|SUDO(5)||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.
- a security policy or I/O logging plugin
- a plugin-agnostic path
- a front end setting, such as disable_coredump or group_source
- debug flags to aid in debugging sudo, sudoreplay, visudo, and the sudoers plugin.
#’) 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
Setare silently ignored. The sudo.conf file is always parsed in the “
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
Pluginline consists of the
Pluginkeyword, followed by the symbol_name and the path to the dynamic shared object that contains the plugin. The symbol_name is the name of the
struct io_pluginsymbol contained in the plugin. The path may be fully qualified or relative. If not fully qualified, it is relative to the directory specified by the plugin_dir
Pathsetting, which defaults to /usr/lib/sudo. In other words:
Plugin sudoers_policy sudoers.so
Plugin sudoers_policy /usr/lib/sudo/sudoers.so
Plugin sudoers_policy sudoers.so
Plugin sudoers_policy sudoers.so sudoers_mode=0440
Pluginlines, 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 sudoers_policy sudoers.so Plugin sudoers_io sudoers.so
Pathline consists of the
Pathkeyword, followed by the name of the path to set and its value. For example:
Path noexec /usr/lib/sudo/sudo_noexec.so Path askpass /usr/X11R6/bin/ssh-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
- 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_PRELOADor its equivalent. The default value is: /usr/lib/sudo/sudo_noexec.so.
- The default directory to use when searching for plugins that are specified without a fully qualified path name. The default value is /usr/lib/sudo.
- The fully-qualified path to the sesh binary. This setting is only used when sudo is built with SELinux support. The default value is /usr/lib/sudo/sesh.
Other settings¶The sudo.conf file also supports the following front end settings:
- 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
- sudo 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:
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 sudo version 1.8.7, if the user's kernel group list has the maximum number of entries, sudo 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 group_source setting allows the administrator to change this default behavior. Supported values for group_source are:
- 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 sudo 1.8.7.
- 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, sudo supports efficient group queries on AIX, BSD, HP-UX, Linux and Solaris.
- 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 sudo 1.8.7 and higher.
Set group_source static
- 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, sudo 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 sudo version 1.8.7 and higher.
- By default, sudo 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
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
Debugline consists of the
Debugkeyword, 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
Debugentry per program is supported. The sudo
Debugentry is shared by the sudo front end, sudoedit and the plugins. A future release may add support for per-plugin
Debuglines 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:
- matches every subsystem
- command line argument processing
- user conversation
- event subsystem
- command execution
- sudo main function
- network interface handling
- communication with the plugin
- plugin configuration
- pseudo-tty related code
- SELinux-specific handling
- utility functions
- utmp handling
- sudo front end configuration
# # 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/lib/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/lib/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
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. MillerSee 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.
|January 22, 2014||Sudo 1.8.10p3|