128 bit uid/gid (UUID) possible?

128 bit uid/gid (UUID) possible?

[David Mulder]

I'm messaging linux-cifs about this, since it's a relevant topic for the 
Samba team (and I'm unsure of the appropriate ml for such a discussion).

What is the possibility of increasing the uid/gid size in the kernel 
from 32bits to 128bits? If possible, how large might such a project be? 
I imagine it could be quite disruptive, but I'm not sure of all the 
implications. My question relates to providing authentication 
capabilities for integrating with oauth2 applications, such as Azure, 
where the user and group object ids are UUIDs. In SSSD and Samba, we're 
currently in discussions about what the id mappings would look like, but 
I wonder if we could take a different approach and make the kernel 
compatible with larger ids instead?

-- 
David Mulder
Labs Software Engineer, Samba
SUSE
1221 S Valley Grove Way, Suite 500
Pleasant Grove, UT 84062
(P)+1 385.208.2989
dmulder@suse.com
http://www.suse.com

Re: 128 bit uid/gid (UUID) possible?

[Linus Torvalds]

On Thu, 25 Apr 2024 at 12:17, David Mulder <dmulder@suse.com> wrote:
>
> What is the possibility of increasing the uid/gid size in the kernel from 32bits to 128bits?

Nope.

We don't have user-space interfaces for it (st_uid is 32-bit), and the
pain is not worth any theoretical gain.

                Linus

Re: 128 bit uid/gid (UUID) possible?

[David Mulder]

On 4/25/24 1:21 PM, Linus Torvalds wrote:
> On Thu, 25 Apr 2024 at 12:17, David Mulder <dmulder@suse.com> wrote:
>> What is the possibility of increasing the uid/gid size in the kernel from 32bits to 128bits?
> Nope.
>
> We don't have user-space interfaces for it (st_uid is 32-bit), and the
> pain is not worth any theoretical gain.
>
>                  Linus
Ok, thanks. I'll move forward with id mapping.

-- 
David Mulder
Labs Software Engineer, Samba
SUSE
1221 S Valley Grove Way, Suite 500
Pleasant Grove, UT 84062
(P)+1 385.208.2989
dmulder@suse.com
http://www.suse.com