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

[Simo Sorce]

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.

Simo.

-- 
Simo Sorce * Red Hat, Inc * New York