SUDO(1m) MAINTENANCE COMMANDS SUDO(1m) NNAAMMEE sudo, sudoedit - execute a command as another user SSYYNNOOPPSSIISS ssuuddoo [--DD _l_e_v_e_l] --hh | --KK | --kk | --VV ssuuddoo --vv [--AAkknnSS] [--aa _a_u_t_h___t_y_p_e] [--DD _l_e_v_e_l] [--gg _g_r_o_u_p _n_a_m_e|_#_g_i_d] [--pp _p_r_o_m_p_t] [--uu _u_s_e_r _n_a_m_e|_#_u_i_d] ssuuddoo --ll[[ll]] [--AAkknnSS] [--aa _a_u_t_h___t_y_p_e] [--DD _l_e_v_e_l] [--gg _g_r_o_u_p _n_a_m_e|_#_g_i_d] [--pp _p_r_o_m_p_t] [--UU _u_s_e_r _n_a_m_e] [--uu _u_s_e_r _n_a_m_e|_#_u_i_d] [_c_o_m_m_a_n_d] ssuuddoo [--AAbbEEHHnnPPSS] [--aa _a_u_t_h___t_y_p_e] [--CC _f_d] [--DD _l_e_v_e_l] [--cc _c_l_a_s_s|_-] [--gg _g_r_o_u_p _n_a_m_e|_#_g_i_d] [--pp _p_r_o_m_p_t] [--rr _r_o_l_e] [--tt _t_y_p_e] [--uu _u_s_e_r _n_a_m_e|_#_u_i_d] [VVAARR=_v_a_l_u_e] [--ii | --ss] [_c_o_m_m_a_n_d] ssuuddooeeddiitt [--AAnnSS] [--aa _a_u_t_h___t_y_p_e] [--CC _f_d] [--cc _c_l_a_s_s|_-] [--DD _l_e_v_e_l] [--gg _g_r_o_u_p _n_a_m_e|_#_g_i_d] [--pp _p_r_o_m_p_t] [--uu _u_s_e_r _n_a_m_e|_#_u_i_d] file ... DDEESSCCRRIIPPTTIIOONN ssuuddoo allows a permitted user to execute a _c_o_m_m_a_n_d as the superuser or another user, as specified by the security policy. The real and effective uid and gid are set to match those of the target user, as specified in the password database, and the group vector is initialized based on the group database (unless the --PP option was specified). ssuuddoo supports a plugin architecture for security policies and input/output logging. Third parties can develop and distribute their own policy and I/O logging modules to work seemlessly with the ssuuddoo front end. The default security policy is _s_u_d_o_e_r_s, which is configured via the file _/_e_t_c_/_s_u_d_o_e_r_s, or via LDAP. See the PLUGINS section for more information. The security policy determines what privileges, if any, a user has to run ssuuddoo. The policy may require that users authenticate themselves with a password or another authentication mechanism. If authentication is required, ssuuddoo will exit if the user's password is not entered within a configurable time limit. This limit is policy-specific; the default password prompt timeout for the _s_u_d_o_e_r_s security policy is 5 minutes. Security policies may support credential caching to allow the user to run ssuuddoo again for a period of time without requiring authentication. The _s_u_d_o_e_r_s policy caches credentials for 5 minutes, unless overridden in _s_u_d_o_e_r_s(4). By running ssuuddoo with the --vv option, a user can update the cached credentials without running a _c_o_m_m_a_n_d. When invoked as ssuuddooeeddiitt, the --ee option (described below), is implied. Security policies may log successful and failed attempts to use ssuuddoo. If an I/O plugin is configured, the running command's input and output may be logged as well. OOPPTTIIOONNSS ssuuddoo accepts the following command line options: -A Normally, if ssuuddoo requires a password, it will read it from the user's terminal. If the --AA (_a_s_k_p_a_s_s) option is specified, a (possibly graphical) helper program is executed to read the user's password and output the password to the standard output. If the SUDO_ASKPASS environment variable is set, it specifies the path to the helper program. Otherwise, if _/_e_t_c_/_s_u_d_o_._c_o_n_f contains a line specifying the askpass program, that value will be used. For example: # Path to askpass helper program Path askpass /usr/X11R6/bin/ssh-askpass If no askpass program is available, sudo will exit with an error. -a _t_y_p_e The --aa (_a_u_t_h_e_n_t_i_c_a_t_i_o_n _t_y_p_e) option causes ssuuddoo to use the specified authentication type when validating the user, as allowed by _/_e_t_c_/_l_o_g_i_n_._c_o_n_f. The system administrator may specify a list of sudo-specific authentication methods by adding an "auth-sudo" entry in _/_e_t_c_/_l_o_g_i_n_._c_o_n_f. This option is only available on systems that support BSD authentication. -b The --bb (_b_a_c_k_g_r_o_u_n_d) option tells ssuuddoo to run the given command in the background. Note that if you use the --bb option you cannot use shell job control to manipulate the process. Most interactive commands will fail to work properly in background mode. -C _f_d Normally, ssuuddoo will close all open file descriptors other than standard input, standard output and standard error. The --CC (_c_l_o_s_e _f_r_o_m) option allows the user to specify a starting point above the standard error (file descriptor three). Values less than three are not permitted. The security policy may restrict the user's ability to use the --CC option. The _s_u_d_o_e_r_s policy only permits use of the --CC option when the administrator has enabled the _c_l_o_s_e_f_r_o_m___o_v_e_r_r_i_d_e option. -c _c_l_a_s_s The --cc (_c_l_a_s_s) option causes ssuuddoo to run the specified command with resources limited by the specified login class. The _c_l_a_s_s argument can be either a class name as defined in _/_e_t_c_/_l_o_g_i_n_._c_o_n_f, or a single '-' character. Specifying a _c_l_a_s_s of - indicates that the command should be run restricted by the default login capabilities for the user the command is run as. If the _c_l_a_s_s argument specifies an existing user class, the command must be run as root, or the ssuuddoo command must be run from a shell that is already root. This option is only available on systems with BSD login classes. -D _l_e_v_e_l Enable debugging of ssuuddoo plugins and ssuuddoo itself. The _l_e_v_e_l may be a value from 1 through 9. -E The --EE (_p_r_e_s_e_r_v_e _e_n_v_i_r_o_n_m_e_n_t) option indicates to the security policy that the user wishes to preserve their existing environment variables. The security policy may return an error if the --EE option is specified and the user does not have permission to preserve the environment. -e The --ee (_e_d_i_t) option indicates that, instead of running a command, the user wishes to edit one or more files. In lieu of a command, the string "sudoedit" is used when consulting the security policy. If the user is authorized by the policy, the following steps are taken: 1. Temporary copies are made of the files to be edited with the owner set to the invoking user. 2. The editor specified by the policy is run to edit the temporary files. The _s_u_d_o_e_r_s policy uses the SUDO_EDITOR, VISUAL and EDITOR environment variables (in that order). If none of SUDO_EDITOR, VISUAL or EDITOR are set, the first program listed in the _e_d_i_t_o_r _s_u_d_o_e_r_s(4) option is used. 3. If they have been modified, the temporary files are copied back to their original location and the temporary versions are removed. If the specified file does not exist, it will be created. Note that unlike most commands run by ssuuddoo, the editor is run with the invoking user's environment unmodified. If, for some reason, ssuuddoo is unable to update a file with its edited version, the user will receive a warning and the edited copy will remain in a temporary file. -g _g_r_o_u_p Normally, ssuuddoo runs a command with the primary group set to the one specified by the password database for the user the command is being run as (by default, root). The --gg (_g_r_o_u_p) option causes ssuuddoo to run the command with the primary group set to _g_r_o_u_p instead. To specify a _g_i_d instead of a _g_r_o_u_p _n_a_m_e, use _#_g_i_d. When running commands as a _g_i_d, many shells require that the '#' be escaped with a backslash ('\'). If no --uu option is specified, the command will be run as the invoking user (not root). In either case, the primary group will be set to _g_r_o_u_p. -H The --HH (_H_O_M_E) option requests that the security policy set the HOME environment variable to the home directory of the target user (root by default) as specified by the password database. Depending on the policy, this may be the default behavior. -h The --hh (_h_e_l_p) option causes ssuuddoo to print a short help message to the standard output and exit. -i [command] The --ii (_s_i_m_u_l_a_t_e _i_n_i_t_i_a_l _l_o_g_i_n) option runs the shell specified by the password database entry of the target user as a login shell. This means that login-specific resource files such as .profile or .login will be read by the shell. If a command is specified, it is passed to the shell for execution via the shell's --cc option. If no command is specified, an interactive shell is executed. ssuuddoo attempts to change to that user's home directory before running the shell. The security policy shall initialize the environment to a minimal set of variables, similar to what is present when a user logs in. The _C_o_m_m_a_n_d _E_n_v_i_r_o_n_m_e_n_t section in the _s_u_d_o_e_r_s(4) manual documents how the --ii option affects the environment in which a command is run when the _s_u_d_o_e_r_s policy is in use. -K The --KK (sure _k_i_l_l) option is like --kk except that it removes the user's cached credentials entirely and may not be used in conjunction with a command or other option. This option does not require a password. Not all security policies support credential caching. -k [command] When used alone, the --kk (_k_i_l_l) option to ssuuddoo invalidates the user's cached credentials. The next time ssuuddoo is run a password will be required. This option does not require a password and was added to allow a user to revoke ssuuddoo permissions from a .logout file. Not all security policies support credential caching. When used in conjunction with a command or an option that may require a password, the --kk option will cause ssuuddoo to ignore the user's cached credentials. As a result, ssuuddoo will prompt for a password (if one is required by the security policy) and will not update the user's cached credentials. -l[l] [_c_o_m_m_a_n_d] If no _c_o_m_m_a_n_d is specified, the --ll (_l_i_s_t) option will list the allowed (and forbidden) commands for the invoking user (or the user specified by the --UU option) on the current host. If a _c_o_m_m_a_n_d is specified and is permitted by the security policy, the fully-qualified path to the command is displayed along with any command line arguments. If _c_o_m_m_a_n_d is specified but not allowed, ssuuddoo will exit with a status value of 1. If the --ll option is specified with an ll argument (i.e. --llll), or if --ll is specified multiple times, a longer list format is used. -n The --nn (_n_o_n_-_i_n_t_e_r_a_c_t_i_v_e) option prevents ssuuddoo from prompting the user for a password. If a password is required for the command to run, ssuuddoo will display an error messages and exit. -P The --PP (_p_r_e_s_e_r_v_e _g_r_o_u_p _v_e_c_t_o_r) option causes ssuuddoo to preserve the invoking user's group vector unaltered. By default, the _s_u_d_o_e_r_s policy will initialize the group vector to the list of groups the target user is in. The real and effective group IDs, however, are still set to match the target user. -p _p_r_o_m_p_t The --pp (_p_r_o_m_p_t) option allows you to override the default password prompt and use a custom one. The following percent (`%') escapes are supported by the _s_u_d_o_e_r_s policy: %H expanded to the host name including the domain name (on if the machine's host name is fully qualified or the _f_q_d_n option is set in _s_u_d_o_e_r_s(4)) %h expanded to the local host name without the domain name %p expanded to the name of the user whose password is being requested (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(4)) %U expanded to the login name of the user the command will be run as (defaults to root unless the -u option is also specified) %u expanded to the invoking user's login name %% two consecutive % characters are collapsed into a single % character The prompt specified by the --pp option will override the system password prompt on systems that support PAM unless the _p_a_s_s_p_r_o_m_p_t___o_v_e_r_r_i_d_e flag is disabled in _s_u_d_o_e_r_s. -r _r_o_l_e The --rr (_r_o_l_e) option causes the new (SELinux) security context to have the role specified by _r_o_l_e. -S The --SS (_s_t_d_i_n) option causes ssuuddoo to read the password from the standard input instead of the terminal device. The password must be followed by a newline character. -s [command] The --ss (_s_h_e_l_l) option runs the shell specified by the _S_H_E_L_L environment variable if it is set or the shell as specified in the password database. If a command is specified, it is passed to the shell for execution via the shell's --cc option. If no command is specified, an interactive shell is executed. -t _t_y_p_e The --tt (_t_y_p_e) option causes the new (SELinux) security context to have the type specified by _t_y_p_e. If no type is specified, the default type is derived from the specified role. -U _u_s_e_r The --UU (_o_t_h_e_r _u_s_e_r) option is used in conjunction with the --ll option to specify the user whose privileges should be listed. The security policy may restrict listing other users' privileges. The _s_u_d_o_e_r_s policy only allows root or a user with the ALL privilege on the current host to use this option. -u _u_s_e_r The --uu (_u_s_e_r) option causes ssuuddoo to run the specified command as a user other than _r_o_o_t. To specify a _u_i_d instead of a _u_s_e_r _n_a_m_e, use _#_u_i_d. When running commands as a _u_i_d, many shells require that the '#' be escaped with a backslash ('\'). Security policies may restrict _u_i_ds to those listed in the password database. The _s_u_d_o_e_r_s policy allows _u_i_ds that are not in the password database as long as the _t_a_r_g_e_t_p_w option is not set. Other security policies may not support this. -V The --VV (_v_e_r_s_i_o_n) option causes ssuuddoo to print its version string and the version string of the security policy plugin and any I/O plugins. If the invoking user is already root the --VV option will display the arguments passed to configure when _s_u_d_o was built and plugins may display more verbose information such as default options. -v When given the --vv (_v_a_l_i_d_a_t_e) option, ssuuddoo will update the user's cached credentials, authenticating the user's password if necessary. For the _s_u_d_o_e_r_s plugin, this extends the ssuuddoo timeout for another 5 minutes (or whatever the timeout is set to in _s_u_d_o_e_r_s) but does not run a command. Not all security policies support cached credentials. -- The ---- option indicates that ssuuddoo should stop processing command line arguments. Environment variables to be set for the command may also be passed on the command line in the form of VVAARR=_v_a_l_u_e, e.g. LLDD__LLIIBBRRAARRYY__PPAATTHH=_/_u_s_r_/_l_o_c_a_l_/_p_k_g_/_l_i_b. Variables passed on the command line are subject to the same restrictions as normal environment variables with one important exception. If the _s_e_t_e_n_v option is set in _s_u_d_o_e_r_s, the command to be run has the SETENV tag set or the command matched is ALL, the user may set variables that would overwise be forbidden. See _s_u_d_o_e_r_s(4) for more information. PPLLUUGGIINNSS Plugins are dynamically loaded based on the contents of the _/_e_t_c_/_s_u_d_o_._c_o_n_f file. If no _/_e_t_c_/_s_u_d_o_._c_o_n_f file is present, or it contains no Plugin lines, ssuuddoo will use the traditional _s_u_d_o_e_r_s security policy and I/O logging, which corresponds to the following _/_e_t_c_/_s_u_d_o_._c_o_n_f file. # # Default /etc/sudo.conf file # # Format: # Plugin plugin_name plugin_path # Path askpass /path/to/askpass # Path noexec /path/to/noexec.so # # The plugin_path is relative to /usr/local/libexec unless # fully qualified. # The plugin_name corresponds to a global symbol in the plugin # that contains the plugin interface structure. # Plugin policy_plugin sudoers.so Plugin io_plugin sudoers.so A Plugin line consists of the Plugin keyword, followed by the _s_y_m_b_o_l___n_a_m_e and the _p_a_t_h to the shared object containing the plugin. The _s_y_m_b_o_l___n_a_m_e is the name of the struct policy_plugin or struct io_plugin in the plugin shared object. The _p_a_t_h may be fully qualified or relative. If not fully qualified it is relative to the _/_u_s_r_/_l_o_c_a_l_/_l_i_b_e_x_e_c directory. Any additional parameters after the _p_a_t_h are ignored. Lines that don't begin with Plugin or Path are silently ignored For more information, see the _s_u_d_o___p_l_u_g_i_n(1m) manual. PPAATTHHSS A Path line consists of the Path keyword, followed by the name of the path to set and its value. E.g. Path noexec /usr/local/libexec/sudo_noexec.so Path askpass /usr/X11R6/bin/ssh-askpass The following plugin-agnostic paths may be set in the _/_e_t_c_/_s_u_d_o_._c_o_n_f file. askpass The fully qualified path to a helper program used to read the user's password when no terminal is available. This may be the case when ssuuddoo is executed from a graphical (as opposed to text-based) application. The program specified by _a_s_k_p_a_s_s should display the argument passed to it as the prompt and write the user's password to the standard output. The value of _a_s_k_p_a_s_s may be overridden by the SUDO_ASKPASS environment variable. noexec The fully-qualified path to a shared library containing dummy versions of the _e_x_e_c_v_(_), _e_x_e_c_v_e_(_) and _f_e_x_e_c_v_e_(_) library functions that just return an error. This is used to implement the _n_o_e_x_e_c functionality on systems that support LD_PRELOAD or its equivalent. Defaults to _/_u_s_r_/_l_o_c_a_l_/_l_i_b_e_x_e_c_/_s_u_d_o___n_o_e_x_e_c_._s_o. RREETTUURRNN VVAALLUUEESS Upon successful execution of a program, the exit status from ssuuddoo will simply be the exit status of the program that was executed. Otherwise, ssuuddoo exits with a value of 1 if there is a configuration/permission problem or if ssuuddoo cannot execute the given command. In the latter case the error string is printed to the standard error. If ssuuddoo cannot _s_t_a_t(2) one or more entries in the user's PATH, an error is printed on stderr. (If the directory does not exist or if it is not really a directory, the entry is ignored and no error is printed.) This should not happen under normal circumstances. The most common reason for _s_t_a_t(2) to return "permission denied" is if you are running an automounter and one of the directories in your PATH is on a machine that is currently unreachable. SSEECCUURRIITTYY NNOOTTEESS ssuuddoo tries to be safe when executing external commands. To prevent command spoofing, ssuuddoo checks "." and "" (both denoting current directory) last when searching for a command in the user's PATH (if one or both are in the PATH). Note, however, that the actual PATH environment variable is _n_o_t modified and is passed unchanged to the program that ssuuddoo executes. Please note that ssuuddoo will normally only log the command it explicitly runs. If a user runs a command such as sudo su or sudo sh, subsequent commands run from that shell are not subject to ssuuddoo's security policy. The same is true for commands that offer shell escapes (including most editors). If I/O logging is enabled, subsequent commands will have their input and/or output logged, but there will not be traditional logs for those commands. Because of this, care must be taken when giving users access to commands via ssuuddoo to verify that the command does not inadvertently give the user an effective root shell. For more information, please see the PREVENTING SHELL ESCAPES section in _s_u_d_o_e_r_s(4). EENNVVIIRROONNMMEENNTT ssuuddoo utilizes the following environment variables. The security policy has control over the content of the command's environment. EDITOR Default editor to use in --ee (sudoedit) mode if neither SUDO_EDITOR nor VISUAL is set MAIL In --ii mode or when _e_n_v___r_e_s_e_t is enabled in _s_u_d_o_e_r_s, set to the mail spool of the target user HOME Set to the home directory of the target user if --ii or --HH are specified, _e_n_v___r_e_s_e_t or _a_l_w_a_y_s___s_e_t___h_o_m_e are set in _s_u_d_o_e_r_s, or when the --ss option is specified and _s_e_t___h_o_m_e is set in _s_u_d_o_e_r_s PATH May be overridden by the security policy. SHELL Used to determine shell to run with -s option SUDO_ASKPASS Specifies the path to a helper program used to read the password if no terminal is available or if the -A option is specified. SUDO_COMMAND Set to the command run by sudo SUDO_EDITOR Default editor to use in --ee (sudoedit) mode SUDO_GID Set to the group ID of the user who invoked sudo SUDO_PROMPT Used as the default password prompt SUDO_PS1 If set, PS1 will be set to its value for the program being run SUDO_UID Set to the user ID of the user who invoked sudo SUDO_USER Set to the login of the user who invoked sudo USER Set to the target user (root unless the --uu option is specified) VISUAL Default editor to use in --ee (sudoedit) mode if SUDO_EDITOR is not set FFIILLEESS _/_e_t_c_/_s_u_d_o_._c_o_n_f ssuuddoo plugin and path configuration EEXXAAMMPPLLEESS Note: the following examples assume a properly configured security policy. To get a file listing of an unreadable directory: $ sudo ls /usr/local/protected To list the home directory of user yaz on a machine where the file system holding ~yaz is not exported as root: $ sudo -u yaz ls ~yaz To edit the _i_n_d_e_x_._h_t_m_l file as user www: $ sudo -u www vi ~www/htdocs/index.html To view system logs only accessible to root and users in the adm group: $ sudo -g adm view /var/log/syslog To run an editor as jim with a different primary group: $ sudo -u jim -g audio vi ~jim/sound.txt To shutdown a machine: $ sudo shutdown -r +15 "quick reboot" To make a usage listing of the directories in the /home partition. Note that this runs the commands in a sub-shell to make the cd and file redirection work. $ sudo sh -c "cd /home ; du -s * | sort -rn > USAGE" SSEEEE AALLSSOO _g_r_e_p(1), _s_u(1), _s_t_a_t(2), _l_o_g_i_n___c_a_p(3), _p_a_s_s_w_d(4), _s_u_d_o_e_r_s(4), _s_u_d_o___p_l_u_g_i_n(1m), _s_u_d_o_r_e_p_l_a_y(1m), _v_i_s_u_d_o(1m) AAUUTTHHOORRSS Many people have worked on ssuuddoo over the years; this version consists of code written primarily by: Todd C. Miller See the HISTORY file in the ssuuddoo distribution or visit http://www.sudo.ws/sudo/history.html for a short history of ssuuddoo. CCAAVVEEAATTSS There is no easy way to prevent a user from gaining a root shell if that user is allowed to run arbitrary commands via ssuuddoo. Also, many programs (such as editors) allow the user to run commands via shell escapes, thus avoiding ssuuddoo's checks. However, on most systems it is possible to prevent shell escapes with the _s_u_d_o_e_r_s(4) module's _n_o_e_x_e_c functionality. It is not meaningful to run the cd command directly via sudo, e.g., $ sudo cd /usr/local/protected since when the command exits the parent process (your shell) will still be the same. Please see the EXAMPLES section for more information. Running shell scripts via ssuuddoo can expose the same kernel bugs that make setuid shell scripts unsafe on some operating systems (if your OS has a /dev/fd/ directory, setuid shell scripts are generally safe). 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 SUDO(1m)