On Fri, Jun 01, 2018 at 07:59:51AM +0300, Mykola Ivanets wrote:
I saw several Windows disk images which contains strange registry
entry
for mapped drives:
"\\DosDevices\\Y:"=hex(3):00,00,00,00,00,00,00,00,00,00,00,00
Which is decoded something like diskID = 0x0, partition starts at 0
bytes offset from the start of the disk. In addition to a Windows disk
image, I have attached dummy disk and made xfs file system on a whole
device without partitioning it. I mount xfs file system to a "/" and
then mkdir and mount other found file systems inside (/fs1, /fs2 etc.).
When we decode drive mappings we are looking for a disk with ID 0x0 (it
is 4 bytes somewhere LBA0). It is appeared that dummy non-partitioned
disk with xfs file system has zeros by offset where diskID is expected
to be). So the disk is considered as a candidate to search for
partition at offset 0. part-list command (and "parted" which is used
under the hood) reports there is 1 partition on "dummy" disk which
starts exactly at offset 0. And thus dummy device name and partition
number are simply concatenated together and corresponding drive mapping
is returned: Y => /dev/sdX1. But /dev/sdX1 is not existing block
device.
No matter either it is a bug in "parted" (or it works this way
by-design), let's protect ourself from this situation: in addition we
look for msdos partition table on a disk before making any further
assumptions.
---
daemon/inspect_fs_windows.ml | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/daemon/inspect_fs_windows.ml b/daemon/inspect_fs_windows.ml
index 8b2aad8d3..af52dee2d 100644
--- a/daemon/inspect_fs_windows.ml
+++ b/daemon/inspect_fs_windows.ml
@@ -329,7 +329,7 @@ and get_drive_mappings h root data =
String.is_prefix blob "DMIO:ID:" (* GPT *) then
map_registry_disk_blob_gpt (Lazy.force partitions) blob
else if String.length blob = 12 then
- map_registry_disk_blob (Lazy.force devices) blob
+ map_registry_disk_blob_mbr (Lazy.force devices) blob
else
None
)
@@ -356,13 +356,18 @@ and get_drive_mappings h root data =
* The following function maps this blob to a libguestfs partition
* name, if possible.
*)
-and map_registry_disk_blob devices blob =
+and map_registry_disk_blob_mbr devices blob =
try
(* First 4 bytes are the disk ID. Search all devices to find the
* disk with this disk ID.
*)
let diskid = String.sub blob 0 4 in
- let device = List.find (fun dev -> pread dev 4 0x01b8 = diskid) devices in
+ let device =
+ List.find (
+ fun dev ->
+ Parted.part_get_parttype dev = "msdos" &&
+ pread dev 4 0x01b8 = diskid
+ ) devices in
Looks sensible, ACK.
Will push it in a bit, thanks.
Rich.
--
Richard Jones, Virtualization Group, Red Hat
http://people.redhat.com/~rjones
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