Create "rootless" namespace when running under root?

[deliciouslytyped]

Looking at #13941, and at the output of lsns not showing any new user namespaces (though I didn't look very hard), apparently podman does not create a rootless namespace when running as root. Is there a way to do this or would that need a feature request? (running similar to "rootless" mode as root.)

[Luap99]

AFAIK we check for CAP_SYS_ADMIN in order to create the rootless userns, so if you drop all caps it may just work.

Though I guess overall there is a fair amount of confusion in the code between checks for uid == 0 and if we use reexec userns mode so you are likely to find many weird behaviours so I would recommend against it.

[deliciouslytyped]

1. Thanks
2. This is why I would like if this was more explicitly tested for.