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 A basic feature of the
58 overlay is the capability to perform suffix massaging between a virtual
59 and a real naming context by means of the
63 .B rwm-suffixmassage "<virtual naming context>" "<real naming context>"
64 Shortcut to implement naming context rewriting; the trailing part
65 of the DN is rewritten from the virtual to the real naming context
66 in the bindDN, searchBase, searchFilterAttrDN, compareDN, compareAttrDN,
67 addDN, addAttrDN, modifyDN, modifyAttrDN, modrDN, newSuperiorDN,
68 deleteDN, exopPasswdDN, and from the real to the virtual naming context
69 in the searchResult, searchAttrDN and matchedDN rewrite contexts.
70 By default no rewriting occurs for the searchFilter rewrite context.
71 This directive implies setting the
76 See the REWRITING section for details.
78 A string is rewritten according to a set of rules, called a `rewrite
80 The rules are based on Regular Expressions (POSIX regex) with
81 substring matching; basic variable substitution and map resolution
82 of substrings is allowed by specific mechanisms detailed in the following.
83 The behavior of pattern matching/substitution can be altered by a set
88 <rewrite context> ::= <rewrite rule> [...]
89 <rewrite rule> ::= <pattern> <action> [<flags>]
93 The underlying concept is to build a lightweight rewrite module
94 for the slapd server (initially dedicated to the LDAP backend):
97 An incoming string is matched agains a set of
100 .IR "regex match pattern" ,
102 .I "substitution pattern"
103 and a set of actions, described by a set of
104 .IR "optional flags" .
105 In case of match, string rewriting is performed according to the
106 substitution pattern that allows to refer to substrings matched in the
108 The actions, if any, are finally performed.
109 Each rule is executed recursively, unless altered by specific action
110 flags; see "Action Flags" for details.
111 A default limit on the recursion level is set, and can be altered
113 .B rwm-rewriteMaxPasses
114 directive, as detailed in the "Additional Configuration Syntax" section.
115 The substitution pattern allows map resolution of substrings.
116 A map is a generic object that maps a substitution pattern to a value.
117 The flags are divided in "Pattern Matching Flags" and "Action Flags";
118 the former alter the regex match pattern behavior, while the latter
119 alter the actions that are taken after substitution.
120 .SH "Pattern Matching Flags"
123 honors case in matching (default is case insensitive)
126 use POSIX Basic Regular Expressions (default is Extended)
131 recursive passes for a specific rule; does not alter the max total count
132 of passes, so it can only enforce a stricter limit for a specific rule.
136 apply the rule once only (default is recursive)
139 stop applying rules in case of match; the current rule is still applied
140 recursively; combine with `:' to apply the current rule only once
144 stop current operation if the rule matches, and issue an `unwilling to
150 rules back and forth (watch for loops!).
151 Note that `G{1}' is implicit in every rule.
154 ignores errors in rule; this means, in case of error, e.g. issued by a
155 map, the error is treated as a missed match.
156 The `unwilling to perform' is not overridden.
162 as return code if the rule matches; the flag does not alter the recursive
163 behavior of the rule, so, to have it performed only once, it must be used
164 in combination with `:', e.g.
166 returns the value `16' after exactly one execution of the rule, if the
168 As a consequence, its behavior is equivalent to `@', with the return
171 or, in other words, `@' is equivalent to `U{0}'.
172 By convention, the freely available codes are above 16 included;
173 the others are reserved.
175 The ordering of the flags can be significant.
176 For instance: `IG{2}' means ignore errors and jump two lines ahead
177 both in case of match and in case of error, while `G{2}I' means ignore
178 errors, but jump two lines ahead only in case of match.
180 More flags (mainly Action Flags) will be added as needed.
181 .SH "Pattern Matching"
184 .SH "Substitution Pattern Syntax"
185 Everything starting with `$' requires substitution;
187 the only obvious exception is `$$', which is left as is;
189 the basic substitution is `$<d>', where `<d>' is a digit;
190 0 means the whole string, while 1-9 is a submatch, as discussed in
193 a `$' followed by a `{' invokes an advanced substitution.
197 `$' `{' [ <operator> ] <name> `(' <substitution> `)' `}'
200 where <name> must be a legal name for the map, i.e.
204 <name> ::= [a-z][a-z0-9]* (case insensitive)
205 <operator> ::= `>' `|' `&' `&&' `*' `**' `$'
209 and <substitution> must be a legal substitution
210 pattern, with no limits on the nesting level.
215 sub-context invocation; <name> must be a legal, already defined
219 external command invocation; <name> must refer to a legal, already
220 defined command name (NOT IMPLEMENTED YET)
223 variable assignment; <name> defines a variable in the running
224 operation structure which can be dereferenced later; operator
226 assigns a variable in the rewrite context scope; operator
228 assigns a variable that scopes the entire session, e.g. its value
229 can be derefenced later by other rewrite contexts
232 variable dereferencing; <name> must refer to a variable that is
233 defined and assigned for the running operation; operator
235 dereferences a variable scoping the rewrite context; operator
237 dereferences a variable scoping the whole session, e.g. the value
238 is passed across rewrite contexts
241 parameter dereferencing; <name> must refer to an existing parameter;
242 the idea is to make some run-time parameters set by the system
243 available to the rewrite engine, as the client host name, the bind DN
244 if any, constant parameters initialized at config time, and so on;
245 no parameter is currently set by either
249 but constant parameters can be defined in the configuration file
254 Substitution escaping has been delegated to the `$' symbol,
255 which is used instead of `\e' in string substitution patterns
256 because `\e' is already escaped by slapd's low level parsing routines;
259 escaping requires two `\e' symbols, e.g. `\fB.*\e.foo\e.bar\fP' must
260 be written as `\fB.*\e\e.foo\e\e.bar\fP'.
262 .\" The symbol can be altered at will by redefining the related macro in
265 .SH "Rewrite Context"
266 A rewrite context is a set of rules which are applied in sequence.
267 The basic idea is to have an application initialize a rewrite
268 engine (think of Apache's mod_rewrite ...) with a set of rewrite
269 contexts; when string rewriting is required, one invokes the
270 appropriate rewrite context with the input string and obtains the
271 newly rewritten one if no errors occur.
273 Each basic server operation is associated to a rewrite context;
274 they are divided in two main groups: client \-> server and
275 server \-> client rewriting.
281 (default) if defined and no specific context
286 searchFilterAttrDN search
288 compareAttrDN compare AVA
292 modifyAttrDN modify AVA
296 exopPasswdDN passwd exop DN if proxy
304 searchResult search (only if defined; no default;
305 acts on DN and DN-syntax attributes
307 searchAttrDN search AVA
308 matchedDN all ops (only if applicable)
312 .SH "Basic Configuration Syntax"
313 All rewrite/remap directives start with the prefix
315 for backwards compatibility with the historical
319 builtin rewrite/remap capabilities, the prefix may be omitted,
320 but this practice is strongly discouraged.
322 .B rwm-rewriteEngine { on | off }
323 If `on', the requested rewriting is performed; if `off', no
324 rewriting takes place (an easy way to stop rewriting without
325 altering too much the configuration file).
327 .B rwm-rewriteContext <context name> "[ alias <aliased context name> ]"
328 <Context name> is the name that identifies the context, i.e. the name
329 used by the application to refer to the set of rules it contains.
330 It is used also to reference sub contexts in string rewriting.
331 A context may aliase another one.
332 In this case the alias context contains no rule, and any reference to
333 it will result in accessing the aliased one.
335 .B rwm-rewriteRule "<regex match pattern>" "<substitution pattern>" "[ <flags> ]"
336 Determines how a string can be rewritten if a pattern is matched.
337 Examples are reported below.
338 .SH "Additional Configuration Syntax"
340 .B rwm-rewriteMap "<map type>" "<map name>" "[ <map attrs> ]"
341 Allows to define a map that transforms substring rewriting into
343 The map is referenced inside the substitution pattern of a rule.
345 .B rwm-rewriteParam <param name> <param value>
346 Sets a value with global scope, that can be dereferenced by the
347 command `${$paramName}'.
349 .B rwm-rewriteMaxPasses <number of passes> [<number of passes per rule>]
350 Sets the maximum number of total rewriting passes that can be
351 performed in a single rewrite operation (to avoid loops).
352 A safe default is set to 100; note that reaching this limit is still
353 treated as a success; recursive invocation of rules is simply
355 The count applies to the rewriting operation as a whole, not
356 to any single rule; an optional per-rule limit can be set.
357 This limit is overridden by setting specific per-rule limits
358 with the `M{n}' flag.
359 .SH "Configuration Examples"
361 # set to `off' to disable rewriting
364 # the rules the "suffixmassage" directive implies
366 # all dataflow from client to server referring to DNs
367 rwm-rewriteContext default
368 rwm-rewriteRule "(.*)<virtualnamingcontext>$" "$1<realnamingcontext>" ":"
370 rwm-rewriteContext searchFilter
371 # all dataflow from server to client
372 rwm-rewriteContext searchResult
373 rwm-rewriteRule "(.*)<realnamingcontext>$" "$1<virtualnamingcontext>" ":"
374 rwm-rewriteContext searchAttrDN alias searchResult
375 rwm-rewriteContext matchedDN alias searchResult
377 # Everything defined here goes into the `default' context.
378 # This rule changes the naming context of anything sent
379 # to `dc=home,dc=net' to `dc=OpenLDAP, dc=org'
381 rwm-rewriteRule "(.*)dc=home,[ ]?dc=net$"
382 "$1dc=OpenLDAP, dc=org" ":"
384 # since a pretty/normalized DN does not include spaces
385 # after rdn separators, e.g. `,', this rule suffices:
387 rwm-rewriteRule "(.*)dc=home,dc=net$"
388 "$1dc=OpenLDAP,dc=org" ":"
390 # Start a new context (ends input of the previous one).
391 # This rule adds blanks between DN parts if not present.
392 rwm-rewriteContext addBlanks
393 rwm-rewriteRule "(.*),([^ ].*)" "$1, $2"
395 # This one eats blanks
396 rwm-rewriteContext eatBlanks
397 rwm-rewriteRule "(.*),[ ](.*)" "$1,$2"
399 # Here control goes back to the default rewrite
400 # context; rules are appended to the existing ones.
401 # anything that gets here is piped into rule `addBlanks'
402 rwm-rewriteContext default
403 rwm-rewriteRule ".*" "${>addBlanks($0)}" ":"
405 .\" # Anything with `uid=username' is looked up in
406 .\" # /etc/passwd for gecos (I know it's nearly useless,
407 .\" # but it is there just as a guideline to implementing
409 .\" # Note the `I' flag that leaves `uid=username' in place
410 .\" # if `username' does not have a valid account, and the
411 .\" # `:' that forces the rule to be processed exactly once.
412 .\" rwm-rewriteContext uid2Gecos
413 .\" rwm-rewriteRule "(.*)uid=([a-z0-9]+),(.+)"
414 .\" "$1cn=$2{xpasswd},$3" "I:"
416 .\" # Finally, in a bind, if one uses a `uid=username' DN,
417 .\" # it is rewritten in `cn=name surname' if possible.
418 .\" rwm-rewriteContext bindDN
419 .\" rwm-rewriteRule ".*" "${>addBlanks(${>uid2Gecos($0)})}" ":"
421 # Rewrite the search base according to `default' rules.
422 rwm-rewriteContext searchBase alias default
424 # Search results with OpenLDAP DN are rewritten back with
425 # `dc=home,dc=net' naming context, with spaces eaten.
426 rwm-rewriteContext searchResult
427 rwm-rewriteRule "(.*[^ ],)?[ ]?dc=OpenLDAP,[ ]?dc=org$"
428 "${>eatBlanks($1)}dc=home,dc=net" ":"
430 # Bind with email instead of full DN: we first need
431 # an ldap map that turns attributes into a DN (the
432 # argument used when invoking the map is appended to
433 # the URI and acts as the filter portion)
434 rwm-rewriteMap ldap attr2dn "ldap://host/dc=my,dc=org?dn?sub"
436 # Then we need to detect DN made up of a single email,
437 # e.g. `mail=someone@example.com'; note that the rule
438 # in case of match stops rewriting; in case of error,
439 # it is ignored. In case we are mapping virtual
440 # to real naming contexts, we also need to rewrite
441 # regular DNs, because the definition of a bindDn
442 # rewrite context overrides the default definition.
443 rwm-rewriteContext bindDN
444 rwm-rewriteRule "^mail=[^,]+@[^,]+$" "${attr2dn($0)}" ":@I"
446 # This is a rather sophisticated example. It massages a
447 # search filter in case who performs the search has
448 # administrative privileges. First we need to keep
449 # track of the bind DN of the incoming request, which is
450 # stored in a variable called `binddn' with session scope,
451 # and left in place to allow regular binding:
452 rwm-rewriteContext bindDN
453 rwm-rewriteRule ".+" "${&&binddn($0)}$0" ":"
455 # A search filter containing `uid=' is rewritten only
456 # if an appropriate DN is bound.
457 # To do this, in the first rule the bound DN is
458 # dereferenced, while the filter is decomposed in a
459 # prefix, in the value of the `uid=<arg>' AVA, and
460 # in a suffix. A tag `<>' is appended to the DN.
461 # If the DN refers to an entry in the `ou=admin' subtree,
462 # the filter is rewritten OR-ing the `uid=<arg>' with
463 # `cn=<arg>'; otherwise it is left as is. This could be
464 # useful, for instance, to allow apache's auth_ldap-1.4
465 # module to authenticate users with both `uid' and
466 # `cn', but only if the request comes from a possible
467 # `cn=Web auth,ou=admin,dc=home,dc=net' user.
468 rwm-rewriteContext searchFilter
469 rwm-rewriteRule "(.*\e\e()uid=([a-z0-9_]+)(\e\e).*)"
470 "${**binddn}<>${&prefix($1)}${&arg($2)}${&suffix($3)}"
472 rwm-rewriteRule "^[^,]+,ou=admin,dc=home,dc=net$"
473 "${*prefix}|(uid=${*arg})(cn=${*arg})${*suffix}" ":@I"
474 rwm-rewriteRule ".*<>$" "${*prefix}uid=${*arg}${*suffix}" ":"
476 # This example shows how to strip unwanted DN-valued
477 # attribute values from a search result; the first rule
478 # matches DN values below "ou=People,dc=example,dc=com";
479 # in case of match the rewriting exits successfully.
480 # The second rule matches everything else and causes
481 # the value to be rejected.
482 rwm-rewriteContext searchResult
483 rwm-rewriteRule ".*,ou=People,dc=example,dc=com$" "$0" ":@"
484 rwm-rewriteRule ".*" "" "#"
489 default slapd configuration file
494 .BR slapd\-relay (5),
498 Pierangelo Masarati; based on back-ldap rewrite/remap features
499 by Howard Chu, Pierangelo Masarati.
projects / openldap / blob