Bug 862756

Fixes for the cloned bug should be copied to direct kernel boot code path, too. You can not currently use kernel/initrd from read only nfs to boot the VM.


+++ This bug was initially created as a clone of Bug #702044 +++

Description of problem:
When trying to attach iso from read-only filesystem (like NFS server administered by somebody else), it fails because iso's ownership cannot be changed to qemu:qemu

Version-Release number of selected component (if applicable):


How reproducible:
always

Steps to Reproduce:
1. run VM with empty cdrom device 
2. run 'virsh attach-disk win7x64 /path/on/readonly_fs/to/image.iso hdc --type cdrom;
3.
  
Actual results:
this error is throwed:
error: Failed to attach disk
error: unable to set user and group to '107:107' on '/mnt/trash/ic114/RHEV-toolsSetup_2.3_395.iso': Nepřípustný argument

Expected results:
disk is attached as read-only

Additional info:
* virt-manager fails with the same error
* 107:107 are UID:GID in local system
* unix permissions don't block qemu or libvirt from reading the isos, but selinux may block them (I don't know how to confirm this now)

--- Additional comment from laine on 2011-06-02 22:28:56 CEST ---

Nepřípustný argument == EINVAL

The error comes (as you'd guess) from chown(2). But the manpage for chown doesn't mention the possibility of returning EINVAL. virSecurityDACSetOwnership already special cases EOPNOTSUPP, EPERM, and EROFS to ignore them. Would it be acceptable in all cases to just ignore EINVAL as well?

--- Additional comment from laine on 2011-06-02 22:34:25 CEST ---

*** Bug 709454 has been marked as a duplicate of this bug. ***

--- Additional comment from laine on 2011-06-03 18:28:17 CEST ---

The following fix has been pushed to upstream libvirt, and will be in the next rebase for RHEL6:

commit 62ed801c13787cc844e75db7cd2d4c8a42454fcc
Author: Laine Stump <laine>
Date:   Fri Jun 3 11:59:09 2011 -0400

    security driver: ignore EINVAL when chowning an image file
    
    This fixes:
    
      https://bugzilla.redhat.com/show_bug.cgi?id=702044
      https://bugzilla.redhat.com/show_bug.cgi?id=709454
    
    Both of these complain of a failure to use an image file that resides
    on a read-only NFS volume. The function in the DAC security driver
    that chowns image files to the qemu user:group before using them
    already has special cases to ignore failure of chown on read-only file
    systems, and in a few other cases, but it hadn't been checking for
    EINVAL, which is what is returned if the qemu user doesn't even exist
    on the NFS server.
    
    Since the explanation of EINVAL in the chown man page almost exactly
    matches the log message already present for the case of EOPNOTSUPP,
    I've just added EINVAL to that same conditional.

--- Additional comment from laine on 2011-06-03 21:54:01 CEST ---

The question in Comment 1 was already answered in IRC (the answer was "yes").

--- Additional comment from veillard on 2011-06-23 05:14:19 CEST ---

This should be fixed by the libvirt-0.9.2-1.el6 rebase

--- Additional comment from zpeng on 2011-06-28 08:37:18 CEST ---

I can reproduce this in libvirt-0.8.7-18.el6
#mount -t nfs4 refarch.cloud.lab.eng.bos.redhat.com:/pub /testnfs

# virsh attach-disk rhel6 /testnfs/kits/os/Fedora/14/x86_64/Fedora-14-x86_64-DVD.iso hdc --type cdrom
error: Failed to attach disk
error: unable to set user and group to '107:107' on '/testnfs/kits/os/Fedora/14/x86_64/Fedora-14-x86_64-DVD.iso': Invalid argument

then update to libvirt-0.9.2-1.el6
# virsh attach-disk rhel6 /testnfs/kits/os/Fedora/14/x86_64/Fedora-14-x86_64-DVD.iso hdc --type cdrom
error: Failed to attach disk
error: internal error unable to execute QEMU command 'change': Could not open '/testnfs/kits/os/Fedora/14/x86_64/Fedora-14-x86_64-DVD.iso'
is the verification enough?  or need other settings and verify points?

--- Additional comment from djasa on 2011-06-28 09:35:59 CEST ---

(In reply to comment #7)
> I can reproduce this in libvirt-0.8.7-18.el6
> #mount -t nfs4 refarch.cloud.lab.eng.bos.redhat.com:/pub /testnfs
> 
> # virsh attach-disk rhel6
> /testnfs/kits/os/Fedora/14/x86_64/Fedora-14-x86_64-DVD.iso hdc --type cdrom
> error: Failed to attach disk
> error: unable to set user and group to '107:107' on
> '/testnfs/kits/os/Fedora/14/x86_64/Fedora-14-x86_64-DVD.iso': Invalid argument
> 
> then update to libvirt-0.9.2-1.el6
> # virsh attach-disk rhel6
> /testnfs/kits/os/Fedora/14/x86_64/Fedora-14-x86_64-DVD.iso hdc --type cdrom
> error: Failed to attach disk
> error: internal error unable to execute QEMU command 'change': Could not open
> '/testnfs/kits/os/Fedora/14/x86_64/Fedora-14-x86_64-DVD.iso'
> is the verification enough?  or need other settings and verify points?

It seems to me that libvirt can't read the file. Are the read permissions ok? Maybe you could try on read-only local filesystem first.

--- Additional comment from zpeng on 2011-06-28 13:08:55 CEST ---

Hi David:
i re-test this , seems the bug fixed
 setup read-only nfs on 10.66.4.239
#cat /etc/exports
/tmp/nfs *(ro)
on test machine :
#mount -t nfs4 10.66.4.239:/tmp/nfs /mnt
using libvirt-0.8.7-18.el6
# virsh attach-disk demo /mnt/boot.iso hdc --type cdrom
error: Failed to attach disk
error: unable to set user and group to '107:107' on '/mnt/boot.iso': Invalid argument

clear env.

update to libvirt-0.9.2-1.el6
# virsh attach-disk demo /mnt/boot.iso hdc --type cdrom
Disk attached successfully

--- Additional comment from rwu on 2011-07-06 12:31:56 CEST ---

Set it as VERIFIED per comment9

--- Additional comment from laine on 2011-09-28 08:26:23 CEST ---

*** Bug 712170 has been marked as a duplicate of this bug. ***

--- Additional comment from yury on 2011-09-28 09:39:26 CEST ---

Perfect, thanks!

--- Additional comment from errata-xmlrpc on 2011-12-06 12:06:34 CET ---

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2011-1513.html