[Freeipa-users] HBAC

[TomK]

On 9/30/2015 8:12 AM, Martin Kosek wrote:
> On 09/30/2015 07:50 AM, Alexander Bokovoy wrote:
>> On Tue, 29 Sep 2015, TomK wrote:
>>> Hey Guy's,
>>>
>>> (Sending this again as I didn't have this email included in the freeipa-users
>>> mailing list so not sure if the other message will get posted.)
>>>
>>> Before I post a ticket to RH Support for an RFE, I'll post the request here
>>> to get some feedback on options and what ideas folks have.  I've a situation
>>> as follows.  I have the following setup in WS 2012 AD DC:
>>>
>>> TomK (user)
>>> TomK Groups:
>>>                 unixg
>>>                 windowsg
>>>
>>> unixg has the 'host' attribute defined 'lab01,lab02,lab03,lab04'
>>> windowsg has the 'host' attribute defined 'lab06,lab07,lab08,lab09'
>>>
>>> TomK(user) also has the 'host' attribute defined as per the proper RFC for
>>> LDAP.  With SSSD rules I can define the rules to read the user 'host'
>>> attribute but not the group 'host' attribute:
>>>
>>>
>>> |access_provider = ldap ldap_access_order = host ldap_user_authorized_host =
>>> host|
>>>
>>>
>>> Essentially TomK to be given access to hosts listed in the 'host' attribute
>>> but denied entry into lab05 for example (not listed in any group 'host'
>>> attribute above) to the server.   If I have a new user that has joined that
>>> particular team at our organization, I can simply add her/him to the above
>>> groups and this user would get access only to the listed servers in 'host'
>>> attribute by default. I don't need to specify new groups in customized
>>> sssd.conf or ldap.conf files or in sshd config files.  Hence less to update
>>> with Salt or any other CM suite.  I've managed to setup SUDO rules and with
>>> the openssh-ldap.diff schema SSH public keys could be stored in AD as well
>>> and be read by OpenSSH.  So aside from the HBAC capability on groups,
>>> virtually all our needs are handled by the WS2012 AD DC as it has to follow
>>> the OpenLDAP standard anyway.  Now to get this we considered and are still
>>> considering FreeIPA.  However this idea poses a set of challenges:
>>>
>>> 1) In large organizations where the AD support department are only trained in
>>> Windows AD setup and configuration (Only windows guy's) this would require a
>>> minimal of 3 bodies to support that know LDAP/Linux.  This is a large cost.
>>>
>>> 2) The additional server requires the same hardening as the Windows AD DC
>>> servers meaning a new procedure has to be carved out for the 2+ FreeIPA
>>> servers to be supported, hardened and maintained (upgraded).
>>>
>>> Now I probably sound somewhat anti-FreeIPA, however the challenges of
>>> implementing it in large organizations surface after some deliberation, so
>>> probably better to list then as it may help direct development of the product
>>> to contend with the challenges (Like having a document fully dedicated to
>>> hardening a FreeIPA server with selinux and other technologies in easy to
>>> maintain configuration).   I could be mistaken but some folks mention that
>>> it's 'better' to implement this sort of HBAC through other means (?? iptables
>>> ??) but never tried the alternatives yet.
>>>
>>> So, cutting to the end, would it be possible to add an attribute like:
>>>
>>> |ldap_user_authorized_host|
>>>
>>> but perhaps called 'ldap_group_authorized_host' to the SSSD code to enable
>>> reading the 'host' attribute on AD/LDAP defined groups?
>> In FreeIPA we support HBAC rules for AD users and groups. What exactly
>> is wrong with that?
>>
>> See 'ipa help trust' for details how to map AD groups to IPA groups and
>> then 'ipa help hbacrule' for how to limit access of those groups to
>> specific hosts and services on them.
>>
>> This is all covered well in the guide:
>> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Linux_Domain_Identity_Authentication_and_Policy_Guide/index.html
> More reading on External groups used for AD access control:
> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Windows_Integration_Guide/active-directory-trust.html#trust-win-groups
>
> I would also suggest a video with HBAC and Trust in action:
>
> https://www.youtube.com/watch?v=sQnNFJOzwa8
>
> HTH,
> Martin

We already defined HBAC rules in the manner that all the links you 
pointed out indicate as an early implementation.  As a product, there is 
no issue in IDM from that perspective.  This is all great and the 
product is fine from that perspective.

It would be good to have a dual option of either allowing SSSD or IDM / 
FreeIPA have full HBAC capability not just FreeIPA / IDM as in our 
organization that would be a huge cost savings vs implementing IDM as a 
separate Linux DC to be managed by a separate team.  So for those 
customers that wish to go directly to AD or have already invested in AD 
can choose SSSD only (If MS bundles AD with certain purchases, for 
example, that is an actual cost savings for a company).  Other customers 
who wish to keep the two separate so they do not flood AD DC's with non 
Windows AD settings can integrate IDM.

There will be cases where there could be a potential to save on costs vs 
AD so the Linux IDM could be chosen as an Enterprise DC to which Windows 
server authenticate as well as Linux ones or vice versa, whereas those 
organizations already implementing Windows AD can have the option to 
have Linux servers connecting to the AD DC via SSSD.

Since SSSD and IDM are so closely coupled, for someone who requires 
HBAC, the choice is either take both SSSD and IDM or neither.  So other 
solutions are being explored instead.

Do these reasons make sense as to why I posted the original ask?

Thanks,
TomK