Re: /bin/ids is setuid root, why ?

[Roland McGrath]

ids needs to be root to use pid2task on PIDs owned by other users.  It does
that so it can be trusted to query tasks directly for what auth port they
are using.  This is what ids does different from what using ps would do--it
gets the auth port rather than the proc server's idea of the associated IDs.

If ids were not setuid, you could not use it on other users' processes.
But since normally the information of what IDs a process has is not
considered private, installing it setuid makes that information visible to all.