[Libguestfs] Accessing iSCSI disc images from the RHEV Manager using libguestfs

[Richard W.M. Jones]

[Adding Itamar: Any suggestions on where Vitaly could get help on this
RHEV-M API problem?]

On Thu, Nov 21, 2013 at 02:27:08PM +0000, Исаев Виталий Анатольевич wrote:
> Dear libguestfs developers,
>
> We are developing the protected enterprise system based on several
> Red Hat technologies (Red Hat Enterprise Virtualisation, the IdM
> server and so on). Our current goal is to prevent the booting of the
> virtual machine in case of integrity loss. So what we are trying to
> do Is to intercept the event of the VM's start (using the RHEV
> Manager hook scripts), mount the starting VM's disk image with
> libguestfs and check the hash sums of the system files.
>
> When we have a local storage of disk images (manager, hypervisor and
> storage - all in one host), this approach works just perfect.
>
> But even a little bit complex network (with at least one manager,
> one hypervisor and one iSCSI/FC storage - three standalone physical
> hosts) blows our minds. RHEV Manager API provides the list of disk
> images which are (in this configurations) are logical volumes on the
> hypervisor and appear in hypervisor's /dev/mapper directory. But
> libguestfs from RHEV manager cannot access them.

When you say "cannot access them" do you get an error message?  Could
it be an SELinux denial?

I can tell you that libguestfs *should* be able to open any disk image
or block device.  But libguestfs doesn't have a magic way to bypass
permissions: if the block device needs (for example) root permissions
or SELinux is stopping things, libguestfs won't be able to open the
file, in the same way that /bin/cat or vi couldn't open it.

> Examples from libguestfs and guestfish guide (for instance, over
> ssh)

Remote access over ssh isn't enabled in RHEL 6 (nor in RHEL 7, sadly).
Is this a remote disk?  RHEL 7.0 will support NBD remote access only,
which probably doesn't help you.

Fedora of course enables every possible remote access method, but you
get to keep the pieces if it breaks.

> do not work. And even more, which host should we access - a
> hypervisor (with a different logical volumes) or a storage (with a
> monolith volume group)?

Itamar can probably help better than me here.

> Software version: RHEV 3.1, libguestfs 1.16.34, guest OS - RHEL 6.4, arch: x86_64.
> 
> P.S. May be I had to post this message directly to the support, but I'd suggest that this topic would be useful for community.
> 
> Thank you,
> Виталий Исаев
> Инженер-программист
> Группа разработки и внедрения ПСЗИ
> Департамент информационной безопасности
> ОАО <Финтех>

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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