Current approaches to ACL handling

simo idra at
Mon Oct 1 13:04:21 MDT 2012

On Mon, 2012-10-01 at 13:57 -0500, Christopher R. Hertel wrote:
> On 10/01/2012 01:52 PM, Jeremy Allison wrote:
> > On Mon, Oct 01, 2012 at 02:42:51PM -0400, simo wrote:
> >> On Mon, 2012-10-01 at 13:28 -0500, Christopher R. Hertel wrote:
> >>> What are the current best practices for ACL handling?
> >>>
> >>> To my knowledge, it's using EAs to store the ACLs.  Is there any in-depth
> >>> documentation on this implementation?  Are there any other mechanisms in use?
> >>
> >> We store the Windows ACL in an EA and a matching posix ACL translation
> >> on the file, plus a sha hash of the ACL so we can be sure they are in
> >> sync.
> >>
> >> I am not aware of any other doc beyond the code.
> >
> > Well there are some SambaXP talks on it I did a while ago :-).
> >
> > Sorry.
> I'll look at the code and your talks.  Those are the kinds of pointers I needed.
> Is there any reason to even consider the possibility of thinking about 
> pondering the idea of toying with the concept of somehow using TDB (CTDB) to 
> manage ACLs, or is that not a particularly rational approach?

We had one TDB based, not really a good idea, EAs tend to move with
files, TDB databases do not. Plus you really do not want to do
enforcement of ACLs in user space. Ideally we should try to get RichACLs
in the Linux kernel so we do not need to keep pairs in EAs.


Simo Sorce
Samba Team GPL Compliance Officer <simo at>
Principal Software Engineer at Red Hat, Inc. <simo at>

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