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diff --git a/doc/man/man5/slapd-ldap.5 b/doc/man/man5/slapd-ldap.5 new file mode 100644 index 0000000..ffcbe81 --- /dev/null +++ b/doc/man/man5/slapd-ldap.5 @@ -0,0 +1,700 @@ +.TH SLAPD-LDAP 5 "RELEASEDATE" "OpenLDAP LDVERSION" +.\" Copyright 1998-2022 The OpenLDAP Foundation All Rights Reserved. +.\" Copying restrictions apply. See COPYRIGHT/LICENSE. +.\" $OpenLDAP$ +.SH NAME +slapd\-ldap \- LDAP backend to slapd +.SH SYNOPSIS +ETCDIR/slapd.conf +.SH DESCRIPTION +The LDAP backend to +.BR slapd (8) +is not an actual database; instead it acts as a proxy to forward incoming +requests to another LDAP server. While processing requests it will also +chase referrals, so that referrals are fully processed instead of being +returned to the slapd client. + +Sessions that explicitly Bind to the back-ldap database always create their +own private connection to the remote LDAP server. Anonymous sessions will +share a single anonymous connection to the remote server. For sessions bound +through other mechanisms, all sessions with the same DN will share the +same connection. This connection pooling strategy can enhance the proxy's +efficiency by reducing the overhead of repeatedly making/breaking multiple +connections. + +The ldap database can also act as an information service, i.e. the identity +of locally authenticated clients is asserted to the remote server, possibly +in some modified form. +For this purpose, the proxy binds to the remote server with some +administrative identity, and, if required, authorizes the asserted identity. +See the +.IR idassert\- * +rules below. +The administrative identity of the proxy, on the remote server, must be +allowed to authorize by means of appropriate +.B authzTo +rules; see +.BR slapd.conf (5) +for details. + +The proxy instance of +.BR slapd (8) +must contain schema information for the attributes and objectClasses +used in filters, request DNs and request-related data in general. +It should also contain schema information for the data returned +by the proxied server. +It is the responsibility of the proxy administrator to keep the schema +of the proxy lined up with that of the proxied server. + +.LP +Note: When looping back to the same instance of +.BR slapd (8), +each connection requires a new thread; as a consequence, the +.BR slapd (8) +\fBthreads\fP parameter may need some tuning. In those cases, +one may consider using +.BR slapd\-relay (5) +instead, which performs the relayed operation +internally and thus reuses the same connection. + +.SH CONFIGURATION +These +.B slapd.conf +options apply to the LDAP backend database. +That is, they must follow a "database ldap" line and come before any +subsequent "backend" or "database" lines. +Other database options are described in the +.BR slapd.conf (5) +manual page. + +.LP +Note: In early versions of back-ldap it was recommended to always set +.LP +.RS +.nf +lastmod off +.fi +.RE +.LP +for +.B ldap +and +.B meta +databases. +This was required because operational attributes related to entry creation +and modification should not be proxied, as they could be mistakenly written +to the target server(s), generating an error. +The current implementation automatically sets lastmod to \fBoff\fP, +so its use is redundant and should be omitted. + +.TP +.B uri <ldapurl> +LDAP server to use. Multiple URIs can be set in a single +.B ldapurl +argument, resulting in the underlying library automatically +calling the first server of the list that responds, e.g. + +\fBuri "ldap://host/ ldap://backup\-host/"\fP + +The URI list is space- or comma-separated. +Whenever the server that responds is not the first one in the list, +the list is rearranged and the responsive server is moved to the head, +so that it will be first contacted the next time a connection +needs to be created. +.HP +.hy 0 +.B acl\-bind +.B bindmethod=simple|sasl [binddn=<simple DN>] [credentials=<simple password>] +.B [saslmech=<SASL mech>] [secprops=<properties>] [realm=<realm>] +.B [authcId=<authentication ID>] [authzId=<authorization ID>] +.B [starttls=no|yes|critical] +.B [tls_cert=<file>] +.B [tls_key=<file>] +.B [tls_cacert=<file>] +.B [tls_cacertdir=<path>] +.B [tls_reqcert=never|allow|try|demand] +.B [tls_reqsan=never|allow|try|demand] +.B [tls_cipher_suite=<ciphers>] +.B [tls_ecname=<names>] +.B [tls_protocol_min=<major>[.<minor>]] +.B [tls_crlcheck=none|peer|all] +.RS +Allows one to define the parameters of the authentication method that is +internally used by the proxy to collect info related to access control, +and whenever an operation occurs with the identity of the rootdn +of the LDAP proxy database. +The identity defined by this directive, according to the properties +associated to the authentication method, is supposed to have read access +on the target server to attributes used on the proxy for ACL checking. + +There is no risk of giving away such values; they are only used to +check permissions. +The default is to use +.BR simple +bind, with empty \fIbinddn\fP and \fIcredentials\fP, +which means that the related operations will be performed anonymously. +If not set, and if \fBidassert\-bind\fP is defined, this latter identity +is used instead. See \fBidassert\-bind\fP for details. + +The connection between the proxy database and the remote server +associated to this identity is cached regardless of the lifespan +of the client-proxy connection that first established it. + +.B This identity is not implicitly used by the proxy +.B when the client connects anonymously. +The +.B idassert\-bind +feature, instead, in some cases can be crafted to implement that behavior, +which is \fIintrinsically unsafe and should be used with extreme care\fP. + +The TLS settings default to the same as the main slapd TLS settings, +except for +.B tls_reqcert +which defaults to "demand", and +.B tls_reqsan +which defaults to "allow". +.RE + +.TP +.B cancel {ABANDON|ignore|exop[\-discover]} +Defines how to handle operation cancellation. +By default, +.B abandon +is invoked, so the operation is abandoned immediately. +If set to +.BR ignore , +no action is taken and any further response is ignored; this may result +in further response messages to be queued for that connection, so it is +recommended that long lasting connections are timed out either by +.I idle\-timeout +or +.IR conn\-ttl , +so that resources eventually get released. +If set to +.BR exop , +a +.I cancel +operation (RFC 3909) is issued, resulting in the cancellation +of the current operation; the +.I cancel +operation waits for remote server response, so its use +may not be recommended. +If set to +.BR exop\-discover , +support of the +.I cancel +extended operation is detected by reading the remote server's root DSE. + +.TP +.B chase\-referrals {YES|no} +enable/disable automatic referral chasing, which is delegated to the +underlying libldap, with rebinding eventually performed if the +\fBrebind\-as\-user\fP directive is used. The default is to chase referrals. + +.TP +.B conn\-pool\-max <int> +This directive defines the maximum size of the privileged connections pool. + +.TP +.B conn\-ttl <time> +This directive causes a cached connection to be dropped and recreated +after a given ttl, regardless of being idle or not. + +.TP +.B idassert\-authzFrom <authz-regexp> +if defined, selects what +.I local +identities are authorized to exploit the identity assertion feature. +The string +.B <authz-regexp> +mostly follows the rules defined for the +.I authzFrom +attribute. +See +.BR slapd.conf (5), +section related to +.BR authz\-policy , +for details on the syntax of this field. This parameter differs from +the documented behavior in relation to the meaning of *, which in this +case allows anonymous rather than denies. + +.HP +.hy 0 +.B idassert\-bind +.B bindmethod=none|simple|sasl [binddn=<simple DN>] [credentials=<simple password>] +.B [saslmech=<SASL mech>] [secprops=<properties>] [realm=<realm>] +.B [authcId=<authentication ID>] [authzId=<authorization ID>] +.B [authz={native|proxyauthz}] [mode=<mode>] [flags=<flags>] +.B [starttls=no|yes|critical] +.B [tls_cert=<file>] +.B [tls_key=<file>] +.B [tls_cacert=<file>] +.B [tls_cacertdir=<path>] +.B [tls_reqcert=never|allow|try|demand] +.B [tls_reqsan=never|allow|try|demand] +.B [tls_cipher_suite=<ciphers>] +.B [tls_ecname=<names>] +.B [tls_protocol_min=<version>] +.B [tls_crlcheck=none|peer|all] +.RS +Allows one to define the parameters of the authentication method that is +internally used by the proxy to authorize connections that are +authenticated by other databases. +Direct binds are always proxied without any idassert handling. + +The identity defined by this directive, according to the properties +associated to the authentication method, is supposed to have auth access +on the target server to attributes used on the proxy for authentication +and authorization, and to be allowed to authorize the users. +This requires to have +.B proxyAuthz +privileges on a wide set of DNs, e.g. +.BR authzTo=dn.subtree:"" , +and the remote server to have +.B authz\-policy +set to +.B to +or +.BR both . +See +.BR slapd.conf (5) +for details on these statements and for remarks and drawbacks about +their usage. +The supported bindmethods are + +\fBnone|simple|sasl\fP + +where +.B none +is the default, i.e. no \fIidentity assertion\fP is performed. + +The +.B authz +parameter is used to instruct the SASL bind to exploit +.B native +SASL authorization, if available; since connections are cached, +this should only be used when authorizing with a fixed identity +(e.g. by means of the +.B authzDN +or +.B authzID +parameters). +Otherwise, the default +.B proxyauthz +is used, i.e. the proxyAuthz control (Proxied Authorization, RFC 4370) +is added to all operations. + +The supported modes are: + +\fB<mode> := {legacy|anonymous|none|self}\fP + +If +.B <mode> +is not present, and +.B authzId +is given, the proxy always authorizes that identity. +.B <authorization ID> +can be + +\fBu:<user>\fP + +\fB[dn:]<DN>\fP + +The former is supposed to be expanded by the remote server according +to the authz rules; see +.BR slapd.conf (5) +for details. +In the latter case, whether or not the +.B dn: +prefix is present, the string must pass DN validation and normalization. + +The default mode is +.BR legacy , +which implies that the proxy will either perform a simple bind as the +.I authcDN +or a SASL bind as the +.I authcID +and assert the client's identity when it is not anonymous. +The other modes imply that the proxy will always either perform a simple bind +as the +.IR authcDN +or a SASL bind as the +.IR authcID , +unless restricted by +.BR idassert\-authzFrom +rules (see below), in which case the operation will fail; +eventually, it will assert some other identity according to +.BR <mode> . +Other identity assertion modes are +.BR anonymous +and +.BR self , +which respectively mean that the +.I empty +or the +.IR client 's +identity +will be asserted; +.BR none , +which means that no proxyAuthz control will be used, so the +.I authcDN +or the +.I authcID +identity will be asserted. +For all modes that require the use of the +.I proxyAuthz +control, on the remote server the proxy identity must have appropriate +.I authzTo +permissions, or the asserted identities must have appropriate +.I authzFrom +permissions. Note, however, that the ID assertion feature is mostly +useful when the asserted identities do not exist on the remote server. + +Flags can be + +\fBoverride,[non\-]prescriptive,proxy\-authz\-[non\-]critical,dn\-{authzid|whoami}\fP + +When the +.B override +flag is used, identity assertion takes place even when the database +is authorizing for the identity of the client, i.e. after binding +with the provided identity, and thus authenticating it, the proxy +performs the identity assertion using the configured identity and +authentication method. + +When the +.B prescriptive +flag is used (the default), operations fail with +\fIinappropriateAuthentication\fP +for those identities whose assertion is not allowed by the +.B idassert\-authzFrom +patterns. +If the +.B non\-prescriptive +flag is used, operations are performed anonymously for those identities +whose assertion is not allowed by the +.B idassert\-authzFrom +patterns. + +When the +.B proxy\-authz\-non\-critical +flag is used (the default), the proxyAuthz control is not marked as critical, +in violation of RFC 4370. Use of +.B proxy\-authz\-critical +is recommended. + +When the +.B dn\-authzid +flag is used, RFC 3829 LDAP Authorization Identity Controls +is used to retrieve the identity associated to the SASL identity; +when the +.B dn\-whoami +flag is used, RFC 4532 LDAP Who am I? Operation is performed +after the bind for the same purpose. + +The TLS settings default to the same as the main slapd TLS settings, +except for +.B tls_reqcert +which defaults to "demand", and +.B tls_reqsan +which defaults to "allow". + +The identity associated to this directive is also used for privileged +operations whenever \fBidassert\-bind\fP is defined and \fBacl\-bind\fP +is not. See \fBacl\-bind\fP for details. + +.TP +.B idassert-passthru <authz-regexp> +if defined, selects what +.I local +identities bypass the identity assertion feature. +Those identities need to be known by the remote host. +The string +.B <authz-regexp> +follows the rules defined for the +.I authzFrom +attribute. +See +.BR slapd.conf (5), +section related to +.BR authz\-policy , +for details on the syntax of this field. + +.TP +.B idle\-timeout <time> +This directive causes a cached connection to be dropped an recreated +after it has been idle for the specified time. + +.TP +.B keepalive <idle>:<probes>:<interval> +The +.B keepalive +parameter sets the values of \fIidle\fP, \fIprobes\fP, and \fIinterval\fP +used to check whether a socket is alive; +.I idle +is the number of seconds a connection needs to remain idle before TCP +starts sending keepalive probes; +.I probes +is the maximum number of keepalive probes TCP should send before dropping +the connection; +.I interval +is interval in seconds between individual keepalive probes. +Only some systems support the customization of these values; +the +.B keepalive +parameter is ignored otherwise, and system-wide settings are used. + +.TP +.B tcp\-user\-timeout <milliseconds> +If non-zero, corresponds to the +.B TCP_USER_TIMEOUT +set on the target connections, overriding the operating system setting. +Only some systems support the customization of this parameter, it is +ignored otherwise and system-wide settings are used. + +.TP +.B network\-timeout <time> +Sets the network timeout value after which +.BR poll (2)/ select (2) +following a +.BR connect (2) +returns in case of no activity. +The value is in seconds, and it can be specified as for +.BR idle\-timeout . + +.TP +.B norefs <NO|yes> +If +.BR yes , +do not return search reference responses. +By default, they are returned unless request is LDAPv2. + +.TP +.B omit-unknown-schema <NO|yes> +If +.BR yes , +do not return objectClasses or attributes that are not known to the local server. +The default is to return all schema elements. + +.TP +.B noundeffilter <NO|yes> +If +.BR yes , +return success instead of searching if a filter is undefined or contains +undefined portions. +By default, the search is propagated after replacing undefined portions +with +.BR (!(objectClass=*)) , +which corresponds to the empty result set. + +.TP +.B onerr {CONTINUE|stop} +This directive allows one to select the behavior in case an error is returned +by the remote server during a search. +The default, \fBcontinue\fP, consists in returning success. +If the value is set to \fBstop\fP, the error is returned to the client. + +.TP +.B protocol\-version {0,2,3} +This directive indicates what protocol version must be used to contact +the remote server. +If set to 0 (the default), the proxy uses the same protocol version +used by the client, otherwise the requested protocol is used. +The proxy returns \fIunwillingToPerform\fP if an operation that is +incompatible with the requested protocol is attempted. + +.TP +.B proxy\-whoami {NO|yes} +Turns on proxying of the WhoAmI extended operation. If this option is +given, back-ldap will replace slapd's original WhoAmI routine with its +own. On slapd sessions that were authenticated by back-ldap, the WhoAmI +request will be forwarded to the remote LDAP server. Other sessions will +be handled by the local slapd, as before. This option is mainly useful +in conjunction with Proxy Authorization. + +.TP +.B quarantine <interval>,<num>[;<interval>,<num>[...]] +Turns on quarantine of URIs that returned +.IR LDAP_UNAVAILABLE , +so that an attempt to reconnect only occurs at given intervals instead +of any time a client requests an operation. +The pattern is: retry only after at least +.I interval +seconds elapsed since last attempt, for exactly +.I num +times; then use the next pattern. +If +.I num +for the last pattern is "\fB+\fP", it retries forever; otherwise, +no more retries occur. +The process can be restarted by resetting the \fIolcDbQuarantine\fP +attribute of the database entry in the configuration backend. + +.TP +.B rebind\-as\-user {NO|yes} +If this option is given, the client's bind credentials are remembered +for rebinds, when trying to re-establish a broken connection, +or when chasing a referral, if +.B chase\-referrals +is set to +.IR yes . + +.TP +.B session\-tracking\-request {NO|yes} +Adds session tracking control for all requests. +The client's IP and hostname, and the identity associated to each request, +if known, are sent to the remote server for informational purposes. +This directive is incompatible with setting \fIprotocol\-version\fP to 2. + +.TP +.B single\-conn {NO|yes} +Discards current cached connection when the client rebinds. + +.TP +.B t\-f\-support {NO|yes|discover} +enable if the remote server supports absolute filters +(see \fIRFC 4526\fP for details). +If set to +.BR discover , +support is detected by reading the remote server's root DSE. + +.TP +.B timeout [<op>=]<val> [...] +This directive allows one to set per-operation timeouts. +Operations can be + +\fB<op> ::= bind, add, delete, modrdn, modify, compare, search\fP + +The overall duration of the \fBsearch\fP operation is controlled either +by the \fBtimelimit\fP parameter or by server-side enforced +time limits (see \fBtimelimit\fP and \fBlimits\fP in +.BR slapd.conf (5) +for details). +This \fBtimeout\fP parameter controls how long the target can be +irresponsive before the operation is aborted. +Timeout is meaningless for the remaining operations, +\fBunbind\fP and \fBabandon\fP, which do not imply any response, +while it is not yet implemented in currently supported \fBextended\fP +operations. +If no operation is specified, the timeout \fBval\fP affects all +supported operations. + +Note: if the timelimit is exceeded, the operation is cancelled +(according to the \fBcancel\fP directive); +the protocol does not provide any means to rollback operations, +so the client will not be notified about the result of the operation, +which may eventually succeeded or not. +In case the timeout is exceeded during a bind operation, the connection +is destroyed, according to RFC4511. + +Note: in some cases, this backend may issue binds prior +to other operations (e.g. to bind anonymously or with some prescribed +identity according to the \fBidassert\-bind\fP directive). +In this case, the timeout of the operation that resulted in the bind +is used. + +.HP +.hy 0 +.B tls {none|[try\-]start|[try\-]propagate|ldaps} +.B [starttls=no] +.B [tls_cert=<file>] +.B [tls_key=<file>] +.B [tls_cacert=<file>] +.B [tls_cacertdir=<path>] +.B [tls_reqcert=never|allow|try|demand] +.B [tls_reqsan=never|allow|try|demand] +.B [tls_cipher_suite=<ciphers>] +.B [tls_ecname=<names>] +.B [tls_crlcheck=none|peer|all] +.RS +Specify TLS settings for regular connections. + +If the first parameter is not "none" then this configures the TLS +settings to be used for regular connections. +The StartTLS extended operation will be used when establishing the +connection unless the URI directive protocol scheme is \fBldaps://\fP. +In that case this keyword may only be set to "ldaps" and the StartTLS +operation will not be used. + +With \fBpropagate\fP, the proxy issues the StartTLS operation only if +the original connection has a TLS layer set up. +The \fBtry\-\fP prefix instructs the proxy to continue operations +if the StartTLS operation failed; its use is \fBnot\fP recommended. + +The TLS settings default to the same as the main slapd TLS settings, +except for +.B tls_reqcert +which defaults to "demand", +.B tls_reqsan +which defaults to "allow", and +.B starttls +which is overshadowed by the first keyword and thus ignored. +.RE + +.TP +.B use\-temporary\-conn {NO|yes} +when set to +.BR yes , +create a temporary connection whenever competing with other threads +for a shared one; otherwise, wait until the shared connection is available. + +.SH ACCESS CONTROL +The +.B ldap +backend does not honor all ACL semantics as described in +.BR slapd.access (5). +In general, access checking is delegated to the remote server(s). +Only +.B read (=r) +access to the +.B entry +pseudo-attribute and to the other attribute values of the entries +returned by the +.B search +operation is honored, which is performed by the frontend. + +.SH OVERLAYS +The LDAP backend provides basic proxying functionalities to many overlays. +The +.B chain +overlay, described in +.BR slapo\-chain (5), +and the +.B translucent +overlay, described in +.BR slapo\-translucent (5), +deserve a special mention. + +Conversely, there are many overlays that are best used in conjunction +with the LDAP backend. +The +.B proxycache +overlay allows caching of LDAP search requests (queries) +in a local database. +See +.BR slapo\-pcache (5) +for details. +The +.B rwm +overlay provides DN rewrite and attribute/objectClass mapping +capabilities to the underlying database. +See +.BR slapo\-rwm (5) +for details. + +.SH FILES +.TP +ETCDIR/slapd.conf +default slapd configuration file +.SH SEE ALSO +.BR slapd.conf (5), +.BR slapd\-config (5), +.BR slapd\-meta (5), +.BR slapo\-chain (5), +.BR slapo\-pcache (5), +.BR slapo\-rwm (5), +.BR slapo\-translucent (5), +.BR slapd (8), +.BR ldap (3). +.SH AUTHOR +Howard Chu, with enhancements by Pierangelo Masarati |