xref: /freebsd-10.2-release/usr.sbin/bsdconfig/share/mustberoot.subr

if [ ! "$_MUSTBEROOT_SUBR" ]; then _MUSTBEROOT_SUBR=1
#
# Copyright (c) 2006-2012 Devin Teske
# 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 (INLUDING, 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: head/usr.sbin/bsdconfig/share/mustberoot.subr 240783 2012-09-21 19:03:25Z dteske $
#
############################################################ INCLUDES

BSDCFG_SHARE="/usr/share/bsdconfig"
. $BSDCFG_SHARE/common.subr || exit 1
f_include $BSDCFG_SHARE/dialog.subr

BSDCFG_LIBE="/usr/libexec/bsdconfig"
f_include_lang $BSDCFG_LIBE/include/messages.subr

############################################################ CONFIGURATION
# NOTE: These are not able to be overridden/inherited for security purposes.

#
# Number of tries a user gets to enter his/her password before we log the
# sudo(8) failure and exit.
#
PASSWD_TRIES=3

#
# While in SECURE mode, should authentication as `root' be allowed? Set to
# non-NULL to enable authentication as `root', otherwise disabled.
#
# WARNING: 
# Unless using a custom sudo(8) configuration, user `root' should not be
# allowed because no password is required to become `root' when already `root'
# and therefore, any value entered as password will work.
#
SECURE_ALLOW_ROOT=

#
# While in SECURE mode, should we divulge (through error message) when the
# requested authentication user does not exist? Set to non-NULL to enable,
# otherwise a non-existent user is treated like an invalid password.
#
SECURE_DIVULGE_UNKNOWN_USER=

############################################################ FUNCTIONS

# f_become_root_via_sudo
#
# If not running as root, prompt for sudo(8) credentials to become root.
# Re-execution of the current program via sudo is automatically handled.
#
# The following environment variables effect functionality:
#
# 	USE_XDIALOG   Either NULL or Non-NULL. If given a value will indicate
# 	              that Xdialog(1) should be used instead of dialog(1).
#
f_become_root_via_sudo()
{
	local msg hline size

	[ "$( id -u )" = "0" ] && return $SUCCESS

	f_have sudo || f_die 1 "$msg_must_be_root_to_execute" "$pgm"

	#
	# Check sudo(8) access before prompting for password.
	#
	:| sudo -S -v 2> /dev/null
	if [ $? -ne $SUCCESS ]; then
		#
		# sudo(8) access denied. Prompt for their password.
		#
		msg="$msg_please_enter_password"
		hline="$hline_alnum_punc_tab_enter"
		size=$( f_dialog_inputbox_size \
		        	"$DIALOG_TITLE"     \
		        	"$DIALOG_BACKTITLE" \
		        	"$msg"              \
		        	"$hline"            )

		#
		# Continue prompting until they either Cancel, succeed
		# or exceed the number of allowed failures.
		#
		local password nfailures=0 retval
		while [ $nfailures -lt $PASSWD_TRIES ]; do
			if [ "$USE_XDIALOG" ]; then
				password=$( $DIALOG \
					--title "$DIALOG_TITLE"            \
					--backtitle "$DIALOG_BACKTITLE"    \
					--hline "$hline"                   \
					--ok-label "$msg_ok"               \
					--cancel-label "$msg_cancel"       \
					--password --inputbox "$msg" $size \
					2>&1 > /dev/null )
				retval=$?

				# Catch X11-related errors
				[ $retval -eq 255 ] &&
					f_die $retval "$password"
			else
				local dialog_inputbox
				dialog_inputbox=$( $DIALOG \
					--title "$DIALOG_TITLE"         \
					--backtitle "$DIALOG_BACKTITLE" \
					--hline "$hline"                \
					--ok-label "$msg_ok"            \
					--cancel-label "$msg_cancel"    \
					--insecure                      \
					--passwordbox "$msg" $size      \
					2>&1 >&$DIALOG_TERMINAL_PASSTHRU_FD
				)
				retval=$?
				setvar DIALOG_INPUTBOX_$$ "$dialog_inputbox"
				password=$( f_dialog_inputstr )
			fi

			# Exit if the user cancelled.
			[ $retval -eq $SUCCESS ] || exit $retval

			#
			# Validate sudo(8) credentials
			#
			sudo -S -v 2> /dev/null <<-EOF
			$password
			EOF
			retval=$?
			unset password # scrub memory
			if [ $retval -eq $SUCCESS ]; then
				# Access granted...
				break
			else
				# Access denied...
				nfailures=$(( $nfailures + 1 ))

				# introduce a short delay
				if [ $nfailures -lt $PASSWD_TRIES ]; then
					f_dialog_info "$msg_sorry_try_again"
					sleep 1
				fi
			fi
		done

		#
		# If user exhausted number of allowed password tries, log
		# the security event and exit immediately.
		#
		if [ $nfailures -ge $PASSWD_TRIES ]; then
			msg=$( printf "$msg_nfailed_attempts" "$nfailures" )
			logger -p auth.notice -t sudo " " \
				"$USER : $msg" \
				"; TTY=$(tty)" \
				"; PWD=$PWD"   \
				"; USER=root"  \
				"; COMMAND=$0"
			f_die 1 "sudo: $msg"
		fi
	fi

	# Use xauth(1) to grant root the ability to use this X11/SSH session
	if [ "$USE_XDIALOG" -a "$SSH_CONNECTION" -a "$DISPLAY" ]; then
		f_have xauth || f_die 1 \
			"$msg_no_such_file_or_directory" "$pgm" "xauth"
		local HOSTNAME displaynum
		HOSTNAME=$(hostname)
		displaynum="${DISPLAY#*:}"
		xauth -f ~/.Xauthority extract - $HOSTNAME/unix:$displaynum \
			$HOSTNAME:$displaynum | sudo sh -c 'xauth -ivf \
			~root/.Xauthority merge - > /dev/null 2>&1'
	fi

	# Re-execute ourselves with sudo(8)
	if [ $ARGC -gt 0 ]; then
		exec sudo "$0" $ARGV
	else
		exec sudo "$0"
	fi
	exit $? # Never reached unless error
}

# f_authenticate_some_user
#
# Only used if running as root and requires X11 (see USE_XDIALOG below).
# Prompts the user to enter a username and password to be authenticated via
# sudo(8) to proceed.
#
# The following environment variables effect functionality:
#
# 	USE_XDIALOG   Either NULL or Non-NULL. If given a value will indicate
# 	              that Xdialog(1) should be used instead of dialog(1).
#
f_authenticate_some_user()
{
	local msg hline size width height

	f_have sudo || f_die 1 "$msg_must_be_root_to_execute" "$pgm"

	#
	# Secure-mode has been requested.
	#
 
	[ "$USE_XDIALOG" ] || f_die 1 "$msg_secure_mode_requires_x11"
	[ "$(id -u)" = "0" ] || f_die 1 "$msg_secure_mode_requires_root"

	#
	# Prompt for sudo(8) credentials.
	#

	msg="$msg_please_enter_username_password"
	hline="$hline_alnum_punc_tab_enter"
	size=$( f_xdialog_2inputsbox_size \
	        	"$DIALOG_TITLE"      \
	        	"$DIALOG_BACKTITLE"  \
	        	"$msg"               \
	        	"$field_username" "" \
	        	"$field_password" "" )
	width="${size##*[$IFS]}"
	height="${size%%[$IFS]*}"
	height=$(( $height + 2 )) # Add height for --password

	#
	# Continue prompting until they either Cancel, succeed or exceed the
	# number of allowed failures.
	#
	local user_pass nfailures=0 retval
	while [ $nfailures -lt $PASSWD_TRIES ]; do
		user_pass=$( $DIALOG \
			--title "$DIALOG_TITLE"         \
			--backtitle "$DIALOG_BACKTITLE" \
			--hline "$hline"                \
			--ok-label "$msg_ok"            \
			--cancel-label "$msg_cancel"    \
			--password --2inputsbox "$msg"  \
			$height $width                  \
			"$field_username" ""            \
			"$field_password" ""            \
			2>&1 > /dev/null )
		retval=$?

		# Catch X11-related errors
		[ $retval -eq 255 ] && f_die $retval "$user_pass"

		# Exit if the user cancelled.
		[ $retval -eq $SUCCESS ] || exit $retval

		#
		# Make sure the user exists and is non-root
		#
		local user password
		user="${user_pass%%/*}"
		password="${user_pass#*/}"
		unset user_pass # scrub memory
		if [ ! "$user" ]; then
			nfailures=$(( $nfailures + 1 ))
			f_dialog_msgbox "$msg_no_username"
			continue
		fi
		if [ ! "$SECURE_ALLOW_ROOT" ]; then
			case "$user" in
			root|toor)
				nfailures=$(( $nfailures + 1 ))
				f_dialog_msgbox "$( printf \
					"$msg_user_disallowed" "$user" )"
				continue
			esac
		fi
		if ! f_quietly id "$user"; then
			nfailures=$(( $nfailures + 1 ))
			if [ "$SECURE_DIVULGE_UNKNOWN_USER" ]; then
				f_dialog_msgbox "$( printf \
					"$msg_unknown_user" "$user" )"
			elif [ $nfailures -lt $PASSWD_TRIES ]; then
				f_dialog_info "$msg_sorry_try_again"
				sleep 1
			fi
			continue
		fi

		#
		# Validate sudo(8) credentials for given user
		#
		su -m "$user" <<-EOF
			sh <<EOS
				sudo -k
				sudo -S -v 2> /dev/null <<EOP
				$password
				EOP
			EOS
		EOF
		retval=$?
		unset user
		unset password # scrub memory

		if [ $retval -eq $SUCCESS ]; then
			# Access granted...
			break
		else
			# Access denied...
			nfailures=$(( $nfailures + 1 ))

			# introduce a short delay
			if [ $nfailures -lt $PASSWD_TRIES ]; then
				f_dialog_info "$msg_sorry_try_again"
				sleep 1
			fi
		fi
	done

	#
	# If user exhausted number of allowed password tries, log
	# the security event and exit immediately.
	#
	if [ $nfailures -ge $PASSWD_TRIES ]; then
		msg=$( printf "$msg_nfailed_attempts" "$nfailures" )
		logger -p auth.notice -t sudo " " \
			"${SUDO_USER:-$USER} : $msg" \
			"; TTY=$(tty)"               \
			"; PWD=$PWD"                 \
			"; USER=root"                \
			"; COMMAND=$0"
		f_die 1 "sudo: $message"
	fi
}

# f_mustberoot_init
#
# If not already root, make the switch to root by re-executing ourselves via
# sudo(8) using user-supplied credentials.
#
# The following environment variables effect functionality:
#
# 	SECURE        Either NULL or Non-NULL. If given a value will indicate
# 	              that (while running as root) sudo(8) authentication is
# 	              required to proceed.
#
f_mustberoot_init()
{
	if [ "$(id -u)" != "0" -a ! "$SECURE" ]; then
		f_become_root_via_sudo
	elif [ "$SECURE" ]; then
		f_authenticate_some_user
	fi
}

fi # ! $_MUSTBEROOT_SUBR