SUDO(5) BSD File Formats Manual SUDO(5)

NAME

sudo.conf — configuration for sudo front end

DESCRIPTION

The sudo.conf file is used to configure the sudo front end. It specifies the security policy and I/O logging plugins, debug flags as well as plugin-agnostic path names and settings.

The sudo.conf 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 disable_coredump or group_source

Debug

debug flags to aid in debugging sudo, sudoreplay, visudo, and the sudoers 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.

Non-comment lines that don’t begin with Plugin, Path, Debug, or Set are silently ignored.

The sudo.conf file is always parsed in the ‘‘C’’ locale.

Plugin configuration
sudo 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 sudo front end. Plugins are dynamically loaded based on the contents of sudo.conf.

A Plugin line consists of the Plugin keyword, followed by the symbol_name and the path to the shared object containing the plugin. The symbol_name is the name of the struct policy_plugin or struct io_plugin in the plugin shared object. The path may be fully qualified or relative. If not fully qualified, it is relative to the /usr/libexec directory. In other words:

Plugin sudoers_policy sudoers.so

is equivalent to:

Plugin sudoers_policy /usr/libexec/sudoers.so

Any additional parameters after the path are passed as arguments to the plugin’s open function. For example, to override the compile-time default sudoers file mode:

Plugin sudoers_policy sudoers.so sudoers_mode=0440

If no sudo.conf file is present, or if it contains no Plugin lines, the sudoers 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 policy_plugin sudoers.so
Plugin io_plugin sudoers.so

For more information on the sudo plugin architecture, see the sudo_plugin(8) manual.

Path settings
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/libexec/sudo_noexec.so
Path askpass /usr/X11R6/bin/ssh-askpass

The following plugin-agnostic paths may be set in the /etc/sudo.conf 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 sudo is executed from a graphical (as opposed to text-based) application. The program specified by askpass should display the argument passed to it as the prompt and write the user’s password to the standard output. The value of askpass may be overridden by the SUDO_ASKPASS environment variable.

noexec

The fully-qualified 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 LD_PRELOAD or its equivalent. The default value is: /usr/libexec/sudo_noexec.so.

Other settings
The sudo.conf file also supports the following front end settings:

disable_coredump

Core dumps of sudo itself are disabled by default. To aid in debugging sudo crashes, you may wish to re-enable core dumps by setting ‘‘disable_coredump’’ to false in sudo.conf as follows:

Set disable_coredump false

Note that most operating systems disable core dumps from setuid programs, including sudo. To actually get a sudo core file you will likely need to enable core dumps for setuid processes. On BSD and Linux systems this is accomplished via the sysctl command. On Solaris, the coreadm command is used to configure core dump behavior.

This setting is only available in sudo version 1.8.4 and higher.

Debug flags
sudo versions 1.8.4 and higher support a flexible debugging framework that can help track down what sudo 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 (sudo, visudo, sudoreplay, sudoers), the debug file name and a comma-separated list of debug flags. The debug flag syntax used by sudo and the sudoers plugin is subsystem@priority 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 warn level and higher in addition to those at the info level for the plugin subsystem.

Currently, only one Debug entry per program is supported. The sudo Debug entry is shared by the sudo front end, sudoedit and the plugins. A future release may add support for per-plugin Debug lines and/or support for multiple debugging files for a single program.

The priorities used by the sudo front end, in order of decreasing severity, are: crit, err, warn, notice, diag, info, trace and debug. Each priority, when specified, also includes all priorities higher than it. For example, a priority of notice would include debug messages logged at notice and higher.

The following subsystems are used by the sudo front-end:

all

matches every subsystem

args

command line argument processing

conv

user conversation

edit

sudoedit

exec

command execution

main

sudo main function

netif

network interface handling

pcomm

communication with the plugin

plugin

plugin configuration

pty

pseudo-tty related code

selinux

SELinux-specific handling

util

utility functions

utmp

utmp handling

FILES
/etc/sudo.conf

sudo front end configuration

EXAMPLES

#
# 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/libexec 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 policy_plugin sudoers.so
Plugin io_plugin 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/libexec/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

SEE ALSO

sudoers(5), sudo(8), sudo_plugin(8)

HISTORY

See the HISTORY file in the sudo distribution (http://www.sudo.ws/sudo/history.html) for a brief history of sudo.

AUTHORS

Many people have worked on sudo over the years; this version consists of code written primarily by:

Todd C. Miller

See the CONTRIBUTORS file in the sudo distribution (http://www.sudo.ws/sudo/contributors.html) for an exhaustive list of people who have contributed to sudo.

BUGS

If you feel you have found a bug in sudo, please submit a bug report at http://www.sudo.ws/sudo/bugs/

SUPPORT

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.

DISCLAIMER

sudo 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 sudo or http://www.sudo.ws/sudo/license.html for complete details.

Sudo 1.8.6p7 February 5, 2013 Sudo 1.8.6p7