1 Copyright (c) 1994-1996, 1998-2005, 2007-2012
2 Todd C. Miller <Todd.Miller@courtesan.com>
4 Permission to use, copy, modify, and distribute this software for any
5 purpose with or without fee is hereby granted, provided that the above
6 copyright notice and this permission notice appear in all copies.
8 THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
17 Sponsored in part by the Defense Advanced Research Projects
18 Agency (DARPA) and Air Force Research Laboratory, Air Force
19 Materiel Command, USAF, under agreement number F39502-99-1-0512.
25 sudoers - default sudo security policy module
29 The I<sudoers> policy module determines a user's B<sudo> privileges.
30 It is the default B<sudo> policy plugin. The policy is driven by
31 the F<@sysconfdir@/sudoers> file or, optionally in LDAP. The policy
32 format is described in detail in the L<"SUDOERS FILE FORMAT">
33 section. For information on storing I<sudoers> policy information
34 in LDAP, please see L<sudoers.ldap(5)>.
36 =head2 Authentication and Logging
38 The I<sudoers> security policy requires that most users authenticate
39 themselves before they can use B<sudo>. A password is not required
40 if the invoking user is root, if the target user is the same as the
41 invoking user, or if the policy has disabled authentication for the
42 user or command. Unlike L<su(1)>, when I<sudoers> requires
43 authentication, it validates the invoking user's credentials, not
44 the target user's (or root's) credentials. This can be changed via
45 the I<rootpw>, I<targetpw> and I<runaspw> flags, described later.
47 If a user who is not listed in the policy tries to run a command
48 via B<sudo>, mail is sent to the proper authorities. The address
49 used for such mail is configurable via the I<mailto> Defaults entry
50 (described later) and defaults to C<@mailto@>.
52 Note that mail will not be sent if an unauthorized user tries to
53 run B<sudo> with the B<-l> or B<-v> option. This allows users to
54 determine for themselves whether or not they are allowed to use
57 If B<sudo> is run by root and the C<SUDO_USER> environment variable
58 is set, the I<sudoers> policy will use this value to determine who
59 the actual user is. This can be used by a user to log commands
60 through sudo even when a root shell has been invoked. It also
61 allows the B<-e> option to remain useful even when invoked via a
62 sudo-run script or program. Note, however, that the I<sudoers>
63 lookup is still done for root, not the user specified by C<SUDO_USER>.
65 I<sudoers> uses time stamp files for credential caching. Once a
66 user has been authenticated, a time stamp is updated and the user
67 may then use sudo without a password for a short period of time
68 (C<@timeout@> minutes unless overridden by the I<timeout> option.
69 By default, I<sudoers> uses a tty-based time stamp which means that
70 there is a separate time stamp for each of a user's login sessions.
71 The I<tty_tickets> option can be disabled to force the use of a
72 single time stamp for all of a user's sessions.
74 I<sudoers> can log both successful and unsuccessful attempts (as well
75 as errors) to syslog(3), a log file, or both. By default, I<sudoers>
76 will log via syslog(3) but this is changeable via the I<syslog>
77 and I<logfile> Defaults settings.
79 I<sudoers> also supports logging a command's input and output
80 streams. I/O logging is not on by default but can be enabled using
81 the I<log_input> and I<log_output> Defaults flags as well as the
82 C<LOG_INPUT> and C<LOG_OUTPUT> command tags.
84 =head2 Command Environment
86 Since environment variables can influence program behavior, I<sudoers>
87 provides a means to restrict which variables from the user's
88 environment are inherited by the command to be run. There are two
89 distinct ways I<sudoers> can deal with environment variables.
91 By default, the I<env_reset> option is enabled. This causes commands
92 to be executed with a minimal environment containing the C<TERM>,
93 C<PATH>, C<HOME>, C<MAIL>, C<SHELL>, C<LOGNAME>, C<USER>, C<USERNAME>
94 and C<SUDO_*> variables in addition to variables from the
95 invoking process permitted by the I<env_check> and I<env_keep>
96 options. This is effectively a whitelist for environment variables.
98 If, however, the I<env_reset> option is disabled, any variables not
99 explicitly denied by the I<env_check> and I<env_delete> options are
100 inherited from the invoking process. In this case, I<env_check>
101 and I<env_delete> behave like a blacklist. Since it is not possible
102 to blacklist all potentially dangerous environment variables, use
103 of the default I<env_reset> behavior is encouraged.
105 In all cases, environment variables with a value beginning with
106 C<()> are removed as they could be interpreted as B<bash> functions.
107 The list of environment variables that B<sudo> allows or denies is
108 contained in the output of C<sudo -V> when run as root.
110 Note that the dynamic linker on most operating systems will remove
111 variables that can control dynamic linking from the environment of
112 setuid executables, including B<sudo>. Depending on the operating
113 system this may include C<_RLD*>, C<DYLD_*>, C<LD_*>, C<LDR_*>,
114 C<LIBPATH>, C<SHLIB_PATH>, and others. These type of variables are
115 removed from the environment before B<sudo> even begins execution
116 and, as such, it is not possible for B<sudo> to preserve them.
118 As a special case, if B<sudo>'s B<-i> option (initial login) is
119 specified, I<sudoers> will initialize the environment regardless
120 of the value of I<env_reset>. The I<DISPLAY>, I<PATH> and I<TERM>
121 variables remain unchanged; I<HOME>, I<MAIL>, I<SHELL>, I<USER>,
122 and I<LOGNAME> are set based on the target user. On Linux and AIX
123 systems the contents of F</etc/environment> are also included. All
124 other environment variables are removed.
126 Lastly, if the I<env_file> option is defined, any variables present
127 in that file will be set to their specified values.
129 =head1 SUDOERS FILE FORMAT
131 The I<sudoers> file is composed of two types of entries: aliases
132 (basically variables) and user specifications (which specify who
135 When multiple entries match for a user, they are applied in order.
136 Where there are multiple matches, the last match is used (which is
137 not necessarily the most specific match).
139 The I<sudoers> grammar will be described below in Extended Backus-Naur
140 Form (EBNF). Don't despair if you don't know what EBNF is; it is
141 fairly simple, and the definitions below are annotated.
143 =head2 Quick guide to EBNF
145 EBNF is a concise and exact way of describing the grammar of a language.
146 Each EBNF definition is made up of I<production rules>. E.g.,
148 symbol ::= definition | alternate1 | alternate2 ...
150 Each I<production rule> references others and thus makes up a
151 grammar for the language. EBNF also contains the following
152 operators, which many readers will recognize from regular
153 expressions. Do not, however, confuse them with "wildcard"
154 characters, which have different meanings.
160 Means that the preceding symbol (or group of symbols) is optional.
161 That is, it may appear once or not at all.
165 Means that the preceding symbol (or group of symbols) may appear
170 Means that the preceding symbol (or group of symbols) may appear
175 Parentheses may be used to group symbols together. For clarity,
176 we will use single quotes ('') to designate what is a verbatim character
177 string (as opposed to a symbol name).
181 There are four kinds of aliases: C<User_Alias>, C<Runas_Alias>,
182 C<Host_Alias> and C<Cmnd_Alias>.
184 Alias ::= 'User_Alias' User_Alias (':' User_Alias)* |
185 'Runas_Alias' Runas_Alias (':' Runas_Alias)* |
186 'Host_Alias' Host_Alias (':' Host_Alias)* |
187 'Cmnd_Alias' Cmnd_Alias (':' Cmnd_Alias)*
189 User_Alias ::= NAME '=' User_List
191 Runas_Alias ::= NAME '=' Runas_List
193 Host_Alias ::= NAME '=' Host_List
195 Cmnd_Alias ::= NAME '=' Cmnd_List
197 NAME ::= [A-Z]([A-Z][0-9]_)*
199 Each I<alias> definition is of the form
201 Alias_Type NAME = item1, item2, ...
203 where I<Alias_Type> is one of C<User_Alias>, C<Runas_Alias>, C<Host_Alias>,
204 or C<Cmnd_Alias>. A C<NAME> is a string of uppercase letters, numbers,
205 and underscore characters ('_'). A C<NAME> B<must> start with an
206 uppercase letter. It is possible to put several alias definitions
207 of the same type on a single line, joined by a colon (':'). E.g.,
209 Alias_Type NAME = item1, item2, item3 : NAME = item4, item5
211 The definitions of what constitutes a valid I<alias> member follow.
216 User ::= '!'* user name |
221 '!'* %:nonunix_group |
222 '!'* %:#nonunix_gid |
225 A C<User_List> is made up of one or more user names, user ids
226 (prefixed with '#'), system group names and ids (prefixed with '%'
227 and '%#' respectively), netgroups (prefixed with '+'), non-Unix
228 group names and IDs (prefixed with '%:' and '%:#' respectively) and
229 C<User_Alias>es. Each list item may be prefixed with zero or more
230 '!' operators. An odd number of '!' operators negate the value of
231 the item; an even number just cancel each other out.
233 A C<user name>, C<uid>, C<group>, C<gid>, C<netgroup>, C<nonunix_group>
234 or C<nonunix_gid> may be enclosed in double quotes to avoid the
235 need for escaping special characters. Alternately, special characters
236 may be specified in escaped hex mode, e.g. \x20 for space. When
237 using double quotes, any prefix characters must be included inside
240 The actual C<nonunix_group> and C<nonunix_gid> syntax depends on
241 the underlying group provider plugin (see the I<group_plugin>
242 description below). For instance, the QAS AD plugin supports the
249 Group in the same domain: "Group Name"
253 Group in any domain: "Group Name@FULLY.QUALIFIED.DOMAIN"
257 Group SID: "S-1-2-34-5678901234-5678901234-5678901234-567"
261 Note that quotes around group names are optional. Unquoted strings
262 must use a backslash (\) to escape spaces and special characters.
263 See L<"Other special characters and reserved words"> for a list of
264 characters that need to be escaped.
266 Runas_List ::= Runas_Member |
267 Runas_Member ',' Runas_List
269 Runas_Member ::= '!'* user name |
273 '!'* %:nonunix_group |
274 '!'* %:#nonunix_gid |
278 A C<Runas_List> is similar to a C<User_List> except that instead
279 of C<User_Alias>es it can contain C<Runas_Alias>es. Note that
280 user names and groups are matched as strings. In other words, two
281 users (groups) with the same uid (gid) are considered to be distinct.
282 If you wish to match all user names with the same uid (e.g.E<nbsp>root
283 and toor), you can use a uid instead (#0 in the example given).
288 Host ::= '!'* host name |
290 '!'* network(/netmask)? |
294 A C<Host_List> is made up of one or more host names, IP addresses,
295 network numbers, netgroups (prefixed with '+') and other aliases.
296 Again, the value of an item may be negated with the '!' operator.
297 If you do not specify a netmask along with the network number,
298 B<sudo> will query each of the local host's network interfaces and,
299 if the network number corresponds to one of the hosts's network
300 interfaces, the corresponding netmask will be used. The netmask
301 may be specified either in standard IP address notation
302 (e.g.E<nbsp>255.255.255.0 or ffff:ffff:ffff:ffff::),
303 or CIDR notation (number of bits, e.g.E<nbsp>24 or 64). A host name may
304 include shell-style wildcards (see the L<Wildcards> section below),
305 but unless the C<host name> command on your machine returns the fully
306 qualified host name, you'll need to use the I<fqdn> option for
307 wildcards to be useful. Note B<sudo> only inspects actual network
308 interfaces; this means that IP address 127.0.0.1 (localhost) will
309 never match. Also, the host name "localhost" will only match if
310 that is the actual host name, which is usually only the case for
311 non-networked systems.
316 commandname ::= file name |
320 Cmnd ::= '!'* commandname |
325 A C<Cmnd_List> is a list of one or more commandnames, directories, and other
326 aliases. A commandname is a fully qualified file name which may include
327 shell-style wildcards (see the L<Wildcards> section below). A simple
328 file name allows the user to run the command with any arguments he/she
329 wishes. However, you may also specify command line arguments (including
330 wildcards). Alternately, you can specify C<""> to indicate that the command
331 may only be run B<without> command line arguments. A directory is a
332 fully qualified path name ending in a '/'. When you specify a directory
333 in a C<Cmnd_List>, the user will be able to run any file within that directory
334 (but not in any subdirectories therein).
336 If a C<Cmnd> has associated command line arguments, then the arguments
337 in the C<Cmnd> must match exactly those given by the user on the command line
338 (or match the wildcards if there are any). Note that the following
339 characters must be escaped with a '\' if they are used in command
340 arguments: ',', ':', '=', '\'. The special command C<"sudoedit">
341 is used to permit a user to run B<sudo> with the B<-e> option (or
342 as B<sudoedit>). It may take command line arguments just as
343 a normal command does.
347 Certain configuration options may be changed from their default
348 values at runtime via one or more C<Default_Entry> lines. These
349 may affect all users on any host, all users on a specific host, a
350 specific user, a specific command, or commands being run as a specific user.
351 Note that per-command entries may not include command line arguments.
352 If you need to specify arguments, define a C<Cmnd_Alias> and reference
355 Default_Type ::= 'Defaults' |
356 'Defaults' '@' Host_List |
357 'Defaults' ':' User_List |
358 'Defaults' '!' Cmnd_List |
359 'Defaults' '>' Runas_List
361 Default_Entry ::= Default_Type Parameter_List
363 Parameter_List ::= Parameter |
364 Parameter ',' Parameter_List
366 Parameter ::= Parameter '=' Value |
367 Parameter '+=' Value |
368 Parameter '-=' Value |
371 Parameters may be B<flags>, B<integer> values, B<strings>, or B<lists>.
372 Flags are implicitly boolean and can be turned off via the '!'
373 operator. Some integer, string and list parameters may also be
374 used in a boolean context to disable them. Values may be enclosed
375 in double quotes (C<">) when they contain multiple words. Special
376 characters may be escaped with a backslash (C<\>).
378 Lists have two additional assignment operators, C<+=> and C<-=>.
379 These operators are used to add to and delete from a list respectively.
380 It is not an error to use the C<-=> operator to remove an element
381 that does not exist in a list.
383 Defaults entries are parsed in the following order: generic, host
384 and user Defaults first, then runas Defaults and finally command
387 See L<"SUDOERS OPTIONS"> for a list of supported Defaults parameters.
389 =head2 User Specification
391 User_Spec ::= User_List Host_List '=' Cmnd_Spec_List \
392 (':' Host_List '=' Cmnd_Spec_List)*
394 Cmnd_Spec_List ::= Cmnd_Spec |
395 Cmnd_Spec ',' Cmnd_Spec_List
397 Cmnd_Spec ::= Runas_Spec? SELinux_Spec? Tag_Spec* Cmnd
399 Runas_Spec ::= '(' Runas_List? (':' Runas_List)? ')'
401 SELinux_Spec ::= ('ROLE=role' | 'TYPE=type')
403 Tag_Spec ::= ('NOPASSWD:' | 'PASSWD:' | 'NOEXEC:' | 'EXEC:' |
404 'SETENV:' | 'NOSETENV:' | 'LOG_INPUT:' | 'NOLOG_INPUT:' |
405 'LOG_OUTPUT:' | 'NOLOG_OUTPUT:')
407 A B<user specification> determines which commands a user may run
408 (and as what user) on specified hosts. By default, commands are
409 run as B<root>, but this can be changed on a per-command basis.
411 The basic structure of a user specification is `who where = (as_whom)
412 what'. Let's break that down into its constituent parts:
416 A C<Runas_Spec> determines the user and/or the group that a command
417 may be run as. A fully-specified C<Runas_Spec> consists of two
418 C<Runas_List>s (as defined above) separated by a colon (':') and
419 enclosed in a set of parentheses. The first C<Runas_List> indicates
420 which users the command may be run as via B<sudo>'s B<-u> option.
421 The second defines a list of groups that can be specified via
422 B<sudo>'s B<-g> option. If both C<Runas_List>s are specified, the
423 command may be run with any combination of users and groups listed
424 in their respective C<Runas_List>s. If only the first is specified,
425 the command may be run as any user in the list but no B<-g> option
426 may be specified. If the first C<Runas_List> is empty but the
427 second is specified, the command may be run as the invoking user
428 with the group set to any listed in the C<Runas_List>. If no
429 C<Runas_Spec> is specified the command may be run as B<root> and
430 no group may be specified.
432 A C<Runas_Spec> sets the default for the commands that follow it.
433 What this means is that for the entry:
435 dgb boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm
437 The user B<dgb> may run F</bin/ls>, F</bin/kill>, and
438 F</usr/bin/lprm> -- but only as B<operator>. E.g.,
440 $ sudo -u operator /bin/ls
442 It is also possible to override a C<Runas_Spec> later on in an
443 entry. If we modify the entry like so:
445 dgb boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm
447 Then user B<dgb> is now allowed to run F</bin/ls> as B<operator>,
448 but F</bin/kill> and F</usr/bin/lprm> as B<root>.
450 We can extend this to allow B<dgb> to run C</bin/ls> with either
451 the user or group set to B<operator>:
453 dgb boulder = (operator : operator) /bin/ls, (root) /bin/kill, \
456 Note that while the group portion of the C<Runas_Spec> permits the
457 user to run as command with that group, it does not force the user
458 to do so. If no group is specified on the command line, the command
459 will run with the group listed in the target user's password database
460 entry. The following would all be permitted by the sudoers entry above:
462 $ sudo -u operator /bin/ls
463 $ sudo -u operator -g operator /bin/ls
464 $ sudo -g operator /bin/ls
466 In the following example, user B<tcm> may run commands that access
467 a modem device file with the dialer group.
469 tcm boulder = (:dialer) /usr/bin/tip, /usr/bin/cu, \
470 /usr/local/bin/minicom
472 Note that in this example only the group will be set, the command
473 still runs as user B<tcm>. E.g.
475 $ sudo -g dialer /usr/bin/cu
477 Multiple users and groups may be present in a C<Runas_Spec>, in
478 which case the user may select any combination of users and groups
479 via the B<-u> and B<-g> options. In this example:
481 alan ALL = (root, bin : operator, system) ALL
483 user B<alan> may run any command as either user root or bin,
484 optionally setting the group to operator or system.
488 On systems with SELinux support, I<sudoers> entries may optionally have
489 an SELinux role and/or type associated with a command. If a role or
490 type is specified with the command it will override any default values
491 specified in I<sudoers>. A role or type specified on the command line,
492 however, will supercede the values in I<sudoers>.
496 A command may have zero or more tags associated with it. There are
497 eight possible tag values, C<NOPASSWD>, C<PASSWD>, C<NOEXEC>,
498 C<EXEC>, C<SETENV>, C<NOSETENV>, C<LOG_INPUT>, C<NOLOG_INPUT>,
499 C<LOG_OUTPUT> and C<NOLOG_OUTPUT>. Once a tag is set on a C<Cmnd>,
500 subsequent C<Cmnd>s in the C<Cmnd_Spec_List>, inherit the tag unless
501 it is overridden by the opposite tag (i.e.: C<PASSWD> overrides
502 C<NOPASSWD> and C<NOEXEC> overrides C<EXEC>).
504 =head3 NOPASSWD and PASSWD
506 By default, B<sudo> requires that a user authenticate him or herself
507 before running a command. This behavior can be modified via the
508 C<NOPASSWD> tag. Like a C<Runas_Spec>, the C<NOPASSWD> tag sets
509 a default for the commands that follow it in the C<Cmnd_Spec_List>.
510 Conversely, the C<PASSWD> tag can be used to reverse things.
513 ray rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm
515 would allow the user B<ray> to run F</bin/kill>, F</bin/ls>, and
516 F</usr/bin/lprm> as B<root> on the machine rushmore without
517 authenticating himself. If we only want B<ray> to be able to
518 run F</bin/kill> without a password the entry would be:
520 ray rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm
522 Note, however, that the C<PASSWD> tag has no effect on users who are
523 in the group specified by the I<exempt_group> option.
525 By default, if the C<NOPASSWD> tag is applied to any of the entries
526 for a user on the current host, he or she will be able to run
527 C<sudo -l> without a password. Additionally, a user may only run
528 C<sudo -v> without a password if the C<NOPASSWD> tag is present
529 for all a user's entries that pertain to the current host.
530 This behavior may be overridden via the verifypw and listpw options.
532 =head3 NOEXEC and EXEC
534 If B<sudo> has been compiled with I<noexec> support and the underlying
535 operating system supports it, the C<NOEXEC> tag can be used to prevent
536 a dynamically-linked executable from running further commands itself.
538 In the following example, user B<aaron> may run F</usr/bin/more>
539 and F</usr/bin/vi> but shell escapes will be disabled.
541 aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi
543 See the L<PREVENTING SHELL ESCAPES> section below for more details
544 on how C<NOEXEC> works and whether or not it will work on your system.
546 =head3 SETENV and NOSETENV
548 These tags override the value of the I<setenv> option on a per-command
549 basis. Note that if C<SETENV> has been set for a command, the user
550 may disable the I<env_reset> option from the command line via the
551 B<-E> option. Additionally, environment variables set on the command
552 line are not subject to the restrictions imposed by I<env_check>,
553 I<env_delete>, or I<env_keep>. As such, only trusted users should
554 be allowed to set variables in this manner. If the command matched
555 is B<ALL>, the C<SETENV> tag is implied for that command; this
556 default may be overridden by use of the C<NOSETENV> tag.
558 =head3 LOG_INPUT and NOLOG_INPUT
560 These tags override the value of the I<log_input> option on a
561 per-command basis. For more information, see the description of
562 I<log_input> in the L<"SUDOERS OPTIONS"> section below.
564 =head3 LOG_OUTPUT and NOLOG_OUTPUT
566 These tags override the value of the I<log_output> option on a
567 per-command basis. For more information, see the description of
568 I<log_output> in the L<"SUDOERS OPTIONS"> section below.
572 B<sudo> allows shell-style I<wildcards> (aka meta or glob characters)
573 to be used in host names, path names and command line arguments in
574 the I<sudoers> file. Wildcard matching is done via the B<POSIX>
575 L<glob(3)> and L<fnmatch(3)> routines. Note that these are I<not>
582 Matches any set of zero or more characters.
586 Matches any single character.
590 Matches any character in the specified range.
594 Matches any character B<not> in the specified range.
598 For any character "x", evaluates to "x". This is used to
599 escape special characters such as: "*", "?", "[", and "}".
603 POSIX character classes may also be used if your system's L<glob(3)>
604 and L<fnmatch(3)> functions support them. However, because the
605 C<':'> character has special meaning in I<sudoers>, it must be
606 escaped. For example:
608 /bin/ls [[\:alpha\:]]*
610 Would match any file name beginning with a letter.
612 Note that a forward slash ('/') will B<not> be matched by
613 wildcards used in the path name. When matching the command
614 line arguments, however, a slash B<does> get matched by
615 wildcards. This is to make a path like:
619 match F</usr/bin/who> but not F</usr/bin/X11/xterm>.
621 =head2 Exceptions to wildcard rules
623 The following exceptions apply to the above rules:
629 If the empty string C<""> is the only command line argument in the
630 I<sudoers> entry it means that command is not allowed to be run
631 with B<any> arguments.
635 =head2 Including other files from within sudoers
637 It is possible to include other I<sudoers> files from within the
638 I<sudoers> file currently being parsed using the C<#include> and
639 C<#includedir> directives.
641 This can be used, for example, to keep a site-wide I<sudoers> file
642 in addition to a local, per-machine file. For the sake of this
643 example the site-wide I<sudoers> will be F</etc/sudoers> and the
644 per-machine one will be F</etc/sudoers.local>. To include
645 F</etc/sudoers.local> from within F</etc/sudoers> we would use the
646 following line in F</etc/sudoers>:
650 C<#include /etc/sudoers.local>
654 When B<sudo> reaches this line it will suspend processing of the
655 current file (F</etc/sudoers>) and switch to F</etc/sudoers.local>.
656 Upon reaching the end of F</etc/sudoers.local>, the rest of
657 F</etc/sudoers> will be processed. Files that are included may
658 themselves include other files. A hard limit of 128 nested include
659 files is enforced to prevent include file loops.
661 If the path to the include file is not fully-qualified (does not
662 begin with a F</>), it must be located in the same directory as the
663 sudoers file it was included from. For example, if F</etc/sudoers>
668 C<#include sudoers.local>
672 the file that will be included is F</etc/sudoers.local>.
674 The file name may also include the C<%h> escape, signifying the short form
675 of the host name. I.e., if the machine's host name is "xerxes", then
677 C<#include /etc/sudoers.%h>
679 will cause B<sudo> to include the file F</etc/sudoers.xerxes>.
681 The C<#includedir> directive can be used to create a F<sudo.d>
682 directory that the system package manager can drop I<sudoers> rules
683 into as part of package installation. For example, given:
685 C<#includedir /etc/sudoers.d>
687 B<sudo> will read each file in F</etc/sudoers.d>, skipping file
688 names that end in C<~> or contain a C<.> character to avoid causing
689 problems with package manager or editor temporary/backup files.
690 Files are parsed in sorted lexical order. That is,
691 F</etc/sudoers.d/01_first> will be parsed before
692 F</etc/sudoers.d/10_second>. Be aware that because the sorting is
693 lexical, not numeric, F</etc/sudoers.d/1_whoops> would be loaded
694 B<after> F</etc/sudoers.d/10_second>. Using a consistent number
695 of leading zeroes in the file names can be used to avoid such
698 Note that unlike files included via C<#include>, B<visudo> will not
699 edit the files in a C<#includedir> directory unless one of them
700 contains a syntax error. It is still possible to run B<visudo>
701 with the C<-f> flag to edit the files directly.
703 =head2 Other special characters and reserved words
705 The pound sign ('#') is used to indicate a comment (unless it is
706 part of a #include directive or unless it occurs in the context of
707 a user name and is followed by one or more digits, in which case
708 it is treated as a uid). Both the comment character and any text
709 after it, up to the end of the line, are ignored.
711 The reserved word B<ALL> is a built-in I<alias> that always causes
712 a match to succeed. It can be used wherever one might otherwise
713 use a C<Cmnd_Alias>, C<User_Alias>, C<Runas_Alias>, or C<Host_Alias>.
714 You should not try to define your own I<alias> called B<ALL> as the
715 built-in alias will be used in preference to your own. Please note
716 that using B<ALL> can be dangerous since in a command context, it
717 allows the user to run B<any> command on the system.
719 An exclamation point ('!') can be used as a logical I<not> operator
720 both in an I<alias> and in front of a C<Cmnd>. This allows one to
721 exclude certain values. Note, however, that using a C<!> in
722 conjunction with the built-in C<ALL> alias to allow a user to
723 run "all but a few" commands rarely works as intended (see SECURITY
726 Long lines can be continued with a backslash ('\') as the last
727 character on the line.
729 Whitespace between elements in a list as well as special syntactic
730 characters in a I<User Specification> ('=', ':', '(', ')') is optional.
732 The following characters must be escaped with a backslash ('\') when
733 used as part of a word (e.g.E<nbsp>a user name or host name):
734 '!', '=', ':', ',', '(', ')', '\'.
736 =head1 SUDOERS OPTIONS
738 B<sudo>'s behavior can be modified by C<Default_Entry> lines, as
739 explained earlier. A list of all supported Defaults parameters,
740 grouped by type, are listed below.
746 =item always_set_home
748 If enabled, B<sudo> will set the C<HOME> environment variable to the
749 home directory of the target user (which is root unless the B<-u>
750 option is used). This effectively means that the B<-H> option is
751 always implied. Note that C<HOME> is already set when the the
752 I<env_reset> option is enabled, so I<always_set_home> is only
753 effective for configurations where either I<env_reset> is disabled
754 or C<HOME> is present in the I<env_keep> list.
755 This flag is I<off> by default.
759 If set, users must authenticate themselves via a password (or other
760 means of authentication) before they may run commands. This default
761 may be overridden via the C<PASSWD> and C<NOPASSWD> tags.
762 This flag is I<on> by default.
764 =item closefrom_override
766 If set, the user may use B<sudo>'s B<-C> option which
767 overrides the default starting point at which B<sudo> begins
768 closing open file descriptors. This flag is I<off> by default.
772 If set, and B<sudo> is configured to log a command's input or output,
773 the I/O logs will be compressed using B<zlib>. This flag is I<on>
774 by default when B<sudo> is compiled with B<zlib> support.
778 If set, B<visudo> will use the value of the EDITOR or VISUAL
779 environment variables before falling back on the default editor list.
780 Note that this may create a security hole as it allows the user to
781 run any arbitrary command as root without logging. A safer alternative
782 is to place a colon-separated list of editors in the C<editor>
783 variable. B<visudo> will then only use the EDITOR or VISUAL if
784 they match a value specified in C<editor>. This flag is I<@env_editor@> by
789 If set, B<sudo> will run the command in a minimal environment
790 containing the C<TERM>, C<PATH>, C<HOME>, C<MAIL>, C<SHELL>,
791 C<LOGNAME>, C<USER>, C<USERNAME> and C<SUDO_*> variables. Any
792 variables in the caller's environment that match the C<env_keep>
793 and C<env_check> lists are then added, followed by any variables
794 present in the file specified by the I<env_file> option (if any).
795 The default contents of the C<env_keep> and C<env_check> lists are
796 displayed when B<sudo> is run by root with the I<-V> option. If
797 the I<secure_path> option is set, its value will be used for the
798 C<PATH> environment variable. This flag is I<@env_reset@> by
803 Normally, B<sudo> uses the L<glob(3)> function to do shell-style
804 globbing when matching path names. However, since it accesses the
805 file system, L<glob(3)> can take a long time to complete for some
806 patterns, especially when the pattern references a network file
807 system that is mounted on demand (automounted). The I<fast_glob>
808 option causes B<sudo> to use the L<fnmatch(3)> function, which does
809 not access the file system to do its matching. The disadvantage
810 of I<fast_glob> is that it is unable to match relative path names
811 such as F<./ls> or F<../bin/ls>. This has security implications
812 when path names that include globbing characters are used with the
813 negation operator, C<'!'>, as such rules can be trivially bypassed.
814 As such, this option should not be used when I<sudoers> contains rules
815 that contain negated path names which include globbing characters.
816 This flag is I<off> by default.
820 Set this flag if you want to put fully qualified host names in the
821 I<sudoers> file. I.e., instead of myhost you would use myhost.mydomain.edu.
822 You may still use the short form if you wish (and even mix the two).
823 Beware that turning on I<fqdn> requires B<sudo> to make DNS lookups
824 which may make B<sudo> unusable if DNS stops working (for example
825 if the machine is not plugged into the network). Also note that
826 you must use the host's official name as DNS knows it. That is,
827 you may not use a host alias (C<CNAME> entry) due to performance
828 issues and the fact that there is no way to get all aliases from
829 DNS. If your machine's host name (as returned by the C<hostname>
830 command) is already fully qualified you shouldn't need to set
831 I<fqdn>. This flag is I<@fqdn@> by default.
835 If set, B<sudo> will ignore '.' or '' (current dir) in the C<PATH>
836 environment variable; the C<PATH> itself is not modified. This
837 flag is I<@ignore_dot@> by default.
839 =item ignore_local_sudoers
841 If set via LDAP, parsing of F<@sysconfdir@/sudoers> will be skipped.
842 This is intended for Enterprises that wish to prevent the usage of local
843 sudoers files so that only LDAP is used. This thwarts the efforts of
844 rogue operators who would attempt to add roles to F<@sysconfdir@/sudoers>.
845 When this option is present, F<@sysconfdir@/sudoers> does not even need to
846 exist. Since this option tells B<sudo> how to behave when no specific LDAP
847 entries have been matched, this sudoOption is only meaningful for the
848 C<cn=defaults> section. This flag is I<off> by default.
852 If set, B<sudo> will insult users when they enter an incorrect
853 password. This flag is I<@insults@> by default.
857 If set, the host name will be logged in the (non-syslog) B<sudo> log file.
858 This flag is I<off> by default.
862 If set, B<sudo> will run the command in a I<pseudo tty> and log all
864 If the standard input is not connected to the user's tty, due to
865 I/O redirection or because the command is part of a pipeline, that
866 input is also captured and stored in a separate log file.
868 Input is logged to the directory specified by the I<iolog_dir>
869 option (F<@iolog_dir@> by default) using a unique session ID that
870 is included in the normal B<sudo> log line, prefixed with I<TSID=>.
871 The I<iolog_file> option may be used to control the format of the
874 Note that user input may contain sensitive information such as
875 passwords (even if they are not echoed to the screen), which will
876 be stored in the log file unencrypted. In most cases, logging the
877 command output via I<log_output> is all that is required.
881 If set, B<sudo> will run the command in a I<pseudo tty> and log all
882 output that is sent to the screen, similar to the script(1) command.
883 If the standard output or standard error is not connected to the
884 user's tty, due to I/O redirection or because the command is part
885 of a pipeline, that output is also captured and stored in separate
888 Output is logged to the directory specified by the I<iolog_dir>
889 option (F<@iolog_dir@> by default) using a unique session ID that
890 is included in the normal B<sudo> log line, prefixed with I<TSID=>.
891 The I<iolog_file> option may be used to control the format of the
894 Output logs may be viewed with the L<sudoreplay(8)> utility, which
895 can also be used to list or search the available logs.
899 If set, the four-digit year will be logged in the (non-syslog) B<sudo> log file.
900 This flag is I<off> by default.
902 =item long_otp_prompt
904 When validating with a One Time Password (OTP) scheme such as
905 B<S/Key> or B<OPIE>, a two-line prompt is used to make it easier
906 to cut and paste the challenge to a local window. It's not as
907 pretty as the default but some people find it more convenient. This
908 flag is I<@long_otp_prompt@> by default.
912 Send mail to the I<mailto> user every time a users runs B<sudo>.
913 This flag is I<off> by default.
917 Send mail to the I<mailto> user if the user running B<sudo> does not
918 enter the correct password. This flag is I<off> by default.
922 If set, mail will be sent to the I<mailto> user if the invoking
923 user exists in the I<sudoers> file, but is not allowed to run
924 commands on the current host. This flag is I<@mail_no_host@> by default.
928 If set, mail will be sent to the I<mailto> user if the invoking
929 user is allowed to use B<sudo> but the command they are trying is not
930 listed in their I<sudoers> file entry or is explicitly denied.
931 This flag is I<@mail_no_perms@> by default.
935 If set, mail will be sent to the I<mailto> user if the invoking
936 user is not in the I<sudoers> file. This flag is I<@mail_no_user@>
941 If set, all commands run via B<sudo> will behave as if the C<NOEXEC>
942 tag has been set, unless overridden by a C<EXEC> tag. See the
943 description of I<NOEXEC and EXEC> below as well as the L<PREVENTING SHELL
944 ESCAPES> section at the end of this manual. This flag is I<off> by default.
948 Normally, B<sudo> will tell the user when a command could not be
949 found in their C<PATH> environment variable. Some sites may wish
950 to disable this as it could be used to gather information on the
951 location of executables that the normal user does not have access
952 to. The disadvantage is that if the executable is simply not in
953 the user's C<PATH>, B<sudo> will tell the user that they are not
954 allowed to run it, which can be confusing. This flag is I<@path_info@>
957 =item passprompt_override
959 The password prompt specified by I<passprompt> will normally only
960 be used if the password prompt provided by systems such as PAM matches
961 the string "Password:". If I<passprompt_override> is set, I<passprompt>
962 will always be used. This flag is I<off> by default.
964 =item preserve_groups
966 By default, B<sudo> will initialize the group vector to the list of
967 groups the target user is in. When I<preserve_groups> is set, the
968 user's existing group vector is left unaltered. The real and
969 effective group IDs, however, are still set to match the target
970 user. This flag is I<off> by default.
974 By default, B<sudo> reads the password like most other Unix programs,
975 by turning off echo until the user hits the return (or enter) key.
976 Some users become confused by this as it appears to them that B<sudo>
977 has hung at this point. When I<pwfeedback> is set, B<sudo> will
978 provide visual feedback when the user presses a key. Note that
979 this does have a security impact as an onlooker may be able to
980 determine the length of the password being entered.
981 This flag is I<off> by default.
985 If set, B<sudo> will only run when the user is logged in to a real
986 tty. When this flag is set, B<sudo> can only be run from a login
987 session and not via other means such as L<cron(8)> or cgi-bin scripts.
988 This flag is I<off> by default.
992 If set, root is allowed to run B<sudo> too. Disabling this prevents users
993 from "chaining" B<sudo> commands to get a root shell by doing something
994 like C<"sudo sudo /bin/sh">. Note, however, that turning off I<root_sudo>
995 will also prevent root from running B<sudoedit>.
996 Disabling I<root_sudo> provides no real additional security; it
997 exists purely for historical reasons.
998 This flag is I<@root_sudo@> by default.
1002 If set, B<sudo> will prompt for the root password instead of the password
1003 of the invoking user. This flag is I<off> by default.
1007 If set, B<sudo> will prompt for the password of the user defined by the
1008 I<runas_default> option (defaults to C<@runas_default@>) instead of the
1009 password of the invoking user. This flag is I<off> by default.
1013 If enabled and B<sudo> is invoked with the B<-s> option the C<HOME>
1014 environment variable will be set to the home directory of the target
1015 user (which is root unless the B<-u> option is used). This effectively
1016 makes the B<-s> option imply B<-H>. Note that C<HOME> is already
1017 set when the the I<env_reset> option is enabled, so I<set_home> is
1018 only effective for configurations where either I<env_reset> is disabled
1019 or C<HOME> is present in the I<env_keep> list.
1020 This flag is I<off> by default.
1024 Normally, B<sudo> will set the C<LOGNAME>, C<USER> and C<USERNAME>
1025 environment variables to the name of the target user (usually root
1026 unless the B<-u> option is given). However, since some programs
1027 (including the RCS revision control system) use C<LOGNAME> to
1028 determine the real identity of the user, it may be desirable to
1029 change this behavior. This can be done by negating the set_logname
1030 option. Note that if the I<env_reset> option has not been disabled,
1031 entries in the I<env_keep> list will override the value of
1032 I<set_logname>. This flag is I<on> by default.
1036 When enabled, B<sudo> will create an entry in the utmp (or utmpx)
1037 file when a pseudo-tty is allocated. A pseudo-tty is allocated by
1038 B<sudo> when the I<log_input>, I<log_output> or I<use_pty> flags
1039 are enabled. By default, the new entry will be a copy of the user's
1040 existing utmp entry (if any), with the tty, time, type and pid
1041 fields updated. This flag is I<on> by default.
1045 Allow the user to disable the I<env_reset> option from the command
1046 line via the B<-E> option. Additionally, environment variables set
1047 via the command line are not subject to the restrictions imposed
1048 by I<env_check>, I<env_delete>, or I<env_keep>. As such, only
1049 trusted users should be allowed to set variables in this manner.
1050 This flag is I<off> by default.
1054 If set and B<sudo> is invoked with no arguments it acts as if the
1055 B<-s> option had been given. That is, it runs a shell as root (the
1056 shell is determined by the C<SHELL> environment variable if it is
1057 set, falling back on the shell listed in the invoking user's
1058 /etc/passwd entry if not). This flag is I<off> by default.
1062 Normally, when B<sudo> executes a command the real and effective
1063 UIDs are set to the target user (root by default). This option
1064 changes that behavior such that the real UID is left as the invoking
1065 user's UID. In other words, this makes B<sudo> act as a setuid
1066 wrapper. This can be useful on systems that disable some potentially
1067 dangerous functionality when a program is run setuid. This option
1068 is only effective on systems with either the setreuid() or setresuid()
1069 function. This flag is I<off> by default.
1073 If set, B<sudo> will prompt for the password of the user specified
1074 by the B<-u> option (defaults to C<root>) instead of the password
1075 of the invoking user. In addition, the timestamp file name will
1076 include the target user's name. Note that this flag precludes the
1077 use of a uid not listed in the passwd database as an argument to
1078 the B<-u> option. This flag is I<off> by default.
1082 If set, users must authenticate on a per-tty basis. With this flag
1083 enabled, B<sudo> will use a file named for the tty the user is
1084 logged in on in the user's time stamp directory. If disabled, the
1085 time stamp of the directory is used instead. This flag is
1086 I<@tty_tickets@> by default.
1088 =item umask_override
1090 If set, B<sudo> will set the umask as specified by I<sudoers> without
1091 modification. This makes it possible to specify a more permissive
1092 umask in I<sudoers> than the user's own umask and matches historical
1093 behavior. If I<umask_override> is not set, B<sudo> will set the
1094 umask to be the union of the user's umask and what is specified in
1095 I<sudoers>. This flag is I<@umask_override@> by default.
1097 =item use_loginclass
1099 If set, B<sudo> will apply the defaults specified for the target user's
1100 login class if one exists. Only available if B<sudo> is configured with
1101 the --with-logincap option. This flag is I<off> by default.
1105 If set, B<sudo> will run the command in a pseudo-pty even if no I/O
1106 logging is being gone. A malicious program run under B<sudo> could
1107 conceivably fork a background process that retains to the user's
1108 terminal device after the main program has finished executing. Use
1109 of this option will make that impossible. This flag is I<off> by default.
1113 If set, B<sudo> will store the name of the runas user when updating
1114 the utmp (or utmpx) file. By default, B<sudo> stores the name of
1115 the invoking user. This flag is I<off> by default.
1119 By default, B<sudo> will refuse to run if the user must enter a
1120 password but it is not possible to disable echo on the terminal.
1121 If the I<visiblepw> flag is set, B<sudo> will prompt for a password
1122 even when it would be visible on the screen. This makes it possible
1123 to run things like C<"rsh somehost sudo ls"> since L<rsh(1)> does
1124 not allocate a tty. This flag is I<off> by default.
1134 Before it executes a command, B<sudo> will close all open file
1135 descriptors other than standard input, standard output and standard
1136 error (ie: file descriptors 0-2). The I<closefrom> option can be used
1137 to specify a different file descriptor at which to start closing.
1138 The default is C<3>.
1142 The number of tries a user gets to enter his/her password before
1143 B<sudo> logs the failure and exits. The default is C<@passwd_tries@>.
1147 B<Integers that can be used in a boolean context>:
1153 Number of characters per line for the file log. This value is used
1154 to decide when to wrap lines for nicer log files. This has no
1155 effect on the syslog log file, only the file log. The default is
1156 C<@loglen@> (use 0 or negate the option to disable word wrap).
1158 =item passwd_timeout
1160 Number of minutes before the B<sudo> password prompt times out, or
1161 C<0> for no timeout. The timeout may include a fractional component
1162 if minute granularity is insufficient, for example C<2.5>. The
1163 default is C<@password_timeout@>.
1165 =item timestamp_timeout
1167 Number of minutes that can elapse before B<sudo> will ask for a
1168 passwd again. The timeout may include a fractional component if
1169 minute granularity is insufficient, for example C<2.5>. The default
1170 is C<@timeout@>. Set this to C<0> to always prompt for a password.
1171 If set to a value less than C<0> the user's timestamp will never
1172 expire. This can be used to allow users to create or delete their
1173 own timestamps via C<sudo -v> and C<sudo -k> respectively.
1177 Umask to use when running the command. Negate this option or set
1178 it to 0777 to preserve the user's umask. The actual umask that is
1179 used will be the union of the user's umask and the value of the
1180 I<umask> option, which defaults to C<@sudo_umask@>. This guarantees
1181 that B<sudo> never lowers the umask when running a command. Note
1182 on systems that use PAM, the default PAM configuration may specify
1183 its own umask which will override the value set in I<sudoers>.
1191 =item badpass_message
1193 Message that is displayed if a user enters an incorrect password.
1194 The default is C<@badpass_message@> unless insults are enabled.
1198 A colon (':') separated list of editors allowed to be used with
1199 B<visudo>. B<visudo> will choose the editor that matches the user's
1200 EDITOR environment variable if possible, or the first editor in the
1201 list that exists and is executable. The default is C<"@editor@">.
1205 The top-level directory to use when constructing the path name for
1206 the input/output log directory. Only used if the I<log_input> or
1207 I<log_output> options are enabled or when the C<LOG_INPUT> or
1208 C<LOG_OUTPUT> tags are present for a command. The session sequence
1209 number, if any, is stored in the directory.
1210 The default is C<"@iolog_dir@">.
1212 The following percent (`C<%>') escape sequences are supported:
1218 expanded to a monotonically increasing base-36 sequence number, such as 0100A5,
1219 where every two digits are used to form a new directory, e.g. F<01/00/A5>
1223 expanded to the invoking user's login name
1227 expanded to the name of the invoking user's real group ID
1229 =item C<%{runas_user}>
1231 expanded to the login name of the user the command will
1232 be run as (e.g. root)
1234 =item C<%{runas_group}>
1236 expanded to the group name of the user the command will
1237 be run as (e.g. wheel)
1239 =item C<%{hostname}>
1241 expanded to the local host name without the domain name
1245 expanded to the base name of the command being run
1249 In addition, any escape sequences supported by the system's strftime()
1250 function will be expanded.
1252 To include a literal `C<%>' character, the string `C<%%>' should
1257 The path name, relative to I<iolog_dir>, in which to store input/output
1258 logs when the I<log_input> or I<log_output> options are enabled or
1259 when the C<LOG_INPUT> or C<LOG_OUTPUT> tags are present for a command.
1260 Note that I<iolog_file> may contain directory components.
1261 The default is C<"%{seq}">.
1263 See the I<iolog_dir> option above for a list of supported percent
1264 (`C<%>') escape sequences.
1266 In addition to the escape sequences, path names that end in six or
1267 more C<X>s will have the C<X>s replaced with a unique combination
1268 of digits and letters, similar to the mktemp() function.
1272 Subject of the mail sent to the I<mailto> user. The escape C<%h>
1273 will expand to the host name of the machine.
1274 Default is C<@mailsub@>.
1278 This option is no longer supported. The path to the noexec file
1279 should now be set in the F<@sysconfdir@/sudo.conf> file.
1283 The default prompt to use when asking for a password; can be overridden
1284 via the B<-p> option or the C<SUDO_PROMPT> environment variable.
1285 The following percent (`C<%>') escape sequences are supported:
1291 expanded to the local host name including the domain name
1292 (only if the machine's host name is fully qualified or the I<fqdn>
1297 expanded to the local host name without the domain name
1301 expanded to the user whose password is being asked for (respects the
1302 I<rootpw>, I<targetpw> and I<runaspw> flags in I<sudoers>)
1306 expanded to the login name of the user the command will
1307 be run as (defaults to root)
1311 expanded to the invoking user's login name
1315 two consecutive C<%> characters are collapsed into a single C<%> character
1319 The default value is C<@passprompt@>.
1323 The default SELinux role to use when constructing a new security
1324 context to run the command. The default role may be overridden on
1325 a per-command basis in I<sudoers> or via command line options.
1326 This option is only available whe B<sudo> is built with SELinux support.
1330 The default user to run commands as if the B<-u> option is not specified
1331 on the command line. This defaults to C<@runas_default@>.
1335 Syslog priority to use when user authenticates unsuccessfully.
1336 Defaults to C<@badpri@>.
1338 The following syslog priorities are supported: B<alert>, B<crit>,
1339 B<debug>, B<emerg>, B<err>, B<info>, B<notice>, and B<warning>.
1341 =item syslog_goodpri
1343 Syslog priority to use when user authenticates successfully.
1344 Defaults to C<@goodpri@>.
1346 See L<syslog_badpri> for the list of supported syslog priorities.
1348 =item sudoers_locale
1350 Locale to use when parsing the sudoers file, logging commands, and
1351 sending email. Note that changing the locale may affect how sudoers
1352 is interpreted. Defaults to C<"C">.
1356 The directory in which B<sudo> stores its timestamp files.
1357 The default is F<@timedir@>.
1359 =item timestampowner
1361 The owner of the timestamp directory and the timestamps stored therein.
1362 The default is C<root>.
1366 The default SELinux type to use when constructing a new security
1367 context to run the command. The default type may be overridden on
1368 a per-command basis in I<sudoers> or via command line options.
1369 This option is only available whe B<sudo> is built with SELinux support.
1373 B<Strings that can be used in a boolean context>:
1379 The I<env_file> option specifies the fully qualified path to a
1380 file containing variables to be set in the environment of the program
1381 being run. Entries in this file should either be of the form
1382 C<VARIABLE=value> or C<export VARIABLE=value>. The value may
1383 optionally be surrounded by single or double quotes. Variables in
1384 this file are subject to other B<sudo> environment settings such
1385 as I<env_keep> and I<env_check>.
1389 Users in this group are exempt from password and PATH requirements.
1390 The group name specified should not include a C<%> prefix.
1391 This is not set by default.
1395 A string containing a I<sudoers> group plugin with optional arguments.
1396 This can be used to implement support for the C<nonunix_group>
1397 syntax described earlier. The string should consist of the plugin
1398 path, either fully-qualified or relative to the F<@prefix@/libexec>
1399 directory, followed by any configuration arguments the plugin
1400 requires. These arguments (if any) will be passed to the plugin's
1401 initialization function. If arguments are present, the string must
1402 be enclosed in double quotes (C<">).
1404 For example, given F</etc/sudo-group>, a group file in Unix group
1405 format, the sample group plugin can be used:
1407 Defaults group_plugin="sample_group.so /etc/sudo-group"
1409 For more information see L<sudo_plugin(5)>.
1413 This option controls when a short lecture will be printed along with
1414 the password prompt. It has the following possible values:
1420 Always lecture the user.
1424 Never lecture the user.
1428 Only lecture the user the first time they run B<sudo>.
1432 If no value is specified, a value of I<once> is implied.
1433 Negating the option results in a value of I<never> being used.
1434 The default value is I<@lecture@>.
1438 Path to a file containing an alternate B<sudo> lecture that will
1439 be used in place of the standard lecture if the named file exists.
1440 By default, B<sudo> uses a built-in lecture.
1444 This option controls when a password will be required when a
1445 user runs B<sudo> with the B<-l> option. It has the following possible values:
1451 All the user's I<sudoers> entries for the current host must have
1452 the C<NOPASSWD> flag set to avoid entering a password.
1456 The user must always enter a password to use the B<-l> option.
1460 At least one of the user's I<sudoers> entries for the current host
1461 must have the C<NOPASSWD> flag set to avoid entering a password.
1465 The user need never enter a password to use the B<-l> option.
1469 If no value is specified, a value of I<any> is implied.
1470 Negating the option results in a value of I<never> being used.
1471 The default value is I<any>.
1475 Path to the B<sudo> log file (not the syslog log file). Setting a path
1476 turns on logging to a file; negating this option turns it off.
1477 By default, B<sudo> logs via syslog.
1481 Flags to use when invoking mailer. Defaults to B<-t>.
1485 Path to mail program used to send warning mail.
1486 Defaults to the path to sendmail found at configure time.
1490 Address to use for the "from" address when sending warning and error
1491 mail. The address should be enclosed in double quotes (C<">) to
1492 protect against B<sudo> interpreting the C<@> sign. Defaults to
1493 the name of the user running B<sudo>.
1497 Address to send warning and error mail to. The address should
1498 be enclosed in double quotes (C<">) to protect against B<sudo>
1499 interpreting the C<@> sign. Defaults to C<@mailto@>.
1503 Path used for every command run from B<sudo>. If you don't trust the
1504 people running B<sudo> to have a sane C<PATH> environment variable you may
1505 want to use this. Another use is if you want to have the "root path"
1506 be separate from the "user path." Users in the group specified by the
1507 I<exempt_group> option are not affected by I<secure_path>.
1508 This option is @secure_path@ by default.
1512 Syslog facility if syslog is being used for logging (negate to
1513 disable syslog logging). Defaults to C<@logfac@>.
1515 The following syslog facilities are supported: B<authpriv> (if your
1516 OS supports it), B<auth>, B<daemon>, B<user>, B<local0>, B<local1>,
1517 B<local2>, B<local3>, B<local4>, B<local5>, B<local6>, and B<local7>.
1521 This option controls when a password will be required when a user runs
1522 B<sudo> with the B<-v> option. It has the following possible values:
1528 All the user's I<sudoers> entries for the current host must have
1529 the C<NOPASSWD> flag set to avoid entering a password.
1533 The user must always enter a password to use the B<-v> option.
1537 At least one of the user's I<sudoers> entries for the current host
1538 must have the C<NOPASSWD> flag set to avoid entering a password.
1542 The user need never enter a password to use the B<-v> option.
1546 If no value is specified, a value of I<all> is implied.
1547 Negating the option results in a value of I<never> being used.
1548 The default value is I<all>.
1552 B<Lists that can be used in a boolean context>:
1558 Environment variables to be removed from the user's environment if
1559 the variable's value contains C<%> or C</> characters. This can
1560 be used to guard against printf-style format vulnerabilities in
1561 poorly-written programs. The argument may be a double-quoted,
1562 space-separated list or a single value without double-quotes. The
1563 list can be replaced, added to, deleted from, or disabled by using
1564 the C<=>, C<+=>, C<-=>, and C<!> operators respectively. Regardless
1565 of whether the C<env_reset> option is enabled or disabled, variables
1566 specified by C<env_check> will be preserved in the environment if
1567 they pass the aforementioned check. The default list of environment
1568 variables to check is displayed when B<sudo> is run by root with
1573 Environment variables to be removed from the user's environment
1574 when the I<env_reset> option is not in effect. The argument may
1575 be a double-quoted, space-separated list or a single value without
1576 double-quotes. The list can be replaced, added to, deleted from,
1577 or disabled by using the C<=>, C<+=>, C<-=>, and C<!> operators
1578 respectively. The default list of environment variables to remove
1579 is displayed when B<sudo> is run by root with the I<-V> option.
1580 Note that many operating systems will remove potentially dangerous
1581 variables from the environment of any setuid process (such as
1586 Environment variables to be preserved in the user's environment
1587 when the I<env_reset> option is in effect. This allows fine-grained
1588 control over the environment B<sudo>-spawned processes will receive.
1589 The argument may be a double-quoted, space-separated list or a
1590 single value without double-quotes. The list can be replaced, added
1591 to, deleted from, or disabled by using the C<=>, C<+=>, C<-=>, and
1592 C<!> operators respectively. The default list of variables to keep
1593 is displayed when B<sudo> is run by root with the I<-V> option.
1601 =item F<@sysconfdir@/sudoers>
1603 List of who can run what
1609 =item F</etc/netgroup>
1611 List of network groups
1613 =item F<@iolog_dir@>
1619 Directory containing time stamps for the I<sudoers> security policy
1621 =item F</etc/environment>
1623 Initial environment for B<-i> mode on Linux and AIX
1629 Below are example I<sudoers> entries. Admittedly, some of
1630 these are a bit contrived. First, we allow a few environment
1631 variables to pass and then define our I<aliases>:
1633 # Run X applications through sudo; HOME is used to find the
1634 # .Xauthority file. Note that other programs use HOME to find
1635 # configuration files and this may lead to privilege escalation!
1636 Defaults env_keep += "DISPLAY HOME"
1638 # User alias specification
1639 User_Alias FULLTIMERS = millert, mikef, dowdy
1640 User_Alias PARTTIMERS = bostley, jwfox, crawl
1641 User_Alias WEBMASTERS = will, wendy, wim
1643 # Runas alias specification
1644 Runas_Alias OP = root, operator
1645 Runas_Alias DB = oracle, sybase
1646 Runas_Alias ADMINGRP = adm, oper
1648 # Host alias specification
1649 Host_Alias SPARC = bigtime, eclipse, moet, anchor :\
1650 SGI = grolsch, dandelion, black :\
1651 ALPHA = widget, thalamus, foobar :\
1652 HPPA = boa, nag, python
1653 Host_Alias CUNETS = 128.138.0.0/255.255.0.0
1654 Host_Alias CSNETS = 128.138.243.0, 128.138.204.0/24, 128.138.242.0
1655 Host_Alias SERVERS = master, mail, www, ns
1656 Host_Alias CDROM = orion, perseus, hercules
1658 # Cmnd alias specification
1659 Cmnd_Alias DUMPS = /usr/bin/mt, /usr/sbin/dump, /usr/sbin/rdump,\
1660 /usr/sbin/restore, /usr/sbin/rrestore
1661 Cmnd_Alias KILL = /usr/bin/kill
1662 Cmnd_Alias PRINTING = /usr/sbin/lpc, /usr/bin/lprm
1663 Cmnd_Alias SHUTDOWN = /usr/sbin/shutdown
1664 Cmnd_Alias HALT = /usr/sbin/halt
1665 Cmnd_Alias REBOOT = /usr/sbin/reboot
1666 Cmnd_Alias SHELLS = /usr/bin/sh, /usr/bin/csh, /usr/bin/ksh, \
1667 /usr/local/bin/tcsh, /usr/bin/rsh, \
1669 Cmnd_Alias SU = /usr/bin/su
1670 Cmnd_Alias PAGERS = /usr/bin/more, /usr/bin/pg, /usr/bin/less
1672 Here we override some of the compiled in default values. We want
1673 B<sudo> to log via L<syslog(3)> using the I<auth> facility in all
1674 cases. We don't want to subject the full time staff to the B<sudo>
1675 lecture, user B<millert> need not give a password, and we don't
1676 want to reset the C<LOGNAME>, C<USER> or C<USERNAME> environment
1677 variables when running commands as root. Additionally, on the
1678 machines in the I<SERVERS> C<Host_Alias>, we keep an additional
1679 local log file and make sure we log the year in each log line since
1680 the log entries will be kept around for several years. Lastly, we
1681 disable shell escapes for the commands in the PAGERS C<Cmnd_Alias>
1682 (F</usr/bin/more>, F</usr/bin/pg> and F</usr/bin/less>).
1684 # Override built-in defaults
1685 Defaults syslog=auth
1686 Defaults>root !set_logname
1687 Defaults:FULLTIMERS !lecture
1688 Defaults:millert !authenticate
1689 Defaults@SERVERS log_year, logfile=/var/log/sudo.log
1690 Defaults!PAGERS noexec
1692 The I<User specification> is the part that actually determines who may
1695 root ALL = (ALL) ALL
1696 %wheel ALL = (ALL) ALL
1698 We let B<root> and any user in group B<wheel> run any command on any
1701 FULLTIMERS ALL = NOPASSWD: ALL
1703 Full time sysadmins (B<millert>, B<mikef>, and B<dowdy>) may run any
1704 command on any host without authenticating themselves.
1706 PARTTIMERS ALL = ALL
1708 Part time sysadmins (B<bostley>, B<jwfox>, and B<crawl>) may run any
1709 command on any host but they must authenticate themselves first
1710 (since the entry lacks the C<NOPASSWD> tag).
1714 The user B<jack> may run any command on the machines in the I<CSNETS> alias
1715 (the networks C<128.138.243.0>, C<128.138.204.0>, and C<128.138.242.0>).
1716 Of those networks, only C<128.138.204.0> has an explicit netmask (in
1717 CIDR notation) indicating it is a class C network. For the other
1718 networks in I<CSNETS>, the local machine's netmask will be used
1723 The user B<lisa> may run any command on any host in the I<CUNETS> alias
1724 (the class B network C<128.138.0.0>).
1726 operator ALL = DUMPS, KILL, SHUTDOWN, HALT, REBOOT, PRINTING,\
1727 sudoedit /etc/printcap, /usr/oper/bin/
1729 The B<operator> user may run commands limited to simple maintenance.
1730 Here, those are commands related to backups, killing processes, the
1731 printing system, shutting down the system, and any commands in the
1732 directory F</usr/oper/bin/>.
1734 joe ALL = /usr/bin/su operator
1736 The user B<joe> may only L<su(1)> to operator.
1738 pete HPPA = /usr/bin/passwd [A-Za-z]*, !/usr/bin/passwd root
1740 %opers ALL = (: ADMINGRP) /usr/sbin/
1742 Users in the B<opers> group may run commands in F</usr/sbin/> as themselves
1743 with any group in the I<ADMINGRP> C<Runas_Alias> (the B<adm> and B<oper>
1746 The user B<pete> is allowed to change anyone's password except for
1747 root on the I<HPPA> machines. Note that this assumes L<passwd(1)>
1748 does not take multiple user names on the command line.
1750 bob SPARC = (OP) ALL : SGI = (OP) ALL
1752 The user B<bob> may run anything on the I<SPARC> and I<SGI> machines
1753 as any user listed in the I<OP> C<Runas_Alias> (B<root> and B<operator>).
1757 The user B<jim> may run any command on machines in the I<biglab> netgroup.
1758 B<sudo> knows that "biglab" is a netgroup due to the '+' prefix.
1760 +secretaries ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser
1762 Users in the B<secretaries> netgroup need to help manage the printers
1763 as well as add and remove users, so they are allowed to run those
1764 commands on all machines.
1766 fred ALL = (DB) NOPASSWD: ALL
1768 The user B<fred> can run commands as any user in the I<DB> C<Runas_Alias>
1769 (B<oracle> or B<sybase>) without giving a password.
1771 john ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root*
1773 On the I<ALPHA> machines, user B<john> may su to anyone except root
1774 but he is not allowed to specify any options to the L<su(1)> command.
1776 jen ALL, !SERVERS = ALL
1778 The user B<jen> may run any command on any machine except for those
1779 in the I<SERVERS> C<Host_Alias> (master, mail, www and ns).
1781 jill SERVERS = /usr/bin/, !SU, !SHELLS
1783 For any machine in the I<SERVERS> C<Host_Alias>, B<jill> may run
1784 any commands in the directory F</usr/bin/> except for those commands
1785 belonging to the I<SU> and I<SHELLS> C<Cmnd_Aliases>.
1787 steve CSNETS = (operator) /usr/local/op_commands/
1789 The user B<steve> may run any command in the directory /usr/local/op_commands/
1790 but only as user operator.
1792 matt valkyrie = KILL
1794 On his personal workstation, valkyrie, B<matt> needs to be able to
1795 kill hung processes.
1797 WEBMASTERS www = (www) ALL, (root) /usr/bin/su www
1799 On the host www, any user in the I<WEBMASTERS> C<User_Alias> (will,
1800 wendy, and wim), may run any command as user www (which owns the
1801 web pages) or simply L<su(1)> to www.
1803 ALL CDROM = NOPASSWD: /sbin/umount /CDROM,\
1804 /sbin/mount -o nosuid\,nodev /dev/cd0a /CDROM
1806 Any user may mount or unmount a CD-ROM on the machines in the CDROM
1807 C<Host_Alias> (orion, perseus, hercules) without entering a password.
1808 This is a bit tedious for users to type, so it is a prime candidate
1809 for encapsulating in a shell script.
1811 =head1 SECURITY NOTES
1813 It is generally not effective to "subtract" commands from C<ALL>
1814 using the '!' operator. A user can trivially circumvent this
1815 by copying the desired command to a different name and then
1816 executing that. For example:
1818 bill ALL = ALL, !SU, !SHELLS
1820 Doesn't really prevent B<bill> from running the commands listed in
1821 I<SU> or I<SHELLS> since he can simply copy those commands to a
1822 different name, or use a shell escape from an editor or other
1823 program. Therefore, these kind of restrictions should be considered
1824 advisory at best (and reinforced by policy).
1826 Furthermore, if the I<fast_glob> option is in use, it is not possible
1827 to reliably negate commands where the path name includes globbing
1828 (aka wildcard) characters. This is because the C library's
1829 L<fnmatch(3)> function cannot resolve relative paths. While this
1830 is typically only an inconvenience for rules that grant privileges,
1831 it can result in a security issue for rules that subtract or revoke
1834 For example, given the following I<sudoers> entry:
1836 john ALL = /usr/bin/passwd [a-zA-Z0-9]*, /usr/bin/chsh [a-zA-Z0-9]*,
1837 /usr/bin/chfn [a-zA-Z0-9]*, !/usr/bin/* root
1839 User B<john> can still run C</usr/bin/passwd root> if I<fast_glob> is
1840 enabled by changing to F</usr/bin> and running C<./passwd root> instead.
1842 =head1 PREVENTING SHELL ESCAPES
1844 Once B<sudo> executes a program, that program is free to do whatever
1845 it pleases, including run other programs. This can be a security
1846 issue since it is not uncommon for a program to allow shell escapes,
1847 which lets a user bypass B<sudo>'s access control and logging.
1848 Common programs that permit shell escapes include shells (obviously),
1849 editors, paginators, mail and terminal programs.
1851 There are two basic approaches to this problem:
1857 Avoid giving users access to commands that allow the user to run
1858 arbitrary commands. Many editors have a restricted mode where shell
1859 escapes are disabled, though B<sudoedit> is a better solution to
1860 running editors via B<sudo>. Due to the large number of programs that
1861 offer shell escapes, restricting users to the set of programs that
1862 do not is often unworkable.
1866 Many systems that support shared libraries have the ability to
1867 override default library functions by pointing an environment
1868 variable (usually C<LD_PRELOAD>) to an alternate shared library.
1869 On such systems, B<sudo>'s I<noexec> functionality can be used to
1870 prevent a program run by B<sudo> from executing any other programs.
1871 Note, however, that this applies only to native dynamically-linked
1872 executables. Statically-linked executables and foreign executables
1873 running under binary emulation are not affected.
1875 The I<noexec> feature is known to work on SunOS, Solaris, *BSD,
1876 Linux, IRIX, Tru64 UNIX, MacOS X, HP-UX 11.x and AIX 5.3 and above.
1877 It should be supported on most operating systems that support the
1878 C<LD_PRELOAD> environment variable. Check your operating system's
1879 manual pages for the dynamic linker (usually ld.so, ld.so.1, dyld,
1880 dld.sl, rld, or loader) to see if C<LD_PRELOAD> is supported.
1882 On Solaris 10 and higher, I<noexec> uses Solaris privileges instead
1883 of the C<LD_PRELOAD> environment variable.
1885 To enable I<noexec> for a command, use the C<NOEXEC> tag as documented
1886 in the User Specification section above. Here is that example again:
1888 aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi
1890 This allows user B<aaron> to run F</usr/bin/more> and F</usr/bin/vi>
1891 with I<noexec> enabled. This will prevent those two commands from
1892 executing other commands (such as a shell). If you are unsure
1893 whether or not your system is capable of supporting I<noexec> you
1894 can always just try it out and check whether shell escapes work
1895 when I<noexec> is enabled.
1899 Note that restricting shell escapes is not a panacea. Programs
1900 running as root are still capable of many potentially hazardous
1901 operations (such as changing or overwriting files) that could lead
1902 to unintended privilege escalation. In the specific case of an
1903 editor, a safer approach is to give the user permission to run
1908 Versions 1.8.4 and higher of the I<sudoers> plugin supports a
1909 debugging framework that can help track down what the plugin is
1910 doing internally if there is a problem. This can be configured in
1911 the F<@sysconfdir@/sudo.conf> file as described in L<sudo(8)>.
1913 The I<sudoers> plugin uses the same debug flag format as B<sudo>
1914 itself: I<subsystem>@I<priority>.
1916 The priorities used by I<sudoers>, in order of decreasing severity,
1917 are: I<crit>, I<err>, I<warn>, I<notice>, I<diag>, I<info>, I<trace>
1918 and I<debug>. Each priority, when specified, also includes all
1919 priorities higher than it. For example, a priority of I<notice>
1920 would include debug messages logged at I<notice> and higher.
1922 The following subsystems are used by I<sudoers>:
1928 C<User_Alias>, C<Runas_Alias>, C<Host_Alias> and C<Cmnd_Alias> processing
1932 matches every subsystem
1936 BSM and Linux audit code
1944 I<sudoers> I<Defaults> settings
1948 environment handling
1960 matching of users, groups, hosts and netgroups in I<sudoers>
1964 network interface handling
1968 network service switch handling in I<sudoers>
1972 I<sudoers> file parsing
1980 The equivalent of I<main> for the plugin.
1984 pseudo-tty related code
1988 redblack tree internals
1996 =head1 SECURITY NOTES
1998 I<sudoers> will check the ownership of its time stamp directory
1999 (F<@timedir@> by default) and ignore the directory's contents if
2000 it is not owned by root or if it is writable by a user other than
2001 root. On systems that allow non-root users to give away files via
2002 L<chown(2)>, if the time stamp directory is located in a world-writable
2003 directory (e.g., F</tmp>), it is possible for a user to create the
2004 time stamp directory before B<sudo> is run. However, because
2005 I<sudoers> checks the ownership and mode of the directory and its
2006 contents, the only damage that can be done is to "hide" files by
2007 putting them in the time stamp dir. This is unlikely to happen
2008 since once the time stamp dir is owned by root and inaccessible by
2009 any other user, the user placing files there would be unable to get
2012 I<sudoers> will not honor time stamps set far in the future. Time
2013 stamps with a date greater than current_time + 2 * C<TIMEOUT> will
2014 be ignored and sudo will log and complain. This is done to keep a
2015 user from creating his/her own time stamp with a bogus date on
2016 systems that allow users to give away files if the time stamp directory
2017 is located in a world-writable directory.
2019 On systems where the boot time is available, I<sudoers> will ignore
2020 time stamps that date from before the machine booted.
2022 Since time stamp files live in the file system, they can outlive a
2023 user's login session. As a result, a user may be able to login,
2024 run a command with B<sudo> after authenticating, logout, login
2025 again, and run B<sudo> without authenticating so long as the time
2026 stamp file's modification time is within C<@timeout@> minutes (or
2027 whatever the timeout is set to in I<sudoers>). When the I<tty_tickets>
2028 option is enabled, the time stamp has per-tty granularity but still
2029 may outlive the user's session. On Linux systems where the devpts
2030 filesystem is used, Solaris systems with the devices filesystem,
2031 as well as other systems that utilize a devfs filesystem that
2032 monotonically increase the inode number of devices as they are
2033 created (such as Mac OS X), I<sudoers> is able to determine when a
2034 tty-based time stamp file is stale and will ignore it. Administrators
2035 should not rely on this feature as it is not universally available.
2037 If users have sudo C<ALL> there is nothing to prevent them from
2038 creating their own program that gives them a root shell (or making
2039 their own copy of a shell) regardless of any '!' elements in the
2044 L<rsh(1)>, L<su(1)>, L<fnmatch(3)>, L<glob(3)>, L<mktemp(3)>, L<strftime(3)>,
2045 L<sudoers.ldap(5)>, L<sudo_plugin(8)>, L<sudo(8)>, L<visudo(8)>
2049 The I<sudoers> file should B<always> be edited by the B<visudo>
2050 command which locks the file and does grammatical checking. It is
2051 imperative that I<sudoers> be free of syntax errors since B<sudo>
2052 will not run with a syntactically incorrect I<sudoers> file.
2054 When using netgroups of machines (as opposed to users), if you
2055 store fully qualified host name in the netgroup (as is usually the
2056 case), you either need to have the machine's host name be fully qualified
2057 as returned by the C<hostname> command or use the I<fqdn> option in
2062 If you feel you have found a bug in B<sudo>, please submit a bug report
2063 at http://www.sudo.ws/sudo/bugs/
2067 Limited free support is available via the sudo-users mailing list,
2068 see http://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or
2069 search the archives.
2073 B<sudo> is provided ``AS IS'' and any express or implied warranties,
2074 including, but not limited to, the implied warranties of merchantability
2075 and fitness for a particular purpose are disclaimed. See the LICENSE
2076 file distributed with B<sudo> or http://www.sudo.ws/sudo/license.html
2077 for complete details.