path: root/doc/sudoers.ldap.mdoc.in

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.Dd October 29, 2020
.Dt SUDOERS.LDAP @mansectform@
.Os Sudo @PACKAGE_VERSION@
.Sh NAME
.Nm sudoers.ldap
.Nd sudo LDAP configuration
.Sh DESCRIPTION
In addition to the standard
.Em sudoers
file,
.Nm sudo
may be configured
via LDAP.
This can be especially useful for synchronizing
.Em sudoers
in a large, distributed environment.
.Pp
Using LDAP for
.Em sudoers
has several benefits:
.Bl -bullet -width 1n
.It
.Nm sudo
no longer needs to read
.Em sudoers
in its entirety.
When LDAP is used, there are only two or three LDAP queries per invocation.
This makes it especially fast and particularly usable in LDAP environments.
.It
.Nm sudo
no longer exits if there is a typo in
.Em sudoers .
It is not possible to load LDAP data into the server that does
not conform to the sudoers schema, so proper syntax is guaranteed.
It is still possible to have typos in a user or host name, but
this will not prevent
.Nm sudo
from running.
.It
It is possible to specify per-entry options that override the global
default options.
.Pa @sysconfdir@/sudoers
only supports default options and limited options associated with
user/host/commands/aliases.
The syntax is complicated and can be difficult for users to understand.
Placing the options directly in the entry is more natural.
.It
The
.Nm visudo
program is no longer needed.
.Nm visudo
provides locking and syntax checking of the
.Pa @sysconfdir@/sudoers
file.
Since LDAP updates are atomic, locking is no longer necessary.
Because syntax is checked when the data is inserted into LDAP, there
is no need for a specialized tool to check syntax.
.El
.Ss SUDOers LDAP container
The
.Em sudoers
configuration is contained in the
.Li ou=SUDOers
LDAP container.
.Pp
Sudo first looks for the
.Li cn=defaults
entry in the SUDOers container.
If found, the multi-valued
.Li sudoOption
attribute is parsed in the same manner as a global
.Li Defaults
line in
.Pa @sysconfdir@/sudoers .
In the following example, the
.Ev SSH_AUTH_SOCK
variable will be preserved in the environment for all users.
.Bd -literal -offset 4n
dn: cn=defaults,ou=SUDOers,dc=my-domain,dc=com
objectClass: top
objectClass: sudoRole
cn: defaults
description: Default sudoOption's go here
sudoOption: env_keep+=SSH_AUTH_SOCK
.Ed
.Pp
The equivalent of a sudoer in LDAP is a
.Li sudoRole .
It consists of the following attributes:
.Bl -tag -width 4n
.It Sy sudoUser
A user name, user-ID (prefixed with
.Ql # ) ,
Unix group name or ID (prefixed with
.Ql %
or
.Ql %#
respectively), user netgroup (prefixed with
.Ql + ) ,
or non-Unix group name or ID (prefixed with
.Ql %:
or
.Ql %:#
respectively).
User netgroups are matched using the user and domain members only;
the host member is not used when matching.
Non-Unix group support is only available when an appropriate
.Em group_plugin
is defined in the global
.Em defaults
.Li sudoRole
object.
.It Sy sudoHost
A host name, IP address, IP network, or host netgroup (prefixed with a
.Ql + ) .
The special value
.Li ALL
will match any host.
Host netgroups are matched using the host (both qualified and unqualified)
and domain members only; the user member is not used when matching.
If a
.Li sudoHost
entry is preceded by an exclamation point,
.Ql \&! ,
and the entry matches, the
.Li sudoRole
in which it resides will be ignored.
Negated
.Li sudoHost
entries are only supported by version 1.8.18 or higher.
.It Sy sudoCommand
A fully-qualified Unix command name with optional command line arguments,
potentially including globbing characters (aka wild cards).
If a command name is preceded by an exclamation point,
.Ql \&! ,
the user will be prohibited from running that command.
.Pp
The built-in command
.Dq Li sudoedit
is used to permit a user to run
.Nm sudo
with the
.Fl e
option (or as
.Nm sudoedit ) .
It may take command line arguments just as a normal command does.
Note that
.Dq Li sudoedit
is a command built into
.Nm sudo
itself and must be specified in without a leading path.
.Pp
The special value
.Li ALL
will match any command.
.Pp
If a command name is prefixed with a SHA-2 digest, it will
only be allowed if the digest matches.
This may be useful in situations where the user invoking
.Nm sudo
has write access to the command or its parent directory.
The following digest formats are supported: sha224, sha256, sha384 and sha512.
The digest name must be followed by a colon
.Pq Ql :\&
and then the actual digest, in either hex or base64 format.
For example, given the following value for sudoCommand:
.Bd -literal -offset 4n
sha224:0GomF8mNN3wlDt1HD9XldjJ3SNgpFdbjO1+NsQ /bin/ls
.Ed
.Pp
The user may only run
.Pa /bin/ls
if its sha224 digest matches the specified value.
Command digests are only supported by version 1.8.7 or higher.
.It Sy sudoOption
Identical in function to the global options described above, but
specific to the
.Li sudoRole
in which it resides.
.It Sy sudoRunAsUser
A user name or uid (prefixed with
.Ql # )
that commands may be run as or a Unix group (prefixed with a
.Ql % )
or user netgroup (prefixed with a
.Ql + )
that contains a list of users that commands may be run as.
The special value
.Li ALL
will match any user.
If a
.Li sudoRunAsUser
entry is preceded by an exclamation point,
.Ql \&! ,
and the entry matches, the
.Li sudoRole
in which it resides will be ignored.
If
.Li sudoRunAsUser
is specified but empty, it will match the invoking user.
If neither
.Li sudoRunAsUser
nor
.Li sudoRunAsGroup
are present, the value of the
.Em runas_default
.Li sudoOption
is used (defaults to
.Li @runas_default@ ) .
.Pp
The
.Li sudoRunAsUser
attribute is only available in
.Nm sudo
versions
1.7.0 and higher.
Older versions of
.Nm sudo
use the
.Li sudoRunAs
attribute instead.
Negated
.Li sudoRunAsUser
entries are only supported by version 1.8.26 or higher.
.It Sy sudoRunAsGroup
A Unix group or gid (prefixed with
.Ql # )
that commands may be run as.
The special value
.Li ALL
will match any group.
If a
.Li sudoRunAsGroup
entry is preceded by an exclamation point,
.Ql \&! ,
and the entry matches, the
.Li sudoRole
in which it resides will be ignored.
.Pp
The
.Li sudoRunAsGroup
attribute is only available in
.Nm sudo
versions
1.7.0 and higher.
Negated
.Li sudoRunAsGroup
entries are only supported by version 1.8.26 or higher.
.It Sy sudoNotBefore
A timestamp in the form
.Li yyyymmddHHMMSSZ
that can be used to provide a start date/time for when the
.Li sudoRole
will be valid.
If multiple
.Li sudoNotBefore
entries are present, the earliest is used.
Note that timestamps must be in Coordinated Universal Time (UTC),
not the local timezone.
The minute and seconds portions are optional, but some LDAP servers
require that they be present (contrary to the RFC).
.Pp
The
.Li sudoNotBefore
attribute is only available in
.Nm sudo
versions 1.7.5 and higher and must be explicitly enabled via the
.Sy SUDOERS_TIMED
option in
.Pa @ldap_conf@ .
.It Sy sudoNotAfter
A timestamp in the form
.Li yyyymmddHHMMSSZ
that indicates an expiration date/time, after which the
.Li sudoRole
will no longer be valid.
If multiple
.Li sudoNotAfter
entries are present, the last one is used.
Note that timestamps must be in Coordinated Universal Time (UTC),
not the local timezone.
The minute and seconds portions are optional, but some LDAP servers
require that they be present (contrary to the RFC).
.Pp
The
.Li sudoNotAfter
attribute is only available in
.Nm sudo
versions
1.7.5 and higher and must be explicitly enabled via the
.Sy SUDOERS_TIMED
option in
.Pa @ldap_conf@ .
.It Sy sudoOrder
The
.Li sudoRole
entries retrieved from the LDAP directory have no inherent order.
The
.Li sudoOrder
attribute is an integer (or floating point value for LDAP servers
that support it) that is used to sort the matching entries.
This allows LDAP-based sudoers entries to more closely mimic the behavior
of the sudoers file, where the order of the entries influences the result.
If multiple entries match, the entry with the highest
.Li sudoOrder
attribute is chosen.
This corresponds to the
.Dq last match
behavior of the sudoers file.
If the
.Li sudoOrder
attribute is not present, a value of 0 is assumed.
.Pp
The
.Li sudoOrder
attribute is only available in
.Nm sudo
versions 1.7.5 and higher.
.El
.Pp
Each attribute listed above should contain a single value, but there
may be multiple instances of each attribute type.
A
.Li sudoRole
must contain at least one
.Li sudoUser ,
.Li sudoHost
and
.Li sudoCommand .
.Pp
The following example allows users in group wheel to run any command
on any host via
.Nm sudo :
.Bd -literal -offset 4n
dn: cn=%wheel,ou=SUDOers,dc=my-domain,dc=com
objectClass: top
objectClass: sudoRole
cn: %wheel
sudoUser: %wheel
sudoHost: ALL
sudoCommand: ALL
.Ed
.Ss Anatomy of LDAP sudoers lookup
When looking up a sudoer using LDAP there are only two or three
LDAP queries per invocation.
The first query is to parse the global options.
The second is to match against the user's name and the groups that
the user belongs to.
(The special
.Li ALL
tag is matched in this query too.)
If no match is returned for the user's name and groups, a third
query returns all entries containing user netgroups and other
non-Unix groups and checks to see if the user belongs to any of them.
.Pp
If timed entries are enabled with the
.Sy SUDOERS_TIMED
configuration directive, the LDAP queries include a sub-filter that
limits retrieval to entries that satisfy the time constraints, if any.
.Pp
If the
.Sy NETGROUP_BASE
configuration directive is present (see
.Sx Configuring ldap.conf
below), queries are performed to determine
the list of netgroups the user belongs to before the sudoers query.
This makes it possible to include netgroups in the sudoers query
string in the same manner as Unix groups.
The third query mentioned above is not performed unless a group provider
plugin is also configured.
The actual LDAP queries performed by
.Nm sudo
are as follows:
.Bl -enum
.It
Match all
.Li nisNetgroup
records with a
.Li nisNetgroupTriple
containing the user, host and NIS domain.
The query will match
.Li nisNetgroupTriple
entries with either the short or long form of the host name or
no host name specified in the tuple.
If the NIS domain is set, the query will match only match entries
that include the domain or for which there is no domain present.
If the NIS domain is
.Em not
set, a wildcard is used to match any domain name but be aware that the
NIS schema used by some LDAP servers may not support wild cards for
.Li nisNetgroupTriple .
.It
Repeated queries are performed to find any nested
.Li nisNetgroup
records with a
.Li memberNisNetgroup
entry that refers to an already-matched record.
.El
.Pp
For sites with a large number of netgroups, using
.Sy NETGROUP_BASE
can significantly speed up
.Nm sudo Ns 's
execution time.
.Ss Differences between LDAP and non-LDAP sudoers
One of the major differences between LDAP and file-based
.Em sudoers
is that in LDAP,
.Nm sudo Ns -specific
Aliases are not supported.
.Pp
For the most part, there is little need for
.Nm sudo Ns -specific
Aliases.
Unix groups, non-Unix groups (via the
.Em group_plugin )
or user netgroups can be used in place of User_Aliases and Runas_Aliases.
Host netgroups can be used in place of Host_Aliases.
Since groups and netgroups can also be stored in LDAP there is no real need for
.Nm sudo Ns -specific
aliases.
.Pp
There are also some subtle differences in the way sudoers is handled
once in LDAP.
Probably the biggest is that according to the RFC, LDAP ordering
is arbitrary and you cannot expect that Attributes and Entries are
returned in any specific order.
.Pp
The order in which different entries are applied can be controlled
using the
.Li sudoOrder
attribute, but there is no way to guarantee the order of attributes
within a specific entry.
If there are conflicting command rules in an entry, the negative
takes precedence.
This is called paranoid behavior (not necessarily the most specific
match).
.Pp
Here is an example:
.Bd -literal -offset 4n
# /etc/sudoers:
# Allow all commands except shell
johnny  ALL=(root) ALL,!/bin/sh
# Always allows all commands because ALL is matched last
puddles ALL=(root) !/bin/sh,ALL

# LDAP equivalent of johnny
# Allows all commands except shell
dn: cn=role1,ou=Sudoers,dc=my-domain,dc=com
objectClass: sudoRole
objectClass: top
cn: role1
sudoUser: johnny
sudoHost: ALL
sudoCommand: ALL
sudoCommand: !/bin/sh

# LDAP equivalent of puddles
# Notice that even though ALL comes last, it still behaves like
# role1 since the LDAP code assumes the more paranoid configuration
dn: cn=role2,ou=Sudoers,dc=my-domain,dc=com
objectClass: sudoRole
objectClass: top
cn: role2
sudoUser: puddles
sudoHost: ALL
sudoCommand: !/bin/sh
sudoCommand: ALL
.Ed
.Pp
Another difference is that it is not possible to use negation in a
sudoUser, sudoRunAsUser or sudoRunAsGroup attribute.
For example, the following attributes do not behave the way one might expect.
.Bd -literal -offset 4n
# does not match all but joe
# rather, does not match anyone
sudoUser: !joe

# does not match all but joe
# rather, matches everyone including Joe
sudoUser: ALL
sudoUser: !joe
.Ed
.Ss Converting between file-based and LDAP sudoers
The
.Xr cvtsudoers 1
utility can be used to convert between file-based and LDAP
.Em sudoers .
However, there are features in the file-based sudoers that have
no equivalent in LDAP-based sudoers (and vice versa).
These cannot be converted automatically.
.Pp
For example, a Cmnd_Alias in a
.Em sudoers
file may be converted to a
.Li sudoRole
that contains multiple commands.
Multiple users and/or groups may be assigned to the
.Li sudoRole .
.Pp
Also, host, user, runas and command-based
.Li Defaults
entries are not supported.
However, a
.Li sudoRole
may contain one or more
.Li sudoOption
attributes which can often serve the same purpose.
.Pp
Consider the following
.Em sudoers
lines:
.Bd -literal -offset 4n
Cmnd_Alias PAGERS = /usr/bin/more, /usr/bin/pg, /usr/bin/less
Defaults!PAGERS noexec
alice, bob ALL = ALL
.Ed
.Pp
In this example, alice and bob are allowed to run all commands, but
the commands listed in PAGERS will have the noexec flag set,
preventing shell escapes.
.Pp
When converting this to LDAP, two sudoRole objects can be used:
.Bd -literal -offset 4n
dn: cn=PAGERS,ou=SUDOers,dc=my-domain,dc=com
objectClass: top
objectClass: sudoRole
cn: PAGERS
sudoUser: alice
sudoUser: bob
sudoHost: ALL
sudoCommand: /usr/bin/more
sudoCommand: /usr/bin/pg
sudoCommand: /usr/bin/less
sudoOption: noexec
sudoOrder: 900

dn: cn=ADMINS,ou=SUDOers,dc=my-domain,dc=com
objectClass: top
objectClass: sudoRole
cn: ADMINS
sudoUser: alice
sudoUser: bob
sudoHost: ALL
sudoCommand: ALL
sudoOrder: 100
.Ed
.Pp
In the LDAP version, the sudoOrder attribute is used to guarantee
that the PAGERS sudoRole with
.Em noexec
has precedence.
Unlike the
.Em sudoers
version, the LDAP version requires that all users for whom the restriction
should apply be assigned to the PAGERS sudoRole.
Using a Unix group or netgroup in PAGERS rather than listing each
user would make this easier to maintain.
.Pp
Per-user
.Li Defaults
entries can be emulated by using one or more sudoOption attributes
in a sudoRole.
Consider the following
.Em sudoers
lines:
.Bd -literal -offset 4n
User_Alias ADMINS = john, sally
Defaults:ADMINS !authenticate
ADMINS ALL = (ALL:ALL) ALL
.Ed
.Pp
In this example, john and sally are allowed to run any command
as any user or group.
.Pp
When converting this to LDAP, we can use a Unix group instead
of the User_Alias.
.Bd -literal -offset 4n
dn: cn=admins,ou=SUDOers,dc=my-domain,dc=com
objectClass: top
objectClass: sudoRole
cn: admins
sudoUser: %admin
sudoHost: ALL
sudoRunAsUser: ALL
sudoRunAsGroup: ALL
sudoCommand: ALL
sudoOption: !authenticate
.Ed
.Pp
This assumes that users john and sally are members of the
.Dq admins
Unix group.
.Ss Sudoers schema
In order to use
.Nm sudo Ns 's
LDAP support, the
.Nm sudo
schema must be
installed on your LDAP server.
In addition, be sure to index the
.Li sudoUser
attribute.
.Pp
The
.Nm sudo
distribution includes versions of the
.Nm sudoers
schema for multiple LDAP servers:
.Bl -tag -width 4n
.It Pa schema.OpenLDAP
OpenLDAP slapd and
.Ox
ldapd
.It Pa schema.olcSudo
OpenLDAP slapd 2.3 and higher when on-line configuration is enabled
.It Pa schema.iPlanet
Netscape-derived servers such as the iPlanet, Oracle,
and 389 Directory Servers
.It Pa schema.ActiveDirectory
Microsoft Active Directory
.El
.Pp
The schema in OpenLDAP format is also included in the
.Sx EXAMPLES
section.
.Ss Configuring ldap.conf
Sudo reads the
.Pa @ldap_conf@
file for LDAP-specific configuration.
Typically, this file is shared between different LDAP-aware clients.
As such, most of the settings are not
.Nm sudo Ns -specific.
Note that
.Nm sudo
parses
.Pa @ldap_conf@
itself and may support options that differ from those described in the
system's
.Xr ldap.conf @mansectform@
manual.
The path to
.Pa ldap.conf
may be overridden via the
.Em ldap_conf
plugin argument in
.Xr sudo.conf @mansectform@ .
.Pp
Also note that on systems using the OpenLDAP libraries, default
values specified in
.Pa /etc/openldap/ldap.conf
or the user's
.Pa .ldaprc
files are not used.
.Pp
.Nm sudo
supports a variety of LDAP library implementations, including
OpenLDAP, Netscape-derived (also used by Solaris and HP-UX), and
IBM LDAP (aka Tivoli).
Some options are specific to certain LDAP implementations or have
implementation-specific behavior.
These differences are noted below where applicable.
.Pp
Only those options explicitly listed in
.Pa @ldap_conf@
as being supported by
.Nm sudo
are honored.
Configuration options are listed below in upper case but are parsed
in a case-independent manner.
.Pp
Lines beginning with a pound sign
.Pq Ql #
are ignored.
Leading white space is removed from the beginning of lines.
.Bl -tag -width 4n
.It Sy BIND_TIMELIMIT Ar seconds
The
.Sy BIND_TIMELIMIT
parameter specifies the amount of time, in seconds, to wait while trying
to connect to an LDAP server.
If multiple
.Sy URI Ns s
or
.Sy HOST Ns s
are specified, this is the amount of time to wait before trying
the next one in the list.
.It Sy BINDDN Ar DN
The
.Sy BINDDN
parameter specifies the identity, in the form of a Distinguished Name (DN),
to use when performing LDAP operations.
If not specified, LDAP operations are performed with an anonymous identity.
By default, most LDAP servers will allow anonymous access.
.It Sy BINDPW Ar secret
The
.Sy BINDPW
parameter specifies the password to use when performing LDAP operations.
This is typically used in conjunction with the
.Sy BINDDN
parameter.
The
.Ar secret
may be a plain text password or a base64-encoded string with a
.Dq base64:
prefix.
For example:
.Bd -literal -offset 4n
BINDPW base64:dGVzdA==
.Ed
.Pp
If a plain text password is used, it should be a simple string without quotes.
Plain text passwords may not include the comment character
.Pq Ql #
and the escaping of special characters with a backslash
.Pq Ql \e
is not supported.
.It Sy DEREF Ar never/searching/finding/always
How alias dereferencing is to be performed when searching.
See the
.Xr ldap.conf @mansectform@
manual for a full description of this option.
.It Sy HOST Ar name[:port] ...
If no
.Sy URI
is specified (see below), the
.Sy HOST
parameter specifies a white space-delimited list of LDAP servers to connect to.
Each host may include an optional
.Em port
separated by a colon
.Pq Ql :\& .
The
.Sy HOST
parameter is deprecated in favor of the
.Sy URI
specification and is included for backward compatibility only.
.It Sy KRB5_CCNAME Ar file name
The path to the Kerberos 5 credential cache to use when authenticating
with the remote server.
.Pp
This option is only relevant when using SASL authentication (see below).
.It Sy LDAP_VERSION Ar number
The version of the LDAP protocol to use when connecting to the server.
The default value is protocol version 3.
.It Sy NETGROUP_BASE Ar base
The base DN to use when performing LDAP netgroup queries.
Typically this is of the form
.Li ou=netgroup,dc=my-domain,dc=com
for the domain
.Li my-domain.com .
Multiple
.Sy NETGROUP_BASE
lines may be specified, in which case they are queried in the order specified.
.Pp
This option can be used to query a user's netgroups directly via LDAP
which is usually faster than fetching every
.Li sudoRole
object containing a
.Li sudoUser
that begins with a
.Ql +
prefix.
The NIS schema used by some LDAP servers need a modification to
support querying the
.Li nisNetgroup
object by its
.Li nisNetgroupTriple
member.
OpenLDAP's
.Sy slapd
requires the following change to the
.Li nisNetgroupTriple
attribute:
.Bd -literal -offset 4n
attributetype ( 1.3.6.1.1.1.1.14 NAME 'nisNetgroupTriple'
    DESC 'Netgroup triple'
    EQUALITY caseIgnoreIA5Match
    SUBSTR caseIgnoreIA5SubstringsMatch
    SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )
.Ed
.It Sy NETGROUP_SEARCH_FILTER Ar ldap_filter
An LDAP filter which is used to restrict the set of records returned
when performing an LDAP netgroup query.
Typically, this is of the
form
.Li attribute=value
or
.Li (&(attribute=value)(attribute2=value2)) .
The default search filter is:
.Li objectClass=nisNetgroup .
If
.Ar ldap_filter
is omitted, no search filter will be used.
.Pp
This option is only used when querying netgroups directly via LDAP.
.It Sy NETWORK_TIMEOUT Ar seconds
An alias for
.Sy BIND_TIMELIMIT
provided for OpenLDAP compatibility.
.It Sy PORT Ar port_number
If no
.Sy URI
is specified, the
.Sy PORT
parameter specifies the default port to connect to on the LDAP server if a
.Sy HOST
parameter does not specify the port itself.
If no
.Sy PORT
parameter is used, the default is port 389 for LDAP and port 636 for LDAP
over TLS (SSL).
The
.Sy PORT
parameter is deprecated in favor of the
.Sy URI
specification and is included for backward compatibility only.
.It Sy ROOTBINDDN Ar DN
The
.Sy ROOTBINDDN
parameter specifies the identity, in the form of a Distinguished Name (DN),
to use when performing privileged LDAP operations, such as
.Em sudoers
queries.
The password corresponding to the identity should be stored in the
or the path specified by the
.Em ldap_secret
plugin argument in
.Xr sudo.conf @mansectform@ ,
which defaults to
.Pa @ldap_secret@ .
If no
.Sy ROOTBINDDN
is specified, the
.Sy BINDDN
identity is used (if any).
.It Sy ROOTUSE_SASL Ar on/true/yes/off/false/no
Enable
.Sy ROOTUSE_SASL
to enable SASL authentication when connecting
to an LDAP server from a privileged process, such as
.Nm sudo .
.It Sy SASL_AUTH_ID Ar identity
The SASL user name to use when connecting to the LDAP server.
By default,
.Nm sudo
will use an anonymous connection.
.Pp
This option is only relevant when using SASL authentication.
.It Sy SASL_MECH Ar mechanisms
A white space-delimited list of SASL authentication mechanisms to use.
By default,
.Nm sudo
will use
.Dv GSSAPI
authentication.
.It Sy SASL_SECPROPS Ar none/properties
SASL security properties or
.Em none
for no properties.
See the SASL programmer's manual for details.
.Pp
This option is only relevant when using SASL authentication.
.It Sy SSL Ar on/true/yes/off/false/no
If the
.Sy SSL
parameter is set to
.Li on ,
.Li true
.Li or
.Li yes ,
TLS (SSL) encryption is always used when communicating with the LDAP server.
Typically, this involves connecting to the server on port 636 (ldaps).
.It Sy SSL Ar start_tls
If the
.Sy SSL
parameter is set to
.Li start_tls ,
the LDAP server connection is initiated normally and TLS encryption is
begun before the bind credentials are sent.
This has the advantage of not requiring a dedicated port for encrypted
communications.
This parameter is only supported by LDAP servers that honor the
.Em start_tls
extension, such as the OpenLDAP and IBM Tivoli Directory servers.
.It Sy SUDOERS_BASE Ar base
The base DN to use when performing
.Nm sudo
LDAP queries.
Typically this is of the form
.Li ou=SUDOers,dc=my-domain,dc=com
for the domain
.Li my-domain.com .
Multiple
.Sy SUDOERS_BASE
lines may be specified, in which case they are queried in the order specified.
.It Sy SUDOERS_DEBUG Ar debug_level
This sets the debug level for
.Nm sudo
LDAP queries.
Debugging information is printed to the standard error.
A value of 1 results in a moderate amount of debugging information.
A value of 2 shows the results of the matches themselves.
This parameter should not be set in a production environment as the
extra information is likely to confuse users.
.Pp
The
.Sy SUDOERS_DEBUG
parameter is deprecated and will be removed in a future release.
The same information is now logged via the
.Nm sudo
debugging framework using the
.Dq ldap
subsystem at priorities
.Em diag
and
.Em info
for
.Em debug_level
values 1 and 2 respectively.
See the
.Xr sudo.conf @mansectform@
manual for details on how to configure
.Nm sudo
debugging.
.It Sy SUDOERS_SEARCH_FILTER Ar ldap_filter
An LDAP filter which is used to restrict the set of records returned
when performing a
.Nm sudo
LDAP query.
Typically, this is of the
form
.Li attribute=value
or
.Li (&(attribute=value)(attribute2=value2)) .
The default search filter is:
.Li objectClass=sudoRole .
If
.Ar ldap_filter
is omitted, no search filter will be used.
.It Sy SUDOERS_TIMED Ar on/true/yes/off/false/no
Whether or not to evaluate the
.Li sudoNotBefore
and
.Li sudoNotAfter
attributes that implement time-dependent sudoers entries.
.It Sy TIMELIMIT Ar seconds
The
.Sy TIMELIMIT
parameter specifies the amount of time, in seconds, to wait for a
response to an LDAP query.
.It Sy TIMEOUT Ar seconds
The
.Sy TIMEOUT
parameter specifies the amount of time, in seconds, to wait for a
response from the various LDAP APIs.
.It Sy TLS_CACERT Ar file name
An alias for
.Sy TLS_CACERTFILE
for OpenLDAP compatibility.
.It Sy TLS_CACERTFILE Ar file name
The path to a certificate authority bundle which contains the certificates
for all the Certificate Authorities the client knows to be valid, e.g.,
.Pa /etc/ssl/ca-bundle.pem .
.Pp
This option is only supported by the OpenLDAP libraries.
Netscape-derived LDAP libraries use the same certificate
database for CA and client certificates (see
.Sy TLS_CERT ) .
.It Sy TLS_CACERTDIR Ar directory
Similar to
.Sy TLS_CACERTFILE
but instead of a file, it is a directory containing individual
Certificate Authority certificates, e.g.,
.Pa /etc/ssl/certs .
The directory specified by
.Sy TLS_CACERTDIR
is checked after
.Sy TLS_CACERTFILE .
.Pp
This option is only supported by the OpenLDAP libraries.
.It Sy TLS_CERT Ar file name
The path to a file containing the client certificate which can
be used to authenticate the client to the LDAP server.
The certificate type depends on the LDAP libraries used.
.Bl -tag -width 4n
.It OpenLDAP:
.Li tls_cert /etc/ssl/client_cert.pem
.It Netscape-derived:
.Li tls_cert /var/ldap/cert7.db
.It IBM LDAP:
Unused, the key database specified by
.Sy TLS_KEY
contains both keys and certificates.
.El
.Pp
When using Netscape-derived libraries, this file may also contain
Certificate Authority certificates.
.It Sy TLS_CHECKPEER Ar on/true/yes/off/false/no
If enabled,
.Sy TLS_CHECKPEER
will cause the LDAP server's TLS certificated to be verified.
If the server's TLS certificate cannot be verified (usually because it
is signed by an unknown certificate authority),
.Nm sudo
will be unable to connect to it.
If
.Sy TLS_CHECKPEER
is disabled, no check is made.
Note that disabling the check creates an opportunity for man-in-the-middle
attacks since the server's identity will not be authenticated.
If possible, the CA's certificate should be installed locally so it can
be verified.
.Pp
This option is not supported by the IBM LDAP libraries.
.It Sy TLS_KEY Ar file name
The path to a file containing the private key which matches the
certificate specified by
.Sy TLS_CERT .
The private key must not be password-protected.
The key type depends on the LDAP libraries used.
.Bl -tag -width 4n
.It OpenLDAP:
.Li tls_key /etc/ssl/client_key.pem
.It Netscape-derived:
.Li tls_key /var/ldap/key3.db
.It IBM LDAP:
.Li tls_key /usr/ldap/ldapkey.kdb
.El
.Pp
When using IBM LDAP libraries, this file may also contain
Certificate Authority and client certificates and may be encrypted.
.It Sy TLS_CIPHERS Ar cipher list
The
.Sy TLS_CIPHERS
parameter allows the administer to restrict which encryption algorithms
may be used for TLS (SSL) connections.
See the OpenLDAP or IBM Tivoli Directory Server manual for a list of valid
ciphers.
.Pp
This option is not supported by Netscape-derived libraries.
.It Sy TLS_KEYPW Ar secret
The
.Sy TLS_KEYPW
contains the password used to decrypt the key database on clients
using the IBM LDAP library.
The
.Ar secret
may be a plain text password or a base64-encoded string with a
.Dq base64:
prefix.
For example:
.Bd -literal -offset 4n
TLS_KEYPW base64:dGVzdA==
.Ed
.Pp
If a plain text password is used, it should be a simple string without quotes.
Plain text passwords may not include the comment character
.Pq Ql #
and the escaping of special characters with a backslash
.Pq Ql \e
is not supported.
If this option is used,
.Pa @ldap_conf@
must not be world-readable to avoid exposing the password.
Alternately, a
.Em stash file
can be used to store the password in encrypted form (see below).
.Pp
If no
.Sy TLS_KEYPW
is specified, a
.Em stash file
will be used if it exists.
The
.Em stash file
must have the same path as the file specified by
.Sy TLS_KEY ,
but use a
.Li .sth
file extension instead of
.Li .kdb ,
e.g.,
.Li ldapkey.sth .
The default
.Li ldapkey.kdb
that ships with the IBM Tivoli Directory Server is encrypted with the password
.Li ssl_password .
The
.Em gsk8capicmd
utility can be used to manage the key database and create a
.Em stash file .
.Pp
This option is only supported by the IBM LDAP libraries.
.It Sy TLS_REQCERT Ar level
The
.Sy TLS_REQCERT
parameter controls how the LDAP server's TLS certificated will be
verified (if at all).
If the server's TLS certificate cannot be verified (usually because it
is signed by an unknown certificate authority),
.Nm sudo
will be unable to connect to it.
The following
.Ar level
values are supported:
.Bl -tag -width 8n -offset 4n
.It never
The server certificate will not be requested or checked.
.It allow
The server certificate will be requested.
A missing or invalid certificate is ignored and not considered an error.
.It try
The server certificate will be requested.
A missing certificate is ignored but an invalid certificate will
result in a connection error.
.It demand | Ar hard
The server certificate will be requested.
A missing or invalid certificate will result in a connection error.
This is the default behavior.
.El
.Pp
This option is only supported by the OpenLDAP libraries.
Other LDAP libraries only support the
.Sy TLS_CHECKPEER
parameter.
.It Sy TLS_RANDFILE Ar file name
The
.Sy TLS_RANDFILE
parameter specifies the path to an entropy source for systems that lack
a random device.
It is generally used in conjunction with
.Em prngd
or
.Em egd .
.Pp
This option is only supported by the OpenLDAP libraries.
.It Sy URI Ar ldap[s]://[hostname[:port]] ...
Specifies a white space-delimited list of one or more URIs describing
the LDAP server(s) to connect to.
The
.Em protocol
may be either
.Em ldap
.Em ldaps ,
the latter being for servers that support TLS (SSL) encryption.
If no
.Em port
is specified, the default is port 389 for
.Li ldap://
or port 636 for
.Li ldaps:// .
If no
.Em hostname
is specified,
.Nm sudo
will connect to
.Em localhost .
Multiple
.Sy URI
lines are treated identically to a
.Sy URI
line containing multiple entries.
Only systems using the OpenSSL libraries support the mixing of
.Li ldap://
and
.Li ldaps://
URIs.
Both the Netscape-derived and IBM LDAP libraries used on most commercial
versions of Unix are only capable of supporting one or the other.
.It Sy USE_SASL Ar on/true/yes/off/false/no
Enable
.Sy USE_SASL
for LDAP servers that support SASL authentication.
.It Sy ROOTSASL_AUTH_ID Ar identity
The SASL user name to use when
.Sy ROOTUSE_SASL
is enabled.
.El
.Pp
See the
.Pa ldap.conf
entry in the
.Sx EXAMPLES
section.
.Ss Configuring nsswitch.conf
Unless it is disabled at build time,
.Nm sudo
consults the Name Service Switch file,
.Pa @nsswitch_conf@ ,
to specify the
.Em sudoers
search order.
Sudo looks for a line beginning with
.Li sudoers :
and uses this to determine the search order.
Note that
.Nm sudo
does
not stop searching after the first match and later matches take
precedence over earlier ones.
The following sources are recognized:
.Pp
.Bl -tag -width 8n -offset 4n -compact
.It files
read sudoers from
.Pa @sysconfdir@/sudoers
.It ldap
read sudoers from LDAP
.El
.Pp
In addition, the entry
.Li [NOTFOUND=return]
will short-circuit the search if the user was not found in the
preceding source.
.Pp
To consult LDAP first followed by the local sudoers file (if it
exists), use:
.Bd -literal -offset 4n
sudoers: ldap files
.Ed
.Pp
The local
.Em sudoers
file can be ignored completely by using:
.Bd -literal -offset 4n
sudoers: ldap
.Ed
.Pp
If the
.Pa @nsswitch_conf@
file is not present or there is no sudoers line, the following
default is assumed:
.Bd -literal -offset 4n
sudoers: files
.Ed
.Pp
Note that
.Pa @nsswitch_conf@
is supported even when the underlying operating system does not use
an nsswitch.conf file, except on AIX (see below).
.Ss Configuring netsvc.conf
On AIX systems, the
.Pa @netsvc_conf@
file is consulted instead of
.Pa @nsswitch_conf@ .
.Nm sudo
simply treats
.Pa netsvc.conf
as a variant of
.Pa nsswitch.conf ;
information in the previous section unrelated to the file format
itself still applies.
.Pp
To consult LDAP first followed by the local sudoers file (if it
exists), use:
.Bd -literal -offset 4n
sudoers = ldap, files
.Ed
.Pp
The local
.Em sudoers
file can be ignored completely by using:
.Bd -literal -offset 4n
sudoers = ldap
.Ed
.Pp
To treat LDAP as authoritative and only use the local sudoers file
if the user is not present in LDAP, use:
.Bd -literal -offset 4n
sudoers = ldap = auth, files
.Ed
.Pp
Note that in the above example, the
.Li auth
qualifier only affects user lookups; both LDAP and
.Em sudoers
will be queried for
.Li Defaults
entries.
.Pp
If the
.Pa @netsvc_conf@
file is not present or there is no sudoers line, the following
default is assumed:
.Bd -literal -offset 4n
sudoers = files
.Ed
.Ss Integration with sssd
On systems with the
.Em System Security Services Daemon
(SSSD) and where
.Nm sudo
has been built with SSSD support,
it is possible to use SSSD to cache LDAP
.Em sudoers
rules.
To use SSSD as the
.Em sudoers
source, you should use
.Li sss
instead of
.Li ldap
for the sudoers entry in
.Pa @nsswitch_conf@ .
Note that the
.Pa @ldap_conf@
file is not used by the SSSD
.Nm sudo
back end.
Please see
.Xr sssd-sudo @mansectform@
for more information on configuring
.Nm sudo
to work with SSSD.
.Sh FILES
.Bl -tag -width 24n
.It Pa @ldap_conf@
LDAP configuration file
.It Pa @nsswitch_conf@
determines sudoers source order
.It Pa @netsvc_conf@
determines sudoers source order on AIX
.El
.Sh EXAMPLES
.Ss Example ldap.conf
.Bd -literal -offset 2n
# Either specify one or more URIs or one or more host:port pairs.
# If neither is specified sudo will default to localhost, port 389.
#
#host          ldapserver
#host          ldapserver1 ldapserver2:390
#
# Default port if host is specified without one, defaults to 389.
#port          389
#
# URI will override the host and port settings.
uri            ldap://ldapserver
#uri            ldaps://secureldapserver
#uri            ldaps://secureldapserver ldap://ldapserver
#
# The amount of time, in seconds, to wait while trying to connect to
# an LDAP server.
bind_timelimit 30
#
# The amount of time, in seconds, to wait while performing an LDAP query.
timelimit 30
#
# Must be set or sudo will ignore LDAP; may be specified multiple times.
sudoers_base   ou=SUDOers,dc=my-domain,dc=com
#
# verbose sudoers matching from ldap
#sudoers_debug 2
#
# Enable support for time-based entries in sudoers.
#sudoers_timed yes
#
# optional proxy credentials
#binddn        <who to search as>
#bindpw        <password>
#rootbinddn    <who to search as, uses /etc/ldap.secret for bindpw>
#
# LDAP protocol version, defaults to 3
#ldap_version 3
#
# Define if you want to use an encrypted LDAP connection.
# Typically, you must also set the port to 636 (ldaps).
#ssl on
#
# Define if you want to use port 389 and switch to
# encryption before the bind credentials are sent.
# Only supported by LDAP servers that support the start_tls
# extension such as OpenLDAP.
#ssl start_tls
#
# Additional TLS options follow that allow tweaking of the
# SSL/TLS connection.
#
#tls_checkpeer yes # verify server SSL certificate
#tls_checkpeer no  # ignore server SSL certificate
#
# If you enable tls_checkpeer, specify either tls_cacertfile
# or tls_cacertdir.  Only supported when using OpenLDAP.
#
#tls_cacertfile /etc/certs/trusted_signers.pem
#tls_cacertdir  /etc/certs
#
# For systems that don't have /dev/random
# use this along with PRNGD or EGD.pl to seed the
# random number pool to generate cryptographic session keys.
# Only supported when using OpenLDAP.
#
#tls_randfile /etc/egd-pool
#
# You may restrict which ciphers are used.  Consult your SSL
# documentation for which options go here.
# Only supported when using OpenLDAP.
#
#tls_ciphers <cipher-list>
#
# Sudo can provide a client certificate when communicating to
# the LDAP server.
# Tips:
#   * Enable both lines at the same time.
#   * Do not password protect the key file.
#   * Ensure the keyfile is only readable by root.
#
# For OpenLDAP:
#tls_cert /etc/certs/client_cert.pem
#tls_key  /etc/certs/client_key.pem
#
# For Netscape-derived LDAP, tls_cert and tls_key may specify either
# a directory, in which case the files in the directory must have the
# default names (e.g., cert8.db and key4.db), or the path to the cert
# and key files themselves.  However, a bug in version 5.0 of the LDAP
# SDK will prevent specific file names from working.  For this reason
# it is suggested that tls_cert and tls_key be set to a directory,
# not a file name.
#
# The certificate database specified by tls_cert may contain CA certs
# and/or the client's cert.  If the client's cert is included, tls_key
# should be specified as well.
# For backward compatibility, "sslpath" may be used in place of tls_cert.
#tls_cert /var/ldap
#tls_key /var/ldap
#
# If using SASL authentication for LDAP (OpenSSL)
# use_sasl yes
# sasl_auth_id <SASL user name>
# rootuse_sasl yes
# rootsasl_auth_id <SASL user name for root access>
# sasl_secprops none
# krb5_ccname /etc/.ldapcache
.Ed
.Ss Sudoers schema for OpenLDAP
The following schema, in OpenLDAP format, is included with
.Nm sudo
source and binary distributions as
.Pa schema.OpenLDAP .
Simply copy
it to the schema directory (e.g.,
.Pa /etc/openldap/schema ) ,
add the proper
.Li include
line in
.Pa slapd.conf
and restart
.Nm slapd .
Sites using the optional on-line configuration supported by OpenLDAP 2.3
and higher should apply the
.Pa schema.olcSudo
file instead.
.Bd -literal -offset 2n
attributetype ( 1.3.6.1.4.1.15953.9.1.1
   NAME 'sudoUser'
   DESC 'User(s) who may  run sudo'
   EQUALITY caseExactIA5Match
   SUBSTR caseExactIA5SubstringsMatch
   SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

attributetype ( 1.3.6.1.4.1.15953.9.1.2
   NAME 'sudoHost'
   DESC 'Host(s) who may run sudo'
   EQUALITY caseExactIA5Match
   SUBSTR caseExactIA5SubstringsMatch
   SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

attributetype ( 1.3.6.1.4.1.15953.9.1.3
   NAME 'sudoCommand'
   DESC 'Command(s) to be executed by sudo'
   EQUALITY caseExactIA5Match
   SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

attributetype ( 1.3.6.1.4.1.15953.9.1.4
   NAME 'sudoRunAs'
   DESC 'User(s) impersonated by sudo'
   EQUALITY caseExactIA5Match
   SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

attributetype ( 1.3.6.1.4.1.15953.9.1.5
   NAME 'sudoOption'
   DESC 'Options(s) followed by sudo'
   EQUALITY caseExactIA5Match
   SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

attributetype ( 1.3.6.1.4.1.15953.9.1.6
   NAME 'sudoRunAsUser'
   DESC 'User(s) impersonated by sudo'
   EQUALITY caseExactIA5Match
   SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

attributetype ( 1.3.6.1.4.1.15953.9.1.7
   NAME 'sudoRunAsGroup'
   DESC 'Group(s) impersonated by sudo'
   EQUALITY caseExactIA5Match
   SYNTAX 1.3.6.1.4.1.1466.115.121.1.26 )

attributetype ( 1.3.6.1.4.1.15953.9.1.8
   NAME 'sudoNotBefore'
   DESC 'Start of time interval for which the entry is valid'
   EQUALITY generalizedTimeMatch
   ORDERING generalizedTimeOrderingMatch
   SYNTAX 1.3.6.1.4.1.1466.115.121.1.24 )

attributetype ( 1.3.6.1.4.1.15953.9.1.9
   NAME 'sudoNotAfter'
   DESC 'End of time interval for which the entry is valid'
   EQUALITY generalizedTimeMatch
   ORDERING generalizedTimeOrderingMatch
   SYNTAX 1.3.6.1.4.1.1466.115.121.1.24 )

attributetype ( 1.3.6.1.4.1.15953.9.1.10
    NAME 'sudoOrder'
    DESC 'an integer to order the sudoRole entries'
    EQUALITY integerMatch
    ORDERING integerOrderingMatch
    SYNTAX 1.3.6.1.4.1.1466.115.121.1.27 )

objectclass ( 1.3.6.1.4.1.15953.9.2.1 NAME 'sudoRole' SUP top STRUCTURAL
   DESC 'Sudoer Entries'
   MUST ( cn )
   MAY ( sudoUser $ sudoHost $ sudoCommand $ sudoRunAs $ sudoRunAsUser $
         sudoRunAsGroup $ sudoOption $ sudoNotBefore $ sudoNotAfter $
         sudoOrder $ description )
   )
.Ed
.Sh SEE ALSO
.Xr cvtsudoers 1 ,
.Xr ldap.conf @mansectform@ ,
.Xr sssd-sudo @mansectform@ ,
.Xr sudo.conf @mansectform@ ,
.Xr sudoers @mansectform@
.Sh AUTHORS
Many people have worked on
.Nm sudo
over the years; this version consists of code written primarily by:
.Bd -ragged -offset indent
.An Todd C. Miller
.Ed
.Pp
See the CONTRIBUTORS file in the
.Nm sudo
distribution (https://www.sudo.ws/contributors.html) for an
exhaustive list of people who have contributed to
.Nm sudo .
.Sh CAVEATS
Note that there are differences in the way that LDAP-based
.Em sudoers
is parsed compared to file-based
.Em sudoers .
See the
.Sx Differences between LDAP and non-LDAP sudoers
section for more information.
.Sh BUGS
If you feel you have found a bug in
.Nm sudo ,
please submit a bug report at https://bugzilla.sudo.ws/
.Sh SUPPORT
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.
.Sh DISCLAIMER
.Nm sudo
is provided
.Dq 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
.Nm sudo
or https://www.sudo.ws/license.html for complete details.