Make mbedtls_ssl_set_hostname safe to be called multiple times
Zeroize and free previously set hostnames before overwriting
them. Also, allow clearance of hostname by providing NULL parameter.
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index b388156..b837690 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -6166,7 +6166,7 @@
{
conf->sig_hashes = hashes;
}
-#endif
+#endif /* MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */
#if defined(MBEDTLS_ECP_C)
/*
@@ -6177,32 +6177,51 @@
{
conf->curve_list = curve_list;
}
-#endif
+#endif /* MBEDTLS_ECP_C */
#if defined(MBEDTLS_X509_CRT_PARSE_C)
int mbedtls_ssl_set_hostname( mbedtls_ssl_context *ssl, const char *hostname )
{
- size_t hostname_len;
+ /* Initialize to suppress unnecessary compiler warning */
+ size_t hostname_len = 0;
+
+ /* Check if new hostname is valid before
+ * making any change to current one */
+
+ if( hostname != NULL )
+ {
+ hostname_len = strlen( hostname );
+
+ if( hostname_len > MBEDTLS_SSL_MAX_HOST_NAME_LEN )
+ return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+ }
+
+ /* Now it's clear that we will overwrite the old hostname,
+ * so we can free it safely */
+
+ if( ssl->hostname != NULL )
+ {
+ mbedtls_zeroize( ssl->hostname, strlen( ssl->hostname ) );
+ mbedtls_free( ssl->hostname );
+ }
+
+ /* Passing NULL as hostname shall clear the old one */
if( hostname == NULL )
- return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+ {
+ ssl->hostname = NULL;
+ }
+ else
+ {
+ ssl->hostname = mbedtls_calloc( 1, hostname_len + 1 );
- hostname_len = strlen( hostname );
+ if( ssl->hostname == NULL )
+ return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
- if( hostname_len + 1 == 0 )
- return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+ memcpy( ssl->hostname, hostname, hostname_len );
- if( hostname_len > MBEDTLS_SSL_MAX_HOST_NAME_LEN )
- return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
-
- ssl->hostname = mbedtls_calloc( 1, hostname_len + 1 );
-
- if( ssl->hostname == NULL )
- return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
-
- memcpy( ssl->hostname, hostname, hostname_len );
-
- ssl->hostname[hostname_len] = '\0';
+ ssl->hostname[hostname_len] = '\0';
+ }
return( 0 );
}