diff options
Diffstat (limited to '')
| -rw-r--r-- | docs/sudoers.mdoc.in | 7443 |
1 files changed, 7443 insertions, 0 deletions
diff --git a/docs/sudoers.mdoc.in b/docs/sudoers.mdoc.in new file mode 100644 index 0000000..8ec5c32 --- /dev/null +++ b/docs/sudoers.mdoc.in @@ -0,0 +1,7443 @@ +.\" +.\" SPDX-License-Identifier: ISC +.\" +.\" Copyright (c) 1994-1996, 1998-2005, 2007-2023 +.\" Todd C. Miller <Todd.Miller@sudo.ws> +.\" +.\" Permission to use, copy, modify, and distribute this software for any +.\" purpose with or without fee is hereby granted, provided that the above +.\" copyright notice and this permission notice appear in all copies. +.\" +.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES +.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR +.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN +.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF +.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +.\" +.\" Sponsored in part by the Defense Advanced Research Projects +.\" Agency (DARPA) and Air Force Research Laboratory, Air Force +.\" Materiel Command, USAF, under agreement number F39502-99-1-0512. +.\" +.nr SL @SEMAN@ +.nr AA @AAMAN@ +.nr BA @BAMAN@ +.nr LC @LCMAN@ +.nr PS @PSMAN@ +.Dd December 19, 2023 +.Dt SUDOERS @mansectform@ +.Os Sudo @PACKAGE_VERSION@ +.Sh NAME +.Nm sudoers +.Nd default sudo security policy plugin +.Sh DESCRIPTION +The +.Nm +policy plugin determines a user's +.Nm sudo +privileges. +It is the default +.Nm sudo +policy plugin. +The policy is driven by +the +.Pa @sysconfdir@/sudoers +file or, optionally, in LDAP. +The policy format is described in detail in the +.Sx SUDOERS FILE FORMAT +section. +For information on storing +.Nm +policy information +in LDAP, see +.Xr sudoers.ldap @mansectform@ . +.Ss Configuring sudo.conf for sudoers +.Nm sudo +consults the +.Xr sudo.conf @mansectform@ +file to determine which plugins to load. +If no +.Xr sudo.conf @mansectform@ +file is present, or if it contains no +.Em Plugin +lines, +.Nm +will be used for auditing, policy decisions and I/O logging. +To explicitly configure +.Xr sudo.conf @mansectform@ +to use the +.Nm +plugin, the following configuration can be used. +.Bd -literal -offset 4n +Plugin sudoers_audit @sudoers_plugin@ +Plugin sudoers_policy @sudoers_plugin@ +Plugin sudoers_io @sudoers_plugin@ +.Ed +.Pp +Starting with +.Nm sudo +1.8.5, it is possible to specify optional arguments to the +.Nm +plugin in the +.Xr sudo.conf @mansectform@ +file. +Plugin arguments, if any, should be listed after the path to the plugin +(i.e., after +.Pa @sudoers_plugin@ ) . +The arguments are only effective for the plugin that opens (and parses) the +.Em sudoers +file. +.Pp +For +.Nm sudo +version 1.9.1 and higher, this is the +.Em sudoers_audit +plugin. +For older versions, it is the +.Em sudoers_policy +plugin. +Multiple arguments may be specified, separated by white space. +For example: +.Bd -literal -offset 4n +Plugin sudoers_audit @sudoers_plugin@ sudoers_mode=0400 error_recovery=false +.Ed +.Pp +The following plugin arguments are supported: +.Bl -tag -width 4n +.It error_recovery=bool +The +.Em error_recovery +argument can be used to control whether +.Nm +should attempt to recover from syntax errors in the +.Em sudoers +file. +If set to +.Em true +(the default), +.Nm +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 +.Em false +will disable error recovery. +Prior to version 1.9.3, no error recovery was performed. +.It ignore_perms=bool +The +.Em ignore_perms +argument can be used to disable security checks when loading the +.Em sudoers +file. +If enabled, the +.Em sudoers +file will be loaded regardless of the owner or file mode. +This argument is intended to be used for testing purposes and +should not be enabled on production systems. +.It ldap_conf=pathname +The +.Em ldap_conf +argument can be used to override the default path to the +.Pa ldap.conf +file. +.It ldap_secret=pathname +The +.Em ldap_secret +argument can be used to override the default path to the +.Pa ldap.secret +file. +.It sudoers_file=pathname +The +.Em sudoers_file +argument can be used to override the default path to the +.Em sudoers +file. +.It sudoers_uid=user-ID +The +.Em sudoers_uid +argument can be used to override the default owner of the sudoers file. +It should be specified as a numeric user-ID. +.It sudoers_gid=group-ID +The +.Em sudoers_gid +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). +.It sudoers_mode=mode +The +.Em sudoers_mode +argument can be used to override the default file mode for the sudoers file. +It should be specified as an octal value. +.El +.Pp +For more information on configuring +.Xr sudo.conf @mansectform@ , +refer to its manual. +.Ss User Authentication +The +.Nm +security policy requires that most users authenticate +themselves before they can use +.Nm sudo . +A password is not required +if the invoking user is +.Sy root , +if the target user is the same as the invoking user, or if the +policy has disabled authentication for the user or command. +Unlike +.Xr su 1 , +when +.Nm +requires +authentication, it validates the invoking user's credentials, not +the target user's (or +.Sy @runas_default@ Ns No 's) +credentials. +This can be changed via +the +.Em rootpw , +.Em targetpw +and +.Em runaspw +flags, described later. +.Pp +If a user who is not listed in the policy tries to run a command +via +.Nm sudo , +mail is sent to the proper authorities. +The address +used for such mail is configurable via the +.Em mailto +Defaults entry +(described later) and defaults to +.Em @mailto@ . +.Pp +No mail will be sent if an unauthorized user tries to run +.Nm sudo +with the +.Fl l +or +.Fl v +option unless there is an authentication error and +either the +.Em mail_always +or +.Em mail_badpass +flags are enabled. +This allows users to +determine for themselves whether or not they are allowed to use +.Nm sudo . +By default, all attempts to run +.Nm sudo +(successful or not) +are logged, regardless of whether or not mail is sent. +.Pp +If +.Nm sudo +is run by +.Sy root +and the +.Ev SUDO_USER +environment variable +is set, the +.Nm +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 +.Sy root +shell has been invoked. +It also +allows the +.Fl e +option to remain useful even when invoked via a +sudo-run script or program. +Note, however, that the +.Em sudoers +file lookup is still done for +.Sy root , +not the user specified by +.Ev SUDO_USER . +.Pp +.Nm +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 +.Nm sudo +without a password for a short period of time (@timeout@ minutes +unless overridden by the +.Em timestamp_timeout +option). +By default, +.Nm +uses a separate record for each terminal, which means that +a user's login sessions are authenticated separately. +The +.Em timestamp_type +option can be used to select the type of time stamp record +.Nm +will use. +.Ss Logging +By default, +.Nm +logs both successful and unsuccessful attempts (as well +as errors). +The +.Em log_allowed +and +.Em log_denied +flags can be used to control this behavior. +Messages can be logged to +.Xr syslog 3 , +a log file, or both. +The default is to log to +.Xr syslog 3 +but this is configurable via the +.Em syslog +and +.Em logfile +settings. +See +.Sx "EVENT LOGGING" +for a description of the log file format. +.Pp +.Nm +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 +.Sx "I/O LOGGING" +section. +.Pp +Starting with version 1.9, the +.Em log_servers +setting may be used to send event and I/O log data to a remote server running +.Nm sudo_logsrvd +or another service that implements the protocol described by +.Xr sudo_logsrv.proto @mansectform@ . +.Ss Command environment +Since environment variables can influence program behavior, +.Nm +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 +.Nm +can deal with environment variables. +.Pp +By default, the +.Em env_reset +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 +.Pa /etc/environment +file. +.if \n(LC \{\ +On +.Bx +systems, if the +.Em use_loginclass +flag is enabled, the environment is initialized +based on the +.Em path +and +.Em setenv +settings in +.Pa /etc/login.conf . +.\} +The +.Ev HOME , +.Ev MAIL , +.Ev SHELL , +.Ev LOGNAME +and +.Ev USER +environment variables are initialized based on the target user +and the +.Ev SUDO_* +variables are set based on the invoking user. +Additional variables, such as +.Ev DISPLAY , +.Ev PATH +and +.Ev TERM , +are preserved from the invoking user's environment if permitted by the +.Em env_check , +or +.Em env_keep +options. +A few environment variables are treated specially. +If the +.Ev PATH +and +.Ev TERM +variables are not preserved from the user's environment, they will be set +to default values. +The +.Ev LOGNAME +and +.Ev USER +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 +.Ev LOGNAME +and +.Ev USER +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 +.Ql () +are removed unless both the name and value parts are matched by +.Em env_keep +or +.Em env_check , +as they may be interpreted as functions by the +.Sy bash +shell. +Prior to version 1.8.11, such variables were always removed. +.Pp +If, however, the +.Em env_reset +flag is disabled, any variables not +explicitly denied by the +.Em env_check +and +.Em env_delete +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 +.Ql () +were always removed. +Beginning with version 1.8.21, a pattern in +.Em env_delete +is used to match +.Sy bash +shell functions instead. +Since it is not possible +to block all potentially dangerous environment variables, use +of the default +.Em env_reset +behavior is encouraged. +.Pp +Environment variables specified by +.Em env_check , +.Em env_delete , +or +.Em env_keep +may include one or more +.Ql * +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 +.Pq Ql =\& , +both the variables name and value must match. +For example, a +.Sy bash +shell function could be matched as follows: +.Bd -literal -offset 4n +env_keep += "BASH_FUNC_my_func%%=()*" +.Ed +.Pp +Without the +.Ql =()* +suffix, this would not match, as +.Sy bash +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 +.Em sudoers , +is displayed when +.Nm sudo +is run by +.Sy root +with the +.Fl V +option. +The list of environment variables to remove +varies based on the operating system +.Nm sudo +is running on. +.Pp +Other settings may influence the command environment: +.Bl -bullet -width 1n +.It +.Nm +options such as +.Em always_set_home , +.Em secure_path , +.Em set_logname , +.Em set_home , +and +.Em setenv . +.It +Command tags, such as +.Dv SETENV +and +.Dv NOSETENV . +Note that +.Dv SETENV +is implied if the command matched is +.Sy ALL . +.It +.Nm sudo +options, such as +.Fl E +and +.Fl i . +.El +.Pp +On systems that support PAM where the +.Sy pam_env +module is enabled for +.Nm sudo , +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 +.Nm . +When +.Em env_reset +is enabled, variables preserved from the invoking user's environment +by the +.Em env_keep +list take precedence over those in the PAM environment. +When +.Em env_reset +is disabled, variables present the invoking user's environment +take precedence over those in the PAM environment unless they +match a pattern in the +.Em env_delete +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 +.Nm sudo . +Depending on the operating +system this may include +.Ev _RLD* , +.Ev DYLD_* , +.Ev LD_* , +.Ev LDR_* , +.Ev LIBPATH , +.Ev SHLIB_PATH , +and others. +These type of variables are +removed from the environment before +.Nm sudo +even begins execution +and, as such, it is not possible for +.Nm sudo +to preserve them. +.Pp +As a special case, if the +.Fl i +option (initial login) is +specified, +.Nm +will initialize the environment regardless +of the value of +.Em env_reset . +The +.Ev DISPLAY , +.Ev PATH +and +.Ev TERM +variables remain unchanged; +.Ev HOME , +.Ev MAIL , +.Ev SHELL , +.Ev USER , +and +.Ev LOGNAME +are set based on the target user. +On AIX (and Linux +systems without PAM), the contents of +.Pa /etc/environment +are also +included. +.if \n(LC \{\ +On +.Bx +systems, if the +.Em use_loginclass +flag is +enabled, the +.Em path +and +.Em setenv +variables in +.Pa /etc/login.conf +are also applied. +.\} +All other environment variables are removed unless permitted by +.Em env_keep +or +.Em env_check , +described above. +.Pp +Finally, the +.Em restricted_env_file +and +.Em env_file +files are applied, if present. +The variables in +.Em restricted_env_file +are applied first and are subject to the same restrictions as the +invoking user's environment, as detailed above. +The variables in +.Em env_file +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 +.Em sudoers +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 +.Em sudoers +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, +.Nm +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 +.Pa pam_limits.so +PAM module. +On some BSD systems, the +.Pa /etc/login.conf +file specifies resource limits for the user. +On AIX systems, resource limits are configured in the +.Pa /etc/security/limits +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 +.Nm +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 +.Em sudoers +file itself, in which case they override those set by the system. +See the +.Em rlimit_as, +.Em rlimit_core, +.Em rlimit_cpu, +.Em rlimit_data, +.Em rlimit_fsize, +.Em rlimit_locks, +.Em rlimit_memlock, +.Em rlimit_nofile, +.Em rlimit_nproc, +.Em rlimit_rss, +.Em rlimit_stack +options described below. +Resource limits in +.Nm +may be specified in one of the following formats: +.Bl -tag -width 6n +.It Dq value +Both the soft and hard resource limits are set to the same value. +The special value +.Dq infinity +can be used to indicate that the value is unlimited. +.It Dq soft,hard +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 +.Pq Ql \e . +The special value +.Dq infinity +may be used in place of either value. +.It Dq default +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 +.Nm sudo +was invoked for systems that don't support per-user limits. +.It Dq user +The invoking user's resource limits will be preserved when running +the command. +.El +.Pp +For example, to restore the historic core dump file size behavior, +a line like the following may be used. +.sp +.Dl Defaults rlimit_core=default +.Pp +Resource limits in +.Nm +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 +.Em production rules . +For example: +.Bd -literal -offset 4n +symbol ::= definition | alternate1 | alternate2 ... +.Ed +.Pp +Each +.Em production rule +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 +.Dq wildcard +characters, which have different meanings. +.Bl -tag -width 4n +.It \&? +Means that the preceding symbol (or group of symbols) is optional. +That is, it may appear once or not at all. +.It * +Means that the preceding symbol (or group of symbols) may appear +zero or more times. +.It + +Means that the preceding symbol (or group of symbols) may appear +one or more times. +.El +.Pp +Parentheses may be used to group symbols together. +For clarity, +we will use single quotes +.Pq '' +to designate what is a verbatim character string (as opposed to a symbol name). +.Ss Aliases +There are four kinds of aliases: +.Em User_Alias , +.Em Runas_Alias , +.Em Host_Alias +and +.Em Cmnd_Alias . +Beginning with +.Nm sudo +1.9.0, +.Em Cmd_Alias +may be used in place of +.Em Cmnd_Alias +if desired. +.Bd -literal +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]_)* +.Ed +.Pp +Each +.Em alias +definition is of the form +.Bd -literal +Alias_Type NAME = item1, item2, ... +.Ed +.Pp +where +.Em Alias_Type +is one of +.Em User_Alias , +.Em Runas_Alias , +.Em Host_Alias , +or +.Em Cmnd_Alias . +A +.Dv NAME +is a string of uppercase letters, numbers, +and underscore characters +.Pq Ql _ . +A +.Dv NAME +.Sy must +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 +.Pq Ql :\& . +For example: +.Bd -literal +Alias_Type NAME = item1, item2, item3 : NAME = item4, item5 +.Ed +.Pp +It is a syntax error to redefine an existing +.Em alias . +It is possible to use the same name for +.Em aliases +of different types, but this is not recommended. +.Pp +The definitions of what constitutes a valid +.Em alias +member follow. +.Bd -literal +User_List ::= User | + User ',' User_List + +User ::= '!'* user name | + '!'* #user-ID | + '!'* %group | + '!'* %#group-ID | + '!'* +netgroup | + '!'* %:nonunix_group | + '!'* %:#nonunix_gid | + '!'* User_Alias +.Ed +.Pp +A +.Em User_List +is made up of one or more user names, user-IDs +(prefixed with +.Ql # ) , +system group names and IDs (prefixed with +.Ql % +and +.Ql %# +respectively), netgroups (prefixed with +.Ql + ) , +non-Unix group names and IDs (prefixed with +.Ql %: +and +.Ql %:# +respectively), and +.Em User_Alias Ns es. +Each list item may be prefixed with zero or more +.Ql \&! +operators. +An odd number of +.Ql \&! +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 +.Em user name , +.Em user-ID , +.Em group , +.Em group-ID , +.Em netgroup , +.Em nonunix_group +or +.Em nonunix_gid +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 +.Em nonunix_group +and +.Em nonunix_gid +syntax depends on +the underlying group provider plugin. +For instance, the QAS AD plugin supports the following formats: +.Bl -bullet -width 1n +.It +Group in the same domain: "%:Group Name" +.It +Group in any domain: "%:Group Name@FULLY.QUALIFIED.DOMAIN" +.It +Group SID: "%:S-1-2-34-5678901234-5678901234-5678901234-567" +.El +.Pp +See +.Sx "GROUP PROVIDER PLUGINS" +for more information. +.Pp +Quotes around group names are optional. +Unquoted strings must use a backslash +.Pq Ql \e +to escape spaces and special characters. +See +.Sx Other special characters and reserved words +for a list of +characters that need to be escaped. +.Bd -literal +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 +.Ed +.Pp +A +.Em Runas_List +is similar to a +.Em User_List +except that instead +of +.Em User_Alias Ns es +it can contain +.Em Runas_Alias Ns es . +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., +.Sy root +and +.Sy toor ) , +you can use a user-ID instead of a name (#0 in the example given). +The user-ID or group-ID specified in a +.Em Runas_Member +need not be listed in the password or group database. +.Bd -literal +Host_List ::= Host | + Host ',' Host_List + +Host ::= '!'* host name | + '!'* ip_addr | + '!'* network(/netmask)? | + '!'* +netgroup | + '!'* Host_Alias | + '!'* ALL +.Ed +.Pp +A +.Em Host_List +is made up of one or more host names, IP addresses, +network numbers, netgroups (prefixed with +.Ql + ) , +and other aliases. +Again, the value of an item may be negated with the +.Ql \&! +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, +.Nm sudo +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 +.Sx Wildcards +section below), +but unless the +.Em hostname +command on your machine returns the fully +qualified host name, you'll need to use the +.Em fqdn +flag for wildcards to be useful. +.Nm sudo +only inspects actual network interfaces; this means that IP address +127.0.0.1 (localhost) will never match. +Also, the host name +.Dq localhost +will only match if that is the actual host name, which is usually +only the case for non-networked systems. +.Bd -literal +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 +.Ed +.Pp +A +.Em Cmnd_List +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 +.Sx Wildcards +section below), +or a regular expression that starts with +.Ql ^ +and ends with +.Ql $ +(see the +.Sx Regular expressions +section below). +A directory is a +fully qualified path name ending in a +.Ql / . +When you specify a directory in a +.Em Cmnd_List , +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 +.Ql ^ +and ends with +.Ql $ . +If the command line arguments consist of +.Ql \&"" , +the command may only be run with +.Em no +arguments. +.Pp +If a +.Em Cmnd +has associated command line arguments, the arguments +in the +.Em Cmnd +must match those given by the user on the command line. +If the arguments in a +.Em Cmnd +begin with the +.Ql ^ +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 +.Ql \e +if they are used in command arguments: +.Ql ,\& , +.Ql :\& , +.Ql =\& , +.Ql \e . +To prevent arguments in a +.Em Cmnd +that begin with a +.Ql ^ +character from being interpreted as a regular expression, the +.Ql ^ +must be escaped with a +.Ql \e . +.Pp +There are two commands built into +.Nm sudo +itself: +.Dq list +and +.Dq sudoedit . +Unlike other commands, these two must be specified in the +.Em sudoers +file +.Em without +a leading path. +.Pp +The +.Dq list +built-in can be used to permit a user to list another user's privileges with +.Nm sudo Ns 's +.Fl U +option. +For example, +.Dq sudo -l -U otheruser . +A user with the +.Dq list +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 +.Ar user +on the current host may use the +.Fl U +option. +No command line arguments may be specified with the +.Dq list +built-in. +.Pp +The +.Dq sudoedit +built-in is used to permit a user to run +.Nm sudo +with the +.Fl e +option (or as +.Nm sudoedit ) . +It may take command line arguments just as a normal command does. +Unlike other commands, +.Dq sudoedit +is built into +.Nm sudo +itself and must be specified in the +.Em sudoers +file +.Em without +a leading path. +If a leading path is present, for example +.Pa /usr/bin/sudoedit , +the path name will be silently converted to +.Dq sudoedit . +A fully-qualified path for +.Nm sudoedit +is treated as an error by +.Nm visudo . +.Pp +A +.Em command +may be preceded by a +.Em Digest_List , +a comma-separated list of one or more +.Em Digest_Spec +entries. +If a +.Em Digest_List +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 +.Sy ALL +reserved word can be used in conjunction with a +.Em Digest_List . +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: +.Bd -literal +$ openssl dgst -sha224 /bin/ls +SHA224(/bin/ls)= 118187da8364d490b4a7debbf483004e8f3e053ec954309de2c41a25 +.Ed +.Pp +It is also possible to use openssl to generate base64 output: +.Bd -literal +$ openssl dgst -binary -sha224 /bin/ls | openssl base64 +EYGH2oNk1JC0p9679IMATo8+BT7JVDCd4sQaJQ== +.Ed +.Pp +Warning, if the user has write access to the command itself (directly or via a +.Nm sudo +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 +.Xr fexecve 2 +system call when the directory in which the command is located +is writable by the user. +See the description of the +.Em fdexec +setting for more information on how +.Nm sudo +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 +.Em Default_Entry +lines. +These may affect all users on any host +.Pq Sq Defaults , +all users on a specific host +.Pq Sq Defaults@host , +a specific user +.Pq Sq Defaults:user , +a specific command +.Pq Sq Defaults!cmnd , +or commands being run as a specific user +.Pq Sq Defaults>runasuser . +.Pp +White space is not permitted between +.Sq Defaults +and the +.Ql @ , +.Ql \&: , +.Ql \&! , +or +.Ql > +characters. +While a comma-separated list may be used in place of a single value after the +.Ql @ , +.Ql \&: , +.Ql \&! , +or +.Ql > +character, using an alias instead of a list is often improve readability. +Per-command entries may not include command line arguments. +If you need to specify arguments, define a +.Em Cmnd_Alias +and reference that instead. +.Bd -literal +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 +.Ed +.Pp +Parameters may be +.Sy flags , +.Sy integer +values, +.Sy strings , +or +.Sy lists . +Flags are implicitly boolean and can be turned off via the +.Ql \&! +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 +.Pq \&"" +when they contain multiple words. +Special characters may be escaped with a backslash +.Pq Ql \e . +.Pp +To include a literal backslash character in a command line argument +you must escape the backslash twice. +For example, to match +.Ql \en +as part of a command line argument, you must use +.Ql \e\e\e\en +in the +.Em sudoers +file. +This is due to there being two levels of escaping, one in the +.Em sudoers +parser itself and another when command line arguments are matched by the +.Xr fnmatch 3 +or +.Xr regexec 3 +function. +.Pp +Lists have two additional assignment operators, +.Ql += +and +.Ql -= . +These operators are used to add to and delete from a list respectively. +It is not an error to use the +.Ql -= +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: +.Em fqdn , +.Em group_plugin , +.Em runas_default , +.Em sudoers_locale . +.Pp +See +.Sx SUDOERS OPTIONS +for a list of supported Defaults parameters. +.Ss User specification +.Bd -literal +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 | Chdir_Spec | Chroot_Spec) +.el Option_Spec ::= (SELinux_Spec | Date_Spec | Timeout_Spec | Chdir_Spec | Chroot_Spec) +.\} +.el \{\ +.ie \n(AA \{\ +.ie \n(PS Option_Spec ::= (AppArmor_Spec | Solaris_Priv_Spec | Date_Spec | Timeout_Spec | Chdir_Spec | Chroot_Spec) +.el Option_Spec ::= (AppArmor_Spec | Date_Spec | Timeout_Spec | Chdir_Spec | Chroot_Spec) +.\} +.el \{\ +.ie \n(PS Option_Spec ::= (Solaris_Priv_Spec | Date_Spec | Timeout_Spec | Chdir_Spec | Chroot_Spec) +.el Option_Spec ::= (Date_Spec | Timeout_Spec | Chdir_Spec | Chroot_Spec) +.\} +.\} + +.if \n(SL \{\ +SELinux_Spec ::= ('ROLE=role' | 'TYPE=type') + +.\} +.if \n(AA \{\ +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') +.Ed +.Pp +A +.Sy user specification +determines which commands a user may run +(and as what user) on specified hosts. +By default, commands are run as +.Sy @runas_default@ +(unless +.Em runas_default +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 +.Dq who where = (as_whom) what . +Let's break that down into its constituent parts: +.Ss Runas_Spec +A +.Em Runas_Spec +determines the user and/or the group that a command +may be run as. +A fully-specified +.Em Runas_Spec +consists of two +.Em Runas_List Ns s +(as defined above) separated by a colon +.Pq Ql \&: +and enclosed in a set of parentheses. +The first +.Em Runas_List +indicates which users the command may be run as via the +.Fl u +option. +The second defines a list of groups that may be specified via the +.Fl g +option (in addition to any of the target user's groups). +If both +.Em Runas_List Ns s +are specified, the command may be run with any combination of users +and groups listed in their respective +.Em Runas_List Ns s. +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 +.Em Runas_List +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 +.Em Runas_List . +If both +.Em Runas_List Ns s +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 +.Em Runas_Spec +is specified, the command may only be run as the +.Em runas_default +user +.Sy ( @runas_default@ +by default) and the group, +if specified, must be one that the +.Em runas_default +user is a member of. +.Pp +A +.Em Runas_Spec +sets the default for the commands that follow it. +What this means is that for the entry: +.Bd -literal +dgb boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm +.Ed +.Pp +The user +.Sy dgb +may run +.Pa /bin/ls , +.Pa /bin/kill , +and +.Pa /usr/bin/lprm +on the host +.No boulder Ns \(em Ns but +only as +.Sy operator . +For example: +.Bd -literal +$ sudo -u operator /bin/ls +.Ed +.Pp +It is also possible to override a +.Em Runas_Spec +later on in an entry. +If we modify the entry like so: +.Bd -literal +dgb boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm +.Ed +.Pp +Then user +.Sy dgb +is now allowed to run +.Pa /bin/ls +as +.Sy operator , +but +.Pa /bin/kill +and +.Pa /usr/bin/lprm +as +.Sy root . +.Pp +We can extend this to allow +.Sy dgb +to run +.Pa /bin/ls +with either +the user or group set to +.Sy operator : +.Bd -literal +dgb boulder = (operator : operator) /bin/ls, (root) /bin/kill,\e + /usr/bin/lprm +.Ed +.Pp +While the group portion of the +.Em Runas_Spec +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: +.Bd -literal +$ sudo -u operator /bin/ls +$ sudo -u operator -g operator /bin/ls +$ sudo -g operator /bin/ls +.Ed +.Pp +In the following example, user +.Sy tcm +may run commands that access +a modem device file with the dialer group. +.Bd -literal +tcm boulder = (:dialer) /usr/bin/tip, /usr/bin/cu,\e + /usr/local/bin/minicom +.Ed +.Pp +In this example only the group will be set, the command still runs as user +.Sy tcm . +For example: +.Bd -literal +$ sudo -g dialer /usr/bin/cu +.Ed +.Pp +Multiple users and groups may be present in a +.Em Runas_Spec , +in which case the user may select any combination of users and groups via the +.Fl u +and +.Fl g +options. +In this example: +.Bd -literal +alan ALL = (root, bin : operator, system) ALL +.Ed +.Pp +user +.Sy alan +may run any command as either user +.Sy root +or +.Sy bin , +optionally setting the group to operator or system. +.Ss Option_Spec +A +.Em Cmnd +may have zero or more options associated with it. +Options may consist of +.if \n(SL \{\ +SELinux roles and/or types, +.\} +.if \n(AA \{\ +AppArmor profiles, +.\} +.if \n(PS \{\ +Solaris privileges sets, +.\} +start and/or end dates and command timeouts. +Once an option is set for a +.Em Cmnd , +subsequent +.Em Cmnd Ns s +in the +.Em Cmnd_Spec_List , +inherit that option unless it is overridden by another option. +Option names are reserved words in +.Em sudoers . +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, +.Em sudoers +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 +.Em sudoers . +A role or type specified on the command line, +however, will supersede the values in +.Em sudoers . +.\} +.if \n(AA \{\ +.Ss AppArmor_Spec +On systems supporting AppArmor, +.Em sudoers +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 +.Em sudoers . +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 +.Xr aa_change_profile 2 . +For instance, in the following +.Em sudoers +entry +.Bd -literal +alice ALL = (root) APPARMOR_PROFILE=my-profile ALL +.Ed +.Pp +the user +.Sy alice +may run any command as +.Sy root +under confinement by the profile +.Ql my-profile . +You can also stack profiles, or allow a user to run commands unconfined by +any profile. +For example: +.Bd -literal +bob ALL = (root) APPARMOR_PROFILE=foo//&bar /usr/bin/vi +cathy ALL = (root) APPARMOR_PROFILE=unconfined /bin/ls +.Ed +.Pp +These +.Em sudoers +entries allow user +.Sy bob +to run +.Pa /usr/bin/vi +as +.Sy root +under the stacked profiles +.Ql foo +and +.Ql bar , +and user +.Sy cathy +to run +.Pa /bin/ls +without any confinement at all. +.\} +.if \n(PS \{\ +.Ss Solaris_Priv_Spec +On Solaris systems, +.Em sudoers +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 +.Em sudoers . +.Pp +A privilege set is a comma-separated list of privilege names. +The +.Xr ppriv 1 +command can be used to list all privileges known to the system. +For example: +.Bd -literal +$ ppriv -l +.Ed +.Pp +In addition, there are several +.Dq special +privilege strings: +.Bl -tag -width "basic" +.It none +the empty set +.It all +the set of all privileges +.It zone +the set of all privileges available in the current zone +.It basic +the default set of privileges normal users are granted at login time +.El +.Pp +Privileges can be excluded from a set by prefixing the privilege +name with either an +.Ql \&! +or +.Ql \- +character. +.\} +.Ss Date_Spec +.Nm +rules can be specified with a start and end date via the +.Dv NOTBEFORE +and +.Dv NOTAFTER +settings. +The time stamp must be specified in +.Dq Generalized Time +as defined by RFC 4517. +The format is effectively +.Ql yyyymmddHHMMSSZ +where the minutes and seconds are optional. +The +.Ql Z +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 +.Ql Z . +For example, +.Ql -0500 +would correspond to Eastern Standard time in the US. +As an extension, if no +.Ql Z +or timezone offset is specified, local time will be used. +.Pp +The following are all valid time stamps: +.Bd -literal -offset 4n +20170214083000Z +2017021408Z +20160315220000-0500 +20151201235900 +.Ed +.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 +.Ql 7d8h30m10s . +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 +.Em valid +timeout values: +.Ql 7d8h30m10s , +.Ql 14d , +.Ql 8h30m , +.Ql 600s , +.Ql 3600 . +The following are +.Em invalid +timeout values: +.Ql 12m2w1d , +.Ql 30s10m4h , +.Ql 1d2d3h . +.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 +.Dv CWD +setting. +The +.Fa directory +must be a fully-qualified path name beginning with a +.Sq / +or +.Sq ~ +character, or the special value +.Dq * . +A value of +.Dq * +indicates that the user may specify the working directory by running +.Nm sudo +with the +.Fl D +option. +By default, commands are run from the invoking user's current working +directory, unless the +.Fl i +option is given. +Path names of the form +.Pa ~user/path/name +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 +.Dv CHROOT +setting. +The +.Fa directory +must be a fully-qualified path name beginning with a +.Sq / +or +.Sq ~ +character, or the special value +.Dq * . +A value of +.Dq * +indicates that the user may specify the root directory by running +.Nm sudo +with the +.Fl R +option. +This setting can be used to run the command in a +.Xr chroot 2 +.Dq sandbox +similar to the +.Xr chroot @mansectsu@ +utility. +Path names of the form +.Pa ~user/path/name +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: +.Dv EXEC , +.Dv NOEXEC , +.Dv FOLLOW , +.Dv NOFOLLOW , +.Dv LOG_INPUT , +.Dv NOLOG_INPUT , +.Dv LOG_OUTPUT , +.Dv NOLOG_OUTPUT , +.Dv MAIL , +.Dv NOMAIL , +.Dv INTERCEPT , +.Dv NOINTERCEPT , +.Dv PASSWD , +.Dv NOPASSWD , +.Dv SETENV , +and +.Dv NOSETENV . +Once a tag is set on a +.Em Cmnd , +subsequent +.Em Cmnd Ns s +in the +.Em Cmnd_Spec_List , +inherit the tag unless it is overridden by the opposite tag (in other words, +.Dv PASSWD +overrides +.Dv NOPASSWD +and +.Dv NOEXEC +overrides +.Dv EXEC ) . +.Bl -hang -width 0n +.It Dv EXEC No and Dv NOEXEC +.sp +If +.Nm sudo +has been compiled with +.Em noexec +support and the underlying operating system supports it, the +.Dv NOEXEC +tag can be used to prevent a dynamically-linked executable from +running further commands itself. +.Pp +In the following example, user +.Sy aaron +may run +.Pa /usr/bin/more +and +.Pa /usr/bin/vi +on the host shanty, but shell escapes will be disabled. +.Bd -literal +aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi +.Ed +.Pp +See the +.Sx Preventing shell escapes +section below for more details on how +.Dv NOEXEC +works and whether or not it will work on your system. +.It Dv FOLLOW No and Dv NOFOLLOW +.sp +Starting with version 1.8.15, +.Nm sudoedit +will not open a file that is a symbolic link unless the +.Em sudoedit_follow +flag is enabled. +The +.Dv FOLLOW +and +.Dv NOFOLLOW +tags override the value of +.Em sudoedit_follow +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 +.Em sudoedit +command and are ignored for all other commands. +.It Dv LOG_INPUT No and Dv NOLOG_INPUT +.sp +These tags override the value of the +.Em log_input +flag on a per-command basis. +For more information, see +.Sx "I/O LOGGING" . +.It Dv LOG_OUTPUT No and Dv NOLOG_OUTPUT +.sp +These tags override the value of the +.Em log_output +flag on a per-command basis. +For more information, see +.Sx "I/O LOGGING" . +.It Dv MAIL No and Dv NOMAIL +.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 +.Em mail_all_cmnds +flag on a per-command basis. +They have no effect when +.Nm sudo +is run with the +.Fl l +or +.Fl v +options. +A +.Dv NOMAIL +tag will also override the +.Em mail_always +and +.Em mail_no_perms +options. +For more information, see the descriptions of +.Em mail_all_cmnds , +.Em mail_always , +and +.Em mail_no_perms +in the +.Sx SUDOERS OPTIONS +section below. +.It Dv PASSWD No and Dv NOPASSWD +.sp +By default, +.Nm sudo +requires that a user authenticate +before running a command. +This behavior can be modified via the +.Dv NOPASSWD +tag. +Like a +.Em Runas_Spec , +the +.Dv NOPASSWD +tag sets +a default for the commands that follow it in the +.Em Cmnd_Spec_List . +Conversely, the +.Dv PASSWD +tag can be used to reverse things. +For example: +.Bd -literal +ray rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm +.Ed +.Pp +would allow the user +.Sy ray +to run +.Pa /bin/kill , +.Pa /bin/ls , +and +.Pa /usr/bin/lprm +as +.Sy @runas_default@ +on the machine +.Dq rushmore +without authenticating himself. +If we only want +.Sy ray +to be able to +run +.Pa /bin/kill +without a password the entry would be: +.Bd -literal +ray rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm +.Ed +.Pp +Note, however, that the +.Dv PASSWD +tag has no effect on users who are in the group specified by the +.Em exempt_group +setting. +.Pp +By default, if the +.Dv NOPASSWD +tag is applied to any of a user's entries for the current host, +the user will be able to run +.Ql sudo -l +without a password. +Additionally, a user may only run +.Ql sudo -v +without a password if all of the user's entries for the current +host have the +.Dv NOPASSWD +tag. +This behavior may be overridden via the +.Em verifypw +and +.Em listpw +options. +.It Dv SETENV No and Dv NOSETENV +.sp +These tags override the value of the +.Em setenv +flag on a per-command basis. +If +.Dv SETENV +has been set for a command, the user may disable the +.Em env_reset +flag from the command line via the +.Fl E +option. +Additionally, environment variables set on the command +line are not subject to the restrictions imposed by +.Em env_check , +.Em env_delete , +or +.Em env_keep . +As such, only trusted users should be allowed to set variables in this manner. +If the command matched is +.Sy ALL , +the +.Dv SETENV +tag is implied for that command; this default may be overridden by use of the +.Dv NOSETENV +tag. +.It Dv INTERCEPT No and Dv NOINTERCEPT +.sp +If +.Nm sudo +has been compiled with +.Em intercept +support and the underlying operating system supports it, the +.Dv INTERCEPT +tag can be used to cause programs spawned by a command to be validated against +.Em sudoers +and logged just like they would be if run through +.Nm sudo +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. +.Pp +In the following example, user +.Sy chuck +may run any command on the machine +.Dq research +in intercept mode. +.Bd -literal +chuck research = INTERCEPT: ALL +.Ed +.Pp +See the +.Sx Preventing shell escapes +section below for more details on how +.Dv INTERCEPT +works and whether or not it will work on your system. +.El +.Ss Wildcards +.Nm sudo +allows shell-style +.Em wildcards +(aka meta or glob characters) +to be used in host names, path names, and command line arguments in the +.Em sudoers +file. +Wildcard matching is done via the +.Xr glob 3 +and +.Xr fnmatch 3 +functions as specified by +.St -p1003.1 . +.Bl -tag -width "[!...]" +.It * +Matches any set of zero or more characters (including white space). +.It \&? +Matches any single character (including white space). +.It [...] +Matches any character in the specified range. +.It [!...] +Matches any character +.Em not +in the specified range. +.It \ex +For any character +.Sq x , +evaluates to +.Sq x . +This is used to escape special characters such as: +.Ql * , +.Ql \&? , +.Ql [\& , +and +.Ql ]\& . +.El +.Pp +.Bf -symbolic +These are not regular expressions. +.Ef +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 +.Xr glob 3 +and +.Xr fnmatch 3 +functions support them. +However, because the +.Ql :\& +character has special meaning in +.Em sudoers , +it must be +escaped. +For example: +.Bd -literal -offset 4n +/bin/ls [[\e:\&alpha\e:\&]]* +.Ed +.Pp +Would match any file name beginning with a letter. +.Pp +A forward slash +.Pq Ql / +will +.Em not +be matched by +wildcards used in the file name portion of the command. +This is to make a path like: +.Bd -literal -offset 4n +/usr/bin/* +.Ed +.Pp +match +.Pa /usr/bin/who +but not +.Pa /usr/bin/X11/xterm . +.Pp +When matching the command line arguments, however, a slash +.Em does +get matched by wildcards since command line arguments may contain +arbitrary strings and not just path names. +.Pp +.Bf -symbolic +Wildcards in command line arguments should be used with care. +.Ef +.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 +.Sx Wildcards in command arguments +below. +.Ss Exceptions to wildcard rules +The following exceptions apply to the above rules: +.Bl -tag -width "sudoedit" +.It \&"" +If the empty string +.Ql \&"" +is the only command line argument in the +.Em sudoers +file entry it means that command is not allowed to be run with +.Em any +arguments. +.It sudoedit +Command line arguments to the +.Em sudoedit +built-in command should always be path names, so a forward slash +.Pq Ql / +will not be matched by a wildcard. +.El +.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 +.Em wildcards +and are usually safer because they provide a greater degree of +control when matching. +The type of regular expressions supported by +.Nm +are POSIX extended regular expressions, similar to those used by the +.Xr egrep 1 +utility. +They are usually documented in the +.Xr regex @mansectmisc@ +or +.Xr re_format @mansectmisc@ +manual, depending on the system. +As an extension, if the regular expression begins with +.Dq (?i) , +it will be matched in a case-insensitive manner. +.Pp +In +.Em sudoers , +regular expressions must start with a +.Ql ^ +character and end with a +.Ql $ . +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 +.Em sudoers +are limited to 1024 characters. +.Pp +There is no need to escape +.Em sudoers +special characters in a regular expression other than the pound sign +.Pq Ql # . +.Pp +In the following example, user +.Sy john +can run the +.Xr passwd 1 +command as +.Sy @runas_default@ +on any host but is not allowed to change +.Sy root Ns No 's +password. +This kind of rule is impossible to express safely using wildcards. +.Bd -literal -offset 4n +john ALL = /usr/bin/passwd ^[a-zA-Z0-9_]+$,\e + !/usr/bin/passwd root +.Ed +.Pp +It is also possible to use a regular expression in conjunction with +.Nm sudoedit +rules. +The following rule would give user bob the ability to edit the +.Pa /etc/motd , +.Pa /etc/issue , +and +.Pa /etc/hosts +files only. +.Bd -literal -offset 4n +bob ALL = sudoedit ^/etc/(motd|issue|hosts)$ +.Ed +.Pp +Regular expressions may also be used to match the command itself. +In this example, a regular expression is used to allow user +.Sy sid +to run the +.Pa /usr/sbin/groupadd , +.Pa /usr/sbin/groupmod , +.Pa /usr/sbin/groupdel , +.Pa /usr/sbin/useradd , +.Pa /usr/sbin/usermod , +and +.Pa /usr/sbin/userdel +commands as +.Sy @runas_default@ . +.Bd -literal -offset 4n +sid ALL = ^/usr/sbin/(group|user)(add|mod|del)$ +.Ed +.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 +.Pa ./useradd +or +.Pa ../sbin/useradd . +This has security implications when a regular expression is used +for the command name in conjunction with the negation operator, +.Ql !\& , +as such rules can be trivially bypassed. +Because of this, using a negated regular expression for the command name is +.Sy strongly discouraged . +This does not apply to negated commands that only use a regular +expression to match the command arguments. +See +.Sx Regular expressions in command names +below for more information. +.Ss Including other files from within sudoers +It is possible to include other +.Em sudoers +files from within the +.Em sudoers +file currently being parsed using the +.Em @include +and +.Em @includedir +directives. +For compatibility with sudo versions prior to 1.9.1, +.Em #include +and +.Em #includedir +are also accepted. +.Pp +An include file can be used, for example, to keep a site-wide +.Em sudoers +file in addition to a local, per-machine file. +For the sake of this example the site-wide +.Em sudoers +file will be +.Pa /etc/sudoers +and the per-machine one will be +.Pa /etc/sudoers.local . +To include +.Pa /etc/sudoers.local +from within +.Pa /etc/sudoers +one would use the following line in +.Pa /etc/sudoers : +.Bd -literal -offset 4n +@include /etc/sudoers.local +.Ed +.Pp +When +.Nm sudo +reaches this line it will suspend processing of the current file +.Pq Pa /etc/sudoers +and switch to +.Pa /etc/sudoers.local . +Upon reaching the end of +.Pa /etc/sudoers.local , +the rest of +.Pa /etc/sudoers +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 +.Pq Ql \e . +Alternately, the entire path may be enclosed in double quotes +.Pq \&"" , +in which case no escaping is necessary. +To include a literal backslash in the path, +.Ql \e\e +should be used. +.Pp +If the path to the include file is not fully-qualified (does not +begin with a +.Ql / ) , +it must be located in the same directory as the sudoers file it was +included from. +For example, if +.Pa /etc/sudoers +contains the line: +.Bd -literal -offset 4n +@include sudoers.local +.Ed +.Pp +the file that will be included is +.Pa /etc/sudoers.local . +.Pp +The file name may also include the +.Ql %h +escape, signifying the short form of the host name. +In other words, if the machine's host name is +.Dq xerxes , +then +.Bd -literal -offset 4n +@include /etc/sudoers.%h +.Ed +.Pp +will cause +.Nm sudo +to include the file +.Pa /etc/sudoers.xerxes . +Any path name separator characters +.Pq Ql / +present in the host name will be replaced with an underbar +.Pq Ql _ +during expansion. +.Pp +The +.Em @includedir +directive can be used to create a +.Pa sudoers.d +directory that the system package manager can drop +.Em sudoers +file rules into as part of package installation. +For example, given: +.Bd -literal -offset 4n +@includedir /etc/sudoers.d +.Ed +.Pp +.Nm sudo +will suspend processing of the current file and read each file in +.Pa /etc/sudoers.d , +skipping file names that end in +.Ql ~ +or contain a +.Ql .\& +character to avoid causing problems with package manager or editor +temporary/backup files. +.Pp +Files are parsed in sorted lexical order. +That is, +.Pa /etc/sudoers.d/01_first +will be parsed before +.Pa /etc/sudoers.d/10_second . +Be aware that because the sorting is lexical, not numeric, +.Pa /etc/sudoers.d/1_whoops +would be loaded +.Em after +.Pa /etc/sudoers.d/10_second . +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 +.Em @includedir +directive. +.Pp +Unlike files included via +.Em @include , +.Nm visudo +will not edit the files in a +.Em @includedir +directory unless one of them contains a syntax error. +It is still possible to run +.Nm visudo +with the +.Fl f +flag to edit the files directly, but this will not catch the +redefinition of an +.Em alias +that is also present in a different file. +.Ss Other special characters and reserved words +The pound sign +.Pq Ql # +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 +.Sy ALL +is a built-in +.Em alias +that always causes a match to succeed. +It can be used wherever one might otherwise use a +.Em Cmnd_Alias , +.Em User_Alias , +.Em Runas_Alias , +or +.Em Host_Alias . +Attempting to define an +.Em alias +named +.Sy ALL +will result in a syntax error. +Using +.Sy ALL +can be dangerous since in a command context, it allows the user to run +.Em any +command on the system. +.Pp +The following option names permitted in an +.Em Option_Spec +are also considered reserved words: +.Dv CHROOT , +.if \n(PS \{\ +.Dv PRIVS , +.Dv LIMITPRIVS , +.\} +.if \n(SL \{\ +.Dv ROLE , +.Dv TYPE , +.\} +.Dv TIMEOUT , +.Dv CWD , +.Dv NOTBEFORE +and +.Dv NOTAFTER . +Attempting to define an +.Em alias +with the same name as one of the options will result in a syntax error. +.Pp +An exclamation point +.Pq Ql \&! +can be used as a logical +.Em not +operator in a list or +.Em alias +as well as in front of a +.Em Cmnd . +This allows one to exclude certain values. +For the +.Ql \&! +operator to be effective, there must be something for it to exclude. +For example, to match all users except for +.Sy root +one would use: +.Bd -literal -offset 4n +ALL, !root +.Ed +.Pp +If the +.Sy ALL , +is omitted, as in: +.Bd -literal -offset 4n +!root +.Ed +.Pp +it would explicitly deny +.Sy root +but not match any other users. +This is different from a true +.Dq negation +operator. +.Pp +Note, however, that using a +.Ql \&! +in conjunction with the built-in +.Sy ALL +alias to allow a user to run +.Dq all but a few +commands rarely works as intended (see +.Sx SECURITY NOTES +below). +.Pp +Long lines can be continued with a backslash +.Pq Ql \e +as the last character on the line. +.Pp +White space between elements in a list as well as special syntactic +characters in a +.Em User Specification +.Po +.Ql =\& , +.Ql :\& , +.Ql (\& , +.Ql )\& +.Pc +is optional. +.Pp +The following characters must be escaped with a backslash +.Pq Ql \e +when used as part of a word (e.g., a user name or host name): +.Ql \&! , +.Ql =\& , +.Ql :\& , +.Ql ,\& , +.Ql (\& , +.Ql )\& , +.Ql \e . +.Sh SUDOERS OPTIONS +.Nm sudo Ns 's +behavior can be modified by +.Em Default_Entry +lines, as explained earlier. +A list of all supported Defaults parameters, grouped by type, are listed below. +.Pp +.Sy Boolean Flags : +.Bl -tag -width 16n +.It always_query_group_plugin +If a +.Em group_plugin +is configured, use it to resolve groups of the form +.Ql %group +as long as there is not also a system group of the same name. +Normally, only groups of the form +.Ql %:group +are passed to the +.Em group_plugin . +This flag is +.Em off +by default. +.It always_set_home +If enabled, +.Nm sudo +will set the +.Ev HOME +environment variable to the home directory of the target user +(which is the +.Em runas_default +user unless the +.Fl u +option is used). +This flag is largely obsolete and has no effect unless the +.Em env_reset +flag has been disabled or +.Ev HOME +is present in the +.Em env_keep +list, both of which are strongly discouraged. +This flag is +.Em off +by default. +.It 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 +.Dv PASSWD +and +.Dv NOPASSWD +tags. +This flag is +.Em on +by default. +.It case_insensitive_group +If enabled, group names in +.Em sudoers +will be matched in a case insensitive manner. +This may be necessary when users are stored in LDAP or AD. +This flag is +.Em on +by default. +.It case_insensitive_user +If enabled, user names in +.Em sudoers +will be matched in a case insensitive manner. +This may be necessary when groups are stored in LDAP or AD. +This flag is +.Em on +by default. +.It closefrom_override +If set, the user may use the +.Fl C +option which overrides the default starting point at which +.Nm sudo +begins closing open file descriptors. +This flag is +.Em off +by default. +.It compress_io +If set, and +.Nm sudo +is configured to log a command's input or output, +the I/O logs will be compressed using +.Sy zlib . +This flag is +.Em on +by default when +.Nm sudo +is compiled with +.Sy zlib +support. +.It exec_background +By default, +.Nm sudo +runs a command as the foreground process as long as +.Nm sudo +itself is running in the foreground. +When the +.Em exec_background +flag is enabled and the command is being run in a pseudo-terminal +(due to I/O logging or the +.Em use_pty +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 +.Dv SIGTTIN +signal (or +.Dv SIGTTOU +in the case of terminal settings). +If this happens when +.Nm sudo +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 +.Nm sudo +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 +.Em sudo +behavior or when the command is not being run in a pseudo-terminal. +.Pp +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 +.Xr tcgetattr 3 +and +.Xr tcsetattr 3 +functions (this is a bug in macOS). +Furthermore, because this behavior depends on the command stopping with the +.Dv SIGTTIN +or +.Dv SIGTTOU +signals, programs that catch these signals and suspend themselves +with a different signal (usually +.Dv SIGTOP ) +will not be automatically foregrounded. +Some versions of the linux +.Xr su 1 +command behave this way. +This flag is +.Em off +by default. +.Pp +This setting is only supported by version 1.8.7 or higher. +It has no effect unless I/O logging is enabled or the +.Em use_pty +flag is enabled. +.It env_editor +If set, +.Nm visudo +will use the value of the +.Ev SUDO_EDITOR , +.Ev VISUAL +or +.Ev EDITOR +environment variables before falling back on the default editor list. +.Nm visudo +is typically run as +.Sy root +so this flag may allow a user with +.Nm visudo +privileges to run arbitrary commands as +.Sy root +without logging. +An alternative is to place a colon-separated list of +.Dq safe +editors int the +.Em editor +setting. +.Nm visudo +will then only use +.Ev SUDO_EDITOR , +.Ev VISUAL +or +.Ev EDITOR +if they match a value specified in +.Em editor . +If the +.Em env_reset +flag is enabled, the +.Ev SUDO_EDITOR , +.Ev VISUAL +and/or +.Ev EDITOR +environment variables must be present in the +.Em env_keep +list for the +.Em env_editor +flag to function when +.Nm visudo +is invoked via +.Nm sudo . +This flag is +.Em @env_editor@ +by default. +.It env_reset +If set, +.Nm sudo +will run the command in a minimal environment containing the +.Ev TERM , +.Ev PATH , +.Ev HOME , +.Ev MAIL , +.Ev SHELL , +.Ev LOGNAME , +.Ev USER +and +.Ev SUDO_* +variables. +Any variables in the caller's environment or in the file specified +by the +.Em restricted_env_file +setting that match the +.Em env_keep +and +.Em env_check +lists are then added, followed by any variables present in the file +specified by the +.Em env_file +setting (if any). +The contents of the +.Em env_keep +and +.Em env_check +lists, as modified by global Defaults parameters in +.Em sudoers , +are displayed when +.Nm sudo +is run by +.Sy root +with the +.Fl V +option. +If the +.Em secure_path +setting is enabled, its value will be used for the +.Ev PATH +environment variable. +This flag is +.Em @env_reset@ +by default. +.It fast_glob +Normally, +.Nm sudo +uses the +.Xr glob 3 +function to do shell-style globbing when matching path names. +However, since it accesses the file system, +.Xr 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 +.Em fast_glob +flag causes +.Nm sudo +to use the +.Xr fnmatch 3 +function, which does not access the file system to do its matching. +The disadvantage of +.Em fast_glob +is that it is unable to match relative paths such as +.Pa ./ls +or +.Pa ../bin/ls . +This has security implications when path names that include globbing +characters are used with the negation operator, +.Ql !\& , +as such rules can be trivially bypassed. +As such, this flag should not be used when the +.Em sudoers +file contains rules that contain negated path names which include globbing +characters. +This flag is +.Em off +by default. +.It 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 +.Sx "I/O LOGGING" ) , +the password will still be present in the I/O log. +If the +.Em log_passwords +option is disabled, +.Nm +will attempt to prevent passwords from being logged. +It does this by using the regular expressions in +.Em passprompt_regex +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 +.Ql * +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 +.Nm sudo +when +.Em pwfeedback +is set), only the +first character of the password will be replaced in the I/O log. +This option has no effect unless +.Em log_input +or +.Em log_ttyin +are also set. +This flag is +.Em on +by default. +.Pp +This setting is only supported by version 1.9.10 or higher. +.It fqdn +Set this flag if you want to put fully qualified host names in the +.Em sudoers +file when the local host name (as returned by the +.Ql hostname +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 +.Dq canonical +host name, as returned by the +.Xr getaddrinfo 3 +or +.Xr 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. +.Pp +If the system is configured to use the +.Pa /etc/hosts +file in preference to DNS, the +.Dq canonical +host name may not be fully-qualified. +The order that sources are queried for host name resolution +is usually specified in the +.Pa @nsswitch_conf@ , +.Pa @netsvc_conf@ , +.Pa /etc/host.conf , +or, in some cases, +.Pa /etc/resolv.conf +file. +In the +.Pa /etc/hosts +file, the first host name of the entry is considered to be the +.Dq canonical +name; subsequent names are aliases that are not used by +.Nm . +For example, the following hosts file line for the machine +.Dq xyzzy +has the fully-qualified domain name as the +.Dq canonical +host name, and the short version as an alias. +.sp +.Dl 192.168.1.1 xyzzy.sudo.ws xyzzy +.sp +If the machine's hosts file entry is not formatted properly, the +.Em fqdn +flag will not be effective if it is queried before DNS. +.Pp +Beware that when using DNS for host name resolution, turning on +.Em fqdn +requires +.Nm +to make DNS lookups which renders +.Nm sudo +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 +.Dq canonical +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. +.Pp +This flag is +.Em @fqdn@ +by default. +.It ignore_audit_errors +Allow commands to be run even if +.Nm +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 +.Nm +supports audit logging, including +.Fx , +Linux, macOS, and Solaris. +This flag is +.Em on +by default. +.It ignore_dot +If set, +.Nm sudo +will ignore "." or "" (both denoting the current directory) in the +.Ev PATH +environment variable; the +.Ev PATH +itself is not modified. +This flag is +.Em @ignore_dot@ +by default. +.It ignore_iolog_errors +Allow commands to be run even if +.Nm +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 +.Em off +by default. +.It ignore_logfile_errors +Allow commands to be run even if +.Nm +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 +.Nm +is configured to use file-based logging via the +.Em logfile +setting. +This flag is +.Em on +by default. +.It ignore_local_sudoers +If set via LDAP, parsing of +.Pa @sysconfdir@/sudoers +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 +.Pa @sysconfdir@/sudoers . +When this flag is enabled, +.Pa @sysconfdir@/sudoers +does not even need to exist. +Since this flag tells +.Nm sudo +how to behave when no specific LDAP entries have been matched, this +sudoOption is only meaningful for the +.Ql cn=defaults +section. +This flag is +.Em off +by default. +.It ignore_unknown_defaults +If set, +.Nm sudo +will not produce a warning if it encounters an unknown Defaults entry +in the +.Em sudoers +file or an unknown sudoOption in LDAP. +This flag is +.Em off +by default. +.It insults +If set, +.Nm sudo +will insult users when they enter an incorrect password. +This flag is +.Em @insults@ +by default. +.It log_allowed +If set, +.Nm +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 +.Em on +by default. +.Pp +This setting is only supported by version 1.8.29 or higher. +.It log_denied +If set, +.Nm +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 +.Em on +by default. +.Pp +This setting is only supported by version 1.8.29 or higher. +.It log_exit_status +If set, +.Nm +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 +.Em off +by default. +.Pp +This setting is only supported by version 1.9.8 or higher. +.It log_host +If set, the host name will be included in log entries written to +the file configured by the +.Em logfile +setting. +This flag is +.Em off +by default. +.It log_input +If set, +.Nm sudo +will run the command in a pseudo-terminal (if +.Nm sudo +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 +.Sx "I/O LOGGING" +section. +This flag is +.Em off +by default. +.It log_output +If set, +.Nm sudo +will run the command in a pseudo-terminal (if +.Nm sudo +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 +.Sx "I/O LOGGING" +section. +This flag is +.Em off +by default. +.It log_server_keepalive +If set, +.Nm sudo +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 +.Em ignore_iolog_errors +flag (I/O logging enabled) or the +.Em ignore_log_errors +flag (I/O logging disabled) is set. +This flag is +.Em on +by default. +.Pp +This setting is only supported by version 1.9.0 or higher. +.It log_server_verify +If set, the server certificate received during the TLS handshake +must be valid and it must contain either the server name (from +.Em log_servers ) +or its IP address. +If either of these conditions is not met, the TLS handshake will fail. +This flag is +.Em on +by default. +.Pp +This setting is only supported by version 1.9.0 or higher. +.It log_stderr +If set, +.Nm sudo +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 +.Em off +by default but is enabled when either the +.Em log_output +flag or the +.Dv LOG_OUTPUT +command tag is set. +.It log_stdin +If set, +.Nm sudo +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 +.Em off +by default but is enabled when either the +.Em log_input +flag or the +.Dv LOG_INPUT +command tag is set. +.It log_stdout +If set, +.Nm sudo +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 +.Em off +by default but is enabled when either the +.Em log_output +flag or the +.Dv LOG_OUTPUT +command tag is set. +.It log_subcmds +If set, +.Nm +will log when a command spawns a child process and executes a program +using the +.Xr execve 2 , +.Xr execl 3 , +.Xr execle 3 , +.Xr execlp 3 , +.Xr execv 3 , +.Xr execvp 3 , +.Xr execvpe 3 , +or +.Xr system 3 +library functions. +For example, if a shell is run by +.Nm sudo , +the individual commands run via the shell will be logged. +This flag is +.Em off +by default. +.Pp +The +.Em log_subcmds +flag uses the same underlying mechanism as the +.Em intercept +setting. +Some commands may not work properly when +.Em log_subcmds +is enabled, due to the way it intercepts sub-commands. +See +.Sx Preventing shell escapes +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 +.Xr seccomp 2 +filter mode. +.It log_ttyin +If set, +.Nm sudo +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 +.Em off +by default but is enabled when either the +.Em log_input +flag or the +.Dv LOG_INPUT +command tag is set. +If no terminal is present, for example when running a remote command using +.Xr ssh 1 , +this flag will have no effect. +.It log_ttyout +If set, +.Nm sudo +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 +.Em off +by default but is enabled when either the +.Em log_output +flag or the +.Dv LOG_OUTPUT +command tag is set. +If no terminal is present, for example when running a remote command using +.Xr ssh 1 , +this flag will have no effect. +.It log_year +If set, the four-digit year will be logged in the (non-syslog) +.Nm sudo +log file. +This flag is +.Em off +by default. +.It long_otp_prompt +When validating with a One Time Password (OTP) scheme such as +.Sy S/Key +or +.Sy OPIE , +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 +.Em @long_otp_prompt@ +by default. +.It mail_all_cmnds +Send mail to the +.Em mailto +user every time a user attempts to run a command via +.Nm sudo +(this includes +.Nm sudoedit ) . +No mail will be sent if the user runs +.Nm sudo +with the +.Fl l +or +.Fl v +option unless there is an authentication error and the +.Em mail_badpass +flag is also set. +This flag is +.Em off +by default. +.It mail_always +Send mail to the +.Em mailto +user every time a user runs +.Nm sudo . +This flag is +.Em off +by default. +.It mail_badpass +Send mail to the +.Em mailto +user if the user running +.Nm sudo +does not enter the correct password. +If the command the user is attempting to run is not permitted by +.Nm +and one of the +.Em mail_all_cmnds , +.Em mail_always , +.Em mail_no_host , +.Em mail_no_perms +or +.Em mail_no_user +flags are set, this flag will have no effect. +This flag is +.Em off +by default. +.It mail_no_host +If set, mail will be sent to the +.Em mailto +user if the invoking user exists in the +.Em sudoers +file, but is not allowed to run commands on the current host. +This flag is +.Em @mail_no_host@ +by default. +.It mail_no_perms +If set, mail will be sent to the +.Em mailto +user if the invoking user is allowed to use +.Nm sudo +but the command they are trying is not listed in their +.Em sudoers +file entry or is explicitly denied. +This flag is +.Em @mail_no_perms@ +by default. +.It mail_no_user +If set, mail will be sent to the +.Em mailto +user if the invoking user is not in the +.Em sudoers +file. +This flag is +.Em @mail_no_user@ +by default. +.It match_group_by_gid +By default, +.Nm +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 +.Em sudoers +file. +This works well on systems where the number of groups listed in the +.Em sudoers +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 +.Em sudoers +file is relatively small, it may be prohibitively expensive and +running commands via +.Nm sudo +may take longer than normal. +On such systems it may be faster to use the +.Em match_group_by_gid +flag to avoid resolving the user's group-IDs to group names. +In this case, +.Nm +must look up any group name listed in the +.Em sudoers +file and use the group-ID instead of the group name when determining +whether the user is a member of the group. +.Pp +If +.Em match_group_by_gid +is enabled, group database lookups performed by +.Nm +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 +.Pa /etc/group +file and the remote group database. +On such systems, enabling or disabling +.Em match_group_by_gid +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. +.Pp +The +.Em match_group_by_gid +flag has no effect when +.Em sudoers +data is stored in LDAP. +This flag is +.Em off +by default. +.Pp +This setting is only supported by version 1.8.18 or higher. +.It intercept +If set, all commands run via +.Nm sudo +will behave as if the +.Dv INTERCEPT +tag has been set, unless overridden by an +.Dv NOINTERCEPT +tag. +Some commands may not work properly when +.Em intercept +is enabled, due to the way it intercept sub-commands. +See the description of +.Dv INTERCEPT and NOINTERCEPT +above as well as the +.Sx Preventing shell escapes +section at the end of this manual. +This flag is +.Em off +by default. +.Pp +This setting is only supported by version 1.9.8 or higher +and is incompatible with SELinux RBAC support unless the system supports +.Xr seccomp 2 +filter mode. +.It intercept_allow_setid +On most systems, the dynamic loader will ignore +.Ev LD_PRELOAD +(or the equivalent) when running set-user-ID and set-group-ID +programs, effectively disabling intercept mode. +To prevent this from happening, +.Nm +will not permit a set-user-ID or set-group-ID program to be run in +intercept mode unless +.Em intercept_allow_setid +is enable. +This flag has no effect unless the +.Em intercept +flag is enabled or the +.Dv INTERCEPT +tag has been set for the command. +This flag is +.Em on +by default when the +.Em intercept_type +option is set to +.Em trace , +otherwise it default to +.Em off . +.Pp +This setting is only supported by version 1.9.8 or higher. +.It 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 +.Em intercept +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 +.Em intercept +flag is enabled or the +.Dv INTERCEPT +tag has been set for the command. +This flag is +.Em off +by default. +.Pp +This setting is only supported by version 1.9.8 or higher. +.It intercept_verify +If set, +.Nm sudo +will attempt to verify that a command run in intercept mode has +the expected path name, command line arguments and environment. +.Pp +The process will be stopped after +.Xr execve 2 +has completed but before the new command has had a chance to run. +To verify the command, +.Nm sudo +will read the command's path from +.Pa /proc/PID/exe , +the command line arguments and environment from the process's memory, +and compare them against the arguments that were passed to +.Xr execve 2 . +In the event of a mismatch, the command will be sent a +.Dv SIGKILL +signal and terminated. +.Pp +This can help prevent a time of check versus time of use issue with +intercept mode where the +.Xr execve 2 +arguments could be altered after the +.Nm +policy check. +The checks can only be performed if the +.Xr proc @mansectform@ +file system is available. +This flag has no effect unless the +.Em intercept +flag is enabled or the +.Dv INTERCEPT +tag has been set for the command and the +.Em intercept_type +option is set to +.Em trace . +.Pp +This setting is incompatible with programs that change their root directory via +.Xr chroot 2 . +If a program changes its root directory, path names will no longer match +those seen by the +.Nm sudo +parent process and sub-commands will be terminated before they have a chance +to run. +This flag is +.Em on +by default. +.Pp +This setting is only supported by version 1.9.12 or higher. +.It 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, +.Nm sudo +only matched the user name and domain for netgroups used in a +.Em User_List +and only matched the host name and domain for netgroups used in a +.Em Host_List . +This flag is +.Em off +by default. +.It noexec +If set, all commands run via +.Nm sudo +will behave as if the +.Dv NOEXEC +tag has been set, unless overridden by an +.Dv EXEC +tag. +See the description of +.Dv EXEC and NOEXEC +above as well as the +.Sx Preventing shell escapes +section at the end of this manual. +This flag is +.Em off +by default. +.It noninteractive_auth +If set, authentication will be attempted even in non-interactive mode +(when +.Nm sudo Ns 's +.Fl n +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 +.Em off +by default. +.Pp +This setting is only supported by version 1.9.10 or higher. +.It pam_acct_mgmt +On systems that use PAM for authentication, +.Nm sudo +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 +.Em on +by default. +.Pp +This setting is only supported by version 1.8.28 or higher. +.It pam_rhost +On systems that use PAM for authentication, +.Nm sudo +will set the PAM remote host value to the name of the local host +when the +.Em pam_rhost +flag is enabled. +On Linux systems, enabling +.Em pam_rhost +may result in DNS lookups of the local host name when PAM is initialized. +On Solaris versions prior to Solaris 8, +.Em pam_rhost +must be enabled if +.Em pam_ruser +is also enabled to avoid a crash in the Solaris PAM implementation. +.Pp +This flag is +.Em off +by default on systems other than Solaris. +.Pp +This setting is only supported by version 1.9.0 or higher. +.It pam_ruser +On systems that use PAM for authentication, +.Nm sudo +will set the PAM remote user value to the name of the user that invoked sudo +when the +.Em pam_ruser +flag is enabled. +This flag is +.Em on +by default. +.Pp +This setting is only supported by version 1.9.0 or higher. +.It pam_session +On systems that use PAM for authentication, +.Nm sudo +will create a new PAM session for the command to be run in. +Unless +.Nm sudo +is given the +.Fl i +or +.Fl s +options, PAM session modules are run with the +.Dq silent +flag enabled. +This prevents last login information from being displayed for every +command on some systems. +Disabling +.Em pam_session +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 +.Em pam_session , +.Em pam_setcred , +and +.Em use_pty +are disabled, +.Em log_servers +has not been set and I/O logging has not been configured, +.Nm sudo +will execute the command directly instead of running it as a child +process. +This flag is +.Em @pam_session@ +by default. +.Pp +This setting is only supported by version 1.8.7 or higher. +.It pam_setcred +On systems that use PAM for authentication, +.Nm sudo +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 +.Em pam_session , +.Em pam_setcred , +and +.Em use_pty +are disabled, +.Em log_servers +has not been set and I/O logging has not been configured, +.Nm sudo +will execute the command directly instead of running it as a child +process. +This flag is +.Em on +by default. +.Pp +This setting is only supported by version 1.8.8 or higher. +.It passprompt_override +If set, the prompt specified by +.Em passprompt +or the +.Ev SUDO_PROMPT +environment variable will always be used and will replace the +prompt provided by a PAM module or other authentication method. +This flag is +.Em off +by default. +.It path_info +Normally, +.Nm sudo +will tell the user when a command could not be +found in their +.Ev PATH +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 +.Ev PATH , +.Nm sudo +will tell the user that they are not allowed to run it, which can be confusing. +This flag is +.Em @path_info@ +by default. +.It preserve_groups +By default, +.Nm sudo +will initialize the group vector to the list of groups the target user is in. +When +.Em preserve_groups +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 +.Em off +by default. +.It pwfeedback +By default, +.Nm sudo +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 +.Nm sudo +has hung at this point. +When +.Em pwfeedback +is set, +.Nm sudo +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 +.Em off +by default. +.It requiretty +If set, +.Nm sudo +will only run when the user is logged in to a real tty. +When this flag is set, +.Nm sudo +can only be run from a login session and not via other means such as +.Xr cron @mansectsu@ +or cgi-bin scripts. +This flag is +.Em off +by default. +.It root_sudo +If set, +.Sy root +is allowed to run +.Nm sudo +too. +Disabling this prevents users from +.Dq chaining +.Nm sudo +commands to get a +.Sy root +shell by doing something like +.Ql sudo sudo /bin/sh . +Note, however, that turning off +.Em root_sudo +will also prevent +.Sy root +from running +.Nm sudoedit . +Disabling +.Em root_sudo +provides no real additional security; it exists purely for historical reasons. +This flag is +.Em @root_sudo@ +by default. +.It rootpw +If set, +.Nm sudo +will prompt for the +.Sy root +password instead of the password of the invoking user +when running a command or editing a file. +This flag is +.Em off +by default. +.It 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 +.Em Runas_List , +this option also allows the +.Sy ALL +alias to match unknown IDs. +This flag is +.Em off +by default. +.Pp +This setting is only supported by version 1.8.30 or higher. +Older versions of +.Nm sudo +always allowed matching of unknown user and group IDs. +.It runas_check_shell +If enabled, +.Nm sudo +will only run commands as a user whose shell appears in the +.Pa /etc/shells +file, even if the invoking user's +.Em Runas_List +would otherwise permit it. +If no +.Pa /etc/shells +file is present, a system-dependent list of built-in default shells is used. +On many operating systems, system users such as +.Dq bin , +do not have a valid shell and this flag can be used to prevent +commands from being run as those users. +This flag is +.Em off +by default. +.Pp +This setting is only supported by version 1.8.30 or higher. +.It runaspw +If set, +.Nm sudo +will prompt for the password of the user defined by the +.Em runas_default +option (defaults to +.Sy @runas_default@ ) +instead of the password of the invoking user +when running a command or editing a file. +This flag is +.Em off +by default. +.if \n(SL \{\ +.It 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 +.Em on +by default. +.\} +.It set_home +If enabled and +.Nm sudo +is invoked with the +.Fl s +option, the +.Ev HOME +environment variable will be set to the home directory of the target +user (which is the +.Em runas_default +user unless the +.Fl u +option is used). +This flag is largely obsolete and has no effect unless the +.Em env_reset +flag has been disabled or +.Ev HOME +is present in the +.Em env_keep +list, both of which are strongly discouraged. +This flag is +.Em off +by default. +.It set_logname +Normally, +.Nm sudo +will set the +.Ev LOGNAME +and +.Ev USER +environment variables to the name of the target user (the user specified by +.Em runas_default +unless the +.Fl u +option is given). +However, since some programs (including the RCS revision control system) use +.Ev LOGNAME +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 +.Em set_logname +option will have no effect +if the +.Em env_reset +option has not been disabled and the +.Em env_keep +list contains +.Ev LOGNAME +or +.Ev USER . +This flag is +.Em on +by default. +.It set_utmp +When enabled, +.Nm sudo +will create an entry in the utmp (or utmpx) file when a pseudo-terminal +is allocated. +A pseudo-terminal is allocated by +.Nm sudo +when it is running in a terminal and one or more of the +.Em log_input , +.Em log_output , +.Em log_stdin , +.Em log_stdout , +.Em log_stderr , +.Em log_ttyin , +.Em log_ttyout , +or +.Em use_pty +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 +.Em on +by default. +.It setenv +Allow the user to disable the +.Em env_reset +option from the command line via the +.Fl E +option. +Additionally, environment variables set via the command line are +not subject to the restrictions imposed by +.Em env_check , +.Em env_delete , +or +.Em env_keep . +As such, only trusted users should be allowed to set variables in this manner. +This flag is +.Em off +by default. +.It shell_noargs +If set and +.Nm sudo +is invoked with no arguments it acts as if the +.Fl s +option had been given. +That is, it runs a shell as +.Sy root +(the shell is determined by the +.Ev SHELL +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 +.Em off +by default. +.It stay_setuid +Normally, when +.Nm sudo +executes a command the real and effective user-IDs are set to the target +user +.Sy ( @runas_default@ +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 +.Nm sudo +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 +.Xr setreuid 2 +or +.Xr setresuid 2 +system call. +This flag is +.Em off +by default. +.It sudoedit_checkdir +If set, +.Nm sudoedit +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 +.Nm sudoedit +will refuse to edit a file located in a writable directory. +These restrictions are not enforced when +.Nm sudoedit +is run by +.Sy root . +On some systems, if all directory components of the path to be edited +are not readable by the target user, +.Nm sudoedit +will be unable to edit the file. +This flag is +.Em on +by default. +.Pp +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. +.It sudoedit_follow +By default, +.Nm sudoedit +will not follow symbolic links when opening files. +The +.Em sudoedit_follow +option can be enabled to allow +.Nm sudoedit +to open symbolic links. +It may be overridden on a per-command basis by the +.Dv FOLLOW +and +.Dv NOFOLLOW +tags. +This flag is +.Em off +by default. +.Pp +This setting is only supported by version 1.8.15 or higher. +.It syslog_pid +When logging via +.Xr syslog 3 , +include the process ID in the log entry. +This flag is +.Em off +by default. +.Pp +This setting is only supported by version 1.8.21 or higher. +.It targetpw +If set, +.Nm sudo +will prompt for the password of the user specified +by the +.Fl u +option (defaults to the value of +.Em runas_default ) +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 +.Fl u +option. +This flag is +.Em off +by default. +.It tty_tickets +If set, users must authenticate on a per-tty basis. +With this flag enabled, +.Nm sudo +will use a separate record in the time stamp file for each terminal. +If disabled, a single record is used for all login sessions. +.Pp +This option has been superseded by the +.Em timestamp_type +option. +.It umask_override +If set, +.Nm sudo +will set the umask as specified in the +.Em sudoers +file without modification. +This makes it possible to specify a umask in the +.Em sudoers +file that is more permissive than the user's own umask and matches +historical behavior. +If +.Em umask_override +is not set, +.Nm sudo +will set the umask to be the union of the user's umask and what is specified in +.Em sudoers . +This flag is +.Em @umask_override@ +by default. +.if \n(LC \{\ +.It use_loginclass +If set, +.Nm sudo +will apply the defaults specified for the target user's login class +if one exists. +Only available if +.Nm sudo +is configured with the +.Li --with-logincap +option. +This flag is +.Em off +by default. +.\} +.It use_netgroups +If set, netgroups (prefixed with +.Ql + ) , +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 +.Sy NETGROUP_BASE +directive is present in the +.Pa @ldap_conf@ +file. +If netgroups are not needed, this option can be disabled to reduce the +load on the LDAP server. +This flag is +.Em on +by default. +.It use_pty +If set, and +.Nm sudo +is running in a terminal, the command will be run in a new pseudo-terminal. +If the +.Nm sudo +process is not attached to a terminal, +.Em use_pty +has no effect. +.Pp +A malicious program run under +.Nm sudo +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 +.Em on +by default for +.Nm sudo +1.9.14 and above. +.It 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 +.Pa sudoers +file and on the command line, the smaller of the two timeouts will be used. +See the +.Em Timeout_Spec +section for a description of the timeout syntax. +This flag is +.Em off +by default. +.Pp +This setting is only supported by version 1.8.20 or higher. +.It utmp_runas +If set, +.Nm sudo +will store the name of the runas user when updating the utmp (or utmpx) file. +By default, +.Nm sudo +stores the name of the invoking user. +This flag is +.Em off +by default. +.It visiblepw +By default, +.Nm sudo +will refuse to run if the user must enter a password but it is not +possible to disable echo on the terminal. +If the +.Em visiblepw +flag is set, +.Nm sudo +will prompt for a password even when it would be visible on the screen. +This makes it possible to run things like +.Ql ssh somehost sudo ls +since by default, +.Xr ssh 1 +does +not allocate a tty when running a command. +This flag is +.Em off +by default. +.El +.Pp +.Sy Integers : +.Bl -tag -width 16n +.It closefrom +Before it executes a command, +.Nm sudo +will close all open file descriptors other than standard input, +standard output, and standard error (file descriptors 0-2). +The +.Em closefrom +option can be used to specify a different file descriptor at which +to start closing. +The default is 3. +.It command_timeout +The maximum amount of time a command is allowed to run before +it is terminated. +See the +.Em Timeout_Spec +section for a description of the timeout syntax. +.Pp +This setting is only supported by version 1.8.20 or higher. +.It log_server_timeout +The maximum amount of time to wait when connecting to a log server +or waiting for a server response. +See the +.Em Timeout_Spec +section for a description of the timeout syntax. +The default value is 30 seconds. +.Pp +This setting is only supported by version 1.9.0 or higher. +.It maxseq +The maximum sequence number that will be substituted for the +.Ql %{seq} +escape in the I/O log file (see the +.Em iolog_dir +description below for more information). +While the value substituted for +.Ql %{seq} +is in base 36, +.Em maxseq +itself should be expressed in decimal. +Values larger than 2176782336 (which corresponds to the +base 36 sequence number +.Dq ZZZZZZ ) +will be silently truncated to 2176782336. +The default value is 2176782336. +.Pp +Once the local sequence number reaches the value of +.Em maxseq , +it will +.Dq roll over +to zero, after which +.Nm +will truncate and re-use any existing I/O log path names. +.Pp +This setting is only supported by version 1.8.7 or higher. +.It passwd_tries +The number of tries a user gets to enter his/her password before +.Nm sudo +logs the failure and exits. +The default is @passwd_tries@. +.It syslog_maxlen +On many systems, +.Xr 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, +.Nm +creates log messages up to 980 bytes which corresponds to the +historic +.Bx +syslog implementation which used a 1024 byte buffer +to store the message, date, hostname, and program name. +To prevent syslog messages from being truncated, +.Nm +will split up log messages that are larger than +.Em syslog_maxlen +bytes. +When a message is split, additional parts will include the string +.Dq Pq command continued +after the user name and before the continued command line arguments. +.Pp +This setting is only supported by version 1.8.19 or higher. +.El +.Pp +.Sy Integers that can be used in a boolean context : +.Bl -tag -width 16n +.It 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). +.It passwd_timeout +Number of minutes before the +.Nm sudo +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@. +.It timestamp_timeout +Number of minutes that can elapse before +.Nm sudo +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 +.Ql sudo -v +and +.Ql sudo -k +respectively. +.It umask +File mode creation mask to use when running the command. +Negate this option or set it to 0777 to prevent +.Nm +from changing the umask. +Unless the +.Em umask_override +flag is set, the actual umask will be the union of the +user's umask and the value of the +.Em umask +setting, which defaults to @sudo_umask@. +This guarantees that +.Nm sudo +never lowers the umask when running a command. +.Pp +If +.Em umask +is explicitly set in +.Em sudoers , +it will override any umask setting in PAM or login.conf. +If +.Em umask +is not set in +.Em sudoers , +the umask specified by PAM or login.conf will take precedence. +The umask setting in PAM is not used for +.Nm sudoedit , +which does not create a new PAM session. +.El +.Pp +.Sy Strings : +.Bl -tag -width 16n +.if \n(AA \{\ +.It apparmor_profile +The default AppArmor profile to transition into when executing the +command. +The default +.Em apparmor_profile +can be overridden for individual +.Em sudoers +entries by specifying the +.Dv APPARMOR_PROFILE +option. +This option is only available when sudo is built with AppArmor +support. +.\} +.It authfail_message +Message that is displayed after a user fails to authenticate. +The message may include the +.Ql %d +escape which will expand to the number of failed password attempts. +If set, it overrides the default message, +.Dq %d incorrect password attempt(s) . +.It badpass_message +Message that is displayed if a user enters an incorrect password. +The default is +.Dq @badpass_message@ +unless insults are enabled. +.It editor +A colon +.Pq Ql :\& +separated list of editor path names used by +.Nm sudoedit +and +.Nm visudo . +For +.Nm sudoedit , +this list is used to find an editor when none of the +.Ev SUDO_EDITOR , +.Ev VISUAL +or +.Ev EDITOR +environment variables are set to an editor that exists and is executable. +For +.Nm visudo , +it is used as a white list of allowed editors; +.Nm visudo +will choose the editor that matches the user's +.Ev SUDO_EDITOR , +.Ev VISUAL +or +.Ev EDITOR +environment variable if possible, or the first editor in the +list that exists and is executable if not. +Unless invoked as +.Nm sudoedit , +.Nm sudo +does not preserve the +.Ev SUDO_EDITOR , +.Ev VISUAL +or +.Ev EDITOR +environment variables unless they are present in the +.Em env_keep +list or the +.Em env_reset +option is disabled. +The default is +.Pa @editor@ . +.It intercept_type +The underlying mechanism used by the +.Em intercept +and +.Em log_subcmds +options. +It has the following possible values: +.Bl -tag -width 6n +.It dso +Preload a dynamic shared object (shared library) that intercepts the +.Xr execve 2 , +.Xr execl 3 , +.Xr execle 3 , +.Xr execlp 3 , +.Xr execv 3 , +.Xr execvp 3 , +.Xr execvpe 3 , +and +.Xr system 3 +library functions. +A value of +.Em dso +is incompatible with +.Nm sudo Ns 's +SELinux RBAC support. +.It trace +Use +.Xr ptrace 2 +to intercept the +.Xr execve 2 +system call. +This is only supported on Linux systems where +.Xr seccomp 2 +filtering is enabled. +If the +.Pa /proc/sys/kernel/seccomp/actions_avail +file is missing or does not contain a +.Dq trap +element, setting +.Em intercept_type +to +.Em trace +will have no effect and +.Em dso +will be used instead. +.El +.Pp +The default is to use +.Em trace +if it is supported by the system and +.Em dso +if it is not. +.It iolog_dir +The top-level directory to use when constructing the path name for +the input/output log directory. +Only used if the +.Em log_input +or +.Em log_output +options are enabled or when the +.Dv LOG_INPUT +or +.Dv LOG_OUTPUT +tags are present for a command. +The session sequence number, if any, is stored in the directory. +The default is +.Pa @iolog_dir@ . +.Pp +The following percent +.Pq Ql % +escape sequences are supported: +.Bl -tag -width 4n +.It %{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., +.Pa 01/00/A5 +.It %{user} +expanded to the invoking user's login name +.It %{group} +expanded to the name of the invoking user's real group-ID +.It %{runas_user} +expanded to the login name of the user the command will +be run as (e.g., +.Sy root ) +.It %{runas_group} +expanded to the group name of the user the command will +be run as (e.g., +.Sy wheel ) +.It %{hostname} +expanded to the local host name without the domain name +.It %{command} +expanded to the base name of the command being run +.El +.Pp +In addition, any escape sequences supported by the system's +.Xr strftime 3 +function will be expanded. +.Pp +To include a literal +.Ql % +character, the string +.Ql %% +should be used. +.Pp +Any path name separator characters +.Pq Ql / +present in the user, group or host name will be replaced with an underbar +.Pq Ql _ +during expansion. +.It iolog_file +The path name, relative to +.Em iolog_dir , +in which to store input/output logs when the +.Em log_input +or +.Em log_output +options are enabled or when the +.Dv LOG_INPUT +or +.Dv LOG_OUTPUT +tags are present for a command. +.Em iolog_file +may contain directory components. +The default is +.Ql %{seq} . +.Pp +See the +.Em iolog_dir +option above for a list of supported percent +.Pq Ql % +escape sequences. +.Pp +In addition to the escape sequences, path names that end in six or +more +.Em X Ns s +will have the +.Em X Ns s +replaced with a unique combination of digits and letters, similar to the +.Xr mktemp 3 +function. +.Pp +If the path created by concatenating +.Em iolog_dir +and +.Em iolog_file +already exists, the existing I/O log file will be truncated and +overwritten unless +.Em iolog_file +ends in six or +more +.Em X Ns s . +.It iolog_flush +If set, +.Nm sudo +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 +.Em off +by default. +.Pp +This setting is only supported by version 1.8.20 or higher. +.It iolog_group +The group name to look up when setting the group-ID on new I/O log +files and directories. +If +.Em iolog_group +is not set, +the primary group-ID of the user specified by +.Em iolog_user +is used. +If neither +.Em iolog_group +nor +.Em iolog_user +are set, I/O log files and directories are created with group-ID 0. +.Pp +This setting is only supported by version 1.8.19 or higher. +.It 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 +.Em iolog_mode . +Defaults to 0600 (read and write by user only). +.Pp +This setting is only supported by version 1.8.19 or higher. +.It iolog_user +The user name to look up when setting the user and group-IDs on new +I/O log files and directories. +If +.Em iolog_group +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. +.Pp +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 +.Nm +does not write to the log files as user-ID 0, which is usually +not permitted by NFS. +.Pp +This setting is only supported by version 1.8.19 or higher. +.It lecture_status_dir +The directory in which +.Nm sudo +stores per-user lecture status files. +Once a user has received the lecture, a zero-length file is +created in this directory so that +.Nm sudo +will not lecture the user again. +This directory should +.Em not +be cleared when the system reboots. +The default is +.Pa @vardir@/lectured . +.if \n(PS \{\ +.It 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 +.Em sudoers . +This option is only available if +.Nm +is built on Solaris 10 or higher. +.\} +.It 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 +.Em log_servers +is set and the remote log server is secured with TLS. +.Pp +This setting is only supported by version 1.9.0 or higher. +.It log_server_peer_cert +The path to the +.Nm sudo +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 +.Nm sudo_logsrvd , +client certificate validation is controlled by the +.Em tls_checkpeer +option, which defaults to +.Em false . +.Pp +This setting is only supported by version 1.9.0 or higher. +.It log_server_peer_key +The path to the +.Nm sudo +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 +.Nm sudo_logsrvd , +client certificate validation is controlled by the +.Em tls_checkpeer +flag, which defaults to +.Em false . +.Pp +This setting is only supported by version 1.9.0 or higher. +.It mailsub +Subject of the mail sent to the +.Em mailto +user. +The escape +.Ql %h +will expand to the host name of the machine. +Default is +.Dq @mailsub@ . +.It noexec_file +As of +.Nm sudo +version 1.8.1 this option is no longer supported. +The path to the noexec file should now be set in the +.Xr sudo.conf @mansectform@ +file. +.It pam_askpass_service +On systems that use PAM for authentication, this is the service +name used when the +.Fl A +option is specified. +The default value is either +.Ql sudo +or +.Ql @pam_login_service@ , +depending on whether or not the +.Fl i +option is also specified. +See the description of +.Em pam_service +for more information. +.Pp +This setting is only supported by version 1.9.9 or higher. +.It pam_login_service +On systems that use PAM for authentication, this is the service +name used when the +.Fl i +option is specified. +The default value is +.Ql @pam_login_service@ . +See the description of +.Em pam_service +for more information. +.Pp +This setting is only supported by version 1.8.8 or higher. +.It 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 +.Pa pam.conf +file or a file in the +.Pa /etc/pam.d +directory. +The default value is +.Ql sudo . +.Pp +This setting is only supported by version 1.8.8 or higher. +.It passprompt +The default prompt to use when asking for a password; can be overridden via the +.Fl p +option or the +.Ev SUDO_PROMPT +environment variable. +The following percent +.Pq Ql % +escape sequences are supported: +.Bl -tag -width 4n +.It %H +expanded to the local host name including the domain name +(only if the machine's host name is fully qualified or the +.Em fqdn +option is set) +.It %h +expanded to the local host name without the domain name +.It %p +expanded to the user whose password is being asked for (respects the +.Em rootpw , +.Em targetpw +and +.Em runaspw +flags in +.Em sudoers ) +.It \&%U +expanded to the login name of the user the command will +be run as (defaults to +.Sy @runas_default@ ) +.It %u +expanded to the invoking user's login name +.It %% +two consecutive +.Ql % +characters are collapsed into a single +.Ql % +character +.El +.Pp +On systems that use PAM for authentication, +.Em passprompt +will only be used if the prompt provided by the PAM module matches the string +.Dq "Password: " +or +.Dq "username's Password: " . +This ensures that the +.Em passprompt +setting does not interfere with challenge-response style authentication. +The +.Em passprompt_override +flag can be used to change this behavior. +.Pp +The default value is +.Ql "@passprompt@" . +.if \n(PS \{\ +.It 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 +.Em privs +option is specified but the +.Em limitprivs +option is not, the limit privileges of the executing process is set to +.Em privs . +The default privileges may be overridden on a per-command basis in +.Em sudoers . +This option is only available if +.Nm +is built on Solaris 10 or higher. +.\} +.if \n(SL \{\ +.It 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 +.Em sudoers +file or via command line options. +This option is only available when +.Nm sudo +is built with SELinux support. +.\} +.It runas_default +The default user to run commands as if the +.Fl u +option is not specified on the command line. +This defaults to +.Sy @runas_default@ . +.It 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 +.Ql C . +.It timestamp_type +.Nm +uses per-user time stamp files for credential caching. +The +.Em timestamp_type +option can be used to specify the type of time stamp record used. +It has the following possible values: +.Bl -tag -width 6n +.It 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 +.Nm sudo +is used multiple times in a pipeline, but this does not affect authentication. +.It 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 +.Em timestamp_timeout +minutes (@timeout@ by default). +Commands run via +.Nm sudo +with a different parent process ID, for example from a shell script, +will be authenticated separately. +.It 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 +.Em ppid . +Commands run from the same terminal will not require a password for +.Em timestamp_timeout +minutes (@timeout@ by default). +.It 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 +.Em ppid . +Negative +.Em timestamp_timeout +values are not supported and positive values are limited to a maximum +of 60 minutes. +This is currently only supported on +.Ox . +.El +.Pp +The default value is +.Em @timestamp_type@ . +.Pp +This setting is only supported by version 1.8.21 or higher. +.It timestampdir +The directory in which +.Nm sudo +stores its time stamp files. +This directory should be cleared when the system reboots. +The default is +.Pa @rundir@/ts . +.It timestampowner +The owner of the lecture status directory, time stamp directory and all +files stored therein. +The default is +.Sy root . +.if \n(SL \{\ +.It 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 +.Em sudoers +file or via command line options. +This option is only available when +.Nm sudo +is built with SELinux support. +.\} +.El +.Pp +.Sy Strings that can be used in a boolean context : +.Bl -tag -width 12n +.It admin_flag +The +.Em admin_flag +option specifies the path to a file that is created the first time +a user that is a member of the +.Em sudo +or +.Em admin +groups runs +.Nm sudo . +Only available if +.Nm sudo +is configured with the +.Li --enable-admin-flag +option. +The default value is +.Pa ~/.sudo_as_admin_successful . +.It env_file +The +.Em env_file +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 +.Ql VARIABLE=value +or +.Ql export VARIABLE=value . +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 +.Nm sudo +environment restrictions such as +.Em env_keep +and +.Em env_check . +.It exempt_group +Users in this group are exempt from password and PATH requirements. +The group name specified should not include a +.Ql % +prefix. +This is not set by default. +.It fdexec +Determines whether +.Nm sudo +will execute a command by its path or by an open file descriptor. +It has the following possible values: +.Bl -tag -width 6n +.It always +Always execute by file descriptor. +.It never +Never execute by file descriptor. +.It digest_only +Only execute by file descriptor if the command has an associated digest +in the +.Em sudoers +file. +.El +.Pp +The default value is +.Em digest_only . +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. +.Pp +.Em fdexec +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, +.Pa /dev/fd/4 +on Solaris and +.Pa /proc/self/fd/4 +on Linux. +A workaround is to use the +.Dv SUDO_COMMAND +environment variable instead. +.Pp +The +.Em fdexec +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 +.Sy ALL +alias. +.Pp +This setting is only supported by version 1.8.20 or higher. +If the operating system does not support the +.Xr fexecve 2 +system call, this setting has no effect. +.It group_plugin +A string containing a +.Nm +group plugin with optional arguments. +The string should consist of the plugin +path, either fully-qualified or relative to the +.Pa @plugindir@ +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 +.Pq \&"" . +.Pp +On 64-bit systems, if the plugin is present but cannot be loaded, +.Nm +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 +.Dq lib , +.Nm +will create a fallback path by appending +.Dq /64 +to the directory name; +.Pa @prefix@/lib/group_plugin.so +becomes +.Pa @prefix@/lib/64/group_plugin.so . +On Linux, a directory ending in +.Dq lib +will be transformed to +.Dq lib64 +as the fallback path; +.Pa @prefix@/lib/group_plugin.so +becomes +.Pa @prefix@/lib64/group_plugin.so . +On all other systems, the fallback path is generated by adding a +.Dq 64 +before the file extension; +.Pa group_plugin.so +becomes +.Pa group_plugin64.so . +.Pp +On AIX systems, the plugin may be either a shared object +ending in +.Ql .so +or an archive file containing a shared object ending in +.Ql .a +with the name of the shared object in parentheses at the end. +.Pp +For more information see +.Sx "GROUP PROVIDER PLUGINS" . +.It lecture +This option controls when a short lecture will be printed along with +the password prompt. +It has the following possible values: +.Bl -tag -width 6n +.It always +Always lecture the user. +.It never +Never lecture the user. +.It once +Only lecture the user the first time they run +.Nm sudo . +.El +.Pp +If no value is specified, a value of +.Em once +is implied. +Negating the option results in a value of +.Em never +being used. +The default value is +.Em @lecture@ . +.It lecture_file +Path to a file containing an alternate +.Nm sudo +lecture that will be used in place of the standard lecture if the named +file exists. +By default, +.Nm sudo +uses a built-in lecture. +.It listpw +This option controls when a password will be required when a user runs +.Nm sudo +with the +.Fl l +option. +It has the following possible values: +.Bl -tag -width 4n +.It all +All the user's +.Em sudoers +file entries for the current host must have +the +.Dv NOPASSWD +flag set to avoid entering a password. +.It always +The user must always enter a password to use the +.Fl l +option. +.It any +At least one of the user's +.Em sudoers +file entries for the current host +must have the +.Dv NOPASSWD +flag set to avoid entering a password. +.It never +The user need never enter a password to use the +.Fl l +option. +.El +.Pp +If no value is specified, a value of +.Em any +is implied. +Negating the option results in a value of +.Em never +being used. +The default value is +.Em any . +.It log_format +The event log format. +Supported log formats are: +.Bl -tag -width 4n +.It 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 +.Em syslog +may be truncated. +.It sudo +Traditional sudo-style logs, see +.Sx "EVENT LOGGING" +for a description of the log file format. +.El +.Pp +This setting affects logs sent via +.Xr syslog 3 +as well as the file specified by the +.Em logfile +setting, if any. +The default value is +.Em sudo . +.It logfile +Path to the +.Nm sudo +log file (not the syslog log file). +Setting a path turns on logging to a file; +negating this option turns it off. +By default, +.Nm sudo +logs via syslog. +.It mailerflags +Flags to use when invoking mailer. +Defaults to +.Fl t . +.It mailerpath +Path to mail program used to send warning mail (negate to prevent +.Nm sudo +from sending mail). +Defaults to the path to sendmail found at configure time. +.It mailfrom +Address to use for the +.Dq from +address when sending warning and error mail. +The address should be enclosed in double quotes +.Pq \&"" +to protect against +.Nm sudo +interpreting the +.Ql @ +sign. +Defaults to the name of the user running +.Nm sudo . +.It mailto +Address to send warning and error mail to (negate to prevent +.Nm sudo +from sending mail). +The address should be enclosed in double quotes +.Pq \&"" +to protect against +.Nm sudo +interpreting the +.Ql @ +sign. +Defaults to @mailto@. +.It rlimit_as +The maximum size to which the process's address space may grow (in bytes), +if supported by the operating system. +See +.Sx "Resource limits" +for more information. +.It rlimit_core +The largest size core dump file that may be created (in bytes). +See +.Sx "Resource limits" +for more information. +Defaults to 0 (no core dump created). +.It rlimit_cpu +The maximum amount of CPU time that the process may use (in seconds). +See +.Sx "Resource limits" +for more information. +.It rlimit_data +The maximum size of the data segment for the process (in bytes). +See +.Sx "Resource limits" +for more information. +.It rlimit_fsize +The largest size file that the process may create (in bytes). +See +.Sx "Resource limits" +for more information. +.It rlimit_locks +The maximum number of locks that the process may establish, +if supported by the operating system. +See +.Sx "Resource limits" +for more information. +.It rlimit_memlock +The maximum size that the process may lock in memory (in bytes), +if supported by the operating system. +See +.Sx "Resource limits" +for more information. +.It rlimit_nofile +The maximum number of files that the process may have open. +See +.Sx "Resource limits" +for more information. +.It rlimit_nproc +The maximum number of processes that the user may run simultaneously. +See +.Sx "Resource limits" +for more information. +.It rlimit_rss +The maximum size to which the process's resident set size may grow (in bytes). +See +.Sx "Resource limits" +for more information. +.It rlimit_stack +The maximum size to which the process's stack may grow (in bytes). +See +.Sx "Resource limits" +for more information. +.It restricted_env_file +The +.Em restricted_env_file +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 +.Ql VARIABLE=value +or +.Ql export VARIABLE=value . +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 +.Em env_file , +the file's contents are not trusted and are processed in a manner +similar to that of the invoking user's environment. +If +.Em env_reset +is enabled, variables in the file will only be added if they are +matched by either the +.Em env_check +or +.Em env_keep +list. +If +.Em env_reset +is disabled, variables in the file are added as long as they +are not matched by the +.Em env_delete +list. +In either case, the contents of +.Em restricted_env_file +are processed before the contents of +.Em env_file . +.It runchroot +If set, +.Nm sudo +will use this value for the root directory when running a command. +The special value +.Dq * +will allow the user to specify the root directory via +.Nm sudo Ns 's +.Fl R +option. +See the +.Sx Chroot_Spec +section for more details. +.Pp +It is only possible to use +.Em runchroot +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 +.Em Cmnd_Spec +that includes a +.Em Chroot_Spec . +.Pp +This setting is only supported by version 1.9.3 or higher. +.It runcwd +If set, +.Nm sudo +will use this value for the working directory when running a command. +The special value +.Dq * +will allow the user to specify the working directory via +.Nm sudo Ns 's +.Fl D +option. +See the +.Sx Chdir_Spec +section for more details. +.Pp +This setting is only supported by version 1.9.3 or higher. +.It secure_path +If set, +.Nm sudo +will use this value in place of the user's +.Ev PATH +environment variable. +This option can be used to reset the +.Ev PATH +to a known good value that contains directories for system administrator +commands such as +.Pa /usr/sbin . +.Pp +Users in the group specified by the +.Em exempt_group +option are not affected by +.Em secure_path . +This option is @secure_path@ by default. +.It syslog +Syslog facility if syslog is being used for logging (negate to +disable syslog logging). +Defaults to @logfac@. +.Pp +The following syslog facilities are supported: +.Sy authpriv +(if your +OS supports it), +.Sy auth , +.Sy daemon , +.Sy user , +.Sy local0 , +.Sy local1 , +.Sy local2 , +.Sy local3 , +.Sy local4 , +.Sy local5 , +.Sy local6 , +and +.Sy local7 . +.It syslog_badpri +Syslog priority to use when the user is not allowed to run a command or +when authentication is unsuccessful. +Defaults to @badpri@. +.Pp +The following syslog priorities are supported: +.Sy alert , +.Sy crit , +.Sy debug , +.Sy emerg , +.Sy err , +.Sy info , +.Sy notice , +.Sy warning , +and +.Sy none . +Negating the option or setting it to a value of +.Sy none +will disable logging of unsuccessful commands. +.It syslog_goodpri +Syslog priority to use when the user is allowed to run a command and +authentication is successful. +Defaults to @goodpri@. +.Pp +See +.Em syslog_badpri +for the list of supported syslog priorities. +Negating the option or setting it to a value of +.Sy none +will disable logging of successful commands. +.It verifypw +This option controls when a password will be required when a user runs +.Nm sudo +with the +.Fl v +option. +It has the following possible values: +.Bl -tag -width 6n +.It all +All the user's +.Em sudoers +file entries for the current host must have the +.Dv NOPASSWD +flag set to avoid entering a password. +.It always +The user must always enter a password to use the +.Fl v +option. +.It any +At least one of the user's +.Em sudoers +file entries for the current host must have the +.Dv NOPASSWD +flag set to avoid entering a password. +.It never +The user need never enter a password to use the +.Fl v +option. +.El +.Pp +If no value is specified, a value of +.Em all +is implied. +Negating the option results in a value of +.Em never +being used. +The default value is +.Em all . +.El +.Pp +.Sy Lists that can be used in a boolean context : +.Bl -tag -width 16n +.It env_check +Environment variables to be removed from the user's environment +unless they are considered +.Dq safe . +For all variables except +.Ev TZ , +.Dq safe +means that the variable's value does not contain any +.Ql % +or +.Ql / +characters. +This can be used to guard against printf-style format vulnerabilities +in poorly-written programs. +The +.Ev TZ +variable is considered unsafe if any of the following are true: +.Bl -bullet -width 1n +.It +It consists of a fully-qualified path name, +optionally prefixed with a colon +.Pq Ql :\& , +that does not match the location of the +.Pa zoneinfo +directory. +.It +It contains a +.Pa .. +path element. +.It +It contains white space or non-printable characters. +.It +It is longer than the value of +.Dv PATH_MAX . +.El +.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 +.Ql = , +.Ql += , +.Ql -= , +and +.Ql \&! +operators respectively. +Regardless of whether the +.Em env_reset +option is enabled or disabled, variables specified by +.Em env_check +will be preserved in the environment if they pass the aforementioned check. +The global list of environment variables to check is displayed when +.Nm sudo +is run by +.Sy root +with the +.Fl V +option. +.It env_delete +Environment variables to be removed from the user's environment when the +.Em env_reset +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 +.Ql = , +.Ql += , +.Ql -= , +and +.Ql \&! +operators respectively. +The global list of environment variables to remove is displayed when +.Nm sudo +is run by +.Sy root +with the +.Fl V +option. +Many operating systems will remove potentially dangerous variables +from the environment of any set-user-ID process (such as +.Nm sudo ) . +.It env_keep +Environment variables to be preserved in the user's environment when the +.Em env_reset +option is in effect. +This allows fine-grained control over the environment +.Nm sudo Ns -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 +.Ql = , +.Ql += , +.Ql -= , +and +.Ql \&! +operators respectively. +The global list of variables to keep +is displayed when +.Nm sudo +is run by +.Sy root +with the +.Fl V +option. +.Pp +Preserving the +.Ev HOME +environment variable has security implications since many programs use it +when searching for configuration or data files. +Adding +.Ev HOME +to +.Em env_keep +may enable a user to run unrestricted commands via +.Nm sudo +and is strongly discouraged. +Users wishing to edit files with +.Nm sudo +should run +.Nm sudoedit +(or +.Nm sudo Fl e ) +to get their accustomed editor configuration instead of +invoking the editor directly. +.It 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 +.Nm sudo_logsrvd +or another service that implements the protocol described by +.Xr sudo_logsrv.proto @mansectform@ . +.Pp +Server addresses should be of the form +.Dq host Ns Oo : Ns port Oc Ns Op (tls) . +The host portion may be a host name, an IPv4 address, or an IPv6 address +in square brackets. +.Pp +If the optional +.Em tls +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. +.Pp +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. +.Pp +When +.Em log_servers +is set, event log data will be logged both locally (see the +.Em syslog +and +.Em log_file +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 +.Em ignore_iolog_errors +flag (I/O logging enabled) or the +.Em ignore_log_errors +flag (I/O logging disabled) is set. +Likewise, if the connection to the log server is interrupted while +.Nm sudo +is running, the command will be terminated unless the +.Em ignore_iolog_errors +flag (I/O logging enabled) or the +.Em ignore_log_errors +flag (I/O logging disabled) is set. +.Pp +This setting is only supported by version 1.9.0 or higher. +.It 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 +.Dq (?i) , +it will be matched in a case-insensitive manner. +Each regular expression is limited to 1024 characters. +This option is only used when +.Em log_passwords +has been disabled. +The default value is +.Dq [Pp]assword[: ]* +.Pp +This setting is only supported by version 1.9.10 or higher. +.El +.Sh GROUP PROVIDER PLUGINS +The +.Nm +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 +.Em nonunix_group +syntax described earlier. +.Pp +Group provider plugins are specified via the +.Em group_plugin +setting. +The argument to +.Em group_plugin +should consist of the plugin path, either fully-qualified or relative to the +.Pa @plugindir@ +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 +.Pq \&"" . +.Pp +The following group provider plugins are installed by default: +.Bl -tag -width 4n +.It group_file +The +.Em group_file +plugin supports an alternate group file that uses the same syntax as the +.Pa /etc/group +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 +.Pa /etc/sudo-group : +.Bd -literal +Defaults group_plugin="group_file.so /etc/sudo-group" +.Ed +.It system_group +The +.Em system_group +plugin supports group lookups via the standard C library functions +.Xr getgrnam 3 +and +.Xr 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: +.Bd -literal +Defaults group_plugin=system_group.so +.Ed +.El +.Pp +The group provider plugin API is described in detail in +.Xr sudo_plugin @mansectform@ . +.Sh EVENT LOGGING +.Nm +can log events in either JSON or +.Em sudo +format, +this section describes the +.Em sudo +log format. +Depending on +.Em sudoers +configuration, +.Nm +can log events via +.Xr 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 +.Ql # +character. +For example, a horizontal tab is stored as +.Ql #011 +and an embedded carriage return is stored as +.Ql #015 . +In addition, space characters in the command path are stored as +.Ql #040 . +Command line arguments that contain spaces are enclosed in single quotes +.Pq '' . +This makes it possible to distinguish multiple command line arguments +from a single argument that contains spaces. +Literal single quotes and backslash characters +.Pq Ql \e +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): +.Bd -literal -offset 4n +date hostname progname: username : TTY=ttyname ; CHROOT=chroot ; \e + PWD=cwd ; USER=runasuser ; GROUP=runasgroup ; TSID=logid ; \e + ENV=env_vars COMMAND=command +.Ed +.Pp +Where the fields are as follows: +.Bl -tag -width 12n +.It date +The date the command was run. +Typically, this is in the format +.Dq MMM, DD, HH:MM:SS . +If logging via +.Xr syslog 3 , +the actual date format is controlled by the syslog daemon. +If logging to a file and the +.Em log_year +option is enabled, +the date will also include the year. +.It hostname +The name of the host +.Nm sudo +was run on. +This field is only present when logging via +.Xr syslog 3 . +.It progname +The name of the program, usually +.Em sudo +or +.Em sudoedit . +This field is only present when logging via +.Xr syslog 3 . +.It username +The login name of the user who ran +.Nm sudo . +.It ttyname +The short name of the terminal (e.g., +.Dq console , +.Dq tty01 , +or +.Dq pts/0 ) +.Nm sudo +was run on, or +.Dq unknown +if there was no terminal present. +.It chroot +The root directory that the command was run in, if one was specified. +.It cwd +The current working directory that +.Nm sudo +was run in. +.It runasuser +The user the command was run as. +.It runasgroup +The group the command was run as if one was specified on the command line. +.It logid +An I/O log identifier that can be used to replay the command's output. +This is only present when the +.Em log_input +or +.Em log_output +option is enabled. +.It env_vars +A list of environment variables specified on the command line, +if specified. +.It command +The actual command that was executed, including any command line arguments. +.El +.Pp +Messages are logged using the locale specified by +.Em sudoers_locale , +which defaults to the +.Ql C +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: +.Bl -tag -width 4 +.It user NOT in sudoers +The user is not listed in the +.Em sudoers +file. +.It user NOT authorized on host +The user is listed in the +.Em sudoers +file but is not allowed to run commands on the host. +.It command not allowed +The user is listed in the +.Em sudoers +file for the host but they are not allowed to run the specified command. +.It 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 +.Em passwd_tries +option. +.It a password is required +The +.Fl n +option was specified but a password was required. +.It 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 +.Em sudoers . +.El +.Ss Error log entries +If an error occurs, +.Nm +will log a message and, in most cases, send a message to the +administrator via email. +Possible errors include: +.Bl -tag -width 4 +.It parse error in @sysconfdir@/sudoers near line N +.Nm +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. +.It problem with defaults entries +The +.Em sudoers +file contains one or more unknown Defaults settings. +This does not prevent +.Nm sudo +from running, but the +.Em sudoers +file should be checked using +.Nm visudo . +.It timestamp owner (username): \&No such user +The time stamp directory owner, as specified by the +.Em timestampowner +setting, could not be found in the password database. +.It unable to open/read @sysconfdir@/sudoers +The +.Em sudoers +file could not be opened for reading. +This can happen when the +.Em sudoers +file is located on a remote file system that maps user-ID 0 to +a different value. +Normally, +.Nm +tries to open the +.Em sudoers +file using group permissions to avoid this problem. +Consider either changing the ownership of +.Pa @sysconfdir@/sudoers +or adding an argument like +.Dq sudoers_uid=N +(where +.Sq N +is the user-ID that owns the +.Em sudoers +file) to the end of the +.Nm +.Em Plugin +line in the +.Xr sudo.conf @mansectform@ +file. +.It unable to open @sysconfdir@/sudoers +The +.Pa @sysconfdir@/sudoers +file is missing. +.It @sysconfdir@/sudoers is not a regular file +The +.Pa @sysconfdir@/sudoers +file exists but is not a regular file or symbolic link. +.It @sysconfdir@/sudoers is owned by uid N, should be 0 +The +.Em sudoers +file has the wrong owner. +If you wish to change the +.Em sudoers +file owner, add +.Dq sudoers_uid=N +(where +.Sq N +is the user-ID that owns the +.Em sudoers +file) to the +.Nm +.Em Plugin +line in the +.Xr sudo.conf @mansectform@ +file. +.It @sysconfdir@/sudoers is world writable +The permissions on the +.Em sudoers +file allow all users to write to it. +The +.Em sudoers +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 +.Dq sudoers_mode +option to the +.Nm +.Em Plugin +line in the +.Xr sudo.conf @mansectform@ +file. +.It @sysconfdir@/sudoers is owned by gid N, should be 1 +The +.Em sudoers +file has the wrong group ownership. +If you wish to change the +.Em sudoers +file group ownership, add +.Dq sudoers_gid=N +(where +.Sq N +is the group-ID that owns the +.Em sudoers +file) to the +.Nm +.Em Plugin +line in the +.Xr sudo.conf @mansectform@ +file. +.It unable to open @rundir@/ts/user-ID +.Nm +was unable to read or create the user's time stamp file. +This can happen when +.Em timestampowner +is set to a user other than +.Sy root +and the mode on +.Pa @rundir@ +is not searchable by group or other. +The default mode for +.Pa @rundir@ +is 0711. +.It unable to write to @rundir@/ts/user-ID +.Nm +was unable to write to the user's time stamp file. +.It @rundir@/ts is owned by uid X, should be Y +The time stamp directory is owned by a user other than +.Em timestampowner . +This can occur when the value of +.Em timestampowner +has been changed. +.Nm +will ignore the time stamp directory until the owner is corrected. +.It @rundir@/ts is group writable +The time stamp directory is group-writable; it should be writable only by +.Em timestampowner . +The default mode for the time stamp directory is 0700. +.Nm +will ignore the time stamp directory until the mode is corrected. +.El +.Ss Notes on logging via syslog +By default, +.Nm +logs messages via +.Xr syslog 3 . +The +.Em date , +.Em hostname , +and +.Em progname +fields are added by the system's +.Xr syslog 3 +function, not +.Nm +itself. +As such, they may vary in format on different systems. +.Pp +The maximum size of syslog messages varies from system to system. +The +.Em syslog_maxlen +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 +.Em syslog_maxlen . +.Ss Notes on logging to a file +If the +.Em logfile +option is set, +.Nm +will log to a local file, such as +.Pa @log_dir@/sudo . +When logging to a file, +.Nm +uses a format similar to +.Xr syslog 3 , +with a few important differences: +.Bl -enum +.It +The +.Em progname +field is not present. +.It +The +.Em hostname +is only logged if the +.Em log_host +option is enabled. +.It +The date does not include the year unless the +.Em log_year +option is enabled. +.It +Lines that are longer than +.Em loglinelen +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 +.Xr grep 1 +on the log files. +If the +.Em loglinelen +option is set to 0 (or negated with a +.Ql \&! ) , +word wrap will be disabled. +.El +.Sh I/O LOGGING +When I/O logging is enabled, +.Nm sudo +will runs the command in a pseudo-terminal, logging user input +and/or output, depending on which +.Nm +flags are enabled. +There are five distinct types of I/O that can be logged, each with +a corresponding +.Nm +flag. +.Bl -column "standard output" "log_output" "command output displayed to the screen" +.It Sy Type Ta Sy Flag Ta Sy Description +.It terminal input Ta log_ttyin Ta keystrokes entered by the user +.It terminal output Ta log_ttyout Ta command output displayed to the screen +.It standard input Ta log_stdin Ta input from a pipe or a file +.It standard output Ta log_stdout Ta output to a pipe or a file +.It standard error Ta log_stderr Ta output to a pipe or a file +.El +.Pp +In addition to flags described the above, the +.Em log_input +flag and +.Dv LOG_INPUT +command tag set both +.Em log_ttyin +and +.Em log_stdin . +The +.Em log_output +flag and +.Dv LOG_OUTPUT +command tag set +.Em log_ttyout , +.Em log_stdout , +and +.Em log_stderr . +.Pp +To capture terminal input and output, +.Nm sudo +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, +.Nm sudo +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 +.Em iolog_dir +option +.Po +.Pa @iolog_dir@ +by default +.Pc +using a unique session ID that is included in the +.Nm sudo +log line, prefixed with +.Ql TSID= . +The +.Em iolog_file +option may be used to control the format of the session ID. +For remote logs, the +.Em log_servers +setting is used to specify one or more log servers running +.Nm sudo_logsrvd +or another server that implements the protocol described by +.Xr 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 +.Nm sudo +is actively reading the standard input. +This may have unexpected results when using +.Nm sudo +in a shell script that expects to process the standard input. +For example, given the following shell script: +.Bd -literal -offset 4n +#!/bin/sh +sudo echo testing +echo done +.Ed +.Pp +It will behave as expected when the script is passed to the shell as a +an argument: +.Bd -literal -offset 4n +$ sh test.sh +testing +done +.Ed +.Pp +However, if the script is passed to the shell on the standard input, the +.Ql sudo echo testing +command will consume the rest of the script. +This means that the +.Ql echo done +statement is never executed. +.Bd -literal -offset 4n +$ sh -s < test.sh +testing +.Ed +.Pp +There are several ways to work around this problem: +.Bl -enum +.It +Redirect the standard input from +.Pa /dev/null +when running a command via +.Nm sudo +that does not need to read the standard input. +.Bd -literal -offset 4n +sudo echo testing < /dev/null +.Ed +.It +Pass the script to the shell by path name instead of via the standard input. +.Bd -literal -offset 4n +sh test.sh +.Ed +.It +Disable logging the standard input for commands that do not need +to read the standard input. +.Bd -literal -offset 4n +Defaults!/bin/echo !log_stdin +.Ed +.El +.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 +.Xr rsync 1 +and +.Xr 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: +.Bd -literal -offset 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 +.Ed +.Pp +However, be aware that using the +.Em log_input +flag or the +.Dv LOG_INPUT +command tag will also enable +.Em log_stdin . +Likewise, the +.Em log_ouput +flag or the +.Dv LOG_OUTPUT +command tag will enable +.Em log_stdout +and +.Em log_stderr. +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: +.Bl -tag -width "log.json" +.It Pa log +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 +.Nm sudo , +the name of the target user, the name of the target group (optional), +the terminal that +.Nm sudo +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). +.It Pa log.json +A JSON-formatted file containing information about the command. +This is similar to the +.Pa log +file but contains additional information and is easily extensible. +The +.Pa log.json +file will be used by +.Xr sudoreplay @mansectsu@ +in preference to the +.Pa log +file if it exists. +The file may contain the following elements: +.Bl -tag -width 4n +.It timestamp +A JSON object containing time the command was run. +It consists of two values, +.Em seconds +and +.Em nanoseconds . +.It columns +The number of columns of the terminal the command ran on, or zero +if no terminal was present. +.It command +The fully-qualified path of the command that was run. +.It lines +The number of lines of the terminal the command ran on, or zero +if no terminal was present. +.It runargv +A JSON array representing the command's argument vector as passed to the +.Xr execve 2 +system call. +.It runenv +A JSON array representing the command's environment as passed to the +.Xr execve 2 +system call. +.It rungid +The group ID the command ran as. +This element is only present when the user specifies a group on the +command line. +.It 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. +.It runuid +The user ID the command ran as. +.It runuser +The name of the user the command ran as. +.It submitcwd +The current working directory at the time +.Nm sudo +was run. +.It submithost +The name of the host the command was run on. +.It submituser +The name of the user who ran the command via +.Nm sudo . +.It ttyname +The path name of the terminal the user invoked +.Nm sudo +from. +If the command was run in a pseudo-terminal, +.Em ttyname +will be different from the terminal the command actually ran in. +.El +.It Pa timing +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 +.Bl -tag -width 4n -compact +.It 0 +standard input, number of bytes in the entry +.It 1 +standard output, number of bytes in the entry +.It 2 +standard error, number of bytes in the entry +.It 3 +terminal input, number of bytes in the entry +.It 4 +terminal output, number of bytes in the entry +.It 5 +window change, new number lines and columns +.It 6 +bug compatibility for +.Nm sudo +1.8.7 terminal output +.It 7 +command suspend or resume, signal received +.El +.It Pa ttyin +Raw input from the user's terminal, exactly as it was received. +This file is only present if the +.Em log_input +or +.Em log_ttyin +flags are set and +.Nm sudo +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: +.Ql gunzip -c ttyin | tr \&"\er\&" \&"\en\&" +.It Pa stdin +The standard input when no terminal is present, or input redirected from +a pipe or file. +This file is only present if the +.Em log_input +or +.Em log_stdin +flags are set and the standard input is not connected to a terminal. +.It Pa ttyout +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 +.Em log_output +or +.Em log_ttyout +flags are set and +.Nm sudo +was run from a terminal. +.It Pa stdout +The standard output when no terminal is present, or output redirected to +a pipe or file. +This file is only present if the +.Em log_output +or +.Em log_stdout +flags are set and the standard output is not connected to a terminal. +.It Pa stderr +The standard error when no terminal is present, or output redirected to +a pipe or file. +This file is only present if the +.Em log_output +or +.Em log_stderr +flags are set and the standard error is not connected to a terminal. +.El +.Pp +All files other than +.Pa log +are compressed in gzip format unless the +.Em compress_io +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 +.Nm sudo +has exited or has been terminated by a signal. +The +.Em iolog_flush +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 +.Xr 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 +.Em log_output +or +.Dv LOG_OUTPUT +is all that is required. +When logging input, consider disabling the +.Em log_passwords +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 +.Em maxseq +option to the maximum number of logs you wish to store. +Once the I/O log sequence number reaches +.Em maxseq , +it will be reset to zero and +.Nm +will truncate and re-use any existing I/O logs. +.Sh FILES +.Bl -tag -width 24n +.It Pa @sysconfdir@/sudo.conf +Sudo front-end configuration +.It Pa @sysconfdir@/sudoers +List of who can run what +.It Pa /etc/group +Local groups file +.It Pa /etc/netgroup +List of network groups +.It Pa @iolog_dir@ +I/O log files +.It Pa @rundir@/ts +Directory containing time stamps for the +.Nm +security policy +.It Pa @vardir@/lectured +Directory containing lecture status files for the +.Nm +security policy +.It Pa /etc/environment +Initial environment for +.Fl i +mode on AIX and Linux systems +.El +.Sh EXAMPLES +Below are example +.Em sudoers +file entries. +Admittedly, some of these are a bit contrived. +First, we allow a few environment variables to pass and then define our +.Em aliases : +.Bd -literal +# 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 +.Ed +.Pp +Here we override some of the compiled in default values. +We want +.Nm sudo +to log via +.Xr syslog 3 +using the +.Em auth +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 +.Nm sudo +lecture and we want to allow them to run commands in a +.Xr chroot 2 +.Dq sandbox +via the +.Fl R +option. +User +.Sy millert +need not provide a password and we don't want to reset the +.Ev LOGNAME +or +.Ev USER +environment variables when running commands as +.Sy root . +Additionally, on the machines in the +.Dv SERVERS +.Em Host_Alias , +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 +.Em Cmnd_Alias +.Po +.Pa /usr/bin/more , +.Pa /usr/bin/pg +and +.Pa /usr/bin/less +.Pc . +This will not effectively constrain users with +.Nm sudo +.Sy ALL +privileges. +.Bd -literal +# 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 +.Ed +.Pp +The +.Em User specification +is the part that actually determines who may run what. +.Bd -literal +root ALL = (ALL) ALL +%wheel ALL = (ALL) ALL +.Ed +.Pp +We let +.Sy root +and any user in group +.Sy wheel +run any command on any host as any user. +.Bd -literal +FULLTIMERS ALL = NOPASSWD: ALL +.Ed +.Pp +Full time sysadmins +.Po +.Sy millert , +.Sy mikef , +and +.Sy dowdy +.Pc +may run any command on any host without authenticating themselves. +.Bd -literal +PARTTIMERS ALL = ALL +.Ed +.Pp +Part time sysadmins +.Sy bostley , +.Sy jwfox , +and +.Sy crawl ) +may run any command on any host but they must authenticate themselves +first (since the entry lacks the +.Dv NOPASSWD +tag). +.Bd -literal +jack CSNETS = ALL +.Ed +.Pp +The user +.Sy jack +may run any command on the machines in the +.Dv CSNETS +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 +.Dv CSNETS , +the local machine's netmask will be used during matching. +.Bd -literal +lisa CUNETS = ALL +.Ed +.Pp +The user +.Sy lisa +may run any command on any host in the +.Dv CUNETS +alias (the class B network 128.138.0.0). +.Bd -literal +operator ALL = DUMPS, KILL, SHUTDOWN, HALT, REBOOT, PRINTING,\e + sudoedit /etc/printcap, /usr/oper/bin/ +.Ed +.Pp +The +.Sy operator +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 +.Pa /usr/oper/bin/ . +One command in the +.Dv DUMPS +Cmnd_Alias includes a sha224 digest, +.Pa /home/operator/bin/start_backups . +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 +.Nm sudo . +.Bd -literal +joe ALL = /usr/bin/su operator +.Ed +.Pp +The user +.Sy joe +may only +.Xr su 1 +to operator. +.Bd -literal +pete HPPA = /usr/bin/passwd [A-Za-z]*, !/usr/bin/passwd *root* + +%opers ALL = (: ADMINGRP) /usr/sbin/ +.Ed +.Pp +Users in the +.Sy opers +group may run commands in +.Pa /usr/sbin/ +as themselves +with any group in the +.Dv ADMINGRP +.Em Runas_Alias +(the +.Sy adm +and +.Sy oper +groups). +.Pp +The user +.Sy pete +is allowed to change anyone's password except for +.Sy root +on the +.Dv HPPA +machines. +Because command line arguments are matched as a single, +concatenated string, the +.Ql * +wildcard will match +.Em multiple +words. +This example assumes that +.Xr passwd 1 +does not take multiple user names on the command line. +On systems with GNU +.Xr getopt 3 , +options to +.Xr passwd 1 +may be specified after the user argument. +As a result, this rule will also allow: +.Bd -literal -offset 4n +passwd username --expire +.Ed +.Pp +which may not be desirable. +.Bd -literal +bob SPARC = (OP) ALL : SGI = (OP) ALL +.Ed +.Pp +The user +.Sy bob +may run anything on the +.Dv SPARC +and +.Dv SGI +machines as any user listed in the +.Dv OP +.Em Runas_Alias +.Po +.Sy root +and +.Sy operator . +.Pc +.Bd -literal +jim +biglab = ALL +.Ed +.Pp +The user +.Sy jim +may run any command on machines in the +.Em biglab +netgroup. +.Nm sudo +knows that +.Dq biglab +is a netgroup due to the +.Ql + +prefix. +.Bd -literal ++secretaries ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser +.Ed +.Pp +Users in the +.Sy secretaries +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. +.Bd -literal +fred ALL = (DB) NOPASSWD: ALL +.Ed +.Pp +The user +.Sy fred +can run commands as any user in the +.Dv DB +.Em Runas_Alias +.Po +.Sy oracle +or +.Sy sybase +.Pc +without giving a password. +.Bd -literal +john ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root* +.Ed +.Pp +On the +.Dv ALPHA +machines, user +.Sy john +may su to anyone except +.Sy root +but he is not allowed to specify any options to the +.Xr su 1 +command. +.Bd -literal +jen ALL, !SERVERS = ALL +.Ed +.Pp +The user +.Sy jen +may run any command on any machine except for those in the +.Dv SERVERS +.Em Host_Alias +(primary, mail, www, and ns). +.Bd -literal +jill SERVERS = /usr/bin/, !SU, !SHELLS +.Ed +.Pp +For any machine in the +.Dv SERVERS +.Em Host_Alias , +.Sy jill +may run +any commands in the directory +.Pa /usr/bin/ +except for those commands +belonging to the +.Dv SU +and +.Dv SHELLS +.Em Cmnd_Aliases . +While not specifically mentioned in the rule, the commands in the +.Dv PAGERS +.Em Cmnd_Alias +all reside in +.Pa /usr/bin +and have the +.Em noexec +option set. +.Bd -literal +steve CSNETS = (operator) /usr/local/op_commands/ +.Ed +.Pp +The user +.Sy steve +may run any command in the directory /usr/local/op_commands/ +but only as user operator. +.Bd -literal +matt valkyrie = KILL +.Ed +.Pp +On his personal workstation, valkyrie, +.Sy matt +needs to be able to kill hung processes. +.Bd -literal +WEBADMIN www = (www) ALL, (root) /usr/bin/su www +.Ed +.Pp +On the host www, any user in the +.Dv WEBADMIN +.Em User_Alias +(will, wendy, and wim), may run any command as user www (which owns the +web pages) or simply +.Xr su 1 +to www. +.Bd -literal +ALL CDROM = NOPASSWD: /sbin/umount /CDROM,\e + /sbin/mount -o nosuid\e,nodev /dev/cd0a /CDROM +.Ed +.Pp +Any user may mount or unmount a CD-ROM on the machines in the CDROM +.Em Host_Alias +(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 So !\& Sc operator +It is generally not effective to +.Dq subtract +commands from +.Sy ALL +using the +.Ql !\& +operator. +A user can trivially circumvent this by copying the desired command +to a different name and then executing that. +For example: +.Bd -literal +bill ALL = ALL, !SU, !SHELLS +.Ed +.Pp +Doesn't really prevent +.Sy bill +from running the commands listed in +.Dv SU +or +.Dv SHELLS +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 +.Sy ALL +there is nothing to prevent them from creating their own program that gives +them a +.Sy root +shell (or making their own copy of a shell) regardless of any +.Ql !\& +elements in the user specification. +.Ss Security implications of Em fast_glob +If the +.Em fast_glob +option is in use, it is not possible to reliably negate commands where the +path name includes globbing (aka wildcard) characters. +This is because the C library's +.Xr 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 +.Em sudoers +file entry: +.Bd -literal +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 +.Ed +.Pp +User +.Sy john +can still run +.Ql /usr/bin/passwd root +if +.Em fast_glob +is enabled by changing to +.Pa /usr/bin +and running +.Ql ./passwd root +instead. +.Pp +Another potential issue is that when +.Nm sudo +executes the command, it must use the command or path specified by +the user instead of a path listed in the +.Em sudoers +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 +.Ql \&? +or +.Ql * +will match across word boundaries, which may be unexpected. +For example, while a sudoers entry like: +.Bd -literal -offset 4n +%operator ALL = /bin/cat @log_dir@/messages* +.Ed +.Pp +will allow command like: +.Bd -literal -offset 4n +$ sudo cat @log_dir@/messages.1 +.Ed +.Pp +It will also allow: +.Bd -literal -offset 4n +$ sudo cat @log_dir@/messages /etc/shadow +.Ed +.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: +.Bd -literal -offset 4n +%operator ALL = /bin/cat ^@log_dir@/messages[^[:space:]]*$ +.Ed +.Pp +The regular expression will only match a single file with a +name that begins with +.Pa @log_dir@/messages +and does not include any white space in the name. +It is often better to do command line processing outside of the +.Em sudoers +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 +.Em fast_glob +option: +.Bl -bullet -width 1n +.It +It is not possible to reliably negate commands when the +path name is a regular expression. +.It +When +.Nm sudo +executes the command, it must use the command or path specified by +the user instead of a path listed in the +.Em sudoers +file. +This may lead to a time of check versus time of use race condition. +.El +.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 +.Nm sudo +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 +.Nm sudo Ns '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: +.Bl -tag -width "intercept" +.It 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 +.Nm sudoedit +is a better solution to +running editors via +.Nm sudo . +Due to the large number of programs that +offer shell escapes, restricting users to the set of programs that +do not is often unworkable. +.It intercept +On most systems, +.Nm sudo Ns 's +.Em intercept +functionality can be used to transparently intercept an attempt to +run a new command, allow or deny it based on +.Em sudoers +rules, and log the result. +For example, this can be used to restrict the commands run from +within a privileged shell or editor. +However, not all programs operate correctly when +.Em intercept +is enabled. +.Pp +There are two underlying mechanisms that may be used to implement +.Em intercept +mode: +.Em dso +and +.Em trace . +The +.Em intercept_type +setting can be used to select between them. +.Pp +The first mechanism, +.Em dso , +overrides the standard C library functions that are used to execute a +command. +It does this by setting an environment variable (usually +.Ev LD_PRELOAD ) +to the path of a dynamic shared object, or shared library, +containing custom versions of the +.Xr execve 2 , +.Xr execl 3 , +.Xr execle 3 , +.Xr execlp 3 , +.Xr execv 3 , +.Xr execvp 3 , +.Xr execvpe 3 , +and +.Xr system 3 +library functions that connect back to +.Nm sudo +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 +.Ev LD_PRELOAD +(or the equivalent) when running set-user-ID and set-group-ID programs, +.Nm +will not permit such programs to be run in +.Em intercept +mode by default. +The +.Em dso +mechanism is incompatible with +.Nm sudo Ns 's +SELinux RBAC support (but see below). +SELinux disables +.Ev LD_PRELOAD +by default and interferes with file descriptor inheritance, which +.Nm sudo +relies on. +.Pp +The second mechanism, +.Em trace , +is available on Linux systems that support +.Xr seccomp 2 +filtering. +It uses +.Xr ptrace 2 +and +.Xr seccomp 2 +to intercept the +.Xr execve 2 +system call instead of pre-loading a dynamic shared object. +Both static and dynamic executables are supported and it is compatible with +.Nm sudo Ns 's +SELinux RBAC mode. +Functions utilizing the +.Xr execveat 2 +system call, such as +.Xr fexecve 3 , +are not currently intercepted. +Programs that rely on +.Xr ptrace 2 +themselves, such as debuggers and system call tracers +.Po +such as +.Xr strace 1 +and +.Xr truss 1 +.Pc +will be unable to function if +.Em intercept +is enabled in +.Em trace +mode. +This same restriction applies to the +.Em log_subcmds +sudoers option. +.Pp +The +.Em intercept +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 +.Ev LD_PRELOAD +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. +.Pp +To enable intercept mode on a per-command basis, use the +.Dv INTERCEPT +tag as documented in the User Specification section above. +Here is that example again: +.Bd -literal +chuck research = INTERCEPT: ALL +.Ed +.Pp +This allows user +.Sy chuck +to run any command on the machine +.Dq research +in intercept mode. +Any commands run via shell escapes will be validated and logged by +.Nm sudo . +If you are unsure whether or not your system is capable of supporting +.Em intercept , +you can always just try it out and check whether or not external +commands run via a shell are logged when +.Em intercept +is enabled. +.Pp +There is an inherent race condition between when a command is checked against +.Nm +rules and when it is actually executed. +If a user is allowed to run arbitrary commands, they may be able +to change the +.Xr execve 2 +arguments in the program after the +.Nm +policy check has completed but before the new command is executed. +Starting with version 1.9.12, the +.Em trace +method will verify that the command and its arguments have not +changed after +.Xr execve 2 +has completed but before execution of the new program has had a chance to run. +This is not the case with the +.Em dso +method. +See the description of the +.Em intercept_verify +setting for more information. +.It log +There are two separate but related ways to log additional commands. +The first is to enable I/O logging using the +.Em log_output +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 +.Em log_subcmds +flag in +.Em sudoers +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 +.Xr sudoreplay @mansectsu@ +utility to replay the I/O log at the exact moment when the command was run. +The +.Em log_subcmds +flag uses the same mechanism as +.Em intercept +(see above) and has the same limitations. +.It noexec +.Nm sudo Ns 's +.Em noexec +functionality can be used to prevent a program run by +.Nm sudo +from executing any other programs. +On most systems, it uses the same +.Ev LD_PRELOAD +mechanism as +.Em intercept +(see above) and thus the same caveats apply. +The +.Em noexec +functionality +is capable of blocking execution of commands run via the +.Xr execve 2 , +.Xr execl 3 , +.Xr execle 3 , +.Xr execlp 3 , +.Xr exect 3 , +.Xr execv 3 , +.Xr execveat 3 , +.Xr execvP 3 , +.Xr execvp 3 , +.Xr execvpe 3 , +.Xr fexecve 3 , +.Xr popen 3 , +.Xr posix_spawn 3 , +.Xr posix_spawnp 3 , +.Xr system 3 , +and +.Xr wordexp 3 +functions. +On Linux, a +.Xr seccomp 2 +filter is used to implement +.Em noexec . +On Solaris 10 and higher, +.Em noexec +uses Solaris privileges instead of the +.Ev LD_PRELOAD +environment variable. +.Pp +To enable +.Em noexec +for a command, use the +.Dv NOEXEC +tag as documented in the User Specification section above. +Here is that example again: +.Bd -literal +aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi +.Ed +.Pp +This allows user +.Sy aaron +to run +.Pa /usr/bin/more +and +.Pa /usr/bin/vi +with +.Em noexec +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 +.Em noexec +you can always just try it out and check whether shell escapes work when +.Em noexec +is enabled. +.El +.Pp +Restricting shell escapes is not a panacea. +Programs running as +.Sy root +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 +.Nm sudoedit +(see below). +.Ss Secure editing +The +.Nm +plugin includes +.Nm sudoedit +support which allows users to securely edit files with the editor +of their choice. +As +.Nm sudoedit +is a built-in command, it must be specified in the +.Em sudoers +file without a leading path. +However, it may take command line arguments just as a normal command does. +Wildcards used in +.Em sudoedit +command line arguments are expected to be path names, so a forward slash +.Pq Ql / +will not be matched by a wildcard. +.Pp +Unlike other +.Nm sudo +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 +.Fl e +option in +.Xr sudo @mansectsu@ . +.Pp +For example, to allow user operator to edit the +.Dq message of the day +file on any machine: +.Bd -literal -offset 4n +operator ALL = sudoedit /etc/motd +.Ed +.Pp +The operator user then runs +.Nm sudoedit +as follows: +.Bd -literal -offset 4n +$ sudoedit /etc/motd +.Ed +.Pp +The editor will run as the operator user, not +.Sy @runas_default@ , +on a temporary copy of +.Pa /etc/motd . +After the file has been edited, +.Pa /etc/motd +will be updated with the contents of the temporary copy. +.Pp +Users should +.Em never +be granted +.Nm sudoedit +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 +.Nm sudoedit +will refuse to edit a file located in a writable directory +unless the +.Em sudoedit_checkdir +option has been disabled or the invoking user is +.Sy root . +Additionally, in version 1.8.15 and higher, +.Nm sudoedit +will refuse to open a symbolic link unless either the +.Em sudoedit_follow +option is enabled or the +.Em sudoedit +command is prefixed with the +.Dv FOLLOW +tag in the +.Em sudoers +file. +.Ss Time stamp file checks +.Nm +will check the ownership of its time stamp directory +.Po +.Pa @rundir@/ts +by default +.Pc +and ignore the directory's contents if it is not owned by +.Sy root +or if it is writable by a user other than +.Sy root . +Older versions of +.Nm sudo +stored time stamp files in +.Pa /tmp ; +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 +.Em should +be cleared at reboot time, not all systems contain a +.Pa /run +or +.Pa /var/run +directory. +To avoid potential problems, +.Nm +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 +.Nm +relies on the system clock for time stamp validation, it may be +possible on such systems for a user to run +.Nm sudo +for longer than +.Em timestamp_timeout +by setting the clock back. +To combat this, +.Nm +uses a monotonic clock (which never moves backwards) for its time stamps +if the system supports it. +.Pp +.Nm +will not honor time stamps set far in the future. +Time stamps with a date greater than current_time + 2 * +.Dv TIMEOUT +will be ignored and +.Nm +will log and complain. +.Pp +If the +.Em timestamp_type +option is set to +.Dq tty , +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 +.Em timestamp_type +option is set to +.Dq global , +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 +.Em timestamp_type +option is set to +.Dq ppid , +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 +.Nm +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 +.Xr sudo.conf @mansectform@ +file. +.Pp +The +.Nm +plugin uses the same debug flag format as the +.Nm sudo +front-end: +.Em subsystem Ns @ Ns Em priority . +.Pp +The priorities used by +.Nm , +in order of decreasing severity, +are: +.Em crit , err , warn , notice , diag , info , trace , +and +.Em debug . +Each priority, when specified, also includes all priorities higher +than it. +For example, a priority of +.Em notice +would include debug messages logged at +.Em notice +and higher. +.Pp +The following subsystems are used by the +.Nm +plugin: +.Bl -tag -width "defaults" +.It Em alias +.Em User_Alias , +.Em Runas_Alias , +.Em Host_Alias +and +.Em Cmnd_Alias +processing +.It Em all +matches every subsystem +.It Em audit +BSM and Linux audit code +.It Em auth +user authentication +.It Em defaults +.Em sudoers +file +.Em Defaults +settings +.It Em env +environment handling +.It Em ldap +LDAP-based sudoers +.It Em logging +logging support +.It Em match +matching of users, groups, hosts, and netgroups in the +.Em sudoers +file +.It Em netif +network interface handling +.It Em nss +network service switch handling in +.Nm +.It Em parser +.Em sudoers +file parsing +.It Em perms +permission setting +.It Em plugin +The equivalent of +.Em main +for the plugin. +.It Em pty +pseudo-terminal related code +.It Em rbtree +redblack tree internals +.It Em sssd +SSSD-based sudoers +.It Em util +utility functions +.El +.Pp +For example: +.Bd -literal +Debug @sudoers_plugin@ @log_dir@/sudoers_debug match@info,nss@info +.Ed +.Pp +For more information, see the +.Xr sudo.conf @mansectform@ +manual. +.Sh SEE ALSO +.Xr ssh 1 , +.Xr su 1 , +.Xr fnmatch 3 , +.Xr glob 3 , +.Xr mktemp 3 , +.Xr strftime 3 , +.Xr sudo.conf @mansectform@ , +.Xr sudo_plugin @mansectform@ , +.Xr sudoers.ldap @mansectform@ , +.Xr sudoers_timestamp @mansectform@ , +.Xr sudo @mansectsu@ , +.Xr visudo @mansectsu@ +.Sh AUTHORS +Many people have worked on +.Nm sudo +over the years; this version consists of code written primarily by: +.Bd -ragged -offset indent +.An Todd C. Miller +.Ed +.Pp +See the CONTRIBUTORS.md file in the +.Nm sudo +distribution (https://www.sudo.ws/about/contributors/) for an +exhaustive list of people who have contributed to +.Nm sudo . +.Sh CAVEATS +The +.Em sudoers +file should +.Sy always +be edited by the +.Nm visudo +utility which locks the file and checks for syntax errors. +If +.Em sudoers +contains syntax errors, +.Nm sudo +may refuse to run, which is a serious problem if +.Nm sudo +is your only method of obtaining superuser privileges. +Recent versions of +.Nm +will attempt to recover after a syntax error by ignoring the rest of +the line after encountering an error. +Older versions of +.Nm sudo +will not run if +.Em sudoers +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 +.Em hostname +command or use the +.Em fqdn +option in +.Em sudoers . +.Sh BUGS +If you believe you have found a bug in +.Nm sudo , +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 +.Nm sudo +is provided +.Dq AS IS +and any express or implied warranties, including, but not limited +to, the implied warranties of merchantability and fitness for a +particular purpose are disclaimed. +See the LICENSE.md file distributed with +.Nm sudo +or https://www.sudo.ws/about/license/ for complete details. |