On Thu, 2014-02-20 at 15:46 -0500, Yassir Elley wrote:
This email proposes two changes that would allow sssd to correctly
support ACL processing on GPO objects.
In addition to various other factors, in order for a GPO to be
considered applicable to a particular computer target, the GPO
object's AD ACL must grant the "ApplyGroupPolicy" right (AGP) to the
computer (or, more likely, to a group of which the computer is a
member). By default, AD grants the AGP right to the "Authenticated
Users" group, which includes both authenticated users and computers.
While this group can be placed on AD ACLs (like other groups), it is
special in that its membership is supposed to be maintained by the
client (not by AD). Additionally, Windows admins can change this
default behavior by denying the AGP right to the "Authenticated Users"
group, and by granting the AGP right to some other security principal
(which could be a "built-in" principal).
Since there has never been a need, SSSD neither maintains an
"Authenticated Users" group membership, nor does it cache any Built-in
Groups (those whose SIDS are of the form S-1-5-32-*, such as
"Administrators", "Users", etc ) returned from LDAP. In order to
support the ACL filtering of GPOs described above, the GPO code needs
to know which Built-in Groups the computer target is a member of.
I have the following two proposals:
1. I propose that the GPO access-control code (which is executed after
a successful pam authentication) should just assume that any user or
computer is a member of the "Authenticated Users" group. This would be
local to the GPO code, and would therefore have no effect on other
Make sense for now, however going forward we will have to add this SID
to a security token of sorts if SSSD is to be used wit the Samba File
Server, so in future we may want to have an explicit "Windows Security
Context" that lists all SIDs, including this one.
2. I propose that SSSD should no longer filter out built-in groups
returned by LDAP, but should rather store them in the sysdb cache, in
the same manner as it stores other groups. This would allow the GPO
code to seamlessly include the built-in groups in its ACL processing
decision. Since we would be storing these built-in groups in the
cache, they would be visible to other SSSD components. An alternative
would be to have the GPO code interact with AD to determine the
computer's group memberships directly (without consulting the cache),
but that seems too inefficient.
Something's not right here.
Built-in groups are an inherently "local" concept in Windows, they are
not associated with domain users (you will not find built-in SIDs in the
MS-PAC or in tokenGroups replies) and are meant to have meaning only on
the local system where they are defined.
Can you give me a reference for the use of built-in groups with GPOs ?
Simo Sorce * Red Hat, Inc * New York