embedaddon/sudo/doc/sudoers.cat - view

File: [ELWIX - Embedded LightWeight unIX -] / embedaddon / sudo / doc / sudoers.cat
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Tue Feb 21 16:23:02 2012 UTC (12 years, 4 months ago) by misho
Branches: sudo, MAIN
CVS tags: v1_8_3p2, HEAD

sudo

SUDOERS(4) MAINTENANCE COMMANDS SUDOERS(4) NNAAMMEE sudoers - default sudo security policy module DDEESSCCRRIIPPTTIIOONN The _s_u_d_o_e_r_s policy module determines a user's ssuuddoo privileges. It is the default ssuuddoo policy plugin. The policy is driven by the _/_e_t_c_/_s_u_d_o_e_r_s file or, optionally in LDAP. The policy format is described in detail in the "SUDOERS FILE FORMAT" section. For information on storing _s_u_d_o_e_r_s policy information in LDAP, please see _s_u_d_o_e_r_s_._l_d_a_p(4). AAuutthheennttiiccaattiioonn aanndd LLooggggiinngg The _s_u_d_o_e_r_s security policy requires that most users authenticate themselves before they can use ssuuddoo. 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 _s_u(1), when _s_u_d_o_e_r_s requires authentication, it validates the invoking user's credentials, not the target user's (or root's) credentials. This can be changed via the _r_o_o_t_p_w, _t_a_r_g_e_t_p_w and _r_u_n_a_s_p_w flags, described later. If a user who is not listed in the policy tries to run a command via ssuuddoo, mail is sent to the proper authorities. The address used for such mail is configurable via the _m_a_i_l_t_o Defaults entry (described later) and defaults to root. Note that mail will not be sent if an unauthorized user tries to run ssuuddoo with the --ll or --vv option. This allows users to determine for themselves whether or not they are allowed to use ssuuddoo. If ssuuddoo is run by root and the SUDO_USER environment variable is set, the _s_u_d_o_e_r_s 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 --ee option to remain useful even when invoked via a sudo-run script or program. Note, however, that the _s_u_d_o_e_r_s lookup is still done for root, not the user specified by SUDO_USER. _s_u_d_o_e_r_s uses time stamp files for credential caching. Once a user has been authenticated, a time stamp is updated and the user may then use sudo without a password for a short period of time (5 minutes unless overridden by the _t_i_m_e_o_u_t option. By default, _s_u_d_o_e_r_s uses a tty-based time stamp which means that there is a separate time stamp for each of a user's login sessions. The _t_t_y___t_i_c_k_e_t_s option can be disabled to force the use of a single time stamp for all of a user's sessions. _s_u_d_o_e_r_s can log both successful and unsuccessful attempts (as well as errors) to _s_y_s_l_o_g(3), a log file, or both. By default, _s_u_d_o_e_r_s will log via _s_y_s_l_o_g(3) but this is changeable via the _s_y_s_l_o_g and _l_o_g_f_i_l_e Defaults settings. _s_u_d_o_e_r_s also supports logging a command's input and output streams. I/O logging is not on by default but can be enabled using the _l_o_g___i_n_p_u_t and _l_o_g___o_u_t_p_u_t Defaults flags as well as the LOG_INPUT and LOG_OUTPUT command tags. CCoommmmaanndd EEnnvviirroonnmmeenntt Since environment variables can influence program behavior, _s_u_d_o_e_r_s 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 _s_u_d_o_e_r_s can deal with environment variables. By default, the _e_n_v___r_e_s_e_t option is enabled. This causes commands to be executed with a minimal environment containing TERM, PATH, HOME, MAIL, SHELL, LOGNAME, USER and USERNAME in addition to variables from the invoking process permitted by the _e_n_v___c_h_e_c_k and _e_n_v___k_e_e_p options. This is effectively a whitelist for environment variables. If, however, the _e_n_v___r_e_s_e_t option is disabled, any variables not explicitly denied by the _e_n_v___c_h_e_c_k and _e_n_v___d_e_l_e_t_e options are inherited from the invoking process. In this case, _e_n_v___c_h_e_c_k and _e_n_v___d_e_l_e_t_e behave like a blacklist. Since it is not possible to blacklist all potentially dangerous environment variables, use of the default _e_n_v___r_e_s_e_t behavior is encouraged. In all cases, environment variables with a value beginning with () are removed as they could be interpreted as bbaasshh functions. The list of environment variables that ssuuddoo allows or denies is contained in the output of sudo -V when run as root. Note that the dynamic linker on most operating systems will remove variables that can control dynamic linking from the environment of setuid executables, including ssuuddoo. Depending on the operating system this may include _RLD*, DYLD_*, LD_*, LDR_*, LIBPATH, SHLIB_PATH, and others. These type of variables are removed from the environment before ssuuddoo even begins execution and, as such, it is not possible for ssuuddoo to preserve them. As a special case, if ssuuddoo's --ii option (initial login) is specified, _s_u_d_o_e_r_s will initialize the environment regardless of the value of _e_n_v___r_e_s_e_t. The _D_I_S_P_L_A_Y, _P_A_T_H and _T_E_R_M variables remain unchanged; _H_O_M_E, _M_A_I_L, _S_H_E_L_L, _U_S_E_R, and _L_O_G_N_A_M_E are set based on the target user. On Linux and AIX systems the contents of _/_e_t_c_/_e_n_v_i_r_o_n_m_e_n_t are also included. All other environment variables are removed. SSUUDDOOEERRSS FFIILLEE FFOORRMMAATT The _s_u_d_o_e_r_s file is composed of two types of entries: aliases (basically variables) and user specifications (which specify who may run what). 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). The _s_u_d_o_e_r_s grammar will be described below in Extended Backus-Naur Form (EBNF). Don't despair if you don't know what EBNF is; it is fairly simple, and the definitions below are annotated. QQuuiicckk gguuiiddee ttoo EEBBNNFF EBNF is a concise and exact way of describing the grammar of a language. Each EBNF definition is made up of _p_r_o_d_u_c_t_i_o_n _r_u_l_e_s. E.g., symbol ::= definition | alternate1 | alternate2 ... Each _p_r_o_d_u_c_t_i_o_n _r_u_l_e 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 "wildcard" characters, which have different meanings. ? Means that the preceding symbol (or group of symbols) is optional. That is, it may appear once or not at all. * Means that the preceding symbol (or group of symbols) may appear zero or more times. + Means that the preceding symbol (or group of symbols) may appear one or more times. 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). AAlliiaasseess There are four kinds of aliases: User_Alias, Runas_Alias, Host_Alias and Cmnd_Alias. Alias ::= 'User_Alias' User_Alias (':' User_Alias)* | 'Runas_Alias' Runas_Alias (':' Runas_Alias)* | 'Host_Alias' Host_Alias (':' Host_Alias)* | 'Cmnd_Alias' Cmnd_Alias (':' Cmnd_Alias)* User_Alias ::= NAME '=' User_List Runas_Alias ::= NAME '=' Runas_List Host_Alias ::= NAME '=' Host_List Cmnd_Alias ::= NAME '=' Cmnd_List NAME ::= [A-Z]([A-Z][0-9]_)* Each _a_l_i_a_s definition is of the form Alias_Type NAME = item1, item2, ... where _A_l_i_a_s___T_y_p_e is one of User_Alias, Runas_Alias, Host_Alias, or Cmnd_Alias. A NAME is a string of uppercase letters, numbers, and underscore characters ('_'). A NAME mmuusstt 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 (':'). E.g., Alias_Type NAME = item1, item2, item3 : NAME = item4, item5 The definitions of what constitutes a valid _a_l_i_a_s member follow. User_List ::= User | User ',' User_List User ::= '!'* user name | '!'* #uid | '!'* %group | '!'* %#gid | '!'* +netgroup | '!'* %:nonunix_group | '!'* %:#nonunix_gid | '!'* User_Alias A User_List is made up of one or more user names, user ids (prefixed with '#'), system group names and ids (prefixed with '%' and '%#' respectively), netgroups (prefixed with '+'), non-Unix group names and IDs (prefixed with '%:' and '%:#' respectively) and User_Aliases. Each list item may be prefixed with zero or more '!' operators. An odd number of '!' operators negate the value of the item; an even number just cancel each other out. A user name, uid, group, gid, netgroup, nonunix_group or nonunix_gid may be enclosed in double quotes to avoid the need for escaping special characters. Alternately, special characters may be specified in escaped hex mode, e.g. \x20 for space. When using double quotes, any prefix characters must be included inside the quotes. The actual nonunix_group and nonunix_gid syntax depends on the underlying group provider plugin (see the _g_r_o_u_p___p_l_u_g_i_n description below). For instance, the QAS AD plugin supports the following formats: +o Group in the same domain: "Group Name" +o Group in any domain: "Group Name@FULLY.QUALIFIED.DOMAIN" +o Group SID: "S-1-2-34-5678901234-5678901234-5678901234-567" Note that quotes around group names are optional. Unquoted strings must use a backslash (\) to escape spaces and special characters. See "Other special characters and reserved words" for a list of characters that need to be escaped. Runas_List ::= Runas_Member | Runas_Member ',' Runas_List Runas_Member ::= '!'* user name | '!'* #uid | '!'* %group | '!'* %#gid | '!'* %:nonunix_group | '!'* %:#nonunix_gid | '!'* +netgroup | '!'* Runas_Alias A Runas_List is similar to a User_List except that instead of User_Aliases it can contain Runas_Aliases. 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). Host_List ::= Host | Host ',' Host_List Host ::= '!'* host name | '!'* ip_addr | '!'* network(/netmask)? | '!'* +netgroup | '!'* Host_Alias A Host_List is made up of one or more host names, IP addresses, network numbers, netgroups (prefixed with '+') and other aliases. Again, the value of an item may be negated with the '!' operator. If you do not specify a netmask along with the network number, ssuuddoo will query each of the local host's network interfaces and, if the network number corresponds to one of the hosts's network interfaces, the corresponding netmask will be used. 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 Wildcards section below), but unless the host name command on your machine returns the fully qualified host name, you'll need to use the _f_q_d_n option for wildcards to be useful. Note ssuuddoo only inspects actual network interfaces; this means that IP address 127.0.0.1 (localhost) will never match. Also, the host name "localhost" will only match if that is the actual host name, which is usually only the case for non-networked systems. Cmnd_List ::= Cmnd | Cmnd ',' Cmnd_List commandname ::= file name | file name args | file name '""' Cmnd ::= '!'* commandname | '!'* directory | '!'* "sudoedit" | '!'* Cmnd_Alias A Cmnd_List is a list of one or more commandnames, directories, and other aliases. A commandname is a fully qualified file name which may include shell-style wildcards (see the Wildcards 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 "" to indicate that the command may only be run wwiitthhoouutt command line arguments. A directory is a fully qualified path name ending in a '/'. When you specify a directory in a Cmnd_List, the user will be able to run any file within that directory (but not in any subdirectories therein). If a Cmnd has associated command line arguments, then the arguments in the Cmnd 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 '\' if they are used in command arguments: ',', ':', '=', '\'. The special command "sudoedit" is used to permit a user to run ssuuddoo with the --ee option (or as ssuuddooeeddiitt). It may take command line arguments just as a normal command does. DDeeffaauullttss Certain configuration options may be changed from their default values at runtime via one or more Default_Entry 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 Cmnd_Alias and reference that instead. 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 Parameters may be ffllaaggss, iinntteeggeerr values, ssttrriinnggss, or lliissttss. Flags are implicitly boolean and can be turned off via the '!' 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 (\). Lists have two additional assignment operators, += and -=. These operators are used to add to and delete from a list respectively. It is not an error to use the -= operator to remove an element that does not exist in a list. Defaults entries are parsed in the following order: generic, host and user Defaults first, then runas Defaults and finally command defaults. See "SUDOERS OPTIONS" for a list of supported Defaults parameters. UUsseerr SSppeecciiffiiccaattiioonn User_Spec ::= User_List Host_List '=' Cmnd_Spec_List \ (':' Host_List '=' Cmnd_Spec_List)* Cmnd_Spec_List ::= Cmnd_Spec | Cmnd_Spec ',' Cmnd_Spec_List Cmnd_Spec ::= Runas_Spec? SELinux_Spec? Tag_Spec* Cmnd Runas_Spec ::= '(' Runas_List? (':' Runas_List)? ')' SELinux_Spec ::= ('ROLE=role' | 'TYPE=type') Tag_Spec ::= ('NOPASSWD:' | 'PASSWD:' | 'NOEXEC:' | 'EXEC:' | 'SETENV:' | 'NOSETENV:' | 'LOG_INPUT:' | 'NOLOG_INPUT:' | 'LOG_OUTPUT:' | 'NOLOG_OUTPUT:') A uusseerr ssppeecciiffiiccaattiioonn determines which commands a user may run (and as what user) on specified hosts. By default, commands are run as rroooott, but this can be changed on a per-command basis. The basic structure of a user specification is `who where = (as_whom) what'. Let's break that down into its constituent parts: RRuunnaass__SSppeecc A Runas_Spec determines the user and/or the group that a command may be run as. A fully-specified Runas_Spec consists of two Runas_Lists (as defined above) separated by a colon (':') and enclosed in a set of parentheses. The first Runas_List indicates which users the command may be run as via ssuuddoo's --uu option. The second defines a list of groups that can be specified via ssuuddoo's --gg option. If both Runas_Lists are specified, the command may be run with any combination of users and groups listed in their respective Runas_Lists. If only the first is specified, the command may be run as any user in the list but no --gg option may be specified. If the first Runas_List is empty but the second is specified, the command may be run as the invoking user with the group set to any listed in the Runas_List. If no Runas_Spec is specified the command may be run as rroooott and no group may be specified. A Runas_Spec sets the default for the commands that follow it. What this means is that for the entry: dgb boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm The user ddggbb may run _/_b_i_n_/_l_s, _/_b_i_n_/_k_i_l_l, and _/_u_s_r_/_b_i_n_/_l_p_r_m -- but only as ooppeerraattoorr. E.g., $ sudo -u operator /bin/ls It is also possible to override a Runas_Spec later on in an entry. If we modify the entry like so: dgb boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm Then user ddggbb is now allowed to run _/_b_i_n_/_l_s as ooppeerraattoorr, but _/_b_i_n_/_k_i_l_l and _/_u_s_r_/_b_i_n_/_l_p_r_m as rroooott. We can extend this to allow ddggbb to run /bin/ls with either the user or group set to ooppeerraattoorr: dgb boulder = (operator : operator) /bin/ls, (root) /bin/kill, \ /usr/bin/lprm Note that while the group portion of the Runas_Spec permits the user to run as command with that group, it does not force the user to do so. If no group is specified on the command line, the command will run with the group listed in the target user's password database entry. The following would all be permitted by the sudoers entry above: $ sudo -u operator /bin/ls $ sudo -u operator -g operator /bin/ls $ sudo -g operator /bin/ls In the following example, user ttccmm may run commands that access a modem device file with the dialer group. tcm boulder = (:dialer) /usr/bin/tip, /usr/bin/cu, \ /usr/local/bin/minicom Note that in this example only the group will be set, the command still runs as user ttccmm. E.g. $ sudo -g dialer /usr/bin/cu Multiple users and groups may be present in a Runas_Spec, in which case the user may select any combination of users and groups via the --uu and --gg options. In this example: alan ALL = (root, bin : operator, system) ALL user aallaann may run any command as either user root or bin, optionally setting the group to operator or system. SSEELLiinnuuxx__SSppeecc On systems with SELinux support, _s_u_d_o_e_r_s 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 _s_u_d_o_e_r_s. A role or type specified on the command line, however, will supercede the values in _s_u_d_o_e_r_s. TTaagg__SSppeecc A command may have zero or more tags associated with it. There are eight possible tag values, NOPASSWD, PASSWD, NOEXEC, EXEC, SETENV, NOSETENV, LOG_INPUT, NOLOG_INPUT, LOG_OUTPUT and NOLOG_OUTPUT. Once a tag is set on a Cmnd, subsequent Cmnds in the Cmnd_Spec_List, inherit the tag unless it is overridden by the opposite tag (i.e.: PASSWD overrides NOPASSWD and NOEXEC overrides EXEC). _N_O_P_A_S_S_W_D _a_n_d _P_A_S_S_W_D By default, ssuuddoo requires that a user authenticate him or herself before running a command. This behavior can be modified via the NOPASSWD tag. Like a Runas_Spec, the NOPASSWD tag sets a default for the commands that follow it in the Cmnd_Spec_List. Conversely, the PASSWD tag can be used to reverse things. For example: ray rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm would allow the user rraayy to run _/_b_i_n_/_k_i_l_l, _/_b_i_n_/_l_s, and _/_u_s_r_/_b_i_n_/_l_p_r_m as rroooott on the machine rushmore without authenticating himself. If we only want rraayy to be able to run _/_b_i_n_/_k_i_l_l without a password the entry would be: ray rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm Note, however, that the PASSWD tag has no effect on users who are in the group specified by the _e_x_e_m_p_t___g_r_o_u_p option. By default, if the NOPASSWD tag is applied to any of the entries for a user on the current host, he or she will be able to run sudo -l without a password. Additionally, a user may only run sudo -v without a password if the NOPASSWD tag is present for all a user's entries that pertain to the current host. This behavior may be overridden via the verifypw and listpw options. _N_O_E_X_E_C _a_n_d _E_X_E_C If ssuuddoo has been compiled with _n_o_e_x_e_c support and the underlying operating system supports it, the NOEXEC tag can be used to prevent a dynamically-linked executable from running further commands itself. In the following example, user aaaarroonn may run _/_u_s_r_/_b_i_n_/_m_o_r_e and _/_u_s_r_/_b_i_n_/_v_i but shell escapes will be disabled. aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi See the "PREVENTING SHELL ESCAPES" section below for more details on how NOEXEC works and whether or not it will work on your system. _S_E_T_E_N_V _a_n_d _N_O_S_E_T_E_N_V These tags override the value of the _s_e_t_e_n_v option on a per-command basis. Note that if SETENV has been set for a command, the user may disable the _e_n_v___r_e_s_e_t option from the command line via the --EE option. Additionally, environment variables set on the command line are not subject to the restrictions imposed by _e_n_v___c_h_e_c_k, _e_n_v___d_e_l_e_t_e, or _e_n_v___k_e_e_p. As such, only trusted users should be allowed to set variables in this manner. If the command matched is AALLLL, the SETENV tag is implied for that command; this default may be overridden by use of the NOSETENV tag. _L_O_G___I_N_P_U_T _a_n_d _N_O_L_O_G___I_N_P_U_T These tags override the value of the _l_o_g___i_n_p_u_t option on a per-command basis. For more information, see the description of _l_o_g___i_n_p_u_t in the "SUDOERS OPTIONS" section below. _L_O_G___O_U_T_P_U_T _a_n_d _N_O_L_O_G___O_U_T_P_U_T These tags override the value of the _l_o_g___o_u_t_p_u_t option on a per-command basis. For more information, see the description of _l_o_g___o_u_t_p_u_t in the "SUDOERS OPTIONS" section below. WWiillddccaarrddss ssuuddoo allows shell-style _w_i_l_d_c_a_r_d_s (aka meta or glob characters) to be used in host names, path names and command line arguments in the _s_u_d_o_e_r_s file. Wildcard matching is done via the PPOOSSIIXX _g_l_o_b(3) and _f_n_m_a_t_c_h(3) routines. Note that these are _n_o_t regular expressions. * Matches any set of zero or more characters. ? Matches any single character. [...] Matches any character in the specified range. [!...] Matches any character nnoott in the specified range. \x For any character "x", evaluates to "x". This is used to escape special characters such as: "*", "?", "[", and "}". POSIX character classes may also be used if your system's _g_l_o_b(3) and _f_n_m_a_t_c_h(3) functions support them. However, because the ':' character has special meaning in _s_u_d_o_e_r_s, it must be escaped. For example: /bin/ls [[\:alpha\:]]* Would match any file name beginning with a letter. Note that a forward slash ('/') will nnoott be matched by wildcards used in the path name. When matching the command line arguments, however, a slash ddooeess get matched by wildcards. This is to make a path like: /usr/bin/* match _/_u_s_r_/_b_i_n_/_w_h_o but not _/_u_s_r_/_b_i_n_/_X_1_1_/_x_t_e_r_m. EExxcceeppttiioonnss ttoo wwiillddccaarrdd rruulleess The following exceptions apply to the above rules: "" If the empty string "" is the only command line argument in the _s_u_d_o_e_r_s entry it means that command is not allowed to be run with aannyy arguments. IInncclluuddiinngg ootthheerr ffiilleess ffrroomm wwiitthhiinn ssuuddooeerrss It is possible to include other _s_u_d_o_e_r_s files from within the _s_u_d_o_e_r_s file currently being parsed using the #include and #includedir directives. This can be used, for example, to keep a site-wide _s_u_d_o_e_r_s file in addition to a local, per-machine file. For the sake of this example the site-wide _s_u_d_o_e_r_s will be _/_e_t_c_/_s_u_d_o_e_r_s and the per-machine one will be _/_e_t_c_/_s_u_d_o_e_r_s_._l_o_c_a_l. To include _/_e_t_c_/_s_u_d_o_e_r_s_._l_o_c_a_l from within _/_e_t_c_/_s_u_d_o_e_r_s we would use the following line in _/_e_t_c_/_s_u_d_o_e_r_s: #include /etc/sudoers.local When ssuuddoo reaches this line it will suspend processing of the current file (_/_e_t_c_/_s_u_d_o_e_r_s) and switch to _/_e_t_c_/_s_u_d_o_e_r_s_._l_o_c_a_l. Upon reaching the end of _/_e_t_c_/_s_u_d_o_e_r_s_._l_o_c_a_l, the rest of _/_e_t_c_/_s_u_d_o_e_r_s 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. The file name may include the %h escape, signifying the short form of the host name. I.e., if the machine's host name is "xerxes", then #include /etc/sudoers.%h will cause ssuuddoo to include the file _/_e_t_c_/_s_u_d_o_e_r_s_._x_e_r_x_e_s. The #includedir directive can be used to create a _s_u_d_o_._d directory that the system package manager can drop _s_u_d_o_e_r_s rules into as part of package installation. For example, given: #includedir /etc/sudoers.d ssuuddoo will read each file in _/_e_t_c_/_s_u_d_o_e_r_s_._d, skipping file names that end in ~ or contain a . character to avoid causing problems with package manager or editor temporary/backup files. Files are parsed in sorted lexical order. That is, _/_e_t_c_/_s_u_d_o_e_r_s_._d_/_0_1___f_i_r_s_t will be parsed before _/_e_t_c_/_s_u_d_o_e_r_s_._d_/_1_0___s_e_c_o_n_d. Be aware that because the sorting is lexical, not numeric, _/_e_t_c_/_s_u_d_o_e_r_s_._d_/_1___w_h_o_o_p_s would be loaded aafftteerr _/_e_t_c_/_s_u_d_o_e_r_s_._d_/_1_0___s_e_c_o_n_d. Using a consistent number of leading zeroes in the file names can be used to avoid such problems. Note that unlike files included via #include, vviissuuddoo will not edit the files in a #includedir directory unless one of them contains a syntax error. It is still possible to run vviissuuddoo with the -f flag to edit the files directly. OOtthheerr ssppeecciiaall cchhaarraacctteerrss aanndd rreesseerrvveedd wwoorrddss The pound sign ('#') 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. The reserved word AALLLL is a built-in _a_l_i_a_s that always causes a match to succeed. It can be used wherever one might otherwise use a Cmnd_Alias, User_Alias, Runas_Alias, or Host_Alias. You should not try to define your own _a_l_i_a_s called AALLLL as the built-in alias will be used in preference to your own. Please note that using AALLLL can be dangerous since in a command context, it allows the user to run aannyy command on the system. An exclamation point ('!') can be used as a logical _n_o_t operator both in an _a_l_i_a_s and in front of a Cmnd. This allows one to exclude certain values. Note, however, that using a ! in conjunction with the built-in ALL alias to allow a user to run "all but a few" commands rarely works as intended (see SECURITY NOTES below). Long lines can be continued with a backslash ('\') as the last character on the line. Whitespace between elements in a list as well as special syntactic characters in a _U_s_e_r _S_p_e_c_i_f_i_c_a_t_i_o_n ('=', ':', '(', ')') is optional. The following characters must be escaped with a backslash ('\') when used as part of a word (e.g. a user name or host name): '!', '=', ':', ',', '(', ')', '\'. SSUUDDOOEERRSS OOPPTTIIOONNSS ssuuddoo's behavior can be modified by Default_Entry lines, as explained earlier. A list of all supported Defaults parameters, grouped by type, are listed below. BBoooolleeaann FFllaaggss: always_set_home If enabled, ssuuddoo will set the HOME environment variable to the home directory of the target user (which is root unless the --uu option is used). This effectively means that the --HH option is always implied. Note that HOME is already set when the the _e_n_v___r_e_s_e_t option is enabled, so _a_l_w_a_y_s___s_e_t___h_o_m_e is only effective for configurations where either _e_n_v___r_e_s_e_t is disabled or HOME is present in the _e_n_v___k_e_e_p list. This flag is _o_f_f by default. 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 PASSWD and NOPASSWD tags. This flag is _o_n by default. closefrom_override If set, the user may use ssuuddoo's --CC option which overrides the default starting point at which ssuuddoo begins closing open file descriptors. This flag is _o_f_f by default. compress_io If set, and ssuuddoo is configured to log a command's input or output, the I/O logs will be compressed using zzlliibb. This flag is _o_n by default when ssuuddoo is compiled with zzlliibb support. env_editor If set, vviissuuddoo will use the value of the EDITOR or VISUAL 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 editor variable. vviissuuddoo will then only use the EDITOR or VISUAL if they match a value specified in editor. This flag is _o_f_f by default. env_reset If set, ssuuddoo will reset the environment to only contain the LOGNAME, MAIL, SHELL, USER, USERNAME and the SUDO_* variables. Any variables in the caller's environment that match the env_keep and env_check lists are then added. The default contents of the env_keep and env_check lists are displayed when ssuuddoo is run by root with the _-_V option. If the _s_e_c_u_r_e___p_a_t_h option is set, its value will be used for the PATH environment variable. This flag is _o_n by default. fast_glob Normally, ssuuddoo uses the _g_l_o_b(3) function to do shell- style globbing when matching path names. However, since it accesses the file system, _g_l_o_b(3) can take a long time to complete for some patterns, especially when the pattern references a network file system that is mounted on demand (automounted). The _f_a_s_t___g_l_o_b option causes ssuuddoo to use the _f_n_m_a_t_c_h(3) function, which does not access the file system to do its matching. The disadvantage of _f_a_s_t___g_l_o_b is that it is unable to match relative path names such as _._/_l_s or _._._/_b_i_n_/_l_s. This has security implications when path names that include globbing characters are used with the negation operator, '!', as such rules can be trivially bypassed. As such, this option should not be used when _s_u_d_o_e_r_s contains rules that contain negated path names which include globbing characters. This flag is _o_f_f by default. fqdn Set this flag if you want to put fully qualified host names in the _s_u_d_o_e_r_s file. I.e., instead of myhost you would use myhost.mydomain.edu. You may still use the short form if you wish (and even mix the two). Beware that turning on _f_q_d_n requires ssuuddoo to make DNS lookups which may make ssuuddoo unusable if DNS stops working (for example if the machine is not plugged into the network). Also note that you must use the host's official name as DNS knows it. That is, you may not use a host alias (CNAME entry) due to performance issues and the fact that there is no way to get all aliases from DNS. If your machine's host name (as returned by the hostname command) is already fully qualified you shouldn't need to set _f_q_d_n. This flag is _o_f_f by default. ignore_dot If set, ssuuddoo will ignore '.' or '' (current dir) in the PATH environment variable; the PATH itself is not modified. This flag is _o_f_f by default. ignore_local_sudoers If set via LDAP, parsing of _/_e_t_c_/_s_u_d_o_e_r_s 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 _/_e_t_c_/_s_u_d_o_e_r_s. When this option is present, _/_e_t_c_/_s_u_d_o_e_r_s does not even need to exist. Since this option tells ssuuddoo how to behave when no specific LDAP entries have been matched, this sudoOption is only meaningful for the cn=defaults section. This flag is _o_f_f by default. insults If set, ssuuddoo will insult users when they enter an incorrect password. This flag is _o_f_f by default. log_host If set, the host name will be logged in the (non- syslog) ssuuddoo log file. This flag is _o_f_f by default. log_input If set, ssuuddoo will run the command in a _p_s_e_u_d_o _t_t_y and log all user input. If the standard input is not connected to the user's tty, due to I/O redirection or because the command is part of a pipeline, that input is also captured and stored in a separate log file. Input is logged to the directory specified by the _i_o_l_o_g___d_i_r option (_/_v_a_r_/_l_o_g_/_s_u_d_o_-_i_o by default) using a unique session ID that is included in the normal ssuuddoo log line, prefixed with _T_S_I_D_=. The _i_o_l_o_g___f_i_l_e option may be used to control the format of the session ID. 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 _l_o_g___o_u_t_p_u_t is all that is required. log_output If set, ssuuddoo will run the command in a _p_s_e_u_d_o _t_t_y and log all output that is sent to the screen, similar to the _s_c_r_i_p_t(1) command. If the standard output or standard error is not connected to the user's tty, due to I/O redirection or because the command is part of a pipeline, that output is also captured and stored in separate log files. Output is logged to the directory specified by the _i_o_l_o_g___d_i_r option (_/_v_a_r_/_l_o_g_/_s_u_d_o_-_i_o by default) using a unique session ID that is included in the normal ssuuddoo log line, prefixed with _T_S_I_D_=. The _i_o_l_o_g___f_i_l_e option may be used to control the format of the session ID. Output logs may be viewed with the _s_u_d_o_r_e_p_l_a_y(1m) utility, which can also be used to list or search the available logs. log_year If set, the four-digit year will be logged in the (non- syslog) ssuuddoo log file. This flag is _o_f_f by default. long_otp_prompt When validating with a One Time Password (OTP) scheme such as SS//KKeeyy or OOPPIIEE, 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 _o_f_f by default. mail_always Send mail to the _m_a_i_l_t_o user every time a users runs ssuuddoo. This flag is _o_f_f by default. mail_badpass Send mail to the _m_a_i_l_t_o user if the user running ssuuddoo does not enter the correct password. This flag is _o_f_f by default. mail_no_host If set, mail will be sent to the _m_a_i_l_t_o user if the invoking user exists in the _s_u_d_o_e_r_s file, but is not allowed to run commands on the current host. This flag is _o_f_f by default. mail_no_perms If set, mail will be sent to the _m_a_i_l_t_o user if the invoking user is allowed to use ssuuddoo but the command they are trying is not listed in their _s_u_d_o_e_r_s file entry or is explicitly denied. This flag is _o_f_f by default. mail_no_user If set, mail will be sent to the _m_a_i_l_t_o user if the invoking user is not in the _s_u_d_o_e_r_s file. This flag is _o_n by default. noexec If set, all commands run via ssuuddoo will behave as if the NOEXEC tag has been set, unless overridden by a EXEC tag. See the description of _N_O_E_X_E_C _a_n_d _E_X_E_C below as well as the "PREVENTING SHELL ESCAPES" section at the end of this manual. This flag is _o_f_f by default. path_info Normally, ssuuddoo will tell the user when a command could not be found in their PATH environment variable. Some sites may wish to disable this as it could be used to gather information on the location of executables that the normal user does not have access to. The disadvantage is that if the executable is simply not in the user's PATH, ssuuddoo will tell the user that they are not allowed to run it, which can be confusing. This flag is _o_n by default. passprompt_override The password prompt specified by _p_a_s_s_p_r_o_m_p_t will normally only be used if the password prompt provided by systems such as PAM matches the string "Password:". If _p_a_s_s_p_r_o_m_p_t___o_v_e_r_r_i_d_e is set, _p_a_s_s_p_r_o_m_p_t will always be used. This flag is _o_f_f by default. preserve_groups By default, ssuuddoo will initialize the group vector to the list of groups the target user is in. When _p_r_e_s_e_r_v_e___g_r_o_u_p_s 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 _o_f_f by default. pwfeedback By default, ssuuddoo 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 ssuuddoo has hung at this point. When _p_w_f_e_e_d_b_a_c_k is set, ssuuddoo 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 _o_f_f by default. requiretty If set, ssuuddoo will only run when the user is logged in to a real tty. When this flag is set, ssuuddoo can only be run from a login session and not via other means such as _c_r_o_n(1m) or cgi-bin scripts. This flag is _o_f_f by default. root_sudo If set, root is allowed to run ssuuddoo too. Disabling this prevents users from "chaining" ssuuddoo commands to get a root shell by doing something like "sudo sudo /bin/sh". Note, however, that turning off _r_o_o_t___s_u_d_o will also prevent root from running ssuuddooeeddiitt. Disabling _r_o_o_t___s_u_d_o provides no real additional security; it exists purely for historical reasons. This flag is _o_n by default. rootpw If set, ssuuddoo will prompt for the root password instead of the password of the invoking user. This flag is _o_f_f by default. runaspw If set, ssuuddoo will prompt for the password of the user defined by the _r_u_n_a_s___d_e_f_a_u_l_t option (defaults to root) instead of the password of the invoking user. This flag is _o_f_f by default. set_home If enabled and ssuuddoo is invoked with the --ss option the HOME environment variable will be set to the home directory of the target user (which is root unless the --uu option is used). This effectively makes the --ss option imply --HH. Note that HOME is already set when the the _e_n_v___r_e_s_e_t option is enabled, so _s_e_t___h_o_m_e is only effective for configurations where either _e_n_v___r_e_s_e_t is disabled or HOME is present in the _e_n_v___k_e_e_p list. This flag is _o_f_f by default. set_logname Normally, ssuuddoo will set the LOGNAME, USER and USERNAME environment variables to the name of the target user (usually root unless the --uu option is given). However, since some programs (including the RCS revision control system) use LOGNAME to determine the real identity of the user, it may be desirable to change this behavior. This can be done by negating the set_logname option. Note that if the _e_n_v___r_e_s_e_t option has not been disabled, entries in the _e_n_v___k_e_e_p list will override the value of _s_e_t___l_o_g_n_a_m_e. This flag is _o_n by default. set_utmp When enabled, ssuuddoo will create an entry in the utmp (or utmpx) file when a pseudo-tty is allocated. A pseudo- tty is allocated by ssuuddoo when the _l_o_g___i_n_p_u_t, _l_o_g___o_u_t_p_u_t or _u_s_e___p_t_y 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 _o_n by default. setenv Allow the user to disable the _e_n_v___r_e_s_e_t option from the command line via the --EE option. Additionally, environment variables set via the command line are not subject to the restrictions imposed by _e_n_v___c_h_e_c_k, _e_n_v___d_e_l_e_t_e, or _e_n_v___k_e_e_p. As such, only trusted users should be allowed to set variables in this manner. This flag is _o_f_f by default. shell_noargs If set and ssuuddoo is invoked with no arguments it acts as if the --ss option had been given. That is, it runs a shell as root (the shell is determined by the SHELL environment variable if it is set, falling back on the shell listed in the invoking user's /etc/passwd entry if not). This flag is _o_f_f by default. stay_setuid Normally, when ssuuddoo 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 ssuuddoo 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 with either the _s_e_t_r_e_u_i_d_(_) or _s_e_t_r_e_s_u_i_d_(_) function. This flag is _o_f_f by default. targetpw If set, ssuuddoo will prompt for the password of the user specified by the --uu option (defaults to root) instead of the password of the invoking user. In addition, the timestamp file name will include the target user's name. Note that this flag precludes the use of a uid not listed in the passwd database as an argument to the --uu option. This flag is _o_f_f by default. tty_tickets If set, users must authenticate on a per-tty basis. With this flag enabled, ssuuddoo will use a file named for the tty the user is logged in on in the user's time stamp directory. If disabled, the time stamp of the directory is used instead. This flag is _o_n by default. umask_override If set, ssuuddoo will set the umask as specified by _s_u_d_o_e_r_s without modification. This makes it possible to specify a more permissive umask in _s_u_d_o_e_r_s than the user's own umask and matches historical behavior. If _u_m_a_s_k___o_v_e_r_r_i_d_e is not set, ssuuddoo will set the umask to be the union of the user's umask and what is specified in _s_u_d_o_e_r_s. This flag is _o_f_f by default. use_loginclass If set, ssuuddoo will apply the defaults specified for the target user's login class if one exists. Only available if ssuuddoo is configured with the --with-logincap option. This flag is _o_f_f by default. use_pty If set, ssuuddoo will run the command in a pseudo-pty even if no I/O logging is being gone. A malicious program run under ssuuddoo could conceivably fork a background process that retains to the user's terminal device after the main program has finished executing. Use of this option will make that impossible. This flag is _o_f_f by default. utmp_runas If set, ssuuddoo will store the name of the runas user when updating the utmp (or utmpx) file. By default, ssuuddoo stores the name of the invoking user. This flag is _o_f_f by default. visiblepw By default, ssuuddoo will refuse to run if the user must enter a password but it is not possible to disable echo on the terminal. If the _v_i_s_i_b_l_e_p_w flag is set, ssuuddoo will prompt for a password even when it would be visible on the screen. This makes it possible to run things like "rsh somehost sudo ls" since _r_s_h(1) does not allocate a tty. This flag is _o_f_f by default. IInntteeggeerrss: closefrom Before it executes a command, ssuuddoo will close all open file descriptors other than standard input, standard output and standard error (ie: file descriptors 0-2). The _c_l_o_s_e_f_r_o_m option can be used to specify a different file descriptor at which to start closing. The default is 3. passwd_tries The number of tries a user gets to enter his/her password before ssuuddoo logs the failure and exits. The default is 3. IInntteeggeerrss tthhaatt ccaann bbee uusseedd iinn aa bboooolleeaann ccoonntteexxtt: 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 80 (use 0 or negate the option to disable word wrap). passwd_timeout Number of minutes before the ssuuddoo password prompt times out, or 0 for no timeout. The timeout may include a fractional component if minute granularity is insufficient, for example 2.5. The default is 5. timestamp_timeout Number of minutes that can elapse before ssuuddoo will ask for a passwd again. The timeout may include a fractional component if minute granularity is insufficient, for example 2.5. The default is 5. Set this to 0 to always prompt for a password. If set to a value less than 0 the user's timestamp will never expire. This can be used to allow users to create or delete their own timestamps via sudo -v and sudo -k respectively. 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 _u_m_a_s_k option, which defaults to 0022. This guarantees that ssuuddoo 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 _s_u_d_o_e_r_s. SSttrriinnggss: badpass_message Message that is displayed if a user enters an incorrect password. The default is Sorry, try again. unless insults are enabled. editor A colon (':') separated list of editors allowed to be used with vviissuuddoo. vviissuuddoo will choose the editor that matches the user's EDITOR environment variable if possible, or the first editor in the list that exists and is executable. The default is "vi". iolog_dir The top-level directory to use when constructing the path name for the input/output log directory. Only used if the _l_o_g___i_n_p_u_t or _l_o_g___o_u_t_p_u_t options are enabled or when the LOG_INPUT or LOG_OUTPUT tags are present for a command. The session sequence number, if any, is stored in the directory. The default is "/var/log/sudo-io". The following percent (`%') escape sequences are supported: %{seq} expanded to a monotonically increasing base-36 sequence number, such as 0100A5, where every two digits are used to form a new directory, e.g. _0_1_/_0_0_/_A_5 %{user} expanded to the invoking user's login name %{group} expanded to the name of the invoking user's real group ID %{runas_user} expanded to the login name of the user the command will be run as (e.g. root) %{runas_group} expanded to the group name of the user the command will be run as (e.g. wheel) %{hostname} expanded to the local host name without the domain name %{command} expanded to the base name of the command being run In addition, any escape sequences supported by the system's _s_t_r_f_t_i_m_e_(_) function will be expanded. To include a literal `%' character, the string `%%' should be used. iolog_file The path name, relative to _i_o_l_o_g___d_i_r, in which to store input/output logs when the _l_o_g___i_n_p_u_t or _l_o_g___o_u_t_p_u_t options are enabled or when the LOG_INPUT or LOG_OUTPUT tags are present for a command. Note that _i_o_l_o_g___f_i_l_e may contain directory components. The default is "%{seq}". See the _i_o_l_o_g___d_i_r option above for a list of supported percent (`%') escape sequences. In addition to the escape sequences, path names that end in six or more Xs will have the Xs replaced with a unique combination of digits and letters, similar to the _m_k_t_e_m_p_(_) function. mailsub Subject of the mail sent to the _m_a_i_l_t_o user. The escape %h will expand to the host name of the machine. Default is *** SECURITY information for %h ***. noexec_file This option is deprecated and will be removed in a future release of ssuuddoo. The path to the noexec file should now be set in the _/_e_t_c_/_s_u_d_o_._c_o_n_f file. passprompt The default prompt to use when asking for a password; can be overridden via the --pp option or the SUDO_PROMPT environment variable. The following percent (`%') escape sequences are supported: %H expanded to the local host name including the domain name (only if the machine's host name is fully qualified or the _f_q_d_n option is set) %h expanded to the local host name without the domain name %p expanded to the user whose password is being asked for (respects the _r_o_o_t_p_w, _t_a_r_g_e_t_p_w and _r_u_n_a_s_p_w flags in _s_u_d_o_e_r_s) %U expanded to the login name of the user the command will be run as (defaults to root) %u expanded to the invoking user's login name %% two consecutive % characters are collapsed into a single % character The default value is Password:. 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 _s_u_d_o_e_r_s or via command line options. This option is only available whe ssuuddoo is built with SELinux support. runas_default The default user to run commands as if the --uu option is not specified on the command line. This defaults to root. syslog_badpri Syslog priority to use when user authenticates unsuccessfully. Defaults to alert. The following syslog priorities are supported: aalleerrtt, ccrriitt, ddeebbuugg, eemmeerrgg, eerrrr, iinnffoo, nnoottiiccee, and wwaarrnniinngg. syslog_goodpri Syslog priority to use when user authenticates successfully. Defaults to notice. See syslog_badpri for the list of supported syslog priorities. 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 "C". timestampdir The directory in which ssuuddoo stores its timestamp files. The default is _/_v_a_r_/_a_d_m_/_s_u_d_o. timestampowner The owner of the timestamp directory and the timestamps stored therein. The default is root. 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 _s_u_d_o_e_r_s or via command line options. This option is only available whe ssuuddoo is built with SELinux support. SSttrriinnggss tthhaatt ccaann bbee uusseedd iinn aa bboooolleeaann ccoonntteexxtt: env_file The _e_n_v___f_i_l_e options 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 VARIABLE=value or export VARIABLE=value. The value may optionally be surrounded by single or double quotes. Variables in this file are subject to other ssuuddoo environment settings such as _e_n_v___k_e_e_p and _e_n_v___c_h_e_c_k. exempt_group Users in this group are exempt from password and PATH requirements. The group name specified should not include a % prefix. This is not set by default. group_plugin A string containing a _s_u_d_o_e_r_s group plugin with optional arguments. This can be used to implement support for the nonunix_group syntax described earlier. The string should consist of the plugin path, either fully-qualified or relative to the _/_u_s_r_/_l_o_c_a_l_/_l_i_b_e_x_e_c 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 ("). For example, given _/_e_t_c_/_s_u_d_o_-_g_r_o_u_p, a group file in Unix group format, the sample group plugin can be used: Defaults group_plugin="sample_group.so /etc/sudo-group" For more information see _s_u_d_o___p_l_u_g_i_n(4). lecture This option controls when a short lecture will be printed along with the password prompt. It has the following possible values: always Always lecture the user. never Never lecture the user. once Only lecture the user the first time they run ssuuddoo. If no value is specified, a value of _o_n_c_e is implied. Negating the option results in a value of _n_e_v_e_r being used. The default value is _o_n_c_e. lecture_file Path to a file containing an alternate ssuuddoo lecture that will be used in place of the standard lecture if the named file exists. By default, ssuuddoo uses a built-in lecture. listpw This option controls when a password will be required when a user runs ssuuddoo with the --ll option. It has the following possible values: all All the user's _s_u_d_o_e_r_s entries for the current host must have the NOPASSWD flag set to avoid entering a password. always The user must always enter a password to use the --ll option. any At least one of the user's _s_u_d_o_e_r_s entries for the current host must have the NOPASSWD flag set to avoid entering a password. never The user need never enter a password to use the --ll option. If no value is specified, a value of _a_n_y is implied. Negating the option results in a value of _n_e_v_e_r being used. The default value is _a_n_y. logfile Path to the ssuuddoo log file (not the syslog log file). Setting a path turns on logging to a file; negating this option turns it off. By default, ssuuddoo logs via syslog. mailerflags Flags to use when invoking mailer. Defaults to --tt. mailerpath Path to mail program used to send warning mail. Defaults to the path to sendmail found at configure time. mailfrom Address to use for the "from" address when sending warning and error mail. The address should be enclosed in double quotes (") to protect against ssuuddoo interpreting the @ sign. Defaults to the name of the user running ssuuddoo. mailto Address to send warning and error mail to. The address should be enclosed in double quotes (") to protect against ssuuddoo interpreting the @ sign. Defaults to root. secure_path Path used for every command run from ssuuddoo. If you don't trust the people running ssuuddoo to have a sane PATH environment variable you may want to use this. Another use is if you want to have the "root path" be separate from the "user path." Users in the group specified by the _e_x_e_m_p_t___g_r_o_u_p option are not affected by _s_e_c_u_r_e___p_a_t_h. This option is not set by default. syslog Syslog facility if syslog is being used for logging (negate to disable syslog logging). Defaults to auth. The following syslog facilities are supported: aauutthhpprriivv (if your OS supports it), aauutthh, ddaaeemmoonn, uusseerr, llooccaall00, llooccaall11, llooccaall22, llooccaall33, llooccaall44, llooccaall55, llooccaall66, and llooccaall77. verifypw This option controls when a password will be required when a user runs ssuuddoo with the --vv option. It has the following possible values: all All the user's _s_u_d_o_e_r_s entries for the current host must have the NOPASSWD flag set to avoid entering a password. always The user must always enter a password to use the --vv option. any At least one of the user's _s_u_d_o_e_r_s entries for the current host must have the NOPASSWD flag set to avoid entering a password. never The user need never enter a password to use the --vv option. If no value is specified, a value of _a_l_l is implied. Negating the option results in a value of _n_e_v_e_r being used. The default value is _a_l_l. LLiissttss tthhaatt ccaann bbee uusseedd iinn aa bboooolleeaann ccoonntteexxtt: env_check Environment variables to be removed from the user's environment if the variable's value contains % or / characters. This can be used to guard against printf- style format vulnerabilities in poorly-written programs. 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 =, +=, -=, and ! operators respectively. Regardless of whether the env_reset option is enabled or disabled, variables specified by env_check will be preserved in the environment if they pass the aforementioned check. The default list of environment variables to check is displayed when ssuuddoo is run by root with the _-_V option. env_delete Environment variables to be removed from the user's environment when the _e_n_v___r_e_s_e_t 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 =, +=, -=, and ! operators respectively. The default list of environment variables to remove is displayed when ssuuddoo is run by root with the _-_V option. Note that many operating systems will remove potentially dangerous variables from the environment of any setuid process (such as ssuuddoo). env_keep Environment variables to be preserved in the user's environment when the _e_n_v___r_e_s_e_t option is in effect. This allows fine-grained control over the environment ssuuddoo-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 =, +=, -=, and ! operators respectively. The default list of variables to keep is displayed when ssuuddoo is run by root with the _-_V option. FFIILLEESS _/_e_t_c_/_s_u_d_o_e_r_s List of who can run what _/_e_t_c_/_g_r_o_u_p Local groups file _/_e_t_c_/_n_e_t_g_r_o_u_p List of network groups _/_v_a_r_/_l_o_g_/_s_u_d_o_-_i_o I/O log files _/_v_a_r_/_a_d_m_/_s_u_d_o Directory containing time stamps for the _s_u_d_o_e_r_s security policy _/_e_t_c_/_e_n_v_i_r_o_n_m_e_n_t Initial environment for --ii mode on Linux and AIX EEXXAAMMPPLLEESS Below are example _s_u_d_o_e_r_s entries. Admittedly, some of these are a bit contrived. First, we allow a few environment variables to pass and then define our _a_l_i_a_s_e_s: # 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 :\ SGI = grolsch, dandelion, black :\ ALPHA = widget, thalamus, foobar :\ 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,\ /usr/sbin/restore, /usr/sbin/rrestore 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, \ /usr/local/bin/tcsh, /usr/bin/rsh, \ /usr/local/bin/zsh Cmnd_Alias SU = /usr/bin/su Cmnd_Alias PAGERS = /usr/bin/more, /usr/bin/pg, /usr/bin/less Here we override some of the compiled in default values. We want ssuuddoo to log via _s_y_s_l_o_g(3) using the _a_u_t_h facility in all cases. We don't want to subject the full time staff to the ssuuddoo lecture, user mmiilllleerrtt need not give a password, and we don't want to reset the LOGNAME, USER or USERNAME environment variables when running commands as root. Additionally, on the machines in the _S_E_R_V_E_R_S Host_Alias, we keep an additional local log file and make sure we log the year in each log line since the log entries will be kept around for several years. Lastly, we disable shell escapes for the commands in the PAGERS Cmnd_Alias (_/_u_s_r_/_b_i_n_/_m_o_r_e, _/_u_s_r_/_b_i_n_/_p_g and _/_u_s_r_/_b_i_n_/_l_e_s_s). # 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 The _U_s_e_r _s_p_e_c_i_f_i_c_a_t_i_o_n is the part that actually determines who may run what. root ALL = (ALL) ALL %wheel ALL = (ALL) ALL We let rroooott and any user in group wwhheeeell run any command on any host as any user. FULLTIMERS ALL = NOPASSWD: ALL Full time sysadmins (mmiilllleerrtt, mmiikkeeff, and ddoowwddyy) may run any command on any host without authenticating themselves. PARTTIMERS ALL = ALL Part time sysadmins (bboossttlleeyy, jjwwffooxx, and ccrraawwll) may run any command on any host but they must authenticate themselves first (since the entry lacks the NOPASSWD tag). jack CSNETS = ALL The user jjaacckk may run any command on the machines in the _C_S_N_E_T_S alias (the networks 128.138.243.0, 128.138.204.0, and 128.138.242.0). Of those networks, only 128.138.204.0 has an explicit netmask (in CIDR notation) indicating it is a class C network. For the other networks in _C_S_N_E_T_S, the local machine's netmask will be used during matching. lisa CUNETS = ALL The user lliissaa may run any command on any host in the _C_U_N_E_T_S alias (the class B network 128.138.0.0). operator ALL = DUMPS, KILL, SHUTDOWN, HALT, REBOOT, PRINTING,\ sudoedit /etc/printcap, /usr/oper/bin/ The ooppeerraattoorr 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 _/_u_s_r_/_o_p_e_r_/_b_i_n_/. joe ALL = /usr/bin/su operator The user jjooee may only _s_u(1) to operator. pete HPPA = /usr/bin/passwd [A-Za-z]*, !/usr/bin/passwd root %opers ALL = (: ADMINGRP) /usr/sbin/ Users in the ooppeerrss group may run commands in _/_u_s_r_/_s_b_i_n_/ as themselves with any group in the _A_D_M_I_N_G_R_P Runas_Alias (the aaddmm and ooppeerr groups). The user ppeettee is allowed to change anyone's password except for root on the _H_P_P_A machines. Note that this assumes _p_a_s_s_w_d(1) does not take multiple user names on the command line. bob SPARC = (OP) ALL : SGI = (OP) ALL The user bboobb may run anything on the _S_P_A_R_C and _S_G_I machines as any user listed in the _O_P Runas_Alias (rroooott and ooppeerraattoorr). jim +biglab = ALL The user jjiimm may run any command on machines in the _b_i_g_l_a_b netgroup. ssuuddoo knows that "biglab" is a netgroup due to the '+' prefix. +secretaries ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser Users in the sseeccrreettaarriieess 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. fred ALL = (DB) NOPASSWD: ALL The user ffrreedd can run commands as any user in the _D_B Runas_Alias (oorraaccllee or ssyybbaassee) without giving a password. john ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root* On the _A_L_P_H_A machines, user jjoohhnn may su to anyone except root but he is not allowed to specify any options to the _s_u(1) command. jen ALL, !SERVERS = ALL The user jjeenn may run any command on any machine except for those in the _S_E_R_V_E_R_S Host_Alias (master, mail, www and ns). jill SERVERS = /usr/bin/, !SU, !SHELLS For any machine in the _S_E_R_V_E_R_S Host_Alias, jjiillll may run any commands in the directory _/_u_s_r_/_b_i_n_/ except for those commands belonging to the _S_U and _S_H_E_L_L_S Cmnd_Aliases. steve CSNETS = (operator) /usr/local/op_commands/ The user sstteevvee may run any command in the directory /usr/local/op_commands/ but only as user operator. matt valkyrie = KILL On his personal workstation, valkyrie, mmaatttt needs to be able to kill hung processes. WEBMASTERS www = (www) ALL, (root) /usr/bin/su www On the host www, any user in the _W_E_B_M_A_S_T_E_R_S User_Alias (will, wendy, and wim), may run any command as user www (which owns the web pages) or simply _s_u(1) to www. ALL CDROM = NOPASSWD: /sbin/umount /CDROM,\ /sbin/mount -o nosuid\,nodev /dev/cd0a /CDROM Any user may mount or unmount a CD-ROM on the machines in the CDROM Host_Alias (orion, perseus, hercules) without entering a password. This is a bit tedious for users to type, so it is a prime candidate for encapsulating in a shell script. SSEECCUURRIITTYY NNOOTTEESS It is generally not effective to "subtract" commands from ALL using the '!' operator. A user can trivially circumvent this by copying the desired command to a different name and then executing that. For example: bill ALL = ALL, !SU, !SHELLS Doesn't really prevent bbiillll from running the commands listed in _S_U or _S_H_E_L_L_S 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). Furthermore, if the _f_a_s_t___g_l_o_b 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 _f_n_m_a_t_c_h(3) function cannot resolve relative paths. While this is typically only an inconvenience for rules that grant privileges, it can result in a security issue for rules that subtract or revoke privileges. For example, given the following _s_u_d_o_e_r_s entry: john ALL = /usr/bin/passwd [a-zA-Z0-9]*, /usr/bin/chsh [a-zA-Z0-9]*, /usr/bin/chfn [a-zA-Z0-9]*, !/usr/bin/* root User jjoohhnn can still run /usr/bin/passwd root if _f_a_s_t___g_l_o_b is enabled by changing to _/_u_s_r_/_b_i_n and running ./passwd root instead. PPRREEVVEENNTTIINNGG SSHHEELLLL EESSCCAAPPEESS Once ssuuddoo 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 ssuuddoo's access control and logging. Common programs that permit shell escapes include shells (obviously), editors, paginators, mail and terminal programs. There are two basic approaches to this problem: 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 ssuuddooeeddiitt is a better solution to running editors via ssuuddoo. Due to the large number of programs that offer shell escapes, restricting users to the set of programs that do not is often unworkable. noexec Many systems that support shared libraries have the ability to override default library functions by pointing an environment variable (usually LD_PRELOAD) to an alternate shared library. On such systems, ssuuddoo's _n_o_e_x_e_c functionality can be used to prevent a program run by ssuuddoo 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. The _n_o_e_x_e_c feature is known to work on SunOS, Solaris, *BSD, Linux, IRIX, Tru64 UNIX, MacOS X, HP-UX 11.x and AIX 5.3 and above. It should be supported on most operating systems that support the LD_PRELOAD 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 LD_PRELOAD is supported. On Solaris 10 and higher, _n_o_e_x_e_c uses Solaris privileges instead of the LD_PRELOAD environment variable. To enable _n_o_e_x_e_c for a command, use the NOEXEC tag as documented in the User Specification section above. Here is that example again: aaron shanty = NOEXEC: /usr/bin/more, /usr/bin/vi This allows user aaaarroonn to run _/_u_s_r_/_b_i_n_/_m_o_r_e and _/_u_s_r_/_b_i_n_/_v_i with _n_o_e_x_e_c 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 _n_o_e_x_e_c you can always just try it out and check whether shell escapes work when _n_o_e_x_e_c is enabled. 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 ssuuddooeeddiitt. SSEECCUURRIITTYY NNOOTTEESS _s_u_d_o_e_r_s will check the ownership of its time stamp directory (_/_v_a_r_/_a_d_m_/_s_u_d_o 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. On systems that allow non-root users to give away files via _c_h_o_w_n(2), if the time stamp directory is located in a world-writable directory (e.g., _/_t_m_p), it is possible for a user to create the time stamp directory before ssuuddoo is run. However, because _s_u_d_o_e_r_s checks the ownership and mode of the directory and its contents, the only damage that can be done is to "hide" files by putting them in the time stamp dir. This is unlikely to happen since once the time stamp dir is owned by root and inaccessible by any other user, the user placing files there would be unable to get them back out. _s_u_d_o_e_r_s will not honor time stamps set far in the future. Time stamps with a date greater than current_time + 2 * TIMEOUT will be ignored and sudo will log and complain. This is done to keep a user from creating his/her own time stamp with a bogus date on systems that allow users to give away files if the time stamp directory is located in a world- writable directory. On systems where the boot time is available, _s_u_d_o_e_r_s will ignore time stamps that date from before the machine booted. Since time stamp files live in the file system, they can outlive a user's login session. As a result, a user may be able to login, run a command with ssuuddoo after authenticating, logout, login again, and run ssuuddoo without authenticating so long as the time stamp file's modification time is within 5 minutes (or whatever the timeout is set to in _s_u_d_o_e_r_s). When the _t_t_y___t_i_c_k_e_t_s option is enabled, the time stamp has per-tty granularity but still may outlive the user's session. On Linux systems where the devpts filesystem is used, Solaris systems with the devices filesystem, as well as other systems that utilize a devfs filesystem that monotonically increase the inode number of devices as they are created (such as Mac OS X), _s_u_d_o_e_r_s is able to determine when a tty-based time stamp file is stale and will ignore it. Administrators should not rely on this feature as it is not universally available. If users have sudo ALL 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 '!' elements in the user specification. SSEEEE AALLSSOO _r_s_h(1), _s_u(1), _f_n_m_a_t_c_h(3), _g_l_o_b(3), _m_k_t_e_m_p(3), _s_t_r_f_t_i_m_e(3), _s_u_d_o_e_r_s_._l_d_a_p(4), _s_u_d_o___p_l_u_g_i_n(1m), _s_u_d_o(1m), _v_i_s_u_d_o(1m) CCAAVVEEAATTSS The _s_u_d_o_e_r_s file should aallwwaayyss be edited by the vviissuuddoo command which locks the file and does grammatical checking. It is imperative that _s_u_d_o_e_r_s be free of syntax errors since ssuuddoo will not run with a syntactically incorrect _s_u_d_o_e_r_s file. 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 hostname command or use the _f_q_d_n option in _s_u_d_o_e_r_s. BBUUGGSS If you feel you have found a bug in ssuuddoo, please submit a bug report at http://www.sudo.ws/sudo/bugs/ SSUUPPPPOORRTT Limited free support is available via the sudo-users mailing list, see http://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the archives. DDIISSCCLLAAIIMMEERR ssuuddoo is provided ``AS IS'' and any express or implied warranties, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose are disclaimed. See the LICENSE file distributed with ssuuddoo or http://www.sudo.ws/sudo/license.html for complete details. 1.8.3 September 16, 2011 SUDOERS(4)