SUDO(1m) MAINTENANCE COMMANDS SUDO(1m)
NNAAMMEE
sudo, sudoedit - execute a command as another user
SSYYNNOOPPSSIISS
ssuuddoo --KK | --LL | --VV | --hh | --kk | --ll | --vv
ssuuddoo [--HHPPSSbb] [--aa _a_u_t_h___t_y_p_e] [--cc _c_l_a_s_s|_-] [--pp _p_r_o_m_p_t]
[--uu _u_s_e_r_n_a_m_e|_#_u_i_d] {--ee file [...] | --ii | --ss | _c_o_m_m_a_n_d}
ssuuddooeeddiitt [--SS] [--aa _a_u_t_h___t_y_p_e] [--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 in the _s_u_d_o_e_r_s
file. The real and effective uid and gid are set to match
those of the target user as specified in the passwd file
and the group vector is initialized based on the group
file (unless the --PP option was specified). If the invok
ing user is root or if the target user is the same as the
invoking user, no password is required. Otherwise, ssuuddoo
requires that users authenticate themselves with a pass
word by default (NOTE: in the default configuration this
is the user's password, not the root password). Once a
user has been authenticated, a timestamp is updated and
the user may then use sudo without a password for a short
period of time (5 minutes unless overridden in _s_u_d_o_e_r_s).
When invoked as ssuuddooeeddiitt, the --ee option (described below),
is implied.
ssuuddoo determines who is an authorized user by consulting
the file _/_e_t_c_/_s_u_d_o_e_r_s. By giving ssuuddoo the --vv flag a user
can update the time stamp without running a _c_o_m_m_a_n_d_. The
password prompt itself will also time out if the user's
password is not entered within 5 minutes (unless overrid
den via _s_u_d_o_e_r_s).
If a user who is not listed in the _s_u_d_o_e_r_s file tries to
run a command via ssuuddoo, mail is sent to the proper author
ities, as defined at configure time or in the _s_u_d_o_e_r_s file
(defaults to root). Note that the mail will not be sent
if an unauthorized user tries to run sudo with the --ll or
--vv flags. 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 vari
able is set, ssuuddoo will use this value to determine who the
actual user is. This can be used by a user to log com
mands through sudo even when a root shell has been
invoked. It also allows the --ee flag to remain useful even
when being run via a sudo-run script or program. Note
however, that the sudoers lookup is still done for root,
not the user specified by SUDO_USER.
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ssuuddoo 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 ssuuddoo will log via _s_y_s_l_o_g(3) but this is changeable
at configure time or via the _s_u_d_o_e_r_s file.
OOPPTTIIOONNSS
ssuuddoo accepts the following command line options:
-H The --HH (_H_O_M_E) option sets the HOME environment vari
able to the homedir of the target user (root by
default) as specified in passwd(4). By default, ssuuddoo
does not modify HOME (see _s_e_t___h_o_m_e and _a_l_w_a_y_s___s_e_t___h_o_m_e
in sudoers(4)).
-K The --KK (sure _k_i_l_l) option is like --kk except that it
removes the user's timestamp entirely. Like --kk, this
option does not require a password.
-L The --LL (_l_i_s_t defaults) option will list out the param
eters that may be set in a _D_e_f_a_u_l_t_s line along with a
short description for each. This option is useful in
conjunction with _g_r_e_p(1).
-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, ssuuddoo 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.
-S The --SS (_s_t_d_i_n) option causes ssuuddoo to read the password
from the standard input instead of the terminal
device.
-V The --VV (_v_e_r_s_i_o_n) option causes ssuuddoo to print the ver
sion number and exit. If the invoking user is already
root the --VV option will print out a list of the
defaults ssuuddoo was compiled with as well as the
machine's local network addresses.
-a 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 /etc/login.conf. The system
administrator may specify a list of sudo-specific
authentication methods by adding an "auth-sudo" entry
in /etc/login.conf. This option is only available on
systems that support BSD authentication where ssuuddoo has
been configured with the --with-bsdauth option.
-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 manipu
late the process.
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-c 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 /etc/login.conf, or a single '-' charac
ter. Specifying a _c_l_a_s_s of - indicates that the com
mand 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 where ssuuddoo has been configured with the
--with-logincap option.
-e The --ee (_e_d_i_t) option indicates that, instead of run
ning a command, the user wishes to edit one or more
files. In lieu of a command, the string "sudoedit" is
used when consulting the _s_u_d_o_e_r_s file. If the user is
authorized by _s_u_d_o_e_r_s 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 VISUAL or EDITOR
environment variables is run to edit the tem
porary files. If neither VISUAL nor EDITOR
are set, the program listed in the _e_d_i_t_o_r
_s_u_d_o_e_r_s variable is used.
3. If they have been modified, the temporary
files are copied back to their original loca
tion and the temporary versions are removed.
If the specified file does not exist, it will be cre
ated. 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.
-h The --hh (_h_e_l_p) option causes ssuuddoo to print a usage mes
sage and exit.
-i 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 in the passwd(4) entry of the user that the
command is being run as. The command name argument
given to the shell begins with a - to tell the shell
to run as a login shell. ssuuddoo attempts to change to
that user's home directory before running the shell.
It also initializes the environment, leaving _T_E_R_M
unchanged, setting _H_O_M_E, _S_H_E_L_L, _U_S_E_R, _L_O_G_N_A_M_E, and
_P_A_T_H, and unsetting all other environment variables.
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Note that because the shell to use is determined
before the _s_u_d_o_e_r_s file is parsed, a _r_u_n_a_s___d_e_f_a_u_l_t
setting in _s_u_d_o_e_r_s will specify the user to run the
shell as but will not affect which shell is actually
run.
-k The --kk (_k_i_l_l) option to ssuuddoo invalidates the user's
timestamp by setting the time on it to the epoch. 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.
-l The --ll (_l_i_s_t) option will list out the allowed (and
forbidden) commands for the user on the current host.
-p 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:
%u expanded to the invoking user's login name
%U expanded to the login name of the user the
command will be run as (defaults to root)
%h expanded to the local hostname without the
domain name
%H expanded to the local hostname including the
domain name (on if the machine's hostname is
fully qualified or the _f_q_d_n sudoers option is
set)
%% two consecutive % characters are collapsed
into a single % character
-s 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 passwd(4).
-u 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. Note that if the
_t_a_r_g_e_t_p_w Defaults option is set (see sudoers(4)) it is
not possible to run commands with a uid not listed in
the password database.
-v If given the --vv (_v_a_l_i_d_a_t_e) option, ssuuddoo will update
the user's timestamp, prompting for the user's pass
word if necessary. 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.
-- The ---- flag indicates that ssuuddoo should stop processing
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command line arguments. It is most useful in conjunc
tion with the --ss flag.
RREETTUURRNN VVAALLUUEESS
Upon successful execution of a program, the return value
from ssuuddoo will simply be the return value of the program
that was executed.
Otherwise, ssuuddoo quits with an exit value of 1 if there is
a configuration/permission problem or if ssuuddoo cannot exe
cute the given command. In the latter case the error
string is printed to stderr. 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 circum
stances. 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.
Variables that control how dynamic loading and binding is
done can be used to subvert the program that ssuuddoo runs.
To combat this the LD_*, _RLD_*, SHLIB_PATH (HP-UX only),
and LIBPATH (AIX only) environment variables are removed
from the environment passed on to all commands executed.
ssuuddoo will also remove the IFS, CDPATH, ENV, BASH_ENV,
KRB_CONF, KRBCONFDIR, KRBTKFILE, KRB5_CONFIG, LOCALDOMAIN,
RES_OPTIONS, HOSTALIASES, NLSPATH, PATH_LOCALE, TERMINFO,
TERMINFO_DIRS and TERMPATH variables as they too can pose
a threat. If the TERMCAP variable is set and is a path
name, it too is ignored. Additionally, if the LC_* or
LANGUAGE variables contain the / or % characters, they are
ignored. Environment variables with a value beginning
with () are also removed as they could be interpreted as
bbaasshh functions. If ssuuddoo has been compiled with SecurID
support, the VAR_ACE, USR_ACE and DLC_ACE variables are
cleared as well. The list of environment variables that
ssuuddoo clears is contained in the output of sudo -V when run
as root.
To prevent command spoofing, ssuuddoo checks "." and "" (both
denoting current directory) last when searching for a com
mand 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.
For security reasons, if your OS supports shared libraries
and does not disable user-defined library search paths for
setuid programs (most do), you should either use a linker
option that disables this behavior or link ssuuddoo
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statically.
ssuuddoo will check the ownership of its timestamp directory
(_/_v_a_r_/_r_u_n_/_s_u_d_o by default) and ignore the directory's con
tents if it is not owned by root and only writable by
root. On systems that allow non-root users to give away
files via _c_h_o_w_n(2), if the timestamp directory is located
in a directory writable by anyone (e.g.: _/_t_m_p), it is pos
sible for a user to create the timestamp directory before
ssuuddoo is run. However, because ssuuddoo checks the ownership
and mode of the directory and its contents, the only dam
age that can be done is to "hide" files by putting them in
the timestamp dir. This is unlikely to happen since once
the timestamp dir is owned by root and inaccessible by any
other user the user placing files there would be unable to
get them back out. To get around this issue you can use a
directory that is not world-writable for the timestamps
(_/_v_a_r_/_a_d_m_/_s_u_d_o for instance) or create _/_v_a_r_/_r_u_n_/_s_u_d_o with
the appropriate owner (root) and permissions (0700) in the
system startup files.
ssuuddoo will not honor timestamps set far in the future.
Timestamps 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
timestamp with a bogus date on systems that allow users to
give away files.
Please note that ssuuddoo will only log the command it explic
itly runs. If a user runs a command such as sudo su or
sudo sh, subsequent commands run from that shell will _n_o_t
be logged, nor will ssuuddoo's access control affect them.
The same is true for commands that offer shell escapes
(including most editors). 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.
EENNVVIIRROONNMMEENNTT
ssuuddoo utilizes the following environment variables:
EDITOR Default editor to use in -e (sudoedit) mode if
VISUAL is not set
HOME In -s or -H mode (or if sudo was configured with
the --enable-shell-sets-home option), set to
homedir of the target user
PATH Set to a sane value if sudo was configured with
the --with-secure-path option
SHELL Used to determine shell to run with -s option
SUDO_PROMPT Used as the default password prompt
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SUDO_COMMAND Set to the command run by sudo
SUDO_USER Set to the login of the user who invoked sudo
SUDO_UID Set to the uid of the user who invoked sudo
SUDO_GID Set to the gid of the user who invoked sudo
SUDO_PS1 If set, PS1 will be set to its value
USER Set to the target user (root unless the -u option
is specified)
VISUAL Default editor to use in -e (sudoedit) mode
FFIILLEESS
/etc/sudoers List of who can run what
/var/run/sudo Directory containing timestamps
EEXXAAMMPPLLEESS
Note: the following examples assume suitable sudoers(4)
entries.
To get a file listing of an unreadable directory:
$ sudo ls /usr/local/protected
To list the home directory of user yazza on a machine
where the file system holding ~yazza is not exported as
root:
$ sudo -u yazza ls ~yazza
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 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), sudoers(4),
passwd(4), visudo(1m)
AAUUTTHHOORRSS
Many people have worked on ssuuddoo over the years; this ver
sion consists of code written primarily by:
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Todd Miller
Chris Jepeway
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 ssuuddoo's _n_o_e_x_e_c functionality.
See the sudoers(4) manual for details.
It is not meaningful to run the cd command directly via
sudo, e.g.
$ sudo cd /usr/local/protected
since when whe command exits the parent process (your
shell) will still be the same. Please see the EXAMPLES
section for more information.
If users have sudo ALL there is nothing to prevent them
from creating their own program that gives them a root
shell regardless of any '!' elements in the user specifi
cation.
Running shell scripts via ssuuddoo can expose the same kernel
bugs that make setuid shell scripts unsafe on some operat
ing 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
Commercial support is available for ssuuddoo, see
http://www.sudo.ws/sudo/support.html for details.
Limited free support is available via the sudo-users mail
ing list, see http://www.sudo.ws/mail
man/listinfo/sudo-users to subscribe or search the
archives.
DDIISSCCLLAAIIMMEERR
SSuuddoo is provided ``AS IS'' and any express or implied war
ranties, including, but not limited to, the implied war
ranties 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
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complete details.
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