Try to minimize places where suid programs and devices can live

by implementing the rules:

Only '/' is neither nodev nor nosuid. i.e.  it can obviously *always*
contain devices or setuid programs.

Every other mounted filesystem is nodev. If the user chooses to mount
/dev as a separate filesystem, then on the user's head be it.

The only directories that install puts suid binaries into (as of 3.2)
are:

/sbin
/usr/bin
/usr/sbin
/usr/libexec
/usr/libexec/auth
/usr/X11R6/bin

and ports and users can do who knows what to /usr/local and sub
directories thereof.

So try to ensure that only filesystems that are mounted at or above
these directories can contain suid programs. In the case of
/usr/libexec, give blanket permission for subdirectories.

Note that if *all* the above are split into separate filesystems the
install process will attempt a couple of cross-device links when
installing base32.tgz, and fail.

ok deraadt@.

1 files changed, 45 insertions, 7 deletions

diff --git a/distrib/miniroot/install.sh b/distrib/miniroot/install.sh
index 9d3f1ed452d..2eb32c69306 100644
--- a/distrib/miniroot/install.sh
+++ b/distrib/miniroot/install.sh
@@ -1,5 +1,5 @@
 #!/bin/sh
-#	$OpenBSD: install.sh,v 1.116 2002/09/24 01:26:15 krw Exp $
+#	$OpenBSD: install.sh,v 1.117 2002/09/25 12:19:12 krw Exp $
 #	$NetBSD: install.sh,v 1.5.2.8 1996/08/27 18:15:05 gwr Exp $
 #
 # Copyright (c) 1997-2002 Todd Miller, Theo de Raadt, Ken Westerback
@@ -266,12 +266,50 @@ __EOT
 		for _pp in ${_partitions[*]}; do
 			if [ "$_mp" = "${_mount_points[$_i]}" ]; then
 				echo -n "/dev/$_pp $_mp ffs rw"
-				case $_mp in
-				"/")	echo " 1 1" ;;
-				"/tmp"|"/var"|"/var/tmp"|"/usr/obj"|"/home") echo ",nosuid,nodev 1 2" ;;
-				"/usr") echo ",nodev 1 2" ;;
-				*)	echo " 1 2" ;;
-				esac
+				# Only '/' is neither nodev nor nosuid. i.e.
+				# it can obviously *always* contain devices or
+				# setuid programs.
+				#
+				# Every other mounted filesystem is nodev. If
+				# the user chooses to mount /dev as a separate
+				# filesystem, then on the user's head be it.
+				#
+				# The only directories that install puts suid
+				# binaries into (as of 3.2) are:
+				#
+				# /sbin
+				# /usr/bin
+				# /usr/sbin
+				# /usr/libexec
+				# /usr/libexec/auth
+				# /usr/X11R6/bin
+				#
+				# and ports and users can do who knows what
+				# to /usr/local and sub directories thereof.
+				#
+				# So try to ensure that only filesystems that
+				# are mounted at or above these directories
+				# can contain suid programs. In the case of
+				# /usr/libexec, give blanket permission for
+				# subdirectories.
+				if [[ $_mp == / ]]; then
+					# / can hold devices and suid programs.
+					echo " 1 1"
+				else
+					# No devices anywhere but /.
+					echo -n ",nodev"
+					case $_mp in
+					# A few directories are allowed suid.
+					/sbin|/usr)			;;
+					/usr/bin|/usr/sbin)		;;
+					/usr/libexec|/usr/libexec/*)	;;
+					/usr/local|/usr/local/*)	;;
+					/usr/X11R6|/usr/X11R6/bin)	;;
+					# But all others are not.
+					*)	echo -n ",nosuid"	;;
+					esac
+					echo " 1 2"
+				fi
 			fi
 			: $(( _i += 1 ))
 		done