aes, buf, 256 );
if( ret != 0 )
goto exit;
memcpy( buf, PLAINTEXT, 16 );
mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_ENCRYPT, buf, buf );
ret = mbedtls_aes_crypt_ecb( &aes, MBEDTLS_AES_ENCRYPT, buf, buf );
if( ret != 0 )
goto exit;
if( ( ret = mbedtls_net_send( &client_fd, buf, 16 ) ) != 16 )
{

10
programs/test/benchmark.c
View File

@ -674,7 +674,8 @@ int main( int argc, char *argv[] )
{
mbedtls_des3_context des3;
mbedtls_des3_init( &des3 );
mbedtls_des3_set3key_enc( &des3, tmp );
if( mbedtls_des3_set3key_enc( &des3, tmp ) != 0 )
mbedtls_exit( 1 );
TIME_AND_TSC( "3DES",
mbedtls_des3_crypt_cbc( &des3, MBEDTLS_DES_ENCRYPT, BUFSIZE, tmp, buf, buf ) );
mbedtls_des3_free( &des3 );
@ -684,7 +685,8 @@ int main( int argc, char *argv[] )
{
mbedtls_des_context des;
mbedtls_des_init( &des );
mbedtls_des_setkey_enc( &des, tmp );
if( mbedtls_des_setkey_enc( &des, tmp ) != 0 )
mbedtls_exit( 1 );
TIME_AND_TSC( "DES",
mbedtls_des_crypt_cbc( &des, MBEDTLS_DES_ENCRYPT, BUFSIZE, tmp, buf, buf ) );
mbedtls_des_free( &des );
@ -722,7 +724,7 @@ int main( int argc, char *argv[] )
memset( buf, 0, sizeof( buf ) );
memset( tmp, 0, sizeof( tmp ) );
mbedtls_aes_setkey_enc( &aes, tmp, keysize );
CHECK_AND_CONTINUE( mbedtls_aes_setkey_enc( &aes, tmp, keysize ) );
TIME_AND_TSC( title,
mbedtls_aes_crypt_cbc( &aes, MBEDTLS_AES_ENCRYPT, BUFSIZE, tmp, buf, buf ) );
@ -743,7 +745,7 @@ int main( int argc, char *argv[] )
memset( buf, 0, sizeof( buf ) );
memset( tmp, 0, sizeof( tmp ) );
mbedtls_aes_xts_setkey_enc( &ctx, tmp, keysize * 2 );
CHECK_AND_CONTINUE( mbedtls_aes_xts_setkey_enc( &ctx, tmp, keysize * 2 ) );
TIME_AND_TSC( title,
mbedtls_aes_crypt_xts( &ctx, MBEDTLS_AES_ENCRYPT, BUFSIZE,