libvirt users - Jul 2013 - nova-compute, libvirt and authentication

Hello

I have a question about live migration when libvirt requires sasl
authentication. I have managed to configure remote access for user nova
with sasl enabled (credentials stored in auth.conf -
https://review.openstack.org/#/c/12706/). It looks like live migration do
not use these credentials at all. What is more it thinks that sasl is not
not configured:

2013-07-01 09:49:09.317+0000: 17997: error :
virNetSASLSessionClientStart:484 : authentication failed: Failed to start
SASL negotiation: -4 (SASL(-4): no mechanism available: No worthy mechs
found)
2013-07-01 09:49:09.317+0000: 17997: error : doPeer2PeerMigrate:2527 :
operation failed: Failed to connect to remote libvirt URI
qemu+tcp://n12c1/system

I execute migration like this:
nova live-migration  c923af69-4cb3-46dd-8bd2-871812d7d223 n12c1

Nova.conf:
live_migration_flag=VIR_MIGRATE_UNDEFINE_SOURCE,VIR_MIGRATE_PEER2PEER,VIR_MIGRATE_LIVE

Could you please let me know whether nova/libvirt support p2p live
migration with sasl and if so point out what might be misconfigured?
Disabling sasl solves all my problems but I have to configure some
authentication.

I would really appreciate your help.

regards
-- 
Maciej Ga?kiewicz
Shelly Cloud Sp. z o. o., Sysadmin
http://shellycloud.com/, macias at shellycloud.com
KRS: 0000440358 REGON: 101504426
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On 07/01/2013 01:27 PM, Maciej Ga?kiewicz wrote:
> Hello
> 
> I have a question about live migration when libvirt requires sasl
> authentication. I have managed to configure remote access for user nova
> with sasl enabled (credentials stored in auth.conf -
> https://review.openstack.org/#/c/12706/). It looks like live migration do
> not use these credentials at all. What is more it thinks that sasl is not
> not configured:
> 
I'd say this is a problem with sasl, nothing else.  "No mechanism
found"
may mean that libraries for configured mechanism aren't found or unknown
mechanism is being requested.  I doubt that access to those libraries
would be a permisison problem, but you might be missing some
cyrus-sasl-* package.  What distro are you running on and what
sasl-related packages do you have installed?
> 2013-07-01 09:49:09.317+0000: 17997: error :
> virNetSASLSessionClientStart:484 : authentication failed: Failed to start
> SASL negotiation: -4 (SASL(-4): no mechanism available: No worthy mechs
> found)
> 2013-07-01 09:49:09.317+0000: 17997: error : doPeer2PeerMigrate:2527 :
> operation failed: Failed to connect to remote libvirt URI
> qemu+tcp://n12c1/system
> 
> I execute migration like this:
> nova live-migration  c923af69-4cb3-46dd-8bd2-871812d7d223 n12c1
> 
> Nova.conf:
>
live_migration_flag=VIR_MIGRATE_UNDEFINE_SOURCE,VIR_MIGRATE_PEER2PEER,VIR_MIGRATE_LIVE
> 
> Could you please let me know whether nova/libvirt support p2p live
> migration with sasl and if so point out what might be misconfigured?
> Disabling sasl solves all my problems but I have to configure some
> authentication.
> 
> I would really appreciate your help.
> 
> regards
> 
> 
> 
> _______________________________________________
> libvirt-users mailing list
> libvirt-users at redhat.com
> https://www.redhat.com/mailman/listinfo/libvirt-users
>

On 2 July 2013 09:58, Martin Kletzander <mkletzan@redhat.com> wrote:
> I'd say this is a problem with sasl, nothing else.  "No mechanism
found"
> may mean that libraries for configured mechanism aren't found or
unknown
> mechanism is being requested.  I doubt that access to those libraries
> would be a permisison problem, but you might be missing some
> cyrus-sasl-* package.  What distro are you running on and what
> sasl-related packages do you have installed?
>
If there is a problem with sasl why I am able to successfully use it for
example through:
virsh -c qemu+tcp://my_remote_server/system list

I am running debian 7.1 (wheezy). Sasl libs:
# dpkg -l | grep sasl
ii  libsasl2-2:amd64                   2.1.25.dfsg1-6+deb7u1        amd64
     Cyrus SASL - authentication abstraction library
ii  libsasl2-modules:amd64             2.1.25.dfsg1-6+deb7u1        amd64
     Cyrus SASL - pluggable authentication modules
ii  sasl2-bin                          2.1.25.dfsg1-6+deb7u1        amd64
     Cyrus SASL - administration programs for SASL users database


regards
-- 
Maciej Gałkiewicz
Shelly Cloud Sp. z o. o., Sysadmin
http://shellycloud.com/, macias@shellycloud.com
KRS: 0000440358 REGON: 101504426

On Mon, Jul 01, 2013 at 01:27:24PM +0200, Maciej Gałkiewicz
wrote:
> Hello
> 
> I have a question about live migration when libvirt requires sasl
> authentication. I have managed to configure remote access for user nova
> with sasl enabled (credentials stored in auth.conf -
> https://review.openstack.org/#/c/12706/). It looks like live migration do
> not use these credentials at all. What is more it thinks that sasl is not
> not configured:
> 
> 2013-07-01 09:49:09.317+0000: 17997: error :
> virNetSASLSessionClientStart:484 : authentication failed: Failed to start
> SASL negotiation: -4 (SASL(-4): no mechanism available: No worthy mechs
> found)
> 2013-07-01 09:49:09.317+0000: 17997: error : doPeer2PeerMigrate:2527 :
> operation failed: Failed to connect to remote libvirt URI
> qemu+tcp://n12c1/system
> 
> I execute migration like this:
> nova live-migration  c923af69-4cb3-46dd-8bd2-871812d7d223 n12c1
> 
> Nova.conf:
>
live_migration_flag=VIR_MIGRATE_UNDEFINE_SOURCE,VIR_MIGRATE_PEER2PEER,VIR_MIGRATE_LIVE
> 
> Could you please let me know whether nova/libvirt support p2p live
> migration with sasl and if so point out what might be misconfigured?
> Disabling sasl solves all my problems but I have to configure some
> authentication.
Hmm, so Nova uses  migrateToURI, which means that the source
libvirtd connects directly to the destination libvirtd. Looking
at the code though, it seems to be using virConnectOpen(), which
means that all the authentication callbacks are disabled. Since
no auth callback is present, SASL doesn't find any mechanisms,
and thus auth fails.

So I think this is a flaw in the QEMU migration code, which
should instead use virConnectOpenAuth().

The only workaround you have in the shorterm is to configure
libvirtd to use TLS + x509 certificates for security and then
setup a whitelist of TLS cert distinguished names in libvirtd.conf
to control which servers can connect to each other

Daniel
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