"algorithmic rid base" bogus?

Andrew Bartlett abartlet at samba.org
Tue Dec 27 22:49:03 GMT 2005

On Tue, 2005-12-27 at 15:38 -0700, John H Terpstra wrote:
> On Tuesday 27 December 2005 15:22, Andrew Bartlett wrote:
> > On Tue, 2005-12-27 at 23:06 +0100, Volker Lendecke wrote:
> > > On Tue, Dec 27, 2005 at 10:49:44PM +0100, Volker Lendecke wrote:
> > > > There's a caveat that I just found out one step later however: The
> > > > samr_query_usergroups call can't return anything sensible if the groups
> > > > a user is member of are not mapped. The primary group sid is fine, this
> > > > is stored with the SAM_ACCOUNT structure, but the additional groups are
> > > > lost. This might be important as this influences the token we're
> > > > returning in the SamLogon call.  People might have (from my point of
> > > > view invalidly) set workstation security descriptors based on
> > > > non-explicitly-mapped groups. Question: Is this really an issue? If I
> > > > pursue my plan further I might have to create a compatibility option
> > > > just for this call to automagically create the group mapping entries
> > > > based on the algorithm.
> > >
> > > Replying to myself: The reason why I'm not sure this is an issue is that
> > > I don't have the slighest idea how an admin could be fooled to locally
> > > assign such a security descriptor. They are not listed with
> > > enum_domain_groups or query_dispinfo, only the mapped ones are. So none
> > > of the non-mapped groups should show up in the windows security dialogue.
> >
> > The only thought I have was possibly by copying a file (with ACLs) off
> > their file-server?
> Simple solution. If foreign domain support (non-local SIDs) is disabled we 
> refuse to copy the file across. In all other cases, we look up the name 
> attached to the SID, then create a local mapping and call the "add group 
> script" to create a UNIX user or group that is auto-mapped to the Windows 
> account (user or group). In all cases preserving the original SID.
> What am I missing here?

My scenario was about where a user has previously copied a file from the
file-server to their laptop.  The laptop is now enforcing access control
based on the ACL and the group list provided by the domain controller.  

This change could alter that group list, without altering the file on
the laptop, or it's ACL.

Alternately, the laptop could be another (windows) file-server.

Andrew Bartlett

Andrew Bartlett                                http://samba.org/~abartlet/
Authentication Developer, Samba Team           http://samba.org
Student Network Administrator, Hawker College  http://hawkerc.net
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