Rooting FreeBSD , Privilege Escalation using Jails (P??????tur)

[Jamie Landeg Jones]

> Do you know if there is a way that chmod on / from within the jail could 
> be prevented easily without breaking something ? Maybe not failing but 
> falling though and return 0 for any operation with the sole argument of /.

Enforcing 700 on the jail root?

Whilst I was wrong on chmod 700 on (say) /usr/jails it is still the case
that the root directory of the jail itself (/usr/jail/jailname) has to
be 755 for non-root processeses within the jail to access the filesystem!

cheers,
Jamie