Re: adding plan9-like usernames to the kernel

[Casey Schaufler]

On 2/7/2018 4:38 AM, Enrico Weigelt, metux IT consult wrote:
> Hi folks,
>
>
> as part as a little research project for bringing Plan9 semantics
> to Linux, I'd like to add textual usernames. In contrast to *nix,
> Plan9 doesn't use numerical IDs, but names.
>
> Obviously that needs some internal mapping between names and ids.
>
> Should this go into struct user_namespace (where per-namespace
> uid mapping lives) or to struct cred / struct user_struct ?

Why not keep a mapping associated with your devices?

>
> The primary consumer of this username will be the /dev/caphash
> and /dev/capuse devices for switching the UID.
> (an interesting question of course is, how to allocate the
> numerical UIDs for given usernames)

You read it from /etc/passwd (or the equivalent service)
and write it to your device based list via an ioctl, or a
companion device (/dev/capset?). If no one outside your
devices is using it this would be the logical place for
the data to reside.

>
>
> --mtx
>