Thanks Cormander for info.
I think i misunderstood RBAC.
I thought that RBAC "linked" a file to a profile (eg:root, alice, bob,...)
Eg: Only Bob is allowed to modify Bob's file, and no one else (not even Root).
Thus i was wondering of the SU command, allowing root to switch to another profile. (and so breaking RBAC)
However, according what you said, i understood something different.
RBAC "links" a file to another one.
Eg: tripwire binary and tripwire database, who ever is the owner of both files.
Am I right ?