SUDO.CONF(4) File Formats Manual SUDO.CONF(4)
NNAAMMEE
ssuuddoo..ccoonnff - configuration for sudo front end
DDEESSCCRRIIPPTTIIOONN
The ssuuddoo..ccoonnff file is used to configure the ssuuddoo front end. It specifies
the security policy and I/O logging plugins, debug flags as well as
plugin-agnostic path names and settings.
The ssuuddoo..ccoonnff file supports the following directives, described in detail
below.
Plugin a security policy or I/O logging plugin
Path a plugin-agnostic path
Set a front end setting, such as _d_i_s_a_b_l_e___c_o_r_e_d_u_m_p or _g_r_o_u_p___s_o_u_r_c_e
Debug debug flags to aid in debugging ssuuddoo, ssuuddoorreeppllaayy, vviissuuddoo, and
the ssuuddooeerrss plugin.
The pound sign (`#') is used to indicate a comment. Both the comment
character and any text after it, up to the end of the line, are ignored.
Long lines can be continued with a backslash (`\') as the last character
on the line. Note that leading white space is removed from the beginning
of lines even when the continuation character is used.
Non-comment lines that don't begin with Plugin, Path, Debug, or Set are
silently ignored.
The ssuuddoo..ccoonnff file is always parsed in the ``C'' locale.
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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. Plugins are dynamically loaded based on the contents of ssuuddoo..ccoonnff.
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 dynamic shared object that contains 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
symbol contained in the plugin. The _p_a_t_h may be fully qualified or
relative. If not fully qualified, it is relative to the directory
specified by the _p_l_u_g_i_n___d_i_r Path setting, which defaults to
_/_u_s_r_/_l_o_c_a_l_/_l_i_b_e_x_e_c_/_s_u_d_o. In other words:
Plugin sudoers_policy sudoers.so
is equivalent to:
Plugin sudoers_policy /usr/local/libexec/sudo/sudoers.so
If the plugin was compiled statically into the ssuuddoo binary instead of
being installed as a dynamic shared object, the _p_a_t_h should be specified
without a leading directory, as it does not actually exist in the file
system. For example:
Plugin sudoers_policy sudoers.so
Starting with ssuuddoo 1.8.5, any additional parameters after the _p_a_t_h are
passed as arguments to the plugin's _o_p_e_n function. For example, to
override the compile-time default sudoers file mode:
Plugin sudoers_policy sudoers.so sudoers_mode=0440
See the sudoers(4) manual for a list of supported arguments.
The same dynamic shared object may contain multiple plugins, each with a
different symbol name. The file must be owned by uid 0 and only writable
by its owner. Because of ambiguities that arise from composite policies,
only a single policy plugin may be specified. This limitation does not
apply to I/O plugins.
If no ssuuddoo..ccoonnff file is present, or if it contains no Plugin lines, the
ssuuddooeerrss plugin will be used as the default security policy and for I/O
logging (if enabled by the policy). This is equivalent to the following:
Plugin sudoers_policy sudoers.so
Plugin sudoers_io sudoers.so
For more information on the ssuuddoo plugin architecture, see the
sudo_plugin(1m) manual.
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A Path line consists of the Path keyword, followed by the name of the
path to set and its value. For example:
Path noexec /usr/local/libexec/sudo/sudo_noexec.so
Path askpass /usr/X11R6/bin/ssh-askpass
If no path name is specified, features relying on the specified setting
will be disabled. Disabling Path settings is only supported in ssuuddoo
version 1.8.16 and higher.
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 eexxeeccll(), eexxeeccllee(), eexxeeccllpp(), eexxeecctt(), eexxeeccvv(),
eexxeeccvvee(), eexxeeccvvPP(), eexxeeccvvpp(), eexxeeccvvppee(), ffeexxeeccvvee(), ppooppeenn(),
ppoossiixx__ssppaawwnn(), ppoossiixx__ssppaawwnnpp(), and ssyysstteemm() 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. The default value is:
_/_u_s_r_/_l_o_c_a_l_/_l_i_b_e_x_e_c_/_s_u_d_o_/_s_u_d_o___n_o_e_x_e_c_._s_o.
plugin_dir
The default directory to use when searching for plugins that
are specified without a fully qualified path name. The default
value is _/_u_s_r_/_l_o_c_a_l_/_l_i_b_e_x_e_c_/_s_u_d_o.
sesh The fully-qualified path to the sseesshh binary. This setting is
only used when ssuuddoo is built with SELinux support. The default
value is _/_u_s_r_/_l_o_c_a_l_/_l_i_b_e_x_e_c_/_s_u_d_o_/_s_e_s_h.
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The ssuuddoo..ccoonnff file also supports the following front end settings:
disable_coredump
Core dumps of ssuuddoo itself are disabled by default to prevent
the disclosure of potentially sensitive information. To aid in
debugging ssuuddoo crashes, you may wish to re-enable core dumps by
setting ``disable_coredump'' to false in ssuuddoo..ccoonnff as follows:
Set disable_coredump false
All modern operating systems place restrictions on core dumps
from setuid processes like ssuuddoo so this option can be enabled
without compromising security. To actually get a ssuuddoo core
file you will likely need to enable core dumps for setuid
processes. On BSD and Linux systems this is accomplished in
the sysctl command. On Solaris, the coreadm command is used to
configure core dump behavior.
This setting is only available in ssuuddoo version 1.8.4 and
higher.
group_source
ssuuddoo passes the invoking user's group list to the policy and
I/O plugins. On most systems, there is an upper limit to the
number of groups that a user may belong to simultaneously
(typically 16 for compatibility with NFS). On systems with the
getconf(1) utility, running:
getconf NGROUPS_MAX
will return the maximum number of groups.
However, it is still possible to be a member of a larger number
of groups--they simply won't be included in the group list
returned by the kernel for the user. Starting with ssuuddoo
version 1.8.7, if the user's kernel group list has the maximum
number of entries, ssuuddoo will consult the group database
directly to determine the group list. This makes it possible
for the security policy to perform matching by group name even
when the user is a member of more than the maximum number of
groups.
The _g_r_o_u_p___s_o_u_r_c_e setting allows the administrator to change
this default behavior. Supported values for _g_r_o_u_p___s_o_u_r_c_e are:
static Use the static group list that the kernel returns.
Retrieving the group list this way is very fast but
it is subject to an upper limit as described above.
It is ``static'' in that it does not reflect changes
to the group database made after the user logs in.
This was the default behavior prior to ssuuddoo 1.8.7.
dynamic Always query the group database directly. It is
``dynamic'' in that changes made to the group
database after the user logs in will be reflected in
the group list. On some systems, querying the group
database for all of a user's groups can be time
consuming when querying a network-based group
database. Most operating systems provide an
efficient method of performing such queries.
Currently, ssuuddoo supports efficient group queries on
AIX, BSD, HP-UX, Linux and Solaris.
adaptive Only query the group database if the static group
list returned by the kernel has the maximum number of
entries. This is the default behavior in ssuuddoo 1.8.7
and higher.
For example, to cause ssuuddoo to only use the kernel's static list
of groups for the user:
Set group_source static
This setting is only available in ssuuddoo version 1.8.7 and
higher.
max_groups
The maximum number of user groups to retrieve from the group
database. Values less than one will be ignored. This setting
is only used when querying the group database directly. It is
intended to be used on systems where it is not possible to
detect when the array to be populated with group entries is not
sufficiently large. By default, ssuuddoo will allocate four times
the system's maximum number of groups (see above) and retry
with double that number if the group database query fails.
However, some systems just return as many entries as will fit
and do not indicate an error when there is a lack of space.
This setting is only available in ssuuddoo version 1.8.7 and
higher.
probe_interfaces
By default, ssuuddoo will probe the system's network interfaces and
pass the IP address of each enabled interface to the policy
plugin. This makes it possible for the plugin to match rules
based on the IP address without having to query DNS. On Linux
systems with a large number of virtual interfaces, this may
take a non-negligible amount of time. If IP-based matching is
not required, network interface probing can be disabled as
follows:
Set probe_interfaces false
This setting is only available in ssuuddoo version 1.8.10 and
higher.
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ssuuddoo versions 1.8.4 and higher support a flexible debugging framework
that can help track down what ssuuddoo is doing internally if there is a
problem.
A Debug line consists of the Debug keyword, followed by the name of the
program (or plugin) to debug (ssuuddoo, vviissuuddoo, ssuuddoorreeppllaayy, ssuuddooeerrss), the
debug file name and a comma-separated list of debug flags. The debug
flag syntax used by ssuuddoo and the ssuuddooeerrss plugin is _s_u_b_s_y_s_t_e_m@_p_r_i_o_r_i_t_y but
a plugin is free to use a different format so long as it does not include
a comma (`,').
For example:
Debug sudo /var/log/sudo_debug all@warn,plugin@info
would log all debugging statements at the _w_a_r_n level and higher in
addition to those at the _i_n_f_o level for the plugin subsystem.
As of ssuuddoo 1.8.12, multiple Debug entries may be specified per program.
Older versions of ssuuddoo only support a single Debug entry per program.
Plugin-specific Debug entries are also supported starting with ssuuddoo
1.8.12 and are matched by either the base name of the plugin that was
loaded (for example sudoers.so) or by the plugin's fully-qualified path
name. Previously, the ssuuddooeerrss plugin shared the same Debug entry as the
ssuuddoo front end and could not be configured separately.
The following priorities are supported, in order of decreasing severity:
_c_r_i_t, _e_r_r, _w_a_r_n, _n_o_t_i_c_e, _d_i_a_g, _i_n_f_o, _t_r_a_c_e and _d_e_b_u_g. Each priority,
when specified, also includes all priorities higher than it. For
example, a priority of _n_o_t_i_c_e would include debug messages logged at
_n_o_t_i_c_e and higher.
The priorities _t_r_a_c_e and _d_e_b_u_g also include function call tracing which
logs when a function is entered and when it returns. For example, the
following trace is for the get_user_groups() function located in
src/sudo.c:
sudo[123] -> get_user_groups @ src/sudo.c:385
sudo[123] <- get_user_groups @ src/sudo.c:429 := groups=10,0,5
When the function is entered, indicated by a right arrow `->', the
program, process ID, function, source file and line number are logged.
When the function returns, indicated by a left arrow `<-', the same
information is logged along with the return value. In this case, the
return value is a string.
The following subsystems are used by the ssuuddoo front-end:
_a_l_l matches every subsystem
_a_r_g_s command line argument processing
_c_o_n_v user conversation
_e_d_i_t sudoedit
_e_v_e_n_t event subsystem
_e_x_e_c command execution
_m_a_i_n ssuuddoo main function
_n_e_t_i_f network interface handling
_p_c_o_m_m communication with the plugin
_p_l_u_g_i_n plugin configuration
_p_t_y pseudo-tty related code
_s_e_l_i_n_u_x SELinux-specific handling
_u_t_i_l utility functions
_u_t_m_p utmp handling
The sudoers(4) plugin includes support for additional subsystems.
FFIILLEESS
_/_e_t_c_/_s_u_d_o_._c_o_n_f ssuuddoo front end configuration
EEXXAAMMPPLLEESS
#
# Default /etc/sudo.conf file
#
# Format:
# Plugin plugin_name plugin_path plugin_options ...
# Path askpass /path/to/askpass
# Path noexec /path/to/sudo_noexec.so
# Debug sudo /var/log/sudo_debug all@warn
# Set disable_coredump true
#
# The plugin_path is relative to /usr/local/libexec/sudo unless
# fully qualified.
# The plugin_name corresponds to a global symbol in the plugin
# that contains the plugin interface structure.
# The plugin_options are optional.
#
# The sudoers plugin is used by default if no Plugin lines are
# present.
Plugin sudoers_policy sudoers.so
Plugin sudoers_io sudoers.so
#
# Sudo askpass:
#
# An askpass helper program may be specified to provide a graphical
# password prompt for "sudo -A" support. Sudo does not ship with
# its own askpass program but can use the OpenSSH askpass.
#
# Use the OpenSSH askpass
#Path askpass /usr/X11R6/bin/ssh-askpass
#
# Use the Gnome OpenSSH askpass
#Path askpass /usr/libexec/openssh/gnome-ssh-askpass
#
# Sudo noexec:
#
# Path to a shared library containing dummy versions of the execv(),
# execve() and fexecve() library functions that just return an error.
# This is used to implement the "noexec" functionality on systems that
# support C<LD_PRELOAD> or its equivalent.
# The compiled-in value is usually sufficient and should only be
# changed if you rename or move the sudo_noexec.so file.
#
#Path noexec /usr/local/libexec/sudo/sudo_noexec.so
#
# Core dumps:
#
# By default, sudo disables core dumps while it is executing
# (they are re-enabled for the command that is run).
# To aid in debugging sudo problems, you may wish to enable core
# dumps by setting "disable_coredump" to false.
#
#Set disable_coredump false
#
# User groups:
#
# Sudo passes the user's group list to the policy plugin.
# If the user is a member of the maximum number of groups (usually 16),
# sudo will query the group database directly to be sure to include
# the full list of groups.
#
# On some systems, this can be expensive so the behavior is configurable.
# The "group_source" setting has three possible values:
# static - use the user's list of groups returned by the kernel.
# dynamic - query the group database to find the list of groups.
# adaptive - if user is in less than the maximum number of groups.
# use the kernel list, else query the group database.
#
#Set group_source static
SSEEEE AALLSSOO
sudoers(4), sudo(1m), sudo_plugin(1m)
HHIISSTTOORRYY
See the HISTORY file in the ssuuddoo distribution
(https://www.sudo.ws/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
(https://www.sudo.ws/contributors.html) for an exhaustive list of people
who have contributed to ssuuddoo.
BBUUGGSS
If you feel you have found a bug in ssuuddoo, please submit a bug report at
https://bugzilla.sudo.ws/
SSUUPPPPOORRTT
Limited free support is available via the sudo-users mailing list, see
https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search
the archives.
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 https://www.sudo.ws/license.html for
complete details.
Sudo 1.8.17 June 15, 2016 Sudo 1.8.17