[Bug 1889033] Re: qemu-img permission denied on vmdk creation on CIFS share

[Thomas Huth]

The QEMU project is currently moving its bug tracking to another system.
For this we need to know which bugs are still valid and which could be
closed already. Thus we are setting the bug state to "Incomplete" now.

If the bug has already been fixed in the latest upstream version of QEMU,
then please close this ticket as "Fix released".

If it is not fixed yet and you think that this bug report here is still
valid, then you have two options:

1) If you already have an account on gitlab.com, please open a new ticket
for this problem in our new tracker here:

    https://gitlab.com/qemu-project/qemu/-/issues

and then close this ticket here on Launchpad (or let it expire auto-
matically after 60 days). Please mention the URL of this bug ticket on
Launchpad in the new ticket on GitLab.

2) If you don't have an account on gitlab.com and don't intend to get
one, but still would like to keep this ticket opened, then please switch
the state back to "New" within the next 60 days (otherwise it will get
closed as "Expired"). We will then eventually migrate the ticket auto-
matically to the new system (but you won't be the reporter of the bug
in the new system and thus won't get notified on changes anymore).

Thank you and sorry for the inconvenience.


** Changed in: qemu
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1889033

Title:
  qemu-img permission denied on vmdk creation on CIFS share

Status in QEMU:
  Incomplete

Bug description:
  
  - on a CIFS mount qemu-img claims not to have permissions to write into a 
file.
  - VMDK sparse file creation succeeds
  - VMDK Flat file creation create the flat-file, but fails to write the 
description-file
  - VMDK flat file creation succeeds on native linux mount such as ~/tmp or /tmp
  - same effect as root or non-root
  - same effect with selinux setenforce 0

  a) I would have expected that the monolithic flat would have created only one 
large file just like sparse, but it seems to create a description file, in 
addition to the storing file.
  b) I am aware that qemu-img may have problem opening very large files on 
CIFS, however, this file is not very large

  Windows-10 latest updated 2004 19041.388
  Linux VM, Fedora-32 in Virtualbox 6.1.12 
  # rpm -qa | grep  qemu-img
  qemu-img-4.2.0-7.fc32.x86_64

  mount options: 
  mount -t cifs //10.x,x,x/$shname  /mnt/hshare -o 
defaults,username=gana,rw,uid=1000,gid=1000,vers=3.0

  [root@fedora ~]# cd /mnt/hshare/some/folder/createvmdk/
  [root@fedora createvmdk]# qemu-img create -f vmdk test1.vmdk 100M -o 
subformat=monolithicFlat
  Formatting 'test1.vmdk', fmt=vmdk size=104857600 compat6=off 
hwversion=undefined subformat=monolithicFlat
  qemu-img: test1.vmdk: Could not write description: Permission denied
  [root@fedora createvmdk]# ls -l test1*.*
  -rwxr-xr-x. 1 gana gana 104857600 Jul 26 23:02 test1-flat.vmdk
  -rwxr-xr-x. 1 gana gana         0 Jul 26 23:02 test1.vmdk
  [root@fedora createvmdk]# du -k test1*.*
  0       test1-flat.vmdk
  0       test1.vmdk
  # (doesn't seem to be really flat)

  creation in /tmp works
  # cd /tmp
  [root@fedora tmp]# qemu-img create -f vmdk test1.vmdk 100M -o 
subformat=monolithicFlat
  Formatting 'test1.vmdk', fmt=vmdk size=104857600 compat6=off 
hwversion=undefined subformat=monolithicFlat
  [root@fedora tmp]# ls -l /tmp/test1*.*
  -rw-r--r--. 1 root root 104857600 Jul 26 22:43 /tmp/test1-flat.vmdk
  -rw-r--r--. 1 root root       313 Jul 26 22:43 /tmp/test1.vmdk
  [root@fedora createvmdk]# du -k /tmp/test1*.*
  4       /tmp/test1-flat.vmdk
  4       /tmp/test1.vmdk

  [root@fedora createvmdk]# cat /tmp/test1.vmdk
  # Disk DescriptorFile
  version=1
  CID=5f13c13d
  parentCID=ffffffff
  createType="monolithicFlat"

  # Extent description
  RW 204800 FLAT "test1-flat.vmdk" 0

  # The Disk Data Base
  #DDB

  ddb.virtualHWVersion = "4"
  ddb.geometry.cylinders = "203"
  ddb.geometry.heads = "16"
  ddb.geometry.sectors = "63"
  ddb.adapterType = "ide"

  
  On the other-hand creating a sparse file works
  cd /mnt/hshare/some/folder/createvmdk/
  [root@fedora createvmdk]# qemu-img create -f vmdk test2.vmdk 100M -o 
subformat=monolithicSparse
  Formatting 'test2.vmdk', fmt=vmdk size=104857600 compat6=off 
hwversion=undefined subformat=monolithicSparse
  [root@fedora createvmdk]# ls l test2*.*
  -rwxr-xr-x. 1 gana gana     65536 Jul 26 22:52 test2.vmdk
  [root@fedora createvmdk]#  du -k  /tmp/test2*.*
  12      /tmp/test2.vmdk

  test2.vmdk is a binary file
  inside it, located among garbled ascii characters is an embedded VMDK 
description
  ````
  # Disk DescriptorFile
  version=1
  CID=cf302a20
  parentCID=ffffffff
  createType="monolithicSparse"

  # Extent description
  RW 204800 SPARSE "test2.vmdk"

  # The Disk Data Base
  #DDB

  ddb.virtualHWVersion = "4"
  ddb.geometry.cylinders = "203"
  ddb.geometry.heads = "16"
  ddb.geometry.sectors = "63"
  ddb.adapterType = "ide"
  ```

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