path: root/docs/sudoers.man.in

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.\" Copyright (c) 1994-1996, 1998-2005, 2007-2023
.\"	Todd C. Miller <Todd.Miller@sudo.ws>
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.nr SL @SEMAN@
.nr BA @BAMAN@
.nr LC @LCMAN@
.nr PS @PSMAN@
.TH "SUDOERS" "@mansectform@" "January 16, 2023" "Sudo @PACKAGE_VERSION@" "File Formats Manual"
.nh
.if n .ad l
.SH "NAME"
\fBsudoers\fR
\- default sudo security policy plugin
.SH "DESCRIPTION"
The
\fBsudoers\fR
policy plugin determines a user's
\fBsudo\fR
privileges.
It is the default
\fBsudo\fR
policy plugin.
The policy is driven by
the
\fI@sysconfdir@/sudoers\fR
file or, optionally, in LDAP.
The policy format is described in detail in the
\fISUDOERS FILE FORMAT\fR
section.
For information on storing
\fBsudoers\fR
policy information
in LDAP, see
sudoers.ldap(@mansectform@).
.SS "Configuring sudo.conf for sudoers"
\fBsudo\fR
consults the
sudo.conf(@mansectform@)
file to determine which plugins to load.
If no
sudo.conf(@mansectform@)
file is present, or if it contains no
\fIPlugin\fR
lines,
\fBsudoers\fR
will be used for auditing, policy decisions and I/O logging.
To explicitly configure
sudo.conf(@mansectform@)
to use the
\fBsudoers\fR
plugin, the following configuration can be used.
.nf
.sp
.RS 4n
Plugin sudoers_audit @sudoers_plugin@
Plugin sudoers_policy @sudoers_plugin@
Plugin sudoers_io @sudoers_plugin@
.RE
.fi
.PP
Starting with
\fBsudo\fR
1.8.5, it is possible to specify optional arguments to the
\fBsudoers\fR
plugin in the
sudo.conf(@mansectform@)
file.
Plugin arguments, if any, should be listed after the path to the plugin
(i.e., after
\fI@sudoers_plugin@\fR).
The arguments are only effective for the plugin that opens (and parses) the
\fIsudoers\fR
file.
.PP
For
\fBsudo\fR
version 1.9.1 and higher, this is the
\fIsudoers_audit\fR
plugin.
For older versions, it is the
\fIsudoers_policy\fR
plugin.
Multiple arguments may be specified, separated by white space.
For example:
.nf
.sp
.RS 4n
Plugin sudoers_audit @sudoers_plugin@ sudoers_mode=0400 error_recovery=false
.RE
.fi
.PP
The following plugin arguments are supported:
.TP 6n
error_recovery=bool
The
\fIerror_recovery\fR
argument can be used to control whether
\fBsudoers\fR
should attempt to recover from syntax errors in the
\fIsudoers\fR
file.
If set to
\fItrue\fR
(the default),
\fBsudoers\fR
will try to recover from a syntax error by discarding the portion
of the line that contains the error until the end of the line.
A value of
\fIfalse\fR
will disable error recovery.
Prior to version 1.9.3, no error recovery was performed.
.TP 6n
ldap_conf=pathname
The
\fIldap_conf\fR
argument can be used to override the default path to the
\fIldap.conf\fR
file.
.TP 6n
ldap_secret=pathname
The
\fIldap_secret\fR
argument can be used to override the default path to the
\fIldap.secret\fR
file.
.TP 6n
sudoers_file=pathname
The
\fIsudoers_file\fR
argument can be used to override the default path to the
\fIsudoers\fR
file.
.TP 6n
sudoers_uid=user-ID
The
\fIsudoers_uid\fR
argument can be used to override the default owner of the sudoers file.
It should be specified as a numeric user-ID.
.TP 6n
sudoers_gid=group-ID
The
\fIsudoers_gid\fR
argument can be used to override the default group of the sudoers file.
It must be specified as a numeric group-ID (not a group name).
.TP 6n
sudoers_mode=mode
The
\fIsudoers_mode\fR
argument can be used to override the default file mode for the sudoers file.
It should be specified as an octal value.
.PP
For more information on configuring
sudo.conf(@mansectform@),
refer to its manual.
.SS "User Authentication"
The
\fBsudoers\fR
security policy requires that most users authenticate
themselves before they can use
\fBsudo\fR.
A password is not required
if the invoking user is
\fBroot\fR,
if the target user is the same as the invoking user, or if the
policy has disabled authentication for the user or command.
Unlike
su(1),
when
\fBsudoers\fR
requires
authentication, it validates the invoking user's credentials, not
the target user's (or
\fB@runas_default@\fR's)
credentials.
This can be changed via
the
\fIrootpw\fR,
\fItargetpw\fR
and
\fIrunaspw\fR
flags, described later.
.PP
If a user who is not listed in the policy tries to run a command
via
\fBsudo\fR,
mail is sent to the proper authorities.
The address
used for such mail is configurable via the
\fImailto\fR
Defaults entry
(described later) and defaults to
\fI@mailto@\fR.
.PP
No mail will be sent if an unauthorized user tries to run
\fBsudo\fR
with the
\fB\-l\fR
or
\fB\-v\fR
option unless there is an authentication error and
either the
\fImail_always\fR
or
\fImail_badpass\fR
flags are enabled.
This allows users to
determine for themselves whether or not they are allowed to use
\fBsudo\fR.
By default, all attempts to run
\fBsudo\fR
(successful or not)
are logged, regardless of whether or not mail is sent.
.PP
If
\fBsudo\fR
is run by
\fBroot\fR
and the
\fRSUDO_USER\fR
environment variable
is set, the
\fBsudoers\fR
policy will use this value to determine who
the actual user is.
This can be used by a user to log commands
through sudo even when a
\fBroot\fR
shell has been invoked.
It also
allows the
\fB\-e\fR
option to remain useful even when invoked via a
sudo-run script or program.
Note, however, that the
\fIsudoers\fR
file lookup is still done for
\fBroot\fR,
not the user specified by
\fRSUDO_USER\fR.
.PP
\fBsudoers\fR
uses per-user time stamp files for credential caching.
Once a user has been authenticated, a record is written
containing the user-ID that was used to authenticate, the
terminal session ID, the start time of the session leader
(or parent process) and a time stamp
(using a monotonic clock if one is available).
The user may then use
\fBsudo\fR
without a password for a short period of time (@timeout@ minutes
unless overridden by the
\fItimestamp_timeout\fR
option).
By default,
\fBsudoers\fR
uses a separate record for each terminal, which means that
a user's login sessions are authenticated separately.
The
\fItimestamp_type\fR
option can be used to select the type of time stamp record
\fBsudoers\fR
will use.
.SS "Logging"
By default,
\fBsudoers\fR
logs both successful and unsuccessful attempts (as well
as errors).
The
\fIlog_allowed\fR
and
\fIlog_denied\fR
flags can be used to control this behavior.
Messages can be logged to
syslog(3),
a log file, or both.
The default is to log to
syslog(3)
but this is configurable via the
\fIsyslog\fR
and
\fIlogfile\fR
settings.
See
\fIEVENT LOGGING\fR
for a description of the log file format.
.PP
\fBsudoers\fR
is also capable of running a command in a pseudo-terminal and logging
input and/or output.
The standard input, standard output, and standard error can be logged
even when not associated with a terminal.
For more information about I/O logging, see the
\fII/O LOGGING\fR
section.
.PP
Starting with version 1.9, the
\fIlog_servers\fR
setting may be used to send event and I/O log data to a remote server running
\fBsudo_logsrvd\fR
or another service that implements the protocol described by
sudo_logsrv.proto(@mansectform@).
.SS "Command environment"
Since environment variables can influence program behavior,
\fBsudoers\fR
provides a means to restrict which variables from the user's
environment are inherited by the command to be run.
There are two
distinct ways
\fBsudoers\fR
can deal with environment variables.
.PP
By default, the
\fIenv_reset\fR
flag is enabled.
This causes commands
to be executed with a new, minimal environment.
On AIX (and Linux
systems without PAM), the environment is initialized with the
contents of the
\fI/etc/environment\fR
file.
.if \n(LC \{\
On
BSD
systems, if the
\fIuse_loginclass\fR
flag is enabled, the environment is initialized
based on the
\fIpath\fR
and
\fIsetenv\fR
settings in
\fI/etc/login.conf\fR.
.\}
The
\fRHOME\fR,
\fRMAIL\fR,
\fRSHELL\fR,
\fRLOGNAME\fR
and
\fRUSER\fR
environment variables are initialized based on the target user
and the
\fRSUDO_*\fR
variables are set based on the invoking user.
Additional variables, such as
\fRDISPLAY\fR,
\fRPATH\fR
and
\fRTERM\fR,
are preserved from the invoking user's environment if permitted by the
\fIenv_check\fR,
or
\fIenv_keep\fR
options.
A few environment variables are treated specially.
If the
\fRPATH\fR
and
\fRTERM\fR
variables are not preserved from the user's environment, they will be set
to default values.
The
\fRLOGNAME\fR
and
\fRUSER\fR
are handled as a single entity.
If one of them is preserved (or removed) from the user's environment,
the other will be as well.
If
\fRLOGNAME\fR
and
\fRUSER\fR
are to be preserved but only one of them is present in the user's environment,
the other will be set to the same value.
This avoids an inconsistent environment where one of the variables
describing the user name is set to the invoking user and one is
set to the target user.
Environment variables with a value beginning with
\(oq()\(cq
are removed unless both the name and value parts are matched by
\fIenv_keep\fR
or
\fIenv_check\fR,
as they may be interpreted as functions by the
\fBbash\fR
shell.
Prior to version 1.8.11, such variables were always removed.
.PP
If, however, the
\fIenv_reset\fR
flag is disabled, any variables not
explicitly denied by the
\fIenv_check\fR
and
\fIenv_delete\fR
options are allowed and their values are
inherited from the invoking process.
Prior to version 1.8.21, environment variables with a value beginning with
\(oq()\(cq
were always removed.
Beginning with version 1.8.21, a pattern in
\fIenv_delete\fR
is used to match
\fBbash\fR
shell functions instead.
Since it is not possible
to block all potentially dangerous environment variables, use
of the default
\fIenv_reset\fR
behavior is encouraged.
.PP
Environment variables specified by
\fIenv_check\fR,
\fIenv_delete\fR,
or
\fIenv_keep\fR
may include one or more
\(oq*\(cq
characters which will match zero or more characters.
No other wildcard characters are supported.
.PP
By default, environment variables are matched by name.
However, if the pattern includes an equal sign
(\(oq=\&\(cq),
both the variables name and value must match.
For example, a
\fBbash\fR
shell function could be matched as follows:
.nf
.sp
.RS 4n
env_keep += "BASH_FUNC_my_func%%=()*"
.RE
.fi
.PP
Without the
\(oq=()*\(cq
suffix, this would not match, as
\fBbash\fR
shell functions are not preserved by default.
.PP
The complete list of environment variables that are preserved or removed,
as modified by global Defaults parameters in
\fIsudoers\fR,
is displayed when
\fBsudo\fR
is run by
\fBroot\fR
with the
\fB\-V\fR
option.
The list of environment variables to remove
varies based on the operating system
\fBsudo\fR
is running on.
.PP
Other
\fBsudoers\fR
options may influence the command environment, such as
\fIalways_set_home\fR,
\fIsecure_path\fR,
\fIset_logname\fR,
and
\fIset_home\fR.
.PP
On systems that support PAM where the
\fBpam_env\fR
module is enabled for
\fBsudo\fR,
variables in the PAM environment may be merged in to the environment.
If a variable in the PAM environment is already present in the
user's environment, the value will only be overridden if the variable
was not preserved by
\fBsudoers\fR.
When
\fIenv_reset\fR
is enabled, variables preserved from the invoking user's environment
by the
\fIenv_keep\fR
list take precedence over those in the PAM environment.
When
\fIenv_reset\fR
is disabled, variables present the invoking user's environment
take precedence over those in the PAM environment unless they
match a pattern in the
\fIenv_delete\fR
list.
.PP
The dynamic linker on most operating systems will remove variables
that can control dynamic linking from the environment of set-user-ID
executables, including
\fBsudo\fR.
Depending on the operating
system this may include
\fR_RLD*\fR,
\fRDYLD_*\fR,
\fRLD_*\fR,
\fRLDR_*\fR,
\fRLIBPATH\fR,
\fRSHLIB_PATH\fR,
and others.
These type of variables are
removed from the environment before
\fBsudo\fR
even begins execution
and, as such, it is not possible for
\fBsudo\fR
to preserve them.
.PP
As a special case, if the
\fB\-i\fR
option (initial login) is
specified,
\fBsudoers\fR
will initialize the environment regardless
of the value of
\fIenv_reset\fR.
The
\fRDISPLAY\fR,
\fRPATH\fR
and
\fRTERM\fR
variables remain unchanged;
\fRHOME\fR,
\fRMAIL\fR,
\fRSHELL\fR,
\fRUSER\fR,
and
\fRLOGNAME\fR
are set based on the target user.
On AIX (and Linux
systems without PAM), the contents of
\fI/etc/environment\fR
are also
included.
.if \n(LC \{\
On
BSD
systems, if the
\fIuse_loginclass\fR
flag is
enabled, the
\fIpath\fR
and
\fIsetenv\fR
variables in
\fI/etc/login.conf\fR
are also applied.
.\}
All other environment variables are removed unless permitted by
\fIenv_keep\fR
or
\fIenv_check\fR,
described above.
.PP
Finally, the
\fIrestricted_env_file\fR
and
\fIenv_file\fR
files are applied, if present.
The variables in
\fIrestricted_env_file\fR
are applied first and are subject to the same restrictions as the
invoking user's environment, as detailed above.
The variables in
\fIenv_file\fR
are applied last and are not subject to these restrictions.
In both cases, variables present in the files will only be set to
their specified values if they would not conflict with an existing
environment variable.
.SH "SUDOERS FILE FORMAT"
The
\fIsudoers\fR
file is composed of two types of entries: aliases
(basically variables) and user specifications (which specify who
may run what).
.PP
When multiple entries match for a user, they are applied in order.
Where there are multiple matches, the last match is used (which is
not necessarily the most specific match).
.PP
The
\fIsudoers\fR
file grammar will be described below in Extended Backus-Naur
Form (EBNF).
Don't despair if you are unfamiliar with EBNF; it is fairly simple,
and the definitions below are annotated.
.SS "Resource limits"
By default,
\fBsudoers\fR
uses the operating system's native method of setting resource limits
for the target user.
On Linux systems, resource limits are usually set by the
\fIpam_limits.so\fR
PAM module.
On some BSD systems, the
\fI/etc/login.conf\fR
file specifies resource limits for the user.
On AIX systems, resource limits are configured in the
\fI/etc/security/limits\fR
file.
If there is no system mechanism to set per-user resource limits,
the command will run with the same limits as the invoking user.
The one exception to this is the core dump file size, which is set by
\fBsudoers\fR
to 0 by default.
Disabling core dumps by default makes it possible to avoid potential
security problems where the core file is treated as trusted input.
.PP
Resource limits may also be set in the
\fIsudoers\fR
file itself, in which case they override those set by the system.
See the
\fIrlimit_as,\fR
\fIrlimit_core,\fR
\fIrlimit_cpu,\fR
\fIrlimit_data,\fR
\fIrlimit_fsize,\fR
\fIrlimit_locks,\fR
\fIrlimit_memlock,\fR
\fIrlimit_nofile,\fR
\fIrlimit_nproc,\fR
\fIrlimit_rss,\fR
\fIrlimit_stack\fR
options described below.
Resource limits in
\fBsudoers\fR
may be specified in one of the following formats:
.TP 8n
\(lqvalue\(rq
Both the soft and hard resource limits are set to the same value.
The special value
\(lqinfinity\(rq
can be used to indicate that the value is unlimited.
.TP 8n
\(lqsoft,hard\(rq
Two comma-separated values.
The soft limit is set to the first value and the hard limit is set
to the second.
Both values must either be enclosed in a set of double quotes,
or the comma must be escaped with a backslash
(\(oq\e\(cq).
The special value
\(lqinfinity\(rq
may be used in place of either value.
.TP 8n
\(lqdefault\(rq
The default resource limit for the user will be used.
This may be a user-specific value (see above) or the value of the
resource limit when
\fBsudo\fR
was invoked for systems that don't support per-user limits.
.TP 8n
\(lquser\(rq
The invoking user's resource limits will be preserved when running
the command.
.PP
For example, to restore the historic core dump file size behavior,
a line like the following may be used.
.sp
.RS 6n
Defaults rlimit_core=default
.RE
.PP
Resource limits in
\fBsudoers\fR
are only supported by version 1.8.7 or higher.
.SS "Quick guide to EBNF"
EBNF is a concise and exact way of describing the grammar of a language.
Each EBNF definition is made up of
\fIproduction rules\fR.
For example:
.nf
.sp
.RS 4n
symbol ::= definition | alternate1 | alternate2 ...
.RE
.fi
.PP
Each
\fIproduction rule\fR
references others and thus makes up a
grammar for the language.
EBNF also contains the following
operators, which many readers will recognize from regular
expressions.
Do not, however, confuse them with
\(lqwildcard\(rq
characters, which have different meanings.
.TP 6n
\&?
Means that the preceding symbol (or group of symbols) is optional.
That is, it may appear once or not at all.
.TP 6n
*
Means that the preceding symbol (or group of symbols) may appear
zero or more times.
.TP 6n
+
Means that the preceding symbol (or group of symbols) may appear
one or more times.
.PP
Parentheses may be used to group symbols together.
For clarity,
we will use single quotes
('')
to designate what is a verbatim character string (as opposed to a symbol name).
.SS "Aliases"
There are four kinds of aliases:
\fIUser_Alias\fR,
\fIRunas_Alias\fR,
\fIHost_Alias\fR
and
\fICmnd_Alias\fR.
Beginning with
\fBsudo\fR
1.9.0,
\fICmd_Alias\fR
may be used in place of
\fICmnd_Alias\fR
if desired.
.nf
.sp
.RS 0n
Alias ::= 'User_Alias'  User_Alias_Spec (':' User_Alias_Spec)* |
          'Runas_Alias' Runas_Alias_Spec (':' Runas_Alias_Spec)* |
          'Host_Alias'  Host_Alias_Spec (':' Host_Alias_Spec)* |
          'Cmnd_Alias'  Cmnd_Alias_Spec (':' Cmnd_Alias_Spec)* |
          'Cmd_Alias'   Cmnd_Alias_Spec (':' Cmnd_Alias_Spec)*

User_Alias ::= NAME

User_Alias_Spec ::= User_Alias '=' User_List

Runas_Alias ::= NAME

Runas_Alias_Spec ::= Runas_Alias '=' Runas_List

Host_Alias ::= NAME

Host_Alias_Spec ::= Host_Alias '=' Host_List

Cmnd_Alias ::= NAME

Cmnd_Alias_Spec ::= Cmnd_Alias '=' Cmnd_List

NAME ::= [A-Z]([A-Z][0-9]_)*
.RE
.fi
.PP
Each
\fIalias\fR
definition is of the form
.nf
.sp
.RS 0n
Alias_Type NAME = item1, item2, ...
.RE
.fi
.PP
where
\fIAlias_Type\fR
is one of
\fIUser_Alias\fR,
\fIRunas_Alias\fR,
\fIHost_Alias\fR,
or
\fICmnd_Alias\fR.
A
\fRNAME\fR
is a string of uppercase letters, numbers,
and underscore characters
(\(oq_\(cq).
A
\fRNAME\fR
\fBmust\fR
start with an
uppercase letter.
It is possible to put several alias definitions
of the same type on a single line, joined by a colon
(\(oq:\&\(cq).
For example:
.nf
.sp
.RS 0n
Alias_Type NAME = item1, item2, item3 : NAME = item4, item5
.RE
.fi
.PP
It is a syntax error to redefine an existing
\fIalias\fR.
It is possible to use the same name for
\fIaliases\fR
of different types, but this is not recommended.
.PP
The definitions of what constitutes a valid
\fIalias\fR
member follow.
.nf
.sp
.RS 0n
User_List ::= User |
              User ',' User_List

User ::= '!'* user name |
         '!'* #user-ID |
         '!'* %group |
         '!'* %#group-ID |
         '!'* +netgroup |
         '!'* %:nonunix_group |
         '!'* %:#nonunix_gid |
         '!'* User_Alias
.RE
.fi
.PP
A
\fIUser_List\fR
is made up of one or more user names, user-IDs
(prefixed with
\(oq#\(cq),
system group names and IDs (prefixed with
\(oq%\(cq
and
\(oq%#\(cq
respectively), netgroups (prefixed with
\(oq+\(cq),
non-Unix group names and IDs (prefixed with
\(oq%:\(cq
and
\(oq%:#\(cq
respectively), and
\fIUser_Alias\fRes.
Each list item may be prefixed with zero or more
\(oq\&!\(cq
operators.
An odd number of
\(oq\&!\(cq
operators negate the value of
the item; an even number just cancel each other out.
User netgroups are matched using the user and domain members only;
the host member is not used when matching.
.PP
A
\fIuser name\fR,
\fIuser-ID\fR,
\fIgroup\fR,
\fIgroup-ID\fR,
\fInetgroup\fR,
\fInonunix_group\fR
or
\fInonunix_gid\fR
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., \ex20 for space.
When
using double quotes, any prefix characters must be included inside
the quotes.
.PP
The actual
\fInonunix_group\fR
and
\fInonunix_gid\fR
syntax depends on
the underlying group provider plugin.
For instance, the QAS AD plugin supports the following formats:
.TP 3n
\fB\(bu\fR
Group in the same domain: "%:Group Name"
.TP 3n
\fB\(bu\fR
Group in any domain: "%:Group Name@FULLY.QUALIFIED.DOMAIN"
.TP 3n
\fB\(bu\fR
Group SID: "%:S-1-2-34-5678901234-5678901234-5678901234-567"
.PP
See
\fIGROUP PROVIDER PLUGINS\fR
for more information.
.PP
Quotes around group names are optional.
Unquoted strings must use a backslash
(\(oq\e\(cq)
to escape spaces and special characters.
See
\fIOther special characters and reserved words\fR
for a list of
characters that need to be escaped.
.nf
.sp
.RS 0n
Runas_List ::= Runas_Member |
               Runas_Member ',' Runas_List

Runas_Member ::= '!'* user name |
                 '!'* #user-ID |
                 '!'* %group |
                 '!'* %#group-ID |
                 '!'* %:nonunix_group |
                 '!'* %:#nonunix_gid |
                 '!'* +netgroup |
                 '!'* Runas_Alias |
                 '!'* ALL
.RE
.fi
.PP
A
\fIRunas_List\fR
is similar to a
\fIUser_List\fR
except that instead
of
\fIUser_Alias\fRes
it can contain
\fIRunas_Alias\fRes.
User names and groups are matched as strings.
In other words, two users (groups) with the same user (group) ID
are considered to be distinct.
If you wish to match all user names with the same user-ID (e.g.,
\fBroot\fR
and
\fBtoor\fR),
you can use a user-ID instead of a name (#0 in the example given).
The user-ID or group-ID specified in a
\fIRunas_Member\fR
need not be listed in the password or group database.
.nf
.sp
.RS 0n
Host_List ::= Host |
              Host ',' Host_List

Host ::= '!'* host name |
         '!'* ip_addr |
         '!'* network(/netmask)? |
         '!'* +netgroup |
         '!'* Host_Alias |
         '!'* ALL
.RE
.fi
.PP
A
\fIHost_List\fR
is made up of one or more host names, IP addresses,
network numbers, netgroups (prefixed with
\(oq+\(cq),
and other aliases.
Again, the value of an item may be negated with the
\(oq\&!\(cq
operator.
Host netgroups are matched using the host (both qualified and unqualified)
and domain members only; the user member is not used when matching.
If you specify a network number without a netmask,
\fBsudo\fR
will query each of the local host's network interfaces and,
if the network number corresponds to one of the hosts's network
interfaces, will use the netmask of that interface.
The netmask may be specified either in standard IP address notation
(e.g., 255.255.255.0 or ffff:ffff:ffff:ffff::),
or CIDR notation (number of bits, e.g., 24 or 64).
A host name may include shell-style wildcards (see the
\fIWildcards\fR
section below),
but unless the
\fIhostname\fR
command on your machine returns the fully
qualified host name, you'll need to use the
\fIfqdn\fR
flag for wildcards to be useful.
\fBsudo\fR
only inspects actual network interfaces; this means that IP address
127.0.0.1 (localhost) will never match.
Also, the host name
\(lqlocalhost\(rq
will only match if that is the actual host name, which is usually
only the case for non-networked systems.
.nf
.sp
.RS 0n
digest ::= [A-Fa-f0-9]+ |
           [A-Za-z0-9\e+/=]+

Digest_Spec ::= "sha224" ':' digest |
                "sha256" ':' digest |
                "sha384" ':' digest |
                "sha512" ':' digest

Digest_List ::= Digest_Spec |
                Digest_Spec ',' Digest_List

Cmnd_List ::= Cmnd |
              Cmnd ',' Cmnd_List

command name ::= regex |
                 file name

command ::= command name |
            command name args |
            command name regex |
            command name '""' |
            ALL

Edit_Spec ::= "sudoedit" file name+ |
              "sudoedit" regex |
              "sudoedit"

List_Spec ::= "list"

Cmnd ::= Digest_List? '!'* command |
         '!'* directory |
         '!'* Edit_Spec |
         '!'* List_Spec |
         '!'* Cmnd_Alias
.RE
.fi
.PP
A
\fICmnd_List\fR
is a list of one or more commands, directories, or aliases.
A command is a fully qualified file name, which may include
shell-style wildcards (see the
\fIWildcards\fR
section below),
or a regular expression that starts with
\(oq^\(cq
and ends with
\(oq$\(cq
(see the
\fIRegular expressions\fR
section below).
A directory is a
fully qualified path name ending in a
\(oq/\(cq.
When you specify a directory in a
\fICmnd_List\fR,
the user will be able to run any file within that directory
(but not in any sub-directories therein).
If no command line arguments are specified, the user may run the
command with any arguments they choose.
Command line arguments can include wildcards or be a regular
expression that starts with
\(oq^\(cq
and ends with
\(oq$\(cq.
If the command line arguments consist of
\(oq\&""\(cq,
the command may only be run with
\fIno\fR
arguments.
.PP
If a
\fICmnd\fR
has associated command line arguments, the arguments
in the
\fICmnd\fR
must match those given by the user on the command line.
If the arguments in a
\fICmnd\fR
begin with the
\(oq^\(cq
character, they will be interpreted as a regular expression
and matched accordingly.
Otherwise, shell-style wildcards are used when matching.
Unless a regular expression is specified, the following characters must
be escaped with a
\(oq\e\(cq
if they are used in command arguments:
\(oq,\&\(cq,
\(oq:\&\(cq,
\(oq=\&\(cq,
\(oq\e\(cq.
To prevent arguments in a
\fICmnd\fR
that begin with a
\(oq^\(cq
character from being interpreted as a regular expression, the
\(oq^\(cq
must be escaped with a
\(oq\e\(cq.
.PP
There are two commands built into
\fBsudo\fR
itself:
\(lqlist\(rq
and
\(lqsudoedit\(rq.
Unlike other commands, these two must be specified in the
\fIsudoers\fR
file
\fIwithout\fR
a leading path.
.PP
The
\(lqlist\(rq
built-in can be used to permit a user to list another user's privileges with
\fBsudo\fR's
\fB\-U\fR
option.
For example,
\(lqsudo -l -U otheruser\(rq.
A user with the
\(lqlist\(rq
privilege is able to list another user's privileges even if they
don't have permission to run commands as that user.
By default, only root or a user with the ability to run any command as
either root or the specified
\fIuser\fR
on the current host may use the
\fB\-U\fR
option.
No command line arguments may be specified with the
\(lqlist\(rq
built-in.
.PP
The
\(lqsudoedit\(rq
built-in is used to permit a user to run
\fBsudo\fR
with the
\fB\-e\fR
option (or as
\fBsudoedit\fR).
It may take command line arguments just as a normal command does.
Unlike other commands,
\(lqsudoedit\(rq
is built into
\fBsudo\fR
itself and must be specified in the
\fIsudoers\fR
file
\fIwithout\fR
a leading path.
If a leading path is present, for example
\fI/usr/bin/sudoedit\fR,
the path name will be silently converted to
\(lqsudoedit\(rq.
A fully-qualified path for
\fBsudoedit\fR
is treated as an error by
\fBvisudo\fR.
.PP
A
\fIcommand\fR
may be preceded by a
\fIDigest_List\fR,
a comma-separated list of one or more
\fIDigest_Spec\fR
entries.
If a
\fIDigest_List\fR
is present, the command will only match successfully if it can be verified
using one of the SHA-2 digests in the list.
Starting with version 1.9.0, the
\fBALL\fR
reserved word can be used in conjunction with a
\fIDigest_List\fR.
The following digest formats are supported: sha224, sha256, sha384, and sha512.
The string may be specified in either hex or base64 format
(base64 is more compact).
There are several utilities capable of generating SHA-2 digests in hex
format such as openssl, shasum, sha224sum, sha256sum, sha384sum, sha512sum.
.PP
For example, using openssl:
.nf
.sp
.RS 0n
$ openssl dgst -sha224 /bin/ls
SHA224(/bin/ls)= 118187da8364d490b4a7debbf483004e8f3e053ec954309de2c41a25
.RE
.fi
.PP
It is also possible to use openssl to generate base64 output:
.nf
.sp
.RS 0n
$ openssl dgst -binary -sha224 /bin/ls | openssl base64
EYGH2oNk1JC0p9679IMATo8+BT7JVDCd4sQaJQ==
.RE
.fi
.PP
Warning, if the user has write access to the command itself (directly or via a
\fBsudo\fR
command), it may be possible for the user to replace the command after the
digest check has been performed but before the command is executed.
A similar race condition exists on systems that lack the
fexecve(2)
system call when the directory in which the command is located
is writable by the user.
See the description of the
\fIfdexec\fR
setting for more information on how
\fBsudo\fR
executes commands that have an associated digest.
.PP
Command digests are only supported by version 1.8.7 or higher.
.SS "Defaults"
Certain configuration options may be changed from their default
values at run-time via one or more
\fIDefault_Entry\fR
lines.
These may affect all users on any host, all users on a specific host, a
specific user, a specific command, or commands being run as a specific user.
Per-command entries may not include command line arguments.
If you need to specify arguments, define a
\fICmnd_Alias\fR
and reference
that instead.
.nf
.sp
.RS 0n
Default_Type ::= 'Defaults' |
                 'Defaults' '@' Host_List |
                 'Defaults' ':' User_List |
                 'Defaults' '!' Cmnd_List |
                 'Defaults' '>' Runas_List

Default_Entry ::= Default_Type Parameter_List

Parameter_List ::= Parameter |
                   Parameter ',' Parameter_List

Parameter ::= Parameter '=' Value |
              Parameter '+=' Value |
              Parameter '-=' Value |
              '!'* Parameter
.RE
.fi
.PP
Parameters may be
\fBflags\fR,
\fBinteger\fR
values,
\fBstrings\fR,
or
\fBlists\fR.
Flags are implicitly boolean and can be turned off via the
\(oq\&!\(cq
operator.
Some integer, string and list parameters may also be
used in a boolean context to disable them.
Values may be enclosed
in double quotes
(\&"")
when they contain multiple words.
Special characters may be escaped with a backslash
(\(oq\e\(cq).
.PP
To include a literal backslash character in a command line argument
you must escape the backslash twice.
For example, to match
\(oq\en\(cq
as part of a command line argument, you must use
\(oq\e\e\e\en\(cq
in the
\fIsudoers\fR
file.
This is due to there being two levels of escaping, one in the
\fIsudoers\fR
parser itself and another when command line arguments are matched by the
fnmatch(3)
or
regexec(3)
function.
.PP
Lists have two additional assignment operators,
\(oq+=\(cq
and
\(oq-=\(cq.
These operators are used to add to and delete from a list respectively.
It is not an error to use the
\(oq-=\(cq
operator to remove an element
that does not exist in a list.
.PP
Defaults entries are parsed in the following order: global, host,
user, and runas Defaults first, then command defaults.
If there are multiple Defaults settings of the same type, the last
matching setting is used.
The following Defaults settings are parsed before all others since
they may affect subsequent entries:
\fIfqdn\fR,
\fIgroup_plugin\fR,
\fIrunas_default\fR,
\fIsudoers_locale\fR.
.PP
See
\fISUDOERS OPTIONS\fR
for a list of supported Defaults parameters.
.SS "User specification"
.nf
.RS 0n
User_Spec ::= User_List Host_List '=' Cmnd_Spec_List \e
              (':' Host_List '=' Cmnd_Spec_List)*

Cmnd_Spec_List ::= Cmnd_Spec |
                   Cmnd_Spec ',' Cmnd_Spec_List

Cmnd_Spec ::= Runas_Spec? Option_Spec* (Tag_Spec ':')* Cmnd

Runas_Spec ::= '(' Runas_List? (':' Runas_List)? ')'

.ie \n(SL \{\
.ie \n(PS Option_Spec ::= (SELinux_Spec | Solaris_Priv_Spec | Date_Spec | Timeout_Spec)
.el Option_Spec ::= (SELinux_Spec | Date_Spec | Timeout_Spec)
.\}
.el \{\
.ie \n(PS Option_Spec ::= (Solaris_Priv_Spec | Date_Spec | Timeout_Spec)
.el Option_Spec ::= (Date_Spec | Timeout_Spec)
.\}

.if \n(SL \{\
SELinux_Spec ::= ('ROLE=role' | 'TYPE=type')

.\}
AppArmor_Spec ::= 'APPARMOR_PROFILE=profile'

.if \n(PS \{\
Solaris_Priv_Spec ::= ('PRIVS=privset' | 'LIMITPRIVS=privset')

.\}
Date_Spec ::= ('NOTBEFORE=timestamp' | 'NOTAFTER=timestamp')

Timeout_Spec ::= 'TIMEOUT=timeout'

Chdir_Spec ::= 'CWD=directory'

Chroot_Spec ::= 'CHROOT=directory'

Tag_Spec ::= ('EXEC' | 'NOEXEC' | 'FOLLOW' | 'NOFOLLOW' |
              'LOG_INPUT' | 'NOLOG_INPUT' | 'LOG_OUTPUT' |
              'NOLOG_OUTPUT' | 'MAIL' | 'NOMAIL' | 'INTERCEPT' |
              'NOINTERCEPT' | 'PASSWD' | 'NOPASSWD' | 'SETENV' |
              'NOSETENV')
.RE
.fi
.PP
A
\fBuser specification\fR
determines which commands a user may run
(and as what user) on specified hosts.
By default, commands are run as
\fB@runas_default@\fR
(unless
\fIrunas_default\fR
has been set to a different value)
but this can also be changed on a per-command basis.
.PP
The basic structure of a user specification is
\(lqwho where = (as_whom) what\(rq.
Let's break that down into its constituent parts:
.SS "Runas_Spec"
A
\fIRunas_Spec\fR
determines the user and/or the group that a command
may be run as.
A fully-specified
\fIRunas_Spec\fR
consists of two
\fIRunas_List\fRs
(as defined above) separated by a colon
(\(oq:\&\(cq)
and enclosed in a set of parentheses.
The first
\fIRunas_List\fR
indicates which users the command may be run as via the
\fB\-u\fR
option.
The second defines a list of groups that may be specified via the
\fB\-g\fR
option (in addition to any of the target user's groups).
If both
\fIRunas_List\fRs
are specified, the command may be run with any combination of users
and groups listed in their respective
\fIRunas_List\fRs.
If only the first is specified, the command may be run as any user
in the list and, optionally, with any group the target user belongs to.
If the first
\fIRunas_List\fR
is empty but the
second is specified, the command may be run as the invoking user
with the group set to any listed in the
\fIRunas_List\fR.
If both
\fIRunas_List\fRs
are empty, the command may only be run as the invoking user and the
group, if specified, must be one that the invoking user is a member of.
If no
\fIRunas_Spec\fR
is specified, the command may only be run as the
\fIrunas_default\fR
user
(\fB@runas_default@\fR
by default) and the group,
if specified, must be one that the
\fIrunas_default\fR
user is a member of.
.PP
A
\fIRunas_Spec\fR
sets the default for the commands that follow it.
What this means is that for the entry:
.nf
.sp
.RS 0n
dgb	boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm
.RE
.fi
.PP
The user
\fBdgb\fR
may run
\fI/bin/ls\fR,
\fI/bin/kill\fR,
and
\fI/usr/bin/lprm\fR
on the host
boulder\(embut
only as
\fBoperator\fR.
For example:
.nf
.sp
.RS 0n
$ sudo -u operator /bin/ls
.RE
.fi
.PP
It is also possible to override a
\fIRunas_Spec\fR
later on in an entry.
If we modify the entry like so:
.nf
.sp
.RS 0n
dgb	boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm
.RE
.fi
.PP
Then user
\fBdgb\fR
is now allowed to run
\fI/bin/ls\fR
as
\fBoperator\fR,
but
\fI/bin/kill\fR
and
\fI/usr/bin/lprm\fR
as
\fBroot\fR.
.PP
We can extend this to allow
\fBdgb\fR
to run
\fI/bin/ls\fR
with either
the user or group set to
\fBoperator\fR:
.nf
.sp
.RS 0n
dgb	boulder = (operator : operator) /bin/ls, (root) /bin/kill,\e
	/usr/bin/lprm
.RE
.fi
.PP
While the group portion of the
\fIRunas_Spec\fR
permits the
user to run as command with that group, it does not force the user
to do so.
If no group is specified on the command line, the command
will run with the group listed in the target user's password database
entry.
The following would all be permitted by the sudoers entry above:
.nf
.sp
.RS 0n
$ sudo -u operator /bin/ls
$ sudo -u operator -g operator /bin/ls
$ sudo -g operator /bin/ls
.RE
.fi
.PP
In the following example, user
\fBtcm\fR
may run commands that access
a modem device file with the dialer group.
.nf
.sp
.RS 0n
tcm	boulder = (:dialer) /usr/bin/tip, /usr/bin/cu,\e
	/usr/local/bin/minicom
.RE
.fi
.PP
In this example only the group will be set, the command still runs as user
\fBtcm\fR.
For example:
.nf
.sp
.RS 0n
$ sudo -g dialer /usr/bin/cu
.RE
.fi
.PP
Multiple users and groups may be present in a
\fIRunas_Spec\fR,
in which case the user may select any combination of users and groups via the
\fB\-u\fR
and
\fB\-g\fR
options.
In this example:
.nf
.sp
.RS 0n
alan	ALL = (root, bin : operator, system) ALL
.RE
.fi
.PP
user
\fBalan\fR
may run any command as either user
\fBroot\fR
or
\fBbin\fR,
optionally setting the group to operator or system.
.SS "Option_Spec"
A
\fICmnd\fR
may have zero or more options associated with it.
Options may consist of
.if \n(SL \{\
SELinux roles and/or types,
.\}
AppArmor profiles,
.if \n(PS \{\
Solaris privileges sets,
.\}
start and/or end dates and command timeouts.
Once an option is set for a
\fICmnd\fR,
subsequent
\fICmnd\fRs
in the
\fICmnd_Spec_List\fR,
inherit that option unless it is overridden by another option.
Option names are reserved words in
\fIsudoers\fR.
This means that none of the valid option names (see below) can be used
when declaring an alias.
.if \n(SL \{\
.SS "SELinux_Spec"
On systems with SELinux support,
\fIsudoers\fR
file entries may optionally have an SELinux role and/or type associated
with a command.
This can be used to implement a form of role-based access control (RBAC).
If a role or
type is specified with the command it will override any default values
specified in
\fIsudoers\fR.
A role or type specified on the command line,
however, will supersede the values in
\fIsudoers\fR.
.\}
.SS "AppArmor_Spec"
On systems supporting AppArmor,
\fIsudoers\fR
file entries may optionally specify an AppArmor profile that should be
used to confine a command.
If an AppArmor profile is specified with the command, it will override
any default values specified in
\fIsudoers\fR.
Appropriate profile transition rules must be defined to support the
profile change specified for a user.
.PP
AppArmor profiles can be specified in any way that complies with the
rules of
aa_change_profile(2).
For instance, in the following
\fIsudoers\fR
entry
.nf
.sp
.RS 0n
alice	ALL = (root)	APPARMOR_PROFILE=my-profile	ALL
.RE
.fi
.PP
the user
\fBalice\fR
may run any command as
\fBroot\fR
under confinement by the profile
\(oqmy-profile\(cq.
You can also stack profiles, or allow a user to run commands unconfined by
any profile.
For example:
.nf
.sp
.RS 0n
bob	ALL = (root)	APPARMOR_PROFILE=foo//&bar	/usr/bin/vi
cathy	ALL = (root)	APPARMOR_PROFILE=unconfined	/bin/ls
.RE
.fi
.PP
These
\fIsudoers\fR
entries allow user
\fBbob\fR
to run
\fI/usr/bin/vi\fR
as
\fBroot\fR
under the stacked profiles
\(oqfoo\(cq
and
\(oqbar\(cq,
and user
\fBcathy\fR
to run
\fI/bin/ls\fR
without any confinement at all.
.if \n(PS \{\
.SS "Solaris_Priv_Spec"
On Solaris systems,
\fIsudoers\fR
file entries may optionally specify Solaris privilege set and/or limit
privilege set associated with a command.
If privileges or limit privileges are specified with the command
it will override any default values specified in
\fIsudoers\fR.
.PP
A privilege set is a comma-separated list of privilege names.
The
ppriv(1)
command can be used to list all privileges known to the system.
For example:
.nf
.sp
.RS 0n
$ ppriv -l
.RE
.fi
.PP
In addition, there are several
\(lqspecial\(rq
privilege strings:
.TP 7n
none
the empty set
.TP 7n
all
the set of all privileges
.TP 7n
zone
the set of all privileges available in the current zone
.TP 7n
basic
the default set of privileges normal users are granted at login time
.PP
Privileges can be excluded from a set by prefixing the privilege
name with either an
\(oq\&!\(cq
or
\(oq\-\(cq
character.
.\}
.SS "Date_Spec"
\fBsudoers\fR
rules can be specified with a start and end date via the
\fRNOTBEFORE\fR
and
\fRNOTAFTER\fR
settings.
The time stamp must be specified in
\(lqGeneralized Time\(rq
as defined by RFC 4517.
The format is effectively
\(oqyyyymmddHHMMSSZ\(cq
where the minutes and seconds are optional.
The
\(oqZ\(cq
suffix indicates that the time stamp is in Coordinated Universal Time (UTC).
It is also possible to specify a timezone offset from UTC in hours
and minutes instead of a
\(oqZ\(cq.
For example,
\(oq-0500\(cq
would correspond to Eastern Standard time in the US.
As an extension, if no
\(oqZ\(cq
or timezone offset is specified, local time will be used.
.PP
The following are all valid time stamps:
.nf
.sp
.RS 4n
20170214083000Z
2017021408Z
20160315220000-0500
20151201235900
.RE
.fi
.SS "Timeout_Spec"
A command may have a timeout associated with it.
If the timeout expires before the command has exited, the
command will be terminated.
The timeout may be specified in combinations of days, hours,
minutes, and seconds with a single-letter case-insensitive suffix
that indicates the unit of time.
For example, a timeout of 7 days, 8 hours, 30 minutes, and
10 seconds would be written as
\(oq7d8h30m10s\(cq.
If a number is specified without a unit, seconds are assumed.
Any of the days, minutes, hours, or seconds may be omitted.
The order must be from largest to smallest unit and a unit
may not be specified more than once.
.PP
The following are all
\fIvalid\fR
timeout values:
\(oq7d8h30m10s\(cq,
\(oq14d\(cq,
\(oq8h30m\(cq,
\(oq600s\(cq,
\(oq3600\(cq.
The following are
\fIinvalid\fR
timeout values:
\(oq12m2w1d\(cq,
\(oq30s10m4h\(cq,
\(oq1d2d3h\(cq.
.PP
This setting is only supported by version 1.8.20 or higher.
.SS "Chdir_Spec"
The working directory that the command will be run in can be specified
using the
\fRCWD\fR
setting.
The
\fIdirectory\fR
must be a fully-qualified path name beginning with a
\(oq/\(cq
or
\(oq~\(cq
character, or the special value
\(lq*\(rq.
A value of
\(lq*\(rq
indicates that the user may specify the working directory by running
\fBsudo\fR
with the
\fB\-D\fR
option.
By default, commands are run from the invoking user's current working
directory, unless the
\fB\-i\fR
option is given.
Path names of the form
\fI~user/path/name\fR
are interpreted as being relative to the named user's home directory.
If the user name is omitted, the path will be relative to the runas
user's home directory.
.PP
This setting is only supported by version 1.9.3 or higher.
.SS "Chroot_Spec"
The root directory that the command will be run in can be specified
using the
\fRCHROOT\fR
setting.
The
\fIdirectory\fR
must be a fully-qualified path name beginning with a
\(oq/\(cq
or
\(oq~\(cq
character, or the special value
\(lq*\(rq.
A value of
\(lq*\(rq
indicates that the user may specify the root directory by running
\fBsudo\fR
with the
\fB\-R\fR
option.
This setting can be used to run the command in a
chroot(2)
\(lqsandbox\(rq
similar to the
chroot(@mansectsu@)
utility.
Path names of the form
\fI~user/path/name\fR
are interpreted as being relative to the named user's home directory.
If the user name is omitted, the path will be relative to the runas
user's home directory.
.PP
This setting is only supported by version 1.9.3 or higher.
.SS "Tag_Spec"
A command may have zero or more tags associated with it.
The following tag values are supported:
\fREXEC\fR,
\fRNOEXEC\fR,
\fRFOLLOW\fR,
\fRNOFOLLOW\fR,
\fRLOG_INPUT\fR,
\fRNOLOG_INPUT\fR,
\fRLOG_OUTPUT\fR,
\fRNOLOG_OUTPUT\fR,
\fRMAIL\fR,
\fRNOMAIL\fR,
\fRINTERCEPT\fR,
\fRNOINTERCEPT\fR,
\fRPASSWD\fR,
\fRNOPASSWD\fR,
\fRSETENV\fR,
and
\fRNOSETENV\fR.
Once a tag is set on a
\fICmnd\fR,
subsequent
\fICmnd\fRs
in the
\fICmnd_Spec_List\fR,
inherit the tag unless it is overridden by the opposite tag (in other words,
\fRPASSWD\fR
overrides
\fRNOPASSWD\fR
and
\fRNOEXEC\fR
overrides
\fREXEC\fR).
.TP 2n
\fREXEC\fR and \fRNOEXEC\fR
.sp
If
\fBsudo\fR
has been compiled with
\fInoexec\fR
support and the underlying operating system supports it, the
\fRNOEXEC\fR
tag can be used to prevent a dynamically-linked executable from
running further commands itself.
.sp
In the following example, user
\fBaaron\fR
may run
\fI/usr/bin/more\fR
and
\fI/usr/bin/vi\fR
but shell escapes will be disabled.
.nf
.sp
.RS 2n
aaron	shanty = NOEXEC: /usr/bin/more, /usr/bin/vi
.RE
.fi
.RS 2n
.sp
See the
\fIPreventing shell escapes\fR
section below for more details on how
\fRNOEXEC\fR
works and whether or not it will work on your system.
.RE
.TP 2n
\fRFOLLOW\fR and \fRNOFOLLOW\fR
.sp
Starting with version 1.8.15,
\fBsudoedit\fR
will not open a file that is a symbolic link unless the
\fIsudoedit_follow\fR
flag is enabled.
The
\fRFOLLOW\fR
and
\fRNOFOLLOW\fR
tags override the value of
\fIsudoedit_follow\fR
and can be used to permit (or deny) the editing of symbolic links
on a per-command basis.
These tags are only effective for the
\fIsudoedit\fR
command and are ignored for all other commands.
.TP 2n
\fRLOG_INPUT\fR and \fRNOLOG_INPUT\fR
.sp
These tags override the value of the
\fIlog_input\fR
flag on a per-command basis.
For more information, see
\fII/O LOGGING\fR.
.TP 2n
\fRLOG_OUTPUT\fR and \fRNOLOG_OUTPUT\fR
.sp
These tags override the value of the
\fIlog_output\fR
flag on a per-command basis.
For more information, see
\fII/O LOGGING\fR.
.TP 2n
\fRMAIL\fR and \fRNOMAIL\fR
.sp
These tags provide fine-grained control over whether
mail will be sent when a user runs a command by
overriding the value of the
\fImail_all_cmnds\fR
flag on a per-command basis.
They have no effect when
\fBsudo\fR
is run with the
\fB\-l\fR
or
\fB\-v\fR
options.
A
\fRNOMAIL\fR
tag will also override the
\fImail_always\fR
and
\fImail_no_perms\fR
options.
For more information, see the descriptions of
\fImail_all_cmnds\fR,
\fImail_always\fR,
and
\fImail_no_perms\fR
in the
\fISUDOERS OPTIONS\fR
section below.
.TP 2n
\fRPASSWD\fR and \fRNOPASSWD\fR
.sp
By default,
\fBsudo\fR
requires that a user authenticate
before running a command.
This behavior can be modified via the
\fRNOPASSWD\fR
tag.
Like a
\fIRunas_Spec\fR,
the
\fRNOPASSWD\fR
tag sets
a default for the commands that follow it in the
\fICmnd_Spec_List\fR.
Conversely, the
\fRPASSWD\fR
tag can be used to reverse things.
For example:
.nf
.sp
.RS 2n
ray	rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm
.RE
.fi
.RS 2n
.sp
would allow the user
\fBray\fR
to run
\fI/bin/kill\fR,
\fI/bin/ls\fR,
and
\fI/usr/bin/lprm\fR
as
\fB@runas_default@\fR
on the machine
\(lqrushmore\(rq
without authenticating himself.
If we only want
\fBray\fR
to be able to
run
\fI/bin/kill\fR
without a password the entry would be:
.nf
.sp
.RS 2n
ray	rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm
.RE
.fi
.sp
Note, however, that the
\fRPASSWD\fR
tag has no effect on users who are in the group specified by the
\fIexempt_group\fR
setting.
.sp
By default, if the
\fRNOPASSWD\fR
tag is applied to any of a user's entries for the current host,
the user will be able to run
\(oqsudo -l\(cq
without a password.
Additionally, a user may only run
\(oqsudo -v\(cq
without a password if all of the user's entries for the current
host have the
\fRNOPASSWD\fR
tag.
This behavior may be overridden via the
\fIverifypw\fR
and
\fIlistpw\fR
options.
.RE
.TP 2n
\fRSETENV\fR and \fRNOSETENV\fR
.sp
These tags override the value of the
\fIsetenv\fR
flag on a per-command basis.
If
\fRSETENV\fR
has been set for a command, the user may disable the
\fIenv_reset\fR
flag from the command line via the
\fB\-E\fR
option.
Additionally, environment variables set on the command
line are not subject to the restrictions imposed by
\fIenv_check\fR,
\fIenv_delete\fR,
or
\fIenv_keep\fR.
As such, only trusted users should be allowed to set variables in this manner.
If the command matched is
\fBALL\fR,
the
\fRSETENV\fR
tag is implied for that command; this default may be overridden by use of the
\fRNOSETENV\fR
tag.
.TP 2n
\fRINTERCEPT\fR and \fRNOINTERCEPT\fR
.sp
If
\fBsudo\fR
has been compiled with
\fIintercept\fR
support and the underlying operating system supports it, the
\fRINTERCEPT\fR
tag can be used to cause programs spawned by a command to be validated against
\fIsudoers\fR
and logged just like they would be if run through
\fBsudo\fR
directly.
This is useful in conjunction with commands that allow shell escapes
such as editors, shells, and paginators.
There is additional overhead due to the policy check that may add
latency when running commands such as shell scripts that execute a
large number of sub-commands.
For interactive commands, such as a shell or editor,
the overhead is not usually noticeable.
.sp
In the following example, user
\fBchuck\fR
may run any command on the machine
\(lqresearch\(rq
in intercept mode.
.nf
.sp
.RS 2n
chuck	research = INTERCEPT: ALL
.RE
.fi
.RS 2n
.sp
See the
\fIPreventing shell escapes\fR
section below for more details on how
\fRINTERCEPT\fR
works and whether or not it will work on your system.
.RE
.SS "Wildcards"
\fBsudo\fR
allows shell-style
\fIwildcards\fR
(aka meta or glob characters)
to be used in host names, path names, and command line arguments in the
\fIsudoers\fR
file.
Wildcard matching is done via the
glob(3)
and
fnmatch(3)
functions as specified by
IEEE Std 1003.1 (\(lqPOSIX.1\(rq).
.TP 8n
*
Matches any set of zero or more characters (including white space).
.TP 8n
\&?
Matches any single character (including white space).
.TP 8n
[...]
Matches any character in the specified range.
.TP 8n
[!...]
Matches any character
\fInot\fR
in the specified range.
.TP 8n
\ex
For any character
\(oqx\(cq,
evaluates to
\(oqx\(cq.
This is used to escape special characters such as:
\(oq*\(cq,
\(oq\&?\(cq,
\(oq[\&\(cq,
and
\(oq]\&\(cq.
.PP
\fBThese are not regular expressions.\fR
Unlike a regular expression there is no way to match one or more
characters within a range.
.PP
Character classes may be used if your system's
glob(3)
and
fnmatch(3)
functions support them.
However, because the
\(oq:\&\(cq
character has special meaning in
\fIsudoers\fR,
it must be
escaped.
For example:
.nf
.sp
.RS 4n
/bin/ls [[\e:\&alpha\e:\&]]*
.RE
.fi
.PP
Would match any file name beginning with a letter.
.PP
A forward slash
(\(oq/\(cq)
will
\fInot\fR
be matched by
wildcards used in the file name portion of the command.
This is to make a path like:
.nf
.sp
.RS 4n
/usr/bin/*
.RE
.fi
.PP
match
\fI/usr/bin/who\fR
but not
\fI/usr/bin/X11/xterm\fR.
.PP
When matching the command line arguments, however, a slash
\fIdoes\fR
get matched by wildcards since command line arguments may contain
arbitrary strings and not just path names.
.PP
\fBWildcards in command line arguments should be used with care.\fR
.br
Wildcards can match any character, including white space.
In most cases, it is safer to use a regular expression to match
command line arguments.
For more information, see
\fIWildcards in command arguments\fR
below.
.SS "Exceptions to wildcard rules"
The following exceptions apply to the above rules:
.TP 10n
\&""
If the empty string
\(oq\&""\(cq
is the only command line argument in the
\fIsudoers\fR
file entry it means that command is not allowed to be run with
\fIany\fR
arguments.
.TP 10n
sudoedit
Command line arguments to the
\fIsudoedit\fR
built-in command should always be path names, so a forward slash
(\(oq/\(cq)
will not be matched by a wildcard.
.SS "Regular expressions"
Starting with version 1.9.10, it is possible to use
regular expressions for path names and command line arguments.
Regular expressions are more expressive than shell-style
\fIwildcards\fR
and are usually safer because they provide a greater degree of
control when matching.
The type of regular expressions supported by
\fBsudoers\fR
are POSIX extended regular expressions, similar to those used by the
egrep(1)
utility.
They are usually documented in the
regex(@mansectmisc@)
or
re_format(@mansectmisc@)
manual, depending on the system.
As an extension, if the regular expression begins with
\(lq(?i)\(rq,
it will be matched in a case-insensitive manner.
.PP
In
\fIsudoers\fR,
regular expressions must start with a
\(oq^\(cq
character and end with a
\(oq$\(cq.
This makes it explicit what is, or is not, a regular expression.
Either the path name, the command line arguments or both may
be regular expressions.
Because the path name and arguments are matched separately, it is
even possible to use wildcards for the path name and regular
expressions for the arguments.
It is not possible to use a single regular expression to match
both the command and its arguments.
Regular expressions in
\fIsudoers\fR
are limited to 1024 characters.
.PP
There is no need to escape
\fIsudoers\fR
special characters in a regular expression other than the pound sign
(\(oq#\(cq).
.PP
In the following example, user
\fBjohn\fR
can run the
passwd(1)
command as
\fB@runas_default@\fR
on any host but is not allowed to change
\fBroot\fR's
password.
This kind of rule is impossible to express safely using wildcards.
.nf
.sp
.RS 4n
john	ALL = /usr/bin/passwd ^[a-zA-Z0-9_]+$,\e
              !/usr/bin/passwd root
.RE
.fi
.PP
It is also possible to use a regular expression in conjunction with
\fBsudoedit\fR
rules.
The following rule would give user bob the ability to edit the
\fI/etc/motd\fR,
\fI/etc/issue\fR,
and
\fI/etc/hosts\fR
files only.
.nf
.sp
.RS 4n
bob    ALL = sudoedit ^/etc/(motd|issue|hosts)$
.RE
.fi
.PP
Regular expressions may also be used to match the command itself.
In this example, a regular expression is used to allow user
\fBsid\fR
to run the
\fI/usr/sbin/groupadd\fR,
\fI/usr/sbin/groupmod\fR,
\fI/usr/sbin/groupdel\fR,
\fI/usr/sbin/useradd\fR,
\fI/usr/sbin/usermod\fR,
and
\fI/usr/sbin/userdel\fR
commands as
\fB@runas_default@\fR.
.nf
.sp
.RS 4n
sid    ALL = ^/usr/sbin/(group|user)(add|mod|del)$
.RE
.fi
.PP
One disadvantage of using a regular expression to match the command
name is that it is not possible to match relative paths such as
\fI./useradd\fR
or
\fI../sbin/useradd\fR.
This has security implications when a regular expression is used
for the command name in conjunction with the negation operator,
\(oq!\&\(cq,
as such rules can be trivially bypassed.
Because of this, using a negated regular expression for the command name is
\fBstrongly discouraged\fR.
This does not apply to negated commands that only use a regular
expression to match the command arguments.
See
\fIRegular expressions in command names\fR
below for more information.
.SS "Including other files from within sudoers"
It is possible to include other
\fIsudoers\fR
files from within the
\fIsudoers\fR
file currently being parsed using the
\fI@include\fR
and
\fI@includedir\fR
directives.
For compatibility with sudo versions prior to 1.9.1,
\fI#include\fR
and
\fI#includedir\fR
are also accepted.
.PP
An include file can be used, for example, to keep a site-wide
\fIsudoers\fR
file in addition to a local, per-machine file.
For the sake of this example the site-wide
\fIsudoers\fR
file will be
\fI/etc/sudoers\fR
and the per-machine one will be
\fI/etc/sudoers.local\fR.
To include
\fI/etc/sudoers.local\fR
from within
\fI/etc/sudoers\fR
one would use the following line in
\fI/etc/sudoers\fR:
.nf
.sp
.RS 4n
@include /etc/sudoers.local
.RE
.fi
.PP
When
\fBsudo\fR
reaches this line it will suspend processing of the current file
(\fI/etc/sudoers\fR)
and switch to
\fI/etc/sudoers.local\fR.
Upon reaching the end of
\fI/etc/sudoers.local\fR,
the rest of
\fI/etc/sudoers\fR
will be processed.
Files that are included may themselves include other files.
A hard limit of 128 nested include files is enforced to prevent include
file loops.
.PP
Starting with version 1.9.1, the path to the include file may contain
white space if it is escaped with a backslash
(\(oq\e\(cq).
Alternately, the entire path may be enclosed in double quotes
(\&""),
in which case no escaping is necessary.
To include a literal backslash in the path,
\(oq\e\e\(cq
should be used.
.PP
If the path to the include file is not fully-qualified (does not
begin with a
\(oq/\(cq),
it must be located in the same directory as the sudoers file it was
included from.
For example, if
\fI/etc/sudoers\fR
contains the line:
.nf
.sp
.RS 4n
@include sudoers.local
.RE
.fi
.PP
the file that will be included is
\fI/etc/sudoers.local\fR.
.PP
The file name may also include the
\(oq%h\(cq
escape, signifying the short form of the host name.
In other words, if the machine's host name is
\(lqxerxes\(rq,
then
.nf
.sp
.RS 4n
@include /etc/sudoers.%h
.RE
.fi
.PP
will cause
\fBsudo\fR
to include the file
\fI/etc/sudoers.xerxes\fR.
.PP
The
\fI@includedir\fR
directive can be used to create a
\fIsudoers.d\fR
directory that the system package manager can drop
\fIsudoers\fR
file rules into as part of package installation.
For example, given:
.nf
.sp
.RS 4n
@includedir /etc/sudoers.d
.RE
.fi
.PP
\fBsudo\fR
will suspend processing of the current file and read each file in
\fI/etc/sudoers.d\fR,
skipping file names that end in
\(oq~\(cq
or contain a
\(oq.\&\(cq
character to avoid causing problems with package manager or editor
temporary/backup files.
.PP
Files are parsed in sorted lexical order.
That is,
\fI/etc/sudoers.d/01_first\fR
will be parsed before
\fI/etc/sudoers.d/10_second\fR.
Be aware that because the sorting is lexical, not numeric,
\fI/etc/sudoers.d/1_whoops\fR
would be loaded
\fIafter\fR
\fI/etc/sudoers.d/10_second\fR.
Using a consistent number of leading zeroes in the file names can be used
to avoid such problems.
After parsing the files in the directory, control returns to the
file that contained the
\fI@includedir\fR
directive.
.PP
Unlike files included via
\fI@include\fR,
\fBvisudo\fR
will not edit the files in a
\fI@includedir\fR
directory unless one of them contains a syntax error.
It is still possible to run
\fBvisudo\fR
with the
\fB\-f\fR
flag to edit the files directly, but this will not catch the
redefinition of an
\fIalias\fR
that is also present in a different file.
.SS "Other special characters and reserved words"
The pound sign
(\(oq#\(cq)
is used to indicate a comment (unless it is part of a #include
directive or unless it occurs in the context of a user name and is
followed by one or more digits, in which case it is treated as a
user-ID).
Both the comment character and any text after it, up to the end of
the line, are ignored.
.PP
The reserved word
\fBALL\fR
is a built-in
\fIalias\fR
that always causes a match to succeed.
It can be used wherever one might otherwise use a
\fICmnd_Alias\fR,
\fIUser_Alias\fR,
\fIRunas_Alias\fR,
or
\fIHost_Alias\fR.
Attempting to define an
\fIalias\fR
named
\fBALL\fR
will result in a syntax error.
Using
\fBALL\fR
can be dangerous since in a command context, it allows the user to run
\fIany\fR
command on the system.
.PP
The following option names permitted in an
\fIOption_Spec\fR
are also considered reserved words:
\fRCHROOT\fR,
.if \n(PS \{\
\fRPRIVS\fR,
.\}
.if \n(PS \{\
\fRLIMITPRIVS\fR,
.\}
.if \n(SL \{\
\fRROLE\fR,
.\}
.if \n(SL \{\
\fRTYPE\fR,
.\}
\fRTIMEOUT\fR,
\fRCWD\fR,
\fRNOTBEFORE\fR
and
\fRNOTAFTER\fR.
Attempting to define an
\fIalias\fR
with the same name as one of the options will result in a syntax error.
.PP
An exclamation point
(\(oq\&!\(cq)
can be used as a logical
\fInot\fR
operator in a list or
\fIalias\fR
as well as in front of a
\fICmnd\fR.
This allows one to exclude certain values.
For the
\(oq\&!\(cq
operator to be effective, there must be something for it to exclude.
For example, to match all users except for
\fBroot\fR
one would use:
.nf
.sp
.RS 4n
ALL, !root
.RE
.fi
.PP
If the
\fBALL\fR,
is omitted, as in:
.nf
.sp
.RS 4n
!root
.RE
.fi
.PP
it would explicitly deny
\fBroot\fR
but not match any other users.
This is different from a true
\(lqnegation\(rq
operator.
.PP
Note, however, that using a
\(oq\&!\(cq
in conjunction with the built-in
\fBALL\fR
alias to allow a user to run
\(lqall but a few\(rq
commands rarely works as intended (see
\fISECURITY NOTES\fR
below).
.PP
Long lines can be continued with a backslash
(\(oq\e\(cq)
as the last character on the line.
.PP
White space between elements in a list as well as special syntactic
characters in a
\fIUser Specification\fR
(\(oq=\&\(cq,
\(oq:\&\(cq,
\(oq(\&\(cq,
\(oq)\&\(cq)
is optional.
.PP
The following characters must be escaped with a backslash
(\(oq\e\(cq)
when used as part of a word (e.g., a user name or host name):
\(oq\&!\(cq,
\(oq=\&\(cq,
\(oq:\&\(cq,
\(oq,\&\(cq,
\(oq(\&\(cq,
\(oq)\&\(cq,
\(oq\e\(cq.
.SH "SUDOERS OPTIONS"
\fBsudo\fR's
behavior can be modified by
\fIDefault_Entry\fR
lines, as explained earlier.
A list of all supported Defaults parameters, grouped by type, are listed below.
.PP
\fBBoolean Flags\fR:
.TP 18n
always_query_group_plugin
If a
\fIgroup_plugin\fR
is configured, use it to resolve groups of the form
\(oq%group\(cq
as long as there is not also a system group of the same name.
Normally, only groups of the form
\(oq%:group\(cq
are passed to the
\fIgroup_plugin\fR.
This flag is
\fIoff\fR
by default.
.TP 18n
always_set_home
If enabled,
\fBsudo\fR
will set the
\fRHOME\fR
environment variable to the home directory of the target user
(which is the
\fIrunas_default\fR
user unless the
\fB\-u\fR
option is used).
This flag is largely obsolete and has no effect unless the
\fIenv_reset\fR
flag has been disabled or
\fRHOME\fR
is present in the
\fIenv_keep\fR
list, both of which are strongly discouraged.
This flag is
\fIoff\fR
by default.
.TP 18n
authenticate
If set, users must authenticate themselves via a password (or other
means of authentication) before they may run commands.
This default may be overridden via the
\fRPASSWD\fR
and
\fRNOPASSWD\fR
tags.
This flag is
\fIon\fR
by default.
.TP 18n
case_insensitive_group
If enabled, group names in
\fIsudoers\fR
will be matched in a case insensitive manner.
This may be necessary when users are stored in LDAP or AD.
This flag is
\fIon\fR
by default.
.TP 18n
case_insensitive_user
If enabled, user names in
\fIsudoers\fR
will be matched in a case insensitive manner.
This may be necessary when groups are stored in LDAP or AD.
This flag is
\fIon\fR
by default.
.TP 18n
closefrom_override
If set, the user may use the
\fB\-C\fR
option which overrides the default starting point at which
\fBsudo\fR
begins closing open file descriptors.
This flag is
\fIoff\fR
by default.
.TP 18n
compress_io
If set, and
\fBsudo\fR
is configured to log a command's input or output,
the I/O logs will be compressed using
\fBzlib\fR.
This flag is
\fIon\fR
by default when
\fBsudo\fR
is compiled with
\fBzlib\fR
support.
.TP 18n
exec_background
By default,
\fBsudo\fR
runs a command as the foreground process as long as
\fBsudo\fR
itself is running in the foreground.
When the
\fIexec_background\fR
flag is enabled and the command is being run in a pseudo-terminal
(due to I/O logging or the
\fIuse_pty\fR
flag), the command will be run as a background process.
Attempts to read from the controlling terminal (or to change terminal
settings) will result in the command being suspended with the
\fRSIGTTIN\fR
signal (or
\fRSIGTTOU\fR
in the case of terminal settings).
If this happens when
\fBsudo\fR
is a foreground process, the command will be granted the controlling terminal
and resumed in the foreground with no user intervention required.
The advantage of initially running the command in the background is that
\fBsudo\fR
need not read from the terminal unless the command explicitly requests it.
Otherwise, any terminal input must be passed to the command, whether it
has required it or not (the kernel buffers terminals so it is not possible
to tell whether the command really wants the input).
This is different from historic
\fIsudo\fR
behavior or when the command is not being run in a pseudo-terminal.
.sp
For this to work seamlessly, the operating system must support the
automatic restarting of system calls.
Unfortunately, not all operating systems do this by default,
and even those that do may have bugs.
For example, macOS fails to restart the
tcgetattr(3)
and
tcsetattr(3)
functions (this is a bug in macOS).
Furthermore, because this behavior depends on the command stopping with the
\fRSIGTTIN\fR
or
\fRSIGTTOU\fR
signals, programs that catch these signals and suspend themselves
with a different signal (usually
\fRSIGTOP\fR)
will not be automatically foregrounded.
Some versions of the linux
su(1)
command behave this way.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.8.7 or higher.
It has no effect unless I/O logging is enabled or the
\fIuse_pty\fR
flag is enabled.
.TP 18n
env_editor
If set,
\fBvisudo\fR
will use the value of the
\fRSUDO_EDITOR\fR,
\fRVISUAL\fR
or
\fREDITOR\fR
environment variables before falling back on the default editor list.
\fBvisudo\fR
is typically run as
\fBroot\fR
so this flag may allow a user with
\fBvisudo\fR
privileges to run arbitrary commands as
\fBroot\fR
without logging.
An alternative is to place a colon-separated list of
\(lqsafe\(rq
editors int the
\fIeditor\fR
setting.
\fBvisudo\fR
will then only use
\fRSUDO_EDITOR\fR,
\fRVISUAL\fR
or
\fREDITOR\fR
if they match a value specified in
\fIeditor\fR.
If the
\fIenv_reset\fR
flag is enabled, the
\fRSUDO_EDITOR\fR,
\fRVISUAL\fR
and/or
\fREDITOR\fR
environment variables must be present in the
\fIenv_keep\fR
list for the
\fIenv_editor\fR
flag to function when
\fBvisudo\fR
is invoked via
\fBsudo\fR.
This flag is
\fI@env_editor@\fR
by default.
.TP 18n
env_reset
If set,
\fBsudo\fR
will run the command in a minimal environment containing the
\fRTERM\fR,
\fRPATH\fR,
\fRHOME\fR,
\fRMAIL\fR,
\fRSHELL\fR,
\fRLOGNAME\fR,
\fRUSER\fR
and
\fRSUDO_*\fR
variables.
Any variables in the caller's environment or in the file specified
by the
\fIrestricted_env_file\fR
setting that match the
\fIenv_keep\fR
and
\fIenv_check\fR
lists are then added, followed by any variables present in the file
specified by the
\fIenv_file\fR
setting (if any).
The contents of the
\fIenv_keep\fR
and
\fIenv_check\fR
lists, as modified by global Defaults parameters in
\fIsudoers\fR,
are displayed when
\fBsudo\fR
is run by
\fBroot\fR
with the
\fB\-V\fR
option.
If the
\fIsecure_path\fR
setting is enabled, its value will be used for the
\fRPATH\fR
environment variable.
This flag is
\fI@env_reset@\fR
by default.
.TP 18n
fast_glob
Normally,
\fBsudo\fR
uses the
glob(3)
function to do shell-style globbing when matching path names.
However, since it accesses the file system,
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 (auto mounted).
The
\fIfast_glob\fR
flag causes
\fBsudo\fR
to use the
fnmatch(3)
function, which does not access the file system to do its matching.
The disadvantage of
\fIfast_glob\fR
is that it is unable to match relative paths such as
\fI./ls\fR
or
\fI../bin/ls\fR.
This has security implications when path names that include globbing
characters are used with the negation operator,
\(oq!\&\(cq,
as such rules can be trivially bypassed.
As such, this flag should not be used when the
\fIsudoers\fR
file contains rules that contain negated path names which include globbing
characters.
This flag is
\fIoff\fR
by default.
.TP 18n
log_passwords
Most programs that require a user's password will disable echo before
reading the password to avoid displaying the plaintext password on
the screen.
However, if terminal input is being logged (see
\fII/O LOGGING\fR),
the password will still be present in the I/O log.
If the
\fIlog_passwords\fR
option is disabled,
\fBsudoers\fR
will attempt to prevent passwords from being logged.
It does this by using the regular expressions in
\fIpassprompt_regex\fR
to match a password prompt in the terminal output buffer.
When a match is found, input characters in the I/O log will be replaced with
\(oq*\(cq
until either a line feed or carriage return is found in the terminal input
or a new terminal output buffer is received.
If, however, a program displays characters as the user types
(such as
\fBsudo\fR
when
\fIpwfeedback\fR
is set), only the
first character of the password will be replaced in the I/O log.
This option has no effect unless
\fIlog_input\fR
or
\fIlog_ttyin\fR
are also set.
This flag is
\fIon\fR
by default.
.sp
This setting is only supported by version 1.9.10 or higher.
.TP 18n
fqdn
Set this flag if you want to put fully qualified host names in the
\fIsudoers\fR
file when the local host name (as returned by the
\(oqhostname\(cq
command) does not contain the domain name.
In other words, instead of myhost you would use myhost.mydomain.edu.
You may still use the short form if you wish (and even mix the two).
This flag is only effective when the
\(lqcanonical\(rq
host name, as returned by the
getaddrinfo(3)
or
gethostbyname(3)
function, is a fully-qualified domain name.
This is usually the case when the system is configured to use DNS
for host name resolution.
.sp
If the system is configured to use the
\fI/etc/hosts\fR
file in preference to DNS, the
\(lqcanonical\(rq
host name may not be fully-qualified.
The order that sources are queried for host name resolution
is usually specified in the
\fI@nsswitch_conf@\fR,
\fI@netsvc_conf@\fR,
\fI/etc/host.conf\fR,
or, in some cases,
\fI/etc/resolv.conf\fR
file.
In the
\fI/etc/hosts\fR
file, the first host name of the entry is considered to be the
\(lqcanonical\(rq
name; subsequent names are aliases that are not used by
\fBsudoers\fR.
For example, the following hosts file line for the machine
\(lqxyzzy\(rq
has the fully-qualified domain name as the
\(lqcanonical\(rq
host name, and the short version as an alias.
.sp
.RS 24n
192.168.1.1 xyzzy.sudo.ws xyzzy
.RE
.RS 18n
.sp
If the machine's hosts file entry is not formatted properly, the
\fIfqdn\fR
flag will not be effective if it is queried before DNS.
.sp
Beware that when using DNS for host name resolution, turning on
\fIfqdn\fR
requires
\fBsudoers\fR
to make DNS lookups which renders
\fBsudo\fR
unusable if DNS stops working (for example if the machine is disconnected
from the network).
Just like with the hosts file, you must use the
\(lqcanonical\(rq
name as DNS knows it.
That is, you may not use a host alias (CNAME entry) due to performance
issues and the fact that there is no way to get all aliases from DNS.
.sp
This flag is
\fI@fqdn@\fR
by default.
.RE
.TP 18n
ignore_audit_errors
Allow commands to be run even if
\fBsudoers\fR
cannot write to the audit log.
If enabled, an audit log write failure is not treated as a fatal error.
If disabled, a command may only be run after the audit event is successfully
written.
This flag is only effective on systems for which
\fBsudoers\fR
supports audit logging, including
FreeBSD,
Linux, macOS, and Solaris.
This flag is
\fIon\fR
by default.
.TP 18n
ignore_dot
If set,
\fBsudo\fR
will ignore "." or "" (both denoting the current directory) in the
\fRPATH\fR
environment variable; the
\fRPATH\fR
itself is not modified.
This flag is
\fI@ignore_dot@\fR
by default.
.TP 18n
ignore_iolog_errors
Allow commands to be run even if
\fBsudoers\fR
cannot write to the I/O log (local or remote).
If enabled, an I/O log write failure is not treated as a fatal error.
If disabled, the command will be terminated if the I/O log cannot be written to.
This flag is
\fIoff\fR
by default.
.TP 18n
ignore_logfile_errors
Allow commands to be run even if
\fBsudoers\fR
cannot write to the log file.
If enabled, a log file write failure is not treated as a fatal error.
If disabled, a command may only be run after the log file entry is successfully
written.
This flag only has an effect when
\fBsudoers\fR
is configured to use file-based logging via the
\fIlogfile\fR
setting.
This flag is
\fIon\fR
by default.
.TP 18n
ignore_local_sudoers
If set via LDAP, parsing of
\fI@sysconfdir@/sudoers\fR
will be skipped.
This is intended for sites that wish to prevent the usage of local
sudoers files so that only LDAP is used.
This thwarts the efforts of rogue operators who would attempt to add roles to
\fI@sysconfdir@/sudoers\fR.
When this flag is enabled,
\fI@sysconfdir@/sudoers\fR
does not even need to exist.
Since this flag tells
\fBsudo\fR
how to behave when no specific LDAP entries have been matched, this
sudoOption is only meaningful for the
\(oqcn=defaults\(cq
section.
This flag is
\fIoff\fR
by default.
.TP 18n
ignore_unknown_defaults
If set,
\fBsudo\fR
will not produce a warning if it encounters an unknown Defaults entry
in the
\fIsudoers\fR
file or an unknown sudoOption in LDAP.
This flag is
\fIoff\fR
by default.
.TP 18n
insults
If set,
\fBsudo\fR
will insult users when they enter an incorrect password.
This flag is
\fI@insults@\fR
by default.
.TP 18n
log_allowed
If set,
\fBsudoers\fR
will log commands allowed by the policy to the system audit log
(where supported) as well as to syslog and/or a log file.
This flag is
\fIon\fR
by default.
.sp
This setting is only supported by version 1.8.29 or higher.
.TP 18n
log_denied
If set,
\fBsudoers\fR
will log commands denied by the policy to the system audit log
(where supported) as well as to syslog and/or a log file.
This flag is
\fIon\fR
by default.
.sp
This setting is only supported by version 1.8.29 or higher.
.TP 18n
log_exit_status
If set,
\fBsudoers\fR
will log the exit value of commands that are run to syslog and/or a log file.
If a command was terminated by a signal, the signal name is logged as well.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.9.8 or higher.
.TP 18n
log_host
If set, the host name will be included in log entries written to
the file configured by the
\fIlogfile\fR
setting.
This flag is
\fIoff\fR
by default.
.TP 18n
log_input
If set,
\fBsudo\fR
will run the command in a pseudo-terminal (if
\fBsudo\fR
was run from a terminal) and log all user input.
If the standard input is not connected to the user's terminal, due
to I/O redirection or because the command is part of a pipeline,
that input is also logged.
For more information about I/O logging, see the
\fII/O LOGGING\fR
section.
This flag is
\fIoff\fR
by default.
.TP 18n
log_output
If set,
\fBsudo\fR
will run the command in a pseudo-terminal (if
\fBsudo\fR
was run from a terminal) and log all output that is sent to the
user's terminal, the standard output or the standard error.
If the standard output or standard error is not connected to the
user's terminal, due to I/O redirection or because the command is
part of a pipeline, that output is also logged.
For more information about I/O logging, see the
\fII/O LOGGING\fR
section.
This flag is
\fIoff\fR
by default.
.TP 18n
log_server_keepalive
If set,
\fBsudo\fR
will enable the TCP keepalive socket option on the connection to the log server.
This enables the periodic transmission of keepalive messages to the server.
If the server does not respond to a message, the connection will
be closed and the running command will be terminated unless the
\fIignore_iolog_errors\fR
flag (I/O logging enabled) or the
\fIignore_log_errors\fR
flag (I/O logging disabled) is set.
This flag is
\fIon\fR
by default.
.sp
This setting is only supported by version 1.9.0 or higher.
.TP 18n
log_server_verify
.br
If set, the server certificate received during the TLS handshake
must be valid and it must contain either the server name (from
\fIlog_servers\fR)
or its IP address.
If either of these conditions is not met, the TLS handshake will fail.
This flag is
\fIon\fR
by default.
.sp
This setting is only supported by version 1.9.0 or higher.
.TP 18n
log_stderr
If set,
\fBsudo\fR
will log the standard error if it is not connected to the user's terminal.
This can be used to log output to a pipe or redirected to a file.
This flag is
\fIoff\fR
by default but is enabled when either the
\fIlog_output\fR
flag or the
\fRLOG_OUTPUT\fR
command tag is set.
.TP 18n
log_stdin
If set,
\fBsudo\fR
will log the standard input if it is not connected to the user's terminal.
This can be used to log input from a pipe or redirected from a file.
This flag is
\fIoff\fR
by default but is enabled when either the
\fIlog_input\fR
flag or the
\fRLOG_INPUT\fR
command tag is set.
.TP 18n
log_stdout
If set,
\fBsudo\fR
will log the standard output if it is not connected to the user's terminal.
This can be used to log output to a pipe or redirected to a file.
This flag is
\fIoff\fR
by default but is enabled when either the
\fIlog_output\fR
flag or the
\fRLOG_OUTPUT\fR
command tag is set.
.TP 18n
log_subcmds
If set,
\fBsudoers\fR
will log when a command spawns a child process and executes a program
using the
execve(2),
execl(3),
execle(3),
execlp(3),
execv(3),
execvp(3),
execvpe(3),
or
system(3)
library functions.
For example, if a shell is run by
\fBsudo\fR,
the individual commands run via the shell will be logged.
This flag is
\fIoff\fR
by default.
.sp
The
\fIlog_subcmds\fR
flag uses the same underlying mechanism as the
\fIintercept\fR
setting.
See
\fIPreventing shell escapes\fR
for more information on what systems support this option and its limitations.
This setting is only supported by version 1.9.8 or higher
and is incompatible with SELinux RBAC support unless the system supports
seccomp(2)
filter mode.
.TP 18n
log_ttyin
If set,
\fBsudo\fR
will run the command in a pseudo-terminal and log user keystrokes
sent to the user's terminal, if one is present.
This flag is
\fIoff\fR
by default but is enabled when either the
\fIlog_input\fR
flag or the
\fRLOG_INPUT\fR
command tag is set.
If no terminal is present, for example when running a remote command using
ssh(1),
this flag will have no effect.
.TP 18n
log_ttyout
If set,
\fBsudo\fR
will run the command in a pseudo-terminal and log all output displayed
on the user's terminal, if one is present.
This flag is
\fIoff\fR
by default but is enabled when either the
\fIlog_output\fR
flag or the
\fRLOG_OUTPUT\fR
command tag is set.
If no terminal is present, for example when running a remote command using
ssh(1),
this flag will have no effect.
.TP 18n
log_year
If set, the four-digit year will be logged in the (non-syslog)
\fBsudo\fR
log file.
This flag is
\fIoff\fR
by default.
.TP 18n
long_otp_prompt
When validating with a One Time Password (OTP) scheme such as
\fBS/Key\fR
or
\fBOPIE\fR,
a two-line prompt is used to make it easier
to cut and paste the challenge to a local window.
It's not as pretty as the default but some people find it more convenient.
This flag is
\fI@long_otp_prompt@\fR
by default.
.TP 18n
mail_all_cmnds
Send mail to the
\fImailto\fR
user every time a user attempts to run a command via
\fBsudo\fR
(this includes
\fBsudoedit\fR).
No mail will be sent if the user runs
\fBsudo\fR
with the
\fB\-l\fR
or
\fB\-v\fR
option unless there is an authentication error and the
\fImail_badpass\fR
flag is also set.
This flag is
\fIoff\fR
by default.
.TP 18n
mail_always
Send mail to the
\fImailto\fR
user every time a user runs
\fBsudo\fR.
This flag is
\fIoff\fR
by default.
.TP 18n
mail_badpass
Send mail to the
\fImailto\fR
user if the user running
\fBsudo\fR
does not enter the correct password.
If the command the user is attempting to run is not permitted by
\fBsudoers\fR
and one of the
\fImail_all_cmnds\fR,
\fImail_always\fR,
\fImail_no_host\fR,
\fImail_no_perms\fR
or
\fImail_no_user\fR
flags are set, this flag will have no effect.
This flag is
\fIoff\fR
by default.
.TP 18n
mail_no_host
If set, mail will be sent to the
\fImailto\fR
user if the invoking user exists in the
\fIsudoers\fR
file, but is not allowed to run commands on the current host.
This flag is
\fI@mail_no_host@\fR
by default.
.TP 18n
mail_no_perms
If set, mail will be sent to the
\fImailto\fR
user if the invoking user is allowed to use
\fBsudo\fR
but the command they are trying is not listed in their
\fIsudoers\fR
file entry or is explicitly denied.
This flag is
\fI@mail_no_perms@\fR
by default.
.TP 18n
mail_no_user
If set, mail will be sent to the
\fImailto\fR
user if the invoking user is not in the
\fIsudoers\fR
file.
This flag is
\fI@mail_no_user@\fR
by default.
.TP 18n
match_group_by_gid
By default,
\fBsudoers\fR
will look up each group the user is a member of by group-ID to
determine the group name (this is only done once).
The resulting list of the user's group names is used when matching
groups listed in the
\fIsudoers\fR
file.
This works well on systems where the number of groups listed in the
\fIsudoers\fR
file is larger than the number of groups a typical user belongs to.
On systems where group lookups are slow, where users may belong
to a large number of groups, or where the number of groups listed
in the
\fIsudoers\fR
file is relatively small, it may be prohibitively expensive and
running commands via
\fBsudo\fR
may take longer than normal.
On such systems it may be faster to use the
\fImatch_group_by_gid\fR
flag to avoid resolving the user's group-IDs to group names.
In this case,
\fBsudoers\fR
must look up any group name listed in the
\fIsudoers\fR
file and use the group-ID instead of the group name when determining
whether the user is a member of the group.
.sp
If
\fImatch_group_by_gid\fR
is enabled, group database lookups performed by
\fBsudoers\fR
will be keyed by group name as opposed to group-ID.
On systems where there are multiple sources for the group database,
it is possible to have conflicting group names or group-IDs in the local
\fI/etc/group\fR
file and the remote group database.
On such systems, enabling or disabling
\fImatch_group_by_gid\fR
can be used to choose whether group database queries are performed
by name (enabled) or ID (disabled), which may aid in working around
group entry conflicts.
.sp
The
\fImatch_group_by_gid\fR
flag has no effect when
\fIsudoers\fR
data is stored in LDAP.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.8.18 or higher.
.TP 18n
intercept
If set, all commands run via
\fBsudo\fR
will behave as if the
\fRINTERCEPT\fR
tag has been set, unless overridden by an
\fRNOINTERCEPT\fR
tag.
See the description of
\fRINTERCEPT and NOINTERCEPT\fR
above as well as the
\fIPreventing shell escapes\fR
section at the end of this manual.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.9.8 or higher
and is incompatible with SELinux RBAC support unless the system supports
seccomp(2)
filter mode.
.TP 18n
intercept_allow_setid
On most systems, the dynamic loader will ignore
\fRLD_PRELOAD\fR
(or the equivalent) when running set-user-ID and set-group-ID
programs, effectively disabling intercept mode.
To prevent this from happening,
\fBsudoers\fR
will not permit a set-user-ID or set-group-ID program to be run in
intercept mode unless
\fIintercept_allow_setid\fR
is enable.
This flag has no effect unless the
\fIintercept\fR
flag is enabled or the
\fRINTERCEPT\fR
tag has been set for the command.
This flag is
\fIon\fR
by default when the
\fIintercept_type\fR
option is set to
\fItrace\fR,
otherwise it default to
\fIoff\fR.
.sp
This setting is only supported by version 1.9.8 or higher.
.TP 18n
intercept_authenticate
If set, commands run by an intercepted process must be authenticated
when the user's time stamp is not current.
For example, if a shell is run with
\fIintercept\fR
enabled, as soon as the invoking user's time stamp is out of date,
subsequent commands will need to be authenticated.
This flag has no effect unless the
\fIintercept\fR
flag is enabled or the
\fRINTERCEPT\fR
tag has been set for the command.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.9.8 or higher.
.TP 18n
intercept_verify
If set,
\fBsudo\fR
will attempt to verify that a command run in intercept mode has
the expected path name, command line arguments and environment.
.sp
The process will be stopped after
execve(2)
has completed but before the new command has had a chance to run.
To verify the command,
\fBsudo\fR
will read the command's path from
\fI/proc/PID/exe\fR,
the command line arguments and environment from the process's memory,
and compare them against the arguments that were passed to
execve(2).
In the event of a mismatch, the command will be sent a
\fRSIGKILL\fR
signal and terminated.
.sp
This can help prevent a time of check versus time of use issue with
intercept mode where the
execve(2)
arguments could be altered after the
\fBsudoers\fR
policy check.
The checks can only be performed if the
proc(@mansectform@)
file system is available.
This flag has no effect unless the
\fIintercept\fR
flag is enabled or the
\fRINTERCEPT\fR
tag has been set for the command and the
\fIintercept_type\fR
option is set to
\fItrace\fR.
This flag is
\fIon\fR
by default.
.sp
This setting is only supported by version 1.9.12 or higher.
.TP 18n
netgroup_tuple
If set, netgroup lookups will be performed using the full netgroup
tuple: host name, user name, and domain (if one is set).
Historically,
\fBsudo\fR
only matched the user name and domain for netgroups used in a
\fIUser_List\fR
and only matched the host name and domain for netgroups used in a
\fIHost_List\fR.
This flag is
\fIoff\fR
by default.
.TP 18n
noexec
If set, all commands run via
\fBsudo\fR
will behave as if the
\fRNOEXEC\fR
tag has been set, unless overridden by an
\fREXEC\fR
tag.
See the description of
\fREXEC and NOEXEC\fR
above as well as the
\fIPreventing shell escapes\fR
section at the end of this manual.
This flag is
\fIoff\fR
by default.
.TP 18n
noninteractive_auth
If set, authentication will be attempted even in non-interactive mode
(when
\fBsudo\fR's
\fB\-n\fR
option is specified).
This allows authentication methods that don't require user interaction
to succeed.
Authentication methods that require input from the user's terminal
will still fail.
If disabled, authentication will not be attempted in non-interactive mode.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.9.10 or higher.
.TP 18n
pam_acct_mgmt
On systems that use PAM for authentication,
\fBsudo\fR
will perform PAM account validation for the invoking user by default.
The actual checks performed depend on which PAM modules are configured.
If enabled, account validation will be performed regardless of whether
or not a password is required.
This flag is
\fIon\fR
by default.
.sp
This setting is only supported by version 1.8.28 or higher.
.TP 18n
pam_rhost
On systems that use PAM for authentication,
\fBsudo\fR
will set the PAM remote host value to the name of the local host
when the
\fIpam_rhost\fR
flag is enabled.
On Linux systems, enabling
\fIpam_rhost\fR
may result in DNS lookups of the local host name when PAM is initialized.
On Solaris versions prior to Solaris 8,
\fIpam_rhost\fR
must be enabled if
\fIpam_ruser\fR
is also enabled to avoid a crash in the Solaris PAM implementation.
.sp
This flag is
\fIoff\fR
by default on systems other than Solaris.
.sp
This setting is only supported by version 1.9.0 or higher.
.TP 18n
pam_ruser
On systems that use PAM for authentication,
\fBsudo\fR
will set the PAM remote user value to the name of the user that invoked sudo
when the
\fIpam_ruser\fR
flag is enabled.
This flag is
\fIon\fR
by default.
.sp
This setting is only supported by version 1.9.0 or higher.
.TP 18n
pam_session
On systems that use PAM for authentication,
\fBsudo\fR
will create a new PAM session for the command to be run in.
Unless
\fBsudo\fR
is given the
\fB\-i\fR
or
\fB\-s\fR
options, PAM session modules are run with the
\(lqsilent\(rq
flag enabled.
This prevents last login information from being displayed for every
command on some systems.
Disabling
\fIpam_session\fR
may be needed on older PAM implementations or on operating systems where
opening a PAM session changes the utmp or wtmp files.
If PAM session support is disabled, resource limits may not be updated
for the command being run.
If
\fIpam_session\fR,
\fIpam_setcred\fR,
and
\fIuse_pty\fR
are disabled,
\fIlog_servers\fR
has not been set and I/O logging has not been configured,
\fBsudo\fR
will execute the command directly instead of running it as a child
process.
This flag is
\fI@pam_session@\fR
by default.
.sp
This setting is only supported by version 1.8.7 or higher.
.TP 18n
pam_setcred
On systems that use PAM for authentication,
\fBsudo\fR
will attempt to establish credentials for the target user by default,
if supported by the underlying authentication system.
One example of a credential is a Kerberos ticket.
If
\fIpam_session\fR,
\fIpam_setcred\fR,
and
\fIuse_pty\fR
are disabled,
\fIlog_servers\fR
has not been set and I/O logging has not been configured,
\fBsudo\fR
will execute the command directly instead of running it as a child
process.
This flag is
\fIon\fR
by default.
.sp
This setting is only supported by version 1.8.8 or higher.
.TP 18n
passprompt_override
If set, the prompt specified by
\fIpassprompt\fR
or the
\fRSUDO_PROMPT\fR
environment variable will always be used and will replace the
prompt provided by a PAM module or other authentication method.
This flag is
\fIoff\fR
by default.
.TP 18n
path_info
Normally,
\fBsudo\fR
will tell the user when a command could not be
found in their
\fRPATH\fR
environment variable.
Some sites may wish to disable this as it could be used to gather
information on the location of executables that the normal user does
not have access to.
The disadvantage is that if the executable is simply not in the user's
\fRPATH\fR,
\fBsudo\fR
will tell the user that they are not allowed to run it, which can be confusing.
This flag is
\fI@path_info@\fR
by default.
.TP 18n
preserve_groups
By default,
\fBsudo\fR
will initialize the group vector to the list of groups the target user is in.
When
\fIpreserve_groups\fR
is set, the user's existing group vector is left unaltered.
The real and effective group-IDs, however, are still set to match the
target user.
This flag is
\fIoff\fR
by default.
.TP 18n
pwfeedback
By default,
\fBsudo\fR
reads the password like most other Unix programs,
by turning off echo until the user hits the return (or enter) key.
Some users become confused by this as it appears to them that
\fBsudo\fR
has hung at this point.
When
\fIpwfeedback\fR
is set,
\fBsudo\fR
will provide visual feedback when the user presses a key.
This does have a security impact as an onlooker may be able to
determine the length of the password being entered.
This flag is
\fIoff\fR
by default.
.TP 18n
requiretty
If set,
\fBsudo\fR
will only run when the user is logged in to a real tty.
When this flag is set,
\fBsudo\fR
can only be run from a login session and not via other means such as
cron(@mansectsu@)
or cgi-bin scripts.
This flag is
\fIoff\fR
by default.
.TP 18n
root_sudo
If set,
\fBroot\fR
is allowed to run
\fBsudo\fR
too.
Disabling this prevents users from
\(lqchaining\(rq
\fBsudo\fR
commands to get a
\fBroot\fR
shell by doing something like
\(oqsudo sudo /bin/sh\(cq.
Note, however, that turning off
\fIroot_sudo\fR
will also prevent
\fBroot\fR
from running
\fBsudoedit\fR.
Disabling
\fIroot_sudo\fR
provides no real additional security; it exists purely for historical reasons.
This flag is
\fI@root_sudo@\fR
by default.
.TP 18n
rootpw
If set,
\fBsudo\fR
will prompt for the
\fBroot\fR
password instead of the password of the invoking user
when running a command or editing a file.
This flag is
\fIoff\fR
by default.
.TP 18n
runas_allow_unknown_id
If enabled, allow matching of runas user and group IDs that are
not present in the password or group databases.
In addition to explicitly matching unknown user or group IDs in a
\fIRunas_List\fR,
this option also allows the
\fBALL\fR
alias to match unknown IDs.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.8.30 or higher.
Older versions of
\fBsudo\fR
always allowed matching of unknown user and group IDs.
.TP 18n
runas_check_shell
.br
If enabled,
\fBsudo\fR
will only run commands as a user whose shell appears in the
\fI/etc/shells\fR
file, even if the invoking user's
\fIRunas_List\fR
would otherwise permit it.
If no
\fI/etc/shells\fR
file is present, a system-dependent list of built-in default shells is used.
On many operating systems, system users such as
\(lqbin\(rq,
do not have a valid shell and this flag can be used to prevent
commands from being run as those users.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.8.30 or higher.
.TP 18n
runaspw
If set,
\fBsudo\fR
will prompt for the password of the user defined by the
\fIrunas_default\fR
option (defaults to
\fB@runas_default@\fR)
instead of the password of the invoking user
when running a command or editing a file.
This flag is
\fIoff\fR
by default.
.if \n(SL \{\
.TP 18n
selinux
If enabled, the user may specify an SELinux role and/or type to use
when running the command, as permitted by the SELinux policy.
If SELinux is disabled on the system, this flag has no effect.
This flag is
\fIon\fR
by default.
.\}
.TP 18n
set_home
If enabled and
\fBsudo\fR
is invoked with the
\fB\-s\fR
option, the
\fRHOME\fR
environment variable will be set to the home directory of the target
user (which is the
\fIrunas_default\fR
user unless the
\fB\-u\fR
option is used).
This flag is largely obsolete and has no effect unless the
\fIenv_reset\fR
flag has been disabled or
\fRHOME\fR
is present in the
\fIenv_keep\fR
list, both of which are strongly discouraged.
This flag is
\fIoff\fR
by default.
.TP 18n
set_logname
Normally,
\fBsudo\fR
will set the
\fRLOGNAME\fR
and
\fRUSER\fR
environment variables to the name of the target user (the user specified by
\fIrunas_default\fR
unless the
\fB\-u\fR
option is given).
However, since some programs (including the RCS revision control system) use
\fRLOGNAME\fR
to determine the real identity of the user, it may be desirable to
change this behavior.
This can be done by negating the set_logname option.
The
\fIset_logname\fR
option will have no effect
if the
\fIenv_reset\fR
option has not been disabled and the
\fIenv_keep\fR
list contains
\fRLOGNAME\fR
or
\fRUSER\fR.
This flag is
\fIon\fR
by default.
.TP 18n
set_utmp
When enabled,
\fBsudo\fR
will create an entry in the utmp (or utmpx) file when a pseudo-terminal
is allocated.
A pseudo-terminal is allocated by
\fBsudo\fR
when it is running in a terminal and one or more of the
\fIlog_input\fR,
\fIlog_output\fR,
\fIlog_stdin\fR,
\fIlog_stdout\fR,
\fIlog_stderr\fR,
\fIlog_ttyin\fR,
\fIlog_ttyout\fR,
or
\fIuse_pty\fR
flags is enabled.
By default, the new entry will be a copy of the user's existing utmp
entry (if any), with the tty, time, type, and pid fields updated.
This flag is
\fIon\fR
by default.
.TP 18n
setenv
Allow the user to disable the
\fIenv_reset\fR
option from the command line via the
\fB\-E\fR
option.
Additionally, environment variables set via the command line are
not subject to the restrictions imposed by
\fIenv_check\fR,
\fIenv_delete\fR,
or
\fIenv_keep\fR.
As such, only trusted users should be allowed to set variables in this manner.
This flag is
\fIoff\fR
by default.
.TP 18n
shell_noargs
If set and
\fBsudo\fR
is invoked with no arguments it acts as if the
\fB\-s\fR
option had been given.
That is, it runs a shell as
\fBroot\fR
(the shell is determined by the
\fRSHELL\fR
environment variable if it is set, falling back on the shell listed
in the invoking user's /etc/passwd entry if not).
This flag is
\fIoff\fR
by default.
.TP 18n
stay_setuid
Normally, when
\fBsudo\fR
executes a command the real and effective user-IDs are set to the target
user
(\fB@runas_default@\fR
by default).
This option changes that behavior such that the real user-ID is left
as the invoking user's user-ID.
In other words, this makes
\fBsudo\fR
act as a set-user-ID wrapper.
This can be useful on systems that disable some potentially
dangerous functionality when a program is run set-user-ID.
This option is only effective on systems that support either the
setreuid(2)
or
setresuid(2)
system call.
This flag is
\fIoff\fR
by default.
.TP 18n
sudoedit_checkdir
.br
If set,
\fBsudoedit\fR
will check all directory components of the path to be edited for writability
by the invoking user.
Symbolic links will not be followed in writable directories and
\fBsudoedit\fR
will refuse to edit a file located in a writable directory.
These restrictions are not enforced when
\fBsudoedit\fR
is run by
\fBroot\fR.
On some systems, if all directory components of the path to be edited
are not readable by the target user,
\fBsudoedit\fR
will be unable to edit the file.
This flag is
\fIon\fR
by default.
.sp
This setting was first introduced in version 1.8.15 but initially
suffered from a race condition.
The check for symbolic links in writable intermediate directories
was added in version 1.8.16.
.TP 18n
sudoedit_follow
By default,
\fBsudoedit\fR
will not follow symbolic links when opening files.
The
\fIsudoedit_follow\fR
option can be enabled to allow
\fBsudoedit\fR
to open symbolic links.
It may be overridden on a per-command basis by the
\fRFOLLOW\fR
and
\fRNOFOLLOW\fR
tags.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.8.15 or higher.
.TP 18n
syslog_pid
When logging via
syslog(3),
include the process ID in the log entry.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.8.21 or higher.
.TP 18n
targetpw
If set,
\fBsudo\fR
will prompt for the password of the user specified
by the
\fB\-u\fR
option (defaults to the value of
\fIrunas_default\fR)
instead of the password of the invoking user
when running a command or editing a file.
This flag precludes the use of a user-ID not listed in the passwd
database as an argument to the
\fB\-u\fR
option.
This flag is
\fIoff\fR
by default.
.TP 18n
tty_tickets
If set, users must authenticate on a per-tty basis.
With this flag enabled,
\fBsudo\fR
will use a separate record in the time stamp file for each terminal.
If disabled, a single record is used for all login sessions.
.sp
This option has been superseded by the
\fItimestamp_type\fR
option.
.TP 18n
umask_override
If set,
\fBsudo\fR
will set the umask as specified in the
\fIsudoers\fR
file without modification.
This makes it possible to specify a umask in the
\fIsudoers\fR
file that is more permissive than the user's own umask and matches
historical behavior.
If
\fIumask_override\fR
is not set,
\fBsudo\fR
will set the umask to be the union of the user's umask and what is specified in
\fIsudoers\fR.
This flag is
\fI@umask_override@\fR
by default.
.if \n(BA \{\
.TP 18n
use_loginclass
If set,
\fBsudo\fR
will apply the defaults specified for the target user's login class
if one exists.
Only available if
\fBsudo\fR
is configured with the
\fR--with-logincap\fR
option.
This flag is
\fIoff\fR
by default.
.\}
.TP 18n
use_netgroups
If set, netgroups (prefixed with
\(oq+\(cq),
may be used in place of a user or host.
For LDAP-based sudoers, netgroup support requires an expensive
sub-string match on the server unless the
\fBNETGROUP_BASE\fR
directive is present in the
\fI@ldap_conf@\fR
file.
If netgroups are not needed, this option can be disabled to reduce the
load on the LDAP server.
This flag is
\fIon\fR
by default.
.TP 18n
use_pty
If set, and
\fBsudo\fR
is running in a terminal, the command will be run in a pseudo-terminal
(even if no I/O logging is being done).
If the
\fBsudo\fR
process is not attached to a terminal,
\fIuse_pty\fR
has no effect.
.sp
A malicious program run under
\fBsudo\fR
may be capable of injecting commands into the user's
terminal or running a background process that retains access to the
user's terminal device even after the main program has finished
executing.
By running the command in a separate pseudo-terminal, this attack is
no longer possible.
This flag is
\fIoff\fR
by default.
.TP 18n
user_command_timeouts
If set, the user may specify a timeout on the command line.
If the timeout expires before the command has exited, the
command will be terminated.
If a timeout is specified both in the
\fIsudoers\fR
file and on the command line, the smaller of the two timeouts will be used.
See the
\fITimeout_Spec\fR
section for a description of the timeout syntax.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.8.20 or higher.
.TP 18n
utmp_runas
If set,
\fBsudo\fR
will store the name of the runas user when updating the utmp (or utmpx) file.
By default,
\fBsudo\fR
stores the name of the invoking user.
This flag is
\fIoff\fR
by default.
.TP 18n
visiblepw
By default,
\fBsudo\fR
will refuse to run if the user must enter a password but it is not
possible to disable echo on the terminal.
If the
\fIvisiblepw\fR
flag is set,
\fBsudo\fR
will prompt for a password even when it would be visible on the screen.
This makes it possible to run things like
\(oqssh somehost sudo ls\(cq
since by default,
ssh(1)
does
not allocate a tty when running a command.
This flag is
\fIoff\fR
by default.
.PP
\fBIntegers\fR:
.TP 18n
closefrom
Before it executes a command,
\fBsudo\fR
will close all open file descriptors other than standard input,
standard output, and standard error (file descriptors 0-2).
The
\fIclosefrom\fR
option can be used to specify a different file descriptor at which
to start closing.
The default is 3.
.TP 18n
command_timeout
The maximum amount of time a command is allowed to run before
it is terminated.
See the
\fITimeout_Spec\fR
section for a description of the timeout syntax.
.sp
This setting is only supported by version 1.8.20 or higher.
.TP 18n
log_server_timeout
The maximum amount of time to wait when connecting to a log server
or waiting for a server response.
See the
\fITimeout_Spec\fR
section for a description of the timeout syntax.
The default value is 30 seconds.
.sp
This setting is only supported by version 1.9.0 or higher.
.TP 18n
maxseq
The maximum sequence number that will be substituted for the
\(oq%{seq}\(cq
escape in the I/O log file (see the
\fIiolog_dir\fR
description below for more information).
While the value substituted for
\(oq%{seq}\(cq
is in base 36,
\fImaxseq\fR
itself should be expressed in decimal.
Values larger than 2176782336 (which corresponds to the
base 36 sequence number
\(lqZZZZZZ\(rq)
will be silently truncated to 2176782336.
The default value is 2176782336.
.sp
Once the local sequence number reaches the value of
\fImaxseq\fR,
it will
\(lqroll over\(rq
to zero, after which
\fBsudoers\fR
will truncate and re-use any existing I/O log path names.
.sp
This setting is only supported by version 1.8.7 or higher.
.TP 18n
passwd_tries
The number of tries a user gets to enter his/her password before
\fBsudo\fR
logs the failure and exits.
The default is @passwd_tries@.
.TP 18n
syslog_maxlen
On many systems,
syslog(3)
has a relatively small log buffer.
IETF RFC 5424 states that syslog servers must support messages of
at least 480 bytes and should support messages up to 2048 bytes.
By default,
\fBsudoers\fR
creates log messages up to 980 bytes which corresponds to the
historic
BSD
syslog implementation which used a 1024 byte buffer
to store the message, date, hostname, and program name.
To prevent syslog messages from being truncated,
\fBsudoers\fR
will split up log messages that are larger than
\fIsyslog_maxlen\fR
bytes.
When a message is split, additional parts will include the string
\(lq(command continued)\(rq
after the user name and before the continued command line arguments.
.sp
This setting is only supported by version 1.8.19 or higher.
.PP
\fBIntegers that can be used in a boolean context\fR:
.TP 18n
loglinelen
Number of characters per line for the file log.
This value is used to decide when to wrap lines for nicer log files.
This has no effect on the syslog log file, only the file log.
The default is @loglen@ (use 0 or negate the option to disable word wrap).
.TP 18n
passwd_timeout
Number of minutes before the
\fBsudo\fR
password prompt times out, or 0 for no timeout.
The timeout may include a fractional component
if minute granularity is insufficient, for example 2.5.
The default is @password_timeout@.
.TP 18n
timestamp_timeout
.br
Number of minutes that can elapse before
\fBsudo\fR
will ask for a password again.
The timeout may include a fractional component if
minute granularity is insufficient, for example 2.5.
The default is @timeout@.
Set this to 0 to always prompt for a password.
If set to a value less than 0 the user's time stamp will not expire
until the system is rebooted.
This can be used to allow users to create or delete their own time stamps via
\(oqsudo -v\(cq
and
\(oqsudo -k\(cq
respectively.
.TP 18n
umask
File mode creation mask to use when running the command.
Negate this option or set it to 0777 to prevent
\fBsudoers\fR
from changing the umask.
Unless the
\fIumask_override\fR
flag is set, the actual umask will be the union of the
user's umask and the value of the
\fIumask\fR
setting, which defaults to @sudo_umask@.
This guarantees that
\fBsudo\fR
never lowers the umask when running a command.
.sp
If
\fIumask\fR
is explicitly set in
\fIsudoers\fR,
it will override any umask setting in PAM or login.conf.
If
\fIumask\fR
is not set in
\fIsudoers\fR,
the umask specified by PAM or login.conf will take precedence.
The umask setting in PAM is not used for
\fBsudoedit\fR,
which does not create a new PAM session.
.PP
\fBStrings\fR:
.TP 18n
apparmor_profile
The default AppArmor profile to transition into when executing the
command.
The default
\fIapparmor_profile\fR
can be overridden for individual
\fIsudoers\fR
entries by specifying the
\fRAPPARMOR_PROFILE\fR
option.
This option is only available when sudo is built with AppArmor
support.
.TP 18n
authfail_message
Message that is displayed after a user fails to authenticate.
The message may include the
\(oq%d\(cq
escape which will expand to the number of failed password attempts.
If set, it overrides the default message,
\(lq%d incorrect password attempt(s)\(rq.
.TP 18n
badpass_message
Message that is displayed if a user enters an incorrect password.
The default is
\(lq@badpass_message@\(rq
unless insults are enabled.
.TP 18n
editor
A colon
(\(oq:\&\(cq)
separated list of editor path names used by
\fBsudoedit\fR
and
\fBvisudo\fR.
For
\fBsudoedit\fR,
this list is used to find an editor when none of the
\fRSUDO_EDITOR\fR,
\fRVISUAL\fR
or
\fREDITOR\fR
environment variables are set to an editor that exists and is executable.
For
\fBvisudo\fR,
it is used as a white list of allowed editors;
\fBvisudo\fR
will choose the editor that matches the user's
\fRSUDO_EDITOR\fR,
\fRVISUAL\fR
or
\fREDITOR\fR
environment variable if possible, or the first editor in the
list that exists and is executable if not.
Unless invoked as
\fBsudoedit\fR,
\fBsudo\fR
does not preserve the
\fRSUDO_EDITOR\fR,
\fRVISUAL\fR
or
\fREDITOR\fR
environment variables unless they are present in the
\fIenv_keep\fR
list or the
\fIenv_reset\fR
option is disabled.
The default is
\fI@editor@\fR.
.TP 18n
intercept_type
The underlying mechanism used by the
\fIintercept\fR
and
\fIlog_subcmds\fR
options.
It has the following possible values:
.PP
.RS 18n
.PD 0
.TP 8n
dso
Preload a dynamic shared object (shared library) that intercepts the
execve(2),
execl(3),
execle(3),
execlp(3),
execv(3),
execvp(3),
execvpe(3),
and
system(3)
library functions.
A value of
\fIdso\fR
is incompatible with
\fBsudo\fR's
SELinux RBAC support.
.PD
.TP 8n
trace
Use
ptrace(2)
to intercept the
execve(2)
system call.
This is only supported on Linux systems where
seccomp(2)
filtering is enabled.
If the
\fI/proc/sys/kernel/seccomp/actions_avail\fR
file is missing or does not contain a
\(lqtrap\(rq
element, setting
\fIintercept_type\fR
to
\fItrace\fR
will have no effect and
\fIdso\fR
will be used instead.
.PP
The default is to use
\fItrace\fR
if it is supported by the system and
\fIdso\fR
if it is not.
.RE
.TP 18n
iolog_dir
The top-level directory to use when constructing the path name for
the input/output log directory.
Only used if the
\fIlog_input\fR
or
\fIlog_output\fR
options are enabled or when the
\fRLOG_INPUT\fR
or
\fRLOG_OUTPUT\fR
tags are present for a command.
The session sequence number, if any, is stored in the directory.
The default is
\fI@iolog_dir@\fR.
.sp
The following percent
(\(oq%\(cq)
escape sequences are supported:
.PP
.RS 18n
.PD 0
.TP 6n
%{seq}
expanded to a monotonically increasing base-36 sequence number, such as 0100A5,
where every two digits are used to form a new directory, e.g.,
\fI01/00/A5\fR
.PD
.TP 6n
%{user}
expanded to the invoking user's login name
.TP 6n
%{group}
expanded to the name of the invoking user's real group-ID
.TP 6n
%{runas_user}
expanded to the login name of the user the command will
be run as (e.g.,
\fBroot\fR)
.TP 6n
%{runas_group}
expanded to the group name of the user the command will
be run as (e.g.,
\fBwheel\fR)
.TP 6n
%{hostname}
expanded to the local host name without the domain name
.TP 6n
%{command}
expanded to the base name of the command being run
.PP
In addition, any escape sequences supported by the system's
strftime(3)
function will be expanded.
.sp
To include a literal
\(oq%\(cq
character, the string
\(oq%%\(cq
should be used.
.RE
.TP 18n
iolog_file
The path name, relative to
\fIiolog_dir\fR,
in which to store input/output logs when the
\fIlog_input\fR
or
\fIlog_output\fR
options are enabled or when the
\fRLOG_INPUT\fR
or
\fRLOG_OUTPUT\fR
tags are present for a command.
\fIiolog_file\fR
may contain directory components.
The default is
\(oq%{seq}\(cq.
.sp
See the
\fIiolog_dir\fR
option above for a list of supported percent
(\(oq%\(cq)
escape sequences.
.sp
In addition to the escape sequences, path names that end in six or
more
\fIX\fRs
will have the
\fIX\fRs
replaced with a unique combination of digits and letters, similar to the
mktemp(3)
function.
.sp
If the path created by concatenating
\fIiolog_dir\fR
and
\fIiolog_file\fR
already exists, the existing I/O log file will be truncated and
overwritten unless
\fIiolog_file\fR
ends in six or
more
\fIX\fRs.
.TP 18n
iolog_flush
If set,
\fBsudo\fR
will flush I/O log data to disk after each write instead of buffering it.
This makes it possible to view the logs in real-time as the program
is executing but may significantly reduce the effectiveness of I/O
log compression.
This flag is
\fIoff\fR
by default.
.sp
This setting is only supported by version 1.8.20 or higher.
.TP 18n
iolog_group
The group name to look up when setting the group-ID on new I/O log
files and directories.
If
\fIiolog_group\fR
is not set,
the primary group-ID of the user specified by
\fIiolog_user\fR
is used.
If neither
\fIiolog_group\fR
nor
\fIiolog_user\fR
are set, I/O log files and directories are created with group-ID 0.
.sp
This setting is only supported by version 1.8.19 or higher.
.TP 18n
iolog_mode
The file mode to use when creating I/O log files.
Mode bits for read and write permissions for owner, group, or other
are honored, everything else is ignored.
The file permissions will always include the owner read and
write bits, even if they are not present in the specified mode.
When creating I/O log directories, search (execute) bits are added
to match the read and write bits specified by
\fIiolog_mode\fR.
Defaults to 0600 (read and write by user only).
.sp
This setting is only supported by version 1.8.19 or higher.
.TP 18n
iolog_user
The user name to look up when setting the user and group-IDs on new
I/O log files and directories.
If
\fIiolog_group\fR
is set, it will be used instead of the user's primary group-ID.
By default, I/O log files and directories are created with user and
group-ID 0.
.sp
This setting can be useful when the I/O logs are stored on a Network
File System (NFS) share.
Having a dedicated user own the I/O log files means that
\fBsudoers\fR
does not write to the log files as user-ID 0, which is usually
not permitted by NFS.
.sp
This setting is only supported by version 1.8.19 or higher.
.TP 18n
lecture_status_dir
The directory in which
\fBsudo\fR
stores per-user lecture status files.
Once a user has received the lecture, a zero-length file is
created in this directory so that
\fBsudo\fR
will not lecture the user again.
This directory should
\fInot\fR
be cleared when the system reboots.
The default is
\fI@vardir@/lectured\fR.
.if \n(PS \{\
.TP 18n
limitprivs
The default Solaris limit privileges to use when constructing a new
privilege set for a command.
This bounds all privileges of the executing process.
The default limit privileges may be overridden on a per-command basis in
\fIsudoers\fR.
This option is only available if
\fBsudoers\fR
is built on Solaris 10 or higher.
.\}
.TP 18n
log_server_cabundle
The path to a certificate authority bundle file, in PEM format,
to use instead of the system's default certificate authority database
when authenticating the log server.
The default is to use the system's default certificate authority database.
This setting has no effect unless
\fIlog_servers\fR
is set and the remote log server is secured with TLS.
.sp
This setting is only supported by version 1.9.0 or higher.
.TP 18n
log_server_peer_cert
The path to the
\fBsudo\fR
client's certificate file, in PEM format.
This setting is required when the remote log server is secured
with TLS and client certificate validation is enabled.
For
\fBsudo_logsrvd\fR,
client certificate validation is controlled by the
\fItls_checkpeer\fR
option, which defaults to
\fIfalse\fR.
.sp
This setting is only supported by version 1.9.0 or higher.
.TP 18n
log_server_peer_key
The path to the
\fBsudo\fR
client's private key file, in PEM format.
This setting is required when the remote log server is secured
with TLS and client certificate validation is enabled.
For
\fBsudo_logsrvd\fR,
client certificate validation is controlled by the
\fItls_checkpeer\fR
flag, which defaults to
\fIfalse\fR.
.sp
This setting is only supported by version 1.9.0 or higher.
.TP 18n
mailsub
Subject of the mail sent to the
\fImailto\fR
user.
The escape
\(oq%h\(cq
will expand to the host name of the machine.
Default is
\(lq@mailsub@\(rq.
.TP 18n
noexec_file
As of
\fBsudo\fR
version 1.8.1 this option is no longer supported.
The path to the noexec file should now be set in the
sudo.conf(@mansectform@)
file.
.TP 18n
pam_askpass_service
On systems that use PAM for authentication, this is the service
name used when the
\fB\-A\fR
option is specified.
The default value is either
\(oqsudo\(cq
or
\(oq@pam_login_service@\(cq,
depending on whether or not the
\fB\-i\fR
option is also specified.
See the description of
\fIpam_service\fR
for more information.
.sp
This setting is only supported by version 1.9.9 or higher.
.TP 18n
pam_login_service
.br
On systems that use PAM for authentication, this is the service
name used when the
\fB\-i\fR
option is specified.
The default value is
\(oq@pam_login_service@\(cq.
See the description of
\fIpam_service\fR
for more information.
.sp
This setting is only supported by version 1.8.8 or higher.
.TP 18n
pam_service
On systems that use PAM for authentication, the service name
specifies the PAM policy to apply.
This usually corresponds to an entry in the
\fIpam.conf\fR
file or a file in the
\fI/etc/pam.d\fR
directory.
The default value is
\(oqsudo\(cq.
.sp
This setting is only supported by version 1.8.8 or higher.
.TP 18n
passprompt
The default prompt to use when asking for a password; can be overridden via the
\fB\-p\fR
option or the
\fRSUDO_PROMPT\fR
environment variable.
The following percent
(\(oq%\(cq)
escape sequences are supported:
.PP
.RS 18n
.PD 0
.TP 6n
%H
expanded to the local host name including the domain name
(only if the machine's host name is fully qualified or the
\fIfqdn\fR
option is set)
.PD
.TP 6n
%h
expanded to the local host name without the domain name
.TP 6n
%p
expanded to the user whose password is being asked for (respects the
\fIrootpw\fR,
\fItargetpw\fR
and
\fIrunaspw\fR
flags in
\fIsudoers\fR)
.TP 6n
\&%U
expanded to the login name of the user the command will
be run as (defaults to
\fB@runas_default@\fR)
.TP 6n
%u
expanded to the invoking user's login name
.TP 6n
%%
two consecutive
\(oq%\(cq
characters are collapsed into a single
\(oq%\(cq
character
.PP
On systems that use PAM for authentication,
\fIpassprompt\fR
will only be used if the prompt provided by the PAM module matches the string
\(lqPassword: \(rq
or
\(lqusername's Password: \(rq.
This ensures that the
\fIpassprompt\fR
setting does not interfere with challenge-response style authentication.
The
\fIpassprompt_override\fR
flag can be used to change this behavior.
.sp
The default value is
\(oq@passprompt@\(cq.
.RE
.if \n(PS \{\
.TP 18n
privs
The default Solaris privileges to use when constructing a new
privilege set for a command.
This is passed to the executing process via the inherited privilege set,
but is bounded by the limit privileges.
If the
\fIprivs\fR
option is specified but the
\fIlimitprivs\fR
option is not, the limit privileges of the executing process is set to
\fIprivs\fR.
The default privileges may be overridden on a per-command basis in
\fIsudoers\fR.
This option is only available if
\fBsudoers\fR
is built on Solaris 10 or higher.
.\}
.if \n(SL \{\
.TP 18n
role
The default SELinux role to use when constructing a new security
context to run the command.
The default role may be overridden on a per-command basis in the
\fIsudoers\fR
file or via command line options.
This option is only available when
\fBsudo\fR
is built with SELinux support.
.\}
.TP 18n
runas_default
The default user to run commands as if the
\fB\-u\fR
option is not specified on the command line.
This defaults to
\fB@runas_default@\fR.
.TP 18n
sudoers_locale
Locale to use when parsing the sudoers file, logging commands, and
sending email.
Changing the locale may affect how sudoers is interpreted.
Defaults to
\(oqC\(cq.
.TP 18n
timestamp_type
\fBsudoers\fR
uses per-user time stamp files for credential caching.
The
\fItimestamp_type\fR
option can be used to specify the type of time stamp record used.
It has the following possible values:
.PP
.RS 18n
.PD 0
.TP 8n
global
A single time stamp record is used for all of a user's login sessions,
regardless of the terminal or parent process ID.
An additional record is used to serialize password prompts when
\fBsudo\fR
is used multiple times in a pipeline, but this does not affect authentication.
.PD
.TP 8n
ppid
A single time stamp record is used for all processes with the same parent
process ID (usually the shell).
Commands run from the same shell (or other common parent process)
will not require a password for
\fItimestamp_timeout\fR
minutes (@timeout@ by default).
Commands run via
\fBsudo\fR
with a different parent process ID, for example from a shell script,
will be authenticated separately.
.TP 8n
tty
One time stamp record is used for each terminal,
which means that a user's login sessions are authenticated separately.
If no terminal is present, the behavior is the same as
\fIppid\fR.
Commands run from the same terminal will not require a password for
\fItimestamp_timeout\fR
minutes (@timeout@ by default).
.TP 8n
kernel
The time stamp is stored in the kernel as an attribute of the terminal
device.
If no terminal is present, the behavior is the same as
\fIppid\fR.
Negative
\fItimestamp_timeout\fR
values are not supported and positive values are limited to a maximum
of 60 minutes.
This is currently only supported on
OpenBSD.
.PP
The default value is
\fI@timestamp_type@\fR.
.sp
This setting is only supported by version 1.8.21 or higher.
.RE
.TP 18n
timestampdir
The directory in which
\fBsudo\fR
stores its time stamp files.
This directory should be cleared when the system reboots.
The default is
\fI@rundir@/ts\fR.
.TP 18n
timestampowner
The owner of the lecture status directory, time stamp directory and all
files stored therein.
The default is
\fBroot\fR.
.if \n(SL \{\
.TP 18n
type
The default SELinux type to use when constructing a new security
context to run the command.
The default type may be overridden on a per-command basis in the
\fIsudoers\fR
file or via command line options.
This option is only available when
\fBsudo\fR
is built with SELinux support.
.PP
\fBStrings that can be used in a boolean context\fR:
.TP 14n
admin_flag
The
\fIadmin_flag\fR
option specifies the path to a file that is created the first time
a user that is a member of the
\fIsudo\fR
or
\fIadmin\fR
groups runs
\fBsudo\fR.
Only available if
\fBsudo\fR
is configured with the
\fR--enable-admin-flag\fR
option.
The default value is
\fI~/.sudo_as_admin_successful\fR.
.TP 14n
env_file
The
\fIenv_file\fR
option specifies the fully qualified path to a file containing variables
to be set in the environment of the program being run.
Entries in this file should either be of the form
\(oqVARIABLE=value\(cq
or
\(oqexport VARIABLE=value\(cq.
The value may optionally be enclosed in single or double quotes.
Variables in this file are only added if the variable does not already
exist in the environment.
This file is considered to be part of the security policy,
its contents are not subject to other
\fBsudo\fR
environment restrictions such as
\fIenv_keep\fR
and
\fIenv_check\fR.
.TP 14n
exempt_group
Users in this group are exempt from password and PATH requirements.
The group name specified should not include a
\(oq%\(cq
prefix.
This is not set by default.
.TP 14n
fdexec
Determines whether
\fBsudo\fR
will execute a command by its path or by an open file descriptor.
It has the following possible values:
.PP
.RS 14n
.PD 0
.TP 8n
always
Always execute by file descriptor.
.PD
.TP 8n
never
Never execute by file descriptor.
.TP 8n
digest_only
Only execute by file descriptor if the command has an associated digest
in the
\fIsudoers\fR
file.
.PP
The default value is
\fIdigest_only\fR.
This avoids a time of check versus time of use race condition when
the command is located in a directory writable by the invoking user.
.sp
\fIfdexec\fR
will change the first element of the argument vector for scripts
($0 in the shell) due to the way the kernel runs script interpreters.
Instead of being a normal path, it will refer to a file descriptor.
For example,
\fI/dev/fd/4\fR
on Solaris and
\fI/proc/self/fd/4\fR
on Linux.
A workaround is to use the
\fRSUDO_COMMAND\fR
environment variable instead.
.sp
The
\fIfdexec\fR
setting is only used when the command is matched by path name.
It has no effect if the command is matched by the built-in
\fBALL\fR
alias.
.sp
This setting is only supported by version 1.8.20 or higher.
If the operating system does not support the
fexecve(2)
system call, this setting has no effect.
.RE
.TP 14n
group_plugin
A string containing a
\fBsudoers\fR
group plugin with optional arguments.
The string should consist of the plugin
path, either fully-qualified or relative to the
\fI@plugindir@\fR
directory, followed by any configuration arguments the plugin requires.
These arguments (if any) will be passed to the plugin's initialization function.
If arguments are present, the string must be enclosed in double quotes
(\&"").
.sp
On 64-bit systems, if the plugin is present but cannot be loaded,
\fBsudoers\fR
will look for a 64-bit version and, if it exists, load that as a fallback.
The exact rules for this vary by system.
On Solaris, if the plugin is stored in a directory ending in
\(lqlib\(rq,
\fBsudoers\fR
will create a fallback path by appending
\(lq/64\(rq
to the directory name;
\fI@prefix@/lib/group_plugin.so\fR
becomes
\fI@prefix@/lib/64/group_plugin.so\fR.
On Linux, a directory ending in
\(lqlib\(rq
will be transformed to
\(lqlib64\(rq
as the fallback path;
\fI@prefix@/lib/group_plugin.so\fR
becomes
\fI@prefix@/lib64/group_plugin.so\fR.
On all other systems, the fallback path is generated by adding a
\(lq64\(rq
before the file extension;
\fIgroup_plugin.so\fR
becomes
\fIgroup_plugin64.so\fR.
.sp
For more information see
\fIGROUP PROVIDER PLUGINS\fR.
.TP 14n
lecture
This option controls when a short lecture will be printed along with
the password prompt.
It has the following possible values:
.PP
.RS 14n
.PD 0
.TP 8n
always
Always lecture the user.
.PD
.TP 8n
never
Never lecture the user.
.TP 8n
once
Only lecture the user the first time they run
\fBsudo\fR.
.PP
If no value is specified, a value of
\fIonce\fR
is implied.
Negating the option results in a value of
\fInever\fR
being used.
The default value is
\fI@lecture@\fR.
.RE
.TP 14n
lecture_file
Path to a file containing an alternate
\fBsudo\fR
lecture that will be used in place of the standard lecture if the named
file exists.
By default,
\fBsudo\fR
uses a built-in lecture.
.TP 14n
listpw
This option controls when a password will be required when a user runs
\fBsudo\fR
with the
\fB\-l\fR
option.
It has the following possible values:
.PP
.RS 14n
.PD 0
.TP 6n
all
All the user's
\fIsudoers\fR
file entries for the current host must have
the
\fRNOPASSWD\fR
flag set to avoid entering a password.
.PD
.TP 6n
always
The user must always enter a password to use the
\fB\-l\fR
option.
.TP 6n
any
At least one of the user's
\fIsudoers\fR
file entries for the current host
must have the
\fRNOPASSWD\fR
flag set to avoid entering a password.
.TP 6n
never
.br
The user need never enter a password to use the
\fB\-l\fR
option.
.PP
If no value is specified, a value of
\fIany\fR
is implied.
Negating the option results in a value of
\fInever\fR
being used.
The default value is
\fIany\fR.
.RE
.TP 14n
log_format
The event log format.
Supported log formats are:
.PP
.RS 14n
.PD 0
.TP 6n
json
Logs in JSON format.
JSON log entries contain the full user details as well as the execution
environment if the command was allowed.
Due to limitations of the protocol, JSON events sent via
\fIsyslog\fR
may be truncated.
.PD
.TP 6n
sudo
Traditional sudo-style logs, see
\fIEVENT LOGGING\fR
for a description of the log file format.
.PP
This setting affects logs sent via
syslog(3)
as well as the file specified by the
\fIlogfile\fR
setting, if any.
The default value is
\fIsudo\fR.
.RE
.TP 14n
logfile
Path to the
\fBsudo\fR
log file (not the syslog log file).
Setting a path turns on logging to a file;
negating this option turns it off.
By default,
\fBsudo\fR
logs via syslog.
.TP 14n
mailerflags
Flags to use when invoking mailer.
Defaults to
\fB\-t\fR.
.TP 14n
mailerpath
Path to mail program used to send warning mail (negate to prevent
\fBsudo\fR
from sending mail).
Defaults to the path to sendmail found at configure time.
.TP 14n
mailfrom
Address to use for the
\(lqfrom\(rq
address when sending warning and error mail.
The address should be enclosed in double quotes
(\&"")
to protect against
\fBsudo\fR
interpreting the
\(oq@\(cq
sign.
Defaults to the name of the user running
\fBsudo\fR.
.TP 14n
mailto
Address to send warning and error mail to (negate to prevent
\fBsudo\fR
from sending mail).
The address should be enclosed in double quotes
(\&"")
to protect against
\fBsudo\fR
interpreting the
\(oq@\(cq
sign.
Defaults to @mailto@.
.TP 14n
rlimit_as
The maximum size to which the process's address space may grow (in bytes),
if supported by the operating system.
See
\fIResource limits\fR
for more information.
.TP 14n
rlimit_core
The largest size core dump file that may be created (in bytes).
See
\fIResource limits\fR
for more information.
Defaults to 0 (no core dump created).
.TP 14n
rlimit_cpu
The maximum amount of CPU time that the process may use (in seconds).
See
\fIResource limits\fR
for more information.
.TP 14n
rlimit_data
The maximum size of the data segment for the process (in bytes).
See
\fIResource limits\fR
for more information.
.TP 14n
rlimit_fsize
The largest size file that the process may create (in bytes).
See
\fIResource limits\fR
for more information.
.TP 14n
rlimit_locks
The maximum number of locks that the process may establish,
if supported by the operating system.
See
\fIResource limits\fR
for more information.
.TP 14n
rlimit_memlock
The maximum size that the process may lock in memory (in bytes),
if supported by the operating system.
See
\fIResource limits\fR
for more information.
.TP 14n
rlimit_nofile
.br
The maximum number of files that the process may have open.
See
\fIResource limits\fR
for more information.
.TP 14n
rlimit_nproc
The maximum number of processes that the user may run simultaneously.
See
\fIResource limits\fR
for more information.
.TP 14n
rlimit_rss
The maximum size to which the process's resident set size may grow (in bytes).
See
\fIResource limits\fR
for more information.
.TP 14n
rlimit_stack
The maximum size to which the process's stack may grow (in bytes).
See
\fIResource limits\fR
for more information.
.TP 14n
restricted_env_file
The
\fIrestricted_env_file\fR
option specifies the fully qualified path to a file containing variables
to be set in the environment of the program being run.
Entries in this file should either be of the form
\(oqVARIABLE=value\(cq
or
\(oqexport VARIABLE=value\(cq.
The value may optionally be enclosed in single or double quotes.
Variables in this file are only added if the variable does not already
exist in the environment.
Unlike
\fIenv_file\fR,
the file's contents are not trusted and are processed in a manner
similar to that of the invoking user's environment.
If
\fIenv_reset\fR
is enabled, variables in the file will only be added if they are
matched by either the
\fIenv_check\fR
or
\fIenv_keep\fR
list.
If
\fIenv_reset\fR
is disabled, variables in the file are added as long as they
are not matched by the
\fIenv_delete\fR
list.
In either case, the contents of
\fIrestricted_env_file\fR
are processed before the contents of
\fIenv_file\fR.
.TP 14n
runchroot
If set,
\fBsudo\fR
will use this value for the root directory when running a command.
The special value
\(lq*\(rq
will allow the user to specify the root directory via
\fBsudo\fR's
\fB\-R\fR
option.
See the
\fIChroot_Spec\fR
section for more details.
.sp
It is only possible to use
\fIrunchroot\fR
as a command-specific Defaults setting if the command exists with
the same path both inside and outside the chroot jail.
This restriction does not apply to global, host, or user-based
Defaults settings or to a
\fICmnd_Spec\fR
that includes a
\fIChroot_Spec\fR.
.sp
This setting is only supported by version 1.9.3 or higher.
.TP 14n
runcwd
If set,
\fBsudo\fR
will use this value for the working directory when running a command.
The special value
\(lq*\(rq
will allow the user to specify the working directory via
\fBsudo\fR's
\fB\-D\fR
option.
See the
\fIChdir_Spec\fR
section for more details.
.sp
This setting is only supported by version 1.9.3 or higher.
.TP 14n
secure_path
If set,
\fBsudo\fR
will use this value in place of the user's
\fRPATH\fR
environment variable.
This option can be used to reset the
\fRPATH\fR
to a known good value that contains directories for system administrator
commands such as
\fI/usr/sbin\fR.
.sp
Users in the group specified by the
\fIexempt_group\fR
option are not affected by
\fIsecure_path\fR.
This option is @secure_path@ by default.
.TP 14n
syslog
Syslog facility if syslog is being used for logging (negate to
disable syslog logging).
Defaults to @logfac@.
.sp
The following syslog facilities are supported:
\fBauthpriv\fR
(if your
OS supports it),
\fBauth\fR,
\fBdaemon\fR,
\fBuser\fR,
\fBlocal0\fR,
\fBlocal1\fR,
\fBlocal2\fR,
\fBlocal3\fR,
\fBlocal4\fR,
\fBlocal5\fR,
\fBlocal6\fR,
and
\fBlocal7\fR.
.TP 14n
syslog_badpri
.br
Syslog priority to use when the user is not allowed to run a command or
when authentication is unsuccessful.
Defaults to @badpri@.
.sp
The following syslog priorities are supported:
\fBalert\fR,
\fBcrit\fR,
\fBdebug\fR,
\fBemerg\fR,
\fBerr\fR,
\fBinfo\fR,
\fBnotice\fR,
\fBwarning\fR,
and
\fBnone\fR.
Negating the option or setting it to a value of
\fBnone\fR
will disable logging of unsuccessful commands.
.TP 14n
syslog_goodpri
Syslog priority to use when the user is allowed to run a command and
authentication is successful.
Defaults to @goodpri@.
.sp
See
\fIsyslog_badpri\fR
for the list of supported syslog priorities.
Negating the option or setting it to a value of
\fBnone\fR
will disable logging of successful commands.
.TP 14n
verifypw
This option controls when a password will be required when a user runs
\fBsudo\fR
with the
\fB\-v\fR
option.
It has the following possible values:
.PP
.RS 14n
.PD 0
.TP 8n
all
All the user's
\fIsudoers\fR
file entries for the current host must have the
\fRNOPASSWD\fR
flag set to avoid entering a password.
.PD
.TP 8n
always
The user must always enter a password to use the
\fB\-v\fR
option.
.TP 8n
any
At least one of the user's
\fIsudoers\fR
file entries for the current host must have the
\fRNOPASSWD\fR
flag set to avoid entering a password.
.TP 8n
never
The user need never enter a password to use the
\fB\-v\fR
option.
.PP
If no value is specified, a value of
\fIall\fR
is implied.
Negating the option results in a value of
\fInever\fR
being used.
The default value is
\fIall\fR.
.RE
.PP
\fBLists that can be used in a boolean context\fR:
.\}
.TP 18n
env_check
Environment variables to be removed from the user's environment
unless they are considered
\(lqsafe\(rq.
For all variables except
\fRTZ\fR,
\(lqsafe\(rq
means that the variable's value does not contain any
\(oq%\(cq
or
\(oq/\(cq
characters.
This can be used to guard against printf-style format vulnerabilities
in poorly-written programs.
The
\fRTZ\fR
variable is considered unsafe if any of the following are true:
.PP
.RS 18n
.PD 0
.TP 3n
\fB\(bu\fR
It consists of a fully-qualified path name,
optionally prefixed with a colon
(\(oq:\&\(cq),
that does not match the location of the
\fIzoneinfo\fR
directory.
.PD
.TP 3n
\fB\(bu\fR
It contains a
\fI..\fR
path element.
.TP 3n
\fB\(bu\fR
It contains white space or non-printable characters.
.TP 3n
\fB\(bu\fR
It is longer than the value of
\fRPATH_MAX\fR.
.PP
The argument may be a double-quoted, space-separated list or a
single value without double-quotes.
The list can be replaced, added to, deleted from, or disabled by using
the
\(oq=\(cq,
\(oq+=\(cq,
\(oq-=\(cq,
and
\(oq\&!\(cq
operators respectively.
Regardless of whether the
\fIenv_reset\fR
option is enabled or disabled, variables specified by
\fIenv_check\fR
will be preserved in the environment if they pass the aforementioned check.
The global list of environment variables to check is displayed when
\fBsudo\fR
is run by
\fBroot\fR
with the
\fB\-V\fR
option.
.RE
.TP 18n
env_delete
Environment variables to be removed from the user's environment when the
\fIenv_reset\fR
option is not in effect.
The argument may be a double-quoted, space-separated list or a
single value without double-quotes.
The list can be replaced, added to, deleted from, or disabled by using the
\(oq=\(cq,
\(oq+=\(cq,
\(oq-=\(cq,
and
\(oq\&!\(cq
operators respectively.
The global list of environment variables to remove is displayed when
\fBsudo\fR
is run by
\fBroot\fR
with the
\fB\-V\fR
option.
Many operating systems will remove potentially dangerous variables
from the environment of any set-user-ID process (such as
\fBsudo\fR).
.TP 18n
env_keep
Environment variables to be preserved in the user's environment when the
\fIenv_reset\fR
option is in effect.
This allows fine-grained control over the environment
\fBsudo\fR-spawned
processes will receive.
The argument may be a double-quoted, space-separated list or a
single value without double-quotes.
The list can be replaced, added to, deleted from, or disabled by using the
\(oq=\(cq,
\(oq+=\(cq,
\(oq-=\(cq,
and
\(oq\&!\(cq
operators respectively.
The global list of variables to keep
is displayed when
\fBsudo\fR
is run by
\fBroot\fR
with the
\fB\-V\fR
option.
.sp
Preserving the
\fRHOME\fR
environment variable has security implications since many programs use it
when searching for configuration or data files.
Adding
\fRHOME\fR
to
\fIenv_keep\fR
may enable a user to run unrestricted commands via
\fBsudo\fR
and is strongly discouraged.
Users wishing to edit files with
\fBsudo\fR
should run
\fBsudoedit\fR
(or
\fBsudo\fR \fB\-e\fR)
to get their accustomed editor configuration instead of
invoking the editor directly.
.TP 18n
log_servers
A list of one or more servers to use for remote event and I/O log storage,
separated by white space.
Log servers must be running
\fBsudo_logsrvd\fR
or another service that implements the protocol described by
sudo_logsrv.proto(@mansectform@).
.sp
Server addresses should be of the form
\(lqhost[:port][(tls)]\(rq.
The host portion may be a host name, an IPv4 address, or an IPv6 address
in square brackets.
.sp
If the optional
\fItls\fR
flag is present, the connection will be secured
with Transport Layer Security (TLS) version 1.2 or 1.3.
Versions of TLS prior to 1.2 are not supported.
.sp
If a port is specified, it may either be a port number or a well-known
service name as defined by the system service name database.
If no port is specified, port 30343 will be used for plaintext
connections and port 30344 will be used for TLS connections.
.sp
When
\fIlog_servers\fR
is set, event log data will be logged both locally (see the
\fIsyslog\fR
and
\fIlog_file\fR
settings) as well as remotely, but I/O log data will only be logged remotely.
If multiple hosts are specified, they will be attempted in reverse order.
If no log servers are available, the user will not be able to run
a command unless either the
\fIignore_iolog_errors\fR
flag (I/O logging enabled) or the
\fIignore_log_errors\fR
flag (I/O logging disabled) is set.
Likewise, if the connection to the log server is interrupted while
\fBsudo\fR
is running, the command will be terminated unless the
\fIignore_iolog_errors\fR
flag (I/O logging enabled) or the
\fIignore_log_errors\fR
flag (I/O logging disabled) is set.
.sp
This setting is only supported by version 1.9.0 or higher.
.TP 18n
passprompt_regex
A list of POSIX extended regular expressions used to
match password prompts in the terminal output.
As an extension, if the regular expression begins with
\(lq(?i)\(rq,
it will be matched in a case-insensitive manner.
Each regular expression is limited to 1024 characters.
This option is only used when
\fIlog_passwords\fR
has been disabled.
The default value is
\(lq[Pp]assword[: ]*\(rq
.sp
This setting is only supported by version 1.9.10 or higher.
.SH "GROUP PROVIDER PLUGINS"
The
\fBsudoers\fR
plugin supports its own plugin interface to allow non-Unix
group lookups which can query a group source other
than the standard Unix group database.
This can be used to implement support for the
\fInonunix_group\fR
syntax described earlier.
.PP
Group provider plugins are specified via the
\fIgroup_plugin\fR
setting.
The argument to
\fIgroup_plugin\fR
should consist of the plugin path, either fully-qualified or relative to the
\fI@plugindir@\fR
directory, followed by any configuration options the plugin requires.
These options (if specified) will be passed to the plugin's initialization
function.
If options are present, the string must be enclosed in double quotes
(\&"").
.PP
The following group provider plugins are installed by default:
.TP 6n
group_file
The
\fIgroup_file\fR
plugin supports an alternate group file that uses the same syntax as the
\fI/etc/group\fR
file.
The path to the group file should be specified as an option
to the plugin.
For example, if the group file to be used is
\fI/etc/sudo-group\fR:
.nf
.sp
.RS 6n
Defaults group_plugin="group_file.so /etc/sudo-group"
.RE
.fi
.TP 6n
system_group
The
\fIsystem_group\fR
plugin supports group lookups via the standard C library functions
getgrnam(3)
and
getgrid(3).
This plugin can be used in instances where the user belongs to
groups not present in the user's supplemental group vector.
This plugin takes no options:
.nf
.sp
.RS 6n
Defaults group_plugin=system_group.so
.RE
.fi
.PP
The group provider plugin API is described in detail in
sudo_plugin(@mansectform@).
.SH "EVENT LOGGING"
\fBsudoers\fR
can log events in either JSON or
\fIsudo\fR
format,
this section describes the
\fIsudo\fR
log format.
Depending on
\fIsudoers\fR
configuration,
\fBsudoers\fR
can log events via
syslog(3),
to a local log file, or both.
The log format is almost identical in both cases.
Any control characters present in the log data are formatted in octal
with a leading
\(oq#\(cq
character.
For example, a horizontal tab is stored as
\(oq#011\(cq
and an embedded carriage return is stored as
\(oq#015\(cq.
In addition, space characters in the command path are stored as
\(oq#040\(cq.
Command line arguments that contain spaces are enclosed in single quotes
('').
This makes it possible to distinguish multiple command line arguments
from a single argument that contains spaces.
Literal single quotes and backslash characters
(\(oq\e\(cq)
in command line arguments are escaped with a backslash.
.SS "Accepted command log entries"
Commands that sudo runs are logged using the following format (split
into multiple lines for readability):
.nf
.sp
.RS 4n
date hostname progname: username : TTY=ttyname ; CHROOT=chroot ; \e
    PWD=cwd ; USER=runasuser ; GROUP=runasgroup ; TSID=logid ; \e
    ENV=env_vars COMMAND=command
.RE
.fi
.PP
Where the fields are as follows:
.TP 14n
date
The date the command was run.
Typically, this is in the format
\(lqMMM, DD, HH:MM:SS\(rq.
If logging via
syslog(3),
the actual date format is controlled by the syslog daemon.
If logging to a file and the
\fIlog_year\fR
option is enabled,
the date will also include the year.
.TP 14n
hostname
The name of the host
\fBsudo\fR
was run on.
This field is only present when logging via
syslog(3).
.TP 14n
progname
The name of the program, usually
\fIsudo\fR
or
\fIsudoedit\fR.
This field is only present when logging via
syslog(3).
.TP 14n
username
The login name of the user who ran
\fBsudo\fR.
.TP 14n
ttyname
The short name of the terminal (e.g.,
\(lqconsole\(rq,
\(lqtty01\(rq,
or
\(lqpts/0\(rq)
\fBsudo\fR
was run on, or
\(lqunknown\(rq
if there was no terminal present.
.TP 14n
chroot
The root directory that the command was run in, if one was specified.
.TP 14n
cwd
The current working directory that
\fBsudo\fR
was run in.
.TP 14n
runasuser
The user the command was run as.
.TP 14n
runasgroup
The group the command was run as if one was specified on the command line.
.TP 14n
logid
An I/O log identifier that can be used to replay the command's output.
This is only present when the
\fIlog_input\fR
or
\fIlog_output\fR
option is enabled.
.TP 14n
env_vars
A list of environment variables specified on the command line,
if specified.
.TP 14n
command
The actual command that was executed, including any command line arguments.
.PP
Messages are logged using the locale specified by
\fIsudoers_locale\fR,
which defaults to the
\(oqC\(cq
locale.
.SS "Denied command log entries"
If the user is not allowed to run the command, the reason for the denial
will follow the user name.
Possible reasons include:
.TP 3n
user NOT in sudoers
The user is not listed in the
\fIsudoers\fR
file.
.TP 3n
user NOT authorized on host
The user is listed in the
\fIsudoers\fR
file but is not allowed to run commands on the host.
.TP 3n
command not allowed
The user is listed in the
\fIsudoers\fR
file for the host but they are not allowed to run the specified command.
.TP 3n
3 incorrect password attempts
The user failed to enter their password after 3 tries.
The actual number of tries will vary based on the number of
failed attempts and the value of the
\fIpasswd_tries\fR
option.
.TP 3n
a password is required
The
\fB\-n\fR
option was specified but a password was required.
.TP 3n
sorry, you are not allowed to set the following environment variables
The user specified environment variables on the command line that
were not allowed by
\fIsudoers\fR.
.SS "Error log entries"
If an error occurs,
\fBsudoers\fR
will log a message and, in most cases, send a message to the
administrator via email.
Possible errors include:
.TP 3n
parse error in @sysconfdir@/sudoers near line N
\fBsudoers\fR
encountered an error when parsing the specified file.
In some cases, the actual error may be one line above or below the
line number listed, depending on the type of error.
.TP 3n
problem with defaults entries
The
\fIsudoers\fR
file contains one or more unknown Defaults settings.
This does not prevent
\fBsudo\fR
from running, but the
\fIsudoers\fR
file should be checked using
\fBvisudo\fR.
.TP 3n
timestamp owner (username): \&No such user
The time stamp directory owner, as specified by the
\fItimestampowner\fR
setting, could not be found in the password database.
.TP 3n
unable to open/read @sysconfdir@/sudoers
The
\fIsudoers\fR
file could not be opened for reading.
This can happen when the
\fIsudoers\fR
file is located on a remote file system that maps user-ID 0 to
a different value.
Normally,
\fBsudoers\fR
tries to open the
\fIsudoers\fR
file using group permissions to avoid this problem.
Consider either changing the ownership of
\fI@sysconfdir@/sudoers\fR
or adding an argument like
\(lqsudoers_uid=N\(rq
(where
\(oqN\(cq
is the user-ID that owns the
\fIsudoers\fR
file) to the end of the
\fBsudoers\fR
\fIPlugin\fR
line in the
sudo.conf(@mansectform@)
file.
.TP 3n
unable to open @sysconfdir@/sudoers
The
\fI@sysconfdir@/sudoers\fR
file is missing.
.TP 3n
@sysconfdir@/sudoers is not a regular file
The
\fI@sysconfdir@/sudoers\fR
file exists but is not a regular file or symbolic link.
.TP 3n
@sysconfdir@/sudoers is owned by uid N, should be 0
The
\fIsudoers\fR
file has the wrong owner.
If you wish to change the
\fIsudoers\fR
file owner, add
\(lqsudoers_uid=N\(rq
(where
\(oqN\(cq
is the user-ID that owns the
\fIsudoers\fR
file) to the
\fBsudoers\fR
\fIPlugin\fR
line in the
sudo.conf(@mansectform@)
file.
.TP 3n
@sysconfdir@/sudoers is world writable
The permissions on the
\fIsudoers\fR
file allow all users to write to it.
The
\fIsudoers\fR
file must not be world-writable, the default file mode
is 0440 (readable by owner and group, writable by none).
The default mode may be changed via the
\(lqsudoers_mode\(rq
option to the
\fBsudoers\fR
\fIPlugin\fR
line in the
sudo.conf(@mansectform@)
file.
.TP 3n
@sysconfdir@/sudoers is owned by gid N, should be 1
The
\fIsudoers\fR
file has the wrong group ownership.
If you wish to change the
\fIsudoers\fR
file group ownership, add
\(lqsudoers_gid=N\(rq
(where
\(oqN\(cq
is the group-ID that owns the
\fIsudoers\fR
file) to the
\fBsudoers\fR
\fIPlugin\fR
line in the
sudo.conf(@mansectform@)
file.
.TP 3n
unable to open @rundir@/ts/username
\fBsudoers\fR
was unable to read or create the user's time stamp file.
This can happen when
\fItimestampowner\fR
is set to a user other than
\fBroot\fR
and the mode on
\fI@rundir@\fR
is not searchable by group or other.
The default mode for
\fI@rundir@\fR
is 0711.
.TP 3n
unable to write to @rundir@/ts/username
\fBsudoers\fR
was unable to write to the user's time stamp file.
.TP 3n
@rundir@/ts is owned by uid X, should be Y
The time stamp directory is owned by a user other than
\fItimestampowner\fR.
This can occur when the value of
\fItimestampowner\fR
has been changed.
\fBsudoers\fR
will ignore the time stamp directory until the owner is corrected.
.TP 3n
@rundir@/ts is group writable
The time stamp directory is group-writable; it should be writable only by
\fItimestampowner\fR.
The default mode for the time stamp directory is 0700.
\fBsudoers\fR
will ignore the time stamp directory until the mode is corrected.
.SS "Notes on logging via syslog"
By default,
\fBsudoers\fR
logs messages via
syslog(3).
The
\fIdate\fR,
\fIhostname\fR,
and
\fIprogname\fR
fields are added by the system's
syslog(3)
function, not
\fBsudoers\fR
itself.
As such, they may vary in format on different systems.
.PP
The maximum size of syslog messages varies from system to system.
The
\fIsyslog_maxlen\fR
setting can be used to change the maximum syslog message size
from the default value of 980 bytes.
For more information, see the description of
\fIsyslog_maxlen\fR.
.SS "Notes on logging to a file"
If the
\fIlogfile\fR
option is set,
\fBsudoers\fR
will log to a local file, such as
\fI@log_dir@/sudo\fR.
When logging to a file,
\fBsudoers\fR
uses a format similar to
syslog(3),
with a few important differences:
.TP 5n
1.\&
The
\fIprogname\fR
field is not present.
.TP 5n
2.\&
The
\fIhostname\fR
is only logged if the
\fIlog_host\fR
option is enabled.
.TP 5n
3.\&
The date does not include the year unless the
\fIlog_year\fR
option is enabled.
.TP 5n
4.\&
Lines that are longer than
\fIloglinelen\fR
characters (80 by default) are word-wrapped and continued on the
next line with a four character indent.
This makes entries easier to read for a human being, but makes it
more difficult to use
grep(1)
on the log files.
If the
\fIloglinelen\fR
option is set to 0 (or negated with a
\(oq\&!\(cq),
word wrap will be disabled.
.SH "I/O LOGGING"
When I/O logging is enabled,
\fBsudo\fR
will runs the command in a pseudo-terminal, logging user input
and/or output, depending on which
\fBsudoers\fR
flags are enabled.
There are five distinct types of I/O that can be logged, each with
a corresponding
\fBsudoers\fR
flag.
.TS
l l l.
.PP
\fBType\fR	\fBFlag\fR	\fBDescription\fR
.PP
terminal input	log_ttyin	keystrokes entered by the user
.PP
terminal output	log_ttyout	command output displayed to the screen
.PP
standard input	log_stdin	input from a pipe or a file
.PP
standard output	log_stdout	output to a pipe or a file
.PP
standard error	log_stderr	output to a pipe or a file
.TE
.PP
In addition to flags described the above, the
\fIlog_input\fR
flag and
\fRLOG_INPUT\fR
command tag set both
\fIlog_ttyin\fR
and
\fIlog_stdin\fR.
The
\fIlog_output\fR
flag and
\fRLOG_OUTPUT\fR
command tag set
\fIlog_ttyout\fR,
\fIlog_stdout\fR,
and
\fIlog_stderr\fR.
.PP
To capture terminal input and output,
\fBsudo\fR
run the command in a pseudo-terminal, logging the input and
output before passing it on to the user.
To capture the standard input, standard output or standard error,
\fBsudo\fR
uses a pipe to interpose itself between the input or output stream,
logging the I/O before passing it to the other end of the pipe.
.PP
I/O can be logged either to the local machine or to a remote log server.
For local logs, I/O is logged to the directory specified by the
\fIiolog_dir\fR
option
(\fI@iolog_dir@\fR
by default)
using a unique session ID that is included in the
\fBsudo\fR
log line, prefixed with
\(oqTSID=\(cq.
The
\fIiolog_file\fR
option may be used to control the format of the session ID.
For remote logs, the
\fIlog_servers\fR
setting is used to specify one or more log servers running
\fBsudo_logsrvd\fR
or another server that implements the protocol described by
sudo_logsrv.proto(@mansectform@).
.SS "I/O logging pitfals"
When logging standard input, anything sent to the standard input
will be consumed, regardless of whether or not the command run via
\fBsudo\fR
is actively reading the standard input.
This may have unexpected results when using
\fBsudo\fR
in a shell script that expects to process the standard input.
For example, given the following shell script:
.nf
.sp
.RS 4n
#!/bin/sh
sudo echo testing
echo done
.RE
.fi
.PP
It will behave as expected when the script is passed to the shell as a
an argument:
.nf
.sp
.RS 4n
$ sh test.sh
testing
done
.RE
.fi
.PP
However, if the script is passed to the shell on the standard input, the
\(oqsudo echo testing\(cq
command will consume the rest of the script.
This means that the
\(oqecho done\(cq
statement is never executed.
.nf
.sp
.RS 4n
$ sh -s < test.sh
testing
.RE
.fi
.PP
There are several ways to work around this problem:
.TP 5n
1.\&
Redirect the standard input from
\fI/dev/null\fR
when running a command via
\fBsudo\fR
that does not need to read the standard input.
.nf
.sp
.RS 9n
sudo echo testing < /dev/null
.RE
.fi
.TP 5n
2.\&
Pass the script to the shell by path name instead of via the standard input.
.nf
.sp
.RS 9n
sh test.sh
.RE
.fi
.TP 5n
3.\&
Disable logging the standard input for commands that do not need
to read the standard input.
.nf
.sp
.RS 9n
Defaults!/bin/echo !log_stdin
.RE
.fi
.PP
Depending on the command, it may not be desirable to log the
standard input or standard output.
For example, I/O logging of commands that send or receive large
amount of data via the standard output or standard input such as
rsync(1)
and
tar(1)
could fill up the log file system with superfluous data.
It is possible to disable logging of the standard input and standard
output for such commands as follows:
.nf
.sp
.RS 4n
Cmnd_Alias COPY_CMDS = /usr/bin/tar, /usr/bin/cpio, /usr/bin/rsync

# Log input and output but omit stdin and stdout when copying files.
Defaults log_input, log_output
Defaults!COPY_CMDS !log_stdin, !log_stdout
.RE
.fi
.PP
However, be aware that using the
\fIlog_input\fR
flag or the
\fRLOG_INPUT\fR
command tag will also enable
\fIlog_stdin\fR.
Likewise, the
\fIlog_ouput\fR
flag or the
\fRLOG_OUTPUT\fR
command tag will enable
\fIlog_stdout\fR
and
\fIlog_stderr.\fR
Careful ordering of rules may be necessary to achieve the results
that you expect.
.SS "I/O log format"
For both local and remote I/O logs, each log is stored in a separate
directory that contains the following files:
.TP 10n
\fIlog\fR
A text file containing information about the command.
The first line consists of the following colon-delimited fields:
the time the command was run, the name of the user
who ran
\fBsudo\fR,
the name of the target user, the name of the target group (optional),
the terminal that
\fBsudo\fR
was run from, and the number of lines and columns of the terminal.
The second and third lines contain the working directory the command
was run from and the path name of the command itself (with arguments
if present).
.TP 10n
\fIlog.json\fR
A JSON-formatted file containing information about the command.
This is similar to the
\fIlog\fR
file but contains additional information and is easily extensible.
The
\fIlog.json\fR
file will be used by
sudoreplay(@mansectsu@)
in preference to the
\fIlog\fR
file if it exists.
The file may contain the following elements:
.PP
.RS 10n
.PD 0
.TP 6n
timestamp
A JSON object containing time the command was run.
It consists of two values,
\fIseconds\fR
and
\fInanoseconds\fR.
.PD
.TP 6n
columns
The number of columns of the terminal the command ran on, or zero
if no terminal was present.
.TP 6n
command
The fully-qualified path of the command that was run.
.TP 6n
lines
.br
The number of lines of the terminal the command ran on, or zero
if no terminal was present.
.TP 6n
runargv
A JSON array representing the command's argument vector as passed to the
execve(2)
system call.
.TP 6n
runenv
A JSON array representing the command's environment as passed to the
execve(2)
system call.
.TP 6n
rungid
The group ID the command ran as.
This element is only present when the user specifies a group on the
command line.
.TP 6n
rungroup
The name of the group the command ran as.
This element is only present when the user specifies a group on the
command line.
.TP 6n
runuid
The user ID the command ran as.
.TP 6n
runuser
The name of the user the command ran as.
.TP 6n
submitcwd
The current working directory at the time
\fBsudo\fR
was run.
.TP 6n
submithost
The name of the host the command was run on.
.TP 6n
submituser
The name of the user who ran the command via
\fBsudo\fR.
.TP 6n
ttyname
The path name of the terminal the user invoked
\fBsudo\fR
from.
If the command was run in a pseudo-terminal,
\fIttyname\fR
will be different from the terminal the command actually ran in.
.PD 0
.PP
.RE
.PD
.TP 10n
\fItiming\fR
Timing information used to replay the session.
Each line consists of the I/O log entry type and amount of time
since the last entry, followed by type-specific data.
The I/O log entry types and their corresponding type-specific data are:
.PP
.RS 10n
.PD 0
.TP 6n
0
standard input, number of bytes in the entry
.TP 6n
1
standard output, number of bytes in the entry
.TP 6n
2
standard error, number of bytes in the entry
.TP 6n
3
terminal input, number of bytes in the entry
.TP 6n
4
terminal output, number of bytes in the entry
.TP 6n
5
window change, new number lines and columns
.TP 6n
6
bug compatibility for
\fBsudo\fR
1.8.7 terminal output
.TP 6n
7
command suspend or resume, signal received
.PP
.RE
.PD
.TP 10n
\fIttyin\fR
Raw input from the user's terminal, exactly as it was received.
This file is only present if the
\fIlog_input\fR
or
\fIlog_ttyin\fR
flags are set and
\fBsudo\fR
was run from a terminal.
No post-processing is performed.
For manual viewing, you may wish to convert carriage return characters
in the log to line feeds.
For example:
\(oqgunzip -c ttyin | tr \&"\er\&" \&"\en\&"\(cq
.TP 10n
\fIstdin\fR
The standard input when no terminal is present, or input redirected from
a pipe or file.
This file is only present if the
\fIlog_input\fR
or
\fIlog_stdin\fR
flags are set and the standard input is not connected to a terminal.
.TP 10n
\fIttyout\fR
Output from the pseudo-terminal (what the command writes to the screen).
Terminal-specific post-processing is performed before the data is logged.
This means that, for example, line feeds are usually converted to
line feed/carriage return pairs and tabs may be expanded to spaces.
This file is only present if the
\fIlog_output\fR
or
\fIlog_ttyout\fR
flags are set and
\fBsudo\fR
was run from a terminal.
.TP 10n
\fIstdout\fR
The standard output when no terminal is present, or output redirected to
a pipe or file.
This file is only present if the
\fIlog_output\fR
or
\fIlog_stdout\fR
flags are set and the standard output is not connected to a terminal.
.TP 10n
\fIstderr\fR
The standard error when no terminal is present, or output redirected to
a pipe or file.
This file is only present if the
\fIlog_output\fR
or
\fIlog_stderr\fR
flags are set and the standard error is not connected to a terminal.
.PP
All files other than
\fIlog\fR
are compressed in gzip format unless the
\fIcompress_io\fR
flag has been disabled.
Due to buffering, it is not normally possible to display the I/O logs in
real-time as the program is executing.
The I/O log data will not be complete until the program run by
\fBsudo\fR
has exited or has been terminated by a signal.
The
\fIiolog_flush\fR
flag can be used to disable buffering, in which case I/O log data
is written to disk as soon as it is available.
The output portion of an I/O log file can be viewed with the
sudoreplay(@mansectsu@)
utility, which can also be used to list or search the available logs.
.PP
User input may contain sensitive information such as passwords (even
if they are not echoed to the screen), which will be stored in the
log file unencrypted.
In most cases, logging the command output via
\fIlog_output\fR
or
\fRLOG_OUTPUT\fR
is all that is required.
When logging input, consider disabling the
\fIlog_passwords\fR
flag.
.PP
Since each session's I/O logs are stored in a separate directory,
traditional log rotation utilities cannot be used to limit the
number of I/O logs.
The simplest way to limit the number of I/O is by setting the
\fImaxseq\fR
option to the maximum number of logs you wish to store.
Once the I/O log sequence number reaches
\fImaxseq\fR,
it will be reset to zero and
\fBsudoers\fR
will truncate and re-use any existing I/O logs.
.SH "FILES"
.TP 26n
\fI@sysconfdir@/sudo.conf\fR
Sudo front-end configuration
.TP 26n
\fI@sysconfdir@/sudoers\fR
List of who can run what
.TP 26n
\fI/etc/group\fR
Local groups file
.TP 26n
\fI/etc/netgroup\fR
List of network groups
.TP 26n
\fI@iolog_dir@\fR
I/O log files
.TP 26n
\fI@rundir@/ts\fR
Directory containing time stamps for the
\fBsudoers\fR
security policy
.TP 26n
\fI@vardir@/lectured\fR
Directory containing lecture status files for the
\fBsudoers\fR
security policy
.TP 26n
\fI/etc/environment\fR
Initial environment for
\fB\-i\fR
mode on AIX and Linux systems
.SH "EXAMPLES"
Below are example
\fIsudoers\fR
file entries.
Admittedly, some of these are a bit contrived.
First, we allow a few environment variables to pass and then define our
\fIaliases\fR:
.nf
.sp
.RS 0n
# Run X applications through sudo; HOME is used to find the
# .Xauthority file.  Other programs use HOME to locate configuration
# files and this may lead to privilege escalation!
Defaults env_keep += "DISPLAY HOME"

# User alias specification
User_Alias	FULLTIMERS = millert, mikef, dowdy
User_Alias	PARTTIMERS = bostley, jwfox, crawl
User_Alias	WEBADMIN = will, wendy, wim

# Runas alias specification
Runas_Alias	OP = root, operator
Runas_Alias	DB = oracle, sybase
Runas_Alias	ADMINGRP = adm, oper

# Host alias specification
Host_Alias	SPARC = bigtime, eclipse, moet, anchor :\e
		SGI = grolsch, dandelion, black :\e
		ALPHA = widget, thalamus, foobar :\e
		HPPA = boa, nag, python
Host_Alias	CUNETS = 128.138.0.0/255.255.0.0
Host_Alias	CSNETS = 128.138.243.0, 128.138.204.0/24, 128.138.242.0
Host_Alias	SERVERS = primary, mail, www, ns
Host_Alias	CDROM = orion, perseus, hercules

# Cmnd alias specification
Cmnd_Alias	DUMPS = /usr/bin/mt, /usr/sbin/dump, /usr/sbin/rdump,\e
			/usr/sbin/restore, /usr/sbin/rrestore,\e
			sha224:0GomF8mNN3wlDt1HD9XldjJ3SNgpFdbjO1+NsQ== \e
			/home/operator/bin/start_backups
Cmnd_Alias	KILL = /usr/bin/kill
Cmnd_Alias	PRINTING = /usr/sbin/lpc, /usr/bin/lprm
Cmnd_Alias	SHUTDOWN = /usr/sbin/shutdown
Cmnd_Alias	HALT = /usr/sbin/halt
Cmnd_Alias	REBOOT = /usr/sbin/reboot
Cmnd_Alias	SHELLS = /usr/bin/sh, /usr/bin/csh, /usr/bin/ksh,\e
			 /usr/local/bin/tcsh, /usr/bin/rsh,\e
			 /usr/local/bin/zsh
Cmnd_Alias	SU = /usr/bin/su
Cmnd_Alias	PAGERS = /usr/bin/more, /usr/bin/pg, /usr/bin/less
.RE
.fi
.PP
Here we override some of the compiled in default values.
We want
\fBsudo\fR
to log via
syslog(3)
using the
\fIauth\fR
facility in all cases and for commands to be run with
the target user's home directory as the working directory.
We don't want to subject the full time staff to the
\fBsudo\fR
lecture and we want to allow them to run commands in a
chroot(2)
\(lqsandbox\(rq
via the
\fB\-R\fR
option.
User
\fBmillert\fR
need not provide a password and we don't want to reset the
\fRLOGNAME\fR
or
\fRUSER\fR
environment variables when running commands as
\fBroot\fR.
Additionally, on the machines in the
\fRSERVERS\fR
\fIHost_Alias\fR,
we keep an additional local log file and make sure we log the year
in each log line since the log entries will be kept around for several years.
Lastly, we disable shell escapes for the commands in the PAGERS
\fICmnd_Alias\fR
(\fI/usr/bin/more\fR,
\fI/usr/bin/pg\fR
and
\fI/usr/bin/less\fR)
\&.
This will not effectively constrain users with
\fBsudo\fR
\fBALL\fR
privileges.
.nf
.sp
.RS 0n
# Override built-in defaults
Defaults		syslog=auth,runcwd=~
Defaults>root		!set_logname
Defaults:FULLTIMERS	!lecture,runchroot=*
Defaults:millert	!authenticate
Defaults@SERVERS	log_year, logfile=@log_dir@/sudo.log
Defaults!PAGERS		noexec
.RE
.fi
.PP
The
\fIUser specification\fR
is the part that actually determines who may run what.
.nf
.sp
.RS 0n
root		ALL = (ALL) ALL
%wheel		ALL = (ALL) ALL
.RE
.fi
.PP
We let
\fBroot\fR
and any user in group
\fBwheel\fR
run any command on any host as any user.
.nf
.sp
.RS 0n
FULLTIMERS	ALL = NOPASSWD: ALL
.RE
.fi
.PP
Full time sysadmins
(\fBmillert\fR,
\fBmikef\fR,
and
\fBdowdy\fR)
may run any command on any host without authenticating themselves.
.nf
.sp
.RS 0n
PARTTIMERS	ALL = ALL
.RE
.fi
.PP
Part time sysadmins
\fBbostley\fR,
\fBjwfox\fR,
and
\fBcrawl\fR)
may run any command on any host but they must authenticate themselves
first (since the entry lacks the
\fRNOPASSWD\fR
tag).
.nf
.sp
.RS 0n
jack		CSNETS = ALL
.RE
.fi
.PP
The user
\fBjack\fR
may run any command on the machines in the
\fRCSNETS\fR
alias (the networks 128.138.243.0, 128.138.204.0, and 128.138.242.0).
Of those networks, only 128.138.204.0 has an explicit netmask (in
CIDR notation) indicating it is a class C network.
For the other networks in
\fRCSNETS\fR,
the local machine's netmask will be used during matching.
.nf
.sp
.RS 0n
lisa		CUNETS = ALL
.RE
.fi
.PP
The user
\fBlisa\fR
may run any command on any host in the
\fRCUNETS\fR
alias (the class B network 128.138.0.0).
.nf
.sp
.RS 0n
operator	ALL = DUMPS, KILL, SHUTDOWN, HALT, REBOOT, PRINTING,\e
		sudoedit /etc/printcap, /usr/oper/bin/
.RE
.fi
.PP
The
\fBoperator\fR
user may run commands limited to simple maintenance.
Here, those are commands related to backups, killing processes, the
printing system, shutting down the system, and any commands in the
directory
\fI/usr/oper/bin/\fR.
One command in the
\fRDUMPS\fR
Cmnd_Alias includes a sha224 digest,
\fI/home/operator/bin/start_backups\fR.
This is because the directory containing the script is writable by the
operator user.
If the script is modified (resulting in a digest mismatch) it will no longer
be possible to run it via
\fBsudo\fR.
.nf
.sp
.RS 0n
joe		ALL = /usr/bin/su operator
.RE
.fi
.PP
The user
\fBjoe\fR
may only
su(1)
to operator.
.nf
.sp
.RS 0n
pete		HPPA = /usr/bin/passwd [A-Za-z]*, !/usr/bin/passwd *root*

%opers		ALL = (: ADMINGRP) /usr/sbin/
.RE
.fi
.PP
Users in the
\fBopers\fR
group may run commands in
\fI/usr/sbin/\fR
as themselves
with any group in the
\fRADMINGRP\fR
\fIRunas_Alias\fR
(the
\fBadm\fR
and
\fBoper\fR
groups).
.PP
The user
\fBpete\fR
is allowed to change anyone's password except for
\fBroot\fR
on the
\fRHPPA\fR
machines.
Because command line arguments are matched as a single,
concatenated string, the
\(oq*\(cq
wildcard will match
\fImultiple\fR
words.
This example assumes that
passwd(1)
does not take multiple user names on the command line.
On systems with GNU
getopt(3),
options to
passwd(1)
may be specified after the user argument.
As a result, this rule will also allow:
.nf
.sp
.RS 4n
passwd username --expire
.RE
.fi
.PP
which may not be desirable.
.nf
.sp
.RS 0n
bob		SPARC = (OP) ALL : SGI = (OP) ALL
.RE
.fi
.PP
The user
\fBbob\fR
may run anything on the
\fRSPARC\fR
and
\fRSGI\fR
machines as any user listed in the
\fROP\fR
\fIRunas_Alias\fR
(\fBroot\fR
and
\fBoperator\fR.)
.nf
.sp
.RS 0n
jim		+biglab = ALL
.RE
.fi
.PP
The user
\fBjim\fR
may run any command on machines in the
\fIbiglab\fR
netgroup.
\fBsudo\fR
knows that
\(lqbiglab\(rq
is a netgroup due to the
\(oq+\(cq
prefix.
.nf
.sp
.RS 0n
+secretaries	ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser
.RE
.fi
.PP
Users in the
\fBsecretaries\fR
netgroup need to help manage the printers as well as add and remove users,
so they are allowed to run those commands on all machines.
.nf
.sp
.RS 0n
fred		ALL = (DB) NOPASSWD: ALL
.RE
.fi
.PP
The user
\fBfred\fR
can run commands as any user in the
\fRDB\fR
\fIRunas_Alias\fR
(\fBoracle\fR
or
\fBsybase\fR)
without giving a password.
.nf
.sp
.RS 0n
john		ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root*
.RE
.fi
.PP
On the
\fRALPHA\fR
machines, user
\fBjohn\fR
may su to anyone except
\fBroot\fR
but he is not allowed to specify any options to the
su(1)
command.
.nf
.sp
.RS 0n
jen		ALL, !SERVERS = ALL
.RE
.fi
.PP
The user
\fBjen\fR
may run any command on any machine except for those in the
\fRSERVERS\fR
\fIHost_Alias\fR
(primary, mail, www, and ns).
.nf
.sp
.RS 0n
jill		SERVERS = /usr/bin/, !SU, !SHELLS
.RE
.fi
.PP
For any machine in the
\fRSERVERS\fR
\fIHost_Alias\fR,
\fBjill\fR
may run
any commands in the directory
\fI/usr/bin/\fR
except for those commands
belonging to the
\fRSU\fR
and
\fRSHELLS\fR
\fICmnd_Aliases\fR.
While not specifically mentioned in the rule, the commands in the
\fRPAGERS\fR
\fICmnd_Alias\fR
all reside in
\fI/usr/bin\fR
and have the
\fInoexec\fR
option set.
.nf
.sp
.RS 0n
steve		CSNETS = (operator) /usr/local/op_commands/
.RE
.fi
.PP
The user
\fBsteve\fR
may run any command in the directory /usr/local/op_commands/
but only as user operator.
.nf
.sp
.RS 0n
matt		valkyrie = KILL
.RE
.fi
.PP
On his personal workstation, valkyrie,
\fBmatt\fR
needs to be able to kill hung processes.
.nf
.sp
.RS 0n
WEBADMIN	www = (www) ALL, (root) /usr/bin/su www
.RE
.fi
.PP
On the host www, any user in the
\fRWEBADMIN\fR
\fIUser_Alias\fR
(will, wendy, and wim), may run any command as user www (which owns the
web pages) or simply
su(1)
to www.
.nf
.sp
.RS 0n
ALL		CDROM = NOPASSWD: /sbin/umount /CDROM,\e
		/sbin/mount -o nosuid\e,nodev /dev/cd0a /CDROM
.RE
.fi
.PP
Any user may mount or unmount a CD-ROM on the machines in the CDROM
\fIHost_Alias\fR
(orion, perseus, hercules) without entering a password.
This is a bit tedious for users to type, so it is a prime candidate
for encapsulating in a shell script.
.SH "SECURITY NOTES"
.SS "Limitations of the \(oq!\&\(cq operator"
It is generally not effective to
\(lqsubtract\(rq
commands from
\fBALL\fR
using the
\(oq!\&\(cq
operator.
A user can trivially circumvent this by copying the desired command
to a different name and then executing that.
For example:
.nf
.sp
.RS 0n
bill	ALL = ALL, !SU, !SHELLS
.RE
.fi
.PP
Doesn't really prevent
\fBbill\fR
from running the commands listed in
\fRSU\fR
or
\fRSHELLS\fR
since he can simply copy those commands to a different name, or use
a shell escape from an editor or other program.
Therefore, these kind of restrictions should be considered
advisory at best (and reinforced by policy).
.PP
In general, if a user has sudo
\fBALL\fR
there is nothing to prevent them from creating their own program that gives
them a
\fBroot\fR
shell (or making their own copy of a shell) regardless of any
\(oq!\&\(cq
elements in the user specification.
.SS "Security implications of \fIfast_glob\fR"
If the
\fIfast_glob\fR
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
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.
.PP
For example, given the following
\fIsudoers\fR
file entry:
.nf
.sp
.RS 0n
john	ALL = /usr/bin/passwd [a-zA-Z0-9]*, /usr/bin/chsh [a-zA-Z0-9]*,\e
              /usr/bin/chfn [a-zA-Z0-9]*, !/usr/bin/* root
.RE
.fi
.PP
User
\fBjohn\fR
can still run
\(oq/usr/bin/passwd root\(cq
if
\fIfast_glob\fR
is enabled by changing to
\fI/usr/bin\fR
and running
\(oq./passwd root\(cq
instead.
.PP
Another potential issue is that when
\fBsudo\fR
executes the command, it must use the command or path specified by
the user instead of a path listed in the
\fIsudoers\fR
file.
This may lead to a time of check versus time of use race condition.
.SS "Wildcards in command arguments"
Command line arguments are matched as a single, concatenated string.
This mean a wildcard character such as
\(oq\&?\(cq
or
\(oq*\(cq
will match across word boundaries, which may be unexpected.
For example, while a sudoers entry like:
.nf
.sp
.RS 4n
%operator ALL = /bin/cat @log_dir@/messages*
.RE
.fi
.PP
will allow command like:
.nf
.sp
.RS 4n
$ sudo cat @log_dir@/messages.1
.RE
.fi
.PP
It will also allow:
.nf
.sp
.RS 4n
$ sudo cat @log_dir@/messages /etc/shadow
.RE
.fi
.PP
which is probably not what was intended.
A safer alternative is to use a regular expression for matching
command line arguments.
The above example can be rewritten as a regular expression:
.nf
.sp
.RS 4n
%operator ALL = /bin/cat ^@log_dir@/messages[^[:space:]]*$
.RE
.fi
.PP
The regular expression will only match a single file with a
name that begins with
\fI@log_dir@/messages\fR
and does not include any white space in the name.
It is often better to do command line processing outside of the
\fIsudoers\fR
file in a scripting language for anything non-trivial.
.SS "Regular expressions in command names"
Using a regular expression to match a command name has the same
security implications as using the
\fIfast_glob\fR
option:
.TP 3n
\fB\(bu\fR
It is not possible to reliably negate commands when the
path name is a regular expression.
.TP 3n
\fB\(bu\fR
When
\fBsudo\fR
executes the command, it must use the command or path specified by
the user instead of a path listed in the
\fIsudoers\fR
file.
This may lead to a time of check versus time of use race condition.
.PP
These issues do not apply to rules where only the command line
options are matched using a regular expression.
.SS "Preventing shell escapes"
Once
\fBsudo\fR
executes a program, that program is free to do whatever
it pleases, including run other programs.
This can be a security issue since it is not uncommon for a program to
allow shell escapes, which lets a user bypass
\fBsudo\fR's
access control and logging.
Common programs that permit shell escapes include shells (obviously),
editors, paginators, mail, and terminal programs.
.PP
There are four basic approaches to this problem:
.TP 11n
restrict
Avoid giving users access to commands that allow the user to run
arbitrary commands.
Many editors have a restricted mode where shell
escapes are disabled, though
\fBsudoedit\fR
is a better solution to
running editors via
\fBsudo\fR.
Due to the large number of programs that
offer shell escapes, restricting users to the set of programs that
do not is often unworkable.
.TP 11n
intercept
On most systems,
\fBsudo\fR's
\fIintercept\fR
functionality can be used to transparently intercept an attempt to
run a new command, allow or deny it based on
\fIsudoers\fR
rules, and log the result.
For example, this can be used to restrict the commands run from
within a privileged shell or editor.
.sp
There are two underlying mechanisms that may be used to implement
\fIintercept\fR
mode:
\fIdso\fR
and
\fItrace\fR.
The
\fIintercept_type\fR
setting can be used to select between them.
.sp
The first mechanism,
\fIdso\fR,
overrides the standard C library functions that are used to execute a
command.
It does this by setting an environment variable (usually
\fRLD_PRELOAD\fR)
to the path of a dynamic shared object, or shared library,
containing custom versions of the
execve(2),
execl(3),
execle(3),
execlp(3),
execv(3),
execvp(3),
execvpe(3),
and
system(3)
library functions that connect back to
\fBsudo\fR
for a policy decision.
Note, however, that this applies only to dynamically-linked
executables.
It is not possible to intercept commands for statically-linked executables
or executables that run under binary emulation this way.
Because most dynamic loaders ignore
\fRLD_PRELOAD\fR
(or the equivalent) when running set-user-ID and set-group-ID programs,
\fBsudoers\fR
will not permit such programs to be run in
\fIintercept\fR
mode by default.
The
\fIdso\fR
mechanism is incompatible with
\fBsudo\fR's
SELinux RBAC support (but see below).
SELinux disables
\fRLD_PRELOAD\fR
by default and interferes with file descriptor inheritance, which
\fBsudo\fR
relies on.
.sp
The second mechanism,
\fItrace\fR,
is available on Linux systems that support
seccomp(2)
filtering.
It uses
ptrace(2)
and
seccomp(2)
to intercept the
execve(2)
system call instead of pre-loading a dynamic shared object.
Both static and dynamic executables are supported and it is compatible with
\fBsudo\fR's
SELinux RBAC mode.
Functions utilizing the
execveat(2)
system call, such as
fexecve(3),
are not currently intercepted.
.sp
The
\fIintercept\fR
feature is known to work on Solaris, *BSD, Linux, macOS, HP-UX 11.x
and AIX 5.3 and above.
It should be supported on most operating systems that support the
\fRLD_PRELOAD\fR
environment variable or an equivalent.
It is not possible to intercept shell built-in commands or restrict
the ability to read or write sensitive files from within a shell.
.sp
To enable intercept mode on a per-command basis, use the
\fRINTERCEPT\fR
tag as documented in the User Specification section above.
Here is that example again:
.nf
.sp
.RS 11n
chuck	research = INTERCEPT: ALL
.RE
.fi
.RS 11n
.sp
This allows user
\fBchuck\fR
to run any command on the machine
\(lqresearch\(rq
in intercept mode.
Any commands run via shell escapes will be validated and logged by
\fBsudo\fR.
If you are unsure whether or not your system is capable of supporting
\fIintercept\fR,
you can always just try it out and check whether or not external
commands run via a shell are logged when
\fIintercept\fR
is enabled.
.sp
There is an inherent race condition between when a command is checked against
\fBsudoers\fR
rules and when it is actually executed.
If a user is allowed to run arbitrary commands, they may be able
to change the
execve(2)
arguments in the program after the
\fBsudoers\fR
policy check has completed but before the new command is executed.
Starting with version 1.9.12, the
\fItrace\fR
method will verify that the command and its arguments have not
changed after
execve(2)
has completed but before execution of the new program has had a chance to run.
This is not the case with the
\fIdso\fR
method.
See the description of the
\fIintercept_verify\fR
setting for more information.
.RE
.TP 11n
log
There are two separate but related ways to log additional commands.
The first is to enable I/O logging using the
\fIlog_output\fR
flag.
This will log the command's output but will not create an event log
entry when the additional command is run.
The second is to enable the
\fIlog_subcmds\fR
flag in
\fIsudoers\fR
which will create an event log entry every time a new command is run.
If I/O logging is also enabled, the log entry will include a time offset
into the I/O log to indicate when the command was run.
This offset can be passed to the
sudoreplay(@mansectsu@)
utility to replay the I/O log at the exact moment when the command was run.
The
\fIlog_subcmds\fR
flag uses the same mechanism as
\fIintercept\fR
(see above) and has the same limitations.
.TP 11n
noexec
\fBsudo\fR's
\fInoexec\fR
functionality can be used to prevent a program run by
\fBsudo\fR
from executing any other programs.
On most systems, it uses the same
\fRLD_PRELOAD\fR
mechanism as
\fIintercept\fR
(see above) and thus the same caveats apply.
The
\fInoexec\fR
functionality
is capable of blocking execution of commands run via the
execve(2),
execl(3),
execle(3),
execlp(3),
exect(3),
execv(3),
execveat(3),
execvP(3),
execvp(3),
execvpe(3),
fexecve(3),
popen(3),
posix_spawn(3),
posix_spawnp(3),
system(3),
and
wordexp(3)
functions.
On Linux, a
seccomp(2)
filter is used to implement
\fInoexec\fR.
On Solaris 10 and higher,
\fInoexec\fR
uses Solaris privileges instead of the
\fRLD_PRELOAD\fR
environment variable.
.sp
To enable
\fInoexec\fR
for a command, use the
\fRNOEXEC\fR
tag as documented in the User Specification section above.
Here is that example again:
.nf
.sp
.RS 11n
aaron	shanty = NOEXEC: /usr/bin/more, /usr/bin/vi
.RE
.fi
.RS 11n
.sp
This allows user
\fBaaron\fR
to run
\fI/usr/bin/more\fR
and
\fI/usr/bin/vi\fR
with
\fInoexec\fR
enabled.
This will prevent those two commands from
executing other commands (such as a shell).
If you are unsure whether or not your system is capable of supporting
\fInoexec\fR
you can always just try it out and check whether shell escapes work when
\fInoexec\fR
is enabled.
.RE
.PP
Restricting shell escapes is not a panacea.
Programs running as
\fBroot\fR
are still capable of many potentially hazardous operations (such
as changing or overwriting files) that could lead to unintended
privilege escalation.
In the specific case of an editor, a safer approach is to give the
user permission to run
\fBsudoedit\fR
(see below).
.SS "Secure editing"
The
\fBsudoers\fR
plugin includes
\fBsudoedit\fR
support which allows users to securely edit files with the editor
of their choice.
As
\fBsudoedit\fR
is a built-in command, it must be specified in the
\fIsudoers\fR
file without a leading path.
However, it may take command line arguments just as a normal command does.
Wildcards used in
\fIsudoedit\fR
command line arguments are expected to be path names, so a forward slash
(\(oq/\(cq)
will not be matched by a wildcard.
.PP
Unlike other
\fBsudo\fR
commands, the editor is run with the permissions of the invoking
user and with the environment unmodified.
More information may be found in the description of the
\fB\-e\fR
option in
sudo(@mansectsu@).
.PP
For example, to allow user operator to edit the
\(lqmessage of the day\(rq
file on any machine:
.nf
.sp
.RS 4n
operator ALL = sudoedit /etc/motd
.RE
.fi
.PP
The operator user then runs
\fBsudoedit\fR
as follows:
.nf
.sp
.RS 4n
$ sudoedit /etc/motd
.RE
.fi
.PP
The editor will run as the operator user, not
\fB@runas_default@\fR,
on a temporary copy of
\fI/etc/motd\fR.
After the file has been edited,
\fI/etc/motd\fR
will be updated with the contents of the temporary copy.
.PP
Users should
\fInever\fR
be granted
\fBsudoedit\fR
permission to edit a file that resides in a directory the user
has write access to, either directly or via a wildcard.
If the user has write access to the directory it is possible to
replace the legitimate file with a link to another file,
allowing the editing of arbitrary files.
To prevent this, starting with version 1.8.16, symbolic links will
not be followed in writable directories and
\fBsudoedit\fR
will refuse to edit a file located in a writable directory
unless the
\fIsudoedit_checkdir\fR
option has been disabled or the invoking user is
\fBroot\fR.
Additionally, in version 1.8.15 and higher,
\fBsudoedit\fR
will refuse to open a symbolic link unless either the
\fIsudoedit_follow\fR
option is enabled or the
\fIsudoedit\fR
command is prefixed with the
\fRFOLLOW\fR
tag in the
\fIsudoers\fR
file.
.SS "Time stamp file checks"
\fBsudoers\fR
will check the ownership of its time stamp directory
(\fI@rundir@/ts\fR
by default)
and ignore the directory's contents if it is not owned by
\fBroot\fR
or if it is writable by a user other than
\fBroot\fR.
Older versions of
\fBsudo\fR
stored time stamp files in
\fI/tmp\fR;
this is no longer recommended as it may be possible for a user
to create the time stamp themselves on systems that allow
unprivileged users to change the ownership of files they create.
.PP
While the time stamp directory
\fIshould\fR
be cleared at reboot time, not all systems contain a
\fI/run\fR
or
\fI/var/run\fR
directory.
To avoid potential problems,
\fBsudoers\fR
will ignore time stamp files that date from before the machine booted
on systems where the boot time is available.
.PP
Some systems with graphical desktop environments allow unprivileged
users to change the system clock.
Since
\fBsudoers\fR
relies on the system clock for time stamp validation, it may be
possible on such systems for a user to run
\fBsudo\fR
for longer than
\fItimestamp_timeout\fR
by setting the clock back.
To combat this,
\fBsudoers\fR
uses a monotonic clock (which never moves backwards) for its time stamps
if the system supports it.
.PP
\fBsudoers\fR
will not honor time stamps set far in the future.
Time stamps with a date greater than current_time + 2 *
\fRTIMEOUT\fR
will be ignored and
\fBsudoers\fR
will log and complain.
.PP
If the
\fItimestamp_type\fR
option is set to
\(lqtty\(rq,
the time stamp record includes the device number of the terminal
the user authenticated with.
This provides per-terminal granularity but time stamp records may still
outlive the user's session.
.PP
Unless the
\fItimestamp_type\fR
option is set to
\(lqglobal\(rq,
the time stamp record also includes the session ID of the process
that last authenticated.
This prevents processes in different terminal sessions from using
the same time stamp record.
On systems where a process's start time can be queried,
the start time of the session leader
is recorded in the time stamp record.
If no terminal is present or the
\fItimestamp_type\fR
option is set to
\(lqppid\(rq,
the start time of the parent process is used instead.
In most cases this will prevent a time stamp record from being re-used
without the user entering a password when logging out and back in again.
.SH "DEBUGGING"
Versions 1.8.4 and higher of the
\fBsudoers\fR
plugin support a flexible debugging framework that can help track
down what the plugin is doing internally if there is a problem.
This can be configured in the
sudo.conf(@mansectform@)
file.
.PP
The
\fBsudoers\fR
plugin uses the same debug flag format as the
\fBsudo\fR
front-end:
\fIsubsystem\fR@\fIpriority\fR.
.PP
The priorities used by
\fBsudoers\fR,
in order of decreasing severity,
are:
\fIcrit\fR, \fIerr\fR, \fIwarn\fR, \fInotice\fR, \fIdiag\fR, \fIinfo\fR, \fItrace\fR,
and
\fIdebug\fR.
Each priority, when specified, also includes all priorities higher
than it.
For example, a priority of
\fInotice\fR
would include debug messages logged at
\fInotice\fR
and higher.
.PP
The following subsystems are used by the
\fBsudoers\fR
plugin:
.TP 10n
\fIalias\fR
\fIUser_Alias\fR,
\fIRunas_Alias\fR,
\fIHost_Alias\fR
and
\fICmnd_Alias\fR
processing
.TP 10n
\fIall\fR
matches every subsystem
.TP 10n
\fIaudit\fR
BSM and Linux audit code
.TP 10n
\fIauth\fR
user authentication
.TP 10n
\fIdefaults\fR
\fIsudoers\fR
file
\fIDefaults\fR
settings
.TP 10n
\fIenv\fR
environment handling
.TP 10n
\fIldap\fR
LDAP-based sudoers
.TP 10n
\fIlogging\fR
logging support
.TP 10n
\fImatch\fR
matching of users, groups, hosts, and netgroups in the
\fIsudoers\fR
file
.TP 10n
\fInetif\fR
network interface handling
.TP 10n
\fInss\fR
network service switch handling in
\fBsudoers\fR
.TP 10n
\fIparser\fR
\fIsudoers\fR
file parsing
.TP 10n
\fIperms\fR
permission setting
.TP 10n
\fIplugin\fR
The equivalent of
\fImain\fR
for the plugin.
.TP 10n
\fIpty\fR
pseudo-terminal related code
.TP 10n
\fIrbtree\fR
redblack tree internals
.TP 10n
\fIsssd\fR
SSSD-based sudoers
.TP 10n
\fIutil\fR
utility functions
.PP
For example:
.nf
.sp
.RS 0n
Debug @sudoers_plugin@ @log_dir@/sudoers_debug match@info,nss@info
.RE
.fi
.PP
For more information, see the
sudo.conf(@mansectform@)
manual.
.SH "SEE ALSO"
ssh(1),
su(1),
fnmatch(3),
glob(3),
mktemp(3),
strftime(3),
sudo.conf(@mansectform@),
sudo_plugin(@mansectform@),
sudoers.ldap(@mansectform@),
sudoers_timestamp(@mansectform@),
sudo(@mansectsu@),
visudo(@mansectsu@)
.SH "AUTHORS"
Many people have worked on
\fBsudo\fR
over the years; this version consists of code written primarily by:
.sp
.RS 6n
Todd C. Miller
.RE
.PP
See the CONTRIBUTORS.md file in the
\fBsudo\fR
distribution (https://www.sudo.ws/about/contributors/) for an
exhaustive list of people who have contributed to
\fBsudo\fR.
.SH "CAVEATS"
The
\fIsudoers\fR
file should
\fBalways\fR
be edited by the
\fBvisudo\fR
utility which locks the file and checks for syntax errors.
If
\fIsudoers\fR
contains syntax errors,
\fBsudo\fR
may refuse to run, which is a serious problem if
\fBsudo\fR
is your only method of obtaining superuser privileges.
Recent versions of
\fBsudoers\fR
will attempt to recover after a syntax error by ignoring the rest of
the line after encountering an error.
Older versions of
\fBsudo\fR
will not run if
\fIsudoers\fR
contains a syntax error.
.PP
When using netgroups of machines (as opposed to users), if you
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
\fIhostname\fR
command or use the
\fIfqdn\fR
option in
\fIsudoers\fR.
.SH "BUGS"
If you believe you have found a bug in
\fBsudo\fR,
you can submit a bug report at https://bugzilla.sudo.ws/
.SH "SUPPORT"
Limited free support is available via the sudo-users mailing list,
see https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or
search the archives.
.SH "DISCLAIMER"
\fBsudo\fR
is provided
\(lqAS IS\(rq
and any express or implied warranties, including, but not limited
to, the implied warranties of merchantability and fitness for a
particular purpose are disclaimed.
See the LICENSE.md file distributed with
\fBsudo\fR
or https://www.sudo.ws/about/license/ for complete details.