Date: Sat, 5 Oct 1996 08:23:14 +0900 (JST) From: Michael Hancock <michaelh@cet.co.jp> To: Garrett Wollman <wollman@lcs.mit.edu> Cc: current@freebsd.org Subject: Re: Immutable flags (was: Re: WARNING: botched ld.so commit! :-() Message-ID: <Pine.SV4.3.93.961005075253.29020A-100000@parkplace.cet.co.jp> In-Reply-To: <9610041429.AA18858@halloran-eldar.lcs.mit.edu>
next in thread | previous in thread | raw e-mail | index | archive | help
On Fri, 4 Oct 1996, Garrett Wollman wrote:
> <<On Fri, 4 Oct 1996 09:48:10 +0900 (JST), Michael Hancock <michaelh@cet.co.jp> said:
>
> >> sysctl -w kern.securelevel=0 #in /etc/rc.local
>
> > How many deamons are running by the time you get to this line?
>
> > This isn't satisfactory, I don't want the -1 to 0 window fullstop.
>
> THERE IS NO OPERATIONAL DIFFERENCE BETWEEN -1 AND 0. Period.
There's a difference when you initialize it and this is different from
securelevel operational mode when in multi-user mode.
> The ONLY difference is in what /sbin/init does AFTER /etc/rc is finished
> executing. This is all documented in the init(8) man page; there is
> no excuse for you not reading it.
The man pages don't tell me anything about when this happens.
> -1 Permanently insecure mode - always run system in level 0 mode.
>
> 0 Insecure mode - immutable and append-only flags may be turned off.
> All devices may be read or written subject to their permissions.
Added part you deleted.
1 Secure mode - immutable and append-only flags may not be
changed; disks for mounted filesystems, /dev/mem, and /dev/kmem
are read-only.
2 Highly secure mode - same as secure mode, plus disks are always
read-only whether mounted or not. This level precludes tampering
with filesystems by unmounting them, but also inhibits running
newfs(8) while the system is multi-user.
I initialize securelevel to 0 if I want securelevel 1 as the operational
mode for multi-user.
>
> Normally, the system runs in level 0 mode while single user and in level
> 1 mode while multiuser. If the level 2 mode is desired while running
> multiuser, it can be set in the startup script /etc/rc using sysctl(8).
Normally, but not FreeBSD. It does this ...
If it is desired to run the system in level 0 mode while multiuser,
the administrator must build a kernel with the variable securelevel
defined in the file /sys/compile/MACHINE/param.c and initialize it to
-1.
Originally, 4.4BSD just didn't initialize securelevel, so it when into
.bss and was zfod'ed by the system. FreeBSD hardcodes it to permanently
insecure.
Regards,
Mike
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.SV4.3.93.961005075253.29020A-100000>