diff options
Diffstat (limited to 'doc/sudoers.man.in')
| -rw-r--r-- | doc/sudoers.man.in | 5831 |
1 files changed, 5831 insertions, 0 deletions
diff --git a/doc/sudoers.man.in b/doc/sudoers.man.in new file mode 100644 index 0000000..e2470b5 --- /dev/null +++ b/doc/sudoers.man.in @@ -0,0 +1,5831 @@ +.\" Automatically generated from an mdoc input file. Do not edit. +.\" +.\" Copyright (c) 1994-1996, 1998-2005, 2007-2018 +.\" 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 BA @BAMAN@ +.nr LC @LCMAN@ +.nr PS @PSMAN@ +.TH "SUDOERS" "@mansectform@" "December 20, 2018" "Sudo @PACKAGE_VERSION@" "File Formats Manual" +.nh +.if n .ad l +.SH "NAME" +\fBsudoers\fR +\- default sudo security policy plugin +.SH "DESCRIPTION" +The +\fBsudoers\fR +policy plugin determines a user's +\fBsudo\fR +privileges. +It is the default +\fBsudo\fR +policy plugin. +The policy is driven by +the +\fI@sysconfdir@/sudoers\fR +file or, optionally in LDAP. +The policy format is described in detail in the +\fISUDOERS FILE FORMAT\fR +section. +For information on storing +\fBsudoers\fR +policy information +in LDAP, please see +sudoers.ldap(@mansectform@). +.SS "Configuring sudo.conf for sudoers" +\fBsudo\fR +consults the +sudo.conf(@mansectform@) +file to determine which policy and I/O logging plugins to load. +If no +sudo.conf(@mansectform@) +file is present, or if it contains no +\fRPlugin\fR +lines, +\fBsudoers\fR +will be used for policy decisions and I/O logging. +To explicitly configure +sudo.conf(@mansectform@) +to use the +\fBsudoers\fR +plugin, the following configuration can be used. +.nf +.sp +.RS 6n +Plugin sudoers_policy sudoers.so +Plugin sudoers_io sudoers.so +.RE +.fi +.PP +Starting with +\fBsudo\fR +1.8.5, it is possible to specify optional arguments to the +\fBsudoers\fR +plugin in the +sudo.conf(@mansectform@) +file. +These arguments, if present, should be listed after the path to the plugin +(i.e., after +\fIsudoers.so\fR). +Multiple arguments may be specified, separated by white space. +For example: +.nf +.sp +.RS 6n +Plugin sudoers_policy sudoers.so sudoers_mode=0400 +.RE +.fi +.PP +The following plugin arguments are supported: +.TP 10n +ldap_conf=pathname +The +\fIldap_conf\fR +argument can be used to override the default path to the +\fIldap.conf\fR +file. +.TP 10n +ldap_secret=pathname +The +\fIldap_secret\fR +argument can be used to override the default path to the +\fIldap.secret\fR +file. +.TP 10n +sudoers_file=pathname +The +\fIsudoers_file\fR +argument can be used to override the default path to the +\fIsudoers\fR +file. +.TP 10n +sudoers_uid=uid +The +\fIsudoers_uid\fR +argument can be used to override the default owner of the sudoers file. +It should be specified as a numeric user ID. +.TP 10n +sudoers_gid=gid +The +\fIsudoers_gid\fR +argument can be used to override the default group of the sudoers file. +It must be specified as a numeric group ID (not a group name). +.TP 10n +sudoers_mode=mode +The +\fIsudoers_mode\fR +argument can be used to override the default file mode for the sudoers file. +It should be specified as an octal value. +.PP +For more information on configuring +sudo.conf(@mansectform@), +please refer to its manual. +.SS "User Authentication" +The +\fBsudoers\fR +security policy requires that most users authenticate +themselves before they can use +\fBsudo\fR. +A password is not required +if the invoking user is 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 +su(1), +when +\fBsudoers\fR +requires +authentication, it validates the invoking user's credentials, not +the target user's (or root's) credentials. +This can be changed via +the +\fIrootpw\fR, +\fItargetpw\fR +and +\fIrunaspw\fR +flags, described later. +.PP +If a user who is not listed in the policy tries to run a command +via +\fBsudo\fR, +mail is sent to the proper authorities. +The address +used for such mail is configurable via the +\fImailto\fR +Defaults entry +(described later) and defaults to +\fR@mailto@\fR. +.PP +Note that no mail will be sent if an unauthorized user tries to run +\fBsudo\fR +with the +\fB\-l\fR +or +\fB\-v\fR +option unless there is an authentication error and +either the +\fImail_always\fR +or +\fImail_badpass\fR +flags are enabled. +This allows users to +determine for themselves whether or not they are allowed to use +\fBsudo\fR. +All attempts to run +\fBsudo\fR +(successful or not) +will be logged, regardless of whether or not mail is sent. +.PP +If +\fBsudo\fR +is run by root and the +\fRSUDO_USER\fR +environment variable +is set, the +\fBsudoers\fR +policy will use this value to determine who +the actual user is. +This can be used by a user to log commands +through sudo even when a root shell has been invoked. +It also +allows the +\fB\-e\fR +option to remain useful even when invoked via a +sudo-run script or program. +Note, however, that the +\fIsudoers\fR +file lookup is still done for root, not the user specified by +\fRSUDO_USER\fR. +.PP +\fBsudoers\fR +uses per-user time stamp files for credential caching. +Once a user has been authenticated, a record is written +containing the user ID that was used to authenticate, the +terminal session ID, the start time of the session leader +(or parent process) and a time stamp +(using a monotonic clock if one is available). +The user may then use +\fBsudo\fR +without a password for a short period of time +(\fR@timeout@\fR +minutes unless overridden by the +\fItimestamp_timeout\fR +option) +\&. +By default, +\fBsudoers\fR +uses a separate record for each terminal, which means that +a user's login sessions are authenticated separately. +The +\fItimestamp_type\fR +option can be used to select the type of time stamp record +\fBsudoers\fR +will use. +.SS "Logging" +\fBsudoers\fR +can log both successful and unsuccessful attempts (as well +as errors) to +syslog(3), +a log file, or both. +By default, +\fBsudoers\fR +will log via +syslog(3) +but this is changeable via the +\fIsyslog\fR +and +\fIlogfile\fR +Defaults settings. +See +\fILOG FORMAT\fR +for a description of the log file format. +.PP +\fBsudoers\fR +is also capable of running a command in a pseudo-tty and logging all +input and/or output. +The standard input, standard output and standard error can be logged +even when not associated with a terminal. +I/O logging is not on by default but can be enabled using +the +\fIlog_input\fR +and +\fIlog_output\fR +options as well as the +\fRLOG_INPUT\fR +and +\fRLOG_OUTPUT\fR +command tags. +See +\fII/O LOG FILES\fR +for details on how I/O log files are stored. +.SS "Command environment" +Since environment variables can influence program behavior, +\fBsudoers\fR +provides a means to restrict which variables from the user's +environment are inherited by the command to be run. +There are two +distinct ways +\fBsudoers\fR +can deal with environment variables. +.PP +By default, the +\fIenv_reset\fR +option is enabled. +This causes commands +to be executed with a new, minimal environment. +On AIX (and Linux +systems without PAM), the environment is initialized with the +contents of the +\fI/etc/environment\fR +file. +.if \n(LC \{\ +On +BSD +systems, if the +\fIuse_loginclass\fR +option is enabled, the environment is initialized +based on the +\fIpath\fR +and +\fIsetenv\fR +settings in +\fI/etc/login.conf\fR. +.\} +The new environment contains the +\fRTERM\fR, +\fRPATH\fR, +\fRHOME\fR, +\fRMAIL\fR, +\fRSHELL\fR, +\fRLOGNAME\fR, +\fRUSER\fR +and +\fRSUDO_*\fR +variables +in addition to variables from the invoking process permitted by the +\fIenv_check\fR +and +\fIenv_keep\fR +options. +This is effectively a whitelist +for environment variables. +The environment variables +\fRLOGNAME\fR +and +\fRUSER\fR +are treated specially. +If one of them is preserved (or removed) from user's environment, the other +will be as well. +If +\fRLOGNAME\fR +and +\fRUSER\fR +are to be preserved but only one of them is present in the user's environment, +the other will be set to the same value. +This avoids an inconsistent environment where one of the variables +describing the user name is set to the invoking user and one is +set to the target user. +\fR()\fR +are removed unless both the name and value parts are matched by +\fIenv_keep\fR +or +\fIenv_check\fR, +as they may be interpreted as functions by the +\fBbash\fR +shell. +Prior to version 1.8.11, such variables were always removed. +.PP +If, however, the +\fIenv_reset\fR +option is disabled, any variables not +explicitly denied by the +\fIenv_check\fR +and +\fIenv_delete\fR +options are +inherited from the invoking process. +In this case, +\fIenv_check\fR +and +\fIenv_delete\fR +behave like a blacklist. +Prior to version 1.8.21, environment variables with a value beginning with +\fR()\fR +were always removed. +Beginning with version 1.8.21, a pattern in +\fIenv_delete\fR +is used to match +\fBbash\fR +shell functions instead. +Since it is not possible +to blacklist all potentially dangerous environment variables, use +of the default +\fIenv_reset\fR +behavior is encouraged. +.PP +Environment variables specified by +\fIenv_check\fR, +\fIenv_delete\fR, +or +\fIenv_keep\fR +may include one or more +\(oq*\(cq +characters which will match zero or more characters. +No other wildcard characters are supported. +.PP +By default, environment variables are matched by name. +However, if the pattern includes an equal sign +(\(oq=\&\(cq), +both the variables name and value must match. +For example, a +\fBbash\fR +shell function could be matched as follows: +.nf +.sp +.RS 4n +env_keep += "BASH_FUNC_my_func%%=()*" +.RE +.fi +.PP +Without the +\(lq\fR=()*\fR\(rq +suffix, this would not match, as +\fBbash\fR +shell functions are not preserved by default. +.PP +The complete list of environment variables that +\fBsudo\fR +allows or denies is contained in the output of +\(lq\fRsudo -V\fR\(rq +when run as root. +Please note that this list varies based on the operating system +\fBsudo\fR +is running on. +.PP +On systems that support PAM where the +\fBpam_env\fR +module is enabled for +\fBsudo\fR, +variables in the PAM environment may be merged in to the environment. +If a variable in the PAM environment is already present in the +user's environment, the value will only be overridden if the variable +was not preserved by +\fBsudoers\fR. +When +\fIenv_reset\fR +is enabled, variables preserved from the invoking user's environment +by the +\fIenv_keep\fR +list take precedence over those in the PAM environment. +When +\fIenv_reset\fR +is disabled, variables present the invoking user's environment +take precedence over those in the PAM environment unless they +match a pattern in the +\fIenv_delete\fR +list. +.PP +Note that the dynamic linker on most operating systems will remove +variables that can control dynamic linking from the environment of +setuid executables, including +\fBsudo\fR. +Depending on the operating +system this may include +\fR_RLD*\fR, +\fRDYLD_*\fR, +\fRLD_*\fR, +\fRLDR_*\fR, +\fRLIBPATH\fR, +\fRSHLIB_PATH\fR, +and others. +These type of variables are +removed from the environment before +\fBsudo\fR +even begins execution +and, as such, it is not possible for +\fBsudo\fR +to preserve them. +.PP +As a special case, if +\fBsudo\fR's +\fB\-i\fR +option (initial login) is +specified, +\fBsudoers\fR +will initialize the environment regardless +of the value of +\fIenv_reset\fR. +The +\fRDISPLAY\fR, +\fRPATH\fR +and +\fRTERM\fR +variables remain unchanged; +\fRHOME\fR, +\fRMAIL\fR, +\fRSHELL\fR, +\fRUSER\fR, +and +\fRLOGNAME\fR +are set based on the target user. +On AIX (and Linux +systems without PAM), the contents of +\fI/etc/environment\fR +are also +included. +.if \n(LC \{\ +On +BSD +systems, if the +\fIuse_loginclass\fR +flag is +enabled, the +\fIpath\fR +and +\fIsetenv\fR +variables in +\fI/etc/login.conf\fR +are also applied. +.\} +All other environment variables are removed unless permitted by +\fIenv_keep\fR +or +\fIenv_check\fR, +described above. +.PP +Finally, the +\fIrestricted_env_file\fR +and +\fIenv_file\fR +files are applied, if present. +The variables in +\fIrestricted_env_file\fR +are applied first and are subject to the same restrictions as the +invoking user's environment, as detailed above. +The variables in +\fIenv_file\fR +are applied last and are not subject to these restrictions. +In both cases, variables present in the files will only be set to +their specified values if they would not conflict with an existing +environment variable. +.SH "SUDOERS FILE FORMAT" +The +\fIsudoers\fR +file is composed of two types of entries: aliases +(basically variables) and user specifications (which specify who +may run what). +.PP +When multiple entries match for a user, they are applied in order. +Where there are multiple matches, the last match is used (which is +not necessarily the most specific match). +.PP +The +\fIsudoers\fR +file grammar will be described below in Extended Backus-Naur +Form (EBNF). +Don't despair if you are unfamiliar with EBNF; it is fairly simple, +and the definitions below are annotated. +.SS "Quick guide to EBNF" +EBNF is a concise and exact way of describing the grammar of a language. +Each EBNF definition is made up of +\fIproduction rules\fR. +E.g., +.PP +\fRsymbol ::= definition\fR | \fRalternate1\fR | \fRalternate2 ...\fR +.PP +Each +\fIproduction rule\fR +references others and thus makes up a +grammar for the language. +EBNF also contains the following +operators, which many readers will recognize from regular +expressions. +Do not, however, confuse them with +\(lqwildcard\(rq +characters, which have different meanings. +.TP 6n +\fR\&?\fR +Means that the preceding symbol (or group of symbols) is optional. +That is, it may appear once or not at all. +.TP 6n +\fR*\fR +Means that the preceding symbol (or group of symbols) may appear +zero or more times. +.TP 6n +\fR+\fR +Means that the preceding symbol (or group of symbols) may appear +one or more times. +.PP +Parentheses may be used to group symbols together. +For clarity, +we will use single quotes +('') +to designate what is a verbatim character string (as opposed to a symbol name). +.SS "Aliases" +There are four kinds of aliases: +\fRUser_Alias\fR, +\fRRunas_Alias\fR, +\fRHost_Alias\fR +and +\fRCmnd_Alias\fR. +.nf +.sp +.RS 0n +Alias ::= 'User_Alias' User_Alias_Spec (':' User_Alias_Spec)* | + 'Runas_Alias' Runas_Alias_Spec (':' Runas_Alias_Spec)* | + 'Host_Alias' Host_Alias_Spec (':' Host_Alias_Spec)* | + 'Cmnd_Alias' Cmnd_Alias_Spec (':' Cmnd_Alias_Spec)* + +User_Alias ::= NAME + +User_Alias_Spec ::= User_Alias '=' User_List + +Runas_Alias ::= NAME + +Runas_Alias_Spec ::= Runas_Alias '=' Runas_List + +Host_Alias ::= NAME + +Host_Alias_Spec ::= Host_Alias '=' Host_List + +Cmnd_Alias ::= NAME + +Cmnd_Alias_Spec ::= Cmnd_Alias '=' Cmnd_List + +NAME ::= [A-Z]([A-Z][0-9]_)* +.RE +.fi +.PP +Each +\fIalias\fR +definition is of the form +.nf +.sp +.RS 0n +Alias_Type NAME = item1, item2, ... +.RE +.fi +.PP +where +\fIAlias_Type\fR +is one of +\fRUser_Alias\fR, +\fRRunas_Alias\fR, +\fRHost_Alias\fR, +or +\fRCmnd_Alias\fR. +A +\fRNAME\fR +is a string of uppercase letters, numbers, +and underscore characters +(\(oq_\(cq). +A +\fRNAME\fR +\fBmust\fR +start with an +uppercase letter. +It is possible to put several alias definitions +of the same type on a single line, joined by a colon +(\(oq:\&\(cq). +E.g., +.nf +.sp +.RS 0n +Alias_Type NAME = item1, item2, item3 : NAME = item4, item5 +.RE +.fi +.PP +It is a syntax error to redefine an existing +\fIalias\fR. +It is possible to use the same name for +\fIaliases\fR +of different types, but this is not recommended. +.PP +The definitions of what constitutes a valid +\fIalias\fR +member follow. +.nf +.sp +.RS 0n +User_List ::= User | + User ',' User_List + +User ::= '!'* user name | + '!'* #uid | + '!'* %group | + '!'* %#gid | + '!'* +netgroup | + '!'* %:nonunix_group | + '!'* %:#nonunix_gid | + '!'* User_Alias +.RE +.fi +.PP +A +\fRUser_List\fR +is made up of one or more user names, user IDs +(prefixed with +\(oq#\(cq), +system group names and IDs (prefixed with +\(oq%\(cq +and +\(oq%#\(cq +respectively), netgroups (prefixed with +\(oq+\(cq), +non-Unix group names and IDs (prefixed with +\(oq%:\(cq +and +\(oq%:#\(cq +respectively) and +\fRUser_Alias\fRes. +Each list item may be prefixed with zero or more +\(oq\&!\(cq +operators. +An odd number of +\(oq\&!\(cq +operators negate the value of +the item; an even number just cancel each other out. +User netgroups are matched using the user and domain members only; +the host member is not used when matching. +.PP +A +\fRuser name\fR, +\fRuid\fR, +\fRgroup\fR, +\fRgid\fR, +\fRnetgroup\fR, +\fRnonunix_group\fR +or +\fRnonunix_gid\fR +may be enclosed in double quotes to avoid the +need for escaping special characters. +Alternately, special characters +may be specified in escaped hex mode, e.g., \ex20 for space. +When +using double quotes, any prefix characters must be included inside +the quotes. +.PP +The actual +\fRnonunix_group\fR +and +\fRnonunix_gid\fR +syntax depends on +the underlying group provider plugin. +For instance, the QAS AD plugin supports the following formats: +.TP 3n +\fB\(bu\fR +Group in the same domain: "%:Group Name" +.TP 3n +\fB\(bu\fR +Group in any domain: "%:Group Name@FULLY.QUALIFIED.DOMAIN" +.TP 3n +\fB\(bu\fR +Group SID: "%:S-1-2-34-5678901234-5678901234-5678901234-567" +.PP +See +\fIGROUP PROVIDER PLUGINS\fR +for more information. +.PP +Note that quotes around group names are optional. +Unquoted strings must use a backslash +(\(oq\e\(cq) +to escape spaces and special characters. +See +\fIOther special characters and reserved words\fR +for a list of +characters that need to be escaped. +.nf +.sp +.RS 0n +Runas_List ::= Runas_Member | + Runas_Member ',' Runas_List + +Runas_Member ::= '!'* user name | + '!'* #uid | + '!'* %group | + '!'* %#gid | + '!'* %:nonunix_group | + '!'* %:#nonunix_gid | + '!'* +netgroup | + '!'* Runas_Alias +.RE +.fi +.PP +A +\fRRunas_List\fR +is similar to a +\fRUser_List\fR +except that instead +of +\fRUser_Alias\fRes +it can contain +\fRRunas_Alias\fRes. +Note that +user names and groups are matched as strings. +In other words, two +users (groups) with the same uid (gid) are considered to be distinct. +If you wish to match all user names with the same uid (e.g., +root and toor), you can use a uid instead (#0 in the example given). +.nf +.sp +.RS 0n +Host_List ::= Host | + Host ',' Host_List + +Host ::= '!'* host name | + '!'* ip_addr | + '!'* network(/netmask)? | + '!'* +netgroup | + '!'* Host_Alias +.RE +.fi +.PP +A +\fRHost_List\fR +is made up of one or more host names, IP addresses, +network numbers, netgroups (prefixed with +\(oq+\(cq) +and other aliases. +Again, the value of an item may be negated with the +\(oq\&!\(cq +operator. +Host netgroups are matched using the host (both qualified and unqualified) +and domain members only; the user member is not used when matching. +If you specify a network number without a netmask, +\fBsudo\fR +will query each of the local host's network interfaces and, +if the network number corresponds to one of the hosts's network +interfaces, will use the netmask of that interface. +The netmask may be specified either in standard IP address notation +(e.g., 255.255.255.0 or ffff:ffff:ffff:ffff::), +or CIDR notation (number of bits, e.g., 24 or 64). +A host name may include shell-style wildcards (see the +\fIWildcards\fR +section below), +but unless the +\fRhost name\fR +command on your machine returns the fully +qualified host name, you'll need to use the +\fIfqdn\fR +option for wildcards to be useful. +Note that +\fBsudo\fR +only inspects actual network interfaces; this means that IP address +127.0.0.1 (localhost) will never match. +Also, the host name +\(lqlocalhost\(rq +will only match if that is the actual host name, which is usually +only the case for non-networked systems. +.nf +.sp +.RS 0n +digest ::= [A-Fa-f0-9]+ | + [[A-Za-z0-9\+/=]+ + +Digest_Spec ::= "sha224" ':' digest | + "sha256" ':' digest | + "sha384" ':' digest | + "sha512" ':' digest + +Cmnd_List ::= Cmnd | + Cmnd ',' Cmnd_List + +command name ::= file name | + file name args | + file name '""' + +Cmnd ::= Digest_Spec? '!'* command name | + '!'* directory | + '!'* "sudoedit" | + '!'* Cmnd_Alias +.RE +.fi +.PP +A +\fRCmnd_List\fR +is a list of one or more command names, directories, and other aliases. +A command name is a fully qualified file name which may include +shell-style wildcards (see the +\fIWildcards\fR +section below). +A simple file name allows the user to run the command with any +arguments he/she wishes. +However, you may also specify command line arguments (including +wildcards). +Alternately, you can specify +\fR\&""\fR +to indicate that the command +may only be run +\fBwithout\fR +command line arguments. +A directory is a +fully qualified path name ending in a +\(oq/\(cq. +When you specify a directory in a +\fRCmnd_List\fR, +the user will be able to run any file within that directory +(but not in any sub-directories therein). +.PP +If a +\fRCmnd\fR +has associated command line arguments, then the arguments +in the +\fRCmnd\fR +must match exactly those given by the user on the command line +(or match the wildcards if there are any). +Note that the following characters must be escaped with a +\(oq\e\(cq +if they are used in command arguments: +\(oq,\&\(cq, +\(oq:\&\(cq, +\(oq=\&\(cq, +\(oq\e\(cq. +The built-in command +\(lq\fRsudoedit\fR\(rq +is used to permit a user to run +\fBsudo\fR +with the +\fB\-e\fR +option (or as +\fBsudoedit\fR). +It may take command line arguments just as a normal command does. +Note that +\(lq\fRsudoedit\fR\(rq +is a command built into +\fBsudo\fR +itself and must be specified in the +\fIsudoers\fR +file without a leading path. +.PP +If a +\fRcommand name\fR +is prefixed with a +\fRDigest_Spec\fR, +the command will only match successfully if it can be verified +using the specified SHA-2 digest. +The following digest formats are supported: sha224, sha256, sha384 and sha512. +The string may be specified in either hex or base64 format +(base64 is more compact). +There are several utilities capable of generating SHA-2 digests in hex +format such as openssl, shasum, sha224sum, sha256sum, sha384sum, sha512sum. +.PP +For example, using openssl: +.nf +.sp +.RS 0n +$ openssl dgst -sha224 /bin/ls +SHA224(/bin/ls)= 118187da8364d490b4a7debbf483004e8f3e053ec954309de2c41a25 +.RE +.fi +.PP +It is also possible to use openssl to generate base64 output: +.nf +.sp +.RS 0n +$ openssl dgst -binary -sha224 /bin/ls | openssl base64 +EYGH2oNk1JC0p9679IMATo8+BT7JVDCd4sQaJQ== +.RE +.fi +.PP +Warning, if the user has write access to the command itself (directly or via a +\fBsudo\fR +command), it may be possible for the user to replace the command after the +digest check has been performed but before the command is executed. +A similar race condition exists on systems that lack the +fexecve(2) +system call when the directory in which the command is located +is writable by the user. +See the description of the +\fIfdexec\fR +setting for more information on how +\fBsudo\fR +executes commands that have an associated digest. +.PP +Command digests are only supported by version 1.8.7 or higher. +.SS "Defaults" +Certain configuration options may be changed from their default +values at run-time via one or more +\fRDefault_Entry\fR +lines. +These may affect all users on any host, all users on a specific host, a +specific user, a specific command, or commands being run as a specific user. +Note that per-command entries may not include command line arguments. +If you need to specify arguments, define a +\fRCmnd_Alias\fR +and reference +that instead. +.nf +.sp +.RS 0n +Default_Type ::= 'Defaults' | + 'Defaults' '@' Host_List | + 'Defaults' ':' User_List | + 'Defaults' '!' Cmnd_List | + 'Defaults' '>' Runas_List + +Default_Entry ::= Default_Type Parameter_List + +Parameter_List ::= Parameter | + Parameter ',' Parameter_List + +Parameter ::= Parameter '=' Value | + Parameter '+=' Value | + Parameter '-=' Value | + '!'* Parameter +.RE +.fi +.PP +Parameters may be +\fBflags\fR, +\fBinteger\fR +values, +\fBstrings\fR, +or +\fBlists\fR. +Flags are implicitly boolean and can be turned off via the +\(oq\&!\(cq +operator. +Some integer, string and list parameters may also be +used in a boolean context to disable them. +Values may be enclosed +in double quotes +(\&"") +when they contain multiple words. +Special characters may be escaped with a backslash +(\(oq\e\(cq). +.PP +Lists have two additional assignment operators, +\fR+=\fR +and +\fR-=\fR. +These operators are used to add to and delete from a list respectively. +It is not an error to use the +\fR-=\fR +operator to remove an element +that does not exist in a list. +.PP +Defaults entries are parsed in the following order: generic, host, +user and runas Defaults first, then command defaults. +If there are multiple Defaults settings of the same type, the last +matching setting is used. +The following Defaults settings are parsed before all others since +they may affect subsequent entries: +\fIfqdn\fR, +\fIgroup_plugin\fR, +\fIrunas_default\fR, +\fIsudoers_locale\fR. +.PP +See +\fISUDOERS OPTIONS\fR +for a list of supported Defaults parameters. +.SS "User specification" +.nf +.RS 0n +User_Spec ::= User_List Host_List '=' Cmnd_Spec_List \e + (':' Host_List '=' Cmnd_Spec_List)* + +Cmnd_Spec_List ::= Cmnd_Spec | + Cmnd_Spec ',' Cmnd_Spec_List + +Cmnd_Spec ::= Runas_Spec? Option_Spec* Tag_Spec* Cmnd + +Runas_Spec ::= '(' Runas_List? (':' Runas_List)? ')' + +.ie \n(SL \{\ +.ie \n(PS Option_Spec ::= (SELinux_Spec | Solaris_Priv_Spec | Date_Spec | Timeout_Spec) +.el Option_Spec ::= (SELinux_Spec | Date_Spec | Timeout_Spec) +.\} +.el \{\ +.ie \n(PS Option_Spec ::= (Solaris_Priv_Spec | Date_Spec | Timeout_Spec) +.el Option_Spec ::= (Date_Spec | Timeout_Spec) +.\} + +.if \n(SL \{\ +SELinux_Spec ::= ('ROLE=role' | 'TYPE=type') + +.\} +.if \n(PS \{\ +Solaris_Priv_Spec ::= ('PRIVS=privset' | 'LIMITPRIVS=privset') + +.\} +Date_Spec ::= ('NOTBEFORE=timestamp' | 'NOTAFTER=timestamp') + +Timeout_Spec ::= 'TIMEOUT=timeout' + +Tag_Spec ::= ('EXEC:' | 'NOEXEC:' | 'FOLLOW:' | 'NOFOLLOW' | + 'LOG_INPUT:' | 'NOLOG_INPUT:' | 'LOG_OUTPUT:' | + 'NOLOG_OUTPUT:' | 'MAIL:' | 'NOMAIL:' | 'PASSWD:' | + 'NOPASSWD:' | 'SETENV:' | 'NOSETENV:') +.RE +.fi +.PP +A +\fBuser specification\fR +determines which commands a user may run +(and as what user) on specified hosts. +By default, commands are +run as +\fBroot\fR, +but this can be changed on a per-command basis. +.PP +The basic structure of a user specification is +\(lqwho where = (as_whom) what\(rq. +Let's break that down into its constituent parts: +.SS "Runas_Spec" +A +\fRRunas_Spec\fR +determines the user and/or the group that a command +may be run as. +A fully-specified +\fRRunas_Spec\fR +consists of two +\fRRunas_List\fRs +(as defined above) separated by a colon +(\(oq:\&\(cq) +and enclosed in a set of parentheses. +The first +\fRRunas_List\fR +indicates +which users the command may be run as via +\fBsudo\fR's +\fB\-u\fR +option. +The second defines a list of groups that can be specified via +\fBsudo\fR's +\fB\-g\fR +option in addition to any of the target user's groups. +If both +\fRRunas_List\fRs +are specified, the command may be run with any combination of users +and groups listed in their respective +\fRRunas_List\fRs. +If only the first is specified, the command may be run as any user +in the list but no +\fB\-g\fR +option +may be specified. +If the first +\fRRunas_List\fR +is empty but the +second is specified, the command may be run as the invoking user +with the group set to any listed in the +\fRRunas_List\fR. +If both +\fRRunas_List\fRs +are empty, the command may only be run as the invoking user. +If no +\fRRunas_Spec\fR +is specified the command may be run as +\fBroot\fR +and +no group may be specified. +.PP +A +\fRRunas_Spec\fR +sets the default for the commands that follow it. +What this means is that for the entry: +.nf +.sp +.RS 0n +dgb boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm +.RE +.fi +.PP +The user +\fBdgb\fR +may run +\fI/bin/ls\fR, +\fI/bin/kill\fR, +and +\fI/usr/bin/lprm\fR +on the host +boulder\(embut +only as +\fBoperator\fR. +E.g., +.nf +.sp +.RS 0n +$ sudo -u operator /bin/ls +.RE +.fi +.PP +It is also possible to override a +\fRRunas_Spec\fR +later on in an entry. +If we modify the entry like so: +.nf +.sp +.RS 0n +dgb boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm +.RE +.fi +.PP +Then user +\fBdgb\fR +is now allowed to run +\fI/bin/ls\fR +as +\fBoperator\fR, +but +\fI/bin/kill\fR +and +\fI/usr/bin/lprm\fR +as +\fBroot\fR. +.PP +We can extend this to allow +\fBdgb\fR +to run +\fR/bin/ls\fR +with either +the user or group set to +\fBoperator\fR: +.nf +.sp +.RS 0n +dgb boulder = (operator : operator) /bin/ls, (root) /bin/kill,\e + /usr/bin/lprm +.RE +.fi +.PP +Note that while the group portion of the +\fRRunas_Spec\fR +permits the +user to run as command with that group, it does not force the user +to do so. +If no group is specified on the command line, the command +will run with the group listed in the target user's password database +entry. +The following would all be permitted by the sudoers entry above: +.nf +.sp +.RS 0n +$ sudo -u operator /bin/ls +$ sudo -u operator -g operator /bin/ls +$ sudo -g operator /bin/ls +.RE +.fi +.PP +In the following example, user +\fBtcm\fR +may run commands that access +a modem device file with the dialer group. +.nf +.sp +.RS 0n +tcm boulder = (:dialer) /usr/bin/tip, /usr/bin/cu,\e + /usr/local/bin/minicom +.RE +.fi +.PP +Note that in this example only the group will be set, the command +still runs as user +\fBtcm\fR. +E.g.\& +.nf +.sp +.RS 0n +$ sudo -g dialer /usr/bin/cu +.RE +.fi +.PP +Multiple users and groups may be present in a +\fRRunas_Spec\fR, +in which case the user may select any combination of users and groups via the +\fB\-u\fR +and +\fB\-g\fR +options. +In this example: +.nf +.sp +.RS 0n +alan ALL = (root, bin : operator, system) ALL +.RE +.fi +.PP +user +\fBalan\fR +may run any command as either user root or bin, +optionally setting the group to operator or system. +.SS "Option_Spec" +A +\fRCmnd\fR +may have zero or more options associated with it. +Options may consist of +.if \n(SL \{\ +SELinux roles and/or types, +.\} +.if \n(PS \{\ +Solaris privileges sets, +.\} +start and/or end dates and command timeouts. +Once an option is set for a +\fRCmnd\fR, +subsequent +\fRCmnd\fRs +in the +\fRCmnd_Spec_List\fR, +inherit that option unless it is overridden by another option. +.if \n(SL \{\ +.SS "SELinux_Spec" +On systems with SELinux support, +\fIsudoers\fR +file entries may optionally have an SELinux role and/or type associated +with a command. +If a role or +type is specified with the command it will override any default values +specified in +\fIsudoers\fR. +A role or type specified on the command line, +however, will supersede the values in +\fIsudoers\fR. +.\} +.if \n(PS \{\ +.SS "Solaris_Priv_Spec" +On Solaris systems, +\fIsudoers\fR +file entries may optionally specify Solaris privilege set and/or limit +privilege set associated with a command. +If privileges or limit privileges are specified with the command +it will override any default values specified in +\fIsudoers\fR. +.PP +A privilege set is a comma-separated list of privilege names. +The +ppriv(1) +command can be used to list all privileges known to the system. +For example: +.nf +.sp +.RS 0n +$ ppriv -l +.RE +.fi +.PP +In addition, there are several +\(lqspecial\(rq +privilege strings: +.TP 10n +none +the empty set +.TP 10n +all +the set of all privileges +.TP 10n +zone +the set of all privileges available in the current zone +.TP 10n +basic +the default set of privileges normal users are granted at login time +.PP +Privileges can be excluded from a set by prefixing the privilege +name with either an +\(oq\&!\(cq +or +\(oq\-\(cq +character. +.\} +.SS "Date_Spec" +\fBsudoers\fR +rules can be specified with a start and end date via the +\fRNOTBEFORE\fR +and +\fRNOTAFTER\fR +settings. +The time stamp must be specified in +\fIGeneralized Time\fR +as defined by RFC 4517. +The format is effectively +\fRyyyymmddHHMMSSZ\fR +where the minutes and seconds are optional. +The +\(oqZ\(cq +suffix indicates that the time stamp is in Coordinated Universal Time (UTC). +It is also possible to specify a timezone offset from UTC in hours +and minutes instead of a +\(oqZ\(cq. +For example, +\(oq-0500\(cq +would correspond to Eastern Standard time in the US. +As an extension, if no +\(oqZ\(cq +or timezone offset is specified, local time will be used. +.PP +The following are all valid time stamps: +.nf +.sp +.RS 4n +20170214083000Z +2017021408Z +20160315220000-0500 +20151201235900 +.RE +.fi +.SS "Timeout_Spec" +A command may have a timeout associated with it. +If the timeout expires before the command has exited, the +command will be terminated. +The timeout may be specified in combinations of days, hours, +minutes and seconds with a single-letter case-insensitive suffix +that indicates the unit of time. +For example, a timeout of 7 days, 8 hours, 30 minutes and +10 seconds would be written as +\fR7d8h30m10s\fR. +If a number is specified without a unit, seconds are assumed. +Any of the days, minutes, hours or seconds may be omitted. +The order must be from largest to smallest unit and a unit +may not be specified more than once. +.PP +The following are all +\fIvalid\fR +timeout values: +\fR7d8h30m10s\fR, +\fR14d\fR, +\fR8h30m\fR, +\fR600s\fR, +\fR3600\fR. +The following are +\fIinvalid\fR +timeout values: +\fR12m2w1d\fR, +\fR30s10m4h\fR, +\fR1d2d3h\fR. +.PP +This option is only supported by version 1.8.20 or higher. +.SS "Tag_Spec" +A command may have zero or more tags associated with it. +The following tag values are supported: +\fREXEC\fR, +\fRNOEXEC\fR, +\fRFOLLOW\fR, +\fRNOFOLLOW\fR, +\fRLOG_INPUT\fR, +\fRNOLOG_INPUT\fR, +\fRLOG_OUTPUT\fR, +\fRNOLOG_OUTPUT\fR, +\fRMAIL\fR, +\fRNOMAIL\fR, +\fRPASSWD\fR, +\fRNOPASSWD\fR, +\fRSETENV\fR, +and +\fRNOSETENV\fR. +Once a tag is set on a +\fRCmnd\fR, +subsequent +\fRCmnd\fRs +in the +\fRCmnd_Spec_List\fR, +inherit the tag unless it is overridden by the opposite tag (in other words, +\fRPASSWD\fR +overrides +\fRNOPASSWD\fR +and +\fRNOEXEC\fR +overrides +\fREXEC\fR). +.TP 2n +\fIEXEC\fR and \fINOEXEC\fR +.sp +If +\fBsudo\fR +has been compiled with +\fInoexec\fR +support and the underlying operating system supports it, the +\fRNOEXEC\fR +tag can be used to prevent a dynamically-linked executable from +running further commands itself. +.sp +In the following example, user +\fBaaron\fR +may run +\fI/usr/bin/more\fR +and +\fI/usr/bin/vi\fR +but shell escapes will be disabled. +.nf +.sp +.RS 2n +aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi +.RE +.fi +.RS 2n +.sp +See the +\fIPreventing shell escapes\fR +section below for more details on how +\fRNOEXEC\fR +works and whether or not it will work on your system. +.RE +.TP 2n +\fIFOLLOW\fR and \fINOFOLLOW\fR +Starting with version 1.8.15, +\fBsudoedit\fR +will not open a file that is a symbolic link unless the +\fIsudoedit_follow\fR +option is enabled. +The +\fIFOLLOW\fR +and +\fINOFOLLOW\fR +tags override the value of +\fIsudoedit_follow\fR +and can be used to permit (or deny) the editing of symbolic links +on a per-command basis. +These tags are only effective for the +\fIsudoedit\fR +command and are ignored for all other commands. +.TP 2n +\fILOG_INPUT\fR and \fINOLOG_INPUT\fR +.sp +These tags override the value of the +\fIlog_input\fR +option on a per-command basis. +For more information, see the description of +\fIlog_input\fR +in the +\fISUDOERS OPTIONS\fR +section below. +.TP 2n +\fILOG_OUTPUT\fR and \fINOLOG_OUTPUT\fR +.sp +These tags override the value of the +\fIlog_output\fR +option on a per-command basis. +For more information, see the description of +\fIlog_output\fR +in the +\fISUDOERS OPTIONS\fR +section below. +.TP 2n +\fIMAIL\fR and \fINOMAIL\fR +.sp +These tags provide fine-grained control over whether +mail will be sent when a user runs a command by +overriding the value of the +\fImail_all_cmnds\fR +option on a per-command basis. +They have no effect when +\fBsudo\fR +is run with the +\fB\-l\fR +or +\fB\-v\fR +options. +A +\fINOMAIL\fR +tag will also override the +\fImail_always\fR +and +\fImail_no_perms\fR +options. +For more information, see the descriptions of +\fImail_all_cmnds\fR, +\fImail_always\fR, +and +\fImail_no_perms\fR +in the +\fISUDOERS OPTIONS\fR +section below. +.TP 2n +\fIPASSWD\fR and \fINOPASSWD\fR +.sp +By default, +\fBsudo\fR +requires that a user authenticate him or herself +before running a command. +This behavior can be modified via the +\fRNOPASSWD\fR +tag. +Like a +\fRRunas_Spec\fR, +the +\fRNOPASSWD\fR +tag sets +a default for the commands that follow it in the +\fRCmnd_Spec_List\fR. +Conversely, the +\fRPASSWD\fR +tag can be used to reverse things. +For example: +.nf +.sp +.RS 2n +ray rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm +.RE +.fi +.RS 2n +.sp +would allow the user +\fBray\fR +to run +\fI/bin/kill\fR, +\fI/bin/ls\fR, +and +\fI/usr/bin/lprm\fR +as +\fBroot\fR +on the machine rushmore without authenticating himself. +If we only want +\fBray\fR +to be able to +run +\fI/bin/kill\fR +without a password the entry would be: +.nf +.sp +.RS 2n +ray rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm +.RE +.fi +.sp +Note, however, that the +\fRPASSWD\fR +tag has no effect on users who are in the group specified by the +\fIexempt_group\fR +option. +.sp +By default, if the +\fRNOPASSWD\fR +tag is applied to any of the entries for a user on the current host, +he or she will be able to run +\(lq\fRsudo -l\fR\(rq +without a password. +Additionally, a user may only run +\(lq\fRsudo -v\fR\(rq +without a password if the +\fRNOPASSWD\fR +tag is present for all a user's entries that pertain to the current host. +This behavior may be overridden via the +\fIverifypw\fR +and +\fIlistpw\fR +options. +.RE +.TP 2n +\fISETENV\fR and \fINOSETENV\fR +.sp +These tags override the value of the +\fIsetenv\fR +option on a per-command basis. +Note that if +\fRSETENV\fR +has been set for a command, the user may disable the +\fIenv_reset\fR +option from the command line via the +\fB\-E\fR +option. +Additionally, environment variables set on the command +line are not subject to the restrictions imposed by +\fIenv_check\fR, +\fIenv_delete\fR, +or +\fIenv_keep\fR. +As such, only trusted users should be allowed to set variables in this manner. +If the command matched is +\fBALL\fR, +the +\fRSETENV\fR +tag is implied for that command; this default may be overridden by use of the +\fRNOSETENV\fR +tag. +.SS "Wildcards" +\fBsudo\fR +allows shell-style +\fIwildcards\fR +(aka meta or glob characters) +to be used in host names, path names and command line arguments in the +\fIsudoers\fR +file. +Wildcard matching is done via the +glob(3) +and +fnmatch(3) +functions as specified by +IEEE Std 1003.1 (\(lqPOSIX.1\(rq). +.TP 10n +\fR*\fR +Matches any set of zero or more characters (including white space). +.TP 10n +\fR\&?\fR +Matches any single character (including white space). +.TP 10n +\fR[...]\fR +Matches any character in the specified range. +.TP 10n +\fR[!...]\fR +Matches any character +\fInot\fR +in the specified range. +.TP 10n +\fR\ex\fR +For any character +\(oqx\(cq, +evaluates to +\(oqx\(cq. +This is used to escape special characters such as: +\(oq*\(cq, +\(oq\&?\(cq, +\(oq[\&\(cq, +and +\(oq]\&\(cq. +.PP +\fBNote that these are not regular expressions.\fR +Unlike a regular expression there is no way to match one or more +characters within a range. +.PP +Character classes may be used if your system's +glob(3) +and +fnmatch(3) +functions support them. +However, because the +\(oq:\&\(cq +character has special meaning in +\fIsudoers\fR, +it must be +escaped. +For example: +.nf +.sp +.RS 4n +/bin/ls [[\e:\&alpha\e:\&]]* +.RE +.fi +.PP +Would match any file name beginning with a letter. +.PP +Note that a forward slash +(\(oq/\(cq) +will +\fInot\fR +be matched by +wildcards used in the file name portion of the command. +This is to make a path like: +.nf +.sp +.RS 4n +/usr/bin/* +.RE +.fi +.PP +match +\fI/usr/bin/who\fR +but not +\fI/usr/bin/X11/xterm\fR. +.PP +When matching the command line arguments, however, a slash +\fIdoes\fR +get matched by wildcards since command line arguments may contain +arbitrary strings and not just path names. +.PP +\fBWildcards in command line arguments should be used with care.\fR +.br +Command line arguments are matched as a single, concatenated string. +This mean a wildcard character such as +\(oq\&?\(cq +or +\(oq*\(cq +will match across word boundaries, which may be unexpected. +For example, while a sudoers entry like: +.nf +.sp +.RS 4n +%operator ALL = /bin/cat /var/log/messages* +.RE +.fi +.PP +will allow command like: +.nf +.sp +.RS 4n +$ sudo cat /var/log/messages.1 +.RE +.fi +.PP +It will also allow: +.nf +.sp +.RS 4n +$ sudo cat /var/log/messages /etc/shadow +.RE +.fi +.PP +which is probably not what was intended. +In most cases it is better to do command line processing +outside of the +\fIsudoers\fR +file in a scripting language. +.SS "Exceptions to wildcard rules" +The following exceptions apply to the above rules: +.TP 10n +\fR\&""\fR +If the empty string +\fR\&""\fR +is the only command line argument in the +\fIsudoers\fR +file entry it means that command is not allowed to be run with +\fIany\fR +arguments. +.TP 10n +sudoedit +Command line arguments to the +\fIsudoedit\fR +built-in command should always be path names, so a forward slash +(\(oq/\(cq) +will not be matched by a wildcard. +.SS "Including other files from within sudoers" +It is possible to include other +\fIsudoers\fR +files from within the +\fIsudoers\fR +file currently being parsed using the +\fR#include\fR +and +\fR#includedir\fR +directives. +.PP +This can be used, for example, to keep a site-wide +\fIsudoers\fR +file in addition to a local, per-machine file. +For the sake of this example the site-wide +\fIsudoers\fR +file will be +\fI/etc/sudoers\fR +and the per-machine one will be +\fI/etc/sudoers.local\fR. +To include +\fI/etc/sudoers.local\fR +from within +\fI/etc/sudoers\fR +we would use the +following line in +\fI/etc/sudoers\fR: +.nf +.sp +.RS 4n +#include /etc/sudoers.local +.RE +.fi +.PP +When +\fBsudo\fR +reaches this line it will suspend processing of the current file +(\fI/etc/sudoers\fR) +and switch to +\fI/etc/sudoers.local\fR. +Upon reaching the end of +\fI/etc/sudoers.local\fR, +the rest of +\fI/etc/sudoers\fR +will be processed. +Files that are included may themselves include other files. +A hard limit of 128 nested include files is enforced to prevent include +file loops. +.PP +If the path to the include file is not fully-qualified (does not +begin with a +\(oq/\(cq), +it must be located in the same directory as the sudoers file it was +included from. +For example, if +\fI/etc/sudoers\fR +contains the line: +.nf +.sp +.RS 4n +\fR#include sudoers.local\fR +.RE +.fi +.PP +the file that will be included is +\fI/etc/sudoers.local\fR. +.PP +The file name may also include the +\fR%h\fR +escape, signifying the short form of the host name. +In other words, if the machine's host name is +\(lqxerxes\(rq, +then +.nf +.sp +.RS 4n +#include /etc/sudoers.%h +.RE +.fi +.PP +will cause +\fBsudo\fR +to include the file +\fI/etc/sudoers.xerxes\fR. +.PP +The +\fR#includedir\fR +directive can be used to create a +\fIsudoers.d\fR +directory that the system package manager can drop +\fIsudoers\fR +file rules into as part of package installation. +For example, given: +.nf +.sp +.RS 4n +#includedir /etc/sudoers.d +.RE +.fi +.PP +\fBsudo\fR +will suspend processing of the current file and read each file in +\fI/etc/sudoers.d\fR, +skipping file names that end in +\(oq~\(cq +or contain a +\(oq.\&\(cq +character to avoid causing problems with package manager or editor +temporary/backup files. +Files are parsed in sorted lexical order. +That is, +\fI/etc/sudoers.d/01_first\fR +will be parsed before +\fI/etc/sudoers.d/10_second\fR. +Be aware that because the sorting is lexical, not numeric, +\fI/etc/sudoers.d/1_whoops\fR +would be loaded +\fIafter\fR +\fI/etc/sudoers.d/10_second\fR. +Using a consistent number of leading zeroes in the file names can be used +to avoid such problems. +After parsing the files in the directory, control returns to the +file that contained the +\fR#includedir\fR +directive. +.PP +Note that unlike files included via +\fR#include\fR, +\fBvisudo\fR +will not edit the files in a +\fR#includedir\fR +directory unless one of them contains a syntax error. +It is still possible to run +\fBvisudo\fR +with the +\fB\-f\fR +flag to edit the files directly, but this will not catch the +redefinition of an +\fIalias\fR +that is also present in a different file. +.SS "Other special characters and reserved words" +The pound sign +(\(oq#\(cq) +is used to indicate a comment (unless it is part of a #include +directive or unless it occurs in the context of a user name and is +followed by one or more digits, in which case it is treated as a +uid). +Both the comment character and any text after it, up to the end of +the line, are ignored. +.PP +The reserved word +\fBALL\fR +is a built-in +\fIalias\fR +that always causes a match to succeed. +It can be used wherever one might otherwise use a +\fRCmnd_Alias\fR, +\fRUser_Alias\fR, +\fRRunas_Alias\fR, +or +\fRHost_Alias\fR. +You should not try to define your own +\fIalias\fR +called +\fBALL\fR +as the built-in alias will be used in preference to your own. +Please note that using +\fBALL\fR +can be dangerous since in a command context, it allows the user to run +\fIany\fR +command on the system. +.PP +An exclamation point +(\(oq\&!\(cq) +can be used as a logical +\fInot\fR +operator in a list or +\fIalias\fR +as well as in front of a +\fRCmnd\fR. +This allows one to exclude certain values. +For the +\(oq\&!\(cq +operator to be effective, there must be something for it to exclude. +For example, to match all users except for root one would use: +.nf +.sp +.RS 4n +ALL,!root +.RE +.fi +.PP +If the +\fBALL\fR, +is omitted, as in: +.nf +.sp +.RS 4n +!root +.RE +.fi +.PP +it would explicitly deny root but not match any other users. +This is different from a true +\(lqnegation\(rq +operator. +.PP +Note, however, that using a +\(oq\&!\(cq +in conjunction with the built-in +\fBALL\fR +alias to allow a user to run +\(lqall but a few\(rq +commands rarely works as intended (see +\fISECURITY NOTES\fR +below). +.PP +Long lines can be continued with a backslash +(\(oq\e\(cq) +as the last character on the line. +.PP +White space between elements in a list as well as special syntactic +characters in a +\fIUser Specification\fR +(\(oq=\&\(cq, +\(oq:\&\(cq, +\(oq(\&\(cq, +\(oq)\&\(cq) +is optional. +.PP +The following characters must be escaped with a backslash +(\(oq\e\(cq) +when used as part of a word (e.g., a user name or host name): +\(oq\&!\(cq, +\(oq=\&\(cq, +\(oq:\&\(cq, +\(oq,\&\(cq, +\(oq(\&\(cq, +\(oq)\&\(cq, +\(oq\e\(cq. +.SH "SUDOERS OPTIONS" +\fBsudo\fR's +behavior can be modified by +\fRDefault_Entry\fR +lines, as explained earlier. +A list of all supported Defaults parameters, grouped by type, are listed below. +.PP +\fBBoolean Flags\fR: +.TP 18n +always_query_group_plugin +If a +\fIgroup_plugin\fR +is configured, use it to resolve groups of the form %group as long +as there is not also a system group of the same name. +Normally, only groups of the form %:group are passed to the +\fIgroup_plugin\fR. +This flag is +\fIoff\fR +by default. +.TP 18n +always_set_home +If enabled, +\fBsudo\fR +will set the +\fRHOME\fR +environment variable to the home directory of the target user +(which is root unless the +\fB\-u\fR +option is used). +This effectively means that the +\fB\-H\fR +option is always implied. +Note that by default, +\fRHOME\fR +will be set to the home directory of the target user when the +\fIenv_reset\fR +option is enabled, so +\fIalways_set_home\fR +only has an effect for configurations where either +\fIenv_reset\fR +is disabled or +\fRHOME\fR +is present in the +\fIenv_keep\fR +list. +This flag is +\fIoff\fR +by default. +.TP 18n +authenticate +If set, users must authenticate themselves via a password (or other +means of authentication) before they may run commands. +This default may be overridden via the +\fRPASSWD\fR +and +\fRNOPASSWD\fR +tags. +This flag is +\fIon\fR +by default. +.TP 18n +case_insensitive_group +If enabled, group names in +\fIsudoers\fR +will be matched in a case insensitive manner. +This may be necessary when users are stored in LDAP or AD. +This flag is +\fIon\fR +by default. +.TP 18n +case_insensitive_user +If enabled, user names in +\fIsudoers\fR +will be matched in a case insensitive manner. +This may be necessary when groups are stored in LDAP or AD. +This flag is +\fIon\fR +by default. +.TP 18n +closefrom_override +If set, the user may use +\fBsudo\fR's +\fB\-C\fR +option which overrides the default starting point at which +\fBsudo\fR +begins closing open file descriptors. +This flag is +\fIoff\fR +by default. +.TP 18n +compress_io +If set, and +\fBsudo\fR +is configured to log a command's input or output, +the I/O logs will be compressed using +\fBzlib\fR. +This flag is +\fIon\fR +by default when +\fBsudo\fR +is compiled with +\fBzlib\fR +support. +.TP 18n +exec_background +By default, +\fBsudo\fR +runs a command as the foreground process as long as +\fBsudo\fR +itself is running in the foreground. +When the +\fIexec_background\fR +flag is enabled and the command is being run in a pty (due to I/O logging +or the +\fIuse_pty\fR +flag), the command will be run as a background process. +Attempts to read from the controlling terminal (or to change terminal +settings) will result in the command being suspended with the +\fRSIGTTIN\fR +signal (or +\fRSIGTTOU\fR +in the case of terminal settings). +If this happens when +\fBsudo\fR +is a foreground process, the command will be granted the controlling terminal +and resumed in the foreground with no user intervention required. +The advantage of initially running the command in the background is that +\fBsudo\fR +need not read from the terminal unless the command explicitly requests it. +Otherwise, any terminal input must be passed to the command, whether it +has required it or not (the kernel buffers terminals so it is not possible +to tell whether the command really wants the input). +This is different from historic +\fIsudo\fR +behavior or when the command is not being run in a pty. +.sp +For this to work seamlessly, the operating system must support the +automatic restarting of system calls. +Unfortunately, not all operating systems do this by default, +and even those that do may have bugs. +For example, macOS fails to restart the +\fBtcgetattr\fR() +and +\fBtcsetattr\fR() +system calls (this is a bug in macOS). +Furthermore, because this behavior depends on the command stopping with the +\fRSIGTTIN\fR +or +\fRSIGTTOU\fR +signals, programs that catch these signals and suspend themselves +with a different signal (usually +\fRSIGTOP\fR) +will not be automatically foregrounded. +Some versions of the linux +su(1) +command behave this way. +This flag is +\fIoff\fR +by default. +.sp +This setting is only supported by version 1.8.7 or higher. +It has no effect unless I/O logging is enabled or the +\fIuse_pty\fR +flag is enabled. +.TP 18n +env_editor +If set, +\fBvisudo\fR +will use the value of the +\fRSUDO_EDITOR\fR, +\fRVISUAL\fR +or +\fREDITOR\fR +environment variables before falling back on the default editor list. +Note that this may create a security hole as it allows the user to +run any arbitrary command as root without logging. +A safer alternative is to place a colon-separated list of editors +in the +\fIeditor\fR +variable. +\fBvisudo\fR +will then only use +\fRSUDO_EDITOR\fR, +\fRVISUAL\fR +or +\fREDITOR\fR +if they match a value specified in +\fIeditor\fR. +If the +\fIenv_reset\fR +flag is enabled, the +\fRSUDO_EDITOR\fR, +\fRVISUAL\fR +and/or +\fREDITOR\fR +environment variables must be present in the +\fIenv_keep\fR +list for the +\fIenv_editor\fR +flag to function when +\fBvisudo\fR +is invoked via +\fBsudo\fR. +This flag is +\fI@env_editor@\fR +by default. +.TP 18n +env_reset +If set, +\fBsudo\fR +will run the command in a minimal environment containing the +\fRTERM\fR, +\fRPATH\fR, +\fRHOME\fR, +\fRMAIL\fR, +\fRSHELL\fR, +\fRLOGNAME\fR, +\fRUSER\fR +and +\fRSUDO_*\fR +variables. +Any variables in the caller's environment or in the file specified +by the +\fIrestricted_env_file\fR +option that match the +\fRenv_keep\fR +and +\fRenv_check\fR +lists are then added, followed by any variables present in the file +specified by the +\fIenv_file\fR +option (if any). +The contents of the +\fRenv_keep\fR +and +\fRenv_check\fR +lists, as modified by global Defaults parameters in +\fIsudoers\fR, +are displayed when +\fBsudo\fR +is run by root with the +\fB\-V\fR +option. +If the +\fIsecure_path\fR +option is set, its value will be used for the +\fRPATH\fR +environment variable. +This flag is +\fI@env_reset@\fR +by default. +.TP 18n +fast_glob +Normally, +\fBsudo\fR +uses the +glob(3) +function to do shell-style globbing when matching path names. +However, since it accesses the file system, +glob(3) +can take a long time to complete for some patterns, especially +when the pattern references a network file system that is mounted +on demand (auto mounted). +The +\fIfast_glob\fR +option causes +\fBsudo\fR +to use the +fnmatch(3) +function, which does not access the file system to do its matching. +The disadvantage of +\fIfast_glob\fR +is that it is unable to match relative path names such as +\fI./ls\fR +or +\fI../bin/ls\fR. +This has security implications when path names that include globbing +characters are used with the negation operator, +\(oq!\&\(cq, +as such rules can be trivially bypassed. +As such, this option should not be used when the +\fIsudoers\fR +file contains rules that contain negated path names which include globbing +characters. +This flag is +\fIoff\fR +by default. +.TP 18n +fqdn +Set this flag if you want to put fully qualified host names in the +\fIsudoers\fR +file when the local host name (as returned by the +\fRhostname\fR +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 option is only effective when the +\(lqcanonical\(rq +host name, as returned by the +\fBgetaddrinfo\fR() +or +\fBgethostbyname\fR() +function, is a fully-qualified domain name. +This is usually the case when the system is configured to use DNS +for host name resolution. +.sp +If the system is configured to use the +\fI/etc/hosts\fR +file in preference to DNS, the +\(lqcanonical\(rq +host name may not be fully-qualified. +The order that sources are queried for host name resolution +is usually specified in the +\fI@nsswitch_conf@\fR, +\fI@netsvc_conf@\fR, +\fI/etc/host.conf\fR, +or, in some cases, +\fI/etc/resolv.conf\fR +file. +In the +\fI/etc/hosts\fR +file, the first host name of the entry is considered to be the +\(lqcanonical\(rq +name; subsequent names are aliases that are not used by +\fBsudoers\fR. +For example, the following hosts file line for the machine +\(lqxyzzy\(rq +has the fully-qualified domain name as the +\(lqcanonical\(rq +host name, and the short version as an alias. +.sp +.RS 24n +192.168.1.1 xyzzy.sudo.ws xyzzy +.RE +.RS 18n +.sp +If the machine's hosts file entry is not formatted properly, the +\fIfqdn\fR +option will not be effective if it is queried before DNS. +.sp +Beware that when using DNS for host name resolution, turning on +\fIfqdn\fR +requires +\fBsudoers\fR +to make DNS lookups which renders +\fBsudo\fR +unusable if DNS stops working (for example if the machine is disconnected +from the network). +Also note that just like with the hosts file, you must use the +\(lqcanonical\(rq +name as DNS knows it. +That is, you may not use a host alias +(\fRCNAME\fR +entry) +due to performance issues and the fact that there is no way to get all +aliases from DNS. +.sp +This flag is +\fI@fqdn@\fR +by default. +.RE +.TP 18n +ignore_audit_errors +Allow commands to be run even if +\fBsudoers\fR +cannot write to the audit log. +If enabled, an audit log write failure is not treated as a fatal error. +If disabled, a command may only be run after the audit event is successfully +written. +This flag is only effective on systems for which +\fBsudoers\fR +supports audit logging, including +FreeBSD, +Linux, macOS and Solaris. +This flag is +\fIon\fR +by default. +.TP 18n +ignore_dot +If set, +\fBsudo\fR +will ignore "." or "" (both denoting current directory) in the +\fRPATH\fR +environment variable; the +\fRPATH\fR +itself is not modified. +This flag is +\fI@ignore_dot@\fR +by default. +.TP 18n +ignore_iolog_errors +Allow commands to be run even if +\fBsudoers\fR +cannot write to the I/O log. +If enabled, an I/O log write failure is not treated as a fatal error. +If disabled, the command will be terminated if the I/O log cannot be written to. +This flag is +\fIoff\fR +by default. +.TP 18n +ignore_logfile_errors +Allow commands to be run even if +\fBsudoers\fR +cannot write to the log file. +If enabled, a log file write failure is not treated as a fatal error. +If disabled, a command may only be run after the log file entry is successfully +written. +This flag only has an effect when +\fBsudoers\fR +is configured to use file-based logging via the +\fIlogfile\fR +option. +This flag is +\fIon\fR +by default. +.TP 18n +ignore_local_sudoers +If set via LDAP, parsing of +\fI@sysconfdir@/sudoers\fR +will be skipped. +This is intended for Enterprises that wish to prevent the usage of local +sudoers files so that only LDAP is used. +This thwarts the efforts of rogue operators who would attempt to add roles to +\fI@sysconfdir@/sudoers\fR. +When this option is present, +\fI@sysconfdir@/sudoers\fR +does not even need to exist. +Since this option tells +\fBsudo\fR +how to behave when no specific LDAP entries have been matched, this +sudoOption is only meaningful for the +\fRcn=defaults\fR +section. +This flag is +\fIoff\fR +by default. +.TP 18n +ignore_unknown_defaults +If set, +\fBsudo\fR +will not produce a warning if it encounters an unknown Defaults entry +in the +\fIsudoers\fR +file or an unknown sudoOption in LDAP. +This flag is +\fIoff\fR +by default. +.TP 18n +insults +If set, +\fBsudo\fR +will insult users when they enter an incorrect password. +This flag is +\fI@insults@\fR +by default. +.TP 18n +log_host +If set, the host name will be logged in the (non-syslog) +\fBsudo\fR +log file. +This flag is +\fIoff\fR +by default. +.TP 18n +log_input +If set, +\fBsudo\fR +will run the command in a pseudo-tty and log all user input. +If the standard input is not connected to the user's tty, due to +I/O redirection or because the command is part of a pipeline, that +input is also captured and stored in a separate log file. +Anything sent to the standard input will be consumed, regardless of +whether or not the command run via +\fBsudo\fR +is actually reading the standard input. +This may have unexpected results when using +\fBsudo\fR +in a shell script that expects to process the standard input. +For more information about I/O logging, see the +\fII/O LOG FILES\fR +section. +This flag is +\fIoff\fR +by default. +.TP 18n +log_output +If set, +\fBsudo\fR +will run the command in a pseudo-tty and log all output that is sent +to the screen, similar to the +script(1) +command. +For more information about I/O logging, see the +\fII/O LOG FILES\fR +section. +This flag is +\fIoff\fR +by default. +.TP 18n +log_year +If set, the four-digit year will be logged in the (non-syslog) +\fBsudo\fR +log file. +This flag is +\fIoff\fR +by default. +.TP 18n +long_otp_prompt +When validating with a One Time Password (OTP) scheme such as +\fBS/Key\fR +or +\fBOPIE\fR, +a two-line prompt is used to make it easier +to cut and paste the challenge to a local window. +It's not as pretty as the default but some people find it more convenient. +This flag is +\fI@long_otp_prompt@\fR +by default. +.TP 18n +mail_all_cmnds +Send mail to the +\fImailto\fR +user every time a user attempts to run a command via +\fBsudo\fR +(this includes +\fBsudoedit\fR). +No mail will be sent if the user runs +\fBsudo\fR +with the +\fB\-l\fR +or +\fB\-v\fR +option unless there is an authentication error and the +\fImail_badpass\fR +flag is also set. +This flag is +\fIoff\fR +by default. +.TP 18n +mail_always +Send mail to the +\fImailto\fR +user every time a user runs +\fBsudo\fR. +This flag is +\fIoff\fR +by default. +.TP 18n +mail_badpass +Send mail to the +\fImailto\fR +user if the user running +\fBsudo\fR +does not enter the correct password. +If the command the user is attempting to run is not permitted by +\fBsudoers\fR +and one of the +\fImail_all_cmnds\fR, +\fImail_always\fR, +\fImail_no_host\fR, +\fImail_no_perms\fR +or +\fImail_no_user\fR +flags are set, this flag will have no effect. +This flag is +\fIoff\fR +by default. +.TP 18n +mail_no_host +If set, mail will be sent to the +\fImailto\fR +user if the invoking user exists in the +\fIsudoers\fR +file, but is not allowed to run commands on the current host. +This flag is +\fI@mail_no_host@\fR +by default. +.TP 18n +mail_no_perms +If set, mail will be sent to the +\fImailto\fR +user if the invoking user is allowed to use +\fBsudo\fR +but the command they are trying is not listed in their +\fIsudoers\fR +file entry or is explicitly denied. +This flag is +\fI@mail_no_perms@\fR +by default. +.TP 18n +mail_no_user +If set, mail will be sent to the +\fImailto\fR +user if the invoking user is not in the +\fIsudoers\fR +file. +This flag is +\fI@mail_no_user@\fR +by default. +.TP 18n +match_group_by_gid +By default, +\fBsudoers\fR +will look up each group the user is a member of by group ID to +determine the group name (this is only done once). +The resulting list of the user's group names is used when matching +groups listed in the +\fIsudoers\fR +file. +This works well on systems where the number of groups listed in the +\fIsudoers\fR +file is larger than the number of groups a typical user belongs to. +On systems where group lookups are slow, where users may belong +to a large number of groups, and where the number of groups listed +in the +\fIsudoers\fR +file is relatively small, it may be prohibitively expensive and +running commands via +\fBsudo\fR +may take longer than normal. +On such systems it may be faster to use the +\fImatch_group_by_gid\fR +flag to avoid resolving the user's group IDs to group names. +In this case, +\fBsudoers\fR +must look up any group name listed in the +\fIsudoers\fR +file and use the group ID instead of the group name when determining +whether the user is a member of the group. +.sp +Note that if +\fImatch_group_by_gid\fR +is enabled, group database lookups performed by +\fBsudoers\fR +will be keyed by group name as opposed to group ID. +On systems where there are multiple sources for the group database, +it is possible to have conflicting group names or group IDs in the local +\fI/etc/group\fR +file and the remote group database. +On such systems, enabling or disabling +\fImatch_group_by_gid\fR +can be used to choose whether group database queries are performed +by name (enabled) or ID (disabled), which may aid in working around +group entry conflicts. +.sp +The +\fImatch_group_by_gid\fR +flag has no effect when +\fIsudoers\fR +data is stored in LDAP. +This flag is +\fIoff\fR +by default. +.sp +This setting is only supported by version 1.8.18 or higher. +.TP 18n +netgroup_tuple +If set, netgroup lookups will be performed using the full netgroup +tuple: host name, user name and domain (if one is set). +Historically, +\fBsudo\fR +only matched the user name and domain for netgroups used in a +\fRUser_List\fR +and only matched the host name and domain for netgroups used in a +\fRHost_List\fR. +This flag is +\fIoff\fR +by default. +.TP 18n +noexec +If set, all commands run via +\fBsudo\fR +will behave as if the +\fRNOEXEC\fR +tag has been set, unless overridden by an +\fREXEC\fR +tag. +See the description of +\fIEXEC and NOEXEC\fR +above as well as the +\fIPreventing shell escapes\fR +section at the end of this manual. +This flag is +\fIoff\fR +by default. +.TP 18n +pam_session +On systems that use PAM for authentication, +\fBsudo\fR +will create a new PAM session for the command to be run in. +Disabling +\fIpam_session\fR +may be needed on older PAM implementations or on operating systems where +opening a PAM session changes the utmp or wtmp files. +If PAM session support is disabled, resource limits may not be updated +for the command being run. +If +\fIpam_session\fR, +\fIpam_setcred\fR, +and +\fIuse_pty\fR +are disabled and I/O logging has not been configured, +\fBsudo\fR +will execute the command directly instead of running it as a child +process. +This flag is +\fI@pam_session@\fR +by default. +.sp +This setting is only supported by version 1.8.7 or higher. +.TP 18n +pam_setcred +On systems that use PAM for authentication, +\fBsudo\fR +will attempt to establish credentials for the target user by default, +if supported by the underlying authentication system. +One example of a credential is a Kerberos ticket. +If +\fIpam_session\fR, +\fIpam_setcred\fR, +and +\fIuse_pty\fR +are disabled and I/O logging has not been configured, +\fBsudo\fR +will execute the command directly instead of running it as a child +process. +This flag is +\fIon\fR +by default. +.sp +This setting is only supported by version 1.8.8 or higher. +.TP 18n +passprompt_override +If set, the prompt specified by +\fIpassprompt\fR +or the +\fRSUDO_PROMPT\fR +environment variable will always be used and will replace the +prompt provided by a PAM module or other authentication method. +This flag is +\fIoff\fR +by default. +.TP 18n +path_info +Normally, +\fBsudo\fR +will tell the user when a command could not be +found in their +\fRPATH\fR +environment variable. +Some sites may wish to disable this as it could be used to gather +information on the location of executables that the normal user does +not have access to. +The disadvantage is that if the executable is simply not in the user's +\fRPATH\fR, +\fBsudo\fR +will tell the user that they are not allowed to run it, which can be confusing. +This flag is +\fI@path_info@\fR +by default. +.TP 18n +preserve_groups +By default, +\fBsudo\fR +will initialize the group vector to the list of groups the target user is in. +When +\fIpreserve_groups\fR +is set, the user's existing group vector is left unaltered. +The real and effective group IDs, however, are still set to match the +target user. +This flag is +\fIoff\fR +by default. +.TP 18n +pwfeedback +By default, +\fBsudo\fR +reads the password like most other Unix programs, +by turning off echo until the user hits the return (or enter) key. +Some users become confused by this as it appears to them that +\fBsudo\fR +has hung at this point. +When +\fIpwfeedback\fR +is set, +\fBsudo\fR +will provide visual feedback when the user presses a key. +Note that this does have a security impact as an onlooker may be able to +determine the length of the password being entered. +This flag is +\fIoff\fR +by default. +.TP 18n +requiretty +If set, +\fBsudo\fR +will only run when the user is logged in to a real tty. +When this flag is set, +\fBsudo\fR +can only be run from a login session and not via other means such as +cron(@mansectsu@) +or cgi-bin scripts. +This flag is +\fIoff\fR +by default. +.TP 18n +root_sudo +If set, root is allowed to run +\fBsudo\fR +too. +Disabling this prevents users from +\(lqchaining\(rq +\fBsudo\fR +commands to get a root shell by doing something like +\(lq\fRsudo sudo /bin/sh\fR\(rq. +Note, however, that turning off +\fIroot_sudo\fR +will also prevent root from running +\fBsudoedit\fR. +Disabling +\fIroot_sudo\fR +provides no real additional security; it exists purely for historical reasons. +This flag is +\fI@root_sudo@\fR +by default. +.TP 18n +rootpw +If set, +\fBsudo\fR +will prompt for the root password instead of the password of the invoking user +when running a command or editing a file. +This flag is +\fIoff\fR +by default. +.TP 18n +runaspw +If set, +\fBsudo\fR +will prompt for the password of the user defined by the +\fIrunas_default\fR +option (defaults to +\fR@runas_default@\fR) +instead of the password of the invoking user +when running a command or editing a file. +This flag is +\fIoff\fR +by default. +.TP 18n +set_home +If enabled and +\fBsudo\fR +is invoked with the +\fB\-s\fR +option the +\fRHOME\fR +environment variable will be set to the home directory of the target +user (which is root unless the +\fB\-u\fR +option is used). +This effectively makes the +\fB\-s\fR +option imply +\fB\-H\fR. +Note that +\fRHOME\fR +is already set when the +\fIenv_reset\fR +option is enabled, so +\fIset_home\fR +is only effective for configurations where either +\fIenv_reset\fR +is disabled +or +\fRHOME\fR +is present in the +\fIenv_keep\fR +list. +This flag is +\fIoff\fR +by default. +.TP 18n +set_logname +Normally, +\fBsudo\fR +will set the +\fRLOGNAME\fR +and +\fRUSER\fR +environment variables to the name of the target user (usually root unless the +\fB\-u\fR +option is given). +However, since some programs (including the RCS revision control system) use +\fRLOGNAME\fR +to determine the real identity of the user, it may be desirable to +change this behavior. +This can be done by negating the set_logname option. +Note that +\fIset_logname\fR +will have no effect +if the +\fIenv_reset\fR +option has not been disabled and the +\fIenv_keep\fR +list contains +\fRLOGNAME\fR +or +\fRUSER\fR. +This flag is +\fIon\fR +by default. +.TP 18n +set_utmp +When enabled, +\fBsudo\fR +will create an entry in the utmp (or utmpx) file when a pseudo-tty +is allocated. +A pseudo-tty is allocated by +\fBsudo\fR +when the +\fIlog_input\fR, +\fIlog_output\fR +or +\fIuse_pty\fR +flags are enabled. +By default, the new entry will be a copy of the user's existing utmp +entry (if any), with the tty, time, type and pid fields updated. +This flag is +\fIon\fR +by default. +.TP 18n +setenv +Allow the user to disable the +\fIenv_reset\fR +option from the command line via the +\fB\-E\fR +option. +Additionally, environment variables set via the command line are +not subject to the restrictions imposed by +\fIenv_check\fR, +\fIenv_delete\fR, +or +\fIenv_keep\fR. +As such, only trusted users should be allowed to set variables in this manner. +This flag is +\fIoff\fR +by default. +.TP 18n +shell_noargs +If set and +\fBsudo\fR +is invoked with no arguments it acts as if the +\fB\-s\fR +option had been given. +That is, it runs a shell as root (the shell is determined by the +\fRSHELL\fR +environment variable if it is set, falling back on the shell listed +in the invoking user's /etc/passwd entry if not). +This flag is +\fIoff\fR +by default. +.TP 18n +stay_setuid +Normally, when +\fBsudo\fR +executes a command the real and effective UIDs are set to the target +user (root by default). +This option changes that behavior such that the real UID is left +as the invoking user's UID. +In other words, this makes +\fBsudo\fR +act as a setuid wrapper. +This can be useful on systems that disable some potentially +dangerous functionality when a program is run setuid. +This option is only effective on systems that support either the +setreuid(2) +or +setresuid(2) +system call. +This flag is +\fIoff\fR +by default. +.TP 18n +sudoedit_checkdir +.br +If set, +\fBsudoedit\fR +will check all directory components of the path to be edited for writability +by the invoking user. +Symbolic links will not be followed in writable directories and +\fBsudoedit\fR +will refuse to edit a file located in a writable directory. +These restrictions are not enforced when +\fBsudoedit\fR +is run by root. +On some systems, if all directory components of the path to be edited +are not readable by the target user, +\fBsudoedit\fR +will be unable to edit the file. +This flag is +\fIon\fR +by default. +.sp +This setting was first introduced in version 1.8.15 but initially +suffered from a race condition. +The check for symbolic links in writable intermediate directories +was added in version 1.8.16. +.TP 18n +sudoedit_follow +By default, +\fBsudoedit\fR +will not follow symbolic links when opening files. +The +\fIsudoedit_follow\fR +option can be enabled to allow +\fBsudoedit\fR +to open symbolic links. +It may be overridden on a per-command basis by the +\fIFOLLOW\fR +and +\fINOFOLLOW\fR +tags. +This flag is +\fIoff\fR +by default. +.sp +This setting is only supported by version 1.8.15 or higher. +.TP 18n +syslog_pid +When logging via +syslog(3), +include the process ID in the log entry. +This flag is +\fIoff\fR +by default. +.sp +This setting is only supported by version 1.8.21 or higher. +.TP 18n +targetpw +If set, +\fBsudo\fR +will prompt for the password of the user specified +by the +\fB\-u\fR +option (defaults to +\fRroot\fR) +instead of the password of the invoking user +when running a command or editing a file. +Note that this flag precludes the use of a uid not listed in the passwd +database as an argument to the +\fB\-u\fR +option. +This flag is +\fIoff\fR +by default. +.TP 18n +tty_tickets +If set, users must authenticate on a per-tty basis. +With this flag enabled, +\fBsudo\fR +will use a separate record in the time stamp file for each terminal. +If disabled, a single record is used for all login sessions. +.sp +This option has been superseded by the +\fItimestamp_type\fR +option. +.TP 18n +umask_override +If set, +\fBsudo\fR +will set the umask as specified in the +\fIsudoers\fR +file without modification. +This makes it possible to specify a umask in the +\fIsudoers\fR +file that is more permissive than the user's own umask and matches +historical behavior. +If +\fIumask_override\fR +is not set, +\fBsudo\fR +will set the umask to be the union of the user's umask and what is specified in +\fIsudoers\fR. +This flag is +\fI@umask_override@\fR +by default. +.if \n(BA \{\ +.TP 18n +use_loginclass +If set, +\fBsudo\fR +will apply the defaults specified for the target user's login class +if one exists. +Only available if +\fBsudo\fR +is configured with the +\fR--with-logincap\fR +option. +This flag is +\fIoff\fR +by default. +.\} +.TP 18n +use_netgroups +If set, netgroups (prefixed with +\(oq+\(cq), +may be used in place of a user or host. +For LDAP-based sudoers, netgroup support requires an expensive +sub-string match on the server unless the +\fBNETGROUP_BASE\fR +directive is present in the +\fI@ldap_conf@\fR +file. +If netgroups are not needed, this option can be disabled to reduce the +load on the LDAP server. +This flag is +\fIon\fR +by default. +.TP 18n +use_pty +If set, and +\fBsudo\fR +is running in a terminal, the command will be run in a pseudo-pty +(even if no I/O logging is being done). +If the +\fBsudo\fR +process is not attached to a terminal, +\fIuse_pty\fR +has no effect. +.sp +A malicious program run under +\fBsudo\fR +may be capable of injecting commands into the user's +terminal or running a background process that retains access to the +user's terminal device even after the main program has finished +executing. +By running the command in a separate pseudo-pty, this attack is +no longer possible. +This flag is +\fIoff\fR +by default. +.TP 18n +user_command_timeouts +If set, the user may specify a timeout on the command line. +If the timeout expires before the command has exited, the +command will be terminated. +If a timeout is specified both in the +\fIsudoers\fR +file and on the command line, the smaller of the two timeouts will be used. +See the +\fRTimeout_Spec\fR +section for a description of the timeout syntax. +This flag is +\fIoff\fR +by default. +.sp +This setting is only supported by version 1.8.20 or higher. +.TP 18n +utmp_runas +If set, +\fBsudo\fR +will store the name of the runas user when updating the utmp (or utmpx) file. +By default, +\fBsudo\fR +stores the name of the invoking user. +This flag is +\fIoff\fR +by default. +.TP 18n +visiblepw +By default, +\fBsudo\fR +will refuse to run if the user must enter a password but it is not +possible to disable echo on the terminal. +If the +\fIvisiblepw\fR +flag is set, +\fBsudo\fR +will prompt for a password even when it would be visible on the screen. +This makes it possible to run things like +\(lq\fRssh somehost sudo ls\fR\(rq +since by default, +ssh(1) +does +not allocate a tty when running a command. +This flag is +\fIoff\fR +by default. +.PP +\fBIntegers\fR: +.TP 18n +closefrom +Before it executes a command, +\fBsudo\fR +will close all open file descriptors other than standard input, +standard output and standard error (ie: file descriptors 0-2). +The +\fIclosefrom\fR +option can be used to specify a different file descriptor at which +to start closing. +The default is +\fR3\fR. +.TP 18n +command_timeout +The maximum amount of time a command is allowed to run before +it is terminated. +See the +\fRTimeout_Spec\fR +section for a description of the timeout syntax. +.sp +This setting is only supported by version 1.8.20 or higher. +.TP 18n +maxseq +The maximum sequence number that will be substituted for the +\(lq\fR%{seq}\fR\(rq +escape in the I/O log file (see the +\fIiolog_dir\fR +description below for more information). +While the value substituted for +\(lq\fR%{seq}\fR\(rq +is in base 36, +\fImaxseq\fR +itself should be expressed in decimal. +Values larger than 2176782336 (which corresponds to the +base 36 sequence number +\(lqZZZZZZ\(rq) +will be silently truncated to 2176782336. +The default value is 2176782336. +.sp +Once the local sequence number reaches the value of +\fImaxseq\fR, +it will +\(lqroll over\(rq +to zero, after which +\fBsudoers\fR +will truncate and re-use any existing I/O log path names. +.sp +This setting is only supported by version 1.8.7 or higher. +.TP 18n +passwd_tries +The number of tries a user gets to enter his/her password before +\fBsudo\fR +logs the failure and exits. +The default is +\fR@passwd_tries@\fR. +.TP 18n +syslog_maxlen +On many systems, +syslog(3) +has a relatively small log buffer. +IETF RFC 5424 states that syslog servers must support messages of +at least 480 bytes and should support messages up to 2048 bytes. +By default, +\fBsudoers\fR +creates log messages up to 980 bytes which corresponds to the +historic +BSD +syslog implementation which used a 1024 byte buffer +to store the message, date, hostname and program name. +To prevent syslog messages from being truncated, +\fBsudoers\fR +will split up log messages that are larger than +\fIsyslog_maxlen\fR +bytes. +When a message is split, additional parts will include the string +\(lq(command continued)\(rq +after the user name and before the continued command line arguments. +.sp +This setting is only supported by version 1.8.19 or higher. +.PP +\fBIntegers that can be used in a boolean context\fR: +.TP 18n +loglinelen +Number of characters per line for the file log. +This value is used to decide when to wrap lines for nicer log files. +This has no effect on the syslog log file, only the file log. +The default is +\fR@loglen@\fR +(use 0 or negate the option to disable word wrap). +.TP 18n +passwd_timeout +Number of minutes before the +\fBsudo\fR +password prompt times out, or +\fR0\fR +for no timeout. +The timeout may include a fractional component +if minute granularity is insufficient, for example +\fR2.5\fR. +The +default is +\fR@password_timeout@\fR. +.TP 18n +timestamp_timeout +.br +Number of minutes that can elapse before +\fBsudo\fR +will ask for a passwd again. +The timeout may include a fractional component if +minute granularity is insufficient, for example +\fR2.5\fR. +The default is +\fR@timeout@\fR. +Set this to +\fR0\fR +to always prompt for a password. +If set to a value less than +\fR0\fR +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 +\(lq\fRsudo -v\fR\(rq +and +\(lq\fRsudo -k\fR\(rq +respectively. +.TP 18n +umask +Umask to use when running the command. +Negate this option or set it to 0777 to preserve the user's umask. +The actual umask that is used will be the union of the user's umask +and the value of the +\fIumask\fR +option, which defaults to +\fR@sudo_umask@\fR. +This guarantees +that +\fBsudo\fR +never lowers the umask when running a command. +Note: on systems that use PAM, the default PAM configuration may specify +its own umask which will override the value set in +\fIsudoers\fR. +.PP +\fBStrings\fR: +.TP 18n +authfail_message +Message that is displayed after a user fails to authenticate. +The message may include the +\(oq%d\(cq +escape which will expand to the number of failed password attempts. +If set, it overrides the default message, +\fR%d incorrect password attempt(s)\fR. +.TP 18n +badpass_message +Message that is displayed if a user enters an incorrect password. +The default is +\fR@badpass_message@\fR +unless insults are enabled. +.TP 18n +editor +A colon +(\(oq:\&\(cq) +separated list of editors path names used by +\fBsudoedit\fR +and +\fBvisudo\fR. +For +\fBsudoedit\fR, +this list is used to find an editor when none of the +\fRSUDO_EDITOR\fR, +\fRVISUAL\fR +or +\fREDITOR\fR +environment variables are set to an editor that exists and is executable. +For +\fBvisudo\fR, +it is used as a white list of allowed editors; +\fBvisudo\fR +will choose the editor that matches the user's +\fRSUDO_EDITOR\fR, +\fRVISUAL\fR +or +\fREDITOR\fR +environment variable if possible, or the first editor in the +list that exists and is executable if not. +Unless invoked as +\fBsudoedit\fR, +\fBsudo\fR +does not preserve the +\fRSUDO_EDITOR\fR, +\fRVISUAL\fR +and +\fREDITOR\fR +environment variables by default, even when the +\fIenv_reset\fR +option is enabled. +The default is +\fI@editor@\fR. +.TP 18n +iolog_dir +The top-level directory to use when constructing the path name for +the input/output log directory. +Only used if the +\fIlog_input\fR +or +\fIlog_output\fR +options are enabled or when the +\fRLOG_INPUT\fR +or +\fRLOG_OUTPUT\fR +tags are present for a command. +The session sequence number, if any, is stored in the directory. +The default is +\fI@iolog_dir@\fR. +.sp +The following percent +(\(oq%\(cq) +escape sequences are supported: +.PP +.RS 18n +.PD 0 +.TP 6n +\fR%{seq}\fR +expanded to a monotonically increasing base-36 sequence number, such as 0100A5, +where every two digits are used to form a new directory, e.g., +\fI01/00/A5\fR +.PD +.TP 6n +\fR%{user}\fR +expanded to the invoking user's login name +.TP 6n +\fR%{group}\fR +expanded to the name of the invoking user's real group ID +.TP 6n +\fR%{runas_user}\fR +expanded to the login name of the user the command will +be run as (e.g., root) +.TP 6n +\fR%{runas_group}\fR +expanded to the group name of the user the command will +be run as (e.g., wheel) +.TP 6n +\fR%{hostname}\fR +expanded to the local host name without the domain name +.TP 6n +\fR%{command}\fR +expanded to the base name of the command being run +.PP +In addition, any escape sequences supported by the system's +strftime(3) +function will be expanded. +.sp +To include a literal +\(oq%\(cq +character, the string +\(oq%%\(cq +should be used. +.RE +.TP 18n +iolog_file +The path name, relative to +\fIiolog_dir\fR, +in which to store input/output logs when the +\fIlog_input\fR +or +\fIlog_output\fR +options are enabled or when the +\fRLOG_INPUT\fR +or +\fRLOG_OUTPUT\fR +tags are present for a command. +Note that +\fIiolog_file\fR +may contain directory components. +The default is +\(lq\fR%{seq}\fR\(rq. +.sp +See the +\fIiolog_dir\fR +option above for a list of supported percent +(\(oq%\(cq) +escape sequences. +.sp +In addition to the escape sequences, path names that end in six or +more +\fRX\fRs +will have the +\fRX\fRs +replaced with a unique combination of digits and letters, similar to the +mktemp(3) +function. +.sp +If the path created by concatenating +\fIiolog_dir\fR +and +\fIiolog_file\fR +already exists, the existing I/O log file will be truncated and +overwritten unless +\fIiolog_file\fR +ends in six or +more +\fRX\fRs. +.TP 18n +iolog_flush +If set, +\fBsudo\fR +will flush I/O log data to disk after each write instead of buffering it. +This makes it possible to view the logs in real-time as the program +is executing but may significantly reduce the effectiveness of I/O +log compression. +This flag is +\fIoff\fR +by default. +.sp +This setting is only supported by version 1.8.20 or higher. +.TP 18n +iolog_group +The group name to look up when setting the group ID on new I/O log +files and directories. +If +\fIiolog_group\fR +is not set, +the primary group ID of the user specified by +\fIiolog_user\fR +is used. +If neither +\fIiolog_group\fR +nor +\fIiolog_user\fR +are set, I/O log files and directories are created with group ID 0. +.sp +This setting is only supported by version 1.8.19 or higher. +.TP 18n +iolog_mode +The file mode to use when creating I/O log files. +Mode bits for read and write permissions for owner, group or other +are honored, everything else is ignored. +The file permissions will always include the owner read and +write bits, even if they are not present in the specified mode. +When creating I/O log directories, search (execute) bits are added +to match the read and write bits specified by +\fIiolog_mode\fR. +Defaults to 0600 (read and write by user only). +.sp +This setting is only supported by version 1.8.19 or higher. +.TP 18n +iolog_user +The user name to look up when setting the user and group IDs on new +I/O log files and directories. +If +\fIiolog_group\fR +is set, it will be used instead of the user's primary group ID. +By default, I/O log files and directories are created with user and +group ID 0. +.sp +This setting can be useful when the I/O logs are stored on a Network +File System (NFS) share. +Having a dedicated user own the I/O log files means that +\fBsudoers\fR +does not write to the log files as user ID 0, which is usually +not permitted by NFS. +.sp +This setting is only supported by version 1.8.19 or higher. +.TP 18n +lecture_status_dir +The directory in which +\fBsudo\fR +stores per-user lecture status files. +Once a user has received the lecture, a zero-length file is +created in this directory so that +\fBsudo\fR +will not lecture the user again. +This directory should +\fInot\fR +be cleared when the system reboots. +The default is +\fI@vardir@/lectured\fR. +.if \n(PS \{\ +.TP 18n +limitprivs +The default Solaris limit privileges to use when constructing a new +privilege set for a command. +This bounds all privileges of the executing process. +The default limit privileges may be overridden on a per-command basis in +\fIsudoers\fR. +This option is only available if +\fBsudoers\fR +is built on Solaris 10 or higher. +.\} +.TP 18n +mailsub +Subject of the mail sent to the +\fImailto\fR +user. +The escape +\fR%h\fR +will expand to the host name of the machine. +Default is +\(lq\fR@mailsub@\fR\(rq. +.TP 18n +noexec_file +As of +\fBsudo\fR +version 1.8.1 this option is no longer supported. +The path to the noexec file should now be set in the +sudo.conf(@mansectform@) +file. +.TP 18n +pam_login_service +.br +On systems that use PAM for authentication, this is the service +name used when the +\fB\-i\fR +option is specified. +The default value is +\(lq\fR@pam_login_service@\fR\(rq. +See the description of +\fIpam_service\fR +for more information. +.sp +This setting is only supported by version 1.8.8 or higher. +.TP 18n +pam_service +On systems that use PAM for authentication, the service name +specifies the PAM policy to apply. +This usually corresponds to an entry in the +\fIpam.conf\fR +file or a file in the +\fI/etc/pam.d\fR +directory. +The default value is +\(lq\fRsudo\fR\(rq. +.sp +This setting is only supported by version 1.8.8 or higher. +.TP 18n +passprompt +The default prompt to use when asking for a password; can be overridden via the +\fB\-p\fR +option or the +\fRSUDO_PROMPT\fR +environment variable. +The following percent +(\(oq%\(cq) +escape sequences are supported: +.PP +.RS 18n +.PD 0 +.TP 6n +\fR%H\fR +expanded to the local host name including the domain name +(only if the machine's host name is fully qualified or the +\fIfqdn\fR +option is set) +.PD +.TP 6n +\fR%h\fR +expanded to the local host name without the domain name +.TP 6n +\fR%p\fR +expanded to the user whose password is being asked for (respects the +\fIrootpw\fR, +\fItargetpw\fR +and +\fIrunaspw\fR +flags in +\fIsudoers\fR) +.TP 6n +\fR\&%U\fR +expanded to the login name of the user the command will +be run as (defaults to root) +.TP 6n +\fR%u\fR +expanded to the invoking user's login name +.TP 6n +\fR%%\fR +two consecutive +\fR%\fR +characters are collapsed into a single +\fR%\fR +character +.PP +On systems that use PAM for authentication, +\fIpassprompt\fR +will only be used if the prompt provided by the PAM module matches the string +\(lqPassword: \(rq +or +\(lqusername's Password: \(rq. +This ensures that the +\fIpassprompt\fR +setting does not interfere with challenge-response style authentication. +The +\fIpassprompt_override\fR +flag can be used to change this behavior. +.sp +The default value is +\(lq\fR@passprompt@\fR\(rq. +.RE +.if \n(PS \{\ +.TP 18n +privs +The default Solaris privileges to use when constructing a new +privilege set for a command. +This is passed to the executing process via the inherited privilege set, +but is bounded by the limit privileges. +If the +\fIprivs\fR +option is specified but the +\fIlimitprivs\fR +option is not, the limit privileges of the executing process is set to +\fIprivs\fR. +The default privileges may be overridden on a per-command basis in +\fIsudoers\fR. +This option is only available if +\fBsudoers\fR +is built on Solaris 10 or higher. +.\} +.if \n(SL \{\ +.TP 18n +role +The default SELinux role to use when constructing a new security +context to run the command. +The default role may be overridden on a per-command basis in the +\fIsudoers\fR +file or via command line options. +This option is only available when +\fBsudo\fR +is built with SELinux support. +.\} +.TP 18n +runas_default +The default user to run commands as if the +\fB\-u\fR +option is not specified on the command line. +This defaults to +\fR@runas_default@\fR. +.TP 18n +sudoers_locale +Locale to use when parsing the sudoers file, logging commands, and +sending email. +Note that changing the locale may affect how sudoers is interpreted. +Defaults to +\(lq\fRC\fR\(rq. +.TP 18n +timestamp_type +\fBsudoers\fR +uses per-user time stamp files for credential caching. +The +\fItimestamp_type\fR +option can be used to specify the type of time stamp record used. +It has the following possible values: +.PP +.RS 18n +.PD 0 +.TP 8n +global +A single time stamp record is used for all of a user's login sessions, +regardless of the terminal or parent process ID. +An additional record is used to serialize password prompts when +\fBsudo\fR +is used multiple times in a pipeline, but this does not affect authentication. +.PD +.TP 8n +ppid +A single time stamp record is used for all processes with the same parent +process ID (usually the shell). +Commands run from the same shell (or other common parent process) +will not require a password for +\fItimestamp_timeout\fR +minutes +(\fR@timeout@\fR +by default) +\&. +Commands run via +\fBsudo\fR +with a different parent process ID, for example from a shell script, +will be authenticated separately. +.TP 8n +tty +One time stamp record is used for each terminal, +which means that a user's login sessions are authenticated separately. +If no terminal is present, the behavior is the same as +\fIppid\fR. +Commands run from the same terminal will not require a password for +\fItimestamp_timeout\fR +minutes +(\fR@timeout@\fR +by default) +\&. +.TP 8n +kernel +The time stamp is stored in the kernel as an attribute of the terminal +device. +If no terminal is present, the behavior is the same as +\fIppid\fR. +Negative +\fItimestamp_timeout\fR +values are not supported and positive values are limited to a maximum +of 60 minutes. +This is currently only supported on +OpenBSD. +.PP +The default value is +\fI@timestamp_type@\fR. +.sp +This setting is only supported by version 1.8.21 or higher. +.RE +.TP 18n +timestampdir +The directory in which +\fBsudo\fR +stores its time stamp files. +This directory should be cleared when the system reboots. +The default is +\fI@rundir@/ts\fR. +.TP 18n +timestampowner +The owner of the lecture status directory, time stamp directory and all +files stored therein. +The default is +\fRroot\fR. +.if \n(SL \{\ +.TP 18n +type +The default SELinux type to use when constructing a new security +context to run the command. +The default type may be overridden on a per-command basis in the +\fIsudoers\fR +file or via command line options. +This option is only available when +\fBsudo\fR +is built with SELinux support. +.PP +\fBStrings that can be used in a boolean context\fR: +.TP 14n +env_file +The +\fIenv_file\fR +option specifies the fully qualified path to a file containing variables +to be set in the environment of the program being run. +Entries in this file should either be of the form +\(lq\fRVARIABLE=value\fR\(rq +or +\(lq\fRexport VARIABLE=value\fR\(rq. +The value may optionally be surrounded by single or double quotes. +Variables in this file are only added if the variable does not already +exist in the environment. +This file is considered to be part of the security policy, +its contents are not subject to other +\fBsudo\fR +environment restrictions such as +\fIenv_keep\fR +and +\fIenv_check\fR. +.TP 14n +exempt_group +Users in this group are exempt from password and PATH requirements. +The group name specified should not include a +\fR%\fR +prefix. +This is not set by default. +.TP 14n +fdexec +Determines whether +\fBsudo\fR +will execute a command by its path or by an open file descriptor. +It has the following possible values: +.PP +.RS 14n +.PD 0 +.TP 8n +always +Always execute by file descriptor. +.PD +.TP 8n +never +Never execute by file descriptor. +.TP 8n +digest_only +Only execute by file descriptor if the command has an associated digest +in the +\fIsudoers\fR +file. +.PP +The default value is +\fIdigest_only\fR. +This avoids a time of check versus time of use race condition when +the command is located in a directory writable by the invoking user. +.sp +Note that +\fIfdexec\fR +will change the first element of the argument vector for scripts +($0 in the shell) due to the way the kernel runs script interpreters. +Instead of being a normal path, it will refer to a file descriptor. +For example, +\fI/dev/fd/4\fR +on Solaris and +\fI/proc/self/fd/4\fR +on Linux. +A workaround is to use the +\fRSUDO_COMMAND\fR +environment variable instead. +.sp +The +\fIfdexec\fR +setting is only used when the command is matched by path name. +It has no effect if the command is matched by the built-in +\fBALL\fR +alias. +.sp +This setting is only supported by version 1.8.20 or higher. +If the operating system does not support the +fexecve(2) +system call, this setting has no effect. +.RE +.TP 14n +group_plugin +A string containing a +\fBsudoers\fR +group plugin with optional arguments. +The string should consist of the plugin +path, either fully-qualified or relative to the +\fI@PLUGINDIR@\fR +directory, followed by any configuration arguments the plugin requires. +These arguments (if any) will be passed to the plugin's initialization function. +If arguments are present, the string must be enclosed in double quotes +(\&""). +.sp +For more information see +\fIGROUP PROVIDER PLUGINS\fR. +.TP 14n +lecture +This option controls when a short lecture will be printed along with +the password prompt. +It has the following possible values: +.PP +.RS 14n +.PD 0 +.TP 8n +always +Always lecture the user. +.PD +.TP 8n +never +Never lecture the user. +.TP 8n +once +Only lecture the user the first time they run +\fBsudo\fR. +.PP +If no value is specified, a value of +\fIonce\fR +is implied. +Negating the option results in a value of +\fInever\fR +being used. +The default value is +\fI@lecture@\fR. +.RE +.TP 14n +lecture_file +Path to a file containing an alternate +\fBsudo\fR +lecture that will be used in place of the standard lecture if the named +file exists. +By default, +\fBsudo\fR +uses a built-in lecture. +.TP 14n +listpw +This option controls when a password will be required when a user runs +\fBsudo\fR +with the +\fB\-l\fR +option. +It has the following possible values: +.PP +.RS 14n +.PD 0 +.TP 10n +all +All the user's +\fIsudoers\fR +file entries for the current host must have +the +\fRNOPASSWD\fR +flag set to avoid entering a password. +.PD +.TP 10n +always +The user must always enter a password to use the +\fB\-l\fR +option. +.TP 10n +any +At least one of the user's +\fIsudoers\fR +file entries for the current host +must have the +\fRNOPASSWD\fR +flag set to avoid entering a password. +.TP 10n +never +The user need never enter a password to use the +\fB\-l\fR +option. +.PP +If no value is specified, a value of +\fIany\fR +is implied. +Negating the option results in a value of +\fInever\fR +being used. +The default value is +\fIany\fR. +.RE +.TP 14n +logfile +Path to the +\fBsudo\fR +log file (not the syslog log file). +Setting a path turns on logging to a file; +negating this option turns it off. +By default, +\fBsudo\fR +logs via syslog. +.TP 14n +mailerflags +Flags to use when invoking mailer. +Defaults to +\fB\-t\fR. +.TP 14n +mailerpath +Path to mail program used to send warning mail. +Defaults to the path to sendmail found at configure time. +.TP 14n +mailfrom +Address to use for the +\(lqfrom\(rq +address when sending warning and error mail. +The address should be enclosed in double quotes +(\&"") +to protect against +\fBsudo\fR +interpreting the +\fR@\fR +sign. +Defaults to the name of the user running +\fBsudo\fR. +.TP 14n +mailto +Address to send warning and error mail to. +The address should be enclosed in double quotes +(\&"") +to protect against +\fBsudo\fR +interpreting the +\fR@\fR +sign. +Defaults to +\fR@mailto@\fR. +.TP 14n +restricted_env_file +The +\fIrestricted_env_file\fR +option specifies the fully qualified path to a file containing variables +to be set in the environment of the program being run. +Entries in this file should either be of the form +\(lq\fRVARIABLE=value\fR\(rq +or +\(lq\fRexport VARIABLE=value\fR\(rq. +The value may optionally be surrounded by single or double quotes. +Variables in this file are only added if the variable does not already +exist in the environment. +Unlike +\fIenv_file\fR, +the file's contents are not trusted and are processed in a manner +similar to that of the invoking user's environment. +If +\fIenv_reset\fR +is enabled, variables in the file will only be added if they are +matched by either the +\fIenv_check\fR +or +\fIenv_keep\fR +list. +If +\fIenv_reset\fR +is disabled, variables in the file are added as long as they +are not matched by the +\fIenv_delete\fR +list. +In either case, the contents of +\fIrestricted_env_file\fR +are processed before the contents of +\fIenv_file\fR. +.TP 14n +secure_path +Path used for every command run from +\fBsudo\fR. +If you don't trust the +people running +\fBsudo\fR +to have a sane +\fRPATH\fR +environment variable you may want to use this. +Another use is if you want to have the +\(lqroot path\(rq +be separate from the +\(lquser path\(rq. +Users in the group specified by the +\fIexempt_group\fR +option are not affected by +\fIsecure_path\fR. +This option is @secure_path@ by default. +.TP 14n +syslog +Syslog facility if syslog is being used for logging (negate to +disable syslog logging). +Defaults to +\fR@logfac@\fR. +.sp +The following syslog facilities are supported: +\fBauthpriv\fR +(if your +OS supports it), +\fBauth\fR, +\fBdaemon\fR, +\fBuser\fR, +\fBlocal0\fR, +\fBlocal1\fR, +\fBlocal2\fR, +\fBlocal3\fR, +\fBlocal4\fR, +\fBlocal5\fR, +\fBlocal6\fR, +and +\fBlocal7\fR. +.TP 14n +syslog_badpri +.br +Syslog priority to use when the user is not allowed to run a command or +when authentication is unsuccessful. +Defaults to +\fR@badpri@\fR. +.sp +The following syslog priorities are supported: +\fBalert\fR, +\fBcrit\fR, +\fBdebug\fR, +\fBemerg\fR, +\fBerr\fR, +\fBinfo\fR, +\fBnotice\fR, +\fBwarning\fR, +and +\fBnone\fR. +Negating the option or setting it to a value of +\fBnone\fR +will disable logging of unsuccessful commands. +.TP 14n +syslog_goodpri +Syslog priority to use when the user is allowed to run a command and +authentication is successful. +Defaults to +\fR@goodpri@\fR. +.sp +See +\fIsyslog_badpri\fR +for the list of supported syslog priorities. +Negating the option or setting it to a value of +\fBnone\fR +will disable logging of successful commands. +.TP 14n +verifypw +This option controls when a password will be required when a user runs +\fBsudo\fR +with the +\fB\-v\fR +option. +It has the following possible values: +.PP +.RS 14n +.PD 0 +.TP 8n +all +All the user's +\fIsudoers\fR +file entries for the current host must have the +\fRNOPASSWD\fR +flag set to avoid entering a password. +.PD +.TP 8n +always +The user must always enter a password to use the +\fB\-v\fR +option. +.TP 8n +any +At least one of the user's +\fIsudoers\fR +file entries for the current host must have the +\fRNOPASSWD\fR +flag set to avoid entering a password. +.TP 8n +never +The user need never enter a password to use the +\fB\-v\fR +option. +.PP +If no value is specified, a value of +\fIall\fR +is implied. +Negating the option results in a value of +\fInever\fR +being used. +The default value is +\fIall\fR. +.RE +.PP +\fBLists that can be used in a boolean context\fR: +.\} +.TP 18n +env_check +Environment variables to be removed from the user's environment +unless they are considered +\(lqsafe\(rq. +For all variables except +\fRTZ\fR, +\(lqsafe\(rq +means that the variable's value does not contain any +\(oq%\(cq +or +\(oq/\(cq +characters. +This can be used to guard against printf-style format vulnerabilities +in poorly-written programs. +The +\fRTZ\fR +variable is considered unsafe if any of the following are true: +.PP +.RS 18n +.PD 0 +.TP 3n +\fB\(bu\fR +It consists of a fully-qualified path name, +optionally prefixed with a colon +(\(oq:\&\(cq), +that does not match the location of the +\fIzoneinfo\fR +directory. +.PD +.TP 3n +\fB\(bu\fR +It contains a +\fI..\fR +path element. +.TP 3n +\fB\(bu\fR +It contains white space or non-printable characters. +.TP 3n +\fB\(bu\fR +It is longer than the value of +\fRPATH_MAX\fR. +.PP +The argument may be a double-quoted, space-separated list or a +single value without double-quotes. +The list can be replaced, added to, deleted from, or disabled by using +the +\fR=\fR, +\fR+=\fR, +\fR-=\fR, +and +\fR\&!\fR +operators respectively. +Regardless of whether the +\fRenv_reset\fR +option is enabled or disabled, variables specified by +\fRenv_check\fR +will be preserved in the environment if they pass the aforementioned check. +The global list of environment variables to check is displayed when +\fBsudo\fR +is run by root with +the +\fB\-V\fR +option. +.RE +.TP 18n +env_delete +Environment variables to be removed from the user's environment when the +\fIenv_reset\fR +option is not in effect. +The argument may be a double-quoted, space-separated list or a +single value without double-quotes. +The list can be replaced, added to, deleted from, or disabled by using the +\fR=\fR, +\fR+=\fR, +\fR-=\fR, +and +\fR\&!\fR +operators respectively. +The global list of environment variables to remove is displayed when +\fBsudo\fR +is run by root with the +\fB\-V\fR +option. +Note that many operating systems will remove potentially dangerous +variables from the environment of any setuid process (such as +\fBsudo\fR). +.TP 18n +env_keep +Environment variables to be preserved in the user's environment when the +\fIenv_reset\fR +option is in effect. +This allows fine-grained control over the environment +\fBsudo\fR-spawned +processes will receive. +The argument may be a double-quoted, space-separated list or a +single value without double-quotes. +The list can be replaced, added to, deleted from, or disabled by using the +\fR=\fR, +\fR+=\fR, +\fR-=\fR, +and +\fR\&!\fR +operators respectively. +The global list of variables to keep +is displayed when +\fBsudo\fR +is run by root with the +\fB\-V\fR +option. +.SH "GROUP PROVIDER PLUGINS" +The +\fBsudoers\fR +plugin supports its own plugin interface to allow non-Unix +group lookups which can query a group source other +than the standard Unix group database. +This can be used to implement support for the +\fRnonunix_group\fR +syntax described earlier. +.PP +Group provider plugins are specified via the +\fIgroup_plugin\fR +Defaults setting. +The argument to +\fIgroup_plugin\fR +should consist of the plugin path, either fully-qualified or relative to the +\fI@PLUGINDIR@\fR +directory, followed by any configuration options the plugin requires. +These options (if specified) will be passed to the plugin's initialization +function. +If options are present, the string must be enclosed in double quotes +(\&""). +.PP +The following group provider plugins are installed by default: +.TP 10n +group_file +The +\fIgroup_file\fR +plugin supports an alternate group file that uses the same syntax as the +\fI/etc/group\fR +file. +The path to the group file should be specified as an option +to the plugin. +For example, if the group file to be used is +\fI/etc/sudo-group\fR: +.nf +.sp +.RS 10n +Defaults group_plugin="group_file.so /etc/sudo-group" +.RE +.fi +.TP 10n +system_group +The +\fIsystem_group\fR +plugin supports group lookups via the standard C library functions +\fBgetgrnam\fR() +and +\fBgetgrid\fR(). +This plugin can be used in instances where the user belongs to +groups not present in the user's supplemental group vector. +This plugin takes no options: +.nf +.sp +.RS 10n +Defaults group_plugin=system_group.so +.RE +.fi +.PP +The group provider plugin API is described in detail in +sudo_plugin(@mansectform@). +.SH "LOG FORMAT" +\fBsudoers\fR +can log events using either +syslog(3) +or a simple log file. +The log format is almost identical in both cases. +.SS "Accepted command log entries" +Commands that sudo runs are logged using the following format (split +into multiple lines for readability): +.nf +.sp +.RS 4n +date hostname progname: username : TTY=ttyname ; PWD=cwd ; \e + USER=runasuser ; GROUP=runasgroup ; TSID=logid ; \e + ENV=env_vars COMMAND=command +.RE +.fi +.PP +Where the fields are as follows: +.TP 14n +date +The date the command was run. +Typically, this is in the format +\(lqMMM, DD, HH:MM:SS\(rq. +If logging via +syslog(3), +the actual date format is controlled by the syslog daemon. +If logging to a file and the +\fIlog_year\fR +option is enabled, +the date will also include the year. +.TP 14n +hostname +The name of the host +\fBsudo\fR +was run on. +This field is only present when logging via +syslog(3). +.TP 14n +progname +The name of the program, usually +\fIsudo\fR +or +\fIsudoedit\fR. +This field is only present when logging via +syslog(3). +.TP 14n +username +The login name of the user who ran +\fBsudo\fR. +.TP 14n +ttyname +The short name of the terminal (e.g., +\(lqconsole\(rq, +\(lqtty01\(rq, +or +\(lqpts/0\(rq) +\fBsudo\fR +was run on, or +\(lqunknown\(rq +if there was no terminal present. +.TP 14n +cwd +The current working directory that +\fBsudo\fR +was run in. +.TP 14n +runasuser +The user the command was run as. +.TP 14n +runasgroup +The group the command was run as if one was specified on the command line. +.TP 14n +logid +An I/O log identifier that can be used to replay the command's output. +This is only present when the +\fIlog_input\fR +or +\fIlog_output\fR +option is enabled. +.TP 14n +env_vars +A list of environment variables specified on the command line, +if specified. +.TP 14n +command +The actual command that was executed. +.PP +Messages are logged using the locale specified by +\fIsudoers_locale\fR, +which defaults to the +\(lq\fRC\fR\(rq +locale. +.SS "Denied command log entries" +If the user is not allowed to run the command, the reason for the denial +will follow the user name. +Possible reasons include: +.TP 3n +user NOT in sudoers +The user is not listed in the +\fIsudoers\fR +file. +.TP 3n +user NOT authorized on host +The user is listed in the +\fIsudoers\fR +file but is not allowed to run commands on the host. +.TP 3n +command not allowed +The user is listed in the +\fIsudoers\fR +file for the host but they are not allowed to run the specified command. +.TP 3n +3 incorrect password attempts +The user failed to enter their password after 3 tries. +The actual number of tries will vary based on the number of +failed attempts and the value of the +\fIpasswd_tries\fR +option. +.TP 3n +a password is required +\fBsudo\fR's +\fB\-n\fR +option was specified but a password was required. +.TP 3n +sorry, you are not allowed to set the following environment variables +The user specified environment variables on the command line that +were not allowed by +\fIsudoers\fR. +.SS "Error log entries" +If an error occurs, +\fBsudoers\fR +will log a message and, in most cases, send a message to the +administrator via email. +Possible errors include: +.TP 3n +parse error in @sysconfdir@/sudoers near line N +\fBsudoers\fR +encountered an error when parsing the specified file. +In some cases, the actual error may be one line above or below the +line number listed, depending on the type of error. +.TP 3n +problem with defaults entries +The +\fIsudoers\fR +file contains one or more unknown Defaults settings. +This does not prevent +\fBsudo\fR +from running, but the +\fIsudoers\fR +file should be checked using +\fBvisudo\fR. +.TP 3n +timestamp owner (username): \&No such user +The time stamp directory owner, as specified by the +\fItimestampowner\fR +setting, could not be found in the password database. +.TP 3n +unable to open/read @sysconfdir@/sudoers +The +\fIsudoers\fR +file could not be opened for reading. +This can happen when the +\fIsudoers\fR +file is located on a remote file system that maps user ID 0 to +a different value. +Normally, +\fBsudoers\fR +tries to open the +\fIsudoers\fR +file using group permissions to avoid this problem. +Consider either changing the ownership of +\fI@sysconfdir@/sudoers\fR +or adding an argument like +\(lqsudoers_uid=N\(rq +(where +\(oqN\(cq +is the user ID that owns the +\fIsudoers\fR +file) to the end of the +\fBsudoers\fR +\fRPlugin\fR +line in the +sudo.conf(@mansectform@) +file. +.TP 3n +unable to stat @sysconfdir@/sudoers +The +\fI@sysconfdir@/sudoers\fR +file is missing. +.TP 3n +@sysconfdir@/sudoers is not a regular file +The +\fI@sysconfdir@/sudoers\fR +file exists but is not a regular file or symbolic link. +.TP 3n +@sysconfdir@/sudoers is owned by uid N, should be 0 +The +\fIsudoers\fR +file has the wrong owner. +If you wish to change the +\fIsudoers\fR +file owner, please add +\(lqsudoers_uid=N\(rq +(where +\(oqN\(cq +is the user ID that owns the +\fIsudoers\fR +file) to the +\fBsudoers\fR +\fRPlugin\fR +line in the +sudo.conf(@mansectform@) +file. +.TP 3n +@sysconfdir@/sudoers is world writable +The permissions on the +\fIsudoers\fR +file allow all users to write to it. +The +\fIsudoers\fR +file must not be world-writable, the default file mode +is 0440 (readable by owner and group, writable by none). +The default mode may be changed via the +\(lqsudoers_mode\(rq +option to the +\fBsudoers\fR +\fRPlugin\fR +line in the +sudo.conf(@mansectform@) +file. +.TP 3n +@sysconfdir@/sudoers is owned by gid N, should be 1 +The +\fIsudoers\fR +file has the wrong group ownership. +If you wish to change the +\fIsudoers\fR +file group ownership, please add +\(lqsudoers_gid=N\(rq +(where +\(oqN\(cq +is the group ID that owns the +\fIsudoers\fR +file) to the +\fBsudoers\fR +\fRPlugin\fR +line in the +sudo.conf(@mansectform@) +file. +.TP 3n +unable to open @rundir@/ts/username +\fBsudoers\fR +was unable to read or create the user's time stamp file. +This can happen when +\fItimestampowner\fR +is set to a user other than root and the mode on +\fI@rundir@\fR +is not searchable by group or other. +The default mode for +\fI@rundir@\fR +is 0711. +.TP 3n +unable to write to @rundir@/ts/username +\fBsudoers\fR +was unable to write to the user's time stamp file. +.TP 3n +@rundir@/ts is owned by uid X, should be Y +The time stamp directory is owned by a user other than +\fItimestampowner\fR. +This can occur when the value of +\fItimestampowner\fR +has been changed. +\fBsudoers\fR +will ignore the time stamp directory until the owner is corrected. +.TP 3n +@rundir@/ts is group writable +The time stamp directory is group-writable; it should be writable only by +\fItimestampowner\fR. +The default mode for the time stamp directory is 0700. +\fBsudoers\fR +will ignore the time stamp directory until the mode is corrected. +.SS "Notes on logging via syslog" +By default, +\fBsudoers\fR +logs messages via +syslog(3). +The +\fIdate\fR, +\fIhostname\fR, +and +\fIprogname\fR +fields are added by the system's +\fBsyslog\fR() +function, not +\fBsudoers\fR +itself. +As such, they may vary in format on different systems. +.PP +The maximum size of syslog messages varies from system to system. +The +\fIsyslog_maxlen\fR +setting can be used to change the maximum syslog message size +from the default value of 980 bytes. +For more information, see the description of +\fIsyslog_maxlen\fR. +.SS "Notes on logging to a file" +If the +\fIlogfile\fR +option is set, +\fBsudoers\fR +will log to a local file, such as +\fI/var/log/sudo\fR. +When logging to a file, +\fBsudoers\fR +uses a format similar to +syslog(3), +with a few important differences: +.TP 5n +1.\& +The +\fIprogname\fR +and +\fIhostname\fR +fields are not present. +.TP 5n +2.\& +If the +\fIlog_year\fR +option is enabled, +the date will also include the year. +.TP 5n +3.\& +Lines that are longer than +\fIloglinelen\fR +characters (80 by default) are word-wrapped and continued on the +next line with a four character indent. +This makes entries easier to read for a human being, but makes it +more difficult to use +grep(1) +on the log files. +If the +\fIloglinelen\fR +option is set to 0 (or negated with a +\(oq\&!\(cq), +word wrap will be disabled. +.SH "I/O LOG FILES" +When I/O logging is enabled, +\fBsudo\fR +will run the command in a pseudo-tty and log all user input and/or output, +depending on which options are enabled. +I/O is logged to the directory specified by the +\fIiolog_dir\fR +option +(\fI@iolog_dir@\fR +by default) +using a unique session ID that is included in the +\fBsudo\fR +log line, prefixed with +\(lq\fRTSID=\fR\(rq. +The +\fIiolog_file\fR +option may be used to control the format of the session ID. +.PP +Each I/O log is stored in a separate directory that contains the +following files: +.TP 10n +\fIlog\fR +a text file containing the time the command was run, the name of the user +who ran +\fBsudo\fR, +the name of the target user, the name of the target group (optional), +the terminal that +\fBsudo\fR +was run from, the number of rows and columns of the terminal, +the working directory the command was run from and the path name of +the command itself (with arguments if present) +.TP 10n +\fItiming\fR +a log of the amount of time between, and the number of bytes in, each +I/O log entry (used for session playback) +.TP 10n +\fIttyin\fR +input from the user's tty (what the user types) +.TP 10n +\fIstdin\fR +input from a pipe or file +.TP 10n +\fIttyout\fR +output from the pseudo-tty (what the command writes to the screen) +.TP 10n +\fIstdout\fR +standard output to a pipe or redirected to a file +.TP 10n +\fIstderr\fR +standard error to a pipe or redirected to a file +.PP +All files other than +\fIlog\fR +are compressed in gzip format unless the +\fIcompress_io\fR +flag has been disabled. +Due to buffering, it is not normally possible to display the I/O logs in +real-time as the program is executing +The I/O log data will not be complete until the program run by +\fBsudo\fR +has exited or has been terminated by a signal. +The +\fIiolog_flush\fR +flag can be used to disable buffering, in which case I/O log data +is written to disk as soon as it is available. +The output portion of an I/O log file can be viewed with the +sudoreplay(@mansectsu@) +utility, which can also be used to list or search the available logs. +.PP +Note that user input may contain sensitive information such as +passwords (even if they are not echoed to the screen), which will +be stored in the log file unencrypted. +In most cases, logging the command output via +\fIlog_output\fR +or +\fRLOG_OUTPUT\fR +is all that is required. +.PP +Since each session's I/O logs are stored in a separate directory, +traditional log rotation utilities cannot be used to limit the +number of I/O logs. +The simplest way to limit the number of I/O is by setting the +\fImaxseq\fR +option to the maximum number of logs you wish to store. +Once the I/O log sequence number reaches +\fImaxseq\fR, +it will be reset to zero and +\fBsudoers\fR +will truncate and re-use any existing I/O logs. +.SH "FILES" +.TP 26n +\fI@sysconfdir@/sudo.conf\fR +Sudo front end configuration +.TP 26n +\fI@sysconfdir@/sudoers\fR +List of who can run what +.TP 26n +\fI/etc/group\fR +Local groups file +.TP 26n +\fI/etc/netgroup\fR +List of network groups +.TP 26n +\fI@iolog_dir@\fR +I/O log files +.TP 26n +\fI@rundir@/ts\fR +Directory containing time stamps for the +\fBsudoers\fR +security policy +.TP 26n +\fI@vardir@/lectured\fR +Directory containing lecture status files for the +\fBsudoers\fR +security policy +.TP 26n +\fI/etc/environment\fR +Initial environment for +\fB\-i\fR +mode on AIX and Linux systems +.SH "EXAMPLES" +Below are example +\fIsudoers\fR +file entries. +Admittedly, some of these are a bit contrived. +First, we allow a few environment variables to pass and then define our +\fIaliases\fR: +.nf +.sp +.RS 0n +# Run X applications through sudo; HOME is used to find the +# .Xauthority file. Note that other programs use HOME to find +# configuration files and this may lead to privilege escalation! +Defaults env_keep += "DISPLAY HOME" + +# User alias specification +User_Alias FULLTIMERS = millert, mikef, dowdy +User_Alias PARTTIMERS = bostley, jwfox, crawl +User_Alias WEBMASTERS = 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 = master, mail, www, ns +Host_Alias CDROM = orion, perseus, hercules + +# Cmnd alias specification +Cmnd_Alias DUMPS = /usr/bin/mt, /usr/sbin/dump, /usr/sbin/rdump,\e + /usr/sbin/restore, /usr/sbin/rrestore,\e + sha224:0GomF8mNN3wlDt1HD9XldjJ3SNgpFdbjO1+NsQ== \e + /home/operator/bin/start_backups +Cmnd_Alias KILL = /usr/bin/kill +Cmnd_Alias PRINTING = /usr/sbin/lpc, /usr/bin/lprm +Cmnd_Alias SHUTDOWN = /usr/sbin/shutdown +Cmnd_Alias HALT = /usr/sbin/halt +Cmnd_Alias REBOOT = /usr/sbin/reboot +Cmnd_Alias SHELLS = /usr/bin/sh, /usr/bin/csh, /usr/bin/ksh,\e + /usr/local/bin/tcsh, /usr/bin/rsh,\e + /usr/local/bin/zsh +Cmnd_Alias SU = /usr/bin/su +Cmnd_Alias PAGERS = /usr/bin/more, /usr/bin/pg, /usr/bin/less +.RE +.fi +.PP +Here we override some of the compiled in default values. +We want +\fBsudo\fR +to log via +syslog(3) +using the +\fIauth\fR +facility in all cases. +We don't want to subject the full time staff to the +\fBsudo\fR +lecture, user +\fBmillert\fR +need not give a password, and we don't want to reset the +\fRLOGNAME\fR +or +\fRUSER\fR +environment variables when running commands as root. +Additionally, on the machines in the +\fISERVERS\fR +\fRHost_Alias\fR, +we keep an additional local log file and make sure we log the year +in each log line since the log entries will be kept around for several years. +Lastly, we disable shell escapes for the commands in the PAGERS +\fRCmnd_Alias\fR +(\fI/usr/bin/more\fR, +\fI/usr/bin/pg\fR +and +\fI/usr/bin/less\fR) +\&. +Note that this will not effectively constrain users with +\fBsudo\fR +\fBALL\fR +privileges. +.nf +.sp +.RS 0n +# Override built-in defaults +Defaults syslog=auth +Defaults>root !set_logname +Defaults:FULLTIMERS !lecture +Defaults:millert !authenticate +Defaults@SERVERS log_year, logfile=/var/log/sudo.log +Defaults!PAGERS noexec +.RE +.fi +.PP +The +\fIUser specification\fR +is the part that actually determines who may run what. +.nf +.sp +.RS 0n +root ALL = (ALL) ALL +%wheel ALL = (ALL) ALL +.RE +.fi +.PP +We let +\fBroot\fR +and any user in group +\fBwheel\fR +run any command on any host as any user. +.nf +.sp +.RS 0n +FULLTIMERS ALL = NOPASSWD: ALL +.RE +.fi +.PP +Full time sysadmins +(\fBmillert\fR, +\fBmikef\fR, +and +\fBdowdy\fR) +may run any command on any host without authenticating themselves. +.nf +.sp +.RS 0n +PARTTIMERS ALL = ALL +.RE +.fi +.PP +Part time sysadmins +\fBbostley\fR, +\fBjwfox\fR, +and +\fBcrawl\fR) +may run any command on any host but they must authenticate themselves +first (since the entry lacks the +\fRNOPASSWD\fR +tag). +.nf +.sp +.RS 0n +jack CSNETS = ALL +.RE +.fi +.PP +The user +\fBjack\fR +may run any command on the machines in the +\fICSNETS\fR +alias (the networks +\fR128.138.243.0\fR, +\fR128.138.204.0\fR, +and +\fR128.138.242.0\fR). +Of those networks, only +\fR128.138.204.0\fR +has an explicit netmask (in CIDR notation) indicating it is a class C network. +For the other networks in +\fICSNETS\fR, +the local machine's netmask will be used during matching. +.nf +.sp +.RS 0n +lisa CUNETS = ALL +.RE +.fi +.PP +The user +\fBlisa\fR +may run any command on any host in the +\fICUNETS\fR +alias (the class B network +\fR128.138.0.0\fR). +.nf +.sp +.RS 0n +operator ALL = DUMPS, KILL, SHUTDOWN, HALT, REBOOT, PRINTING,\e + sudoedit /etc/printcap, /usr/oper/bin/ +.RE +.fi +.PP +The +\fBoperator\fR +user may run commands limited to simple maintenance. +Here, those are commands related to backups, killing processes, the +printing system, shutting down the system, and any commands in the +directory +\fI/usr/oper/bin/\fR. +Note that one command in the +\fRDUMPS\fR +Cmnd_Alias includes a sha224 digest, +\fI/home/operator/bin/start_backups\fR. +This is because the directory containing the script is writable by the +operator user. +If the script is modified (resulting in a digest mismatch) it will no longer +be possible to run it via +\fBsudo\fR. +.nf +.sp +.RS 0n +joe ALL = /usr/bin/su operator +.RE +.fi +.PP +The user +\fBjoe\fR +may only +su(1) +to operator. +.nf +.sp +.RS 0n +pete HPPA = /usr/bin/passwd [A-Za-z]*, !/usr/bin/passwd *root* + +%opers ALL = (: ADMINGRP) /usr/sbin/ +.RE +.fi +.PP +Users in the +\fBopers\fR +group may run commands in +\fI/usr/sbin/\fR +as themselves +with any group in the +\fIADMINGRP\fR +\fRRunas_Alias\fR +(the +\fBadm\fR +and +\fBoper\fR +groups). +.PP +The user +\fBpete\fR +is allowed to change anyone's password except for +root on the +\fIHPPA\fR +machines. +Because command line arguments are matched as a single, +concatenated string, the +\(oq*\(cq +wildcard will match +\fImultiple\fR +words. +This example assumes that +passwd(1) +does not take multiple user names on the command line. +Note that on GNU systems, options to +passwd(1) +may be specified after the user argument. +As a result, this rule will also allow: +.nf +.sp +.RS 4n +passwd username --expire +.RE +.fi +.PP +which may not be desirable. +.nf +.sp +.RS 0n +bob SPARC = (OP) ALL : SGI = (OP) ALL +.RE +.fi +.PP +The user +\fBbob\fR +may run anything on the +\fISPARC\fR +and +\fISGI\fR +machines as any user listed in the +\fIOP\fR +\fRRunas_Alias\fR +(\fBroot\fR +and +\fBoperator\fR.) +.nf +.sp +.RS 0n +jim +biglab = ALL +.RE +.fi +.PP +The user +\fBjim\fR +may run any command on machines in the +\fIbiglab\fR +netgroup. +\fBsudo\fR +knows that +\(lqbiglab\(rq +is a netgroup due to the +\(oq+\(cq +prefix. +.nf +.sp +.RS 0n ++secretaries ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser +.RE +.fi +.PP +Users in the +\fBsecretaries\fR +netgroup need to help manage the printers as well as add and remove users, +so they are allowed to run those commands on all machines. +.nf +.sp +.RS 0n +fred ALL = (DB) NOPASSWD: ALL +.RE +.fi +.PP +The user +\fBfred\fR +can run commands as any user in the +\fIDB\fR +\fRRunas_Alias\fR +(\fBoracle\fR +or +\fBsybase\fR) +without giving a password. +.nf +.sp +.RS 0n +john ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root* +.RE +.fi +.PP +On the +\fIALPHA\fR +machines, user +\fBjohn\fR +may su to anyone except root but he is not allowed to specify any options +to the +su(1) +command. +.nf +.sp +.RS 0n +jen ALL, !SERVERS = ALL +.RE +.fi +.PP +The user +\fBjen\fR +may run any command on any machine except for those in the +\fISERVERS\fR +\fRHost_Alias\fR +(master, mail, www and ns). +.nf +.sp +.RS 0n +jill SERVERS = /usr/bin/, !SU, !SHELLS +.RE +.fi +.PP +For any machine in the +\fISERVERS\fR +\fRHost_Alias\fR, +\fBjill\fR +may run +any commands in the directory +\fI/usr/bin/\fR +except for those commands +belonging to the +\fISU\fR +and +\fISHELLS\fR +\fRCmnd_Aliases\fR. +While not specifically mentioned in the rule, the commands in the +\fIPAGERS\fR +\fRCmnd_Alias\fR +all reside in +\fI/usr/bin\fR +and have the +\fInoexec\fR +option set. +.nf +.sp +.RS 0n +steve CSNETS = (operator) /usr/local/op_commands/ +.RE +.fi +.PP +The user +\fBsteve\fR +may run any command in the directory /usr/local/op_commands/ +but only as user operator. +.nf +.sp +.RS 0n +matt valkyrie = KILL +.RE +.fi +.PP +On his personal workstation, valkyrie, +\fBmatt\fR +needs to be able to kill hung processes. +.nf +.sp +.RS 0n +WEBMASTERS www = (www) ALL, (root) /usr/bin/su www +.RE +.fi +.PP +On the host www, any user in the +\fIWEBMASTERS\fR +\fRUser_Alias\fR +(will, wendy, and wim), may run any command as user www (which owns the +web pages) or simply +su(1) +to www. +.nf +.sp +.RS 0n +ALL CDROM = NOPASSWD: /sbin/umount /CDROM,\e + /sbin/mount -o nosuid\e,nodev /dev/cd0a /CDROM +.RE +.fi +.PP +Any user may mount or unmount a CD-ROM on the machines in the CDROM +\fRHost_Alias\fR +(orion, perseus, hercules) without entering a password. +This is a bit tedious for users to type, so it is a prime candidate +for encapsulating in a shell script. +.SH "SECURITY NOTES" +.SS "Limitations of the \(oq!\&\(cq operator" +It is generally not effective to +\(lqsubtract\(rq +commands from +\fBALL\fR +using the +\(oq!\&\(cq +operator. +A user can trivially circumvent this by copying the desired command +to a different name and then executing that. +For example: +.nf +.sp +.RS 0n +bill ALL = ALL, !SU, !SHELLS +.RE +.fi +.PP +Doesn't really prevent +\fBbill\fR +from running the commands listed in +\fISU\fR +or +\fISHELLS\fR +since he can simply copy those commands to a different name, or use +a shell escape from an editor or other program. +Therefore, these kind of restrictions should be considered +advisory at best (and reinforced by policy). +.PP +In general, if a user has sudo +\fBALL\fR +there is nothing to prevent them from creating their own program that gives +them a root shell (or making their own copy of a shell) regardless of any +\(oq!\&\(cq +elements in the user specification. +.SS "Security implications of \fIfast_glob\fR" +If the +\fIfast_glob\fR +option is in use, it is not possible to reliably negate commands where the +path name includes globbing (aka wildcard) characters. +This is because the C library's +fnmatch(3) +function cannot resolve relative paths. +While this is typically only an inconvenience for rules that grant privileges, +it can result in a security issue for rules that subtract or revoke privileges. +.PP +For example, given the following +\fIsudoers\fR +file entry: +.nf +.sp +.RS 0n +john ALL = /usr/bin/passwd [a-zA-Z0-9]*, /usr/bin/chsh [a-zA-Z0-9]*,\e + /usr/bin/chfn [a-zA-Z0-9]*, !/usr/bin/* root +.RE +.fi +.PP +User +\fBjohn\fR +can still run +\fR/usr/bin/passwd root\fR +if +\fIfast_glob\fR +is enabled by changing to +\fI/usr/bin\fR +and running +\fR./passwd root\fR +instead. +.SS "Preventing shell escapes" +Once +\fBsudo\fR +executes a program, that program is free to do whatever +it pleases, including run other programs. +This can be a security issue since it is not uncommon for a program to +allow shell escapes, which lets a user bypass +\fBsudo\fR's +access control and logging. +Common programs that permit shell escapes include shells (obviously), +editors, paginators, mail and terminal programs. +.PP +There are two basic approaches to this problem: +.TP 10n +restrict +Avoid giving users access to commands that allow the user to run +arbitrary commands. +Many editors have a restricted mode where shell +escapes are disabled, though +\fBsudoedit\fR +is a better solution to +running editors via +\fBsudo\fR. +Due to the large number of programs that +offer shell escapes, restricting users to the set of programs that +do not is often unworkable. +.TP 10n +noexec +Many systems that support shared libraries have the ability to +override default library functions by pointing an environment +variable (usually +\fRLD_PRELOAD\fR) +to an alternate shared library. +On such systems, +\fBsudo\fR's +\fInoexec\fR +functionality can be used to prevent a program run by +\fBsudo\fR +from executing any other programs. +Note, however, that this applies only to native dynamically-linked +executables. +Statically-linked executables and foreign executables +running under binary emulation are not affected. +.sp +The +\fInoexec\fR +feature is known to work on SunOS, Solaris, *BSD, +Linux, IRIX, Tru64 UNIX, macOS, HP-UX 11.x and AIX 5.3 and above. +It should be supported on most operating systems that support the +\fRLD_PRELOAD\fR +environment variable. +Check your operating system's manual pages for the dynamic linker +(usually ld.so, ld.so.1, dyld, dld.sl, rld, or loader) to see if +\fRLD_PRELOAD\fR +is supported. +.sp +On Solaris 10 and higher, +\fInoexec\fR +uses Solaris privileges instead of the +\fRLD_PRELOAD\fR +environment variable. +.sp +To enable +\fInoexec\fR +for a command, use the +\fRNOEXEC\fR +tag as documented +in the User Specification section above. +Here is that example again: +.nf +.sp +.RS 10n +aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi +.RE +.fi +.RS 10n +.sp +This allows user +\fBaaron\fR +to run +\fI/usr/bin/more\fR +and +\fI/usr/bin/vi\fR +with +\fInoexec\fR +enabled. +This will prevent those two commands from +executing other commands (such as a shell). +If you are unsure whether or not your system is capable of supporting +\fInoexec\fR +you can always just try it out and check whether shell escapes work when +\fInoexec\fR +is enabled. +.RE +.PP +Note that restricting shell escapes is not a panacea. +Programs running as 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 +\fBsudoedit\fR +(see below). +.SS "Secure editing" +The +\fBsudoers\fR +plugin includes +\fBsudoedit\fR +support which allows users to securely edit files with the editor +of their choice. +As +\fBsudoedit\fR +is a built-in command, it must be specified in the +\fIsudoers\fR +file without a leading path. +However, it may take command line arguments just as a normal command does. +Wildcards used in +\fIsudoedit\fR +command line arguments are expected to be path names, so a forward slash +(\(oq/\(cq) +will not be matched by a wildcard. +.PP +Unlike other +\fBsudo\fR +commands, the editor is run with the permissions of the invoking +user and with the environment unmodified. +More information may be found in the description of the +\fB\-e\fR +option in +sudo(@mansectsu@). +.PP +For example, to allow user operator to edit the +\(lqmessage of the day\(rq +file: +.nf +.sp +.RS 6n +operator sudoedit /etc/motd +.RE +.fi +.PP +The operator user then runs +\fBsudoedit\fR +as follows: +.nf +.sp +.RS 6n +$ sudoedit /etc/motd +.RE +.fi +.PP +The editor will run as the operator user, not root, on a temporary copy of +\fI/etc/motd\fR. +After the file has been edited, +\fI/etc/motd\fR +will be updated with the contents of the temporary copy. +.PP +Users should +\fInever\fR +be granted +\fBsudoedit\fR +permission to edit a file that resides in a directory the user +has write access to, either directly or via a wildcard. +If the user has write access to the directory it is possible to +replace the legitimate file with a link to another file, +allowing the editing of arbitrary files. +To prevent this, starting with version 1.8.16, symbolic links will +not be followed in writable directories and +\fBsudoedit\fR +will refuse to edit a file located in a writable directory +unless the +\fIsudoedit_checkdir\fR +option has been disabled or the invoking user is root. +Additionally, in version 1.8.15 and higher, +\fBsudoedit\fR +will refuse to open a symbolic link unless either the +\fIsudoedit_follow\fR +option is enabled or the +\fIsudoedit\fR +command is prefixed with the +\fRFOLLOW\fR +tag in the +\fIsudoers\fR +file. +.SS "Time stamp file checks" +\fBsudoers\fR +will check the ownership of its time stamp directory +(\fI@rundir@/ts\fR +by default) +and ignore the directory's contents if it is not owned by root or +if it is writable by a user other than root. +Older versions of +\fBsudo\fR +stored time stamp files in +\fI/tmp\fR; +this is no longer recommended as it may be possible for a user +to create the time stamp themselves on systems that allow +unprivileged users to change the ownership of files they create. +.PP +While the time stamp directory +\fIshould\fR +be cleared at reboot time, not all systems contain a +\fI/run\fR +or +\fI/var/run\fR +directory. +To avoid potential problems, +\fBsudoers\fR +will ignore time stamp files that date from before the machine booted +on systems where the boot time is available. +.PP +Some systems with graphical desktop environments allow unprivileged +users to change the system clock. +Since +\fBsudoers\fR +relies on the system clock for time stamp validation, it may be +possible on such systems for a user to run +\fBsudo\fR +for longer than +\fItimestamp_timeout\fR +by setting the clock back. +To combat this, +\fBsudoers\fR +uses a monotonic clock (which never moves backwards) for its time stamps +if the system supports it. +.PP +\fBsudoers\fR +will not honor time stamps set far in the future. +Time stamps with a date greater than current_time + 2 * +\fRTIMEOUT\fR +will be ignored and +\fBsudoers\fR +will log and complain. +.PP +If the +\fItimestamp_type\fR +option is set to +\(lqtty\(rq, +the time stamp record includes the device number of the terminal +the user authenticated with. +This provides per-terminal granularity but time stamp records may still +outlive the user's session. +.PP +Unless the +\fItimestamp_type\fR +option is set to +\(lqglobal\(rq, +the time stamp record also includes the session ID of the process +that last authenticated. +This prevents processes in different terminal sessions from using +the same time stamp record. +On systems where a process's start time can be queried, +the start time of the session leader +is recorded in the time stamp record. +If no terminal is present or the +\fItimestamp_type\fR +option is set to +\(lqppid\(rq, +the start time of the parent process is used instead. +In most cases this will prevent a time stamp record from being re-used +without the user entering a password when logging out and back in again. +.SH "DEBUGGING" +Versions 1.8.4 and higher of the +\fBsudoers\fR +plugin support a flexible debugging framework that can help track +down what the plugin is doing internally if there is a problem. +This can be configured in the +sudo.conf(@mansectform@) +file. +.PP +The +\fBsudoers\fR +plugin uses the same debug flag format as the +\fBsudo\fR +front-end: +\fIsubsystem\fR@\fIpriority\fR. +.PP +The priorities used by +\fBsudoers\fR, +in order of decreasing severity, +are: +\fIcrit\fR, \fIerr\fR, \fIwarn\fR, \fInotice\fR, \fIdiag\fR, \fIinfo\fR, \fItrace\fR +and +\fIdebug\fR. +Each priority, when specified, also includes all priorities higher +than it. +For example, a priority of +\fInotice\fR +would include debug messages logged at +\fInotice\fR +and higher. +.PP +The following subsystems are used by the +\fBsudoers\fR +plugin: +.TP 10n +\fIalias\fR +\fRUser_Alias\fR, +\fRRunas_Alias\fR, +\fRHost_Alias\fR +and +\fRCmnd_Alias\fR +processing +.TP 10n +\fIall\fR +matches every subsystem +.TP 10n +\fIaudit\fR +BSM and Linux audit code +.TP 10n +\fIauth\fR +user authentication +.TP 10n +\fIdefaults\fR +\fIsudoers\fR +file +\fIDefaults\fR +settings +.TP 10n +\fIenv\fR +environment handling +.TP 10n +\fIldap\fR +LDAP-based sudoers +.TP 10n +\fIlogging\fR +logging support +.TP 10n +\fImatch\fR +matching of users, groups, hosts and netgroups in the +\fIsudoers\fR +file +.TP 10n +\fInetif\fR +network interface handling +.TP 10n +\fInss\fR +network service switch handling in +\fBsudoers\fR +.TP 10n +\fIparser\fR +\fIsudoers\fR +file parsing +.TP 10n +\fIperms\fR +permission setting +.TP 10n +\fIplugin\fR +The equivalent of +\fImain\fR +for the plugin. +.TP 10n +\fIpty\fR +pseudo-tty related code +.TP 10n +\fIrbtree\fR +redblack tree internals +.TP 10n +\fIsssd\fR +SSSD-based sudoers +.TP 10n +\fIutil\fR +utility functions +.PD 0 +.PP +For example: +.nf +.sp +.RS 0n +Debug sudo /var/log/sudo_debug match@info,nss@info +.RE +.fi +.PD +.PP +For more information, see the +sudo.conf(@mansectform@) +manual. +.SH "SEE ALSO" +ssh(1), +su(1), +fnmatch(3), +glob(3), +mktemp(3), +strftime(3), +sudo.conf(@mansectform@), +sudo_plugin(@mansectform@), +sudoers.ldap(@mansectform@), +sudoers_timestamp(@mansectform@), +sudo(@mansectsu@), +visudo(@mansectsu@) +.SH "AUTHORS" +Many people have worked on +\fBsudo\fR +over the years; this version consists of code written primarily by: +.sp +.RS 6n +Todd C. Miller +.RE +.PP +See the CONTRIBUTORS file in the +\fBsudo\fR +distribution (https://www.sudo.ws/contributors.html) for an +exhaustive list of people who have contributed to +\fBsudo\fR. +.SH "CAVEATS" +The +\fIsudoers\fR +file should +\fBalways\fR +be edited by the +\fBvisudo\fR +command which locks the file and does grammatical checking. +It is +imperative that the +\fIsudoers\fR +file be free of syntax errors since +\fBsudo\fR +will not run with a syntactically incorrect +\fIsudoers\fR +file. +.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 +\fRhostname\fR +command or use the +\fIfqdn\fR +option in +\fIsudoers\fR. +.SH "BUGS" +If you feel you have found a bug in +\fBsudo\fR, +please submit a bug report at https://bugzilla.sudo.ws/ +.SH "SUPPORT" +Limited free support is available via the sudo-users mailing list, +see https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or +search the archives. +.SH "DISCLAIMER" +\fBsudo\fR +is provided +\(lqAS IS\(rq +and any express or implied warranties, including, but not limited +to, the implied warranties of merchantability and fitness for a +particular purpose are disclaimed. +See the LICENSE file distributed with +\fBsudo\fR +or https://www.sudo.ws/license.html for complete details. |