[RFC PATCH v2 00/41] UUID and GUID user and group ids (*_r system calls)

[Casey Schaufler]

On 10/20/2026 8:15 PM, Jan Koester wrote:
> Hi,
>
> this RFC series lets a user or group id be a UUID (RFC 9562, version 4)
> or a Microsoft GUID as well as a classic 32-bit number. Processes can run
> as such a user, files can be owned by one, and credentials, ACLs, keys,
> System V IPC, sockets, signals, audit and procfs carry the whole id.

I can't see this being acceptable for a variety of reasons, including
but not limited to performance and configuration complexity. It's a
general solution for a special case or two, and the impact is significant.

If you're willing to use a UUID and/or GUID in addition to a UID/GID
instead of in place of it you could consider implementing this as an
LSM. There are a number of issues you'd still run into there (e.g. UDS
attributes) and I can't say if the resulting behavior would be what
you're looking for. I also can't say that the security community would
necessarily be any happier with it than the general population, but if
you really want this it might be worth a shot.