On 01/13/2015 05:48 PM, Jeremy Allison wrote:
My understanding of Christoph's objection (although I'm sure
he can chime in himself :-) was that he wanted to see POSIX
ACLs reworked as a mapping on top of RichACLs, so that ultimately
RichACLs would be the only on-disk format of the EA.
I think that is doable, as I think any POSIX ACL can be represented
as an underlying RichACL, just not the reverse.
On of the differences is that permissions in POSIX ACLs do accumulate,
while in NFSv4 and CIFS ACLs, and therefore also richacls, they do not.
So the two models are really not interchangeable, however annoying that
may be.
For example, with the following POSIX ACL, a non-root process in group
5001 and 5002 would not be allowed to open f with O_RDWR, only with
O_RDONLY *or* O_WRONLY.
# file: f
# owner: root
# group: root
user::rw-
group::rw-
group:5001:r--
group:5002:-w-
mask::rw-
other::---
In all the other ACL models, the process would be allowed to open f with
O_RDWR.
The rationale for this behavior in POSIX ACLs was / is consistency with
how the traditional POSIX file permission model works -- determine which
of the (three) sets of permissions applies to a process, then check only
that set.
Thanks,
Andreas
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