Merge pull request #4529 from hanno-arm/ssl_session_cache_fix_backport_2x
Backport 2.x: Add session ID as an explicit parameter to SSL session cache API
diff --git a/ChangeLog.d/session-cache.txt b/ChangeLog.d/session-cache.txt
new file mode 100644
index 0000000..a12db3c
--- /dev/null
+++ b/ChangeLog.d/session-cache.txt
@@ -0,0 +1,5 @@
+Changes
+ * When using session cache based session resumption on the server,
+ double-check that custom session cache implementations return
+ sessions which are consistent with the negotiated ciphersuite
+ and compression method.
diff --git a/library/ssl_cache.c b/library/ssl_cache.c
index 7e9d4da..32188cf 100644
--- a/library/ssl_cache.c
+++ b/library/ssl_cache.c
@@ -78,14 +78,12 @@
continue;
#endif
- if( session->ciphersuite != entry->session.ciphersuite ||
- session->compression != entry->session.compression ||
- session->id_len != entry->session.id_len )
- continue;
-
- if( memcmp( session->id, entry->session.id,
+ if( session->id_len != entry->session.id_len ||
+ memcmp( session->id, entry->session.id,
entry->session.id_len ) != 0 )
+ {
continue;
+ }
ret = mbedtls_ssl_session_copy( session, &entry->session );
if( ret != 0 )
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 581b3f7..aca871e 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -2765,6 +2765,55 @@
}
#endif /* MBEDTLS_SSL_DTLS_HELLO_VERIFY */
+static void ssl_handle_id_based_session_resumption( mbedtls_ssl_context *ssl )
+{
+ int ret;
+ mbedtls_ssl_session session_tmp;
+ mbedtls_ssl_session * const session = ssl->session_negotiate;
+
+ /* Resume is 0 by default, see ssl_handshake_init().
+ * It may be already set to 1 by ssl_parse_session_ticket_ext(). */
+ if( ssl->handshake->resume == 1 )
+ return;
+ if( session->id_len == 0 )
+ return;
+ if( ssl->conf->f_get_cache == NULL )
+ return;
+#if defined(MBEDTLS_SSL_RENEGOTIATION)
+ if( ssl->renego_status != MBEDTLS_SSL_INITIAL_HANDSHAKE )
+ return;
+#endif
+
+ mbedtls_ssl_session_init( &session_tmp );
+
+ session_tmp.id_len = session->id_len;
+ memcpy( session_tmp.id, session->id, session->id_len );
+
+ ret = ssl->conf->f_get_cache( ssl->conf->p_cache,
+ &session_tmp );
+ if( ret != 0 )
+ goto exit;
+
+ if( session->ciphersuite != session_tmp.ciphersuite ||
+ session->compression != session_tmp.compression )
+ {
+ /* Mismatch between cached and negotiated session */
+ goto exit;
+ }
+
+ /* Move semantics */
+ mbedtls_ssl_session_free( session );
+ *session = session_tmp;
+ memset( &session_tmp, 0, sizeof( session_tmp ) );
+
+ MBEDTLS_SSL_DEBUG_MSG( 3, ( "session successfully restored from cache" ) );
+ ssl->handshake->resume = 1;
+
+exit:
+
+ mbedtls_ssl_session_free( &session_tmp );
+}
+
static int ssl_write_server_hello( mbedtls_ssl_context *ssl )
{
#if defined(MBEDTLS_HAVE_TIME)
@@ -2835,22 +2884,7 @@
MBEDTLS_SSL_DEBUG_BUF( 3, "server hello, random bytes", buf + 6, 32 );
- /*
- * Resume is 0 by default, see ssl_handshake_init().
- * It may be already set to 1 by ssl_parse_session_ticket_ext().
- * If not, try looking up session ID in our cache.
- */
- if( ssl->handshake->resume == 0 &&
-#if defined(MBEDTLS_SSL_RENEGOTIATION)
- ssl->renego_status == MBEDTLS_SSL_INITIAL_HANDSHAKE &&
-#endif
- ssl->session_negotiate->id_len != 0 &&
- ssl->conf->f_get_cache != NULL &&
- ssl->conf->f_get_cache( ssl->conf->p_cache, ssl->session_negotiate ) == 0 )
- {
- MBEDTLS_SSL_DEBUG_MSG( 3, ( "session successfully restored from cache" ) );
- ssl->handshake->resume = 1;
- }
+ ssl_handle_id_based_session_resumption( ssl );
if( ssl->handshake->resume == 0 )
{