Manual Pages for UNIX Darwin command on man slapo-rwm

SLAPO-RWM(5) SLAPO-RWM(5)

NAME

slapo-rwm - rewrite/remap overlay

SYNOPSIS

/etc/openldap/slapd.conf

DESCRIPTION

The rrwwmm overlay to ssllaappdd(8) performs basic DN/data rewrite and object-

Class/attributeType mapping. Its usage is mostly intended to provide virtual views of existing data either remotely, in conjunction with the

proxy backend described in ssllaappdd-llddaapp(5), or locally, in conjunction

with the relay backend described in ssllaappdd-rreellaayy(5).

This overlay is experimental. MMAAPPPPIINNGG An important feature of the rrwwmm overlay is the capability to map objectClasses and attributeTypes from the local set (or a subset of it) to a foreign set, and vice versa. This is accomplished by means of the

rrwwmm-mmaapp directive.

rrwwmm-mmaapp {{aattttrriibbuuttee || oobbjjeeccttccllaassss}} [[<> || **]] {{<> ||

**}} Map attributeTypes and objectClasses from the foreign server to different values on the local slapd. The reason is that some attributes might not be part of the local slapd's schema, some attribute names might be different but serve the same purpose, etc. If local or foreign name is `*', the name is preserved. If local name is omitted, the foreign name is removed. Unmapped names are preserved if both local and foreign name are `*', and removed if local name is omitted and foreign name is `*'. The local objectClasses and attributeTypes must be defined in the local schema; the foreign ones do not have to, but users are encouraged to explicitly define the remote attributeTypes and the objectClasses they

intend to map. All in all, when remapping a remote server via back-

ldap (ssllaappdd-llddaapp(5)) or back-meta (ssllaappdd-mmeettaa(5)) their definition can

be easily obtained by querying the subschemaSubentry of the remote server; the problem should not exist when remapping a local database.

Note, however, that the decision whether to rewrite or not attribute-

Types with distinguishedName syntax, requires the knowledge of the attributeType syntax. See the REWRITING section for details.

Note that when mapping DN-valued attributes from local to remote, first

the DN is rewritten, and then the attributeType is mapped; while map-

ping from remote to local, first the attributeType is mapped, and then the DN is rewritten. As such, it is important that the local attributeType is appropriately defined as using the distinguishedName

syntax. Also, note that there are DN-related syntaxes (i.e. compound

types with a portion that is DN-valued), like nameAndOptionalUID, whose

values are currently not rewritten. SSUUFFFFIIXX MMAASSSSAAGGIINNGG A basic feature of the rrwwmm overlay is the capability to perform suffix massaging between a virtual and a real naming context by means of the

rrwwmm-ssuuffffiixxmmaassssaaggee directive.

rrwwmm-ssuuffffiixxmmaassssaaggee [[<>]] <>

Shortcut to implement naming context rewriting; the trailing part of the DN is rewritten from the virtual to the real naming context in the bindDN, searchDN, searchFilterAttrDN, compareDN, compareAttrDN, addDN, addAttrDN, modifyDN, modifyAttrDN, modrDN, newSuperiorDN, deleteDN, exopPasswdDN, and from the real to the virtual naming context in the searchEntryDN, searchAttrDN and matchedDN rewrite contexts. By default no rewriting occurs for

the searchFilter and for the referralAttrDN and referralDN re-

write contexts. If no is given, the

first suffix of the database is used; this requires the rrwwmm-ssuuff-

ffiixxmmaassssaaggee directive be defined after the database ssuuffffiixx direc-

tive. The rrwwmm-ssuuffffiixxmmaassssaaggee directive automatically sets the

rrwwmm-rreewwrriitteeEEnnggiinnee to OONN.

See the REWRITING section for details. RREEWWRRIITTIINNGG A string is rewritten according to a set of rules, called a `rewrite

context'. The rules are based on POSIX (''extended'') regular expres-

sions with substring matching; basic variable substitution and map res-

olution of substrings is allowed by specific mechanisms detailed in the following. The behavior of pattern matching/substitution can be altered by a set of flags. ::= [...] ::= [] The underlying concept is to build a lightweight rewrite module for the slapd server (initially dedicated to the LDAP backend): PPaasssseess An incoming string is matched against a set of rewriteRules. Rules are made of a regex match pattern, a substitution pattern and a set of actions, described by a set of optional flags. In case of match, string rewriting is performed according to the substitution pattern that allows to refer to substrings matched in the incoming string. The

actions, if any, are finally performed. Each rule is executed recur-

sively, unless altered by specific action flags; see "Action Flags" for details. A default limit on the recursion level is set, and can be

altered by the rrwwmm-rreewwrriitteeMMaaxxPPaasssseess directive, as detailed in the

"Additional Configuration Syntax" section. The substitution pattern allows map resolution of substrings. A map is a generic object that

maps a substitution pattern to a value. The flags are divided in "Pat-

tern Matching Flags" and "Action Flags"; the former alter the regex match pattern behavior, while the latter alter the actions that are taken after substitution. PPaatttteerrnn MMaattcchhiinngg FFllaaggss ``CC'' honors case in matching (default is case insensitive) ``RR'' use POSIX ''basic'' regular expressions (default is ''extended'') ``MM{{nn}}'' allow no more than nn recursive passes for a specific rule; does not alter the max total count of passes, so it can only enforce a stricter limit for a specific rule. AAccttiioonn FFllaaggss ``::'' apply the rule once only (default is recursive) ``@@'' stop applying rules in case of match; the current rule is still applied recursively; combine with `:' to apply the current rule only once and then stop.

``##'' stop current operation if the rule matches, and issue an

`unwilling to perform' error. ``GG{{nn}}'' jump nn rules back and forth (watch for loops!). Note that `G{1}' is implicit in every rule. ``II'' ignores errors in rule; this means, in case of error, e.g. issued by a map, the error is treated as a missed match. The `unwilling to perform' is not overridden. ``UU{{nn}}'' uses nn as return code if the rule matches; the flag does not

alter the recursive behavior of the rule, so, to have it per-

formed only once, it must be used in combination with `:', e.g. ``::UU{{3322}}'' returns the value `32' (indicating noSuchObject) after exactly one execution of the rule, if the pattern matches. As a consequence, its behavior is equivalent to `@', with the return code set to nn; or, in other words, `@' is equivalent to `U{0}'. Positive errors are allowed, indicating the related LDAP error

codes as specified in draft-ietf-ldapbis-protocol.

The ordering of the flags can be significant. For instance: `IG{2}' means ignore errors and jump two lines ahead both in case of match and in case of error, while `G{2}I' means ignore errors, but jump two lines ahead only in case of match. More flags (mainly Action Flags) will be added as needed. PPaatttteerrnn MMaattcchhiinngg See rreeggeexx(7) and/or rreeffoorrmmaatt(7). SSuubbssttiittuuttiioonn PPaatttteerrnn SSyynnttaaxx

Everything starting with `$' requires substitution;

the only obvious exception is `$$', which is turned into a single `$';

the basic substitution is `$', where `' is a digit; 0 means the

whole string, while 1-9 is a submatch, as discussed in rreeggeexx(7) and/or

rreeffoorrmmaatt(7).

a `$' followed by a `{' invokes an advanced substitution. The pattern

is:

`$' `{' [ ] `(' `)' `}'

where must be a legal name for the map, i.e.

::= [a-z][a-z0-9]* (case insensitive)

::= `>' `|' `&' `&&' `*' `**' `$'

and must be a legal substitution pattern, with no limits on the nesting level. The operators are:

>> sub-context invocation; must be a legal, already defined

rewrite context name || external command invocation; must refer to a legal, already defined command name (NOT IMPLEMENTED YET) && variable assignment; defines a variable in the running operation structure which can be dereferenced later; operator && assigns a variable in the rewrite context scope; operator &&&& assigns a variable that scopes the entire session, e.g. its value can be dereferenced later by other rewrite contexts ** variable dereferencing; must refer to a variable that is defined and assigned for the running operation; operator ** dereferences a variable scoping the rewrite context; operator **** dereferences a variable scoping the whole session, e.g. the value is passed across rewrite contexts

$$ parameter dereferencing; must refer to an existing param-

eter; the idea is to make some run-time parameters set by the

system available to the rewrite engine, as the client host name, the bind DN if any, constant parameters initialized at config time, and so on; no parameter is currently set by either

bbaacckk-llddaapp or bbaacckk-mmeettaa, but constant parameters can be defined

in the configuration file by using the rreewwrriitteePPaarraamm directive.

Substitution escaping has been delegated to the `$' symbol, which is

used instead of `\' in string substitution patterns because `\' is

already escaped by slapd's low level parsing routines; as a conse-

quence, regex escaping requires two `\' symbols, e.g. `..**\\..ffoooo\\..bbaarr' must be written as `..**\\\\..ffoooo\\\\..bbaarr'. RReewwrriittee CCoonntteexxtt A rewrite context is a set of rules which are applied in sequence. The basic idea is to have an application initialize a rewrite engine (think of Apache's modrewrite ...) with a set of rewrite contexts; when

string rewriting is required, one invokes the appropriate rewrite con-

text with the input string and obtains the newly rewritten one if no errors occur. Each basic server operation is associated to a rewrite context; they

are divided in two main groups: client -> server and server -> client

rewriting.

client -> server:

(default) if defined and no specific context is available bindDN bind searchDN search searchFilter search searchFilterAttrDN search compareDN compare compareAttrDN compare AVA addDN add addAttrDN add AVA (DN portion of "ref" excluded) modifyDN modify modifyAttrDN modify AVA (DN portion of "ref" excluded) referralAttrDN add/modify DN portion of referrals (default to none) modrDN modrdn newSuperiorDN modrdn deleteDN delete exopPasswdDN password modify extended operation DN

server -> client:

searchEntryDN search (only if defined; no default; acts on DN of search entries) searchAttrDN search AVA (only if defined; defaults

to searchEntryDN; acts on DN-syntax

attributes of search results) matchedDN all ops (only if applicable; defaults to searchEntryDN) referralDN all ops (only if applicable; defaults to none) BBaassiicc CCoonnffiigguurraattiioonn SSyynnttaaxx

All rewrite/remap directives start with the prefix rrwwmm-; for backwards

compatibility with the historical ssllaappdd-llddaapp(5) and ssllaappdd-mmeettaa(5)

builtin rewrite/remap capabilities, the prefix may be omitted, but this practice is strongly discouraged.

rrwwmm-rreewwrriitteeEEnnggiinnee {{ oonn || ooffff }}

If `on', the requested rewriting is performed; if `off', no rewriting takes place (an easy way to stop rewriting without altering too much the configuration file).

rrwwmm-rreewwrriitteeCCoonntteexxtt <> [[ aalliiaass <> ]]

is the name that identifies the context, i.e. the name used by the application to refer to the set of rules it contains. It is used also to reference sub contexts in string rewriting. A context may alias another one. In this case the alias context contains no rule, and any reference to it will result in accessing the aliased one.

rrwwmm-rreewwrriitteeRRuullee <> <> [[ <>

]] Determines how a string can be rewritten if a pattern is matched. Examples are reported below. AAddddiittiioonnaall CCoonnffiigguurraattiioonn SSyynnttaaxx

rrwwmm-rreewwrriitteeMMaapp <> <> [[ <> ]]

Allows to define a map that transforms substring rewriting into something else. The map is referenced inside the substitution pattern of a rule.

rrwwmm-rreewwrriitteePPaarraamm <> <>

Sets a value with global scope, that can be dereferenced by the

command `${$paramName}'.

rrwwmm-rreewwrriitteeMMaaxxPPaasssseess <> [[<>]]

Sets the maximum number of total rewriting passes that can be performed in a single rewrite operation (to avoid loops). A safe default is set to 100; note that reaching this limit is still treated as a success; recursive invocation of rules is

simply interrupted. The count applies to the rewriting opera-

tion as a whole, not to any single rule; an optional per-rule

limit can be set. This limit is overridden by setting specific

per-rule limits with the `M{n}' flag.

RREEWWRRIITTEE CCOONNFFIIGGUURRAATTIIOONN EEXXAAMMPPLLEESS

# set to `off' to disable rewriting

rwm-rewriteEngine on

# the rules the "suffixmassage" directive implies

rwm-rewriteEngine on

# all dataflow from client to server referring to DNs

rwm-rewriteContext default

rwm-rewriteRule "(.+,)?$" "$1" ":"

# empty filter rule

rwm-rewriteContext searchFilter

# all dataflow from server to client

rwm-rewriteContext searchEntryDN

rwm-rewriteRule "(.+,)?$" "$1" ":"

rwm-rewriteContext searchAttrDN alias searchEntryDN

rwm-rewriteContext matchedDN alias searchEntryDN

# misc empty rules

rwm-rewriteContext referralAttrDN

rwm-rewriteContext referralDN

# Everything defined here goes into the `default' context.

# This rule changes the naming context of anything sent

# to `dc=home,dc=net' to `dc=OpenLDAP, dc=org'

rwm-rewriteRule "(.+,)?dc=home,[ ]?dc=net$"

"$1dc=OpenLDAP, dc=org" ":"

# since a pretty/normalized DN does not include spaces

# after rdn separators, e.g. `,', this rule suffices:

rwm-rewriteRule "(.+,)?dc=home,dc=net$"

"$1dc=OpenLDAP,dc=org" ":"

# Start a new context (ends input of the previous one).

# This rule adds blanks between DN parts if not present.

rwm-rewriteContext addBlanks

rwm-rewriteRule "(.*),([^ ].*)" "$1, $2"

# This one eats blanks

rwm-rewriteContext eatBlanks

rwm-rewriteRule "(.*), (.*)" "$1,$2"

# Here control goes back to the default rewrite

# context; rules are appended to the existing ones.

# anything that gets here is piped into rule `addBlanks'

rwm-rewriteContext default

rwm-rewriteRule ".*" "${>addBlanks($0)}" ":"

# Rewrite the search base according to `default' rules.

rwm-rewriteContext searchDN alias default

# Search results with OpenLDAP DN are rewritten back with

# `dc=home,dc=net' naming context, with spaces eaten.

rwm-rewriteContext searchEntryDN

rwm-rewriteRule "(.*[^ ],)?[ ]?dc=OpenLDAP,[ ]?dc=org$"

"${>eatBlanks($1)}dc=home,dc=net" ":"

# Bind with email instead of full DN: we first need

# an ldap map that turns attributes into a DN (the

# argument used when invoking the map is appended to

# the URI and acts as the filter portion)

rwm-rewriteMap ldap attr2dn "ldap://host/dc=my,dc=org?dn?sub"

# Then we need to detect DN made up of a single email,

# e.g. `mail=someone@example.com'; note that the rule

# in case of match stops rewriting; in case of error,

# it is ignored. In case we are mapping virtual

# to real naming contexts, we also need to rewrite

# regular DNs, because the definition of a bindDN

# rewrite context overrides the default definition.

rwm-rewriteContext bindDN

rwm-rewriteRule "^mail=[^,]+@[^,]+$" "${attr2dn($0)}" ":@I"

# This is a rather sophisticated example. It massages a

# search filter in case who performs the search has

# administrative privileges. First we need to keep

# track of the bind DN of the incoming request, which is

# stored in a variable called `binddn' with session scope,

# and left in place to allow regular binding:

rwm-rewriteContext bindDN

rwm-rewriteRule ".+" "${&&binddn($0)}$0" ":"

# A search filter containing `uid=' is rewritten only

# if an appropriate DN is bound.

# To do this, in the first rule the bound DN is

# dereferenced, while the filter is decomposed in a

# prefix, in the value of the `uid=' AVA, and

# in a suffix. A tag `<>' is appended to the DN.

# If the DN refers to an entry in the `ou=admin' subtree,

# the filter is rewritten OR-ing the `uid=' with

# `cn='; otherwise it is left as is. This could be

# useful, for instance, to allow apache's authldap-1.4

# module to authenticate users with both `uid' and

# `cn', but only if the request comes from a possible

# `cn=Web auth,ou=admin,dc=home,dc=net' user.

rwm-rewriteContext searchFilter

rwm-rewriteRule "(.*\$)uid=([a-z0-9]+)(\$.*)"

"${**binddn}<>${&prefix($1)}${&arg($2)}${&suffix($3)}"

":I"

rwm-rewriteRule "^[^,]+,ou=admin,dc=home,dc=net$"

"${*prefix}|(uid=${*arg})(cn=${*arg})${*suffix}" ":@I"

rwm-rewriteRule ".*<>$" "${*prefix}uid=${*arg}${*suffix}" ":"

# This example shows how to strip unwanted DN-valued

# attribute values from a search result; the first rule

# matches DN values below "ou=People,dc=example,dc=com";

# in case of match the rewriting exits successfully.

# The second rule matches everything else and causes

# the value to be rejected.

rwm-rewriteContext searchEntryDN

rwm-rewriteRule ".+,ou=People,dc=example,dc=com$" "$0" ":@"

rwm-rewriteRule ".*" "" "#"

MMAAPPPPIINNGG EEXXAAMMPPLLEESS The following directives map the object class `groupOfNames' to the object class `groupOfUniqueNames' and the attribute type `member' to the attribute type `uniqueMember': map objectclass groupOfNames groupOfUniqueNames map attribute uniqueMember member This presents a limited attribute set from the foreign server: map attribute cn * map attribute sn * map attribute manager * map attribute description * map attribute * These lines map cn, sn, manager, and description to themselves, and any other attribute gets "removed" from the object before it is sent to the client (or sent up to the LDAP server). This is obviously a simplistic example, but you get the point. FILES /etc/openldap/slapd.conf default slapd configuration file