api: disallow virDomainSaveImageGetXMLDesc on read-only connections

The virDomainSaveImageGetXMLDesc API is taking a path parameter,
which can point to any path on the system. This file will then be
read and parsed by libvirtd running with root privileges.

Forbid it on read-only connections.

Fixes: CVE-2019-10161
Reported-by: NMatthias Gerstner <mgerstner@suse.de>
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>
(cherry picked from commit aed6a032)
Signed-off-by: NJán Tomko <jtomko@redhat.com>

Conflicts:
  src/libvirt-domain.c
  src/remote/remote_protocol.x

Upstream commit 12a51f37 which introduced the VIR_DOMAIN_SAVE_IMAGE_XML_SECURE
alias for VIR_DOMAIN_XML_SECURE is not backported.
Just skip the commit since we now disallow the whole API on read-only
connections, regardless of the flag.
Signed-off-by: NJán Tomko <jtomko@redhat.com>

src/libvirt-domain.c

@@ -1077,9 +1077,7 @@ virDomainRestoreFlags(virConnectPtr conn, const char *from, const char *dxml,
  * previously by virDomainSave() or virDomainSaveFlags().
  *
  * No security-sensitive data will be included unless @flags contains
- * VIR_DOMAIN_XML_SECURE; this flag is rejected on read-only
- * connections.  For this API, @flags should not contain either
- * VIR_DOMAIN_XML_INACTIVE or VIR_DOMAIN_XML_UPDATE_CPU.
+ * VIR_DOMAIN_XML_SECURE.
  *
  * Returns a 0 terminated UTF-8 encoded XML instance, or NULL in case of
  * error.  The caller must free() the returned value.
@@ -1095,12 +1093,7 @@ virDomainSaveImageGetXMLDesc(virConnectPtr conn, const char *file,
 
     virCheckConnectReturn(conn, NULL);
     virCheckNonNullArgGoto(file, error);
-
-    if ((conn->flags & VIR_CONNECT_RO) && (flags & VIR_DOMAIN_XML_SECURE)) {
-        virReportError(VIR_ERR_OPERATION_DENIED, "%s",
-                       _("virDomainSaveImageGetXMLDesc with secure flag"));
-        goto error;
-    }
+    virCheckReadOnlyGoto(conn->flags, error);
 
     if (conn->driver->domainSaveImageGetXMLDesc) {
         char *ret;

src/qemu/qemu_driver.c

@@ -6757,7 +6757,7 @@ qemuDomainSaveImageGetXMLDesc(virConnectPtr conn, const char *path,
     if (fd < 0)
         goto cleanup;
 
-    if (virDomainSaveImageGetXMLDescEnsureACL(conn, def, flags) < 0)
+    if (virDomainSaveImageGetXMLDescEnsureACL(conn, def) < 0)
         goto cleanup;
 
     ret = qemuDomainDefFormatXML(driver, def, flags);

src/remote/remote_protocol.x

@@ -5009,8 +5009,7 @@ enum remote_procedure {
     /**
      * @generate: both
      * @priority: high
-     * @acl: domain:read
-     * @acl: domain:read_secure:VIR_DOMAIN_XML_SECURE
+     * @acl: domain:write
      */
     REMOTE_PROC_DOMAIN_SAVE_IMAGE_GET_XML_DESC = 235,