SUDO(1m) System Manager's Manual SUDO(1m)
NNAAMMEE
ssuuddoo, ssuuddooeeddiitt - execute a command as another user
SSYYNNOOPPSSIISS
ssuuddoo --hh | --KK | --kk | --VV
ssuuddoo --vv [--AAkknnSS] [--aa _a_u_t_h___t_y_p_e] [--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[_l] [--AAkknnSS] [--aa _a_u_t_h___t_y_p_e] [--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] [--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 | _-]
[--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.
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 plugins to work seamlessly 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 _P_l_u_g_i_n_s 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
sudoers(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.
The options are as follows:
--AA 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 sudo.conf(4) 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, ssuuddoo will exit with an
error.
--aa _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.
--bb 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.
--CC _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.
--cc _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.
--EE 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.
--ee 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
sudoers(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 _s_u_d_o, 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.
--gg _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.
--HH 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.
--hh The --hh (_h_e_l_p) option causes ssuuddoo to print a short help
message to the standard output and exit.
--ii [_c_o_m_m_a_n_d]
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 _._p_r_o_f_i_l_e or _._l_o_g_i_n 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
sudoers(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.
--KK 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.
--kk [_c_o_m_m_a_n_d]
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 _._l_o_g_o_u_t 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.
--ll[ll] [_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 _l argument (i.e.
--llll), or if --ll is specified multiple times, a longer list
format is used.
--nn 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 message and exit.
--PP 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.
--pp _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 sudoers(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 sudoers(4))
%U expanded to the login name of the user the command will
be run as (defaults to root unless the --uu 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.
--rr _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.
--SS 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.
--ss [_c_o_m_m_a_n_d]
The --ss (_s_h_e_l_l) option runs the shell specified by the SHELL
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.
--tt _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.
--UU _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.
--uu _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, _#_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.
--VV 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 ssuuddoo was built and plugins may display more verbose
information such as default options.
--vv 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 by the security policy) 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 otherwise be forbidden. See
sudoers(4) for more information.
CCOOMMMMAANNDD EEXXEECCUUTTIIOONN
When ssuuddoo executes a command, the security policy specifies the execution
environment for the command. Typically, 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).
The following parameters may be specified by security policy:
oo real and effective user ID
oo real and effective group ID
oo supplementary group IDs
oo the environment list
oo current working directory
oo file creation mode mask (umask)
oo SELinux role and type
oo Solaris project
oo Solaris privileges
oo BSD login class
oo scheduling priority (aka nice value)
PPrroocceessss mmooddeell
When ssuuddoo runs a command, it calls fork(2), sets up the execution
environment as described above, and calls the execve system call in the
child process. The main ssuuddoo process waits until the command has
completed, then passes the command's exit status to the security policy's
close function and exits. If an I/O logging plugin is configured or if
the security policy explicitly requests it, a new pseudo-terminal
(``pty'') is created and a second ssuuddoo process is used to relay job
control signals between the user's existing pty and the new pty the
command is being run in. This extra process makes it possible to, for
example, suspend and resume the command. Without it, the command would
be in what POSIX terms an ``orphaned process group'' and it would not
receive any job control signals. As a special case, if the policy plugin
does not define a close function and no pty is required, ssuuddoo will
execute the command directly instead of calling fork(2) first.
SSiiggnnaall hhaannddlliinngg
Because the command is run as a child of the ssuuddoo process, ssuuddoo will
relay signals it receives to the command. Unless the command is being
run in a new pty, the SIGHUP, SIGINT and SIGQUIT signals are not relayed
unless they are sent by a user process, not the kernel. Otherwise, the
command would receive SIGINT twice every time the user entered control-C.
Some signals, such as SIGSTOP and SIGKILL, cannot be caught and thus will
not be relayed to the command. As a general rule, SIGTSTP should be used
instead of SIGSTOP when you wish to suspend a command being run by ssuuddoo.
As a special case, ssuuddoo will not relay signals that were sent by the
command it is running. This prevents the command from accidentally
killing itself. On some systems, the reboot(1m) command sends SIGTERM to
all non-system processes other than itself before rebooting the system.
This prevents ssuuddoo from relaying the SIGTERM signal it received back to
reboot(1m), which might then exit before the system was actually rebooted,
leaving it in a half-dead state similar to single user mode. Note,
however, that this check only applies to the command run by ssuuddoo and not
any other processes that the command may create. As a result, running a
script that calls reboot(1m) or shutdown(1m) via ssuuddoo may cause the system
to end up in this undefined state unless the reboot(1m) or shutdown(1m) are
run using the eexxeecc() family of functions instead of ssyysstteemm() (which
interposes a shell between the command and the calling process).
If no I/O logging plugins are loaded and the policy plugin has not
defined a cclloossee() function, set a command timeout or required that the
command be run in a new pty, ssuuddoo may execute the command directly
instead of running it as a child process.
PPlluuggiinnss
Plugins are dynamically loaded based on the contents of the sudo.conf(4)
file. If no sudo.conf(4) 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. See the sudo.conf(4) manual for details of the _/_e_t_c_/_s_u_d_o_._c_o_n_f
file and the sudo_plugin(1m) manual for more information about the ssuuddoo
plugin architecture.
EEXXIITT VVAALLUUEE
Upon successful execution of a program, the exit status from _s_u_d_o 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 stat(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 stat(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 _P_R_E_V_E_N_T_I_N_G _S_H_E_L_L _E_S_C_A_P_E_S section in
sudoers(4).
To prevent the disclosure of potentially sensitive information, ssuuddoo
disables core dumps by default while it is executing (they are re-enabled
for the command that is run). To aid in debugging ssuuddoo crashes, you may
wish to re-enable core dumps by setting ``disable_coredump'' to false in
the sudo.conf(4) file as follows:
Set disable_coredump false
See the sudo.conf(4) manual for more information.
EENNVVIIRROONNMMEENNTT
ssuuddoo utilizes the following environment variables. The security policy
has control over the actual 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 --ss option.
SUDO_ASKPASS Specifies the path to a helper program used to read the
password if no terminal is available or if the --AA 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 name 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 front end 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 shut down 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
su(1), stat(2), login_cap(3), passwd(4), sudo.conf(4), sudoers(4),
sudo_plugin(1m), sudoreplay(1m), visudo(1m)
HHIISSTTOORRYY
See the HISTORY file in the ssuuddoo distribution
(http://www.sudo.ws/sudo/history.html) for a brief history of sudo.
AAUUTTHHOORRSS
Many people have worked on ssuuddoo over the years; this version consists of
code written primarily by:
Todd C. Miller
See the CONTRIBUTORS file in the ssuuddoo distribution
(http://www.sudo.ws/sudo/contributors.html) for an exhaustive list of
people who have contributed to 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 sudoers(4) plugin'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 _E_X_A_M_P_L_E_S 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.
Sudo 1.8.7 March 13, 2013 Sudo 1.8.7
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>