On 19.7.2016 09:01, Fraser Tweedale wrote:
On Tue, Jul 19, 2016 at 08:26:22AM +0200, Jan Cholasta wrote:
Hi,

On 4.7.2016 09:06, Fraser Tweedale wrote:
On Tue, Jun 28, 2016 at 01:47:23PM -0000, freeipa wrote:
#6002: Default CA can be used without an ACL

Comment (by ftweedal):

 This is expected behaviour; if a CA ACL does not reference any CAs,
 and does not have cacat=all, then it is assumed to refer to the
 default CA.  This is for backwards compatibility with existing
 CA ACLs, which do not reference any CAs but did (and still do)
 allow access to IPA CA.

 Leaving open for discussion about whether to break compatibility
 for a more consistent behaviour.

Didn't get any feedback in the ticket yet so raising on list for
visibility.  If people agree with current behaviour I can add a
clarification to caacl plugin help text and close out this ticket.

(Sorry for the late reply, I was on vacation the last 2 weeks.)

I would very much prefer if this was consistent with (literally) every other
member list+category attribute, that is, no member and no category means the
rule never matches.

While documenting this as an exception to the above rule is the easy way
out, IMHO adhering to the rule is even better - anyone who touched HBAC or
sudo in IPA would immediately know their way around CA ACLs without having
to read the documentation at all, which is a win, because people don't
generally read documentation until something goes wrong. The current
behavior might surprise them, even if documented properly (it sure surprised
me at first :-).

BTW I think this can be done without breaking compatibility, e.g. by using a
new objectclass to distinguish between "old" (CA is always implicitly the
top-level CA) and "new" (CAs are specified using the member and category
attributes) CA ACLs.

Honza

Is there precedent of "varying behaviour based on objectclass" in
IPA?

Yes, for example in the permission plugin.


Would it go along the lines of...

1. subtype 'ipaCaAcl' object class (let us call it 'ipaCaAclWithCa'
   for sake of discussion).  (Note that moving the 'ipaCa' attribute
   to be part of 'ipaCaAclWithCa' would not be backwards compatible
   with v4.4 as currently released, so it would remain in 'ipaCaAcl'
   objectclass.)

2. Upgrade script to take 'ipaCaAcl' objects that are NOT
   'ipaCaAclWithCa', and make them so, while adding the IPA CA.

Is this what you have in mind?

Yes, something like this, but we can't inherit the new object class from ipaCaAcl if we want "new" CA ACLs to be invisible on 4.3 servers.


If so, I don't think there is actually a need to vary the behaviour
based on object class, other than during upgrade.  The reason I was
not doing upgrades in the first place was because I could not in
distinguish between "old" CA ACLs, and "new" CA ACLs that don't have
any CAs defined.  However, adding a new objectclass resolves this
ambiguity.

I'm not sure if this can be handled properly during upgrade only.

One could have a 4.3 server and 4.4 replica, add a CA ACL on the 4.3 server and then uninstall the server, which would leave the CA ACL not upgraded for indeterminate time.

Also we should keep "old" CA ACLs working on 4.3 servers, otherwise we would break cert-request on them, and I don't think this can be done without changing the object class at runtime.


Lmk what you think; I could be way off track :)

Cheers,
Fraser



--
Jan Cholasta

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