[trasz]

>File systems aren't actually capability based (generally, in practice) because you can 'ls' and 'cd ../'. Otherwise they could be.

That's precisely how it works in FreeBSD (https://www.freebsd.org/cgi/man.cgi?capsicum).

[staticassertion]

"generally, in practice"

There's also openat on linux. My point is that the general, practiced approach is not capability based.

[trasz]

It it’s not capability based, because Linux doesn’t provide necessary functionality. FreeBSD does, as explained in the man page I’ve linked to.