qemu: Let empty default VNC password work as documented

CVE-2016-5008

Setting an empty graphics password is documented as a way to disable
VNC/SPICE access, but QEMU does not always behaves like that. VNC would
happily accept the empty password. Let's enforce the behavior by setting
password expiration to "now".

https://bugzilla.redhat.com/show_bug.cgi?id=1180092

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
(cherry picked from commit bb848feec0f3f10e92dd8e5231ae7aa89b5598f3)
(cherry picked from commit d933f68ee660566b52cd90330aee0d5f414636a4)

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index a589c8a0c6b387dd4a544c1698000c7071c05f9d..25335152d5bcebfbe7fa01764c3e4dd9eb3b34c2 100644 (file)
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -2930,6 +2930,7 @@ qemuDomainChangeGraphicsPasswords(virQEMUDriverPtr driver,
     time_t now = time(NULL);
     char expire_time [64];
     const char *connected = NULL;
+    const char *password;
     int ret = -1;
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
 
@@ -2937,15 +2938,13 @@ qemuDomainChangeGraphicsPasswords(virQEMUDriverPtr driver,
         ret = 0;
         goto cleanup;
     }
+    password = auth->passwd ? auth->passwd : defaultPasswd;
 
     if (auth->connected)
         connected = virDomainGraphicsAuthConnectedTypeToString(auth->connected);
 
     qemuDomainObjEnterMonitor(driver, vm);
-    ret = qemuMonitorSetPassword(priv->mon,
-                                 type,
-                                 auth->passwd ? auth->passwd : defaultPasswd,
-                                 connected);
+    ret = qemuMonitorSetPassword(priv->mon, type, password, connected);
 
     if (ret == -2) {
         if (type != VIR_DOMAIN_GRAPHICS_TYPE_VNC) {
@@ -2953,14 +2952,15 @@ qemuDomainChangeGraphicsPasswords(virQEMUDriverPtr driver,
                            _("Graphics password only supported for VNC"));
             ret = -1;
         } else {
-            ret = qemuMonitorSetVNCPassword(priv->mon,
-                                            auth->passwd ? auth->passwd : defaultPasswd);
+            ret = qemuMonitorSetVNCPassword(priv->mon, password);
         }
     }
     if (ret != 0)
         goto end_job;
 
-    if (auth->expires) {
+    if (password[0] == '\0') {
+        snprintf(expire_time, sizeof(expire_time), "now");
+    } else if (auth->expires) {
         time_t lifetime = auth->validTo - now;
         if (lifetime <= 0)
             snprintf(expire_time, sizeof(expire_time), "now");