[Libguestfs] libguestfs-tools with libvirt SASL authentication

[Richard W.M. Jones]

On Fri, Nov 07, 2014 at 02:37:06PM +0000, Dan Ryder (daryder) wrote:
> Thanks for the info, Richard.
>
> Hi Dan,
> 
> Any additional information on this?

I don't know if Dan B wants to chime in here, but can you try
out the following patch?

diff --git a/df/domains.c b/df/domains.c
index b2d9537..6cbc0f9 100644
--- a/df/domains.c
+++ b/df/domains.c
@@ -77,7 +77,8 @@ get_all_libvirt_domains (const char *libvirt_uri)
   size_t i;
 
   /* Get the list of all domains. */
-  conn = virConnectOpenReadOnly (libvirt_uri);
+  conn = virConnectOpenAuth (libvirt_uri, virConnectAuthPtrDefault,
+                             VIR_CONNECT_RO);
   if (!conn) {
     err = virGetLastError ();
     fprintf (stderr,

Rich.

> 
> -----Original Message-----
> From: Richard W.M. Jones [mailto:rjones at redhat.com] 
> Sent: Wednesday, November 05, 2014 8:46 AM
> To: Dan Ryder (daryder); berrange at redhat.com
> Cc: libguestfs at redhat.com
> Subject: Re: [Libguestfs] libguestfs-tools with libvirt SASL authentication
> 
> On Tue, Nov 04, 2014 at 06:47:04PM +0000, Dan Ryder (daryder) wrote:
> > Hello,
> > 
> > I'm running into an issue using the 'virt-df' command when SASL is enabled in libvirt. I'm running version 1.26.5 of libguestfs on an Ubuntu 14.04 OS.
> > 
> > I'm running 'virt-df' for all guests at one time, not specifying a domain or image to use. I was expecting a SASL authentication prompt but to no avail. Below is a sample run:
> > 
> > root at all-in-one:~# virt-df -P 15
> > libvirt: XML-RPC error : authentication failed: Failed to start SASL 
> > negotiation: -4 (SASL(-4): no mechanism available: No worthy mechs 
> > found)
> > virt-df: could not connect to libvirt (code 45, domain 7): 
> > authentication failed: Failed to start SASL negotiation: -4 (SASL(-4): 
> > no mechanism available: No worthy mechs found)
> > 
> > However, if I do specify a domain to run on, I am prompted for SASL authentication:
> > 
> > root at all-in-one:~# virt-df -d instance-0000004d libvirt needs 
> > authentication to connect to libvirt URI NULL (see also: 
> > http://libvirt.org/auth.html http://libvirt.org/uri.html) Please enter 
> > your authentication name: nova at all-in-one Please enter your password:
> > Filesystem                           1K-blocks       Used  Available  Use%
> > instance-0000004d:/dev/sdb                 458        458          0  100%
> > instance-0000004d:/dev/sda1              22773      12223       9322   54%
> > 
> > Is there any way to successfully run 'virt-df' for all instances at once while SASL is enabled in libvirt?
> 
> I think this may be a bug.
> 
> virt-df has potentially 3(!) places where it can make a libvirt connection, although only 2 of them are being used on Ubuntu.
> 
> (1) If you don't supply a list of domain names on the command line, then virt-df will call libvirt to get them.  That happens in
> df/domains.c:get_all_libvirt_domains:
> 
>   https://github.com/libguestfs/libguestfs/blob/master/df/domains.c#L72
> 
> If you supply a domain name, then this is not used.
> 
> (2) Secondly, virt-df calls into libguestfs (the C library) call
> guestfs_add_domain() with a domain name parameter as a literal string, either one fetched from (1) or one you passed on the command line.
> Libguestfs then looks that up with libvirt to check it exists and to get the list of disks.  That happens in
> src/libvirt-auth.c:guestfs___open_libvirt_connection:
> 
>   https://github.com/libguestfs/libguestfs/blob/master/src/libvirt-auth.c#L192
> 
> (3) Finally if you are using the libvirt backend (which you are not on
> Ubuntu) then there would be a third connection to run the appliance, although it uses the same code as (2).
> 
> I believe the problem here is that (1) does not pass an auth handler.
> ie. it calls virConnectOpenReadonly, not virConnectOpenAuth.  It's my understanding that virConnectOpenReadonly bypasses the policy kit and SASL stuff, but Dan Berrange (CC'd) will be able to tell me if I'm correct about that.
> 
> If that was the case then you would see an error when virt-df tries to get a list of domains.
> 
> Anyway, if it turns out to be a bug, please file it using the method outlined on the front page of the website (or submit a patch!)
> 
> Rich.
> 
> --
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines.  Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc.
> http://people.redhat.com/~rjones/virt-top

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-top is 'top' for virtual machines.  Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://people.redhat.com/~rjones/virt-top