- /dev/mem: only allow access to physical RAM

- /dev/kmem: disallow access to devices

This is designed to protect device registers from being corrupted
accidentally by "innocent" mem/kmem grovellers.

sys/arch/hp300/hp300/mem.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: mem.c,v 1.14 1997/02/02 07:59:41 thorpej Exp $	*/
+/*	$NetBSD: mem.c,v 1.15 1997/03/15 23:30:12 thorpej Exp $	*/
 
 /*
  * Copyright (c) 1988 University of Utah.
@@ -56,6 +56,7 @@
 #include <vm/vm.h>
 
 extern u_int lowram;
+extern char *extiobase;
 static caddr_t devzeropage;
 
 /*ARGSUSED*/
@@ -116,13 +117,15 @@ mmrw(dev, uio, flags)
 /* minor device 0 is physical memory */
 		case 0:
 			v = uio->uio_offset;
-#ifndef DEBUG
-			/* allow reads only in RAM (except for DEBUG) */
+
+			/*
+			 * Only allow reads in physical RAM.
+			 */
 			if (v >= 0xFFFFFFFC || v < lowram) {
 				error = EFAULT;
 				goto unlock;
 			}
-#endif
+
 			pmap_enter(pmap_kernel(), (vm_offset_t)vmmap,
 			    trunc_page(v), uio->uio_rw == UIO_READ ?
 			    VM_PROT_READ : VM_PROT_WRITE, TRUE);
@@ -140,6 +143,17 @@ mmrw(dev, uio, flags)
 			if (!kernacc((caddr_t)v, c,
 			    uio->uio_rw == UIO_READ ? B_READ : B_WRITE))
 				return (EFAULT);
+
+			/*
+			 * Don't allow reading intio or dio
+			 * device space.  This could lead to
+			 * corruption of device registers.
+			 */
+			if (ISIIOVA(v) ||
+			    ((caddr_t)v >= extiobase &&
+			    (caddr_t)v < (extiobase + (EIOMAPSIZE * NBPG))))
+				return (EFAULT);
+
 			error = uiomove((caddr_t)v, c, uio);
 			continue;
 
@@ -158,19 +172,11 @@ mmrw(dev, uio, flags)
 			/*
 			 * On the first call, allocate and zero a page
 			 * of memory for use with /dev/zero.
-			 *
-			 * XXX on the hp300 we already know where there
-			 * is a global zeroed page, the null segment table.
 			 */
 			if (devzeropage == NULL) {
-#if CLBYTES == NBPG
-				extern caddr_t Segtabzero;
-				devzeropage = Segtabzero;
-#else
 				devzeropage = (caddr_t)
 				    malloc(CLBYTES, M_TEMP, M_WAITOK);
 				bzero(devzeropage, CLBYTES);
-#endif
 			}
 			c = min(iov->iov_len, CLBYTES);
 			error = uiomove(devzeropage, c, uio);
@@ -210,11 +216,9 @@ mmmmap(dev, off, prot)
 	 */
 	if (minor(dev) != 0)
 		return (-1);
+
 	/*
 	 * Allow access only in RAM.
-	 *
-	 * XXX could be extended to allow access to IO space but must
-	 * be very careful.
 	 */
 	if ((unsigned)off < lowram || (unsigned)off >= 0xFFFFFFFC)
 		return (-1);