[Samba] Behavior of acl_xattr:ignore system acls = yes on a share

[Peter Milesson]

Hi folks,

Thanks everybody for your information.

I have continued my testing and have got the following to report:

Setting up the share with either root:"Domain Admins", or 
"Administrator":"Domain Admins" as owner, while setting permissions on 
the share folder to 0777 from the start, and acl_xattr:ignore system 
acls = yes on the share definition in smb.conf (I did not forget to 
restart smbd and winbind)

Then in Windows Computer management/Security I get the following list:
Owner: (root or Administrator)

    root (or Administrator)    Full Control    This folder only
    Domain Admins    Read, write & execute    This folder only
    Everyone    Read, write & execute    This folder only
    SYSTEM    Full Control    This folder only

Any change I make to the list ends with the error message "Failed to 
enumerate objects in the container. Access is denied" after clicking OK.

If I first make the basic setup of the share to my liking, without 
having acl_xattr:ignore system acls = yes active, and then reload smbd 
with acl_xattr:ignore system acls = yes, it seems to work.

It does not seem important whether the linux permissions on the share 
folder are 0770 or 0777, or linux owner on the share folder being root 
or Administrator when setting it up. I have not investigated if the 
folder permissions are important for the share later on.

Best regards,

Peter


On 31.01.2024 0:45, Bailey Allison via samba wrote:
> Just wanted to say very interesting thread! I would like to share my experience as well if that's alright.
>
> I have noticed when using the ignore system acls = yes value, when checking on the Windows side permissions it appears as the following (copying from Peter here):
>
> -Permissions list-
> root (Unix User\root)    Full Control    This folder only Domain Admins (Private\Domain Admins)    Read, write & Execute    This folder only SYSTEM    Full control    This folder only
>
> Note that the group assigned on the Linux side gets read write execute, and the user gets Full Control. What does this mean? On Windows, read write execute is not enough to modify permissions on files or folders, so anyone in Domain Admins can access but not administer permissions for the share (i.e add users or groups, modify permissions). With the above permissions the only user who can actually edit the permissions on the Windows side is root, which is most likely not a good idea. Also where root isn't (shouldn't?) be a domain user, and is a linux user this also does not help.
>
> Despite the underlying permissions being 0770 in this case, i.e user and group same on linux, they get interpreted differently on the Windows side.
>
> This could be an entirely Windows related thing, perhaps someone else can share their knowledge on this.
>
> I am assuming by changing to 0777 the idea is that anyone can modify permissions? But where's there is no entry for everyone, and Domain Admins is still getting listed as read write execute, not sure if this would work. I will check in on this. Checking in on this as I write the email, 0777 adds an entry for Everyone also as read write execute, which is not enough to modify the permissions on the Windows side.
>
> Peter, for your sake try assigning an admin account/your account as the owner user instead of root, and try modifying the permissions then to see if it works. You should see your account listed as Full Control, which should give you enough access to add and modify the permissions on Windows.
>
> Happy to be corrected if there's something I'm completely missing/am incorrect about! 😊
>
> Regards,
>
> Bailey
>
>
>> -----Original Message-----
>> From: samba<samba-bounces at lists.samba.org>  On Behalf Of Greg Sloop
>> <gregs--- via samba
>> Sent: January 30, 2024 6:33 PM
>> To:samba at lists.samba.org
>> Subject: Re: [Samba] Behavior of acl_xattr:ignore system acls = yes on a
>> share
>>
>> Perhaps everyone's clear on this - but I thought I should add this, just in case.
>> (And perhaps the clarification should be added to the wiki.) When it says
>> "Samba will ignore the standard Unix system ACL's (ugo)"
>> This is technically true. HOWEVER!
>> It only ignores the standard Unix system ACLS as it applies to SAMBA
>> permissions.
>>
>> This won't allow Samba to read files that the samba process can't read.
>> Thus, set them to 0777 so there are no restrictions at the file system level,
>> and then SAMBA will ignore the Unix ACL's for what permissions it gives to
>> *SAMBA* users, and apply them purely based on the extended acls set in
>> Windows, for example.
>>
>> (Wording that properly is not exactly easy, but hopefully that's helpful.)
>>
>> On Tue, Jan 30, 2024 at 12:24 PM Ralph Boehme via samba <
>> samba at lists.samba.org> wrote:
>>
>>> On 1/30/24 20:15, Peter Milesson via samba wrote:
>>>> *Setup shared folder*
>>>>
>>>>    * Create the folder /data/migrtest
>>>>    * Set ownership to root:"Domain Admins"
>>>>    * chmod 0770 migrtest
>>> iirc this has to be 0777, otherwise the kernel gets in your way. You
>>> only want Samba to enforce permissions so you have to get the kernel
>>> filesystem permissions our of the way by goint with 0777.
>>>
>>> -slow
>>>
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>