1 .TH SLAPO-RWM 5 "RELEASEDATE" "OpenLDAP LDVERSION"
2 .\" Copyright 1998-2004 The OpenLDAP Foundation, All Rights Reserved.
3 .\" Copying restrictions apply. See the COPYRIGHT file.
4 .\" Copyright 2004, Pierangelo Masarati, All rights reserved. <ando@sys-net.it>
7 .\" Portions of this document should probably be moved to slapd-ldap(5)
8 .\" and maybe manual pages for librewrite.
11 slapo-rwm \- rewrite/remap overlay
19 performs basic DN/data rewrite and objectClass/attributeType mapping.
20 Its usage is mostly intended to provide virtual views of existing data
21 either remotely, in conjunction with the proxy backend described in
23 or locally, in conjunction with the relay backend described in
26 An important feature of the
28 overlay is the capability to map objectClasses and attributeTypes
29 from the local set (or a subset of it) to a foreign set, and vice versa.
30 This is accomplished by means of the
34 .B rwm-map "{attribute | objectclass} [<local name> | *] {<foreign name> | *}"
35 Map attributeTypes and objectClasses from the foreign server to
36 different values on the local slapd.
37 The reason is that some attributes might not be part of the local
38 slapd's schema, some attribute names might be different but serve the
40 If local or foreign name is `*', the name is preserved.
41 If local name is omitted, the foreign name is removed.
42 Unmapped names are preseved if both local and foreign name are `*',
43 and removed if local name is omitted and foreign name is `*'.
49 must be defined in the local schema; the foreign ones do not have to.
50 Note, however, that the decision whether to rewrite or not attributeTypes
52 .IR "distinguishedName syntax" ,
53 requires the knowledge of the attributeType syntax.
54 See the REWRITING section for details.
56 Note that when mapping DN-valued attributes from local to remote,
57 first the DN is rewritten, and then the attributeType is mapped;
58 while mapping from remote to local, first the attributeType is mapped,
59 and then the DN is rewritten.
60 As such, it is important that the local attributeType is appropriately
61 defined as using the distinguishedName syntax.
62 Also, note that there are DN-related syntaxes, like nameAndOptionalUID,
63 whose values are currenlty not rewritten.
65 A basic feature of the
67 overlay is the capability to perform suffix massaging between a virtual
68 and a real naming context by means of the
72 .B rwm-suffixmassage "<virtual naming context>" "<real naming context>"
73 Shortcut to implement naming context rewriting; the trailing part
74 of the DN is rewritten from the virtual to the real naming context
75 in the bindDN, searchDN, searchFilterAttrDN, compareDN, compareAttrDN,
76 addDN, addAttrDN, modifyDN, modifyAttrDN, modrDN, newSuperiorDN,
77 deleteDN, exopPasswdDN, and from the real to the virtual naming context
78 in the searchEntryDN, searchAttrDN and matchedDN rewrite contexts.
79 By default no rewriting occurs for the searchFilter rewrite context.
80 This directive implies setting the
85 See the REWRITING section for details.
87 A string is rewritten according to a set of rules, called a `rewrite
89 The rules are based on Regular Expressions (POSIX regex) with
90 substring matching; basic variable substitution and map resolution
91 of substrings is allowed by specific mechanisms detailed in the following.
92 The behavior of pattern matching/substitution can be altered by a set
97 <rewrite context> ::= <rewrite rule> [...]
98 <rewrite rule> ::= <pattern> <action> [<flags>]
102 The underlying concept is to build a lightweight rewrite module
103 for the slapd server (initially dedicated to the LDAP backend):
106 An incoming string is matched agains a set of
109 .IR "regex match pattern" ,
111 .I "substitution pattern"
112 and a set of actions, described by a set of
113 .IR "optional flags" .
114 In case of match, string rewriting is performed according to the
115 substitution pattern that allows to refer to substrings matched in the
117 The actions, if any, are finally performed.
118 Each rule is executed recursively, unless altered by specific action
119 flags; see "Action Flags" for details.
120 A default limit on the recursion level is set, and can be altered
122 .B rwm-rewriteMaxPasses
123 directive, as detailed in the "Additional Configuration Syntax" section.
124 The substitution pattern allows map resolution of substrings.
125 A map is a generic object that maps a substitution pattern to a value.
126 The flags are divided in "Pattern Matching Flags" and "Action Flags";
127 the former alter the regex match pattern behavior, while the latter
128 alter the actions that are taken after substitution.
129 .SH "Pattern Matching Flags"
132 honors case in matching (default is case insensitive)
135 use POSIX Basic Regular Expressions (default is Extended)
140 recursive passes for a specific rule; does not alter the max total count
141 of passes, so it can only enforce a stricter limit for a specific rule.
145 apply the rule once only (default is recursive)
148 stop applying rules in case of match; the current rule is still applied
149 recursively; combine with `:' to apply the current rule only once
153 stop current operation if the rule matches, and issue an `unwilling to
159 rules back and forth (watch for loops!).
160 Note that `G{1}' is implicit in every rule.
163 ignores errors in rule; this means, in case of error, e.g. issued by a
164 map, the error is treated as a missed match.
165 The `unwilling to perform' is not overridden.
171 as return code if the rule matches; the flag does not alter the recursive
172 behavior of the rule, so, to have it performed only once, it must be used
173 in combination with `:', e.g.
175 returns the value `16' after exactly one execution of the rule, if the
177 As a consequence, its behavior is equivalent to `@', with the return
180 or, in other words, `@' is equivalent to `U{0}'.
181 By convention, the freely available codes are above 16 included;
182 the others are reserved.
184 The ordering of the flags can be significant.
185 For instance: `IG{2}' means ignore errors and jump two lines ahead
186 both in case of match and in case of error, while `G{2}I' means ignore
187 errors, but jump two lines ahead only in case of match.
189 More flags (mainly Action Flags) will be added as needed.
190 .SH "Pattern Matching"
193 .SH "Substitution Pattern Syntax"
194 Everything starting with `$' requires substitution;
196 the only obvious exception is `$$', which is left as is;
198 the basic substitution is `$<d>', where `<d>' is a digit;
199 0 means the whole string, while 1-9 is a submatch, as discussed in
202 a `$' followed by a `{' invokes an advanced substitution.
206 `$' `{' [ <operator> ] <name> `(' <substitution> `)' `}'
209 where <name> must be a legal name for the map, i.e.
213 <name> ::= [a-z][a-z0-9]* (case insensitive)
214 <operator> ::= `>' `|' `&' `&&' `*' `**' `$'
218 and <substitution> must be a legal substitution
219 pattern, with no limits on the nesting level.
224 sub-context invocation; <name> must be a legal, already defined
228 external command invocation; <name> must refer to a legal, already
229 defined command name (NOT IMPLEMENTED YET)
232 variable assignment; <name> defines a variable in the running
233 operation structure which can be dereferenced later; operator
235 assigns a variable in the rewrite context scope; operator
237 assigns a variable that scopes the entire session, e.g. its value
238 can be derefenced later by other rewrite contexts
241 variable dereferencing; <name> must refer to a variable that is
242 defined and assigned for the running operation; operator
244 dereferences a variable scoping the rewrite context; operator
246 dereferences a variable scoping the whole session, e.g. the value
247 is passed across rewrite contexts
250 parameter dereferencing; <name> must refer to an existing parameter;
251 the idea is to make some run-time parameters set by the system
252 available to the rewrite engine, as the client host name, the bind DN
253 if any, constant parameters initialized at config time, and so on;
254 no parameter is currently set by either
258 but constant parameters can be defined in the configuration file
263 Substitution escaping has been delegated to the `$' symbol,
264 which is used instead of `\e' in string substitution patterns
265 because `\e' is already escaped by slapd's low level parsing routines;
268 escaping requires two `\e' symbols, e.g. `\fB.*\e.foo\e.bar\fP' must
269 be written as `\fB.*\e\e.foo\e\e.bar\fP'.
271 .\" The symbol can be altered at will by redefining the related macro in
274 .SH "Rewrite Context"
275 A rewrite context is a set of rules which are applied in sequence.
276 The basic idea is to have an application initialize a rewrite
277 engine (think of Apache's mod_rewrite ...) with a set of rewrite
278 contexts; when string rewriting is required, one invokes the
279 appropriate rewrite context with the input string and obtains the
280 newly rewritten one if no errors occur.
282 Each basic server operation is associated to a rewrite context;
283 they are divided in two main groups: client \-> server and
284 server \-> client rewriting.
290 (default) if defined and no specific context
295 searchFilterAttrDN search
297 compareAttrDN compare AVA
299 addAttrDN add AVA (including "ref")
301 modifyAttrDN modify AVA (including "ref")
305 exopPasswdDN passwd exop DN
313 searchEntryDN search (only if defined; no default;
314 acts on DN of search entries)
315 searchAttrDN search AVA (only if defined; defaults
316 to searchEntryDN; acts on DN-syntax
317 attributes of search results)
318 matchedDN all ops (only if applicable; defaults
320 referralDN all ops (only if applicable; defaults
325 .SH "Basic Configuration Syntax"
326 All rewrite/remap directives start with the prefix
328 for backwards compatibility with the historical
332 builtin rewrite/remap capabilities, the prefix may be omitted,
333 but this practice is strongly discouraged.
335 .B rwm-rewriteEngine { on | off }
336 If `on', the requested rewriting is performed; if `off', no
337 rewriting takes place (an easy way to stop rewriting without
338 altering too much the configuration file).
340 .B rwm-rewriteContext <context name> "[ alias <aliased context name> ]"
341 <Context name> is the name that identifies the context, i.e. the name
342 used by the application to refer to the set of rules it contains.
343 It is used also to reference sub contexts in string rewriting.
344 A context may aliase another one.
345 In this case the alias context contains no rule, and any reference to
346 it will result in accessing the aliased one.
348 .B rwm-rewriteRule "<regex match pattern>" "<substitution pattern>" "[ <flags> ]"
349 Determines how a string can be rewritten if a pattern is matched.
350 Examples are reported below.
351 .SH "Additional Configuration Syntax"
353 .B rwm-rewriteMap "<map type>" "<map name>" "[ <map attrs> ]"
354 Allows to define a map that transforms substring rewriting into
356 The map is referenced inside the substitution pattern of a rule.
358 .B rwm-rewriteParam <param name> <param value>
359 Sets a value with global scope, that can be dereferenced by the
360 command `${$paramName}'.
362 .B rwm-rewriteMaxPasses <number of passes> [<number of passes per rule>]
363 Sets the maximum number of total rewriting passes that can be
364 performed in a single rewrite operation (to avoid loops).
365 A safe default is set to 100; note that reaching this limit is still
366 treated as a success; recursive invocation of rules is simply
368 The count applies to the rewriting operation as a whole, not
369 to any single rule; an optional per-rule limit can be set.
370 This limit is overridden by setting specific per-rule limits
371 with the `M{n}' flag.
372 .SH "Configuration Examples"
374 # set to `off' to disable rewriting
377 # the rules the "suffixmassage" directive implies
379 # all dataflow from client to server referring to DNs
380 rwm-rewriteContext default
381 rwm-rewriteRule "(.*)<virtualnamingcontext>$" "$1<realnamingcontext>" ":"
383 rwm-rewriteContext searchFilter
384 # all dataflow from server to client
385 rwm-rewriteContext searchEntryDN
386 rwm-rewriteRule "(.*)<realnamingcontext>$" "$1<virtualnamingcontext>" ":"
387 rwm-rewriteContext searchAttrDN alias searchEntryDN
388 rwm-rewriteContext matchedDN alias searchEntryDN
390 # Everything defined here goes into the `default' context.
391 # This rule changes the naming context of anything sent
392 # to `dc=home,dc=net' to `dc=OpenLDAP, dc=org'
394 rwm-rewriteRule "(.*)dc=home,[ ]?dc=net$"
395 "$1dc=OpenLDAP, dc=org" ":"
397 # since a pretty/normalized DN does not include spaces
398 # after rdn separators, e.g. `,', this rule suffices:
400 rwm-rewriteRule "(.*)dc=home,dc=net$"
401 "$1dc=OpenLDAP,dc=org" ":"
403 # Start a new context (ends input of the previous one).
404 # This rule adds blanks between DN parts if not present.
405 rwm-rewriteContext addBlanks
406 rwm-rewriteRule "(.*),([^ ].*)" "$1, $2"
408 # This one eats blanks
409 rwm-rewriteContext eatBlanks
410 rwm-rewriteRule "(.*), (.*)" "$1,$2"
412 # Here control goes back to the default rewrite
413 # context; rules are appended to the existing ones.
414 # anything that gets here is piped into rule `addBlanks'
415 rwm-rewriteContext default
416 rwm-rewriteRule ".*" "${>addBlanks($0)}" ":"
418 .\" # Anything with `uid=username' is looked up in
419 .\" # /etc/passwd for gecos (I know it's nearly useless,
420 .\" # but it is there just as a guideline to implementing
422 .\" # Note the `I' flag that leaves `uid=username' in place
423 .\" # if `username' does not have a valid account, and the
424 .\" # `:' that forces the rule to be processed exactly once.
425 .\" rwm-rewriteContext uid2Gecos
426 .\" rwm-rewriteRule "(.*)uid=([a-z0-9]+),(.+)"
427 .\" "$1cn=$2{xpasswd},$3" "I:"
429 .\" # Finally, in a bind, if one uses a `uid=username' DN,
430 .\" # it is rewritten in `cn=name surname' if possible.
431 .\" rwm-rewriteContext bindDN
432 .\" rwm-rewriteRule ".*" "${>addBlanks(${>uid2Gecos($0)})}" ":"
434 # Rewrite the search base according to `default' rules.
435 rwm-rewriteContext searchDN alias default
437 # Search results with OpenLDAP DN are rewritten back with
438 # `dc=home,dc=net' naming context, with spaces eaten.
439 rwm-rewriteContext searchEntryDN
440 rwm-rewriteRule "(.*[^ ],)?[ ]?dc=OpenLDAP,[ ]?dc=org$"
441 "${>eatBlanks($1)}dc=home,dc=net" ":"
443 # Bind with email instead of full DN: we first need
444 # an ldap map that turns attributes into a DN (the
445 # argument used when invoking the map is appended to
446 # the URI and acts as the filter portion)
447 rwm-rewriteMap ldap attr2dn "ldap://host/dc=my,dc=org?dn?sub"
449 # Then we need to detect DN made up of a single email,
450 # e.g. `mail=someone@example.com'; note that the rule
451 # in case of match stops rewriting; in case of error,
452 # it is ignored. In case we are mapping virtual
453 # to real naming contexts, we also need to rewrite
454 # regular DNs, because the definition of a bindDN
455 # rewrite context overrides the default definition.
456 rwm-rewriteContext bindDN
457 rwm-rewriteRule "^mail=[^,]+@[^,]+$" "${attr2dn($0)}" ":@I"
459 # This is a rather sophisticated example. It massages a
460 # search filter in case who performs the search has
461 # administrative privileges. First we need to keep
462 # track of the bind DN of the incoming request, which is
463 # stored in a variable called `binddn' with session scope,
464 # and left in place to allow regular binding:
465 rwm-rewriteContext bindDN
466 rwm-rewriteRule ".+" "${&&binddn($0)}$0" ":"
468 # A search filter containing `uid=' is rewritten only
469 # if an appropriate DN is bound.
470 # To do this, in the first rule the bound DN is
471 # dereferenced, while the filter is decomposed in a
472 # prefix, in the value of the `uid=<arg>' AVA, and
473 # in a suffix. A tag `<>' is appended to the DN.
474 # If the DN refers to an entry in the `ou=admin' subtree,
475 # the filter is rewritten OR-ing the `uid=<arg>' with
476 # `cn=<arg>'; otherwise it is left as is. This could be
477 # useful, for instance, to allow apache's auth_ldap-1.4
478 # module to authenticate users with both `uid' and
479 # `cn', but only if the request comes from a possible
480 # `cn=Web auth,ou=admin,dc=home,dc=net' user.
481 rwm-rewriteContext searchFilter
482 rwm-rewriteRule "(.*\e\e()uid=([a-z0-9_]+)(\e\e).*)"
483 "${**binddn}<>${&prefix($1)}${&arg($2)}${&suffix($3)}"
485 rwm-rewriteRule "^[^,]+,ou=admin,dc=home,dc=net$"
486 "${*prefix}|(uid=${*arg})(cn=${*arg})${*suffix}" ":@I"
487 rwm-rewriteRule ".*<>$" "${*prefix}uid=${*arg}${*suffix}" ":"
489 # This example shows how to strip unwanted DN-valued
490 # attribute values from a search result; the first rule
491 # matches DN values below "ou=People,dc=example,dc=com";
492 # in case of match the rewriting exits successfully.
493 # The second rule matches everything else and causes
494 # the value to be rejected.
495 rwm-rewriteContext searchEntryDN
496 rwm-rewriteRule ".+,ou=People,dc=example,dc=com$" "$0" ":@"
497 rwm-rewriteRule ".*" "" "#"
502 default slapd configuration file
507 .BR slapd\-relay (5),
511 Pierangelo Masarati; based on back-ldap rewrite/remap features
512 by Howard Chu, Pierangelo Masarati.
projects / openldap / blob