> есть ли защита такого уровня для BSD?

С разморозкой!

> Author: wollman <wollman@FreeBSD.org>
> Date:   Wed Aug 10 02:48:08 1994 +0000
>    If you have compiled a kernel from the latest sources, your kernel
>    security level is set to -1 by default

man securelevel

The kernel runs with five different security levels.  Any super-user
     process can raise the level, but no process can lower it.  The security
     levels are:
     -1    Permanently insecure mode - always run the system in insecure mode.
           This is the default initial value.
     0     Insecure mode - immutable and append-only flags may be turned off.
           All devices may be read or written subject to their permissions.
     1     Secure mode - the system immutable and system append-only flags may
           not be turned off; disks for mounted file systems, /dev/mem and
           /dev/kmem may not be opened for writing; /dev/io (if your platform
           has it) may not be opened at all; kernel modules (see kld(4)) may
           not be loaded or unloaded.  The kernel debugger may not be entered
           using the debug.kdb.enter sysctl.  A panic or trap cannot be forced
           using the debug.kdb.panic and other sysctl's.
 
     2     Highly secure mode - same as secure mode, plus disks may not be
           opened for writing (except by mount(2)) whether mounted or not.
           This level precludes tampering with file systems by unmounting
           them, but also inhibits running newfs(8) while the system is multi-
           user.
 
           In addition, kernel time changes are restricted to less than or
           equal to one second.  Attempts to change the time by more than this
           will log the message “Time adjustment clamped to +1 second”.
 
     3     Network secure mode - same as highly secure mode, plus IP packet
           filter rules (see ipfw(8), ipfirewall(4) and pfctl(8)) cannot be
           changed and dummynet(4) or pf(4) configuration cannot be adjusted

> sysctl -d security.bsd.suser_enabled
> security.bsd.suser_enabled: processes with uid 0 have privilege