mustberoot.subr revision 251242 
1if [ ! "$_MUSTBEROOT_SUBR" ]; then _MUSTBEROOT_SUBR=1
2#
3# Copyright (c) 2006-2013 Devin Teske
4# All Rights Reserved.
5#
6# Redistribution and use in source and binary forms, with or without
7# modification, are permitted provided that the following conditions
8# are met:
9# 1. Redistributions of source code must retain the above copyright
10#    notice, this list of conditions and the following disclaimer.
11# 2. Redistributions in binary form must reproduce the above copyright
12#    notice, this list of conditions and the following disclaimer in the
13#    documentation and/or other materials provided with the distribution.
14#
15# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING BUT NOT LIMITED TO, THE
17# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20# DAMAGES (INLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25# SUCH DAMAGE.
26#
27# $FreeBSD: head/usr.sbin/bsdconfig/share/mustberoot.subr 251242 2013-06-02 05:45:25Z dteske $
28#
29############################################################ INCLUDES
30
31BSDCFG_SHARE="/usr/share/bsdconfig"
32. $BSDCFG_SHARE/common.subr || exit 1
33f_dprintf "%s: loading includes..." mustberoot.subr
34f_include $BSDCFG_SHARE/dialog.subr
35
36BSDCFG_LIBE="/usr/libexec/bsdconfig"
37f_include_lang $BSDCFG_LIBE/include/messages.subr
38
39############################################################ CONFIGURATION
40# NOTE: These are not able to be overridden/inherited for security purposes.
41
42#
43# Number of tries a user gets to enter his/her password before we log the
44# sudo(8) failure and exit.
45#
46PASSWD_TRIES=3
47
48#
49# While in SECURE mode, should authentication as `root' be allowed? Set to
50# non-NULL to enable authentication as `root', otherwise disabled.
51#
52# WARNING: 
53# Unless using a custom sudo(8) configuration, user `root' should not be
54# allowed because no password is required to become `root' when already `root'
55# and therefore, any value entered as password will work.
56#
57SECURE_ALLOW_ROOT=
58
59#
60# While in SECURE mode, should we divulge (through error message) when the
61# requested authentication user does not exist? Set to non-NULL to enable,
62# otherwise a non-existent user is treated like an invalid password.
63#
64SECURE_DIVULGE_UNKNOWN_USER=
65
66############################################################ FUNCTIONS
67
68# f_become_root_via_sudo
69#
70# If not running as root, prompt for sudo(8) credentials to become root.
71# Re-execution of the current program via sudo is automatically handled.
72#
73# The following environment variables effect functionality:
74#
75# 	USE_XDIALOG   Either NULL or Non-NULL. If given a value will indicate
76# 	              that Xdialog(1) should be used instead of dialog(1).
77#
78f_become_root_via_sudo()
79{
80	local msg hline height width rows
81
82	[ "$( id -u )" = "0" ] && return $SUCCESS
83
84	f_have sudo || f_die 1 "$msg_must_be_root_to_execute" "$pgm"
85
86	#
87	# Ask the user if it's OK to become root via sudo(8) and give them
88	# the option to save this preference (by touch(1)ing a file in the
89	# user's $HOME directory).
90	#
91	local checkpath="${HOME%/}/.bsdconfig_uses_sudo"
92	if [ ! -e "$checkpath" ]; then
93		msg=$( printf "$msg_always_try_sudo_when_run_as" "$USER" )
94		local menu_list="
95			'X' '$msg_cancel_exit'
96			'1' '$msg'
97			'2' '$msg_try_sudo_only_this_once'
98		" # END-QUOTE
99		msg=$( printf "$msg_you_are_not_root_but" bsdconfig )
100		hline="$hline_arrows_tab_enter"
101		eval f_dialog_menu_size height width rows \
102		                        \"\$DIALOG_TITLE\"     \
103		                        \"\$DIALOG_BACKTITLE\" \
104		                        \"\$msg\"              \
105		                        \"\$hline\"            \
106		                        $menu_list
107
108		local mtag
109		mtag=$( eval $DIALOG \
110			--title \"\$DIALOG_TITLE\"         \
111			--backtitle \"\$DIALOG_BACKTITLE\" \
112			--hline \"\$hline\"                \
113			--ok-label \"\$msg_ok\"            \
114			--cancel-label \"\$msg_cancel\"    \
115			--menu \"\$msg\"                   \
116			$height $width $rows               \
117			$menu_list                         \
118			2>&1 >&$DIALOG_TERMINAL_PASSTHRU_FD
119		) || f_die
120		f_dialog_data_sanitize mtag
121
122		case "$mtag" in
123		X) # Cancel/Exit
124		   f_die ;;
125		1) # Always try sudo(8) when run as $user
126			local err
127			if ! err=$( touch "$checkpath" 2>&1 ); then
128				f_dialog_msgbox "$err"
129			else
130				f_show_msg "$msg_created_path" "$checkpath"
131			fi
132		esac
133	else
134		#
135		# This user has created the path signing-off on sudo(8)-use
136		# but let's still give them a short/quick/unobtrusive reminder
137		#
138		f_dialog_info "$msg_becoming_root_via_sudo"
139		[ "$USE_XDIALOG" ] || sleep 0.6
140	fi
141
142	#
143	# Check sudo(8) access before prompting for password.
144	#
145	:| sudo -S -v 2> /dev/null
146	if [ $? -ne $SUCCESS ]; then
147		#
148		# sudo(8) access denied. Prompt for their password.
149		#
150		msg="$msg_please_enter_password"
151		hline="$hline_alnum_punc_tab_enter"
152		f_dialog_inputbox_size height width \
153		                       "$DIALOG_TITLE"     \
154		                       "$DIALOG_BACKTITLE" \
155		                       "$msg"              \
156		                       "$hline"
157
158		#
159		# Continue prompting until they either Cancel, succeed
160		# or exceed the number of allowed failures.
161		#
162		local password nfailures=0 retval
163		while [ $nfailures -lt $PASSWD_TRIES ]; do
164			if [ "$USE_XDIALOG" ]; then
165				password=$( $DIALOG \
166					--title "$DIALOG_TITLE"         \
167					--backtitle "$DIALOG_BACKTITLE" \
168					--hline "$hline"                \
169					--ok-label "$msg_ok"            \
170					--cancel-label "$msg_cancel"    \
171					--password --inputbox "$msg"    \
172					$height $width                  \
173					2>&1 > /dev/null )
174				retval=$?
175
176				# Catch X11-related errors
177				[ $retval -eq 255 ] &&
178					f_die $retval "$password"
179			else
180				password=$( $DIALOG \
181					--title "$DIALOG_TITLE"         \
182					--backtitle "$DIALOG_BACKTITLE" \
183					--hline "$hline"                \
184					--ok-label "$msg_ok"            \
185					--cancel-label "$msg_cancel"    \
186					--insecure                      \
187					--passwordbox "$msg"            \
188					$height $width                  \
189					2>&1 >&$DIALOG_TERMINAL_PASSTHRU_FD
190				) || exit $?
191			fi
192			debug= f_dialog_line_sanitize password
193
194			#
195			# Validate sudo(8) credentials
196			#
197			sudo -S -v 2> /dev/null <<-EOF
198			$password
199			EOF
200			retval=$?
201			unset password # scrub memory
202			if [ $retval -eq $SUCCESS ]; then
203				# Access granted...
204				break
205			else
206				# Access denied...
207				nfailures=$(( $nfailures + 1 ))
208
209				# introduce a short delay
210				if [ $nfailures -lt $PASSWD_TRIES ]; then
211					f_dialog_info "$msg_sorry_try_again"
212					sleep 1
213				fi
214			fi
215		done
216
217		#
218		# If user exhausted number of allowed password tries, log
219		# the security event and exit immediately.
220		#
221		if [ $nfailures -ge $PASSWD_TRIES ]; then
222			msg=$( printf "$msg_nfailed_attempts" "$nfailures" )
223			logger -p auth.notice -t sudo " " \
224				"$USER : $msg" \
225				"; TTY=$(tty)" \
226				"; PWD=$PWD"   \
227				"; USER=root"  \
228				"; COMMAND=$0"
229			f_die 1 "sudo: $msg"
230		fi
231	fi
232
233	# Use xauth(1) to grant root the ability to use this X11/SSH session
234	if [ "$USE_XDIALOG" -a "$SSH_CONNECTION" -a "$DISPLAY" ]; then
235		f_have xauth || f_die 1 \
236			"$msg_no_such_file_or_directory" "$pgm" "xauth"
237		local HOSTNAME displaynum
238		HOSTNAME=$(hostname)
239		displaynum="${DISPLAY#*:}"
240		xauth -f ~/.Xauthority extract - $HOSTNAME/unix:$displaynum \
241			$HOSTNAME:$displaynum | sudo sh -c 'xauth -ivf \
242			~root/.Xauthority merge - > /dev/null 2>&1'
243	fi
244
245	# Re-execute ourselves with sudo(8)
246	f_dprintf "%s: Becoming root via sudo(8)..." mustberoot.subr
247	if [ $ARGC -gt 0 ]; then
248		exec sudo "$0" $ARGV
249	else
250		exec sudo "$0"
251	fi
252	exit $? # Never reached unless error
253}
254
255# f_authenticate_some_user
256#
257# Only used if running as root and requires X11 (see USE_XDIALOG below).
258# Prompts the user to enter a username and password to be authenticated via
259# sudo(8) to proceed.
260#
261# The following environment variables effect functionality:
262#
263# 	USE_XDIALOG   Either NULL or Non-NULL. If given a value will indicate
264# 	              that Xdialog(1) should be used instead of dialog(1).
265#
266f_authenticate_some_user()
267{
268	local msg hline height width
269
270	f_have sudo || f_die 1 "$msg_must_be_root_to_execute" "$pgm"
271
272	#
273	# Secure-mode has been requested.
274	#
275
276	[ "$USE_XDIALOG" ] || f_die 1 "$msg_secure_mode_requires_x11"
277	[ "$(id -u)" = "0" ] || f_die 1 "$msg_secure_mode_requires_root"
278
279	#
280	# Prompt for sudo(8) credentials.
281	#
282
283	msg="$msg_please_enter_username_password"
284	hline="$hline_alnum_punc_tab_enter"
285	f_xdialog_2inputsbox_size height width \
286	                          "$DIALOG_TITLE"      \
287	                          "$DIALOG_BACKTITLE"  \
288	                          "$msg"               \
289	                          "$field_username" "" \
290	                          "$field_password" ""
291	height=$(( $height + 2 )) # Add height for --password
292
293	#
294	# Continue prompting until they either Cancel, succeed or exceed the
295	# number of allowed failures.
296	#
297	local user_pass nfailures=0 retval
298	while [ $nfailures -lt $PASSWD_TRIES ]; do
299		user_pass=$( $DIALOG \
300			--title "$DIALOG_TITLE"         \
301			--backtitle "$DIALOG_BACKTITLE" \
302			--hline "$hline"                \
303			--ok-label "$msg_ok"            \
304			--cancel-label "$msg_cancel"    \
305			--password --2inputsbox "$msg"  \
306			$height $width                  \
307			"$field_username" ""            \
308			"$field_password" ""            \
309			2>&1 > /dev/null )
310		retval=$?
311
312		# Catch X11-related errors
313		[ $retval -eq 255 ] && f_die $retval "$user_pass"
314
315		# Exit if the user cancelled.
316		[ $retval -eq $SUCCESS ] || exit $retval
317
318		#
319		# Make sure the user exists and is non-root
320		#
321		local user password
322		user="${user_pass%%/*}"
323		password="${user_pass#*/}"
324		unset user_pass # scrub memory
325		if [ ! "$user" ]; then
326			nfailures=$(( $nfailures + 1 ))
327			f_dialog_msgbox "$msg_no_username"
328			continue
329		fi
330		if [ ! "$SECURE_ALLOW_ROOT" ]; then
331			case "$user" in
332			root|toor)
333				nfailures=$(( $nfailures + 1 ))
334				f_show_msg "$msg_user_disallowed" "$user"
335				continue
336			esac
337		fi
338		if ! f_quietly id "$user"; then
339			nfailures=$(( $nfailures + 1 ))
340			if [ "$SECURE_DIVULGE_UNKNOWN_USER" ]; then
341				f_show_msg "$msg_unknown_user" "$user"
342			elif [ $nfailures -lt $PASSWD_TRIES ]; then
343				f_dialog_info "$msg_sorry_try_again"
344				sleep 1
345			fi
346			continue
347		fi
348
349		#
350		# Validate sudo(8) credentials for given user
351		#
352		su -m "$user" <<-EOF
353			sh <<EOS
354				sudo -k
355				sudo -S -v 2> /dev/null <<EOP
356				$password
357				EOP
358			EOS
359		EOF
360		retval=$?
361		unset user
362		unset password # scrub memory
363
364		if [ $retval -eq $SUCCESS ]; then
365			# Access granted...
366			break
367		else
368			# Access denied...
369			nfailures=$(( $nfailures + 1 ))
370
371			# introduce a short delay
372			if [ $nfailures -lt $PASSWD_TRIES ]; then
373				f_dialog_info "$msg_sorry_try_again"
374				sleep 1
375			fi
376		fi
377	done
378
379	#
380	# If user exhausted number of allowed password tries, log
381	# the security event and exit immediately.
382	#
383	if [ $nfailures -ge $PASSWD_TRIES ]; then
384		msg=$( printf "$msg_nfailed_attempts" "$nfailures" )
385		logger -p auth.notice -t sudo " " \
386			"${SUDO_USER:-$USER} : $msg" \
387			"; TTY=$(tty)"               \
388			"; PWD=$PWD"                 \
389			"; USER=root"                \
390			"; COMMAND=$0"
391		f_die 1 "sudo: $message"
392	fi
393}
394
395# f_mustberoot_init
396#
397# If not already root, make the switch to root by re-executing ourselves via
398# sudo(8) using user-supplied credentials.
399#
400# The following environment variables effect functionality:
401#
402# 	SECURE        Either NULL or Non-NULL. If given a value will indicate
403# 	              that (while running as root) sudo(8) authentication is
404# 	              required to proceed.
405#
406f_mustberoot_init()
407{
408	if [ "$(id -u)" != "0" -a ! "$SECURE" ]; then
409		f_become_root_via_sudo
410	elif [ "$SECURE" ]; then
411		f_authenticate_some_user
412	fi
413}
414
415############################################################ MAIN
416
417f_dprintf "%s: Successfully loaded." mustberoot.subr
418
419fi # ! $_MUSTBEROOT_SUBR
420