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diff --git a/doc/man/man5/slapd.access.5 b/doc/man/man5/slapd.access.5 new file mode 100644 index 0000000..72e7140 --- /dev/null +++ b/doc/man/man5/slapd.access.5 @@ -0,0 +1,1183 @@ +.TH SLAPD.ACCESS 5 "RELEASEDATE" "OpenLDAP LDVERSION" +.\" Copyright 1998-2021 The OpenLDAP Foundation All Rights Reserved. +.\" Copying restrictions apply. See COPYRIGHT/LICENSE. +.\" $OpenLDAP$ +.SH NAME +slapd.access \- access configuration for slapd, the stand-alone LDAP daemon +.SH SYNOPSIS +ETCDIR/slapd.conf +.SH DESCRIPTION +The +.BR slapd.conf (5) +file contains configuration information for the +.BR slapd (8) +daemon. This configuration file is also used by the SLAPD tools +.BR slapacl (8), +.BR slapadd (8), +.BR slapauth (8), +.BR slapcat (8), +.BR slapdn (8), +.BR slapindex (8), +and +.BR slaptest (8). +.LP +The +.B slapd.conf +file consists of a series of global configuration options that apply to +.B slapd +as a whole (including all backends), followed by zero or more database +backend definitions that contain information specific to a backend +instance. +.LP +The general format of +.B slapd.conf +is as follows: +.LP +.nf + # comment - these options apply to every database + <global configuration options> + # first database definition & configuration options + database <backend 1 type> + <configuration options specific to backend 1> + # subsequent database definitions & configuration options + ... +.fi +.LP +Both the global configuration and each backend-specific section can +contain access information. Backend-specific access control +directives are used for those entries that belong to the backend, +according to their naming context. In case no access control +directives are defined for a backend or those which are defined are +not applicable, the directives from the global configuration section +are then used. +.LP +If no access controls are present, the default policy +allows anyone and everyone to read anything but restricts +updates to rootdn. (e.g., "access to * by * read"). +.LP +When dealing with an access list, because the global access list is +effectively appended to each per-database list, if the resulting +list is non-empty then the access list will end with an implicit +.B access to * by * none +directive. If there are no access directives applicable to a backend, +then a default read is used. +.LP +.B Be warned: the rootdn can always read and write EVERYTHING! +.LP +For entries not held in any backend (such as a root DSE), the +global directives are used. +.LP +Arguments that should be replaced by actual text are shown in +brackets <>. +.SH THE ACCESS DIRECTIVE +The structure of the access control directives is +.TP +.B access to <what> "[ by <who> [ <access> ] [ <control> ] ]+" +Grant access (specified by +.BR <access> ) +to a set of entries and/or attributes (specified by +.BR <what> ) +by one or more requestors (specified by +.BR <who> ). + +.LP +Lists of access directives are evaluated in the order they appear +in \fIslapd.conf\fP. +When a +.B <what> +clause matches the datum whose access is being evaluated, its +.B <who> +clause list is checked. +When a +.B <who> +clause matches the accessor's properties, its +.B <access> +and +.B <control> +clauses are evaluated. +Access control checking stops at the first match of the +.B <what> +and +.B <who> +clause, unless otherwise dictated by the +.B <control> +clause. +Each +.B <who> +clause list is implicitly terminated by a +.LP +.nf + by * none stop +.fi +.LP +clause that results in stopping the access control with no access +privileges granted. +Each +.B <what> +clause list is implicitly terminated by a +.LP +.nf + access to * + by * none +.fi +.LP +clause that results in granting no access privileges to an otherwise +unspecified datum. +.SH THE <WHAT> FIELD +The field +.BR <what> +specifies the entity the access control directive applies to. +It can have the forms +.LP +.nf + dn[.<dnstyle>]=<dnpattern> + filter=<ldapfilter> + attrs=<attrlist>[ val[/matchingRule][.<attrstyle>]=<attrval>] +.fi +.LP +with +.LP +.nf + <dnstyle>={{exact|base(object)}|regex + |one(level)|sub(tree)|children} + <attrlist>={<attr>|[{!|@}]<objectClass>}[,<attrlist>] + <attrstyle>={{exact|base(object)}|regex + |one(level)|sub(tree)|children} +.fi +.LP +The statement +.B dn=<dnpattern> +selects the entries based on their naming context. +The +.B <dnpattern> +is a string representation of the entry's DN. +The wildcard +.B * +stands for all the entries, and it is implied if no +.B dn +form is given. +.LP +The +.B <dnstyle> +is optional; however, it is recommended to specify it to avoid ambiguities. +.B Base +(synonym of +.BR baseObject ), +the default, +or +.B exact +(an alias of +.BR base ) +indicates the entry whose DN is equal to the +.BR <dnpattern> ; +.B one +(synonym of +.BR onelevel ) +indicates all the entries immediately below the +.BR <dnpattern> , +.B sub +(synonym of +.BR subtree ) +indicates all entries in the subtree at the +.BR <dnpattern> , +.B children +indicates all the entries below (subordinate to) the +.BR <dnpattern> . +.LP +If the +.B <dnstyle> +qualifier is +.BR regex , +then +.B <dnpattern> +is a POSIX (''extended'') regular expression pattern, +as detailed in +.BR regex (7) +and/or +.BR re_format (7), +matching a normalized string representation of the entry's DN. +The regex form of the pattern does not (yet) support UTF-8. +.LP +The statement +.B filter=<ldapfilter> +selects the entries based on a valid LDAP filter as described in RFC 4515. +A filter of +.B (objectClass=*) +is implied if no +.B filter +form is given. +.LP +The statement +.B attrs=<attrlist> +selects the attributes the access control rule applies to. +It is a comma-separated list of attribute types, plus the special names +.BR entry , +indicating access to the entry itself, and +.BR children , +indicating access to the entry's children. ObjectClass names may also +be specified in this list, which will affect all the attributes that +are required and/or allowed by that objectClass. +Actually, names in +.B <attrlist> +that are prefixed by +.B @ +are directly treated as objectClass names. A name prefixed by +.B ! +is also treated as an objectClass, but in this case the access rule +affects the attributes that are not required nor allowed +by that objectClass. +If no +.B attrs +form is given, +.B attrs=@extensibleObject +is implied, i.e. all attributes are addressed. +.LP +Using the form +.B attrs=<attr> val[/matchingRule][.<attrstyle>]=<attrval> +specifies access to a particular value of a single attribute. +In this case, only a single attribute type may be given. The +.B <attrstyle> +.B exact +(the default) uses the attribute's equality matching rule to compare the +value, unless a different (and compatible) matching rule is specified. If the +.B <attrstyle> +is +.BR regex , +the provided value is used as a POSIX (''extended'') regular +expression pattern. If the attribute has DN syntax, the +.B <attrstyle> +can be any of +.BR base , +.BR onelevel , +.B subtree +or +.BR children , +resulting in base, onelevel, subtree or children match, respectively. +.LP +The dn, filter, and attrs statements are additive; they can be used in sequence +to select entities the access rule applies to based on naming context, +value and attribute type simultaneously. +Submatches resulting from +.B regex +matching can be dereferenced in the +.B <who> +field using the syntax +.IR ${v<n>} , +where +.I <n> +is the submatch number. +The default syntax, +.IR $<n> , +is actually an alias for +.IR ${d<n>} , +that corresponds to dereferencing submatches from the +.B dnpattern +portion of the +.B <what> +field. +.SH THE <WHO> FIELD +The field +.B <who> +indicates whom the access rules apply to. +Multiple +.B <who> +statements can appear in an access control statement, indicating the +different access privileges to the same resource that apply to different +accessee. +It can have the forms +.LP +.nf + * + anonymous + users + self[.<selfstyle>] + + dn[.<dnstyle>[,<modifier>]]=<DN> + dnattr=<attrname> + + realanonymous + realusers + realself[.<selfstyle>] + + realdn[.<dnstyle>[,<modifier>]]=<DN> + realdnattr=<attrname> + + group[/<objectclass>[/<attrname>]] + [.<groupstyle>]=<group> + peername[.<peernamestyle>]=<peername> + sockname[.<style>]=<sockname> + domain[.<domainstyle>[,<modifier>]]=<domain> + sockurl[.<style>]=<sockurl> + set[.<setstyle>]=<pattern> + + ssf=<n> + transport_ssf=<n> + tls_ssf=<n> + sasl_ssf=<n> + + dynacl/<name>[/<options>][.<dynstyle>][=<pattern>] +.fi +.LP +with +.LP +.nf + <style>={exact|regex|expand} + <selfstyle>={level{<n>}} + <dnstyle>={{exact|base(object)}|regex + |one(level)|sub(tree)|children|level{<n>}} + <groupstyle>={exact|expand} + <peernamestyle>={<style>|ip|ipv6|path} + <domainstyle>={exact|regex|sub(tree)} + <setstyle>={exact|expand} + <modifier>={expand} + <name>=aci <pattern>=<attrname>] +.fi +.LP +They may be specified in combination. +.LP +.nf +.fi +.LP +The wildcard +.B * +refers to everybody. +.LP +The keywords prefixed by +.B real +act as their counterparts without prefix; the checking respectively occurs +with the \fIauthentication\fP DN and the \fIauthorization\fP DN. +.LP +The keyword +.B anonymous +means access is granted to unauthenticated clients; it is mostly used +to limit access to authentication resources (e.g. the +.B userPassword +attribute) to unauthenticated clients for authentication purposes. +.LP +The keyword +.B users +means access is granted to authenticated clients. +.LP +The keyword +.B self +means access to an entry is allowed to the entry itself (e.g. the entry +being accessed and the requesting entry must be the same). +It allows the +.B level{<n>} +style, where \fI<n>\fP indicates what ancestor of the DN +is to be used in matches. +A positive value indicates that the <n>-th ancestor of the user's DN +is to be considered; a negative value indicates that the <n>-th ancestor +of the target is to be considered. +For example, a "\fIby self.level{1} ...\fP" clause would match +when the object "\fIdc=example,dc=com\fP" is accessed +by "\fIcn=User,dc=example,dc=com\fP". +A "\fIby self.level{-1} ...\fP" clause would match when the same user +accesses the object "\fIou=Address Book,cn=User,dc=example,dc=com\fP". +.LP +The statement +.B dn=<DN> +means that access is granted to the matching DN. +The optional style qualifier +.B dnstyle +allows the same choices of the dn form of the +.B <what> +field. In addition, the +.B regex +style can exploit substring substitution of submatches in the +.B <what> +dn.regex clause by using the form +.BR $<digit> , +with +.B digit +ranging from 0 to 9 (where 0 matches the entire string), +or the form +.BR ${<digit>+} , +for submatches higher than 9. +Substring substitution from attribute value can +be done in +using the form +.BR ${v<digit>+} . +Since the dollar character is used to indicate a substring replacement, +the dollar character that is used to indicate match up to the end of +the string must be escaped by a second dollar character, e.g. +.LP +.nf + access to dn.regex="^(.+,)?uid=([^,]+),dc=[^,]+,dc=com$" + by dn.regex="^uid=$2,dc=[^,]+,dc=com$$" write +.fi +.LP +The style qualifier +allows an optional +.BR modifier . +At present, the only type allowed is +.BR expand , +which causes substring substitution of submatches to take place +even if +.B dnstyle +is not +.BR regex . +Note that the +.B regex +dnstyle in the above example may be of use only if the +.B <by> +clause needs to be a regex; otherwise, if the +value of the second (from the right) +.B dc= +portion of the DN in the above example were fixed, the form +.LP +.nf + access to dn.regex="^(.+,)?uid=([^,]+),dc=example,dc=com$" + by dn.exact,expand="uid=$2,dc=example,dc=com" write +.fi +.LP +could be used; if it had to match the value in the +.B <what> +clause, the form +.LP +.nf + access to dn.regex="^(.+,)?uid=([^,]+),dc=([^,]+),dc=com$" + by dn.exact,expand="uid=$2,dc=$3,dc=com" write +.fi +.LP +could be used. +.LP +Forms of the +.B <what> +clause other than regex may provide submatches as well. +The +.BR base(object) , +the +.BR sub(tree) , +the +.BR one(level) , +and the +.BR children +forms provide +.B $0 +as the match of the entire string. +The +.BR sub(tree) , +the +.BR one(level) , +and the +.BR children +forms also provide +.B $1 +as the match of the rightmost part of the DN as defined in the +.B <what> +clause. +This may be useful, for instance, to provide access to all the +ancestors of a user by defining +.LP +.nf + access to dn.subtree="dc=com" + by dn.subtree,expand="$1" read +.fi +.LP +which means that only access to entries that appear in the DN of the +.B <by> +clause is allowed. +.LP +The +.BR level{<n>} +form is an extension and a generalization of the +.BR onelevel +form, which matches all DNs whose <n>-th ancestor is the pattern. +So, \fIlevel{1}\fP is equivalent to \fIonelevel\fP, +and \fIlevel{0}\fP is equivalent to \fIbase\fP. +.LP +It is perfectly useless to give any access privileges to a DN +that exactly matches the +.B rootdn +of the database the ACLs apply to, because it implicitly +possesses write privileges for the entire tree of that database. +Actually, access control is bypassed for the +.BR rootdn , +to solve the intrinsic chicken-and-egg problem. +.LP +The statement +.B dnattr=<attrname> +means that access is granted to requests whose DN is listed in the +entry being accessed under the +.B <attrname> +attribute. +.LP +The statement +.B group=<group> +means that access is granted to requests whose DN is listed +in the group entry whose DN is given by +.BR <group> . +The optional parameters +.B <objectclass> +and +.B <attrname> +define the objectClass and the member attributeType of the group entry. +The defaults are +.B groupOfNames +and +.BR member , +respectively. +The optional style qualifier +.B <style> +can be +.BR expand , +which means that +.B <group> +will be expanded as a replacement string (but not as a regular expression) +according to +.BR regex (7) +and/or +.BR re_format (7), +and +.BR exact , +which means that exact match will be used. +If the style of the DN portion of the +.B <what> +clause is regex, the submatches are made available according to +.BR regex (7) +and/or +.BR re_format (7); +other styles provide limited submatches as discussed above about +the DN form of the +.B <by> +clause. +.LP +For static groups, the specified attributeType must have +.B DistinguishedName +or +.B NameAndOptionalUID +syntax. For dynamic groups the attributeType must +be a subtype of the +.B labeledURI +attributeType. Only LDAP URIs of the form +.B ldap:///<base>??<scope>?<filter> +will be evaluated in a dynamic group, by searching the local server only. +.LP +The statements +.BR peername=<peername> , +.BR sockname=<sockname> , +.BR domain=<domain> , +and +.BR sockurl=<sockurl> +mean that the contacting host IP (in the form +.BR "IP=<ip>:<port>" +for IPv4, or +.BR "IP=[<ipv6>]:<port>" +for IPv6) +or the contacting host named pipe file name (in the form +.B "PATH=<path>" +if connecting through a named pipe) for +.BR peername , +the named pipe file name for +.BR sockname , +the contacting host name for +.BR domain , +and the contacting URL for +.BR sockurl +are compared against +.B pattern +to determine access. +The same +.B style +rules for pattern match described for the +.B group +case apply, plus the +.B regex +style, which implies submatch +.B expand +and regex match of the corresponding connection parameters. +The +.B exact +style of the +.BR <peername> +clause (the default) implies a case-exact match on the client's +.BR IP , +including the +.B "IP=" +prefix and the trailing +.BR ":<port>" , +or the client's +.BR path , +including the +.B "PATH=" +prefix if connecting through a named pipe. +The special +.B ip +style interprets the pattern as +.BR <peername>=<ip>[%<mask>][{<n>}] , +where +.B <ip> +and +.B <mask> +are dotted digit representations of the IP and the mask, while +.BR <n> , +delimited by curly brackets, is an optional port. +The same applies to IPv6 addresses when the special +.B ipv6 +style is used. +When checking access privileges, the IP portion of the +.BR peername +is extracted, eliminating the +.B "IP=" +prefix and the +.B ":<port>" +part, and it is compared against the +.B <ip> +portion of the pattern after masking with +.BR <mask> : +\fI((peername & <mask>) == <ip>)\fP. +As an example, +.B peername.ip=127.0.0.1 +and +.B peername.ipv6=::1 +allow connections only from localhost, +.B peername.ip=192.168.1.0%255.255.255.0 +allows connections from any IP in the 192.168.1 class C domain, and +.B peername.ip=192.168.1.16%255.255.255.240{9009} +allows connections from any IP in the 192.168.1.[16-31] range +of the same domain, only if port 9009 is used. +The special +.B path +style eliminates the +.B "PATH=" +prefix from the +.B peername +when connecting through a named pipe, and performs an exact match +on the given pattern. +The +.BR <domain> +clause also allows the +.B subtree +style, which succeeds when a fully qualified name exactly matches the +.BR domain +pattern, or its trailing part, after a +.BR dot , +exactly matches the +.BR domain +pattern. +The +.B expand +style is allowed, implying an +.B exact +match with submatch expansion; the use of +.B expand +as a style modifier is considered more appropriate. +As an example, +.B domain.subtree=example.com +will match www.example.com, but will not match www.anotherexample.com. +The +.B domain +of the contacting host is determined by performing a DNS reverse lookup. +As this lookup can easily be spoofed, use of the +.B domain +statement is strongly discouraged. By default, reverse lookups are disabled. +The optional +.B domainstyle +qualifier of the +.B <domain> +clause allows a +.B modifier +option; the only value currently supported is +.BR expand , +which causes substring substitution of submatches to take place even if +the +.B domainstyle +is not +.BR regex , +much like the analogous usage in +.B <dn> +clause. +.LP +The statement +.B set=<pattern> +is undocumented yet. +.LP +The statement +.B dynacl/<name>[/<options>][.<dynstyle>][=<pattern>] +means that access checking is delegated to the admin-defined method +indicated by +.BR <name> , +which can be registered at run-time by means of the +.B moduleload +statement. +The fields +.BR <options> , +.B <dynstyle> +and +.B <pattern> +are optional, and are directly passed to the registered parsing routine. +Dynacl is experimental; it must be enabled at compile time. +.LP +The statement +.B dynacl/aci[=<attrname>] +means that the access control is determined by the values in the +.B attrname +of the entry itself. +The optional +.B <attrname> +indicates what attributeType holds the ACI information in the entry. +By default, the +.B OpenLDAPaci +operational attribute is used. +ACIs are experimental; they must be enabled at compile time. +.LP +The statements +.BR ssf=<n> , +.BR transport_ssf=<n> , +.BR tls_ssf=<n> , +and +.BR sasl_ssf=<n> +set the minimum required Security Strength Factor (ssf) needed +to grant access. The value should be positive integer. +.SH THE <ACCESS> FIELD +The optional field +.B <access> ::= [[real]self]{<level>|<priv>} +determines the access level or the specific access privileges the +.B who +field will have. +Its component are defined as +.LP +.nf + <level> ::= none|disclose|auth|compare|search|read|{write|add|delete}|manage + <priv> ::= {=|+|\-}{0|d|x|c|s|r|{w|a|z}|m}+ +.fi +.LP +The modifier +.B self +allows special operations like having a certain access level or privilege +only in case the operation involves the name of the user that's requesting +the access. +It implies the user that requests access is authorized. +The modifier +.B realself +refers to the authenticated DN as opposed to the authorized DN of the +.B self +modifier. +An example is the +.B selfwrite +access to the member attribute of a group, which allows one to add/delete +its own DN from the member list of a group, while being not allowed +to affect other members. +.LP +The +.B level +access model relies on an incremental interpretation of the access +privileges. +The possible levels are +.BR none , +.BR disclose , +.BR auth , +.BR compare , +.BR search , +.BR read , +.BR write , +and +.BR manage . +Each access level implies all the preceding ones, thus +.B manage +grants all access including administrative access. +The +.BR write +access is actually the combination of +.BR add +and +.BR delete , +which respectively restrict the write privilege to add or delete +the specified +.BR <what> . + +.LP +The +.B none +access level disallows all access including disclosure on error. +.LP +The +.B disclose +access level allows disclosure of information on error. +.LP +The +.B auth +access level means that one is allowed access to an attribute to perform +authentication/authorization operations (e.g. +.BR bind ) +with no other access. +This is useful to grant unauthenticated clients the least possible +access level to critical resources, like passwords. +.LP +The +.B priv +access model relies on the explicit setting of access privileges +for each clause. +The +.B = +sign resets previously defined accesses; as a consequence, the final +access privileges will be only those defined by the clause. +The +.B + +and +.B \- +signs add/remove access privileges to the existing ones. +The privileges are +.B m +for manage, +.B w +for write, +.B a +for add, +.B z +for delete, +.B r +for read, +.B s +for search, +.B c +for compare, +.B x +for authentication, and +.B d +for disclose. +More than one of the above privileges can be added in one statement. +.B 0 +indicates no privileges and is used only by itself (e.g., +0). +Note that +.B +az +is equivalent to +.BR +w . +.LP +If no access is given, it defaults to +.BR +0 . +.SH THE <CONTROL> FIELD +The optional field +.B <control> +controls the flow of access rule application. +It can have the forms +.LP +.nf + stop + continue + break +.fi +.LP +where +.BR stop , +the default, means access checking stops in case of match. +The other two forms are used to keep on processing access clauses. +In detail, the +.B continue +form allows for other +.B <who> +clauses in the same +.B <access> +clause to be considered, so that they may result in incrementally altering +the privileges, while the +.B break +form allows for other +.B <access> +clauses that match the same target to be processed. +Consider the (silly) example +.LP +.nf + access to dn.subtree="dc=example,dc=com" attrs=cn + by * =cs break + + access to dn.subtree="ou=People,dc=example,dc=com" + by * +r +.fi +.LP +which allows search and compare privileges to everybody under +the "dc=example,dc=com" tree, with the second rule allowing +also read in the "ou=People" subtree, +or the (even more silly) example +.LP +.nf + access to dn.subtree="dc=example,dc=com" attrs=cn + by * =cs continue + by users +r +.fi +.LP +which grants everybody search and compare privileges, and adds read +privileges to authenticated clients. +.LP +One useful application is to easily grant write privileges to an +.B updatedn +that is different from the +.BR rootdn . +In this case, since the +.B updatedn +needs write access to (almost) all data, one can use +.LP +.nf + access to * + by dn.exact="cn=The Update DN,dc=example,dc=com" write + by * break +.fi +.LP +as the first access rule. +As a consequence, unless the operation is performed with the +.B updatedn +identity, control is passed straight to the subsequent rules. + +.SH OPERATION REQUIREMENTS +Operations require different privileges on different portions of entries. +The following summary applies to primary MDB database backend and the +deprecated BDB and HDB backends. Requirements for other backends may +(and often do) differ. + +.LP +The +.B add +operation requires +.B add (=a) +privileges on the pseudo-attribute +.B entry +of the entry being added, and +.B add (=a) +privileges on the pseudo-attribute +.B children +of the entry's parent. +When adding the suffix entry of a database, +.B add +access to +.B children +of the empty DN ("") is required. Also if +Add content ACL checking has been configured on +the database (see the +.BR slapd.conf (5) +or +.BR slapd\-config (5) +manual page), +.B add (=a) +will be required on all of the attributes being added. + +.LP +The +.B bind +operation, when credentials are stored in the directory, requires +.B auth (=x) +privileges on the attribute the credentials are stored in (usually +.BR userPassword ). + +.LP +The +.B compare +operation requires +.B compare (=c) +privileges on the attribute that is being compared. + +.LP +The +.B delete +operation requires +.B delete (=z) +privileges on the pseudo-attribute +.B entry +of the entry being deleted, and +.B delete (=d) +privileges on the +.B children +pseudo-attribute of the entry's parent. + +.LP +The +.B modify +operation requires +.B write (=w) +privileges on the attributes being modified. +In detail, +.B add (=a) +is required to add new values, +.B delete (=z) +is required to delete existing values, +and both +.B delete +and +.BR "add (=az)" , +or +.BR "write (=w)" , +are required to replace existing values. + +.LP +The +.B modrdn +operation requires +.B write (=w) +privileges on the pseudo-attribute +.B entry +of the entry whose relative DN is being modified, +.B delete (=z) +privileges on the pseudo-attribute +.B children +of the old entry's parents, +.B add (=a) +privileges on the pseudo-attribute +.B children +of the new entry's parents, and +.B add (=a) +privileges on the attributes that are present in the new relative DN. +.B Delete (=z) +privileges are also required on the attributes that are present +in the old relative DN if +.B deleteoldrdn +is set to 1. + +.LP +The +.B search +operation, requires +.B search (=s) +privileges on the +.B entry +pseudo-attribute of the searchBase +(NOTE: this was introduced with OpenLDAP 2.4). +Then, for each entry, it requires +.B search (=s) +privileges on the attributes that are defined in the filter. +The resulting entries are finally tested for +.B read (=r) +privileges on the pseudo-attribute +.B entry +(for read access to the entry itself) +and for +.B read (=r) +access on each value of each attribute that is requested. +Also, for each +.B referral +object used in generating continuation references, the operation requires +.B read (=r) +access on the pseudo-attribute +.B entry +(for read access to the referral object itself), +as well as +.B read (=r) +access to the attribute holding the referral information +(generally the +.B ref +attribute). + +.LP +Some internal operations and some +.B controls +require specific access privileges. +The +.B authzID +mapping and the +.B proxyAuthz +control require +.B auth (=x) +privileges on all the attributes that are present in the search filter +of the URI regexp maps (the right-hand side of the +.B authz-regexp +directives). +.B Auth (=x) +privileges are also required on the +.B authzTo +attribute of the authorizing identity and/or on the +.B authzFrom +attribute of the authorized identity. +In general, when an internal lookup is performed for authentication +or authorization purposes, search-specific privileges (see the access +requirements for the search operation illustrated above) are relaxed to +.BR auth . + +.LP +Access control to search entries is checked by the frontend, +so it is fully honored by all backends; for all other operations +and for the discovery phase of the search operation, +full ACL semantics is only supported by the primary backends, i.e. +.BR back\-bdb (5), +and +.BR back\-hdb (5). + +Some other backend, like +.BR back\-sql (5), +may fully support them; others may only support a portion of the +described semantics, or even differ in some aspects. +The relevant details are described in the backend-specific man pages. + +.SH CAVEATS +It is strongly recommended to explicitly use the most appropriate +.B <dnstyle> +in +.B <what> +and +.B <who> +clauses, to avoid possible incorrect specifications of the access rules +as well as for performance (avoid unnecessary regex matching when an exact +match suffices) reasons. +.LP +An administrator might create a rule of the form: +.LP +.nf + access to dn.regex="dc=example,dc=com" + by ... +.fi +.LP +expecting it to match all entries in the subtree "dc=example,dc=com". +However, this rule actually matches any DN which contains anywhere +the substring "dc=example,dc=com". That is, the rule matches both +"uid=joe,dc=example,dc=com" and "dc=example,dc=com,uid=joe". +.LP +To match the desired subtree, the rule would be more precisely +written: +.LP +.nf + access to dn.regex="^(.+,)?dc=example,dc=com$" + by ... +.fi +.LP +For performance reasons, it would be better to use the subtree style. +.LP +.nf + access to dn.subtree="dc=example,dc=com" + by ... +.fi +.LP +When writing submatch rules, it may be convenient to avoid unnecessary +.B regex +.B <dnstyle> +use; for instance, to allow access to the subtree of the user +that matches the +.B <what> +clause, one could use +.LP +.nf + access to dn.regex="^(.+,)?uid=([^,]+),dc=example,dc=com$" + by dn.regex="^uid=$2,dc=example,dc=com$$" write + by ... +.fi +.LP +However, since all that is required in the +.B <by> +clause is substring expansion, a more efficient solution is +.LP +.nf + access to dn.regex="^(.+,)?uid=([^,]+),dc=example,dc=com$" + by dn.exact,expand="uid=$2,dc=example,dc=com" write + by ... +.fi +.LP +In fact, while a +.B <dnstyle> +of +.B regex +implies substring expansion, +.BR exact , +as well as all the other DN specific +.B <dnstyle> +values, does not, so it must be explicitly requested. +.LP +.SH FILES +.TP +ETCDIR/slapd.conf +default slapd configuration file +.SH SEE ALSO +.BR slapd (8), +.BR slapd\-* (5), +.BR slapacl (8), +.BR regex (7), +.BR re_format (7) +.LP +"OpenLDAP Administrator's Guide" (http://www.OpenLDAP.org/doc/admin/) +.SH ACKNOWLEDGEMENTS +.so ../Project |