Disable debug messages that can introduce a timing side channel.

Introduced the POLARSSL_SSL_DEBUG_ALL flag to enable all these debug
messages in case somebody does want to see the reason checks fail.
This commit is contained in:
Paul Bakker 2013-01-31 16:57:45 +01:00
parent 4582999be6
commit d66f070d49
3 changed files with 24 additions and 1 deletions

View File

@ -3,6 +3,8 @@ PolarSSL ChangeLog
= Development
Changes
* Allow enabling of dummy error_strerror() to support some use-cases
* Debug messages about padding errors during SSL message decryption are
disabled by default and can be enabled with POLARSSL_SSL_DEBUG_ALL
Security
* Removed timing differences during SSL message decryption in

View File

@ -238,6 +238,22 @@
*/
#define POLARSSL_SELF_TEST
/**
* \def POLARSSL_SSL_DEBUG_ALL
*
* Enable the debug messages in SSL module for all issues.
* Debug messages have been disabled in some places to prevent timing
* attacks due to (unbalanced) debugging function calls.
*
* If you need all error reporting you should enable this during debugging,
* but remove this for production servers that should log as well.
*
* Uncomment this macro to report all debug messages on errors introducing
* a timing side-channel.
*
#define POLARSSL_SSL_DEBUG_ALL
*/
/**
* \def POLARSSL_SSL_HW_RECORD_ACCEL
*

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@ -1403,9 +1403,10 @@ static int ssl_decrypt_buf( ssl_context *ssl )
if( ssl->in_msglen < ssl->transform_in->maclen + padlen )
{
#if defined(POLARSSL_SSL_DEBUG_ALL)
SSL_DEBUG_MSG( 1, ( "msglen (%d) < maclen (%d) + padlen (%d)",
ssl->in_msglen, ssl->transform_in->maclen, padlen ) );
#endif
padlen = 0;
fake_padlen = 256;
correct = 0;
@ -1415,9 +1416,11 @@ static int ssl_decrypt_buf( ssl_context *ssl )
{
if( padlen > ssl->transform_in->ivlen )
{
#if defined(POLARSSL_SSL_DEBUG_ALL)
SSL_DEBUG_MSG( 1, ( "bad padding length: is %d, "
"should be no more than %d",
padlen, ssl->transform_in->ivlen ) );
#endif
correct = 0;
}
}
@ -1443,8 +1446,10 @@ static int ssl_decrypt_buf( ssl_context *ssl )
else
minlen = 1;
}
#if defined(POLARSSL_SSL_DEBUG_ALL)
if( padlen > 0 && correct == 0)
SSL_DEBUG_MSG( 1, ( "bad padding byte detected" ) );
#endif
}
}