Attribute Value Filters
While each policy defines what principal attributes may be allowed for a given service, there are optional attribute filters that can be set per policy to further weed out attributes based on their values.
Chaining Filters
Attribute filters can be chained together so as to associate multiple filters with a single service definition.
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{
"@class" : "org.apereo.cas.services.CasRegisteredService",
"serviceId" : "sample",
"name" : "sample",
"id" : 200,
"description" : "sample",
"attributeReleasePolicy" : {
"@class" : "org.apereo.cas.services.ReturnAllowedAttributeReleasePolicy",
"attributeFilter" : {
"@class" : "org.apereo.cas.services.support.RegisteredServiceChainingAttributeFilter",
"filters": [ "java.util.ArrayList",
[
{
"@class" : "org.apereo.cas.services.support.RegisteredServiceRegexAttributeFilter",
"pattern" : "^\\w{3}$",
"order": 10
},
{
"@class" : "..."
}
]
]
},
"allowedAttributes" : [ "java.util.ArrayList", [ "uid", "groupMembership" ] ]
}
}
Chained attribute filters are sorted given their order
property first before execution.
Regex
The regex filter that is responsible to make sure only attributes whose value matches a certain regex pattern are released.
Suppose that the following attributes are resolved:
Name | Value |
---|---|
uid |
jsmith |
groupMembership |
std |
cn |
JohnSmith |
The following configuration for instance considers the initial list of uid
,
groupMembership
and then only allows and releases attributes whose value’s length
is 3 characters. Therefore, out of the above list, only groupMembership
is released to the application.
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{
"@class" : "org.apereo.cas.services.CasRegisteredService",
"serviceId" : "sample",
"name" : "sample",
"id" : 200,
"description" : "sample",
"attributeReleasePolicy" : {
"@class" : "org.apereo.cas.services.ReturnAllowedAttributeReleasePolicy",
"attributeFilter" : {
"@class" : "org.apereo.cas.services.support.RegisteredServiceRegexAttributeFilter",
"pattern" : "^\\w{3}$"
},
"allowedAttributes" : [ "java.util.ArrayList", [ "uid", "groupMembership" ] ]
}
}
Mapped Regex
The regex filter that is responsible to make sure only a selected set of attributes whose value matches a certain regex pattern are released. The filter selectively applies patterns to attributes mapped in the configuration. If an attribute is mapped, it is only allowed to be released if it matches the linked pattern. If an attribute is not mapped, it may optionally be excluded from the released set of attributes.
For example, the below example only allows release of memberOf
if it contains a value that is 3 characters in length. If no values are found, the memberOf
is excluded from the final released bundle.
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{
"@class" : "org.apereo.cas.services.CasRegisteredService",
"serviceId" : "sample",
"name" : "sample",
"id" : 200,
"description" : "sample",
"attributeReleasePolicy" : {
"@class" : "org.apereo.cas.services.ReturnAllowedAttributeReleasePolicy",
"attributeFilter" : {
"@class": "org.apereo.cas.services.support.RegisteredServiceMappedRegexAttributeFilter",
"patterns": {
"@class" : "java.util.TreeMap",
"memberOf": "^\\w{3}$"
},
"excludeUnmappedAttributes": false,
"completeMatch": false,
"caseInsensitive": true,
"order": 0
},
"allowedAttributes" : [ "java.util.ArrayList", [ "uid", "memberOf" ] ]
}
}
The following fields are supported by this filter:
Name | Description |
---|---|
patterns |
A map of attributes and their associated pattern tried against value(s). |
completeMatch |
Indicates whether pattern-matching should execute over the entire value region. |
excludeUnmappedAttributes |
Indicates whether unmapped attributes should be removed from the final bundle. |
caseInsensitive |
Indicates whether pattern matching should be done in a case-insensitive manner. |
Reverse Mapped Regex
Identical to the Mapped Regex filter, except that the filter only allows a selected set of attributes whose value does not match a certain regex pattern are released.
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{
"@class" : "org.apereo.cas.services.CasRegisteredService",
"serviceId" : "sample",
"name" : "sample",
"id" : 200,
"description" : "sample",
"attributeReleasePolicy" : {
"@class" : "org.apereo.cas.services.ReturnAllowedAttributeReleasePolicy",
"attributeFilter" : {
"@class": "org.apereo.cas.services.support.RegisteredServiceReverseMappedRegexAttributeFilter",
"patterns": {
"memberOf": "^\\w{3}$"
},
"excludeUnmappedAttributes": false,
"completeMatch": false,
"caseInsensitive": true,
"order": 0
},
"allowedAttributes" : [ "java.util.ArrayList", [ "uid", "memberOf" ] ]
}
}
Mutant Mapped Regex
This filter structurally, in terms of settings and properties, is identical to the Mapped Regex filter. Its main ability is to filter attribute values by a collection of patterns and then supplant the value dynamically based on the results of the regex match.
For example, the following definition attempts to filter all values assigned to the attribute memberOf
based on the given patterns. Each pattern is linked via ->
to the expected return value that may reference specific groups in the produced regex result. Assuming the attribute memberOf
has values of math101
and marathon101
, the filter will produce values courseA-athon101
and courseB-h101
after processing.
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{
"@class" : "org.apereo.cas.services.CasRegisteredService",
"serviceId" : "sample",
"name" : "sample",
"id" : 200,
"description" : "sample",
"attributeReleasePolicy" : {
"@class" : "org.apereo.cas.services.ReturnAllowedAttributeReleasePolicy",
"attributeFilter" : {
"@class": "org.apereo.cas.services.support.RegisteredServiceMutantRegexAttributeFilter",
"patterns": {
"@class" : "java.util.TreeMap",
"memberOf": [ "java.util.ArrayList", [ "^mar(.+)(101) -> courseA-$1$2", "^mat(.+)(101) -> courseB-$1$2" ] ]
},
"excludeUnmappedAttributes": false,
"completeMatch": false,
"caseInsensitive": true,
"order": 0
},
"allowedAttributes" : [ "java.util.ArrayList", [ "uid", "memberOf" ] ]
}
}
Groovy
Attribute value filtering may also be carried out using an inline or external Groovy script.
Scripts have access to the current resolved attributes via attributes
and a logger
.
The returned result of the script must be a Map<String, Object>
.
Inlined Groovy
An inline groovy filter allows you to embed the script directly in the service definition.
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{
"@class" : "org.apereo.cas.services.CasRegisteredService",
"serviceId" : "sample",
"name" : "sample",
"id" : 200,
"description" : "sample",
"attributeReleasePolicy" : {
"@class" : "org.apereo.cas.services.ReturnAllowedAttributeReleasePolicy",
"attributeFilter" : {
"@class" : "org.apereo.cas.services.support.RegisteredServiceScriptedAttributeFilter",
"script" : "groovy { return attributes }"
},
"allowedAttributes" : [ "java.util.ArrayList", [ "uid", "groupMembership" ] ]
}
}
External Groovy
An external groovy filter allows you to define the script in file located outside of the CAS web application.
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{
"@class" : "org.apereo.cas.services.CasRegisteredService",
"serviceId" : "sample",
"name" : "sample",
"id" : 200,
"description" : "sample",
"attributeReleasePolicy" : {
"@class" : "org.apereo.cas.services.ReturnAllowedAttributeReleasePolicy",
"attributeFilter" : {
"@class" : "org.apereo.cas.services.support.RegisteredServiceScriptedAttributeFilter",
"script" : "file:/etc/cas/filter-this.groovy"
},
"allowedAttributes" : [ "java.util.ArrayList", [ "uid", "groupMembership" ] ]
}
}
The outline of the script may be as follows:
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import java.util.*
def run(final Object... args) {
def attributes = args[0]
def logger = args[1]
logger.info "Attributes currently resolved: ${attributes}"
def map =...
return map
}
The parameters passed are as follows:
Parameter | Description |
---|---|
attributes |
A Map of current attributes resolved from sources. |
logger |
The object responsible for issuing log messages such as logger.info(...) . |