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.
(cherry picked from commit d66f070d492ef75405baad9f0d018b1bd06862c8)
Conflicts:
include/polarssl/config.h
library/ssl_tls.c
diff --git a/ChangeLog b/ChangeLog
index 5884e49..5afc2a1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,8 @@
= Branch 1.1
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
diff --git a/include/polarssl/config.h b/include/polarssl/config.h
index 110e3b4..e597edf 100644
--- a/include/polarssl/config.h
+++ b/include/polarssl/config.h
@@ -217,6 +217,22 @@
#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_X509_ALLOW_UNSUPPORTED_CRITICAL_EXTENSION
*
* If set, the X509 parser will not break-off when parsing an X509 certificate
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 95e912f..2c618a7 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -769,9 +769,10 @@
if( ssl->in_msglen < ssl->maclen + padlen )
{
+#if defined(POLARSSL_SSL_DEBUG_ALL)
SSL_DEBUG_MSG( 1, ( "msglen (%d) < maclen (%d) + padlen (%d)",
ssl->in_msglen, ssl->maclen, padlen ) );
-
+#endif
padlen = 0;
fake_padlen = 256;
correct = 0;
@@ -781,9 +782,11 @@
{
if( padlen > ssl->ivlen )
{
+#if defined(POLARSSL_SSL_DEBUG_ALL)
SSL_DEBUG_MSG( 1, ( "bad padding length: is %d, "
"should be no more than %d",
padlen, ssl->ivlen ) );
+#endif
correct = 0;
}
}
@@ -809,8 +812,10 @@
else
minlen = 1;
}
+#if defined(POLARSSL_SSL_DEBUG_ALL)
if( padlen > 0 && correct == 0)
SSL_DEBUG_MSG( 1, ( "bad padding byte detected" ) );
+#endif
}
}