[Freeipa-devel] [PATCH 0049] Add support for protected tokens

Tue May 13 17:12:48 UTC 2014

On Tue, 2014-05-13 at 16:33 +0200, Jan Cholasta wrote:
> On 12.5.2014 21:02, Nathaniel McCallum wrote:
> > On Thu, 2014-05-08 at 13:51 -0400, Simo Sorce wrote:
> >> On Thu, 2014-05-08 at 12:26 -0400, Nathaniel McCallum wrote:
> >>> On Wed, 2014-05-07 at 11:17 -0400, Simo Sorce wrote:
> >>>> On Wed, 2014-05-07 at 09:54 -0400, Dmitri Pal wrote:
> >>>>> On 05/07/2014 09:05 AM, Nathaniel McCallum wrote:
> >>>>>> On Wed, 2014-05-07 at 11:42 +0200, Jan Cholasta wrote:
> >>>>>>> Hi,
> >>>>>>>
> >>>>>>> On 6.5.2014 17:08, Nathaniel McCallum wrote:
> >>>>>>>> On Tue, 2014-05-06 at 09:49 -0400, Nathaniel McCallum wrote:
> >>>>>>>>> On Mon, 2014-05-05 at 12:42 -0400, Nathaniel McCallum wrote:
> >>>>>>>>>> This also constitutes a rethinking of the token ACIs after the
> >>>>>>>>>> introduction of SELFDN support.
> >>>>>>>>>>
> >>>>>>>>>> Admins, as before, have full access to all token permissions.
> >>>>>>>>>>
> >>>>>>>>>> Normal users have read/search/compare access to all of the non-secret
> >>>>>>>>>> data for tokens assigned to them, whether protected or non-protected.
> >>>>>>>>>> Users can add or delete non-protected tokens and modify most of their
> >>>>>>>>>> metadata. However they cannot create, delete or modify protected tokens.
> >>>>>>>>>> Regardless of whether the token is protected or not, users cannot change
> >>>>>>>>>> a token's ownership or unique identity.
> >>>>>>>>>>
> >>>>>>>>>> In contrast, admins can create protected tokens. This protects the token
> >>>>>>>>>> from deletion or modification when assigned to users. Additionally, when
> >>>>>>>>>> a user account is deleted, the assigned non-protected tokens are deleted
> >>>>>>>>>> but the protected tokens are merely orphaned. This permits the token to
> >>>>>>>>>> be reassigned without having to recreate it. This last point is
> >>>>>>>>>> particularly useful in the case of hardware tokens.
> >>>>>>>>>>
> >>>>>>>>>> https://fedorahosted.org/freeipa/ticket/4228
> >>>>>>>>>>
> >>>>>>>>>> NOTE: This patch depends on my patch 0048.
> >>>>>>>>> This new version makes ipatokenDisabled visible for token owners. It is
> >>>>>>>>> also writable if the token is non-protected. This additionally fixes:
> >>>>>>>>>
> >>>>>>>>> https://fedorahosted.org/freeipa/ticket/4259
> >>>>>>>> This new version changes the way the default value of protected is setup
> >>>>>>>> in accordance with the changes made for the review of my patch 0048.2.
> >>>>>>>>
> >>>>>>>> Nathaniel
> >>>>>>> Is using the ipatokenprotected attribute the final design?
> >>>>>> No. Alternate designs are welcome. The code is easy enough to modify.
> >>>>>>
> >>>>>>> I did not dig too deep into this, but I think it might be better to
> >>>>>>> instead use the managedby attribute on a token to limit who can delete
> >>>>>>> (or administer in other way) the token. On otptoken-add, managedby would
> >>>>>>> be set to the "whoami" user DN, unless run with --protected, in which
> >>>>>>> case managedby would be left empty. Then, when deleting a user, the
> >>>>>>> token would be deleted only if the user manages the token.
> >>>>>> It seems to me that the mechanics of this are roughly the same as
> >>>>>> protected, just with a different syntax. The cost of this is more
> >>>>>> complex ACIs. In particular, we'd have to use two userdn clauses (is
> >>>>>> this possible?) instead of a simple filter. If there is a clear benefit,
> >>>>>> we can justify the more obtuse syntax.
> >>>>>
> >>>>> We usually try not to create new attributes until it is fully justified.
> >>>>> I would like Simo to chime in on this.
> >>>>
> >>>> I would also prefer to reuse existing attributes and mechanism if
> >>>> possible and if it will not preclude future work.
> >>>>
> >>>> In this case, it "sounds" like managed-by has the appropriate meaning:
> >>>> "who manages the token ?" -> myself, admin, other, none ?
> >>>>
> >>>> Nathaniel can you send 2 lines showing the difference in ACIs between
> >>>> using managed-by vs a new attribute ?
> >>>
> >>> These are the ACIs using the protected mechanism:
> >>>
> >>> aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs =
> >>> "objectclass || description || ipatokenUniqueID || ipatokenDisabled ||
> >>> ipatokenNotBefore || ipatokenNotAfter || ipatokenVendor || ipatokenModel
> >>> || ipatokenSerial || ipatokenOwner || ipatokenProtected")(version 3.0;
> >>> acl "Users can read basic token info"; allow (read, search, compare)
> >>> userattr = "ipatokenOwner#USERDN";)
> >>>
> >>> aci: (targetfilter = "(objectClass=ipatokenTOTP)")(targetattrs =
> >>> "ipatokenOTPalgorithm || ipatokenOTPdigits ||
> >>> ipatokenTOTPtimeStep")(version 3.0; acl "Users can see TOTP details";
> >>> allow (read, search, compare) userattr = "ipatokenOwner#USERDN";)
> >>>
> >>> aci: (targetfilter = "(objectClass=ipatokenHOTP)")(targetattrs =
> >>> "ipatokenOTPalgorithm || ipatokenOTPdigits")(version 3.0; acl "Users can
> >>> see HOTP details"; allow (read, search, compare) userattr =
> >>> "ipatokenOwner#USERDN";)
> >>>
> >>> aci: (targetfilter =
> >>> "(&(objectClass=ipaToken)(!(ipatokenProtected=TRUE)))")(targetattrs =
> >>> "description || ipatokenDisabled || ipatokenNotBefore ||
> >>> ipatokenNotAfter || ipatokenVendor || ipatokenModel ||
> >>> ipatokenSerial")(version 3.0; acl "Users can write basic token info";
> >>> allow (write) userattr = "ipatokenOwner#USERDN";)
> >>>
> >>> aci: (target = "ldap:///ipatokenuniqueid=*,cn=otp,$SUFFIX")(targetfilter
> >>> = "(&(objectClass=ipaToken)(!(ipatokenProtected=TRUE))))")(version 3.0;
> >>> acl "Users can create and delete tokens"; allow (add, delete) userattr =
> >>> "ipatokenOwner#SELFDN";)
> >>>
> >>> This is what they look like using managedBy (I have not tested this):
> >>>
> >>> aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs =
> >>> "objectclass || description || ipatokenUniqueID || ipatokenDisabled ||
> >>> ipatokenNotBefore || ipatokenNotAfter || ipatokenVendor || ipatokenModel
> >>> || ipatokenSerial || ipatokenOwner || ipatokenProtected")(version 3.0;
> >>> acl "Users can read basic token info"; allow (read, search, compare)
> >>> userattr = "ipatokenOwner#USERDN"; allow (read, search, compare)
> >>> userattr = "managedBy#USERDN";)
> >>>
> >>> aci: (targetfilter = "(objectClass=ipatokenTOTP)")(targetattrs =
> >>> "ipatokenOTPalgorithm || ipatokenOTPdigits ||
> >>> ipatokenTOTPtimeStep")(version 3.0; acl "Users can see TOTP details";
> >>> allow (read, search, compare) userattr = "ipatokenOwner#USERDN"; allow
> >>> (read, search, compare) userattr = "managedBy#USERDN";)
> >>>
> >>> aci: (targetfilter = "(objectClass=ipatokenHOTP)")(targetattrs =
> >>> "ipatokenOTPalgorithm || ipatokenOTPdigits")(version 3.0; acl "Users can
> >>> see HOTP details"; allow (read, search, compare) userattr =
> >>> "ipatokenOwner#USERDN"; allow (read, search, compare) userattr =
> >>> "managedBy#USERDN";)
> >>>
> >>> aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs =
> >>> "description || ipatokenDisabled || ipatokenNotBefore ||
> >>> ipatokenNotAfter || ipatokenVendor || ipatokenModel ||
> >>> ipatokenSerial")(version 3.0; acl "Managers can write basic token info";
> >>> allow (write) userattr = "managedBy#USERDN";)
> >>>
> >>> aci: (targetfilter = "(objectClass=ipaToken)")(version 3.0; acl
> >>> "Managers can delete tokens"; allow (delete) userattr =
> >>> "managedBy#USERDN";)
> >>>
> >>> aci: (target = "ldap:///ipatokenuniqueid=*,cn=otp,$SUFFIX")(targetfilter
> >>> = "(objectClass=ipaToken)")(version 3.0; acl "Users can create
> >>> self-managed tokens"; allow (add) userattr = "ipatokenOwner#SELFDN" and
> >>> userattr = "managedBy#SELFDN";)
> >>>
> >>> In short:
> >>> 1. Owner and manager get read, search and compare.
> >>> 2. Manager gets write (to select attributes) and delete.
> >>> 3. Users can create self-managed tokens for themselves only.
> >>>
> >>> The otptoken-add command should gain the following defaults:
> >>> 1. The owner defaults to the user adding the token.
> >>> 2. If owner == user adding token, managedBy defaults to owner.
> >>> 3. Otherwise, managedBy defaults to None.
> >>>
> >>> This means that if neither owner nor managedBy are specified, the
> >>> default is a self-owned, self-managed token. Likewise, if a different
> >>> owner is specified, no manager is assumed.
> >>>
> >>> rcrit expresses worry that ipalib's ACI parser may not handle the above
> >>> syntax. This will become clear during testing if we want this approach.
> >>>
> >>> Does this look sane?
> >>
> >> I am not entirely sure your ACI syntax is always right for the second
> >> set. and perhaps we want to duplicate ACIs in some cases (once for owner
> >> once for manager).
> >>
> >> I think the read ACIs do not need to list managedby ? Do we plan to have
> >> a manager that is another regular user but not the owner nor an admin ?
> >>
> >> In any case I prefer the sytnax that uses managedby, as it has more
> >> potential.
> >
> > Attached is a new version of the patch which implements the feature
> > using managedBy instead of ipatokenProtected. One important thing needs
> > to be said about this patch. I am not exposing managedBy in either the
> > UI, the CLI or LDAP (ACI). Do we care about this? If yes, should I
> > expose this similar to owner or as a relationship?
> 
> I would expose it, as a relationship. (Note that ipatokenowner should 
> ideally be represented as a relationship too, but the framework does not 
> support 1-to-many relationships ATM.)

So since this is a 1-to-many relationship we shouldn't expose it?

Or should I do it like owner is currently done?

> 
> Just curious, why are the ACIs divided like this:
> 
>      aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs = 
> "objectclass || description || ipatokenUniqueID || ipatokenDisabled || 
> ipatokenNotBefore || ipatokenNotAfter || ipatokenVendor || ipatokenModel 
> || ipatokenSerial || ipatokenOwner")(version 3.0; acl "Users/managers 
> can read basic token info"; allow (read, search, compare) userattr = 
> "ipatokenOwner#USERDN" or userattr = "managedBy#USERDN";)
>      aci: (targetfilter = "(objectClass=ipatokenTOTP)")(targetattrs = 
> "ipatokenOTPalgorithm || ipatokenOTPdigits || 
> ipatokenTOTPtimeStep")(version 3.0; acl "Users/managers can see TOTP 
> details"; allow (read, search, compare) userattr = 
> "ipatokenOwner#USERDN" or userattr = "managedBy#USERDN";)
>      aci: (targetfilter = "(objectClass=ipatokenHOTP)")(targetattrs = 
> "ipatokenOTPalgorithm || ipatokenOTPdigits")(version 3.0; acl 
> "Users/managers can see HOTP details"; allow (read, search, compare) 
> userattr = "ipatokenOwner#USERDN" or userattr = "managedBy#USERDN";)
> 
> IMHO you could make them less complex by dividing them like this:
> 
>      aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs = 
> "objectclass || description || ipatokenUniqueID || ipatokenDisabled || 
> ipatokenNotBefore || ipatokenNotAfter || ipatokenVendor || ipatokenModel 
> || ipatokenSerial || ipatokenOwner || ipatokenOTPalgorithm || 
> ipatokenOTPdigits || ipatokenTOTPtimeStep")(version 3.0; acl "Owner can 
> read token details"; allow (read, search, compare) userattr = 
> "ipatokenOwner#USERDN";)
>      aci: (targetfilter = "(objectClass=ipaToken)")(targetattrs = 
> "objectclass || description || ipatokenUniqueID || ipatokenDisabled || 
> ipatokenNotBefore || ipatokenNotAfter || ipatokenVendor || ipatokenModel 
> || ipatokenSerial || ipatokenOwner || ipatokenOTPalgorithm || 
> ipatokenOTPdigits || ipatokenTOTPtimeStep")(version 3.0; acl "Managers 
> can read token details"; allow (read, search, compare) userattr = 
> "managedBy#USERDN";)

The first set is organized by objectClass. The second by userattr. I
have no strong opinion on this matter, though performance is probably a
consideration. Do any DS guys want to chime in?

> Would it make sense to keep --protected as a flag in otptoken-add as a 
> shortcut for "entry_attrs['managedby'] = None"?

I can't think of a use case for this. The only use case I *can* think of
is an admin creating a non-protected token for a user.

> Would it make sense to default managedby to the current bind DN in 
> otptoken-add, even if it's not a user DN? (Do we want to allow running 
> otptoken-add by hosts/services/other non-users?)

No idea. Dmitri?

> Is orphaning a token when a user is deleted only if it is not managed by 
> any other users the intended behavior? It just seems sort of strange to 
> me, since it changes the token from unprotected to protected.

I don't think that is the behavior. We orphan the token if the owner is
not listed as a manager. If the owner is listed as a manager, we delete
the token.

Put another way, protected tokens are orphaned and unprotected tokens
are deleted.

If I didn't implement that, please point out my bug.

Nathaniel