libxl: Specify format of inserted cdrom

Without this extra parameter on the QMP command, QEMU will guess the
format of the new file.

This is XSA-258.

Reported-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
master commit: d8f65e68a7
master date: 2018-04-25 14:38:47 +0200

tools/libxl/libxl_device.c

@@ -425,6 +425,18 @@ char *libxl__device_disk_string_of_backend(libxl_disk_backend backend)
     }
 }
 
+const char *libxl__qemu_disk_format_string(libxl_disk_format format)
+{
+    switch (format) {
+    case LIBXL_DISK_FORMAT_QCOW: return "qcow";
+    case LIBXL_DISK_FORMAT_QCOW2: return "qcow2";
+    case LIBXL_DISK_FORMAT_VHD: return "vpc";
+    case LIBXL_DISK_FORMAT_RAW: return "raw";
+    case LIBXL_DISK_FORMAT_EMPTY: return NULL;
+    default: return NULL;
+    }
+}
+
 int libxl__device_physdisk_major_minor(const char *physpath, int *major, int *minor)
 {
     struct stat buf;

tools/libxl/libxl_dm.c

@@ -669,18 +669,6 @@ static int libxl__build_device_model_args_old(libxl__gc *gc,
     return 0;
 }
 
-static const char *qemu_disk_format_string(libxl_disk_format format)
-{
-    switch (format) {
-    case LIBXL_DISK_FORMAT_QCOW: return "qcow";
-    case LIBXL_DISK_FORMAT_QCOW2: return "qcow2";
-    case LIBXL_DISK_FORMAT_VHD: return "vpc";
-    case LIBXL_DISK_FORMAT_RAW: return "raw";
-    case LIBXL_DISK_FORMAT_EMPTY: return NULL;
-    default: return NULL;
-    }
-}
-
 static char *dm_spice_options(libxl__gc *gc,
                                     const libxl_spice_info *spice)
 {
@@ -1342,9 +1330,9 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
              * always raw
              */
             if (disks[i].backend == LIBXL_DISK_BACKEND_QDISK)
-                format = qemu_disk_format_string(disks[i].format);
+                format = libxl__qemu_disk_format_string(disks[i].format);
             else
-                format = qemu_disk_format_string(LIBXL_DISK_FORMAT_RAW);
+                format = libxl__qemu_disk_format_string(LIBXL_DISK_FORMAT_RAW);
 
             if (disks[i].format == LIBXL_DISK_FORMAT_EMPTY) {
                 if (!disks[i].is_cdrom) {

tools/libxl/libxl_internal.h

@@ -1170,6 +1170,7 @@ _hidden int libxl__domain_pvcontrol_write(libxl__gc *gc, xs_transaction_t t,
 /* from xl_device */
 _hidden char *libxl__device_disk_string_of_backend(libxl_disk_backend backend);
 _hidden char *libxl__device_disk_string_of_format(libxl_disk_format format);
+_hidden const char *libxl__qemu_disk_format_string(libxl_disk_format format);
 _hidden int libxl__device_disk_set_backend(libxl__gc*, libxl_device_disk*);
 
 _hidden int libxl__device_physdisk_major_minor(const char *physpath, int *major, int *minor);

tools/libxl/libxl_qmp.c

@@ -982,6 +982,8 @@ int libxl__qmp_insert_cdrom(libxl__gc *gc, int domid,
         return qmp_run_command(gc, domid, "eject", args, NULL, NULL);
     } else {
         qmp_parameters_add_string(gc, &args, "target", disk->pdev_path);
+        qmp_parameters_add_string(gc, &args, "arg",
+            libxl__qemu_disk_format_string(disk->format));
         return qmp_run_command(gc, domid, "change", args, NULL, NULL);
     }
 }