In Unix, any user with sudo access can act as any other user using
sudo su. This invalidates any imagined privacy of local files for all other users of the same Mac. Is there any (preferably OS-level) way to work around this and give users of a multi-user Mac privacy from a potentially snooping administrator?
Edit: In my further testing it seems at least Keychain is blocked for the administrator using
sudo su. Using
security I could see the metadata -- i.e. what websites there were passwords for and titles of secure notes -- but not the contents themselves. And even if I as administrator reset the account password, the login keychain still used the old password. Also of interest, opening GUI apps using
open will try to open them for the actual user(in their GUI context, and only if it exists), not in the GUI context of the administrator.
Edit2: To get into the right frame of mind, imagine a family with one Mac. The kids have been learning about root access and are asking how they can be sure Mom & Dad can't snoop on their files. How do Mom & Dad avoid buying one Mac per kid?