Allow compile-time configuration of DTLS anti replay
Introduce MBEDTLS_SSL_CONF_ANTI_REPLAY to allow configuring
the use/nonuse of DTLS anti replay protection at compile-time.
Impact on code-size, measured with
> ./scripts/baremetal.sh --rom --gcc --armc5 --armc6
| | GCC | ARMC5 | ARMC6 |
| --- | --- | --- | --- |
| `libmbedtls.a` before | 23559 | 24089 | 27921 |
| `libmbedtls.a` after | 23511 | 24049 | 27903 |
| gain in Bytes | 48 | 40 | 18 |
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 2116521..1ff34dc 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -3450,6 +3450,9 @@
* \{
*/
+/* DTLS Anti replay */
+//#define MBEDTLS_SSL_CONF_ANTI_REPLAY MBEDTLS_SSL_ANTI_REPLAY_ENABLED
+
/* ExtendedMasterSecret extension
* The following two options must be set/unset simultaneously. */
//#define MBEDTLS_SSL_CONF_EXTENDED_MASTER_SECRET MBEDTLS_SSL_EXTENDED_MS_ENABLED
diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index b517089..fbc6109 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1070,8 +1070,10 @@
#endif /* !MBEDTLS_SSL_CONF_ENFORCE_EXTENDED_MASTER_SECRET */
#endif
#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+#if !defined(MBEDTLS_SSL_CONF_ANTI_REPLAY)
unsigned int anti_replay : 1; /*!< detect and prevent replay? */
-#endif
+#endif /* !MBEDTLS_SSL_CONF_ANTI_REPLAY */
+#endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
#if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
unsigned int cbc_record_splitting : 1; /*!< do cbc record splitting */
#endif
@@ -2016,14 +2018,16 @@
#endif /* MBEDTLS_SSL_DTLS_HELLO_VERIFY && MBEDTLS_SSL_SRV_C */
-#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY) && \
+ !defined(MBEDTLS_SSL_CONF_ANTI_REPLAY)
/**
* \brief Enable or disable anti-replay protection for DTLS.
* (DTLS only, no effect on TLS.)
* Default: enabled.
*
* \param conf SSL configuration
- * \param mode MBEDTLS_SSL_ANTI_REPLAY_ENABLED or MBEDTLS_SSL_ANTI_REPLAY_DISABLED.
+ * \param mode MBEDTLS_SSL_ANTI_REPLAY_ENABLED or
+ * MBEDTLS_SSL_ANTI_REPLAY_DISABLED.
*
* \warning Disabling this is a security risk unless the application
* protocol handles duplicated packets in a safe way. You
@@ -2031,9 +2035,13 @@
* However, if your application already detects duplicated
* packets and needs information about them to adjust its
* transmission strategy, then you'll want to disable this.
+ *
+ * \note On constrained systems, this option can also be
+ * fixed at compile-time by defining the constant
+ * MBEDTLS_SSL_CONF_ANTI_REPLAY.
*/
void mbedtls_ssl_conf_dtls_anti_replay( mbedtls_ssl_config *conf, char mode );
-#endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
+#endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY && !MBEDTLS_SSL_CONF_ANTI_REPLAY */
#if defined(MBEDTLS_SSL_DTLS_BADMAC_LIMIT)
/**
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 7009c4f..092819e 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -1085,6 +1085,23 @@
* be fixed at compile time via one of MBEDTLS_SSL_SSL_CONF_XXX.
*/
+#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
+#if !defined(MBEDTLS_SSL_CONF_ANTI_REPLAY)
+static inline unsigned int mbedtls_ssl_conf_get_anti_replay(
+ mbedtls_ssl_config const *conf )
+{
+ return( conf->anti_replay );
+}
+#else /* !MBEDTLS_SSL_CONF_ANTI_REPLAY */
+static inline unsigned int mbedtls_ssl_conf_get_anti_replay(
+ mbedtls_ssl_config const *conf )
+{
+ ((void) conf);
+ return( MBEDTLS_SSL_CONF_ANTI_REPLAY );
+}
+#endif /* MBEDTLS_SSL_CONF_ANTI_REPLAY */
+#endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
+
#if defined(MBEDTLS_SSL_EXTENDED_MASTER_SECRET)
static inline unsigned int mbedtls_ssl_conf_get_ems(
mbedtls_ssl_config const *conf )