Add an (off by default) check for negative permissions (where the

group on a object has less permissions that everyone).  These
permissions will not work reliably over NFS if you have more than
14 supplemental groups and are usually not what you mean.

MFC after:	1 week

etc/defaults/periodic.conf

@@ -160,6 +160,9 @@ daily_status_security_diff_flags="-b -u"		# flags for diff output
 # 100.chksetuid
 daily_status_security_chksetuid_enable="YES"
 
+# 110.neggrpperm
+daily_status_security_neggrpperm_enable="NO"
+
 # 200.chkmounts
 daily_status_security_chkmounts_enable="YES"
 #daily_status_security_chkmounts_ignore="^amd:"		# Don't check matching

etc/periodic/security/110.neggrpperm

@@ -0,0 +1,54 @@
+#!/bin/sh -
+#
+# Copyright (c) 2001  The FreeBSD Project
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+# SUCH DAMAGE.
+#
+# $FreeBSD$
+#
+
+# If there is a global system configuration file, suck it in.
+#
+if [ -r /etc/defaults/periodic.conf ]
+then
+    . /etc/defaults/periodic.conf
+    source_periodic_confs
+fi
+
+rc=0
+
+case "$daily_status_security_neggrpperm_enable" in
+    [Yy][Ee][Ss])
+	echo ""
+	echo 'Checking negative group permissions:'
+	MP=`mount -t ufs,zfs | awk '$0 !~ /no(suid|exec)/ { print $3 }'`
+	n=$(find -sx $MP /dev/null -type f \
+	    \( \( ! -perm +010 -and -perm +001 \) -or \
+	    \( ! -perm +020 -and -perm +002 \) -or \
+	    \( ! -perm +040 -and -perm +004 \) \) \
+	    -exec ls -liTd \{\} \+ | tee /dev/stderr | wc -l)
+	[ $n -gt 0 ] && rc=1 || rc=0
+	;;
+esac
+
+exit $rc

etc/periodic/security/Makefile

@@ -3,6 +3,7 @@
 .include <bsd.own.mk>
 
 FILES=	100.chksetuid \
+	110.neggrpperm \
 	200.chkmounts \
 	300.chkuid0 \
 	400.passwdless \

share/man/man5/periodic.conf.5

@@ -482,6 +482,14 @@ Set to
 .Dq Li YES
 to compare the modes and modification times of setuid executables with
 the previous day's values.
+.It Va daily_status_security_neggrpperm_enable
+.Pq Vt bool
+Set to
+.Dq Li YES
+to check for files where the group of a file has less permissions than
+the world at large.
+When users are in more than 14 supplemental groups these negative
+permissions may not be enforced via NFS shares.
 .It Va daily_status_security_chkmounts_enable
 .Pq Vt bool
 Set to