-Copyright (c) 1994-1996, 1998-2005, 2007-2009
+Copyright (c) 1994-1996, 1998-2005, 2007-2010
Todd C. Miller <Todd.Miller@courtesan.com>
Permission to use, copy, modify, and distribute this software for any
Agency (DARPA) and Air Force Research Laboratory, Air Force
Materiel Command, USAF, under agreement number F39502-99-1-0512.
-$Sudo: sudoers.pod,v 1.173 2009/06/30 12:41:09 millert Exp $
=pod
=head1 NAME
User_List ::= User |
User ',' User_List
- User ::= '!'* username |
+ User ::= '!'* user name |
'!'* '#'uid |
'!'* '%'group |
'!'* '+'netgroup |
'!'* '%:'nonunix_group |
'!'* User_Alias
-A C<User_List> is made up of one or more usernames, uids (prefixed
+A C<User_List> is made up of one or more user names, uids (prefixed
with '#'), system groups (prefixed with '%'), netgroups (prefixed
with '+') and C<User_Alias>es. Each list item may be prefixed with
zero or more '!' operators. An odd number of '!' operators negate
the value of the item; an even number just cancel each other out.
-A C<username>, C<group>, C<netgroup> and C<nonunix_groups> may
+A C<user name>, C<group>, C<netgroup> or C<nonunix_group> may
be enclosed in double quotes to avoid the need for escaping special
characters. Alternately, special characters may be specified in
escaped hex mode, e.g. \x20 for space.
Runas_List ::= Runas_Member |
Runas_Member ',' Runas_List
- Runas_Member ::= '!'* username |
+ Runas_Member ::= '!'* user name |
'!'* '#'uid |
'!'* '%'group |
'!'* +netgroup |
A C<Runas_List> is similar to a C<User_List> except that instead
of C<User_Alias>es it can contain C<Runas_Alias>es. Note that
-usernames and groups are matched as strings. In other words, two
+user names and groups are matched as strings. In other words, two
users (groups) with the same uid (gid) are considered to be distinct.
-If you wish to match all usernames with the same uid (e.g.E<nbsp>root
+If you wish to match all user names with the same uid (e.g.E<nbsp>root
and toor), you can use a uid instead (#0 in the example given).
Host_List ::= Host |
Host ',' Host_List
- Host ::= '!'* hostname |
+ Host ::= '!'* host name |
'!'* ip_addr |
'!'* network(/netmask)? |
'!'* '+'netgroup |
'!'* Host_Alias
-A C<Host_List> is made up of one or more hostnames, IP addresses,
+A C<Host_List> is made up of one or more host names, IP addresses,
network numbers, netgroups (prefixed with '+') and other aliases.
Again, the value of an item may be negated with the '!' operator.
If you do not specify a netmask along with the network number,
interfaces, the corresponding netmask will be used. The netmask
may be specified either in standard IP address notation
(e.g.E<nbsp>255.255.255.0 or ffff:ffff:ffff:ffff::),
-or CIDR notation (number of bits, e.g.E<nbsp>24 or 64). A hostname may
+or CIDR notation (number of bits, e.g.E<nbsp>24 or 64). A host name may
include shell-style wildcards (see the L<Wildcards> section below),
-but unless the C<hostname> command on your machine returns the fully
-qualified hostname, you'll need to use the I<fqdn> option for
-wildcards to be useful.
+but unless the C<host name> command on your machine returns the fully
+qualified host name, you'll need to use the I<fqdn> option for
+wildcards to be useful. Note B<sudo> only inspects actual network
+interfaces; this means that IP address 127.0.0.1 (localhost) will
+never match. Also, the host name "localhost" will only match if
+that is the actual host name, which is usually only the case for
+non-networked systems.
Cmnd_List ::= Cmnd |
Cmnd ',' Cmnd_List
- commandname ::= filename |
- filename args |
- filename '""'
+ commandname ::= file name |
+ file name args |
+ file name '""'
Cmnd ::= '!'* commandname |
'!'* directory |
'!'* Cmnd_Alias
A C<Cmnd_List> is a list of one or more commandnames, directories, and other
-aliases. A commandname is a fully qualified filename which may include
+aliases. A commandname is a fully qualified file name which may include
shell-style wildcards (see the L<Wildcards> section below). A simple
-filename allows the user to run the command with any arguments he/she
+file name allows the user to run the command with any arguments he/she
wishes. However, you may also specify command line arguments (including
wildcards). Alternately, you can specify C<""> to indicate that the command
may only be run B<without> command line arguments. A directory is a
-fully qualified pathname ending in a '/'. When you specify a directory
+fully qualified path name ending in a '/'. When you specify a directory
in a C<Cmnd_List>, the user will be able to run any file within that directory
(but not in any subdirectories therein).
Cmnd_Spec_List ::= Cmnd_Spec |
Cmnd_Spec ',' Cmnd_Spec_List
- Cmnd_Spec ::= Runas_Spec? Tag_Spec* Cmnd
+ Cmnd_Spec ::= Runas_Spec? SELinux_Spec? Tag_Spec* Cmnd
Runas_Spec ::= '(' Runas_List? (':' Runas_List)? ')'
+ SELinux_Spec ::= ('ROLE=role' | 'TYPE=type')
+
Tag_Spec ::= ('NOPASSWD:' | 'PASSWD:' | 'NOEXEC:' | 'EXEC:' |
- 'SETENV:' | 'NOSETENV:' )
+ 'SETENV:' | 'NOSETENV:' | 'LOG_INPUT:' | 'NOLOG_INPUT:' |
+ 'LOG_OUTPUT:' | 'NOLOG_OUTPUT:')
A B<user specification> determines which commands a user may run
(and as what user) on specified hosts. By default, commands are
tcm boulder = (:dialer) /usr/bin/tip, /usr/bin/cu, \
/usr/local/bin/minicom
+=head2 SELinux_Spec
+
+On systems with SELinux support, I<sudoers> entries may optionally have
+an SELinux role and/or type associated with a command. If a role or
+type is specified with the command it will override any default values
+specified in I<sudoers>. A role or type specified on the command line,
+however, will supercede the values in I<sudoers>.
+
=head2 Tag_Spec
A command may have zero or more tags associated with it. There are
-eight possible tag values, C<NOPASSWD>, C<PASSWD>, C<NOEXEC>, C<EXEC>,
-C<SETENV> and C<NOSETENV>.
-Once a tag is set on a C<Cmnd>, subsequent C<Cmnd>s in the
-C<Cmnd_Spec_List>, inherit the tag unless it is overridden by the
-opposite tag (i.e.: C<PASSWD> overrides C<NOPASSWD> and C<NOEXEC>
-overrides C<EXEC>).
+eight possible tag values, C<NOPASSWD>, C<PASSWD>, C<NOEXEC>,
+C<EXEC>, C<SETENV>, C<NOSETENV>, C<LOG_INPUT>, C<NOLOG_INPUT>,
+C<LOG_OUTPUT> and C<NOLOG_OUTPUT>. Once a tag is set on a C<Cmnd>,
+subsequent C<Cmnd>s in the C<Cmnd_Spec_List>, inherit the tag unless
+it is overridden by the opposite tag (i.e.: C<PASSWD> overrides
+C<NOPASSWD> and C<NOEXEC> overrides C<EXEC>).
=head3 NOPASSWD and PASSWD
I<env_keep>. As such, only trusted users should be allowed to set
variables in this manner. If the command matched is B<ALL>, the
C<SETENV> tag is implied for that command; this default may
-be overridden by use of the C<UNSETENV> tag.
+be overridden by use of the C<NOSETENV> tag.
+
+=head3 LOG_INPUT and NOLOG_INPUT
+
+These tags override the value of the I<log_input> option on a
+per-command basis. For more information, see the description of
+I<log_input> in the L<"SUDOERS OPTIONS"> section below.
+
+=head3 LOG_OUTPUT and NOLOG_OUTPUT
+
+These tags override the value of the I<log_output> option on a
+per-command basis. For more information, see the description of
+I<log_output> in the L<"SUDOERS OPTIONS"> section below.
=head2 Wildcards
B<sudo> allows shell-style I<wildcards> (aka meta or glob characters)
-to be used in hostnames, pathnames and command line arguments in
+to be used in host names, path names and command line arguments in
the I<sudoers> file. Wildcard matching is done via the B<POSIX>
L<glob(3)> and L<fnmatch(3)> routines. Note that these are I<not>
regular expressions.
/bin/ls [[\:alpha\:]]*
-Would match any filename beginning with a letter.
+Would match any file name beginning with a letter.
Note that a forward slash ('/') will B<not> be matched by
-wildcards used in the pathname. When matching the command
+wildcards used in the path name. When matching the command
line arguments, however, a slash B<does> get matched by
wildcards. This is to make a path like:
themselves include other files. A hard limit of 128 nested include
files is enforced to prevent include file loops.
-The filename may include the C<%h> escape, signifying the short form
-of the hostname. I.e., if the machine's hostname is "xerxes", then
+The file name may include the C<%h> escape, signifying the short form
+of the host name. I.e., if the machine's host name is "xerxes", then
C<#include /etc/sudoers.%h>
characters in a I<User Specification> ('=', ':', '(', ')') is optional.
The following characters must be escaped with a backslash ('\') when
-used as part of a word (e.g.E<nbsp>a username or hostname):
+used as part of a word (e.g.E<nbsp>a user name or host name):
'@', '!', '=', ':', ',', '(', ')', '\'.
=head1 SUDOERS OPTIONS
explained earlier. A list of all supported Defaults parameters,
grouped by type, are listed below.
-B<Flags>:
+B<Boolean Flags>:
=over 16
=item always_set_home
-If set, B<sudo> will set the C<HOME> environment variable to the home
-directory of the target user (which is root unless the B<-u> option is used).
-This effectively means that the B<-H> option is always implied.
+If enabled, B<sudo> will set the C<HOME> environment variable to the
+home directory of the target user (which is root unless the B<-u>
+option is used). This effectively means that the B<-H> option is
+always implied. Note that C<HOME> is already set when the the
+I<env_reset> option is enabled, so I<always_set_home> is only
+effective for configurations where I<env_reset> is disabled.
This flag is I<off> by default.
=item authenticate
overrides the default starting point at which B<sudo> begins
closing open file descriptors. This flag is I<off> by default.
+=item compress_io
+
+If set, and B<sudo> is configured to log a command's input or output,
+the I/O logs will be compressed using B<zlib>. This flag is I<on>
+by default when B<sudo> is compiled with B<zlib> support.
+
=item env_editor
If set, B<visudo> will use the value of the EDITOR or VISUAL
=item env_reset
If set, B<sudo> will reset the environment to only contain the
-LOGNAME, SHELL, USER, USERNAME and the C<SUDO_*> variables. Any
+LOGNAME, MAIL, SHELL, USER, USERNAME and the C<SUDO_*> variables. Any
variables in the caller's environment that match the C<env_keep>
and C<env_check> lists are then added. The default contents of the
C<env_keep> and C<env_check> lists are displayed when B<sudo> is
is set, its value will be used for the C<PATH> environment variable.
This flag is I<on> by default.
+=item fast_glob
+
+Normally, B<sudo> uses the L<glob(3)> function to do shell-style
+globbing when matching path names. However, since it accesses the
+file system, L<glob(3)> can take a long time to complete for some
+patterns, especially when the pattern references a network file
+system that is mounted on demand (automounted). The I<fast_glob>
+option causes B<sudo> to use the L<fnmatch(3)> function, which does
+not access the file system to do its matching. The disadvantage
+of I<fast_glob> is that it is unable to match relative path names
+such as F<./ls> or F<../bin/ls>. This has security implications
+when path names that include globbing characters are used with the
+negation operator, C<'!'>, as such rules can be trivially bypassed.
+As such, this option should not be used when I<sudoers> contains rules
+that contain negated path names which include globbing characters.
+This flag is I<off> by default.
+
=item fqdn
-Set this flag if you want to put fully qualified hostnames in the
+Set this flag if you want to put fully qualified host names in the
I<sudoers> file. I.e., instead of myhost you would use myhost.mydomain.edu.
You may still use the short form if you wish (and even mix the two).
Beware that turning on I<fqdn> requires B<sudo> to make DNS lookups
you must use the host's official name as DNS knows it. That is,
you may not use a host alias (C<CNAME> entry) due to performance
issues and the fact that there is no way to get all aliases from
-DNS. If your machine's hostname (as returned by the C<hostname>
+DNS. If your machine's host name (as returned by the C<hostname>
command) is already fully qualified you shouldn't need to set
I<fqdn>. This flag is I<@fqdn@> by default.
=item log_host
-If set, the hostname will be logged in the (non-syslog) B<sudo> log file.
+If set, the host name will be logged in the (non-syslog) B<sudo> log file.
This flag is I<off> by default.
=item log_year
=item passprompt_override
The password prompt specified by I<passprompt> will normally only
-be used if the passwod prompt provided by systems such as PAM matches
+be used if the password prompt provided by systems such as PAM matches
the string "Password:". If I<passprompt_override> is set, I<passprompt>
will always be used. This flag is I<off> by default.
=item set_home
-If set and B<sudo> is invoked with the B<-s> option the C<HOME>
+If enabled and B<sudo> is invoked with the B<-s> option the C<HOME>
environment variable will be set to the home directory of the target
user (which is root unless the B<-u> option is used). This effectively
-makes the B<-s> option imply B<-H>. This flag is I<off> by default.
+makes the B<-s> option imply B<-H>. Note that C<HOME> is already
+set when the the I<env_reset> option is enabled, so I<set_home> is
+only effective for configurations where I<env_reset> is disabled.
+This flag is I<off> by default.
=item set_logname
change this behavior. This can be done by negating the set_logname
option. Note that if the I<env_reset> option has not been disabled,
entries in the I<env_keep> list will override the value of
-I<set_logname>. This flag is I<off> by default.
+I<set_logname>. This flag is I<on> by default.
=item setenv
set, falling back on the shell listed in the invoking user's
/etc/passwd entry if not). This flag is I<off> by default.
-=item fast_glob
-
-Normally, B<sudo> uses the L<glob(3)> function to do shell-style
-globbing when matching pathnames. However, since it accesses the
-file system, L<glob(3)> can take a long time to complete for some
-patterns, especially when the pattern references a network file
-system that is mounted on demand (automounted). The I<fast_glob>
-option causes B<sudo> to use the L<fnmatch(3)> function, which does
-not access the file system to do its matching. The disadvantage
-of I<fast_glob> is that it is unable to match relative pathnames
-such as F<./ls> or F<../bin/ls>. This flag is I<off> by default.
-
=item stay_setuid
Normally, when B<sudo> executes a command the real and effective
=item targetpw
-If set, B<sudo> will prompt for the password of the user specified by
-the B<-u> option (defaults to C<root>) instead of the password of the
-invoking user. Note that this precludes the use of a uid not listed
-in the passwd database as an argument to the B<-u> option.
-This flag is I<off> by default.
+If set, B<sudo> will prompt for the password of the user specified
+by the B<-u> option (defaults to C<root>) instead of the password
+of the invoking user. In addition, the timestamp file name will
+include the target user's name. Note that this flag precludes the
+use of a uid not listed in the passwd database as an argument to
+the B<-u> option. This flag is I<off> by default.
+
+=item log_input
+
+If set, B<sudo> will run the command in a I<pseudo tty> and log all
+user input.
+If the standard input is not connected to the user's tty, due to
+I/O redirection or because the command is part of a pipeline, that
+input is also captured and stored in a separate log file.
+
+Input is logged to the F</var/log/sudo-io> directory using a unique
+session ID that is included in the normal B<sudo> log line, prefixed
+with I<TSID=>.
+
+=item log_output
+
+If set, B<sudo> will run the command in a I<pseudo tty> and log all
+output that is sent to the screen, similar to the script(1) command.
+If the standard output or standard error is not connected to the
+user's tty, due to I/O redirection or because the command is part
+of a pipeline, that output is also captured and stored in separate
+log files.
+
+Output is logged to the
+F</var/log/sudo-io> directory using a unique session ID that is
+included in the normal B<sudo> log line, prefixed with I<TSID=>.
+
+Output logs may be viewed with the L<sudoreplay(8)> utility, which
+can also be used to list or search the available logs.
=item tty_tickets
-If set, users must authenticate on a per-tty basis. Normally,
-B<sudo> uses a directory in the ticket dir with the same name as
-the user running it. With this flag enabled, B<sudo> will use a
-file named for the tty the user is logged in on in that directory.
-This flag is I<@tty_tickets@> by default.
+If set, users must authenticate on a per-tty basis. With this flag
+enabled, B<sudo> will use a file named for the tty the user is
+logged in on in the user's time stamp directory. If disabled, the
+time stamp of the directory is used instead. This flag is
+I<@tty_tickets@> by default.
=item umask_override
login class if one exists. Only available if B<sudo> is configured with
the --with-logincap option. This flag is I<off> by default.
+=item use_pty
+
+If set, B<sudo> will run the command in a pseudo-pty even if no I/O
+logging is being gone. A malicious program run under B<sudo> could
+conceivably fork a background process that retains to the user's
+terminal device after the main program has finished executing. Use
+of this option will make that impossible.
+
=item visiblepw
By default, B<sudo> will refuse to run if the user must enter a
=item passwd_timeout
-Number of minutes before the B<sudo> password prompt times out.
-The default is C<@password_timeout@>; set this to C<0> for no password timeout.
+Number of minutes before the B<sudo> password prompt times out, or
+C<0> for no timeout. The timeout may include a fractional component
+if minute granularity is insufficient, for example C<2.5>. The
+default is C<@password_timeout@>.
=item timestamp_timeout
Number of minutes that can elapse before B<sudo> will ask for a
-passwd again. The default is C<@timeout@>. Set this to C<0> to always
-prompt for a password.
+passwd again. The timeout may include a fractional component if
+minute granularity is insufficient, for example C<2.5>. The default
+is C<@timeout@>. Set this to C<0> to always prompt for a password.
If set to a value less than C<0> the user's timestamp will never
expire. This can be used to allow users to create or delete their
own timestamps via C<sudo -v> and C<sudo -k> respectively.
Umask to use when running the command. Negate this option or set
it to 0777 to preserve the user's umask. The actual umask that is
-used will be the union of the user's umask and C<@sudo_umask@>.
-This guarantees that B<sudo> never lowers the umask when running a
-command. Note on systems that use PAM, the default PAM configuration
-may specify its own umask which will override the value set in
-I<sudoers>.
+used will be the union of the user's umask and the value of the
+I<umask> option, which defaults to C<@sudo_umask@>. This guarantees
+that B<sudo> never lowers the umask when running a command. Note
+on systems that use PAM, the default PAM configuration may specify
+its own umask which will override the value set in I<sudoers>.
=back
A colon (':') separated list of editors allowed to be used with
B<visudo>. B<visudo> will choose the editor that matches the user's
EDITOR environment variable if possible, or the first editor in the
-list that exists and is executable. The default is the path to vi
-on your system.
+list that exists and is executable. The default is C<"@editor@">.
=item mailsub
Subject of the mail sent to the I<mailto> user. The escape C<%h>
-will expand to the hostname of the machine.
+will expand to the host name of the machine.
Default is C<@mailsub@>.
=item noexec_file
=item C<%H>
-expanded to the local hostname including the domain name
-(on if the machine's hostname is fully qualified or the I<fqdn>
+expanded to the local host name including the domain name
+(on if the machine's host name is fully qualified or the I<fqdn>
option is set)
=item C<%h>
-expanded to the local hostname without the domain name
+expanded to the local host name without the domain name
=item C<%p>
List of network groups
+=item F</var/log/sudo-io>
+
+I/O log files
+
=back
=head1 EXAMPLES
Below are example I<sudoers> entries. Admittedly, some of
-these are a bit contrived. First, we define our I<aliases>:
+these are a bit contrived. First, we allow a few environment
+variables to pass and then define our I<aliases>:
+
+ # Run X applications through sudo; HOME is used to find the
+ # .Xauthority file. Note that other programs use HOME to find
+ # configuration files and this may lead to privilege escalation!
+ Defaults env_keep += "DISPLAY HOME"
# User alias specification
User_Alias FULLTIMERS = millert, mikef, dowdy
The user B<pete> is allowed to change anyone's password except for
root on the I<HPPA> machines. Note that this assumes L<passwd(1)>
-does not take multiple usernames on the command line.
+does not take multiple user names on the command line.
bob SPARC = (OP) ALL : SGI = (OP) ALL
program. Therefore, these kind of restrictions should be considered
advisory at best (and reinforced by policy).
+Furthermore, if the I<fast_glob> option is in use, it is not possible
+to reliably negate commands where the path name includes globbing
+(aka wildcard) characters. This is because the C library's
+L<fnmatch(3)> function cannot resolve relative paths. While this
+is typically only an inconvenience for rules that grant privileges,
+it can result in a security issue for rules that subtract or revoke
+privileges.
+
+For example, given the following I<sudoers> entry:
+
+ john ALL = /usr/bin/passwd [a-zA-Z0-9]*, /usr/bin/chsh [a-zA-Z0-9]*,
+ /usr/bin/chfn [a-zA-Z0-9]*, !/usr/bin/* root
+
+User B<john> can still run C</usr/bin/passwd root> if I<fast_glob> is
+enabled by changing to F</usr/bin> and running C<./passwd root> instead.
+
=head1 PREVENTING SHELL ESCAPES
Once B<sudo> executes a program, that program is free to do whatever
escapes are disabled, though B<sudoedit> is a better solution to
running editors via B<sudo>. Due to the large number of programs that
offer shell escapes, restricting users to the set of programs that
-do not if often unworkable.
+do not is often unworkable.
=item noexec
will not run with a syntactically incorrect I<sudoers> file.
When using netgroups of machines (as opposed to users), if you
-store fully qualified hostnames in the netgroup (as is usually the
-case), you either need to have the machine's hostname be fully qualified
+store fully qualified host name in the netgroup (as is usually the
+case), you either need to have the machine's host name be fully qualified
as returned by the C<hostname> command or use the I<fqdn> option in
I<sudoers>.
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