Thanks for showing me this at the conference, Marco. I like the idea of authenticated users, but I haven't understood the role of the XenServer plugin here. Only a pool admin can call Host.call_plugin, and pool admins have the same permissions as root, so the plugin can't convey any additional privileges and I don't see how it acts as a security layer. In general, I think we should move away from XenServer plugins (and Alex Huang already made some steps in this direction at the beginning of the year). The problem with plugins is that if XenServer changes, it may break the plugin, and we will have to scramble to fix it up when we notice.
You also mentioned xenstore: I would certainly caution against using that, because it's not supposed to be a public interface. I guess my philosophy is that we should treat XenServer as a black box as much as possible, accessible only through the public API. (Of course, Host.call_plugin is an API call, but you know what I mean). Just because we know that dom0 is just a Linux box and we can do anything, doesn't mean that that's good architecture. XenCenter only uses the public API, for example. And if the public API doesn't provide something we really need, we should advocate to the upstream project to change it, or even submit a patch as XenServer is open source too. -- Stephen Turner -----Original Message----- From: Rohit Yadav [mailto:rohit.ya...@shapeblue.com] Sent: 24 November 2014 08:44 To: dev@cloudstack.apache.org Subject: Re: [Propose] Improvements in XenServer + ACS integration Great idea and work Marco! The gist of the proposal is that we can allow non-root users to add hosts and Marco successfully shows us how that is possible. > On 23-Nov-2014, at 5:42 pm, Marco Sinhoreli <marco.sinhor...@shapeblue.com> > wrote: > > Hi community, > > I'm starting this discussion to share some ideas about XenServer integration > in ACS. Since XenServer has some nice features to do that like RBAC, host > plugin and XenStore, I demonstrate these to some community members at CCCEU14. > > Some references you can look in these links: > https://blog.xenproject.org/2011/11/09/xcp-rbac-and-pam-authentication > -in-the-xenapi/ https://wiki.xenserver.org/index.php?title=RBAC > http://wiki.xen.org/wiki/XAPI_Host_Plugins > http://wiki.xen.org/wiki/XenStore > > Actual status in ACS: > During the XenServer setup, is possible to define a user to connect to the > xapi. In XenCenter, is possible to use a different user (no-root) using > external authentication like AD our PAM since the RBAC is configured properly > for this. In ACS it's not possible because many command need be called by > root using SSH. Another issue in this approach is about security: root > password is stored in DB and, in this approach we have a security compliance > issue. The root used used to call shell scripts in the XenServer host are all > hard-coded. > > What we can do? > - Substitute host SSH connection to XAPI host plugins In my view, I > prefer use just one-way to connect to XenServer, in this case, changing host > SSH interactions to use exclusively XAPI. XAPI implements Host Plugins where > could be used to as a security layer to call commands into host. > > An example of host plugin: > # cat xen_plugin_demo > #!/usr/bin/python > > import XenAPIPlugin > import subprocess > > def main(session, args): > try: > p = subprocess.Popen(args["cmd"].split(" "), stdout=subprocess.PIPE, > stderr=subprocess.PIPE) out, err = p.communicate() > return out > except KeyError: > raise RuntimeError("No argument found with key.") > > if __name__ == "__main__": > XenAPIPlugin.dispatch({"main": main}) > > And a client: > $ cat call_plugin.py > import XenAPI > import sys > > session = > XenAPI.Session('https://secure-web.cisco.com/11oaIT0CArnYayDlQLndB8lR7 > lQ49gVxf2sio9aLIq1ZY2HcalTSEU-sxMWIGBtez69UyOkhjgoSY99b9P1H6x2vKiMGr79 > TzSNVYdOK6BkY9mgKMi7MzA4LLWJmuMWocGWgyzznE_PdtwBz0xBzr3DuVUqw_OGIWtIDN > Gb6O0HA/https%3A%2F%2F192.168.56.12') > session.login_with_password('cloud', 'password') host, = > session.xenapi.host.get_all() > > print > print session.xenapi.host.call_plugin(host, 'xen_plugin_demo', 'main', > {'cmd' : " ".join(sys.argv[1:])}) > > Calling: > $ python call_plugin.py ls /root > > add_roles.sh > support.tar.bz2 > > - Setup RBAC to use a non-root to manage the XenServer host As a > suggestion, for this approach, need to have a user pre-seted in PAM or > configure XenServer AD. Follow what need be running in the XenServer shell to > setup the user, external auth, associate RBAC role to this user: > adduser cloudstack > password cloudstack > xe pool-enable-external-auth auth-type=PAM config:user=cloudstack > service-name=CloudStack xe subject-add subject-name=cloudstack > subject_uuid=$(xe subject-list | awk '/^uuid/{print $5}') > role_uuid=$(xe role-list name=pool-admin params=uuid | awk > '/^uuid/{print $5}') xe subject-role-add uuid=${subject_uuid} > role-uuid=${role_uuid} > > We can in this case, maintain the scripts used today, needing change the way > to call them from ACS. > > Best regards, > > > Marco Sinhoreli > Consultant Manager > > > > Phone: +55 21 2586 6390 | Fax: +55 21 2586 6002 | Mobile: +55 21 98276 > 3636 | Mobile: +55 21 99711 4645 Praia de Botafogo 501, bloco 1 - sala > 101, Botafogo, Rio de Janeiro, RJ - Brazil - CEP 22250-040 > marco.sinhor...@shapeblue.com | www.shapeblue.com | Twitter:@shapeBlue > > Find out more about ShapeBlue and our range of CloudStack related > services > > IaaS Cloud Design & Build > CSForge - rapid IaaS deployment framework CloudStack Consulting > CloudStack Software Engineering CloudStack Infrastructure Support > CloudStack Bootcamp Training Courses > > This email and any attachments to it may be confidential and are intended > solely for the use of the individual to whom it is addressed. Any views or > opinions expressed are solely those of the author and do not necessarily > represent those of Shape Blue Ltd or related companies. If you are not the > intended recipient of this email, you must neither take any action based upon > its contents, nor copy or show it to anyone. Please contact the sender if you > believe you have received this email in error. Shape Blue Ltd is a company > incorporated in England & Wales. ShapeBlue Services India LLP is a company > incorporated in India and is operated under license from Shape Blue Ltd. > Shape Blue Brasil Consultoria Ltda is a company incorporated in Brasil and is > operated under license from Shape Blue Ltd. ShapeBlue SA Pty Ltd is a company > registered by The Republic of South Africa and is traded under license from > Shape Blue Ltd. ShapeBlue is a registered trademark. Regards, Rohit Yadav Software Architect, ShapeBlue M. +91 88 262 30892 | rohit.ya...@shapeblue.com Blog: bhaisaab.org | Twitter: @_bhaisaab Find out more about ShapeBlue and our range of CloudStack related services IaaS Cloud Design & Build<http://shapeblue.com/iaas-cloud-design-and-build//> CSForge - rapid IaaS deployment framework<http://shapeblue.com/csforge/> CloudStack Consulting<http://shapeblue.com/cloudstack-consultancy/> CloudStack Software Engineering<http://shapeblue.com/cloudstack-software-engineering/> CloudStack Infrastructure Support<http://shapeblue.com/cloudstack-infrastructure-support/> CloudStack Bootcamp Training Courses<http://shapeblue.com/cloudstack-training/> This email and any attachments to it may be confidential and are intended solely for the use of the individual to whom it is addressed. Any views or opinions expressed are solely those of the author and do not necessarily represent those of Shape Blue Ltd or related companies. If you are not the intended recipient of this email, you must neither take any action based upon its contents, nor copy or show it to anyone. Please contact the sender if you believe you have received this email in error. Shape Blue Ltd is a company incorporated in England & Wales. ShapeBlue Services India LLP is a company incorporated in India and is operated under license from Shape Blue Ltd. Shape Blue Brasil Consultoria Ltda is a company incorporated in Brasil and is operated under license from Shape Blue Ltd. ShapeBlue SA Pty Ltd is a company registered by The Republic of South Africa and is traded under license from Shape Blue Ltd. ShapeBlue is a registered trademark.
