#include <sys/types.h>
#include <sys/errno.h>
#include <sys/conf.h>
#include <sys/file.h>

extern int nodev();
extern int mmopen();
extern int mem_no;

#define VD_MAJOR 57
#define OE_MAJOR 70

/*
 * Known memory device minors:
 *	 0 mem		 5 vme16d16	10 vme32d32	32 sbus0
 *	 1 kmem		 6 vme24d16	11 eeprom	33 sbus1
 *	 2 null		 7 vme32d16	12 zero		34 sbus2
 *	 3 mbmem	 8 vme16d32			35 sbus3
 *	 4 mbio		 9 vme24d32
 * When security is on, /dev/null and /dev/zero are untouched,
 *  /dev/eeprom is completely disabled, and the rest are read-only.
 */

/* from: der Mouse <mouse@collatz.mcrcim.mcgill.edu> */

/*
  Here's what I found.  It's fairly close to what I posted, though I'd
  have to dig out a bugtraq archive to be sure.  This assumes you're used
  to adding device drivers; this is installed as device driver with just
  an open routine (read, write, close, etc, can all be nodev/nulldev).
  Don't forget to check that VD_MAJOR is the correct major number for
  /dev/vd in your kernel.  It also wouldn't hurt to check the "Known
  memory device minors" against what you have in /dev.
 
  Once installed, just attempt to open the newly-added device.  The
  attempt will fail, but in the process of doing so it will disable
  /dev/vd and much of the memory devices - see the comments.  I hope this
  is small enough to be read and understood in its entirety.
*/

   
static int mmopen_wrapper(dev,flag)
dev_t dev;
int flag;
{
 switch (minor(dev))
  { case 2: /* /dev/null */
    case 12: /* /dev/zero */
       break;
    case 11: /* /dev/eeprom */
       return(EPERM);
       break;
    default:
       if (flag & FWRITE) return(EPERM);
       break;
  }
 return(mmopen(dev,flag));
}

int security_open(dev,flag)
dev_t dev;
int flag;
{
	cdevsw[VD_MAJOR].d_open = nodev;
	cdevsw[VD_MAJOR].d_ioctl = nodev;
	cdevsw[OE_MAJOR].d_open = nodev;
	cdevsw[OE_MAJOR].d_ioctl = nodev;
	cdevsw[mem_no].d_open = mmopen_wrapper;
	return(ENODEV);
}