Subject: sysctl securelevel -1
Index:	 src/sys/conf/param.c src/sys/sys/kern_sysctl.c src/sys/GENERIC/param.c

Description:
	By default the securelevel is set to 1 by init when going multiuser. 
	However, both common behavior in other systems, as well as explicit 
	comments in init mentions that if the operator have set securelevel 
	to -1, init will not bump it to 1.

	The problem is that it is not possible to set securelevel to -1, not 
	even in single user mode. The only component allowed to lower the 
	securelevel is init, and init only does it in two places and gives no 
	further control.

	The solution is to allow, only if securelevel is 0, root to both
	raise *and* lower the securelevel via sysctl -w kern.securelevel 

Repeat-By:
	Observation.   Going init always raises the securelevel to 1.  This
	patch implments a runtime (via sysctl) method of setting securelevel
	to -1 rather than compiling (via param.c) -1 into the kernel.
	
Fix:

	This patch (and description) are from Johnny Billquist (bqt@softjar.se).
	Thanks!

	The compile time setting of securelevel is removed in the template
	param.c file and GENERIC build directories only.   It is only 
	necessary to edit your local kernel param.c if you keep synchronized 
	with the system config templates.

	Cut where indicated and save to a file (/tmp/451 for example), change
	into the root directory and apply the patch:

	cd /
	patch -p0 < /tmp/451

	For the change to take effect a new kernel is built and installed:

	cd /sys/YOUR_KERNEL
	make
	mv /unix /ounix
	(and optionally for a networking kernel)
	mv /netnix /onetnix
	mv netnix /netnix
	reboot

	This and previous updates to 2.11BSD are available at the following
	locations:
	
	ftp://ftp.update.uu.se/pub/pdp11/2.11BSD
	https://www.tuhs.org/Archive/Distributions/UCB/2.11BSD/Patches/
	ftp://ftp.2bsd.com/2.11BSD

---------------------------cut here--------------------
*** ./usr/src/sys/conf/param.c.old	Fri Feb 14 23:22:50 1997
--- ./usr/src/sys/conf/param.c	Wed Dec 19 23:28:13 2018
***************
*** 3,9 ****
   * All rights reserved.  The Berkeley software License Agreement
   * specifies the terms and conditions for redistribution.
   *
!  *	@(#)param.c	2.2 (2.11BSD GTE) 1997/2/14
   */
  
  #include "../h/param.h"
--- 3,9 ----
   * All rights reserved.  The Berkeley software License Agreement
   * specifies the terms and conditions for redistribution.
   *
!  *	@(#)param.c	2.3 (2.11BSD) 2018/12/19
   */
  
  #include "../h/param.h"
***************
*** 71,86 ****
  struct	mount mount[NMOUNT];
  struct	buf buf[NBUF], bfreelist[BQUEUES];
  struct	bufhd bufhash[BUFHSZ];
- 
- /*
-  * Remove the ifdef/endif to run the kernel in unsecure mode even when in
-  * a multiuser state.  Normally 'init' raises the security level to 1 
-  * upon transitioning to multiuser.  Setting the securelevel to -1 prevents
-  * the secure level from being raised by init.
- */
- #ifdef	PERMANENTLY_INSECURE
- int	securelevel = -1;
- #endif
  
  #ifdef UCB_CLIST
  	u_int clstdesc = ((((btoc(NCLIST*sizeof(struct cblock)))-1) << 8) | RW);
--- 71,76 ----
*** ./usr/src/sys/sys/kern_sysctl.c.old	Fri Oct 13 23:54:52 2000
--- ./usr/src/sys/sys/kern_sysctl.c	Thu Dec 20 20:44:23 2018
***************
*** 33,39 ****
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
!  *	@(#)kern_sysctl.c	8.4.12 (2.11BSD) 2000/5/17
   */
  
  /*
--- 33,39 ----
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
!  *	@(#)kern_sysctl.c	8.4.13 (2.11BSD) 2018/12/20
   */
  
  /*
***************
*** 230,236 ****
  		if ((error = sysctl_int(oldp, oldlenp, newp, newlen, &level)) ||
  		    newp == NULL)
  			return (error);
! 		if (level < securelevel && u.u_procp->p_pid != 1)
  			return (EPERM);
  		securelevel = level;
  		return (0);
--- 230,236 ----
  		if ((error = sysctl_int(oldp, oldlenp, newp, newlen, &level)) ||
  		    newp == NULL)
  			return (error);
! 		if (level < securelevel && u.u_procp->p_pid != 1 && securelevel > 0)
  			return (EPERM);
  		securelevel = level;
  		return (0);
*** ./usr/src/sys/GENERIC/param.c.old	Fri Feb 14 23:35:37 1997
--- ./usr/src/sys/GENERIC/param.c	Thu Dec 20 21:50:02 2018
***************
*** 3,9 ****
   * All rights reserved.  The Berkeley software License Agreement
   * specifies the terms and conditions for redistribution.
   *
!  *	@(#)param.c	2.2 (2.11BSD GTE) 1997/2/14
   */
  
  #include "../h/param.h"
--- 3,9 ----
   * All rights reserved.  The Berkeley software License Agreement
   * specifies the terms and conditions for redistribution.
   *
!  *	@(#)param.c	2.3 (2.11BSD) 2018/12/19
   */
  
  #include "../h/param.h"
***************
*** 71,86 ****
  struct	mount mount[NMOUNT];
  struct	buf buf[NBUF], bfreelist[BQUEUES];
  struct	bufhd bufhash[BUFHSZ];
- 
- /*
-  * Remove the ifdef/endif to run the kernel in unsecure mode even when in
-  * a multiuser state.  Normally 'init' raises the security level to 1 
-  * upon transitioning to multiuser.  Setting the securelevel to -1 prevents
-  * the secure level from being raised by init.
- */
- #ifdef	PERMANENTLY_INSECURE
- int	securelevel = -1;
- #endif
  
  #ifdef UCB_CLIST
  	u_int clstdesc = ((((btoc(NCLIST*sizeof(struct cblock)))-1) << 8) | RW);
--- 71,76 ----
*** ./VERSION.old	Wed Mar 16 08:05:36 2016
--- ./VERSION	Sat Dec 22 08:22:27 2018
***************
*** 1,5 ****
! Current Patch Level: 450
! Date: March 16, 2016
  
  2.11 BSD
  ============
--- 1,5 ----
! Current Patch Level: 451
! Date: December 22, 2018
  
  2.11 BSD
  ============